PDA

View Full Version : What is the very best way to get a positive image for PCB making these days?



idbruce
02-04-2012, 05:43 AM
Hello Everyone

I am looking for the best way to get a positive PCB image. I already know about laser printing and transparencies, as well as using vellum. Years ago, you could create camera ready artwork and take it to a print shop to have a positive made, but I believe this method is now outdated, because the print shops don't offer that service anymore. Any suggestions?

Bruce

idbruce
02-04-2012, 06:14 AM
After a little research, it appears that photoplotting with a photoplotter is the answer that I was looking for.

idbruce
02-04-2012, 06:38 AM
Does anyone know where to get some inexpensive photoplotting?

Phil Pilgrim (PhiPi)
02-04-2012, 06:50 AM
I don't know that anyone does photoplotting anymore. Print imaging is all direct-to-plate these days, without the need for intervening phototools. PCB fabs also use laser direct imaging. There may still be a handful of photoplotting houses serving niche markets, however; but most have gone the way of the dodo.

-Phil

Leon
02-04-2012, 09:16 AM
I get excellent results with a cheap HP inkjet printer and Mega Electronics JetStar Premium film.

jmg
03-29-2012, 09:30 AM
After a little research, it appears that photoplotting with a photoplotter is the answer that I was looking for.

You are half right: Actually using a Photo plotter (as in a Disk + Lamp + XY table) has not been done for a long time, but if you can find some print/imaging company that knows what Photoplotting is, and can import Gerber files onto their laser printer, then you are in luck.
Likely they have a laser imager at the better end of the scale.

Failing that, you may find a Silkscreen/print/imaging company that understands imaging Postscript onto film, but has no idea what a Gerber format is.
(Silkscreens still use the same photo-imaging they always have)

If you find one like that, (they are more common) just check the precision in the X and Y axes of their plots.
They may be used to lower levels of precision, and as long as the film distortions in their colour separation prints all track, usually their customers are happy.

A purist will print with the photo-emulsion on the film-side that will touch the photo-resist, but that can dictate a flip of one image.
On a low end printer, you may prefer the parallax issues, over image skew.

idbruce
03-29-2012, 12:21 PM
Actually there are still quite a few places that still offer laser photo plotting. A Google search with 'RS-274X' and 'Laser Photo' should return quite a handful of companies that still offer laser photo plotting.

@devil in angel - You may want to refer to some of my other posts that are all inter-related to the subject of making PCBs. In my opinion, they all contain some worthwhile knowledge for those wanting to create PCBs.

DVD Laser Diode And Optical Block (Future Laser Photoplotter)
http://forums.parallax.com/showthread.php?137850-DVD-Laser-Diode-And-Optical-Block-(Future-Laser-Photoplotter)

ATTN: PCBers SUBJECT: New website and exposure box design for your creative needs
http://forums.parallax.com/showthread.php?135950-ATTN-PCBers-SUBJECT-New-website-and-exposure-box-design-for-your-creative-needs

DIY PCB Fabrication For The Sake Of Science And Education
http://forums.parallax.com/showthread.php?138954-DIY-PCB-Fabrication-For-The-Sake-Of-Science-And-Education

Looking For Ideas - Temperature Control
http://forums.parallax.com/showthread.php?137511-Looking-For-Ideas-Temperature-Control

idbruce
03-29-2012, 12:28 PM
jmg

Alas my friend, you are half right also...



You are half right: Actually using a Photo plotter (as in a Disk + Lamp + XY table) has not been done for a long time, but if you can find some print/imaging company that knows what Photoplotting is, and can import Gerber files onto their laser printer, then you are in luck.
Likely they have a laser imager at the better end of the scale.


You are talking about the old method of photo plotting. They now use lasers to expose film. Perhaps you should also read the "DVD Laser Diode And Optical Block (Future Laser Photoplotter)" thread to gain a little more insight :)

Loopy Byteloose
03-29-2012, 12:53 PM
I have had good success with HP Inkjet printers and Eagle CAD software, but terrible results with Canon inkjet printers.

The Canon ink did not effectively stick to the transparency matter and wasn't opague enough for exposure, while the HP ink is both sticky and opague. But please be aware that the HP doesn't fully dry and can be smugged by rough handling.

Resolution with SMD may indeed be an issue with the use of inkjet printers - the images are getting tougher to produce.

Leon
03-29-2012, 12:57 PM
I used to use a Canon inkjet with Mega Electronics JetStar film. The results were quite good, but my current HP 5940 printer produces excellent transparencies (1200 dpi) when used with JetStar Premium film. I don't have any problems with the ink smudging.

I'm not sure if the 5940 is still available. Current low-cost Deskjets such as the 3000 give 4800x1200 dpi colour, but only 600 dpi for B&W, which isn't much use.

idbruce
03-29-2012, 01:03 PM
And since we are on the subject...

As many of you know, it is very difficult to obtain a high quality mask by simply printing your circuitry onto a transparent film with a laser printer. However, in the past, I have read about and watched several videos of people producing high quality boards by doubling up their transparencies and gluing them together to make a more opaque mask. Last night, I made several photo masks using this method, and I must say that I am quite pleased with the outcome. They appear to be some fairly nice masks and should produce some nice boards.

Basically I printed each mask twice onto a premium laser transparency film using a LaserJet 6L 600 DPI laser printer. After cutting all the masks to size, I sprayed each mask with Acrylic Krylon Crystal Clear Satin to blend and darken the toner from the printer. After allowing the masks to dry, I then aligned duplicate masks together and applied a very fine layer of Elmers Glue-All to the edges.

They look good to me and I am a pretty picky person.

Loopy Byteloose
03-29-2012, 01:10 PM
Some inkjet printers provided for direct printing of CDs for the purpose of labels. If the ink resists the FeCl, one can directly feed the blank circuit board into such a printer. I never considered trying to use my laser printer and laminating two transparencies into one, but the Fuji Xerox I have is no good for a single layer opacity on a transparency film.

Leon
03-29-2012, 01:14 PM
I used to manage OK with an old HP laser printer using LaserStar film, without doubling up.

idbruce
03-29-2012, 01:14 PM
@Loopy Byteloose

Just for giggles, give it a shot, but the key is to spray each mask with Clear Satin to blend and darken the toner. This will make the mask more opaque and it will help to protect the mask from smudging. The masks I made last night look pretty outstanding and very durable.

Loopy Byteloose
03-29-2012, 01:28 PM
I am pretty much staying with my HP laser printer and any transparency film as I have both on hand. I don't have any Clear Satin spray, but it does seem a workable solution.

I threw out a Canon printer and bought yet another HP about a year ago.

Leon
03-29-2012, 01:37 PM
The $100 6940 seems to be the replacement for my 5940, it'll do the same 1200x1200 dpi with black ink. If my 5940 dies on me, I'll get the 6940.

I can't see any point in using a laser printer.

idbruce
03-29-2012, 01:38 PM
I don't have any Clear Satin spray


Take my word for it, buy yourself a can and give it a shot. I think you will be highly impressed with the quality and durability. :)

idbruce
03-29-2012, 01:46 PM
I have not yet tried the double transparency method with my LaserJet 2200D, but somewhere in the near future, I will set the DPI to 1200 and the density level to 5, and give it a shot. I can only imagine what the results will look like.

While making the masks last night, I chose 600 DPI because I figured that was what most people had access to, and this is an experiment for my exposure box.

prof_braino
03-29-2012, 02:29 PM
Could you please post example pix of high quality results and unacceptable results? I'm new to this and don't know how good it has to be to work.
Thanks!

Loopy Byteloose
03-29-2012, 02:40 PM
There are two different factors that contribute to an unacceptible image - first is poor resolution; second in not opague enough for use with light sensitive copper circuit boards.

600dpi is likely good enough resolution for both. I doubt if I could post a visual example of poor opacity as the image looks excellent on printed paper.

idbruce
03-29-2012, 02:42 PM
@prof_braino

I do not believe that photos are capable of showing the desired quality. The main goal is for the artwork (circuitry) to be opaque as compared to translucent.

DEFS.

Translucent - Permitting the passage of light
Opaque - Blocking the passage of radiant energy and especially light

When holding a mask up to a light, black should remain black, instead of allowing light to seep through which would cause the black lines to appear grey. If you print out a transparency on a laser printer, it may appear black at a distance, but when it is up close, or close to a light, it will actually be grey because light is passing through.

Bruce

Leon
03-29-2012, 03:24 PM
When I worked for Xerox Research (UK) many years ago I did a lot of work on perceived copy quality, correlating it with physical measurements of density, MTF and edge-gradient. The physicists I worked with had a computer-controlled scanning micro-densitometer, using a sort of microscope with a photo-multiplier. That's the sort of equipment one really needs for the objective assessment of different techniques for making transparencies.

idbruce
03-29-2012, 03:28 PM
When I worked for Xerox Research (UK) many years ago I did a lot of work on perceived copy quality, correlating it with physical measurements of density, MTF and edge-gradient. The physicists I worked with had a computer-controlled scanning micro-densitometer, using a sort of microscope with a photo-multiplier. That's the sort of equipment one really needs for the objective assessment of different techniques for making transparencies.


Perhaps a bit of overkill for the DIY :)

Publison
03-29-2012, 04:09 PM
Anybody want a real Gerber Aperture Wheel to build an X-Y table, I have two. :)

Jim

idbruce
03-29-2012, 04:29 PM
Jim

I would imagine there is probably a person or two out there looking for one of those, and I imagine they would be pretty rare. If they were mine, I would try selling them on eBay.

As far as wanting one, sure I want one :) However, I do not know if I would ever do anything with it, considering that I will probably go the laser route and raster processing.

Bruce

Publison
03-29-2012, 04:45 PM
Jim

I would imagine there is probably a person or two out there looking for one of those, and I imagine they would be pretty rare. If they were mine, I would try selling them on eBay.

As far as wanting one, sure I want one :) However, I do not know if I would ever do anything with it, considering that I will probably go the laser route and raster processing.

Bruce

Yes, it was kinda a funny. Gerber knew where it was going, so they bought two companies back in 1988-1989? One did direct to film and the other did direct to plate. The rest is history.

Jim

prof_braino
03-29-2012, 04:46 PM
I do not believe that photos are capable of showing the desired quality. ...

When holding a mask up to a light, black should remain black, instead of allowing light to seep through which would cause the black lines to appear grey.

I'm looking for a yes/no answerable test. Your first statement doesn't get me there, and indicates there is no way to check if a solution is suitable.
But your next statement says there might be a method, and it might photograph-able.

(That's me, each requirement must have a yes/no test, or the requirement needs fixin') :)

Can you get (from your existing collection) an example of a good mask, and as you suggested hold it to the light and take a picture, and do the same with a bad mask?

I just want to see what good and bad look like, so I'll know it when I see it next.

If evaluation needs equipment that (sounds like it) cost more than my entire lab, I will probably drift off to another thread.

Leon
03-29-2012, 05:06 PM
It's impossible to predict by inspection how a given transparency will perform, the easiest way to find out is to make a board using it. My ink jet artwork doesn't look all that good under high magnification, but works very well - I can do 8/8 mil tracks without any problems.

Publison
03-29-2012, 05:15 PM
If evaluation needs equipment that (sounds like it) cost more than my entire lab, I will probably drift off to another thread.

Evaluation takes no more that a Calibrated Loupe (http://www.pcbsupplies.com/servlet/the-430/Measuring-Magnifier-15X-Scale/Detail) and a light table, (if I understand your question). When I was with Gerber, in field we would calibrate to .25-.5 mil. For a new machine, it would be calibrated to .1 mils before it shipped. Of course we used optical inspection equipment that was 50K at the time.

Jim

EDIT: of course I am referring to original artwork and not final PCB.

idbruce
03-29-2012, 05:55 PM
@prof_braino


Can you get (from your existing collection) an example of a good mask, and as you suggested hold it to the light and take a picture, and do the same with a bad mask?

For one, I do not have a good digital camera, and secondly, the last thing you want to do, is directly point a camera at a light source. When taking photographs, the normal procedure is to apply light from the side, from behind, or from above a camera. Avoiding direct lighting into the lense is always a good idea if you want nice photographs.

The bottom line is this... You can produce a decent circuit board without a perfectly opaque mask, but it is much more difficult. The darker the lines the better.

Just to give you a general idea, locate a board layout, and print out two copies on standard paper. Walk over to the nearest window with sunlight, and first place one copy on the window and look at how the light passes through the black. Then place the second copy over the first and you will see that very little light passes through the black.

Like I said earlier, I have seen several videos of doubling the transparencies, which have produced some very nice looking boards. And I imagine that I will have similar results. When I get finished exposing and etching the boards that I create with my new masks, I will then have photographs taken of the resulting boards.

Bruce

idbruce
03-29-2012, 06:11 PM
@prof_braino

If you are ever inclined to do so, you could always come by for another visit, and we will expose and etch a couple of boards just to give you a general and overall idea of the process. In fact, unless I achieve perfect results with the first attempts pertaining to the new masks, I will probably be experimenting with exposures for the next couple of days. During this time frame, it would be a good opportunity to learn what I have learned through trial and error.

Bruce

jmg
03-29-2012, 07:59 PM
jmg

Alas my friend, you are half right also...
You are talking about the old method of photo plotting. They now use lasers to expose film. Perhaps you should also read the "DVD Laser Diode And Optical Block (Future Laser Photoplotter)" thread to gain a little more insight :)

Err ? - I believe I already said that. It is now more widely called Dry Film imaging.

XY tables and classic photo-plotters for Gerber files, you will not find in commercial operation, which I thought was the line of your original question ?

idbruce
03-29-2012, 08:18 PM
jmg


which I thought was the line of your original question

:) Indeed. I have learned a lot in the last two months :)

idbruce
03-30-2012, 04:10 AM
Hello Everyone

Well it took quite some time to get motivated. However throughout the day, I did a little here and there to get everything ready for some serious testing. As a final step, I checked the fit of everything. When I attempted to fit the smaller photo mask to the exposure plate, the two layers of the photo mask seperated, because it was a fairly snug fit and it broke the glue seam apart. It definitely was not as durable as I initially thought. From this point, I will either crazy glue the seams together or fuse them together electronically somehow. Additionally, I am reevaluating a couple other minor problems, for potential solutions.

I will keep you posted on the photo masks.

Bruce

idbruce
03-30-2012, 01:59 PM
Hello Everyone

Refering to my last post, concerning the durability of the photo mask and the other minor problems that I was having, here is what I decided to do and what not to do.

Initially I considered trimming the photo masks with resistance wire, which would have permanently bonded the two layers of the photo mask together, but I came to the conclusion that most people would not bother with this method, and I am seeking a good solution for everyone. However, many of you who may be reading this, probably have a much different exposure system than me. Considering that I am also attempting a commercial venture, much of my solution will also coincide with my exposure box/cylinder system. If interested, you can find more information about that system here:
http://forums.parallax.com/showthread.php?135950-ATTN-PCBers-SUBJECT-New-website-and-exposure-box-design-for-your-creative-needs

For the most part, I was very happy with the double layered mask, with the exception of it coming apart at the seems. These masks had very nice registration alignment, and they were very close to being completely opaque. However, due to the tight tolerances of my exposure box system, the Elmers glue just did not hold up. To overcome this problem, I have decided upon two things:
I will be modifying the design of my exposure plate to readily adapt to a modified two layer mask, which is as follows.
Instead of making the masks to the exact size of the desired PCB, all masks will now be constructed to a size of 4" X 5". Along the outer perimeter of each mask, I will provide a series of registration marks, which will be spaced approximately 1/4" apart from each other.
So how does this help to solve the durability problem of a double layered mask? Read on to hear my proposed solution.

When I print my masks, I will also print the outer perimeter of the mask, which will allow each mask to easily be trimmed to the appropriate size. After trimming the masks to the appropriate size, I will then align the duplicate layers for each mask according to the forementioned registration marks. Once the duplicate masks have been properly aligned, I will then pierce each registration with a hot sewing needle or sharpened piece of metal rod, which should sufficiently bond the duplicate masks together. In reality, I will probably sharpen a piece of 1/8" metal rod and use this as compared to a sewing needle, just to obtain a better grip. Bonding the two layers together, probably shouldn't take more than a couple minutes. After bonding the two layers together, I will lightly sand the bonding locations with some very fine sand paper just to remove any raised edges.

Although I have not created any masks with this method yet, I have taken the time to pierce two sheets of transparent film with a red hot needle and the results look promising.

Bruce

jmg
03-31-2012, 05:11 AM
How about those Double sided Photo-mount tabs ? - come precut on rolls, with easy dispense tabs, and are very thin, and re-peelable.

Ideally they would be outside the PCB clamp area, so even their thickness does not affect the film-pcb clamping.

I think there are also glue-only dots, but they tend to have more wastage, and can pollute things

idbruce
03-31-2012, 06:32 AM
jmg

That would probably be a perfect solution for most people, depending on their exposure setup.

In my current exposure setup, it would not work, because the boards and masks are cut to actual size before exposure. However, as I stated, I am going to make an alternate design, in which all masks will be 4 X 5. In this type of setup, it might work, but in the past, I have had problems with adhesives oozing because the exposure plate is close to exposure bulb.

Thanks for the suggestion, I am sure someone will find it useful.

Bruce

idbruce
03-31-2012, 11:02 PM
Hello Everyone

After quite a bit of deliberation and a little bit of experimentation, I believe I have come up with the very best solution for a low cost, fairly high quality, and durable photomask. Of course it won't compare to a purchased laser photo plot, but how many DIYers is going to order one of those?

Referring to an earlier post, due to my special circumstances concerning my exposure plate design, I was contemplating altering my exposure plate to make double layered transparency photo masks more adaptable, but I wanted to try one more experiment before making any alterations, which resulted in a solution for me.

Creating an opaque photo mask by doubling up laser printed transparencies is nothing new, and there are plenty of examples on the internet. However, in my case, due to the design of my exposure plate, the mask must be the exact same size as the final board. This requirement previously caused me problems due to seperation of the two transparency layers, because the glue did not hold, and tape was definitely out of the question, because it would extend into the exposure area.

So here is my solution for low cost, fairly high quality, and durable photomasks.
Tools, Materials, And Equipment Required:
[*=1]A good work area with adequate lighting[*=1]Magnifying glass[*=1]Scratch awl[*=1]Minimum of a 600 DPI laser printer[*=1]Utility knife[*=1]Thin metal ruler[*=1]Clean sheet of glass for mask alignment, or a light table[*=1]Clean sheet of metal plate (size is dependant upon the size of the mask[*=1]Premium laser transparency film[*=1]Propane or MAPP gas with torch tip[*=1]Bastard file[*=1]Acrylic Krylon Crystal Clear Satin spray paint[*=1]Clean piece of cardboard

Directions:

When designing the mask, include an outline of the board.
Provide several registration marks around the perimeter of the board outline, with the center of the registration marks being approximately 1/2 an inch from the edge of the board.
Print two copies of each mask at the highest possible density and DPI settings.
Place the masks onto the cardboard and spray the masks with a fine even coat of the Crystal Clear Satin. This will blend and darken the toner from the printer. Give them sufficient time to dry.
Place two of the duplicate masks onto the glass, with one side of regristration marks barely overhanging the edge of the glass, and align the registration marks using the magnifying glass.
Light up the torch and heat the tip of the awl to red hot, and then pierce both layers of transpancies through the registration marks that are overhanging the glass. Repeat this procedure until all registration marks have been pierced. Do not go to deep when piercing, just enough to bond the two sheets.
Align the metal ruler at a predetermined trim location. Heat the tip of the utility knife with the torch until it is red hot. While firmly holding down the metal ruler, run the hot utiility blade of along the edge of the ruler. The goal is to remove the excess mask material through a melting process, not a cutting process. It may take a couple of passes to completely remove the excess with a red hot tip. Continue this process until all excess material has been removed. At this point, both layers should be bonded together.
Turn off the torch and put it in a safe location to cool down.
Move the bonded masks to the metal plate and align one of the trimmed edges of the mask with the edge of the metal plate. Now take the file and gently remove any high points from the mask that resulted from trimming with the hot utility knife. Repeat this process until all burrs have been removed from the mask.
Remove any dust or debris that may have accumulated on the mask. I would imagine that with enough Crystal Clear Satin coating, it might even be safe to wash them. :)
Well there you have it folks :)

Bruce

Leon
04-01-2012, 10:07 AM
Or, just use a suitable inkjet printer and save yourself a lot of trouble. :)

idbruce
04-01-2012, 11:00 AM
Or, just use a suitable inkjet printer and save yourself a lot of trouble. :smile:


As we all know, Leon is a firm believer in inkjet printers :) And I must admit that his inkjet does put out a nice mask, however I do not have a 1200 DPI inkjet printer, and after looking at the result printouts of both his printer and mine, I still prefer the laser printer due to it's line definition. However once again, his inkjet does have better line seperation for fine lines.

In my opinion, as established by comparisons, there are pros and cons to both types of printers, which are as follows:
Ink Jet


Pros:
[*=3]For lines smaller than 10 mil there is much better line seperation[*=3]Printouts from an inkjet appear to be more opaque than a laser printout

Cons:
[*=3]Poor line definition

Laser


Pros:
[*=3]Good line definition

Cons:
[*=3]For lines smaller than 10 mil there is poor line seperation[*=3]Printouts from a laser are more translucent than an inkjet printout.
If you need trace widths smaller than 10 mil, I highly suggest using an inkjet printer, but if you prefer better line definition on traces larger that 10 mil, I would go with a laser printer.

Whatever printer you may decide to use, you want the positive/negative image (photo mask) to be as opaque as possible. Even though Leon may not admit it, doubling up inkjet tranparency printouts may also produce better results for your PCBs.

In my opinion, the most difficult part of making your own PCBs is the exposure process. The exposure time of the PCB will be directly related to the quality and opacity of the photo mask. An opaque mask can be exposed for a longer period of time as compared to one that is slightly translucent, which will result in a much better breakdown of the photo resist film in the transparent areas of the mask, and the opaque areas of the mask will still have good photo resist, which will result in easier developing and etching.

Use you own judgement, but I can tell you that my biggest problem has always been the opacity of the photo mask and fine line seperation.

Bruce

Leon
04-01-2012, 11:10 AM
I've never needed to double my transparencies, even when I used a laser printer.

My line definition (on the actual PCB) with an inkjet is just as good as that delivered by a laser printer.

idbruce
04-01-2012, 11:11 AM
Give it a try Leon, it may produce better results for you :)

idbruce
04-01-2012, 11:12 AM
I would be interested to know if it does.

Leon
04-01-2012, 11:14 AM
It's too much trouble, and my results are pretty good as they are. The edges are very sharp.

idbruce
04-01-2012, 11:20 AM
As a side note, referring to Post #39, it is a little bit of a pain working with the torch to trim the masks, so I have decided to try two more experiments:
I am going to attempt to trim the masks with a soldering iron.
If the soldering iron fails to do the job, I will create a little handheld pen with a small piece of nichrome wire (resistance wire) installed at the tip which can be plugged into a wall wart

idbruce
04-01-2012, 11:49 AM
Referring to my previous post, I have decided to design, expose, and etch a simple two trace circuit board which will contain provisions for a wall wart plug and a 2 position screw clamp. The wall wart will plug into the wall wart plug, and the resistance wire will be attached to the 2 position screw clamp. This should enable me to bond and trim the masks quickly and easily.

Hopefully I will have a wall wart without too much current. I am hoping I can achieve this without the need for more resistance in the circuitry.

idbruce
04-01-2012, 11:56 AM
@Leon

All I got to say is this....

When I get it all figured out, I will be able to produce some very nice DOUBLE-SIDED PCBs very quickly.

Experimentation is a good thing. There is an old saying.... "If you continue to do what you have always done, you will continue to get what you have always gotten."

Bruce

Leon
04-01-2012, 01:35 PM
I have made double-sided boards, it wasn't difficult. I stuck the top and bottom transparencies together with masking tape ensuring that they were properly aligned, inserted the double-sided board, and exposed the two sides in turn.

idbruce
04-01-2012, 01:48 PM
As long as you are happy with your process and the results, I guess that is all that counts.

Leon
04-01-2012, 02:00 PM
I haven't found many people who can equal them, let alone get better results.

I've supplied home-made boards when designing systems for people, to save time, intending to replace them with professionally-made boards later. In some cases, they are still using my boards, many years later.

idbruce
04-01-2012, 03:10 PM
Leon

:) :)


I haven't found many people who can equal them, let alone get better results.

I may have lost the pattern challenge, but you never accepted my challenge, referring to Post #152 at http://forums.parallax.com/showthread.php?135950-ATTN-PCBers-SUBJECT-New-website-and-exposure-box-design-for-your-creative-needs&p=1073035&viewfull=1#post1073035

If you need Gerbers instead of a board file, I can supply it.

:) :)

Bruce

idbruce
04-01-2012, 03:12 PM
:)

And if you decide to accept the challenge, please include the quarter in your photos :)

idbruce
04-01-2012, 03:21 PM
And then....

If you are really ambitous....

I further challenge you to make the PCB for this board http://www.st.com/internet/evalboard/product/152186.jsp for which all the gerbers can be found at that link under the tab design support. To make it even more difficult, add four mounting holes to the board. At which point, we can both upload photos and let the forum members judge our endeavors and declare the winner.

:)

Bruce

EDIT: No drilling required, just the etched board, considering I don't have my driller built just yet :)

Leon
04-01-2012, 03:41 PM
I checked the Gerbers with GC-Prevue. It looks like LS.GBR and LC.GBR are the top and bottom.

I'll have a go at it!

idbruce
04-01-2012, 03:54 PM
Please note this specific post has been deleted and is superseded by Post #58.

idbruce
04-02-2012, 12:24 PM
Leon

I thought it would only be fair to mention that this is a quality challenge and not a race, so please take your time. I currently have more pressing issues than this challenge, however, I would imagine that I should have a PCB and photos within a weeks time.

Bruce

Leon
04-02-2012, 12:37 PM
I'll see what I can do.

Was I correct about the top and bottom layers? I imported the Gerbers into Pulsonix.

Something digital with 8/8 mil tracks would be more meaningful.

idbruce
04-03-2012, 12:11 AM
To Those That May Be Interested

Here is my recipe for my second attempt at making a film cutter/fuser. This one appears to work pretty well.

CAUTION: Please do not attempt this project if you are unfamiliar with higher voltages and safe wiring practices.

CAUTION: Please be aware that this device has the abiltity to burn plastic. If you decide to make this device, you must avoid burning plastic with this device. Burning plastics contain a high level of toxins, one of which is cyanide.

CAUTION: Please be aware that this device uses a red hot wire to melt plastic and may cause serious burns if accidently applied to your skin. While the tool is energized and the cutting blade is red hot, please take the appropriate precautions to prevent accidental burns.

FILM CUTTER/FUSER

Purpose:


The purpose of this project is to create a tool to join two identical layers of laser printed transparencies in order to create a more opaque photo mask that can be used to make your own printed circuit boards.


Difficulty Level And Time Required


Providing that a person is familiar with residential electrical devices, this project is very easy to complete and should take no longer than an hour to complete once all the material and equipment have been gathered.


Tools, Materials, And Equipment Required:
[*=1]0.047" 0.032" music wire[*=1]12-Position European-Style Mini Terminal Strip (Radio Shack #274-680)[*=1]Electrical tape[*=1]12 Gauge zip cord[*=1]Small flat blade screw driver[*=1]Drill press[*=1]Sanding drum[*=1]Needle nose pliers[*=1]Dimmer switch[*=1]Receptacle outlet[*=1]4 X 4 electrical box[*=1]Ground screw[*=1]Two gang raised electrical cover to match the dimmer and receptacle outlet[*=1]14/3 SO cord or similar[*=1]Some type of electrical fitting to adapt the cord to the electrical box[*=1]Male plug end[*=1]Battery charger 2 amps @ 12 volts[*=1]Some means to temporarily attach zip cord ends to the aligator clamps of charger[*=1]Heavy duty diagonal cutters[*=1]Wire strippers

Directions:
[*=1]Do not attempt this if you are unfamiliar with working on higher voltages and safe wiring practices.[*=1]Wire up the dimmer to the receptacle using these materials: 14/3 cord, electrical fitting, electrical box, raised cover, ground screw, raised cover, male plug end, dimmer, and receptacle.[*=1]Using needle nose pliers, bend a piece of music wire into a U-shape, with the center of the legs being equal to the center distance between two terminals on the terminal strip. Then cut the legs to a length of 5/8". EDIT: The previously mentioned U-shape is comprised of two ninety degree angles, instead of two legs with a semi-cirlce.[*=1]Sharpen the bottom of the U-shaped piece with a sanding drum and drill press. Sharpen the cutting blade. Through experimentation, I have determined that the film cutter/fuser works best when the leading ninety degree angle has been ground thin for approximately 3/16 of an inch in both directions, and with the bottom corner edge beveled on both sides, similar to a razor blade or utility blade. Additionally, this entire ninety degree angle should have a pointed corner. Make it thin and it cuts like butter, but apply current very, very slowly, when you get to that point.[*=1]Install the U-shaped wire into the last two positions of the terminal strip and tighten the terminal screws.[*=1]On the opposite side of the terminal, apply a conductor from the zip cord to each leg of the U-shape piece, and tighten the terminal screws. The forementioned terminal strip is only rated for 16 gauge, but the 12 gauge wire will fit.[*=1]Fold the zip cord back along the terminal strip and secure with electrical tape.[*=1]By whatever means available, attach the other end of the zip cord to the aligator clips of the battery charger.[*=1]Place the dimmer switch into the off position.[*=1]Plug the charger into the receptacle outlet.[*=1]Plug the previously made electrical assembly in an availabe outlet.[*=1]Slowly turn the dimmer on. If you apply to much current, the U-shaped piece will burn in two or it will be too hot to properly cut and fuse the plastic film. Only use in a well ventilated area and avoid breathing any fumes if the film melts too quickly.
IMPORTANT NOTE: It works much better making several passes with a lower temperature at the cutting blade, then making one pass with the blade at a higher temperature.

Who needs glue or tape :)

Bruce

EDIT: If you decide to make one of these, please take the time to make some spare blades. While I was happily cutting along, the sound of the charger changed from a rough hum to a mild hum and the red tip had turned black. At first I thought I overheated the charger, so I let it sit for a few minutes and tried again, but still no juice. Still hoping it was overheated, I let it set for an hour and tried again, but once again, still no juice. I thought I had burned up my charger and started to dispair :( And just when I was about to pay my last respects, I noticed a crack in the blade. Keep this in mind if you lose power. Check for cracks before deep sixing your power supply, because the crack was very hard to see. :) All is good :)

idbruce
04-03-2012, 03:36 AM
I just made my first double layered positive with a tool as described above and I must say it turned out pretty nice. However, I think the blade needs just a little tweaking because of plastic build up. But I suppose the blade could also be too hot or too cold. I need to experiment just a little more to get the feel for it.

Bruce

idbruce
04-03-2012, 03:37 PM
To Those That May Be Interested

I now have the film cutter/fuser down to a science. Successful operation of the film cutter/fuser is all dependant upon how the blade is sharpened and how much current is applied. I am now able to cut and fuse two layers of transparencies together with very little melted plastic buildup. Please refer to Post #58 and item #4 in the Directions section for an update to properly sharpen the cutting blade.

Bruce

Publison
04-03-2012, 04:25 PM
Bruce,

Got pictures?

Jim

idbruce
04-03-2012, 05:12 PM
Jim

Sorry to say that I have no photos. However, I did learn something new about my exposure box/cylinder and that I must make a new attachment for it. With the addition of some white vinyl and a small piece of glass, the bottom portion of the exposure box/cylinder makes an excellent light box for layout, alignment, and trimming purposes. I used this setup for aligning both transparency layers, spot fusing the transparencies together, and for trimming the double layer transparencies to size. The combination of this setup along with the film cutter/fuser, definitely helps to make less translucent double layer laser transparencies. It all works together pretty nice.

Bruce

$WMc%
04-04-2012, 12:36 AM
Hello Bruce..
'
A big problem I found using Laser printers is with Copper Pours.
'
I'm working with a lot of RF here lately and I need a good ground plain (copper pour) to help propagate the RF.
'
Have you been able to print copper pours with your laser printer with out making a mess?

idbruce
04-04-2012, 12:39 AM
Walt

How big a copper pour are you talking about? Can you provide an example? And are you talking about a mess on the board or with your printer?

Bruce

idbruce
04-04-2012, 12:43 AM
Walt

If you are referring to a mess with the printer.... If I remember correctly, you said you were using 3M transparency film. I would imagine that film is very similar to the film I initially used and it gave me many headaches. With the premium transparency film that I received from the local graphic arts supply house, the results are much better in all respects, including ground planes.

Bruce

idbruce
04-04-2012, 12:50 AM
Walt

Additionally, don't be afraid to touch up the ground planes on the photo mask with a black permanent marker.

Bruce

Leon
04-04-2012, 10:39 AM
When I used a laser printer, I used a grid pattern for copper pour areas.

Leon
04-04-2012, 11:34 AM
Bruce,

I just had a go at printing the top and bottom layers of that test PCB, but had problems printing from GC-Prevue and Pulsonix.

Have you been able to print them OK?

idbruce
04-05-2012, 01:50 AM
Leon

I apologize for the delay, but I just noticed your last post.

GC-Prevue prints out perfect masks for me. In fact, it allows me to add extra layers, such as the mounting holes, and prints them out as well.

There are three possible states for each layer, which are View, Edit, and Hide. When the layers are listed, there will be either an E, V, or H, at the beginning of the layer to represent its state. The layers should be in View state to allow printing.

To save you some trouble, I have attached a project file that includes the mounting holes. Perhaps this will work better for you.

Bruce

EDIT: Additionally, all layers that you do not want printed must be hidden.
EDIT: When printing, select the checkbox for: "Print all data in black"
EDIT: And of course, when printing the top layer, select the checkbox for: "Print as bottom view"

idbruce
04-05-2012, 02:18 AM
To Those That May Be Interested

Just a friendly word of caution.

When spraying your photo mask films with Acrylic Krylon Crystal Clear Satin, the utmost care must be taken not to completely saturate the image, otherwise the toner will bleed to unwanted areas. It takes a few times to get the hang of it. And if it looks as though it has bled, believe it. Just print another mask and try again, because wasting a little film is much better than wasting additional time and board material. Trust me I know. :)

Bruce

__red__
04-05-2012, 05:07 AM
Watching this thread with interest. At our hackerspace we do both laser toner transfer and PCB milling. Never done photo-resist boards so interested to see the results.

idbruce
04-05-2012, 12:30 PM
Leon

Did that help?

Leon
04-05-2012, 01:38 PM
Thanks, Bruce. They printed OK.

idbruce
04-05-2012, 02:12 PM
Leon

In regard to the tips that I provided in Post #69, there is one thing I forgot to mention. Retain the default setting of "Layers To Print: VISIBLE" in the Print Setup property sheet, when using the tips I provided, or you can select individual layers from the Print Setup property sheet if you choose to do so, which will also print a hidden layer without altering the visibilty within the user interface view.

Bruce

idbruce
04-05-2012, 05:08 PM
Hello Everyone

The blades for the film cutter/fuser are burning up to often. They work great, but it is turning out to be a pain creating new blades all the time. As mentioned in Post #58, I am currently bending 0.047" music wire into a U-shaped form, and then sharpening one corner as described in Item #4 of the directions for that same post. I am not sure if they are burning up quickly because the music wire is tempered, too much carbon buildup on the blade from cutting the film, or some other reason.

I would like to find a solution with a little bit of longevity. Does anyone have any suggestions?

Bruce

Publison
04-05-2012, 06:51 PM
Hello Everyone

The blades for the film cutter/fuser are burning up to often. They work great, but it is turning out to be a pain creating new blades all the time. As mentioned in Post #59, I am currently bending 0.047" music wire into a U-shaped form, and then sharpening one corner as described in Item #4 of the directions for that same post. I am not sure if they are burning up quickly because the music wire is tempered, too much carbon buildup on the blade from cutting the film, or some other reason.

I would like to find a solution with a little bit of longevity. Does anyone have any suggestions?

Bruce

Bruce,

I use these a lot for cutting foam shapes. They are actual blades and hold up very well. The price of admission is a little high though.

http://www.demandproducts.com/Hotwire-items/search.php?l1=8,15

Jim

idbruce
04-05-2012, 07:10 PM
Thanks Jim

However I was thinking more along the lines of my homemade cutter, with a different cutting blade. I found some 3/8 crown X 5/8 leg staples, and I have been experiment with them. If I could perfect the use of those, that would drastically cut the time required for making blades.

Bruce

idbruce
04-06-2012, 12:07 AM
To Those That May Be Interested

Referring to Post #75. In an attempt to find a better blade material, I tried using 1/16" tie wire. It appeared that the wire held up well, but there was a drastic increase in the plastic buildup as compared to the 0.047" music wire. By the time I finished removing all the buildup, I had ruined the best looking photo mask that I have had in my hands. :(

Ohhh, and I finally kicked the circuit breaker in the battery charger with this last experiment :)

For a while, I have been considering the modification of a double-edged shaving blade. I may try that next. I will keep you posted.

Bruce

idbruce
04-06-2012, 12:15 AM
I just had a fantastic idea!!!! One of those "A DUH" moments. The wire bending CNC is loaded up with 0.032" music wire. I will attempt to hand bend a prototype, and if it works out well, I could just write a small program to spit out a couple thousand :)

Why didn't I think of that a little sooner DUH

Bruce

idbruce
04-06-2012, 01:43 AM
Referring to Post #79

The 0.032" music wire seemed to do okay with very little buildup, however, it seemed to burn out just a little faster than the 0.047" music wire. Additionally, it seemed that the 0.032" wire did not fuse the layers together as well as the 0.047" wire. I plan to do a little more experimenting with this wire size, because it will enable me to make my blades much faster using the wire bending CNC and I have lot of wire in this size. My main goal now is to get the two layers to fuse together properly. If I can achieve that, then I believe I will be able to create some nice masks fairly quickly and without the hassle of using a torch.

On a side note, when filing down any remaining plastic buildup, use a new or very clean file. Oil, dirt, and old metal shavings remaining on used files quickly destroy a good looking mask. Once again, I am speaking from the little experience I have gained through this experimentation process. However, I did previously mention to perform the filing procedure on the edge of a metal plate, so a new file will eventually gather small metal shavings. Just remember to keep the file as clean as possible and work in a very clean environment to keep the masks looking nice.

Oh, and there is something else you should know. If you make a film cutter/fuser and cut upon a piece of glass as I describe, each cut will leave a line of plastic resin upon your glass plate. This plastic resin can be removed with laquer thinner. Additionally, pressure and heat from the cutting action will cause permanent scratching upon the glass surface. Considering that the cutting wire gets red hot, if you leave it in one place for too long, it will melt the glass, thus making a permanent indentation. :)

Bruce

idbruce
04-06-2012, 12:08 PM
To Those That May Be Interested

As it turns out, the 0.032" dia. music wire works pretty good for cutting and fusing the two layers of film together, however it requires several passes through the cut. Upon completion of trimming the mask, there is very little touchup required to remove the plastic buildup. I am sure there are probably much better solutions available, but this works pretty darn good, and considering that I have an abundance of this particular wire size and a machine to quickly bend the wire into shape and cut it, I believe this is the best solution for me. Please note, that in accordance with previous experiments for cutting blades, these cutting blades must also be sharpened as described in Item #4 of the Directions section of Post #58.

As I mentioned, this is a good solution for me, but if you decide to make a film cutter/fuser, you may want to experiment a bit more to find or create something that works much better. If you do find something that works much better, please let me know.

Bruce

doggiedoc
04-06-2012, 12:20 PM
Bruce - I was wondering about the physics of the smaller wire working better. Does the smaller wire heat up faster from the friction and thus fuse the layers better and burn off buildup better or am I not visualizing the process properly?

Thanks,
Paul

idbruce
04-06-2012, 12:43 PM
doggiedoc


Does the smaller wire heat up faster from the friction and thus fuse the layers better and burn off buildup better or am I not visualizing the process properly?

The smaller wire heats up faster due to resistance. :)

The main idea is not to burn the plastic, but to slice through it by a melting process. As the blade is slicing through the two layers of film, the blade is hot on both sides, which results in both layers on both sides of the blade being melted and joined together.

As for the buildup, I believe this is all related to the actual thickness and bevel of the cutting portion of the blade. For instance, if you have a lump of bread dough on the counter and you slice through it with a razor blade, you will not have much buildup on either side of the blade. On the other hand, if you attempt to slice through the dough with the handle end of a butter knife, I would imagine the buildup would be pretty significant on both sides.

Remember, you do not want to burn anything, you want to melt it.

Bruce

idbruce
04-06-2012, 01:14 PM
As a side note, in the past, I had been tacking the layers together by just placing the blade in one spot and holding it there for a second or two. This actually burns the plastic in these particular spots, and releases a very pugnant odor. Burning plastic fumes can be very harmful and may even contain cyanide, so burning the plastic should be avoided if at all possible. Tacking can also be achieved by a slicing motion through the trim areas of the films and this is my current method of tacking.

Bruce

doggiedoc
04-06-2012, 01:53 PM
Thanks Bruce. I understand now. In skimming through the thread I picked up on key words such as "blade" and must have missed references to there being a current through the blade. Now I see.

Thanks again for helping me understand.

Paul

idbruce
04-06-2012, 02:00 PM
Paul

You're welcome. Actually, besides the friction part :) it was a very good question. It helped me to analyze the whole situation and I now have a much better understanding myself, especially after thinking about the dough, razor blade, and butter knife analogy.

Thanks for the question.

Bruce

doggiedoc
04-06-2012, 05:21 PM
:D I had visualized the thin loop of wire spinning in the fashion of a Weed-Whacker! But I must confess my mind was on lawn work at the time. :D

idbruce
04-19-2012, 11:53 AM
To Those That May Be Interested

I have been doing all kinds of experiments lately, and as you might have guessed, some of these experiments have pertained to making a more opaque positive. In earlier posts you will see that I have experimented with fusing together double layer laser transparency prints. While this effectively makes a more opaque photo mask, I must admit that it is a slight pain to align and trim, therefore I doubt most DIYers would attempt this method. Still the fact remains, an opaque photo mask must be used to obtain high quality PCBs.

So how do you obtain an opaque photo mask for creating PCBs with the least amount of pain?

I currently do not have an answer to that question, but I may be onto something. After thinking about the problem for quite some time, I came to the conclusion that the biggest problem with laser printers is that it fades in large areas of black, such as a copper pour on a PCB. So my next question was, "Why does it fade in large areas of black?". So I began to investigate and experiment.

For my first experiment, I printed a 300 X 300 pixel filled black rectangle. Upon close examination, I noticed there was a very dense outline around the perimeter of the rectangle, and this outline was approximately 5 pixels wide, and furthermore, whatever was on the inside of the outline had the same type of shading (greyscale). So now I wondered, "Is this type of print shading (greyscale) specific to filled shapes or does it also apply to printed fonts?". So for my next experiment, I printed the letter "R" with a font size of 400. Since I already knew what I was looking for, no close examination was needed and it was readily apparent that the large "R" had the very same dense outline around the perimeter and the very same shading (greyscale) as the filled black rectangle.

Through these experiments I have come to the conlusion that the outline and shading is all software related to save toner. If the entire image could be printed with the same density as the outline, then perhaps a laser printer just might be capable of printing a very nice photo mask in one layer. Since both of my laser printers are Hewlett Packard LaserJet(s), I have ready access to two programming languages for controlling them, which are PJL and PCL. I don't know if either of these programming languages will allow me to alter this perimeter density and shading effects, but I definitely plan to investigate the possibilty.

Bruce

Leon
04-19-2012, 12:27 PM
As I've said on one or two occasions, a 1200 dpi inkjet printer costing $100 produces opaque transparencies when used with the correct material, without any problems. The fact that exposure and development times both have a lot of latitude indicate that the contrast is correct.

I used to use an HP laser printer to produce transparencies on both tracing paper and LaserStar film, and that worked OK, without messing about with the software. Exposure and development were also non-critical.

You should mention your problems to the Homebrew PCB Yahoo Group. Several people there use laser printers to produce their transparencies.

idbruce
04-19-2012, 12:34 PM
Leon

That is great for people that are willing to go drop $100 dollars for a new printer, but what about the people that have already have a laser printer and don't want to spend $100.

As you have already mentioned, and as Walt has hinted, this is a problem specific to laser printers, especially for copper pours.

It might be easily resolved with a few lines of code and I intend to find out.

Bruce

T Chap
04-19-2012, 12:42 PM
Back when I was making homemade boards, I used either 2 mylars with laser or inkjet prints stacked on top of each other. I took 2 pieces of scotch tape, stuck them together so they overlapped a little to create a double sided piece of tape. I would make at least 4 of these pieces and then put one near the edge of the mylar(top, bot, l/r) and then press the mylar together in the art region. It would take maybe a minute to line it up and then press the tape areas together to lock the mylar on top of each other. Another trick is to print the image reversed so that the image is placed on the bottom side of the transparency against the board. This way there is even less light to travel 'around' the edge of the ink and create a less sharp impression. Of course it was required to press the glass against the mylar to force the ink layer onto the PCB. This was cheap and dirty, worked great.

Regarding lasers, I found that they provided no real benefit. A basic inkjet will do the job just fine, but I always stacked the film. Side note: Ordering boards is the only way to go in hind sight :)

idbruce
04-19-2012, 12:48 PM
@T Chap

I am aware of double layering, however this is what I want to eliminate. On your laser printer, print out a 300 X 300 pixel filled black rectangle and you will see a definite dense outline around the perimeter. If this dense outline could be changed for the whole image, double layering could become a thing of the past.

Bruce

Leon
04-19-2012, 12:48 PM
I always reverse the bottom image.

T Chap
04-19-2012, 02:10 PM
Even if you can eliminate the fringe issue, you cannot rely on one mylar for a home process, whether laser or ink jet. It is begging for problems. Some traces will get lost, maybe not every board though.

idbruce
04-19-2012, 02:35 PM
T Chap

It is not really a fringe issue. The issue is to get all printed data to the same density as the outline. Considering that the proposed solution is not readily available on the internet, unless someone has tried this proposed solution discretely, I do not see how it can be unequivocally stated that proposed solution would not provide a photo mask dark enough to proficiently create PCBs.

Bruce

idbruce
04-19-2012, 02:40 PM
And just for the record.... At this point, I have completed at least 100 exposures concerning PCBs and laser printed photo masks, so I am fully aware of the circumstances.

Leon
04-19-2012, 03:10 PM
Even if you can eliminate the fringe issue, you cannot rely on one mylar for a home process, whether laser or ink jet. It is begging for problems. Some traces will get lost, maybe not every board though.

I use a single transparency, and never have problems. Other people who use inkjet printers achieve similar results.

idbruce
04-19-2012, 05:41 PM
To Those That Might Be Interested

In an effort to create a more opaque photo mask in a single layer, I attempted to utilize PCL5 to manipulate the printer. Although I was eventually able to programatically communicate with the printer, at this point I have had no success, however it was an interesting learning process, and I will try again at a later date.

Here is an interesting page for those of you who may have a PCL5 compatible printer:
http://www.piclist.com/techref/language/pcl/index.htm

And here is an easy example of using PCL5:

http://www.piclist.com/techref/language/pcl/lj1438.htm

Bruce

idbruce
04-20-2012, 02:02 AM
To Those That May Be Interested

Upon further examination and consideration, I have now come to the conclusion that the darker rectangle surrounding the faded rectangle is not software related. I now believe it is just build up of melted toner that has gone to the outer edges.

So now I wonder what the printed output would look like if the laser printer fuser temperature was reduced to a point of just adhering the toner to the paper or transparency.

Bruce

idbruce
04-20-2012, 11:02 AM
To Those That May Be Interested

In reference to my last few previous posts, but more particularly the last post, I have decided to devote one more day to experimenting with my LaserJet 6L. For today's experiments, I will be exploring various options concerning the fusing of toner to transparency film with a laser printer.

For my first experiment, I will attempt to completely disassemble and disconnect the fuser and roller assemblies, and allow the printer to exit a film with loosely positioned toner to see what it looks like untouched by further processing. If it looks good (better than the normal printing procedure), I will then bake the film to see if I can get the toner to adhere to the film with the absence of pressure. I believe this would be the best possible scenario.

Another option is to reassemble the printer with the fuser and roller assemblies, and decrease the current available to the fuser for a cooler fusing process.

Bruce

Leon
04-20-2012, 11:39 AM
The film you are using might be the cause of your problems. You should try a film that is made for PCB transparencies, such as Mega Electronics LaserStar:

http://www.megauk.com/artwork_films.php

It worked very well in my LaserJet II, many years ago.

They will probably send you a sample if you ask them nicely. They let me have a sample of their JetStar film for testing.

It's available in the USA from Farnell.

I even got my laser printer to produce a transparency by using ordinary paper, and making it translucent with vegetable oil. It worked OK, but was a bit messy. It does illustrate how non-critical the standard photo-etch technique can be.

I can't understand why you are having so many problems. You've been at it for nearly six months, and still haven't produced a single working board! :)

idbruce
04-20-2012, 12:44 PM
Leon

I got my film from a graphics art supply and it is supposed to be used for plate making in conjunction with laser printers, and it would work perfectly, if I was not trying to conquer copper pours. As it stands, considering the translucency of the toner within copper pours, if I expose for the pour, than the line art is improperly exposed, and if I expose for the line art than the pour is improperly exposed. It is really wierd. If I was to expose the top and the bottom at different exposure times, I am sure I could create the perfect sample.

I know you have seen this file before, but here it is again. I can either expose the bottom perfectly or I can expose the top perfectly, but not both, all based upon exposure time. I am certain that if I had a laser photo plot, it would be a cake walk.

If I expose for the top layer, the photo resist washes off of the copper pour on the bottom layer during developing, due to the translucency.

If I expose for the bottom layer, the photo resist on the top first becomes fuzzy and then washes away while I try to remove the haze.

I have perfect etchings for both the top and bottom layers, but not on the same sample chip. And of course the goal is for perfect exposure and perfect etching for both layers on the same sample chip.

Bruce

idbruce
04-20-2012, 12:47 PM
Leon

Additionally, the instructions for the film are to use the lowest possible fuser setting, however, the LaserJet 6L does not provide any means for lowering the fuser temperature.

Bruce

Leon
04-20-2012, 01:19 PM
That would be one reason for trying the LaserStar film. It doesn't have any such recommendation.

I don't think that I'd have had a problem with those top and bottom patterns when I used a laser printer. I think that you might have a problem with light leakage, which doesn't arise with UV-sensitive material. Making two single-sided boards might show the cause of the problem.

idbruce
04-20-2012, 01:26 PM
Leon

Perhaps it is the fuser temperature, because a lower temperature would defintely result in a thicker toner layer on the film.


You've been at it for nearly six months, and still haven't produced a single working board!

You're funny!

The fact is that I can create a working board any day of the week, but once again, I am striving for perfection. If I have to, I will go get the photo plot, but I truly want a LOCAL solution.

Bruce

idbruce
04-20-2012, 01:29 PM
Making two single-sided boards might show the cause of the problem.

I am sure a lot of it pertains to the close proximity of the board to the light source, and of course there is always the possibility that one light is stronger than the other.

idbruce
04-21-2012, 11:31 AM
Leon

You better start practicing, because I am getting ready to start giving you lessons :)

Bruce

Leon
04-21-2012, 11:43 AM
Have you fixed the problems?

idbruce
04-21-2012, 12:08 PM
Leon

For the last couple days, in addition to various exposure tests, I have also been experimenting with various mask materials. Last night I attempted another exposure with vellum, only this time I sprayed it with a clear coat. I exposed both sides at the same time, for 1 minute and 35 seconds. After developing the sample, it appeared to look pretty darn good on both top and bottom. Then upon closer inspection with a magnifying glass, I noticed that the traces appeared a little jagged, however the films produce nice and smooth lines. So I decided to give one of my thickest films with a matte finish another try, only this time, I put a clear coat on both sides of the film. With the exception of a small light bleed on one edge, the sample came out of the exposure and developing process looking quite "stupendous" :)

This particular film with a clear coating on both sides in conjunction with a 1 minute and 35 second exposure time, as well as a developer mixture of 13 grams sodium hydroxide to 1 liter of water, appears to be the perfect combination.

Over the last couple days, I have noticed light bleeds on one edge only, and always on the bottom layer. Once I figure out how this light is getting in, I should have the perfect process.

Bruce

idbruce
04-21-2012, 12:13 PM
It is noteworthy to mention that when I ordered new boards, they came in new packaging, and the protective covering seems a little more difficult to remove. Perhaps the film is creeping back on me during the exposure process. I will have to pay better attention after the next exposure to see if this is the cause.

Bruce

idbruce
04-21-2012, 01:23 PM
I would imagine that I should have a "beautiful" sample to photograph sometime later today. And when I say "beautiful", I mean it will be a "10" on a scale of 1-10, with 10 being the highest rating. :)

Am I telling tall tales? :)

I don't think so. :)

idbruce
04-23-2012, 09:12 PM
Hello Everyone

I just wanted to say that I have a very nice looking sample chip to show you guys, but I do not have any photographs yet. I will probably tin plate the sample before taking the photos.

Bruce

$WMc%
04-25-2012, 02:13 AM
Hello Bruce
'
I'd like to see the PICs of the exposure when you get them ready to post. I have found copper pours the most difficult to do.
'
Had a freak storm come through FL.
'
Lightin strike has about put me in the dirt.
'
I hope to recover in a week or so.

idbruce
04-25-2012, 03:05 AM
Walt

The way I interpret your post, you must have got personally struck by the bolt, if that is the case, I am sorry to hear that and I hope you get better soon.

As for the sample, it looks pretty darn good. The file attached in Post #102 represents the sample that I made. It does not have much of a copper pour, but there is a good chunk of solid copper on the back side with no pin holes. I will post photos soon.

After all my testing, I have come to the conclusion that all my problems were either associated with improper developer temperature or an inadequate photo mask. I have finally achieved good temperature control for the developer and I am currently working on something to get better masks.

Since I am assuming that you got struck, I will also assume that you have not felt good enough to read the forums. Since we last chatted, I have started several knew threads, and I think they have some very good content. You might want to check them out.
New Project/New Experiment - PCB Etchant And Developer Heaters
http://forums.parallax.com/showthrea...eloper-Heaters


Construction Of A PCB Prototyping Table
http://forums.parallax.com/showthread.php?139308-Construction-Of-A-PCB-Prototyping-Table

Help needed for thermistor/Propeller BOE experiment
http://forums.parallax.com/showthread.php?139633-Help-needed-for-thermistor-Propeller-BOE-experiment

Bruce

$WMc%
04-26-2012, 02:36 AM
Hello Bruce
'
I wasn't hit by the strike, But my house was.The strike knocked out my PCs and the back-up usb drives that I had....A lot of data lost.
'
Now I see a use for Cloud...
'
I'll check out your posts

idbruce
04-28-2012, 12:13 AM
Walt

Glad to hear that you were not hit, but sorry about the data loss. I truly know what it is like to lose data.

Bruce

idbruce
07-02-2014, 02:48 AM
Hello Everyone

It has been two years since this thread has seen any action, but since my current endeavors and problems apply to this thread, I thought I would make a post.

In the last two weeks, I have attempted to make two boards. The first board turned out nice on the first try, but the second board was really quite disappointing, with the copper pours being highly faded, and I just did not waste my time attempting to etch it. So here I am, stuck again with the same old problem, being a poor positive image for exposure. So I fiddled around all day, toying with various printers, which left me quite frustrated, and having to face the fact that print shops no longer make positive films, made my situation even worse.

A while back, Phil helped me set up the thermistor for a modified LaserJet 6L printer, and it worked pretty well, but has since become filthy with excessive toner buildup. To sum that up, I just got tired of taking it apart and cleaning it. So instead of cleaning and using the LaserJet 6L, I decided to use the LaserJet 2000D in an unmodified form. I began by testing various professional transparency films, but none of them even came close to achieving the film I desired. Being an experimental type person, I decided to see how many layers of printed films it would actually take to make a combined film that would be fairly opaque. Altogether, it took three layers of film with printed circuitry to form a pretty dense positive. I have heard about and even attempted doubling up films, but three of them....

Taking the layers one at a time, I taped the top and bottom of each layer to a white layout board, aligning them as I progressed. I then trimmed one side to the final dimension and lifted all three layers and inserted scotch tape under the layers and folded it over the top of the layers. After doing this, I then done the other side the same way, and then finally the top and bottom.

As it stands, the combined positive is fairly stout and pretty much opaque, but still allows light to pass through the transparent areas. To compensate for all these layers, I will undoubtedly have to increase my exposure time and experiment a little.

Of course I am hoping this will be the end of my woes concerning positive films. I will let you know if it works or not.

Tubular
07-02-2014, 03:32 AM
I've found if you accept a bit of pitting in your copper pours, generally one layer of film is sufficient, even if the laser printer isn't great. Two layers is better, particularly if using overhead transparency film.

Also its worth mirroring the top layer before you print it, as this lets you place it directly against the copper pcb. That closeness stops light ducking under the substrate, blurring the definition a bit.

And, are you printing on Mylar (polyester) - if not this is well worthwhile. It does seem to absorb a bit of the UV

idbruce
07-02-2014, 04:02 AM
Okay....

My normal exposure time is 1:30, and since I was going with three layers, I decided to bump it up to 2:30. After several minutes in the developer, not even a single trace could be seen and the resist was all in tact. I will now attempt a 5:00 exposure time. Hopefully I will get it in the ballpark before I eat up to much material.

idbruce
07-02-2014, 04:04 AM
Tubular

I would assume the film is polyester, although I am not 100 % certain. It is a milky white color.

Tubular
07-02-2014, 04:09 AM
Yep that sounds like the one. Its good stuff, but I have found getting the toner against the pcb (mirror printing) helps with definition. Of course the pits are better defined too, but it might save you a layer

I've also found 2 layers needs much longer exposure time (~double).

I'm getting close to revisiting all this again with old HP laserjets, 4 of them to try at last count, vs more modern samsung, oki and lexmarks. I'd also like to try direct printing onto the adafruit copper clad flex (newly available) and see how that goes

idbruce
07-02-2014, 04:53 AM
I have always liked laser printers, but Epson supposedly has some inkjet printers that do a nice job.

potatohead
07-02-2014, 05:38 AM
"print shops no longer making positive transparencies"

Really?

I just got one yesterday. This problem is very similar to the one involving silk screen exposure. There are basically four cases involving the emulsion and the image.

E-up, Positive
E-up, Negative (image printed mirror, on the near side of the transparency, closest to your eye)
E-down, Positive (Image printed normal, on the far side of the transparency, farthest from your eye)
E-down, Negative.

For a "shine a light on it" type exposure, you really want E-down, Positive, or E-up, Negative. (this is the mirror print mentioned above, I believe) E-down positive means you will be looking through the transparency to see the image rendered correctly. E-up, Negative means you will still look through the transparency to see the image rendered correctly, but you will flip it over first. Both result in the same thing, and it's just how the printer ends up doing things.

The key is to look through the transparency to the image, not have the image separated from the material to be exposed.

The thickness of the transparency is generally on the order of .004' to .012", depending on a lot of things.

If you get it printed with one of those combinations, how thick the transparency is doesn't matter too much because the toner, ink, whatever, will be right up against whatever it is that is being exposed, which results in very little and very sharp shadow, important for thin, or high precision images. Think a PCB trace, or photo reduced to dots for grey scale approximation like you see in a newspaper.

Even very thin, .004" transparency casts a significant shadow, which itself can impact art under .005"

When I get these printed, I just ask for the appropriate emulsion, and image positive or negative, and I get them quickly. If they don't understand the specification, I don't have anything printed there.

Use a shop that understands screen printing, and get a great transparency done for very little money. An ordinary office or Kinko's type place may not even understand what any of the above means, and the printers they use won't deliver very good images, particularly where there are extremes, such as high detail, combined with big fill areas.

They almost all use document based setups, and often middle to low end business grade gear. Nearly all prints, even on pro grade equipment, will require some touch up, though the better places either do it, or there isn't much to do. Consumer and middle of the road business printers are worse.

To beat that, it's basically a matter of doing a precision camera exposure. Those are a PITA, and not something suitable for most PCB work I see people do.

As mentioned above, allowing for variances in the big fill areas is a much quicker and easier cleanup than the same thing happening in detail areas.

Here's a nice tip:

Two kinds of inks out there: dye based and pigment based.

A dye based ink, will generally dry very flat, and can be easily dispensed from a pen, or brush. Dye based inks, deposited in thin layers really do not occlude brighter light sources on non-absorbent material. This is the streaking you see from a sharpie, etc... on transparency. Pigment based inks do occlude, but they also have a thickness when dry. But they work on non-absorbent material much better than a dye based ink does.

Lasers use pigments, ink jets generally use dyes. Xerox combines the two, using a wax, pigment based ink. (makes killer transparencies, BTW. Just do E-up, Negative and flip it over. :)

To fix something with small pits:

A sharpie on the emulsion side can work for some small things, like a little dot here and there, and if more is needed, use the sharpie on the emulsion side, but then also go to the OTHER SIDE, and use touch up ink of some kind that is pigment based, not dye based, and it will black out with few worries.

The sharpie will occlude most of it, but it's dye based, and it will allow some light through. Using pigment based inks will block the light, but those have a thickness that causes a separation from the material to be exposed.

Avoid this, and use the pigment on the non emulsion side, sharpie on the emulsion side, and you get the best of both worlds and a good exposure. And, you can overdo the non-emulsion side for simple fills. Just a bigger dot takes care of it.

One other advantage of using a silk screen capable shop, that understands emulsion, is you can ask for fairly thick, durable transparency and not have to worry about always cleaning it up. For PCB, this is likely of limited use, but something to think about if you plan on making multiple exposures.

Watch out for Ink Jet printers. They have a "dot duty cycle" or dither pattern that does not produce a 100 percent ink fill when printing. Since the vast majority of prints happen on special photo paper, or absorbant paper, a 100 percent ink fill is actually too much. If you run a print on something not absorbant at all and examine it under a lens, it's highly likely to contain variations in the overall ink coverage, due to this being engineered in. Absorbant paper spreads the ink out, and it's not an issue most of the time.

Secondly, they are dye based. Some drying time will be needed, and the ink may well puddle or gather requiring a touch up phase. And a dye just won't occlude the light as well as a pigment will, narrowing the exposure time constraints, due to leakage on detail areas.

Toner based machines use a pigment, and it's powder, ink, or wax of some kind. This generally doesn't have the same problem on transparency, just FYI.

garyg
07-02-2014, 06:09 AM
Hi
I'm a bit late at chiming in here, but here goes.
While I'm using Toner Transfer method with my circuit board projects, I'm quite familiar with silk screen light sensitive exposure template
I have been quite disappointed with the results of my toner transfer printings until the last few circuit boards using the toner transfer method.

I am not intending to say that the toner transfer method of making circuit boards is proper for what you are attempting to do.

However
If the toner is dense enough on the proper substrate, I believe that you should not have problems exposing your light sensitive boards.
Common transparency film does not work well.
Photo copies from Office Max do not work well, unless I've coated inkjet transparency film with PVA, it's a water soluable coating.
I've spray coated inkjet film with PVA and ran copies of my print that seemed to work pretty good.

The last project I did used something called Tek-200 film.
The company that I purchased the Tek-200 from no longer exists, but the result was very good.
I used a Brother laser printer, with settings at 600 dpi and toner set to maximum density.

The maximum density setting, I believe is the most important.
I could see the toner actually raised above the film.
I could even see the toner raised above my common 20lb printing paper.

On my Brother Laser printer, I can set the print resolution to 600 DPI
But
if I don't set the Density setting to max, Silk screen films do not expose correctly nor do my Toner transfer films.

Just one other thought,
Your are, in some manner, making sure that your printed film is exactly in contact with your copper clad board?

When I'm doing a screen, I put the screen on a piece of felt fabric, then a piece of 1/8" glass on top.
If the substrate and film are not in absolutely direct contact, unsatisfactory results will happen.
I'm sure you realize that the actual toner needs to be in contact with your copper clad,

Just my 2 cents worth.
I hope it helps in some manner.
I've been following all of the idbruce 3d printing threads very closely.

Loopy Byteloose
07-02-2014, 06:19 AM
My own experience is with printing transparencies on ink jet and laser printers.

A. With a laser printer, you seem to have to print two copies and tape the edges together in perfect alignment to get a good dense black. I have a Fuji-Xerox Docuprint 203 that never prints an adequate single copy.

B. With ink jet printers, I found Canon to be terrible as the ink would actually bead up on the transparency.

But the HP ink jet printers, are pretty good. Their ink appears to be an emulsion intended to stick to anything. The only draw back is that is doesn't dry completely and can smudge with handling. It doesn't seem to be much of a problem for myself.

+++++++++++
Conclusion - I just got rid of the Canon ink jet and got an HP that is my stand by for color printing and circuit boards.

It is all in the quality of the ink or toner. And it seems that ink varies more from maker to maker.

+++++++++
I don't use toner transfer method as it seems to be harder to control than a light exposure. With a good dense transparency, the timing of the exposure should not be hard to get right.

potatohead
07-02-2014, 06:21 AM
Yes, great tip with the glass.

I just was thinking about the two layer approach mentioned here. Given a good alignment, this just leaves the little shadow resulting from the distance between the layers and the exposure target. That will impact things under about .007" or so. Smaller = worse. If a two layer is used, that should be combined with the very thinnest transparency possible to feed through the printer.

Registration marks are a plus, but I'm sure those are being used. Worth a mention though. Just make sure they are on opposing corners, so you get good registration on both axis.

Some of that can be mitigated by making the light source more directional. Consider a paper wrap around the lamp to form a cylinder. A conical light will cast a much greater shadow than a more directional one will. Using the paper will limit the light area, but for a board, this might work well! You will still get a shadow, but it will be a much sharper one, and smaller relative to the image detail.

What you want is more of a spot type light, not so much an area light or cone, if you've got layers and or are working with the emulsion away from the exposure target. Placing the light close to the exposure action will further improve this.

Something to try anyway.

idbruce
07-02-2014, 02:47 PM
5 minute results....

After exposing the 3 layer positive for 5 minutes, I placed the board into the developer, which was at 106 degrees fahrenheit. It did not take too long before the traces and holes started to appear, however the whole developing process was taking way to long and the developer got cold. Anyhow, during the development process, all the traces and pours were looking very nice (with the exception of a blemish that I believe has to do with the board being old), until I cranked the heater back on for the developer, at which point I went to hot.... And started washing the resist away :)

Anyhow, I believe the 3 layer positive will work well for both traces and pours, but I think I need to lengthen the exposure time a bit more, to make the developing go much quicker. I think for my next try, I will attempt 8 minutes. Perhaps this will soften the resist a bit more, but hopefully not too much.

@potatohead - Print shops in my neck of the woods no longer offer the service of making positives. I would assume because they have gone with more recent technology.

potatohead
07-02-2014, 04:26 PM
Probably cheaper tech. Good printing isn't old. It is more like they can make enough with mid-grade tech, which is new.

If you can find a Xerox printer somewhere, you should try an e-up, negative print. Flip it, and that should expose very well. The wax ink is solid, pigment based. One layer is likely sufficient. And those will print on the thicker transparency sheets.

You want to find the wax ink ones, not the newer toner models. Wax models went to 600 DPI, more than enough for PCB work.

I don't have one where I work now, or I would just do a print.

Those things can be had used for not too many $$$

I've done screen art on 'em, and got really good results. Likely a good fit for PCB.

idbruce
07-02-2014, 05:42 PM
Before washing out my board, by cranking up the developer heater, it was looking pretty good. For now, I am just going to experiment a bit more with the three layer positive. However, I think the previously stated exposure time of 8 minutes, might be a little too much, for my next experiment. Now that I am getting results, I think I should experiment in smaller increments. So for my next trial, instead of an 8 minute exposure, I believe I will shoot for 6-1/2 minutes.

As for seeking out printers to make positives, I believe you are correct and I should be seeking out screen printers, because they have very similar needs. And even if they don't make their own positives, maybe they might know where to get them.

Hopefully, the three layer setup will work well for me, because then my problem will be solved, and I will be able to save all the gas money of driving back and forth that may go toward purchasing a positive film. Either way, I am out to resolve this problem once and for all, before wasting too much board material.

Heater.
07-02-2014, 08:48 PM
My question is: Why are we straining our brains over this?

Design your schematic, do your layout, get oshpark or whoever to make the PCB. It's all done in less time and less money that dicking around with all these home brew ideas. Plus the resulting boards are works of art you can be proud of.

Don't get me wrong, it's all a good experience to make your own PCB's from scratch. I did that back in the late 1970's when that was the only way for a penniless young boy to go. Today we have the luxury of very quick and cheap ways to get boards made.

potatohead
07-02-2014, 08:56 PM
I agree. However, I also know Bruce wants to do it in house, so to speak.

Personally, I would send out, or build on perfboard. Time is expensive.

Thing is whether or not one is setup. If the skill is sharp, gear sorted out, it's nothing to just make one and get it built up that day.

I'm assuming the latter here, and enough boards to make sense.

***Which is why locating an older Tektronix / Xerox printer that does wax ink may be worth doing. One it gets to layers, using a print shop, etc... may as well send out for the board and do other engineering while waiting.

idbruce
07-03-2014, 02:20 AM
Why are we straining our brains over this?

One, I have a fairly nice system and setup, except for the positives films and automated drill. Two, I have several boards that need to be made and I only need one of each. Three, I like to experiment and make things with my hands. Four, because I have had success with it. Five, it is economical. Six, I am impatient. Seven, I am still trying to perfect my system.


Plus the resulting boards are works of art you can be proud of.

Hmmmm.... I take pride in my work. I could easily just lay traces and etch, but I want the pride of knowing that I can do nice copper pours with my own two hands.

Alex.Stanfield
07-03-2014, 03:07 AM
I'm using Dupont's Riston 9000 series of negative UV photoresists. Very easy to use and reliable.
For the artwork I print on tracing paper (150grams) using a Ricoh 600dpi multifunction laser copier (mirrored and negative of course)
Exposure time is 1:30 to 2:00 with two F6T5 BL lamps
After developing in solvay sosa and etching you get rid of the photoresist with plain household alcohol

Results are great.

Alex

potatohead
07-03-2014, 05:28 PM
Tracing paper seems like a great option!

Thanks for posting that. I may well attempt it for some screen art I need to bang out in the near future.

Any special light setup?

I would have thought that kind of paper would diffuse the light into small details, or vary in the exposure time, due to reduced efficiency and variances in paper material density. Doing it negative does get the image right up against the exposure target though... I'm intrigued.

ellipser
07-03-2014, 09:49 PM
My question is: Why are we straining our brains over this?

Design your schematic, do your layout, get oshpark or whoever to make the PCB. It's all done in less time and less money that dicking around with all these home brew ideas. Plus the resulting boards are works of art you can be proud of.

Don't get me wrong, it's all a good experience to make your own PCB's from scratch. I did that back in the late 1970's when that was the only way for a penniless young boy to go. Today we have the luxury of very quick and cheap ways to get boards made.

^^This

I just paid $35 for 3 boards. They make it unbelievably simple. Instead of zipping your file, following a tutorial to send the Gerbers, etc, you just download it onto their website, and you immediately get the image they are going to make for you. I found some mistakes on my board and corrected them with their service. It's been a few years since I messed around with those nasty staining chemicals, and in that short period of time, technology for the hobbyist significantly improved. Cheaper, simpler and the ability to do checking based on what the board house gets. You'll save money by not having to do as many revisions.

Alex.Stanfield
07-05-2014, 03:26 AM
Tracing paper seems like a great option!

Thanks for posting that. I may well attempt it for some screen art I need to bang out in the near future.

Any special light setup?

I would have thought that kind of paper would diffuse the light into small details, or vary in the exposure time, due to reduced efficiency and variances in paper material density. Doing it negative does get the image right up against the exposure target though... I'm intrigued.
My light setup is DIY UV exposure box with two 6W BL bulbs at about 40mm from the pcb. The artwork and pcb are sandwiched between two 6mm clear glass plates.

The tracing paper appears to be "transparent" to the UV light and helps to evenly diffuse the light, it's also a better sustrate for holding the toner in it's place. If you are not very picky about edges you can even print it on ink jet printers.

Alex

Heater.
07-05-2014, 03:40 AM
Whilst we are here, has everyone seen the online 3D gerber viewer at http://mayhewlabs.com/3dpcb

idbruce
07-05-2014, 06:08 AM
The 6-1/2 minute exposure was a complete loss and waste of time. In fact, the five minute exposure was a lot less of a headache.

I have decided to abandon the three layer positive for now. Later today, I will be tracking down various screen printers and see if they know where I can have positives made.

As mentioned, I intend to solve this problem once and for all, or at least make a very serious attempt at it. If I fail to find a local source for opaque positives, I will then be attempting to process my own positives with contact printing, by exposing and developing orthochromatic high contrast film.

EDIT: After a bit more research, I came across much cheaper film supplies. If I end up going the film route, this will be the purchases in an attempt to resolve the positive film problem:

Arista Ortho Litho Film 2.0 4x5/50 Sheets $10.99
http://www.freestylephoto.biz/51455-Arista-Ortho-Litho-Film-2.0-4x5-50-Sheets


Arista Powder A/B Lith Developer 1 Gallon $17.49
http://www.freestylephoto.biz/50022-Arista-Powder-A-B-Lith-Developer-1-Gallon


Arista Darkoom Safelight - Red $35.99
http://www.freestylephoto.biz/325000-Arista-Darkoom-Safelight-Red


Arista Premium Odorless Powder Fixer to Make 1 Gallon $6.49
http://www.freestylephoto.biz/4086-Arista-Premium-Odorless-Powder-Fixer-to-Make-1-Gallon


Arista Indicator Stop Bath makes 3 Gallons $5.29
http://www.freestylephoto.biz/11912-Arista-Indicator-Stop-Bath-makes-3-Gallons


Arista Flow Wetting Agent 4 oz. $4.19
http://www.freestylephoto.biz/6170-Arista-Flow-Wetting-Agent-4-oz.


Arista Set of 4 Developing Trays - Accommodates 5x7 inch prints - (White/Red/Buff/Green) $11.99
http://www.freestylephoto.biz/012057-Arista-Set-of-4-Developing-Trays-Accommodates-5x7-inch-prints-(White


Paterson Print Tongs (2) $9.99
http://www.freestylephoto.biz/2341-Paterson-Print-Tongs-(2)


Total $102.42 not including tax or shipping

idbruce
07-05-2014, 08:17 PM
It appears that I had one of those DUH moments.

Early this morning, I started tinkering with the printer settings, in an attempt to make a better positive, and after a bit of fiddling, I produced a fairly decent positive film. Since I had used all of my developer on previous attempts, I had to make another batch, and while I was making the new batch, it dawned on me that I had not subtracted to weight of my measuring container, on both the previous and current batch, so I added a little extra something something and whola.

After mixing the new developer, I decided to try another single layer exposure at 1:30 minutes, because this is my normal procedure. Anyhow, just as soon as I placed the board in the developer, the resist started to disappear and the copper traces and pours appeared instead. :)

I am proud to announce that with the exception of three tiny pinholes in one of the copper pours, the 2 oz. board is immaculate.

idbruce
07-06-2014, 05:08 AM
I learned something new today.... PCBs can be scanned to giving amazing photo detail.

Referring to my previous post, I had my neighbor perform a quick scan of the board I made earlier today. And here is the result....

Please note that the copper looks much more shiny in hand, but I would imagine the scanned image, actually shows oxidation. As for the included illustrated image of the board, this was copied from a PDF file, which enlarges all the traces and such, but in reality, they are much smaller, as can be seen by the actual board.

This board was made as outlined in the previous post and the actual board size is 1.85 in. X 2.05 in.

109509