"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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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 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.
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.
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:
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.
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.
Comments
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
^^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.
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
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:
http://www.freestylephoto.biz/51455-Arista-Ortho-Litho-Film-2.0-4x5-50-Sheets
http://www.freestylephoto.biz/50022-Arista-Powder-A-B-Lith-Developer-1-Gallon
http://www.freestylephoto.biz/325000-Arista-Darkoom-Safelight-Red
http://www.freestylephoto.biz/4086-Arista-Premium-Odorless-Powder-Fixer-to-Make-1-Gallon
http://www.freestylephoto.biz/11912-Arista-Indicator-Stop-Bath-makes-3-Gallons
http://www.freestylephoto.biz/6170-Arista-Flow-Wetting-Agent-4-oz.
http://www.freestylephoto.biz/012057-Arista-Set-of-4-Developing-Trays-Accommodates-5x7-inch-prints-(White
http://www.freestylephoto.biz/2341-Paterson-Print-Tongs-(2)
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.
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.