I had to take some time out to make some shims and shim up the cutter by another 1/16", but all is well at this point. I just finished cutting up (10) samples and all samples measure 0.937" X 0.937" (15/16" X 15/16"). How is that for accurately cutting 1/16" 2oz. double sided FR-4 board with photo-resist film and plastic protective layer?
And just so you know, the plastic protective layer is in good shape on all (10) sample boards.
Anyhow, now I will make the custom 15/16" X 15/16" exposure plate to fit my exposure box/cylinder.
As previously mentioned, it is my intention to expose and etch one side of the board with company information, however the other side of the board is wide open for a PCB exposure/etch challenge.
If anyone cares to design a 15/16" X 15/16" layout challenge, within reason, I would be more than willing to attempt the challenge. Any submitted layout should be accessible by PCB design freeware. Please feel free to submit your challenge. I do not know if I will be able to do it, but I will sure try.
Exposure Box/Cylinder Test #1 Parameters and Results
This specific post is set aside to set the parameters of testing and detail the final results. At this point in time, I am not concerned with the speed of the exposure process. The goal of this test is to produce a high quality exposure and etching. Considering the variables of this procedure, I will not post all results or methods. I will only post the final results that produce the best board.
Exposure Unit: My PCB Exposure Box/Cylinder listed at the beginning of this thread.
PCB Material: Philmore DATAK Premier Series (1/16" 2oz. double sided FR-4 board with positive acting photo-resist film)
Test Size: 0.937" X 0.937"
Test Pattern: Gradient lines 0.010" - 0.075" in 0.005 increments.
Positive Medium: Laser printed Vellum
Exposure Lamps:
This is a trial and error test procedure, bulbs used will be listed in chronological order of testing. All the bulbs listed are of the "clear" type.
(2) New 60W/120V Sylvania A15 Ceiling Fan Light Bulbs (60A15/CL/2PK/BL)
(2) New 40W/120V Sylvania A15 Ceiling Fan Light Bulbs (40A15/CL/2PK/BL)
(2) New 25W/120V Sylvania G16.5 Light Bulbs (25G16.5/BL)
***NOTE: I could not find fan bulbs available in any wattage below 40 watts, so I had to change the complete bulb style from A15 to G16.5. Considering that I am no longer using fan bulbs for my exposures, I will have to be a little more careful with the bulbs. The previous fan bulbs had a vibration resistent filament, whereas the G16.5 base bulbs do not have this desirable feature. However it is worth mentioning that the G16.5 base bulb is more inline with the center of the exposure box as compared to the A15 base bulb.
Exposure Time: To Be Posted After Testing Is Completed
Final Developing Mixture: To Be Posted After Testing Is Completed
Final Etching Mixture: To Be Posted After Testing Is Completed
Just in case anyone is paying attention, after a minor problem of toner transfer to the PCB from the laser transparency, I have decided to start using vellum for my positive images. This will take a while longer for exposure, but it should help to further reduce the cost of making PCBs.
Considering the design of this exposure box/cylinder, heat buildup was causing me some various problems, especially when attempting exposures with vellum as a positive, because it requires a much longer exposure time. As an end result of this heat buildup, I decided to modify the exposure box to include (5) 1/2" ventilation holes in both the top and bottom cans. These holes have grommets inserted which further reduces the holes to a size of 3/8". My web site instructions have not been updated yet to include these modifications, but I will do that soon. To further reduce heat buildup, I have resorted back to using laser transparencies as my positive medium.
Anyhow enough of the mumbo jumbo. I initially started my testing with an exposure time of (10) minutes in association with the transparencies. At (10) minutes the boards were being over-exposed utilizing the setup as stated above, and the toner was transferring to the board surface. In an effort to curb over-exposure, the forementioned heat buildup, and toner transfer, I have steadily been reducing the exposure time. I am now exposing the samples for (4) minutes and they are starting to look pretty darn good with no toner transfer and a significant reduction in heat buildup. It is my intention to keep reducing the exposure time until an under-exposure situation develops and then bump it back up a notch.
Philmore DATAK recommends a (10) minute exposure with a 100 watt light bulb for their Premier presensitized positive acting boards. At this point in time, I am using less electricity by using a lower wattage bulb and much shorter exposure times.
after a minor problem of toner transfer to the PCB from the laser transparency,
What exactly is the problem? I have spent some time leaning on a hot iron trying to do this very thing,
and so I was just curious about why this would be a bad thing?
Please don't take my question the wrong way, It is not critisism, just curiosity on my part...
Keep up the good fun, looks like it's starting to pan out for you.
Yes, when you are attempting hot iron transfer of the toner it is a good thing, but when using photo imaging like I am attempting, you do not want to destroy your positive. Additionally, it was getting so hot that it was coating the whole board area with a protective coating, and therefore creating a board as if a negative was used for the process instead of a positive.
Oh duh, heh, good point about preserving the artwork for the next board.
I bet the artwork could also distort from the shrinking if the heat was too much..
Hey, wonder if it would help to hook up a vacuum to suck cooler air thru the exposure box during the hottest time?
At two minutes exposure time, the boards were coming out fairly nice, but there were a few flaws here and there. I believe the flaws are due to an inadequate positive image. As mentioned in a previous post, I had attempted to use vellum as a positive medium, but then returned to using laser transparencies. I abandoned the use of vellum, because of heat buildup within the exposure box. Considering that I am getting pretty decent exposures at (2) minutes using the transparencies, I now know that I initially was over-exposing these boards considerably, especially while previously attempting the use of vellum as a positive. It is an indisputable fact that I can print a much better positive on vellum as compared to laser transparencies, so I have decided to give vellum another try in an attempt to obtain a much better positive image. However, considering the (2) minute exposure time with the use of transparencies, I will start with this time and work my way up, and hopefully I can obtain a good exposure, before heat buildup becomes an issue.
As I mentioned, I am striving for perfection here, so please be patient. And please keep in mind that I am doing double-sided exposures. When I conquer this situation, there will be a nice system and method for making double-sided boards without the high dollar investment.
As previously mentioned, the smallest trace width on the samples is 0.010". When I conquer the current tasks, and when time permits, I will attempt to obtain much finer trace widths.
By using vellum as a positive medium, with a (2) minute exposure time, I am still getting a fairly decent exposure
The 0.010" trace width is in much better shape than it was when using the transparencies, however it appears that I need just a little more exposure time. Just a little more experimenting and I should have a very nice sample to show you guys.
I bumped it up to a (3) minute exposure time, and after developing, it appeared to be over-exposed. I then bumped it down to (1) minute exposure time, and now it is starting to really look good, however, it still appears to be slightly over-exposed.
Hello Bruce--
'
I have looked back at some of my test data I ran a month or so ago on exposures and how long to expose.
'
While most of my attention was focused on exposure time and the PH of my developer, I still made so notes on board temps and developer temps.
'
I have found that the exposure time is greatly affected by the temperature of the film on the board.(The board temp and the exposure environment temperature){Air Temp}
'
Here in Florida the temperature really swings during the winter months(80F to 25F). I can see in my test results are affected by this temperature swing now that I have looked at the board exposure temps.
'
I wasn't really looking for a constant board temperature in my first batch of PCB positive film test, So my logged data is a little sloppy.
I have some more DataK boards coming---I will log a lot more data on the next run.I also have some heaters to get the boards/development environment to a constant temperature before exposing.
'
Hope this helps with your exposure time issue.
'
P.S. I like the 3M-PP2500 transparency's
Hope all is well with you, have not heard from you in a while.
I am not going to say you are wrong, because you could be right, but I have done an enormous amount of research into this subject, and this is the first time that I have ever heard about board temperature considerations for the exposure process. As the name implies ("photo-resist"), it is light sensitive, just like a photographic film. Your main considerations for exposure should be, the amount of light used for the exposure, the amount of time for the exposure, and the distance of the film from the light source.
However, I do believe that during the developing process, board temperature can play an important role, but the temperature of the developer is more critical. I have found that photo-resist dissolves more easily in a warm to hot solution. I would pay more attention to the temperature of the developer solution as compared to board temperature. The same holds true for the etchant.
At this point in time, I have no accurate means for temperature control. I am simply exposing the boards within my exposure box and then placing the boards into very warm ("almost hot") developer. For heating the developer, I am filling a glass ashtray with developer, and then placing it on a coffee maker. It works great, but I wish I had some temperature control for this arrangement. I use a similar setup for etching.
I wish you could be here for all the experiments that I am doing. I am sure you would find it to be quite interesting. As mentioned in my last post, I am getting pretty decent exposures at (1) minute using 60 watt light bulbs for exposures and using vellum for my positives. Instead of reducing my exposure time below (1) minute to obtain a better exposure, I have decided to reduce the wattage of my light sources to 40 watts, and perhaps increase the exposure time. That is (1) 40 watt bulb per board side. I think I may be able to gain a little better exposure control by going with smaller light bulbs.
I use cold NaOH solution for development, it takes under 30 secs.
Etching is in FeCl3 solution using a small plastic etchant container in an old washing-up bowl with some just boiled water in it. It takes about 5 minutes with continuous agitation.
It must be something particular about this photoresist. It just does not develop in cold developer. The minute you warm it up, no problem. Additionally, the manufacturer (or distributor) recommends a developer temperature between 100 and 110F. Depending on the concentration of the mixture and the temperature of the developer (luke warm, warm, hot ), it takes anywhere from 30 seconds to 2 minutes.
As for the etching process, I have found that etchings occur more rapidly when the etchant is pretty darn warm. I have one of those bubble agitators for etching, but the coffee maker heater blows it away
Bruce
EDIT: Eventually, I will combine a heater in combination with a bubble agitator.
That's very strange. I've only used a couple of brands of pre-coated boards but they both develop very quickly in cold developer. You must have different resist in the USA.
I bought a cheap heated bubble etcher. It took ages to heat up, and didn't work properly, so I went back to my manual technique. One of the local colleges has a spray etching system and that is very impressive.
The light bulbs within the exposure box have been changed from 60 watt to 40 watt and a sample has been exposed for a period of (1) minute. This is the best exposure so far, but still not perfect. I am now heading back to the hardware store to get some 25 watt bulbs.
A cold developer is not going to work. The temperature should be above room temperature (about 100 to 110 degrees F) .
In the research that I have done on photo-resist film, this stuff does seem pretty unique. The boards are distributed in the U.S.A., but I am unsure where the film comes from. I sure would like to know who makes the film and how to obtain it.
Yes, it does seem very different from the positive dry-film resist used with the boards available here. It's available in the USA as well, of course. This material doesn't need a safe light, and UV light is essential. I've always found it very easy to use, provided it's quite fresh; it doesn't work very well when it's more than a few months old.
I love this stuff, but it is so darn expensive. The boards that I am testing with now were purchased approximately two years ago, so the shelf life is good as far as that goes. The fact that these boards can be exposed with a standard light bulb makes them a very attractive alternative as compared to UV exposure units and the expensive UV bulbs.
I just purchased (2) new 25 watt bulbs for $2.40 and I still expect about a (1) minute exposure time.
Additionally, pertaining to the safe light, I am just working in a location where there is a 60 watt light bulb about 14 feet away, but I am also attempting to block stray light rays from hitting the board.
When I get finished with this sample, you may want to review your choices
I just added three more gradient traces to the business info side of the sample, these trace widths are 0.008, 0.006, and 0.004. I don't know if I can achieve this yet, but I already have a 0.010 trace width looking pretty darn good.
That is very cool! Yea, from all of your posts that I have found scattered here and there across the internet pertaining to PCB creation, I would imagine that you have been doing this for quite some time, and have become quite good at it.
Over 35 years, using various techniques. I started by designing the layout on 0.1" graph paper, marking the holes with a punch, and painting the tracks on the copper.
Comments
I had to take some time out to make some shims and shim up the cutter by another 1/16", but all is well at this point. I just finished cutting up (10) samples and all samples measure 0.937" X 0.937" (15/16" X 15/16"). How is that for accurately cutting 1/16" 2oz. double sided FR-4 board with photo-resist film and plastic protective layer?
And just so you know, the plastic protective layer is in good shape on all (10) sample boards.
Anyhow, now I will make the custom 15/16" X 15/16" exposure plate to fit my exposure box/cylinder.
As previously mentioned, it is my intention to expose and etch one side of the board with company information, however the other side of the board is wide open for a PCB exposure/etch challenge.
If anyone cares to design a 15/16" X 15/16" layout challenge, within reason, I would be more than willing to attempt the challenge. Any submitted layout should be accessible by PCB design freeware. Please feel free to submit your challenge. I do not know if I will be able to do it, but I will sure try.
Bruce
This specific post is set aside to set the parameters of testing and detail the final results. At this point in time, I am not concerned with the speed of the exposure process. The goal of this test is to produce a high quality exposure and etching. Considering the variables of this procedure, I will not post all results or methods. I will only post the final results that produce the best board.
Exposure Unit: My PCB Exposure Box/Cylinder listed at the beginning of this thread.
PCB Material: Philmore DATAK Premier Series (1/16" 2oz. double sided FR-4 board with positive acting photo-resist film)
Test Size: 0.937" X 0.937"
Test Pattern: Gradient lines 0.010" - 0.075" in 0.005 increments.
Positive Medium: Laser printed Vellum
Exposure Lamps:
Exposure Time: To Be Posted After Testing Is Completed
Final Developing Mixture: To Be Posted After Testing Is Completed
Final Etching Mixture: To Be Posted After Testing Is Completed
Please stay tuned
Considering the design of this exposure box/cylinder, heat buildup was causing me some various problems, especially when attempting exposures with vellum as a positive, because it requires a much longer exposure time. As an end result of this heat buildup, I decided to modify the exposure box to include (5) 1/2" ventilation holes in both the top and bottom cans. These holes have grommets inserted which further reduces the holes to a size of 3/8". My web site instructions have not been updated yet to include these modifications, but I will do that soon. To further reduce heat buildup, I have resorted back to using laser transparencies as my positive medium.
Anyhow enough of the mumbo jumbo. I initially started my testing with an exposure time of (10) minutes in association with the transparencies. At (10) minutes the boards were being over-exposed utilizing the setup as stated above, and the toner was transferring to the board surface. In an effort to curb over-exposure, the forementioned heat buildup, and toner transfer, I have steadily been reducing the exposure time. I am now exposing the samples for (4) minutes and they are starting to look pretty darn good with no toner transfer and a significant reduction in heat buildup. It is my intention to keep reducing the exposure time until an under-exposure situation develops and then bump it back up a notch.
Philmore DATAK recommends a (10) minute exposure with a 100 watt light bulb for their Premier presensitized positive acting boards. At this point in time, I am using less electricity by using a lower wattage bulb and much shorter exposure times.
Still striving for perfection!
Bruce
A (3) minute exposure looks much better than a (4) minute exposure.
When you say What exactly is the problem? I have spent some time leaning on a hot iron trying to do this very thing,
and so I was just curious about why this would be a bad thing?
Please don't take my question the wrong way, It is not critisism, just curiosity on my part...
Keep up the good fun, looks like it's starting to pan out for you.
-Tommy
I bet the artwork could also distort from the shrinking if the heat was too much..
Hey, wonder if it would help to hook up a vacuum to suck cooler air thru the exposure box during the hottest time?
-Tommy
(2) minute exposure looks better than (3) minute exposure
At (2) minutes exposure time, heat is barely an issue at this point.
Here is the latest update.
At two minutes exposure time, the boards were coming out fairly nice, but there were a few flaws here and there. I believe the flaws are due to an inadequate positive image. As mentioned in a previous post, I had attempted to use vellum as a positive medium, but then returned to using laser transparencies. I abandoned the use of vellum, because of heat buildup within the exposure box. Considering that I am getting pretty decent exposures at (2) minutes using the transparencies, I now know that I initially was over-exposing these boards considerably, especially while previously attempting the use of vellum as a positive. It is an indisputable fact that I can print a much better positive on vellum as compared to laser transparencies, so I have decided to give vellum another try in an attempt to obtain a much better positive image. However, considering the (2) minute exposure time with the use of transparencies, I will start with this time and work my way up, and hopefully I can obtain a good exposure, before heat buildup becomes an issue.
As I mentioned, I am striving for perfection here, so please be patient. And please keep in mind that I am doing double-sided exposures. When I conquer this situation, there will be a nice system and method for making double-sided boards without the high dollar investment.
As previously mentioned, the smallest trace width on the samples is 0.010". When I conquer the current tasks, and when time permits, I will attempt to obtain much finer trace widths.
Bruce
By using vellum as a positive medium, with a (2) minute exposure time, I am still getting a fairly decent exposure
The 0.010" trace width is in much better shape than it was when using the transparencies, however it appears that I need just a little more exposure time. Just a little more experimenting and I should have a very nice sample to show you guys.
Bruce
I bumped it up to a (3) minute exposure time, and after developing, it appeared to be over-exposed. I then bumped it down to (1) minute exposure time, and now it is starting to really look good, however, it still appears to be slightly over-exposed.
I am now thinking (30) seconds
I just don't comprehend, but I like it
'
I have looked back at some of my test data I ran a month or so ago on exposures and how long to expose.
'
While most of my attention was focused on exposure time and the PH of my developer, I still made so notes on board temps and developer temps.
'
I have found that the exposure time is greatly affected by the temperature of the film on the board.(The board temp and the exposure environment temperature){Air Temp}
'
Here in Florida the temperature really swings during the winter months(80F to 25F). I can see in my test results are affected by this temperature swing now that I have looked at the board exposure temps.
'
I wasn't really looking for a constant board temperature in my first batch of PCB positive film test, So my logged data is a little sloppy.
I have some more DataK boards coming---I will log a lot more data on the next run.I also have some heaters to get the boards/development environment to a constant temperature before exposing.
'
Hope this helps with your exposure time issue.
'
P.S. I like the 3M-PP2500 transparency's
Hope all is well with you, have not heard from you in a while.
I am not going to say you are wrong, because you could be right, but I have done an enormous amount of research into this subject, and this is the first time that I have ever heard about board temperature considerations for the exposure process. As the name implies ("photo-resist"), it is light sensitive, just like a photographic film. Your main considerations for exposure should be, the amount of light used for the exposure, the amount of time for the exposure, and the distance of the film from the light source.
However, I do believe that during the developing process, board temperature can play an important role, but the temperature of the developer is more critical. I have found that photo-resist dissolves more easily in a warm to hot solution. I would pay more attention to the temperature of the developer solution as compared to board temperature. The same holds true for the etchant.
At this point in time, I have no accurate means for temperature control. I am simply exposing the boards within my exposure box and then placing the boards into very warm ("almost hot") developer. For heating the developer, I am filling a glass ashtray with developer, and then placing it on a coffee maker. It works great, but I wish I had some temperature control for this arrangement. I use a similar setup for etching.
I wish you could be here for all the experiments that I am doing. I am sure you would find it to be quite interesting. As mentioned in my last post, I am getting pretty decent exposures at (1) minute using 60 watt light bulbs for exposures and using vellum for my positives. Instead of reducing my exposure time below (1) minute to obtain a better exposure, I have decided to reduce the wattage of my light sources to 40 watts, and perhaps increase the exposure time. That is (1) 40 watt bulb per board side. I think I may be able to gain a little better exposure control by going with smaller light bulbs.
Bruce
Etching is in FeCl3 solution using a small plastic etchant container in an old washing-up bowl with some just boiled water in it. It takes about 5 minutes with continuous agitation.
It must be something particular about this photoresist. It just does not develop in cold developer. The minute you warm it up, no problem. Additionally, the manufacturer (or distributor) recommends a developer temperature between 100 and 110F. Depending on the concentration of the mixture and the temperature of the developer (luke warm, warm, hot
As for the etching process, I have found that etchings occur more rapidly when the etchant is pretty darn warm. I have one of those bubble agitators for etching, but the coffee maker heater blows it away
Bruce
EDIT: Eventually, I will combine a heater in combination with a bubble agitator.
I bought a cheap heated bubble etcher. It took ages to heat up, and didn't work properly, so I went back to my manual technique. One of the local colleges has a spray etching system and that is very impressive.
The light bulbs within the exposure box have been changed from 60 watt to 40 watt and a sample has been exposed for a period of (1) minute. This is the best exposure so far, but still not perfect. I am now heading back to the hardware store to get some 25 watt bulbs.
It is looking very promising.
Yea, I have seen those spray etchers online. They are indeed very impressive.
Please refer to the section "Develop the board:" within the following linked document.
http://www.philmore-datak.com/datakpos.html
In the research that I have done on photo-resist film, this stuff does seem pretty unique. The boards are distributed in the U.S.A., but I am unsure where the film comes from. I sure would like to know who makes the film and how to obtain it.
I love this stuff, but it is so darn expensive. The boards that I am testing with now were purchased approximately two years ago, so the shelf life is good as far as that goes. The fact that these boards can be exposed with a standard light bulb makes them a very attractive alternative as compared to UV exposure units and the expensive UV bulbs.
I just purchased (2) new 25 watt bulbs for $2.40
Additionally, pertaining to the safe light, I am just working in a location where there is a 60 watt light bulb about 14 feet away, but I am also attempting to block stray light rays from hitting the board.
Bruce
http://www.megauk.com/pcb_laminates.php
I usually use the FPC 16 material, as it's so easy to cut and drill.
When I get finished with this sample, you may want to review your choices
I just added three more gradient traces to the business info side of the sample, these trace widths are 0.008, 0.006, and 0.004. I don't know if I can achieve this yet, but I already have a 0.010 trace width looking pretty darn good.
Bruce
That is very cool! Yea, from all of your posts that I have found scattered here and there across the internet pertaining to PCB creation, I would imagine that you have been doing this for quite some time, and have become quite good at it.
Bruce