Project: Photographic methods of making PCBs

Robin Mitchell

Joined Oct 25, 2009
819
Ok so I am shocked.

I did not bother adjusting xy scales but it appears that the rotational warp has gone because of the pre-heat!

KeepItSimpleStupid

Joined Mar 4, 2014
4,556
So then keep an eye on humidity and keep your transparency film in a zip lock bag.

I still like translucent polyester.

Paper is like chocolate. Storage of chocolate does it in. Once you taste Belgian or Swiss chocolate that has been stored properly, you'll never go back and it's drastically cut my consumption of everyday chocolate to nearly zero. It just tastes bad, so I'd rather go without.

Robin Mitchell

Joined Oct 25, 2009
819
So then keep an eye on humidity and keep your transparency film in a zip lock bag.
Will do.

Paper is like chocolate. Storage of chocolate does it in. Once you taste Belgian or Swiss chocolate that has been stored properly, you'll never go back and it's drastically cut my consumption of everyday chocolate to nearly zero. It just tastes bad, so I'd rather go without.
Note to self: Never eat Belgian or Swiss chocolate. That way I can keep eating the chocolate here in the UK!

KeepItSimpleStupid

Joined Mar 4, 2014
4,556

Lestraveled

Joined May 19, 2014
1,946
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KeepItSimpleStupid

Joined Mar 4, 2014
4,556
Not sure what tip your talking about: Humidity; the reference post on paper or chocolate?

BTW: KISS works.

Once you tasted Belgian Chocolate, you would wonder how "they" could make chocolate taste that bad.

Lestraveled

Joined May 19, 2014
1,946
I have fired my laser printer. It will never be used for PCB work ever again. I went back to my inkjet printer, played with the setting and can now produce denser, higher quality, PCB transparencies, using just two layer. The laser printer was very fast but the toner density was so inconsistent that when I printed a solid square, it looked like a topo map. The difference between the laser and the inkjet printers density and consistency was amazing. I get better density with two layers from the inkjet printer than with three layers with the laser printer.

Now that I only need two layers of transparency to get the density, I also do not need the litho film step in my procedure. (Because my laser printer was so crappy I had to use litho film to make a transparency with enough density to expose the PCB consistently.)

To sum it all up:
- I print two negative PCB image transparencies.
- I align them on my home built light table and scotch tape them together.
- I direct contact expose the image on to a piece of PCB that is sensitized with dry film resist.
- Develop and etch.

I am still a super fan of dry film resist. For you people that use the toner transfer method, you would use the same technique and equipment to apply dry film resist to a PCB. The stuff works freakin great and is cheap.

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cmartinez

Joined Jan 17, 2007
7,290
For you people that use the toner transfer method, you would use the same technique and equipment to apply dry film resist to a PCB
And where can I find dry film resist, for instance?

Lestraveled

Joined May 19, 2014
1,946
EBay, of course

Lestraveled

Joined May 19, 2014
1,946
The developer is sodium carbonate, I bought 10 pounds of it for $18 delivered. (A table spoon in one liter of water will develop a half dozen boards.) The stripper is household lye (sodium Hydroxide). Ace hardware <5$

@cmartinez

Lestraveled

Joined May 19, 2014
1,946
Here is a video that shows how to turn baking soda into washing soda (sodium carbonate).

cmartinez

Joined Jan 17, 2007
7,290
Here is a video that shows how to turn baking soda into washing soda (sodium carbonate).

Very interesting.... from the Wikipedia:

Sodium carbonate is also used as a relatively strong base in various settings. For example, it is used as a pH regulator to maintain stable alkaline conditions necessary for the action of the majority of photographic film developing agents. It acts as an alkali because when dissolved in water, it dissociates into the weak acid: carbonic acid and the strong alkali; sodium hydroxide. This gives sodium carbonate in solution the ability to attack metals such as aluminum with the release of hydrogen gas.
Is this why you posted the video? Oh the other hand, if the thing attacks aluminum, will it also attack copper?

Lestraveled

Joined May 19, 2014
1,946
No, I thought it to be an interesting way to make sodium carbonate. Everyone has baking soda in their cabinet or refrigerator.

DPHigley

Joined Dec 21, 2016
4
I've been working with photoresists for about a year now, not for PCBs but for jewelry, etching copper and silver. The basics are the same, though, and these posts constitute a gold mine of information that I can use. If the thread is still being looked at, I'd like to reply to several of the individual posts.

cmartinez

Joined Jan 17, 2007
7,290
I've been working with photoresists for about a year now, not for PCBs but for jewelry, etching copper and silver. The basics are the same, though, and these posts constitute a gold mine of information that I can use. If the thread is still being looked at, I'd like to reply to several of the individual posts.
Sure thing. All contributions are thoroughly appreciated.

Welcome to AAC, BTW.

nerdegutta

Joined Dec 15, 2009
2,676
If the thread is still being looked at, I'd like to reply to several of the individual posts.
Bring it on!

DPHigley

Joined Dec 21, 2016
4
Sure thing. All contributions are thoroughly appreciated.

Welcome to AAC, BTW.
Still learning how to use this forum, so please forgive screw-ups.
I got here because I'd been trying to find a better way to make masks for photoresists, and came up with the idea of using litho film to greatly increase contrast. I tried it with great success, which led me to believe it had been thought of before; so I did a web search, and sure enough!
As I mentioned previously, I'm into making jewelry with etching, rather than electronics. Some of the processes are much the same, but screwing up a circuit board will cost you just a few dollars, whereas screwing up a piece of silver will put you out $30 at least. I've done that more than once, and it's painful. So I'm motivated to learn all I can about the most reliable/dependable ways of working with photoresists. The posts by Lestraveled would, I think, be invaluable to others like me who are using photoresists for purposes other than PCBs, and I think it would be a good thing to have this information disseminated as widely as possible. Meanwhile, I would like to exchange some thoughts and ideas on this subject. David cmartinez Joined Jan 17, 2007 7,290 Still learning how to use this forum, so please forgive screw-ups. I got here because I'd been trying to find a better way to make masks for photoresists, and came up with the idea of using litho film to greatly increase contrast. I tried it with great success, which led me to believe it had been thought of before; so I did a web search, and sure enough! As I mentioned previously, I'm into making jewelry with etching, rather than electronics. Some of the processes are much the same, but screwing up a circuit board will cost you just a few dollars, whereas screwing up a piece of silver will put you out$30 at least. I've done that more than once, and it's painful. So I'm motivated to learn all I can about the most reliable/dependable ways of working with photoresists.
The posts by Lestraveled would, I think, be invaluable to others like me who are using photoresists for purposes other than PCBs, and I think it would be a good thing to have this information disseminated as widely as possible. Meanwhile, I would like to exchange some thoughts and ideas on this subject.

David
David, please have a look at this post, I'm not sure if it will help you, but it's an alternative to what's being discussed here.