Another Wacky Idea for Making Circuit Boards

How many PCBs could you have made at Olimex by now? With the time and money you spent tilting at windmills? Just curious.

You could print glue with an inkjet-type printer and coat in copper pigment powder available at good artist supply houses. Still won't give you plated through holes or even a garantee of alignment between the layers. But I'd like to hear about what you'd do with copper pigment. (PS test to see if it's really copper by tossing it into a flame. Green is the color you want)

How about the old-fashioned el-cheapo way: eggwhite sensitized with potassium dichromate? Develop with the universal solvent: water...

Cool. Negative exposure, gold plate the traces, strip resist, and use the gold as etch resist for the copper. Make pot au creme with the egg yolks.

John

I've never heard of that..Does it work well? Also...I think powdered eggwhite exists and would that work? D from BC

Very cool! See for the albumen photo process:

Piece of cake, so to speak.

also:

Cheers, James Arthur

I did a little GoogleFu on this and found that gelatine can be used. Wikipedia mentions animal protein. D from BC

I looked at:

Casein is mentioned and I believe that's what's in Elmers white glue.. So maybe Elmers white glue + cancer causing potassium dichromate = negative type photoresist... Wonderful! :) When I was a kid..that cow on the label was always a mystery to me.. Cow bone glue.. :P

It's kinda like the potassium dichromate is the reverse of sunblock :) UV SPF -40 for extra burn :P (note the negative sign.) D from BC

All this reminds me of using potassium dichromate and sulfuric acid to make "chemist's cleaning solution," which I'd use to clean glassware. Wonderful stuff. To dispose, I'd have to reduce to chromium-III with sulfite salts and then neutralize that stuff with sodium bicarbonate or hydroxide (exothermic.)

Jon

Actually, Elmer was Elsie's "husband" in the Borden's Milk logo. Their "daughter" was Beulah. ... Just did a quick search, and apparently there is no such thing as "Borden's Milk" any more, just archival stuff. )-; ... Did a little more in-depth search, for images this time, hoping to see a logo, and imagine my surprise - Elmer's glue is made by Borden!

Cheers! Rich

Powdered eggwhite works just as well. The problems are that the "shelf life" of sensitized board is maybe a week or two, and the surface is sensitive to scratching (it is soft eggwhite). This "trick" has been around since at least the 1970's.

I'll keep an eye out for some potassium dichromate.. I think I can get it at photo supply shops..It might be pricy from the local chemical distributor..

...well this thread is about to fizzle out.. I'd like to lastly mention that nobody made fun of the obvious flaw that UV glue would glue the transparency to the PCB.. It might be very difficult to remove!

...but maybe some spray PAM or spray silicone on the transparency might help.. D from BC

Maybe going through all these gyrations is fun for you, but it sounds like a PITA to me.

I like the idea of printing the artwork on my dot-matrix, xeroxing it onto coated paper, and ironing it onto the board. The only chemical involved is the etchant, and you don't have to be in the dark to prepare the resist. :-)

Cheers! Rich

There have been a few XEROX and other printers that hav a flat (paper) pass-thru, and accept fairly thick "paper". AFAIK all of those are useable for *direct* printing of the pattern onto the PCB. Some of the first lazer copy machines were like that, and Lexmart "recently" (2-5 years ago?) had one like that.

As I've said before, old flatbed pen plotters, with a resist ink pen also worked well for direct printing of resist. Plot, dry, etch.

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Late at night, by candle light, Rich Grise penned this immortal opus:

Dot-matrix? How's the resolution with it? Do you print expanded and reduce the copy? I recall having done that with some artwork stuff at a time when laser-printers were affordable only to the rich and wealthy.

Personally I run photo-paper through my laser-printer and then do the thermal transfer thing. Takes a bit of experimenting with different brands and types but now I've found a good combination that lets me successfully do 0.1 mm (4 mil) traces. Not that I use such fine pitch for anything but lettering, standard is 0.4 mm (15 mil). Bit of a PITA to remove but the result compensates.

- YD.

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Toner transfer ...ugh.. :P I ordered dry-film photoresist to put an end to that.... D from BC