Today, I tried to build a PCB of a programmer for PIC micro controller 16F628. I wanted to use an easy prototyping method and I decided to go for the method specified here and here.
Soon, I went out hunting for Ink jet photo quality glossy paper in a few shops, and they all were out of stock. Then i remembered a friend who owns a Image / graphics studio and he gave me 2 A4 sheets and did not take money for it even though I insisted a lot. His site is here. Those sheets were high quality Epson ones. Next trip, to my friend who has a high quality Laserjet Printer. I installed the Cadsoft Eagle software in his system and took a couple of printouts.
Once I had the printed sheets, came back home, and did the standard procedures, like cleaning the PCB, cutting it to the required size, not a clean cut, but I had a crude cut using a BIG hacksaw. I didn't have acetone (Thinner) here, so i cleaned my PCB with some Zippo Lighter fluid. Got my Clothes Iron and started ironing it, and the problems started. one layer at the back of the paper started melting, so I kept a backing paper behind it and continued ironing. And soon the backing paper got stuck to the photo sheet. First reaction was, so what?
Made a trip to the kitchen, and started boiling water for cooking my PCBs till the paper came out, but unfortunately, even after 30 minutes of continuous boiling torture, the paper wouldn't move!, and I let it stay there for another 30 minutes, and i finally removed the paper and found, that the toner did not get transfered fully. I had some partial tracks here and there. Which was not useful for me. Repeated with the other circuits and all of them failed.
I am unsure what made the process fail, was it the paper? the Zippo fluid? or an over heated Iron? I have no idea, But I guess I will try it again tomorrow. Will update this post with further findings and failure stories (hope not!) and observations about this comparatively easy trick. Making me insane thinking about what went wrong anyways.. so, lets see how it goes tomorrow.
Good night!
Dude, did you try the thermometer ?
ReplyDeletehi there from bombay. you did just about everything wrong (we all did the first time, so don't stop just because of that!)
ReplyDelete1. don't use lighter fluid. while harmless, i've noticed it leaves a resdue behind and is realtivey ineffective. stick to acetone and only acetone - no nail polish remover or the ilk.
2. the choice of paper. you'd be better off ripping out a sheet of thin glossy paper from, e.g. time magazine or india today. the type with a plasticky feel to it. the best results i got were using pages from a mail order catalogue - sadly, i don't have it anymore - i was living in germany and the catalogue was from a big mail order electronics supplier named conrad.
so no need for high-quality paper - waste of money - go for magazine pages instead. if they are too thin, tape them flush against a normal A4 sheet and print away. 600 dpi will do for most applications, i've printed up to 16 mil on 600 dpi.
3. ironing technique is critical - there should be NO steam whatsoever. do not iron back and forth. the problem with ironing is to ensure equal application of pressure. i used a dry iron, ran it in one direction a few times slowly, let the board cool down, turn it 90° and repeat for full 360°. this is trial and error. i used a backing paper or a thin handkerchief as well, because the paper finish sticks to the iron.
4. "cooking" the PCBs - BIG mistake. the only thing you need to do is soak the PCBs in lukewarm (about 25-30°) water with a drop of detergent. after about 10 minutes, the thin paper will be transparent at the non-black areas. you can (gently!) rub it off.
by boiling the board, not only did you remove the paper but probably melted any adhered toner right off the board!
this site is great, and gives excellent and simple instructions on making PCBs using the ironing method - i try and follow this method as far as possible. the laminator works like a dream - however, it is necessary to find one that reaches the correct temperature.
http://thomaspfeifer.net/direct_toner_pcb.htm
have fun!