To Johnson777717 RE: His Electro-Etch Question

[chemelec]

I don't use Resist Pens at All. I computer draft my boards, Print off a Positive onto Mylar and use a photographic process to transfer the image to the board.
I bought 300 sheets (3 ft by 4 ft sheets) of Raw PCB at $1.00 sq ft. Good price. I cut these into 12 by 18 inch pieces and coat them with "Shipleys" Auto-Positive Resist.

Resist Pens are almost useless if you want Quality and the Iron On Transfers are good, but Too Expensive for production runs.

However, Almost Any reasonable resist will work in my Electro-Etch Process. If they stand up to Ferric Chloride, the should work OK.

For those reading this that maybe also interested in this process, Go to:
**broken link removed**

Take care.........Gary

 

[Johnson777717]

Thank you for your follow up Chemelec!

I've been using etch resist with ink pens for school work. The demand for PCB's has increased due to my interest in different types of circuits, so drawing PCB's hasn't been the most efficient process, as you know.

With that said, I think I'll take a step up to the Photo process, to further the efficiency, and allow PCB's with fine traces (for digital work etc.). I'm nowhere near a production state (like you) but your article intrigued me, especially with the electro static bath. I WISH I could get small quantities of PCB for $1 sq ft!!! Man, what a blessing that would be. I'm currently working off of $8 sq ft from a local supplier (Circuit Specialists). The price reduction would come in handy for the prototypes, and school work. I suppose that kind of price reduction is only available in large quantities.

Nevertheless, thank you for your reply. I was curious how the etch resist held up against the acid bath. Seems to be no problem with Shipleys eh?

 

[pike]

Iron On Transfers are good, but Too Expensive for production runs.

I'm currently experimenting by making my own sheets of these. I use mylar sheets and coat it with a solution of clay and water. The clay simply acts as a release agent allowing the resist to peel of easier from the mylar sheets. then leave the sheets to dry

the water simply is there to provide a better adhesion between the clay and water.

the problem with this is that the clay can wash off, contaminating the etchant(unless you wash it off before etching)

edit: i actually spray the clay solution on

 

[evandude]

Just use Epson glossy photo paper. It cost me 10 bucks for 40 sheets.

already has a clay coating on it, it irons on fine (use a piece of regular paper as a backing so it doesn't stick to the iron)
and you just toss the board/paper into hot soapy water for 10 minutes or so after ironing and it peels right off.

I've had good luck so far, and it works better as you get the hang of it... so far I've had little trouble running pads between IC legs, etc. so the accuracy is pretty good for a home process.

Note that it doesn't go through printers or copiers very easily since it's slippery. I run it through my laser printer (which lets it run almost straight through, no sharp corners) with a regular piece of paper taped on the back, and a little square of masking tape where the rollers first grab the paper from the tray. Give it a little help getting out of the tray by pushing gently and it usually goes through just fine.