Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Ancel,

Thanks for the link.  He has some interesting approaches. I was with him all the way until the Nitric Acid.  Bad stuff in any concentration.  Luckily, this works with our more conventional etchants.

My issues with double sided are not registration, I use similar pins, but mine are the ones with the metal tops.  I found those to be more uniform in diameter from one pin to the next.  My problem has always been getting uniform etching on both sides.  At one point, I built a vertical bubble etcher with a heater for ferric chloride etching.  I arranged the bubbler such that I had coverage on both sides.  The results was that the edge of the board closest to the bubbler became over etched, while the area furthest away was only beginning to etch.  I envied the spray etchers my company used in their PWB production area. My best results were obtained by fully masking off one side while etching the other.  Tedious, but it works.

(Another) Harvey

 

You may find this useful:
https://hackaday.io/project/7938-pcb-smt-maker-lab-home

I do single pass toner transfer -double sided with good registration
permitting a single etch .
Ancel