| previous by date | index | next by date |
| previous in topic | topic list |
Fred,
I use both positive photoresist (pre coated boards) and negative photoresists (laminated at home).
The positive resist is thin and fragile. It does not hold up to the sponge technique. In fact it gets erroded noticeably by my rotary spray etcher if I am using old ferric that had had much brass in it.
The negative photoresist is much more robust. it actually takes some effort with a sharp knife to scrape it away.
---In Homebrew_PCBs@yahoogroups.com, <homebrew_pcbs@yahoogroups.com> wrote:Thanks for your comments. It's good to know that people on here are interested in more than just how to do toner transfer.
I think the ziplock bag would have had minimal attenuation. Whilst there was a little air in it, it was above the waterline of the bath. I suspect the rigid plastic container would have attenuated more. The cleaner claims to be 50W and 45kHz. I may make a bubble etch tank (or maybe even spray) but thought I'd try something different.
If it looked like it made any difference I would consider modifying the cleaner or coating the bath, but as it appeared to be nothing it would seem a bit pointless to destroy it.
I tried the sponge technique when an etch started well but then seemed to stop. It worked well, but definitely affected the thinner tracks and small text. I used photoresist boards so perhaps a little more delicate than toner.
Fred
---In homebrew_pcbs@yahoogroups.com, <jan.kok.5y@...> wrote:Thanks for reporting those results. I would suggest/request that you try "washing" the board with etchant using a small piece of sponge.I've tried that, using a soft amber colored plastic (polyethylene?) foam sponge and it seems to work maybe twice as fast as the sloshing method.