--- In
Homebrew_PCBs@yahoogroups.com, "pcb.easy" <rpdavidson@...> wrote:
>
> Red Devil no longer makes the 100% LYE crystals (THANK YOU METH HEADS)
> there is another brand called "ROOTO crystals of Household 100% LYE
> drain opener" this is what I now use to develop the positive resist
> on GC Pre-Sensitized Positive Acting PCB. Add 300mL of tepid water to
> the developing tray. Stir in 1/2 teaspoon of Sodium Hydroxide (LYE
> drain cleaner). Continue to stir until all of the Sodium Hydroxide is
> dissolved. Place circuit board into the developer and gently rock
> back and forth until all unwanted photo resist has been removed.
> Development should take less than 2 minutes. This method is fast,
> clean, and very cheap.
OK Thanks, I did find some Crystal Drano, Had thought I had seen
before some drain cleaner had Sodium Hydroxide but I had looked at the
liquid type before which used something else. The Crystal Drano works
good. The 1/2 teaspoon/300mL seemed a bit strong on some of my quick
test that I did. Added more water so it is maybe more like 1/2
teaspoon/400mL water. Still don't think I could leave it in there for
2 min. and have any resist left on the board.
Home Depot carries 3 different brands, Drano, some by Zep and then
one other but I can not think of the name and I think it was liquid.
Yes the Drano does have some metal in it but they for the most part
stay on the bottom.
With the M G Chemicals solution I normally brushed the board with a
foam brush but with this found that it was better to just stir the
solution with the brush. Take the board out just as soon as it looks
like resist has stopped coming off.
Even at just 1/2 teaspoon/400mL it seems to be stronger than the 10:1
solution of M G Chemicals.
Need to get going with my original project.
Ben