Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Russell Shaw <rjshaw@...> wrote:
>
> derekhawkins wrote:
> > I'm attempting to debunk the following two myths at the same time;
> > 
> > 1. A collimated light source is needed for .005" to .01" rules 
> when 
> > photoetching.
> > 
> > 2. All vertical bubble etching system cause uneven etching. Board 
> size 
> > is 6"X4" hung vertically as shown. 
> > 
> > http://www.pbase.com/eldata/6_6_rules
> 
> I've used a vertical bubble etcher for a few years and have no 
> uneven etching
> at all. These myths are in the same category such as "ferric 
> chloride is slow",
> "PRP doesn't work", etc.

I've used vertical bubble etchers, both homemade, and commercial (but 
cheaper models), and both of them caused terribly uneven etching. I 
suspect that 1) the strength of the air pump and 2) the size and 
placement of the bubbles have a lot to do with this. So if you have a 
vertical bubble etcher that works perfectly, post the name and model 
number of it. I don't remember where I got the commercial one that I'd 
bought, I think it was Electronics Express but I could be wrong. I 
threw it away about two years ago. It etched much, much faster where 
the bubbles hit the metal, and one edge would etch faster than the 
other. So I don't think this is entirely a myth, I think it has to do 
with the quality of the bubble etcher you buy.