Homebrew PCBs

On Sat, 16 Apr 2005 08:27:21 -0000, ballendo <ballendo@...> wrote:

>
> Hello,
> Can I ask a really dumb question?
> When I visit my board house (they're local and let me "tour" as I
> wish; a 900x certified facility) I see ALL their plating and etching
> baths using vertical board holders closely spaced in large tanks.
> No slanted walls, No bubbles. But here IS good recirculation of the
> etchant. (They do acid etching, AIRC)
> If it works for them; why doesn't it work for us?
> Ballendo


It does work for us, however if i have uneven etch that limits resolution  
and min. track width as the faster portions get etched more. True i do not  
really currently need more resolution than i can get, but i still like to  
solve problems.


> P.S. A buddy bought a commercial spray etcher from a closing low
> volume PCB fab house (They mostly stuffed boards, so were not really
> a PCB mfr. Had the spray etcher to be "complete" I guess.)
> Nothing special about it. Again boards/panels held vertically, with
> SS spray jets on each plexiglas side--might have been polycarb
> instead of acrylic? It WAS clear--and about 2' high by 3 feet wide
> and about 4-6 inches thick The spray nozzles were on about 8 inch
> centers The spray form was a flat cone, and they overlapped about 1/3
> cone. (So there was a spray line about every 2-2/3 inches)
> I'm pretty sure it had a back and forth motion to the board holder;
> kinda like Markus Zingg's THP line setup, only 90 degrees turned Like
> duck decoys at an amusement park shooting range.
> The etchant was clear (AP?)
> Worked like a charm; but took up too much space for him so he sold it.
> So the second question is, since we know spray etchers work, why are
> they so hard to duplicate?

Because those manufacturers spend a lot of money and time to develop these  
machines. I have no doubt it can be done (some have), but the simple and  
cheap solution i had aimed for didn't work out for me.

ST