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On Nov 26, 2007 6:20 PM, DJ Delorie <dj@...> wrote:
>
> Got one done:
>
> http://www.delorie.com/electronics/usb-gpio/
>
> The inner core is 1/2oz 32 mil DS. The two outer layers are 1/2oz 8
> mil SS, taped on with 3M 7953 laminating adhesive. TT (Pulsar), FeCl
> etch, MG Liquid Tin.
>
> Lessons learned:
>
> ∗ Keep track of which holes are which sizes on which layers. I got
> this wrong in a couple of places, and had to use an xacto knife to
> cut through the outer layers. There were a few places I drilled
> where I shouldn't have, but those were fixable.
>
> ∗ My process "bloats" copper, so I need to print it shrunk to
> compensate. I had to "edit" the etch resist before etching, and
> still had some shorts afterwards that I had to fix.
>
> ∗ I still can't manually iron on toner with any success. I tried the
> glossy magazine paper instead of the coated paper, just to see. It
> seemed like it would have worked, if only the toner had stuck to the
> board better. There's a fine line between "does stick" and "smears"
> that I keep passing through. I didn't try it with the laminator, as
> I was trying to use up some 1/16" stock.
>
> ∗ How to do fast vias: Wrap solder around the board, to hold it off
> the table a bit. Cut off a few inches of bare wire wrap wire.
> Stick wire through hole, solder, cut, repeat. Flip board, solder
> all the little bits of wire sticking out.
>
> ∗ Pin 4 is not ground on mini-B connectors :-(
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
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