[Openocd-development] PCB tips and tricks

[Tomek C. <tom...@gm...>]

Hello Michael! :-)

On Fri, Jul 8, 2011 at 8:18 PM, Michael Schwingen
<rin...@di...> wrote:
> Am 07/08/2011 08:30 PM, schrieb Tomek CEDRO:
> (..) Still I don't know any sensible method
>> to make drills metalization at home to produce advanced two layer
>> pcb... maybe you guys know some tricks? :-
> Simply drill the holes and solder both sides - with a thin wire if there
> is no THT pin. This may be a bit painful, but works quite well if you
> take care during layout so that you do not place vias under parts.

Yes, this is the obvious solution for low count VIAs, but I am
wondering on making something more useful to connect both layers on
PAD (that is when also some component use that hole) - this is
especially painful on connectors or other parts that hide top layer
when element is mounted...

> BTW: I found that PCB material that comes pre-coated with the photo mask
> works *way* better than positive-20, because you get consistent exposure
> times. Also, positive-20 tends to get bad shortly after the "best
> before" date, which was about a year when I used the stuff, while the
> pre-coated material can be stored a lot longer.

Thank you for this advice - I am actually using small 100ml Positiv20
spray far beyond expiration (03/09) and it works fine ha! I noticed
the NaOH must be fresh and the light source is very important
(mentioned philips 14552 12V/75W halogen/uv lamp gives best results of
all) and it can overcome Positive20 limitiations.. maybe thats also
because I give thick layer of fotopositive (dry it in oven) and strong
lamp. This photolitography method is really nice and far more reliable
than thermal-transfer, its not expensive, I can recommend it to anyone
that want to make precise pcb at home :-) For my applications this
quality is enough, maybe pre-coated boards are better but also far
more expensive...

Still, no solution/idea on how to make pads metalization at home
safely... there is a clear field for a patent, hey inventors wake up!
:-)

Best regards! :-)
Tomek

-- 
CeDeROM, SQ7MHZ, http://www.tomek.cedro.info