Homebrew PCBs

The CW2200 pen idea is not mine.  Hero999 suggested it over at
ElectroTech in this Thread
<http://www.electro-tech-online.com/general-electronics-chat/93922-using\
-silver-loaded-paint-vias.html>  .  I would like to give it a try but
need to find a source for low temp solder 350°F (177°C).

My next project uses 44 pin TQFP's and need a method to connect the vias
under the chip that will not fall apart when the PCB is heated to
melt/reflow the solder paste.

I would like to see what would happen if one treated the hole with
CW2200 and heat cured it as suggested.  Then fill the hole with solder
paste and relfow it in oven or frypan. I know it is not low temp
soldering as suggested.


--- In Homebrew_PCBs@yahoogroups.com, "sailingto" <sailingto@...> wrote:
>
> Sounds like an interesting approach - I've also use the copper foil
from LaserPCB to putting traces on the bottom side of a board - works
pretty darn good - still have to use the low temperature solder, but
that's not a problem.
>
> 73 de Ken H>
>
> -- In Homebrew_PCBs@yahoogroups.com, "a3v03v0" a3v03v0@ wrote:
> >
> > Has anyone tried used a conductive pen such as the ITW Chemtronics
> > CW2200MTP for making vias conductive.  Once the via has been treated
> > with the pen it may be possible to solder it with a low temperature
> > solder.
> >
> > Found this
> >
> > "Curing: Tack-free in 3 to 5 minutes at room
> > temperature. Achieves electrical conductivity
> > within 30 minutes. Heat cure for 5 minutes at 250
> > to 300°F (120 to 150°C) for maximum conductivity,
> > durability and chemical resistance.
> >
> > Soldering: Low temperature soldering is possible
> > to the heat-cured silver conductive traces if done at
> > 350°F (177°C) for <5 seconds."
> >
> > Note: Solder iron tip temperatures are most commonly between
> > 315-371°C (600-700°F) for Sn63Pb37 and
> > Sn62Pb36Ag02 alloys.
> >
> > It looks like we have to use a low temp solder. SnIn20Ag2.8 may work
but
> > I have not found a source for it.
> >




[Non-text portions of this message have been removed]