Homebrew PCBs

----- Original Message ----- 
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, May 26, 2005 10:45 AM
Subject: Re: RE : [Homebrew_PCBs] Plated through holes


> On Thu, 26 May 2005 11:28:21 +0200, Thomas <teecee@...> wrote:
>
>> I was at a machine shop here in Jakarta several weeks ago and they do
>> selective plating etc for Aircraft parts, they had also repaired
>> an Engine Block in a camshaft bore using a Coloidal Copper solution
>> (IIRC) applied with Electrolysis,
>> my first thought was to use this solution to plate via holes also, but
>> of course the hole must be conductive for this to work so maybe
>> the conductive silver pen will have to be used first to get the process
>> working. I dont know about the price but looking at the amount
>> they chew through 1liter would last me a long time if it worked ok.
>> http://www.brushplating.com/
>> Thomas
>
>
> Well, hole wall activation is apparently the hardest part of it all.
>
> Silver paint costs like 1eur/g, so it is relatively expensive. there is
> much cheaper conductive graphite paint, and ideas if that can be used for
> hole wall activation?
>
> Even if that works i am not sure it is suitable for my style of making
> pcbs, which is quick and cheap.
> Toner transfer is not really compatible with THP, because it can't tent
> the holes. What you'd have to do is transfer the negative (which raises a
> number of problems in itself), and then plate with tin, which in turn
> requires a change of etchant to sulphuric/H2O2 instead of CuCl.
>
> Considering the work you need to add (2 plating baths, more complicated
> etchant, wall activation), and the costs, i will rather stay with using
> pieces of wire for vias. I mean, unless you do it for the advantage of
> having a PCB in an hour, financially it does not seem justifyable to make
> homebrew PTH boards. The prices for boards are incredibly low nowadays...


A small PCB company I know who had just been making non-PTH PCBs decided to 
install the equipment for PTH. I think it took a couple of months before 
they got the process working reliably.

Leon