Homebrew PCBs

----- Original Message ----- 
From: "DJ Delorie" <dj@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, December 08, 2006 3:44 PM
Subject: Re: [Homebrew_PCBs] Making hidden vias?


>
> "Stefan Trethan" <stefan_trethan@...> writes:
>> And how much fun would it be to place 300 vias a board, manually?
>
> More fun than soldering in 300 1/8" long wires.
>
>> Also, with 300 vias a board you only get 3 boards out of your 1000
>> pieces pack, for 15 pounds?
>
> A thought I had... #30 wire wrapping wire is only 10 mils diameter; an
> easy fit in a 13 mil hole.  If you can cut it so that the end is
> essentially flat (or flat enough), what you do is turn the board
> component side down on a flat surface and clamp/tape it down.  Then,
> insert #30 wire into each via hole, solder, trim.  When you flip the
> board over, the wires should be flush with the surface, and you may be
> able to solder them to the pads with minimal bump-out.  Not sure if
> it's flat enough for smd, but a copper braid may help to remove
> excess.
>
> I think if you have clearance issues under SMD parts, the solutions
> could include (1) not putting vias there, or (2) pre-soldering all the
> pads to raise the part up some.  Maybe smashing the #30 so it's
> thinner might help too.  Or build a home electroless plating tank ;-)

I try to avoid putting vias under SMD parts with homemade PCBs, but if I 
have to use them wire-wrap wire bent over doesn't cause too many problems 
provided I don't use too much solder.

Leon