Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "Tony Harris" <tony@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, January 22, 2004 5:01 AM
Subject: [Homebrew_PCBs] double sided pcb's - thruhole question.


> Hi all,
>
> I'm having a little trouble and I'm hoping someone here might be able to
> help.
>
> Several of my pcb's are double sided - it's taken some practice aligning
> both sides for proper etching, but I'm getting the hang of it, but I've
run
> into another problem....
>
> Let's say you have a part - an IC socket, some traces run from the top
pads,
> and some traces run from the bottom pads and some run from both.
>
> Normally, the hole would be thruplated creating a connection between both
> sides of the pad, but I don't have any kind of thruplating equipment. So,
> How do you all compensate for this? Solder doesn't seem to want to flow
> thru the hole and I've found myself removing sockets trying to figure out
> how to make connections on the top pads to the bottom where one solders.
>
> Now on places where the chip is installed permanently, I'm just soldering
> both top and bottom pads, so no direct connection between top and bottom
is
> required.
>
> Any ideas on how to solve this, without purchasing more chemicals or
> equipment, would be most appreciated.

If you use turned-pin sockets, you can just about solder the pins on the top
and bottom if you raise them slightly.

You might be able to put thin wire down the holes next to the pins, and use
that for the through-board connection. Tricky, but I've heard of people
doing it.

Or, you could design your boards so that a via is used for the through-board
connection (the ICs should just have pads on the bottom layer) instead of
the pins, then connect the top and bottom pads of the vias with wire. I can
do this quite easily with the PCB software I use (Pulsonix).

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html