Several (at least three) strands of very thin wire will wick much better than a single strand (which barely wicks at all.) Of course, one needs to make the through holes large enough to handle several strands.
Donald.
----- Original Message -----
From: "DJ Delorie" <dj@...>
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, December 16, 2009 5:18:49 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Homebrew_PCBs] 4 Layer boards
Harvey White <madyn@...> writes:
> Just solder making the connection between layers is not a good idea.
> If the connection is from a trace to a pit (what would be a blind via,
> not all the way through), I'd use a wire and solder it.
>
> If the connection is through a board (full via) connecting top and
> bottom layers, solder is not the way to go. There's no way to
> guarantee that the solder flows down into the hole and makes the
> connection.
Having tried these, I can pretty much guarantee that the solder will
∗not∗ go down the hole, or into the pit, or whatnot. Way too much
surface tension.
> The solder that helps hold them in place can wick down the wire, but
> is not the prime connection.
In my experience, it doesn't wick down the wire into the hole. You've
seen it happen with ∗plated∗ holes, but without plating, it just stays
at the surface.