Insufficient heat, basically.
Ground planes such the heat away and solder will not flow where the temperature is too low. You may need a hotter iron or to raise the temperature of the iron you have (if it is temp-controlled). When all parts of the joint are hot enough (not too cool, not too hot) the solder should flow right into it as you would expect. Don't feed more solder in than necessary to make a good joint. The excess will just cool the region more.
Make sure you heat the joint, not the solder. You might need to get a little solder on the tip of the iron the aid heat transfer, but don't expect to melt solder on the iron and have it flow into the joint. Heat the joint, then add the solder to it.
BTW, if you are starting a new thread, it's best to do so by sending a brand new email to the group <mailto://
Homebrew_PCBs@yahoogroups.com> rather than replying to an existing thread. Even if you change the subject line, your new email will be associated with the previous thread through identifiers in the hearders that the email systems of the world attach.
HTH,
Donald.
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----- Original Message -----
> From: "Steve Maroney" <steve@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, September 24, 2010 12:02:18 AM
> Subject: [Homebrew_PCBs] Trouble with through hole pads connected to plane
>
> Dear Gang,
>
>
>
> I'm having quite a bit of trouble when I solder a component lead (or
> jumper wire) to a through-hole pad that is connected to a ground plane.
> When I heat the component lead/pad and begin to apply solder, the solder
> flows outwards over the plane around the pad but not to the lead and/or
> pad itself. The more solder I continue to feed in just continues to
> build up outside of the pad. Every now and then , I'll get a pad that
> the solder will stay within, but most wont.
>
>
>
> I do NOT have a single problem soldering through hole pads NOT connected
> to a plane. Anyone else have this problem and/or know what the
> solution is or what Im doing wrong ?
>
>
>
> Love this list and thanks in advance.
>
>
>
> Best Regards,
> Steve Maroney
>
>
> Business Computer Support, LLC
> Mobile Phone:504-914-4704
> Office Phone: 504-904-0266
> Fax: 866-871-7797
>
>
[snip]