[sdiy] SMD experiences

[Dave Manley]

On 9/9/2011 2:43 AM, Colin f wrote:
>
>> What's a "thermal relief pad" and why would I only need one
>> for through-hole?
>
> If your thru-hole has no relief, it can feed too much heat into the inner
> layers, increasing the risk of de-lamination.
> It can also suck too much heat out of the joint during soldering, causing a
> cold joint.
> This applies to fills on top and bottom layers too, particularly where you
> have a component that can soak up a lot of heat itself, such as the legs on
> a vertical pot.
> Maybe not so much of a problem where you are hand, rather than
> wave-soldering.

In addition, it is important when desoldering. If you have a thru hole that has
unrelieved pads, it can be very difficult to pump enough heat into the joint
to allow desoldering.  If you never have to change or fix anything - no prob :-)

http://en.wikipedia.org/wiki/Thermal_pad_%28electronics%29
http://www.pcbwizards.com/Glossary20.htm

-Dave