On 1/20/2011 2:03 AM, Dave Platt wrote:

And, yes, if the heatsink actually comes loose from the Peltier
junction (e.g. if it was originally spring-clipped in place, and the
clips are loose or have fatigued and lost pressure) then you've got
problems... you'll get a layer of air between the two surfaces, and
thermal conductivity will become quite poor. Adding a thicker layer
of goop to try to fill the gap isn't the right thing to do - instead,
fix whatever caused the devices to become loose, clean the surfaces,
reapply a *thin* layer of compound, and secure the devices back
together with the proper amount of pressure.

I agree. The assembly goes like this:
Small heat sink (cold side) - square plastic gasket with embedded rubber
seal that doesn't physically touch anything - square block of Styrofoam
with a square cutout in the middle - Peltier device - foam tape around
the styrofoam - large heat sink. To screws go through everything on
either side of the Peltier to sandwich it all together.
And oddly they hot-glued the ends of the screws and nuts.

This is obviously made in China, everything is pretty crudely
manufactured and assembled, heat sink fins were mashed together in
spots. I didn't think to check the tightness of those two screws when I
took it apart, but I bet you are right and they weren't nearly tight
enough. I'm going to rebuild the 2nd one while I'm at it and will check
the tightness after I pry off all the hot glue...


--
-Scott