A pair of colorful laser-cut stacked acrylic Raspberry Pi cases with “Moster” (*) heatsinks arrived, with the intent of dressing up the HP 7475A plotters for their next Show-n-Tell:
Unfortunately, the thermal tape on one of the CPU heatsinks was sufficiently wrinkled to prevent good contact with the CPU:
The seller sent a replacement copper slug with tape on one side. Presumably, they glue it to the heatsink with thermal silicone:
Of which, I have none on hand.
So I did what I should have done originally, which was to drop a few bucks on a lifetime supply of thermally conductive heatsink tape, apply it to the bare side of the slug and stick the slug to the heatsink with their tape:
The blue stuff is the separation film, with the tape being white. It doesn’t match the black tape on the other side, but seems gooey enough to work.
Done!
Despite the heatsink hype, ball grid array chips dissipate most of their heat through their pads (and perhaps a central thermal pad) into the PCB, so sticking a heatsink atop the package is largely decorative, along the lines of hotrod ornamentation.
The epoxy packages used in previous Raspberry Pi iterations had better thermal conductivity to their top surface:
Than the more recent metal-top packages, which surely have inert-gas fill under the lid:
Pix cropped after being pilfered from the Official Raspberry Pi site.
Yes, the heatsink does conduct some heat into the air, even if not nearly as much as you might want.
(*) I’m pretty sure “Moster” was a typo in the original eBay listing which took on a life of its own to become something of an unofficial trademark. All of the search results ship from Duluth, Georgia (USA), regardless of the nominal seller; feel free to draw your own conclusions.
The Smell of Molten Projects in the Morning 