ISSUE:
The op-amps are Class-A biased for a portable audio headphone amp. They only become problematic during hot weather.

SOLUTION: I need to adhere some small heatsinks to SOIC (SOP) op-amps.

I do know about $$ glue options like MG Chemicals or Artic Silver:
https://www.digikey.com/en/products/detail/mg-chemicals/8329TFF-25ML/9608260
https://www.arcticsilver.com/arctic_alumina_thermal_adhesive.htm

Not sure what the secret sauce is behind these pricey products.
I am wondering whether a more conventional product might not work? Such as automotive gasket material or some variety of JB Weld. I think JB Steelstick might be okay -- not sure. The epoxy/glue absolutely cannot be a THERMAL INSULATOR.

BTW: I do have double-sided thermal tape, but it's pretty much useless at small surface area (sink pr IC can't adhere).

 

Why use current-hungry class-A? Audio outputs today are low current and low heating class-AB and class-D.

 

Why use current-hungry class-A? Audio outputs today are low current and low heating class-AB and class-D.

This thread is not about amp classes and choices. Please stick to the orig topic.

 

This thread is not about amp classes and choices. Please stick to the orig topic.

Rather abrupt, but a valid point!

 

Anything rubbery, like gasket maker, will likely be more of an insulator. I believe thermal conductivity of JB Weld is also relatively poor. How big are the parts, and is there room around them? Also is this your own PCB design or a commercial one? If it's your own PCB, maybe spin a new version and just put a whopper ton of copper under and around those chips, maybe even an exposed pad under them if possible.

Or if it's not your design, but there's room around them, perhaps you can use a metal bar or heatsink that is much larger than the chips with significant overhang, then use thermal paste or double sticky tape just to connect the chips to the heatsink and then use the area around the chips to physically retain the heatsink, either with clips or non-thermal epoxy, etc..

 

The "secret sauce" is powder of something thermally conductive, like silver (which can make the epoxy also electrically conductive) or alumina (less thermal conductivity, but an electrical insulator).

J-B Weld doesn't appear to publish thermal conductivity of their products, but according to this article it is 7.47 W/m-K.

I've not used their products, but Atom Adhesives sells an epoxy "based on a silver coated ceramic" in small quantity, with thermal conductivity specified at 13 W/m-K.

Of course, if you use an electrically conductive epoxy, be sure not to bridge pins of the IC while attaching the heat sink.