Best heat transfer insulator

Silvio

Active member
I encuntered a dilemma what to choose as an insulator behind a power transistor. Is it a silicone pad, a mica pad or a ceramic pad.
Which of these deliver the best heat transfer to the heat sink? Which of these has the best electrical insulating properties? And lastly Safety.

All opinions are welcome. We can discuss and see one's opinion about this matter.
 

Silvio

Active member
Comprehensive cost concerns are mica pad.
Seeing a lot of commercial amplifiers, I find various types used. In good quality amplifiers like Herman kardon use mostly ceramic in class d amplifiers and where high voltage is present, other Chinese stuff you will probably find mica or silpads. My true question was which of these has the best heat transfer not concerning the cost. I tried looking on line but did not find a definite answer without a lot of complications. I guess the best is without an insulator at all where possible. This all cropped up when I had a couple of ceramic insulators for TO247 package. I was curious which was best between Mica or ceramic for best heat transfer.
Thanks for your reply. :) Regards Silvio.
 

edonky

New member
I happened to be in China,The most common here are alumina ceramic sheets,The specifications are top3,to220 to-3P ect.100 tablets for about $2.94;96% alumina,Thermal conductivity 29.3W/m.k,Insulation 22.5KV and heat resistance 1600 degrees.Do not look at the cost performance is the best material, civilian very little, mainly price.Regards edonky.
 

Silvio

Active member
I happened to be in China,The most common here are alumina ceramic sheets,The specifications are top3,to220 to-3P ect.100 tablets for about $2.94;96% alumina,Thermal conductivity 29.3W/m.k,Insulation 22.5KV and heat resistance 1600 degrees.Do not look at the cost performance is the best material, civilian very little, mainly price.Regards edonky.
Thanks for your reply, I also taught that ceramic had to be the best in this case thus having also the best insulating properties. The only mishap with them is that they need perfectly flat and clean surface as they break easily when tightened up. I usually sand the back of transistors with a fine sand paper to make sure there are no dents present before applying heat sink compound and assembling.
 
Top