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Keratherm Transistor Insulators

  • 1900


Problem: You need to use something to go between your transistors and heatsinks so they can transfer heat efficiently.

Thermal grease is a pain in the backside - it's painstaking to apply, it ends up stuck to everything within arms reach (certainly your fingers) and some preparations are highly toxic.

Solution: Keratherm.  Clean, efficient, effective and easy to apply.

This is a pack of 10 Kerafol Keratherm Red transistor insulators. Keratherm is regarded as the best insulator in the business. Unfortunately it's only available if you can buy a thousand at a time. To help out our fellow DIYers, we've split up a large roll into handy 10 packs, because we feel everyone should be entitled to use this awesome product.

The insulators are placed in-between the face of the transistor and the heatsink. The transistor will be electrically insulated but also thermally conductive - allowing the heatsink to heat up and dissipate the heat from the device.

This material is a single solution - there is no need to use thermal grease - just place the insulator between the transistor and heatsink.

The Keratherm Red material is silicone and fiberglass material impregnated with ceramic that is thermally conductive. In normal use it can match or even exceed the performance of mica and grease. It is ideal for Class-A and Class-AB power amplifier devces and anywhere you need a good thermal interface. 

Dimensions are 32mm x 23mm, which will fit TO-247, TO-3P, TO-218, and can be cut with scissors to fit TO-220 and smaller packages.  One side is smoother than the other.  We have consulted at length with manufacturer and they have advised us that either side can be used for heatsink or transistor.

We guarantee this is 100% original Keratherm Red sourced from the original manufacturer, Kerafol in Germany.

Usage notes:

  • Peel the pink "sliver" of Keratherm away from the backing (made of either plastic or a brown material)
  • The part you want to use is the thin, floppy, delicate "pink" colored soft material
  • Use of thermal grease is not recommended
  • See photos for an example of how to use it in a real life project


  • 10 Kerafol "Keratherm® Red" premium insulators
  • Model: 86/82
  • Format: XXXX-028 (To suit TO-247, TO-3P and TO-218)
  • Color: Red (Actually, a light shade of pink, and to quote the manufacturer "it varies from batch to batch")
  • Datasheet
  • Dimensions

Customer Reviews

Based on 36 reviews

Great product
Easier to use vs the mica insulators.

happy w. diyaudiostore

good job making available what you make available

As promised - highest quality

very happy with them. Nice to have a reliable supplier. I just wish they had more stuff available.


These electrical insulators/heat conductors are excellent ant easy to work with. NO MORE PASTE! Nice.

I like ‘em

A little pricey, but perform well and are very convenient.
I keep extras on hand, never can tell when the itch to build another Firstwatt clone might come along.

Nice to have always available

I bought many of them in the past years and I always want to have some spares in my lab. They are really great isolators, easy to use and with impressive performance.

Great product

Keratherm gave my aleph j build great thermal conduction. And DiyAudiostore are very reliable and have the best communication with me as costumer

Perfect for LM3886

Easy to apply with plenty of coverage for LM3886. In fact I had to trim a little with scissors and it was super easy to cut. My experience is that the pad will lightly "stick" to the chip or transistor while you are aligning everything, but not adhere so much you can't reposition it before final tightening. Transfers heat well - I'm pleased. Chip cool - heatsink warm. It's great having a source for hard t to find parts - thanks DIYStore!

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