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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 40 reviews
Excellent results

I was worried that the fets in my F2J were running too hot with generic silicon rubber pads. With these Keratherm pads I have a 25% reduction in case temp of the fets. I can now sleep at night.....

David E.

excellent alternative to messy mica and grease.

Rick M.
Got them much quicker than i expected to

A great service having these made available by THE STORE.

Unlike many stores attached to websites - this one is well run.

Orders are sent out within hours of receipt.

A very good product

Easy to use and very friendly unlike that old mica
Does the job in efficiently providing electrical isolation with heat condution

Mattias Ö.

Great product
Easier to use vs the mica insulators.

amp b.3.
happy w. diyaudiostore

good job making available what you make available

Alan H.
As promised - highest quality

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

Niels G.

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

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