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Re: [Amps] Arctic Silver

To: Steve Thompson <>,
Subject: Re: [Amps] Arctic Silver
From: peter chadwick <>
Date: Thu, 12 Dec 2013 11:40:30 +0100
List-post: <">>

If the copper has been rolled there will have been some work hardening. It 
could well be worthwhile annealing it BEFORE doing the final milling. Same as 
one does for BMS (Bright Mild Steel)

Annealing copper is easy - get it red hot and then let it cool - or dump in a 
bucket of water. Although for tubing, that can lead to water boiling in the 
tube and shooting out of the open end.


Peter G3RZP

 Message Received: Dec 12 2013, 08:35 AM
 From: "Steve Thompson" <>
 Subject: Re: [Amps] Arctic Silver
 I'll echo other's comments about Arctic Silver, which I've used on 
 numerous high power transistor amps.
 Taking for granted that the copper heatspreader and main heatsink 
 are milled truly flat, the crucial thing is to get the transistor 
 flange flat as well. The majority I've handled are not anywhere 
 near flat, and always bowed upwards in the centre (something that 
 hasn't improved since the package style first appeared ~30 years 
 ago). I use the method mentioned by others - fine emery face up on 
 glass. Mirror glass is good, as it tends to be made better and any 
 imperfections in the surface show up.
 If the copper spreader is thick enough, the heat is spread over a 
 large enough area whereby the heat sink compound is less 
 significant and the regular white stuff can be used - but even 
 that varies in quality. I stick to Dow Corning or Emerson.
 Don't assume your copper spreader is flat just because it was 
 machined so in the workshop. Most of it is rolled and it's quite 
 normal for it to change a bit after the hard outer layer is 
 skimmed off (just like timber).
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