Thermally Conductive Insulator Pads for TO-3 Transistors

NavLinear

NavLinear

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I've been meaning to purchase some Bergquist Sil-Pads for the PL amplifier output drivers and came across this:

http://www.ebay.com/itm/T03-SIZE-TR...862?pt=LH_DefaultDomain_0&hash=item588d5b0a16

Not bad - $7.25 for 50 so I purchased two packs. I ordered them on Wednesday and they came in today. Shortly after I committed to the purchase and PayPal'd the funds I went back to eBay and scrolled down some and came across this:

http://www.ebay.com/itm/T03-SIZE-BE...059?pt=LH_DefaultDomain_0&hash=item1c080f232b

DAMN - I could have saved a few bucks. These are good prices for the Sil-Pads IMO.
 
Northwinds

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I remember when the pads were considered inferior to the white goop. I guess they have come aways eh?
 
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fitz43

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NavLinear said:
I've been meaning to purchase some Bergquist Sil-Pads for the PL amplifier output drivers and came across this:

http://www.ebay.com/itm/T03-SIZE-TR...862?pt=LH_DefaultDomain_0&hash=item588d5b0a16

Not bad - $7.25 for 50 so I purchased two packs. I ordered them on Wednesday and they came in today. Shortly after I committed to the purchase and PayPal'd the funds I went back to eBay and scrolled down some and came across this:

http://www.ebay.com/itm/T03-SIZE-BE...059?pt=LH_DefaultDomain_0&hash=item1c080f232b

DAMN - I could have saved a few bucks. These are good prices for the Sil-Pads IMO.
Click to expand...
I thought there once was talk here about different colour ones. One colour being better than the other. Was it green?
 
NavLinear

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Northwinds said:
I remember when the pads were considered inferior to the white goop. I guess they have come aways eh?
Click to expand...
I'm not sure of the earlier pads but they seemed to do a good job of transferring heat and provided good electrical isolation. If these were reused one could get into trouble quickly as they were prone to cracking and that is a bad thing.

Bergquist has been around a long time as have the Sil-Pads but I've never used them before. Wattsabundent (Don) mentioned some time ago that he gave up using the mica with silicone grease and used a pad that is either the Sil-Pad 400 or something similar. I immediately looked into this after Joe mentioned that he uses the Sil-Pad and enlightened us that the heat transfer coefficient of the Bergquist pad and the mica with grease were almost identical. With the Sil-Pad it's a one time use and you have to be careful of not over torqueing the fasteners. The cost of the Sil-Pad is more than the mica but that damn silicone grease is a PITA.
 
NavLinear

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fitz43 said:
I thought there once was talk here about different colour ones. One colour being better than the other. Was it green?
Click to expand...
Lee has a few of those that he received from Don. He may be able to shed more light on that, but I do remember green ones were used. Those should be saved for Jason. :iconbiggrin:

The Bergquist will work quite nicely for this application but other options are out there.
 
Gepetto

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NavLinear said:
Lee has a few of those that he received from Don. He may be able to shed more light on that, but I do remember green ones were used. Those should be saved for Jason. :iconbiggrin:

The Bergquist will work quite nicely for this application but other options are out there.
Click to expand...
The gray SIL400 pads in the 0.009" thick thickness are the ones to use. Similar to the ones Nav purchased.

There are a lot of low cost Chinese ones floating around but where would you get specs on them?? Not worth the risk IMO.
 
laatsch55

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Silly Nav, after everything you've sent me, all you had to do was say something and I would have sent you a handful..
 
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gadget73

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Hmm, here I thought the mica with the grease was the way to go. Pretty sure I've seen a TSB from Phase Linear about using mica instead of silicone because it causes oscillation problems or something.
 
wattsabundant

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gadget73 said:
Hmm, here I thought the mica with the grease was the way to go. Pretty sure I've seen a TSB from Phase Linear about using mica instead of silicone because it causes oscillation problems or something.
Click to expand...
I think the oscillation was due to over tightening or reusing a silpad when the transistor was changed out.

If anybody has time to do some controlled tests on temperature rise I'll supply the insulators. I've got a few thousand grays, several hundred green and a few hundred mica.

The green ones appear to be very similar to the salmon colored ones P/L used early on.
 
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