Fast & Cheap Sources for Non-Standard Size Thermally Conducting Insulators?

[rjb]

I need to replace the Thermalsil pad that backed a barbecued TDA7294 amplifier chip in an Anchor powered speaker.
http://www.st.com/internet/com/TECHN...CD00000017.pdf

The amp's nominal package size is .772"W x .689"H (19.6mm x 17.5mm)
Aavid does not sell this configuration as a standard size pad.

I assume Anchor cut their own pads from bulk Thermalsil rolls.
Mouser does not normally stock Thermasil rolls, but will sell PN 5300 1.500G (1.5"x328') for $4.28 - with a minimum order of qty 245.
I am not looking to organize a group buy - just need a small piece of something that will work, fast.

I see that Aavid's mica insulators are 1-3mil thick. https://www.aavidthermalloy.com/prod...nsulators/mica
I've found (3) 8"x12" sheets of 1mil Kapton on eBay for $5.99. Any reason that won't work (with heatsink compound)?

I've also got some of this 3mil sheet Teflon on hand: MusicMedic.com: Sheet TeflonŽ
CAN THIS BE USED INSTEAD OF MICA OR KAPTON (WITHOUT BURNING UP THE NEW AMP)?

ANY OTHER SUGGESTIONS?

Thanks,
-rb

[J M Fahey]

In a similar case, on an urgent job on a Saturday afternoon, I used two edge to edge TO218/247 micas which formed a rectangle larger than was needed and the pre perforated holes they had, stayed well away from the critical (high screw pressure) centerline.
The practically virtual "slit" in the middle is not dangerous, because mica thickness keeps heatsink and case separate.
I trust mica more than anything else.
1 mil kapton *might* work and don't trust Teflon for this job.
jm2c

[jrfrond]

I bought a roll of Bergquist Silpad 400 material, and just cut it to any unusual size we need. One of those 7-size leather punch tools is great for holes.

[rjb]

I bought a roll of Bergquist Silpad 400 material

Can you tell me where you bought it?

I've tried Mouser, Digikey, Allied, Newark....
The only non-precut Sil-Pad 400 product I've found for sale in single quantities is 7mil 12"x12" sheets for $25.04 at Newark.

One of those 7-size leather punch tools is great for holes.

Thanks for the tip. I'll keep it in mind for my next Harbor Freight run.

-rb

[rjb]

Since I don't have any micas on hand, and couldn't find a reasonable quantity of Sil-pad material, I ordered the Kapton and cut my own insulators.
After 24 hr burn-in, so far so good.

I still would appreciate any leads on where to buy *one* roll of Sil-pad material.

Now I'd like to take this moment to express my heart-felt thanks the humans who replied, and fond farewell to the Iranian robot whose post was expunged.

Later,
-rb