TO-3P Insulators

[EchoWars]

Does anyone make a Mica insulator for a TO-3P package? All I can find is the silicone pads from Parts Express.

In another thread Kapton tape was discussed, but the price is outragous, and 33m is waayyyy more than I'll ever need. Even if the price was acceptable, the only width I can find is .75" (Digikey), which isn't wide enough for a TO-3P device.

I'm getting pretty frustrated...why is a plain-old Mica insulator impossible to find? Should I just give up and order the silicone pad from Parts Express and hope it's good enough?

[cpu_bach]

How about the following link?

http://www.mouser.com/?No=10&handler=data.listcategory&Ne=101&terms=insu lator&Ntt=*insulator*&crc=true&Ns=MfgrPartNumber%7 c%7cSField&N=360

[subwo1]

Hi, I would guess it may be related to safety issues surrounding the whole process involved with dealing with mica.

[EchoWars]

Originally posted by cpu_bach
How about the following link?

http://www.mouser.com/?No=10&handler=data.listcategory&Ne=101&terms=insu lator&Ntt=*insulator*&crc=true&Ns=MfgrPartNumber%7 c%7cSField&N=360

Close...but the Aavid part is 56-02-101, and Mouser does not stock it. At least I know they make it though...

subwo1...no difference in making a mica part for a TO-3, so I'm not sure what you're getting at.

So...everybody here at DIY uses their TO-3P's uninsulated?

[Nelson Pass]

Originally posted by EchoWars
Does anyone make a Mica insulator for a TO-3P package? All I can find is the silicone pads from Parts Express.

In another thread Kapton tape was discussed, but the price is outragous, and 33m is waayyyy more than I'll ever need. Even if the price was acceptable, the only width I can find is .75" (Digikey), which isn't wide enough for a TO-3P device.

I'm getting pretty frustrated...why is a plain-old Mica insulator impossible to find? Should I just give up and order the silicone pad from Parts Express and hope it's good enough?

They are available - I think Digikey has them. If the application
is critical and high power, use the micas and grease. If the heat
sink is bead blasted or otherwise frosted finish and you have
high power, use micas and grease. Otherwise the silicone
products are fine.

Kapton? Never used it.

[moving_electron]

The ESP website sells Kapton tape by the meter. I picked some up there. The site states that is enough for mounting about 33 transistors. Haven's used it yet though but folks seem to like it and think the heat transfer is better than Mica.

http://sound.westhost.com/purchase.htm

[EchoWars]

Hi Nelson!

Digikey sells the sil-pads and variations of, but seemingly not for TO-3P's. They do not have mica for anything other than TO-220 and TO-3, and perhaps one or two others, but not TO-3P. Bummer.

electron...

I may do that. I just sent a request for samples from Aavid, and if I get them I think I'll be the only one on the planet using mica for TO-3P. If I can't get them, I guess I'll settle for Parts Express sil-pads.

[BrianGT]

Mouser does indeed carry an insulator that should work fine:
mouser link to 4180 Aavid Aluminum Oxide pad
"1,030 Ships Immediately"

They are noticibly bigger than the 4170 insulators.

Aavid's site:
http://www.aavidthermalloy.com/produ...insulate.shtml
They say: "For TO-218, TO-247, and TO-3P"

They are not listed on Mouser as insulators, so they are more difficult to find, unless you search for the 4180 part number.

--
Brian

[peranders]

Originally posted by Nelson Pass
Kapton? Never used it.

Kapton works fine _only_ if the surface of the heatsink is smoothe and particular the hole has no sharp edges. It's very easy for those edges to cut through (= no insulation)

[EchoWars]

Originally posted by BrianGT
Mouser does indeed carry an insulator that should work fine:
mouser link to 4180 Aavid Aluminum Oxide pad
"1,030 Ships Immediately"

They are noticibly bigger than the 4170 insulators.

Aavid's site:
http://www.aavidthermalloy.com/produ...insulate.shtml
They say: "For TO-218, TO-247, and TO-3P"

They are not listed on Mouser as insulators, so they are more difficult to find, unless you search for the 4180 part number.

--
Brian

Yikes! 2mm thick! I think I might have room for 'em. Nice research though Brian!!

I thought that these oxide washers/spacers were fragile...? Never used 'em, so anyone else have firsthand experiance?

Still hoping that Aavid will send me freebies...