Mica Insulators

glen65 · 22nd December 2006, 05:28 PM

Hello,
Just looking for an opinion from others as to which
would be the best course of action. I have looked all over the place
for mica insulators for TO127 devices and been unsuccessful. However I have some new mica insulators I believe are for a TO3P case transistors. Based on the pics below would they be safe to use on these TO127 case devices?

Here is one I modified so that it would cover the entire back of the device.
Would this be a better way to go if I were to use them?

Thanks.

Netlist · 22nd December 2006, 05:48 PM

Nice modification but I would prefer the original.
Suppose you drill the whole one little millimeter lower and the mica is accidentally placed too high...
The first picture covers the risky area very well.
Just make sure to always measure for shorts between heat sink and body of an insulated transistor before applying current.

/Hugo

steenoe · 22nd December 2006, 05:54 PM

Dont cut them to size, they fit good enough. What you often can do with Mica is to actually split them with a sharp scalpel! More often than not they are too thick. Being the material it is, you can easily split them in half or even more some times. Just go ahead and try it, its easier than one should think. The thinner the better, regarding heat-transfer.

Steen

anatech · 22nd December 2006, 07:02 PM

Hi glen65,
I agree with Hugo 100%. Use them in their stock form.

Maintaining surface flatness may be difficult if you split the mica insulators to make two thinner ones.

-Chris

steenoe · 22nd December 2006, 07:12 PM

Quote:

Maintaining surface flatness may be difficult if you split the mica insulators to make two thinner ones.

Nope!! They wont be more uneven when split. I dont mean to start an arguement, but Mica's are no flatter if not split!
Mica's are allways a bit bumpy

Thats what you got Thermal grease for.

Steen

(used to build Class A amps with heavy current draw

)

glen65 · 22nd December 2006, 07:15 PM

Thanks for the response,

I was just a little concerned that not having the insulator
extending completely to the bottom of the device might
result in a lack of heat transfer.

22nd December 2006, 05:28 PM	#1
glen65 diyAudio Member Join Date: Jun 2004 Location: mid Ohio USA	Mica Insulators Hello, Just looking for an opinion from others as to which would be the best course of action. I have looked all over the place for mica insulators for TO127 devices and been unsuccessful. However I have some new mica insulators I believe are for a TO3P case transistors. Based on the pics below would they be safe to use on these TO127 case devices? Here is one I modified so that it would cover the entire back of the device. Would this be a better way to go if I were to use them? Thanks.

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22nd December 2006, 05:48 PM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	Nice modification but I would prefer the original. Suppose you drill the whole one little millimeter lower and the mica is accidentally placed too high... The first picture covers the risky area very well. Just make sure to always measure for shorts between heat sink and body of an insulated transistor before applying current. /Hugo

22nd December 2006, 05:54 PM	#3
steenoe diyAudio Member Join Date: Mar 2004	Dont cut them to size, they fit good enough. What you often can do with Mica is to actually split them with a sharp scalpel! More often than not they are too thick. Being the material it is, you can easily split them in half or even more some times. Just go ahead and try it, its easier than one should think. The thinner the better, regarding heat-transfer. Steen

22nd December 2006, 07:02 PM	#4
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi glen65, I agree with Hugo 100%. Use them in their stock form. Maintaining surface flatness may be difficult if you split the mica insulators to make two thinner ones. -Chris

22nd December 2006, 07:15 PM	#6
glen65 diyAudio Member Join Date: Jun 2004 Location: mid Ohio USA	Thanks for the response, I was just a little concerned that not having the insulator extending completely to the bottom of the device might result in a lack of heat transfer.

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