TO-220 package insulation for heat sink

[Johnson777717]

Good day folks!
I have a simple question for you.

I have 5 (count) voltage regulators that I want to install on a single heat sink. I realise that each regulator pin 2 is connected to the metal tab of the To-220 regulator package. Because not all of my regulators are the same (One for positive 5V, one for negative 5V, one positive adjustable, one negative adjustable and one for positive 12 volts.) the pin 2 does not correspond on all of the regulators. Thus, if I am to install all 5 regulators on the same heat sink, I need a method where I can insulate the tabs from the heatsink, while still providing for a good heat transfer.

Thus here is my question:

What is the name of this insulating type device? Is it a mica washer? I've also seen some thin rubber like material. Any suggestions? Thank you!

 

[Johnson777717]

Nevermind folks, I found them, typically called "heat sink pads". Thanks!

 

[k7elp60]

In addition to the pad, a fiber shoulder washer is used to insulate the mounting screw from the mounting tab. In the US, the screw is generally a 4-40. Depending upon the amount of heat and the type of pads you use, you might want to consider heatsink compound. Some pads, generally grey in color and look like thin rubber donot require the heatsink compound.

 

[Johnson777717]

good point! Thank you for the info!

 

[jbeng]

In addition to the pad, a fiber shoulder washer is used to insulate the mounting screw from the mounting tab.

I see the shoulder washers made of nylon or some other plastic as well...
JB

 

[Johnson777717]

Ya, I looked around at digikey and found a TO-220 mounting and insulating kit which contains 2 screws (4-40), a mica insulating pad, 2 pairs of shoulder washers (fiber), 2 flat washers and 2 nuts for 89 cents! Seems like a pretty good rate for me.

 

[captainkirksdog]

Check out some of the surplus houses. You might get an even better deal.

 

[captainkirksdog]

Check out some of the surplus houses. You might get an even better deal.