Can I enlarge the mounting hole on Mosfet?

BillEpstein · 30th January 2010, 10:41 AM

The nylon shoulder washers I have to isolate the devices (Mosfets, current regs, diode bridge) from their TO-220 heatsinks are a smidge too big to go through the mounting holes in the various devices. Can I ream or drill out the holes slightly without damaging the devices?

AndrewT · 30th January 2010, 10:58 AM

Quote:

Originally Posted by BillEpstein

The nylon shoulder washers I have to isolate the devices ..... from their TO-220 heatsinks are a smidge too big to go through the mounting holes in the various devices. Can I ream or drill out the holes slightly ....?

To220 devices have a metal tab. It's usually plated copper.
Easy to ream out. The slightly tapered hole makes it even easier to insert the top hat.
Ream out the minimum to make the top hat a push fit, not a slack or rattle fit.

TheGimp · 2nd February 2010, 05:39 PM

Be sure to debur the back side so you don't pinch through your insulator.

jcx · 2nd February 2010, 06:24 PM

since it is a soft copper alloy messing with the tab can easily bend it - causing large gaps in the heatsink interface when bolted

30th January 2010, 10:41 AM	#1
BillEpstein diyAudio Member Join Date: Feb 2004 Location: The Great Smoky Mountains	Can I enlarge the mounting hole on Mosfet? The nylon shoulder washers I have to isolate the devices (Mosfets, current regs, diode bridge) from their TO-220 heatsinks are a smidge too big to go through the mounting holes in the various devices. Can I ream or drill out the holes slightly without damaging the devices?

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2nd February 2010, 05:39 PM	#3
TheGimp diyAudio Member Join Date: Aug 2009 Location: Johnson City, TN	Be sure to debur the back side so you don't pinch through your insulator.

2nd February 2010, 06:24 PM	#4
jcx diyAudio Member Join Date: Feb 2003 Location: ..	since it is a soft copper alloy messing with the tab can easily bend it - causing large gaps in the heatsink interface when bolted

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