Recommend method for fastening IGBT to heatsink

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,942
This IGBT does not have a mounting hole. The heatsink does - but I can't use it where it's located. Looking for suggestions on how to mount the transistor to the heatsink. Please forego mentioning heatsink compound - that much is known.

Thinking some kind of spring clip - but nothing in the junk bin will do. It probably doesn't take tremendous pressure to hold the transistor to the heatsink. Just sufficient to make contact along with compound. Any ideas - suggestions - even dumb ideas may be entertained.

Thanks.

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Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,942
Been looking around in my stockpile for anything like this. I know I've seen the screw-on type spring clip. If I can find it - my area has been under a little re-organizing - I'll put a hole in my heatsink and tap it then screw the clip on. One thing I am hoping to avoid is making it a permanent fixture to the heatsink. But if all else fails - that'll probably be the end result. Before that happens I have some heavy gauge copper out in the garage. I can cut and shape something that can be pressed in-between the blades of the sink. A little cutting, a little filing and I'll have something. BUT - does anyone know how to harden copper? Suddenly, it occurs to me - I have ribbon stainless steel welding wire. I can cut some of that and make a clip that wedges between the fins with a bow to it to hold the IGBT to the sink.

You guys are really helpful. Thanks.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,942
Issue resolved. Took some of that flat ribbon stainless steel welding wire and cut a short strip just slightly larger than the width of the fins. Cut pointed ends into each end so it would act like teeth going in and biting upon attempting to come out. Filed it until it was a forced fit (not high force - please). Removed and applied thermal paste "Arctic Silver 5" to cleaned surfaces, both the heatsink and the IGBT and then pressed the clamp back into position. Holds with some pretty good tension. Yet it remains removable in the event I want to change something.

OK, back to my other thread - this time I'm building a 555 PWM to control the blower speed. Y'all remember that thread, the one where everybody disagreed with somebody and somebody disagreed with everybody. Anyway - thanks for the input.

PROBLEM SOLVED! THANK YOU.

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dl324

Joined Mar 30, 2015
9,334
I would have been tempted to use an adhesive BGA heat sink:
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Since I have a bag of them...
 
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Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,942
Since I have a bag of them...
I have one. Also have some HS's from scrapped computers, they have fans attached.

For the "Other" project I've been working on - for which this is a part of - I will drive a 12 VDC motor that can draw as much as 36 amps at full speed startup and about 19 amps at full speed running. It will be PWM speed controlled, so it's not going to be running at full speed very often. Probably hardly ever - if ever at all. Switching the IGBT on and off at 50% power should not produce as much heat. So this HS should be sufficient. If not - I'll learn the hard way. After all, I COULD use one of those MCU HS Cooling rigs.

Here's a few of the salvaged junk in the bin: Three computer MCU's, two BGA, a tin finned HS and a couple LED Lightbulbs that failed LONG before their 10 year lifespan. I'm sure I have a few more floating around somewhere. My work area is a mess. But they say a clean work area is a sign of a sick mind. If true - I must be healthy as hell.

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Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,942
This is stainless steel welding ribbon. It's been in the shop for years and I've never seen it used so I really can't describe its use. Nevertheless, it must take a specialized machine - something like "Sub-Arc" welding. The thing I find appealing with this wire is its rigidity. It's very difficult to bend. It's very springy and flexible. To shape it I've had to heat it then let it cool to room temperature in atmosphere, not water or oil quenched. I took what the company decided to toss into the scrap bin. Not long lengths either. Pretty much useless for their purpose. At the time I was interested in learning something about HHO. Please - lets not get started on that subject - you can't get more energy out of something than you put into it. Nuff bout dat!

As to the disagreement part in my other thread - I found myself discussing a difference of opinion with someone. No need in naming names - the point is that we resolved the subject satisfactorily.
 

shortbus

Joined Sep 30, 2009
7,245
Reason I asked is I never saw anything like it and couldn't find it on the web. In my earlier working years the company was heavily involved with high tech welding.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,942
That's the only time I've ever even SEEN the stuff. Have two left-over spools; one is about an inch wide the other is about 2 1/2 inches wide.
 
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