Fastening methods for heatsinking PSU components.

[sonewone]

Hello Guys,

I am a Mech Engineer designing an enclosure for a Power Supply PCB.

On the Layout, there are couple of components (See below)
those require heat sinking.

IC Bridge rectifier
MOSFET N Channel

I am using a common strip of metal to heat sink them. Later the complete assembly will be potted.

Question : For fastening these components to the metal plate, is it mandatory to use s screw? Is it alright if we revit them? Or use a spring steel clip? Will UL have any issues if I use these kind of fastening methods.

Thanks In advance.
BT

 

[itsmoked]

You can use any method you want. Lately I have been using the clips - I love them. But with potting... I would go with screws or rivets since the potting could possibly unseat springs.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[zappedagain]

The answer really depends upon your specific packages that the rectifier and MOSFET are in.

If the package is something like a TO-220 then as long as they are secure (screw, rivet, clip) and don't loosen up over temperature cycles there should be no issues. Others may chime in with more specifics.

John D

 

[sonewone]

Thanks guys. Itsomked, you mentioned about the clips. may I know what kind of clips? Were they off the shelf or custom parts?
I tried to lookup for clips on mcmaster, the results were not relavent.

Thanks

 

[sonewone]

Sorry I forgot to mention about the alternative Plastic heat sink I am planning to use. Its from

http://www.Coolpolymers.com

.
By using this, I need not worry about using insulation material while fastening.

Another alternative I thought about was to laminate the metal heatsink. This saves the time we spend on cutting the small pieces of thermal pads and storing them.

 

[itsmoked]

These are what I'm talking about:

http://www.aavidthermalloy.com/products/maxclip/index.shtml

This movie about using them sez it ALL.

http://www.aavidthermalloy.com/products/maxclip/maxclip_movie.asf

They work very well. Frankly, they're superior to all alternatives if the configuration allows them.

You can always go to someone like Berquist and have them diecut you a bunch of thermal isolators with contact adhesive on one side.(If they don't stock the size you need.)

Keith Cress
kcress -

http://www.flaminsystems.com

 

[sonewone]

Awsome, Thanks a lot for the links.