What paint to use on a heat sink?

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What kind of paint can I use on a heat sink that will electrically insulate it but will not degrade its efficiency of heat transfer with ambient air too much? The heat sink will be used for a voltage regulator. I will paint only the exposed parts to prevent problems like accidental shorting with nearby components. I will not paint the area that makes contact with the regulator's metal tab.

On the other hand, what about having the heat sink anodized? I've heard of anodized heat sinks where the surface is still metallic but non-conductive. Where can I have this done? Is it something that I can also DIY?

Thanks! 🙂
 
You should design your layout so that nothing is in danger of becoming in contact with the heat sink. Also make sure the heat sink is secure.

Relying on paint or anodized coating to provide insulation in the event of accidental contact is not something you want to do. Any amount of paint sufficient to reliably insulate is going to decrease thermal efficiency quite significantly. Again, design it so that it's virtually impossible for something like that to happen.

If you must absolutely place components very close to the heat sink due to size restrictions, consider putting shrink tubing over any conductive parts of the components.
 
I used automotive black spray (the non glossy type) with success. You may want to etch the surface of the heatsink in sodium-hydroxyde beforehand. Anodizing is the best, though. Also consider using mica or other thermally conductive washer and white thermal grease.
 
I'm wondering the same thing.

I have some shiny silver-yellow heatsinks, and I want them metallic blue. They sell paint that makes chrome into metallic colors - I've used it on wheels before.

I'm wondering if the coat of paint will make the heatsink get hotter or not.
 
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