How do you pot a driver/UI into a heatsink?

[KrisP]

Hi,

I've seen the picture below but don't have tools to shape up a plastic housing for the board to sit in. Is there an easy method of securing the board like in the picture that can be done by someone with basic tools?

Image is of Ledean's work

Thanks,

Kris.

 

[DonShock]

I just use Arctic Alumina 2 part adhesive or JB Weld. If all I need is to fix the driver in place and want maximum heat transfer, I use the smallest amount of AA I can to bond the driver to the heatsink as closely as possible. But when I've done something like in the picture above, where there is going to be a fair amount of force from a battery being pushed against the contact on the driver by a tailspring, I use the JB. I bed the entire driver in the JB so that it is supported mechanically. The JB is not conductive and I have never had it cause any problems with the driver.

AA is more forgiving in case you have to do rework after it sets up. It's often possible to break a thin bond layer with just moderate force on the parts if it's applied carefully. And I have had success with larger blobs by using a screwdriver to chip off pieces until it's possible to force the pieces apart. However, JB Weld is permanent and pretty much unbreakable except when it's really thin.

 

[KrisP]

Thanks for the reply. My problem was that the hole in the back of the heatsink was about 9mm deep and the board was about 2mm thick so I had a 7mm gap that needed to be filled with something that could also transfer the heat from the driver to the heatsink. I also needed something to hold the board central so the battery nipple would hit the centre of the driver.

I ended up finding a plastic cap that fit tightly inside the heatsink, so I cut that down to size with a Dremel until the board would squeeze in tightly. Then I got a bit of aluminium and cut out a little block 7mm thick and glued it into the heatsink with Arctic Alumina epoxy, then glued the driver to the block of aluminium with Arctic Alumina epoxy.

It didn't end up perfect but it's central and flush with the edge of the heatsink, so it should work OK