How to one mount PCB-mounted TO-247 devices to a large plate heatsink

heatsinkmechanicalmount

I want to mount multiple PCB-mounted TO-247 devices to a single large heatsink, something comparable to this:

enter image description here

My devices may or may not have mounting holes through them, and their tabs may or may not be isolated. Any approach will have to support the use of mounting clamps and isolation pads. I'm using TO-247 devices for cost reasons; the smallest chassis-mount devices I'm aware of are SOT-227, which cost much more than similar parts in TO-247 packages.

What approaches to this problem are used? What difficulties are presented by those approaches?

Best Answer

I did this once: - enter image description here

Use a strap of sturdy metal to push the transistors down onto the base of the heatsink.

You'll need to drill holes in the sides of the heatsink to hold the strap in place.

Legs of transistors point upwards and solder into PCB.

Transistors and PCB can be removed from the heatsink by undoing screws holding strap.

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