Connecting mosfet heatsink to mosfet

I am using the DV-T263-201ETR-ND heatsink for my to-263 mosfets. Even though the data sheet claims that it has solderable rods, it doesn’t seem to even bond with the solder (99.3% Sn / 0.7% Cu) at 400C. Could someone suggest why this is more difficult than it should be?

Hello Tomz0804 and welcome to the forum.

Are you using any flux (in the core of the solder or otherwise) to facilitate this?

I did try applying flux to it, did not make a difference.

Keep in mind that the thing you’re trying to solder to is specifically designed to dissipate heat and has a substantial thermal mass.

It’ll be rather difficult to get it up to a temperature that’ll enable a nice wet-out and bond using a small-tip pencil iron. The ideal tool for planting those things would be a reflow oven, but a person could probably get a job done using a hot plate and fatter tip, heat gun, or other combination of tools that’ll help you get the thing up to a temperature that’ll get the job done.

Most of my manual assembly these days gets done using SMD291AX solder paste fortified with a dab of SMD291 tacky flux, and a hot air station. Not having one hand occupied holding the solder can be quite handy…

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Ok thank you. I have a heat gun at my school which I could use with some solder paste. It still might be difficult to actually get a good angle onto the point of contact though.