Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Heatsink solder fillet

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Heatsink solder fillet | 12 January, 2006

Opinions. I have a large finned heatsink that we place over a D2pak transistor. This heatsink is designed to heatsink the transistor through the junction of the pad area that the transistor is attached to. The paste pattern we chose was small dots around the outside of the transitor were the heatsink makes contact and a "window pane" of 4 sqaures behind the transitor. Smalls dots were chose to minimize "float/skewing" of the heatsink. Would you expect to see a solder fillet on the heatsink? Would you think it should? Ipc does not address this type of device specifically, but the heatsink maker says minimal 50% solder coverage on the back is required (no fillet).Our inspectors are reluctant to release due to lack of fillet. What do you think?

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Heatsink solder fillet | 12 January, 2006

We think if you follow your suppliers instructions, you should be OK. Why not have your quality people rip a couple of the soldered heat sinks from the board to assure themselves that your soldering process is adequate? Give them a pair of pliers and let them got at it.

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