Dear Technetters:

  I have a thought question for you SMT process engineers out there.

  We are attempting to have a part selectively drop off in a reflow oven on a 2-sided l-f SMT assembly. In order for this to happen we will have to make sure during the reflow cycle that the part in question falls off while the others remain.

  The question is how does one calculate the force due to surface tension holding a part to the PCB while the solder is in the  liquidus phase? If we know this then we believe we have a method to attach the right amount of weight to the device to make it fall off.
  \
  Thanks .

  BWET


Bob Wettermann

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