Fellow Techs,

We are assembling a double sided board with BGAs on both sides.  One board seems to be having a problem with a 21 mm sq. pbga that is initial installed on the 1st side and then goes through the reflow oven again, upside down during the 2nd side reflow.  It looks like the bga is dropping slightly when it goes through the reflow oven for a second time, upside down.

Does anyone have any ideas on how to either temporarily or permanently secure the bga in place after the 1st side reflow so the bga does not pull away from the board slightly during the 2nd side reflow?  Tacking the corners with some type of epoxy that would not affect long term reliability?  thanks

joe

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