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

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Reflow Bottom BGA without pallet

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Kim

#65222

Reflow Bottom BGA without pallet | 13 October, 2011

Hi!

We have many PCBA with double side BGA mounted, current practice is to put the board on reflow pallet (durastone 761) to cover BGA at bottom side so that the BGA won't lift after go through reflow oven, but this created 2 problems:- 1) We need to transfer empty pallet back to front 2) Maintenance cost for the pallet

We tried to improve this 2 problem with eliminate the use of reflow pallet, but it seem impossible because even we turn off bottom oven (reflow machine), the peak temperature at bottom side still hit 210degC above, the bottom BGA will still tilt.

Appreciate if anyone have ideas or experiance to handle such kind problem.

Thanks.

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#65224

Reflow Bottom BGA without pallet | 13 October, 2011

Have you considered adding adhesive / epoxy at the corners of the BGA to secure it in place?

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#65225

Reflow Bottom BGA without pallet | 13 October, 2011

You can use a paste that flows at 2 different temps. (first side flows hotter than second side) Glue, as stated in other answer and capton tape covering the BGA will defect enough heat usually as well.

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#65227

Reflow Bottom BGA without pallet | 13 October, 2011

BGA solder joint reliability is actually improved slightly from a double-sided reflow. [Jean-Paul Clech APEX 2003 Solder Joint Reliability of BGA Assemblies]

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Kim

#65230

Reflow Bottom BGA without pallet | 13 October, 2011

Hi Doug

Nice idea (2 type paste), I will have a trial.

We think of glue and tape too, but it involve cost, but we still keep as an option.

thanks.

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