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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

BGA opens

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BGA opens | 9 November, 2009

Hi, i have a big problem with a BGA, and i have no idea where could be the broblem because eveything seems to be ok(printing, placement, reflow). I have arroud 2-3% Opens from the quantity of boards produced during a shift. Can enybody help me with some ideas what else can cause this opens, or something to fix the process? thanks

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BGA opens | 10 November, 2009

Step 1 is to find out what kind of opens you're getting through a cross-section or die & pry. Are they head in pillow, brittle fracture at the intermetallic, bulk solder cracks, ball separation from interposer? Without some basic failure analysis all you're going to get is shotgunning.

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BGA opens | 12 November, 2009

You can certainly venture out to the nearest lab for in-depth analyses. But since you mention 2-3% defectives in a batch, there is much you can do in-house as well. Measure the height of your solder paste deposit (in zero print gap condition)across all lands of the BGA. This should be near equal to stencil plate thickness. Any gross variation is attributed to either poor stencil quality or the need to re-validate the printing process. - Cheers !!!

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