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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


bga warp

manic

#21417

bga warp | 5 September, 2002

Hi,

I encountered a problem with pbga. One edge either warp downwards or upwards creating bridging or open. This pbga have fr4 at the bottom (compound molding at the top). The fr4 is bigger than the top compound by 3mm at each edge.

Pls help. Thanx. manic.

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#21467

bga warp | 10 September, 2002

I doubt that the interposer is FR4, it's more likely to be BT.

Warp during reflow is a function of material a reflow recipe. Your ramp is too fast and is causing the interposer to bend like a potato chip.

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Stephen

#21494

bga warp | 11 September, 2002

I've seen this problem caused by the cool down. On a 7 zone oven I made a profile to peak at zone 5 to give some semblance of control to the cool down. The component can develope a big delta T, because of the difference of materials

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#21497

bga warp | 11 September, 2002

> I've seen this problem caused by the cool down. > On a 7 zone oven I made a profile to peak at zone > 5 to give some semblance of control to the cool > down. The component can develope a big delta T, > because of the difference of materials

Check with your part vendor it might be in there fab process of there BGA. The process might have changed. And your peak temp might effect the BGA. Try staying under 220C on that BGA in your Oven Profile. I bet your corners warp the most on that BGA.

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#21498

bga warp | 11 September, 2002

Profiles are absolutely the first course of action to validate. A few additional questions would be:

* Moisture can cause warping as well, verify the manufacturers recommended handling procedures were followed. * Where is the suspect BGA located on the assembly ? * Is this repeatable or a random and isolated location ? * Is component utilized on other assemblies, same results ? * Is the component a stable and high user in the industry, or a new component to market ? * Has the components internal temp been measured under reflow conditions ? * Failure analysis should be conducted on the component to verify intergrity of the part and manufacturers process. * Ask the F.A. lab to perform a Moyet analysis on a new component, this technique can measure the die/substrate deflection characteristics under thermal conditions.

Please email if you have any additional questions.

Scott E. Fiske scottefiske@hotmail.com

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