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Functional Test Faulure due to BGA ICs

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CKH

#42872

Functional Test Faulure due to BGA ICs | 21 July, 2006

Hi Folk,

every now and then, i would encounter Functional Failure due to BGA ICs. The Testing Tech always conclude that the contact of the BGA to the PCB Pad is poor.

The 2D/3D X-ray machine can't detect any of the poor contact on the BGA.....

We have tried to filter out some of the possible causes for this by doing a visual inspection for Contamination, Missing BGA Balls or any other abnormal quality before the start of the SMT Production.

However, we still can find similar functional failure due to the BGA ICs. Could anyone advise me on other possible root cause for this and some possible way to prevent/reduce the rate of such failure.....

Appreciate your help.

Thks & Warmest Rdgs CKH

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Chunks

#42880

Functional Test Faulure due to BGA ICs | 21 July, 2006

Stencil clog on BGA apps.

BGA not reflowing all the way - check profile.

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#42883

Functional Test Faulure due to BGA ICs | 21 July, 2006

could also be a component issue...delamination/popcorning of the component....what is the MSL level?

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#42889

Functional Test Faulure due to BGA ICs | 21 July, 2006

Does replacing the BGA fix the problem? To be a little more blunt, is the BGA or is it the tech says it's the BGA. Beleive none of what you hear and only half of what you see.

What kind of BGA is it? If it is one of those BGA's with a built in heatsink, then the center balls may not be getting complete reflow. If it is a BGA with a flange, maybe the cool down is too fast and the BGA is warped during cool down.

If you can sacrifice a PCB and BGA for profiling that would be your best bet. Drill a small hole through the other side to put the thermocouple.

Most BGA problems I"ve seen have been the reflow.

Although if you look at the BGA carefully with the XRAY and find that the center balls are bigger than the others, I would then say delamination caused by MSD issues.

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GMan

#42917

Functional Test Faulure due to BGA ICs | 24 July, 2006

Is there any ICT done prior to the Functional?

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#42918

Functional Test Faulure due to BGA ICs | 24 July, 2006

Most Test Technicians, Managers, and everyone else in the organization always believe that the BGA is the #1, and most likely failure mode in a circuit. You can analyze it with all the tools available...2D, 3D, 10D, underneath, etc...... convince them with pictures of a collapsed BGA that obviously has formed an intermetallic connection, but everyone STILL believes it's the BGA that failed.

They replace it, spend lots of sweet moolah fixing it, only to find out when they retest it, that it WASN'T the BGA in the first place....why people believe that a 20 year old, established and very robust technology like BGA's are most likely to fail?? ...not sure about that one..

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Chunks

#42919

Functional Test Faulure due to BGA ICs | 24 July, 2006

Usually when someone is just guessing on what to t-shoot, they will always choose the most expensive part. BGA, QFP, GPS Module....... Same groups believe you can get rid of defects by wearing smocks.

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#42925

Functional Test Faulure due to BGA ICs | 25 July, 2006

If your Test tech able to analyze and tell you which exact ball/location is the problem, you may send it for cross section analysis and see how the solder connection behaves. also pls check your ESD implementation.

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GS

#42926

Functional Test Failure due to BGA ICs | 25 July, 2006

Does your board passes also through the wave solder step ?

If, yes, it could be a matter of secondary reflow on BGA ball solder joints.

Best Regards....GS

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