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Failure Analysis Dilemma on a BGA Sample

             

Getting just a single sample reject for a failure analysis (FA) request in always unnerving for an FA engineer, since a single mistake in the FA process can render the lone sample unusable for further FA. This is especially true for newbie FA engineers.  The archived forum thread below is about this - a new FA engineer getting just a single BGA sample for FA.  Of course, the first rule of FA is..."always do the non-destructive FA techniques first."

  

Posted by Tata: Thu Apr 07, 2005 11:13 am    Post subject: What should I start FA on BGA product

 

I have received 1 BGA failed "Open", I have no experience on this and there is only 1 sample, what should I start and end on analysis step/ :D
Thanks you

 

Posted by Fa Jujing: Thu Apr 07, 2005 3:27 pm    Post subject:

 

Tata, maybe you should start with review of all documents from this FA request. Understand the failure reported then do external visual inspection. What is the condition of the returned BGA sample? Is it still mounted on the board? If not, what's its condition? Can you still do FA on it or not anymore? Try to establish first what is the customer complaining about and if it is true. In this case, what is "open" according to them? Is it really "open"? If yes, you can continue looking for the cause of the failure. Always consider it is possible the customer induced the failure they are seeing. Let us know what you'll see.

FA Jujing

 

Posted by Fa Guy: Thu Apr 07, 2005 7:25 pm    Post subject:

 

if the sample was already demounted then it probably don't have its balls anymore so you need to do reballing on the sample to test it. but first you can do curve tracing on the interconnects just to confirm if the internal connections of the package are still ok. if the curve traces are still ok then the open failures may be due to solder ball failures. if the curve traces are not ok then there is an internal problem.

fa guy

 

Posted by Grant: Fri Jul 15, 2005 8:47 pm    Post subject:

 

Maybe X-ray inspection is a good start!

 

Posted by Guest: Mon Jul 25, 2005 12:22 pm    Post subject:

 

I would start with non-destructive tests:
1 - visual inspect the whole BGA and zoom in at the trace that's open
2 - X-ray
3 - CSAM for delam
4 - curve trace to confirm the open
5 - TDR to see "where" it opens inside

FA progressed with every findings you have so there is usually no set of Start or End to an FA. Good luck,

      

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