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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Joe Cameron

#12703

BGA Shorts? | 4 February, 1999

Hello all,

Are BGA's easy to develope shorts? If a process is stable and all of a sudden you get BGA's shorting out on you, what might be problems?

We've checked our solder paste amount, and we've rechecked our reflow profiles and nothing has changed. Where are we going wrong?

Joe

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Terry Burnette

#12704

Re: BGA Shorts? | 4 February, 1999

| Hello all, | | Are BGA's easy to develope shorts? If a process is stable and all of a sudden you get BGA's shorting out on you, what might be problems? | | We've checked our solder paste amount, and we've rechecked our reflow profiles and nothing has changed. Where are we going wrong? | | Joe | Check to make sure the BGA's have not been out of dry pack beyond their specified limit. When PBGA's "popcorn" due to moisture, they tend to also get solder shorts. The one other place shorting can occur is if the wave solder process is pushing solder up through open via's beneath the BGA's. Most times we find the problem to be popcorn. You can prove it by baking your BGA's for 24 hours, at 125� C, prior to reflow. This will remove the moisture from the BGA, and prevent delamination.

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Evelyn York

#12705

BGA-Problems with adhesion of the solder balls | 11 February, 1999

Hey, has anybody experienced problems with solder balls falling off BGA's? I have not been able to identify a contaminant nor any physical problems that would cause this.

On packages with 'good' adhesion I have not observed any intermetallic formation on the ball/board interface. Should there be?

Your comments will be greatly appreciated!

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Thomas Ballhausen

#12706

Re: BGA-Problems with adhesion of the solder balls | 1 November, 2000

Since your problem has been posted quite some time ago I am eager to know, if you have got any clue. One of my customers recently claimed our 313-PBGA causing problems, as one of its balls (randomly) is almost dewetting. So no evidence is found by x-ray, the system fails at electrical test. Investigations revealed the open is caused by the ball has lost contact to its pad, while the joint with the PCB is OK.

I shall appreciate comments or ideas of what may cause a solder ball to dewet from its pad?

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