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

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BGA solderability / moisture

Stephen

#18838

BGA solderability / moisture | 11 February, 2002

We have some BGA's that don't solder very well. They weren't properly stored in regards to moisture protection. The balls look dull and rough. After reflow there seemed to be a diffinate line between the balls and the solder on the PCB's. I think there was some oxidation. Would re-balling be the only option? We plan on getting a vaccuum bag resealer and a batch drying oven. I think the oven will help with other issues but I don't think it will help with these BGA's. We only have this problem with one kind of Motorola BGA. I also tried applying no clean flux to the balls and putting them through the oven at about 150 degrees C. It did seem to clean them up a little. I havn't heard any results about that batch yet.

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CAL

#18840

BGA solderability / moisture | 11 February, 2002

Stephano-

There is a Chemical process to revert the contamination back to its original form. The EMPF Developed it back a few years ago in conjunction with Rockwell and some others. Please contact ACI at 610-362-1200 and ask for Dr. Greg Parks. This process is not detrimental to the components and makes them good as new. www.aciusa.org or http://www.empf.org

I personally would not "reball" as you maybe adding variables that could be worse than you are now.

Best Regards, Cal

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#18841

BGA solderability / moisture | 11 February, 2002

LONG TERM

Your plans to buy a vaccuum bag resealer and a batch drying oven sound good as you say, but you�re correct. They will not help with this current situation.

SHORT TERM

If your connections are clean, free of pits and holes with a smooth, slightly concave, feathered fillet; I would not mess with the BGA that are soldered to the boards. They are fine. The definite line on the balls is demarcation of the extent of the flow of the flux contained in your paste.

Listen. If your BGA are soldering with good flow, do not mess with the balls on the components that are not soldered to boards. These balls are just heavily oxidized. Contact your supplier, if you want confirmation. If you are getting good flow with your current flux: say �pfew�, sign-off on the noncompliance report, and move on to other things.

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