Hello to All,
We have had solder short in a PBGA with a pitch of 1.27 mm.
The short is between one solder ball and an adjacent via pad.
The problem is only shown in specific date codes of the component.
We measured the solder balls and there are differences between the diameter of the solder balls:
The average diameter in the "good" date codes is 0.58 mm and in the "bad" date code is 0.63mm.
The specs. states that the diameter could be between 0.50 and 0.70 mm; then both date codes are within specs.
We also found that the soldermask over the via pads is not well centered causing that solderable surface in some
via pads be closer to the solder balls.
Is it possible that the solder short could be caused by the combination of these two issues?
Thanks in advance.
Alejandro Becerra
Quality Assurance
Phone (915) 841-8439, Fax (915) 841-8401