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BGA Reflow Issue

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Carol Stirling

#41027

BGA Reflow Issue | 18 April, 2006

Hello All,

Could someone offer suggestions to cure poor BGA reflow that is limited to the same area of the BGA and on one type of board only. The reflow has the look of "baseball caps" and is positioned such that it is the leading edge only that doesn't reflow. The part in question is a 272 ball, 1" square approx. We have checked different batches of BGAs, reflow profile, board layout, contaminents. The paste is Alpha WS-709. The unusual aspect is the last run of this product ran perfectly. The only change is a board spin, in which the Engineers say had minimal change and not in this particular area.

Any ideas would be appreciated.

Regards,

Carol

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RDR

#41031

BGA Reflow Issue | 18 April, 2006

Don't comprehend the baseball cap comparison, could you try a different description maybe?

You say leading edge, have you turned the board 180 deg. and does the defect follow the leading edge of board or the same balls on part?

Russ

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Carol Stirling

#41055

BGA Reflow Issue | 19 April, 2006

Sorry about that. I'd like to post a picture but doubt it's possible. Baseball cap = The pad solder reflows but the BGA ball and the pad don't reflow together in a continuous elliptical shape.

Carol

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#41056

BGA Reflow Issue | 19 April, 2006

So, your solder ball didn't collapse. What is the ball material? More and more BGA are shipped leadfree.

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Carol Stirling

#41210

BGA Reflow Issue | 26 April, 2006

That would be correct. Some others call it `Head in Pillow'. The BGA balls are 63/37 and the board it's mounting to is HASL.

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RDR

#41216

BGA Reflow Issue | 26 April, 2006

So does the defect follow the part or the orientation of the board?

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Carol Stirling

#41220

BGA Reflow Issue | 26 April, 2006

Hi Russ,

The board was ran in two orientations but with poor results. The same area of the BGA failed.

I was advised today that the Process Engineer here has come to the conclusion the defect is Pick and Place machine oriented, not a process/product problem.

Hope he's right and thanks for the input.

Regards,

Carol

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