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BGA Resistor Array Separating from Balls

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#60859

BGA Resistor Array Separating from Balls | 18 January, 2010

Hello all,

One of our resistor arrays is becoming detached from its balls after reflow. This is the second instance of this happening. The balls are clearly soldered to the board, but the actual package is coming off (package pads are quite bare).

The first time this happened was on the bottom of the board ( 2 reflow cycles). The board was in test, and a tech lightly poked the package and it separated. The second time was a top-side component (single reflow), and the package was bumped while changing out a nearby part and the package came off (again, the balls are firmly attached to the PCB, and the BGA pads look bare).

We are using a leadfree solder. We do not currently have xray inspection in-house, as our BGA usage is VERY low. Our source for inspecting our boards didnt see anything wrong, but I'm not sure they were looking at this part of the BGA (probably focusing on where the ball meets the PCB).

Any ideas what to look at here? Is this a manufacturer defect? Handling? Profile issue? Any input is appreciated. Thanks

Edit: In looking very closely under the scope, it appears there is some solder on the BGA's pads. The PCB definitely has the ball-shaped part soldered to it though.

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CL

#60864

BGA Resistor Array Separating from Balls | 18 January, 2010

Good Afternoon,

Is this by chance a Pb BGA on a RoHS board?

We had an issue with a Pb BGA on a RoHS board where we experienced "ball drop" on the Pb BGA. This was due to the heat required to reflow the RoHS paste. It was more than the Pb BGA could handle.

Just a thought.

CL

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#60871

BGA Resistor Array Separating from Balls | 19 January, 2010

You nailed it. After some further investigation, it appears we had some old Pb version of this part that never got scrapped. Corrective action has been taken, and all the Pb parts have been disposed of.

It makes sense that this would happen to the Pb part, as you said the heat would be really high for the Pb balls.

Thanks!

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