Solder Bridging in BGA devices Definition: Solder bridging is a defect that commonly occurs during reflow of BGA devices. The BGA device can warp during reflow causing adjacent BGA spheres to come in contact and form a solder bridge. The BGA spheres located in the corners of the device are most susceptible to this phenomenon. In some cases solder bridging can be overcome by adjusting the reflow profile or repositioning the device on the PCB. However, in many cases neither of these solutions rectifies the problem forcing manufacturing to live with the DPMO yield. www.alpha.alent.com With No Precision Preform Spacer During the liquidous phase, solder is squeezed and forms a bridge due to either substrate warpage or component weight. BRIDGING Before Reflow During Reflow After Reflow
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Solder Bridging in BGA devices
Definition: Solder bridging is a defect that commonly occurs during reflow of BGAdevices. The BGA device can warp during reflow causing adjacent BGA spheres tocome in contact and form a solder bridge. The BGA spheres located in the cornersof the device are most susceptible to this phenomenon. In some cases solderbridging can be overcome by adjusting the reflow profile or repositioning the deviceon the PCB. However, in many cases neither of these solutions rectifies the problemforcing manufacturing to live with the DPMO yield.
www.alpha.alent.com
With No Precision Preform Spacer
During the liquidous phase, solder is squeezedand forms a bridge due to either substratewarpage or component weight.
BRIDGING
Before Reflow
During Reflow
After Reflow
Possible Causes:
Description
PCB/Component During reflow CTE mismatches within the BGA component commonly trigger a warpage phenomenon known as“frowning.” Frowning over-compressesor pancakes the solder spheres. Solderbridging occurs when these compressedspheres come in contact with oneanother during the reflow process. This is especially common in the corners ofthe BGA.
Recommendations
•Use a precision preform spacer on the 4 corners of the BGA device tomaintain a minimum standoff heightand prevent solder bridging.
•Contact your local Alpha salesrepresentative to learn more aboutPrecision Preform Spacers.
With Precision Preform Spacer
Maintain minimum stand-off height, allowing solderto form a more spherical ball and prevent bridging.
NO BRIDGING
Before Reflow
During Reflow
After Reflow
SPACER
SOLDER PASTE
PAD
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