Effect of unfilled underfill on drop test and thermal cycle reliability

Ibe, Edward S.; Loh, K.I.; Luan, Jing-en; Tee, Tong Yan

doi:10.1109/icept.2005.1564728

Cited by 1 publication

(2 citation statements)

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“…Ball grid array (BGA) packages are more prone to damage after drop impact, because the package is larger and the solder joints are the only source of a mechanical adhesion (no underfill is used in BGA). 2,3 Also, as solder alloys move to lead-free compositions, the increased strength of these alloys, especially in the Sn-Ag based solders, may lead to drop concerns.…”

Section: Introductionmentioning

confidence: 99%

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Failure Morphology after the Drop Impact Test of the Ball Grid Array Package with Lead-Free Sn-3.8Ag-0.7Cu on Cu and Ni Under-Bump Metallurgies

Jang

Lin

Frear

2007

Journal of Elec Materi

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High strain-rate drop impact tests were performed on ball grid array (BGA) packages with lead-free Sn-3.8Ag-0.7Cu solder (in wt.%). Plated Ni and Cu under-bump metallurgies (UBMs) were used on the device side, and their drop test performances were compared. Failure occurred at the device side, exhibiting brittle interfacial fracture. For Ni UBM, failure occurred along the Ni/(Cu,Ni) 6 Sn 5 interface, while the Cu UBM case showed failure along the interface between two intermetallics, Cu 6 Sn 5 /Cu 3 Sn. However, the damage across the package varied. For Cu UBM, only a few solder balls failed at the device edge, whereas on Ni UBM, many more solder bumps failed. The difference in the failure behavior is due to the adhesion of the UBM and intermetallics rather than the intermetallic thickness. The better adhesion of Cu UBM is due to a more active soldering reaction than Ni, leading to stronger chemical bonding between intermetallics and UBM. In our reflow condition, the soldering reaction rate was about 4 times faster on Cu UBM than on Ni UBM.

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Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8] However, very limited work has been reported on the metallurgical response. 9,10 Drop impact leads to highly accelerated strain/stress conditions, so the failure morphology of the solder joint may differ from that of a convention mechanical test.…”

Section: Introductionmentioning

confidence: 99%