Effect of Lid Materials on the Solder Ball Reliability of Thermally Enhanced Flip-Chip Plastic Ball Grid Array Packages

This research studied the thermal fatigue life for eutectic solder balls of thermally enhanced flip-chip plastic ball grid array (FC-PBGA) packages with different lid materials under thermal cycling tests. Three FC-PBGA packages with different lid materials, i.e., Al, AlSiC, and Cu, were utilized to examine the lid material effect on solder ball reliability. The cyclic stress/strain behavior for the packages was estimated by using the nonlinear finite element method. The eutectic solder was assumed to be elastic-plastic-creep. The stable stress/strain results obtained from FEM analysis were utilized to predict the thermal fatigue life of solder balls by using the Coffin-Manson prediction model. Simulation results showed that the fatigue life of the FC-PBGA package with a Cu lid was much shorter than FC-PBGA packages with other lid materials. The relatively shorter fatigue life for the FC-PBGA package with a Cu lid was due to the complex constrained behavior caused by the thermal mismatch between the lid, substrate and the printed circuit board. The difference was insignificant in the fatigue lives between the package with an Al lid and the conventional package.

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Investigation and analysis on the solder ball shear strength of plastic ball grid array, chip scale, and flip chip packages with eutectic Pb-Sn and Pb-free solders

10.14711/thesis-b786511 ◽

2003 ◽

Author(s):

Xingjia Huang

Keyword(s):

Shear Strength ◽

Solder Ball ◽

Flip Chip ◽

Ball Grid Array ◽

Ball Shear ◽

Plastic Ball ◽

Plastic Ball Grid Array ◽

Ball Shear Strength

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The Effect of Ball Pad Metallurgy and Ball Composition on Solder Ball Integrity of Plastic Ball Grid Array Packages

ISTFA 1998: Conference Proceedings from the 24th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa1998p0405 ◽

1998 ◽

Author(s):

C.H. Zhong ◽

Sung Yi

Keyword(s):

Failure Mode ◽

Barrier Layer ◽

Shear Force ◽

Solder Ball ◽

Ball Grid Array ◽

Reliability Test ◽

Shear Forces ◽

Ball Shear ◽

Plastic Ball ◽

Plastic Ball Grid Array

Abstract Ball shear forces of plastic ball grid array (PBGA) packages are found to decrease after reliability test. Packages with different ball pad metallurgy form different intermetallic compounds (IMC) thus ball shear forces and failure modes are different. The characteristic and dynamic process of IMC formed are decided by ball pad metallurgy which includes Ni barrier layer and Au layer thickness. Solder ball composition also affects IMC formation dynamic process. There is basically no difference in ball shear force and failure mode for packages with different under ball pad metallurgy before reliability test. However shear force decreased and failure mode changed after reliability test, especially when packages exposed to high temperature. Major difference in ball shear force and failure mode was found for ball pad metallurgy of Ni barrier layer including Ni-P, pure Ni and Ni-Co. Solder ball composition was found to affect the IMC formation rate.

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