Effects of underfill material properties on the reliability of solder bumped flip chip on board with imperfect underfill encapsulants

被引:17
作者
Lau, JH [1 ]
Lee, SWR [1 ]
Chang, C [1 ]
Ouyang, C [1 ]
机构
[1] Express Packaging Syst Inc, Palo Alto, CA 94303 USA
来源
49TH ELECTRONIC COMPONENTS & TECHNOLOGY CONFERENCE - 1999 PROCEEDINGS | 1999年
关键词
D O I
10.1109/ECTC.1999.776237
中图分类号
TP3 [计算技术、计算机技术];
学科分类号
0812 ;
摘要
The effects of underfill material properties on the reliability of solder bumped flip chip on printed circuit board (PCB) with imperfect underfill encapsulants were studied in this paper. Three different types of underfill imperfections were considered; i.e., (1) interfacial delamination between the underfill encapsulant and the solder mask on the PCB (crack initiated at the tip of underfill fillet), (2) interfacial delamination between the chip and the underfill encapsulant (crack initiated at the chip corner), and (3) the same as (2) but without the underfill fillet. Five different combinations of coefficient of thermal expansion (CTE) and Young's modulus with the aforementioned delaminations were investigated. A fracture mechanics approach was employed for computational analysis. The strain energy release rate at the crack tip and the maximum accumulated equivalent plastic strain in the solder bumps of all cases were evaluated as indices of reliability, Besides, mechanical shear tests were performed to characterize the shear strength at the underfill-solder mask interface and the underfill-chip passivation interface. The main objective of the present study is to achieve a better understanding of the thermo-mechanical behavior of flip chip on board (FCOB) assemblies with imperfect underfill encapsulants.
引用
收藏
页码:571 / 582
页数:12
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