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Chip Surface Damage Induced by Internal Stress of Lead–ON–Chip (Loc) Packages

Published online by Cambridge University Press:  22 February 2011

Masazumi Amagai
Affiliation:
Texas Instruments Japan Limited, Hiji Plant, New Package Development 4260 Takao, Kawasakiaza, Ohaza, Hiji, Hayami, Oita 879–15, Japan
Eiji Kawasaki
Affiliation:
Texas Instruments Japan Limited, Miho Plant, Wafer Fab Engineering 2350 Kihara, Miho, Inashikigun, Ibaraki 300–04, Japan
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Abstract

In lead–on–chip (LOC) packaging technology, the lead fingers are attached directly to the surface of the chip using a double–side adhesive tape. This method of chip attachment naturally concerns with regards to stress on the polyimide coated chip surface. Device failure related to fracture in the passivation layers and the Al–Si metal has been observed in temperature cycle tests. The dominant issue is polyimide cracking due to mechanical stress caused by internal stress of LOC packages. To investigate the effect of polyimide characterization, devices were fabricated with different polyimides. The degree of polyimide cracking was determined with scanning electron microscope (SEM) technique. The polyimides were characterized with chemicals, tensile measurement tester, thermal analyzer, fourier transform infrared spectroscope (FTIR), computer simulation and various package-level reliability tests. The results of the characterization and an explanation of the primary factors affecting chip surface damage are presented in this paper.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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References

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