NDLI: The effect of globtop process and material condition on voiding

Content Provider	IEEE Xplore Digital Library
Author	Wong, C.K.Y. Teng, A.
Copyright Year	2000
Description	Author affiliation: EPACK Lab., Hong Kong Univ. of Sci & Technol., China (Wong, C.K.Y.)
Abstract	Chip-on-board (COB) packaging is a common IC packaging process in the Hong Kong-South China region. According to the packaging roadmap, the worldwide COB market trend is likely to expand to about 25 billion units per year by 2001 (Hwang, 1998). The popularity of COB is driven by its lower cost and its compatibility with PCB surface mounting processes. COB is now penetrating higher grade products such as telecommunications. There is increasing interest to make COB and globtop encapsulant materials more reliable and able to withstand stringent environmental conditions. This paper investigated possible sources of voiding in the dispensed glob-top material used in COBs. Factors such as substrate temperature, substrate preheat time, dispensing parameters, globtop thawing condition and curing profile were examined. The detection and quantification of voids was performed by C-mode and tomographic acoustic micro imaging (TAMI/sup TM/) mode scanning acoustic microscopy. It was found that voiding behavior was material dependent. Increased pot-life increased void density. It was observed that with optimized substrate temperature and preheat time, the number of voids could be reduced significantly. Also, materials cured at higher than recommended temperatures are more susceptible to voids at the globtop-substrate interface.
Starting Page	251
Ending Page	256
File Size	1421193
Page Count	6
File Format	PDF
ISBN	0780366549
DOI	10.1109/EMAP.2000.904163
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-11-30
Publisher Place	China
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Temperature Wire Moisture Integrated circuit packaging Printed circuits Curing Stress Encapsulation Viscosity Spirals
Content Type	Text
Resource Type	Article

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