NDLI: Comparing the Impacts of the Capillary and the Molded Underfill Process on the Reliability of the Flip-Chip BGA

Content Provider	IEEE Xplore Digital Library
Author	Chen, K.M.
Copyright Year	1999
Abstract	In the assembly process for the conventional capillary underfill (CUF) flip-chip ball grid array (FCBGA) packaging the underfill dispensing creates bottleneck. The material property of the underfill, the dispensing pattern and the curing profile all have a significant impact on the flip-chip packaging reliability. Due to the demand for high performance in the CPU, graphics and communication market, the large die size with more integrated functions using the low-K chip must meet the reliability criteria and the high thermal dissipation. In addition, the coplanarity of the flip-chip package has become a major challenge for large die packaging. This work investigates the impact of the CUF and the novel molded underfill (MUF) processes on solder bumps, low-K chip and solder ball stress, packaging coplanarity and reliability. Compared to the conventional CUF FCBGA, the proposed MUF FCBGA packaging provides superior solder bump protection, packaging coplanarity and reliability. This strong solder bump protection and high packaging reliability is due to the low coefficient of thermal expansion and high modulus of the molding compound. According to the simulation results, the maximum stress of the solder bumps, chip and packaging coplanarity of the MUF FCBGA shows a remarkable improvement over the CUF FCBGA, by 58.3%, 8.4%, and 41.8% (66 mum), respectively. The results of the present study indicates that the MUF packaging is adequate for large die sizes and large packaging sizes, especially for the low-K chip and all kinds of solder bump compositions such as eutectic tin-lead, high lead, and lead free bumps.
Sponsorship	IEEE Components, Packaging, and Manufacturing Technology Society
Starting Page	586
Ending Page	591
Page Count	6
File Size	5264232
File Format	PDF
ISSN	15213331
Volume Number	31
Issue Number	3
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2008-09-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Thermal stresses Protection Environmentally friendly manufacturing techniques Lead Assembly Electronics packaging Material properties Curing Materials reliability Graphics underfill Coplanarity flip-chip reliability
Content Type	Text
Resource Type	Article
Subject	Electronic, Optical and Magnetic Materials Electrical and Electronic Engineering

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