NDLI: Flip chip underfill flow characteristics and prediction

Content Provider	IEEE Xplore Digital Library
Author	Fine, P. Cobb, B. Nguyen, L.
Copyright Year	1999
Abstract	This paper presents recent results on underfill flow characterization. The flow properties of a number of commercial and experimental underfills were recorded and analyzed using quartz test chips with specially designed bump patterns (e.g., peripheral, full array, and mixed designs). Each was bonded onto an organic laminate substrate to form a flip chip package. Underfill was then applied to the packages and flow time, filler settling, and air entrapment were evaluated. Good flow can be described in terms of three measurable parameters, namely, viscosity, contact angle, and more importantly, filler size and distribution. Viscosity and contact angle are commonly used in Hele Shaw and Washburn models. However, these models do not take filler properties into consideration. In general, underfills with particles less than 5 /spl mu/m exhibited faster and more uniform flow fronts than materials with larger particles. The best flowing materials worked well with standoff heights between 50 and 75 /spl mu/m, while the poorer flowing materials showed streaking, voiding, and fingering at these heights. At gaps of 25 /spl mu/m, however, nearly all the materials exhibited pronounced and reproducible streaking.
Sponsorship	IEEE Components, Packaging, and Manufacturing Technology Society
Starting Page	420
Ending Page	427
Page Count	8
File Size	1653366
File Format	PDF
ISSN	15213331
Volume Number	23
Issue Number	3
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-09-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Flip chip Testing Packaging Viscosity Manufacturing Pattern analysis Bonding Laminates Semiconductor device measurement Size measurement
Content Type	Text
Resource Type	Article
Subject	Electronic, Optical and Magnetic Materials Electrical and Electronic Engineering

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