NDLI: Investigation of cure kinetics and its effect on adhesion strength of nonconductive adhesives used in flip chip assembly

Content Provider	IEEE Xplore Digital Library
Author	Yu, H. Mhaisalkar, S.G. Wong, E.H. Teh, L.K. Wong, C.C.
Copyright Year	1999
Abstract	The reaction kinetics of a commercial fast cure nonconductive adhesive has been systematically investigated using differential scanning calorimetry. Samples were isothermally cured at temperatures from 120 to 160/spl deg/C and dynamically cured at ramp rates between 5 and 20/spl deg/C/min. A good agreement between the autocatalytic kinetic model prediction and experimental results was demonstrated. Deviation occurred at high degrees of cure for curing below 140/spl deg/C due to the occurrence of vitrification. Additionally, by comparing the dynamic cure prediction with the isothermal experiment, good agreements and equivalence were demonstrated. As such, it is possible to predict the isothermal reaction behavior of fast cure materials at high temperature provided that the variation between the actual temperature of the heating system and the setting temperature is not large. Furthermore, the effect of curing process on the adhesion strength has been demonstrated by testing the shear strength of lap joint specimens. It was found that the evolution of adhesion strength was largely dependent on the buildup of mechanical properties during the curing process. At low and medium degrees of cure, cohesive and adhesive failures were respectively observed, while at high degrees of cure, adhesion strength surpassing the shear strength of the solder mask was observed. The sharp increase in adhesion strength was observed to coincide with the gelation point marked by the crossover between the storage and loss modulii, thus suggesting that the contributors to adhesion strength include mechanical interlocking as well as chemical bonding, as evidenced by buildup of storage modulus and mechanical strength of the adhesive.
Sponsorship	IEEE Components, Packaging, and Manufacturing Technology Society
Starting Page	71
Ending Page	79
Page Count	9
File Size	1067535
File Format	PDF
ISSN	15213331
Volume Number	29
Issue Number	1
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2006-01-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Kinetic theory Nonconductive adhesives Flip chip Assembly Temperature Curing Isothermal processes Calorimetry Predictive models Vitrification vitrification Adhesion strength cure kinetics flip chip gelation nonconductive adhesives (NCAs)
Content Type	Text
Resource Type	Article
Subject	Electronic, Optical and Magnetic Materials Electrical and Electronic Engineering

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