NDLI: Development of high performance surface mount conductive adhesives

Content Provider	IEEE Xplore Digital Library
Author	Daoqiang Lu Wong, C.P. Tong, Q.K. Zhang, E.
Copyright Year	2000
Description	Author affiliation: Packaging Res. Center, Georgia Inst. of Technol., Atlanta, GA, USA (Daoqiang Lu)
Abstract	Electrically conductive adhesives (ECAs) are an environmentally friendly alternative to tin/lead (Sn/Pb) solders for surface mount applications. Compared to Sn/Pb solders, conductive adhesive technology offers numerous advantages. However, this new technology, still has limitations. Two critical ones are the unstable contact resistance on non-noble metals and the inferior impact performance. The ultimate goal of our study has been to develop conductive adhesives with stable contact resistance and superior impact performance. Our previous study indicated that electrochemical (galvanic) corrosion was the predominant mechanism for the unstable contact resistance during elevated temperature and humidity aging. In this study, the effects of several additives (oxygen scavengers and corrosion inhibitors) on contact resistance stability during elevated temperature and humidity aging have been investigated. Effective additives have been identified based on the evaluation results. The adsorption of the additives on Sn/Pb solder surface are studied and correlated to their effectiveness to prevent the electrochemical corrosion. In addition, several rubber-modified epoxy resins and epoxide-terminated polyurethane resins have been introduced into the adhesive formulations to determine their effects on impact strength. Tan /spl delta/ of each formulation was measured using a dynamic mechanical analyzer (DMA) and impact strength was evaluated using drop test. Resins that improve the impact strength of adhesives have been identified. Finally, high performance conductive adhesives have been formulated by combining the identified resins with the effective additives. It is found that (1) the oxygen scavengers tested can delay the resistance increase of the adhesives; (2) the effectiveness of the best performing corrosion inhibitor is probably due to its strong adsorption to the metal surfaces; (3) some rubber modified epoxy resins and epoxide-terminated polyurethane resins provide the superior impact performance of conductive adhesives; and (4) conductive adhesives with both stable contact resistance and superior impact performance can be developed based on the above findings.
Starting Page	892
Ending Page	898
File Size	782785
Page Count	7
File Format	PDF
ISBN	0780359089
DOI	10.1109/ECTC.2000.853270
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-05-21
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Conductive adhesives Contact resistance Tin Surface resistance Resins Lead Additives Corrosion Temperature Humidity
Content Type	Text
Resource Type	Article

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