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Soldering external connections to thin film systems
Author(s) -
Keller H. N.,
Morabito J. M.
Publication year - 1981
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740030108
Subject(s) - intermetallic , soldering , materials science , thin film , metallurgy , dissolution , brittleness , thermocompression bonding , tin , alloy , composite material , layer (electronics) , nanotechnology , chemistry
External connections to thin film hybrid integrated circuits (HICs) by solder bonding have several advantages over those bonded by solid phase or thermocompression bonding. This paper reviews these advantages and discusses the parameters necessary for high strength, reliable solder joints to thin films. Dissolution of the soluble thin film(s) into solder limits the solder reflow times. Recent work has shown that dissolution rates of thin films in solder depend primarily on the degree of thin film heat treatment prior to soldering, substrate surface texture, and the method of thin film deposition. Auger in‐depth profiling data show that alloy formation and internal oxidation reduces film dissolution during solder reflow. Metallographic sectioning and chemical analysis are used to identify weak solder bond interfaces which result from intermetallic formation. Tin from the solder diffuses rapidly and reacts with soluble metals such as gold, palladium and copper to form brittle intermetallics such as AuSn 4 , PdSn 4 and Cu 6 Sn 5 . Intermetallic formation between the solder and the thin film systems of interest can affect joint strength and reliability.