SMTA International Conference Proceedings


Authors: Ning-Cheng Lee, Ph.D.
Company: Indium Corporation of America
Date Published: 10/11/2007   Conference: SMTA International

Abstract: In general, new lead-free solder alloys with the following characteristics are desired in order to enable the continuation of miniaturization trend: (1) alloy with a reduced melting temperature, (2) alloy with a better solder spread, (3) alloy with a slower wetting speed at melting temperature, (4) a softer alloy, or alloy with a reduced voiding tendency or greater ductility, (5) alloy with a refined grain size, (6) alloy with low tendency to form large IMC plate, (7) alloy with a higher resistance toward corrosion and electrochemical migration, (8) alloy with a greater oxidation resistance. On the other hand, no-clean fluxes with the following features are needed: (1) reduced volatile, (2) halidefree, (3) greater fluxing capacity, (4) higher residue resistivity, (5) more resistant to oxidation and charring, (6) more efficient oxidation barrier, (7) lower activation temperature, (8) slower wetting speed when solder begins to melt, (9) less spattering, (10) higher probe penetrability, (11) capability of inducing nucleation of solder upon cooling, and (12) greater resistance against slump.

Key words: solder alloys, flux, lead-free, miniaturization.

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