Dresden 2003 – scientific programme

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M: Metallphysik

M 31: Intermetallische Phasen I

M 31.3: Talk

Wednesday, March 26, 2003, 15:15–15:30, IFW B

Analysis of Cu/Sn and Cu/SnPb solder reaction — •Jens Görlich¹ and Guido Schmitz² — ¹Institut für Materialphysik, Univ. Göttingen, Hospitalstr. 3-7, 37073 Göttingen, Germany — ²Institut für Materialphysik, Univ. Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany

Soldering is a well known technological process. However, recent developments in microelectronic packaging suggest to re-investigate the interreaction of the base material copper with the liquid solder in detail, in order to reduce the size of solder joints. Formation of the intermetallic Cu₆Sn₅ is essential for the joining. Instead of a planar reaction layer known from solid state reactions, the intermetallic phase forms in a rough, scallop-like structure, which leads to high reaction rates that hinder a further size reduction. This process of scallop formation is studied by scanning and transmission electron microscopy. Observed size distributions and growth kinetics are discussed on the basis of recent theoretical formulations [1]. For comparison, also sputter-deposited planar thin films of Cu₆Sn₅ haven been used as base material.

[1] A.M. Gusak, Phys. Rev. B 66, 115403 (2002)