Edge effects in intermetallic compound crystal growth between Nb and molten 52 In - 48 Sn solder

• Published in: Applied physics letters Vol. 88; no. 10; pp. 104105 - 104105-3
• Main Authors: Li, J. F., Mannan, S. H., Clode, M. P.
• Format: Journal Article
• Published: American Institute of Physics 10-03-2006
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2186392

A solder/substrate couple consisting of a Nb substrate and eutectic
52
In
-
48
Sn
solder shows promise for high-temperature liquid solder interconnects. In this letter, the intermetallic compound (IMC) crystal growth between vacuum-sputtered Nb film and molten
52
In
-
48
Sn
solder at four temperatures; 192, 220, 240, and
260
°
C
, was investigated employing samples with a solder/substrate interface area of
7
mm
by
7
mm
. It was found that at all four temperatures, the IMC crystals nucleated and grew first at the corners of the substrate, followed by the edges, and then gradually covered the entire interface. This result, can be explained if the initiation of IMC crystal growth is diffusion controlled, and the value of the Nb diffusion coefficient is estimated with the aid of a three-dimensional numerical simulation.