Solder/substrate interfacial thermal conductance and wetting angles of Bi-Ag solder alloys

Autor(es)

Silva, Bismarck Luiz ^[1] ; Bertelli, Felipe ^{[2, 3]} ; Cante, Manuel V. ^[4] ; Spinelli, Jose E. ^[1] ; Cheung, Noe ^[4] ; Garcia, Amauri ^[4]

Afiliação do(s) autor(es)

^[1] Fed Univ Sao Carlos UFSCar, Dept Mat Engn, BR-13565905 Sao Carlos, SP - Brazil

^[2] Santa Cecilia Univ UNISANTA, Dept Mech Engn, BR-11045040 Santos, SP - Brazil

^[3] Santa Cecilia Univ UNISANTA, Postgrad Program Mech Engn, BR-11045040 Santos, SP - Brazil

^[4] Univ Estadual Campinas, UNICAMP, Dept Mfg & Mat Engn, BR-13083860 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS; v. 27, n. 2, p. 1994-2003, FEB 2016.
• Citações Web of Science: 7

Resumo

Bi-Ag lead-free alloys are considered interesting alternatives to Pb-based traditional solders due to compatible melting point and strength. During soldering, the ability of a liquid alloy to flow or spread over the substrate is crucial for the formation of a metallic bond driven by the physicochemical properties of the liquid solder/solid substrate system. In addition, the wettability is intimately associated with the solder/substrate thermal conductance represented by a heat transfer coefficient, h(i). In this work, three Bi-Ag alloys (hypoeutectic-1.5 wt%Ag, eutectic-2.5 wt%Ag and hypereutectic-4.0 wt%Ag) were directionally solidified under upward unsteady state heat flow conditions. Both time-dependent h(i) profiles and wetting behavior represented by contact angles (theta) were determined for the three alloys examined. The dependence of theta on the alloy Ag content is assessed experimentally. Also, thermal readings collected during directional solidification of the Bi 1.5, 2.5 and 4.0 wt% Ag alloys are used with a view to permitting h(i) versus time (t) profiles to be computed. It is shown that along a first solidification stage (t < 16 s) the h(i) values followed the trend experimentally observed by the contact angles for the three alloys examined, while for t > 16 s the volumetric expansion of the Bi-rich phase is shown to have a dominant role inducing a sudden increase in h(i). For each alloy a couple of time-dependent h(i) expressions is needed to represent the entire solidification progress. (AU)

• Processo FAPESP: 13/13030-5 - Microestrutura, parâmetros térmicos, segregação e propriedades mecânicas de ligas alternativas de soldagem à base de Sn, Zn e Bi
• Beneficiário: José Eduardo Spinelli
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/08259-3 - Desenvolvimento microestrutural e do comportamento mecânico de ligas alternativas de soldagem Sn-Bi-Cu e Sn-Bi-Ag
• Beneficiário: Bismarck Luiz Silva
• Modalidade de apoio: Bolsas no Brasil - Doutorado