The properties of tin-bismuth alloy solders

Abstract

Tin-bismuth alloys may be an alternative to lead-based solders for low-temperature applications, but very little is known about their manufacturability and reliability. This article presents an overview of these issues. First, experiments to determine the wetting properties of the Sn-Bi solder are presented. The results show that Sn-Bi solders do not wet bare copper well, but that they do wet copper having a hot-dipped Sn-Bi coating. Next, the effects of aging on the microstructure of Sn-Bi solders are described. The results show that during aging, tin is de-pleted from the solder/base metal interface. The two-phase Sn-Bi microstructure coarsens during aging; the rate of coarsening can be slowed by adding 1.0 wt. % Cu to the solder. The aging also affects the shear strength of the solder jOints, where aged joints show an increase in maximum shear stress and ductility at failure.

Wetting interaction between Sn-Zn-Ag solders and Cu

“…Binary alloys investigated include Sn-Ag, Sn-Au, Sn-Zn, Sn-Cd, Sn-Sb, and many others. [1][2][3][4][5][6][7][8] Ternary alloys of Sn-AgZn, 9 Sn-Zn-In, 10,11 Sn-Ag-Sb, 12 Bi-Sb-Sn, 13 Sn-BiAg, 14 Sn-Ag-Cu, 15 and Sn-Zn-Al 16 have been reported. Among these, Sn-Ag-Cu is one of the most frequently mentioned potential candidate systems for Pb-free solder.…”

Interfacial Reactions Between Sn-58 mass%Bi Eutectic Solder and (Cu, Electroless Ni-P/Cu) Substrate

“…Also, when compared to the Sn-Pb eutectic solder, the Sn-58Bi eutectic solder offers a higher strength and superior creep resistance but a lower ductility. [5][6][7][8][9] During soldering, the solder alloy melts and then reacts with the substrate to form intermetallic compounds at the joint interface. The growth of interfacial reaction products through solid-state aging in solder joints is of particular interest to the electronics industry.…”

Sn-Zn-Al Pb-free solder—An inherent barrier solder for Cu contact

“…It is seen that, besides Cu, there is Al 4.2 Cu 3.2 Zn 0.7 compound. An increase in soldering temperature simplifies the crystal plane from various facets to (1,0,10). This compound layer is attributed for the "inherent barrier" behavior of the Sn-Zn-Al solder when in contact with Cu pad or Cu substrate.…”

“…Binary alloys investigated include Sn-Ag, Sn-Au, Sn-Zn, Sn-Cd, Sn-Sb, and many others. [7][8][9][10][11][12][13][14] Ternary alloys include Sn-Ag-Zn, 15 Sn-ZnIn, 16,17 Sn-Ag-Sb, 18 Bi-Sb-Sn, 19 Sn-Bi-Ag, 20 Sn-Ag-Cu, 21 and Sn-Zn-Al. 22 It is seen that all the reported solders are Sn-rich alloys.…”