Dissolution Kinetics of Nickel in Lead-Free Sn-Bi-In-Zn-Sb Soldering Alloys
- PDF / 776,091 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 52 Downloads / 218 Views
0993-E03-01
Dissolution Kinetics of Nickel in Lead-Free Sn-Bi-In-Zn-Sb Soldering Alloys Katayun Barmak1, David C. Berry1, Vira G. Khoruzha2, Kostyantyn A. Meleshevich2 and Vasyl I. Dybkov2 1 Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213 2 Department of Physical Chemistry of Inorganic Materials, Institute for Problems of Materials Science, Kyiv, 03180, Ukraine
ABSTRACT The dissolution process of nickel in liquid Pb-free 87.5% Sn-7.5% Bi-3% In-1% Zn-1% Sb and 80% Sn-15% Bi-3% In-1% Zn-1% Sb soldering alloys has been investigated by the rotating disc technique at 250-450°C. The temperature dependence of the nickel solubility in the solders obeys a relation of the Arrhenius type cs = 4.94 × 102 exp (–39500/RT) % for the former alloy and cs = 4.19 × 102 exp (–40200/RT) % for the latter, where R is in J mol–1 K–1 (8.314 J mol–1 K–1) and T in K. The solubility values of nickel in the alloys differ considerably, while the dissolution rate constants are rather close. The data presented can be used to evaluate (i) the thickness of the dissolved portion of the solid nickel material during soldering, (ii) the extent of saturation of a solder with nickel and (iii) the effect of dissolution on the growth rate of intermetallic layers at the Ni-solder interface. INTRODUCTION Because of the toxicity of lead, conventional Sn-Pb solders are gradually being replaced with Sn-base soldering alloys containing additions of other metals (Ag, Bi, Ga, In, Zn, Sb, etc.) [1-8]. To avoid the excessive loss of solid metals in contact with the alloys during soldering, data on metal dissolution rates in molten solders are needed. In this work, the results of investigation of the dissolution kinetics of nickel in liquid 87.5% Sn-7.5% Bi-3% In-1% Zn-1% Sb and 80% Sn-15% Bi-3% In-1% Zn-1% Sb soldering alloys at 250-450ºC are reported. According to binary phase diagrams [9], all four additives lower the melting-point temperature of tin. To avoid undesirable phase transformations, indium, zinc and antimony were taken in the amounts, not exceeding their solid-state solubility limits in tin. These elements are known to improve service characteristics of Sn-base solders [10]. EXPERIMENTAL DETAILS Electrolytic-grade nickel plates (99.98% Ni), tin (99.93% Sn), bismuth (99.999% Bi) and indium (99.999% In) slabs, and zinc granules (99.94% Zn) were employed for the investigation. The process of dissolution of nickel in liquid Pb-free Sn-base soldering alloys was studied by the rotating disc technique using a rapid-quenching device [11].
Briefly, the experimental procedure was as follows. To heat the materials under investigation to the required temperature and to maintain it, the electric-resistance furnace is employed. A flux is used both to pre-heat the solid specimen to the experimental temperature and to protect the melt from oxidation by atmospheric air. Before the experiment, the solid nickel specimen, 11.28 ± 0.02 mm in diameter (1 cm2 area) and 5-6 mm high, is pressed into a graphite tube, 16 mm i
Data Loading...
