Publications Details
Development of Alternatives to Pb-Based Solders
An experimental program was performed that examined the physical and mechanical properties of several candidate, lead (Pb)-free solder alloys. The project was separated into three tasks designated as follows: (1) Alloy Development, (2) Intermetallic Compound (IMC) Growth, and (3) Mechanical Testing. Task 1, Alloy Development, examined the impact that small Pb additions had on the physical and mechanical properties of several Pb-free solders. Task 2, Intermetallic Compound (IMC) Growth investigated the development of the IMC layer between several Pb-free solder alloys and Cu. Quantitative analyses established the kinetics of layer growth in the solid state as a result of elevated temperature aging treatments, and as a function of the composition of the solder. Liquid state IMC layer growth as well as dissolution rates of Cu substrates by molten solders were quantitatively documented. Task 3, Mechanical Properties, performed a series of experiments that provided fracture toughness measurement, thermomechanical fatigue evaluations, and creep deformation data on a number of the Pb-free solders as well as on Pb-free alloys that had been contaminated with controlled quantities of Pb additions. The data obtained from these tests results relative performance information as well as valuable input data for computer models. Several ancillary tests were also performed to support partner company efforts.