Pb free solder for electronics assemblies is fast becoming a reality primarily because of market driven forces. This impacts the entire electronic manufacturing industry, from component supplier to equipment manufacturer. While the industry has identified possible alternates to Sn/Pb solder alloy, much work still needs to be done, especially in the area of component & board level reliability an...

Skin effect of lead-free solder joints is investigated over a wide frequency band. Contrary to common believe that ‘effective impedance of solder alloys increases with frequency’, resistance tends to saturate when frequency reaches a critical value, 10 MHz for SAC solder alloys. Negative surface impedance growth rate is observed when employs square waveform AC current loading at high current de...

Failure of solder joints under shear frequently occurs along a path near and parallel to, but not necessarily exactly at, the interface between the alloy and the bonding material. A numerical finite element analysis was employed to simulate the deformation in solder during cyclic lap-shear testing. High magnitudes of equivalent plastic strain were seen to initiate from the corner regions and sp...

As the second part to a paper presented at the 2004 SMTA Pan Pacific Symposium, this paper further summarizes the results from technical qualification of the Ni/Pd/Au process. Whereas the previous paper examined the wire bonding capabilities of this surface finish, this second paper focuses specific attention to BGA applications. In these investigations, the solder joint integrity is measured u...

Lead-free selective soldering can result in extended times at high temperatures, which in turn can result in excessive dissolution of exposed copper, such as plated through holes. This phenomenon is more severe with lead-free, since the alloys have higher melting points, hence requiring longer times for the PTH to reach the higher temperatures, and the alloys typically have a greater capacity t...

The electrochemical behaviors of eight parent alloys and four post-solder alloys used in dental prostheses were specified in a (pH=7.4; [NaCl]=9g/L)-aqueous solution at 37°C. For each alloy, the free potential was followed during two hours, and a cyclic polarization between the cathodic domain and the solvent’s oxidation was performed. The galvanic corrosion between each parent alloy and its us...

In this paper, Moir e interferometry technique is used to measure the in situ displacement evolution of lead-free solder joint under electric current stressing. Large deformation was observed in solder joint under high density (10 A/cm) current stressing. The deformation was found to be due to electromigration in the solder joint. An electromigration constitutive model is applied to simulate de...