Japan's largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies

This study aims to evaluate solder joint reliability under high speed impact tests using nanoindentation properties of intermetallic compounds (IMCs) at the joint interface. Sn–Ag based solder joints with different kinds of interfacial IMCs were obtained through the design of solder alloy/substrate material combinations. Nanoindentation was applied to investigate the mechanical properties of IMCs, including hardness, Young’s modulus, work hardening exponent, yield strength, and plastic ability. Experimental results suggest that nanoindentation responses of IMCs at joint interface definitely dominates joint impact performance. The greater the plastic ability the interfacial IMC exhibits, the superior impact energy the solder joints possess. The concept of mechanical and geometrical discontinuities was also proposed to explain brittle fracture of the solder joints with bi-layer interfacial IMCs subject to impact load.

In order to conquer the limitation of conventional solders and adhesives used in electronics packaging, a novel self-organized joining process using conductive adhesive with low melting point alloy was proposed. As a basic characteristic of the adhesive paste, the differential scanning calorimetry analysis was carried out. Joint morphology, the formation of conduction path, and the self-organized characteristics were examined. Melting fillers were preserved their initial spherelike form for nonreductive adhesive, although enlargement of the alloy colony occurred in the case of the reductive polymer. The formation of a conduction path can be controlled significantly by varying the resin performance and the process parameters such as the joint height and the volume fraction of filler. The self-organized characteristic was observed on the copper line patterned glass-epoxy substrate. The matched pair of substrates could be interconnected with excellent self-organized joint.