Effect of Specimen Size and Aging on Tensile Properties of Sn-Ag-Cu Lead-Free Solders

Abstract

Tensile properties of several Sn-Ag-Cu lead-free solders have been investigated by micro size specimens. For as-cast specimens, tensile strength increases with increasing content of Cu and Ag. After aging at 120 C for 168 h, however, tensile strengths are similar among eutectic and hypereutectic alloys. The similar tendency was observed among hypoeutectic alloys. Moreover, negligible change was found in tensile strength between specimens aged at 120 C for 168 h and 504 h in all solders. The strength change with aging corresponds to microstructural change of the solder. In the cases of eutectic and hypoeutectic alloys, as-cast microstructures are composed of coarsened primary Sn phases and finer eutectic phases of Sn and intermetallic compounds. The primary Sn phases and the eutectic phases are homogenized upon aging. In contrast, finer Sn and eutectic phases are formed in as-cast hypereutectic alloys. The finer phases are coarsened upon aging. After aging, homogenization of the Sn phases and the eutectic phases occurred in all solders.

Effect of Shear Speed on the Ball Shear Strength of Sn-3Ag-0.5Cu Solder Ball Joints

“…Fracture surfaces after the test were observed with the EPMA to investigate the fracture mode. Since it has been reported that there are at most only a few grains in CSP joints with a Sn-Ag-Cu solder [19] and in micro size specimens on a similar scale to CSP solder joints, [20][21][22][23][24] a transgranular fracture seems to have occurred in the joints. Therefore, the decrease of shear On the other hand, the fracture mode changes from solder fractures to IMC fractures at higher shear speed (above 0.5 m/s) regardless of aging conditions.…”

Development of high reliability lead-free solder joint dispersed IMC pillar

“…[1] Sn-Ag-Cu lead-free solder such as Sn-3.0Ag-0.5Cu (mass%) has been spread in various electronics products as the substitute of SnPb eutectic solder. [2][3][4] For automotive applications, similar request has been also required. In the case of packaging substrates used in automotive products such as power modules, a high-reliable relatively large joint area is required.…”

Effect of third element addition on joint strength of low-Ag lead-free solder

“…Although Sn-3.0Ag-0.5Cu solder has approximately 35 higher liduidus temperature than that of conventional Sn-Pb eutectic solder, it has excellent mechanical strength [1] and sufficient properties as a soldering material. [2,3] However, the material cost is very high due to including high cost Ag so that low-Ag lead-free solder has been required in order to reduce the material cost.…”