Purpose -The purpose of this work is to study the effect of the reflow peak temperature and time above liquidus on both SnPb and SnAgCu solder joint shear strength. Design/methodology/approach -Nine reflow profiles for Sn3.0Ag0.5Cu and nine reflow profiles for Sn37Pb have been developed with three levels of peak temperature (2308C, 2408C, and 2508C for Sn3.0Ag0.5Cu; and 1958C, 2058C, and 2158C for Sn37Pb) and three levels of time above solder liquidus temperature (30, 60, and 90 s). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear forces for the resistors were measured after assembly. The fracture interfaces were inspected using scanning electron microscopy with energy dispersive spectroscopy in order to determine the failure mode and failure surface morphology. Findings -The results show that the effects of the peak temperature and the time above solder liquidus temperature are not consistent between different component sizes and between Sn37Pb and Sn3.0Ag0.5Cu solder. The shear force of SnPb solder joints is higher than that of Sn3.0Ag0.5Cu solder joints because the wetting of SnPb is better than that of SnAgCu. Research limitations/implications -This study finds that fracture occurred partially in the termination metallization and partially in the bulk solder joint. To eliminate the effect of the termination metallization, future research is recommended to conduct the same study on solder joints without component attachment. Practical implications -The shear strength of both SnPb and SnAgCu solder joints is equal to or higher than that of the termination metallization for the components tested. Originality/value -Fracture was observed to occur partially in the termination metallization (Ag layer) and partially in the bulk solder joint. Therefore, it is essential to inspect the fracture interfaces when comparing solder joint shear strength.

Purpose -The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for Sn3.0Ag0.5Cu (SAC305) soldered joints. Design/methodology/approach -A four-factor factorial design with three replications is selected in the experiment. The input variables are the peak temperature, the duration of time above solder liquidus temperature (TAL), solder alloy and thermal shock. The peak temperature has three levels, 12, 22 and 328C above solder liquidus temperatures (or 230, 240 and 2508C for SAC305 and 195, 205, and 2158C for SnPb). The TAL has two levels, 30 and 90 s. The thermally shocked test vehicles are subjected to air-to-air thermal shock conditioning from 2 40 to 1258C with 30 min dwell times (or 1 h/ cycle) for 500 cycles. Samples both from the initial time zero and after thermal shock are cross-sectioned. The IMC thickness is measured using scanning electron microscopy. Statistical analyses are conducted to compare the difference in IMC thickness growth between SAC305 solder joints and SnPb solder joints, and the difference in IMC thickness growth between after thermal shock and after thermal aging. Findings -The IMC thickness increases with higher reflow peak temperature and longer time above liquidus. The IMC layer of SAC305 soldered joints is statistically significantly thicker than that of SnPb soldered joints when reflowed at comparable peak temperatures above liquidus and the same time above liquidus. Thermal conditioning leads to a smoother and thicker IMC layer. Thermal shock contributes to IMC growth merely through hightemperature conditioning. The IMC thickness increases in SAC305 soldered joints after thermal shock or thermal aging are generally in agreement with prediction models such as that proposed by Hwang. Research limitations/implications -It is still unknown which thickness of IMC layer could result in damage to the solder. Practical implications -The IMC thickness of all samples is below 3 mm for both SnPb and SAC305 solder joints reflowed at the peak temperature ranging from 12 to 328C above liquidus temperature and at times above liquidus ranging from 30 to 90 s. The IMC thickness is below 4 mm after subjecting to air-to-air thermal shock from 2 40 to 1258C with 30 min dwell time for 500 cycles or thermal aging at 1258C for 250 h. Originality/value -The paper reports experimental results of IMC thickness at different thermal conditions. The application is useful for understanding the thickness growth of the IMC layer at various thermal conditions.