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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.

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 32°C above solder liquidus temperatures (or 230, 240 and 250°C for SAC305 and 195, 205, and 215°C 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 −40 to 125°C 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.

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 high‐temperature 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.

It is still unknown which thickness of IMC layer could result in damage to the solder.

The IMC thickness of all samples is below 3 μm for both SnPb and SAC305 solder joints reflowed at the peak temperature ranging from 12 to 32°C above liquidus temperature and at times above liquidus ranging from 30 to 90 s. The IMC thickness is below 4 μm after subjecting to air‐to‐air thermal shock from −40 to 125°C with 30 min dwell time for 500 cycles or thermal aging at 125°C for 250 h.

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.

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.

Nine reflow profiles for Sn3.0Ag0.5Cu and nine reflow profiles for Sn37Pb have been developed with three levels of peak temperature (230°C, 240°C, and 250°C for Sn3.0Ag0.5Cu; and 195°C, 205°C, and 215°C 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.

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.

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.

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.

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.

This study aims to contribute to literature on mobile learning (m-learning) by proposing four research clusters whereby scholars can expand m-learning research to facilitate effective learning experiences for students.

This study reviews student-centric literature on m-learning since 2010 and presents insights on m-learning while applying well-established bibliometric techniques. Consequently, 722 articles published in the past decade were evaluated by identifying key research areas, most influential authors, countries, journals and organisations. Most influential studies based on number of citations were also examined.

Through article co-citation analysis, four clusters representing m-learning literature were identified: concept of m-learning, application of m-learning in education, designing framework for model learning/acceptance and emerging technologies.

As mobile learning (m-learning) has undergone an evolution from being an emerging field to a significant teaching and research tool, it is pertinent to explore and identify the trends of m-learning research.