The world is moving rapidly toward green manufacturing. The miniaturisation trend of the electronics industry is constantly imposing new criteria, making the selection of ideal Pb-free alloys a moving target. Dr. Ning-Cheng Lee looks at the challenges posed by miniaturisation to both solders and fluxes. Miniaturisation not only poses challenges to the solder market, flux chemistry is also complicated due to requirements for no-clean applications and the increasing amount of oxides. But first the considerations for solder alloys. Reducing the size of microvias in pads will inevitably result in a greater sensitivity toward CTE mismatch. In addition, reducing the pitch dimension will significantly increase the chance of a circuit short caused by conductive anodic filament. To avoid the problems described above, a lower soldering temperature is highly desirable.
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