Modeling of localized reflow in solder/magnetic nanocomposites for area-array packaging

Abstract

We have modeled the reflow process of FeCo magnetic nanoparticle (MNP)-based solder composites with eddy current power loss of substrate and magnetic power losses of solder bumps. For an area array package without MNPs when subjected to 300 kHz ac magnetic field, the eddy current power loss can result in excessive temperatures that can cause substrate damage. Temperature profiles with different MNP concentration were simulated and the results showed localized reflow of solders to enable low-temperature assembly. The temperatures at different times and positions in solder composites were analyzed. We also modeled thermal profiles for solder composites with 0.2 wt. % MNP in 1 MHz and 3 MHz magnetic field. Such high field frequency generated larger power losses in MNPs and is shown to increase the heating efficiency.

A Modular Solder System with Hierarchical Morphology and Backward Compatibility

“…That is to say, the core–shell structure of the catalytic nanostructures has two phase interfaces able to render the junction for the rich catalytic performance and to be even more beneficial to the synergistic effects, thereby maximizing the functions attained from the other modular solder constituents . Just like in the previous case, Fe 3 O 4 @CeO 2 nanostructures can be added instead of the catalytic nanostructures to induce magnetization for induction‐coupled soldering with high‐throughput energy efficiency and thus provide uniform thermal distribution that minimizes the eddy currents in induction‐coupled heating equipment . Overall, the introduction of the unique topographical features of the micropowders and nanoparticles in the hybrid solder system and the simultaneous adoption of the unique backward compatibility can significantly increase its potential by creating a solder with the intended properties based on each underlying constituent.…”