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. © 2013 American Institute of Physics.