Inductive heating based on VHF-ISM radio band frequencies as technology platform for efficient heating of metallic micro-scaled bonding layers in MEMS packaging

This paper presents a method for selective and energy-efficient induction heating of metallic microstructures to support and enhance metal bonding technologies for MEMS packaging. The technological challenges include the use of miniaturized coils for homogeneous heat distribution, the implementation of VHF-ISM radio band frequencies up to f<inf>0</inf> = 40.68 MHz for the generation of high frequency electromagnetic fields and the integration of the inductive equipment into a heating and bonding system. FE simulation and infrared (IR) thermography were used to characterize the inductive process with low coil currents of I<inf>0</inf> < 30 A and very fast heating rates of T = 150 K/s. As a result, bonding times and pressures can be reduced significantly.