Embedded Capacitive Filter Units in LTCC for the Protection of Active Implantable Medical Devices

Abstract

We investigate the compact integration of passive capacitive filter units embedded in low-temperature cofired ceramics for active implantable medical devices. The goal lies in avoiding volume consumption by large passive components and to achieve a miniaturized integration of filters for the reduction of induced radio frequency currents and voltages during magnetic resonance imaging. Embedding such filter units inside the substrates carrying the electronics can be a promising solution for implants to allow higher channel densities with only a marginal increase in implant's size. By combining laser ablation and screen printing manufacturing technologies, we investigated a fabrication process for multilevel ceramic capacitors (MLCCs) in low temperature co-fired ceramic (LTCC) substrates resulting in mean capacitances of 220 pF, (10 × 0.4 × 0.62 mm3) with a dissipation factor of 0.42% and a breakdown voltage of 500 V. Dissolution of the material during accelerated aging tests however raises concerns over its biostability and biocompatibility during chronic implantation and needs further testing.