Hybrid LTCC–Polyimide Approach for High-Sensitivity Mechanical Sensing Applications

TL;DR

A new hybrid ceramic and flexible material platform improves mechanical sensor sensitivity and adaptability for electronics.

Contribution

A hybrid LTCC-polyimide platform with tunable RF components for high-sensitivity mechanical sensing.

Findings

Inductance tuning achieved 48% range with 0.715 nH/mN sensitivity.

Capacitance tuning reached 36% range with 47.3 fF/mN sensitivity at 1 MHz.

Hybrid platform enables compact, scalable sensors for harsh environments.

Abstract

Low-Temperature Co-Fired Ceramic (LTCC)-based mechanical sensors are inherently limited by the thickness and rigidity of multilayer ceramic stacks, which restrict miniaturization and mechanical compliance. To overcome these constraints, this work presents a hybrid LTCC/Kapton® platform enabling high-sensitivity mechanical sensing through mechanically tunable RF passive components. The proposed approach integrates a flexible polyimide membrane, bonded onto an LTCC substrate at low temperatures using selectively electroplated indium pillars that simultaneously define the air gap and provide mechanical fixation. Inductance tuning is achieved via metal-shielding proximity effects, whereas capacitance tuning relies on force-controlled air-gap modulation in a metal–insulator–metal configuration. The fabrication process ensures precise gap control, high compliance, and structural robustness without requiring deformable ceramic membranes. Experimental characterization, including three-dimensional surface profiling and impedance measurements, demonstrates a 48% inductance tuning range with a sensitivity of 0.715 nH/mN and a 36% capacitance tuning range with a sensitivity of 47.3 fF/mN at 1 MHz. The proposed hybrid platform provides a compact and scalable solution for high-sensitivity sensors and mechanically reconfigurable RF components suitable for harsh-environment and adaptive electronics applications.

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