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

Area of Science:

• Materials Science
• Electrical Engineering
• Mechanical Engineering

Background:

• Traditional Low-Temperature Co-Fired Ceramic (LTCC) sensors face limitations in miniaturization and flexibility due to rigid multilayer structures.
• Existing LTCC sensor designs struggle to achieve high mechanical compliance and sensitivity simultaneously.

Purpose of the Study:

• To develop a novel hybrid LTCC/Kapton platform for high-sensitivity mechanical sensing.
• To enable mechanically tunable RF passive components by overcoming the limitations of conventional LTCC sensors.
• To demonstrate a fabrication process for a compliant and robust hybrid sensor platform.

Main Methods:

• Integration of a flexible polyimide membrane onto an LTCC substrate using electroplated indium pillars.
• Creation of tunable inductance via metal-shielding proximity effects.
• Creation of tunable capacitance through force-controlled air-gap modulation in a metal-insulator-metal configuration.
• Utilizing 3D surface profiling and impedance measurements for characterization.

Main Results:

• Achieved a 48% inductance tuning range with a sensitivity of 0.715 nH/mN.
• Demonstrated a 36% capacitance tuning range with a sensitivity of 47.3 fF/mN at 1 MHz.
• Fabrication process ensures precise gap control, high compliance, and structural robustness.

Conclusions:

• The hybrid LTCC/Kapton platform offers a compact, scalable solution for high-sensitivity mechanical sensors.
• The developed platform is suitable for mechanically reconfigurable RF components in harsh environments and adaptive electronics.
• This approach overcomes the rigidity and thickness constraints of traditional LTCC sensors.