Document: Piezoelectric Ceramics
Introduction
Piezoelectric ceramics (such as PZT, PMN-PT, etc.) are a class of functional materials with significant electromechanical coupling properties. They can generate electrical signals under mechanical stress or undergo deformation under an electric field, leading to widespread applications in ultrasonic transducers, sensors, actuators, acoustic devices, medical imaging, and precision actuation. Their high hardness, significant brittleness, and frequent multi-layer or thin-film structures impose extremely high requirements on surface quality, flatness, and geometric consistency.
Hemei Company possesses profound experience in the precision machining of hard, brittle, and functional materials. We have developed a high-precision, low-damage polishing and thinning process specifically for piezoelectric ceramics. This process enables fully controllable handling from the flattening of green bodies to the fine finishing of functional surfaces, ensuring optimal performance of piezoelectric ceramic devices in terms of frequency response, sensitivity, and reliability.
Application Requirements
The objectives for polishing and surface treatment of piezoelectric ceramic materials include:
Reducing surface roughness (Ra) to < 10 nm (can be further optimized based on device requirements).
Achieving surface flatness (TTV) ≤ 2 μm, ensuring uniformity for multi-layer stacking or electrode coating.
Producing surfaces free of micro-cracks, edge chipping, and sub-surface domain structure damage to maintain the stability of piezoelectric properties.
Compatibility with processing circular, square, and irregularly shaped thin plates, with thickness ranges of 50-1000 μm.
To achieve these goals, Hemei's process employs low-stress bonding systems and multi-step fine polishing techniques, ensuring high-precision thickness control and excellent surface profile consistency while maintaining surface integrity.
System Specifications
Hemei's modular polishing systems support the processing of piezoelectric ceramic components of various sizes and shapes. The core systems include:
HSM-L/LP Series lapping Equipment: Used for initial material removal and thickness control.
HSM-CMP Series Chemical Mechanical Polishing Systems: Used for achieving ultra-smooth, damage-free surfaces.
Key Subsystems:
Wafer/Crystal-specific Bonding Unit (WB).
SJ/ASJ Series Precision Polishing Fixtures.
C-ASJ Drive Head High-Speed Polishing System.
Process Flow
Bonding and Mounting: The piezoelectric ceramic component is temporarily bonded to a carrier plate using the WB bonding unit and then mounted onto the polishing fixture.
Rough and Intermediate Polishing: Controlled lapping is performed on the HSM-L equipment to remove the process-affected layer.
Fine Polishing: The final polishing is conducted using the HSM-CMP system. Parameters such as pressure, rotation speed, and slurry flow rate are adjusted in real-time to achieve nano-level surface smoothness.
Typical Results
Surface Roughness Ra < 10 nm (optimizable to < 5 nm).
Total Thickness Variation (TTV) ≤ 2 μm, Local Thickness Variation (LTV) ≤ 0.5 μm.
Material Removal Rate: 0.3 - 1.5 μm/min (adjustable, balancing efficiency and surface quality).
Suitable for piezoelectric ceramic wafers with diameters ≤ 4 inches and various irregularly shaped thin plates, supporting common systems like PZT and PMN-PT.
Summary
Hemei Company provides a complete and controllable polishing and thinning solution for piezoelectric ceramic materials. This solution ensures high surface quality and geometric precision while maximally preserving their piezoelectric properties and reliability. It thereby supports the performance enhancement and scalable application of piezoelectric ceramics in high-end fields such as ultrasonic medicine, sensors, and precision actuation.
