Ultrasonic Piezoelectric Discs: Precision Engineered for Sensing and Power Applications

In the fields of ultrasonic technology, precision sensing, and industrial actuation, piezoelectric ceramic discs are the core components enabling energy conversion. Whether converting electrical energy into ultrasonic vibrations or transforming weak pressure changes into electrical signals, selecting the right piezo ceramic disc directly determines the performance and reliability of the entire system. This article will provide an in-depth analysis of the working principles and key selection parameters of piezoelectric ceramic discs, helping you make accurate technical decisions across different application scenarios.

Working Principle and Core Performance Parameter Analysis

Core Piezoelectric Effect Principle

Piezoelectric ceramic discs are primarily made of lead zirconate titanate (PZT)-based ceramics, leveraging the bidirectional piezoelectric effect to achieve electromechanical energy conversion. They are core components in the fields of ultrasonics, sensing, and power actuation.

Direct Piezoelectric Effect (Sensing Mode): When the disc is deformed by mechanical vibration or pressure, the ceramic lattice charge shifts, inducing an output voltage or charge across the upper and lower electrodes. This effect is widely used in vibration acquisition, acoustic detection, pressure sensing, and other scenarios.

Converse Piezoelectric Effect (Drive Mode): When an alternating voltage is applied to the electrodes, the ceramic body periodically expands, contracts, and bends in response to the electric field changes, thereby generating high-frequency mechanical vibrations or ultrasonic waves. This effect is the core driving force behind applications such as ultrasonic cleaning, ultrasonic welding, atomizers, buzzers, and medical ultrasound probes.

Product Structure: Piezoelectric ceramic discs typically consist of a ceramic substrate with double-sided electrodes. Electrode materials include silver, nickel, gold, and others. Some buzzer models incorporate a brass metal substrate laminated onto the ceramic disc, forming a double-layer vibration structure to enhance sound pressure output.

Key Performance Parameter Analysis

To make accurate selections, understanding the following core parameters is essential:

Piezoelectric Constant (d33)

Measures the sensitivity of the material in converting electrical energy into mechanical energy (or vice versa). The higher the value, the greater the displacement or voltage output. Common PZT materials have d33 values ranging from 200 to 650 pC/N, with PZT-4 series around 300 pC/N and PZT-5H series up to approximately 600 pC/N. High-sensitivity sensors typically use materials with d33 above 500 pC/N, while high-power drive applications use materials in the 200~400 pC/N range.

Electromechanical Coupling Coefficient (Kp)

Reflects the efficiency of electrical-to-mechanical energy conversion, typically ranging from 0.50 to 0.70. The higher the Kp, the more complete the energy conversion. Ultrasonic transducers generally prefer models with Kp greater than 0.60 to improve overall electroacoustic conversion efficiency.

Mechanical Quality Factor (Qm)

Describes the degree of energy loss during vibration. High Qm materials (e.g., PZT-4, with Qm reaching above 1000) have sharp resonant peaks, making them suitable for high-power narrow-band applications such as ultrasonic cleaning. Low Qm materials (e.g., PZT-5, with Qm around 70) offer wider bandwidth, making them suitable for sensors and buzzers.

Resonant Frequency and Dimensions

Resonant frequency is determined by disc thickness and diameter – the thinner the disc, the higher the frequency. The typical frequency range extends from a few kHz to several MHz, with common specifications including 20kHz, 40kHz, 200kHz, etc. Outer diameters commonly range from a few millimeters to several tens of millimeters, and thickness can be as thin as 0.2mm.

Material and Specification Selection Methods for Piezo Ceramic Discs in Different Scenarios

When selecting a piezo ceramic disc, trade-offs often need to be made among sensitivity, power, stability, and temperature range. The following is a general selection guide based on different application scenarios:

High-Sensitivity Sensing & Reception (Sensing)

Suitable for applications such as NDT, medical ultrasound probes, and underwater sonar, which require extremely high sensitivity and signal-to-noise ratio. PZT-5A or PZT-5H series soft piezoelectric materials are recommended for their high piezoelectric constants, enabling high voltage output from minimal deformation. In terms of specifications, a thin disc structure with thickness of 0.3~1.2mm, outer diameter of 6~30mm, and double-sided silver electrodes is suggested.

High-Power Ultrasonic Emission (Power / Ultrasonic)

Suitable for applications such as ultrasonic cleaners, welders, and atomizers, which require generating high-intensity ultrasonic waves with low loss and high stability. PZT-4 or PZT-8 series hard piezoelectric materials are recommended for their high Curie temperature, resistance to depolarization, and stable operation under high voltage. In terms of specifications, a thick-walled disc structure with thickness of 3~15mm, outer diameter of 20~50mm is suggested, and multiple discs can be stacked to increase power.

Audio & Buzzer (Buzzer / Audio)

Suitable for applications such as alarms, home appliance buzzers, and automotive warnings, which require producing clear sound over a wide frequency range. Modified PZT soft piezoelectric materials combined with a brass substrate are recommended for their large deformation, high acoustic efficiency, low cost, and low power consumption. Common specifications include outer diameters of φ12/15/20mm, ceramic layer thickness of 0.25~0.4mm, laminated with a 0.1mm brass substrate.

Applications of Piezoelectric Ceramic Discs in Ultrasonic, Sensing, and Buzzer Fields

Leveraging their bidirectional piezoelectric effect, piezoelectric ceramic discs have formed mature applications in three major areas: industrial ultrasonics, precision sensing, and consumer electronics.

Industrial Ultrasonic Equipment

In the field of industrial ultrasonic equipment, piezoelectric ceramic discs are primarily used as the core vibrator of transducers. For ultrasonic cleaning equipment, PZT-8 series piezoelectric discs operate across a frequency range of 5kHz to 40kHz and are widely used in hardware degreasing, jewelry cleaning, and PCB board cleaning. For ultrasonic welding and punching equipment, high-power thick piezoelectric discs with mainstream specifications of 20kHz and 15kHz serve as core driving components for plastic welding, non-woven fabric punching, and metal spot welding. In the field of underwater acoustics and sonar, large-sized piezoelectric discs are used for underwater acoustic wave transmission and reception, supporting equipment for oil and gas well logging, ocean current measurement, and underwater detection.

Precision Sensing and Flow Measurement

Leveraging the direct piezoelectric effect, piezoelectric ceramic discs are widely used in precision sensing applications such as ultrasonic water meters, heat meters, industrial flowmeters, and metal non-destructive testing sensors. Their core function is to capture weak acoustic signals such as fluid vibration and structural cracks, and convert them into electrical signals. Piezoelectric ceramic discs feature strong stability across a wide temperature range, with controllable measurement errors under high and low temperature conditions, meeting national metrology standards. They are key sensing components in smart meters and industrial testing equipment.

Buzzers and Consumer Electronics

Piezoelectric buzzer discs with a composite metal substrate are widely used in smoke alarms, car reverse buzzers, microwave oven and washing machine notification sounds, electronic doorbells, and other consumer electronic devices. Compared to traditional electromagnetic buzzers, piezoelectric buzzers offer significant advantages: approximately 90% lower power consumption, no electromagnetic interference, a service life of over 100,000 hours, and a miniaturized design suitable for PCB surface-mount assembly. They are the mainstream acoustic solution in home appliances and automotive electronics.

Summary

Piezoelectric ceramic discs are key components for electromechanical energy conversion, playing an irreplaceable role in industrial ultrasonics, precision sensing, and consumer electronics. Correct selection depends on understanding core parameters such as piezoelectric constant, electromechanical coupling coefficient, mechanical quality factor, and resonant frequency. High-sensitivity sensing suits PZT-5A/5H soft materials, high-power ultrasonic emission suits PZT-4/8 hard materials, and buzzers typically use modified PZT with metal substrates. Matching materials to specific applications ensures system reliability and efficiency.

Weifang Jude offers customized solutions for piezoelectric ceramic discs in three areas: dimensions, electrodes, and frequency. Dimensions can be tailored to various outer diameters and thicknesses. Electrodes support multiple materials and pattern designs. Frequency can be precisely tuned to meet different application requirements.