In the 1980s, with the development of my country's electronics industry and the needs of civilian products, the demand for ceramic filters and ceramic resonators in household appliances increased rapidly. Jiangxi Jingdezhen 999 Factory and Shanghai No. 1 Radio Factory At the same time, the Japanese Murata piezoelectric ceramic frequency component production line was introduced, which kicked off the mass production of my country's piezoelectric ceramic products from military products to civilian products. By exploring and digesting advanced materials and processes imported from Japan, many domestic small and medium-sized piezoelectric ceramic manufacturers have developed rapidly, such as Zhejiang Jiakang Electronics (formerly Jiaxing Electric Ceramics Factory), Jiangsu Jiangjia Electronics, Wuxi Baotong Electronics, Suzhou Jiejia Electronics, etc. The flagship product of Jiakang Electronics at that time was piezoelectric ceramic buzzers, with a monthly output of tens of millions. Through the introduction, digestion, absorption and improvement of advanced process lines, it soon became the largest high-frequency product with the most complete varieties in China. Device manufacturer, by 2007 the number of piezoelectric ceramic devices had reached 715 million. Jiangsu Jiangjia Electronics began to produce small quantities of multi-chip ceramic filters and has now developed into the largest manufacturer of mid-frequency ceramic filters in China. By 2007, its annual output had reached 467 million pieces.
Ceramic materials have made great progress
Looking back at the development of my country's piezoelectric ceramics industry, 20 years ago there were only a few universities such as Shandong University, Tsinghua University, South China Institute of Technology, Tianjin University, Sichuan University, and Shanghai University of Science and Technology.The school has a major in piezoelectric materials and applications. The Shanghai Ceramic Research Institute, the 7th Research Institute and the 26th Research Institute of China Electronics Technology Group have piezoelectric ceramic materials and application research laboratories. The only manufacturer is Zibo Radio Ceramics, Shandong. Factory, most of its main projects are related to military products. The only products related to civilian use are mass-produced piezoelectric ceramic buzzers and igniters, a small amount of multi-chip ceramic filters used in postal and telecommunications communications, mechanical filters, and piezoelectric ceramic transducers used for underwater acoustics and ultrasound.
In order to adapt to the different requirements for material properties of various piezoelectric devices, materials researchers have conducted extensive research on modified additives and developed a large number of high-performance piezoelectric ceramic materials.
Lead titanate ceramic (PT)
In the late 1990s, in order to meet the needs of manufacturing high-frequency ceramic filters and ceramic resonators above 10MHz, materials researchers replaced the lead titanate ceramic material with a small amount of lanthanum oxide, and added an appropriate amount Manganese, niobium, and cerium ions were used to obtain a modified lead titanate ceramic material with good high-frequency response and excellent temperature stability. Its electrical properties are equivalent to similar materials from Japan's Murata at the same time. At the same time, lead titanate piezoelectric ceramic materials suitable for high-temperature ultrasonic transducers have been developed and successfully used in deep oil well detection and flow meters in high-temperature environments.
Lead zirconate titanate ceramic (PZT)
In the 1980s, Jiangxi Jingdezhen 999 Factory and Shanghai Radio Factory 1 simultaneously introduced the Japanese Murata piezoelectric ceramic frequency component production line. The main raw materials were provided by Japan, which caused problems in domestic mass production and cost reduction. Overcoming great difficulties, in order to break the foreign blockade, through research and development and improvement of PZT materials, the localization of the material formula was quickly achieved. The electrical performance indicators of the independently developed PZT piezoelectric ceramic materials fully met the requirements. Then a variety of PZT piezoelectric ceramic materials suitable for different bandwidths were developed.
Ternary Ceramics
In the past 20 years, my country has done a lot of continuous research work on the modification of ternary piezoelectric ceramic materials. It has tested the combination substitution and addition of various elements and developed many modifications. ternary system,Quaternary and multi-element materials, such as: PCM-PZT, PMS-PZT, PNZ-PNS-PZT, PMS-PNZ-PNS-PZT, etc. These materials have different properties and can meet various needs, making piezoelectric ceramics The application scope has been rapidly expanded.
Lead-free piezoelectric ceramics
The above-mentioned piezoelectric ceramics contain a large amount of lead, and the manufacturing process will cause environmental pollution. In order to reduce pollution, domestic and foreign researchers have carried out research on lead-free piezoelectric ceramics, which are different from lead-containing piezoelectric ceramics. Compared with ceramic materials, the performance of lead-free piezoelectric ceramics is obviously different from that of lead-containing piezoelectric ceramics. For example, the Curie point of lead-free piezoelectric ceramics is about 200℃~300℃ higher, and the dielectric constant is only 140~150. The mechanical quality factor is as high as 4000~7000. However, the electromechanical coupling coefficient and other properties of lead-free piezoelectric ceramics are far inferior to those of lead-containing ceramics, and the manufacturing process is difficult to control. Therefore, lead-free piezoelectric ceramics are only used in some specific fields, and their research work is still In progress.
Rapid application penetration
After 20 years of development, today, piezoelectric ceramic products have a complete range, which are not only widely used in military and industrial fields, but also penetrated into every corner of people's daily life. Its application fields mainly involve the following five aspects:
First, frequency control device. In recent years, ceramic resonators, ceramic filters, as well as tuned tuning fork filters, mechanical filters, ceramic frequency discriminators, notches and delay lines have developed rapidly in recent years. Among them, the output of ceramic resonators and ceramic filters has accounted for more than 65% of my country's piezoelectric ceramic products, which is quite eye-catching. In particular, ceramic resonators have the characteristics of high stability, no adjustment required, small size and low cost. Typical applications include: televisions, camcorders, computers, CD-ROM drives, automotive appliances, VCDs, telephones, copiers, speech synthesizers, remote controls and toys, etc.
Second, piezoelectric ultrasonic transducer. Piezoelectric ultrasonic transducers are acoustic devices that emit and receive ultrasonic waves and are widely used in water and air media. It plays the role of radar in underwater acoustic communications and is called sonar. It is an indispensable and important sensor for all types of ships. In industry, ultrasonic transducers have been used for ultrasonic cleaning, ultrasonic precision machining, ultrasonic humidification, phacoemulsification, ultrasonic seed treatment, ultrasonic flaw detection and ultrasonic diagnosis, etc. Another broad area of application for piezoelectric ultrasonic transducers today is telemetry, remote control systems and alarm systems.
Third, piezoelectric sound generator. Typical products of piezoelectric sounders are piezoelectric buzzers and piezoelectric transmitters, receivers, watches, calculators, electronic alarm clocks, small alarm bells, and the ringing of telephones and mobile phones are all inseparable from buzzers. Buzzers with transistor oscillation circuits and DC power supplies can emit continuous sounds, buzzers with switching circuits can emit intermittent sounds, and underwater microphones and speakers that are acoustic transducers can also be used to drive away or lure School of fish.
Fourth, piezoelectric devices for measurement and control. Piezoelectric devices for measurement and control mainly include pressure, acceleration, angular velocity sensors, ultrasonic depth measurement, ultrasonic thickness measurement, ultrasonic flow velocity measurement, ultrasonic diagnosis, etc.
Fifth, piezoelectric igniters and piezoelectric transformers. Mass production of piezoelectric igniters began in 1965 and has developed faster in the past 20 years. Currently, almost all gas stoves, bathroom gas boilers, gas room heaters, gas water heaters and cigarette lighters in my country use piezoelectric igniters. Piezoelectric transformers have the advantages of simple structure, small size, high transformation ratio, high electromechanical conversion efficiency, no electromagnetic interference and safety, so they are used in electrostatic smoke removers, negative ion generators, electrostatic coating equipment, electrostatic copying machines, and electric field therapy. Instruments and LCD backlights, etc.
Surface acoustic waves form a complete system
Surface acoustic wave devices are a popular product in the field of electronic ceramics. Surface acoustic wave (SAW) is a kind of elastic wave that propagates along the surface of an object. The development of surface acoustic technology in my country began in 1970. After 37 years of research and development, it has basically formed a complete system from theoretical research, crystal material growth and processing, A complete system of device design and production as well as system application.
The development of surface acoustic wave technology in my country can be roughly divided into three stages: In the first stage, surface acoustic wave technology is used in the development and application of military fields. The initial impetus for the development of surface acoustic wave technology comes from the national defense and military fields in various countries, and our country is no exception; radar, communications, navigation and electronic countermeasures all use a variety of SAW signal processing devices. In the second stage, surface acoustic wave technology is applied to the field of radio and television. In the third stage, surface acoustic wave technology is applied to modern communications.
Surface acoustic wave has experienced more than 30 years of development in my country, and more than 30 large and small manufacturing companies have emerged. Although there are many manufacturers, their technical level and production scale are limited. Except for the third company of China Electronics Technology 26. 55 Research Institute, Deqing Huaying Electronics Co., Ltd., Wuxi Haoda Electronics Co., Ltd., etc. have certain advantages in production technology, scale and product types. The others are small in scale and mainly produce TV intermediate frequency filters and resonators. As well as products with relatively low process requirements such as walkie-talkie filters, the prices are low.
From the perspective of product packaging, TV mid-frequency surface acoustic wave filters are developing from metal packaging to plastic shell packaging. Since plastic shell packaging has the characteristics of small size and light weight, especially in integrated Its advantages can be reflected in the high-frequency head. Many domestic manufacturers have developed their own plastic packaging products. In terms of scale, Wuxi Haoda Electronics Co., Ltd. and Zhongdian Technology Deqing Huaying Electronics Co., Ltd. occupy a larger share in plastic packaging products. market share.
The minimum size of SMD products that can be mass-produced in China is 3mm × 3mm. The main production units include the 55th Institute of China Electronics Technology, Deqing Huaying, 26th Institute and Wuxi Haoda Electronics Co., Ltd. The current mainstream product packaging of RF filters uses flip-chip soldering technology below 2.5mm×2.0mm. Therefore, domestic SAWRF filter production is currently greatly restricted. Due to cost, technology and other factors, several domestic powerful Neither the research institute nor the manufacturing company has any plans to further invest in shrinking product packaging. Nanyang Golden Crown Group has invested in some flip-chip soldering equipment, but it does not yet have production capacity.
The basic research on surface acoustic wave products in my country, especially low-loss design technology, is currently mainly conducted by three scientific research institutions: the 26th Research Institute of China Electronics Technology, Nanjing University and the Institute of Acoustics of the Chinese Academy of Sciences. In addition, China Electronics Technology Co., Ltd. Units such as Tsing Huaying, 55 Institute of Science and Technology, and Wuxi Haoda also have certain product development capabilities.
Compared with that of foreign countries, there is a big gap between my country's surface acoustic wave industry and foreign countries. There are not many scientific research institutions and colleges and universities as technical support for product research and development, and there is a lack of a basic research team. Due to market competition, each unit operates independently and lacks academic exchanges. Many small businesses do not have R&D capabilities. In terms of production technology and production scale, there is still a big gap compared with some well-known international companies such as EPCOS, Murata, Fujistu, SANYO, etc., including packaging technology, automation level, process level, production scale, etc.
With the intensification of market competition, the current profitability of the entire SAW industry is generally not high. The largest market, mobile phone RF filters, has been produced at a maintenance level, losing investment opportunities. If you want to have a certain survival position in the industry in the future, you must continuously improve product yields, reduce production costs, improve product quality, and enhance large-scale production capabilities through your own technological progress. We believe that my country's surface acoustic wave industry can do the following aspects for future development: First, strengthen mutual cooperation and resource integration within the industry. Second, expand international technical cooperation. Third, actively explore new application areas. In addition to its current conventional applications, surface acoustic wave technology also hasSome special uses in sensors, radio frequency identification (RFID), etc.
