Electronic ceramics: widening application fields
The emergence and development of piezoelectric ceramics has had a significant impact on technological progress, the formation of new industries, and the economic and social development of our country. Global annual sales volume of piezoelectric ceramic products is increasing at a rate of about 15 %%.
In the 1980s, with the development of China ’s electronics industry and the demand for civilian products, the demand for ceramic filters and ceramic resonators in household appliances has increased rapidly. Jingdezhen 999 Factory in Jiangxi and Shanghai No. 1 Radio Factory also introduced Japanese Murata piezoelectric ceramics The component production line has since begun the mass production of China's piezoelectric ceramic products from military products to civilian products. By exploring and digesting the advanced materials and processes of the Japanese introduction line, many domestic small and medium-sized piezoelectric ceramic manufacturers have developed rapidly, such as Zhejiang Jiakang Electronics (formerly Jiaxing Electric Ceramic Factory), Jiangsu Jiangjia Electronics, Wuxi Baotong Electronics, Suzhou Jiejia Electronics, etc. The main product of Jiakang Electronics at that time was piezoelectric ceramic buzzer, with a monthly output of tens of millions. Through the introduction, digestion, absorption and improvement of advanced technology lines, it quickly became the largest high-frequency product in China. Device manufacturers have reached 715 million piezoelectric ceramic devices by 2007. Jiangsu Jiangjia Electronics started to produce a small number of multi-chip ceramic filters, and has now developed into the largest manufacturer of domestic medium-frequency ceramic filters, with an annual output of 467 million by 2007.
Great progress in ceramic materials
Looking back at the development of China's piezoelectric ceramics industry, only 20 years ago, only Shandong University, Tsinghua University, South China Institute of Technology, Tianjin University, Sichuan University, Shanghai University of Science and Technology have majors in piezoelectric materials and applications, Shanghai Silicate Research The Institute, the 7th Research Institute and the 26th Research Institute of China Electronics Technology Group have built piezoelectric ceramic materials and application research laboratories. The only manufacturer is the Shandong Zibo Radio Ceramics Factory. Most of the major projects are related to military products. The products related to civilian use are only mass-produced piezoelectric ceramic buzzers and igniters, a small number of multi-chip ceramic filters, mechanical filters for post and telecommunications, and piezoelectric ceramic transducers for underwater acoustics and ultrasound.
In order to meet the different requirements of various piezoelectric devices for material properties, materials researchers have extensively studied the modification additives and developed a large number of high-performance piezoelectric ceramic materials.
Lead titanate ceramic (PT)
At the end of the 1990s, in order to meet the needs of manufacturing high-frequency ceramic filters and ceramic resonators above 10MHz, materials researchers obtained lead titanate ceramic materials by replacing them with a small amount of lanthanum oxide and adding appropriate amounts of manganese, niobium, and cerium ions to obtain The modified lead titanate ceramic material with good high frequency response and excellent temperature stability has the same electrical performance as similar materials of the same period in Murata, Japan. At the same time, lead titanate piezoelectric ceramic materials suitable for high-temperature ultrasonic transducers have also been developed, and they have been successfully used in deep oil detection and flow meters in high-temperature environments.
Lead zirconate titanate ceramic (PZT)
In the 1980s, Jiangxi Jingdezhen Factory 999 and Shanghai Radio No. 1 Factory introduced the Japanese Murata piezoelectric ceramic frequency component production line at the same time. The main raw materials were provided by Japan, which caused greater difficulties for domestic mass production and cost reduction. Foreign blockade, through research and development and improvement of PZT materials, quickly realized the localization of the material formula, and the self-developed PZT piezoelectric ceramic materials fully met the electrical performance requirements. Then a variety of PZT piezoelectric ceramic materials suitable for different bandwidths were developed.
In the past 20 years of ternary ceramics, China has done a lot of continuous research work on the modification of ternary piezoelectric ceramic materials, and tested the combination substitution and addition of various elements to expand many modified ternary, Quaternary and multivariate 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 area has been rapidly expanded.
Lead-free piezoelectric ceramics The above-mentioned piezoelectric ceramics all contain a large amount of lead, and the manufacturing process will cause environmental pollution. In order to reduce pollution, researchers at home and abroad have carried out research on lead-free piezoelectric ceramics. 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 ° C to 300 ° C higher, the dielectric constant is only 140 to 150, and the mechanical quality factor is Up to 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 applied in some specific fields, and research work is still ongoing.
Application fast penetration
After 20 years of development, today, piezoelectric ceramic products are complete, 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 5 aspects:
First, the frequency control device. In recent years, ceramic resonators and ceramic filters have developed rapidly, as well as tuning tuning fork filters, mechanical filters, ceramic frequency discriminators, notches, and delay lines. Among them, the output of ceramic resonators and ceramic filters has accounted for more than 65% of China's piezoelectric ceramic products, which is quite noticeable. In particular, ceramic resonators have the characteristics of high stability, no adjustment, small size, and low cost. Typical applications are: TVs, camcorders, computers, CD-ROM drives, automotive appliances, VCDs, telephones, copiers, speech synthesizers, remote controls, and toys.
Second, piezoelectric ultrasonic transducers. 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 communication. It is called sonar, and it is an essential and important sensor for all kinds of ships. In the industry, ultrasonic transducers have been used in ultrasonic cleaning, ultrasonic precision machining, ultrasonic humidification, ultrasonic emulsification, ultrasonic seed processing, ultrasonic flaw detection and ultrasonic diagnosis. Today, another widely used field of piezoelectric ultrasonic transducers is telemetry, remote control systems, and alarm systems.
Third, piezoelectric sounders. 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. Buzzer with transistor oscillation circuit and DC power supply can make continuous sound, buzzer with switch circuit can make intermittent sound, underwater microphones and speakers belonging to sound transducer can also be used to drive or lure School of fish.
Fourth, piezoelectric devices for measurement and control. The measurement and control piezoelectric devices mainly include pressure, acceleration, and angular velocity sensors, as well as ultrasonic sounding, ultrasonic thickness measurement, ultrasonic flow velocity measurement, and ultrasonic diagnosis.
Fifth, piezoelectric igniter and piezoelectric transformer. The mass production of piezoelectric igniters began in 1965, and has developed faster in the past 20 years. At present, almost all gas stoves, bathroom gas boilers, gas room heaters, gas water heaters and cigarette lighters use piezoelectric igniters. Piezoelectric transformers have the advantages of simple structure, small size, high transformer ratio, high electromechanical conversion efficiency, no electromagnetic interference and safety, etc., so they are used in electrostatic smoke removers, negative ion generators, electrostatic coating equipment, electrostatic copiers, and electric field treatment. Instrument and LCD backlight.
SAW forms a complete system
Surface acoustic wave devices are a popular product in the field of electronic ceramics. Surface acoustic wave (SAW) is an elastic wave that propagates along the surface of an object. The development of acoustic surface technology in China began in 1970. After 37 years of research and development, it has basically formed theoretical research, crystal material growth processing, A complete system for device design and production and system applications.
The development of surface acoustic wave technology in China can be roughly divided into three stages: In the first stage, surface acoustic wave technology is applied to the development and application of military fields. The initial impetus for the development of surface acoustic wave technology is from the national defense and military fields, and China is no exception; radar, communications, navigation, and electronic countermeasures all use various SAW signal processing devices. In the second stage, SAW technology was applied in the field of broadcasting and television. In the third stage, SAW technology was applied to modern communications.
SAW has experienced more than 30 years of development in China, and more than 30 large and small manufacturers have emerged. Although there are many manufacturers, the technical level and production scale are limited. Except for the 26th and 55th Research Institutes of CLP Technology, Tsinghua University Yingying Electronics Co., Ltd., Wuxi Haoda Electronics Co., Ltd. have certain advantages in production technology, scale and product types, and the rest are small in scale. They are mainly based on the process requirements of producing TV IF filters, resonators, and radio filters. The lower products are the main products and the prices are low.
From the perspective of product packaging, TV IF surface acoustic wave filters have evolved from metal packaging to plastic case packaging. Due to the small size and light weight of plastic case packaging, its advantages can be reflected especially in integrated high-frequency heads. Many domestic manufacturers have developed their own plastic packaging products. In terms of scale, Wuxi Haoda Electronics Co., Ltd. and CLP Deqing Huaying Electronics Co., Ltd. occupy a large market share in plastic packaging products.
At present, the smallest size of SMD products that can be mass-produced in China is 3mm × 3mm. The main production units include 55 CLP Technologies, Deqing Huaying, 26 and Wuxi Haoda Electronics Co., Ltd. At present, the mainstream products of RF filters are packaged using flip-chip welding technology below 2.5mm × 2.0mm. Therefore, the current domestic SAWRF filter production has been greatly restricted. Due to cost, technology and other factors, several domestic companies have strong capabilities. Neither the research institute nor the production enterprise has any plans to further invest in reducing product packaging. Nanyang Golden Crown Group has invested in some flip-chip welding equipment, but it does not yet have production capacity.
Basic research on surface acoustic wave products in China, especially low-loss design technology, is currently dominated by the three research institutes of the 26th Research Institute of China Electronics Technology, Nanjing University, and the Institute of Acoustics of the Chinese Academy of Sciences. Units such as Wuxi Haoda also have certain product development capabilities.
Compared with foreign countries, the surface acoustic wave industry in China has a large gap. Product research and development do not have too many scientific research institutions and colleges as technical support, lack of a basic research team, due to market competition factors, each unit is independent, lack of academic exchanges, many small companies do not have research and development capabilities. From the perspective of production technology and production scale, compared with some internationally renowned companies such as EPCOS, Murata, Fujistu, SANYO, etc., there are still large gaps, including packaging technology, degree of automation, process level, production scale, etc.
With the intensification of market competition, the current profitability of the entire sound watch industry is generally not high. The RF filters for mobile phones in the largest market have been produced at a sustained level, and investment opportunities have been lost. In order to have a certain survival status in the industry in the future, it is necessary to continuously improve product yield, reduce production costs, improve product quality, and enhance large-scale production capabilities through its own technological progress. We believe that China's surface acoustic wave industry can do the following in the 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 the current conventional applications, surface acoustic wave technology also has some special applications in sensors, radio frequency devices (RFID), and so on.
Development Trend of Electronic Ceramic Materials
With regard to high-temperature and high-performance piezoelectric ceramic materials, with the development of steel, chemical, energy, and aerospace, piezoelectric devices such as high-precision drivers, detection transducers, and sensors are required to withstand high temperatures (up to 600 ° C to 800 ° C). Working in the environment. Vibration control of aircraft engines, non-destructive testing of liquid (steam) -laden metal pipelines, high-temperature flow detection and control of steel and chemical industries, heating networks, power grids, and nuclear power industries, non-destructive testing of welded pipelines, high-precision sensor driving devices There are urgent requirements for high temperature applications of piezoelectric materials.
As for lead-free piezoelectric ceramic materials, piezoelectric ceramic materials characterized by electromechanical energy conversion are currently using lead-based piezoelectric ceramics on a large scale, and PbO accounts for about 60% to 70% of the raw materials. These lead-containing piezoelectric ceramic materials will cause serious harm to humans and the ecological environment during production, use and disposal. In order to protect the living space of the earth and human beings and prevent environmental pollution, research and development of practical lead-free piezoelectric ceramic materials is a topic of great social and economic significance.
Electronic ceramic application development trend
Piezoelectric ceramic frequency components with thinner and smaller size; piezoelectric ceramic resonators with higher frequency; piezoelectric ceramic frequency components with higher frequency accuracy, better frequency stability and higher reliability; It has excellent heat resistance and can be used for chip-type ceramic frequency components required for lead-free reflow; the application of chip-type piezoelectric ceramic frequency components that contain no or less toxic and harmful elements will attract attention.
In addition, ultrasonic waves generated by piezoelectric ceramic transducers are used to treat wastewater and toxic water. Ultrasonic motors with small radial dimensions, large output torque, and strong controllability; ultrasonic sensors such as anti-theft, height measurement, automobile collision avoidance, remote switch and robot distance measurement; servo displacement brakes, optical strain mirrors, strain gratings, Special attention should be paid to ultra-precision guidance mechanisms, cutting error compensation brakes, and hydraulic servo valves.
Editor-in-chief: Electronic Information Industry Network