Solid aluminum capacitor development history

　　Capacitor cathode materials (i.e. electrolyte) performance,largely determines the properties of capacitors. The solid electrolyte is much higher than the conductivity of liquid electrolytes (depending on different materials, electrical conductivity can reach 0.1 ~ 100S/cm), and has temperature characteristics and excellent chemical stability,it is because of the excellent properties of the solid electrolyte, and excellent performance of solid aluminumcapacitors in liquid aluminum capacitor. Between differentsolid electrolyte performance varies widely, frommanganese dioxide originally used to present the use of PEDOT, the electrical conductivity is hundreds of times,therefore, the performance of solid aluminum capacitor in different stages of development are different. The solid aluminum capacitor development process are introduced.
　　1 manganese dioxide solid aluminum capacitor
　　Manganese dioxide as the solid electrolyte in application oftantalum capacitors has been successful, originallysomeone try using manganese dioxide as the electrolytesolid aluminum capacitors, but Al2O3 dielectric oxide filmunder high temperature corrosion, resulting in leakage current of the capacitor is increased, because of this, by using manganese dioxide as the technical difficulty of aluminum capacitor electrolyte greatly, the low rate of finished products.
　　2 TCNQ type solid aluminum capacitor
　　TCNQ‘s researchers American DuPont in 1959 firstsuccessfully synthesized; in 1961, American ROSS first TCNQ composite salt used in the preparation of capacitors;in 1983, the Japanese Sanyo motor company developed organic semiconductor TCNQ type solid aluminumcapacitors, this is the first generation of solid aluminumcapacitors on real significance, known as the OS-Con type aluminum electrolytic capacitor. The conductivity of TCNQ is about 1S/cm, much higher than the liquid electrolyte0.01S/cm, therefore, TCNQ type solid aluminum capacitorscompared with liquid aluminum capacitor much lower ESR,with high frequency characteristics, is good at the same time, the service life and environmental stability is also greatly improved. There is no doubt, OS-Con capacitors than the traditional liquid aluminum container is a great progress.
　　A series of research results, the TCNQ composite salt directly heating melt, then dipping and cooling curing is a good method for preparing TCNQ type solid aluminumcapacitor. But due to the thermal processing properties of TCNQ composite salt is not too good, can only maintain themolten stable state in a very narrow temperature range, and the stable time is very short, therefore, the manufacturing process of TCNQ type solid aluminum capacitor (especially the impregnation process) requirements are very strict. In addition, TCNQ solder heat resistance stability is not good enough, which restricts the further development of TCNQ type solid aluminum capacitors in a certain extent.
　　3 polypyrrole solid aluminum capacitor
　　Since the success of conductive polypyrrole research,people of polypyrrole solid aluminum capacitors made great effort. In 1973 Japan‘s Showa electrician for basic patentpolypyrrole solid aluminum capacitor, the capacitor is called functional polymer solid aluminum electrolytic capacitors(SP-Cap), is the second generation of solid aluminumcapacitor. SP-Cap is lower than the OS-Con ESR, the frequency characteristic is better, in a wide temperature range can be kept very low ESR, in addition, polypyrroletemperature and chemical stability than TCNQ, therefore,SP-Cap compared with OS-Con is a big progress.
　　Because of polypyrrole solid aluminum capacitors generally by the electrochemical polymerization method, need to beon the surface of alumina membrane to form a layer of thin conductive layer, but this method can only manufacturelaminated aluminum capacitor, not suitable for the production of winding aluminum capacitor.
　　4 polyaniline solid aluminum capacitor
　　Research of conductive polyaniline provides a kind of newelectrolyte for solid aluminum capacitors, polyaniline hasexcellent environmental stability, low price of raw materials,easy to dissolve and melt, in has certain advantages andpreparation of solid aluminum capacitors, but because the aniline environmental pollution is a problem, which limits its application.
　　5 PEDOT type solid aluminum capacitor
　　In 1988, Germany Bayer (Bayer) company is the first to develop a new generation of conductive polymer materialsPEDOT (Eur. Patent 339340 (1988)), and also apply for apatent based application of PEDOT type solid aluminumcapacitor.
　　Compared with other solid electrolyte, PEDOT has the outstanding performance:
　　U conductivity is high, can reach 100S/cm;
　　U produced less than the substrate surface effects of 1mmwithin the thin layer, so the available low cost to obtain very good results;
　　Hydrolysis resistance, light stability and thermal stability of uis very good, will not cause environmental pollution;
　　U has the advantages of simple process, easy to use;
　　U high pH value conductivity will not fall;
　　U good electrochemical performance.
　　Successful application of PEDOT in aluminum capacitors inmarks the birth of the third generation of solid aluminumcapacitors, the industry generally believe that the PEDOT type aluminum solid capacitor has the most developmentprospect and application value. At present, PEDOT typesolid aluminum capacitors have been well-known international electron manufacturer approval, is considered to be the solid aluminum capacitor is currently the most advanced, and mass application.