Chromium-free, lead-free and low-voltage piezoresistor

Abstract

The invention discloses a chromium-free, lead-free and low-voltage piezoresistor which is prepared from the following raw materials in molar percent through conventional solid phase method: ZnO:Bi2O3:Co2O3:MnCO3:SiO2:Ni2O3:Bi4Ti3O12:SnO2=(98.17-X):0.4:(0.6-Y):(0.5+Y):0.05:0.1:(0.1+X):0.08, wherein X is more than or equal to 0 and less than or equal to 2 and Y is more than or equal to 0 and less than or equal to 0.1; the additive amount of B2O3 accounts for 0.02% of total weight of all raw materials. According to the chromium-free, lead-free and low-voltage piezoresistor, Bi3Ti3O112 is used to replace TiO2 to dope, the inhibiting effect on generation of Zn2TiO4 by reaction of TiO2 and ZnO at high temperature relative to grain growth can be effectively reduced, so that the low voltage piezoresistor with lower electric potential gradient is obtained. Meanwhile, better pressure-sensitive and higher flow capacity and energy absorption capability are maintained. The high performance chromium and lead free low voltage piezoresistor developed is free of any chromium and lead elements and is environment-friendly.

Description

technical field [0001] The invention relates to a chrome-free lead-free low-voltage varistor, which belongs to the technical field of electronic component manufacturing. Background technique [0002] With the miniaturization and integration of electronic products, the demand for low-voltage varistors is increasing, with an average annual growth rate of about 25%, and its application fields are also expanding. For example, the prosperity of the automotive electronic system industry has promoted the development of the automotive special circuit protection component market. Since 2003, the market for automotive low-voltage varistors has been optimistic all the way, and the proportion of its demand in the total market demand for varistors has been rising Steadily rising, from 15% in 1998 to about 32%. But at present, in the manufacture of low-voltage varistors, Littelfuse and GE in the United States, TDK and Panasonic in Japan are in a leading position. The production and prep...

AI Technical Summary

Problems solved by technology

Due to the time-consuming preparation and screening of seed crystals, the process is complicated, and the uniformity of materials is poor, it is difficult to realize industrial production in the seed crystal method.

Adding a grain growth agent is the simplest and most effective method for low pressure at present. The commonly used grain growth agent is TiO 2 , it can effectively promote the grain growth and reduce the potential gradient, but at high temperature TiO 2 Easily react with ZnO to generate Zn 2 TiO 4 Phase, distributed at the junction of ZnO grains, does not move with the ZnO interface, inhibits the growth of grains, and is not conducive to the low voltage of the varistor

[0004] In addition, with the development of society, the environmental protection requirements for electronic products at home and abroad are getting higher and higher. A mandatory standard formulated by the EU legislation is the "Directive on Restricting the Use of Certain Hazardous Components in Electrical and Electronic Equipment", the standard The purpose is to eliminate 6 substances including lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers in electrical and electronic products. At present, most of the low-voltage products contain lead and chromium elements. For example, the patent number is 200810058400.2, and the name is The invention patent application for the manufacturing method of the layered structure low-voltage ZnO varistor, the material of which the varistor is manufactured contains harmful components such as lead and chromium, which seriously limits the export and application of the product