Zinc oxide pressure sensitive resistor

Abstract

The invention discloses a zinc oxide pressure sensitive resistor which comprises a zinc oxide ceramic substrate, an electrode layer and an electrode lead, wherein the electrode layer is arranged on the surface of the zinc oxide ceramic substrate; the electrode lead is arranged on the electrode layer; the electrode layer comprises a transition layer which is connected with the zinc oxide ceramic substrate and a welded layer positioned on the outer side of the transition layer; the transition layer is made of nickel, chromium, titanium, aluminum, copper or the alloy of the elements; the welded layer is made of gold, silver, copper or the alloy of the elements.

Description

technical field [0001] The invention relates to the preparation technology of zinc oxide piezoresistors. Background technique [0002] Zinc oxide varistors are based on zinc oxide powder, doped with metal oxides in different proportions and sintered at high temperature into an embryo body, covered with an electrode layer on the surface of the embryo body, and then welded electrode leads. It includes zinc oxide There are three parts: the base ceramic body, the electrode layer arranged on the surface of the ceramic, and the electrode lead welded on the surface of the electrode layer. The electrode layer is used to make ohmic contact with the ceramic, and the lead is used to lead out the electrode for connection with the circuit. [0003] As a varistor, the contact point between the electrode layer and the electrode lead wire needs to withstand the surge current of thousands or even tens of thousands of amperes in an instant, which puts forward strict requirements on the elec...

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Problems solved by technology

[0004] 1) Since silver and zinc oxide ceramics are mismatched in terms of mechanical properties and electrical properties, it will cause two problems. First, the bonding force between the electrode layer and zinc oxide ceramics is very poor, generally lower than 15N. The middle electrode layer is easy to fall off, the reliability of the device is poor, and the life is short; second, the ohmic contact resistance is large, generally greater than several ohms, and when the surge current passes through such a large ohmic contact resistance, the heat generated is correspondingly large. It is easy to burn the electrode layer;

[0005] 2) Since the electrode lead wire is a straight guide wire, the current is mainly concentrated at the line contact between the guide wire and the electrode film layer, the current density distribution is extremely uneven, and the strong surge current can easily burn through the electrode layer locally, resulting in resistance device is permanently damaged;

[0006] 3) In order to prevent the electrode layer from being burned, the thickness of the silver electrode layer has to reach tens of microns or even hundreds of microns, which requires a large amount of expensive silver consumption and high production costs

[0007] 4) The silver paste for silk screen printing on the electrode layer needs high-temperature sintering in a tunnel kiln, which consumes a lot of energy and causes pollution in the process; there are also prohibited substances such as lead in the silver paste, and the product does not meet the RoSH standard

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