Stainless steel / alumina ceramic low stress hermetic seal solder

Abstract

The invention relates to a silver alloy composite solder strip for a vacuum switch tube stainless steel and 95 percent alumina ceramic low-stress hermetic seal joint. The cross section of the composite solder strip has a three-layer overlapping structure of a solder alloy layer, a copper core layer and a solder alloy layer, wherein solder in the composite solder comprises the following compositions in percentage by mass: 55 to 72 percent of silver, 19.0 to 43.0 percent of copper and 0.50 to 4.50 percent of nickel; the melting temperature of the solder is between 780 and 835 DEG C, and the hermetic seal temperature is between 820 and 850 DEG C; the unilateral thickness of the solder alloy layer in the composite solder is between 0.08 and 0.20 millimeter; the copper core layer in the composite solder is copper with the purity of more than or equal to 99.95 percent or oxygen free copper; the interlayer composite proportion of the composite solder, namely the thickness of the solder layer to the thickness of the copper core layer to the thickness of the solder layer, is 1:X:1 (wherein, X is between 1.8 and 3.5); and firm metallurgical combination is formed between various layers. The intensity of the vacuum switch tube stainless steel and 95 percent alumina ceramic joint is more than or equal to 90 MPa, and the leakage rate of the joint is less than or equal to 1*10Pa.m / s.

Description

technical field [0001] The invention relates to the field of electric vacuum device manufacturing in the electronic industry, in particular to silver alloy composite brazing filler metal used for vacuum switch tube stainless steel and 95% alumina ceramic low-stress hermetic joint. Background technique [0002] In recent years, in the field of electric vacuum device manufacturing, in order to reduce the cost of products in mass-produced vacuum switch tubes, stainless steel is used to replace the high-cost low-expansion coefficient Kovar alloy, that is, stainless steel end caps and 95% aluminum oxide are used. Ceramic tube sealing structure, the new problem of this sealing structure is: the expansion coefficient of stainless steel and ceramics is very different (at 20 ~ 500 ℃, the linear expansion coefficient of 95% alumina ceramics is (6.5 ~ 7.5) × 10 -6 / °C, the linear expansion coefficient of stainless steel is 17.9×10 -6 / °C), they cannot form a matching seal, and the str...

AI Technical Summary

Problems solved by technology

[0003] The existing sealing process needs to add two solder rings and an oxygen-free copper ring (that is, C in Table 1) between stainless steel / 95% alumina ceramics. This process has many operating procedures and low assembly efficiency , high production costs, etc.

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