高压真空开关管黄斑现象的剖析  

Analysis of the yellow spot phenomenon of high-voltage vacuum switching tube

作　　者：杨卫英[1] 伍智[1] 胡守亮[1] 邹桂娟[1] 

机构地区：[1]中国工程物理研究院,四川绵阳621900

出　　处：《真空》2014年第3期61-64,共4页Vacuum

摘　　要：在使用高压真空开关管时,发现器件表面出现黄斑现象,不能满足焊接要求。经分析发现:对其金属零件进行双层电镀——镀镍和镀银,如果银层在0.7μm以下,在后序的焊接热处理过程中银层被熔化,原来均匀、致密的镀银层被重新分布后,银层变得不均匀,露出的镍占银的50%,在烘烤排气时露出表面的镍被氧化,呈现黄色现象,并进一步扩散到银层下面的镍区域,使银层与镍层结合不牢;银层在2μm以上时,热处理后,出现银堆积现象,不能满足要求;银层厚度在1μm^2μm范围时,钎焊热处理后,即使露出8%左右的镍,镍不会氧化。When using high-voltage vacuum switching tube, the yellow spot phenomenon appears on the tube surface, and the tube does not meet the welding requirement. We find that the reason is as the follows. The metal parts are electroplated with an adhesion coating of nickel in preparation before further plating the silver. If the silver coating thicknes is less than 0.7 txm, the coated silver is re-distributed during the brazing heat treatment. The silver coating thus becomes non-uniform. There is about 50% of the nickel coating exposed out of the silver coating. The exposed nickel coating is oxidized, and the oxidation results in the yellowness. The oxide diffuses to the area under the silver coating, which will make the silver coating combine poor with the nickel coating because of the oxidation. If the silver coating thicknes is more than 2 μm, the silver coating will be piled during the heat treatment, such object doesn＇t fit requirement. When the silver coating thicknes is 1 μm-2μm, although a small quantity of nickel coating （about 8% ） is exposed, the nickel coating isn＇t oxided.

关 键 词：高压真空开关管 黄斑 银层厚度 钎焊热处理 氧化 烘烤排气 

分 类 号：TB753[一般工业技术—真空技术]