PURPOSE: To perform sure electrical connection between inside/outside a vacuum chamber with the deformation or boring of/in a sleeve prevented, by making the melting temperature of solder material, on which an aluminium-made sleeve is to be fittably mounted on the jaw part of an insulating board.

CONSTITUTION: A metalized layer 5 is formed on the jaw part 1a of an insulating board 1, composed of an aluminum oxide quality sintered body, etc. An aluminium-made sleeve 2 is soldered to the layer 5, and a vacuum terminal is fixedly mounted on the vacuum chamber of a physical and chemical equipment, etc. At that time, solder material, composed of the alloy, etc., of aluminium and germanium and having a melting temperature of 570°C or less. is used for solder material 4, by which the sleeve 2 is soldered to the jaw part 1a via the layer 5. This eliminates the occurrence of the deformation or haling in the sleeve 2 due to heat in blazing.