Metal member and electric contact using same

1 . A metal member comprising:

a metal base;

a first plating layer of nickel and unavoidable impurities, said first plating layer being formed on the metal base;

a second plating layer of nickel, phosphorus and unavoidable impurities, said second plating layer being formed on said first plating layer;

a third plating layer of a gold alloy and unavoidable impurities, said third plating layer being formed on said second plating layer; and

a fourth layer formed on said third plating layer by a sealing process,

whereas said first plating layer has a thickness of 0.5 to 2.5 μm, and said second plating layer has a thickness of 0.05 to 0.5 μm, the sum of the thicknesses of the first and second plating layers being in the range of from 0.60 μm to 2.5 μm, and said third plating layer having a thickness of not less than 0.05 μm.

2 . A metal member as set forth in claim 1 , wherein said first plating layer is a nickel plating layer formed by a sulfamic acid bath or by a Watt's bath to which a primary brightener containing a sulfur content is added.

3 . An electric contact comprising:

a first terminal of a metal member as set forth in claim 1; and

a second terminal contacting said first terminal.

4 . An electric contact comprising:

a first terminal of a metal member as set forth in claim 2; and

a second terminal contacting said first terminal.