COMPOSITE BRAZING FILLER METAL AND BRAZING METHOD THEREOF

摘要

PURPOSE:To execute brazing in a good position by interposing a composite laminated brazing filler metal consisting of >=3 layers formed by sandwiching Au layers with Sn-In alloy sat specific weight ratios in a weld zone and executing brazing of mainly the Sn-In alloy at a specific temp., then heating the weld zone to a specific temp. to diffuse both the brazing filler metals. CONSTITUTION:The composite laminated brazing filler metal of >=3 layers is formed by sandwiching 45-90wt.% Au layers having a high m.p. with 1-60wt.% low melting Sn-In alloy layers. Such brazing filler metal is rolled and is blanked to a prescribed shape. The blanked brazing filler metal is interposed in the weld zone and is heated to 120-180 deg.C above the m.p. of the Sn-In alloy by which the brazing of mainly the Sn-In alloy is executed. The brazing filler metal is then heated up to 220-280 deg.C at which the Sn-In alloy does not flow so much to diffuse the Sn-In alloy and Au so as to enhance the joint strength. Brazing is satisfactorily executed without forming an intermetallic compd. with the weldment and without changing the position. The composite brazing filler metal may also be formed in the superposed shape of >=2 layers with the Au as a center.