Brazing method

A brazing method for bonding a first member and a second member made of one of copper or a copper alloy as a base material by brazing using a brazing material, comprising:

• applying a plurality of lines of paste brazing material spaced from each other and extending in a direction crossing a contact portion defined by the first member and a contact portion defined by the second member to at least one of the first and second members, the plurality of lines of paste brazing material being between opposite ends of the contact portions defined by the first and second members, the plurality of lines of brazing material defining a first part of each of the contact portions to which the brazing material is applied and a second part of the contact portions to which the brazing material is not applied, the paste brazing material consisting essentially of copper (Cu), tin (Sn), nickel (Ni) and phosphorus (P);
• temporarily assembling the first and second members at a predetermined position;
• heating the assembled first and second members at a temperature in a range of 600° C.-800° C. within a reducing atmosphere furnace,
• exposing the second part of the contact portions defined by the first and second members to a reducing gas in the reducing atmosphere furnace during the heating step;
• removing an oxide film from a surface of the second part of the contact portions defined by the first and second members using the reducing gas in the reducing atmosphere furnace;
• and
• melting the plurality of lines of the paste brazing material to allow the melted paste brazing material to flow to the second part of the contact portions defined by the first and second members to form a fillet and bond the first and second members.