Press-Fit Terminal, a Method for Manufacturing the Same, and a Structure of Connection Between a Press-Fit Terminal and a Circuit Board

A method for manufacturing a press-fit terminal for inserting into a conductive through hole of a circuit board, the method comprising the steps of:

• forming an underplating layer including one or more plating layers on a surface of a terminal base in a connecting part of the press-fit terminal which comes into electrical contact with the through hole;
• forming an Sn plating layer at a thickness of 0.1 to 0.7 μm on the top plating layer;
• and
• after the step of forming the Sn plating layer, conducting a reflow process of performing heat treatment to form an alloy layer of Sn and an underplating metal of the top plating layer on the underplating layer as well as make unalloyed Sn mixed in the alloy layer so as to have a depth of a few to 50 nm from an outside surface of the alloy layer.

A structure of connection between a press-fit terminal and a conductive through hole of a circuit board, wherein

• an underplating layer including one or more plating layers is formed on a surface of a terminal base in a connecting part of the press-fit terminal,
• an alloy layer of Sn and an underplating metal of the top plating layer is formed on the underplating layer,
• unalloyed Sn is mixed in the alloy layer while having a depth of a few to 50 nm from an outside surface of the alloy layer, and
• surface hardness of the press-fit connecting part is higher than surface hardness of a connecting part of the through hole.