| 摘要 |
An electrical property (low contact resistance) after being maintained for a long time at a high temperature is improved in a Sn-coated-layer attached copper alloy board, in which a surface coating layer is formed in order of a Ni-layer, a Cu-Sn alloy layer and a Sn-layer on the surface of a base material consisting of a copper alloy board. The Sn-coated-layer attached copper alloy board comprises 0.1-3.0 μm of the average thickness of the Ni-layer, 0.2-3.0 μm of the average thickness of the Cu-Sn alloy layer, and 0.01-5.0 μm of the average thickness of the Sn-layer, wherein the Cu-Sn alloy layer consists of η-phase (Cu6Sn5) only or η-phase and ε-phase (Cu3Sn). If the Cu-Sn alloy layer consists of ε-phase and η-phase, the ε-phase exists between the Ni-layer and the η-phase, and the ε-phase thickness ratio (the ratio of the average thickness of the ε-phase to the average thickness of the Cu-Sn alloy layer) is 30% or less. Also, the thermal expoliation resistance is improved by controlling the ε-phase length ratio (the ratio of the length of the ε-phase to the length of the Ni-layer in the cross-section of the surface coated layer) to 50% or less. |
