| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a copper alloy sheet for electric and electronic parts that simultaneously achieves high strength, high electrical conductivity, good bendability, and high stress relaxation resistance in a Cu-Fe-P-based copper alloy sheet. <P>SOLUTION: The copper alloy sheet for electric and electronic parts has composition in which 2.5-3.5 mass% of Fe and 0.001-0.050 mass% of P are contained, and proper quantities of Mg, Sn, and Zn are added thereto with the balance comprising copper and unavoidable impurities, and has a two-phase structure in which a secondary phase is precipitated in a Cu matrix phase. In the surfaces of section in the rolling direction and the sheet thickness direction, an average crystal grain size D<SB POS="POST">n</SB>in the sheet thickness direction of the matrix phase is 2-15 μm, and when an average crystal grain size in the rolling direction of the matrix phase is D<SB POS="POST">L</SB>, a ratio D<SB POS="POST">L/</SB>D<SB POS="POST">n</SB>to the average crystal grain size D<SB POS="POST">n</SB>in the sheet thickness direction is 1.5 or more. When an average crystal grain size in the rolling direction of a secondary phase particle is D<SB POS="POST">L2</SB>and an average crystal grain size in the sheet thickness direction of the secondary phase particle is D<SB POS="POST">n2</SB>, a ratio D<SB POS="POST">L2/</SB>D<SB POS="POST">n2</SB>is 5 or less. <P>COPYRIGHT: (C)2013,JPO&INPIT |
