| 摘要 |
PROBLEM TO BE SOLVED: To provide a rolled copper foil for flexible printed wiring boards which suppresses crack growth even under its strict bending conditions to obtain its high bendable quality. SOLUTION: The rolled copper for flexible printed wiring boards has conductivity not smaller than 80% IACS after heat-treating at 300°C for 30 minutes. Also, it has a crystal grain boundary in the cross section viewed in a direction parallel to its rolling direction. Further, it satisfies such a relation of N/t≥1 that N is the number of grain boundaries each of which intersects the straight line connecting one grain surface with the other grain surface in a shortest distance, at an angle not smaller than 45°when it has a foil thickness of t(μm). Moreover, when its grain size is D and its thickness is t0 after final annealing, it is manufactured by final rolling with workability satisfying the relation of 0.13×D+0.75≤ln(t0/t)≤0.085×D+2.95, after final annealing. COPYRIGHT: (C)2009,JPO&INPIT
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