| 摘要 |
PROBLEM TO BE SOLVED: To realize a lead frame in which cracking can be suppressed even when a plated layer of Sn or an An alloy containing no Pb is formed by heating a plated layer at a temperature higher than the melting point thereof and then cooling the plated layer. SOLUTION: Underlying Cu and Ni plated layers 7, 8 and an Ag strike plated layer 9 are laminated on a basic material 6 having surface subjected to degreasing, cleaning and acid treatments. An Ag plated layer 10 is then formed at the parts 2c, 3c of inner lead parts 2a, 3a and outer lead parts 2b, 3b and then a mat finished Sn electroplated layer 11 is formed at the outer lead parts 2b, 3b and a coupling part 5. More specifically, Sn is diffused from the Sn plated layer 11 at the parts 2c, 3c into the Ag plated layer at the inner lead parts 2a, 3a to prevent the bonding strength of an LED element 14 and a wire 15 from lowering. Consequently, when the plated layer is thermally fused by heating at a temperature higher than the melting point thereof and then cooled down, internal stress is removed and generation of whiskers can be suppressed. |
