| 摘要 |
PURPOSE:To obtain stock for a lead frame having especially superior corrosion resistance, solderability and adhesion by forming a Cu coating layer of a prescribed thickness on a Cr-contg. steel sheet contg. specified amounts of C, acid- sol. Al and Cr. CONSTITUTION:The above-mentioned stock is obtd. by forming a Cu coating layer of 1.5-10mum thickness on a Cr-contg. steel sheet consisting of, by weight, <=0.30% C, 0.005-0.10% acid-sol. Al, 3-11% Cr and the balance Fe with inevitable impurities. One or more among 0.05-1% Cu, 0.05-3% Ni and 0.05-0.5% Mo may be incorporated into the steel sheet so as to improve the rust preventiveness and corrosion resistance. Those elements give higher potential in combination with Cr in a corrosive environment and reduce the potential difference between the steel sheet and the Cr coating layer, so the deterioration of the rust and corrosion resistances by the preferential corrosion of Fe can be further prevented.
|
