| 摘要 |
PURPOSE:To obtain a lead frame of high reliability without noble metal by only plating gloss Ni on a substrate of Fe or Cu, and forming a solder plating layer on the position to be bonded with a semiconductor element. CONSTITUTION:The connecting strength of aluminum wirings 7 on a substrate 1 of Fe or Cu depends largely upon the surface state of an Ni-plating 4 on the substrate 1, stable connection cannot be obtained in case of glossless Ni plating on rough surface, but more stable in connection when the surface is more smooth. Accordingly, smooth Ni plating layer 4 which is more smooth than semigloss is formed. Further, pure Pb or Pb solder plating layer is used as a lower layer, pure Sn or Sn solder plating layer is superposed, and a semiconductor element is brazed at 5. According to this solder plating layer, the thermal stress after brazing can be absorbed by the lower layer, discoloration can be prevented by the upper layer, and ageing deterioration in moistening property can be prevented. According to this configuration, a lead frame having high reliability can be obtained without using a noble metal. |
