The effect of a coating on the springback of integrated circuit leadframes

Recently, the springback behaviour of integrated circuit (IC) leadframe has been investigated both experimentally and theoretically, but less work has been carried out in examining the effect of a coating on the springback of IC leadframes. In this paper, the springback of leadframes of steel and copper alloys with a different nickel-coating thickness has been studied using a special cantilever-type-forming jig with different die clearances. The springback of the materials is found to increase with increasing coating thickness and die clearance. For both the copper and steel alloys, the strips exhibit a larger springback angle along the rolling direction than that along the transverse direction. A mechanical model reported in the literature has been used to predict the springback behaviour of the coated materials. The significance of the findings are discussed in the paper.