| 摘要 |
PURPOSE:To disperse and absorb the distortion in the direction of major axis generating on a lead frame after a resin sealing is performed by a method wherein a distortion-preventing part is provided at the tip part of the external lead. CONSTITUTION:A distortion-preventing work is performed on the external lead 16 of a lead frame. When the width of narrow-widthed part of the tip of the external lead 16, which is processed in the first process, is set at B and the plate thickness of the lead frame is set at T, the width with which a work can be performed smoothly is B=TX(1-0.5). When the plate thickness after coining of t1, B is set at the width of said narrow-widthed part, the range of smooth working is worked out as t1=BX(0.5-0.8). When the width of a distortion-preventing part 20 after trimming is set at (b1), b1=t1X(1-0.5) is obtained. The above-mentioned formula is worked out by the same way of thinking used when the first process is performed for formation of the narrow-widthed part. The working on distortionpreventing part 20 is completed with the third process. It is practically unnecessary to perform the above- mentioned working on all the external leads, the purpose of distortion-prevention can be accomplished by performing the work for several pieces of lead frames for a semiconductor unit. |
