Method for Assemblying a Semiconductor Chip Package with Deflection-Resistant Leadfingers

Abstract

Embodiments of the invention relate to methods for semiconductor chip package assembly. An embodiment of the invention includes providing a metallic leadframe with a chip mounting surface and a plurality of leadfingers. The leadfingers have a proximal end for receiving one or more wirebonds and a distal end for providing an electrical path from the proximal end. One or more of the leadfingers also has an offset portion and underlying heat spreader, increasing the stiffness of the leadfinger, and increasing leadfinger deflection-resistance and spring-back. The offset is in the direction opposite the plane of a heat spreader thermally coupled to the mounting surface. A semiconductor chip is affixed to the mounting surface and a plurality of bond pads of the chip are wirebonded to the offset portions of the proximal ends of individual leadfingers. The chip, the bondwires, portions of the heat spreader and leadfingers are encapsulated.

1 .- 9 . (canceled) 
     
     
         10 . A method for assembling a semiconductor chip package comprising:
 providing a metallic leadframe, the leadframe comprising a mounting surface for receiving a semiconductor chip, the leadframe further comprising a plurality of leadfingers, each leadfinger having a proximal end for receiving one or more wirebond, the proximal ends of the leadfingers defining a plane parallel to a surface of the heat spreader, each leadfinger also having a distal end for receiving electrical connections external to the package;   wherein, each of the plurality of the leadfingers further comprises an offset portion at its proximal end, the offset portion being in the direction opposite the plane of the heat spreader and angled away from a plane of the distal end, the heat spreader situated for providing a thermal path from the mounting surface;   affixing a semiconductor chip to the mounting surface;   wirebonding a plurality of bond pads of the semiconductor chip to a plurality of offset portions of the proximal ends of the leadfingers; and   encapsulating the chip, bondwires, and portions of the heat spreader and leadfingers.   
     
     
         11 . The method according to  claim 10 , wherein the wirebonding further comprises operably coupling at least one leadfinger offset portion to a plurality of bond pads. 
     
     
         12 . The method according to  claim 10 , wherein the mounting surface comprises a portion of the surface of the heat spreader. 
     
     
         13 . The method according to  claim 10  wherein the mounting surface further comprises a paddle portion of the leadframe. 
     
     
         14 . The method according to  claim 10  further comprising riveting the heat spreader to the leadframe.