A flip chip semiconductor device comprising: a drain contact and a source contact on a first surface of said device; a metal layer on a second surface of said device, said second surface opposite said first surface; a substrate layer adjacent said metal layer, wherein said substrate layer is separated from said drain contact by an intervening layer; a plurality of solder balls (302, 304, 306, 308) comprising a solder ball coupled to said drain contact; a plurality of feed-through trenches (230; 510, 512) under said drain contact on said first surface, each of said feed-through trenches (230, 510, 512) filled with a filler material coupled to said drain contact, wherein said feed-through trenches (230; 510, 512) pass completely through said intervening layer and into said substrate layer, said filler material in said feed-through trenches providing an electrical connection between said drain contact and said substrate layer, wherein said plurality of feed-through trenches (230; 510, 512) form an array of adjacent feed-through trenches; wherein in operation said semiconductor device comprises a circuit from said source contact through said intervening layer, said substrate layer, and said feed-through trenches (230; 510, 512) to said drain contact; characterized in that said plurality of feed-through trenches (230; 510, 512) are arrayed in only a portion of the intervening layer of said semiconductor device under said drain contact between said drain contact and said substrate layer, wherein said plurality of feed-through trenches (230; 510, 512) are not included under said drain contact outside said portion and wherein said feed-through trenches (230; 510, 512) within said portion are concentrated toward said source contact. a drain contact and a source contact on a first surface of said device; a metal layer on a second surface of said device, said second surface opposite said first surface; a substrate layer adjacent said metal layer, wherein said substrate layer is separated from said drain contact by an intervening layer; a plurality of solder balls (302, 304, 306, 308) comprising a solder ball coupled to said drain contact; a plurality of feed-through trenches (230; 510, 512) under said drain contact on said first surface, each of said feed-through trenches (230, 510, 512) filled with a filler material coupled to said drain contact, wherein said feed-through trenches (230; 510, 512) pass completely through said intervening layer and into said substrate layer, said filler material in said feed-through trenches providing an electrical connection between said drain contact and said substrate layer, wherein said plurality of feed-through trenches (230; 510, 512) form an array of adjacent feed-through trenches; wherein in operation said semiconductor device comprises a circuit from said source contact through said intervening layer, said substrate layer, and said feed-through trenches (230; 510, 512) to said drain contact; characterized in that said plurality of feed-through trenches (230; 510, 512) are arrayed in only a portion of the intervening layer of said semiconductor device under said drain contact between said drain contact and said substrate layer, wherein said plurality of feed-through trenches (230; 510, 512) are not included under said drain contact outside said portion and wherein said feed-through trenches (230; 510, 512) within said portion are concentrated toward said source contact.