A high current semiconductor device (for example QFN for 30 to 70 A) with low resistance and low inductance is encapsulated by molding compound (401, height 402 about 0.9 mm) so that the second lead surfaces (110b) remain un-encapsulated. A copper heat slug (404) may be attached to chip surface (101b) using thermally conductive adhesive (403). Chip surface (101a), protected by an overcoat (103) has metallization traces (102). Copper-filled windows contact the traces and copper layers (105) parallel to traces. Copper bumps (108) are formed on each line in an orderly and repetitive arrangement so that the bumps of one line are positioned about midway between the bumps of the neighboring lines. A substrate has elongated leads (110) oriented at right angles to the lines; the leads connect the corresponding bumps of alternating lines.