Patent ID: 7251872

Claim:
A method for forming a chip package, comprising the steps of: a. providing a lead frame of predetermined thickness having an upwardly facing surface and a downwardly facing surface, a central region having a first plurality of sides, and a peripheral edge region having a second plurality of sides extending around and spaced from said first plurality of sides; b. providing an upper mask to position resist material on said upwardly facing surface that define a first set of leads extending from each of said second plurality of sides, each of said first set of leads being partially defined by a first terminal end, first opposing side surfaces each of which extends along a respective first longitudinal axis, and a lower surface that extends in a first plane; c. providing a lower mask to position resist material on said downwardly facing surface that define a second set of leads extending from said second plurality of sides, each of said second set of leads being partially defined by a second terminal end, second opposing side surfaces each of which extends along a respective second longitudinal axis, and an upper surface that extends in a second plane, and a portion of said second set of leads that are vertically aligned with a portion of said first set of leads; d. etching away portions of said upwardly facing surface that are not covered with said resist material to a depth greater than one half of said predetermined thickness; and e. etching away portions of said downwardly facing surface that are not covered with said resist material to a depth greater than one half of said predetermined thickness, wherein each of said first set of leads are positioned in non-overlapping staggered relation to corresponding ones of said second set of leads such that said first terminal ends are spaced from said second terminal ends by a first predetermined distance, each of said first longitudinal axes are substantially parallel to and spaced from the adjacent ones of said second longitudinal axes by a second predetermined distance, and said first plane is spaced from said second plane by a third predetermined distance.