Allegro Microsystems, LLC

Paul J Panaccione

Jay J Gagnon

Thomas J Martiska

Paul A Guillotte

The lead-frame in an integrated circuit package, a standard package designated SOT-89, has a plurality of leads of which at least one is an extension of a die-attach pad. At least one ground wing is formed as an extension of a peripheral portion of the die-attach pad and extends upward to approximately the plane of the top of the die. The ground wing has an upstanding portion and a horizontal portion that are at an angle to each other so as to lock the distal end of the wing in the body of encapsulating resin. An integrated circuit die having at least one electrical connection which is grounded electrically via a terminal and wire bonded to the distal part of the ground wing. A contact surface near the distal end of wing is positioned approximately in the plane of the top of the die. This ground circuit can parallel and can be redundant to a ground circuit through the die via the conductive bond that attaches the bottom of the die to the die-attach pad. The ground lead that is an extension of the die-attach pad serves both to remove heat from the die and to provide an electrical ground connection. The contact surface of the wing provides a point of ground-wire attachment that does not move relative to the encapsulating resin as do other peripheral parts of the die attach pad during temperature cycling and mechanical stress. Thus, a common failure mode, which is called heal-cracking, is substantially eliminated.

Integrated-circuit lead-frame package with failure-resistant ground-lead

A uniformly thick dielectric polyimide coating is provided on the back face of an integrated circuit and the die is mounted to a copper lead frame finger by interposing an epoxy resin bonding agent between the uniformly thick polyimide coating and the copper support finger. The die coating is provided before separating die from the precursive water. Liquid polyimide is poured onto the back side of the water which is spun, in a manner similar to that usually used for obtaining uniformly thick photoresist films. After curing the polyimide, the die are cut from the wafer by sawing.

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Barre, MA, United States of America

Paul J Panaccione