Patent number: 5817545

Pressurized underfill encapsulation of integrated circuits

Original Assignee: Cornell Research Foundation, Inc.

Field of technology: Electronics, Industrial Machinery and Processes

Patent granted on: Tue, 06 Oct 1998

Patent drawing

Abstract

A new method and device to encapsulate integrated circuits such as flip chips and BGA packages. A special mold to surrounds the chip to be encapsulated in a cavity, and the encapsulant is injected into the cavity at an elevated pressure, and possibly at an elevated temperature. This shortens the cavity filling time by two or three orders of magnitude, compared to the conventional dispensing process. The reliability of the package is increased by increasing the adhesion of encapsulant to the package, by controlling fillet shape through in-mold curing, and by completely filling the cavity through proper mold design and, optionally, evacuation of the cavity prior to injection. The invention also allows the use of a wider range of encapsulants, including highly viscous material, fast curing materials and reworkable materials.