Patent ID: 7776993
Filing Date: 2010-08-17
Classification: C08G,H01L,Y10T

Abstract:
1. A process for encapsulating a chip or wafer with metal solder bumps and a substrate with metal pads comprising the steps of a) providing a chip or wafer with a first surface comprising a plurality of metal solder bumps in a first pattern; b) coating on said first surface an underfill to the extent that said underfill completely covers said plurality of metal solder bumps; c) applying a B-stage cure to obtain a tack-free B-staged underfill coated on said first surface, d) providing a substrate with a second surface comprising a plurality of metal pads in a second pattern, wherein said second pattern is aligned with said first pattern when contacted therewith; e) aligning said metal solder bumps on said chip or wafer with the corresponding metal pads on said substrate to form an aligned assembly; f) heating said aligned assembly above the Tg of said B-staged underfill, and applying pressure to push said B-staged underfill out of the way of said metal solder bumps to establish metal to metal contact between said metal solder bumps and said metal pads; wherein an encapsulated assembly is obtained with said underfill disposed in the spaces between the contacted metal solder bumps and metal pads within said first and second surfaces; wherein said underfill is an epoxy-containing oligomer having the formula: wherein n is 1 to 6, and X is the same or different, and is selected from the group consisting of: at least one R and any R and Q is selected from the group consisting of: said epoxy groups in said epoxy-containing oligomer, after said epoxy-containing oligomer is cured, being cleavable using an acid selected from the group consisting of an organic acid and a Lewis acid.