Patent ID: 6774497
Filing Date: 2004-08-10
Classification: H01L

Abstract:
A method for attaching a flip chip to an electrical substrate, comprising:providing a bumped flip chip, the flip chip including an active surface and a plurality of connective bumps extending from the active surface, each connective bump including a side region; applying a layer of an underfill material to the active surface of the flip chip and to a portion of the side regions of the connective bumps, the underfill material extending from the active surface of the flip chip to a thickness between nominally 20 percent and 60 percent of a connective bump height; positioning the flip chip on the electrical substrate, the electrical substrate including a layer of a solder mask disposed on the electrical substrate; and heating the flip chip to electrically connect the flip chip to the electrical substrate, wherein the underfill material and the solder mask combine to form a stress-relief layer when the flip chip is electrically connected to the electrical substrate.