US 7,321,005 B2
Encapsulant composition and electronic package utilizing same
Konstantinos I. Papathomas, Endicott, N.Y. (US)
Assigned to International Business Machines Corporation, Armonk, N.Y. (US)
Filed on Mar. 19, 2007, as Appl. No. 11/687,997.
Application 11/687997 is a division of application No. 09/778996, filed on Feb. 07, 2001, granted, now 7,192,997.
Prior Publication US 2007/0185227 A1, Aug. 09, 2007
Int. Cl. C08K 3/10 (2006.01); C08L 63/00 (2006.01); C08L 71/12 (2006.01); C08L 87/00 (2006.01); H01L 21/56 (2006.01)
U.S. Cl. 523—442  [257/793; 438/127; 523/443; 524/544; 524/560; 524/567; 524/571; 524/574; 524/575; 524/577; 524/578; 524/579; 524/588; 524/590; 524/601; 524/606; 524/609; 524/611; 524/612; 525/390; 525/396; 525/507; 525/524] 12 Claims
 
1. A method of making an encapsulant composition, the method comprising the steps of:
providing a first quantity of resin material selected from the group consisting of epoxy and cyanate ester resins;
adding to said first quantity of resin material a second quantity of flexibilizing agent by homogenizing said flexibilizing agent in said first quantity of resin material by reacting said resin material and said flexibilizing agent together at a temperature of greater than about 100 degrees Celsius, from about 1.0% by weight to about 5% by weight of the composition of said flexibilizing agent comprising a flexibilizer containing functional groups capable of reaction with the epoxy or cyanate ester resin during thermally induced curing, and a thermoplastic other than the flexibilizer, wherein the thermoplastic is separated from the cured epoxy or cyanate ester resin;
adding to said first quantity of resin material a third quantity of filler material comprising substantially spherical or spheroidal particles, each particle having a diameter of less than about 41 microns;
blending said resin material, wherein after said blending said flexibilizing agent comprises 1 percent to about 5 percent by weight of said composition, wherein immediately after the steps of adding the flexibilizing agent and adding the filler material have been performed the composition is uncured and the composition is stable for a time period at least 12 hours, wherein the composition has a higher fracture toughness, a lower viscosity, and increased thermal shock resistance at a temperature excursion below −40° C., or combinations thereof than the composition would have if the flexibilizing agent were not present in the composition, wherein the thermoplastic comprises a poly(arylene) ether, and wherein the flexibilizer comprises bis(2,3-epoxy-2-methylpropyl)ether;
after the steps of adding the flexibilizing agent, adding the filler material, and blending the resin material, applying the composition to a gap between a substrate and a semiconductor chip, wherein the semiconductor chip is assembled to the substrate by Controlled Collapse Chip Connection (C4) interconnections, wherein the composition completely covers the C4 interconnections, wherein said applying the composition to the gap comprises dispensing the composition through nozzles under pressure between about 15 pounds per square inch and about 90 pounds per square inch at a temperatures between about 25 degrees ° C. and about 45 degrees ° C. to a surface of the substrate on which the semiconductor is assembled and to at least a portion of edges of a device that comprises the semiconductor chip so as to form a fillet;
after the step of applying the composition to the gap, pregelling the composition by heating the composition for a period of time between about 15 and about 60 minutes at a temperature between about 75° C. and about 100° C.; and
after the pregelling step, substantially curing the composition by heating the composition to a temperature between about 130° C. and about 180° C. for a period of time between about 2 and about 4 hours.