| abstract |
The present invention discloses chip (die) bond adhesive formulationsnpreferably comprising a siloxane containing epoxide preferably a diglycidylnether derivative, an anhydride curing additive which is soluble in thenepoxide without the use of a solvent, and, optionally comprising, annoligomeric/polymeric co-additive of the type poly(alkyl-acrylate or -nmethacrylate), in conjunction with thermal and electrically conductivenfillers and conventional co-catalysts used for curing epoxy systems tonprovide reworkable epoxy adhesives. Also disclosed are adhesivenformulations comprising a siloxane containing epoxide and anhydroxybenzophenone curing additive which is soluble in the epoxide withoutnthe use of a solvent. The chips can be bonded to the substrate bynconventional heating and curing techniques. With epoxy adhesivencompositions comprising polyacrylate additives, the die bonded assembly cannbe reworked by heating the assembly to about 180°C to 250°C removing thenchip, and rebonding a new chip on the same surface without any effect on thenshear strength for die bonded on to gold, copper, silver or a ceramic dienpad. Die shear strength using the adhesives remains unchanged when exposednto thermal shock involving -65°C to +150°C excursions, and HAST test at 130°Cn/85 percent RH (Relative Humidity) or 85°C/85% RH. A method is alsonprovided for using the adhesives to make electronic component assemblies. |