Die attach adhesive composition

Claim 1

A composition which is useful for bonding integrated circuits to inorganic dielectric substrates comprising an admixture of a. finely divided particles of metal and/or metal containing compound having a thermal conductivity of at least 0.2 Wcm -1 K -1 at 298 K at least 90% of the metal particles having a maximum dimension of less than 15 μm; b. finely divided particles of a non-aqueously milled crystallizable amorphous glass frit which (1) has a DTA softening point of 300°-400° C., (2) has a contact angle with gold of no more than 60° when measured at a peak temperature of 400° C., and (3) is substantially free of alkali metal and halogen ions, the volume ratio of a. to b. being from 0.75 to 5.0; c. 0.2-2% weight of a surfactant selected from long chain carboxylic acids, alkyl esters of long chain carboxylic acids, and mixtures thereof, a., b., and c. being dispersed in d. organic medium comprising a solution of (1) acrylic polymer free of polar functional groups dissolved in (2) a solvent consisting essentially of (a) 60-100% wt. of a primary solvent selected from ethylene glycol monobutyl ether acetate, dimethyl adipate and mixtures thereof and (b) 40-0% wt. of a secondary solvent selected from glycol monoethers, terpineol, 2,2,4-trimethyl-1,2-pentanediol monoisobutyrate, tridecyl acetate and mixtures thereof, the total composition containing 0.5--5% wt. acrylic polymer, the composition having a yield stress of at least 200 dynes/cm.