| 主权项 |
1. A method of preparing a one-part and heat-curable die attach adhesive (DAA) composition comprising:
providing a thermally and electrically conductive filler; providing a polymer matrix; providing a solvent; and mixing the thermally and electrically conductive filler, the polymer matrix and the solvent to form the composition, wherein said filler is an inorganic compound with 30-96% by weight of the composition, said inorganic filler being further modified prior to said mixing to form a modified filler formulation to improve fluidity of said filler in the solvent, and said modified filler formulation having different graded sizes of the filler comprising:
microparticles having a diameter of about 13-50 μm in about 20-100% by weight of said inorganic filler,microparticles having a diameter of about 6-12 μm in about 10-100% by weight of said inorganic filler,microparticles having a diameter of about 5-6 μm in about 10-90% by weight of said inorganic fillers,microparticles having a diameter of 1-5 μm in about 20-100% by weight of said inorganic filler,nanoparticles having a diameter of about 10-200 nm in about 1-10% by weight of said inorganic filler, and/or nanorods having a diameter of about 100 nm-1 μm and a length of about 1-10 μm in 1-10% by weight of said inorganic filler; and wherein the nanoparticles and/or the nanorods fill gaps among the microparticles to form shortcuts, resulting in continuous, direct and multichannel dissipation pathways to facilitate heat dissipation; wherein the surface of said inorganic filler is further modified by a dispersing agent comprising at least one of glycerin fatty acid esters or their polymers, organic silane coupling agents having hydrophilic groups and/or hydrophobic groups, organic titanates having hydrophilic groups and/or hydrophobic groups, thiol containing molecules with hydrophilic groups and/or hydrophobic groups, or a combination thereof for facilitating dispersing the inorganic filler into the polymer matrix, and wherein said dispersing agent is about 0.1-10% by weight of said inorganic filler; wherein after modifying the surface of the inorganic filler and mixing the thermally and electrically conductive filler, the polymer matrix and the solvent to form the DAA composition with said modified filler formulation having different graded sizes of the modified filler, the fluidity of the fillers in the solvent is improved, enabling homogeneous dispersion of the filler to form the adhesive with high thermal conductivity; wherein said polymer matrix is 2-30% by weight of the DAA composition;said solvent is 2-40% by weight of the DAA composition;
wherein said thermal conductivity is at least 40 W/M·K, and curing temperature of the DAA composition is about 80-100° C.; and wherein the modified filler formulation is further re-dispersed in a solvent selected from toluene, xylene, propylene carbonate, mixed aliphatic dimethyl esters, diethylene glycol monomethyl ether acetate, dimethyl carbonate, diethylene carbonate, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethanol, isopropanol, n-butanol, ethyl acetate, or a combination thereof, and wherein an ultrasonic probe is applied after re-dispersing the modified filler formulation in said solvent, followed by size separation by centrifuge and then vacuum drying the selected filler under a temperature ranging from about 60-150° C. for 10 minutes to 3 hours. |
