B-stageable and skip-curable wafer back side coating adhesives
View Patent ↗An adhesive composition comprising elastomeric polymer, epoxy resin, reactive diluent, and filler, is suitable for use within the electronics industry, and in particular for wafer back side coating adhesives. The elastomeric polymer is a mixture of a vinyl elastomer and an epoxy elastomer; the reactive diluent is a combination of two or more diluents, one of which must have carbon to carbon unsaturation, providing cross-linking within the composition after cure; and the filler is a non-conductive filler.
1. An adhesive composition comprising:
(A) an elastomeric polymer comprising a mixture of a vinyl elastomer and an epoxy elastomer, the mixture present in an amount within the range of 20% to 40% by weight,
(B) an epoxy resin, present in the adhesive composition in the range of 3% to 10% by weight,
(C) reactive diluent comprising a combination of two or more diluents, one of which must have carbon to carbon unsaturation, the combination present in the adhesive composition within the range of 35% to 50% by weight of the composition,
(D) a curing agent, and
(E) filler, sufficient to bring the total of the composition to 100% by weight.
2. The adhesive composition according to claim 1 in which the mixture of vinyl elastomer and epoxy elastomer are present in a weight ratio of 1:3 and have weight average molecular weights (MW) within the range of 3000 to 100,000.
3. The adhesive composition according to claim 1 in which the vinyl and epoxy elastomers have glass transition temperatures (Tg) within the range of −65° to 20° C.
4. The adhesive composition according to claim 1 in which the vinyl and epoxy elastomers are selected from the group consisting of butadiene-acrylonitrile rubbers, butadiene rubbers, nitrile butadiene rubbers, polyurethane elastomers, polyisobutene elastomers, polyisoprene elastomers, polyester amide elastomers, ethylene-vinyl acetate copolymer elastomers, polypropylene elastomers, polyethylene elastomers, siloxane elastomers, and copolymers prepared from two or more of styrene, isoprene, butadiene, ethylene, and propylene.
5. The adhesive composition according to claim 4 in which the vinyl and epoxy elastomers are butadiene-acrylonitrile rubbers.
6. The adhesive composition according to claim 1 in which the epoxy resin is selected from the group consisting of novolac epoxy resins, bis-phenol epoxy resins, aliphatic epoxy resins, and aromatic epoxy resins.
7. The adhesive composition according to claim 1 in which the epoxy resin has a weight average molecular weight of 3000 or less.
8. The adhesive composition according to claim 1 in which the reactive diluents are selected from the group consisting of THF acrylate monomer, 4-hydroxybutyl acrylate glycidylether monomer, glycidyl acrylate, glycidyl methacrylate, and 1,4-cyclohexanedimethanol monoacrylate.
9. The adhesive composition according to claim 1 in which at least one reactive diluent is an acrylate or methacrylate containing an epoxy or hydroxyl group.
10. The adhesive composition according to claim 1 in which the filler is selected from the group consisting of ground quartz, fused silica, amorphous silica, talc, glass beads, graphite, carbon black, alumina, clays, mica, vermiculite, aluminum nitride, and boron nitride.