Chain extended epoxy to improve adhesion of conductive die attach film
View Patent ↗A conductive adhesive film is prepared from components comprising a thermosetting resin, a film-forming resin, a conductive filler, and further comprising a chain extended epoxy resin prepared from the reaction of a poly-functional phenol with a combination of a poly-functional aromatic epoxy and a poly-functional aliphatic epoxy (poly-functional includes di-functional). The addition of the chain extended epoxy preserves the adhesiveness of the conductive adhesive film at silver loadings of 80 weight percent or greater.
1. A conductive adhesive composition comprising:
(i) a thermosetting resin,
(ii) optionally, a film-forming resin,
(iii) a conductive filler, and
(iv) a chain extended epoxy prepared from a reaction of a poly-functional phenol with a combination of a poly-functional aromatic epoxy and a poly-functional aliphatic epoxy,
wherein the poly-functional aromatic epoxy is selected from the group consisting of:
2. The conductive adhesive composition according to claim 1 in which the chain extended epoxy is present in the composition an amount of 1-20 wt % of the total composition.
3. The conductive adhesive composition according to claim 1 in which the poly-functional aliphatic epoxy used to prepare the chain extended epoxy is selected from the group consisting of:
4. The conductive adhesive composition according to claim 1 in which the poly-functional phenol used to prepare the chain extended epoxy is selected from the group consisting of
in which n is a numeral denoting repeating units.
5. The conductive adhesive composition according to claim 1 in which the stoichiometric ratio of the total epoxy functional groups to the phenolic functional groups in the chain extended epoxy ranges from 0.05 to 30.
6. The conductive adhesive composition according to claim 1 in which the thermosetting resin is an epoxy selected from the group consisting of diglycidyl ethers of bisphenol A epoxy resin, diglycidyl ethers of bisphenol F epoxy resin, epoxy novolac resins, epoxy cresol resins, and those having the structures:
7. The conductive adhesive composition according to claim 6 in which the claim extended epoxy is present in the composing an amount of 1-20 wt % of the total composition.
8. The conductive adhesive composition according to claim 6 in which the poly-functional aliphatic epoxy used to prepare the chain exted epoxy is selected from the group consisting of:
9. The conductive adhesive composition according to claim 6 in which the poly-functional phenol used to prepare the chain extended epoxy is selected from the group consisting of
in which n is a numeral denoting repeating units.
10. The conductive adhesive composition according to claim 6 in which the stoichiometric ratio of the total epoxy functional groups to the phenolic functional groups in the chain extended epoxy ranges from 0.05 to 30.
11. The conductive adhesive composition according to claim 6 in which the epoxy is present in an amount from about 0.5 wt % to about 40 wt % of the total composition.
12. The conductive adhesive composition according to claim 1 in which the thermosetting resin is a bismaleimide selected from the group consisting of 4,4′-diphenylmethane bismaleimide, 4,4′diiphenylether bismaleimide, 4,4′diiphenylsulfone bismaleimide, phenylmethane maleimide, m-phenylene bismaleimide, 2,2′-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6′-bismaleimide-(2,2,4-trimethyl)hexane, 1,3-bis(3-maleimidophenoxy)benzene, and 1,3-bis(4-maleimidophenoxy)-benzene.
13. The conductive adhesive composition according to claim 1 in which the thermosetting resin is an acrylate having the structure
14. The conductive adhesive composition according to claim 1 in which the thermosetting resin is present in an amount from about 0.5 wt % to about 40 wt % of the total composition.
15. The conductive adhesive composition according to claim 1 in which the film forming resin is present and is selected from the group consisting of the adduct of a carboxy-terminated butadiene acrylonitrile and a liquid or viscous epoxy resin;
poly[(methyl)methacrylate]-b-poly(butyl acrylate)-b-poly[(methyl)methacrylate]; poly[styrene-b-polybutadiene-b-poly[(methyl)methacrylate], butadiene rubbers, and styrene rubbers.
16. The conductive adhesive composition according to claim 15 in which the film forming resin is present in the conductive composition in an amount up to about 30 wt % of the total composition.
17. The conductive adhesive composition according to claim 1 in which the conductive filler is selected from the group consisting of carbon black, graphite, gold, silver, copper, platinum, palladium, nickel, aluminum, silver plated copper, silver plated aluminum, bismuth, tin, bismuth-tin alloy, silver plated fiber, silicon carbide, boron nitride, diamond, alumina, and alloy 42.
18. The conductive adhesive composition according to claim 1 in which the conductive filler is present in the conductive composition in an amount of 80 wt % or greater of the total composition.
19. A conductive adhesive composition comprising:
(i) a thermosetting resin selected from the group consisting of diglycidyl ethers of bisphenol A epoxy resin, diglycidyl ethers of bisphenol F epoxy resin, epoxy novolac resins, epoxy cresol resins, and those having the structures:
(ii) optionally, a film-forming resin,
(iii) a conductive filler, and
(iv) a chain extended epoxy prepared from a reaction of
(1) a polyfunctional aromatic epoxy selected from the group consisting of:
(2) a poly-functional phenol; and
(3) a poly-functional aliphatic epoxy: