Epoxy resin, styrene-maleic anhydride copolymer and crosslinking agent
View Patent ↗A composition useful as an impregnant for the making of laminates for printed wiring boards including an epoxy resin, a first cross-linking agent of a strene-maleic anhydride copolymer and a second co-cross-linking agent.
1. A resin composition comprising:
a mixture of:
an epoxy resin that is a derivative of bisphenol A;
a crosslinking agent comprising a copolymer of styrene and maleic anhydride (SMA), and;
at least 5% by weight of a co-crosslinking agent selected from the group consisting of a brominated bisphenol A (BPA), brominated bisphenol A diglycidyl ether (BPADGE), and mixtures thereof wherein the resin composition does not include an acrylic resin.
2. The resin composition of claim 1 wherein the copolymer of styrene and maleic anhydride has a molecular weight of about 1400 to about 50,000, and an anhydride content of more than 15% by weight.
3. The resin composition of claim 1 wherein the epoxy resin is FR4.
4. The resin composition of claim 1 , further comprising an accelerator.
5. The resin composition of claim 4 wherein the accelerator is an imidazole.
6. The resin composition of claim 1 further comprising one or more additives selected from the group consisting of dyes, pigments, thixotropic agents, fluidity control agents, and stabilizers.
7. The resin composition of claim 1 having a ratio of anhydride and aromatic hydroxyl groups: epoxy groups of from 90 to 130.
8. The resin composition of claim 1 having a ratio of anhydride and aromatic hydroxyl groups: epoxy groups of from 90 to 110.
9. A resin composition comprising:
a mixture of:
an FR-4 epoxy resin;
a crosslinking agent comprising a copolymer of styrene and maleic anhydride (SMA), and;
at least 5% by weight of a co-crosslinking agent selected from the group consisting of a brominated bisphenol A (BPA), brominated bisphenol A diglycidyl ether (BPADGE), and mixtures thereof.
10. The resin composition of claim 1 wherein the amount of copolymer used will give an anhydride and aromatic hydroxyl group: epoxy group equivalency ratio of between 90 and 110%.
11. The resin composition of claim 1 including at least 10% by weight of tetrabromobisphenol A and at least 10% by weight tetrabromobisphenol A diglycidyl ether.
12. The resin composition of claim 1 including at least 10% by weight of tetrabromobisphenol A diglycidyl ether.