High Tg epoxy formulation with good thermal properties
View Patent ↗Varnish compositions and prepregs and laminates made therefrom wherein the varnish compositions include at least one first epoxy resin and at least one second epoxy resin that includes a bisphenol-A novolac epoxy resin and a harder wherein the at least one first epoxy resin and the at least one second bisphenol-A novolac epoxy resin are present in the varnish at a weight ratio ranging from about 1:1 to about 1:3.
1. A prepreg comprising a b-staged varnish composition including:
30-60 parts by weight of a multi-functional epoxy wherein the multi-functional resin is not an eight-functional bisphenol-A novolac epoxy resin;
80-150 parts by weight of an eight-functional bisphenol-A novolac epoxy resin;
30-60 parts by weight of a bifunctional epoxy resin;
20-50 parts by weight of a hardener selected from 4,4′diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone and mixtures thereof; and
10-70 parts by weight of a flame retardant wherein the prepreg is capable of being c-staged to a composite having a DMA Tg in excess of 280° C. and a T288 time in excess of 20 minutes.
2. The prepreg of claim 1 wherein the multifunctional epoxy resin and the eight functional bisphenol-A novolac epoxy resin are present in the varnish at a weight ratio ranging from about 1:1.8 to about 1:2.0.
3. The prepreg of claim 1 wherein the hardener is 4,4′-diaminophenylsulfone.
4. The prepreg of claim 1 wherein the at least one flame retardant is decabromodiphenylethane.
5. A printed circuit board including at least one layer that is a c-staged prepreg of claim 1 .
6. A prepreg comprising a b-staged varnish composition including:
30-60 parts by weight of a multi-functional epoxy resin wherein the multi-functional resin is not an eight-functional bisphenol-A novolac epoxy resin;
80-150 parts by weight of an eight-functional bisphenol-A novolac epoxy resin;
30-60 parts by weight of a bifunctional epoxy resin;
20-50 parts by weight of a hardener selected from 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone and mixtures thereof;
10-70 parts by weight of a flame retardant;
0-50 parts of a filler;
0-5 parts of a rubber; and
0-5 parts of a Lewis acid wherein the prepreg is capable of being c-staged to a composite having a DMA Tg in excess of 280° C. and a T288 time in excess of 20 minutes.