there is disclosed a novel mixture of polyhydroxy phenolic curing agents , such as novolac resins blended with a mixture of mono , bis and tris hydroxyaryl phosphine oxides for co - curing epoxy resins and imparting flame resistance thereto . a preferred composition includes a mixture of monohydroxyaryl , bishydroxyaryl and trishydroxyaryl phosphine oxide and a benzoguanamine / phenol / formaldehyde terpolymer which is used along with an epoxy resin to produce flame - resistant printed wiring boards without the use of halogens .