Patent ID: 8703277

Claim:
A curable resin composition comprising a polyphenylene ether, wherein: the average number of phenolic hydroxyl groups per molecule of said polyphenylene ether is 0.3 or more, the resin flow rate of said curable resin composition at curing as measured under the following conditions is from 0.3 to 15%, a sample for dielectric loss tangent measurement produced from said curable resin composition under the following conditions has a dielectric loss tangent at 1 GHz of 0.005 or less, a sample for glass transition temperature measurement produced from said curable resin composition under the following conditions has a glass transition temperature of 170° C. or more, assuming that two 150 mm-square prepreg sheets obtained by impregnating a glass cloth specified by IPC Style 2116 with said curable resin composition to have a resin content of 60±2 mass % are stacked to obtain a laminate sheet precursor and a laminate sheet is produced by molding said laminate sheet precursor under the following condition (a) and removing the resin part flowed out, said resin flow rate at curing is a value calculated from the mass (g) of said laminate sheet and the mass (g) of said laminate sheet precursor according to the following formula: Resin flow rate (%) at curing=(mass (g) of laminate sheet precursor−mass (g) of laminate sheet)/mass (g) of laminate sheet precursor×100, said sample for dielectric loss tangent measurement is molded under the following condition (a) after stacking 16 prepreg sheets obtained by impregnating a glass cloth specified by IPC Style 2116 with the curable resin composition to have a resin content of 60±2 mass %, and said sample for glass transition temperature measurement is molded under the following condition (a) after stacking 2 prepreg sheets obtained by impregnating a glass cloth specified by IPC Style 2116 with the curable resin composition to have a resin content of 60±2 mass %, Condition (a): vacuum pressing is performed under the condition of a pressure of 5 kg/cm 2 while heating at a temperature rise rate of 3° C./min from room temperature; when reached 130° C., vacuum pressing is performed under the condition of a pressure of 30 kg/cm 2 while heating at a temperature rise rate of 3° C./min; and when reached 200° C., vacuum pressing is performed under the conditions of a pressure of 30 kg/cm 2 and a time for 60 minutes while maintaining the temperature at 200° C.