Abstract: The present invention relates to a composite, a high-frequency circuit substrate prepared therefrom and a process for preparing the same. Such composite includes (1) from 20 to 70 parts by weight of a thermosetting mixture, including (A) a thermosetting resin based on polybutadiene or a copolymer resin of polybutadiene and styrene having a molecular weight of 11,000 or less, being composed of carbon and hydrogen elements and containing 60% or more of vinyl groups, and (B) an ethylene-propylene rubber having a weight-average molecular weight of greater than 100,000 and less than 150,000 and a number-average molecular weight of greater than 60,000 and less than 100,000 and being in a solid state at room temperature; (2) from 10 to 60 parts by weight of a glass fiber cloth; (3) from 0 to 70 parts by weight of a powder filler; and (4) from 1 to 3 parts by weight of a curing initiator. The composite of the present invention has good solvent solubility and good process operability.

Abstract: The present invention relates to a composite, a high-frequency circuit substrate prepared therefrom and a process for preparing the same. Such composite comprises (1) from 20 to 70 parts by weight of a thermosetting mixture, comprising (A) a thermosetting resin based on polybutadiene or a copolymer resin of polybutadiene and styrene having a molecular weight of 11,000 or less, being composed of carbon and hydrogen elements and containing 60% or more of vinyl groups, and (B) an ethylene-propylene rubber having a weight-average molecular weight of greater than 100,000 and less than 150,000 and a number-average molecular weight of greater than 60,000 and less than 100,000 and being in a solid state at room temperature; (2) from 10 to 60 parts by weight of a glass fiber cloth; (3) from 0 to 70 parts by weight of a powder filler; and (4) from 1 to 3 parts by weight of a curing initiator. The composite of the present invention has good solvent solubility and good process operability.