Curable dielectric polynorbornene composition and electric circuit boards made therefrom.

A curable dielec. compn. comprises 70-85 wt.% polynorbornene, 15-30 wt.% polymeric diluent that plasticizes the compn., such as EPDM rubber, 50-95 wt.% particulate material having a particle size of 1-250 mm, such as titania, silica, and strontium titanate, 5-10 wt.% curing agent triggered at 120-200 Deg, such as peroxide, and, optionally, at least one auxiliary agent, such as filler, fire retardant, coupling agent, or chain extender. An electronic circuit board comprising a conductive circuit mounted on a substrate that comprises a cured form of the above compn. is also provided. Thus, 100 g mixt. of polynorbornene rubber (Norsorex) and EPDM rubber (Vistalon V 2504) at a ratio of 3:1, 50 g TiO2 (RCL 535), 350 g fused silica (Ranco Sil), and 10 g peroxide (Trigonox 101) were mixed and pressed to receive a compn. having dielec. const. of 3.51. [on SciFinder (R)]