An aramid/epoxy substrates increased the facility of rigid-flexible substrates for high performance use

A material has been developed for fabricating rigid-flexible printed boards. The material includes copper-clad laminates (TL-01) and prepregs (ET-100) consisting of a recently developed aramid paper made of an aramid fiber from poly-paraphenylene 3,4' diphenilether terephthalamid (PPDETA) as a reinforcement, and a sophisticated epoxy resin system having high affinity to an aramid fiber as an impregnant. The dimensional stability of the multilayer system has been shown to surpass that of the conventional lamination system of FR-4, polyimide films, and acrylic adhesives. A flexural fatigue test on the flexible printed wiring has been carried out, and the flexible material revealed a higher flexibility than FR-4. Copper migration has been observed after full absorption of moisture by a pressure cooker test (PCT). TL-01 has shown an excellent resistance to migration for more than 50 h, while polyimide film with an acrylic adhesive has shown a heavy migration. It is concluded that this material may be useful for advanced rigid-flex multilayer printed boards suitable for surface mount technologies.<
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