| 摘要 |
PURPOSE:To obtain excellent resistance to flexure fatigue, dimensional stability to heat and electrical resistance, by impregnating specific glass cloth with thermosetting resin. CONSTITUTION:It is necessary that a glass fiber composed of a monofilament whose mean diameter falls within a range of 2.0-4.8mum is used at least for either of warp or weft, in glass cloth. In case where a mean diameter of the monofilament is less than 2.0mum, impregnation properties of resin varnish among the filaments are apt to become insufficient at the time of manufacturing of those prepregs and it becomes difficult to produce stably as a long fiber. On the one hand, in case where the mean diameter of the monofilament exceeds 4.8mum, sufficient resistance to flexure fatigue cannot be afforded. Then it is necessary to make a ratio (warp/weft) of weaving density of the warp of the glass cloth to that of the weft of the glass cloth fall within a range of 0.95-1.35. Although a thermosetting resin composition to be used is selected according to capacity of a circuit board to be required, epoxy resin or polyimide resin is suitable.
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