| 摘要 |
An intermediate material which is adapted to manufacture a circuit board includes a prepreg sheet having a through-hole provided therein, a first film provided on a surface of the prepreg sheet and having a first hole communicating with the through-hole, a second film provided on another surface of the prepreg sheet and having a second hole communicating with the through-hole, and a conductive paste filling the though-hole, the first hole, and the second hole. The thickness t1 of the prepreg sheet, the minimum diameter rmin of the through-hole, the thickness tf1 of the first film, the diameter rf1 of the first hole, the thickness tf2 of the second film, the diameter rf2 of the second hole satisfy a relation: rf1/tf1≧3, rf2/tf2≧3, and rmin/(t1+tf1+tf2)≰1.5. This intermediate material provides a circuit board having a fine via-conductor connected to a metal foil securely and stably.
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