| 摘要 |
The present invention provides a multilayer printed wiring board having a filled viahole structure advantageously usable for forming a fine circuit pattern thereon, and having an excellent resistance against cracking under a thermal shock or due to heat cycle. The multilayer printed wiring board is comprised of conductor circuitry layers and interlaminar insulative resin layers deposited alternately one on another, the interlaminar insulative resin layers each having formed through them holes each filled with a plating layer to form a viahole. The surface of the plating layer exposed out of the hole for the viahole is formed substantially flat and lies at a substantially same level as the surface of the conductor circuit disposed in the interlaminar insulative resin layer. The thickness of the conductor circuitry layer is less than a half of the viahole diameter and less than 25 mum. The inner wall of the hole formed in the interlaminar insulative resin layer is roughened and an electroless plating layer is deposited on the roughened surface. An electroplating layer is filled in the hole including the electroless plating layer to form the viahole. The interlaminar insulative resin layer is formed from a composite of a fluororesin showing a high fracture toughness and a heat-resistant thermoplastic resin, a composite of fluororesin and thermosetting resin or a composite of thermosetting and thermoplastic resins.
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