| CPC C08J 5/244 (2021.05) [B29B 11/16 (2013.01); C08J 5/18 (2013.01); H05K 1/0366 (2013.01); H05K 1/182 (2013.01); B29K 2101/10 (2013.01); B29K 2105/0094 (2013.01); C08J 2363/00 (2013.01); C08J 2463/00 (2013.01)] | 6 Claims |

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3. A printed wiring board comprising:
a core member including an insulating substrate and a conductor laid on top of the insulating substrate; and
an insulating layer stacked on the core member and covering the conductor,
the insulating layer including: a first layer which is arranged in contact with the core member and is a cured product of a resin sheet; and a second layer which is stacked on the first layer and is a cured product of a prepreg,
the resin sheet comprising an uncured product or semi-cured product of a thermosetting resin composition (X1),
a melt viscosity of the resin sheet being equal to or greater than 10 Pa·s and equal to or less than 2000 Pa·s when measured using a Koka flow tester under a measuring condition including 130° C. and 1 MPa and being equal to or greater than 6 Pa·s and equal to or less than 1200 Pa·s when measured using the Koka flow tester under a measuring condition including 130° C. and 4 MPa,
the prepreg comprising: a base member; and an uncured product or semi-cured product of a thermosetting resin composition (X2) impregnated into the base member,
a melt viscosity of the uncured product or semi-cured product of the thermosetting resin composition (X2) being equal to or greater than 500 Pa·s and equal to or less than 6000 Pa·s when measured using the Koka flow tester under the measuring condition including 130° C. and 4 MPa.
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