Printed wiring board

A printed wiring board, comprising:

• a base substrate;
• an electronic component accommodated in a cavity formed in the base substrate;
• a resin insulating layer formed on the base substrate such that the resin insulating layer is covering the electronic component;
• a conductor layer formed on the resin insulating layer;
• and
• a plurality of via conductors formed in the resin insulating layer and each comprising a seed layer and an electrolytic plating layer formed on the seed layer such that the via conductors are connecting the conductor layer and a plurality of electrodes of the electronic component,
• wherein the resin insulating layer includes resin and inorganic particles comprising at least one of silica and alumina and has a plurality of via holes in which the plurality of via conductors is formed respectively such that the inorganic particles include first inorganic particles having smooth surfaces and second inorganic particles embedded in the resin insulating layer and that an inner wall surface of each of the via holes includes the resin and the smooth surfaces of the first inorganic particles, and the plurality of via conductors is formed such that the seed layer is a sputtering film comprising a first layer formed in contact with the inner wall surface of each of the via holes and a second layer formed on the first layer, that the first layer comprises a copper alloy comprising copper, silicon and aluminum and that second layer comprises copper.