Electronic component built-in wiring substrate

An electronic component built-in wiring substrate comprising:

• a first wiring substrate having a first surface and a second surface opposite to the first surface;
• an electronic component, which is mounted on the first surface of the first wiring substrate and is connected to the first wiring substrate by flip-chip bonding;
• an external connection terminal formed on the second surface of the first wiring substrate;
• a second wiring substrate, which is stacked on the first wiring substrate and is connected electrically to the first wiring substrate by connection terminals, the second wiring substrate having an opening portion in a portion, which faces the electronic component, of the second wiring substrate, the opening portion having a size larger than a planar area of the electronic component, and
• a first resin including an underfill resin portion and a raised portion, the underfill resin portion being filled in a first space between the first wiring substrate and the electronic component, the raised portion being raised along an outer peripheral side surface of the electronic component, sealing a clearance between an inner peripheral edge of the opening portion and an outer peripheral edge of the electronic component and supporting the second wiring substrate, wherein the raised portion of the first resin directly contacts the outer peripheral side surface of the electronic component and the inner peripheral edge of the opening portion;
• and
• a second resin which is filled in a second space between the first and second wiring substrates.