Wiring substrate, semiconductor device, and method of manufacturing the wiring substrate

1 . A wiring substrate comprising:

a first insulating layer that is formed of a non-photosensitive thermosetting resin as a main component and is a single layer;

a first wiring layer that is provided on the first insulating layer; and

a thin film layer that is provided on one of surfaces of the first insulating layer and that includes a plurality of second wiring layers and a plurality of second insulating layers that is different from the first insulating layer and is formed of a photosensitive thermosetting resin as a main component, in which the plurality of second wiring layers and the plurality of second insulating layers are sequentially laminated, wherein

the thin film layer includes

a first pad and a second pad that are provided on an opposite surface of a surface that faces the first insulating layer,

a first via that is electrically connected to the first pad, and

a second via that is electrically connected to the second pad, the first wiring layer includes

a first conductive layer that is formed on a lower surface of the first insulating layer and is covered by the first insulating layer, and

a second conductive layer that is formed on an upper surface of the first insulating layer and is covered by one of the plurality of second insulating layers, the first conductive layer being thicker than the second conductive layer and the plurality of the second wiring layers,

the first insulating layer includes a third via that electrically connects the first conductive layer and the second conductive layer and has an inverted truncated cone shape that tapers in diameter from the upper surface to the lower surface of the first insulating layer,

the first wiring layer includes a transmission wiring that electrically connects between the first via and the second via, and

a dielectric loss tangent of the first insulating layer that includes the transmission wiring is smaller than a dielectric loss tangent of the plurality of second insulating layers that are included in the thin film layer.

2 . The wiring substrate according to claim 1 , wherein a wiring thickness of the first conductive layer in the first wiring layer is within a range of 10 to 20 μm, and

a wiring thickness of each of the second conductive layer in the first wiring layer and the plurality of second wiring layers is within a range of 1 to 3 μm.

3 . The wiring substrate according to claim 1 , wherein the transmission wiring is a wiring that transmits a high-speed serial signal between the first via and the second via.

4 . The wiring substrate according to claim 1 , wherein

the thin film layer includes a third conductive layer that is formed on a surface located at a side opposite to the surface that faces the first insulating layer,

and

the thin film layer includes the first via and the second via that electrically connect the second conductive layer and the third conductive layer.

5 . The wiring substrate according to claim 1 , wherein the transmission wiring is formed in the first conductive layer.

6 . The wiring substrate according to claim 1 , wherein the dielectric loss tangent of the first insulating layer is within a range of 0.0004 to 0.02.

7 . The wiring substrate according to claim 1 , wherein the first wiring layer is thicker than the second wiring layer so as to reduce a wiring resistance of the transmission wiring so that it is possible to suppress an insertion loss and a reflection loss occurring when a high-speed signal passes through the transmission wiring.

8 . A semiconductor device comprising:

a wiring substrate on which a first electronic component and a second electronic component are mounted; and

a multi-layer wiring substrate on which the wiring substrate is mounted, wherein

the wiring substrate includes

a first insulating layer that is formed of a non-photosensitive thermosetting resin as a main component and is a single layer,

a first wiring layer that is provided on the first insulating layer, and

a thin film layer that is provided on one of surfaces of the first insulating layer and that includes a plurality of second wiring layers and a plurality of second insulating layers that is different from the first insulating layer and is formed of a photosensitive thermosetting resin as a main component, in which the plurality of second wiring layers and the plurality of second insulating layers are sequentially laminated,

the thin film layer includes

a first pad and a second pad that are provided on an opposite surface of a surface that faces the first insulating layer,

a first via that is electrically connected to the first pad that is connected to the first electronic component, and

a second via that is electrically connected to the second pad that is connected to the second electronic component,

the first wiring layer includes

a first conductive layer that is formed on a lower surface of the first insulating layer and is covered by the first insulating layer, and

a second conductive layer that is formed on an upper surface of the first insulating layer and is covered by the plurality of second insulating layers, the first conductive layer being thicker than the second conductive layer and the plurality of the second wiring layers,

the first insulating layer includes a third via that electrically connects the first conductive layer and the second conductive layer and has an inverted truncated cone shape that tapers in diameter from the upper surface to the lower surface of the first insulating layer,

the first wiring layer includes a transmission wiring that electrically connects between the first via and the second via, and

a dielectric loss tangent of the first insulating layer that includes the transmission wiring is smaller than a dielectric loss tangent of the plurality of second insulating layers that are included in the thin film layer.