Wiring board and semiconductor device

1. A wiring board comprising:

a first insulating layer made of a single layer of non-photosensitive resin including a reinforcing member, the first insulating layer including a first surface and a second surface opposite to the first surface, a center position of the reinforcing member being positioned on a side toward the first surface with respect to a center of the first insulating layer in a thickness direction of the first insulating layer;

a layered structure, in which a wiring layer and a second insulating layer are stacked, stacked on the first surface of the first insulating layer;

a through wiring provided to penetrate the first insulating layer, the through wiring including a first end surface and a second end surface opposite to the first end surface, the first end surface of the through wiring being exposed from the first surface of the first insulating layer to be connected to the wiring layer, the through wiring and the first insulating layer forming a first concave portion at the second surface of the first insulating layer, in which the second end surface of the through wiring is exposed at a position concaved from the second surface of the first insulating layer, the second end surface of the through wiring forming a bottom surface of the first concave portion and the first insulating layer forming an inner side surface of the first concave portion; and

a pad for external connection formed on the second surface of the first insulating layer at a position corresponding to the through wiring, the pad for external connection being formed along the bottom surface and the inner side surface of the first concave portion, and extending on the second surface of the first insulating layer around the first concave portion, only the pad for external connection being formed on the second surface of the first insulating layer, the pad for external connection having a second concave portion formed so as to be concaved toward the through wiring within a part of the pad for external connection extended on the second surface of the first insulating layer.

2. The wiring board according to claim 1 , wherein the first surface of the first insulating layer and the first end surface of the through wiring are substantially flush with each other.

3. The wiring board according to claim 1 , wherein the first surface of the first insulating layer and the first end surface of the through wiring are polished surfaces.

4. The wiring board according to claim 1 , wherein the layered structure includes a plurality of the wiring layers and a plurality of the second insulating layers,

the plurality of wiring layers including a first wiring layer directly formed on the first surface of the first insulating layer,

the first wiring layer being bonded to the first end surface of the through wiring, and

the second insulating layers of the layered structure being made of photosensitive resin.

5. The wiring board according to claim 1 ,

wherein the second insulating layer of the layered structure is made of photosensitive resin, and

wherein the wiring layer of the layered structure is a fine wiring layer.

6. The wiring board according to claim 1 , wherein the first surface of the first insulating layer is smoother than the second surface of the first insulating layer.

7. The wiring board according to claim 1 , wherein the center position of the reinforcing member is positioned at center of a combination of the first insulating layer and the layered structure in the thickness direction.

8. The wiring board according to claim 1 , wherein a side surface of the through wiring, the inner side surface of the first concave portion and the second surface of the first insulating layer are roughened surfaces, respectively.

9. The wiring board according to claim 1 , wherein a portion of the second surface of the pad for external connection formed on the second end surface of the through wiring is positioned closer to the first surface of the first insulating layer than a portion of the second surface of the pad for external connection formed on the second surface of the first insulating layer.

10. A semiconductor device comprising:

the wiring board according to claim 1 ;

a semiconductor chip mounted on the layered structure, and connected with an uppermost wiring layer of the layered structure; and

sealing resin, formed on the layered structure, that seals the semiconductor chip.

11. The wiring board according to claim 1 , wherein the first insulating layer is an outermost layer of the wiring board, and the second surface of the first insulating layer is exposed.

12. The wiring board according to claim 1 , wherein the bottom surface of the first concave portion is only formed by the second end surface of the through wiring.

13. The wiring board according to claim 1 , wherein an external shape of the pad for external connection is larger than an external shape of the first concave portion, in a planar view.

14. The wiring board according to claim 1 ,

wherein the through wiring includes

a first metal layer including the first end surface that is exposed from the first surface of the first insulating layer and is connected to the wiring layer, and a third end surface opposite to the first end surface, and

a second metal layer including the second end surface that forms the bottom surface of the first concave portion, and a fourth end surface opposite to the second end surface,

wherein the first metal layer at the first end surface is made larger than the first metal layer at the third end surface, and

wherein the second metal layer at the fourth end surface is made larger than the first metal layer at the third end surface, and the second metal layer at the fourth end surface contacts the first metal layer at the third end surface and the first insulating layer.

15. The wiring board according to claim 14 ,

wherein the first metal layer has a circular shape, and a diameter of the first metal layer at the first end surface is made larger than a diameter of the first metal layer at the third end surface.