Circuit board and method of manufacturing the same

1. A circuit board comprising:

a core layer comprising a first surface and a second surface opposite to the first surface;

a first build-up layer and a second build-up layer formed on the first surface and the second surface of the core layer, respectively, and comprising a conductive pattern and a conductive via; and

an outer layer formed on a surface of the first build-up layer or a surface of the second build-up layer,

wherein at least one build-up layer of the first build-up layer and the second build-up layer comprises a photosensitive insulating layer in which a cavity is disposed and a thermal dissipation unit is disposed in the cavity,

wherein the outer layer has a pad formed thereon, the pad being connected with an electronic component, and

wherein the pad is connected with the thermal dissipation unit through a heat dissipation via.

2. The circuit board of claim 1 , wherein a conductive material of the thermal dissipation unit is the same as a conductive material of a conductive via formed in the photosensitive insulating layer.

3. The circuit board of claim of claim 2 , wherein the conductive material comprises a metal seed layer formed on an inner surface of the cavity and a plating layer formed on the metal seed layer.

4. The circuit board of claim 1 , wherein the first build-up layer and the second build-up layer each comprises a plurality of build-up layers.

5. The circuit board of claim 4 , wherein the plurality of build-up layers of the first build-up layer, and the plurality of build-up layers of the second build-up layer and the core layer together comprises the heat dissipation via directly or indirectly connected to the thermal dissipation unit.

6. The circuit board of claim 4 , wherein at least one build-up layer among the first build-up layer and the second build-up layer comprises two or more build-up layers which are adjacent to each other and thermal dissipation units are formed in the two or more build-up layers which are adjacent to each other and are laminated to be overlapped in a laminated direction of the build-up layers.

7. The circuit board of claim 4 , wherein each of the first build-up layer and the second build-up layer comprises at least one build-up layer in which the thermal dissipation unit is formed.

8. The circuit board of claim 7 , wherein thermal dissipation units formed in the at least one build-up layer in each of the first build-up layer and the second buildup layer are laminated to be overlapped in a laminated direction of the build-up layer.

9. The circuit board of claim 7 , wherein the at least one build-up layer in each of the first build-up layer and the second build-up layer is formed in a different number of layers.

10. The circuit board of claim 1 wherein the thermal dissipation unit comprises a plurality of thermal dissipation units arranged asymmetrically with respect to the core layer.

11. The circuit board of claim 1 , wherein a conductor volume fraction of each of the first build-up layer and the second build-up layer are different from each other,

wherein the conductor volume fraction comprises a ratio of volume occupied by the conductive pattern and the conductive via, excluding the thermal dissipation unit, to the entire volume of the first build-up layer and the second build-up layer, and

wherein the thermal dissipation unit is arranged asymmetrically with respect to the core layer to reduce the difference of the conductor volume fractions of the first build-up layer and the second build-up layer.