Circuit Board

Provided is a circuit board capable of dissipating heat at a higher efficiency compared with conventional cases from an electronic component mounted at a high density. A circuit board 2 has a first wiring layer 33 and a second wiring layer 34, which are laminated on the front surface 31a side of an aluminum base material 31. The second wiring layer 34 is positioned between the first wiring layer 33 and the base material 31. The first wiring layer 33 is provided with a land 40 having a BGA 30 placed thereon and connected thereto, said BGA being a terminal 30a of a wafer-level chip-size package4. The land 40 is electrically connected to the second wiring layer 34 by means of a via-filling plating 41 formed at a position overlapping the land 40 when viewed from the lamination direction Z. Heat of the wafer-level chip-size package 4 is transmitted to the base material 31 via the land 40, the via-filling plating 41, and the second wiring layer 34, and is dissipated from the base material 31. 提供种电路板，其能以比以往高的效率释放被高密