A printed wiring board includes a core substrate having a cavity, multiple electronic components accommodated in the cavity, and a build-up layer formed on the substrate and including an insulating interlayer such that the interlayer is covering the cavity. The components include a first component, second component and third component, the core substrate has a first projection structure partitioning the first and second components in the cavity and a second projection structure partitioning the second and third components in the cavity, and the cavity and the first and second structures are formed in the substrate such that T1