Miniaturization and high functionality of electric equipment has been achieved as well as miniaturization of electronic components incorporated in equipment. Even for a printed wiring board for mounting electric components, higher density, multilayer, multi-layering, and enhancement of high-speed transmission characteristics are required. As a technology to meet these requirements, there is a packaging technology called EWLP (Embedded Wafer Level Package).
EWLP is a technology for mounting semiconductor components (electric component) such as a WLCSP (Wafer Level Chip Size Package) to a printed wiring board. According to EWLP, it is possible to improve the packaging density, reduce the wiring length between the semiconductor elements, and enhance the high-speed transmission characteristics.
A component-embedded board is known in which a single-sided wiring board is laminated on both sides of a double-sided wiring board in which an electric component is embedded (see Patent Document 1).
FIG. 13 is an example of a component-embedded board. The component-embedded board 100 includes a double-sided wiring board A102 in which a conductive layer 4 is formed on both faces of an insulation resin layer 3, and single-sided wiring boards A101 and A103 each in which the conductive layer 4 is formed on the outer side of the insulation resin layer 3. The single-sided wiring boards A101 and A103 are laminated on one and the other faces of the double-sided wiring board A102. An electric component 2 is embedded in an opening portion 6 formed in the insulation resin layer 3 of the double-sided wiring board A102.
The wiring boards A101-A103 are adhered together with an adhesion layer 5 and electrically connected to each other through an interlayer conductive portion 1.
FIG. 14 and FIG. 15 show a process of forming the opening portion 6 in the insulation resin layer 3 of the double-sided wiring board A102. As shown in the figures, the opening portion 6 is formed in the insulation resin layer 3 of a plurality of the double-sided wiring board A102 before the dicing by laser processing or drill processing, for example.
FIGS. 16A and 16B are a plan view showing the insulation resin layer 3 of the double-sided wiring board A102 in the process of forming the opening portion 6. By removing off by laser processing or drill processing the area 6a shown by a two-dot chain line in FIG. 16A, the opening portion 6 shown in FIG. 16B can be formed.