WIRING SUBSTRATE

PROBLEM TO BE SOLVED: To provide a wiring substrate which is capable of causing a mounted electronic component to operate normally, being low in generating noise in signals input/output to the electronic component mounted on the wiring substrate. SOLUTION: The wiring substrate is constituted so that, on the upper face of an insulating substrate 1; an electronic component connecting pad 5 for a signal, grounding; and a power supply composed of a part of a wiring conductor layer 2 is formed, and at the same time, on the lower face of the insulating substrate 1, an external connection pad 6 for a signal, grounding, and a power supply electrically connected to the electronic component connection pad 5 via the wiring conductor layer 2 and a through-conductor 4 is formed, wherein one side of the external connection pad 6 for grounding or a power supply is formed, by exposing a part of the wiring conductor 2 insider thereof in an opening A provided in the outer-most insulating layer 1b in the lower side. COPYRIGHT: (C)2010,JPO&INPIT