Wiring substrate, method of trimming same, and multi-layered wiring board

A wiring substrate comprising:

• a device region in which a main wiring pattern composed of a metal layer is embedded in an insulating layer, the main wiring pattern having peaks and valleys provided within the device region;
• a peripheral region which surrounds a periphery of the device region and in which a dummy wiring pattern composed of a metal layer electrically independent of the main wiring pattern is embedded in an insulating layer, the dummy wiring pattern having peaks and valleys provided within the peripheral region, and wherein peaks of the main wiring pattern extend into valleys of the dummy wiring pattern, and peaks of the dummy wiring pattern extend into valleys of the main wiring pattern;
• and
• an insulating boundary region interposed between the device region and the peripheral region, composed of an insulating layer, and free from a metal layer,
• wherein the insulating boundary region has a winding shape in which it is possible to draw a virtual straight line alternately traversing the metal layer constituting the dummy wiring pattern and the insulating layer constituting the insulating boundary region, parallel to an inscribed line of at least one side of an outer edge of the device region, when the wiring substrate is seen in a planar view, wherein the peripheral region is a disposal margin configured to be removed by cutting along the virtual straight line such that the device region remains surrounded by the insulating boundary region, and
• wherein the device region is completely separated from the virtual straight line by the insulating boundary region when the wiring substrate is seen in a planar view.