Multilayer substrate, method for manufacturing multilayer substrate, and electronic device

A multilayer substrate, comprising:

• a multilayer body including a plurality of insulating layers laminated in a first direction, the plurality of insulating layers including a first insulating layer including a first main surface and a second main surface, the first main surface being located above or below the second main surface in the first direction;
• a plurality of inter-layer connection conductors that extend through the first insulating layer in the first direction, and that include a first inter-layer connection conductor and a second inter-layer connection conductor;
• a first conductive layer that is in contact with the first main surface of the first insulating layer, and in contact with the first inter-layer connection conductor and the second inter-layer connection conductor, and that includes a third main surface and a fourth main surface, the third main surface being located above or below the fourth main surface in the first direction, and the first conductive layer having a same composition as the first inter-layer connection conductor and the second inter-layer connection conductor;
• at least one first metal foil layer that is in contact with the third main surface of the first conductive layer, the at least one first metal foil layer overlapping the first inter-layer connection conductor and the second inter-layer connection conductor when viewed in the first direction, the at least one first metal foil layer having a composition different from a composition of the first conductive layer;
• and
• at least one second metal foil layer located above or below the first insulating layer in a second direction, the second direction being opposite to the first direction, the at least one second metal foil layer overlapping the first inter-layer connection conductor and the second inter-layer connection conductor when viewed in the first direction, the at least one second metal foil layer being electrically connected to the first inter-layer connection conductor and the second inter-layer connection conductor, the at least one second metal foil layer having a composition different from a composition of the first conductive layer;
• wherein
• the first conductive layer includes a single conductive layer that is in contact with the first inter-layer connection conductor and the second inter-layer connection conductor.