Multilayer substrate and a manufacturing method of the multilayer substrate

A multilayer substrate comprising:

• an element assembly including a first insulating layer, a second insulating layer, and a third insulating layer, stacked in layers such that the second insulating layer, the third insulating layer, and the first insulating layer are arranged in this order from a first side to a second side with respect to a layer stacking direction;
• a first conductor layer disposed on a first principal surface of the first insulating layer and including a plated layer, the first principal surface being on the first side of the first insulating layer with respect to the layer stacking direction;
• and
• a second conductor layer disposed on a second principal surface of the second insulating layer, the second principal surface being on the second side of the second insulating layer with respect to the layer stacking direction;
• wherein
• the first conductor layer includes a first connection portion and a first circuit portion which defines a signal transmission path;
• the second conductor layer includes a second connection portion and a second circuit portion which defines a signal transmission path;
• the first connection portion and the second connection portion are connected to each other;
• when viewed from the layer stacking direction, the first circuit portion includes an overlapping portion which overlaps the second circuit portion;
• a portion of the first connection portion which is connected to the second connection portion has a maximum thickness greater than a maximum thickness of the overlapping portion;
• and
• the plated layer in the portion of the first connection portion which is connected to the second connection portion has a maximum thickness greater than a maximum thickness of the plated layer in the overlapping portion.

A method for manufacturing multilayer substrates, each of the multilayer substrates including an element assembly including a first insulating layer and a second insulating layer, stacked in layers such that the second insulating layer and the first insulating layer are arranged in this order from a first side to a second side with respect to a layer stacking direction;

• a first conductor layer disposed on a first principal surface of the first insulating layer and including a plated layer, the first principal surface being on the first side of the first insulating layer with respect to the layer stacking direction;
• and a second conductor layer disposed on a first principal surface of the second insulating layer, the first principal surface being on the first side of the second insulating layer with respect to the layer stacking direction;
• wherein the first conductor layer includes a first connection portion and a first circuit portion which defines a signal transmission path;
• and the second conductor layer includes a second connection portion and a second circuit portion which defines a signal transmission path;
• the method comprising:
• forming a plurality of first conductor layers for the multilayer substrates on a first principal surface of a first mother insulating layer by a process including electroplating, the first principal surface being on the first side of the first mother insulating layer with respect to the layer stacking direction;
• forming a plurality of second conductor layers for the multilayer substrates on a first principal surface of a second mother insulating layer, the first principal surface being on the first side of the second mother insulating layer with respect to the layer stacking direction;
• forming a plurality of interlayer connection portions to connect the first connection portions of the respective first conductor layers and the second connection portions of the respective second conductor layers;
• forming a mother element assembly by stacking the first mother insulating layer and the second mother insulating layer in layers such that the second mother insulating layer and the first mother insulating layer are arranged in this order from the first side to the second side with respect to the layer stacking direction;
• and
• cutting the mother element assembly into a plurality of element assemblies;
• wherein
• in the forming the plurality of first conductor layers, the plurality of first conductor layers are formed such that, when viewed from the layer stacking direction, an outer edge of the first mother insulating layer is at a shorter distance from the first connection portions of the respective first conductor layers than from the first circuit portions of the respective first conductor layers.

A method for manufacturing multilayer substrates, each of the multilayer substrates including an element assembly including a first insulating layer, a second insulating layer and a third insulating layer, stacked in layers such that the second insulating layer, the third insulating layer, and the first insulating layer are arranged in this order from a first side to a second side with respect to a layer stacking direction;

• a first conductor layer disposed on a first principal surface of the first insulating layer and including a plated layer, the first principal surface being on the first side of the first insulating layer with respect to the layer stacking direction;
• and a second conductor layer disposed on a second principal surface of the second insulating layer, the second principal surface being on the second side of the second insulating layer with respect to the layer stacking direction;
• wherein the first conductor layer includes a first connection portion and a first circuit portion which defines a signal transmission path;
• the second conductor layer includes a second connection portion and a second circuit portion which defines a signal transmission path;
• the method comprising:
• forming a plurality of first conductor layers for the multilayer substrates on a first principal surface of a first mother insulating layer by a process including plating, the first principal surface being on the first side of the first mother insulating layer with respect to the layer stacking direction;
• forming a plurality of second conductor layers for the multilayer substrates on a second principal surface of a second mother insulating layer, the second principal surface being on the second side of the second mother insulating layer with respect to the layer stacking direction;
• forming a mother element assembly by stacking the second mother insulating layer, the third mother insulating layer, and the first mother insulating layer in layers in this order such that the first connection portions of the respective first conductor layers are connected to the second connection portions of the respective second conductor layers;
• and
• cutting the mother element assembly into a plurality of element assemblies;
• wherein
• in the forming the plurality of first conductor layers, the plurality of first conductor layers are formed such that, when viewed from the layer stacking direction, an outer edge of the first mother insulating layer is shorter distance from the first connection portions of the respective first conductor layers than from the first circuit portions of the respective first conductor layers.