Multilayered substrate

A multilayered substrate comprising:

• a plurality of laminated insulating layers including a first insulating layer, a second insulating layer, and a third insulating layer;
• and
• a transmission line;
• wherein the first insulating layer includes a first surface and a second surface that are opposite to each other;
• a signal conductor of the transmission line is provided on the first surface of the first insulating layer;
• the second insulating layer is in contact with the first surface of the first insulating layer;
• the third insulating layer is in contact with the second surface of the first insulating layer;
• a dielectric loss of the second insulating layer is lower than a dielectric loss of the third insulating layer;
• a degree of close contact between the first insulating layer and the third insulating layer is higher than a degree of close contact between the first insulating layer and the second insulating layer;
• a material of each of the first insulating layer, the second insulating layer, and the third insulating layer is different from one another;
• a boundary surface between the first insulating layer and the second insulating layer is closer to a center in a lamination direction than is a boundary surface between the first insulating layer and the third insulating layer;
• and
• the third insulating layer is a prepreg layer made of polyimide or liquid crystal polymer.

A multilayered substrate comprising:

• a plurality of laminated insulating layers including a first insulating layer, a second insulating layer, a third insulating layer, a fourth insulating layer, and a fifth insulating layer;
• and
• a transmission line;
• wherein the first insulating layer includes a first surface and a second surface that are opposite to each other;
• a signal conductor of the transmission line is provided on the first surface of the first insulating layer;
• the second insulating layer is in contact with the first surface of the first insulating layer;
• the third insulating layer is in contact with the second surface of the first insulating layer;
• a dielectric loss of the second insulating layer is lower than a dielectric loss of the third insulating layer;
• a degree of close contact between the first insulating layer and the third insulating layer is higher than a degree of close contact between the first insulating layer and the second insulating layer;
• a material of each of the first insulating layer, the second insulating layer, and the third insulating layer is different from one another;
• a boundary surface between the first insulating layer and the second insulating layer is closer to a center in a lamination direction than is a boundary surface between the first insulating layer and the third insulating layer;
• the fourth insulating layer is in contact with a surface of the second insulating layer opposite to a surface with which the first insulating layer is in contact;
• the fifth insulating layer is in contact with a surface of the third insulating layer opposite to a surface with which the first insulating layer is in contact;
• a boundary surface between the second insulating layer and the fourth insulating layer is closer to the center in the lamination direction than is a boundary surface between the first insulating layer and the third insulating layer;
• the degree of close contact between the first insulating layer and the third insulating layer is higher than a degree of close contact between the second insulating layer and the fourth insulating layer;
• and
• the fourth and fifth insulating layers are made of polyimide, modified-polyphenylene ether, or liquid crystal polymer.