Abstract: In a multilayer substrate, one of a first reference conductor layer and a second reference conductor layer overlapping an eleventh interlayer connection conductor includes a first opening overlapping a signal conductor layer when viewed in a Z-axis direction. When viewed in the Z-axis direction, the first opening is positioned in a negative direction of an X axis relative to a vicinity of a first reference straight line connecting a second interlayer connection conductor and a fifth interlayer connection conductor. When viewed in the Z-axis direction, the first opening is positioned in a positive direction of the X axis relative to the eleventh interlayer connection conductor.

Abstract: In a circuit module, a first signal electrode is electrically connected to a first signal conductor layer. A first branch electrode is electrically connected to a first branch conductor layer. A second signal electrode is electrically connected to a second signal conductor layer and is bonded to the first signal electrode by using a conductive bonding material. A second branch electrode is electrically connected to a second ground conductor layer and is bonded to the first branch electrode by using a conductive bonding material.

Abstract: A multilayer substrate includes a resin multilayer body including, in a lamination direction, first and second laminate portions respectively including first and second thermoplastic resin layers, and a first interlayer connection conductor extending through the first thermoplastic resin layer. A storage elastic modulus of the first thermoplastic resin layer is lower than that of the second thermoplastic resin layer at a measurement temperature equal to or higher than a minimum melting point among melting points of metallic elements included in the first interlayer connection conductors and equal to or lower than melting points of the first thermoplastic resin layer and the second thermoplastic resin layer.

Abstract: A multilayer substrate includes a resin multilayer body including, in a lamination direction, first and second laminate portions respectively including first and second thermoplastic resin layers, and a first interlayer connection conductor extending through the first thermoplastic resin layer. A storage elastic modulus of the first thermoplastic resin layer is lower than that of the second thermoplastic resin layer at a measurement temperature equal to or higher than a minimum melting point among melting points of metallic elements included in the first interlayer connection conductors and equal to or lower than melting points of the first thermoplastic resin layer and the second thermoplastic resin layer.

Abstract: A transmission line includes an element body and a signal conductor layer in the element body and having a linear shape. The transmission line includes a first, second, and third impedance sections, an impedance conversion section, and a reflection section. The second impedance section, the reflection section, the first impedance section, the impedance conversion section, and the third impedance section are positioned in this order along the signal conductor layer. Characteristic impedance of the first impedance section is lower than characteristic impedance in the second impedance section and characteristic impedance in the third impedance section. A change amount of characteristic impedance per unit length in the reflection section is larger than a change amount of characteristic impedance per unit length in the impedance conversion section.