A circuit structure includes a first busbar constituted by a cladding material, a second busbar, an insulating member including an insulating portion located between the first busbar and the second busbar, and an electronic component provided on the first busbar and the second busbar so as to straddle the insulating portion. The electronic component has a connection terminal bonded to the first busbar.

A metal base substrate of the present invention is a metal base substrate including a metal substrate, an insulating layer laminated on one surface of the metal substrate, and a circuit layer laminated on a surface of the insulating layer opposite to the metal substrate side, in which the circuit layer is made of a metal having a semi-softening temperature of 100° C. or higher and 150° C. or lower, the insulating layer contains a resin, and a relationship between a thickness t (μm) of the insulating layer and an elastic modulus E (GPa) of the insulating layer at 100° C. satisfies a following formula (1).

10<t/E  (1)

A metal base substrate of the present invention includes a metal substrate, an insulating layer, and a circuit layer, which are laminated in this order, in which the insulating layer contains an insulating resin and an inorganic filler, and an elastic modulus (unit: GPa) at 100° C. of the insulating layer, an elastic modulus (unit: GPa) at 100° C. of the circuit layer, a thickness (unit: μm) of the insulating layer, a thickness (unit: μm) of the circuit layer, and a thickness (unit: μm) of the metal substrate are set so as to satisfy predetermined formulae.

A method for manufacturing a circuit board embeds a portion of an outer circuit layer in an outer dielectric layer which increases contact area between the outer circuit layer and the outer dielectric layer, improving adhesion between the outer circuit layer and the outer dielectric layer, and reducing a thickness of the outer circuit substrate, thereby reducing the overall thickness of the finished circuit board.

A copper base substrate of the present invention, in which a copper substrate, an insulating layer, and a circuit layer, are laminated in an order in the copper substrate, a ratio of a thickness (unit: .Math.m) to an elastic modulus (unit: GPa) at 100° C. is 50 or more in the insulating layer, and the circuit layer has an elastic modulus at 100° C. of 100 GPa or less.

A suspension board with circuit including a first mounting region for mounting a slider and a second mounting region for mounting a piezoelectric element. The wiring circuit board includes a metal support layer, a base insulating layer, and a conductive layer. The conductive layer includes a first wiring pattern, a second wiring pattern, and a shield wiring pattern. The first wiring pattern includes a read wiring. The second wiring pattern includes a power supply wiring disposed at spaced intervals to the read wiring. The shield wiring pattern includes a shield wiring disposed between the read wiring and the power supply wiring.

Provided is a wiring circuit board that includes a first insulating layer, a conductive pattern disposed on the first insulating layer, a second insulating layer disposed on the first insulating layer and covering the conductive pattern, and a third protective layer disposed between the conductive pattern and the second insulating layer and protecting the conductive pattern. The third protective layer consists of a metal oxide.

Provided is a wiring circuit board that includes a first insulating layer, a conductive pattern disposed on the first insulating layer, and a second protective layer disposed between the first insulating layer and protecting the conductive pattern. The second protective layer consists of a metal oxide.

A circuit board includes a first metal layer; a second metal layer that is arranged on the first metal layer; and a sealing resin with which a space between the first metal layer and the second metal layer is filled, wherein the second metal layer includes an electrode that protrudes from an upper surface of the sealing resin and that has an end face on which an electronic part is mountable; and an interlayer connector whose upper surface is exposed in a position lower than the end face of the electrode from the upper surface of the sealing resin and that makes contact with the first metal layer.

A circuit part is provided that provides both high heat dissipation and high adhesion of its circuit wiring. A circuit part includes: a metal member; an insulating resin layer located on the metal member; circuit wiring including a plating film located on the insulating resin layer; and a mounted component mounted on the circuit wiring and electrically connected to the circuit wiring, wherein a plurality of non-penetrating holes are provided in a wiring region, the non-penetrating holes being filled with the plating film, the wiring region being a portion of the resin-layer surface on which the circuit wiring is located, and the ratio of the depth d of the non-penetrating holes to the width D of the non-penetrating holes, d/D, is 0.5 to 5.