TECHNICAL FIELD

The present invention relates to a solid electrolytic capacitor and a method for manufacturing the solid electrolytic capacitor.

BACKGROUND

In general a solid electrolytic capacitor includes a valve action metal base including a porous layer on a surface of a base composed of a valve action metal such as aluminum, a dielectric layer that is formed on a surface of the porous layer, a solid electrolyte layer that is disposed on the dielectric layer, and a capacitor element that includes a conductor layer that is disposed on the solid electrolyte layer.

As disclosed in Patent Document 1 (identified below), an existing method of resin sealing is performed in a manner in which capacitor elements are stacked, the stacked capacitor elements are electrically connected to a lead frame, and transfer molding or another method is subsequently performed. In some cases, the capacitor elements are electrically connected to a mounting substrate such as a printed circuit board instead of the lead frame before resin sealing.

Patent Document 2 (also identified below) discloses a solid electrolytic capacitor that includes a capacitor element that has an anode and a cathode, and a substrate on which the capacitor element is mounted. In the solid electrolytic capacitor disclosed in Patent Document 2, an anode pattern that is connected to the anode and a cathode pattern that is connected to the cathode are formed on a capacitor-element-mounting surface of the substrate, and pairs of anode terminals and cathode terminals are formed on a back surface of the substrate opposite the capacitor-element-mounting surface. The anode terminals are connected to the anode of the capacitor element with a conduction path that is formed in the substrate and the anode pattern that is formed on the capacitor-element-mounting surface interposed therebetween. Moreover, the cathode terminals are connected to the cathode of the capacitor element with a conduction path that is formed in the substrate and the cathode pattern that is formed on the capacitor-element-mounting surface interposed therebetween.

For this reason, the solid electrolytic capacitor disclosed in Patent Document 2 functions as a solid electrolytic capacitor that includes pairs of terminals when the solid electrolytic capacitor is mounted on the mounting substrate from the back surface, and a predetermined voltage is applied to the pairs of the anode terminals and the cathode terminals that are formed on the back surface. That is, the solid electrolytic capacitor disclosed in Patent Document 2 is a solid electrolytic capacitor that includes pairs of terminals in which a two-terminal capacitor element is used.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-135427.

Patent Document 2: Japanese Unexamined Patent Application Publication No. 2007-266247.

In the solid electrolytic capacitor, a capacitance generation portion, which is conducive to electrostatic capacity, is a porous portion such as an etching layer in which a dielectric layer is formed. It is effective to decrease the distance from the capacitance generation portion to an outer electrode such as the lead frame from which an electric current flows, in order to decrease an equivalent series resistance (ESR), and an equivalent series inductance (ESL).

However, an existing structure in Patent Document 1 where a terminal extends from the capacitor element to an outer electrode in a plane direction is disadvantageous to a design for decreasing the ESR and the ESL because the distance to the outer electrode is long. With the existing structure, it is difficult to achieve a design for increasing a ratio of the volume of the capacitance generation portion to the volume of the entire capacitor. With the structure disclosed in Patent Document 1, it is thus difficult to design a thin solid electrolytic capacitor having a low ESR and a low ESL.

In addition, in the solid electrolytic capacitor in Patent Document 2, in which the capacitor element is mounted on the mounting surface of the substrate and the anode terminals and the cathode terminals that are formed on the back surface of the substrate are outer electrodes, the substrate is interposed. Accordingly, it is difficult to design a thin solid electrolytic capacitor having a low ESR and a low ESL.

SUMMARY OF THE INVENTION

The exemplary embodiments of the present invention solve the above-noted problems of the prior art. Accordingly, it is an object of the present invention to provide a solid electrolytic capacitor that has a low ESR and a low ESL and that can be designed to be thin, and to provide a method for manufacturing the solid electrolytic capacitor.

In a first exemplary aspect, a solid electrolytic capacitor is provided that includes a capacitor element that includes a valve action metal base including a porous portion at least on a first main surface of a core portion, a dielectric layer that is disposed on a surface of the porous portion, a solid electrolyte layer that is disposed on the dielectric layer, and a conductor layer that is disposed on the solid electrolyte layer. Moreover, the capacitor includes a sealing layer that seals a first main surface of the capacitor element, a cathode outer electrode that is electrically connected to the conductor layer, and an anode outer electrode that is electrically connected to the valve action metal base. The conductor layer contains metal foil. The sealing layer and the cathode outer electrode are disposed in this order on the conductor layer. A cathode through-electrode that extends through the sealing layer is disposed in the sealing layer on the conductor layer. The conductor layer and the cathode outer electrode are connected to each other with the cathode through-electrode interposed therebetween.

A solid electrolytic capacitor according to a second aspect includes a capacitor element that includes a valve action metal base including a porous portion at least on a first main surface of a core portion, a dielectric layer that is disposed on a surface of the porous portion, a solid electrolyte layer that is disposed on the dielectric layer, and a conductor layer that is disposed on the solid electrolyte layer, with the capacitor element including an exposed portion of the core portion along the first main surface of the valve action metal base. Moreover, the capacitor includes an insulating layer that is disposed on the exposed portion of the core portion of the capacitor element, a first sealing layer that is disposed on the insulating layer and the conductor layer of the capacitor element such that the first sealing layer covers the first main surface of the capacitor element, a first anode through-electrode that is disposed in the first sealing layer and the insulating layer such that the first anode through-electrode extends through the first sealing layer and the insulating layer on the exposed portion of the core portion of the capacitor element, and that is connected to the core portion of the capacitor element, a first cathode through-electrode that is disposed in the first sealing layer such that the first cathode through-electrode extends through the first sealing layer on the conductor layer of the capacitor element and that is connected to the conductor layer of the capacitor element, a first anode inner electrode that is disposed on the first sealing layer and that is connected to the first anode through-electrode that is exposed from a surface of the first sealing layer, a first cathode inner electrode that is disposed on the first sealing layer and that is connected to the first cathode through-electrode that is exposed from the surface of the first sealing layer, a second sealing layer that is directly or indirectly disposed above the first sealing layer such that the second sealing layer covers the first anode inner electrode and the first cathode inner electrode, a second anode through-electrode that is disposed in the second sealing layer such that the second anode through-electrode extends through the second sealing layer and that is directly or indirectly connected to the first anode inner electrode, a second cathode through-electrode that is disposed in the second sealing layer such that the second cathode through-electrode extends through the second sealing layer and that is directly or indirectly connected to the first cathode inner electrode, an anode outer electrode that is disposed on the second sealing layer and that is connected to the second anode through-electrode that is exposed from a surface of the second sealing layer, and a cathode outer electrode that is disposed on the second sealing layer and that is connected to the second cathode through-electrode that is exposed from the surface of the second sealing layer.

A solid electrolytic capacitor according to a third aspect includes a capacitor element that includes a valve action metal base including a porous portion at least on a first main surface of a core portion, a dielectric layer that is disposed on a surface of the porous portion, a solid electrolyte layer that is disposed on the dielectric layer, and a conductor layer that is disposed on the solid electrolyte layer, with the capacitor element including an exposed portion of the core portion along the first main surface of the valve action metal base. Moreover, the capacitor includes a first sealing layer that is disposed on the conductor layer and the exposed portion of the core portion of the capacitor element such that the first sealing layer covers the first main surface of the capacitor element, a first anode through-electrode that is disposed in the first sealing layer such that the first anode through-electrode extends through the first sealing layer on the exposed portion of the core portion of the capacitor element and that is connected to the core portion of the capacitor element, a first cathode through-electrode that is disposed in the first sealing layer such that the first cathode through-electrode extends through the first sealing layer on the conductor layer of the capacitor element and that is connected to the conductor layer of the capacitor element, a first anode inner electrode that is disposed on the first sealing layer and that is connected to the first anode through-electrode that is exposed from a surface of the first sealing layer, a first cathode inner electrode that is disposed on the first sealing layer and that is connected to the first cathode through-electrode that is exposed from the surface of the first sealing layer, a second sealing layer that is directly or indirectly disposed above the first sealing layer such that the second sealing layer covers the first anode inner electrode and the first cathode inner electrode, a second anode through-electrode that is disposed in the second sealing layer such that the second anode through-electrode extends through the second sealing layer and that is directly or indirectly connected to the first anode inner electrode, a second cathode through-electrode that is disposed in the second sealing layer such that the second cathode through-electrode extends through the second sealing layer and that is directly or indirectly connected to the first cathode inner electrode, an anode outer electrode that is disposed on the second sealing layer and that is connected to the second anode through-electrode that is exposed from a surface of the second sealing layer, and a cathode outer electrode that is disposed on the second sealing layer and that is connected to the second cathode through-electrode that is exposed from the surface of the second sealing layer.

A method according to an exemplary aspect is provided for manufacturing a solid electrolytic capacitor and includes a step of preparing a capacitor element that includes a valve action metal base including a porous portion at least on a first main surface of a core portion, a dielectric layer that is disposed on a surface of the porous portion, a solid electrolyte layer that is disposed on the dielectric layer, and a conductor layer that is disposed on the solid electrolyte layer, with the capacitor element including an exposed portion of the core portion along the first main surface of the valve action metal base with an insulating layer formed on the exposed portion of the core portion. Moreover, the method includes a step of forming a sealing layer on the insulating layer and the conductor layer of the capacitor element such that the sealing layer covers the first main surface of the capacitor element with the insulating layer formed, a step of forming an anode through-electrode that is disposed in the sealing layer and the insulating layer such that the anode through-electrode extends through the sealing layer and the insulating layer on the exposed portion of the core portion of the capacitor element and that is connected to the core portion of the capacitor element, a step of forming a cathode through-electrode that is disposed in the sealing layer such that the cathode through-electrode extends through the sealing layer on the conductor layer of the capacitor element and that is connected to the conductor layer of the capacitor element, a step of forming, on the sealing layer, an anode outer electrode that is connected to the anode through-electrode that is exposed from a surface of the sealing layer, and a step of forming, on the sealing layer, a cathode outer electrode that is connected to the cathode through-electrode that is exposed from the surface of the sealing layer.

A method according to another exemplary aspect is provided for manufacturing a solid electrolytic capacitor that includes a step of preparing a capacitor element that includes a valve action metal base including a porous portion at least on a first main surface of a core portion, a dielectric layer that is disposed on a surface of the porous portion, a solid electrolyte layer that is disposed on the dielectric layer, and a conductor layer that is disposed on the solid electrolyte layer, with the capacitor element including an exposed portion of the core portion along the first main surface of the valve action metal base. Moreover, the method includes a step of forming a sealing layer on the conductor layer and the exposed portion of the core portion of the capacitor element such that the sealing layer covers the first main surface of the capacitor element, a step of forming an anode through-electrode that is disposed in the sealing layer such that the anode through-electrode extends through the sealing layer on the exposed portion of the core portion of the capacitor element and that is connected to the core portion of the capacitor element, a step of forming a cathode through-electrode that is disposed in the sealing layer such that the cathode through-electrode extends through the sealing layer on the conductor layer of the capacitor element and that is connected to the conductor layer of the capacitor element, a step of forming, on the sealing layer, an anode outer electrode that is connected to the anode through-electrode that is exposed from a surface of the sealing layer, and a step of forming, on the sealing layer, a cathode outer electrode that is connected to the cathode through-electrode that is exposed from the surface of the sealing layer.

The present disclosure provides a solid electrolytic capacitor that has a low ESR and a low ESL and that can be designed to be thin.

