SOLID ELECTROLYTIC CAPACITOR

• US 20120127634A1
• Filed: 11/22/2010
• Published: 05/24/2012
• Est. Priority Date: 12/18/2009
• Status: Active Grant

• Current Assignee: Tayca Corporation
• Original Assignee: Tayca Corporation
• Inventors: Sugihara, Ryosuke, Tsurumoto, Yuhei, Fujihara, Kazuto
• Granted Patent: US 8,684,576 B2
• Time in Patent Office: Days
• US Class Current: 361/525
• CPC Class Codes: H01G 11/48 Conductive polymers
• CPC Class Codes: H01G 11/56 Solid electrolytes, e.g. gels; Additives therein
• CPC Class Codes: H01G 9/0036 Formation of the solid electrolyte layer
• CPC Class Codes: H01G 9/028 Organic semiconducting electrolytes, e.g. TCNQ
• CPC Class Codes: H01G 9/15 Solid electrolytic capacitors H01G11/00 takes precedence
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

The present invention provides a solid electrolytic capacitor having a low ESR, excellent heat resistance, and reliability used under a high temperature condition. On the dielectric layer of the capacitor element, 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine monomer is subject to oxidation polymerization to provide a first conductive polymer layer. Then, 2,3-dihydro-thieno[3,4-b][1,4]dioxine or a monomer mixture of 2,3-dihydro-thieno[3,4-b][1,4]dioxine and 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine is subject to oxidation polymerization to provide a second conductive polymer layer. The formation of the first conductive polymer layer and the second conductive polymer layer is alternatively repeated. The first conductive polymer and the second conductive polymer serve as a solid electrolyte to provide a solid electrolytic.

Claims

1. A solid electrolytic capacitor, comprising:

a capacitor element including a porous material of a valve metal, and a dielectric layer of an oxidation film of the valve metal; and

a solid electrolyte of a conductive polymer provided on the dielectric layer,

wherein the solid electrolyte comprises;

a first conductive polymer layer obtained by oxidation polymerization of 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine; and

a second conductive polymer layer obtained by oxidation polymerization of 2,3-dihydro-thieno[3,4-b][1,4]dioxine or a mixture of 2,3-dihydro-thieno[3,4-b][1,4]dioxine with 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine,

wherein at least one of the first conductive polymer layer and at least one of the second conductive polymer layer are alternatively laminated,

wherein the first conductive polymer layer is provided on the dielectric layer of the capacitor element.

3. A solid electrolytic capacitor according to claim 1, wherein the 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine is at least one selected from the group consisting of 2-methyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, 2-ethyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, 2-propyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, and 2-butyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine.

5. A solid electrolytic capacitor according to claim 1, wherein the valve metal is selected from the group consisting of tantalum, aluminum and niobium.

2. A solid electrolytic capacitor, comprising:

a capacitor element including a porous material of a valve metal, and a dielectric layer of an oxidation film of the valve metal; and

a solid electrolyte of a conductive polymer provided on the dielectric layer,

wherein the solid electrolyte comprises a lamination comprising;

a first conductive polymer layer obtained by oxidation polymerization of 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, including an aromatic sulfonic acid as dopant; and

a second conductive polymer layer obtained by oxidation polymerization of 2,3-dihydro-thieno[3,4-b][1,4]dioxine or a mixture of 2,3-dihydro-thieno[3,4-b][1,4]dioxine with 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, including an aromatic sulfonic acid as dopant,

wherein at least one of the first conductive polymer layer and at least one of the second conductive polymer layer are alternatively laminated,

wherein a third conductive polymer layer including a polymeric sulfonic acid as dopant is further laminated on the lamination,

wherein the first conductive polymer layer is provided on the dielectric layer of the capacitor element.

4. A solid electrolytic capacitor according to claim 2, wherein the 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine is at least one selected from the group consisting of 2-methyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, 2-ethyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, 2-propyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, and 2-butyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine.

6. A solid electrolytic capacitor according to claim 2, wherein the valve metal is selected from the group consisting of tantalum, aluminum and niobium.

7. A method for producing a solid electrolytic capacitor, comprising:

providing a capacitor element including a porous material of a valve metal, and a dielectric layer of an oxidation film of the valve metal; and

providing a solid electrolyte of a conductive polymer on the dielectric layer,

wherein the solid electrolyte is formed by the steps comprising;

preparing a first conductive polymer layer by oxidation polymerization of 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine; and

preparing a second conductive polymer layer by oxidation polymerization of 2,3-dihydro-thieno[3,4-b][1,4]dioxine or a mixture of 2,3-dihydro-thieno[3,4-b][1,4]dioxine with 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine,

wherein at least one of the first conductive polymer layer and at least one of the second conductive polymer layer are alternatively laminated,

wherein the first conductive polymer layer is provided on the dielectric layer of the capacitor element.

8. A method for producing a solid electrolytic capacitor according to claim 7, wherein the steps to form the solid electrolyte further comprises

providing a third conductive polymer layer including a polymeric sulfonic acid as dopant,

wherein the third conductive polymer layer is provided over the first conductive polymer layer or the second conductive polymer layer.

9. A method for producing a solid electrolytic capacitor according to claim 7, wherein the 2-alkyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine is at least one selected from the group consisting of 2-methyl-2,3-dihydro-thieno[3,4-b][1,4] dioxine, 2-ethyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, 2-propyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine, and 2-butyl-2,3-dihydro-thieno[3,4-b][1,4]dioxine.

10. A method for producing a solid electrolytic capacitor according to claim 7, wherein the valve metal is selected from the group consisting of tantalum, aluminum and niobium.