Co-fired ceramic capacitor and method for forming ceramic capacitors for use in printed wiring boards

• US 7,072,167 B2
• Filed: 06/28/2004
• Issued: 07/04/2006
• Est. Priority Date: 10/11/2002
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Borland, William J.
• Primary Examiner(s): Ha, Nguyen T.
• Application Number:
  US10/878,877
• Publication Number:
  US 20040233611A1
• Time in Patent Office: 736 Days
• Field of Search: 361302-303, 361/305, 361/321.1, 361/321.5, 361/306.1, 361/306.3, 361/311, 361/313, 361/328, 361/321.2, 438/400, 438/243, 438/250
• US Class Current: 361/302
• CPC Class Codes: H01G 4/01 Form of self-supporting electrodes
• CPC Class Codes: H05K 1/092 Dispersed materials, e.g. conductive pastes or inks
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2201/09509 Blind vias, i.e. vias having one side closed
• CPC Class Codes: H05K 2201/09718 Clearance holes
• CPC Class Codes: H05K 2201/09763 Printed component having superposed conductors, but integrated in one circuit layer
• CPC Class Codes: H05K 3/429 Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers
• CPC Class Codes: H05K 3/4611 by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: H05K 3/4623 the circuit boards having internal via connections between two or more circuit layers before lamination, e.g. double-sided circuit boards H05K3/462 takes precedence
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

A capacitor structure is fabricated by forming a pattern of first dielectrics over a foil, forming first electrodes over the first dielectrics, and co-firing the first dielectrics and the first electrodes. Co-firing of the dielectrics and the electrodes alleviates cracking caused by differences in thermal coefficient of expansion (TCE) between the electrodes and the dielectrics. Co-firing also ensures a strong bond between the dielectrics and the electrodes. In addition, co-firing allows multi-layer capacitor structures to be constructed, and allows the capacitor electrodes to be formed from copper.

Claims

1. A capacitor structure, comprising:

a metallic foil;

at least one dielectric layer disposed over a portion of the foil; and

at least one first electrode disposed over a portion of the dielectric layer;

wherein upon cofiring the at least one dielectric layer with the at least one first electrode, the at least one dielectric layer exhibits a high dielectric constant, and the foil, the at least one dielectric layer and the at least one first electrode form a high capacitance capacitor.

2. The capacitor structure of claim 1, wherein the metallic foil and the at least one first electrode comprises copper.

3. The capacitor structure of claim 1, wherein the at least one dielectric layer comprises a high K glass and barium titanate.

4. The capacitor structure of claim 3, wherein the at least one dielectric layer further comprises zirconium oxide.

5. The capacitor structure of claim 1, incorporated into a device.

6. A multi-layer capacitor structure, comprising:

a metallic foil;

a first dielectric layer disposed over a portion of the foil;

a first electrode disposed over a portion of to dielectric layer and a portion of the foil;

a second dielectric layer disposed over a portion of the first dielectric layer and the first electrode; and

at least one second electrode disposed over a portion of the second dielectric layer and over a portion of the foil, wherein, upon cofiring the first and second dielectric layers with the first and second electrodes, and after etching the foil to form a trench, the dielectric exhibits a high dielectric constant and the foil, the first and second dielectric layers and the first and second electrodes form a high capacitance capacitor.

7. The capacitor structure of claim 6, wherein the first dielectric layer and the first electrode are cofired prior to the addition of the second dielectric layer and the second electrode.

8. The capacitor structure of claim 6, wherein the dielectric layer comprises a high K glass and barium titanate.

9. The capacitor structure of claim 8, wherein the dielectric layer further comprises zirconium oxide.

10. The capacitor structure of claim 6, wherein the metallic foil and the first electrode comprise copper.

11. The capacitor structure of claim 10, wherein the second electrode comprises copper.

12. The capacitor structure of claim 6, further comprising a third electrode formed over a portion of the second dielectric layer.

13. The capacitor structure of claim 6, incorporated into a device.