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

• US 20040233611A1
• Filed: 06/28/2004
• Published: 11/25/2004
• 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.
• Granted Patent: US 7,072,167 B2
• Time in Patent Office: Days
• US Class Current: 361/306.3
• 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 disposed over the foil;

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

at least one second electrode disposed over a portion of the dielectric and over a portion of the first electrode, wherein a portion of the dielectric is disposed between the first and second electrodes.

2. The capacitor structure of claim 1, wherein the foil comprises:

a trench that electrically isolates the first electrode from the second electrode.

3. The capacitor structure of claim 1, wherein:

the at least one dielectric comprises a plurality of dielectrics;

the at least one first electrode comprises a plurality of first electrodes;

the at least one second electrode comprises a plurality of second electrodes; and

the dielectrics, the first electrodes, and the second electrodes are arranged as a plurality of stacks on the metallic foil, each stack comprising a first electrode, a second electrode, and a dielectric.

4. The capacitor structure of claim 3, comprising:

a plurality of third electrodes, one in each stack, wherein each third electrode is disposed over a portion of a corresponding dielectric and over a portion of a corresponding first electrode and is electrically connected to the corresponding first electrode.

5. The capacitor structure of claim 3, wherein the metallic foil and the first and second electrodes comprise copper.