Electrically variable piezoelectric hybrid capacitor

• US 4,716,331 A
• Filed: 03/13/1987
• Issued: 12/29/1987
• Est. Priority Date: 12/30/1985
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Higgins, Robert J. Jr.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US07/025,430
• Time in Patent Office: 291 Days
• Field of Search: 310/317, 310/319, 310/330-332, 310/369, 361/277, 361/278, 361/287, 361/289, 361/290, 29/25.35
• US Class Current: 310/330
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/43 Electric condenser making

Abstract

An electrically variable three terminal monomorphic piezoelectric capacitor is manufactured with thick or thin film hybrid microelectronic circuit technology. A first capacitor plate and a ridge, which substantially surrounds and extends above the first capacitor plate, are formed on the surface of a substrate. A monomorphic piezoelectric wafer having a control plate and a second capacitor plate on opposing surfaces is bonded to the upper surface of the ridge. During bonding, a force is applied at the center of the wafer which fixes a permanent bow in the wafer in the direction of the first capacitor plate. A four terminal monomorphic embodiment and three and four terminal bimorphic embodiments are also described.

Claims

1. An electrically variable piezoelectric hybrid microelectronic circuit capacitor, comprising in combination:

a substrate;

a first capacitor plate formed on a surface of said substrate;

a ridge formed by a hybrid microelectronic circuit manufacturing process on said surface of said substrate, said ridge having an upper surface positioned a predetermined distance above said first capacitor plate;

an arch or dome shaped piezoelectric wafer connected to said upper surface of said ridge;

a second capacitor plate formed on a first surface of said piezoelectric wafer;

a first control plate formed on a second surface of said piezoelectric wafer.

3. The capacitor of claim 1 wherein said ridge is tooled in said substrate.

4. The capacitor of claim 1 wherein said ridge is sputtered on said substrate.

5. The capacitor of claim 1 wherein said ridge is vacuum-deposited on said substrate.

6. The capacitor of claim 1 wherein said ridge is electroplated on said substrate.

7. The capacitor of claim 1 wherein said ridge is screened on said substrate.

8. The capacitor of claim 1 wherein said ridge is a preformed glass ring bonded to said substrate.

9. The capacitor of claim 1 further comprising a second control plate on said first surface of said piezoelectric wafer.

2. An electrically variable piezoelectric hybrid microelectronic circuit capacitor, comprising in combination:

a ceramic substrate;

a first capacitor plate formed on a surface of said ceramic substrate;

a substantially circular supporting ridge formed by a hybrid microelectronic circuit manufacturing process on said surface of said ceramic substrate, said ridge having an upper surface positioned a predetermined distance above said first capacitor plate;

a substantially dome shaped piezoelectric wafer having a convex surface adjacent said first capacitor plate and a concave surface opposed to said convex surface, said wafer being connected to said upper surface of said ridge at the perimeter of said wafer;

a second capacitor plate formed on said convex surface of said piezoelectric wafer; and

a control plate formed on said concave surface of said piezoelectric wafer;

whereby, the capacitance between said first and second capacitor plates is a function of the control voltage applied between said control plate and said second capacitor plate.