Temperature compensating device with integral sheet thermistors

• US 20030128096A1
• Filed: 01/10/2002
• Published: 07/10/2003
• Est. Priority Date: 01/10/2002
• Status: Active Grant

• Current Assignee: Lighting Science Group Corporation (Pegasus Capital Advisors, L.P.)
• Original Assignee: Lamina Ceramics, Inc.
• Inventors: Mazzochette, Joseph
• Granted Patent: US 6,759,940 B2
• Time in Patent Office: Days
• US Class Current: 338/22R
• CPC Class Codes: H01C 7/008 Thermistors H01C7/02 - H01C7/06 take precedence
• CPC Class Codes: H01C 7/021 formed as one or more layers or coatings
• CPC Class Codes: H01C 7/041 formed as one or more layers or coatings

Abstract

In accordance with the invention, a temperature compensating device comprises one or more integrated sheet thermistors. Because the sheet thermistors are relatively thick and integral with the substrate, they are less susceptible to changes in air temperature and to temperature gradients. Moreover, the sheet thermistors can be made smaller in area, permitting more compact, less expensive devices that exhibit improved high frequency performance. The devices can advantageously be fabricated using the low temperature co-fired ceramic (LTCC) process.

Claims

1. A device for compensating the effect of temperature changes in an electrical or electronic circuit comprising a plurality of thermistors electronically connected in a temperature compensating circuit wherein:

at least one of the thermistors is a sheet thermistor comprising a sheet of thermistor material having a pair of major surfaces and a pair of electrodes formed and laterally spaced apart on the major surfaces.

2. A device according to claim 1 wherein each electrode comprises a first portion on one major surface, a second portion on the other major surface and one or more conductive vias connecting the first and second portions.

3. A device according to claim 1 wherein the sheet of thermistor material has a thickness of about 0.001 inch or more.

4. A device for compensating the effect of temperature changes in an electrical or electronic circuit comprising:

an integral body comprising a plurality of sheet thermistors connected in a temperature compensating circuit, each sheet thermistor comprising

a sheet of thermistor material having a pair of major surfaces and a pair of electrodes formed and laterally spaced apart on the major surfaces.

5. A device according to claim 4 wherein each electrode comprises a first portion on one major surface, a second portion on the other major surface and one or more conductive vias connecting the first and second portions.

6. A device according to claim 4 wherein an insulating layer is disposed between successive sheets of thermistor material.

7. A method of making a device for compensating the effect of temperature changes in an electrical or electronic circuit comprising the steps of:

providing a plurality of green sheet thermistors, each green sheet thermistor comprising a sheet of thermistor material having a pair of major surfaces and a pair of conductive ink patterns formed and laterally spaced apart on a major surface;

providing one or more green sheets of insulating ceramic;

alternately stacking the sheets so that there is at least one insulating ceramic sheet between successive sheet thermistors; and

cofiring the stacked sheets to form an integrated body.

8. The method of claim 7 wherein at least one green sheet thermistor has conductive ink patterns formed and laterally spaced apart on both major surfaces, patterns on one major surface connected to patterns on the other major surface to form, after firing, a pair of laterally spaced apart electrodes, each electrode having conductive portions on both major surfaces.

9. The method of claim 8 wherein the patterns are connected by conductive vias between the major surfaces.