Sacrificial quartz crystal mount

• US 5,030,875 A
• Filed: 01/26/1990
• Issued: 07/09/1991
• Est. Priority Date: 01/26/1990
• Status: Expired due to Fees

• Current Assignee: CTS Corporation
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Knecht, Thomas A.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US07/470,484
• Time in Patent Office: 529 Days
• Field of Search: 310/346, 310/348, 310/351-353, 310/344
• US Class Current: 310/346
• CPC Class Codes: H03H 9/0509 consisting of adhesive elements
• CPC Class Codes: H03H 9/0514 consisting of mounting pads or bumps

Abstract

In a conventional quartz crystal resonator, a sacrificial quartz layer attached to the mounting posts and between the active, vibrating quartz layer and the package base reduces mechanical stresses on the active quartz layer caused by thermal expansion coefficient differences. The intermediate quartz layer is a sacrificial layer which acts to maintain the spacing of mounting posts.

Claims

1. A piezoelectric quartz crystal resonator comprised of:

a package base having a first thermal expansion coefficient;

an active piezoelectric quartz layer including electroded surfaces and with a second thermal expansion coefficient;

mounting pedestals coupled to and cantilevered from said package base and coupled to said active piezoelectric quartz layer, said mounting pedestals capable of exerting mechanical stress on said active piezoelectric quartz layer arising from differences between said first and second thermal expansion coefficients; and

an intermediate layer means coupled to said mounting pedestals and between said active piezoelectric quartz layer and said package base for reducing mechanical stress on said active piezoelectric quartz layer.

2. The resonator of claim 1 where said package is a leaded package.

3. The resonator of claim 1 where said package is surface mountable.

4. The crystal resonator of claim 1 where said intermediate layer means is quartz.

5. The crystal resonator of claim 1 where said first thermal expansion coefficient is between approximately 2 and 10 ppm/degrees C. and said second thermal expansion coefficient is between 10 and 20 ppm/degree C.

6. The crystal resonator of claim 5 where said intermediate layer has a thermal expansion coefficient substantially between said first and second thermal expansion coefficients.

7. The crystal resonator of claim 1 where said mounting base is ceramic.

8. The crystal resonator of claim 1 where said mounting posts are conductive epoxy.

9. The crystal resonator of claim 1 where said mounting posts are conductive adhesive.

10. The communications device of claim 1 where said mounting posts are conductive epoxy.

11. The crystal resonator of claim 1 where said crystal has a predetermined fabrication cut.

12. The crystal resonator of claim 11 where said intermediate layer is quartz with a fabrication cut substantially identical to said fabrication cut of said crystal resonator.

13. The crystal resonator of claim 1 including means for conducting electrical signals to said electroded crystal plate.

14. The crystal resonator of claim 13 where said means for conducting electrical signals includes wires bonded to said electroded crystal plate and said package base.

15. The crystal resonator of claim 13 where said means for conducting electrical signals includes conductive adhesive on said electroded crystal plate, said intermediate layer and said package base.

16. The crystal resonator of claim 1 where said intermediate layer means is coupled to said package base by at least one, first mounting means and said electroded crystal plate is coupled to said intermediate layer by at least one second mounting means.