Surface acoustic wave device package

• US 5,237,235 A
• Filed: 09/30/1991
• Issued: 08/17/1993
• Est. Priority Date: 09/30/1991
• Status: Expired due to Fees

• Current Assignee: CTS Corporation
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Falkner, Robert F. Jr., Penunuri, David, Cho, Frederick Y.
• Primary Examiner(s): Budd, Mark O.
• Assistant Examiner(s): Dougherty, Thomas M.
• Application Number:
  US07/767,338
• Time in Patent Office: 687 Days
• Field of Search: 310/313 R, 310/340, 310/344, 333/195, 29/25.35
• US Class Current: 310/313.00R
• CPC Class Codes: H03H 9/02874 of direct coupling between input and output transducers
• CPC Class Codes: H03H 9/0585 consisting of an adhesive layer
• CPC Class Codes: H03H 9/1071 the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the SAW device
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A surface acoustic wave (SAW) device package for reducing insertion loss and direct RF feedthrough of the SAW device is disclosed. The package provides for extensive shielding of each of the input and output pads. The inputs and outputs to the SAW device are separated by maintaining the inputs on one surface of the substrate and the outputs on the opposite surface of the substrate. The SAW crystal substrate including the SAW devices is bonded to the package substrate and the package is hermetically sealed via a low-temperature glass seal or solder-type sealing, for example.

Claims

1. A surface acoustic wave (SAW) device package for reducing insertion loss and direct RF feedthrough of a SAW device, the SAW device package comprising:

substrate means including at least first and second surfaces;

input means for connection to external circuitry, said input means disposed on said substrate means;

output means for connection to external circuitry, said output means disposed on said substrate;

shield means for preventing electrical coupling to said input means and said output means, said shield means disposed on said substrate means;

SAW means including;

SAW input means connected to said input means for transmitting an input signal to said SAW device;

SAW output means connected to said output means for transmitting at least one output signal from said SAW device; and

a SAW substrate, said SAW device disposed on said SAW substrate and positioned substantially over said shield means to inhibit parasitic electrical connection to said SAW device;

said SAW device package further comprising bonding means disposed on said shield means and said substrate means, said bonding means for bonding said SAW substrate to said substrate means;

lid means for physically covering said SAW means, said lid means positioned over said SAW means and in contact with said substrate means;

means for sealing said lid means to said substrate means;

said shield means including;

input shield means corresponding to said input means and substantially surrounding said input means; and

output shield means corresponding to said output means and surrounding said output means on at least two sides;

said output means and said corresponding output shield means disposed on said first surface of said substrate means for connection to external circuitry; and

said input means and said corresponding input shield means disposed on said first surface of said substrate means and wrapped around said substrate means to said second surface for connection to external circuitry.

2. The SAW device package as claimed in claim 1, wherein said bonding means includes a thermoplastic adhesive.

3. The SAW device package as claimed in claim 1, wherein said sealing means includes a low-melting-temperature glass for hermetically sealing said lid means to said substrate means.

4. The SAW device package as claimed in claim 1, wherein said SAW means includes:

a plurality of SAW devices including a central SAW device and first and second end SAW devices, said central SAW device being positioned between said first and second end SAW devices;

said central SAW device for receiving said input signal via said input means and said SAW input means, said central SAW device connected to said SAW input means; and

said first end SAW device located on one end of said central SAW device and said second end SAW device located on an opposite end of said central SAW device, said first and second end SAW devices acoustically coupled to said central SAW device for providing said output signal in response to said input signal, said first and second end SAW devices connected to said SAW output means.

5. The SAW device package as claimed in claim 4, wherein:

said shield means includes a central shield and first and second end shields;

said central shield connected to said central SAW device;

said first end shield connected to said first end SAW device; and

said second end shield connected to said second end SAW device.

6. The SAW device package as claimed in claim 5, wherein said central shield, said first end shield and said second end shield are each separately connected to electrical ground.

7. The SAW device package as claimed in claim 6, wherein there are further included first and second dummy electrode means, said first dummy electrode means disposed on said SAW substrate between said central SAW device and said first end SAW device, said second dummy electrode means disposed on said SAW substrate between said central SAW device and said second end SAW device;

and

said first and second dummy electrode means being separately connected to electrical ground.

8. A surface acoustic wave (SAW) device package for reducing insertion loss and direct RF feedthrough of a SAW device, the SAW device package comprising:

substrate means including at least first and second surfaces;

input means for connection to external circuitry, said input means disposed on said substrate means;

output means for connection to external circuitry, said output means disposed on said substrate;

shield means for preventing electrical coupling to said input means and said output means, said shield means disposed on said substrate means;

SAW means including;

SAW input means connected to said input means for transmitting an input signal to said SAW device;

SAW output means connected to said output means for transmitting at least one output signal from said SAW device;

a SAW crystal substrate; and

said SAW device disposed on said SAW crystal substrate and positioned substantially over said shield means to inhibit parasitic electrical connection to said SAW device;

said SAW device package further comprising bonding means disposed on said shield means and said substrate means, said bonding means for bonding said SAW crystal substrate to said substrate means;

lid means for physically covering said SAW means, said lid means positioned over said SAW means and in contact with said substrate means;

said substrate means including holes through said substrate means from said first to said second surface, said holes for transmitting electrical connection from said input means or from said output means, and from said shield means, on said first surface to said second surface for electrical connection to external circuitry; and

means for sealing said lid means to said substrate means.

9. The SAW device package as claimed in claim 8, wherein said bonding means includes a thermoplastic adhesive.

10. The SAW device package as claimed in claim 8, wherein said sealing means includes a solder seal for hermetically sealing said lid means to said substrate means.

11. The SAW device package as claimed in claim 8, wherein said SAW means includes:

a plurality of SAW device including a central SAW device and first and second end SAW devices, said central SAW device positioned between said first and second end SAW devices;

said central SAW device for receiving said input signal via said input means and said SAW input means, said central SAW device connected to said SAW input means; and

said first end SAW device located on one end of said central SAW device and said second end SAW device located on an opposite end of said central SAW device, said first and said second end SAW devices acoustically coupled to said central SAW device for providing said at least one output signal in response to said input signal, said first and said second end SAW devices connected to said output means.

12. The SAW device package as claimed in claim 11, wherein:

said shield means includes a central shield and first and second end shields;

said central shield connected to said central SAW device;

said first end shield connected to said first end SAW device; and

said second end shield connected to said second end SAW device.

13. The SAW device package as claimed in claim 12, wherein said central shield, said first end shield and said second end shield are each separately connected to electrical ground.

14. The SAW device package as claimed in claim 13, wherein there are further included:

first and second dummy electrode means, said first dummy electrode means disposed on said SAW crystal substrate between said central SAW device and said first end SAW device, said second dummy electrode means disposed on said SAW crystal substrate between said central SAW device and said second end SAW device; and

said first and second dummy electrode means being separately connected to electrical ground.

15. A surface acoustic wave (SAW) device package for reducing insertion loss and direct RF feedthrough of a SAW device, the SAW device package comprising:

substrate means including at least first and second surfaces;

input means for connection to external circuitry, said input means disposed on said substrate means;

output means for connection to external circuitry, said output means disposed on said substrate;

shield means for preventing electrical coupling to said input means and said output means, said shield means disposed on said substrate means;

SAW means including;

SAW input means connected to said input means for transmitting an input signal to said SAW device;

SAW output means connected to said output means for transmitting at least one output signal from said SAW device; and

a SAW substrate, said SAW device disposed on said SAW substrate and positioned substantially over said shield means to inhibit parasitic electrical connection to said SAW device;

said SAW device package further comprising bonding means disposed on said shield means and said substrate means, said bonding means for bonding said SAW substrate to said substrate means;

lid means for physically covering said SAW means, said lid means positioned over said SAW means and in contact with said substrate means;

means for sealing said lid means to said substrate means;

said shield means including input shield means corresponding to said input means and surrounding said input means on at least two sides;

said shield means including output shield means corresponding to said output means and substantially surrounding said output means;

said input means and said corresponding input shield means disposed on said first surface of said substrate means for electrical connection to external circuitry; and

said output means and said corresponding output shield means disposed on said first surface of said substrate means and are wrapped around said substrate means to said second surface of said substrate means for electrical connection to external circuitry.

16. A method for packaging a SAW device, the method comprising the steps of:

providing a ceramic substrate having a top and a bottom surface;

disposing an input pad on the top surface of the ceramic substrate and wrapping the input pad around to the bottom surface of the ceramic substrate;

disposing output pads on the top surface of the ceramic substrate;

disposing a plurality of ground planes on the top surface of the ceramic substrate, each of the plurality of ground planes substantially surrounding a corresponding input pad or surrounding a corresponding output pad on at least two sides;

providing a SAW crystal substrate including at least one SAW device;

bonding the SAW crystal substrate to the ceramic substrate so that the at least one SAW device is substantially over a first ground plane of the plurality of ground planes;

connecting the at least one SAW device to the first ground plane;

connecting the at least one SAW device to the input and output pads;

providing a lid; and

hermetically sealing the lid to the ceramic substrate.

17. In a radio, at least one surface acoustic wave (SAW) device package for reducing insertion loss and direct RF feedthrough of a SAW device, the SAW device package comprising:

substrate means including at least first and second surfaces;

input means for connection to external circuitry, said input means disposed on said substrate means;

output means for connection to external circuitry, said output means disposed on said substrate;

shield means for preventing electrical coupling to said input means and said output means, said shield means disposed on said substrate and substantially surrounding said input means and surrounding said output means on at least two sides, said shield means including input shield means corresponding to said input means and substantially surrounding said input means, said input means and said corresponding input shield means disposed on said first surface of said substrate means and wrapped around said substrate means to said second surface for connection to external circuitry;

SAW means including;

SAW input means connected to said input means for transmitting an input signal to said SAW device;

SAW output means connected to said output means for transmitting at least one output signal from said SAW device; and

a SAW substrate, said SAW device disposed on said SAW substrate and positioned substantially over said shield means to inhibit parasitic electrical connection to said SAW device;

bonding means disposed on said shield means and said substrate means, said bonding means for bonding said SAW substrate to said substrate means;

said SAW device package further comprising lid means for physically covering said SAW means, said lid means positioned over said SAW means and in contact with said substrate means; and

means for sealing said lid means to said substrate means.

18. In a radio, at least one surface acoustic wave (SAW) device package for reducing insertion loss and direct RF feedthrough of a SAW device, the SAW device package comprising;

substrate means including at least first and second surface;

input means for connection to external circuitry, said input means disposed on said substrate means;

output means for connection to external circuitry, said output means disposed on said substrate;

shield means for preventing electrical coupling to said input means and said output means, said shield means disposed on said substrate means and substantially surrounding said input means and surrounding said output means on at least two sides;

SAW means including;

SAW input means connected to said input means for transmitting an input signal to said SAW device; and

SAW output means connected to said output means for transmitting at least one output signal from said SAW means; and

a SAW substrate, said SAW device disposed on said SAW substrate and positioned substantially over said shield means to inhibit parasitic electrical connection to said SAW device;

said SAW device package further comprising lid means for physically covering said SAW means, said lid means positioned over said SAW mans and in contact with said substrate means;

bonding means disposed on said shield means and said substrate means, said bonding means for bonding said SAW substrate to said substrate means;

said substrate means including holes through said substrate means from said first to said second surface, said holes for transmitting electrical connection from said input means or alternatively from said output means, and from said shield means, on said first surface to said second surface for electrical connection to external circuitry; and

means for sealing said lid means to said substrate means.