Surface acoustic wave device

• US 5,939,817 A
• Filed: 09/21/1995
• Issued: 08/17/1999
• Est. Priority Date: 09/22/1994
• Status: Expired due to Fees

• Current Assignee: Nihon Dempa Kogyo Company Limited
• Original Assignee: NEC Corporation
• Inventors: Takado, Heiji
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/531,594
• Time in Patent Office: 1,426 Days
• Field of Search: 310/313 R, 310/344, 310/348, 310/365
• US Class Current: 310/348
• CPC Class Codes: H01L 2224/4899 Auxiliary members for wire connectors, e.g. flow-barriers, reinforcing structures, spacers, alignment aids
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/15153 the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/1517 Multilayer substrate
• CPC Class Codes: H01L 2924/16195 Flat cap [not enclosing an internal cavity]
• CPC Class Codes: H03H 9/059 consisting of mounting pads or bumps
• 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

Abstract

A surface acoustic wave element 11 having an inter digital electrode 12 formed on one surface of a piezo-electric substrate is arranged in a recess of a package 13 with the one surface being faced to a bottom surface of the recess of the package 13. An elastic conductive pad 35 having pads electrically connected to the electrode of the surface acoustic wave element 11 and electrodes of the package 13 is provided between the one surface of the surface acoustic wave element 11 and the package 13. The conductive pad 35 includes wiring means 35a, with which it is possible to connect the surface acoustic wave element 11 to the package 13 even when the position of the surface acoustic wave element in which the interdigital electrode is formed is deviated from the position of the electrodes of the package 13. The package 13 includes a cap 30 for pressing down the surface acoustic wave element 11. The surface acoustic wave element 11 is mounted on the conductive pad 35 in the package 13 with a surface of the surface acoustic wave element 11 on which the interdigital electrode is formed being down. Since the package 13 is hermetically sealed by the cap 30 while the surface acoustic wave element 11 being pressed down, the wire bonding becomes unnecessary, causing mounting to be facilitated. Further, the improvement of the quality of the device and its miniaturization are realized.

Claims

1. A surface acoustic wave device comprising:

a surface acoustic wave element comprising a piezoelectric substrate and an interdigital electrode formed on one surface of said piezoelectric substrate, said interdigital electrode having connection pads;

mounting means for mounting said surface acoustic wave element, said mounting means having a mounting surface which faces said one surface of said piezoelectric substrate and having mounting pads formed on portions of said mounting surface;

electric connection means, which includes a conductive pad formed of an electrically non-conductive and elastic material, for electrically connecting said connection pads of said interdigital electrode to said mounting pads of said mounting means, said elastic material having a plurality of conductive filaments embedded therein, electrically isolated from each other and extending in only one direction from said conductive pads to said mounting pads for allowing current to pass between said connection pads and said mounting pads while preventing current from passing between adjacent filaments; and

a cap disposed on said mounting surface for hermetically sealing said mounting means while pressing said surface acoustic wave element toward said mounting means.

2. The surface acoustic wave device claimed in claim 1, further comprising a buffer sheet disposed between said cap and an acoustic wave element surface which is opposite said one surface of said acoustic surface wave element.

3. The surface acoustic wave device claimed in claim 1, wherein said mounting means includes a surface mount electrode pad formed on an opposite surface thereof to said surface on which said surface acoustic wave element is mounted.

4. The surface acoustic wave device claimed in claim 1, wherein said mounting means includes lead terminals formed on a surface thereof opposing to said mounting surface on which said surface acoustic wave element is mounted and extending perpendicularly to said surface acoustic wave element.

5. The surface acoustic wave device claimed in claim 1, wherein said electrically conductive and elastic material includes silicon rubber and metal filaments.

6. The surface acoustic wave device claimed in claim 1, wherein said electric connection means is continuous under a periphery of said surface acoustic wave element and is located between said connecting pads of said interdigital electrode and said mounting pads of said mounting means.

7. The surface acoustic wave device claimed in claim 1, wherein said conductive pads and mounting pads are substantially parallel to each other and wherein said conductive filaments are perpendicular to said mounting and conductive pads.