Method for forming an ultrasonic phased array transducer with an ultralow impedance backing

• US 6,263,551 B1
• Filed: 04/10/2000
• Issued: 07/24/2001
• Est. Priority Date: 06/19/1995
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Smith, Lowell Scott, Lorraine, Peter William
• Primary Examiner(s): Hall, Carl E.
• Application Number:
  US09/546,406
• Time in Patent Office: 470 Days
• Field of Search: 29/253.5, 298/52, 310/334, 310/336, 310/365
• US Class Current: 29/25.35
• CPC Class Codes: B06B 1/0622 on one surface
• CPC Class Codes: B06B 1/0629 Square array
• CPC Class Codes: G10K 11/002 Devices for damping, suppressing, obstructing or conducting sound in acoustic devices G10K1/06 - G10K1/10 take precedence; for electro-mechanical transducers for communication H04R3/002
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49165 by forming conductive walled aperture in base
• CPC Class Codes: Y10T 29/49792 Dividing through modified portion

Abstract

Method for forming an ultrasonic phased array transducer with an ultralow impedance backing. The ultrasonic phased array includes a low density backfill material having an ultralow acoustic impedance. The backfill material is either an aerogel, a carbon aerogel, an xerogel, or a carbon xerogel. A piezoelectric ceramic material and two matching layers are bonded to the backfill material. In one embodiment, a plurality of interconnect vias are formed in the backfill material with conducting material deposited in the vias. A portion of the bonded matching layers, the piezoelectric ceramic material, and the backfill material have isolation cuts therethrough to form an array of electrically and acoustically isolated individual elements. In a second embodiment, the backfill material is bonded to an electronic layer at a face opposite to the piezoelectric ceramic material and the matching layers. Then isolation cuts are made through the matching layers, the piezoelectric ceramic material, and the backfill material, to form an array of electrically and acoustically isolated individual elements.

Claims

1. A method for forming an ultrasonic phased array transducer with an ultralow impedance backing, the method comprising the steps of:

bonding a piezoelectric ceramic material and a plurality of matching layers on a substrate;

cutting the bonded plurality of matching layers and the piezoelectric ceramic material to form an array of electrically and acoustically isolated individual elements;

depositing a low density backfill material having an ultralow acoustic impedance over the array of electrically and acoustically isolated individual elements;

forming a plurality of interconnect vias in the backfill material; and

depositing a conducting material in the plurality of interconnect vias.

2. A method according to claim 1, wherein the backfill material is either an aerogel or an xerogel.

3. A method according to claim 2, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

4. A method according to claim 3, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

5. A method according to claim 1, further comprising the step of planarizing the backfill material deposited on the array of electrically and acoustically isolated individual elements.

6. A method according to claim 1, further comprising the step of removing the substrate from the backfill material, the piezoelectric material, and the plurality of matching layers.