Ultrasonic phased array transducer with an ultralow impedance backfill and a method for making

• US 20010032382A1
• Filed: 04/09/2001
• Published: 10/25/2001
• Est. Priority Date: 06/19/1995
• Status: Active Grant

• Current Assignee: Lowell Scott Smith, Peter William Lorraine
• Original Assignee: Lowell Scott Smith, Peter William Lorraine
• Inventors: Smith, Lowell Scott, Lorraine, Peter William
• Granted Patent: US 6,453,526 B2
• Time in Patent Office: Days
• 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

The present invention discloses an ultrasonic phased array transducer with an ultralow backfill and a method for making. 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:

providing a low density backfill material having an ultralow acoustic impedance;

bonding a piezoelectric ceramic material and a plurality of matching layers to the backfill material; and

cutting through portions of the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material to form an array of electrically and acoustically isolated individual elements.

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 placing a flexible circuit board between the piezoelectric ceramic material and the ultralow impedance backfill.

6. A method according to

claim 1

, further comprising the step of forming a plurality of interconnect vias in the backfill material.

7. A method according to

claim 6

, further comprising the step of depositing a conducting material in the plurality of interconnect vias.

8. A method according to

claim 1

, further comprising the step of bonding an electronic layer to the backfill material at a face opposite to the bonded piezoelectric ceramic material and plurality of matching layers, the electronic layer used for making electrical contacts to the piezoelectric ceramic material and to external devices.

9. A method according to

claim 8

, wherein the cuts extend through the plurality of matching layers, the piezoelectric ceramic material, and the backfill material.

10. A method according to

claim 8

, wherein the backfill material is either a carbon aerogel or a carbon xerogel.

11. A method according to

claim 1

, wherein the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material are cut with a laser.

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

providing a low density backfill material having an ultralow acoustic impedance;

bonding a flexible circuit board at one end of the ultralow impedance backfill;

bonding a piezoelectric ceramic material and a plurality of matching layers to the flexible circuit board and the backfill material, wherein the flexible circuit board is bonded between the backfill material and the piezoelectric ceramic material; and

cutting through portions of the bonded plurality of matching layers, the piezoelectric ceramic material, the flexible circuit board, and the backfill material to form an array of electrically and acoustically isolated individual elements.

13. A method according to

claim 12

, wherein the backfill material is either an aerogel or an xerogel.

14. A method according to

claim 13

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

15. A method according to

claim 14

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

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

providing a low density backfill material having an ultralow acoustic impedance;

bonding a piezoelectric ceramic material and a plurality of matching layers to the backfill material;

forming a plurality of interconnect vias in the backfill material;

depositing a conducting material in the plurality of interconnect vias; and

cutting through portions of the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material to form an array of electrically and acoustically isolated individual elements.

17. A method according to

claim 16

, wherein the backfill material is either an aerogel or an xerogel.

18. A method according to

claim 17

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

19. A method according to

claim 18

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

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

providing an electrically conductive low density backfill material having an ultralow acoustic impedance;

bonding a piezoelectric ceramic material and a plurality of matching layers to the backfill material;

bonding an electronic layer to the backfill material at a face opposite to the bonded piezoelectric ceramic material and plurality of matching layers, the electronic layer used for making electrical contacts to the piezoelectric ceramic material and to external devices; and

cutting through portions of the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material to form an array of electrically and acoustically isolated individual elements.

21. A method according to

claim 20

, wherein the backfill material is either a carbon aerogel or a carbon xerogel.

22. A method according to

claim 21

, wherein the cut portions extend through the plurality of matching layers, the piezoelectric ceramic material, and the backfill material.

23. A method according to

claim 22

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

24. A method according to

claim 23

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

25. 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.

26. A method according to

claim 25

, wherein the backfill material is either an aerogel or an xerogel.

27. A method according to

claim 26

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

28. A method according to

claim 27

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

29. A method according to

claim 25

, further comprising the step of planarizing the backfill material deposited on the array of electrically and acoustically isolated individual elements.

30. A method according to

claim 25

, further comprising the step of removing the substrate from the backfill material, the piezoelectric material, and the plurality of matching layers.

31. An ultrasonic phased array transducer, comprising:

a low density backfill material having an ultralow acoustic impedance;

a piezoelectric ceramic material; and

a plurality of matching layers;

the piezoelectric ceramic material and the plurality of matching layers bonded to the backfill material, a portion of the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material having cuts therethrough to form an array of electrically and acoustically isolated individual elements.

32. An ultrasonic phased array transducer according to

claim 31

, wherein the backfill material is either an aerogel or an xerogel.

33. An ultrasonic phased array transducer according to

claim 32

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

34. An ultrasonic phased array transducer according to

claim 33

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

35. An ultrasonic phased array transducer according to

claim 31

, further comprising a flexible circuit board placed between the piezoelectric ceramic material and the ultralow impedance backfill.

36. An ultrasonic phased array transducer according to

claim 31

, further comprising a plurality of interconnect vias formed in the backfill material.

37. An ultrasonic phased array transducer according to

claim 36

, further comprising a conducting material deposited in the plurality of interconnect vias.

38. An ultrasonic phased array transducer according to

claim 31

, further comprising an electronic layer bonded to the backfill material at a face opposite to the bonded piezoelectric ceramic material and plurality of matching layers, the electronic layer used for making electrical contacts to the piezoelectric ceramic material and to external devices.

39. An ultrasonic phased array transducer according to

claim 38

, wherein the cuts extend through the plurality of matching layers, the piezoelectric ceramic material, and the backfill material.

40. An ultrasonic phased array transducer according to

claim 38

, wherein the backfill material is either a carbon aerogel or a carbon xerogel.

41. An ultrasonic phased array transducer, comprising:

a low density backfill material having an ultralow acoustic impedance;

a flexible circuit board bonded to one side of the ultralow impedance backfill;

a piezoelectric ceramic material; and

a plurality of matching layers;

the piezoelectric ceramic material and the plurality of matching layers bonded to the flexible circuit board and the backfill material, wherein the flexible circuit board is placed between the piezoelectric ceramic material and the backfill material, a portion of the bonded plurality of matching layers, the piezoelectric ceramic material, the flexible circuit board and the backfill material having cuts therethrough to form an array of electrically and acoustically isolated individual elements.

42. An ultrasonic phased array transducer according to

claim 41

, wherein the backfill material is either an aerogel or an xerogel.

43. An ultrasonic phased array transducer according to

claim 42

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

44. An ultrasonic phased array transducer according to

claim 43

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

45. An ultrasonic phased array transducer, comprising:

a low density backfill material having an ultralow acoustic impedance;

a piezoelectric ceramic material; and

a plurality of matching layers;

the piezoelectric ceramic material and the plurality of matching layers bonded to the backfill material, the backfill material having a plurality of interconnect vias formed therein, the plurality of interconnect vias having a conducting material deposited therein, a portion of the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material having cuts therethrough to form an array of electrically and acoustically isolated individual elements.

46. An ultrasonic phased array transducer according to

claim 45

, wherein the backfill material is either an aerogel or an xerogel.

47. An ultrasonic phased array transducer according to

claim 46

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

48. An ultrasonic phased array transducer according to

claim 47

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

49. An ultrasonic phased array transducer, comprising:

an electrically conductive low density backfill material having an ultralow acoustic impedance;

a piezoelectric ceramic material; and

a plurality of matching layers;

the piezoelectric ceramic material and the plurality of matching layers bonded to the backfill material, the backfill material bonded to an electronic layer at a face opposite to the bonded piezoelectric ceramic material and a plurality of matching layers, the electronic layer used for making electrical contacts to the piezoelectric ceramic material and to external devices, a portion of the bonded plurality of matching layers, the piezoelectric ceramic material, and the backfill material having cuts therethrough to form an array of electrically and acoustically isolated individual elements.

50. An ultrasonic phased array transducer according to

claim 49

, wherein the backfill material is either a carbon aerogel or a carbon xerogel.

51. An ultrasonic phased array transducer according to

claim 50

, wherein the cut portions extend through the plurality of matching layers, the piezoelectric ceramic material, and the backfill material.

52. An ultrasonic phased array transducer according to

claim 51

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

53. An ultrasonic phased array transducer according to

claim 52

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.

54. An ultrasonic phased array transducer, comprising:

a piezoelectric ceramic material and a plurality of matching layers bonded to each other, the piezoelectric ceramic material and the plurality of matching layers having cuts therethrough to form an array of electrically and acoustically isolated individual elements;

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

a plurality of interconnect vias formed in the backfill material, wherein the plurality of interconnect vias have a conducting material deposited therein.

55. An ultrasonic phased array transducer according to

claim 54

, wherein the backfill material is either an aerogel or an xerogel.

56. An ultrasonic phased array transducer according to

claim 55

, wherein the backfill material has an acoustic impedance substantially less than 1 MRayl.

57. An ultrasonic phased array transducer according to

claim 56

, wherein the backfill material has an acoustic impedance less than 0.5 MRayl.