Liquid-jet head and method of producing the same and liquid injection device

• US 20060290747A1
• Filed: 09/24/2004
• Published: 12/28/2006
• Est. Priority Date: 09/24/2003
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Tsuda, Akihito, Yazaki, Shiro, Nishiwaki, Tsutomu, Shimada, Masato, Yamada, Masataka
• Granted Patent: US 7,559,631 B2
• Time in Patent Office: Days
• US Class Current: 347/68
• CPC Class Codes: B41J 2/14233 of film type, deformed by bending and disposed on a diaphragm
• CPC Class Codes: B41J 2/161 of film type, deformed by bending and disposed on a diaphragm
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1629 wet etching
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1635 dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2002/14241 having a cover around the piezoelectric thin film element
• CPC Class Codes: B41J 2002/14419 Manifold
• CPC Class Codes: B41J 2002/14491 Electrical connection

Abstract

There are provided a liquid-jet head which can reliably prevent breakage of piezoelectric elements over a long period of time, and a method for manufacturing the liquid-jet head, as well as a liquid-jet apparatus. Further, there are provided a liquid-jet head which can effectively prevent a drop in the amount of displacement of a vibration plate caused through drive of a piezoelectric element, and a method for manufacturing the liquid-jet head, as well as a liquid-jet apparatus.

A liquid-jet head includes a channel substrate 10 which has pressure generation chambers 12 formed therein and communicating nozzle orifices for discharging liquid droplets, and piezoelectric elements 300 each of which is composed of a lower electrode 60, a piezoelectric layer 70, and an upper electrode 80 and which are disposed on one surface of the channel substrate 10 via a vibration plate, wherein at least pattern regions of the respective layers which constitute the piezoelectric elements 300 are covered with an insulating film 100 formed of an inorganic insulating material.

Claims

1. A liquid-jet head characterized by comprising a channel substrate which has pressure generation chambers formed therein and communicating nozzle orifices for discharging liquid droplets;

and piezoelectric elements each of which is composed of a lower electrode, a piezoelectric layer, and an upper electrode and which are disposed on one surface of the channel substrate via a vibration plate, wherein at least pattern regions of the respective layers which constitute the piezoelectric elements are covered with an insulating film formed of an inorganic amorphous material.

2. The liquid-jet head according to claim 1, wherein the amorphous material is aluminum oxide (Al₂0₃).

3. The liquid-jet head according to claim 2, wherein the insulating film has a thickness of 30 to 150 nm.

4. The liquid-jet head according to claim 2, wherein the insulating film has a film density of 3.08 to 3.25 g/cm³.

5. The liquid-jet head according to claim 2, wherein the insulating film has a Young'"'"'s modulus of elasticity of 170 to 200 GPa.

6. The liquid-jet head according to claim 1, wherein the sum of stress of the insulating film and stress of the upper electrode is compressive.

7. The liquid-jet head according to claim 6, wherein stress of the insulating film and stress of the upper electrode are each compressive.

8. The liquid-jet head according to claim 7, wherein the upper electrode is formed of at least Pt.

9. The liquid-jet head according to claim 6, wherein stress of the insulating film is compressive, and stress of the upper electrode is tensile.

10. The liquid-jet head according to claim 9, wherein the upper electrode is formed of at least Ir.

11. The liquid-jet head according to claim 9, wherein stress 6 of the upper electrode and that of the insulating film are each represented by the product (ε

×

Y×

m) of Young'"'"'s modulus of elasticity Y, distortion ε

, and film thickness m, and stress δ

₁ of the upper electrode and stress δ

₂ of the insulating film satisfy the condition |δ

₁|<

|δ

₂|.

12. The liquid-jet head according to claim 1, further comprising an upper-electrode lead electrode extending from the upper electrode, wherein at least pattern regions of the respective layers which constitute the piezoelectric elements and the upper-electrode lead electrode are covered with the insulating film, except for regions facing connection portions of the lower electrode and the upper-electrode lead electrode, the connection portions being used for connection with connection wiring.

13. The liquid-jet head according to claim 12, wherein the upper-electrode lead electrode is formed of a material containing aluminum as a predominant component.

14. The liquid-jet head according to claim 12, further comprising a lower-electrode lead electrode extending from the lower electrode, wherein the lower electrode is connected to the connection wiring via the lower-electrode lead electrode, and the pattern region containing the lower-electrode lead electrode is covered with the insulating film, except for regions of the upper-electrode lead electrode and the lower-electrode lead electrode facing the connection wiring.

15. The liquid-jet head according to claim 12, wherein the upper electrode and the upper-electrode lead electrode are formed of different materials.

16. The liquid-jet head according to claim 12, wherein the piezoelectric layer and the upper electrode of each piezoelectric element extend to the outside of a region facing the corresponding pressure generation chamber so that a piezoelectric non-active portion is formed, and an end portion of the upper-electrode lead electrode on the side toward the upper electrode is located on the piezoelectric non-active portion and outside the pressure generation chamber.

17. The liquid-jet head according to claim 12, wherein in a state in which the connection wiring is connected, the connection portions are covered with a sealing material formed of an organic insulating material.

18. The liquid-jet head according to claim 12, wherein the insulating film includes a first insulating film and a second insulating film, the piezoelectric elements are covered by the first insulating film except for the connection portion for connection with the upper-electrode lead electrode, the upper-electrode lead electrode is provided on the first insulating film, and at least the pattern regions of the respective layers which constitute the piezoelectric elements and the upper-electrode lead electrode are covered with the second insulating film except for regions facing the connection portions.

19. The liquid-jet head according to claim 12, wherein the connection wiring includes a second upper-electrode lead electrode extending from the upper-electrode lead electrode, the second upper-electrode lead electrode is provided on the insulating film and is connected to the upper-electrode lead electrode at the connection portion, and a terminal portion to which drive wring is connected is provided at a tip end portion of the second upper-electrode lead electrode.

20. The liquid-jet head according to claim 12, wherein the piezoelectric layer and the upper electrode of each piezoelectric element extend to the outside of a region facing the corresponding pressure generation chamber so that a piezoelectric non-active portion is formed, and an upper-electrode-side end portion of the upper-electrode lead electrode which is connected to the upper electrode is located on the piezoelectric non-active portion and outside the pressure generation chamber.

21. The liquid-jet head according to claim 12, wherein a protective plate having a piezoelectric-element-holding portion, which is a space for protecting the piezoelectric elements, is bonded to a surface of the channel substrate, the surface being located on the side toward the piezoelectric elements, and the connection portion of the upper-electrode lead electrode is provided outside the piezoelectric-element-holding portion.

22. The liquid-jet head according to claim 1, wherein a protective plate having a piezoelectric-element-holding portion, which is a space for protecting the piezoelectric elements, is bonded to a surface of the channel substrate via an adhesive layer, the surface being located on the side toward the piezoelectric elements, the protective plate includes a flow passage for liquid to be supplied to the pressure generation chambers, the adhesive layer located on the flow passage side of the piezoelectric-element-holding portion is exposed to the interior of the flow passage, and a moisture permeable portion which enables permeation of water within the piezoelectric-element-holding portion is provided in a region other than the flow passage side of the piezoelectric-element-holding portion.

23. The liquid-jet head according to claim 22, wherein the moisture permeable portion is formed of an organic material.

24. The liquid-jet head according to claim 22, wherein the moisture permeable portion is provided on a portion of a bonding surface of the protective plate, the bonding surface being bonded to the channel substrate.

25. The liquid-jet head according to claim 22, wherein the moisture permeable portion is provided on an upper surface of the protective plate.

26. The liquid-jet head according to claim 24, wherein the moisture permeable portion is formed of an adhesive having a water permeability higher than that of an adhesive which constitutes the adhesive layer.

27. The liquid-jet head according to claim 22, wherein the moisture permeable portion is formed of a potting material.

28. The liquid-jet head according to claim 22, wherein the moisture permeable portion is provided in a region on a side of the piezoelectric-element-holding portion opposite the flow passage.

29. The liquid-jet head according to claim 22, wherein the moisture permeable portion is provided on the protective plate in each of regions outside the opposite ends of the row of pressure generation chambers.

30. A liquid-jet apparatus characterized by comprising the liquid-jet head according to any one of claims 1 to 29.

34. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 2.

35. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 3.

36. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 4.

37. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 5.

38. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 6.

39. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 7.

40. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 8.

41. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 9.

42. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 10.

43. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 11.

44. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 12.

45. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 13.

46. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 14.

47. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 15.

48. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 16.

49. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 17.

50. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 18.

51. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 19.

52. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 20.

53. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 21.

54. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 22.

55. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 23.

56. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 24.

57. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 25.

58. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 26.

59. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 27.

60. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 28.

61. A liquid-jet apparatus characterized by comprising the liquid-jet head according to claim 29.

31. A method of manufacturing a liquid-jet head, comprising the steps of forming piezoelectric elements, each of which is composed of a lower electrode, a piezoelectric layer, and an upper electrode, on one surface of a channel substrate via a vibration plate, the channel substrate having pressure generation chambers formed therein and communicating nozzle orifices for discharging liquid droplets;

forming an upper-electrode lead electrode extending from the upper electrode of each piezoelectric element;

forming an insulating film of an inorganic amorphous material over the entirety of a surface of the channel substrate, the surface facing the piezoelectric elements; and

patterning the insulating film such that at least connection-wiring connection portions of the lower electrode and the upper-electrode lead electrode are exposed, and the insulating film is left in pattern regions of the respective layers of the piezoelectric elements and the upper-electrode lead electrode, except for the connection portion.

32. The method of manufacturing a liquid-jet head according to claim 31, wherein in the step of patterning the insulating film, a portion of the insulating film within a predetermined region is removed by means of ion milling.

33. The method of manufacturing a liquid-jet head according to claim 31, wherein the method includes, after the step of patterning the insulating film, a step of bonding a protective plate to a surface of the channel substrate, the surface facing the piezoelectric elements, the protective plate including a piezoelectric-element-holding portion for protecting the piezoelectric elements and a flow passage for liquid to be supplied to the pressure generation chambers, wherein in the step of bonding the protective plate, an adhesive is applied to the protective plate such that a space portion is left in a portion of a region surrounding the piezoelectric-element-holding portion, except for a region located on the side toward the flow passage, the protective plate is bonded to the channel substrate, and the space portion is sealed by a material having a water permeability higher than that of the adhesive so as to form a moisture permeable portion through which water within the piezoelectric-element-holding portion permeates.