Printhead having a thin pre-fired piezoelectric layer
View Patent ↗A printhead having a monolithic semiconductor body with an upper face and a lower face. The body defines a fluid path including a pumping chamber, a nozzle flow path, and a nozzle opening. The nozzle opening is defined in the lower face of the body and the nozzle flow path includes an accelerator region. A piezoelectric actuator is associated with the pumping chamber. The actuator includes a piezoelectric layer having a thickness of about 50 micron or less.
1. A printhead comprising:
a flow path including a pumping region, and
a piezoelectric actuator associated with the pumping region of the flow path, said actuator having a pre-fired piezoelectric layer with a thickness of less than 50 microns, the pre-fired piezoelectric layer being a piezoelectric material fired at a thickness greater than 50 microns prior to attachment to a support and thinned to the thickness less than 50 microns after attachment to the support.
2. The printhead of claim 1 wherein the thickness of the piezoelectric layer is about 25 microns or less.
3. The printhead of claim 2 wherein the piezoelectric layer is bonded to an actuator membrane.
4. The printhead of claim 3 wherein the actuator membrane has a thickness of about 25 microns or less.
5. The printhead of claim 4 wherein the actuator membrane is silicon or glass.
6. The printhead of claim 1 wherein the piezoelectric layer has a surface with an Ra of about 0.05 micron or less.
7. The printhead of claim 1 wherein the piezoelectric layer is a substantially planar body of piezoelectric material.
8. The printhead of claim 1 wherein the pumping region is formed in silicon.
9. The printhead of claim 8 wherein the flow path includes a nozzle opening and the nozzle opening is in silicon.
10. The printhead of claim 8 wherein the flow path is defined in a body that is a wafer segment and the piezoelectric actuator is attached to a first face of the body and the flow path includes a nozzle on a second opposing face of the body.
11. The printhead of claim 1 , further comprising a bonding layer.
12. The printhead of claim 11 , wherein the bonding layer includes an organic material.
13. The printhead of claim 11 , wherein the bonding layer includes an adhesive or an epoxy.
14. The printhead of claim 11 , wherein:
the actuator includes a membrane between the piezoelectric layer and the flow path, and
the bonding layer is between the piezoelectric layer and the membrane.
15. The printhead of claim 14 , wherein the support includes the membrane.
16. The printhead of claim 14 , wherein the support includes the membrane and the pumping region.
17. The printhead of claim 11 , wherein:
the piezoelectric layer has a metal layer formed thereon, and
the bonding layer is between the metal layer and the flow path.
18. The printhead of claim 17 , wherein the metal layer is exposed to the flow path.
19. The printhead of claim 11 , wherein:
the piezoelectric layer has a metal layer formed thereon,
the actuator includes a membrane, and
the bonding layer is between the metal layer and the membrane.
20. The printhead of claim 11 , wherein the actuator includes a metal layer supported by the piezoelectric layer on a side opposite to the bonding layer.
21. The printhead of claim 11 , wherein the bonding layer includes amorphous silicon.
22. The printhead of claim 11 , wherein the bonding layer includes a eutectic bond.
23. The printhead of claim 11 , wherein the bonding layer includes BCB.
24. The printhead of claim 1 , wherein the printhead includes multiple flow paths with associated actuators.
25. The printhead of claim 1 , wherein the pre-fired piezoelectric layer has a d31 of about 200 or more.
26. The printhead of claim 1 , wherein the density of the piezoelectric layer is about 7.5 g/cm or more.
27. The printhead of claim 1 , wherein the printhead includes a plurality of pumping regions, associated actuators, and associated ejection nozzles for ejecting fluid from the printhead, the ejection nozzles having a diameter of about 50 microns or less.
28. The printhead of claim 27 , wherein the plurality of pumping regions are defined in a common body.
29. The printhead of claim 28 , wherein the common body is a silicon or a silicon on insulator wafer and said pumping regions are defined on a face of said wafer.
30. The printhead of claim 28 , wherein the common body is an etchable material etchable by deep reactive ion etching.
31. The printhead of claim 30 , wherein the etchable material is silicon.
32. The printhead of claim 27 , wherein the plurality of ejection nozzles are defined in a common body.
33. The printhead of claim 32 , wherein the common body is an etchable material etchable by deep reactive ion etching.
34. The printhead of claim 32 , wherein the common body is a silicon or a silicon on insulator wafer and the nozzles are defined on a face of said wafer.
35. The printhead of claim 1 , wherein the piezoelectric actuator comprises no more than one layer of piezoelectric material.