JP2009166452A - Liquid jetting head, and liquid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting head and a liquid jetting apparatus by which a wiring pattern can accurately be formed in a photo-lithography process, which cause less abnormalities in the wiring pattern such as a wiring breakage, and have a high reliability. <P>SOLUTION: When the wiring patterns 35 and 37 are formed on a bonded board 30 by the photo-lithography process, if a resist R which has invaded in a through-hole 33 by including air bubbles moves toward the outside from the through-hole 33 by the swelling of the air bubbles B in a temporary baking process of the resist R, the air bubbles break and jet out at a step section 38 which is formed on the inner surface of the through-hole 33. Therefore, the splashing stays within the inside of the through-hole 33, and the splashing to a resist R4 which is applied on the bonded board 30 can be reduced. Thus, the film thickness of the applied resist R can be kept uniform, and the wiring patterns 35 and 37 are accurately formed in the subsequent process. Also, abnormalities in the wiring patterns such as the wiring breakage can be reduced, and the reliability of the inkjet type recording head 1 and the inkjet type recording apparatus 1000 can be increased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, and in particular, a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is configured by a diaphragm, and a piezoelectric element is formed on the surface of the diaphragm. The present invention relates to an ink jet recording head and an ink jet recording apparatus that eject ink droplets by displacement of a piezoelectric element.

As an ink jet recording head, a flow path forming substrate having a plurality of rows of pressure generation chambers communicating with nozzle openings, and a drive IC that is bonded to the piezoelectric element side provided on the flow path forming substrate and drives the piezoelectric element are provided. A structure having a bonding substrate to be mounted is known.
Further, in these ink jet recording heads, in the bonding substrate, through holes through which the extraction electrodes drawn out from the piezoelectric elements are exposed correspond to each row of the pressure generation chambers in a region corresponding to the row of the pressure generation chambers. It is known that at least one beam is provided and a beam portion is formed between adjacent through holes.
Furthermore, a wiring pattern on which the driving IC is mounted is formed on the bonding substrate, and a common electrode that forms a part of the wiring pattern and is common to a plurality of piezoelectric elements arranged in parallel on the beam portion. Is known in which common electrode wirings connected to are formed along a row of pressure generation chambers (see, for example, Patent Document 1).

JP-A-2005-53079 (pages 4 to 5, FIG. 1)

  A wiring pattern on which the driving IC is mounted is formed on the bonding substrate by a photolithography process. Here, in the resist coating process and the temporary baking process in the photolithography process, the resist that has entered through the through holes in the resist coating process is ruptured and ejected by the expansion of the air trapped in the preliminary baking process. The sprayed resist adheres to the uniformly applied resist film, and the resist film thickness in that portion becomes thicker, or the resist film thickness is reduced by being dragged by the spraying near the through hole. Cause non-uniformity. If the resist film thickness is non-uniform, the wiring pattern cannot be formed accurately under the conditions of the subsequent exposure and development processes determined according to the resist film thickness, and wiring pattern abnormality such as wiring breakage occurs. Therefore, the reliability of the liquid ejecting head and the liquid ejecting apparatus including the liquid ejecting head is lowered.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A flow path forming substrate provided with a plurality of rows of pressure generating chambers communicating with the nozzle openings, and a piezoelectric element provided on one surface side of the flow path forming substrate corresponding to the pressure generating chamber via a vibration plate A bonding substrate that is bonded to the pressure element side of the flow path forming substrate, a driving IC that is disposed on the bonding substrate and drives the piezoelectric element, and between the rows of the pressure generation chambers of the bonding substrate One or a plurality of the pressure generating chambers are provided in a region corresponding to each of the pressure generating chambers, and are formed between a through hole in which a lead electrode extracted from the piezoelectric element is exposed and the adjacent through hole. A stepped portion extending along the row of pressure generating chambers is formed on the inner surface of the through hole and the beam portion. A liquid jet head characterized by .

  According to this application example, when the wiring pattern is formed on the bonded substrate by the photolithography process, the resist that has entered the through hole into the through hole is expanded from the through hole due to the expansion of the bubble in the resist pre-baking process. Even toward the surface, the stepped portion formed on the inner surface of the through hole is ruptured and ejected, so that it is only scattered inside the through hole, and there is little scattering to the resist applied on the bonding substrate. Accordingly, the thickness of the applied resist can be kept uniform, the wiring pattern can be accurately formed in the subsequent steps, wiring pattern abnormalities such as wiring breakage can be reduced, and the reliability of the liquid jet head can be improved.

[Application Example 2]
The liquid ejecting head according to claim 1, wherein the step portion is a protrusion.
In this application example, the bubble that expands in the through-hole and the resist that goes to the outside from the through-hole is easily ruptured and ejected by the protrusion on the inner surface of the through-hole, and has less influence on the resist applied on the bonding substrate. Become.

[Application Example 3]
The liquid ejecting head according to claim 1, wherein an edge is formed in the stepped portion.
In this application example, bubbles are expanded in the through-holes by the edges, and the resist going outward from the through-holes is cut, and before reaching the bonding substrate, it becomes easier to rupture and eject inside the through-holes. The influence on the resist applied thereon is lessened.

[Application Example 4]
A liquid ejecting apparatus comprising the liquid ejecting head described above.

  According to this application example, a liquid ejecting apparatus that can achieve the above-described effects can be obtained.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a schematic perspective view illustrating an example of an ink jet recording apparatus 1000 as a liquid ejecting apparatus.
In FIG. 1, an ink jet recording apparatus 1000 includes recording head units 1A and 1B. The recording head units 1A and 1B are detachably provided with cartridges 2A and 2B constituting ink supply means. A carriage 3 on which the recording head units 1A and 1B are mounted is a carriage shaft 5 attached to the apparatus main body 4. Are provided so as to be axially movable.

  The recording head units 1A and 1B, for example, discharge a black ink composition and a color ink composition, respectively. The driving force of the driving motor 6 is transmitted to the carriage 3 through a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted moves along the carriage shaft 5. . On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  The recording head units 1 </ b> A and 1 </ b> B include an ink jet recording head 1 as a liquid ejecting head at a position facing the recording sheet S. In the figure, they are located on the recording sheet S side of the recording head units 1A and 1B and are not shown.

FIG. 2 is an exploded partial perspective view showing the ink jet recording head 1 according to the embodiment. The shape of the ink jet recording head 1 is a substantially rectangular parallelepiped, and FIG. 2 is an exploded partial perspective view cut along a plane orthogonal to the longitudinal direction of the ink jet recording head 1 (the direction of the white arrow in the figure).
3A is a partial plan view of the ink jet recording head 1, and FIG. 3B is a cross-sectional view taken along line AA in FIG.

2 and 3, the ink jet recording head 1 includes a flow path forming substrate 10, a nozzle plate 20, a bonding substrate 30, a compliance substrate 40, and two drive ICs 110.
The flow path forming substrate 10, the nozzle plate 20, and the bonding substrate 30 are stacked such that the flow path forming substrate 10 is sandwiched between the nozzle plate 20 and the bonding substrate 30, and the compliance substrate 40 is formed on the bonding substrate 30. ing. A driving IC 110 is mounted on the compliance board 40.

  The flow path forming substrate 10 is made of a silicon single crystal plate having a plane orientation (110). A plurality of pressure generating chambers 12 are formed on the flow path forming substrate 10 in two rows 13 by anisotropic etching. Here, the rows 13 are arranged in parallel in the width direction of the ink jet recording head 1 (direction orthogonal to the longitudinal direction). The cross-sectional shape of the pressure generation chamber 12 in the width direction of the ink jet recording head 1 is trapezoidal, and the pressure generation chamber 12 is formed long in the width direction of the ink jet recording head 1.

  Further, a communication portion 14 is formed in a region outside the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10, and the communication portion 14 and each pressure generation chamber 12 are provided in each pressure generation chamber 12. Communication is made via an ink supply path 15. The ink supply path 15 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 14.

In the nozzle plate 20, nozzle openings 21 communicating with the outside are formed in the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 15.
The nozzle plate 20 has a thickness of, for example, 0.01 to 1 mm, a linear expansion coefficient of 300 ° C. or less, for example, 2.5 to 4.5 [× 10 ⁻⁶ / ° C.], glass ceramics, silicon It consists of a single crystal substrate or non-rust steel.
The flow path forming substrate 10 and the nozzle plate 20 are fixed by an adhesive, a heat welding film, or the like through an insulating film 51 used as a mask when the pressure generating chamber 12 is formed by anisotropic etching. .

An elastic film 50 as a vibration plate is formed on the surface of the flow path forming substrate 10 that faces the surface on which the nozzle plate 20 is fixed. The elastic film 50 is made of an oxide film formed by thermal oxidation.
An insulator film 55 made of an oxide film is formed on the elastic film 50 of the flow path forming substrate 10. Further, on the insulator film 55, a lower electrode film 60 made of a metal such as platinum (Pt) or a metal oxide such as strontium ruthenate (SrRuO), a piezoelectric layer 70 having a perovskite structure, Au, Ir The upper electrode film 80 made of a metal such as the above is formed to constitute the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80.

In general, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned into each pressure generating chamber 12. In addition, here, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion.
In the embodiment, the lower electrode film 60 is a common electrode of the piezoelectric element 300, and the upper electrode film 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. . In either case, a piezoelectric active part is formed for each pressure generating chamber 12. Here, the piezoelectric element 300 and the elastic film 50 and the insulator film 55 (vibrating plate) that are displaced by the driving of the piezoelectric element 300 are collectively referred to as a piezoelectric actuator.

  In addition, a lead electrode 90 as an extraction electrode made of, for example, gold (Au) or the like is connected to the upper electrode film 80 constituting each of the piezoelectric elements 300, and the lead electrode 90 is connected to the pressure generation chamber. It extends to the area between the twelve rows 13.

A bonding substrate 30 on which a drive IC 110 for driving the piezoelectric element 300 is mounted is bonded on the flow path forming substrate 10 on which the piezoelectric element 300 is formed.
The bonding substrate 30 includes a piezoelectric element holding portion 31 that can seal the space in a region facing the piezoelectric element 300 in a state where a space that does not hinder the movement of the piezoelectric element 300 is secured. Two piezoelectric element holding portions 31 are provided corresponding to the two rows 13 of each pressure generating chamber 12.
In the embodiment, each piezoelectric element holding portion 31 is integrally provided in a region corresponding to the row 13 of each pressure generating chamber 12, but may be provided independently for each piezoelectric element 300. .
Examples of the material of the bonding substrate 30 include glass, a ceramic material, a metal, a resin, and the like, but it is more preferable that the bonding substrate 30 is formed of substantially the same material as the thermal expansion coefficient of the flow path forming substrate 10. In the embodiment, it is formed using a silicon single crystal substrate made of the same material as the flow path forming substrate 10.

  The bonding substrate 30 is provided with a reservoir portion 32 in a region corresponding to the communication portion 14 of the flow path forming substrate 10. In the embodiment, the reservoir portion 32 is provided along the row 13 of the pressure generating chambers 12 through the bonding substrate 30 in the thickness direction, and is communicated with the communication portion 14 of the flow path forming substrate 10. A reservoir 100 serving as an ink chamber common to the pressure generation chamber 12 is configured.

Further, in a substantially central portion of the bonding substrate 30, that is, in a region facing the region between the rows 13 of the pressure generation chambers 12, through holes 33 penetrating the bonding substrate 30 in the thickness direction are arranged in the rows of the pressure generation chambers 12. A beam portion 34 is formed between the through holes 33.
The extended lead electrode 90 has its tip exposed at the bottom of the through hole 33.
The beam portion 34 is preferably formed integrally with the bonding substrate 30, but may be a separate body from the bonding substrate 30.

  Further, a wiring pattern 35 to which an external wiring (not shown) is connected and a drive signal is supplied is provided on the bonding substrate 30 via an insulating film 36. A semiconductor integrated circuit (IC) for driving each piezoelectric element 300 on both sides of the through hole 33 of the bonding substrate 30, that is, on the wiring pattern 35 in a region corresponding to each row 13 of the pressure generation chamber 12. A drive IC 110 is mounted on each.

  The drive signal includes, for example, a drive system signal for driving the drive IC such as a drive power supply signal, and various control system signals such as a serial signal (SI). The wiring pattern 35 is supplied with each signal. Consists of multiple wires. In the embodiment, the wiring pattern as the common electrode wiring connected to the lower electrode film 60 that is the common electrode of the piezoelectric element 300 among the wirings constituting the wiring pattern 35 and supplied with the driving signal (COM). 37 extends along the row 13 of the pressure generating chambers 12 on the beam portion 34 together with the region where the driving IC 110 is mounted. The wiring provided on the beam portion 34 is not limited to the wiring pattern 37, and wiring for supplying a signal such as serial may be arranged.

  Each drive IC 110 mounted on the wiring pattern 35 and the lead electrode 90 extended from each piezoelectric element 300 are electrically conductive, such as a bonding wire, extended in the through hole 33 of the bonding substrate 30. They are electrically connected by connecting wires 120 made of conductive wires. Similarly, the wiring pattern 37 and the lower electrode film 60 are electrically connected by the connection wiring 120 in the vicinity of both end portions of the through hole 33.

  A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the bonding substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and the sealing film 41 seals one surface of the reservoir portion 32. It has been stopped. The fixing plate 42 is formed of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

FIG. 4 shows an enlarged cross-sectional view near the through hole 33. Here, the connection wiring 120 is not shown.
A step portion 38 is formed on the inner surface of the through hole 33. The step portion 38 is formed from the bottom of the through hole 33 to the middle of the inner surface of the through hole 33 and extends along the row 13 of the pressure generating chambers 12 (longitudinal direction of the ink jet recording head 1 in FIG. 2). Is formed. Further, the stepped portion 38 includes an edge 39. Here, the angle forming the edge is preferably 90 ° or less.
It should be noted that the protrusions only need to be provided on the inner surface of the through-hole 33 regardless of the size of the opening of the through-hole 33. Further, the height of the edge 39 from the bottom surface of the through hole 33 is a height that is not covered by the resist R even if the resist R enters, and is preferably low.

Various shapes can be adopted as the shape of the stepped portion 38. For example, the shapes shown in FIGS. 5A to 5C may be used.
In FIG. 5A, a stepped portion 381 having a quadrangular cross section may be formed in the middle of the inner surface of the through hole 33. The step portion 381 has an edge 391.
In FIG. 5B, a step portion 382 having a triangular cross-sectional shape may be formed in the middle of the inner surface of the through hole 33. The stepped portion 382 has an edge 392 at the top. The apex angle of the apex is preferably 90 ° or less.
In FIG. 5C, a stepped portion 383 having a half-moon shaped cross section may be formed in the middle of the inner surface of the through hole 33. In this case, no edge is provided.

  Further, the stepped portion 38 is formed so as to extend along the row 13 of the pressure generating chambers 12, but may be formed with an interval in the middle. Here, the interval is preferably shorter than the thickness of the bonding substrate 30.

According to such an embodiment, there are the following effects.
(1) The effects will be described below by comparing the case where the stepped portion 38 is not formed on the inner surface of the through hole 33 and the case where the stepped portion 38 is formed.
FIG. 6 is a schematic cross-sectional view showing a state in which the resist R for forming the wiring patterns 35 and 37 is pre-baked by the photolithography process when the step portion 38 is not formed on the inner surface of the through-hole 33. showed that.
FIG. 6A shows a state after the resist R is applied and before temporary baking. (B) has shown the state at the time of temporary baking.

6A, a metal thin film F used for the wiring pattern 35 is formed on the surface of the bonding substrate 30 on which the wiring pattern 35 is formed. Further, a protective tape T is attached to the surface facing the surface on which the wiring pattern 35 is formed.
A resist R is applied on the thin film F in a resist application step of a photolithography process. At this time, the resist R also enters the reservoir portion 32 and the through hole 33. Here, since the resist R has a relatively high viscosity, the bubbles B are involved when entering the narrow space, for example, the through hole 33.

In FIG.6 (b), the bubble B wound in the state of (a) expand | swells with the heat | fever applied at the time of temporary baking, and becomes bubble B1. The bubble B1 expands and bursts while lifting the resist R1 (the direction of scattering is indicated by a solid arrow in the figure). At this time, the resist R1 is ejected and scattered, and the thick resist R2 portion and the resist R in the vicinity of the opening of the through-hole 33 are dragged when the resist R1 expands to produce a thin resist R3 portion.
The state of the resist film thickness variation is not limited to the state shown in the figure. For example, it varies depending on the pre-baked state and how the resist enters the through-hole 33.

On the other hand, FIG. 7 shows a state in which the resist R for forming the wiring pattern 35 is temporarily baked by a photolithography process when the stepped portion 38 having the edge 39 is formed on the inner surface of the through-hole 33. The schematic sectional drawing showing was shown.
FIG. 7A shows a state after the resist R is applied and before temporary baking. (B) has shown the state at the time of temporary baking.

In FIG. 7A, the resist R has entered the inner surface of the through hole 33 including the stepped portion 38. In the figure, bubbles B are generated near the bottom of the through-hole 33.
Note that the resist R does not have to penetrate to the bottom.

  In FIG. 7B, when the wiring patterns 35 and 37 are formed on the bonding substrate 30 by the photolithography process, the resist R that has entered and penetrated through the through-hole 33 becomes the bubble B in the preliminary baking step of the resist R. Expands to the outside from the through-hole 33 and ruptures and ejects at the stepped portion 38 formed on the inner surface of the through-hole 33, so that it scatters into the through-hole 33 and is applied onto the bonding substrate 30. Further, scattering to the resist R can be reduced. Accordingly, the film thickness of the applied resist R can be kept uniform, the wiring patterns 35 and 37 can be accurately formed in the subsequent steps, and wiring pattern abnormalities such as wiring breakage can be reduced. The reliability of the recording apparatus 1000 can be improved.

  (2) The resist R4 that the bubble B expands in the through hole 33 and goes to the outside from the through hole 33 can be easily ruptured and ejected by the step portions 381, 382, and 383 on the inner surface of the through hole 33. The influence on the applied resist R can be reduced.

  (3) By the edges 391 and 392, the bubble B expands in the through hole 33 and the resist R4 that goes to the outside from the through hole 33 can be cut. It becomes easy to eject, and the influence on the resist R applied on the bonding substrate 30 can be reduced.

(Modification)
FIG. 8 is a plan view of an ink jet recording head according to a modification.
In FIG. 8, two through holes 33A and 33B are provided corresponding to the row 13 of each pressure generating chamber 12, and a beam portion 34A is also formed between the two through holes 33A and 33B. That is, on the bonding substrate 30, two drive ICs 110 </ b> A and 110 </ b> B are mounted in a region facing the row 13 of each pressure generation chamber 12, and a total of four drive ICs 110 are mounted. And through-holes 33A and 33B are provided corresponding to each drive IC 110, and the beam portion 34A is integrally formed by the same member as the bonding substrate 30 between these two through-holes 33A and 33B. This is the same as the embodiment.
Even with such a configuration, the same effect as the embodiment can be obtained.

Various modifications other than the modified examples can be made.
For example, in the above-described embodiment, the bonding substrate 30 having the piezoelectric element holding unit 31 is exemplified as the bonding substrate, but the bonding substrate is not particularly limited as long as the driving IC is mounted thereon.
Moreover, those skilled in the art can make various modifications in other detailed matters such as the shape of the stepped portion, the material to be used, and the like.

1 is a schematic perspective view showing an ink jet recording apparatus according to an embodiment. FIG. 3 is an exploded partial perspective view showing an ink jet recording head. (A) is a fragmentary top view of an inkjet recording head, (b) is AA sectional drawing in (a). The expanded sectional view of the through-hole vicinity. (A) And (b) is a figure showing the shape in which the edge is formed in the through-hole inner surface, (c) represents the shape in which the protrusion is formed in the through-hole inner surface. (A) is a figure which shows the state at the time of temporary baking after application | coating of a resist, and the state before temporary baking in the case where the level | step-difference part is not formed in a through-hole. (A) is a figure which shows the state before a temporary baking after application | coating a resist, when the level | step-difference part is formed in the through-hole, (b) is a figure which shows the state at the time of temporary baking. The top view of the ink jet type recording head concerning a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Flow path formation board | substrate, 12 ... Pressure generating chamber, 13 ... Row, 21 ... Nozzle opening, 30 ... Bonding board, 33 ... Through-hole, 34, 34A ... Beam part, 35, 37 ... Wiring pattern, 38, 381, 382, 383: Stepped portion, 39, 391, 392 ... Edge, 50 ... Elastic film as diaphragm, 90 ... Lead electrode as extraction electrode, 110, 110A, 110B ... Drive IC, 300 ... Piezoelectric element, 1000 ... Liquid An ink jet recording apparatus as an ejecting apparatus.

Claims (4)

A flow path forming substrate having a plurality of rows of pressure generating chambers respectively communicating with the nozzle openings;
A piezoelectric element provided on one side of the flow path forming substrate in correspondence with the pressure generating chamber via a vibration plate;
A bonded substrate bonded to the pressure element side of the flow path forming substrate;
A driving IC disposed on the bonding substrate and driving the piezoelectric element;
A through hole in which one or a plurality of pressure generating chambers corresponding to each row of the pressure generating chambers is provided in a region corresponding to the pressure generating chambers of the bonding substrate, and a lead electrode drawn from the piezoelectric element is exposed. When,
A beam portion formed between adjacent through holes;
A wiring pattern on which the driving IC is mounted on the bonding substrate,
A step part extending along the row of the pressure generating chambers is formed on the inner surface of the through hole and the beam part. The liquid ejecting head according to claim 1,
The step portion is a protrusion. The liquid ejecting head according to claim 1, wherein
An edge is formed in the stepped portion. A liquid ejecting head, wherein: A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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