JP2014004721A - Liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance strength of a wall portion forming pressure chambers while relaxing a temperature rise in a liquid discharge head.SOLUTION: A liquid discharge head 1 includes: a liquid discharge block 3 including a plurality of pressure chambers 12 capable of storing liquid, a plurality of air chambers 13a and 13b disposed around the plurality of pressure chambers 12, and a wall portion forming at least the pressure chamber 12, which is made of a piezoelectric material; and a flow passage 14 including an inlet and an outlet which are provided on the same surface of the liquid discharge block 3, and a portion between the inlet and the outlet, which is routed around in the liquid discharge block 3.

Description

  The present invention relates to a liquid discharge head that discharges liquid.

  A general ink jet recording apparatus is equipped with a liquid discharge head for discharging ink onto a recording medium in order to record an image.

  Patent Document 1 discloses a liquid discharge head provided with a cooling dedicated flow path for adjusting the temperature of the liquid (ink). This liquid discharge head uses a part of a plurality of parallel grooves provided in the piezoelectric material plate as an ink flow path, and the other part as a cooling dedicated flow path through which a temperature-controlled cooling dedicated fluid flows. It is.

  Patent Document 2 discloses a configuration in which a cylindrical ink discharge portion (piezoelectric element) made of a piezoelectric material is provided, and a hollow portion inside the cylindrical ink discharge portion is a pressure chamber. In this configuration, the cylindrical ink discharge portion constitutes a wall portion that forms a pressure chamber. Then, when the voltage is applied and the ink discharge portion (each wall portion) is deformed, the volume of the pressure chamber is reduced, and the ink in the pressure chamber is discharged to the outside.

  As an example of a method for forming this pressure chamber, a plurality of piezoelectric substrates formed with a plurality of grooves extending in the same direction are stacked with the groove directions aligned, and the stacked piezoelectric substrates are stacked in a direction perpendicular to the grooves. There is a method of cutting and using each groove as a pressure chamber. In this case, a plate-shaped unit laminate in which pressure chambers are arranged in a matrix is formed. In this unit laminate, separation grooves are formed so as to surround each of the pressure chambers arranged in a matrix, and a plurality of cylindrical ink discharge portions are substantially separated and independent. .

JP 2011-235480 A JP 2007-168319 A

  In the liquid discharge head disclosed in Patent Document 1, a part of each wall of the groove-shaped ink flow paths arranged in a row is piezoelectrically deformed to discharge the ink in the ink flow path to the outside. However, in the case of discharging high-viscosity ink or the like that has been required with the recent increase in image quality of recording, the ink discharge force is insufficient. In Patent Document 1, it is not assumed that the ink flow paths and the ejection openings are arranged in a two-dimensional matrix, and the ink droplets can be ejected only one by one. It is difficult to deal with

  On the other hand, in the liquid discharge head disclosed in Patent Document 2, the ink discharge portions are arranged in a two-dimensional matrix, and high density is realized. However, since the individual ink discharge portions are formed in a cylindrical shape substantially separated by the separation groove and are arranged with high density, the wall portion forming the pressure chamber of each ink discharge portion is thin, and the ink discharge portion The durability is low. When ejecting highly viscous ink, it is necessary to increase the ejection force of ink in the pressure chamber. For this purpose, the length of the pressure chamber must be increased. However, if the length of the ink discharge portion is increased in order to increase the length of the pressure chamber, the length of the thin wall portion is increased, and the durability is further reduced. For this reason, there is a risk that the wall portion of the ink discharge portion may be damaged and the ink cannot be discharged due to vibration generated during recording on the recording medium or deformation of the ink discharge portion (pressure chamber contraction) repeated to discharge the ink. is there.

  Further, in the invention disclosed in Patent Document 2, it is necessary to form separation grooves around the pressure chambers located in a matrix in order to form each ink discharge portion in a substantially independent cylindrical shape. is there. Accordingly, there is a separation groove between adjacent ink discharge portions, and there is a limit to narrowing the separation groove in a normal forming method such as cutting by sandblasting. Hinder.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid discharge head that solves the above-described problems and can increase the strength of a wall portion that forms a pressure chamber while mitigating an internal temperature rise.

  The liquid discharge head of the present invention has a plurality of pressure chambers capable of storing liquid and a plurality of air chambers arranged around the plurality of pressure chambers, and at least a wall portion forming the pressure chambers is made of a piezoelectric material. A liquid ejection block, and an inlet and an outlet provided on the same surface of the liquid ejection block, and a portion between the inlet and the outlet has a flow path routed around the liquid ejection block.

  According to the present invention, an increase in internal temperature can be mitigated without increasing the liquid discharge block constituting the liquid discharge head, and the rigidity of the structure around the pressure chamber can be increased.

It is the disassembled perspective view which looked at the liquid discharge head of one Embodiment of this invention from the nozzle plate side. FIG. 2 is an exploded perspective view of the liquid discharge head shown in FIG. 1 as viewed from the manifold side. FIG. 2A is a perspective view of a first piezoelectric substrate of the liquid ejection head shown in FIG. 1, and FIG. 2B is a perspective view of a second piezoelectric substrate. (A) is a perspective view seen from the liquid supply side showing the manifold of the liquid ejection head shown in FIG. 1, (b) is a perspective view seen from the liquid outlet side, and (c) is a liquid with its mounting plate omitted. It is the perspective view seen from the supply side. FIG. 2 is a perspective view showing a cooling unit of the liquid discharge head shown in FIG. 1. FIG. 2 is a plan view showing a first piezoelectric substrate of the liquid discharge head shown in FIG. 1. (A)-(h) is a perspective view which shows the process process of the 1st piezoelectric substrate shown in FIG. 6 in order. (A)-(h) is a perspective view which shows the detail of the electrode formation process schematically shown to FIG.7 (d)-(e) in order. FIG. 4 is a plan view of a second piezoelectric substrate of the liquid ejection head shown in FIG. 1. (A)-(e) is a perspective view which shows the process process of the 2nd piezoelectric substrate shown in FIG. 9 in order. (A)-(d) is a perspective view which shows the detail of the electrode formation process schematically shown to FIG.10 (c)-(d) in order. FIG. 2 is a perspective view of a liquid discharge block of the liquid discharge head shown in FIG. 1 as viewed from a supply side. (A)-(d) is a top view which shows the electrode formation process of the supply side edge part of the liquid discharge block shown in FIG. 12 in order. It is a top view which shows the electrode pattern of the front-end surface of the liquid discharge block shown in FIG. It is the perspective view which looked at the liquid discharge block shown in FIG. 12 from the discharge side. (A)-(d) is a top view which shows the electrode formation process of the discharge side edge part of the liquid discharge block shown in FIG. 15 in order.

  A liquid discharge head according to an embodiment of the present invention will be described with reference to the drawings. A liquid discharge head 1 according to this embodiment shown in FIGS. 1 and 2 includes a nozzle plate 2, a liquid discharge block 3, a rear throttle plate 4, and a manifold 5. The nozzle plate 2 is joined to the front surface of the liquid discharge block 3 (discharge side end which is a liquid discharge side), and the rear throttle plate 4 and the manifold 5 are connected to the back surface (supply side end which is a liquid supply side). Are joined. In FIGS. 1 and 2, the structure of the liquid discharge block 3 and the manifold 5 is shown in an exploded manner for easy understanding, and in particular, the manifold 5 is shown in a shape with details omitted.

  The nozzle plate 2 is formed with a plurality of discharge ports 6 that are circular through holes, and these discharge ports 6 are arranged in a two-dimensional matrix at predetermined intervals. In an example, the thickness of the nozzle plate 2 is 17 μm, and the diameter of each discharge port 6 is 10 μm.

  The rear diaphragm plate 4 includes a diaphragm opening 7 serving as a flow path when supplying liquid (ink) from the manifold 5 to the liquid ejection block 3. A plurality of throttle openings 7 are provided corresponding to pressure chambers of the liquid discharge block 3 to be described later. Further, the rear throttle plate 4 includes a cooling fluid supply port 8 and a cooling fluid recovery port 9 that serve as a flow path for supplying and recovering the cooling fluid from the manifold 5 to the liquid discharge block 3. A plurality of cooling fluid supply ports 8 and cooling fluid recovery ports 9 are provided facing the cooling liquid flow path of the liquid discharge block 3 and are arranged alternately. In one example, the rear diaphragm plate 4 has a thickness of 200 μm, the diaphragm opening 7 has a rectangular shape of 50 μm × 50 μm, and the cooling fluid supply port 8 and the cooling fluid recovery port 9 have a rectangular shape of 120 μm × 120 μm. .

  The liquid discharge block 3 includes a stacked body in which a plurality of first piezoelectric substrates 10 shown in FIG. 3A and a plurality of second piezoelectric substrates 11 shown in FIG. 3B are alternately stacked. Both the first piezoelectric substrate 10 and the second piezoelectric substrate 11 are made of a piezoelectric material. The first piezoelectric substrate 10 includes a plurality of concave grooves constituting the pressure chambers 12 capable of storing liquid and a plurality of concave grooves constituting the air chambers 13 a formed on both sides of each pressure chamber 12. Is formed. The grooves constituting the pressure chamber 12 are grooves having openings at both ends that penetrate the first piezoelectric substrate 10 from the discharge side end portion 104 to the supply side end portion 103. The groove constituting the air chamber 13a is a groove whose one end is opened at the supply-side end portion 103 but whose other end is closed by the discharge-side end portion 104 of the first piezoelectric substrate 10 and whose one end is opened. It is. On the other hand, the second piezoelectric substrate 11 is formed with a plurality of concave grooves constituting the air chambers 13b and concave grooves constituting the cooling fluid passages 14 arranged alternately with the air chambers 13b. Yes. Each of the groove constituting the air chamber 13 b and the groove constituting the cooling fluid flow path 14 is open at one end at the supply side end 102 of the second piezoelectric substrate 11, but the other end is at the discharge side end 101. It is a groove that is closed at one end and is open at only one end. The grooves constituting the cooling fluid flow path located on both sides of the groove constituting the air chamber 13b are 2 by the communication groove 15 on the discharge side end 101 side rather than the other end of the groove constituting the air chamber 13b. Each one is connected to each other.

  The first piezoelectric substrate 10 and the second piezoelectric substrate 11 are laminated with each other, and the groove forming surface of the first piezoelectric substrate 10 is formed by the flat surface of the second piezoelectric substrate 11 (the surface opposite to the groove forming surface). Covered. The groove forming surface of the second piezoelectric substrate 11 is covered with a flat surface (a surface opposite to the groove forming surface) of another first piezoelectric substrate 10. In this manner, the pressure chamber 12 having both ends positioned on the front end surfaces 101 and 104 and the rear end surfaces 102 and 103 of the piezoelectric substrates 10 and 11 is formed by the concave grooves constituting the air chamber 13b. Air in which only one end located at the rear end surfaces 102 and 103 of the piezoelectric substrates 10 and 11 is opened by the grooves constituting the air chamber 13a, the grooves constituting the air chamber 13b, and the grooves constituting the cooling fluid flow path 14, respectively. A chamber 13a, an air chamber 13b, and a cooling fluid flow path 14 are formed.

  In this way, the top plate 16 (upper plate) is laminated on the uppermost part of the laminate formed by alternately laminating the first piezoelectric substrate 10 and the second piezoelectric substrate 11, and the bottom plate 17 (lower part) on the lowermost part. Plate) is disposed to form the liquid ejection block 3. The top plate 16 and the bottom plate 17 do not need to be formed of a piezoelectric material, but are desirably formed of a material having a thermal expansion coefficient close to that of the first piezoelectric substrate 10 and the second piezoelectric substrate 11. In the liquid discharge block 3, air chambers 13 a and 13 b are located in four directions (up, down, left and right) around the pressure chamber 12. Similarly, air chambers 13a and 13b are located in the four directions (up, down, left and right) around the cooling fluid flow path 14. Electrodes are formed on the inner walls of the pressure chamber 12 and the air chambers 13a and 13b. The cooling fluid flow path 14 has an inlet and an outlet that open to the supply side end of the liquid ejection block 3, and a portion between the inlet and the outlet is routed around the liquid ejection block 3. .

  In the present embodiment, a manifold 5 for supplying liquid (ink) and supplying and recovering cooling fluid is attached to the supply side end of the liquid discharge block 3 via the rear throttle plate 4. . As shown in FIGS. 4A to 4C, on the liquid supply side (the side opposite to the liquid discharge block 3) of the mounting plate 18 of the manifold 5, there is an opening (liquid supply) for circulating liquid or cooling fluid. There is a cylindrical member having a port 19, a cooling fluid supply port 21, and a cooling fluid recovery port 24). On the liquid discharge block 3 side of the mounting plate 18, a flow path (liquid supply flow path 20, cooling fluid supply flow) communicating with the throttle opening 7 of the rear throttle plate 4, the cooling fluid supply port 8, and the cooling fluid recovery port 9. A member having a passage 22 and a cooling fluid recovery passage 23) is provided. This flow path circulates a liquid or a cooling fluid.

  Further, the nozzle plate 2 is attached to the discharge side end of the liquid discharge block 3 to form the liquid discharge head 1 of the present embodiment.

  Further, a cooling unit shown in FIG. 5 is attached to the liquid discharge head 1. The cooling unit is for circulating the cooling fluid mainly in the liquid discharge block 3 of the liquid discharge head 1 to cool the liquid discharge head 1. The cooling unit includes a pump 30 and a temperature control unit 31 located between the pump 30 and the liquid discharge block 3. The outlet 203 of the pump 30 is connected to the inlet 204 of the temperature control unit 31 by the connection tube 32, and the outlet 201 of the temperature control unit 31 is connected to the cooling fluid supply port 21 of the liquid discharge block 3. The inlet 202 of the pump 30 is connected to the cooling fluid recovery port 24 of the liquid discharge block 3.

  The flow of liquid (ink) and cooling fluid in the liquid discharge head 1 will be described. The recording liquid, that is, the flow of ink will be described. First, liquid is supplied to the manifold 5 from a tank or the like (not shown) through the liquid supply port 19 shown in FIGS. The liquid flows from the liquid supply port 19 through the liquid supply flow path 20, further through the throttle opening 7 of the rear throttle plate 4, and flows into each pressure chamber 12 of the liquid discharge block 3. Thus, in a state where the liquid flows into and is stored in the pressure chamber 12, the electrode on the inner wall of the pressure chamber 12 and the electrode on the inner wall of the air chamber 13a, or the electrode on the inner wall of the pressure chamber 12 and the air chamber. When a voltage is applied between the electrodes on the inner wall of 13b, the wall located between these electrodes deforms and expands. When a voltage is applied and each wall forming the pressure chamber 12 is deformed in a convex shape toward the inner side (center side of the pressure chamber 12), the volume of the pressure chamber 12 is reduced and the liquid inside is pressurized. Then, a droplet (ink droplet) is ejected from the ejection port 6 to the outside.

  In this embodiment, each electrode formed on the inner wall of the pressure chamber 12 is individually connected to one wiring pattern, and all the electrodes formed on the outer wall of each pressure chamber 12 (the inner walls of the air chambers 13a and 13b) are all. They are connected to each other and connected to a common wiring. By applying a drive signal to the wiring individually connected to the electrodes formed on the inner wall of the pressure chamber 12, the walls of each pressure chamber 12 are driven independently. A wiring pattern connected to the electrode formed on the inner wall of the pressure chamber 12 is formed at the discharge side end of the liquid discharge block 3. Thereby, electrical driving of the pressure chamber 12 and heat dissipation of heat generated by driving the pressure chamber 12 can be realized without enlarging the liquid discharge block 3 itself. And according to this embodiment, the air chambers 13a and 13b exist between the pressure chambers 12, and the wall parts forming the pressure chamber 12 are connected to each other. Therefore, it is possible to increase the rigidity of the wall portion of the pressure chamber 12 as compared with a structure in which the wall portions forming the pressure chamber 12 are substantially separated and separated from each other.

  On the other hand, when the pump 30 shown in FIG. 5 is operated, the cooling fluid is supplied to the cooling fluid supply port 21 and enters the manifold 5 through the connection tube 32 and the temperature control unit 31. This cooling fluid passes through the cooling fluid supply passage 22 (see FIG. 4) and the cooling fluid supply port 8 (see FIGS. 1 and 2) of the rear throttle plate 4 to cool the liquid discharge block 3. It is supplied to the fluid flow path 14. This cooling fluid further passes through another cooling fluid flow path 14 communicating via the communication groove 15 shown in FIG. 3B, and cools the liquid discharge block 3 as a whole. Then, the cooling fluid flows from the other cooling fluid channel 14 through the cooling fluid recovery port 9 of the rear throttle plate 4 into the cooling fluid recovery channel 23 (see FIG. 4) of the manifold 5. . The cooling fluid that has flowed into the cooling fluid recovery passage 23 (see FIG. 4) of the manifold 5 passes through the cooling fluid recovery port 24 and is recovered from the inlet 202 to the pump 30. In the cooling fluid circulation path, for example, the temperature control unit 31 including a Peltier element functions to measure the temperature of the cooling fluid and maintain the cooling fluid at a predetermined temperature.

[Temperature control method]
The fact that sufficient temperature control of the liquid ejection block 3 is possible in the present embodiment will be described in detail below. First, the heat generation amount P due to the dielectric loss of the drive region of the liquid ejection block 3, that is, the wall portion forming the pressure chamber 12, is expressed by the following equation.

Here, assuming that the drive frequency f is 50 kHz, the dielectric constant ε is 1.5 × 10 ⁻⁸ F / m, the thickness d of the wall portion made of piezoelectric material is 120 μm, and the applied electric field E is 714 kV / m, the dielectric loss When tan δ is 0.32%, the heat generation amount P is about 460 W / m ² .

  On the other hand, the heat transfer coefficient α of forced convection in a plate having a uniform temperature is expressed by the following equation.

Here, the flow velocity u of water as a cooling fluid is 0.04 m / s, the density ρ of water is 996 kg / m ³ , the specific heat C _p of water is 4177 J / Kg · K, and the thermal conductivity λ is 0.6104 W / m · K, representative length L is 5.15 mm, and kinematic viscosity coefficient ν is 8.57 × 10 ⁻⁷ m ² / s. At this time, the heat transfer coefficient α is 2198 W / m ² · K.

The cooling fluid in the cooling fluid flow path 14 absorbs heat generated by the wall portion of the pressure chamber 12 located around the cooling fluid flow path 14. That is, since there are four pressure chambers 12 around the cooling fluid flow path 14 and each pressure chamber has four wall portions, assuming that the heat generation area and the heat absorption area are the same, 4 × 4. X460 = 7360 W / m ² The heat generation amount is absorbed with a heat transfer coefficient of 2198 W / m ² · K. The temperature rise of the water due to this is 3.35 K, and the temperature rise due to the dielectric loss in the drive region of the first piezoelectric substrate 10 and the second substrate 11 can be suppressed to a small level. As described above, according to this embodiment, the temperature of the first piezoelectric substrate 10 and the second piezoelectric substrate 11 and the liquid (ink) to be ejected are effectively controlled by controlling the temperature of the cooling fluid. can do.

[Liquid discharge head manufacturing method]
Next, the main part of the manufacturing method of the liquid discharge head 1 (mainly, the electrode forming step and the polarization step of the first piezoelectric substrate 10 and the second piezoelectric substrate 11, and the electrode forming step of the liquid discharge block 3) ).

(Formation of the first piezoelectric substrate)
In this embodiment, the substrate block 501 shown in FIG. 6 is formed and then divided to obtain five first piezoelectric substrates 10. The first piezoelectric substrate 10 has five pressure chambers 12 and six air chambers 13a. However, for the sake of convenience, FIGS. 7 to 8 show only a portion corresponding to one first piezoelectric substrate 10 (a portion where five pressure chambers 12 and six air chambers 13a are formed).

(Grooving process)
First, as shown in FIG. 7A, a flat first substrate block 501 having a desired thickness and shape is prepared. As an example, a plate material made of PZT (lead zirconate titanate) and having dimensions of 19 mm × 70 mm × 0.24 mm. Then, the first exposure alignment groove 514 shown in FIG. 6 is formed in the first substrate block 501 by grinding with a superabrasive wheel. The first exposure alignment groove 514 may be formed by positioning based on the distance from the end surface of the first substrate block 501. The first exposure alignment groove 514 may be positioned by using a metal pattern or the like previously formed by photolithography as a mark. It may be formed.

  Subsequently, as shown in FIG. 7B, a plurality of first grooves 503 are formed on the first substrate block 501 with the first exposure alignment groove 514 as a reference. A part of the first groove 503 functions as the pressure chamber 12. In the present embodiment, the first groove 503 is formed by grinding using a superabrasive wheel (not shown), and the superabrasive wheel is pulled up above the first substrate block 501 during the grinding process. Thus, a groove portion that is not in communication is formed on one end face. In other words, the first groove 503 is open on the first end surface 804 of the first substrate block 501, but is closed without opening on the second end surface 805. As an example, the width of the first groove 503 is 0.12 mm, the depth is 0.12 mm, and the pitch is 0.706 mm (the number of nozzles per inch (2.54 cm) is 36 npi). Although omitted in FIG. 7, the first groove 503 located on the outermost side shown in FIG. 6 can function as an adhesive escape groove in a subsequent bonding step. In addition, as shown in FIG. 6, a first bonding alignment groove 513 is formed in order to serve as an alignment mark in the subsequent chip stacking process.

  Further, as shown in FIG. 7C, second grooves 504 are formed on both sides of each first groove 503 of the first substrate block 501. A part of the second groove 504 functions as the air chamber 13a. The second grooves 504 are formed on both sides of the first grooves 503, and the first grooves 503 and the second grooves 504 are alternately arranged. As an example, the width of the second groove 504 is 0.346 mm, the depth is 0.14 mm, and the distance between the first groove 503 and the second groove 504 is 0.12 mm. The second groove 504 is closed without opening at the first end surface 804 of the first substrate block 501, and is open at the second end surface 805.

(Electrode formation process)
Next, as shown in FIG. 7D, the first electrode 505 is formed on the inner surface of the first groove 503, and the second electrode 506 is formed on the inner surface of the second groove 504, respectively. The first electrode 505 is a signal electrode (SIG), and the second electrode is a ground electrode (GND). These electrodes 505 and 506 are patterned by a method such as lift-off, laser, and polishing.

  As an example, FIG. 8 shows an electrode patterning method by lift-off. First, a film resist 902 is laminated on the surface of the first substrate block 501 as shown in FIG. 8A, which is a cross-sectional view taken along the line A-A 'of FIG. Since the surface of the first substrate block 501 subjected to the groove processing has irregularities, it is difficult to form a uniform resist film by an ordinary spin coater coating method. Therefore, laminating the film resist 902 or coating with a spray coater is suitable. Further, since it is difficult to uniformly expose the inside of each groove, it is preferable to use a negative type film resist 902 that only needs to expose the outside of the groove. Further, if the first substrate block 501 is a sintered body, voids having a size of about 10 μm are scattered. Therefore, if the film resist 902 is too thin, a pattern defect occurs in the film resist above the voids. Therefore, the film resist 902 preferably has a sufficient thickness, for example, 40 μm or more.

  Next, as shown in FIG. 8B, exposure and development are performed to pattern the film resist 902. In the lift-off, the film resist 902 is patterned by photolithography so that the resist remains in a portion where the electrode pattern is not desired to be left. At this time, it is preferable that the pattern width of the film resist 902 be made smaller than the width of the side wall so that a metal layer is formed on the entire side wall of the groove in a later step. For example, while the width of the side wall of the groove is 0.12 mm, the pattern width of the film resist 902 is set to 0.06 mm.

  As shown in FIG. 8C, a metal layer serving as an electrode is formed on the entire surface of the first substrate block 501 including the portion where the patterned film resist 902 is present by sputtering or vapor deposition. Sputtering is excellent in film formation on the side wall of the groove, and vapor deposition is excellent in patterning at lift-off. Then, as shown in FIG. 8D, by removing the film resist 902, the metal film is patterned into a desired shape to form an electrode. Specifically, for example, an electrode layer made of Au having a thickness of about 1000 nm may be formed on an underlayer made of Cr having a thickness of about 20 nm to form an electrode. Alternatively, after forming a base layer made of Cr having a thickness of about 20 nm and Pd having a thickness of about 50 nm thereon and patterning, and forming a Ni plating layer having a thickness of about 1000 nm using Pd as a seed layer, The electrode can also be formed by substitution plating of Ni on the surface with Au. According to the latter method, since the film thickness at the time of lift-off is thin, the burrs hardly remain and the patterning property is improved. In addition, Au is formed only on the patterned part of the surface, so that the cost is low. However, the electrodes can also be formed using laser or polishing. In that case, a metal film is formed on the entire surface of the first substrate block 501 by a method such as sputtering, vapor deposition, or electroless plating. In this case, a metal film is also formed on the first and second end faces 804 and 805 of the first substrate block 501. Then, an unnecessary portion of the formed metal film, that is, a portion of the metal film other than the first and second grooves 503 and 504 on the surface of the first substrate block 501 is removed by laser or polishing. Then, an electrode pattern having a desired shape is obtained. Thus, the first electrode 505 formed on the inner surface of the first groove 503 constituting the pressure chamber 12 is a signal electrode, and the second electrode formed on the inner surface of the second groove 504 forming the air chamber 13a. The electrode 506 is a ground electrode. The first electrodes 505 are electrically connected via a metal film formed on the first end surface 804, and the second electrodes 506 are electrically connected via a metal film formed on the second end surface 805. Yes.

  Next, the back surface of the first substrate block 501 that is the surface opposite to that shown in FIGS. 7A to 7D (the surface opposite to the surface on which the first and second grooves 503 and 504 are formed). A metal film is formed on the substrate, and third electrodes (first and second common wirings 802 and 803) are formed (see FIG. 7E). The first common wiring 802 and the second common wiring 803 are patterned by lift-off or etching using photoresist photolithography, cutting such as laser, grinding, and milling. Accordingly, the first common wiring 802 and the second common wiring 803 are divided in a direction perpendicular to the longitudinal direction of the first groove 503 and the second groove 504. Specifically, a resist 903 is formed on the back surface of the first substrate block 501 as shown in FIG. 8E, which is a cross-sectional view taken along the line BB ′ in FIG. As shown in FIG. 8F, the resist 903 is patterned. Thereafter, after forming a metal layer as shown in FIG. 8G, the resist 903 is removed as shown in FIG. The remaining metal layers are the first common wiring 802 and the second common wiring 803. The first common wiring 802 is electrically connected to the first electrode 505 through an end surface 804 where the first groove 503 is open. On the other hand, the second common wiring 803 is electrically connected to the second electrode 506 through the end face 805.

  Since the back surface of the first substrate block 501 is not uneven, it is not limited to the above-described film resist lamination or spray coater coating, and a uniform resist film can be formed by ordinary spin coating resist coating. is there. Also, as a method of forming the first and second common wirings 802 and 803, a thicker metal layer is formed by plating Pd, which is formed and patterned as a part (upper layer) of the base layer, as a seed layer. An electrode can be formed.

(Polarization process)
Next, the first substrate block 501 is polarized in three different directions on each wall surface forming the first groove 503 (pressure chamber 12). For example, a high electric field is applied between the electrodes 505 and 506 as shown in FIG. 7F, with the first electrode 505 being a positive potential and the second electrode 506 being a ground potential. For example, a high electric field of about 1 to 2 kV / mm is applied for a predetermined time between the electrodes 505 and 506 while being heated to about 100 to 150 ° C. At this time, since the first and second common wirings 802 and 803 formed on the back surface of the first substrate block 501 have a large pattern size, they should be connected to a power supply device that generates a high electric field and used as an electrode pad. Can do. The distance between the electrodes on each wall surface forming the first groove 503 (pressure chamber 12) is narrow (for example, 0.06 mm). When a high electric field of 1 to 2 kV / mm is applied in air, air discharge or creeping discharge is applied. Is likely to occur. Therefore, it is desirable to perform the polarization process in a state where the first substrate block 501 is inserted in a highly insulating oil such as silicone oil (dielectric breakdown voltage: 10 kV / mm or more). Silicone oil can be removed after the polarization step by using a hydrocarbon solvent such as xylene, benzene, or toluene, or a chlorinated hydrocarbon solvent such as methylene chloride, 1.1.1-trichloroethane, or chlorobenzene.

  If necessary, an aging process for stabilizing the piezoelectric characteristics is performed by holding the first substrate block 501 subjected to the polarization process in a heated state for a certain period of time after the polarization process. For example, as the aging process, for example, the first substrate block 501 subjected to the polarization process is placed in an oven at 100 ° C. and left for 10 hours.

(Chip separation process)
As shown in FIG. 7G, the first substrate block 501 is cut by a method such as grinding, polishing, or laser ablation, and both ends of the first groove 503 are opened to be used as the pressure chamber 12. . In the chip separation step, the second common electrode on the second end surface 805 is also removed, so that the second electrode 506 in the second groove 504 and the second common wiring 803 on the back surface are electrically connected to each other. Separated and disconnected.

  Further, as shown in FIG. 7H, the first common wiring 802 on the first end face 804 is removed by a method such as grinding, polishing, or laser ablation. As a result, the first electrodes 505 in the first groove 503 are electrically separated from each other. Note that the second groove 504 does not open in the first end surface 804.

  Next, the first substrate block 501 shown in FIG. 6 is divided into five, the dimensions are 10 mm × 10 mm × 0.24 mm, the five pressure chambers 12 including the first grooves 503 are provided, the second The five first piezoelectric substrates 10 provided with six air chambers 13a each having the groove 504 are cut out.

  By the processing method described above, the polarization process can be performed in a state where the second groove 504 serving as the air chamber 13a does not open to the first side surface 804 of the first substrate block 501 (first piezoelectric substrate 10). .

[Processing of second piezoelectric substrate]
Further, as the second substrate block 502 for forming the second piezoelectric substrate, for example, a PZT substrate of 15 mm × 70 mm × 0.43 mm is prepared. In the present embodiment, as shown in FIG. 9, the second substrate block 502 is processed and then divided to obtain five second piezoelectric substrates 11. The second piezoelectric substrate 11 has five air chambers 13b, six cooling fluid flow paths 14, and three communication grooves 15 that connect two adjacent cooling fluid flow paths 14. . However, for convenience, in FIGS. 10 to 11, only a portion corresponding to one second piezoelectric substrate 11 (a portion in which five air chambers 13 b, six cooling fluid flow paths 14 and three communication paths 15 are formed). Is illustrated.

(Polarization process)
As described above, the first substrate block 501 that forms the first piezoelectric substrate 10 is subjected to the polarization process after the groove processing step (see FIG. 7F), but the second substrate that forms the second piezoelectric substrate 11 is formed. The substrate block 502 performs polarization processing in the state of a flat plate before the groove processing step. In the polarization treatment, electrodes are formed on the front and back surfaces of the second substrate block 502, respectively, and a high electric field of about 1 to 2 kV / mm is applied between the electrodes for a predetermined time while being heated to about 100 to 150 ° C. Do by. By the polarization process, the second substrate block 502 is uniformly polarized in a direction perpendicular to the main plane. The polarization treatment of the second substrate block 502 may be performed in insulating oil as in the first substrate block 501, or may be performed in the air. After the polarization treatment, the electrode on the surface of the second substrate block 502 is removed by etching or polishing.

(Grooving process)
First, the second substrate block 502 is ground with a superabrasive wheel to form second exposure alignment grooves 516 (see FIG. 9). The second exposure alignment groove 516 may be formed by positioning based on the distance from the end surface of the second substrate block 502, or may be positioned using a metal pattern or the like previously formed by photolithography as a mark. It may be formed. Subsequent groove processing steps are performed using the second alignment groove for exposure 516 as a reference.

  As shown in FIG. 10A, a plurality of third grooves 507 and a plurality of fourth grooves 508 are formed in the second substrate block 502. A part of the third groove 507 becomes an air chamber 13b arranged at a position overlapping the pressure chamber 12 when seen in a plan view, and the fourth groove 508 functions as the cooling fluid flow path 14. In the present embodiment, the third and fourth grooves 507 and 508 are formed by grinding using a superabrasive wheel (not shown), and the superabrasive wheel is placed above the substrate block 502 during the grinding process. The groove part which is not connected to one end face is formed. That is, the third and fourth grooves 507 and 508 are configured such that one end face of the second substrate block 502 is closed without opening, and only the other end face is opened. The fourth groove 508 is longer in the longitudinal direction than the third groove 507. As an example, the width of the third groove 507 is 0.20 mm, the depth is 0.31 mm, and the pitch is 0.706 mm (the number of nozzles per inch (2.54 cm) is 36 npi). The fourth groove 508 has a width of 0.266 mm, a depth of 0.31 mm, and a pitch of 0.706 mm (36 npi).

  Subsequently, as shown in FIG. 10B, a communication groove (fifth groove) 509 for communicating two adjacent fourth grooves 508 is formed by a method such as grinding, plasma etching, or laser ablation. The communication groove 509 functions as the communication path 15 of the cooling fluid flow path 14. In one example, the width of the communication groove 509 is 0.266 mm and the depth is 0.31 mm.

(Electrode formation process)
Next, as shown in FIG. 10C, a fourth electrode 510 serving as a ground electrode is formed on the inner surface (at least the bottom surface) of the third groove 507. The fourth electrode 510 is formed on at least the bottom surface of the third groove 507 and may be formed on the entire inner surface of the third groove 507. An electrode may also be formed on the upper surface of the side wall forming the third groove 507, but in that case, it is necessary to perform patterning to avoid a short circuit on the front end surface 807 or the like.

  The patterning of the fourth electrode 510 can be performed by a method such as lift-off, laser, or polishing. Examples of performing electrode patterning by lift-off are shown in FIGS. 11A to 11D are cross-sectional views taken along a line A-A ′ in FIG. First, as shown in FIG. 11A, a film resist 903 is laminated on the surface of the second substrate block 502. Since the surface of the second substrate block 502 subjected to the groove processing has irregularities, it is difficult to form a uniform resist film by an ordinary spin coater coating method. Therefore, lamination with a film resist 903 or application by a spray coater is suitable. Furthermore, since it is difficult to uniformly expose the inside of each groove, it is preferable to use a negative type film resist 903 that only needs to expose the outside of the groove.

  As shown in FIG. 11B, the film resist 903 is patterned by photolithography so that the resist remains in a portion where the electrode pattern is not desired to be left. Further, as shown in FIG. 11C, a metal layer is formed on the entire surface of the second substrate block 502 including the upper portion of the film resist 903 by sputtering or vapor deposition. And as shown in FIG.11 (d), the film resist 903 is removed and the metal film pattern of a desired shape is obtained. The method for forming the electrodes may be the same as the method for forming the first and second electrodes 505 and 506 on the second substrate block 501. Further, as shown in FIG. 10D, a fifth electrode (signal) made of a metal film is formed on the back surface of the second substrate block 502 (the surface opposite to the side where the third groove 507 is formed). Electrode) 512 is formed. The fifth electrode 512 is patterned so as to be divided along a direction parallel to the third groove 507 on the surface. The fifth electrode 512 is patterned by lift-off or etching using photoresist photolithography, or cutting such as laser, grinding, or milling. In particular, since there is no unevenness on the back surface of the second substrate block 502, a uniform resist film can be formed even by resist application by normal spin coating. Similarly to the case where the fourth electrode 507 is formed on the surface of the second substrate block 502, a resist is formed and patterned, and then a metal layer is formed and the fifth electrode is removed by removing the resist. 512 can be formed. As a method for forming the fifth electrode 512, an electrode made of a thicker metal layer is formed by plating Pd, which is formed and patterned as a part (upper layer) of the base layer, as a seed layer. You can also. The width of the fifth electrode pattern may be approximately the same as the width of the third groove, and may be set to, for example, approximately 0.18 mm in consideration of alignment errors during stacking or exposure.

(Chip separation process)
As shown in FIG. 10E, the second substrate block 502 is cut by a method such as grinding, polishing, or laser ablation. Even if a metal film is formed on the side wall of the second substrate block 502, it is removed by this process, so that the fifth electrodes 512 are electrically disconnected from each other. In the third groove 507 of the present embodiment, only one end is opened, and the other end is not opened. Next, similarly to the first substrate block 501, the second substrate block 502 shown in FIG. 9 is divided into five. As a result, the dimensions are 10 mm × 10 mm × 0.43 mm, and five air chambers 13b including third grooves 507 are connected to each other and two air channels 13b including fourth grooves 508 are connected to each other by the communication passage 15. Five second piezoelectric substrates 11 provided with six fluid flow paths 14 are cut out.

[Lamination of both piezoelectric substrates]
As described above, the liquid ejection block 3 is configured by stacking the first piezoelectric substrate 10 cut out from the first substrate block 501 and the second piezoelectric substrate 11 cut out from the second substrate block 502. In the liquid discharge block 3, a plurality of pressure chambers 12 are arranged in a matrix so as to face the plurality of discharge ports 6 of the nozzle plate 2. Air chambers 13a and 13b are disposed around the pressure chamber, and a cooling fluid flow path 14 is disposed on the side of the air chamber 13b.

[Rear end face electrode formation]
Next, as shown in FIG. 12, ground electrodes (second electrode 506, fourth electrode 510) provided in the air chambers 13 a, 13 b on the rear end surface (supply side end portion) 806 of the liquid discharge block 3. A wiring lead-out pattern 817 connected to () is formed. The ground-side wiring lead-out pattern 817 is routed from the rear end surface 806 to the upper end surface 808 of the liquid ejection block 3 and connected to a flexible substrate (FPC: Flexible Printed Circuits) at the ground-side mounting wiring connection portion 815. The wiring lead-out pattern 817 on the rear end face 806 is a cross-sectional view taken along the line AA ′ in FIG. 12 and a cross-sectional view taken along the line BB ′ in FIG. Is shown in

  Hereinafter, an example of a method for forming the wiring drawing pattern 817 by the lift-off method will be described. In the process of forming the wiring lead-out pattern 817, since the rear end surface 806 has irregularities such as the pressure chamber 12 and the air chamber 13a, it is difficult to form a uniform resist film using a normal spin coater. Laminate is suitable. Then, by photolithography, a film resist is formed so as to remain in the part where the electrode pattern is not desired, and a metal layer to be an electrode is formed on the entire rear end surface including the film resist by sputtering or vapor deposition. To do. And the metal film patterned by the desired shape is obtained by removing a resist.

  Specifically, first, a film resist 904 is laminated as shown in FIG. Next, as shown in FIG. 13B, exposure and development are performed to expose the air chambers 13a and 13b and their surroundings on the rear end face. At this time, the pressure chamber 12 and its periphery are kept covered with the film resist 904. Further, as shown in FIG. 13C, a metal layer that is electrically connected to the second electrode 506 (ground electrode) in the air chamber 13a is formed. At this time, by forming a metal layer after masking the upper end surface 808, a ground-side mounting wiring connection portion 815 that becomes a connection portion with the FPC can be formed. Next, as shown in FIG. 13D, by removing the film resist 904, lift-off is performed, and a wiring lead-out pattern 817 patterned into a desired shape can be obtained. As shown in FIG. 14, the wiring lead-out pattern 817 is electrically connected to the second electrode 506 in the air chamber 13a, but is not connected to the first electrode 505 in the pressure chamber 12. Not.

  As a method for forming a metal layer to be the wiring lead pattern 817, for example, Cr having a thickness of about 20 nm can be formed as a base layer, and Au having a thickness of about 1000 nm can be formed thereon as an electrode layer. Alternatively, Pd having a thickness of about 50 nm is formed on a Cr layer having a thickness of about 20 nm as a part (upper layer) of the base layer and patterned, and plating is performed using the Pd as a seed layer. Ni can be formed, and Ni can be replaced with Au. According to the latter method, since the film thickness at the time of lift-off is thin, the patterning property is improved, and Au is formed only on the patterned portion of the surface, so that the cost is low. In the example of the dimension (thickness) of each layer described above, there is a gap of about 1 to 2 μm between the piezoelectric substrates 10 and 11 due to the adhesive layer. It is thick enough to obtain a connection.

[Formation of front end electrode]
Next, as shown in FIG. 15, the wiring lead-out pattern connected to the signal electrode (first electrode 505) provided in each pressure chamber 12 on the front end face (discharge side end) 807 of the liquid discharge block 3. 816 is formed. The signal-side wiring lead-out pattern 816 is connected to a signal-side mounting wiring connection portion 814 formed on the front end surface 807 of the liquid ejection block 3, and is connected to an individual drive source via a flexible substrate (FPC). The A wiring lead-out pattern 816 on the front end surface 807 is shown in FIG. 16 which is a cross-sectional view taken along the line AA ′ in FIG.

  The method for forming the wiring lead pattern 816 on the front end surface 807 may be substantially the same as the method for forming the wiring lead pattern 817 on the rear end surface 806.

  Specifically, first, a film resist 905 is laminated as shown in FIG. Next, as shown in FIG. 16B, exposure and development are performed to expose the pressure chamber 12 and its periphery on the front end face. At this time, the pressure chamber 12 and its periphery are kept covered with the film resist 905. Further, as shown in FIG. 16C, a metal layer that is electrically connected to the first electrode 505 and the fifth electrode 512 (signal electrode) in the pressure chamber 12 is formed. Next, as shown in FIG. 16D, by removing the film resist 905, lift-off is performed, and a wiring lead-out pattern 816 patterned into a desired shape can be obtained. A method for forming a metal layer to be the wiring lead pattern 816 may be a film formation of an underlayer made of Cr having a thickness of about 20 nm and an electrode layer made of Au having a thickness of about 1000 nm. Alternatively, a base layer made of Cr having a thickness of about 20 nm and Pd having a thickness of about 50 nm is formed and patterned, and Ni having a thickness of about 1000 nm is formed by plating using Pd as a seed layer. Alternatively, replacement plating may be used.

DESCRIPTION OF SYMBOLS 1 Liquid discharge head 2 Nozzle plate 3 Liquid discharge block 6 Discharge port 10 1st piezoelectric substrate 11 2nd piezoelectric substrate 12 Pressure chamber 13a Air chamber 13b Air chamber 14 Cooling fluid flow path 30 Pump (cooling unit)
31 Temperature control unit (cooling unit)
503 1st groove | channel 504 2nd groove | channel 505 1st electrode 506 2nd electrode 507 3rd groove | channel 508 4th groove | channel 509 Communication groove | channel (5th groove | channel)
510 4th electrode 512 5th electrode 806 Rear end surface (supply side end)
807 Front end face (discharge end)
816 Signal side wiring lead pattern 817 Ground side wiring lead pattern

Claims (6)

A liquid discharge block having a plurality of pressure chambers capable of storing liquid, and a plurality of air chambers arranged around the plurality of pressure chambers, wherein at least a wall portion forming the pressure chamber is made of a piezoelectric material;
A liquid discharge head having an inlet and an outlet provided on the same surface of the liquid discharge block, and a channel between the inlet and the outlet is routed around the inside of the liquid discharge block .   The liquid discharge head according to claim 1, wherein a cooling fluid for cooling the liquid discharge block flows through the flow path.   The liquid discharge head according to claim 2, further comprising a cooling unit that supplies the cooling fluid to the inlet of the flow path and collects the cooling fluid from the outlet.   The liquid discharge block includes a first groove constituting a part of the wall portion forming the pressure chamber and a wall portion forming the air chamber formed alternately with the first groove. A plurality of first piezoelectric substrates having a second groove constituting a portion, a third groove forming a part of the wall portion of the air chamber, and the third groove are alternately arranged. And a plurality of second piezoelectric substrates having a fourth groove forming a part of the wall portion forming the flow path and a fifth groove communicating the two fourth grooves. The first groove is opened to each of a discharge side end portion that is a liquid discharge side of the liquid discharge block and a supply side end portion that is a side to which the liquid is supplied. The second groove, the third groove, and the fourth groove are open at the supply side end of the liquid discharge block. There is on the discharge side end portion is closed without opening, the liquid discharge head according to any one of claims 1 to 3.   The liquid discharge block further includes a nozzle plate in which a plurality of discharge ports for discharging liquid are provided in a matrix, and the plurality of pressure chambers of the liquid discharge block are arranged in a matrix so as to face the plurality of discharge ports, respectively. 5. The liquid discharge head according to claim 1, wherein the liquid discharge head is disposed on the surface.   A wiring lead-out pattern individually connected to the electrode formed on the inner wall of the pressure chamber is formed at the discharge side end of the liquid discharge block, and at the supply side end of the liquid discharge block, the air chamber The wiring lead-out pattern connected to the electrode formed on the inner wall is formed, and the inlet and the outlet of the flow path are provided at the supply side end of the liquid discharge block. The liquid discharge head according to claim 1.