JP4178604B2 - Ink jet head and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet head for recording characters and figures by ejecting ink from nozzle holes and a method for manufacturing the same.
[0002]
[Prior art]
Ink jet heads are usually ejected grooves communicating with nozzle holes, and the ink is removed from the nozzle holes by applying pressure to the ink by deforming the piezoelectric material or locally heating and vaporizing the ink. It is comprised so that it may inject.
[0003]
Conventionally, as an inkjet head using a piezoelectric material, a plurality of grooves parallel to the upper surface of the actuator substrate made of a piezoelectric material and a plurality of connection terminals on the back surface are selectively provided from each connection terminal to an electrode on each side surface of each groove. In some cases, a voltage is applied to the electrode to deform the partition between the grooves. When manufacturing such an ink jet head, first, a plurality of grooves are formed in parallel on the upper surface of the actuator substrate made of a piezoelectric material, and then the entire surface of the actuator substrate including the inside of the grooves is electrically conductive by electroless plating or the like. Form a layer. Then, by dividing the conductive layer into grooves by grinding or laser processing, an electrode made of a conductive layer is formed on the partition walls of each groove, and the conductive layer on the back surface is divided from the front end surface of the actuator substrate. By doing so, a plurality of connection terminals individually connected to the electrodes of the respective grooves are formed. Then, by connecting a wiring material such as a flexible printed wiring board to the connection terminal, the flexible printed wiring board is connected to the drive control unit of the inkjet recording apparatus and the drive voltage output from the drive control unit based on the recording data. Then, the ink is applied to each partition wall via each connection terminal to be deformed, and the ink in each groove is ejected from the nozzle hole.
[0004]
[Problems to be solved by the invention]
In a conventional inkjet head, a nickel layer as a conductive layer is formed on the entire surface of an actuator substrate made of piezoelectric material by electroless plating, etc., and gold is coated on the nickel layer by electrolytic plating, and further insulated on the nickel layer. The protective film is formed by spin coating or CVD. This is because it is difficult to braze the wiring material to nickel, so that the brazing property is improved by interposing gold. Nickel itself has high corrosion resistance to ink. However, if gold is placed on nickel, a potential difference is generated at the interface, so that nickel is easily ionized and comes into contact with the ink (the unevenness of the piezoelectric material). Since the nickel is not completely covered with gold due to the influence and the gold is very thin, the ink is likely to be corroded when the ink comes into contact with the nickel through the gap), so that it is covered with an insulating protective film.
[0005]
As described above, forming an insulating protective film by a spin coating method, a CVD method, or the like requires considerable equipment and increases the number of steps. In particular, as described in Japanese Patent Application Laid-Open No. 7-101057, in order to secure a protective film, a plurality of organic films and inorganic films are formed, which requires a large number of man-hours and increases costs.
[0006]
The present invention solves this problem, and provides an ink jet head that omits an insulating protective film and has good corrosion resistance to ink and brazing with a wiring material, and a method for manufacturing the same.
[0007]
[Means for Solving the Problems and Effects of the Invention]
In order to solve the above problem, in the ink jet head according to claim 1, an actuator substrate, a plurality of ejection grooves for ejecting ink formed on one surface of the actuator substrate, and both sides of the plurality of ejection grooves are provided. A partition composed of at least a part of a polarized piezoelectric material, a plurality of electrodes formed on a side surface of the partition, and disposed on a surface opposite to the plurality of ejection grooves of the actuator substrate. A plurality of connection terminals connected to the electrodes of the ink jet head, wherein the electrode is formed of a nickel conductive layer having high corrosion resistance to ink, A side surface and the connection terminal on the opposite surface are formed of one continuous layer, and at least the nickel of the connection terminal is formed. On the surface of the conductive layer, the brazing property good gold conductive layer is formed, wherein the surface of the conductive layer of the nickel is formed on the side surfaces of each partition wall, the conductive layer of the gold is not formed.
[0008]
Thereby, it is possible to simultaneously realize that the electrodes and the connection terminals connected in series are prevented from being corroded by the ink, and the brazing property between the connection terminals and the wiring material is improved.
[0009]
Further, the conductive layer constituting the electrode is nickel, and the nickel conductive layer is formed of one continuous layer from the spray groove to the position corresponding to the connection terminal, and only at the position corresponding to the connection terminal on the layer. A gold conductive layer is formed. That is, a conductive layer made of nickel is formed by electroless plating on an actuator substrate made of an insulating material, and gold is hardly formed by electroless plating, but is easily formed on a conductive layer made of nickel. In addition, nickel is located in the portion exposed to the ink, and gold is located in the portion connected to the wiring material, so that the electrodes and connection terminals connected in series are prevented from corroding by the ink, and the connection terminal and wiring material are It is possible to improve the brazing performance at the same time.
Further, a nickel conductive layer can be formed from the ejection groove to the back surface of the actuator substrate on the opposite side, and a part of the back surface of the actuator substrate can be used as a connection terminal, facilitating manufacture.
According to a second aspect of the present invention, there is provided an inkjet head manufacturing method comprising: an actuator substrate; a plurality of ejection grooves for ejecting ink formed on one surface of the actuator substrate; and both sides in the plurality of ejection grooves. It is composed of at least a part of a partition made of polarized piezoelectric material, a plurality of electrodes formed on a side surface of the partition, and disposed on a surface opposite to the plurality of ejection grooves of the actuator substrate, A plurality of connection terminals connected to the electrodes, and in a method of manufacturing an inkjet head for brazing a wiring material to the connection terminals, a step of forming a plurality of ejection grooves on one surface of the actuator substrate; One continuous conductive layer of nickel having high corrosion resistance to ink is provided on the side surface of each partition wall of the actuator substrate and the connection terminal on the opposite surface. Forming as a layer, dividing the nickel conductive layer into the electrode corresponding to each injection groove and the portion corresponding to the connection terminal, and the surface of the nickel conductive layer corresponding to the connection terminal And forming a gold conductive layer having good brazing properties, and the gold conductive layer is not formed on the surface of the nickel conductive layer formed on the side surface of each partition wall.
[0010]
[0011]
[0012]
[0013]
In this manufacturing method, a nickel conductive layer connected to an actuator substrate including injection grooves is formed, and then divided into portions corresponding to the injection grooves and connection terminals, thereby connecting to a plurality of electrodes. The reliability of mutual connection with the terminals can be increased and the connection can be easily made.
Also, by forming a nickel conductive layer on the opposite surface of the actuator substrate in advance, a gold conductive layer can be easily formed on the portion corresponding to the connection terminal.
[0014]
Further, after forming a conductive layer of gold on the conductive layer of nickel, it is also possible to divide the two conductive layers at the same time, in the case of electroplating a conductive layer of gold on the conductive layer of nickel, a nickel After dividing only the conductive layer, a gold conductive layer can be formed on the nickel conductive layer by electroplating.
According to another aspect of the invention, the nickel conductive layer and the gold conductive layer are formed by plating, vapor deposition, or the like, so that the connection terminals are easily formed on the electrodes. . In particular, when the conductive layer constituting the connection terminal is a material that is difficult to form by plating or the like on the actuator substrate made of an insulating material, it is easily formed on the conductive layer constituting the electrode formed in advance.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
The ink-jet head has an actuator substrate 1, a plate member 4, a nozzle plate 6, and a manifold member 7. The actuator substrate 1 is configured by laminating a plurality of piezoelectric materials made of ceramics such as lead zirconate titanate (PZT) or lead titanate (PT), and the piezoelectric materials of the respective layers are in opposite directions ( Each is polarized in the direction of the thickness of the actuator substrate 1 (arrow 27 in FIG. 1). A plurality of grooves 14 and 15 are formed on the upper surface of the actuator substrate 1 by cutting over each layer. Of the plurality of grooves, every other groove is used as an ejection groove 14 for ejecting ink, and every other groove between both ends and the ejection groove 14 is used as a dummy groove 15.
[0017]
Each injection groove 14 is formed through the actuator substrate 1 from the front end 1a (left end in the figure) to the rear end 1d (right end in the figure) at a predetermined depth. Each dummy groove 15 is formed to have a predetermined depth from the front end of the actuator substrate 1 to the vicinity of the rear end side, and the rear end portion of the dummy groove is raised so as to be flush with the upper surface of the actuator substrate 1. Has been blocked. Further, a longitudinal groove 40 is formed at a position corresponding to the dummy groove 15 at the tip of the actuator substrate 1. The injection grooves 14 and the dummy grooves 15 are alternately arranged in parallel via the actuator partition walls 20, and the actuator partition walls 20 are composed of a plurality of layers of piezoelectric materials polarized in opposite directions.
[0018]
A conductive layer 41 of Ni (nickel) is formed by vapor deposition or electroless plating on the entire surface of the actuator substrate 1 including each injection groove 14, each dummy groove 15, the rear end surface 1d, and the back surface 1c. The front end surface 1a and the upper surface 1b of the actuator substrate 1 are cut or ground into a planar shape to remove the conductive layer. In the center of the bottom surface of each dummy groove 15, a first dividing groove 44 a is formed from the front end side to the surface without the conductive layer on the rear end upper surface. As a result, one electrode 23 is formed on the inner surface of each injection groove 14, and two independent electrodes 22, 22 are formed on the inner surface of each dummy groove 15. Each vertical groove 40 communicating with the dummy groove 15 is formed with a second divided groove 44b that is continuous with the first divided groove 44a. Furthermore, on the back surface 1c of the actuator substrate 1, as shown in FIG. 2, a plurality of third divided grooves 44c connected to the second divided grooves 44a are parallel to the dummy grooves 15 from the front end side to the vicinity of the rear end. A fourth divided groove 44d is formed on the rear end side of each third divided groove 44c so as to be orthogonal to the third divided groove 44c.
[0019]
On the back surface 1 c of the actuator substrate 1, an Au (gold) conductive layer 42 is formed only on the Ni conductive layer 41.
[0020]
Thus, each of the divided grooves 44c to 44d has a plurality of connection terminals 43 formed in parallel on the back surface of the actuator substrate 1, and a connection terminal 46 on the common potential side formed around the connection terminals 43. The connecting groove 43 is connected to the electrodes 22 and 22 on the side of the dummy grooves 15 of the two actuator partitions 20 with the vertical grooves 40. The injection grooves 14 and the two actuator partitions 20 adjacent to each other are used as a set of actuators. They are electrically connected to each other via the inner conductive layer 41, and are separated and independent from other sets of actuators by dividing grooves 44a to 44c. The connection terminal 46 on the common potential side is connected to the electrode 23 in the ejection groove 14 via the conductive layer 41 on the actuator substrate 1 rear end face 1d.
[0021]
Further, as shown in FIG. 2, a wiring material, that is, a flexible printed wiring board 32 is connected to the back surface 1c of the actuator substrate 1 on which the connection terminals 43 and 46 are formed by brazing (for example, soldering). Terminals 64 and 67 are formed on the flexible printed wiring board 32 so as to correspond to the connection terminals 43 and 46. The terminals 64 and 67 are connected to a drive control unit of an inkjet recording apparatus (not shown).
[0022]
On the upper surface of the actuator substrate 1 configured as described above, a flat plate member 4 made of a ceramic material or a resin material is bonded in a liquid-tight state with an epoxy-based adhesive or the like. Thus, each injection groove 14 is covered with the plate member 4 to open only the front end and the rear end. Each dummy groove 15 is covered with the plate member 4 so that only the tip is opened.
[0023]
A nozzle plate 6 is joined to the tips of the actuator substrate 1 and the plate member 4 in a liquid-tight state using an epoxy adhesive or the like. In the nozzle plate 6, a plurality of nozzle holes 30 are formed corresponding to each ejection groove 14 so that ink droplets are ejected from the ejection grooves 14.
[0024]
A manifold member 7 is joined to the rear ends of the actuator substrate 1 and the plate member 4. An ink supply port 31 connected to an ink tank (not shown) is formed at the center of the manifold member 7 and distributes ink to all the ejection grooves 14.
[0025]
FIG. 6 shows a processing apparatus for forming the divided grooves 44a to 44c, for example, a laser processing apparatus such as a YAG laser. The laser processing apparatus 80 includes a laser oscillator 81 that emits laser light 82, an X-axis galvanometer 84 that includes a reflecting mirror 83 that reflects the laser light and scans it in the X-axis direction (groove arrangement direction), and laser light 82. Are provided, and a Y-axis galvanometer 86 having a reflecting mirror 85 that scans in the Y-axis direction (longitudinal direction of the groove) and a condensing lens 87 that emits laser light 82 are provided. Then, the laser beam 82 is scanned and irradiated along the conductive layer, so that the conductive layer is linearly removed to form the respective divided grooves 44a to 44d.
[0026]
Next, a method for manufacturing the ink jet head will be described.
[0027]
First, the actuator substrate 1 is formed by slicing a flat plate made of laminated piezoelectric material into a strip shape, and then a plurality of injection grooves 14, dummy grooves 15, and vertical grooves 40 are formed by a diamond blade or the like. Thereafter, a conductive layer 41 of Ni or the like is formed on the entire surface including the grooves 14, 15, 40 of the actuator substrate 1 by vapor deposition or electroless plating. After that, the upper surface 1b of the actuator substrate 1 is cut or ground into a planar shape to remove the conductive layer on the upper surface, and the conductive layers in the grooves 14, 15 are made independent on the upper surface.
[0028]
As shown in FIG. 6, the actuator substrate 1 is mounted below the laser processing apparatus 80, and the conductive layer 41 is divided. First, the first divided groove 44a is formed by scanning the bottom surface of the dummy groove 15 and removing the conductive layer in a linear shape. The same processing is sequentially performed on the bottom surface of the adjacent dummy groove 15. Similarly, the bottom surface of the vertical groove 40 is scanned to remove the conductive layer in the form of a line to form the second divided groove 44b. Further, the back surface 1c of the actuator substrate 1 is also irradiated with the laser beam 82 to remove the conductive layer in a linear form, thereby forming third and fourth divided grooves 44c and 44d. By forming the first to fourth dividing grooves 44a to 44d in this division processing, and cutting or grinding the upper surface 1b and the front end surface 1a of the actuator substrate 1 (processing of the front end surface will be described later), the conductive layer 41 becomes each actuator. Every time, it is made independent in the dummy groove 15 on the back surface 1c.
[0029]
After the processing of the dividing grooves 44a to 44d, the Au conductive layer 42 is formed only on the connection terminals 43 and 46 on the back surface of the actuator substrate 1 by electrolytic plating. If the Ni conductive layer 41 is used as one electrode during the electrolytic plating, Au adheres only on Ni, so that the Au conductive layer is formed without filling the dividing grooves. In addition, when electrolytic plating is performed, the other surfaces except the back surface 1c of the actuator substrate 1 are masked so that plating is not formed, but at least only the ejection grooves 14 and the rear end surface 1d in contact with ink may be masked. Further, when it is difficult to mask the ejection groove 14 and the rear end surface 1d, only the back surface 1c of the actuator substrate 1 may be immersed in a plating solution so that only that portion may be plated.
[0030]
In addition, it is also possible to form not only Ni but also an Au conductive layer before processing the dividing grooves 44a to 44d, and then process the dividing grooves 44a to 44d together with the Au conductive layer. is there. The formation of the Au conductive layer can also be performed by other methods such as vapor deposition.
[0031]
Next, the plate member 4 is joined to the upper surface of the actuator substrate 1, and the tip surfaces of the actuator substrate 1 and the plate member 4 are cut or ground into a flat surface, and the conductive layer 41 on the tip surface 1 a is removed. To do. Then, the nozzle plate 6 is joined to the front end face and the manifold member 7 is joined to the rear end face so that the injection groove 14 and the nozzle hole 30 correspond to each other. Thereafter, the flexible printed wiring board 32 and the connection terminals 43 and 46 of the actuator substrate 1 are connected. This connection is made by bringing the terminals 64 and 67 of the flexible printed circuit board 32 into contact with the connection terminals 43 and 46 of the actuator substrate 1 and then brazing (for example, soldering). And assembled as an inkjet head. Note that a solder layer is formed in advance on each of the terminals 64 and 67 of the flexible printed circuit board 32 and is melted by heating and fixed to the connection terminals 43 and 46.
[0032]
Thus, according to the ink jet head of this embodiment, the drive signal output through the flexible printed wiring board 32 from the drive control unit of the ink jet recording apparatus (not shown) is applied to the pair of electrodes 22 and 22 of each actuator, By grounding the electrode 23, an electric field perpendicular to the polarization direction 27 is generated in the pair of partition walls 20, and the partition walls 20 are deformed to eject the ink in the ejection grooves 14.
[0033]
The electrode 23 formed in the ejection groove 14 is made of Ni, and Ni itself has high corrosion resistance against ink. Also, the connection terminals 43 and 46 on the back surface 1c of the actuator substrate 1 are made of Au on Au, and Au itself has good brazability. Therefore, the terminals 64 and 67 of the flexible printed wiring board 32 are Bonded well. In addition, even if Au is difficult to electrolessly plate the piezoelectric material of the actuator substrate, the conductive layer 41 of Au is formed at a position corresponding to the connection terminal by forming the Ni conductive layer 41 on the back surface of the actuator substrate in advance. 42 can be formed easily. Since Au is not formed over Ni in the injection groove 14 as in the prior art, Ni is easily ionized by Au and does not corrode, and an insulating protective film becomes unnecessary.
[0034]
Further, Pd (palladium) can be used for the conductive layer. Pd has both excellent corrosion resistance and brazing properties against ink, and both the electrode 23 and the connection terminals 43 and 46 can be made of one material. Pd can be formed on the actuator substrate by the same plating as Ni. In this case, the man-hour for forming the Au conductive layer can be omitted.
[0035]
In the present invention, not only Ni, Au, and Pd but also other materials having high corrosion resistance to ink and materials having good brazing properties can be used as the conductive layer.
Further, the present invention can be applied not only to ejecting ink by deforming the partition wall of the ejection groove 14 but also to other types of heads that supply power to the actuator for ink ejection through the connection terminals 43 and 46. it can.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an inkjet head as viewed from above.
FIG. 2 is an exploded perspective view of the inkjet head as viewed from below.
3 is an enlarged view in which a part of the ink jet head of FIG. 2 is sectioned in a groove row direction.
4 is a cross-sectional view taken along line AA in FIG.
5 is a cross-sectional view taken along line BB in FIG.
FIG. 6 is an explanatory diagram showing a state in which a division groove is formed by irradiating an actuator substrate with laser light from a laser processing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Actuator board | substrate 14 Injection groove | channel 15 Dummy groove | channel 20 Actuator partition wall 22 Electrode 23 Electrode 32 Wiring material 41 Ni conductive layer 42 Au conductive layer 43 Connection terminal 46 Connection terminal

Claims (3)

And the actuator substrate,
A plurality of ejection grooves formed on one surface of the actuator substrate for ejecting ink;
A plurality of electrodes formed on the side surfaces of the partition walls, each side of the plurality of ejection grooves is constituted by partition walls of at least partly polarized piezoelectric material ;
The actuator substrate is disposed on a surface opposite to the plurality of ejection grooves, and includes a plurality of connection terminals connected to the plurality of electrodes ,
In an inkjet head that brazes a wiring material to the connection terminal,
The electrode is formed of a nickel conductive layer having high corrosion resistance to ink , and the side surface of each partition wall and the connection terminal on the opposite surface are formed of one continuous layer,
On the surface of at least the nickel conductive layer on which the connection terminals are formed, the gold brazing conductive layer is formed,
An ink jet head , wherein the gold conductive layer is not formed on a surface of the nickel conductive layer formed on a side surface of each partition wall . An actuator substrate ;
A plurality of ejection grooves formed on one surface of the actuator substrate for ejecting ink;
A plurality of electrodes formed on the side surfaces of the partition walls, each side of the plurality of ejection grooves is constituted by a partition wall of a piezoelectric material polarized at least in part .
The actuator substrate is disposed on a surface opposite to the plurality of ejection grooves, and includes a plurality of connection terminals connected to the plurality of electrodes ,
In the method of manufacturing an inkjet head for brazing a wiring material to the connection terminal,
Forming a plurality of ejection grooves on one surface of the actuator substrate;
Forming a nickel conductive layer having high corrosion resistance against ink as one continuous layer on the side surface of each partition wall of the actuator substrate and the connection terminal on the opposite surface;
Dividing the nickel conductive layer into the electrodes corresponding to the injection grooves and the portions corresponding to the connection terminals;
Forming a gold conductive layer with good brazing on the surface of the nickel conductive layer corresponding to the connection terminal ,
An ink jet head manufacturing method , wherein the gold conductive layer is not formed on a surface of the nickel conductive layer formed on a side surface of each partition wall .   3. The ink jet head manufacturing method according to claim 2, wherein the nickel conductive layer and the gold conductive layer are formed by plating, vapor deposition, or the like.

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