JP2000318168A - Manufacture of ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance machining accuracy and work efficiency in the working process of an ink jet head by bonding a piezoelectric element to one major surface of a large area substrate and then dividing the substrate into a plurality of head substrates. SOLUTION: The ink jet head comprises an actuator unit, i.e., a drive unit 1, a liquid chamber unit 2, and a head cover 3. The drive unit 1 comprises a plurality of multiplayer piezoelectric elements 12 arranged in two rows on a head substrate 11 wherein resin and a frame member 13 surrounding these piezoelectric elements 12 are bonded through an adhesive 14. When the head substrate 11 is manufactured, a ceramic substrate is employed as a large area substrate and one major surface of the substrate is divided into a plurality of sections by making a plurality of scribe lines (split lines) in grid. Each section is provided with a multiplayer piezoelectric element and, after an electrode is formed, the substrate is set on the table of dicing saw in order to split each section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ink jet head, and more particularly to a method of manufacturing an ink jet head having a piezoelectric element bonded to a head substrate.

[0002]

2. Description of the Related Art As an ink jet head for an ink jet recording apparatus (including an image forming apparatus) used in a printer, a facsimile, a copying machine, etc., for example, as described in Japanese Patent Application Laid-Open No. 8-108540, An actuator unit in which a stacked piezoelectric element is joined to a liquid chamber unit that ejects ink droplets by displacement of the piezoelectric element is known.

As a method of manufacturing such an ink jet head, for example, as described in JP-A-9-156114, after a piezoelectric element is bonded on a head substrate, a dicing saw blade or a wire saw is attached to the piezoelectric element. There has been known a method of dividing the piezoelectric element into a plurality of piezoelectric elements by performing slit processing using the method.

In this case, according to the publication, a work in which a piezoelectric element is bonded to a small-sized substrate (ceramic substrate) is placed on a dicing saw table with good positional accuracy by using a substrate holder that has been processed with high precision in advance. It is arranged and slitted with a blade.

[0005]

However, as described above, when a plurality of rows of workpieces are arranged on the substrate holder and slit processing is performed, variations in the set positions of the workpieces may cause a gap between the samples (workpieces). May not provide sufficient slit accuracy. In an extreme case, there is a possibility that a shift of several hundred μm on the left and right may occur in the head substrate. Further, when a plurality of workpieces are set on the substrate holder, the workpieces are difficult to handle due to the small size of the substrate, and the work efficiency is deteriorated because the workpieces are set on the substrate holder and the table of the dicing saw.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to improve processing accuracy and work efficiency in a work process of an ink jet head.

[0007]

In order to solve the above-mentioned problems, a method of manufacturing an ink jet head according to the present invention comprises:
After bonding a piezoelectric element to one main surface of a large-area substrate, the substrate is divided into a plurality of head substrates.

Here, slit processing for dividing the piezoelectric element bonded to the substrate into a plurality of piezoelectric elements can be performed.
Further, it is preferable to use a substrate in which division grooves for dividing into a plurality of sections in which the piezoelectric elements are arranged are formed in a lattice shape or to form the same division grooves. It is preferable that the dividing groove be deeper than the groove depth of the slit processing for dividing the piezoelectric element bonded to the substrate into a plurality of piezoelectric elements.

When a piezoelectric element and a component are joined on a substrate, it is preferable to planarize the upper surfaces of the substrates at the same time. After the planarization, the substrate is divided into a plurality of head substrates. Is preferred.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an ink jet head to which the present invention is applied, FIG. 2 is an enlarged cross-sectional view of a main part in a direction orthogonal to a channel direction (nozzle arrangement direction) of the head, and FIG. It is an expanded sectional view.

The ink jet head includes a drive unit 1 as an actuator unit, a liquid chamber unit 2
And a head cover 3. Drive unit 1
Is a ceramic substrate, for example, an insulating head substrate 11 made of barium titanate, alumina, forsterite or the like.
A plurality of laminated piezoelectric elements 12 as energy generating elements are arranged and joined in two rows in a row, and a frame, which is a component made of resin, ceramic, or the like, surrounding the periphery of each of the two rows of piezoelectric elements 12. The member (support) 13 is bonded to the adhesive 1
4 joined together.

A plurality of piezoelectric elements 12 are provided between piezoelectric elements 17 (to be referred to as “driving units”) to which driving pulses for causing ink to be formed into droplets and fly are provided, and driving units 17. A piezoelectric element (hereinafter, referred to as a “non-driving unit”) serving as a liquid chamber support member that is located and receives a driving pulse and simply fixes the liquid chamber unit 2 to the substrate 11.
... are alternately configured.

Here, as the piezoelectric element 12, a laminated piezoelectric element having ten or more layers is used. This laminated piezoelectric element has a thickness of 10 to 50 μm / 1, for example, as shown in FIG.
Layer of lead zirconate titanate (PZT) 20 and a thickness of several μ
An internal electrode 21 made of silver / paradium (AgPd) of m / 1 layer is alternately laminated, but the material used for the piezoelectric element is not limited to the above, and other electromechanical conversion elements may be used. Can also.

The internal electrodes 21 of each piezoelectric element 12 are left and right end electrodes 22 and 23 made of AgPd every other layer (the opposing surfaces of the two piezoelectric element rows are end electrodes 22 and the non-opposing surfaces are end electrodes. 23). On the other hand, as shown in FIG.
Each pattern of the common electrode 24 and the individual electrode 25 is provided by Au plating, AgPt paste printing, AgPd paste printing, or the like.

The opposite end electrodes 22 of each row of the piezoelectric elements 12 are connected to the common electrode 24 via a conductive adhesive 26.
On the other hand, the non-opposing end surface electrodes 23 of the piezoelectric elements 12 in each row are connected to the individual electrodes 25 via the conductive adhesive 26 in the same manner. Thereby, the driving unit 17
When a drive voltage is applied to the drive unit 17, an electric field is generated in the stacking direction, and the driving unit 17 is displaced in the stacking direction (d 33).
Direction displacement) occurs. As shown in FIG. 2, the common electrode 24 has a hole 13a formed in the frame member 13.
By filling the inside with the conductive adhesive 26, the pattern connected to each piezoelectric element is conducted.

On the other hand, the liquid chamber unit 2 includes a diaphragm 31 having a multilayer structure composed of a laminate of metal thin films and a liquid chamber partition member having a two-layer structure composed of a photosensitive resin layer composed of dry film resist (DFR). 32 and a nozzle plate 33 made of metal, resin, or the like, are sequentially laminated, and are formed by heat fusion. By each of these members, one piezoelectric element 12
(Driving unit 17), a diaphragm 34 corresponding to the one piezoelectric element 12, a pressurized liquid chamber 35 pressurized via each diaphragm 34, and both sides of the pressurized liquid chamber 35. Common liquid chambers 36, 36 for introducing ink to be supplied to the pressurized liquid chamber 35, and a pressurized liquid chamber 35 and common liquid chambers 36, 36.
Ink supply paths 37, 37 communicating with the pressure liquid chamber 35.
One channel is formed by the nozzle 38 communicating with the nozzle, and a plurality of channels are provided in two rows.

The diaphragm 31 is made of a nickel plating film having a two-layer structure, and is formed integrally with the diaphragm portion 34 corresponding to the driving portion 17 and at the center of the diaphragm portion 34 for joining with the driving portion 17. Corresponding to the island-shaped convex portion 40, the partition wall portion 41 which becomes a beam to be connected to the non-driving portion 18 and makes each channel (nozzle) independent, the peripheral thick portion 42 to be connected to the frame member 13, and the common liquid chamber 36. Elastic part (hereinafter referred to as "damper part") that absorbs the pressure of
43 are formed.

The liquid chamber partition member 32 is formed by applying a dry film resist on the diaphragm 31 in advance, exposing it using a required mask, and developing it to form a first liquid chamber pattern.
The photosensitive resin layer 45 and the second photosensitive resin layer 46 on which a dry film resist is applied in advance on the nozzle plate 33 side, exposed using a required mask, and developed to form a predetermined liquid chamber pattern are heated. It is joined by crimping.

The nozzle plate 33 has a large number of nozzles 38, which are fine discharge ports for ejecting ink droplets. The internal shape (inner shape) of this nozzle 38 is
It is formed in a substantially cylindrical shape (or a substantially truncated cone shape). The diameter of the nozzle 38 is about 25 to 35 μm on the ink droplet outlet side.

The ink ejection surface (nozzle surface side) of the nozzle plate 33 is a water-repellent surface 47 which has been subjected to a water-repellent surface treatment as shown in FIG. For example, PTF
Ink physical properties such as E-Ni eutectoid plating, electrodeposition coating of fluororesin, vapor-deposited evaporative fluororesin (for example, pitch fluoride), baking after solvent application of silicon resin or fluorine resin The water-repellent treatment film selected according to the above is provided to stabilize the ink droplet shape and the flying characteristics so that high-quality image quality can be obtained.

The drive unit 1 and the liquid chamber unit 2
After processing and assembling separately, the vibration plate 31 of the liquid chamber unit 2 and the piezoelectric element 12 and the frame member 13 of the drive unit 1 are joined with an adhesive 49.

Then, the substrate 11 is supported and held on a spacer member (head holder) 50 as a head support member, and the head driving I disposed in the spacer member 50 is provided.
C and the electrodes 24 and 25 connected to the piezoelectric elements 12 (drive unit 17) of the drive unit 1
They are connected via PC cables 51,51.

A nozzle cover (head cover) 3
Is formed in a box shape that covers the periphery of the nozzle plate 33 and the side surface of the head, and is bonded to the periphery of the nozzle plate 33 with an adhesive. Further, in order to supply ink from an ink cartridge (not shown) to the liquid chamber, a spacer member 50,
The substrate 11, the frame member 13, and the vibration plate 31 are provided with ink supply holes 52 to 55, respectively.

In the ink jet head configured as described above, by applying a driving waveform (pulse voltage of 10 to 50 V) to the driving unit 17 in accordance with the recording signal, a displacement in the stacking direction occurs in the driving unit 17, Diaphragm 31
The pressurized liquid chamber 35 is pressurized through the diaphragm section 34 of the above, and the pressure rises, and ink droplets are ejected from the nozzle 38. At this time, ink flows also in the direction of the ink supply passages 37, 37 leading from the pressurized liquid chamber 35 to the common liquid chamber 36. However, by reducing the cross-sectional area of the ink supply passages 37, 37, the fluid resistance portion is reduced. Function to reduce the flow of ink toward the common liquid chambers 36, 36, thereby preventing a drop in ink ejection efficiency.

Then, with the end of the ink droplet ejection, the ink pressure in the pressurized liquid chamber 35 decreases, and a negative pressure is generated in the pressurized liquid chamber 34 due to the inertia of the ink flow and the discharge process of the drive pulse. To the ink filling process. At this time, the ink supplied from the ink tank flows into the common liquid chambers 36, 36, and from the common liquid chambers 36, 36 to the ink supply paths 37, 3.
After that, it is filled into the pressurized liquid chamber 35. Then, the vibration of the ink meniscus surface near the outlet of the nozzle 38 is attenuated,
When the ink is returned to the vicinity of the outlet of the nozzle 38 due to surface tension (refill) and reaches a stable state, the operation shifts to the next ink droplet ejection operation.

Next, an embodiment of a manufacturing process of the actuator unit according to the present invention will be described with reference to FIGS. 4 is a plan view, FIG. 5 is a front view, FIG. 6 is a perspective view of a main part of FIG. 4, and FIG. 7 is a perspective view of a main part after slit processing.

First, a ceramic substrate having good flatness is used as the large-area substrate 61. The large area means an area large enough to be divided into a plurality (two or more) of head substrates. A plurality of scribe lines (divided grooves) 63 are formed in a lattice shape on one main surface of the large-area substrate 61 and divided into a plurality of sections 62. here,
The number of the sections 62 is 4 × 4 = 16. Further, the depth of the division groove 63 is formed to be deeper than the groove depth of the slit processing described later.

Then, each section 62 of the large area substrate 61
And a plate-shaped piezoelectric element (here, a laminated piezoelectric element) 6
4 are precisely bonded to predetermined positions by two. As shown in FIG. 6, each of the sections 62 has an electrode pattern 65 serving as a common electrode and an electrode pattern 6 serving as an individual electrode.
6, and an ink supply hole 53 is formed.

This large area substrate 61 is set on a table of a dicing saw. In this case, the piezoelectric element 64 is set so that the longitudinal direction is perpendicular to the scanning direction (the direction indicated by the arrow) of the blade 67, and alignment is performed so that the slit processing position and the blade position match.

Then, the table of the dicing saw and the blade 67 are relatively moved to perform slit processing to reach the large-area substrate 61 to form slit grooves 11a. As shown in FIG. Of the piezoelectric element 12. In this case, since the depth of the dividing groove 63 is formed deeper than the slit groove 11a formed by the slit processing,
It is possible to prevent cracks from entering from the dividing grooves 63 during the slit processing and breakage.

Next, by dividing the large-area substrate 61 from the dividing groove 63, the head substrate 11 in which a plurality of piezoelectric elements 12 are joined is obtained. The division of the substrate 61 is performed by a hand,
A dicing saw, a wire saw, a laser, or the like can be used. In this case, since the division groove 63 is formed, the head substrate 11 can be easily divided even by hand, and the depth of the division groove 63 is formed to be deeper than the slit groove 11a formed by the slit processing. Therefore, the dividing wall is formed favorably.

As described above, after the piezoelectric element is bonded to one main surface of the large-sized substrate, the substrate is divided into a plurality of head substrates. Variations in slit processing accuracy between samples due to variations in set positions can be reduced, and slit processing accuracy can be improved. In addition, since the substrate is a large-area substrate, handling at the time of work is good, and work efficiency is improved.

Here, the variation of the slit groove was evaluated for the head substrate manufactured as described above. Table 1 shows the evaluation results. In addition, the evaluation position evaluated the dispersion | variation between the first indexes AB of FIG.

[0034]

[Table 1]

Next, another embodiment of the manufacturing process of the actuator will be described with reference to FIGS. 9 is an explanatory perspective view of a main part, and FIG. 10 is a front view of the main part. First, as shown in FIG.
After slitting the upper piezoelectric element 64 to divide it into individual piezoelectric elements 12, as shown in FIG. 9, a frame 13 as a component is joined on a large-area substrate 61, and this is combined with a workpiece. I do.

Thereafter, as shown in FIG. 10, the grinding wheel 71 is rotated to move the workpiece 70 in the direction indicated by the arrow, and the upper surfaces 12a and 12b of the piezoelectric element 12 and the upper surface 1 of the frame 13 are moved.
Grinding the piezoelectric element 12 and the frame 13
Is adjusted to the height indicated by the line CC.

That is, the height of the piezoelectric element 12 bonded to the upper surface of the substrate 61 from the upper surface of the substrate is generally irregular, and the height of the upper surface of the frame 13 of the component may be varied. However, if the heights are irregular, when the liquid chamber units 2 are joined, the ejection characteristics are adversely affected, such as the occurrence of defective ink droplet ejection due to defective joining.

Therefore, the height between the individual piezoelectric elements 12 and the height of the frame 13 are made uniform by performing surface grinding. By performing this surface grinding, the upper surface of the piezoelectric element 12 and the upper surface of the frame 13 can have a planar accuracy of 5 μm or less, and the surface roughness Ra can be 0.2 to 0.5 μm.
And sufficient joining quality can be obtained.

Next, the individual actuator units (drive units) 1 are obtained by dividing the large-area substrate 61 from the division grooves 63 in the same manner as in the above embodiment.

By using a large-area substrate in this manner, handling when performing surface grinding is good, work efficiency is improved, and the cost can be reduced because a jig such as a substrate holder is not required.

[0041]

As described above, according to the method of manufacturing an ink jet head according to the present invention, after a piezoelectric element is bonded to one main surface of a large area substrate, the substrate is divided into a plurality of head substrates. Therefore, the processing variation is reduced and the processing quality is improved, and the handling is facilitated to improve the working efficiency.

Here, by dividing the piezoelectric element bonded to the substrate into a plurality of piezoelectric elements by performing slit processing, the division of the piezoelectric element is facilitated. In addition, the substrate is divided into a plurality of sections in which the piezoelectric elements are arranged, and a division groove is formed in a grid shape. By forming the division grooves, division work into individual head substrates is easy. become. By making the dividing groove deeper than the groove depth of the slit processing for dividing the piezoelectric element bonded to the substrate into a plurality of piezoelectric elements, damage due to the slit processing can be prevented.

When the piezoelectric element and the component are joined on the substrate, their upper surfaces are simultaneously flattened to improve the joining quality with the liquid chamber unit. Dividing the substrate into a plurality of head substrates improves the processing quality of the flattening process.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an inkjet head to which the present invention has been applied.

FIG. 2 is an enlarged sectional view of a main part of the head in a direction orthogonal to a channel direction.

FIG. 3 is an enlarged cross-sectional view of a main part of the head in a channel direction.

FIG. 4 is a plan view for explaining a first embodiment of a manufacturing process of the drive unit.

FIG. 5 is an exemplary front view for explaining the embodiment;

FIG. 6 is an explanatory perspective view of a main part in the state of FIG. 4 for describing the embodiment;

FIG. 7 is an explanatory perspective view of a main part in a state after slit processing for the description of the embodiment;

FIG. 8 is a perspective explanatory view for explaining an evaluation result;

FIG. 9 is a perspective explanatory view for explaining a second embodiment of the manufacturing process of the drive unit.

FIG. 10 is an explanatory front view of a main part used for describing the same step;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drive unit (actuator unit), 2 ... Liquid chamber unit, 3 ... Frame, 11 ... Head substrate, 11a
... Slit groove, 12 ... Piezoelectric element, 17 ... Drive section, 18 ...
Non-driving unit, 31: diaphragm, 33: nozzle plate, 34
... diaphragm part, 40 ... island-shaped convex part, 41 ... beam part, 42
... peripheral thick part, 43 ... damper part, 61 ... large area substrate, 62 ... division, 63 ... division groove, 64 ... piezoelectric element.

Claims (6)

[Claims] 1. A method for manufacturing an ink jet head comprising: an actuator unit having a piezoelectric element joined to a head substrate; and a liquid chamber unit joined to the actuator unit and ejecting ink droplets by displacement of the piezoelectric element. A method for manufacturing an ink jet head, comprising: after joining the piezoelectric element to one main surface of a large-area substrate, dividing the substrate into a plurality of head substrates. 2. The method for manufacturing an ink jet head according to claim 1, wherein a slit process for dividing the piezoelectric element bonded to the substrate into a plurality of piezoelectric elements is performed. 3. The method for manufacturing an ink jet head according to claim 1, wherein the substrate is formed in a lattice shape with a plurality of division grooves for dividing the piezoelectric element into a plurality of sections. Of producing an inkjet head. 4. The method for manufacturing an ink-jet head according to claim 1, wherein the large-area substrate is formed in a lattice shape with division grooves for dividing the plurality of sections in which the piezoelectric elements are arranged. A method for manufacturing an ink jet head, wherein a depth of a slit processing for dividing a piezoelectric element bonded to the substrate into a plurality of piezoelectric elements is deeper. 5. The method for manufacturing an ink jet head according to claim 1, wherein a component is joined to the substrate together with a piezoelectric element, and slit processing is performed to divide the piezoelectric element into a plurality of piezoelectric elements. The method for manufacturing an ink jet head, wherein after the application, the upper surfaces of the piezoelectric element and the component are flattened at the same time. 6. The method for manufacturing an ink jet head according to claim 5, wherein the substrate is divided into a plurality of head substrates after the flattening process is completed.