JP2003039686A - Method of manufacturing inkjet head - Google Patents

Abstract

(57) Abstract: A highly reliable inkjet head capable of maintaining the wiring resistance of an electrode pattern substantially constant over a long period of time. The head substrate includes a plurality of heating resistors, an electrode pattern, and a protective film formed on an upper surface of a base plate, and a top plate. An ink jet head for discharging ink filled so as to be in partial contact with the protective film 5 on the electrode pattern 4 from an ink discharge hole by the heat generated by the heat generating resistor 3, wherein the electrode pattern 4 is mainly composed of aluminum. The protective film 5 is formed of a thin film made of an inorganic material, and a portion of the electrode pattern 4 located under the contact area of the ink is partially isotropic prior to the formation of the protective film 5. By etching, the upper surface of the electrode pattern 4 located below the contact region is made smoother than the upper surface of the electrode pattern 4 located below the non-contact region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ink jet head which records an image by depositing ink drops on a recording paper in a predetermined pattern.

[0002]

2. Description of the Related Art Conventionally, an ink jet head has been used as a recording device for forming an image on recording paper.

The ink jet head recording method uses a thermal energy generated by a heat generating resistor to eject and fly an ink droplet toward a recording sheet, a method using a deformation of a piezoelectric element, and an electromagnetic wave. There are those that utilize the heat generated by irradiation, and among these, the thermal jet type that utilizes the thermal energy of the heating resistor is easy to pattern the heating resistor,
Since even a heating resistor having a small area can generate a relatively large amount of heat energy, it is attracting attention as being suitable for high density recording.

As such a thermal jet type ink jet head, for example, as shown in FIG. 4, a plurality of heating resistors 13 and electrode patterns 14 and a protective film 1 are provided on the upper surface of a base plate 12 made of single crystal silicon or the like.
A plurality of ink discharge holes 1 corresponding to the heating resistors 13 in a one-to-one correspondence are formed on a head substrate 11 formed by sequentially forming
7 is disposed so that a predetermined gap is formed between the top plate 16 and the head substrate 11-top plate 16
There is known a structure in which a gap between them is filled with ink 18, and while the recording paper is conveyed along the outer surface of the top plate 16, the heating resistor 13 of the head substrate 11 is converted into image data from the outside. Based on individual Joule heating,
Bubbles A are generated in the ink 18 on the heating resistor 13, and the ink 18 on the heating resistor 13 is pushed upward by the pressure of the generated bubbles A, so that the ink 18
An image is recorded on the recording paper by ejecting a part of the ink from the ink ejection holes 17 toward the recording paper.

The protective film 15 on the head substrate 11 is
Alkali ions, water, etc. contained in the ink 18 come into contact with the heating resistor 13, the electrode pattern 14, etc. to corrode them, or the lump of dye contained in the ink 18 causes the heating resistance. This is to prevent the surface of the body 13 from sticking, and an inorganic material such as silicon nitride or silicon oxide is deposited on the base plate 12 to a predetermined thickness by a well-known thin film process such as CVD or sputtering. Was formed by.

[0006]

However, according to the above-mentioned conventional ink jet head, when the protective film 15 is formed by a thin film process such as a CVD method, the electrode pattern 14 is exposed to a high temperature of 150 ° C. or higher for a long time. During this time, the small protrusions formed on the surface of the electrode pattern 14 grow with the above-mentioned temperature rise, so that “hillocks” are formed on the surface of the electrode pattern 14.
A large protrusion having a particle size of about 1 μm is formed. In this case, since a film defect corresponding to a "hillock" forming portion is formed on the protective film 15 formed on the electrode pattern 14, if such an ink jet head is formed using such a head substrate 11, the protective film 15 is protected. The ink 18 comes into contact with the electrode pattern 14 through the film defect in the film 15, so that the electrode pattern 14 is corroded, and the wiring resistance of the electrode pattern 14 has a drawback that it largely changes in a short period of time. .

The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to obtain an ink jet head of high reliability capable of keeping the wiring resistance of an electrode pattern substantially constant for a long period of time. It is to provide a method of manufacturing a head.

[0008]

A method of manufacturing an ink jet head according to the present invention comprises a head substrate having a plurality of heating resistors and electrode patterns and a protective film formed on an upper surface of a base plate, and a top plate. An ink jet head for discharging ink filled between the head substrate and the top plate so as to partially contact the protective film on the electrode pattern from an ink discharge hole by heat generation of the heat generating resistor, The electrode pattern is a sputtered film containing aluminum as a main component, the protective film is formed of a thin film made of an inorganic material, and the portion of the electrode pattern located under the ink contact area is formed prior to the formation of the protective film. By performing isotropic etching halfway in the thickness direction, the upper surface of the electrode pattern located under the ink contact area is placed under the non-contact area. Is characterized in that the forming smoothly than the upper surface of the pattern.

In the method of manufacturing an ink jet head of the present invention, the surface roughness of the upper surface of the electrode pattern located under the ink contact area is 0.02 μm in terms of arithmetic average roughness Ra.
It is characterized by being set as follows.

Further, in the method for manufacturing an ink jet head of the present invention, the thickness of the electrode pattern is 0.1 μm to 0.3 μm under the contact area of the ink and is less than 0.1 μm under the non-contact area.
It is characterized by being set to 5 μm to 1.0 μm.

Furthermore, in the method for manufacturing an ink jet head of the present invention, the thickness of the protective film is 0.2 μm to 1.2 μm.
It is characterized by being set to μm.

Furthermore, the method of manufacturing an ink jet head of the present invention is characterized in that the protective film is formed in a temperature range of 250 ° C to 400 ° C.

According to the present invention, the surface of the electrode pattern located below the ink contact area is isotropically etched so that the surface becomes smoother than the surface of the electrode pattern located below the non-contact area. Therefore, when the protective film is formed in the subsequent process, even if the electrode pattern is exposed to high temperature, a large protrusion called “hillock” is formed on the surface of the electrode pattern located under the ink contact area. Therefore, it is possible to form a good protective film having almost no film-forming defects in this region. Therefore, the corrosion of the electrode pattern due to contact with the ink is effectively prevented,
It becomes possible to obtain a highly reliable inkjet head capable of maintaining the wiring resistance of the electrode pattern substantially constant over a long period of time.

Further, according to the present invention, the electrode pattern is not etched and the thickness is maintained thick in the portion located below the non-contact area of the ink, so that the wiring resistance of the entire electrode pattern becomes extremely large. There is no such inconvenience, and the power loss in the electrode pattern can be suppressed small.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. 1 is a perspective view of an inkjet head manufactured by the manufacturing method of the present invention, FIG. 2 is a sectional view of the inkjet head of FIG. 1, and 1 is a head substrate,
Reference numeral 6 is a top plate, and 8 is ink filled between the head substrate 1 and the top plate 6.

The head substrate 1 is electrically connected to a large number of heating resistors 3 which are linearly arranged in the longitudinal direction on the upper surface of a base plate 2 which is formed in a rectangular shape. The electrode pattern 4 to be formed is adhered, and these are covered with a protective film 5.

The base plate 2 is made of single crystal silicon, and an insulating film (not shown) made of silicon oxide or the like is deposited on the surface of the base plate 2 to a thickness of, for example, 1 μm to 3 μm. It electrically insulates the heating resistor 3 and the like.

A large number of heating resistors 3 provided on the upper surface of the base plate 2 are, for example, 600 dpi.
They are arranged linearly in the main scanning direction (longitudinal direction of the base plate 2) with a density of (dot per inch), and each of them is TaN, TaSiO, TaSiNO, TiSiO, Ti.
Since it is formed of an electric resistance material such as SiCO or NbSiO, when power source power is supplied through the electrode pattern 4 or the like, Joule heat is generated and bubbles A are generated in the ink 8 on the heating resistor 3. It has become.

Further, the electrode pattern 4 on the base plate 2 is formed in a predetermined thickness by a sputtered film containing aluminum as a main component so as to form a predetermined pattern. It acts as a power supply wiring for supplying the like.

The electrode pattern 4 has a thin portion and a thick portion, and is thin, for example, about 0.1 .mu.m to 0.3 .mu.m below the contact area of the ink 8 described below, and below the non-contact area of the ink 8. Then, for example, 0.5 μm to 1.0 μm
It is formed to be relatively thick.

On the surface of the electrode pattern 4 as described above, a large number of "hillocks" are formed in the thickened portion, whereas there is almost no "hillock" in the thinned portion. As for the surface roughness, the arithmetic mean roughness Ra of the thinned portion is 0.02 μm or less, and the arithmetic mean roughness Ra of the thickened portion Ra (0.04 μm to 0.06).
.mu.m) and is smoother.

The protective film 5 that covers the heating resistor 3 and the electrode pattern 4 described above contacts the heating resistor 3 and the electrode pattern 4 with the alkaline ions and water contained in the ink 8. Corrosion or ink 8
It is intended to effectively prevent the dyes contained therein from sticking to the surface of the heating resistor 3 and the like, and is made of, for example, 0.2 μm to 1. It is formed to a thickness of 2 μm.

On the other hand, the top plate 6 is disposed on the head substrate 1 with a partition wall member 9 having a predetermined thickness (for example, 25 μm to 200 μm) and a predetermined shape interposed therebetween.

The top plate 6 has a plurality of ink ejection holes 7 corresponding to the heating resistors 3 in a one-to-one correspondence, and these ink ejection holes 7 are directly above the corresponding heating resistors 3. The head substrate 1 is fixed so as to be positioned.

The ink ejection holes 7 of the top plate 6 are for ejecting ink droplets i toward the recording paper during the recording operation of the ink jet head, and the diameter of each ink ejection hole 7 is 10 μm to 100 μm. It is set to the size of
The heating resistors 3 are arranged linearly in the main scanning direction with the same density.

The partition member 9 interposed between the head substrate 1 and the top plate 6 keeps the space between the head substrate 1 and the top plate 6 substantially constant, and the individual heating resistors 3 are provided between them. The ink flow path corresponding to the above is formed, and the above-described ink flow path is formed in a portion where the partition member 9 does not exist.

The top plate 6 is formed by processing a photosensitive epoxy resin, a polyimide resin, molybdenum, alumina ceramics or the like into a predetermined shape, or by combining the above materials, and is made of, for example, molybdenum. , An ingot of molybdenum (lump) is formed into a plate shape by a conventionally known metal processing method, and a predetermined portion of the plate body is perforated by a conventionally known laser processing to form an ink ejection hole 7. Then, the obtained top plate 6 is mounted on the head substrate 1 via the partition member 9 and the spacers (not shown) described above, so that the top plate 6 is fixed at a predetermined position on the head substrate 1.

As the ink 8 to be filled between the head substrate 1 and the top plate 6, for example, pigment type oil-based ink or water-based dye ink is used, and the viscosity thereof is, for example, 0.3 mPa · s to 3.0 mPa.・ Adjusted to s (25 ℃).

The ink 8 is supplied from an ink tank (not shown) to the gap between the head substrate 1 and the top plate 6 and is filled so as to partially contact the protective film 5 on the electrode pattern 4.
Specifically, the ink 8 contacts the protective film 5 in a region on the heating resistor 3 or in a region where an ink flow path for supplying the ink 8 to the heating resistor 3 is formed. The ink 8 is kept in non-contact with the protective film 5 in the other region (region where the partition member 9 exists).

Bubbles A are generated in the ink 8 by the heat energy of the heating resistor 3 described above, and a part of the ink 8 becomes an ink droplet i due to the pressure when the bubbles are generated. The ink is ejected from the ink ejection hole 7 to the outside.

Thus, the above-mentioned ink jet head conveys the recording paper along the outer surface of the top plate 6 in the direction orthogonal to the arrangement direction of the ink ejection holes 7, while making a large number of heating resistors 3 image data from the outside. Based on the above, the heat is generated individually and the bubbles A are generated in the ink 8 on the corresponding heating resistor 3 by this heat energy.
A predetermined image is recorded on the recording paper by pushing up the ink 8 toward the ink ejection hole 7 side by the pressure of the generated bubbles A and ejecting the ink droplet i from the ink ejection hole 7 toward the recording paper.

Next, a method for manufacturing the head substrate 1 of the above-mentioned ink jet head will be described with reference to FIG.

(1) First, as shown in FIG. 3A, a base plate 2 made of single crystal silicon having an insulating film on its surface is prepared. The base plate 2 is manufactured by forming an ingot (lump) of single crystal silicon by a conventionally known Czochralski method (pulling method) or the like, and slicing this into a predetermined thickness. The insulating film on the surface of the base plate is formed to have a thickness of, for example, 1 μm to 3 μm by oxidizing the surface of the base plate 2 obtained as described above to a predetermined depth region by a conventionally known thermal oxidation method.

(2) Next, as shown in FIG. 3B, the heating resistor 3 and the electrode pattern 4 are patterned on the upper surface of the base plate 2. The heating resistor 3 and the electrode pattern 4 are formed by a conventionally well-known thin film forming technique, specifically, an electrically resistive material such as TaSiO mentioned above and a metal material containing aluminum as a main component by a conventionally well-known sputtering method. The base plate 2 is formed by sequentially depositing it on the upper surface of the base plate 2 and processing it into a predetermined pattern by using the well-known photolithography and etching techniques.

(3) Next, as shown in FIG. 3C, a part of the electrode pattern 4, specifically, a portion below the contact region of the ink 8 is formed in the thickness direction by a conventionally known isotropic etching. Erodes halfway. This thickness processing employs conventionally known photolithography technology and etching technology, and a part of the electrode pattern 4 is in the middle of the thickness direction, for example, when the total thickness of the electrode pattern 4 is 0.8 μm, 0.6 μ from the upper surface thereof.
This is performed by eroding to a depth region of m, whereby the upper surface of the portion of the electrode pattern 4 that is below the contact area of the ink 8 is on the upper surface of the portion that is below the non-contact area (non-etched area). The surface becomes smoother.

(4) Finally, as shown in FIG. 3D, a protective film 5 is formed on the heating resistor 3 and the electrode pattern 4 which are previously patterned, and the heating resistor 3 is formed by the protective film 5. And the electrode pattern 4 are covered. The protective film 5 is
Conventionally known thin film forming techniques such as CVD (Chemical Vapor Deposition) method and sputtering method are used to remove silicon nitride, silicon oxide, etc.
It is formed by depositing an inorganic material such as sialon on the heating resistor 3 and the electrode pattern 4 to a thickness of 0.2 μm to 1.2 μm, for example.

At the time of forming the protective film 5 as described above, the temperature of the head substrate 1 is exposed to a high temperature of 150 ° C. to 400 ° C. for degassing in the film forming apparatus and improving the adhesion of the film. However, when the ink jet head is constructed, the surface of the electrode pattern 4 located below the contact area of the ink 8 is made smooth as described above, and has a large size that grows into "hillock" even when placed under high temperature. Since there is no protrusion, the electrode pattern 4 and the like located under the contact area of the ink 8 can be satisfactorily covered with the protective film 5 having few film-forming defects.

Therefore, when the above-described head substrate 1 is used to form an ink jet head, the ink 8 does not come into contact with the electrode pattern 4 through a film formation defect in the protective film 5 or the like, and Corrosion is effectively prevented,
The wiring resistance of the electrode pattern 4 can be maintained substantially constant for a long period of time.

Moreover, in the electrode pattern 4, the thickness processing as described above is performed only under the contact area of the ink 8, and the thickness of the electrode pattern 4 located under the non-contact area is maintained thick. Therefore, there is no inconvenience that the wiring resistance of the entire electrode pattern becomes extremely large, and there is also an advantage that the power loss in the electrode pattern 4 can be suppressed to be small.

In the head substrate 1 of the above-mentioned ink jet head, "hillock" may be generated on the upper surface of the electrode pattern 4 located below the non-contact area of the ink 8. In this area, the protective film 5 is formed. The ink 8 does not come into contact therewith, and therefore, even if a film-forming defect is formed in the protective film 5, the ink 8 does not come into contact with the electrode pattern 4 through the film-forming defect, which adversely affects the reliability of the inkjet head. Does not affect

The present invention as described above is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, the ink discharge hole 7 is provided in the top plate 6 and the heating resistor 3 corresponding thereto is provided.
However, instead of this, the ink ejection holes 7 may be arranged so as to be offset from directly above the heating resistor 3, or ink droplets may be ejected from the edge of the head substrate 1. In applying the present invention to an edge-shooter type inkjet head, the ink discharge holes 7 are not provided in the top plate 6, and a nozzle member is disposed on one end side of the head substrate 1 in a direction orthogonal to the top plate 6. The holes may be provided.

[0043]

According to the present invention, the upper surface of the electrode pattern located under the ink contact area is eroded by isotropic etching so as to be smoother than the upper surface of the electrode pattern located under the non-contact area. Therefore, when the protective film is formed in the subsequent process, even if the electrode pattern is exposed to high temperature, a large protrusion called “hillock” is formed on the surface of the electrode pattern located under the ink contact area. Therefore, it is possible to form a good protective film having almost no film-forming defects in this region. Therefore, corrosion of the electrode pattern due to contact with ink is effectively prevented, and a highly reliable inkjet head capable of maintaining the wiring resistance of the electrode pattern substantially constant for a long period of time can be obtained.

Further, according to the present invention, since the electrode pattern is not etched and the thickness is maintained thick under the non-contact area of the ink, the disadvantage that the wiring resistance of the entire electrode pattern becomes extremely large occurs. Therefore, the power loss in the electrode pattern can be suppressed to be small.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet head manufactured by a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view of the inkjet head of FIG.

3 (a) to 3 (d) are cross-sectional views for each step for explaining the manufacturing method of the present invention.

FIG. 4 is a cross-sectional view of a conventional inkjet head.

[Explanation of symbols]

1 ... Head substrate, 2 ... Base plate, 3 ...
-Heating resistor, 4 ... Electrode pattern, 5 ... Protective film, 6 ... Top plate, 7 ... Ink ejection hole, 8 ... Ink, A ... Bubble, i ... Ink drops

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C057 AF70 AG46 AG91 AP33 AP52                       AP53 BA04 BA13

Claims (5)

[Claims] 1. A head substrate having a plurality of heating resistors, electrode patterns, and a protective film formed on an upper surface of a base plate in this order, and a top plate.
An ink jet head for ejecting ink filled so as to partially contact with a protective film on the electrode pattern from an ink ejection hole by heat generation of the heating resistor, wherein the electrode pattern is a sputtered film whose main component is aluminum. The protective film is formed of a thin film made of an inorganic material, and the portion of the electrode pattern located under the ink contact region is isotropically etched halfway in the thickness direction prior to forming the protective film. According to the method, the upper surface of the electrode pattern located below the ink contact area is made smoother than the upper surface of the electrode pattern located below the non-contact area. 2. The surface roughness of the upper surface of the electrode pattern located below the ink contact area is 0.02 in terms of arithmetic average roughness Ra.
The method of manufacturing an inkjet head according to claim 1, wherein the thickness is set to be equal to or less than μm. 3. The thickness of the electrode pattern is set to 0.1 μm to 0.3 μm under the contact area of the ink and 0.5 μm to 1.0 μm under the non-contact area. The method for manufacturing an inkjet head according to claim 1 or 2. 4. The protective film has a thickness of 0.2 μm to 1.2 μm.
4. The method for manufacturing an inkjet head according to claim 1, wherein the inkjet head is set to .mu.m. 5. The method according to claim 1, wherein the protective film is formed in a temperature range of 150 ° C. to 400 ° C.