JPH11188875A - Substrate for ink jet recording head and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substrate for ink jet recording head having long term reliability. SOLUTION: A substrate for ink jet recording head comprises an electric insulation layer also serving as a heat storage layer 2, a heating element layer 3, a wiring layer 4, and a plurality of protective layers formed sequentially on a metal substrate 1 wherein the heat storage layer 2 is composed of silicon dioxide, silicon nitride or metal oxide and the heat storage layer 2 is made more compact at the part touching the heating element layer 3 that at the part touching the metal substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for an ink jet recording head used in an ink jet recording apparatus and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a substrate for an ink jet recording head, as shown in FIG. 4, there is a substrate in which a single crystal silicon substrate 11 is used and a thermal oxide film 12 of silicon is formed as a heat storage layer. 13 is a heating resistor layer, and 14 is a wiring layer.

The substrate 11 is used because it has better thermal conductivity than glass or the like, and can easily form an electrical insulating layer also serving as a heat storage layer having good flatness by a thermal oxidation method of silicon. This is because a drive IC for an ink jet recording element can be formed in the substrate.

However, the material cost is high, and the yield of the driving IC decreases as the number of nozzles increases. Therefore, it is not always the best material. The size of the short-crystal silicon substrate that can be easily obtained at this time is 8 inches (200 mm).
In order to produce a longer head up to φ), the substrates have to be joined together.

[0005] From the above, as shown in FIG.
A proposal has been made of a metal substrate 21 which is low in cost, has good thermal conductivity, and can handle a relatively large size, and on which a dense thermal oxide film 22 of silicon is formed as a heat storage layer.

In the case of the metal substrate 21, a mirror surface sufficient to form a thin film pattern can be secured by cutting or polishing with a cutting tool. The drive element of the head is formed on another substrate, and is electrically connected to the head by wire bonding or the like.

The heat storage layer 22 of the metal substrate 21 is temporarily exposed to a high temperature of several hundred degrees by heating the heating resistor layer 23 for discharging ink. Therefore, an inorganic material is generally used for the heat storage layer 22 as a material that can withstand the high temperature. The heat storage layer is usually formed by sputtering or CVD using this material. 24 is a wiring layer.

[0008]

However, inorganic materials have a smaller coefficient of thermal expansion than metals and require a film thickness of 1 μm or more in order to obtain performance as a heat storage layer. Therefore, a change in the temperature of the substrate causes warpage such as bimetal. Also, spattering and CV
When an inorganic film is formed on a metal substrate by the method D, the temperature at the time of film formation is high, and stress exists in the film itself. Therefore, when the temperature is returned to normal temperature, warpage occurs on the substrate.

[0009] When an ink jet recording head is manufactured by mechanically correcting and flattening the substrate on which warpage has occurred as described above, the reliability of the ink jet printer significantly deteriorates due to a temperature change in an operating environment of the ink jet printer.

[0010] This is because the inorganic film of the substrate is peeled off, cracked, or warped between the nozzle forming material and the substrate due to warpage of the substrate.

If the warpage is extremely large, it may not be possible to set the device in a photolithography exposure apparatus.
In particular, in the case of a long head such as a full-line head, this adverse effect is large, and the head itself cannot be manufactured.

Therefore, the inventor of the present invention has proposed that an SiO 2
_A low stress film was laminated by sputtering ₂ at a low temperature. However, in the case of this heat storage layer, the life of the heating resistor layer formed thereon on the applied pulse becomes extremely short, and the reliability as an ink jet recording head cannot be obtained.

The present invention has been made in view of such conventional problems, and has as its object to provide a long-term reliable substrate for an ink jet recording head and a method of manufacturing the same.

[0014]

Means for Solving the Problems The substrate for an ink jet recording head provided by the present invention is as described in the following (1) and (2).

(1) An ink-jet recording method in which an electrical insulating layer also serving as a heat storage layer is formed on a metal substrate, and a heating resistor layer, a wiring layer, and a single or a plurality of protective layers are sequentially formed thereon. In the head substrate, the layer includes silicon dioxide,
A substrate for an ink jet recording head, which is formed of silicon nitride or a metal oxide, wherein a film quality of a portion of the heat storage layer in contact with the heating resistor layer is denser than that of a portion in contact with the metal substrate.

(2) Ink jet recording in which an electrical insulating layer also serving as a heat storage layer is formed on a metal substrate, and a heating resistor layer, a wiring layer, and a single layer or a plurality of protective layers are sequentially formed thereon. In the head substrate, the heat storage layer is formed of a laminated body in which at least two compounds selected from silicon dioxide, silicon nitride, and metal oxide are sequentially laminated, and a portion of the heat storage layer in contact with the heating resistor layer is formed. A substrate for an ink jet recording head, wherein the film quality is denser than that of a portion in contact with a metal substrate.

The method of manufacturing a substrate for an ink jet recording head provided by the present invention is described in the following (1) and (2).

(1) An ink jet recording head is formed by forming an electrical insulating layer also serving as a heat storage layer on a metal substrate, and sequentially forming a heating resistor layer, a wiring layer, and a single or a plurality of protective layers thereon. When manufacturing a substrate, the heat storage layer is formed of silicon dioxide, silicon nitride, or metal oxide, and the film quality of a portion of the heat storage layer in contact with the heating resistor layer is that of a portion in contact with the metal substrate. A method for manufacturing a substrate for an ink jet recording head, wherein the substrate is made denser.

(2) An electrical insulating layer also serving as a heat storage layer is formed on a metal substrate, and a heating resistor layer, a wiring layer, and a single or a plurality of protective layers are sequentially formed thereon to form an ink jet recording head. When manufacturing a substrate, the heat storage layer is formed by sequentially laminating at least two compounds selected from silicon dioxide, silicon nitride, and metal oxide, and a heat-generating resistor layer of the heat storage layer A method for manufacturing a substrate for an ink jet recording head, wherein the film quality of a portion in contact with the metal substrate is made denser than that of a portion in contact with the metal substrate.

[0020]

The uniformly dense inorganic film to be laminated on the metal substrate has an internal stress at the time of film formation and has a coefficient of thermal expansion one order of magnitude smaller than that of the metal. In response to a temperature change, the stress of the inorganic film greatly changes from compression to tension, causing peeling and cracking of the film.

In order to avoid this, the density of the inorganic film is reduced uniformly by setting the CVD, PVD and sputtering at a low temperature, setting the argon pressure in the sputtering higher than usual, or setting the degree of vacuum in the PVD higher. In this case, the durability of the heating resistor layer is deteriorated.

Therefore, in the present invention, as described above, the portion of the inorganic heat storage layer in contact with the heating resistor layer is made of high-density film, and many portions in contact with the metal substrate are formed of low-density low-stress material. It was formed with the film quality.

In the present invention, the highly dense film portion is
Improves the durability of the heating resistor layer, and the low-density film quality part acts as a sponge between metal and inorganic film with different coefficients of thermal expansion to absorb the difference in expansion between them, preventing warpage of the metal substrate I do. Note that the thermal conductivity seems to be worse due to the difference in the foaming power from the head of the conventional configuration.

[0024]

Embodiments of the present invention will be described below with reference to embodiments.

(Embodiment 1) Embodiment 1 will be described with reference to FIG.

First, a 2 mm thick, 150 mm square aluminum substrate 1 was used as a metal substrate. Aluminum substrate 1
Can easily obtain a mirror surface by cutting with a diamond bite. Then, a silicon dioxide film 2 was formed as a heat storage layer 2 by 2.5 μm by a magnetron sputtering method using a film forming apparatus.
m was formed.

At this time, the first film 2a having a thickness of 2.3 μm from the start of film formation was not heated to the substrate 1, but was left to be spontaneously heated by sputtering. From the viewpoint of the temperature of the substrate hinder, the substrate 1
Is considered to be 100 ° C. or less. Thereafter, a high-frequency bias was applied to the substrate 1 side, and the remaining 0.2 μm of the second film 2b was laminated by a so-called bias sputtering method.

In order to examine the film quality of these two members 2a and 2b,
The etching rate was compared with that of a single crystal silicon thermal oxide film using diluted hydrofluoric acid. The first film 2a was etched as soon as it was immersed in the etchant, and the rate could not be measured, but the second film 2b showed the same etching rate as the thermal oxide film.
From this, it was found that the first film 2a was a low-density porous film and the second film 2b was a high-density film.

After the film formation, when the substrate 1 was taken out of the film formation apparatus, no warping was observed at this time.

Next, as the heating resistor layer 3 on the substrate 1, T
a-Ir was formed to a thickness of 0.1 μm, and A1 was formed as an electrode layer 4 to a thickness of 0.6 μm by a sputtering method.

Next, a resist (OFPA-800 made by Tokyo Ohka) is applied, patterned by resist exposure and development, and the electrode layer 4 is etched using this as a mask (A1 uses a C-6 etching solution made by Tokyo Ohka). )did. Then
The Ta-Ir is patterned by the same method and etched by the sputter etching method to form the heating resistor layer 3 having a width of 25 μm.
m, the length was 100 μm, and the number of heat generating elements in one head was 1024. Ta-Ir is a metal having excellent oxidation resistance and corrosion resistance, and does not deteriorate even when it comes into contact with ink or air, so that a protective film is not required.

Next, in order to protect the electrodes and the substrate, the entire surface except for the heater portion and the wire bonding portion was covered with a polyimide resin (Photo Nice). In the above steps,
The heater board substrate on which the heating resistance element was formed was completed.

Next, a positive resist (PEMR-AR900 manufactured by Tokyo Ohka) is coated on the heater board substrate to a thickness of 35 μm.
A nozzle and a liquid chamber are formed using photolithography technology, and a printing agent (made by MA-830 Taiyo Ink) is screen-printed on the resist in the liquid part to increase the height of the liquid chamber. Patterning was performed with a thickness of 150 μm. afterwards,
The 1 mm-thick aluminum top plate on which the ink supply port was formed and the heater board substrate were aligned and fixed integrally with an instant adhesive (Aron Alpha). At this time, in the gap between the heater board substrate and the top plate, the liquid chamber printing agent functions as a spacer.

Next, a room-temperature curable resin was injected into the above-mentioned gap and cured, and the resin was cut with a dicer having a 1 mm-wide diamond attached thereto to form a discharge port surface, which was mirror-finished with a diamond. . Subsequently, the liquid chamber printing agent and the positive mold resist nozzle mold material were removed with ethyl cellosolve, and finally a water repellent (CTX) was applied to the discharge port surface to complete the discharge element.

Finally, the ejection element was adhered to the base plate, the electrical connection between the heating resistor layer 3 and the driving element of the head was established by wire bonding, and an ink supply system was attached to complete the ink jet recording head.

The ink jet recording head manufactured in this manner has no problem in the heat treatment step at about 200 ° C. in the manufacturing process, and has a temperature of −30 ° C. to + 6 ° C. as the head.
Sufficient reliability was secured for a temperature cycle test in the range of 0 ° C. Also, in the discharge durability test, compared with the conventional thermal oxide film thermal storage layer system on the silicon substrate,
It showed the same durability.

(Examples 2 to 5) Examples 2 to 5 will be described with reference to FIG.

An aluminum substrate 1 having a thickness of 2 mm and a square of 105 mm was used as a metal substrate. Then, silicon nitride (Example 2), Ta ₂ O ₅ (Example 3), Al ₂ O ₃ (Example 4), SiAlON (Sialon) (Example 5) were formed as a heat storage layer 5 by magnetron sputtering. Each film 5 was formed to 2.5 μm. At this time, the temperature of the first film 5a up to 2.3 μm from the start of the film formation was spontaneously raised by sputtering without heating the substrate 1. Considering the temperature of the substrate hinder, the substrate temperature is considered to be 100 ° C. to 150 ° C. Thereafter, a high-frequency bias is applied to the substrate 1 side, and the remaining 0.2 μm second film 5 is formed by a so-called bias sputtering method.
b was laminated with each compound.

Thereafter, an ink jet recording head was manufactured in the same steps as in Example 1. The result of the reliability evaluation is
Same as Example 1.

Embodiments 6 to 9 Embodiments 6 to 9 will be described with reference to FIG.

As a metal substrate, an aluminum substrate 1 having a thickness of 2 mm and a square of 150 mm was used. Then, silicon oxide (Examples 6 to 6) was used as the heat storage layer 6 by magnetron sputtering.
The film 6 of 9) was formed in a thickness of 2.5 μm. At this time, the first film 6a having a thickness of 2.3 μm from the start of the film formation was not heated to the substrate 1, but was left to a spontaneous temperature increase by sputtering. Considering the temperature of the substrate hinder, the temperature of the substrate 1 is considered to be 100 ° C. or less. Thereafter, a high frequency bias is applied to the substrate 1 side, and SiN (Example 6), Ta ₂ O
₅ (Example 7), Al ₂ O ₃ (Example 8), SiAlO
Second film 6b of N (SiAlON) (Example 9)
Was laminated by 0.2 μm.

Thereafter, an ink jet recording head was manufactured in the same steps as in Example 1. The result of the reliability evaluation is
Same as Example 1.

[0043]

As described above, according to the present invention,
With the configuration as described above, the heat storage layer is not cracked, the heat storage layer is peeled off from the substrate, and the substrate is not warped, and the durability of the heating resistor layer is improved, and Thus, a highly reliable substrate for an ink jet recording head can be obtained in a long term.

[Brief description of the drawings]

FIG. 1 is a side view of an inkjet recording head substrate according to a first embodiment.

FIG. 2 is a side view of an inkjet recording head substrate according to a second embodiment.

FIG. 3 is a side view of a conventional substrate for an ink jet recording head.

FIG. 4 is a side view of a conventional substrate for an ink jet recording head.

FIG. 5 is a side view of a conventional substrate for an ink jet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum substrate 2,5,6 Heat storage layer 2a, 5a, 6a 1st film 2b, 5b, 6b 2nd film 3 Heating resistor layer 4 Wiring layer

Claims (4)

[Claims] 1. An ink jet recording head comprising: an electrical insulating layer also serving as a heat storage layer formed on a metal substrate; and a heating resistor layer, a wiring layer, and a single layer or a plurality of protective layers formed thereon in that order. In the substrate for use, the heat storage layer includes silicon dioxide,
A substrate for an ink jet recording head, which is formed of silicon nitride or a metal oxide, wherein the film quality of a portion of the heat storage layer in contact with the heating resistor layer is denser than that of a portion in contact with the metal substrate. 2. An ink jet recording head in which an electrical insulating layer also serving as a heat storage layer is formed on a metal substrate, and a heating resistor layer, a wiring layer, and a single layer or a plurality of protective layers are sequentially formed thereon. In the substrate for use, the heat storage layer includes silicon dioxide,
It is formed of a laminate in which at least two compounds selected from silicon nitride and a metal oxide are sequentially laminated, and the film quality of the portion in contact with the heating resistor layer is more dense than that of the portion in contact with the metal substrate. A substrate for an ink jet recording head, comprising: 3. An ink jet recording head, comprising: forming an electrical insulating layer also serving as a heat storage layer on a metal substrate; and sequentially forming a heating resistor layer, a wiring layer, and a single layer or a plurality of protective layers thereon. When manufacturing a substrate, the heat storage layer is formed of silicon dioxide, silicon nitride, or metal oxide, and the film quality of a portion of the heat storage layer in contact with the heating resistor layer is made higher than that of a portion in contact with the metal substrate. A method for manufacturing a substrate for an ink jet recording head, wherein the substrate is made dense. 4. An ink jet recording head substrate comprising: an electrical insulating layer serving also as a heat storage layer formed on a metal substrate; and a heating resistor layer, a wiring layer, and a single layer or a plurality of protective layers formed thereon in that order. When manufacturing, the heat storage layer, silicon dioxide,
Silicon nitride, and at least two compounds selected from metal oxides are sequentially laminated and formed, and the film quality of the heat storage layer in contact with the heating resistor layer is made higher than that of the portion in contact with the metal substrate, A method for manufacturing a substrate for an ink jet recording head, wherein the substrate is made dense.