JPH02281951A - Ink jet recording head and base for the same - Google Patents

Abstract

PURPOSE:To more satisfactorily cover a stepped part between an electrode and a resistance heating layer and to separate a stepped part in contact with liquid and the stepped part between the electrode and the resistance heating layer by preventing the stepped part of a protective layer from being constricted by the stepped part between the resistance heating layer and the electrode thanks to the existence of a stepped part enclosing layer and stepped coating layer. CONSTITUTION:A stepped part coating layer 111 enters a space between a stepped part enclosing layer 113, a stepped part and stuffs this space completely, and coats the exterior of the stepped part enclosing layer. Since a liquid-state material is used for the stepped part coating layer 111, a deeper stepped part is formed between the layer 111 and the enclosing layer 113, whereas a shallower stepped part is formed on electrodes 109 and 110 and the plane of a resistance heating layer 108. Here, a protective layer for the electrodes 109 and 110 and for the resistance heating layer 108 is formed, and the stepped part of the protective layer 112 laminated thereon is prevented from being constricted. Consequently, the stepped part between the electrodes and the resistance heating layer is more satisfactorily covered, and the stepped part in contact with liquid can be separated from the stepped part between the electrodes and the resistance heating layer.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inkjet recording head and a recording head substrate, and more specifically, the present invention relates to an inkjet recording head and a recording head substrate, and more specifically, the present invention relates to an inkjet recording head and a recording head substrate. The present invention relates to an ink shed recording head and a recording head substrate for recording by forming an ink shed.

[Prior Art] Inkjet recording methods have attracted attention in recent years because they can perform low-noise and high-speed recording, and can also record on plain paper.

Among such inkjet recording methods, for example, Japanese Patent Application Laid-Open No. 54-51837, German Open Publication (DOLS)
The method described in Japanese Patent No. 2843064 has a different feature from other inkjet recording methods in that thermal energy is applied to the liquid to obtain the driving force for ejecting droplets.

That is, in the recording method disclosed in the above-mentioned publication, the liquid subjected to the action of thermal energy undergoes a state change accompanied by a sharp increase in volume, and the acting force based on this state change causes
Liquid is ejected from the ejection port at the tip of the recording head to form flying droplets, and these droplets adhere to the recording member to perform recording.

In particular, the inkjet recording method disclosed in DOLS 2843064 is not only very effectively applied to the so-called drop-on-demand recording method, but also
It is easy to realize a recording head with a full-line ejection port and high-density multi-orifice, resulting in high resolution,
It has the characteristic of being able to obtain high-quality images at high speed.

The recording head section of the apparatus applied to the above recording method includes an ejection port provided for ejecting liquid and a portion that communicates with the ejection port and where thermal energy for ejecting droplets acts on the liquid. The apparatus includes a liquid discharge part having a liquid path that includes a heat acting part as a part of the structure, and an electrothermal converter as a means for generating thermal energy. This electrothermal converter includes a pair of electrodes, and a heat generating resistor layer connected to these electrodes and having a region (heat generating portion) that generates heat between these electrodes.

A conventional example showing the structure of such an inkjet recording head is shown in FIGS. 5 and 6.

FIG. 5 is a schematic partial cross-sectional view showing a cross section in the longitudinal direction of the liquid path of a structure related to one ejection port in the recording head, and FIG. 6 is a schematic partial cross-sectional view taken along the dashed-dotted line AA' in FIG. Show the diagram.

In these figures, the recording head 200 includes an electrothermal transducer 2
By bonding a substrate 202 on which 01 is provided and a grooved plate 203 on which grooves of a predetermined width and depth are provided at a predetermined line density and correspond to the number of ejection ports, the ejection ports 20
In the case of the recording head shown in FIG. 0, which has a structure in which a liquid ejection portion 205 including a liquid ejection port 205 is formed, it is shown as having a plurality of ejection ports 204, but it is limited to such a structure. However, a recording head with a single ejection port is also included in the description of this specification below.

The liquid discharge part 205 has a discharge port 204 for discharging the liquid at its terminal end, and thermal energy generated by the electrothermal converter 201 acts on the liquid to generate bubbles, causing rapid expansion and contraction of the volume. It has a heat acting part 206 which is a part that causes a state change.

The heat acting part 206 is the heat generating part 20 of the electrothermal converter 201.
7 and has a heat acting surface 208 as a surface in contact with the liquid of the heat generating section 207 as its bottom surface.

The heat generating section 207 includes a lower layer 209 provided on the support 216 of the substrate 202, a heat generating resistor layer 210 provided on the lower layer 209, and a protective layer 211 provided on the heat generating resistor layer 210. Ru. The heating resistance layer 21G is provided with electrodes 212 and 213 on its surface for supplying electricity to the heating resistance layer 210 in order to generate heat. Electrode 21
Reference numeral 2 denotes an electrode common to the heat generating section of each liquid discharging section, and electrode 213 is a selection electrode for selectively generating heat in the heat generating section of each liquid discharging section. It is located along the

The protective layer 211 is a heat generating resistor layer 2 in the heat generating section 207.
10 and the inlet filling the liquid path of the liquid ejection part 205, and chemically and physically protects it from ink.
This prevents a short circuit between the electrodes 212 and 213 via the ink. Furthermore, the protective layer 211 also plays a role in preventing electrical leakage between adjacent electrodes.

In particular, it is important to prevent electrical leakage between the selected electrodes, or to prevent electrolytic corrosion of the electrodes that occurs when the electrodes under each liquid path come into contact with the ink for some reason and are energized. For this purpose, a protective layer 211 having the function of a protective layer is provided at least on the electrode that is located below the liquid flow path.

Furthermore, the liquid path provided in each liquid discharge section has a common liquid chamber (
(not shown), but due to its design, the electrodes connected to the electrothermal converters provided in each liquid discharge section pass under the common liquid chamber on the upstream side of the heat acting section. Generally, it is provided as follows. Therefore, the above-mentioned protective layer is generally provided in this portion as well to prevent the electrode from coming into contact with the liquid.

[Problems to be Solved by the Invention] By the way, especially in the case of a multi-orifice type recording head in which a large number of ejection ports are arranged, a large number of fine electrothermal transducers corresponding to the ejection ports, Since electrodes and the like are formed at the same time, the formation of each layer of the substrate and the removal of a portion of the formed layer are repeated during the manufacturing process.

For this reason, at the stage of forming the protective layer, especially at the stage of forming the protective layer on the electrode, the surface of the protective layer becomes minutely uneven with steps, and as a result, coverage at these steps is important. This becomes a problem.

That is, in the conventional example shown in FIGS. 5 and 6, the step portion in this protective layer has a constricted shape, and the influence of pressure waves accompanying the expansion and contraction of bubbles in the heat-acting portion when ink is ejected. If exposed to water, cracks are likely to occur, and ink may penetrate into those areas, causing electrolytic corrosion or electrical breakdown.

Furthermore, if the protective layer to be formed has a high probability of having defects due to its manufacturing method, ink may penetrate through the defects, causing a significant reduction in the lifespan of the heating resistor layer, electrodes, etc.

The present invention has been made to solve the above-mentioned problems, and its first purpose is to make the step shape of the protective layer in the base (substrate) constituting the recording head into a shape without constriction. An object of the present invention is to provide an inkjet recording head and a substrate for the recording head, which are made difficult to generate cracks by doing so, and which prevent ink penetration by providing an enveloping layer around the heating resistance layer and the electrodes. .

[Means for Solving the Problems] To this end, the present invention provides an ink path communicating with an ejection port for ejecting ink, and a base forming part of a wall of an ink liquid chamber, which ejects ink from the ejection port. A heat generating resistor layer that generates thermal energy used for The step enveloping layer, the step covering layer filled between the step enclosing layer, the protective layer, the electrode, and the heat generating resistor layer, the heat generating resistor layer, the electrode, and the heat generating resistor layer. It is characterized by having a support body that supports the layer, the step enveloping layer, and the step covering layer.

[Function] According to the above configuration, due to the presence of the step enclosing layer and the step covering layer, the shape of the step of the protective layer due to the step of the heat generating resistor layer and the electrode becomes gentle, eliminating the constricted shape, etc. It becomes possible to increase the distance between the electrode and the heating resistor layer, especially at the step portion.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic partial cross-sectional view in the longitudinal direction of the liquid path for explaining the main part of an inkjet recording head structure showing an embodiment of the present invention, and FIG.
FIG. 3 shows a plan view of the substrate shown in FIGS. 1 and 2, respectively.

In these figures, reference numeral 100 indicates an inkjet recording head, which corresponds to the number of ejection ports, and includes a substrate 102 as a base on which electrothermal transducers 101 that generate heat used for ejecting ink are provided, and an electric Its main part is constituted by a grooved plate 103 having grooves provided corresponding to each of the heat exchangers 101.

By joining the substrate 102 and the grooved plate 103 at predetermined locations with an adhesive or the like, the electrothermal converter 10 of the substrate 102
A liquid path 104 is formed by the portion where the grooved plate 103 is disposed and the groove portion of the grooved plate 103, and the liquid path 104 has a heat acting portion lO5 in a part thereof.

The substrate 102 includes a support 106 made of silicon, glass, ceramics, etc., and a 5i0 layer on the support 106.
a lower layer 107 consisting of a 2-layer structure, and a band-shaped heating resistance layer 1 formed on the lower layer 107 in the longitudinal direction of the liquid path 104.
08, a common electrode 109 partially connected to the upper surface of the heating resistance layer 108 and disposed on the lower layer 107, and a selection electrode 110 connected to the common electrode 109 at a distance in the heating resistance layer 108. , common electrode 109, selection electrode 1
10 and a step covering layer 111 that covers the heating resistance layer 108 , and a step enveloping layer 113 that covers the electrodes 109 , 11 .
0 and around the heating resistance layer 108.

The step covering layer 111 enters between the step surrounding layer 113 and the step, sufficiently filling this portion, and also covers the outside of the step surrounding layer. That is, since the step covering layer 111 uses a liquid material, the surrounding layer 11
A large amount is formed on the stepped portion between the electrodes 109 and 110 and the heating resistor layer 10B, whereas a thin layer is formed on the flat portions of the electrodes 109 and 110 and the heating resistance layer 10B. This forms a protective layer for the electrodes 109, 110 and the heat generating resistor layer 108, and also forms a fifth layer in the step shape of the protective layer 112 laminated thereon.
The shape is such that the constriction shape shown in the figure and S6 is eliminated.

As a material constituting the protective layer 112, an inorganic insulating material having relatively excellent thermal conductivity and heat resistance is suitable. Examples of such materials include inorganic oxides such as Sin, titanium oxide, vanadium oxide, niobium oxide, molybdenum oxide, tantalum oxide, tungsten oxide, chromium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, yttrium oxide, Transition metal oxides such as manganese oxide, metal oxides such as aluminum oxide, calcium oxide, strontium oxide, barium oxide, silicon oxide, and complexes thereof, high resistance materials such as silicon nitride, aluminum nitride, boron nitride, tantalum nitride, etc. Nitride, composites of these oxides and nitrides, and semiconductors such as amorphous silicon and amorphous selenium can be processed using sputtering, CVD, vapor deposition, vapor phase reaction, and liquid coating methods even if they have low resistance in bulk. Examples include thin film materials that can be made highly resistive during the manufacturing process.

Furthermore, since the protective layer 112 is in direct contact with liquid ink and is particularly affected by the impact caused by the pressure waves generated during ink ejection, the upper layer of the protective layer 112 is made of a relatively sticky material such as metal, although it is not shown in the figure. A layer composed of an inorganic material with mechanical strength may be provided, and the material constituting the upper layer of this protective layer 112 may be a material from the periodic table 1II, such as Sc or Y.
Elements of group A, elements of group 1 Va such as Ti and Zr, elements of group Va such as Ta, V, and Nb, Cr, Mo,
Group Vla elements such as W, Group 1 elements such as Fe, Co, Nj: Ti-Ni, Ta-W.

Ta-Mo-Ni, Ni-0r, Fe-Go
, Ta-W, Fe-Ti, Fe-Ni, F
e-Cr.

Alloys of the above metals such as Fe-N1-fl:r; Ti-
B, Ta-8°1 (borides of the above metals such as f-B, W-B; Ti-C, Zr-C.

Carbides of the above metals such as VC, Ta-C, Mo-11:, N1-C; Mo-5i, Si, Ta-
Silicides of the above metals such as 5i; Ti-N, Nb-N,
Examples include nitrides of the above metals such as Ta-N. The upper layer of the protective layer can be formed using these materials by methods such as vapor deposition, sputtering, and CVD, and this upper layer may be a single layer using any of the above materials. On the other hand, the upper layer of the selection electrode 110 includes, in order from the electrode side, a step covering layer 10, a protective layer 112, and so on. An upper layer is provided in which the upper layer of the optional protective layer 112 and the second protective layer 114 are laminated. It may be provided in a portion.

The second protective layer 114 is made of an organic insulating material that has excellent ink liquid penetration prevention and liquid resistance properties, and has the following characteristics: (1) good film formability, (2) a dense structure with few pinholes, It is desirable that the material has physical properties such as not swelling or dissolving in the ink used, (1) good insulation properties when formed into a film, and (2) high heat resistance. Examples of such organic materials include the following resins, such as silicone resins, fluororesins, aromatic polyamides, and addition-polymerized polyimides.

Polybenzimidazole, metal chelate polymer.

Examples include titanate esters, epoxy resins, phthalic acid resins, thermosetting phenolic resins, P-vinylphenol resins, Zyrotsuta resins, triazine resins, BT resins (triazine resins and bismaleimide addition polymer resins), and the like.

In addition to this, the second protective layer 114 can also be formed by vaporizing polyxylylene resin and its derivatives.

Additionally, various organic compounds such as thiourea, thioacetamide, vinylferrocene, 1,3.5
-)-Licrobenzene, chlorobenzene, styrene,
Ferrocene, pyrroline, naphthalene, pentamethylbenzene, nitrotoluene, acrylonitrile, diphenylselenide, P-toluidine, P-xylene, N, N
-dimethyl-p-toluidine, toluene, aniline, diphenylmercury, hexamethylbenzene, malonitrile, tetracyanoethylene, thiophene, benzeneselenol, tetrafluoroethylene, ethylene, N
-nitron diphenylamine, acetylene, 1,2.
The second protective layer 114 can also be formed by a plasma polymerization method using 4-trichlorobenzene, propane, or the like.

However, if a high-density multi-orifice type recording head is to be manufactured, an organic material that is extremely easy to process using fine photolithography is used as the material for forming the second protective layer 114, in addition to the above-mentioned organic materials. It is desirable to do so. Specifically, such organic materials include, for example, polyimide isoindoquinazolinedione (product name: PIQ, manufactured by Hitachi Chemical), polyimide resin (product name: PYR^L I N, manufactured by DuPont).
, cyclized polybutadiene (trade name: JSR-CBR,C
Preferred examples include BR-M2O3 (manufactured by Japan Synthetic Rubber Co., Ltd.), Photoneese (trade name: Toshi Co., Ltd.), and other photosensitive polyimide resins.

The lower layer 107 is provided as a layer that controls the flow of generated heat toward the support body 106, and is a layer that controls the flow of generated heat toward the support body 106.
When thermal energy is applied to the ink liquid in step 05, more of the generated heat is transmitted to the heat acting part 105 side, and on the other hand, the electricity to the electrothermal converter 101 is turned off.
When this occurs, the selection of the constituent materials and the design of the layer thickness, etc. are made so that the remaining heat is quickly transferred to the support body 106 side.

The material constituting the lower layer 107 is the above-mentioned Si.
In addition to n, inorganic materials typified by metal oxides such as zirconium oxide, tantalum oxide, and magnesium oxide can be mentioned.

As the material constituting the heat generating resistor layer ioa, almost any material can be used as long as it generates desired heat when energized.

Examples of such materials include tantalum nitride, nichrome, silver-palladium alloys, silicon semiconductors, metals such as hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, vanadium, and their alloys, and their alloys. Preferred examples include borides.

Among these materials constituting the heating resistance layer 108, metal borides are particularly excellent, and among them, hafnium boride has the most excellent properties.
This is followed by zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heat generating resistor layer 108 can be formed using the above-described materials by techniques such as electron beam evaporation and sputtering.

The material constituting the electrodes 109 and 110 is selected from among many electrode materials, taking into consideration cost and electrical conductivity. Specifically, for example, ^11. ．． Examples include metals such as Cu, which are used to provide a predetermined size, shape, and thickness at a predetermined location by a method such as vapor deposition.

The step coating layer 111 is used to manufacture various electronic component materials, and the composition of the coating liquid is, for example, a silicon compound [RnSi (OH) 4-1 and additives such as a glass forming agent and an organic binder. It is dissolved in an organic solvent (ester, ketone, etc. whose main component is alcohol). This composition liquid is applied by spinner dipping, spraying,
Apply by brushing or other methods, for example at 100°C and 250°C.
The step coating layer 111 can be obtained as a film by betaening in several steps at 450° C. and 450° C. This is thought to be because after the coating solution is applied, the solvent evaporates and dehydration condensation polymerization of silanol groups proceeds to form a coating.

Silicon compound RnSi (014) 4-n is 5
i(0)1)4.

)1nSt (OH) 4-n, (RO) nsf
(OH) and -n are preferred. Compounds such as P, B, 811, As, Zn, and Ti are used as glass forming agents, and by adding these,
In order to improve the fracture resistance of the step covering layer 111, it is particularly preferable to add a Ti compound.

The thickness of the step covering layer Ill is 2000 Å in the flat part.
The following is preferable; if it exceeds this, the step covering layer 111 itself is likely to crack. Further, the step enveloping layer 113 is provided mainly for the purpose of concentrating the step covering layer 111 on the step, and its thickness is preferably equal to the thickness of the step of the step, and its width is the same as that of the heating resistor. Select the appropriate amount depending on the linear density of your body. Furthermore, the distance between the step part and the step part surrounding layer 112 is not particularly limited, but is preferably 0.05 to 2.0 μm, more preferably 0.1 to 1.0 μm. O.OS
If it is shorter than μl, the material constituting the step covering layer 111 will not be sufficiently embedded between the step portion and the step surrounding layer 113, while if it is longer than 2.0 μl, the material constituting the step covering layer 111 will not be sufficiently embedded between the step portion and the step surrounding layer 113. The step covering layer is formed in a tapered shape and is no longer effective in preventing cracks and the like.

That is, the step covering layer 111 obtained by firing a liquid raw material mainly containing a silicon compound is
This prevents the upper protective layer from constricting at the stepped portion, and further moves the stepped shape further away from the electrode and the heating resistor through the action of the stepped portion surrounding layer 113.

Further, in the embodiments shown in FIGS. 1 and 2, the width of the heating resistance layer 108 and the electrode 109 are equal, but if the heating resistance layer 108 is wider than the electrode 109,
Or, conversely, if the electrode 109 is wider, the above-mentioned preferred distance refers from the end of the electrode.

Examples of the material constituting the stepped portion surrounding layer 113 include inorganic materials typified by metal oxides similar to those used for the lower layer 107; In some cases, it can be formed only by patterning, which is effective in manufacturing.

The materials constituting the components of the grooved plate 103 and the common liquid chamber provided on the upstream side of the heat acting section 105 should be carefully selected to ensure that their shape is not affected by heat during the manufacturing or use environment of the recording head. In addition, the ink liquid can flow smoothly in the liquid path formed by these materials, and the surface accuracy can be easily achieved as desired. Most materials are effective as long as they can be processed so that they can flow.

Typical examples of such materials include ceramics, glass, metals, plastics, and silicon wafers. In particular, glass and silicon wafers are suitable materials because they are easy to process and have appropriate heat resistance, thermal expansion coefficient, and thermal conductivity. The outer surface around the ejection port 115 is treated with water-repellent treatment if the ink is aqueous, or oil-repellent if the ink is non-aqueous, so that the ink does not leak from the ejection port 115 and go around the outside of the ejection port 115. It is better to treat it.

The discharge ports 115 may be formed by attaching a photosensitive resin to the substrate 102, forming a pattern using photolithography, and then attaching a top plate.

FIG. 4 is a sectional view of a main part of a recording head showing another embodiment of the present invention.

Fig. 4 shows a diagram similar to Fig. 2, but the difference is that the protective layer 112 is made of two layers, and a step covering layer 111 is provided between each of these protective layers, and a liquid material is used. Since the step covering layer 111 formed in this manner does not have high adhesion to the electrode material, good adhesion is achieved by forming a multilayer protective layer.

Inkjet recording heads according to embodiments of the present invention will be specifically described below with reference to specific examples.

(Specific Example 1) The inkjet recording head shown in FIG. 1 was manufactured as follows.

After forming a SiO□ film as the lower layer 107 with a thickness of 6 μm on the support 106 by thermal oxidation of Si raw material, a pattern with a thickness of 6,500 layers and a width of 5 μm is formed as the step enveloping layer 113, and this is applied to the main part of the substrate. And so. 1500% HfB2 was applied to the main part of this substrate as a heating resistance layer 108 by sputtering.
The film was formed to a thickness of about 100 mm, and then one layer of 5,000 layers was successively deposited by electron beam evaporation to form an electrode of 8i109°110.

After that, a pattern as shown in Fig. 3 was formed using a photolithography process, and as a result, the size of the heat-active surface was 30 μm wide.
The length was 150 μm and the resistance including the resistance of the Aj2 electrode was 80Ω. Further, the distance between the step portion and the step surrounding layer 113 is 0.
It was 8 μ■.

Next, a solution containing a silicon compound as the main component was applied by spin coating, followed by a first heat treatment at 70°C in a nitrogen atmosphere, and then a first heat treatment at 120°C.
A second heat treatment at 200° C. and a third heat treatment at 200° C. were performed for 1 minute each. Furthermore, a baled silica film was formed at 430°C. As a result, the step covering layer 111 had a thickness of 1000 mm on the flat portion of the substrate.

Next, as the lower layer of the protection F1112, 5in2 with 2.0μI
Ta is deposited thickly on the entire surface of the substrate by magnetron high rate sputtering, and then Ta is deposited as the upper layer of the protective layer 112.
was similarly deposited to a thickness of 0.6 μm over the entire surface of the substrate by sputtering.

Next, PIQ was formed as a second protective layer 114 to a thickness of 20 .mu.m on the shaded area shown in FIG. 3 according to the following steps, thereby producing the substrate 102.

In other words, the main parts of the substrate on which the protective layer is formed are cleaned.

After drying, the PIQ solution was coated on the protective layer with a spinner, and then this was left at 80° C. for 10 minutes, and after drying the solvent, temporary baking was performed at 220° C. for 60 minutes. A photoresist is applied on top of this using a spinner, and after drying, it is exposed using a mask aligner and developed to obtain the desired Pf.
A Q layer pattern was obtained. Next, the PIQ layer was etched at room temperature using a PIQ etchant. After washing with water and drying, remove the photoresist with 11ill solution, then use 350°C.
Baking was performed for 60 minutes in a vacuum chamber to complete the process of forming the PIQ layer pattern. The shape of the removed portion around the heat-active surface is as shown in FIG. 3, and the size is 50 μm×250 μm.

Next, a grooved glass plate was adhered in a predetermined manner onto the substrate 102 created as described above. That is, in the same way as shown in FIG. 1, a grooved glass plate (groove size 50 μm wide x 50 μm deep x 2 mm long) was glued to the substrate 102 to form an ink introduction liquid path and a heat acting part. Ru.

Inkjet recording head A was obtained as described above.

A schematic exploded perspective view of this recording head is shown in FIG.

(Specific Example 2) A head B was obtained in the same manner as in Specific Example 1, except that a silicon compound-containing solution containing 10% of a titanium compound was used as the step covering layer 111.

(Specific Example 3) A head C was obtained in the same manner as in Specific Example 1, except that the protective layer 112 was made into two layers as shown in FIG. 4, and a step covering layer lll was provided between these layers.

(Comparative Example) As shown in FIGS. 5 and 6, a head D was obtained in the same manner as in Example 1 except that the step surrounding layer and the step covering layer were not provided.

To test the failure rate of inkjet recording heads A, B, C, and D, the electrothermal transducer of each head was
, 30 V rectangular pulse voltage was applied at a period of 3 kHz.

According to this, the failure rate of head D increased near the number of pulses lXl0', but for heads A and B.

For C, there is no change in failure rate up to lXl0' pulse, especially for head B, 5 x 10' pulse, and for head C, 8 x 10''.
There was no change in failure rate until pulse.

When the failed head D was observed under a microscope, it was found that cracks began to form at the stepped portion, leading to corrosion or wire breakage.

[Effects of the Invention] As is clear from the above description, according to the present invention, the shape of the step portion of the protective layer due to the step of the heating resistor layer and the electrode is reduced to a constricted shape due to the presence of the step surrounding layer and the step covering layer. Moreover, it becomes possible to increase the distance between the ink, the electrode, and the heat-generating resistive layer, especially at the step portion.

As a result, not only the coverage of the stepped portions of the electrode and heat generating resistor layer is improved, but also the stepped portions in contact with the liquid can be separated from the stepped portions of the electrode and heat generating resistive layer, and the protective layer is prevented from cracking. Even if a crack occurs, it is protected by the enveloping layer at the stepped part, resulting in excellent head durability.In addition, the heat-active surface that comes into contact with the ink has fewer irregularities, reducing resistance to ink flow. , stable discharge can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view in the longitudinal direction of the liquid path for explaining the main parts of an inkjet recording head according to an embodiment of the present invention, and FIG. 2 is a diagram taken along the dashed line XX' in FIG. 1. 3 is a partial plan view of the substrate shown in FIGS. 1 and 2, FIG. 4 is a schematic sectional view showing another embodiment of the present invention, and FIG. 5 is a partial plan view of the substrate shown in FIGS. A schematic exploded perspective view showing an example of an inkjet recording head constructed using the substrate shown in the figures to FIG. 4, and FIG. 6 a schematic cross-sectional view in the longitudinal direction of the liquid path showing the structure of a conventional inkjet recording head. , FIG. 7 is a schematic sectional view taken along the dashed line A^' in FIG. 100...Liquid jet recording head, 101...Electrothermal converter, 102...Substrate, 103...Grooved plate, 104...Liquid discharge section, 105...Heat action section, 106. ... Support, 107 ... Lower layer, 108 ... Heat generating resistor layer, 109.110 ... Electrode, 111 ... Step covering layer, 112 ... Protective layer, 113 ... Step part surrounding layer, 114...second protective layer, 115...discharge port. Figure Figure Figure Figure 5 Figure

Claims (1)

[Scope of Claims] 1) An ink path communicating with an ejection port for ejecting ink, and a base forming part of a wall of the ink chamber, which is used for ejecting ink from the ejection port. a heating resistance layer that generates thermal energy, an electrode connected to the heating resistance layer, a protective layer for protecting the heating resistance layer and the electrode from the ink, and a layer around the heating resistance layer and the electrode. The formed step enclosing layer; A step covering layer filled between each of the step enveloping layer, the protective layer, the electrode, and the heat generating resistor layer; the heat generating resistor layer, the electrode, and the protective layer. An inkjet recording head comprising: a support that supports the step enveloping layer and the step covering layer; 2) The inkjet recording head according to claim 1, wherein the protective layer is multilayered, and the step covering layer is formed between each protective layer. 3) The inkjet recording head according to claim 1 or 2, wherein the step covering layer is formed using a liquid material containing a silicon compound. 4) A recording head substrate constituting the inkjet recording head according to any one of claims 1 to 3.