Patent Application
20060061626
The present invention relates to a substrate for an ink jet head for recording or printing a character, a symbol or an image by discharging a functional liquid such as ink on a recording medium including paper, plastic sheet, cloth or article, an ink jet head employing such substrate and a producing method therefor.
A general configuration of a head employed in ink jet recording includes plural discharge ports, ink flow paths communicated with such discharge ports, and plural electrothermal converting elements for generating thermal energy to be utilized for ink discharge. The electrothermal converting elements are constituted by heat-generating resistors and electrodes for supplying electric power to the heat-generating resistors, and such electrothermal converting elements are covered by an insulation film to secure insulation among the electrothermal converting elements. Each ink flow path communicates, at an end opposite to the discharge port, with a common liquid chamber which stores an ink supplied from an ink tank as an ink reservoir. The ink supplied to the common liquid chamber is guided to each ink flow path, and is retained by forming a meniscus in the vicinity of the discharge port. In this state, the electrothermal converting element is selectively driven to generate thermal energy, which is utilized for causing a rapid bubbling of the ink on a heat acting surface, whereby the ink is discharged by a pressure resulting from such state change.
The heat acting portion of the ink jet head in such ink discharge is exposed to a high temperature generated by heating of the heat-generating resistor, and is also subjected mainly to a composite action of an impact of a cavitation resulting from bubble formation and contraction of the ink, and a chemical action by the ink.
Therefore, the heat acting portion is usually provided with an upper protective layer for protecting the electrothermal converting element from such impact by cavitation and such chemical action of the ink.
Conventionally, a Ta film, relatively strong against the impact by cavitation and the chemical action of the ink, is formed with a thickness of 0.2 to 0.5 μm for realizing a service life and a reliability of the head at the same time.
Also in such heat acting portion, there results a phenomenon that a coloring material or an additive substance contained in the ink is decomposed in a molecular level by heating to a high temperature to form a difficultly soluble substance which is physically adsorbed on the upper protective layer. This phenomenon is called kogation. Such adsorption of the difficultly soluble organic or inorganic substance on the upper protective layer causes an uneven heat conduction from the heat-generating resistor to the ink, thereby resulting in an unstable bubble generation. Therefore an excellent Ta film, relatively free from kogation, is employed ordinarily.
In the following, a mode of generation and extinction of a bubble in the ink in the heat action part will be explained with reference to
In
Consequently, the upper protective layer maintained in contact with the ink is required to have excellent film properties in heat resistance, mechanical properties, chemical stability, oxidation resistance, alkali resistance etc. For the material usable for such upper protective layer, in addition to the aforementioned Ta film, there are already known a precious metal, a high-melting transition metal, an alloy thereof, and a nitride, a boride, a silicide or a carbide of such metal, or amorphous silicon. For example, Japanese Patent Application Laid-open No. 2001-105596 proposes a recording head of a long service life and a high reliability by forming an upper protective layer on a heat-generating resistor through an insulation layer, and forming the upper protective layer with an amorphous alloy represented by TaαFeβNiγCrδ (wherein 10 atomic % (at. %)≦α≦30 at. %, and α+β>80 at. %, and α<β, δ>γ and α+β+γ+δ=100 at. %) in which a surface thereof in contact with the ink includes an oxide of a constituent thereof.
However, a higher functionality such as a higher image quality and a higher recording speed for an image recorded by an ink jet recording apparatus is being required more strongly in recent years, and, in order to meet such requirement, there are desired an improvement in ink performance such as an improvement in color developing property and weather resistance for achieving a higher image quality and a prevention of a bleeding phenomenon (blotting between inks of different colors) in order to achieve a higher recording speed. For this reason, it has been tried to add various components to the ink. Also types of the ink have become diversified, such as light-colored inks of lower density in addition to black, yellow, magenta and cyan colors. Such inks cause a corroding phenomenon even on the Ta film, that has been considered stable as the upper protective film, by a thermal chemical reaction with such inks. Such phenomenon appears conspicuously in an ink containing a salt of a divalent metal such as Ca or Mg, or a component forming a chelate complex.
On the other hand, an upper protective layer with an improved corrosion resistance to the ink as explained above tends to generate a kogation more easily since the surface is scarcely damaged because of the higher corrosion resistance, whereby a discharge speed of the ink is lowered or becomes unstable. The kogation is generated little in the conventional Ta film presumably because the Ta film generates corrosion and kogation in a certain balanced level whereby the surface of the Ta film is abraded by such corrosion to suppress deposition of a product of kogation.
Also for achieving a further higher recording speed in the ink jet recording, it is necessary to further increase the drive frequency thereby executing a drive with shorter pulses. In such drive with shorter pulses, processes of heating, bubble generation, bubble extinction and cooling are repeated within a shorter period in the heat acting portion of the head, whereby a larger thermal stress is generated in a shorter time than in the conventional drive. Also in a drive with a shorter pulse, the cavitation impact resulting from the bubble generation and bubble contraction in the ink is concentrated in the upper protective film within a shorter time than in the conventional drive, whereby there is required an upper protective layer particularly excellent in the mechanical impact resistance.
For forming an ink jet head with an ink jet head substrate provided with such upper protective layer, there is employed, as disclosed in Japanese Patent Application Laid-open No. H6-286149, a method of forming an ink flow path with a soluble resin by a photolithographic patterning, then covering and hardening such pattern with an epoxy resin or the like, and eliminating such soluble resin after the substrate is cut into a piece.
It is also possible, as disclosed in Japanese Patent Application Laid-open No. 2002-113870, to achieve a higher durability and a higher reliability by constituting the upper protective layer with two layers, employing an amorphous Ta film of a high ink corrosion resistance as a lower layer and a Ta film of relatively low generation of kogation as an upper layer.
However, in case of elongating an ink discharge element (to 0.5 inches or larger) for achieving a higher recording speed or in case of employing diversified inks containing additives for improving a light fastness or a gas resistance of the inks on a recording medium, there are generated strains by a difference in the linear expansion coefficient of such components, and by a stress in the resin layer constituting walls of the liquid flow path or the discharge port, and an influence on the interface by inks of new types, thus leading to a peeling phenomenon between the covering resin layer constituting the walls of the liquid flow path or the discharge port and the upper protective layer on the heater substrate. Also, even in case an organic adhesion promoting layer is provided on the upper protective layer, there may result a peeling at the interface between the organic adhesion promoting layer and the upper protective layer to cause a penetration of the ink onto the substrate and to induce a corrosion of the wirings, thereby hindering satisfactory recording or reliability in quality over a prolonged period.
An object of the present invention is to improve adhesion between an upper protective layer of a substrate for an ink jet head, having a portion coming into contact with an ink, and a resin layer, thereby providing an ink jet head and a substrate therefor capable of ensuring reliability over a prolonged period.
Another object of the present invention is to provide a substrate for an ink jet head with an improved adhesion between an upper protective layer and resin layer even in case of a smaller dot for a higher definition of a recorded image or of a longer recording element for a higher recording speed or in case of employing diversified inks thereby enabling a higher density of the head, an ink jet head provided with such substrate, and a producing method thereof.
Another object of the present invention is to provide a configuration of an upper protective layer realizing a high durability and a high reliability even for highly corrosive inks, thereby providing a substrate for an ink jet head and an ink jet head of a long service life and a producing method thereof.
Another object of the present invention is to provide a substrate for ink jet comprising a base plate formed with a heat-generating resistor for generating energy for discharging ink, an electrode wiring electrically connected with said heat-generating resistor, and an upper protective layer provided above said heat-generating resistor and said electrode wiring, and comprising a TaCr alloy, wherein said upper protective layer is formed with a construction made by resin on an upper portion thereof and said resin construction is fixed on said upper protective layer.
Another object of the present invention is to provide an ink jet head comprising, a discharge port for discharging a liquid, a liquid flow path communicating with said discharge port and having a portion for applying thermal energy for discharging said liquid to said liquid, a heat-generating resistor for generating said thermal energy, an electrode wiring electrically connected with said heat-generating resistor, and an upper protective layer provided above said heat-generating resistor and said electrode wiring, and comprising a TaCr alloy, wherein said upper protective layer is formed with a construction made by resin on an upper portion thereof and said resin construction is fixed on said upper protective layer:
Another object of the present invention is to provide a producing method for an ink jet head including, on a substrate, a heat-generating resistor constituting a heat generating portion, an electrode wiring electrically connected with said heat-generating resistor, an upper protective layer provided on said heat-generating resistor and said electrode wiring and having a contact surface with an ink, and a liquid flow path member formed by a resin layer on said substrate, comprising, a step of forming an upper protective layer in which a Ta layer is laminated on a layer formed by a TaCr alloy, a step of selectively patterning said Ta layer and selectively removing said Ta layer, a step of forming the liquid flow path member in a portion where the layer formed by said TaCr alloy is exposed by said removing step.
Another object of the present invention is to provide a substrate for an ink jet head, having an excellent adhesion between an upper protective layer and a resin layer and enabling to form a pattern of a liquid flow path with a high precision thereby providing an ink jet head of a high reliability, also not causing a peeling of a member constituting a liquid flow path even in an ink jet head elongated to 0.5 inches or larger thereby ensuring a high reliability over a prolonged period, an ink jet head and a producing method thereof.
Another object of the present invention is to provide a substrate for an ink jet head enabling to form a pattern of a liquid flow path with a high precision by an excellent adhesion between an upper protective layer and a member constituting the liquid flow path, thereby ensuring a high reliability even in case of a smaller dot formation for achieving a higher definition in a recorded image or of a high-speed drive for achieving a high-speed recording, an ink jet head and a producing method thereof.
In
The heat acting portion of the ink jet head is exposed to a high temperature resulting from heat generation by the heat-generating resistor, and is also principally subjected to a cavitation impact resulting from a bubble generation in the ink and a bubble contraction thereafter and a chemical action by the ink. For this reason, the upper protective layer 107 is provided on the thermal action portion in order to protect the electrothermal converting element from such cavitation impact and chemical action of the ink. On the upper protective layer 107, there is formed a discharge element including a discharge port 110, utilizing a member 109 for forming a flow path.
On an ink jet head substrate 200, which is same as the ink jet head substrate 100 shown in
It is also possible, as shown in
In the following, there will be explained, with reference to
Then a covering resin layer 303 is formed in order to form a wall of the ink flow path and a discharge port. Prior to forming the covering resin layer 303, a silane coupling process or the like may be suitably applied in order to improve adhesion. The covering resin layer 303 can be coated on a substrate for ink jet, on which the pattern of the ink flow path is formed, by suitably selecting an already known coating method. The coated covering resin layer 303 is patterned by a photolithographic process. Then an ink supply aperture 306 is formed from a rear surface of the substrate by anisotropic etching, sand blasting or anisotropic plasma etching. The ink supply aperture 206 is formed most preferably by chemical anisotropic etching of silicon utilizing tetrramethylhydroxylamine (TMAH), NaOH or KOH. Then, for eliminating the soluble solid layer 301, there are executed a flush exposure with a deep UV light, a development and a drying.
The substrate, bearing the nozzle portion formed through the steps explained in
The upper protective layer coming into contact with the ink, is required to have excellent film characteristics such as a heat resistance, mechanical properties, a chemical stability, an oxidation resistance and an alkali resistance, and an excellent adhesion to the organic adhesion promoting layer and the nozzle-constituting member, and is constituted of Ta and Cr. It is preferably constituted of Ta100-xCrx in which x≧12 at. %.
A thickness of the upper protective layer 107 is selected within a range of 50 to 500 nm, preferably 100 to 300 nm. Also the upper protective layer has at least a compression stress, preferably not exceeding 1.0×1010 dyn/cm2. The upper protective layer 107 can be formed by various methods, but can generally be formed by a magnetron sputtering method utilizing a high frequency (RF) power source or a direct current (DC) power source.
A film formation with the apparatus shown in
In the present invention, the film formation can be executed by a binary simultaneous sputtering utilizing a Ta target and a Cr target and applying electric powers thereto from two power sources respectively connected thereto. In such case, it is possible to independently regulate the electric power applied to each target. It is also possible to obtain a film of a desired composition by preparing plural alloy targets adjusted in advance to desired compositions and to execute sputtering with a single target or simultaneously with plural targets.
At the formation of the upper protective layer 107, a strong film adhesion can be obtained by heating the substrate to 100 to 300° C. as explained above. Also a strong film adhesion can be achieved by a film formation with a sputtering method capable of forming particles of a relatively high kinetic energy as explained in the foregoing.
Also a strong film adhesion can be obtained by providing the film at least with a compression stress, not exceeding 1.0×1010 dyn/cm2. Such film stress can be regulated by suitably setting a flow rate of the Ar gas introduced into the film forming apparatus, a power applied to the target and a heating temperature of the substrate.
In the ink jet apparatus shown in
Photocouplers 2107, 2108 constitute home position detecting means, for confirming presence of a lever 2109 of the carriage 2120 in the position of the photocouplers thereby switching the rotating direction of the driving motor 2101. There are also provided a member 2110 for supporting a cap member 2111 for capping an entire face of the recording head 2200, and suction means 2112 for suction removal of ink in the cap member 2111 thereby achieving a suction recovery of the recording head 2200 through an aperture 2113 in the cap. A cleaning blade 2114 and a movable member 2115 for supporting the cleaning blade in movable manner in front-rear direction are supported by a support plate 2116 in a main body of the apparatus. The cleaning blade 2114 is not limited to the illustrated form and any known cleaning blade can naturally be applicable.
A lever 2117 for starting a suction of a suction recovery operation is moved by a movement of a cam 2118 engaging with the carriage 2120, thereby controlling the driving power of the driving motor 2101 through transmission means such as a clutch. A recording control unit (not shown) for supplying a signal to a heat generating unit 2110 provided in the recording head 2200 and for controlling the function of the aforementioned mechanisms is provided in the main body of the recording apparatus.
The ink jet recording apparatus 2100 of the above-explained configuration executes a recording by a reciprocating motion of the recording head 2200 over an entire width of the recording paper P conveyed onto the platen 2106 by the recording medium supplying apparatus, and is capable of a high-speed recording of a high precision, as the recording head 2200 is prepared by a method explained in the foregoing.
In the following, the present invention will be clarified further by examples of formation of the upper protective layer 107 and of an ink jet head utilizing the same. However, the present invention is not limited by such examples.
The apparatus shown in
[Film Forming Operation]
At first a thermal oxide film was formed on a monocrystalline silicon wafer, and such silicon wafer (substrate 4004) was placed on the substrate holder 4003 in the film forming chamber 4009 of the apparatus shown in
[Film Forming Condition]
Then, by a binary sputtering method utilizing a Ta target and a Cr target with a variable power to each target, a Ta100-xCrx film was formed with a thickness of 200 nm on the thermal oxide film of the silicon wafer, thereby obtaining samples 1 to 7.
[Evaluation of Film Properties]
A composition analysis was conducted on each of the obtained samples 1 to 7 by a Rutherford back scattering (RBS). Obtained results are shown in Table 1. As shown in Table 1, films of different compositions can be obtained by changing the powers supplied to the Ta and Cr targets.
[Film Stress]
Then a film stress of each sample was measured from an amount of deformation of the substrate before and after the film formation. As a result, with an increase in the Cr concentration in the Ta100-xCrx film, the film stress tended to change from a compression stress to a tensile stress and a film adhesion tended to decrease. A strong film adhesion can be obtained by forming a film stress at least as a compression stress and not exceeding 1.0×1010 dyn/cm2.
[Adhesion with Resin]
In order to simply evaluate an adhesion between a Ta88Cr12 film 107 (representing a film with a composition ratio of Ta 88 at. % and Cr 12 at. %; hereinafter composition being represented in a similar manner) of the present example and an organic adhesion promoting film (polyether amide resin) 307, a tape peeling test was conducted after a pressure cooker test (PCT).
The tape peeling test was conducted in the following manner. On a silicon wafer bearing the upper protective layer 107, an organic adhesion promoting film (polyether amide resin) 307 was formed with a thickness of 2 μm, and squares of 1×1 mm in a checkerboard pattern of 10 (longitudinal)×10 (lateral)=100 squares were formed with a cutter knife on the organic adhesion promoting film 307. Then a PCT was conducted by immersion in an alkaline ink under conditions of 121° C. and 2.0265×105 Pa (2 atm.) for 10 hours. Thereafter, an adhesive tape was applied on the squares in the checkerboard pattern and peeled, and a number of squares peeled by the adhesive tape among 100 squares was investigated. As a result, a generally satisfactory result was obtained, though peeling was observed in about 15 squares among 100 (Table 2).
A method similar to that in Example 1 was employed to evaluate an adhesion between the Ta film and the organic adhesion promoting film (polyether amide resin) 307 after PCT, and the obtained result is shown in Table 2.
As shown in Table 2, a peeling was generated at the interface between the Ta film and the organic adhesion promoting film 307 after the PCT, clearing indicating a deterioration of the adhesion property.
A method similar to that in Example 1 was employed to evaluate an adhesion of Ta100-xCrx films of different compositions after PCT, and the obtained results are shown in Table 2.
A method similar to that in Example 1 was employed to evaluate an adhesion after PCT. Evaluations were made on Ta20Fe61Cr14Ni5 (Comparative Example 2) and Ta87Fe10Cr2Ni1 (Comparative Example 3), and the obtained results are shown in Table 2.
As will be apparent from these results, the Ta20Fe61Cr14Ni5 film and Ta87Fe10Cr2Ni1 film, conventionally employed as the upper protective film, could not provide a sufficient adhesion property because of the peeling at the interface between the upper protective layer 107 and the organic adhesion promoting film 307.
As explained in the foregoing, the adhesion between the upper protective layer 107 and the organic adhesion promoting layer 307 after the PCT, in the Ta100-xCrx film, tended to become lower in a film with a low Cr content, and was within a satisfactory range in case X was equal to or higher than 12 at. %.
In addition to the aforementioned results in the presence of an adhesion promoting layer, similar results were obtained in the absence of the adhesion promoting layer, and it was identified that a Ta100-xCrx film (X≧12 at. %) was effective for the adhesion regardless of the presence or absence of the adhesion promoting layer.
[Evaluation of Ink Jet Properties]
In the present example, a Si substrate or a Si substrate in which a driving IC is formed is used for a sample for evaluating the ink jet properties. In case of a Si substrate, an SiO2 heat accumulation layer 102 (
Then an SiO2 interlayer insulation film 103 of a thickness of 1.2 μm was formed by sputtering or CVD. Then a Ta40Si21N39 heat-generating resistor layer 104 of a thickness of 50 nm was formed by reactive sputtering employing a Ta—Si target. This operation was conducted at a substrate temperature of 200° C. Then an Al film for the metal wiring 105 was formed with a thickness of 200 nm by sputtering.
Then a patterning was executed by a photolithographic process to form a heat acting portion 108 of 26×26 μm in which the Al film was eliminated. Then an SiN insulating member of a thickness of 300 nm as a protective film 106 by plasma CVD.
Then, as an upper protective layer 107, a Ta88Cr12 film was formed with a thickness of 200 nm by sputtering under varying powers to a Ta target and a Cr target.
Then the upper protective layer 107 was patterned by dry etching.
Subsequently, in order to improve adhesion between the upper protective layer and a nozzle-constituting member, an organic adhesion promoting film (polyether amide resin) 307 was formed with a thickness of 2 μm, whereby an ink jet head substrate was obtained.
Such ink jet head substrate was employed in a producing method shown in
As shown in Table 3, it was identified that, despite of a slight abrasion after continuous discharge up to 2.0×108 pulses, the upper protective layer was stable with stable discharge characteristics.
An ink jet head was prepared in the same manner as in Example 8, except that the upper protective layer 107 was prepared with a Ta film. Such ink jet head was subjected to a discharge durability test as in Example 1, and an obtained result is shown in Table 3. As shown in Table 3, the discharge became impossible before reaching 2.0×108 pulses in Comparative Example 4. An analysis conducted by disassembling the ink jet head proved that the corrosion reached the heat-generating resistor layer and caused a breakage thereof.
Ink jet heads were prepared in the same manner as in Example 8, except that the upper protective layers 107 were prepared with compositions and thicknesses as shown in Table 3. Such ink jet heads were subjected to a discharge durability test as in Example 8, and obtained results are shown in Table 3.
Ink jet heads were prepared in the same manner as in Example 8, except that the upper protective layers 107 were prepared with compositions and thicknesses as shown in Table 3.
Such ink jet heads were subjected to a discharge durability test as in Example 8, and obtained results are shown in Table 3.
As shown in Table 3, Ta20Fe61Cr14Ni5 (Comparative Example 5) showed scarce abrasion and was stable in the discharge durability test.
Ta87Fe10Cr2Ni1 (Comparative Example 6) showed a abrasion to about a half of the film thickness.
These results indicate followings.
As will be apparent from the results shown in Table 3, the stability of the upper protective layer 107 in the discharge durability test against abrasion is dependent on the composition of Ta100-xCrx film, and becomes superior as the Cr content increases. More specifically, the upper protective layer 107 is extremely stable against abrasion in case X≧12 at. % in the composition of the Ta100-xCrx film.
Also the upper protective film 107 preferably has a film thickness of 100 to 500 nm. A film thickness less than 100 nm may result in an insufficient protective ability against ink, while a film thickness exceeding 500 nm may hinder an efficient energy conduction from the heat-generating resistor layer to the ink, thus resulting in a large energy loss.
In these examples, it was possible to obtain excellent durability even with a film thickness of about 100 nm. As regards the film stress, at least a compression stress, not exceeding 1.0×1010 dyn/cm2 could provide a strong film adhesive force with an excellent durability.
As explained in the foregoing examples, it is rendered possible, by constituting the upper protective layer 107 with an alloy of Ta and Cr, by forming a resin (flow path-forming member 109) on the upper protective layer 107 and by fixing such resin on the upper protective layer 107, to provide an ink jet head substrate enabling to realize a higher density, an ink jet head provided with such substrate, and an ink jet apparatus equipped with such ink jet head.
In the present example, the upper protective layer 107 has a two-layered configuration, and, in the heat acting portion, there is employed a two-layered configuration constituted of an upper Ta layer 111 and a lower TaCr layer 112 while, under the flow path forming member 109, there is employed a one-layered configuration of the lower layer 112 only.
More specifically there is shown a case of employing a Ta80Cr20 film as the lower film 112 of the upper protective film 107 and a Ta film as the upper film 111.
The lower film 112 was formed by a binary sputtering utilizing a Ta target and a Cr target, with a composition of Ta80Cr20 and a thickness of 130 nm on the insulation layer. Conditions of binary sputtering were determined by analyzing the composition in advance by changing powers for Ta sputtering and for Cr sputtering. Also instead of binary sputtering, there may be executed a sputtering with a TaCr alloy target of a composition known in advance.
Thereafter the upper layer 111 was formed with a thickness of 100 nm by sputtering utilizing a Ta target. The film formation was executed in continuous manner in the same sputtering chamber.
Thereafter the Ta film constituting the upper layer 111 was patterned by an ordinary photolithographic process by steps of resist patterning (resist coating, exposure and development), Ta etching and resist stripping.
In this operation, the pattern of the Ta film can be arbitrarily selected by a photomask pattern at the exposure step. Therefore, the pattern was so selected as to form a Ta film on the heat generating part (heat acting portion 108) but not to form Ta film as the upper layer 111 where the liquid flow path forming member 109 is to be formed, as shown in
The etching of the TaCr film was conducted with a dry etching apparatus, selecting an etching gas, a gas pressure and a power capable of achieving a selective etching ratio with the underlying insulating protective layer. In the formation of the pattern of the TaCr film, it was formed under the portion 1090 for forming the liquid flow path forming member as shown in
Also as shown in
The PCT was conducted by immersion in an alkaline ink under conditions of 121° C. and 2.0265×105 Pa. (2 atm.) for 10 hours. Obtained results are shown in Table 4. These results indicate that the Ta80Cr20 film had a satisfactory adhesion.
After the patterning of the Ta80Cr20 film constituting the lower layer 112 of the upper protective layer 107 and the Ta film constituting the upper layer 111, a soluble solid layer 301 was coated by a spin coating method on the substrate, and was exposed to form a shape to constitute an ink flow path. The shape of the ink flow path could be obtained with an ordinary mask and a deep UV light. Then a covering resin layer 303 was laminated, then exposed with an exposure apparatus and was developed to form a discharge port 110. Subsequently, after formation of an ink supply aperture 306 by an anisotropic etching of silicon with TMAH, a portion to be dissolved of the covering resin layer 303 was eliminated by a flush exposure to a deep UV light, a development and a drying. The substrate, bearing the nozzle portion formed through the steps explained in the foregoing, is cut and separated with a dicing saw or the like into a chip, which is subjected to an electrical connection for driving the heat-generating resistor and an adjoining of an ink supply member, thereby completing an ink jet head.
Thus prepared ink jet head provided a satisfactory recording quality in an evaluation of discharging an alkaline ink of pH 10. Also in case this ink jet head, after immersion in this ink for 3 months at 60° C., provided a satisfactory recording quality in an ink discharging evaluation, and did not show a peeling of the covering resin layer 303.
There is shown a case of employing a single-layered film of Ta only as the upper protective layer.
In the present comparative example, a Ta film of a thickness of 230 nm was formed by sputtering with a Ta target.
Thereafter the Ta film was patterned by an ordinary photolithographic process by steps of resist patterning (resist coating, exposure and development), Ta etching and resist stripping.
In this operation, the pattern of the Ta film can be arbitrarily selected by a photomask pattern at the exposure step.
In order to simply evaluate the adhesion between the Ta film of a thickness of 230 nm, and the liquid flow path member 109 and the organic adhesion promoting film 307 constituting the lower liquid flow path member, there was executed a tape peeling test. The evaluation was made by executing the tape peeling test in an initial state and after a pressure cooler test (PCT).
The PCT was conducted by immersion in an alkaline ink under conditions of 121° C. and 2.0265×105 Pa (2 atm.) for 10 hours. Obtained results are shown in Table 4.
Based on these results, in which the Ta film showed a peeling after the PCT, it was confirmed that the adhesion was superior in the configuration of the foregoing Example 17 employing Ta80Cr20 as the lower film 112 of the upper protective layer 107 and a Ta film as the upper layer film 111.
Thereafter, a soluble solid layer 301 was coated by a spin coating method on the substrate bearing the upper protective layer 107, and was exposed to form a shape to constitute an ink flow path. The shape of the ink flow path could be obtained with an ordinary mask and a deep UV light. Then a covering resin layer 303 was laminated, then exposed with an exposure apparatus and was developed to form a discharge port 110. Subsequently, after formation of an ink supply aperture 306 by an anisotropic etching of silicon with TMAH, a portion to be dissolved of the covering resin layer 303 was eliminated by a flush exposure to a deep UV light, a development and a drying. The substrate, bearing the nozzle portion formed through the steps explained in the foregoing, is cut and separated with a dicing saw or the like into a chip, which is subjected to an electrical connection for driving the heat-generating resistor and an adjoining of an ink supply member, thereby completing an ink jet head.
Thus prepared ink jet head provided a satisfactory recording quality in an evaluation of discharging an alkaline ink of pH 10. However, this ink jet head, when immersed in this ink for 3 months at 60° C., showed a portion of non-discharge and could not provide a satisfactory recording quality. In an observation of the ink jet head, a peeling of the covering resin layer 303 was observed and there was confirmed a connected state of the ink flow paths.
In this example, it is rendered possible, by forming a TaCr film in a lower layer, coming into contact with the liquid flow path member, of the upper protective film on the heater substrate, and by forming a Ta film in an upper layer coming into contact with the ink, to improve the adhesion between the upper protective layer and the resin layer constituting the liquid flow path even in case of a smaller dot for achieving a higher definition in the recorded image or of an elongated head for achieving a higher recording speed, or in case of employing diversified inks, thereby providing an ink jet head substrate and an ink jet head enabling to realize a higher density, and an ink jet apparatus equipped with such ink jet head.
Also a two-layered configuration of the upper protective layer realizes a high durability and a high reliability for diversified inks such as an ink showing a high discharge instability by kogation and an ink with a high corrosive property, thereby providing an ink jet head substrate and an ink jet head of a long service life, and an ink jet apparatus equipped with such ink jet head.
In the foregoing examples, there has been explained an ink jet recording head of which discharge elements such as a discharge port and an ink flow path are prepared by a photolithographic technology, but the present invention also includes a configuration in which an orifice plate constituting a discharge port or a top plate constituting an ink flow path is separately formed and adhered, for example, with an adhesive material, onto the upper protective layer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-380822 | Dec 2002 | JP | national |
| 2002-380823 | Dec 2002 | JP | national |
| 2003-413498 | Dec 2003 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP03/16712 | 12/25/2003 | WO | 5/16/2005 |
