JP7127409B2 - Liquid ejection head, liquid ejection unit, device for ejecting liquid, and method for manufacturing liquid ejection head - Google Patents

Description

The present invention relates to a liquid ejection head, a liquid ejection unit, an apparatus for ejecting liquid, and a method for manufacturing a liquid ejection head.

2. Description of the Related Art In the industrial and commercial printing fields, highly reliable liquid ejection heads are required.

In the prior art, for example, a liquid chamber substrate made of single crystal Si on which a surface treatment film is formed and a nozzle substrate are bonded with an adhesive. However, the adhesiveness between the liquid chamber substrate and the surface treatment film is poor, and the liquid discharge head using this film suffers initial failure and reliability failure. There is a problem that the surface treatment film may peel off and stable quality cannot be obtained. Therefore, it is necessary to perform a heat cycle test or the like on actual products to select non-defective products. Further, if the adhesion of the surface treatment film formed on the surface of the flow path forming member that forms the flow path of the liquid is poor, the quality and reliability of the liquid discharge head to which the film is applied cannot be sufficiently obtained. be.

For example, in Patent Document 1, for the purpose of improving adhesion between an adhesive and a surface treatment film formed on the surface of a flow path forming member, the surface treatment film is an oxide film containing Si, and the oxide film is tantalum. , niobium, titanium, hafnium, zirconium, tungsten, and other transition metals that form passivation films.
However, improvement of adhesion between the flow path forming member and the surface treatment film is not described or studied.

Further, Patent Document 2 discloses that an organic film is used as the surface treatment film.
However, since the organic film cannot completely block the permeation of moisture, there is a problem that a material that is not easily corroded by ink or the like must be used as the flow path forming member.

Further, Patent Document 3 discloses a SiO ₂ film as a surface treatment film.
However, the _SiO2 film used as the surface treatment film changes to hydroxide when exposed to a strong alkaline liquid, becomes easily ionized, and dissolves into the liquid, resulting in damage to the flow path forming member. There's a problem.

Metals such as Ni and Ti and alloy materials such as SUS are sometimes used for the surface treatment film, but metal films are often oxidized and easily ionized when they come into contact with acidic liquids. In the case of materials that are difficult to dissolve, there is a problem that the bonding function with the adhesive is impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid ejection head in which the adhesion of a surface treatment film is good and high reliability can be obtained.

In order to solve the above-described problems, the present invention provides a liquid ejection head having a flow path forming member for forming a flow path of liquid, the flow path forming member comprising an actuator substrate having liquid ejection energy generating means; a nozzle substrate bonded to the actuator substrate and formed with nozzles, wherein the actuator substrate and the nozzle substrate are made of Si; An oxide film is formed thereon, and a surface treatment film is formed on the oxide film, the surface treatment film containing an oxide of Si and an oxide of a transition metal selected from Groups 4 and 5. , the content of the Si is greater than the content of the transition metal on the side of the flow path forming member in terms of atomic ratio (atomic %), and the content of the transition metal on the side opposite to the flow path forming member is the same as the content of the Si and the ratio of Si to the transition metal gradually changes in the film thickness direction of the surface treatment film .

According to the present invention, it is possible to provide a liquid ejection head in which the adhesion of the surface treatment film is good and high reliability can be obtained.

1 is a perspective view of an example of a liquid ejection head according to the present invention; FIG. 1 is a longitudinal sectional view of a liquid chamber in an example of a liquid ejection head according to the present invention; FIG. FIG. 2 is a cross-sectional view in the lateral direction of a liquid chamber in an example of the liquid ejection head according to the present invention; 4A and 4B are partially enlarged views of an example of the liquid ejection head according to the present invention; FIG. It is a figure for _{demonstrating} the relationship of the ratio of _SiO2 and _Ta2O5 in a surface treatment film. It is the figure ₍ A) for demonstrating the relationship of the ratio of _SiO2 and Ta2O5 in a surface treatment film, and the figure ₍ B) for demonstrating the relationship of a ratio and intensity|strength. FIG. 8A is another diagram for explaining the relationship between the ratios of SiO ₂ and Ta ₂ O ₅ in the surface treatment film, and another diagram is for explaining the relationship between the ratio and the strength (B). FIG. 4 is a diagram for explaining patterns of changes in ratios of SiO ₂ and Ta ₂ O ₅ in a surface treatment film; 1 is a schematic diagram showing an example of a liquid ejection unit according to the present invention; FIG. FIG. 5 is a schematic diagram showing another example of the liquid ejection unit according to the present invention; FIG. 5 is a schematic diagram showing another example of the liquid ejection unit according to the present invention; FIG. 4 is a perspective view of an example of a liquid cartridge; FIG. 4 is a perspective view of another example of the device for ejecting liquid according to the present invention; FIG. 4 is a side view of another example of the device for ejecting liquid according to the present invention;

Hereinafter, a liquid ejection head, a liquid ejection unit, a device for ejecting liquid, and a method for manufacturing a liquid ejection head according to the present invention will be described with reference to the drawings. In addition, the present invention is not limited to the embodiments shown below, and can be changed within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. is also included in the scope of the present invention as long as the functions and effects of the present invention are exhibited.

The present invention provides a liquid ejection head having a flow path forming member that forms a flow path for liquid (sometimes referred to as ink), wherein the flow path forming member has a surface treatment film on the surface of the flow path for the liquid. is formed, the surface treatment film includes an oxide of Si and an oxide of a transition metal selected from Groups 4 and 5, and the Si content on the channel forming member side is the transition The content of the transition metal is higher than the content of the metal in terms of atomic ratio (atomic %), and the content of the transition metal is higher than the content of Si on the side opposite to the flow path forming member.

(liquid ejection head)
A "liquid ejection head" is a functional component that ejects and ejects liquid from nozzles.
The liquid to be ejected is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head. is preferred. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional-imparting materials such as polymerizable compounds, resins, and surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, etc., including solutions, suspensions, emulsions, etc. These are, for example, inkjet inks, surface treatment liquids, components of electronic elements and light emitting elements, and formation of electronic circuit resist patterns It can be used for applications such as liquids for liquids and material liquids for three-dimensional modeling.
Piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators that consist of a diaphragm and a counter electrode are used as energy sources for liquid ejection. includes those that

<Basic Configuration of Liquid Ejection Head>
A basic configuration of the liquid ejection head according to this embodiment will be described.
1 is a perspective view of the liquid ejection head according to this embodiment, FIG. 2 is a schematic cross-sectional view in the long side direction of the liquid chamber in FIG. 1, and FIG. 3 is a schematic cross-sectional view in the short side direction of the liquid chamber in FIG. Note that the liquid ejection head of this embodiment is a liquid ejection head having a piezoelectric actuator.

As shown in the figure, the liquid ejection head 1 of the present embodiment is of a side shooter type that ejects liquid droplets from nozzle holes provided on the substrate surface portion. 2. A vibration plate 3 is provided, and a pressurized liquid chamber partition 4, a pressurized liquid chamber 5, a fluid resistance portion 7, and a common liquid chamber 8 are formed. Each pressurized liquid chamber 5 is partitioned by a pressurized liquid chamber partition wall 4 .

Further, the subframe substrate 200 is formed with a droplet supply port 66 for supplying droplets from the outside, a common droplet flow path 9, and a gap 67 so that the vibration plate 3 can bend. Further, nozzle holes 6 are formed in the nozzle substrate 300 at positions corresponding to the individual pressurized liquid chambers 5 . A passivation film 50 is formed for the purpose of protecting the lead wiring layer. The liquid ejection head 1 is formed by joining the actuator substrate 100, the subframe substrate 200, and the nozzle substrate 300 together.

As shown in FIGS. 1 and 2, the actuator substrate 100 includes a vibration plate 3 forming a partial wall surface of the pressurized liquid chamber 5 and a piezoelectric member on the side facing the pressurized liquid chamber 5 via the vibration plate 3 . element 2 is formed. Further, a common droplet flow path 9 is formed on the diaphragm 3 surface of the common liquid chamber 8, and the liquid can be supplied from the outside from here. As shown in FIG. 2 , the piezoelectric element 2 formed on the side facing the pressurized liquid chamber 5 with the diaphragm 3 interposed therebetween is composed of a common electrode 10 , individual electrodes 11 and a piezoelectric body 12 .

In the liquid ejection head 1 formed in this manner, the liquid, for example, recording liquid (ink) is filled in each pressurized liquid chamber 5, and the recording liquid is ejected from the control unit based on the image data. A pulse voltage of, for example, 20 V is applied by an oscillation circuit to the individual electrode 11 corresponding to the nozzle hole 6 to be processed through the lead wire 40 and the connection hole 30 formed in the interlayer insulating film 45 .

By applying this voltage pulse, the piezoelectric body 12 itself shrinks in the direction parallel to the diaphragm 3 due to the electrostrictive effect, so that the diaphragm 3 bends in the direction of the pressurized liquid chamber 5 . As a result, the pressure in the pressurized liquid chamber 5 rises sharply, and the recording liquid is ejected from the nozzle hole 6 communicating with the pressurized liquid chamber 5 .

Next, after the application of the pulse voltage, the contracted piezoelectric body 12 returns to its original position, and the flexed vibration plate 3 returns to its original position. Ink supplied from the outside via the droplet supply port 66 is supplied from the common droplet flow path 9 and the common liquid chamber 8 to the pressurized liquid chamber 5 via the fluid resistance portion 7 .
By repeating this, droplets (liquid) can be continuously ejected to form an image on a recording medium (paper) arranged facing the liquid ejection head.

<Example of liquid ejection head according to the present embodiment>
Next, details of the liquid ejection head of the present embodiment will be described while showing a manufacturing method.
The manufacturing method of the liquid ejection head of the present embodiment includes a step of forming a surface treatment film on the surface of the flow path forming member in the liquid flow path, and other steps as necessary. The flow path forming member is a member for forming a liquid flow path, and includes, for example, the subframe substrate 200, the actuator substrate 100, and the nozzle substrate 300 as in the present embodiment.

First, the vibration plate 3 and the piezoelectric element 2 are formed on the actuator substrate 100 shown in FIG. 2 and the like by a known method. Next, an interlayer insulating film 45, a connection hole 30, a wiring pattern 42, a lead wire 40, and a lead wire pad 41 are formed by a known method.

Next, through holes 60 and gaps 67 are formed in the subframe substrate by, for example, a litho-etching method. A Si substrate is preferably used as the subframe substrate 200 .
Next, the subframe substrate 200 and the actuator substrate 100 are joined. The bonding method is not particularly limited, and can be changed as appropriate.

Regarding the above processes, either the process for the actuator substrate 100 or the process for the subframe substrate 200 may be performed first.

Next, the pressurized liquid chamber 5 is formed in the actuator substrate 100 . For forming the pressurized liquid chamber 5, an ICP etcher, for example, is used, and dry etching is performed using, for example, CF ₄ gas. However, in this case, C and F tend to remain as contaminants on the surface of the actuator substrate 100 after the pressurized liquid chamber 5 is formed.

Therefore, in this embodiment, for the purpose of removing C and F from the surface of the flow path forming member and for the purpose of oxidizing the surface of the flow path forming member, particularly the flow path forming member made of Si, for example, It is preferable to perform the _O2 plasma treatment at . As a result, contaminants such as C and F can be removed, factors that inhibit bonding can be eliminated, and by naturally oxidizing, the adhesion between the surface of the flow path forming member and the surface treatment film can be improved more than Si. can be improved. The amount of impurities (the amount of C, the amount of F) at the interface between the flow path forming member and the surface treatment film is preferably 5 atomic % or less.

Next, a surface treatment film is formed. By forming the surface treatment film, it is possible to secure the liquid resistance of the flow path forming member and prevent deterioration of the flow path forming member due to contact with liquid. FIG. 4 shows a cross-sectional view of an example of a portion where the surface treatment film is formed.

As the flow path forming member, it is preferable to use a single crystal Si substrate suitable for microfabrication technology as the precision and density of the liquid ejection head become higher. In this case, in order to form a siloxane bond (Si—O—Si bond) with a strong bonding force, the ratio of Si (atomic ratio (atomic %)) on the side of the flow path forming member of the surface treatment film is set higher than a predetermined value. It is preferable to make it large, so that the adhesion of the interface can be improved.

However, if the surface treatment film is made of Si oxide alone, it will change to a hydroxide in a strong alkaline liquid, become easily ionized, and dissolve into the liquid. There is a problem of damage.

For this reason, on the side opposite to the flow path forming member (also referred to as the flow path side), it is preferable that the ratio (atomic number ratio) of the Group 4 or Group 5 transition metal is greater than a predetermined value. problem can be suppressed.

As for the surface treatment film as a whole, it is preferable that the ratio of Si to the transition metal changes in the film thickness direction of the surface treatment film. As a result, the internal stress can be reduced when the surface treatment film is formed, and peeling of the interface caused by temperature effects in the transportation environment can be suppressed.

The transition metal in the surface treatment film is preferably at least one selected from Hf, Ta and Zr. As a result, liquid resistance (ink resistance) can be further improved.

The surface treatment film preferably has a Ta—Si bonding state. In this case, the bond at the interface of the surface treatment film can be made stronger, the adhesion of the surface treatment film can be further improved, and the liquid resistance can be further improved. The binding state can be identified by XPS (X-ray Photoelectron Spectroscopy) analysis.

The film thickness of the surface treatment film 52 is preferably 30 to 100 nm, more preferably 30 to 70 nm. In the case of the above range, the adhesion strength of the surface treatment film can be improved and resistance to droplets (ink) can be obtained.

The method of forming the surface treatment film can be changed as appropriate, and examples thereof include the ALD method, the sputtering method, the CVD method, and the like. From the viewpoint of coatability, the ALD method is particularly preferred. Since the ALD method can form a uniform film on unevenness, it has the advantage of being able to form a uniform film on a complicated structure.

Next, an example of the surface treatment film will be described. Here, an example in which a SiO ₂ film and a Ta ₂ O ₅ film are alternately formed by the ALD method will be described. In the ALD method, a desired film can be digitally formed for each molecular layer. However, although the film for each molecular layer should ideally be formed uniformly on the surface of the flow path forming member, the film is actually formed in an island shape due to variations in surface energy. there is Therefore, the island-shaped SiO ₂ film and the Ta ₂ O ₅ film are mixed at the interface between the flow path forming member and the surface treatment film. Adhesion depends on the contact area ratio of the interface between the SiO ₂ film and the Ta ₂ O ₅ film.

Normally, the step of forming the SiO ₂ film and the step of forming the Ta ₂ O ₅ film _are alternately formed. The membrane may be processed in multiple steps in succession. That is, the Si content can be adjusted by changing the number of steps. Film formation is performed while adjusting the film composition ratio of SiO ₂ and Ta ₂ O ₅ from the viewpoint of adhesion and internal stress between the surface treatment film and the flow path forming member.

FIG. 5 shows a diagram for explaining the relationship between the ratios of SiO ₂ and Ta ₂ O ₅ in the surface treatment film. FIG. 5 shows the ratio of SiO ₂ and Ta ₂ O ₅ in the film thickness direction of the surface treatment film, and the vertical axis represents the amount of SiO ₂ . _A large value _on the vertical axis means that the proportion of _SiO2 is large and the proportion of Ta2O5 is small, and a small value _on the vertical axis means that the proportion of _SiO2 is small and the proportion of _Ta2O5 is small. means big.
The ratio of SiO ₂ indicates the ratio of Si (atomic ratio (atomic %)), and the ratio of Ta ₂ O ₅ indicates the ratio of Ta (atomic ratio (atomic %)).

As shown in the figure, conventionally, there is no variation in the film thickness direction, and the ratio of SiO ₂ and Ta ₂ O ₅ is constant.

On the other hand, in one embodiment of the present invention, it is as follows.
(1) In order to improve the adhesion between the flow path forming member and the surface treatment film, the Si content is higher than the transition metal content on the side of the flow path forming member in terms of atomic percentage (atomic %).
(2) In order to improve ink resistance, the transition metal content is higher than the Si content on the side opposite to the flow path forming member in terms of atomic number ratio.

Moreover, it is preferable to do as follows.
(3) In order to reduce the internal stress between the flow path forming member side and the opposite side, the ratio of Si to the transition metal varies monotonically or gradually in the film thickness direction of the surface treatment film.

FIG. 6 shows a diagram (A) for explaining the relationship between the ratios of SiO ₂ and Ta ₂ O ₅ in the surface treatment film, and a diagram (B) for explaining the relationship between the ratio and the strength. FIG. 6(A) shows a graph when the ratio of SiO ₂ and Ta ₂ O ₅ is changed on the channel side of the surface treatment film (on the side opposite to the channel forming member). The axis is expressed as _SiO2 content. FIG. 6(B) shows the results of the peel test strength and the ink immersion test when the ratio is changed as in FIG. 6(A). Note that (a), (c), and (e) in FIG. 6A correspond to (a), (c), and (e) in FIG. 6B, and in FIG. b) and (d) are omitted.

The peel test strength is one of the adhesion evaluations of the surface treatment film, and is evaluated by attaching a predetermined tape and peeling it off. Further, the ink immersion test is one of the liquid resistance evaluations, in which the film is immersed in ink for a predetermined period, and the appearance is evaluated before and after.

As shown in the figure, when the Ta ₂ O ₅ composition ratio on the channel side becomes smaller, the overall ratio of SiO ₂ increases and the peel test strength tends to increase. However, beyond a certain range, the ink resistance deteriorates, and NG occurs in the ink immersion test.

FIG. 7 shows another diagram (A) for explaining the relationship between the ratios of SiO ₂ and Ta ₂ O ₅ in the surface treatment film, and another diagram (B) for explaining the relationship between the ratio and the strength. show. As shown in FIG. 7A, composition modulation is performed by changing the film thickness region on the side of the flow path forming member or on the side of the flow path.

Here, three examples of (a), (c), and (e) are shown, and (a), (c), and (e) correspond to (a'), (c'), and (e'). Yes. On the side of the flow path forming member, the film thickness in the region where the ratio of SiO ₂ is large is increased in the order of (a), (c), and (e). On the other hand, on the channel side, the film thickness in the region where the ratio of Ta ₂ O ₅ is high is increased in order of (a'), (c'), and (e').

FIG. 7B shows the results of the peel test and HCT (heat cycle test) test of the surface treatment film at that time. The HCT test is one of reliability evaluations.

As shown in the figure, the peel test strength increases as the film thickness in the region with a high SiO ₂ ratio on the channel forming member side or the film thickness in the region with a high Ta ₂ O ₅ ratio on the channel side increases. Although it rises, it starts to decline at a certain point, and a region where the HCT test is NG occurs. The reason for the decrease in the peel test strength in the middle is that the compression stress increases on the channel member side and the tensile stress on the channel side increases within the film thickness of the surface treatment film due to the inability to sufficiently modulate the composition. It is thought that the peel test strength decreased due to the stress difference.

In consideration of the above, in the surface treatment film on the flow path forming member side of the surface treatment film, the region where the ratio of Si is 80 atomic % or more is preferably 1 nm or more and 20 nm or less, and is 3 nm or more and 10 nm or less. is more preferred. When the thickness is 1 nm or more, it is possible to prevent the adhesive force between the flow path forming member and the surface treatment film from being lowered, thereby further suppressing the peeling. Moreover, when it is 20 nm or less, it is possible to prevent a large stress difference from occurring within the film thickness of the surface treatment film, and to further suppress a decrease in the peel test strength.

It is more preferable that the surface treatment film on the side of the flow path forming member has a Si ratio of 90% or more. can be prevented.

On the other hand, as the surface treatment film on the channel side, the region in which the ratio of Ta (transition metal) is 50% or more is preferably 1 nm or more and 20 nm or less, more preferably 3 nm or more and 10 nm or less. When it is 1 nm or more, deterioration of ink resistance can be prevented, and occurrence of NG in the ink immersion test can be further suppressed. Moreover, when it is 20 nm or less, it is possible to prevent a large stress difference from occurring within the film thickness of the surface treatment film, and to further suppress a decrease in the peel test strength.

It is more preferable that the surface treatment film on the channel side has a Ta (transition metal) ratio of 70% or more.

As shown in (3) of FIG. 5, the Si oxide and the transition metal oxide are compositionally modulated and inclined. The tilt pattern is not limited to this. FIG. 8 shows tilt patterns (1) to (3) as examples. It is preferable that the ratio of Si to transition metal changes monotonically or gradually in the film thickness direction of the surface treatment film, and the pattern of inclination is not limited to one.

A method for measuring the ratio of Si, transition metal and oxide thereof in the surface treatment film will be described. With respect to the channel forming member after forming the surface treatment film, the cross section of the surface treatment film is observed with a TEM (transmission electron microscope), and the length of each layer is measured. Also, regarding the composition, EDX (Energy Dispersive X-ray Spectroscopy) analysis is performed to quantify Si, transition metals and their oxides. This is possible because similar results are obtained by XPS (X-ray Photoelectron Spectroscopy) analysis.
The EDX analysis can be similarly performed on the liquid ejection head after the nozzle substrate 300 has been bonded, and quantification can be performed.

When the surface treatment film is formed, the surface of the subframe substrate 200 opposite to the actuator substrate 100 is protected with a support tape or the like so that the film is not formed by the ALD method. Such protection by the support tape or the like also plays a role in preventing the film from adhering to the lead-out wiring pad 41 by the ALD method and preventing electrical continuity.

However, if the support tape or the like is attached to the subframe substrate and placed in the ALD chamber, contaminants such as C tend to adhere to the surface of the flow path forming member due to the gas from the support tape. If the surface treatment film is formed in this state by the ALD method or the like, the film adhesion between the surface treatment film and the flow path forming member may decrease.

In this embodiment, the O ₃ treatment is preferably performed in the ALD apparatus, thereby removing the C amount. By removing the amount of C, it is possible to suppress a decrease in film adhesion.

In this embodiment, the O ₃ treatment can be changed as appropriate, but it is preferable to perform the O ₃ treatment before forming the surface treatment film. Normally, O ₃ is supplied per molecular layer, but it is preferable to treat the substrate surface with O ₃ in order to remove the C amount.

Next, a surface treatment film is formed in the same manner as above on the nozzle substrate 300 on which the nozzle holes 6 are formed. Note that this step may be performed before the above steps.
Then, it is bonded to the actuator substrate 100 obtained in the above steps. The joining method can be performed by a known method. In this embodiment, an adhesive is used.

The surface treatment film may be formed in the liquid flow path of the flow path forming member, that is, in a portion that can come into contact with the liquid, and can be changed as appropriate within a range in which the liquid resistance is ensured. For example, the surfaces of the through holes 60 and the individual through holes 61 of the subframe substrate 200, the common droplet flow path 9, the common liquid chamber 8, the fluid resistance portion 7, the pressurized liquid chamber 5, and the nozzle substrate 300 of the actuator substrate 100 , the surface of the nozzle hole 6, and the like.

FIG. 4A shows an enlarged schematic diagram of the A region in FIG. FIG. 4A shows that the surface treatment film 52 is formed on the portion of the through-hole portion 60 of the subframe substrate 200 that is in contact with the liquid.

FIG. 4B shows an enlarged schematic diagram of region B in FIG. In FIG. 4B, a surface treatment film 52 is formed on the surface of the actuator substrate 100 and the surface of the nozzle substrate 300, and both substrates are bonded via an adhesive 610. In FIG.

In the nozzle substrate 300, which is one of the flow path forming members of the present embodiment, the surface treatment film 52 is also formed in the region that comes into contact with the liquid. In this embodiment, the surface treatment film 52 is also formed on the ejection surface of the nozzle substrate 300 (the surface opposite to the actuator substrate 100), but the present invention is not limited to this.

The actuator substrate and nozzle substrate are preferably made of Si. In this case, since the nozzles are made of the same material, the effect of stress is reduced, and a greater effect can be expected in terms of preventing peeling after joining the nozzles.

According to the present embodiment, the adhesion between the surface of the flow path forming member on which the surface treatment film is formed and the surface treatment film, the adhesion between the surface treatment film and the adhesive, or the adhesion between the water-repellent layer and the like can be improved. It is possible to improve the quality and reliability of the liquid ejection head to which this is applied.

(Liquid discharge unit)
Next, the liquid ejection unit of the present invention will be described with reference to FIGS. 9 to 11. FIG.
The carriage 403 is equipped with a liquid ejection unit 440 in which a liquid ejection head 404 and a head tank 441 according to the present invention are integrated. The liquid ejection head 404 of the liquid ejection unit 440 ejects yellow (Y), cyan (C), magenta (M), and black (K) liquids, for example. Further, the liquid ejection head 404 is mounted with a nozzle row having a plurality of nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ejection direction facing downward.

Also, the "liquid ejection head" is not limited to the pressure generating means to be used. For example, in addition to the piezoelectric actuator described in the above embodiment (which may use a laminated piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, and a vibration plate and a counter electrode may be used. An electrostatic actuator or the like may be used.

Further, the terms used in the present application, such as image formation, recording, printing, printing, printing, modeling, etc., are synonymous.

A "liquid ejection unit" is a combination of functional parts and mechanisms integrated with a liquid ejection head, and is a collection of parts related to ejection of liquid. For example, the "liquid ejection unit" includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance/recovery mechanism, and a main scanning movement mechanism with a liquid ejection head.

Here, integration means, for example, that the liquid ejection head and functional parts or mechanisms are fixed to each other by fastening, adhesion, or engagement, or that one is held movably with respect to the other. include. Also, the liquid ejection head, the functional parts, and the mechanism may be configured to be detachable from each other.

For example, there is a liquid ejection unit in which a liquid ejection head and a head tank are integrated. An example is shown in FIG. Also, there is a type in which a liquid ejection head and a head tank are integrated by being connected to each other by a tube or the like. Here, it is also possible to add a unit including a filter between the head tank and the liquid ejection head of these liquid ejection units.

Further, there is a liquid ejection unit in which a liquid ejection head and a carriage are integrated.

Further, as a liquid ejection unit, there is one in which the liquid ejection head is movably held by a guide member constituting a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated. Also, there is a type in which the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated. An example is shown in FIG.

There is also a liquid ejection unit in which the liquid ejection head, the carriage, and the maintenance and recovery mechanism are integrated by fixing a cap member, which is a part of the maintenance and recovery mechanism, to a carriage to which the liquid ejection head is attached. .

Further, as a liquid ejection unit, there is one in which a tube is connected to a liquid ejection head to which a head tank or a channel component is attached, and the liquid ejection head and the supply mechanism are integrated. An example is shown in FIG. The liquid in the liquid storage source is supplied to the liquid ejection head through this tube.

It is assumed that the main scanning movement mechanism also includes a single guide member. Also, the supply mechanism includes a single tube and a single loading unit.

Further, as an example of the liquid ejection unit, there is a liquid cartridge in which the liquid ejection head of the present invention and an ink tank for supplying liquid to the liquid ejection head are integrated. According to this embodiment, it is possible to obtain a high-quality liquid cartridge that is excellent in durability and reliability.

An example of a cartridge is shown in FIG. This ink cartridge 80 integrates a liquid ejection head 1 having nozzles 81 and the like and an ink tank 82 for supplying ink to the liquid ejection head 1 . In the case of the liquid ejection head 1 in which the ink tank 82 is integrated as described above, the yield and reliability of the ink cartridge 80 can be improved by increasing the precision, density, and reliability of the actuator section. Therefore, the cost of the ink cartridge 80 can be reduced.

(Apparatus for ejecting liquid)
In the present application, a "device that ejects liquid" is a device that includes a liquid ejection head or a liquid ejection unit, drives the liquid ejection head, and ejects liquid. Devices that eject liquid include not only devices that can eject liquid onto an object to which liquid can adhere, but also devices that eject liquid into air or liquid.

The "liquid ejecting device" can include means for feeding, transporting, and ejecting an object to which liquid can adhere, as well as a pre-processing device, a post-processing device, and the like.

For example, as a "device that ejects liquid", an image forming device that ejects ink to form an image on paper, and powder is formed in layers to form a three-dimensional object (three-dimensional object). There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that ejects a modeling liquid onto a formed powder layer.

Further, the "apparatus for ejecting liquid" is not limited to one that visualizes significant images such as characters and figures with the ejected liquid. For example, it includes those that form patterns that have no meaning per se, and those that form three-dimensional images.

The above-mentioned "substance to which a liquid can adhere" means a substance to which a liquid can adhere at least temporarily, such as a substance to which a liquid adheres and adheres, a substance which adheres and permeates, and the like. Specific examples include media such as recording media such as paper, recording paper, recording paper, film, and cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, and test cells. Yes, and unless otherwise specified, includes anything that has liquid on it.

The material of the above-mentioned "thing to which a liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as the liquid can adhere even temporarily.

Further, the "liquid" is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head, but it should have a viscosity of 30 mPa·s or less at room temperature and pressure, or by heating or cooling. Preferably. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional-imparting materials such as polymerizable compounds, resins, and surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium. , edible materials such as natural pigments, solutions, suspensions, emulsions, etc. These are, for example, inkjet inks, surface treatment liquids, components of electronic elements and light emitting elements, and formation of electronic circuit resist patterns It can be used for applications such as liquids for liquids and material liquids for three-dimensional modeling.

Further, the ``device for ejecting liquid'' includes a device in which a liquid ejection head and an object to which liquid can be adhered move relatively, but is not limited to this. Specific examples include a serial type apparatus in which the liquid ejection head is moved and a line type apparatus in which the liquid ejection head is not moved.

In addition, as a "liquid ejecting device", there are other processing liquid coating devices that eject processing liquid onto the paper in order to apply the processing liquid to the surface of the paper for the purpose of modifying the surface of the paper, raw materials is dispersed in a solution, and sprays a composition liquid through a nozzle to granulate fine particles of the raw material.

Next, an example of an apparatus for ejecting liquid having a liquid ejection head or a liquid ejection unit according to the present invention will be described with reference to an inkjet recording apparatus shown in FIGS. 13 and 14. FIG. 13 is an explanatory perspective view of the same recording apparatus, and FIG. 14 is an explanatory side view of a mechanical portion of the same recording apparatus.

The ink jet recording apparatus 90 includes a printing mechanism including a carriage 98 movable in the scanning direction, a liquid ejection head 1 mounted on the carriage 98, an ink cartridge 99 for supplying ink to the liquid ejection head 1, and the like. A paper feed cassette (or a paper feed tray) 93 capable of stacking a large number of sheets 92 from the front side is detachably attached to the lower part of the apparatus main body. It also has a manual feed tray 94 that can be opened to manually feed the paper 92, takes in the paper 92 fed from the paper feed cassette 93 or the manual feed tray 94, and records a desired image by the printing mechanism section 91. After that, the paper is discharged to the paper discharge tray 95 mounted on the rear side.

The printing mechanism unit 91 holds a main guide rod 96, a sub guide rod 97, and a carriage 98, which are guide members horizontally mounted on left and right side plates (not shown), so as to be slidable in the main scanning direction. A plurality of ink ejection openings (nozzles) of a liquid ejection head 1 for ejecting ink droplets of respective colors of (Y), cyan (C), magenta (M), and black (Bk) are arranged in a direction intersecting the main scanning direction. , the ink droplet ejection direction is directed downward. In addition, each ink cartridge 99 for supplying ink of each color to the liquid ejection head 1 is exchangeably mounted on the carriage 98 .

The ink cartridge 99 is provided with an air port communicating with the atmosphere at the top and a supply port at the bottom for supplying ink to the liquid ejection head 1, and has a porous body filled with ink inside. The ink supplied to the liquid ejection head 1 is maintained at a slight negative pressure by the capillary force of the solid body. Further, although the liquid ejection heads 1 of each color are used as the liquid ejection heads 1, one liquid ejection head having nozzles for ejecting ink droplets of each color may be used.

Here, the carriage 98 has its rear side (paper conveying downstream side) slidably fitted on the main guide rod 96 and its front side (paper conveying upstream side) slidably mounted on the follower guide rod 97 . there is In order to move and scan the carriage 98 in the main scanning direction, a timing belt 104 is stretched between a driving pulley 102 and a driven pulley 103 which are rotationally driven by a main scanning motor 101 . , and the forward and reverse rotation of the main scanning motor 101 reciprocates the carriage 98 .

On the other hand, in order to convey the paper 92 set in the paper feed cassette 93 downward to the liquid ejection head 1, the paper feed roller 105 and the friction pad 106 for separating and feeding the paper 92 from the paper feed cassette 93 and the paper 92 are placed. A guide member 107 that guides, a transport roller 108 that inverts and transports the fed paper 92, a transport roller 109 that is pressed against the peripheral surface of the transport roller 108, and a delivery angle of the paper 92 from the transport roller 108 is defined. It has a tip roller 110 that The conveying roller 108 is rotationally driven by a sub-scanning motor through a gear train.

A print receiving member 111 serving as a paper guide member is provided to guide the paper 92 fed from the transport roller 108 below the liquid discharge head 1 so as to correspond to the moving range of the carriage 98 in the main scanning direction. . A conveying roller 112 and a spur 113 which are rotatably driven for sending out the paper 92 in the paper discharging direction are provided on the downstream side of the print receiving member 111 in the paper conveying direction. A roller 114, a spur 115, and guide members 116 and 117 forming a paper ejection path are provided.

During recording by the inkjet recording apparatus 90, the carriage 98 is moved and the liquid discharge head 1 is driven in accordance with image signals to discharge ink onto the stationary paper 92 to record one line. , the paper 92 is conveyed by a predetermined amount, and then the next line is recorded. Upon receiving a recording end signal or a signal indicating that the trailing edge of the paper 92 has reached the recording area, the recording operation is terminated and the paper 92 is discharged.

A recovery device 127 for recovering ejection failures of the liquid ejection head 1 is arranged at a position outside the recording area on the right end side in the moving direction of the carriage 98 . The recovery device 127 has cap means, suction means and cleaning means. The carriage 98 is moved to the recovery device 127 side during printing standby and caps the liquid ejection head 1 with the capping means to keep the ejection openings in a wet state, thereby preventing ejection failure due to ink drying. In addition, by ejecting ink unrelated to printing during printing, etc., the ink viscosity of all ejection ports is made constant, and a stable ejection state is maintained.

In the event of an ejection failure or the like, the ejection opening (nozzle) of the liquid ejection head 1 is sealed with a capping means, and the ink and air bubbles are sucked out from the ejection opening through a tube by a suction means, and the ink is applied to the ejection opening surface. Adhered ink, dust, and the like are removed by a cleaning means, and ejection defects are recovered. Also, the sucked ink is discharged to a waste ink reservoir provided at the bottom of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

As described above, since the ink jet recording apparatus 90 is equipped with the liquid ejection head 1 manufactured according to the present invention, stable ink ejection characteristics can be obtained, and image quality can be improved.

In the above description, the liquid ejection head 1 is used in the inkjet recording apparatus 90. However, the liquid ejection head 1 may be applied to an apparatus that ejects liquid droplets other than ink, such as liquid resist for patterning. .

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Examples 2 to 5 refer to Reference Examples 2 to 5, which are not included in the present invention.

(Example 1)
Vibration plate 3 and piezoelectric element 2 are formed on actuator substrate 100 made of Si shown in FIGS. formed.
Next, the subframe substrate 200 and the actuator substrate 100 were joined by forming the through holes 60 and the gaps 67 in the subframe substrate made of Si by the litho-etching method. Next, the actuator substrate 100 was processed by dry etching using an ICP etcher and CF ₄ gas to form the pressurized liquid chambers 5 .

Next, an O ₂ plasma treatment (50 W, 5 minutes) was performed in an ICP etcher to naturally oxidize the portions to be liquid flow paths.

Next, a surface treatment film is formed by ALD. A support tape was attached to a portion where a film was not formed by the ALD method. In this state, the substrate was placed in an ALD chamber, and a first layer of SiO ₂ film was formed with a thickness of 0.1 nm. Next, the step of forming the SiO ₂ film was followed by the step of forming the Ta ₂ O ₅ film. Adjustment was made by changing the number of steps so that the ratio of Si and Ta gradually changed in the film thickness direction of the surface treatment film. The SiO ₂ ratio and its film thickness in the surface treatment film, the Ta ₂ O ₅ ratio and its film thickness, and the film thickness of the surface treatment film were as shown in Table 1 below. Also, the ratios of SiO ₂ and Ta ₂ O ₅ were changed as shown in gradient pattern 1 in FIG.
Also, O ₃ treatment was performed for 5 minutes in the ALD apparatus during the ALD treatment. The O ₃ treatment was performed before forming the surface treatment film, and the O ₃ treatment was performed on the substrate surface.

After forming the surface treatment film, the cross section of the surface treatment film was observed with a TEM, and the length of each layer was measured. At this time, EDX analysis was performed to quantify the composition. Further, when XPS analysis was performed, it was observed as TaSiOx, and it was a film obtained in a Ta—Si bonding state.

Next, a surface treatment film was formed on the nozzle substrate 300 on which the nozzle holes 6 were formed under the same manufacturing conditions as above. Next, it was bonded to the actuator substrate 100 obtained in the above steps using an adhesive. Thus, the liquid ejection head of this example was produced.

(Examples 2-6, Comparative Examples 1-4)
Example 1 was the same as Example 1, except that it was changed as shown in Table 1 below.

(evaluation)
<Scratch strength>
As for the scratch strength, a scratch tester (CSR-5000) manufactured by Resca Co., Ltd. was used to evaluate the adhesion of the surface treatment film. Since the adhesion strength varies depending on the state of the indenter used for evaluation, the evaluation was performed using a spherical indenter with a stylus diameter of 15 μm. 50 mN or more is preferable, and 70 mN or more is more preferable.

<Ink immersion test>
In the ink immersion test, it is immersed in an alkaline ink for a long time (7 days) and judged from the appearance before and after.
[Evaluation criteria]
○: No change in appearance ×: Change in appearance

<Reliability test>
For the reliability test, an HCT (heat cycle test) was performed using the inkjet recording apparatus shown in FIGS. After the test, ejection evaluation is performed to check whether there is any problem.
[Evaluation criteria]
OK: No problem of ejection failure NG: Problem of ejection failure

Table 1 shows the production conditions, measured values, and evaluation results of each example and comparative example. In Table 1, "%" means "atomic %". In addition, "the nozzle part side" means the channel side.

Looking at Examples 1 to 6, when the SiO ₂ ratio on the flow path forming member side is high and the Ta ₂ O ₅ ratio on the flow path side is high, both adhesion and ink immersion are excellent. Good results have also been obtained in reliability tests.
On the other hand, in Comparative Examples 1 and 3, although the scratch test was relatively good, problems occurred during ink immersion, and NG occurred in the subsequent reliability test. In Comparative Examples 2 and 4, the film adhesion strength in the scratch test was insufficient, and NG occurred in the subsequent reliability test as well.

Further, when the impurities (C amount, F amount) at the interface were quantified by EDX analysis, in Comparative Examples 2 and 4, they exceeded 5 atomic %. There is a tendency that the more the impurities at the interface are reduced, the higher the scratch strength. When the interface impurities exceed 5 atomic%, the strength falls below 20 mN, and the reliability test after that is NG (causing peeling of the surface treatment film). is occurring.

REFERENCE SIGNS LIST 1 liquid discharge head 2 piezoelectric element 3 vibration plate 4 pressurized liquid chamber partition wall 5 pressurized liquid chamber 6 nozzle hole 7 fluid resistance portion 8 individual droplet supply hole 9 common droplet channel 10 common electrode 11 individual electrode 12 piezoelectric body 30 connection hole 40 extraction wiring 41 extraction wiring pad 42 wiring pattern 45 interlayer insulating film 50 passivation film 52 surface treatment film 60 through hole portion 61 individual through portion 66 droplet supply port 67 void 100 actuator substrate 200 subframe substrate 300 nozzle substrate 401 guide member 403 carriage 404 liquid ejection head 405 main scanning motor 406 drive pulley 407 driven pulley 408 timing belt 412 transport belt 413 transport roller 414 tension roller 440 liquid ejection unit 441 head tank 442 cover 443 connector 444 channel component 456 tube 491A, 491B side plate 491C back plate 493 main scanning movement mechanism 610 adhesive

Japanese Patent No. 6194767 JP 2012-91381 A JP-A-2004-98310

Claims (7)

A liquid ejection head having a flow path forming member that forms a liquid flow path,
The flow path forming member has an actuator substrate including liquid ejection energy generating means, and a nozzle substrate bonded to the actuator substrate and formed with nozzles,
the actuator substrate and the nozzle substrate are made of Si,
An oxide film is formed on a substrate at a portion of the flow channel forming member that serves as a flow channel for the liquid, and a surface treatment film is formed on the oxide film ,
The surface treatment film contains an oxide of Si and an oxide of a transition metal selected from Groups 4 and 5, and the content of Si on the side of the flow path forming member is equal to the content of the transition metal. more in terms of atomic ratio (atomic%) than the flow path forming member, the content of the transition metal on the side opposite to the flow path forming member is greater in terms of atomic ratio than the content of the Si, and the ratio of the Si to the transition metal gradually changes in the film thickness direction of the surface treatment film . 2. A liquid ejection head according to claim 1 , wherein said transition metal is at least one selected from Hf, Ta and Zr. 3. The liquid ejection head according to claim 1, wherein the surface treatment film has a film thickness of 30 nm or more and 100 nm or less. 4. The liquid ejection head according to claim 1 , wherein the surface treatment film has a Ta--Si bonding state. A liquid ejection unit comprising the liquid ejection head according to any one of claims 1 to 4 . a head tank for storing the liquid to be supplied to the liquid ejection head, a carriage for mounting the liquid ejection head, a supply mechanism for supplying the liquid to the liquid ejection head, a maintenance and recovery mechanism for maintaining and recovering the liquid ejection head, and the liquid 6. A liquid ejection unit according to claim 5 , wherein at least one of main scanning movement mechanisms for moving the ejection head in the main scanning direction is integrated with the liquid ejection head. A device for ejecting liquid, comprising the liquid ejection head according to any one of claims 1 to 4 , or the liquid ejection unit according to claim 5 or 6 .

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