JP2020019205A - Liquid discharge head, liquid discharge unit, liquid discharge device, and liquid discharge head manufacturing method - Google Patents

Abstract

To provide a liquid discharge head with high reliability thereon in which a surface processing film has excellent adhesion.SOLUTION: The liquid discharge head has a flow path forming member for forming a flow path for liquid. The flow path forming member has a surface processing film formed on a surface thereof in the flow path for liquid. The surface processing film contains an oxide of Si and an oxide of transition metal selected from a fourth group and a fifth group. At the flow path forming member side, contents of the Si are more in atomicity (atom%) than contents of the transition metal, and at the opposite side of the flow path forming member, contents of the transition metal are more in atomicity than contents of the Si.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a liquid discharge head, a liquid discharge unit, a device for discharging liquid, and a method for manufacturing a liquid discharge head.

  In the industrial and commercial printing fields, a highly reliable liquid ejection head is required.

  In the prior art, for example, a single-crystal Si liquid chamber substrate on which a surface treatment film is formed and a nozzle substrate are joined with an adhesive. However, the adhesion between the liquid chamber substrate and the surface treatment film is poor, and in the liquid discharge head to which the liquid chamber head is applied, initial failure and reliability are poor, or in the worst case, the surface of the liquid chamber substrate is in the middle of the nozzle substrate bonding step. There is a problem that the surface treatment film may be peeled off and stable quality cannot be obtained. For this purpose, it is necessary to carry out a heat cycle test or the like on an actual product and to select a good product, which requires man-hours, a work period, a decrease in yield, and an increase in cost. In addition, if the adhesion of the surface treatment film formed on the surface of the flow path forming member that forms the liquid flow path is poor, there is a problem that the quality and reliability of the liquid ejection head to which this is applied cannot be sufficiently obtained. is there.

For example, in Patent Document 1, in order to improve the adhesiveness between the adhesive and the surface treatment film formed on the surface of the 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 the like.
However, there is no description about improving the adhesion between the flow path forming member and the surface treatment film, and no study is made.

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

Patent Document 3 discloses an SiO ₂ film as a surface treatment film.
However, the SiO ₂ film as a surface treatment film changes to hydroxide with respect to a strongly alkaline liquid, is easily ionized, and is dissolved in the liquid. As a result, the flow path forming member is damaged. There's a problem.

  In some cases, a metal such as Ni or Ti or an alloy material such as SUS is used for the surface treatment film. However, the metal film is often oxidized when exposed to an acidic liquid and easily ionized. In the case of a material that is difficult to dissolve, there is a problem that the function of bonding with the adhesive is impaired.

  An object of the present invention is to provide a liquid discharge head in which the adhesion of a surface treatment film is good and high reliability is obtained.

  In order to solve the above problem, the present invention is a liquid ejection head having a flow path forming member for forming a liquid flow path, wherein the flow path forming member has a surface treatment film on a surface of the liquid flow path. Is formed, and the surface treatment film includes an oxide of Si and an oxide of a transition metal selected from Group 4 and Group 5; It is characterized in that the content of the transition metal is higher than the content of the metal in the atomic ratio (atomic%), and the content of the transition metal is higher in the atomic ratio than the content of the Si on the side opposite to the flow path forming member.

  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 is obtained.

FIG. 3 is a perspective view of an example of a liquid ejection head according to the present invention. FIG. 3 is a cross-sectional view of an example of a liquid ejection head according to the present invention in a liquid chamber longitudinal direction. FIG. 2 is a cross-sectional view in a lateral direction of a liquid chamber in an example of a liquid ejection head according to the present invention. FIGS. 3A and 3B are partially enlarged views of an example of a liquid discharge head according to the present invention. FIGS. It is a diagram for explaining the relationship between the ratio of SiO ₂ and _Ta 2 _{O 5} in the surface treatment film. FIG. 7A is a diagram for explaining the relationship between the ratio of SiO ₂ and Ta ₂ O ₅ in the surface treatment film, and FIG. 8B is a diagram for explaining the relationship between the ratio and the strength. FIG. 9A is another diagram (A) for explaining the relationship between the ratio 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. It is a diagram for explaining the pattern of change in the ratio of SiO ₂ and _Ta 2 _{O 5} in the surface treatment film. FIG. 3 is a schematic diagram illustrating an example of a liquid ejection unit according to the present invention. FIG. 9 is a schematic view illustrating another example of the liquid ejection unit according to the present invention. FIG. 9 is a schematic view illustrating 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. It is a perspective view in other examples of the device which discharges the liquid of the present invention. It is a side view in other examples of the device which discharges the liquid of the present invention.

  Hereinafter, a liquid discharge head, a liquid discharge unit, a device for discharging liquid, and a method for manufacturing a liquid discharge head according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiment described below, and can be changed in other embodiments, additions, modifications, deletions, and the like within a range that can be conceived by those skilled in the art. The present invention 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 is a liquid ejection head having a flow path forming member for forming a flow path of a liquid (sometimes referred to as ink), wherein the flow path forming member has a surface treatment film on a surface of the liquid flow path. Is formed, and the surface treatment film includes an oxide of Si and an oxide of a transition metal selected from Group 4 and Group 5; It is characterized in that the content of the transition metal is higher than the content of the metal in the atomic ratio (atomic%), and the content of the transition metal is higher in the atomic ratio than the content of the Si on the side opposite to the flow path forming member.

(Liquid ejection head)
The “liquid ejection head” is a functional component that ejects and ejects a liquid from a nozzle.
The liquid to be discharged is not particularly limited as long as it has a viscosity and a surface tension that can be discharged from the head, and the liquid has a viscosity of 30 mPa · s or less at room temperature, under normal pressure, or by heating and cooling. Is preferred. More specifically, solvents such as water and organic solvents, coloring agents such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, and the like, solutions, suspensions, emulsions, and the like. These include, for example, ink-jet inks, surface treatment solutions, 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.
As the energy generation source for discharging liquid, piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators using electrothermal transducers such as heating resistors, and electrostatic actuators composed of a diaphragm and a counter electrode are used. Are included.

<Basic configuration of liquid ejection head>
The basic configuration of the liquid ejection head according to the embodiment will be described.
FIG. 1 is a perspective view of the liquid discharge head according to the present 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 the present embodiment is a liquid ejection head having a piezoelectric actuator.

  As shown in the drawing, the liquid discharge head 1 of the present embodiment is of a side shooter type that discharges liquid droplets from nozzle holes provided in a substrate surface portion, and a piezoelectric element that generates liquid discharge energy on an actuator substrate 100. 2, a vibrating plate 3 and a pressurized liquid chamber partition 4, a pressurized liquid chamber 5, a fluid resistance part 7, and a common liquid chamber 8 are formed. Each pressurized liquid chamber 5 is partitioned by a pressurized liquid chamber partition 4.

  Further, the subframe substrate 200 is provided with a droplet supply port 66 for supplying a droplet from the outside, a common droplet flow path 9, and a gap 67 so that the diaphragm 3 can bend. The nozzle substrate 300 has nozzle holes 6 at positions corresponding to the individual pressurized liquid chambers 5. Further, 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.

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

  In the liquid ejection head 1 formed as described above, in a state in which each of the pressurized liquid chambers 5 is filled with a liquid, for example, a recording liquid (ink), the control section discharges the recording liquid based on image data. A pulse voltage of, for example, 20 V is applied to the individual electrode 11 corresponding to the nozzle hole 6 to be performed by the oscillation circuit via the lead-out line 40 and the connection hole 30 formed in the interlayer insulating film 45.

  By applying the voltage pulse, the piezoelectric body 12 contracts in the direction parallel to the diaphragm 3 due to the electrostriction effect, so that the diaphragm 3 bends toward the pressurized liquid chamber 5. As a result, the pressure in the pressurized liquid chamber 5 rises sharply, and the recording liquid is discharged from the nozzle holes 6 communicating with the pressurized liquid chamber 5.

Next, after application of the pulse voltage, the vibrating plate 3 which is bent because the contracted piezoelectric body 12 returns to its original position returns to its original position, so that the inside of the pressurized liquid chamber 5 is more negative than the inside of the common liquid chamber 8. Pressure is applied, and ink supplied from outside via the droplet supply port 66 is supplied to the pressurized liquid chamber 5 from the common liquid droplet channel 9 and the common liquid chamber 8 via the fluid resistance part 7.
By repeating this, droplets (liquid) can be continuously ejected, and an image is formed on a recording medium (paper) arranged opposite to the liquid ejection head.

<One example of the liquid ejection head of the present embodiment>
Next, details of the liquid ejection head of the present embodiment will be described with reference to a manufacturing method.
The method of manufacturing a liquid ejection head according to the present embodiment includes a step of forming a surface treatment film on the surface of a flow path forming member in a liquid flow path, and includes 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, the interlayer insulating film 45, the connection hole 30, the wiring pattern 42, the lead wiring 40, and the lead wiring pad 41 are formed by a known method.

Next, the through hole 60 and the void 67 are formed in the sub-frame substrate by, for example, a litho-etch method. As the subframe substrate 200, it is preferable to use a Si substrate.
Next, the subframe substrate 200 and the actuator substrate 100 are joined. The joining method is not particularly limited, and can be appropriately changed.

  Regarding the above steps, either the step of the actuator substrate 100 or the step of the subframe substrate 200 may be performed first.

Next, the pressurized liquid chamber 5 is formed in the actuator substrate 100. The pressurized liquid chamber 5 is formed by dry etching using, for example, an ICP etcher and using, for example, CF ₄ gas. However, in this case, C and F are likely to remain as contaminants on the surface of the actuator substrate 100 after the formation of the pressurized liquid chamber 5.

Therefore, in the present embodiment, for the purpose of removing C and F on 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, an ICP etcher is used. It is preferable to perform O ₂ plasma treatment at This makes it possible to remove contaminants such as C and F, to eliminate factors that hinder the bonding, and to perform natural oxidation, whereby the adhesion between the surface of the flow path forming member and the surface treatment film can be reduced as compared with Si. Can be improved. In addition, it is preferable that the impurity amount (C amount, F amount) at the interface between the flow path forming member and the surface treatment film is 5 atomic% or less.

  Next, a surface treatment film is formed. By forming the surface treatment film, liquid resistance of the flow path forming member can be ensured, and deterioration of the flow path forming member caused by contact with the liquid can be prevented. FIG. 4 is a cross-sectional view illustrating an example of a portion where the surface treatment film is formed.

  It is preferable to use a single-crystal Si substrate suitable for microfabrication technology as the flow path forming member becomes more precise and higher in density of the liquid ejection head. In this case, in order to form a strong siloxane bond (Si-O-Si bond), the ratio of Si (atomic ratio) on the flow path forming member side of the surface treatment film is higher than a predetermined value. It is preferable to increase the size, whereby the adhesion at the interface can be improved.

  However, if the surface treatment film is made of only Si oxide, it changes to hydroxide with respect to a strongly alkaline liquid, becomes easily ionized, and dissolves in the liquid. The problem of damage occurs.

  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 ratio) of the Group 4 or Group 5 transition metal be larger than a predetermined value. Problem can be suppressed.

  As for the entire surface treatment film, it is preferable that the ratio of Si to the transition metal changes in the thickness direction of the surface treatment film. This makes it possible to reduce the internal stress at the time of forming the surface treatment film, and it is possible to suppress the peeling of the interface caused by the temperature effect in the transport environment.

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

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

  The 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, it is possible to improve the adhesion of the surface treatment film and to obtain the resistance to droplets (ink).

  The method for forming the surface treatment film can be appropriately changed, and examples thereof include an ALD method, a sputtering method, and a CVD method. From the viewpoint of coatability, the ALD method is particularly preferable. The ALD method has an advantage that a uniform film can be formed even on a complicated structure because the film can be formed uniformly on the irregularities.

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 film to be formed can be digitally formed for each molecular layer. However, the film for each molecular layer should ideally be uniformly formed on the surface of the flow path forming member on which the film is formed. However, due to the variation in surface energy, the film is actually formed in an island shape. I have. Therefore, at the interface between the flow path forming member and the surface treatment film, the island-shaped SiO ₂ film and the Ta ₂ O ₅ film are mixed. The adhesion depends on the contact area ratio of the interface between the SiO ₂ film and the Ta ₂ O ₅ film.

Normally, a step of forming a SiO ₂ film and then a step of forming a Ta ₂ O ₅ film are alternately formed one by one. However, when increasing the Si content, the formation of the SiO ₂ film is performed. The film may be continuously processed in a plurality of steps. That is, the Si content can be adjusted by changing the number of steps. The film is formed while adjusting the film composition ratio of SiO ₂ and Ta ₂ O ₅ from the viewpoint of the adhesion between the surface treatment film and the flow path forming member and the internal stress.

Figure 5 shows a diagram for explaining a relationship of the ratio 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 thickness direction of the surface treatment film, and the vertical axis represents the amount of SiO ₂ . When the value of the vertical axis is large, the ratio of SiO ₂ is large and the ratio of Ta ₂ O ₅ is small. When the value of the vertical axis is small, the ratio of SiO ₂ is small and the ratio of Ta ₂ O ₅ is small. It 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, the following is performed.
(1) In order to improve the adhesion between the flow path forming member and the surface treatment film, the content of Si is higher in the atomic ratio (atomic%) than the content of the transition metal on the flow path forming member side.
(2) In order to improve the ink resistance, the content of the transition metal on the side opposite to the flow path forming member is higher in atomic ratio than the content of Si.

Further, it is preferable to perform the following.
(3) The ratio between Si and the transition metal changes monotonically or gradually in the thickness direction of the surface treatment film to reduce internal stress between the flow path forming member side and the opposite side.

FIG. 6 shows a diagram (A) for explaining the relationship between the ratio 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. 6A shows a graph in the case where the ratio of SiO ₂ and Ta ₂ O ₅ is changed on the flow path side (the side opposite to the flow path forming member) of the surface treatment film, and as in FIG. The axis is expressed as the amount of SiO ₂ . FIG. 6B shows the results of the peel test strength and the ink immersion test when the ratio is changed as in FIG. 6A. 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 evaluations of the adhesion of the surface-treated film, and is evaluated by attaching a predetermined tape and peeling it off. The ink immersion test is one of the evaluations of liquid resistance. The ink immersion test is immersed in the ink for a predetermined period, and is evaluated based on the appearance before and after.

As shown in the figure, when the composition ratio of Ta ₂ O ₅ on the flow channel side decreases, the ratio of SiO ₂ generally increases and the peel test strength tends to increase. However, if it exceeds a certain area, the ink resistance deteriorates, and NG occurs in the ink immersion test.

FIG. 7 shows another diagram (A) for explaining the relationship between the ratio 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, the composition modulation is performed by changing the film thickness region on the flow path forming member side or the flow path side.

Here, three examples of (a), (c), and (e) are shown, and (a), (c), and (e) are replaced with (a '), (c'), and (e '). Yes, it is. On the channel forming member side, the thickness of 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 thickness of the region where the ratio of Ta ₂ O ₅ is large is increased in the order of (a ′), (c ′), and (e ′).

  FIG. 7B shows a peel test result of the surface-treated film and an HCT (heat cycle test) test result at that time. The HCT test is one of the reliability evaluations.

As shown in the drawing, when the film thickness in the region where the ratio of SiO ₂ on the flow path forming member side is large or the film thickness in the region where the ratio of Ta ₂ O ₅ on the flow path side is large becomes thicker, the peel test strength becomes smaller. It rises, but then falls from a certain point, and an NG area occurs in the HCT test. The reason why the peel test strength decreases in the middle is that due to the inability to sufficiently modulate the composition, the compressive stress increases on the flow channel member side, and the tensile stress increases on the flow channel side. It is thought that a stress difference was caused, and the peel test strength was reduced by the influence.

  In consideration of the above, as 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 more preferably 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 a decrease in adhesion between the flow path forming member and the surface treatment film, and to further suppress peeling. When the thickness is 20 nm or less, it is possible to prevent a large stress difference from occurring within the thickness of the surface treatment film, and to further suppress a decrease in peel test strength.

  As the surface treatment film on the side of the flow path forming member, it is more preferable that the ratio of Si is 90% or more. In this case, the adhesion between the flow path forming member and the surface treatment film can be further increased, and peeling can be further reduced. Can be prevented.

  On the other hand, as the surface treatment film on the flow path side, the region where 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 generation of NG in an ink immersion test can be further suppressed. When the thickness is 20 nm or less, it is possible to prevent a large stress difference from occurring within the thickness of the surface treatment film, and to further suppress a decrease in peel test strength.

  It is more preferable that the ratio of Ta (transition metal) is 70% or more as the surface treatment film on the flow path side. In this case, the ink resistance is further improved, and NG in the ink immersion test can be reduced.

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

A method for measuring the ratio of Si, the transition metal and its oxide in the surface treatment film will be described. With respect to the flow path forming member after the formation of the surface treatment film, the cross section of the surface treatment film is observed with a TEM (transmission electron microscope) to measure the length of each layer. 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 can be obtained by XPS (X-ray Photoelectron Spectroscopy) analysis.
Note that the EDX analysis can be similarly performed on the liquid ejection head after the nozzle substrate 300 is joined, and the liquid ejection head can be quantified.

  When the surface treatment film is formed, the surface of the subframe substrate 200 opposite to the actuator substrate 100 is protected by a support tape or the like so that the film is not formed by the ALD method. Such protection by a support tape or the like also plays a role in preventing a problem such as a failure in which electrical conduction cannot be obtained due to a film formed by the ALD method on the lead wiring pad 41.

  However, when the support tape or the like is put into the ALD chamber with the sub-frame substrate attached, contaminants such as C easily adhere to the surface of the flow path forming member due to the influence of the gas from the support tape. If the surface treatment film is formed by the ALD method or the like in this state, the film adhesion between the surface treatment film and the flow path forming member may be reduced.

In the present embodiment, it is preferable to perform the O ₃ treatment 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 the present embodiment, the O ₃ treatment can be changed as appropriate, but the O ₃ treatment is preferably performed before forming the surface treatment film. Usually, O ₃ is supplied for each molecular layer, but it is preferable to perform O ₃ treatment on the substrate surface in order to remove the C amount.

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

  The surface treatment film may be formed in a liquid flow path in the flow path forming member, that is, at a location where the liquid can be in contact with the liquid, and can be appropriately changed as long as the liquid resistance is ensured. For example, the surface of the through-hole portion 60 or the individual through-hole portion 61 of the sub-frame substrate 200, the common droplet flow path 9, the common liquid chamber 8, the fluid resistance section 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 is an enlarged schematic diagram of the region A in FIG. FIG. 4A shows that a surface treatment film 52 is formed in a portion of the sub-frame substrate 200 in contact with the liquid in the through hole 60.

  FIG. 4B is an enlarged schematic diagram of a 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 the two substrates are joined via an adhesive 610.

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

  The actuator substrate and the nozzle substrate are preferably made of Si. In this case, since the structure is made of the same material, the influence of stress is reduced, and the effect of preventing peeling after nozzle bonding can be expected.

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

(Liquid discharge unit)
Next, the liquid ejection unit of the present invention will be described with reference to FIGS.
On the carriage 403, a liquid discharge unit 440 in which the liquid discharge head 404 and the head tank 441 according to the present invention are integrated is mounted. The liquid discharge head 404 of the liquid discharge unit 440 discharges, for example, liquid of each color of yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 404 has a nozzle row composed of a plurality of nozzles arranged in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ejection direction facing downward.

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

  Further, image forming, recording, printing, printing, printing, molding, and the like in the terms of the present application are all synonyms.

  The “liquid discharge unit” is a unit in which functional components and mechanisms are integrated with a liquid discharge head, and is an assembly of components related to liquid discharge. For example, the “liquid ejection unit” includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism with a liquid ejection head.

  Here, the term “integration” means, for example, a case where the liquid ejection head and the functional component or mechanism are fixed to each other by fastening, bonding, engagement, or the like, or a case where one is movably held with respect to the other. Including. Further, the liquid ejection head, the functional component, and the mechanism may be configured to be detachable from each other.

  For example, there is a liquid discharge unit in which a liquid discharge head and a head tank are integrated. An example is shown in FIG. In some cases, the liquid ejection head and the head tank are integrated with each other by a tube or the like. Here, a unit including a filter can be added between the head tank and the liquid discharge head of these liquid discharge units.

  There is a liquid discharge unit in which a liquid discharge head and a carriage are integrated.

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

  Further, as a liquid discharge unit, there is a liquid discharge head in which a cap member which is a part of a maintenance / recovery mechanism is fixed to a carriage to which a liquid discharge head is attached, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. .

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

  The main scanning movement mechanism includes a guide member alone. The supply mechanism also includes a tube unit and a loading unit alone.

  Further, as an example of the liquid discharge unit, there is a liquid cartridge in which the liquid discharge head of the present invention and an ink tank that supplies liquid to the liquid discharge head are integrated. According to the present embodiment, a high-quality liquid cartridge excellent in durability and reliability can be obtained.

  FIG. 12 shows an example of the cartridge. The ink cartridge 80 integrates a liquid ejection head 1 having nozzles 81 and the like, and an ink tank 82 that supplies ink to the liquid ejection head 1. As described above, when the ink tank 82 is an integrated liquid ejection head 1, the yield and reliability of the ink cartridge 80 can be improved by increasing the accuracy, density, and reliability of the actuator unit. As a result, the cost of the ink cartridge 80 can be reduced.

(Device for ejecting liquid)
In the present application, a “device that discharges liquid” is a device that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge liquid. The device that discharges a liquid includes not only a device that can discharge a liquid to which a liquid can be attached, but also a device that discharges a liquid into the air or into the liquid.

  The “device for discharging liquid” may include a unit for feeding, transporting, and discharging paper to which liquid can be attached, as well as a pre-processing device and a post-processing device.

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

  Further, the “device for discharging liquid” is not limited to a device in which a significant image such as a character or a graphic is visualized by the discharged liquid. For example, those that form a pattern or the like that has no meaning in itself, and those that form a three-dimensional image are also included.

  The above-mentioned "thing to which a liquid can be attached" means a thing to which a liquid can be attached at least temporarily, such as a thing which adheres and adheres, a thing which adheres and penetrates, and the like. Specific examples include 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 media such as inspection cells. Yes, unless otherwise specified, includes everything to which a liquid adheres.

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

  The “liquid” is not particularly limited as long as it has a viscosity and a surface tension that can be ejected from the head, but is not particularly limited at normal temperature and normal pressure, or a material whose viscosity becomes 30 mPa · s or less by heating and cooling. Preferably, there is. More specifically, solvents such as water and organic solvents, coloring agents such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, and the like, solutions, suspensions, emulsions, and the like. These include, for example, ink-jet inks, surface treatment liquids, components of electronic elements and light-emitting elements, and formation of resist patterns for electronic circuits. Liquid, three-dimensional modeling material liquid, and the like.

  In addition, the “device that discharges liquid” includes a device in which a liquid discharge head and a device to which liquid can be attached relatively move, but is not limited thereto. Specific examples include a serial device that moves the liquid ejection head, a line device that does not move the liquid ejection head, and the like.

  Other examples of the “liquid discharging device” include a processing liquid coating device that discharges a processing liquid onto a paper in order to apply the processing liquid to the surface of the paper for the purpose of modifying the surface of the paper, and a raw material. There is an injection granulation apparatus that granulates the fine particles of the raw material by spraying a liquid composition dispersed in a solution through a nozzle.

  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 the ink jet recording apparatus of FIGS. FIG. 13 is a perspective view of the recording apparatus, and FIG. 14 is a side view of a mechanism of the recording apparatus.

  The ink jet recording apparatus 90 includes a carriage 98 movable in the scanning direction inside the apparatus main body, 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. In the lower part of the apparatus main body, a sheet cassette (or a sheet tray) 93 capable of loading a large number of sheets 92 is detachably mounted from the front side. In addition, the printer has a manual feed tray 94 that is 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 required image by the printing mechanism unit 91. Thereafter, the paper is discharged to the paper discharge tray 95 mounted on the rear side.

  The printing mechanism unit 91 slidably holds a main guide rod 96, a sub guide rod 97, and a carriage 98, which are guide members laid horizontally on left and right side plates (not shown), in the main scanning direction. A liquid ejection head 1 for ejecting ink droplets of each color of (Y), cyan (C), magenta (M), and black (Bk) has a plurality of ink ejection ports (nozzles) arranged in a direction intersecting the main scanning direction. , With the ink droplet ejection direction facing downward. In addition, the ink cartridges 99 for supplying each color ink to the liquid ejection head 1 are exchangeably mounted on the carriage 98.

  The ink cartridge 99 is provided with an air port that communicates with the atmosphere above, a supply port that supplies ink to the liquid ejection head 1 below, and 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 material. Further, although the liquid discharge heads 1 of each color are used as the liquid discharge head 1, a single liquid discharge head having nozzles for discharging ink droplets of each color may be used.

  Here, the carriage 98 is slidably fitted to the main guide rod 96 on the rear side (downstream side of the paper conveyance), and slidably mounted on the front guide rod 97 on the front side (upstream side of the paper conveyance). I have. 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 driven to rotate by a main scanning motor 101, and the timing belt 104 is mounted on the carriage 98. , And the carriage 98 is reciprocated by the forward and reverse rotation of the main scanning motor 101.

  On the other hand, in order to transport the sheet 92 set in the sheet cassette 93 downward to the liquid ejection head 1, the sheet 92 is separated from the sheet supply roller 105 and the friction pad 106 for feeding the sheet 92 from the sheet cassette 93. A guide member 107 for guiding, a transport roller 108 for transporting the fed paper 92 in reverse, and a transport roller 109 pressed against the peripheral surface of the transport roller 108 and a feed angle of the paper 92 from the transport roller 108 are defined. And a leading end roller 110 that is formed. The transport roller 108 is driven to rotate by a sub-scanning motor via a gear train.

  An image receiving member 111 is provided as a paper guide member for guiding the paper 92 sent from the transport roller 108 below the liquid ejection head 1 in accordance with the movement range of the carriage 98 in the main scanning direction. . On the downstream side of the printing receiving member 111 in the sheet conveying direction, there are provided a conveying roller 112 and a spur 113 which are driven to rotate to send the sheet 92 in the sheet discharging direction. A roller 114, a spur 115, and guide members 116 and 117 forming a paper discharge path are provided.

  At the time of recording by the inkjet recording apparatus 90, the liquid ejection head 1 is driven in accordance with an image signal while moving the carriage 98, thereby ejecting ink to the stopped paper 92 to record one line, and thereafter, After the paper 92 has been conveyed by a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal indicating that the rear end of the sheet 92 has reached the recording area, the recording operation is terminated and the sheet 92 is discharged.

  A recovery device 127 for recovering a discharge failure of the liquid discharge head 1 is disposed 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, capping the liquid discharge head 1 by capping means and keeping the discharge port in a wet state, thereby preventing discharge failure due to ink drying. In addition, by discharging ink that is not related to printing during printing or the like, the ink viscosities of all the discharge ports are kept constant, and a stable discharge state is maintained.

  Further, in the case of a discharge failure, for example, the discharge outlet (nozzle) of the liquid discharge head 1 is sealed by the capping means, and bubbles and the like with ink are sucked out of the discharge port by the suction means through the tube. The attached ink, dust, and the like are removed by the cleaning means, and the ejection failure is recovered. The sucked ink is discharged to a waste ink reservoir provided at a lower portion 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 are obtained and image quality is improved.

  In the above description, the case where the liquid ejection head 1 is used in the inkjet recording apparatus 90 has been described. However, the liquid ejection head 1 may be applied to an apparatus that ejects droplets other than ink, for example, a liquid resist for patterning. .

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example 1)
The vibration plate 3 and the piezoelectric element 2 are formed on the actuator substrate 100 made of Si shown in FIGS. 1 to 3, and the interlayer insulating film 45, the connection hole 30, the wiring pattern 42, the lead wiring 40, and the lead wiring pad 41 are further formed. Formed.
Next, through-holes 60 and voids 67 were formed on the subframe substrate made of Si by a lithoetch method, and the subframe substrate 200 and the actuator substrate 100 were joined. Next, the pressurized liquid chamber 5 was formed on the actuator substrate 100 by performing dry etching using an ICP etcher and using CF ₄ gas.

Next, O ₂ plasma treatment (50 W, 5 minutes) was performed in the ICP etcher, and a portion serving as a liquid flow path was naturally oxidized.

Next, a surface treatment film is formed by the ALD method. A support tape was attached to a portion where a film was not formed by the ALD method. In this state, the substrate was put into an ALD chamber, and a first SiO ₂ film was formed with a thickness of 0.1 nm. Next, a step of forming a Ta ₂ O ₅ film was performed after the step of forming the SiO ₂ film. The adjustment was performed by changing the number of steps so that the ratio of Si and Ta gradually changed in the thickness direction of the surface treatment film. The SiO ₂ ratio and the thickness thereof, the Ta ₂ O ₅ ratio and the thickness thereof, and the thickness of the surface treatment film in the surface treatment film were as shown in Table 1 below. Further, the change in the ratio of SiO ₂ and Ta ₂ O ₅ was as shown in the inclined pattern 1 in FIG.
During the ALD processing, O ₃ processing was performed in the ALD apparatus for 5 minutes. O ₃ treatment is performed before forming the surface treatment film, it was carried out O ₃ treatment 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. In addition, XPS analysis revealed that the film was observed as TaSiOx and was obtained in a Ta-Si bonded state.

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

(Examples 2 to 6, Comparative Examples 1 to 4)
Example 1 was the same as Example 1 except for the changes as shown in Table 1 below.

(Evaluation)
<Scratch strength>
Regarding the scratch strength, the adhesive strength of the surface treatment film was evaluated, and a scratch tester (CSR-5000) manufactured by Resca Corporation was used. Since the adhesion varies depending on the state of the indenter at the time of evaluation, the evaluation was performed using a spherical indenter and a stylus diameter of 15 μm. It is preferably at least 50 mN, more preferably at least 70 mN.

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

<Reliability test>
For the reliability test, HCT (heat cycle test) was performed using the ink jet recording apparatus shown in FIGS. 13 and 14, and a temperature cycle (9 cycles) of −70 ° C. to 30 ° C. was performed. After the test, a discharge evaluation was performed to check for any defects.
[Evaluation criteria]
OK: No defective discharge failure NG: Defect defective discharge

  Table 1 shows manufacturing conditions, measured values, and evaluation results of each of the examples and the comparative examples. In Table 1, “%” means “atomic%”. Further, “the nozzle portion side” means the channel side.

As can be seen from 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 been obtained in reliability tests.
On the other hand, in Comparative Examples 1 and 3, the scratch test was relatively good, but a defect occurred in ink immersion, and NG occurred in the subsequent reliability test. In Comparative Examples 2 and 4, the film adhesion in the scratch test was insufficient, and NG also occurred in the subsequent reliability test.

  In addition, when the impurities (C content and F content) at the interface were quantified by EDX analysis, the results exceeded 5 atomic% in Comparative Examples 2 and 4. As the impurities at the interface are reduced, the scratch strength tends to be higher. When the interface impurities exceed 5 atomic%, the strength is lower than 20 mN, and NG (the cause of peeling of the surface treatment film) in a reliability test thereafter. Has occurred.

DESCRIPTION OF SYMBOLS 1 Liquid discharge head 2 Piezoelectric element 3 Vibration plate 4 Pressurized liquid chamber partition 5 Pressurized liquid chamber 6 Nozzle hole 7 Fluid resistance part 8 Individual droplet supply hole 9 Common droplet flow path 10 Common electrode 11 Individual electrode 12 Piezoelectric REFERENCE SIGNS LIST 30 connection hole 40 lead-out wiring 41 lead-out wiring pad 42 wiring pattern 45 interlayer insulating film 50 passivation film 52 surface treatment film 60 through-hole 61 individual through-hole 66 droplet supply port 67 void 100 actuator substrate 200 sub-frame substrate 300 nozzle substrate 401 guide member 403 carriage 404 liquid discharge 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 discharge unit 441 head tank 442 cover 443 connector 444 flow Parts 456 tubes 491A, 491B plate 491C backplate 493 main scan movement mechanism 610 adhesive

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

Claims (12)

A liquid ejection head having a flow path forming member that forms a liquid flow path,
In the flow path forming member, a surface treatment film is formed on a surface of the liquid flow path,
The surface treatment film includes an oxide of Si and an oxide of a transition metal selected from Group 4 and Group 5, and the content of Si on the flow path forming member side is the content of the transition metal. A liquid ejection head characterized in that the transition metal content is higher in atomic ratio than the Si content on the side opposite to the flow path forming member.   2. The liquid discharge head according to claim 1, wherein a ratio of the Si and the transition metal monotonously changes in a thickness direction of the surface treatment film.   2. The liquid discharge head according to claim 1, wherein the ratio of the Si and the transition metal gradually changes in a thickness direction of the surface treatment film.   The liquid ejection head according to any one of claims 1 to 3, wherein the transition metal is at least one selected from Hf, Ta, and Zr.   5. The liquid discharge head according to claim 1, wherein in the surface treatment film, a region where the amount of Si is 80 atomic% or more is 1 nm or more and 20 nm or less on the flow path forming member side.   The liquid discharge according to any one of claims 1 to 5, wherein, in the surface treatment film, a region where the transition metal is 50 atomic% or more is 1 nm or more and 20 nm or less on a side opposite to the flow path forming member. head.   7. The liquid ejection head according to claim 1, wherein the thickness of the surface treatment film is 30 nm or more and 100 nm or less. The flow path forming member has an actuator substrate including a liquid discharge energy generating unit, and a nozzle substrate formed with a nozzle, which is joined to the actuator substrate,
The liquid ejection head according to claim 1, wherein the actuator substrate and the nozzle substrate are made of Si.   9. The liquid ejection head according to claim 1, wherein the surface treatment film has a Ta-Si bonding state.   A liquid discharge unit comprising the liquid discharge head according to claim 1.   A head tank for storing liquid to be supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism for supplying liquid to the liquid discharge head, a maintenance and recovery mechanism for maintaining and recovering the liquid discharge head, and the liquid The liquid ejection unit according to claim 10, wherein at least one of a main scanning movement mechanism that moves the ejection head in the main scanning direction and the liquid ejection head are integrated.   An apparatus for discharging a liquid, comprising: the liquid discharge head according to claim 1; or a liquid discharge unit according to claim 10.