JP2003326710A - Method for forming protective film and ink jet head employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect an ink channel from being clogged with coating solution when an organic film for insulating an electrode from electrolytic components in ink is formed. <P>SOLUTION: After a bonding member consisting of a base member 1 and a cover member 2 constituting an ink jet head is coated with an organic solution, gas is fed to the outer surface of the bonding member and into the ink channel 10 in the bonding member before a liquid sucking member 50 is bonded tightly to the end face of the bonding member opposite to the gas inflow side. Excess organic solution on the surface of the bonding member and in the ink channel 10 is thereby moved toward the liquid sucking member 50 and sucked by the liquid sucking member 50. Consequently, an ink jet head having a uniform organic insulation film and exhibiting high structural and electrical reliability is provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an insulating film formed on a surface of a base material and an inkjet head provided with the insulating film formed by this manufacturing method.

[0002]

2. Description of the Related Art Today, non-impact printers such as ink jet systems, which are suitable for color printing and multi-step printing, are rapidly becoming popular in place of impact printers. Above all,
The drop-on-demand method, which discharges the necessary ink only during printing, is drawing attention because of its good printing efficiency, low cost, and low running cost. In such a drop-on-demand system,
The piezo method using a piezoelectric element (Kaiser method) and the thermal jet method using bubbles are the mainstream.

However, the piezo method has a drawback that it is difficult to reduce the size because it uses a piezoelectric element and is not suitable for high density. Further, although the thermal jet method is suitable for increasing the density, it generates bubbles in the ink by heating the heater and uses the energy of the bubbles for ejecting the ink, so that the durability of the ink is improved. Demanding. Further, there is a problem that it is difficult to extend the life of the heater and the power consumption is increased because the heater is heated.

In order to solve such a drawback, an ink jet system utilizing a shear mode of a piezoelectric material has been proposed. In this method, an electrode is formed on an ink channel wall made of a piezoelectric material, and electric power is supplied to this electrode to apply an electric field in a direction orthogonal to the polarization direction of the piezoelectric material to deform the channel wall in a shear mode. . Ink droplets are ejected by utilizing the pressure fluctuation caused by this deformation. With this method, the nozzle density is increased,
It is possible to realize low power consumption and high driving frequency.

The structure of an ink jet head using such a shear mode will be described with reference to FIG. FIG. 6 is a partially exploded perspective view of the inkjet head. The ink jet head has a plurality of grooves 12 formed therein, and is a base member 1 made of a piezoelectric body that is vertically polarized in FIG.
By adhering the cover member 2 in which the ink supply port 21 and the common ink chamber 22 are formed and the nozzle plate 3 provided with the plurality of nozzle holes 31 for ejecting ink droplets,
The ink channel 10 is formed. One groove 12
Adjacent channel walls 11 that sandwich the (ink channel 10)
The plurality of grooves 12 are configured such that the polarization directions of the piezoelectric material face each other. Metal electrodes 5 for applying an electric field to the piezoelectric material are formed on the surfaces of the channel walls 11, respectively. Further, a conductive member 8 is embedded in an end portion of the ink channel 10 opposite to the nozzle plate 3, and the external connection substrate 4 in which a connection electrode 41 such as a flexible substrate is formed in the conductive member 8. Are connected using an anisotropic conductive adhesive. Ink channel 10
An insulating film (not shown) is formed on the inner wall of the sheet to prevent the metal electrode 5 and the conductive member 8 from coming into contact with the ink.

Since the ink contains an electrolyte component, if the insulating film has a structural defect such as a pinhole,
The ink and the metal electrode 5 come into contact with each other, resulting in generation of bubbles and corrosion of the metal electrode 5.

In order to improve the reliability of this insulating film, a polyparaxylylene film which can be formed with a uniform film thickness on a complicated surface shape is generally used. However, the surface of the base material on which the polyparaxylylene film is to be formed is 10
If a void with a diameter of less than μm is present, the polyparaxylylene monomer cannot penetrate into this void,
Only extremely thin polyparaxylylene film can be formed in the void portion. In some cases, the polyparaxylylene film itself cannot be formed. For this reason, when forming a polyparaxylylene film, it is necessary to prevent narrow voids from existing on the surface on which the polyparaxylylene film is formed.

An invention for solving this problem is disclosed in Japanese Patent Laid-Open No. 8-7.
It is disclosed in Japanese Patent No. 3569. In the present invention, as a method for coating a polyparaxylylene film, a liquid resin film is thinly applied in advance on the surface on which the polyparaxylylene film is formed, and the surface is formed by forming the polyparaxylylene film on this surface. Provided is a method of coating a polyparaxylylene film, which fills existing voids and is excellent in reliability.

[0009]

However, when the liquid resin film that fills the voids on the surface on which the polyparaxylylene film is formed is formed, the following problems occur.

That is, the ink jet head according to the invention of the reference or the present invention has a very complicated surface shape such as an ink channel, unlike a usual semiconductor device.
When a liquid resin film is formed on the surface of such a complicated shape, it is impossible to uniformly form the liquid resin film inside the ink channel by a method such as a spin coater. Further, there is also a problem that an excess amount of the material solution for forming the liquid resin film cannot be completely removed in a narrow space such as an ink channel, and the ink channel or the like is clogged.

The present invention has been made to solve the above problems, and even when a liquid resin film is used for a very complicated shape such as an ink channel, the resin film is formed uniformly. An object of the present invention is to provide a method of manufacturing an inkjet head with improved yield and an inkjet head manufactured by this manufacturing method with high structural reliability.

[0012]

The present invention has the following structure as means for solving the above problems.

(1) The method for forming a protective film according to the present invention is characterized by including a step of applying a material solution which becomes a protective film on the surface of a base material and a step of removing an excessive material solution by flowing a gas. I am trying. In particular, the coating type first from the substrate surface side
And the second organic film in this order,
The method is characterized by including a step of applying the substrate by immersing it in a coating type organic material solution and a step of removing excess material solution by flowing gas.

In this structure, since the base material is immersed in the coating type organic material solution, even if the ink flow path has a very complicated shape, the details are uniformly applied, and the material solution is further applied. A gas is flowed through the base material to remove the material solution accumulated in a very complicated shape such as an ink channel.

(2) The method of forming a protective film according to the present invention is characterized in that the coating type organic material solution to be the first organic film contains an amide resin.

With this structure, the adhesion between the first organic film and the polyparaxylylene film, which is the second organic film formed on the surface of the first organic film, is improved.

(3) The protective film forming method of the present invention is characterized in that the second organic film contains polyparaxylylene as a main component.

In this structure, the polyparaxylylene is formed by vapor phase growth at room temperature, and the characteristics of the substrate deteriorated by heat and the substrate having a complicated surface shape are uniformly organic without thermal damage. A film is formed.

(4) In the protective film forming method of the present invention, the surface of the first organic film is formed before forming the first organic film and forming the second organic film on the surface of the first organic film. Is characterized by plasma etching.

In this structure, the surface of the first organic film is etched to form a flat surface, and the polyparaxylylene film to be the second organic film formed on the surface of the first organic film. The adhesiveness with is further improved.

(5) In the protective film forming method of the present invention, a liquid absorbing member is brought into close contact with a part of the base material in the step of removing the excess material solution by flowing gas, and the material is attached to the absorbing member. It is characterized by absorbing the excess of the solution.

In this structure, the surplus of the material solution is removed by flowing the gas, and the surplus of the material solution accumulated on the base material is absorbed.

(6) The protective film forming method of the present invention is characterized in that the liquid absorbing member is brought into close contact with the surface of the base material on the side opposite to the gas inflow side.

With this structure, the excess amount of the material solution is caused to flow toward the liquid-absorbent member, and the material solution is easily absorbed by the liquid-absorbent member.

(7) The ink jet head of the present invention is characterized in that the first organic film and the second organic film are used as protective films.

In this structure, by using the coating type organic material as the first organic film, it is possible to fill the narrow voids of the surface having a very complicated shape such as the ink channel, and the second organic film is uniform. Is formed.

(8) The ink jet head of the present invention is characterized in that the coating type first organic film is also formed on the surface of the ink jet head to which the nozzle plate is joined.

In this structure, the coating type first organic film is formed on the step generated when the base member and the cover member of the ink jet head are joined, and the step is flattened.

(9) A method of manufacturing an ink jet head according to the present invention is characterized by including the method of forming an electrode protective film.

Therefore, the moisture resistance in the ink flow path of the ink jet head is greatly improved.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a schematic diagram of the structure of an inkjet head according to this embodiment. FIG. 2 is a schematic view of a cross section parallel to the ink flow path direction of the inkjet head, and FIG. 3 is a schematic view of a cross section perpendicular to the ink flow path direction.

As shown in FIGS. 1, 2 and 3, an ink jet head (ink jet printer head) 100 is provided.
Is composed of a base member 1, a cover member 2, a nozzle plate 3, an external connection board 4, and a manifold 9. A plurality of grooves 12 are formed in an array on the base member 1, and are separated from each other by the channel walls 11 which are both side surfaces thereof. Both side surfaces of the channel wall 11 (inner side surface of the groove 12) and bottom surface of the groove 12 (upper surface of the groove 12 in FIGS. 2 and 3).
A metal electrode 5 is formed on. The cover member 2 having the ink supply port 21 and the common ink chamber 22 is joined to face the surface of the base member 1 having the groove 12.
A plurality of ink channels 10 are formed inside. A conductive member 8 is formed in a predetermined shape at each end of the plurality of ink channels 10 on the ink supply port 21 side. Further, the external connection substrate 4 having the connection electrodes 41 arranged in accordance with the formation pitch of the ink channels 10 is joined to the end surface of the joining member of the base member 1 and the cover member 2 provided with the ink supply port 21. Has been done. Here, each connection electrode 41 is bonded with an anisotropic conductive adhesive so as to be electrically connected to the conductive member 8 in each ink channel 10.

Further, the first organic film 6 is formed on the entire outer surface of the bonded body composed of the base member 1, the cover member 2 and the external connection substrate 4 corresponding to the base material of the present invention and the inner surface of the ink channel 10. A protective film including the second organic film 7 is formed.

A nozzle plate 3 having nozzle holes 31 arrayed according to the formation pitch of the ink channels 10 is bonded to the end surface of the bonded body on the side opposite to the ink supply ports 21, and the ink channels 10 and the nozzles are connected to each other. The holes 31 are joined so as to be arranged at the corresponding positions.

A manifold 9 for supplying ink to each ink channel 10 so as to sandwich the external connection substrate 4.
The ink jet head 100 is configured by joining the above and the above joined body.

The base member 1 is made of a lead zirconate titanate (PZT) -based ceramic material having ferroelectricity. As shown in FIG. 3, the base member 1 is a plate having a thickness of about 1 mm that is polarized in the direction of the arrow 500. Further, the base member 1 is formed with an array of a plurality of grooves 12 serving as ink channels by cutting by rotating a diamond cutting disk. These grooves 1
2 are parallel and formed at the same depth, the depth is about 300 μm, the width is about 80 μm, and the formation pitch of the grooves 12 is about 160 μm.

Metal electrodes 5 are formed on the side surfaces of the channel wall 11 (inner surfaces of the groove 12) of the base member forming the both side surfaces of the groove 12, the bottom surface of the groove 12 and the upper surface of the channel wall 11. As the metal electrode 5, aluminum (A
1), nickel (Ni), copper (Cu), gold (Au), etc. are used.

Here, the metal electrode 5 formed on the upper surface of the channel wall 11 may be previously lapped before the metal electrode 5 is formed, or may be pasted on the cut surface of the base member 1 before the groove 12 is cut. The attached resist film is removed by removing it after forming the metal electrode 5.

Next, the conductive member 8 is drawn on the base member 1 in a direction perpendicular to the ink flow path direction by using a dispenser (not shown), and is filled in a predetermined position inside the groove 12 by gravity or the like. It A cross-sectional view of the base member 1 at this time is shown in FIG. Then, the conductive member 8 of the base member 1
Is heated by a heating device (not shown) and is solidified by this heat. The conductive member 8 includes gold (Au) paste containing an epoxy resin component, silver (A
g) Paste, copper (Cu) paste, gold (Au) plating based on a plating solution, nickel (Ni) plating, etc. are used. After that, the conductive member 8 remaining on the channel wall 11 is removed by a method such as grinding, and each ink channel 10 is electrically insulated. Also, the groove 12
The metal electrode 5 on one side surface and the metal electrode 5 on the other side surface facing the one side are electrically conducted by the conductive member 8,
An electrical connection circuit is formed for each ink channel.

Next, as shown in FIG. 4 (b), the processed surface of the groove 12 of the base member 1 and the cover member 2 are joined by an adhesive such as an epoxy type adhesive, and as shown in FIG. 4 (c). The cover member 2 and the base member 1 are cut into a predetermined shape. Here, the common ink chamber 22 of the cover member 2 is joined so as to be in a position facing the conductive member 8 formed in the groove 12. As a result, the conductive member 8 is separated for each ink flow path, and as shown in FIG. 1, the ink jet head 1 has a plurality of ink channels 10 arranged at predetermined intervals in a direction perpendicular to the ink flow path. To be done.
Ink is filled in all the ink channels 10 through a space (ink supply port 21) between the conductive member 8 and the cover member 2 when ink is filled.

Next, at the position corresponding to the conductive member 8 formed in each ink channel 10, the connection electrode 4 of the conductive layer is formed.
The external connection board 4 having the structure 1 is bonded to the end surface of the bonding housing including the base member 1 and the cover member 2 on the side having the conductive member 8. Here, the connection electrode 41 and the conductive member 8 are electrically connected by inserting an anisotropic conductive adhesive or a bump (not shown) formed in the connection electrode 41 into the conductive member 8.

Next, as shown in FIG. 4D, an organic material of a coating type is applied to the bonded body composed of the base member 1, the cover member 2 and the external connection substrate 4, and heated by an apparatus (not shown). The first organic film 6 is formed by being cured. Here, for this coating type organic material, an amide-based resin containing N-methyl-2pyrrolidone and butylcellosolve acetate as a solvent component, or an amide-based resin containing N-methyl-2pyrrolidone and cyclohexanone is used. These amide-based resins have good adhesion between the resin and the polyparaxylylene film when a polyparaxylylene film is formed on the surface of these resins as described later. Further, the coating type organic film is applied by being immersed in a solution. Accordingly, even with a member having a complicated surface shape such as the ink channel 10 of the inkjet head 100, the organic insulating film having a uniform thickness can be formed on the wall surface, the bottom surface, or the surface of the conductive member.

Next, gas is introduced into the ink channel 10 from the nozzle side of the ink jet head 100 coated with the first organic film 6. At this time, the liquid absorbing member 50 is brought into close contact with the end surface of the joined body on the conductive member 8 side. As a result, the material solution accumulated in the ink channel 10 can be removed, and the liquid solution can be absorbed by the liquid-absorbent member 50 to form an organic film (first organic film 6) having no step.

In this example, the thickness of the first organic film 6 on the wall surface was formed to be 1 μm after firing. Further, after firing the first organic film 6, the surface of the first organic film 6 was etched by a cylindrical plasma processing apparatus. Here, the etching condition is that the introduced gas is air (atmosphere),
The pressure was 0.3 Torr, and the power applied power density was 0.
It was set to 12 W / cm2 and the application time was set to 5 minutes. Under this condition, the first organic film 6 was etched by about 75 nm.

Next, a second organic film 7 made of polyparaxylylene (hereinafter referred to as "parylene") is formed to a thickness of about 4 μm on the bonded body having the first organic film 6 formed on its surface. . Here, since the parylene film formed by the CVD method can be formed at room temperature without heating the bonded body that is the base material, there is a risk of degrading the polarization characteristics of the piezoelectric member forming the base member 1. There is no. In addition, since the parylene film is in a gas phase at room temperature and has excellent step coverage, it is very useful for ensuring insulation in a member having a complicated surface shape such as the ink channel 10. In the inkjet head 100 according to the present embodiment, the film thickness of the second organic film 7 is 3.5 even in the ink channel 10.
It can be formed to a thickness of μm or more. In addition, since the second organic film 7 is formed after the external connection substrate 4 is connected to the conductive member 8, the joint part by the anisotropic conductive adhesive is also separated from the ink by the parylene film, and the anisotropic conductive film is formed. It is possible to reduce the risk of electric current leaking through the conductive adhesive and improve the reliability of the inkjet head. In this way, as shown in FIGS. 3 and 4E, the second organic film 7 is uniformly formed in the ink channel 10.

Next, as shown in FIG. 4 (f), a plurality of nozzle holes 31 are provided at the end surface of the bonded body where the conductive member 8 is not provided, corresponding to the position of each ink channel 10. The nozzle plate 3 is joined. Then, the manifold 9 is joined to the end surface of the joined body on which the conductive member 8 is provided, with the external connection board 4 sandwiched therebetween. At this time, reliability is improved by sealing the joint with resin so that ink does not leak from the joint.

The ink jet head configured as described above operates as follows. When a voltage is applied to the conductive member 8 via the connection electrode 41, the ink channel 1
A voltage is simultaneously applied to the metal electrodes 5 on both sides of 0. By this voltage, a piezoelectric effect is generated in the channel walls 11 on both side surfaces of the ink channel 10, and the ink is deformed so as to expand toward the inside of the ink channel 10. Since the ink is filled in the ink channel 10 in advance, the volume of the ink channel 10 is reduced by the deformation, and the ink filled in the ink channel 10 is replaced with the nozzle hole 3.
It is ejected from 1 to the outside.

Here, as shown in this embodiment, a step of removing an excess of the organic material solution on the surface of the base material (base member and cover member) by flowing a gas when applying the organic material solution is performed. The results of comparing the occurrence rate of channel clogging with and without is shown.

Samples coated with an organic film by flowing a gas and samples coated with an organic film without flowing a gas were prepared, respectively, and after firing and curing, the ink channels were observed to see if channel clogging occurred. I confirmed. The number of samples under each condition is 200 channels. As a result of this experiment, for the sample formed by flowing gas,
The channel was not clogged, but the sample formed without flowing gas had 60 channels clogged. As described above, by flowing the gas to remove the excess material solution, the channel clogging can be greatly improved.

<Embodiment 1> Table 1 shows the presence or absence of a step on the surface of the base material due to the presence or absence of the liquid absorbing member 50 and the presence or absence of leakage at the joint when the manifold 9 is joined.

[0051]

[Table 1]

In forming the coating type first organic film 6, the bonded body composed of the base member 1, the cover member 2 and the external connection substrate 4 is immersed in the coating type organic material solution. Next, in the step of flowing a gas through the bonded body coated with the first organic film 6 to remove the excess material solution on the surface of the bonded body, a liquid absorbing member is provided on the end surface of the bonded body on the external bonding substrate 4 side. A sample in which the excess material solution is removed by bringing them into close contact with each other and a sample in which the excess material solution is removed without using the liquid absorbing member are prepared. 10 samples were prepared for each experiment, and 1
It was baked and cured under conditions of 20 ° C. and 2 hours.

For each sample, the presence or absence of a level difference on the surface and the occurrence of leakage at the joint portion during manifold joining were examined. As a result, the excess material solution was removed by bringing the liquid-absorbent member of this embodiment into close contact with the gas and flowing the gas. The removed sample had a maximum step difference of 20 μm, and no leak occurred in the manifold. On the other hand, a sample in which a surplus material solution was removed by flowing gas without using a liquid-absorbent member had a maximum step difference of 1
It becomes 00 μm, and the leak at the manifold junction is 3/1.
0 occurred. As described above, by removing the excess material solution while flowing the gas using the liquid-absorbent member, it is possible to suppress the step on the surface of the joined body and prevent the occurrence of leakage at the time of joining the manifolds. .

Example 2 Table 2 shows the occurrence of air bubbles and communication between ink channels during nozzle plate bonding depending on the presence or absence of an organic film on the surface to which the nozzle plate 3 is bonded.

[0055]

[Table 2]

In the step of applying the first coating-type organic film on the surface of the bonded body composed of the base member 1, the cover member 2, and the external connection substrate 4, the first organic layer is also applied to the nozzle plate bonded surface of the bonded body. Ten samples each having a film formed and a sample not having a film formed were prepared, and baked and cured at 120 ° C. for 2 hours. As the evaluation content, a nozzle was joined to the joining surface of the nozzle plate of the joined body, and the bubbles generated in the joined portion and the communication of ink between the ink channels were confirmed.
A resin adhesive was used to bond the nozzle plate.

As a result, in the sample in which the first organic film was formed on the nozzle plate joint surface of this example, no bubbles or communication occurred. On the other hand, in the sample in which the first organic film was not formed on the joint surface of the nozzle plate, bubbles were generated in 7/10 samples, and communication between the ink channels was generated in 5/10 samples. From this, by forming at least the first organic film on the nozzle plate joint surface of the joint body, the steps in the joint surface are flattened, and bubble generation and communication between adjacent ink channels are prevented. be able to.

Example 3 Table 3 shows that the thickness of the second organic film formed on the surface of the first organic film was 4 μm, and the thickness of the coating type organic material solution to be the first organic film was changed. The results of comparing the insulation reliability in the case of

[0059]

[Table 3]

The evaluation method will be described with reference to FIG. FIG. 5 is a diagram illustrating a method of evaluating a protective film according to this example. As shown in FIG. 5, a composite protective film 200 composed of a first organic film and a second organic film is formed on the surface of a 0.5 μm thick copper (Cu) film 301 formed on the surface of a glass substrate 300. There is. Here, a coating type resin containing an amide-based resin was used for the first organic film, and coating on the surface of the Cu film was performed with a spin coater. The control of the film thickness of the first organic film is adjusted by using the rotation speed at the time of application of the spin coater and the viscosity of the coating resin, and the firing condition of the first organic film is 120 ° C. for 2 hours. In this way, samples with different first organic film thicknesses were prepared.

A pair of the samples prepared under the respective conditions was placed in ink 302 having an electric conductivity of 20 mS / m.
The sample is soaked at a distance of mm that it is immersed in the Cu film of the sample by using a wiring such as a flexible substrate, and an AC power source 303.
Was connected, an AC voltage of 90 V and 60 Hz was applied as an effective value, and corrosion of the electrodes was observed.

Sample 1 has a thickness of the first organic film of 0.5.
It was made to be μm, and corrosion was observed at two places by energizing for 24 hours. Sample 2 has a thickness of the first organic film of 1.
The thickness was set to 0 μm, and corrosion was observed at one location after energizing for 125 hours. In Sample 3, the thickness of the first organic film was set to 1.5 μm, and corrosion was observed at one location after energization for 150 hours. In Sample 4, the thickness of the first organic film was 3.0 μm, and no corrosion was observed even after the energization for 424 hours. In the comparative sample, the first organic film was not formed, and only the second organic film made of the parylene film was formed to a thickness of 4 μm. Corrosion was confirmed at four locations by energizing for 24 hours. Here, all these corrosions
This is due to pinholes in the parylene film which is the second organic film.

As the result shows, the insulation reliability is improved by stacking the first organic film and the second organic film. Here, by setting the thickness of the first organic film to 1.0 μm or more, the insulation reliability can be further improved dramatically.

In the above embodiment, the ink jet head using the shearing mode is used, but the present invention does not depend on the method of driving the ink jet head. Therefore, for example, the piezo method or the thermal jet method is used. It can also be applied to an inkjet head and a method for forming a protective film thereof.

[0065]

As described above, the following effects can be obtained by using the present invention.

(1) In the protective film forming method of the present invention, the protective film is formed by forming the coating type first organic film and the second organic film in this order from the substrate side. Since it includes a step of applying by dipping in a coating type organic material solution and a step of removing excess material solution by flowing gas,
Even if the ink channel has a very complicated shape, the organic film can be evenly applied to the details. Furthermore, by flowing a gas through the substrate, it is possible to remove the material solution clogged in a very complicated shape such as an ink channel.
As a result, it is possible to provide a stable inkjet head with a good yield without solidifying an excessive amount of the coating type organic material solution to be the first organic film and blocking the ink channel.

(2) In the method for forming a protective film of the present invention, a coating organic material containing an amide resin is used as the coating organic material to be the first organic film. As a result, the adhesion of the polyparaxylylene film (parylene film) to be the second organic film formed on the surface of the first organic film is improved, and the structural reliability of the inkjet head can be increased.

(3) An environment where the organic film is chemically stable and the organic film is exposed by using polyparaxylylene as a main component in the second organic film in the protective film forming method of the present invention. As a result, it is possible to prevent the organic film from being damaged, and it is possible to stably maintain the insulating characteristics. In addition, since polyparaxylylene is formed by vapor phase growth at room temperature, it does not cause thermal damage to a base material whose properties deteriorate due to heat or a base material with a complicated surface shape, and a uniform insulating film is formed. Can be formed.

(4) In the protective film forming method of the present invention, the first
Of the first organic film surface before the polyparaxylylene film, which contains the amide-based resin in the coating organic material that becomes the organic film of 1), and further forms the polyparaxylylene film that becomes the second organic film on the surface of the first organic film. Is provided with a plasma etching step. By etching the surface of the first organic film in this manner, the surface of the first organic film can be made flat, and the adhesion between the first organic film and the polyparaxylylene film to be the second organic film Performance is further improved, and the structural reliability of the inkjet head is further enhanced.

(5) In the protective film forming method of the present invention, the excess material solution is absorbed by bringing the liquid absorbing member into close contact with part of the base material in the step of removing the excess material solution by flowing gas. By doing so, it is possible to remove the excess material solution, and at the same time, the liquid absorbing member absorbs the accumulation on the surface of the base material to form an organic film with few steps on the surface of the base material. As a result, it is possible to prevent ink leakage from occurring at the manifold joint portion, and it is possible to improve the structural reliability of the inkjet head.

(6) In the ink jet head of the present invention, the second organic film and the polyparaxylylene film are used as the second organic film.
By forming the protective film from the organic film of
The coating-type organic material serving as the organic film can fill a narrow void having a very complicated shape such as an ink channel including an ink channel, and can uniformly form the second organic film. As a result, it is possible to provide a highly reliable inkjet head that has significantly improved moisture resistance and is free from corrosion.

(7) In the ink jet head of the present invention, the surface of the ink jet head on which the nozzle plate is joined is
By forming the first organic film and the second organic film, it is possible to flatten the step generated when the base member and the cover member of the inkjet head are joined, and it is possible to form air bubbles at the nozzle plate joining portion. It is possible to suppress the occurrence of ink and to prevent communication between ink channels.

(8) Since the method for manufacturing an ink jet head of the present invention includes the method for forming a protective film, the moisture resistance in the ink channel of the ink jet head can be greatly improved. This makes it possible to prevent the occurrence of corrosion without significantly increasing the manufacturing cost.

[Brief description of drawings]

FIG. 1 is an external perspective view illustrating the outline of the structure of an inkjet head of the present invention.

FIG. 2 is a schematic diagram of a cross section parallel to the ink flow path direction of the inkjet head.

FIG. 3 is a schematic view of a cross section perpendicular to the ink flow path direction of the inkjet head.

FIG. 4 is a schematic diagram illustrating a manufacturing process of an inkjet head.

FIG. 5 is a diagram illustrating a method for evaluating a protective film according to the present invention.

FIG. 6 is an exploded perspective view illustrating the outline of the structure of a conventional inkjet head.

[Explanation of symbols]

100-inkjet head (inkjet printer head) 1-base member 2-cover member 3-nozzle plate 4-external connection substrate 5-metal electrode 6-first organic film 7-second organic film 8-conductive member 9 -Manifold 10-Ink channel 11-Channel wall 12-Groove 21-Ink supply port 22-Common ink chamber 31-Nozzle hole 41-Connecting electrode 50-Liquid absorbing member 200-Composite protective film 300-Glass substrate 301-Cu film 302-ink 303-AC power supply

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B41J 2/16

Claims (10)

[Claims] 1. A method of forming a coating type protective film on a surface of a base material, the step of applying a material solution to be the protective film on the base material, and removing excess material solution by flowing a gas. The method of forming a protective film, comprising: 2. The protective film is a first organic film applied on the surface of the base material, and a second organic film applied on the surface of the first organic film.
And a step of applying the material solution by immersing the base material in a material solution that forms the first organic film, and a step of applying the material solution that forms the first organic film. 2. The method for forming a protective film according to claim 1, further comprising the step of removing excess portion of the above by flowing gas. 3. The method for forming a protective film according to claim 2, wherein the material solution forming the first organic film contains an amide resin. 4. The protective film forming method according to claim 2, wherein the second organic film contains polyparaxylylene as a main component. 5. A step of performing plasma etching on the surface of the first organic film after forming the first organic film and before forming the second organic film. The method for forming a protective film according to any one of 2 to 4. 6. In the step of removing the excess amount of the material solution with a gas, a liquid absorbing member is brought into close contact with a part of the base material so that the liquid absorbing member absorbs the excess amount of the material solution. The method for forming a protective film according to any one of claims 1 to 5, wherein: 7. The protective film according to claim 6, wherein the liquid-absorbent member is brought into close contact with the surface of the base material on the side opposite to the inflow side of the gas for removing the excess amount of the material solution. Forming method. 8. An ink channel composed of a groove having a wall of a piezoelectric material, a drive electrode for applying a voltage to the piezoelectric element to change the pressure of the ink channel, and the drive electrode contained in the ink. An ink jet head having an insulating film that prevents contact with an electrolyte solution according to claim 1, wherein the insulating film includes a protective film formed by using the protective film forming method according to any one of claims 1 to 7. And inkjet head. 9. The inkjet head according to claim 8, wherein at least the first organic film is formed on a surface of the inkjet head on which the nozzle is provided. 10. A method of manufacturing an inkjet head according to claim 8 or 9, comprising the method of forming a protective film according to any one of claims 1 to 7. .