JP2006212912A - Protective film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a protective film with a uniform thickness on the inner face of a narrow channel of a liquid droplets delivering head used for inkjet recording. <P>SOLUTION: The protective film forming method is provided to form the protective film on the inner face of a tunnel-like channel with an opening part formed in a head chip used for the liquid droplets discharging head in a film manufacturing chamber equipped with a film-manufacturing gas introducing means equipped with a nozzle with a gas jetting opening. The protective film forming method comprises a process for depressurizing the film manufacturing chamber, a process for inserting the gas jetting opening into the inside of the channel, and a process for jetting a film-manufacturing gas from the gas jetting opening, introducing the film-manufacturing gas into the inside of the channel, and forming the protective film on the inner face of the channel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a protective film, and more particularly to a method for forming a protective film on the inner surface of a channel of a head chip used in a droplet discharge head.

  In recent years, methods for recording an image or forming a fine pattern or structure by ejecting fine droplets such as an ink jet head for an ink jet printer have been well known. A typical example of such a droplet discharge head is one that discharges a droplet by utilizing deformation of a piezoelectric ceramic material by voltage, and one that generates bubbles in the liquid by heating to cause volume expansion. Thus, it is known that liquid droplets are discharged. As an example of this type of element, a fine groove having a groove depth of about 0.5 mm, a groove width, and a wall thickness between grooves of 0.18 mm is formed on a substrate made of a ceramic material and having a thickness of about 1 to 2 mm. Some have a structure in which a large number of fine tunnel-like spaces are formed by joining a cover material on the side where the grooves are formed. The liquid to be discharged is held in this tunnel-shaped space, and the liquid is discharged by the method described above. Such a space is called a channel in the following description.

  In order to obtain a function of discharging a liquid based on an electric signal, an electrode made of a metal material is often formed on the inner surface of the channel. In the case of discharging liquid by generating bubbles by heating, a heater as a heating means is often formed inside the channel as a metal, ceramic, or a composite thereof. Accordingly, the inner surface of the channel of the droplet discharge head is usually formed of a metal material, a ceramic material, or a composite material thereof.

  On the other hand, various types of discharged liquids are used. Oily liquids such as oil-based inks are generally less corrosive to metals and ceramics, but water-soluble liquids such as water-based inks are applied to metals and ceramics. On the other hand, it may be corrosive. In particular, when a voltage is applied to the electrode, corrosion is accelerated by an electrochemical reaction. Depending on the purpose of droplet ejection, a highly corrosive liquid may be used.

  In order to prevent the corrosion of the ceramic material and the metal material caused by such a cause and to improve the durability of the droplet discharge head, a protective film is formed on the inner surface of the channel. As a material for such a protective film, polyparaxylylene, which is a polymer of paraxylene, or a derivative thereof is well known, and is generally protected on the inner surface of the channel by chemical vapor deposition (hereinafter referred to as CVD). A film is formed. In addition, various devices have been made to improve the performance and durability of the polyparaxylylene protective film (see, for example, Patent Document 1 and Patent Document 2).

  Patent Document 1 discloses a method for improving the protective performance by improving the adhesion and heat resistance of a protective film by using a combination of multiple types of polyparaxylylene having different properties and derivatives thereof.

Patent Document 2 discloses a method for improving the adhesion and durability of a protective film to be formed by incorporating a silane coupling agent into polyparaxylylene.
JP 2000-71451 A Japanese Patent Laid-Open No. 2003-19797

  The methods disclosed in Patent Documents 1 and 2 are intended to improve the performance as a protective film mainly focusing on the adhesion of the polyparaxylylene film and the properties of the film itself. It is an effective method for improvement. However, when a polyparaxylylene film is formed on the inner surface of the channel of the droplet discharge head, there are the following technical problems.

For example, in the case of an ink jet head which is a typical example of a droplet discharge head, the channel usually has a very small cross-sectional shape, and the cross-sectional area may be 0.1 mm ² or less and the length may be about 10 mm. It is a very narrow space. In addition, when manufacturing an inkjet head, the protective film is formed by forming a groove in order to sufficiently bond the substrate having the groove for forming the channel and the cover material bonded to the substrate. It is desirable to perform the process after bonding the cover material to the substrate thus formed, and therefore it is required to form a film in the tunnel-like space. In addition, the channel does not necessarily have openings at both ends, and one end may be closed and only the other end may have an opening.

  When a protective film is formed on the inner surface of such a long and narrow channel by CVD, the film-forming gas is easily distributed near the opening of the channel or a film having a required thickness is easily formed, but the film is separated from the opening. The film-forming gas does not sufficiently reach the back part of the channel, and the thickness of the film tends to be thinner than the vicinity of the opening. When it is difficult to form a protective film with a uniform thickness, in order to obtain the required film thickness in the part where the film thickness tends to be thin, it is more than necessary near the opening of the channel. This narrows the channel space. If film formation is continued until the film thickness of the protective film reaches 1 μm or more at the center of the channel, the film thickness often exceeds 10 μm near the opening of the channel.

  If the film thickness is thin, pinholes and cracks existing in the film tend to penetrate the film, and the performance as a protective film may not be sufficient. Corrosion begins when ink comes into contact with the ceramic or electrode at the pinholes or cracks, and the corrosion expands, leading to a decrease in the durability of the inkjet head. On the other hand, if the film thickness is too thick, adhesion to the substrate and durability may be reduced.

  In general, the thickness of the protective film made of polyparaxylylene is desirably 1 μm or more and 8 μm or less. By forming the thickness of the protective film in this range, the performance as the protective film is exhibited and the adhesion and durability of the film are maintained, while the protective film is prevented from narrowing the channel.

  The present invention has been made in view of the above circumstances, and the object thereof is to form a portion of a tunnel-like channel having a small opening area with respect to the length, such as a channel of an inkjet head, from the opening. A protective film with a uniform thickness is formed on the distant part to prevent the part where the film thickness is insufficient, and conversely, the part where the film thickness is excessively thick. It is to provide a protective film forming method that realizes a protective film having a necessary and sufficient thickness.

  The above object can be achieved by the following method and configuration.

(Claim 1)
A film-forming chamber provided with a film-forming gas introducing means having a nozzle having a gas outlet, and a protective film is formed on the inner surface of a tunnel-like channel having an opening formed in a head chip used for a droplet discharge head In the protective film forming method to be formed,
Depressurizing the film forming chamber;
Inserting the gas outlet from the opening into the channel;
Forming a protective film on the inner surface of the channel by blowing a film-forming gas from the gas outlet under reduced pressure, introducing the film-forming gas into the channel, and
A method for forming a protective film, comprising:

(Claim 2)
A film-forming chamber provided with a film-forming gas introducing means having a nozzle having a gas outlet, and a protective film is formed on the inner surface of a tunnel-like channel having an opening formed in a head chip used for a droplet discharge head In the protective film forming method to be formed,
Depressurizing the film forming chamber;
Under reduced pressure, the gas ejection port is relatively moved from the outside of the opening to the inside of the channel, and the deposition gas is ejected from the gas ejection port to introduce the deposition gas into the channel. And forming a protective film on the inner surface of the channel;
A method for forming a protective film, comprising:

(Claim 3)
A film-forming chamber provided with a film-forming gas introducing means having a nozzle having a gas outlet, and a protective film is formed on the inner surface of a tunnel-like channel having an opening formed in a head chip used for a droplet discharge head In the protective film forming method to be formed,
Depressurizing the film forming chamber;
Bringing the gas outlet close to the opening;
Forming a protective film on the inner surface of the channel by injecting the film-forming gas directly from the gas outlet toward the opening under reduced pressure, introducing the film-forming gas into the channel, and
A method for forming a protective film, comprising:

(Claim 4)
The inner surface of the channel is at least partly formed as an electrode,
The method for forming a protective film according to claim 1, wherein a film forming gas is introduced in a state where the electrode is cooled to form a protective film on the inner surface of the channel.

  In the present invention, the head chip is a step of manufacturing a droplet discharge head as described above, and a droplet discharge is performed in a state where a cover material is bonded to a substrate having a groove to form a tunnel-like space. It refers to a member that has been cut or shaped to the dimensions used as a head.

  In the present invention, the tunnel-like channel means a channel whose cross section is a closed curve, and excludes a so-called U-shaped or V-shaped groove such as a groove whose cross section does not become a closed curve. The channel does not necessarily have openings at both ends, and may have a structure in which one end is closed.

  According to the first aspect of the present invention, the film-forming gas is ejected in a state where the gas outlet is inserted into the channel, so that all the film-forming gas is once introduced into the channel before being finally discharged. As a result, a protective film having a sufficient thickness is formed in the back part of the channel in the same manner as in the vicinity of the opening, and the film thickness is improved. The effect is further enhanced by oscillating the position of the gas outlet relative to the channel inside the channel.

  According to the invention of claim 2, the film-forming gas is efficiently introduced into the inside of the channel by ejecting the film-forming gas while relatively moving the gas ejection port from the inside of the channel to the outside of the opening of the channel. On the other hand, since the film-forming gas ejected from the outside of the opening is directly sprayed on the inner surface in the vicinity of the opening of the channel, the film thickness uniformity between the deep part of the channel and the vicinity of the opening is Further improve.

  According to the third aspect of the present invention, the film-forming gas is efficiently introduced into the channel by ejecting the film-forming gas directly from the vicinity of the outside of the opening of the channel toward the inside of the channel. A film-forming gas also travels to the inner part of the film, and a protective film having a sufficient thickness is formed as in the vicinity of the opening of the channel. The gas outlet may be disposed with a gap with respect to the opening of the channel, or may be in close contact with the opening of the channel if possible, and both are within the scope of claim 3.

  According to the invention of claim 4, when at least a part of the inner surface of the channel is formed as an electrode, the film-forming gas is ejected to the cooled electrode portion by ejecting the film-forming gas with the electrode cooled. A protective film having a sufficient thickness is formed on the inner surface of the channel on the electrode portion where the importance of the protective film is particularly high.

  Hereinafter, although an embodiment of the present invention is described based on a drawing, the present invention is not limited to this embodiment. This embodiment is an example of a method using a CVD film forming apparatus conventionally known as a film forming apparatus in order to form a protective film on the inner surface of a channel of an ink jet head which is a typical example of a droplet discharge head. First, devices and components used, and functions and operations thereof will be described with reference to FIGS.

  FIG. 1 is an external view showing a CVD film forming apparatus 1 for carrying out a method for forming a protective film according to the present invention. In the vaporization chamber 2, paraxylylene, which is a raw material for the film-forming gas, is converted into diparaxylylene, which is a dimer, by thermal decomposition and rapid cooling. The monomer is introduced into the film forming chamber 4 by the film forming gas introducing means 5 as a film forming gas. The monomer adheres to the film formation body in the film forming chamber 4 and forms a protective film of polyparaxylylene having a molecular weight of several hundreds of thousands by a polymerization reaction.

  In the detoxification cooling device 6, the film forming gas remaining in the film forming process and its decomposition product are cooled, and the harmful decomposition product is adsorbed by an adsorbent to prevent discharge to the outside. The exhaust device 7 has a role of evacuating the air in the film forming apparatus 1 including the film forming chamber 4 to reduce the film forming chamber 4 to a substantially vacuum before the film forming process, and among the generated film forming gas, The gas remaining without contributing to film formation is exhausted, and the inside of the film formation chamber 4 is maintained at a gas pressure suitable for film formation during the film formation process.

  In addition to the above-described components, the CVD film forming apparatus 1 is provided with a flow rate adjusting valve (not shown) for adjusting the gas pressure in the film forming chamber 4 by adjusting pipes connecting the respective components and adjusting the gas flow rate. ing.

  After exhausting the air in the film forming apparatus 1 sufficiently by the exhaust apparatus 7 to 4000 Pa or less, generation of the film forming gas is started as described above, the generation speed, the exhaust speed of the exhaust apparatus 7 and the above-mentioned The gas pressure in the film forming chamber 4 can be adjusted by adjusting the flow rate adjusting valve. That is, the partial pressure of the film forming gas in the film forming chamber 4 is approximately equal to the amount of the film forming gas introduced by the film forming gas introduction means 5 and the amount of the film forming gas exhausted by the exhaust device 7. The flow rate adjustment valve is adjusted so as to be maintained at 4000 Pa, and a protective film is formed in that state.

  FIG. 2 is a schematic view of the inside of the film forming chamber 4 of the CVD film forming apparatus 1 as viewed from the horizontal direction. In FIG. 2, the same components as those in FIG. In addition, as described above, the dimensions of the head chip and the channel are extremely small. In FIG. 2, the dimensional ratio of each component in the drawing is drawn differently from the actual dimensional ratio for easy understanding. There is a case.

  In a normal protective film forming method, the film forming gas introducing means provides a relatively large opening in the film forming chamber so as to disperse the film forming gas over a wide range so that the film forming gas is distributed throughout the film forming chamber. The shape is suitable for. However, the film forming gas introducing means 5 used in the protective film forming method of the present invention has the following configuration in order to efficiently introduce the film forming gas into the channel of the head chip of the inkjet head.

  That is, it has the piping part 51 from the pyrolysis chamber 3 to the inside of the film forming chamber 4, the connecting pipe 52 connected to the piping part 51 and having flexibility, and the extending part 53 connected to the connecting pipe 52. The external dimensions in the vicinity of the distal end portion of the extending portion 53 are formed small, and a nozzle having a gas ejection port is detachably provided. The nozzle will be described later with reference to FIGS. 3 to 5.

  The extending portion 53 is held by the second holding means 13 and is held movably by the flexibility of the connection pipe 52.

  A first holding means 12 is provided in the film forming chamber 4 and movably holds the head chip 11 as a film forming body via a pedestal 19. The gantry 14 mounts and fixes the first holding means 12 and the second holding means 13.

  When an electrode is formed on the inner surface of the channel of the head chip 11 and the protective film is formed while cooling the electrode, it is necessary to provide a cooling means, but the illustration is omitted in FIG. 6 will be described.

  Next, the nozzle provided in the vicinity of the distal end portion of the extending portion 53 will be described with reference to FIGS. 3 to 5. 3 is formed at the tip of each of the nozzle holding tube 54 attached to the side wall near the tip of the extending portion 53 shown in FIG. 2, the four nozzles 55 fixed to the nozzle holding tube 54, and the four nozzles 55. A gas outlet 56 is shown. 3A is a cross-sectional view of a plane including the central axis of the four nozzles 55, and FIG. 3B is a diagram viewed from the direction in which the gas of the nozzle 55 is ejected. The nozzle holding cylinder 54 is preferably detachable from the extending portion 53 so that it can be replaced when the nozzle is damaged or a different type of nozzle can be used. The number of nozzles 55 is not limited to four, and at least one nozzle may be provided. However, when a plurality of nozzles 55 are provided, the time required for forming a protective film is reduced by ejecting a film-forming gas to a large number of channels simultaneously. This is preferable. The number of nozzles is preferably a number that can be divided by the number of channels on which the protective film is formed. Further, the interval between the plurality of nozzles is made to coincide with the channel interval of the head chip 11 or an integral multiple thereof.

  The nozzle 55 shown in FIG. 3A is a stainless steel having an outer diameter of 0.1 mm and an inner diameter of 0.04 mm in order to allow the gas outlet 56 to be inserted into the channel of the head chip 11 described later. It was manufactured with a thin tube. In the case where the film forming gas is ejected from the vicinity of the opening without inserting the gas ejection port 56 into the channel, a nozzle 55 having a large outer dimension and increased mechanical strength may be used. . FIG. 4 shows an example of such a nozzle, and FIG. 4A shows a nozzle made of a stainless steel thin tube having an outer diameter of 0.3 mm and an inner diameter of 0.1 mm. Further, in order to further increase the mechanical strength, it is also possible to use a gas jet outlet formed on an integral member as shown in FIG.

  In the nozzle shown in FIG. 3, the gas ejection port 56 ejects the film-forming gas substantially parallel to the length direction of the nozzle 55, but the film-forming gas ejection direction has an angle with respect to the length direction of the nozzle 55. Anyway. An example is shown in FIG. FIG. 5A is a view of such a nozzle as viewed from the direction in which a plurality of nozzles overlap, and FIG. 5B is an enlarged view of the tip portion of the nozzle 55 surrounded by a dashed line in FIG. It is. By forming the gas ejection port 56 in such a shape that the gas is ejected obliquely in the up-down direction, the film-forming gas easily spreads in the height direction of the channel 15, and even when the height of the channel 15 is relatively large, the protective film The film thickness tends to be uniform.

  Next, the first holding means 12 and the second holding means 13 will be described with reference to FIG. FIG. 6 shows a first holding means 12 composed of a plurality of components 12-1 to 12-5, a pedestal 19 mounted thereon, a Peltier element 20 as a cooling element, and a head chip 11. In FIG. 6, the dimensional ratio of each component and the vertical / horizontal dimensional ratio are depicted differently from the actual dimensional ratio for easy understanding.

  The first holding means 12 shown in FIG. 6 uses the head chip 11 as a mechanism that can move in three directions, the horizontal (X and Y) direction and the vertical (Z) direction, and rotates about a rotation axis parallel to the Z axis. It has a possible structure.

  The holding substrate 12-1 is fixed on the gantry 14 of FIG. 2, and the entire movable part of the first holding means 12 is mounted thereon. The vertical movement member 12-2 is a member movable in the vertical direction (Z direction) with respect to the holding substrate 12-1, and the X direction movable member 12-3 is a member movable in the horizontal direction (X) indicated by an arrow. The Y-direction movable member 12-4 is movable in a direction perpendicular to the paper surface of this drawing. The rotating member 12-5 is rotatable about a straight line parallel to the Z direction indicated by reference numeral C, and the head chip 11 is fixed thereon via a pedestal 19 and a Peltier element 20. The pedestal 19 was provided to increase the height from the upper surface of the rotating member 12-5 so that a gas outlet 56 at the tip of the nozzle 55 described later can be brought close to the head chip 11. The Peltier element 20 is provided for cooling the electrode 16. Although it is preferable to use a Peltier element that has no mechanical movable part and can be cooled only by energization, it is not limited to this, and a small refrigerator or the like can also be used. Although wiring, a power supply device, and a control device and sensor for controlling temperature and current for energizing the Peltier element 20 are also necessary, illustration is omitted. The method for cooling the electrode 16 will be described in detail in the description of the fourth embodiment to be described later.

  In addition, in order to make it easy to understand the movable mechanism of the first holding means 12, only the member that moves itself with respect to the movement such as up and down, horizontal, and rotation is shown in FIG. 6, but the first holding means 12 is , A drive mechanism (not shown) for moving them, a motor, a sensor for maintaining the accuracy of movement, and the like are provided. A driving circuit for driving the motor and a control circuit for controlling the driving circuit are also provided inside or outside the film forming chamber 5, but illustration thereof is omitted. The same applies to the second holding means described later. Also, the means for fixing the head chip 11 and the pedestal 19 and the means for fixing the pedestal 19 to the rotating member 12-5 are not shown.

  The second holding means 13 shown in FIG. 2 has a structure excluding the movable mechanism in the rotational direction of the first holding means 12 shown in FIG. The mechanism is movable in the movable range obtained by the flexibility of the connecting pipe 52 in the direction (X and Y) and the vertical direction (Z).

  The movable mechanisms of the first and second holding means 12 and 13 are not limited to those described above, and any movable mechanism can be used as long as the relative position of the head chip 11 and the nozzle 51 can be varied within a necessary range. These movable directions may be appropriately shared by the first and second holding means 12 and 13. Further, in order to facilitate the adjustment of the relative position of the head chip 11 and the nozzle 51, the head chip 11 and the second holding means 12, 13 may be provided redundantly. One may be a structure in which only one is held fixed and the other holding means bears all the movable functions.

Next, the head chip 11 will be described with reference to FIG. The head chip 11 shown in FIG. 7 is a head chip used for an ink jet head that discharges droplets by utilizing shear mode deformation of a piezoelectric ceramic, and its structure is well known and will be described briefly.

  A thick plate 17-a and a thin plate 17-b of lead zirconate titanate (generally called PZT, hereinafter referred to as PZT) well known as a piezoelectric ceramic as the substrate 17 are bonded with an adhesive layer (not shown). The combined material is used as the substrate 17, and the cover material 18 is also made of PZT in order to match the thermal and mechanical characteristics. The polarization direction indicated by the symbol A of the thick plate 17-a and the polarization direction indicated by the symbol B of the thin plate 17-b are the thickness direction of the plate and are opposite to each other. The cover material 18 is not polarized. The thickness of the thin plate 17-b is approximately half of the depth of a groove to be described later. The reason why the substrate 17 has such a structure is to cause shear mode deformation efficiently, and since it is well known in this field, detailed description thereof is omitted.

  In FIG. 7, a groove for forming the channel 15 is formed on the substrate 17 by a method such as grooving with a precision dicing saw, but the method of forming the groove is not limited to this. The electrode 16 is formed by vapor deposition of aluminum after forming the groove. However, the electrode formation method is not limited to vapor deposition, and the electrode 16 may be formed by, for example, nickel electroless plating.

  In some inkjet heads, every other channel is used, and the channel between them is called an air channel and does not contain liquid. In general, it is not necessary to form a protective film on the air channel. In this case, the interval between the plurality of nozzles is preferably twice or an integral multiple of the interval between the channels 15 of the head chip 11. A head chip 11 shown in FIG. 7 is a head chip for an ink jet head of a type having no air channel.

  The head chip 11 has 80 channels 15 each having a channel width and a wall thickness between the channels of 0.18 mm (that is, a channel interval of 0.36 mm), a height of 0.5 mm, and a length of 5 mm. However, only a part thereof is shown in the figure. Of the 80 channels 15, 72 channels 15 excluding 4 on both sides are used for droplet ejection. Out of the four on each side, three on the outside are used as a space for releasing excess adhesive when bonding is performed for bonding. Each of the inner channels has a structure in which the channels 15 at both ends of the 72 channels 15 used for ejecting droplets are sandwiched between 0.18 mm thick walls in the same manner as the other channels 15, and the outside of the walls. This is a space necessary for forming the electrode 16. It is necessary to form a protective film for the central 72 channels used for droplet ejection.

  As shown in FIG. 7, the electrode 16 of the head chip 11 according to the present embodiment is on the surface having both the side surface and the bottom surface portion indicated by 16-a and the opening portion indicated by 16-b among the inner surface of the channel 15. No electrode is formed on the surface formed by the cover material 18 and the portion formed on the bottom surface of the substrate 17a indicated by 16-c. Normally, the portion indicated by 16-c is electrically connected to the drive circuit by a method such as wire bonding.

  The protective film 21 is formed on the inner surface of the channel 15, and protects the surface formed by the electrode 16-a and the cover material 18 on the upper portion of the channel 15.

  At the stage completed as a droplet discharge head, a minute discharge port (not shown) through which droplets are discharged is provided at one end of the channel 15. Usually, a thin plate called a nozzle plate formed with a large number of minute holes serving as ejection ports is joined to the end face of the head chip 11 or a minute hole is formed after joining the thin plate, thereby ejecting the ejection port of the droplet ejection head. Is provided. The size of the discharge port is usually sufficiently smaller than the cross section of the channel 15.

(First embodiment)
A first embodiment according to claim 1 of the present invention will be described below with reference to FIG. The first embodiment is a method of forming a protective film 21 by inserting a gas outlet into the channel 15 of the head chip 11 and ejecting a film forming gas. Using the nozzle 55 having the shape shown in FIG. 3A, the gas ejection port 56 is positioned inside the channel 15 of the head chip 11 shown in FIG.

  In order to insert the gas outlet 56 into the channel 15, first, the nozzle 55 is rotated by rotating the rotating member 12-5 in the length direction of the channel 15 of the head chip 11 held by the first holding means 12. It is made to almost coincide with the length direction. Next, the extending part 53 of the film forming gas introducing unit 5 is moved by the second holding unit 13, and the position of the gas ejection port 56 of the nozzle 55 is positioned within the movable range of the head chip 11.

  Subsequently, as described in the description of FIG. 1, after the air in the film forming apparatus 1 is sufficiently exhausted by the exhaust apparatus 7 to be equal to or lower than 4000 Pa, the production of the film forming gas is started, and the flow rate adjusting valve is started. Is adjusted to maintain the partial pressure of the deposition gas in the deposition chamber 4 at about 4000 Pa. At this stage, the film forming gas is released into the entire space inside the film forming chamber 4.

  Next, the opening of the channel 15 is brought close to the four gas ejection ports 56. Of the 72 channels 15 that need to be formed with a protective film, it is preferable that the openings of the four channels 15 positioned at the end are first brought close to each other. Subsequently, the head chip 11 is moved in the length direction of the channel 15 by using at least one of the movable mechanisms of the first holding means 12 of the X-direction movable member 12-3 and the Y-direction movable member 12-4, so that 4 Each gas outlet 56 is inserted into each of the four channels 15. Obviously, if either the X direction or the Y direction of the first holding means 12 is substantially aligned with the length direction of the nozzle 55, only one of the X direction and the Y direction can be moved. Since it can be inserted by movement by a mechanism, control for movement is easy and accuracy is easily improved. The same applies to the case of periodically changing the position of a gas outlet 56 described later.

  FIG. 8 shows a state in which the gas ejection port 56 is inserted into the channel 15, and the film-forming gas is continuously ejected in the state of FIG. After a predetermined time has elapsed, the head chip 11 is moved in the direction opposite to the moving direction to bring the gas outlet 56 out of the channel 15, and a protective film is formed similarly on the four adjacent channels 15. I do. By sequentially repeating the above steps for a plurality of channels 15, the protective film 21 can be formed on all the channels 15.

  The position of the gas outlet 56 inside the channel 15 and the time during which it is inserted into the channel 15 vary depending on the dimensions and shape of the channel 15 and the nozzle 55, but are determined experimentally by obtaining appropriate values.

  When the position of the gas ejection port 56 is located at a distance of about a quarter of the length of the channel from the opening on the nozzle 55 insertion side, the film thickness is maximized at the substantially central portion in the channel length direction. 55 near the opening on the insertion side had a minimum film thickness, and when the film thickness reached about 7 μm at the center, the film thickness was about 3 μm near the opening.

  By swinging the head chip 11 in the length direction of the channel 15 while continuing the film-forming gas ejection, the relative position of the gas ejection port 56 inside the channel 15 changes periodically, thereby further The uniformity of the film thickness can be improved.

(Second Embodiment)
Next, a second embodiment according to claim 2 of the present invention will be described with reference to FIG. In the second embodiment, the nozzle 55 and the head chip 11 having the same shape as in the first embodiment are used. However, the relative position of the head chip 11 with respect to the channel 15 of the gas ejection port 56 is outside the opening of the channel 15. Then, the head chip 11 is swung so as to periodically change over the inside of the channel 15.

  That is, for the opening of the channel 15 on the side where the nozzle 55 is inserted, the film-forming gas is directly jetted when the gas outlet 56 is located in the vicinity of the outside of the opening of the channel 15. For the interior of the channel 15 and the vicinity of the opening on the opposite side, when the gas ejection port 56 enters the interior of the channel 15, most of the ejected film-forming gas is inside the channel 15. Through this, the film is released from the opening on the opposite side to the outside of the channel 15, so that the film-forming gas reaches the entire inside of the channel 15 and tends to have a uniform thickness.

  The nozzle 55 is inserted when the position of the gas ejection port 56 is swung between about 0.5 mm from the outside of the opening on the side where the nozzle 55 is inserted and the substantially central position inside the channel 15. The vicinity of the opening on the side had the maximum film thickness, and the opening on the opposite side had the minimum film thickness. When the film thickness reached about 7 μm in the former, the film thickness was about 4 μm in the latter.

(Third embodiment)
Next, a third embodiment according to claim 3 of the present invention will be described with reference to FIG. The third embodiment is a method in which the gas ejection port 56 is positioned outside the channel 15 and a film forming gas is ejected to form a protective film. In FIG. 9, the nozzle 55 having a shape as shown in FIG. 4A is used, and the head chip 11 having the same shape as that shown in FIG. 7 as in the first and second embodiments is used. It is also possible to use an integral member in which a gas ejection port is formed as shown in FIG.

  The length direction of the nozzle 55 is made substantially parallel to the length direction of the channel 15, and the position of the gas outlet 56 is made close to the opening of the channel 15 outside the channel 15. Even if the film-forming gas is ejected from the outside of the channel by making it as close as possible, the ratio of the ejected gas that is exhausted from the film-forming chamber 4 without entering the channel 15 can be reduced.

When the nozzle 55 has the shape shown in FIGS. 4A and 4B, there is an advantage that it is mechanically stronger than the shape shown in FIG. Further, by bringing the tip of the nozzle formed with the gas ejection port into close contact with the opening of the channel 15, almost all of the ejected film forming gas can be introduced into the channel 15. Is less likely to be damaged. In addition, the time required for forming the protective film can be shortened by not inserting the gas ejection port inside the channel 15. Although the use of the nozzle 55 having the shape shown in FIGS. 4A and 4B has the advantages as described above, the nozzle 55 having the shape shown in FIG. It is also possible to eject the film-forming gas from the outside of 15 and is within the scope of the present invention.
When the protective film is formed by using the nozzle 55 having the shape shown in FIG. 4 (a) and forming the protective film with the gas ejection port substantially in close contact with the opening of the channel 15, the vicinity of the opening close to the nozzle 55 is the maximum film thickness. The opening on the opposite side tends to have a minimum film thickness. When the film thickness was 7 μm in the former, the film thickness was about 3 μm in the latter.

(Fourth embodiment)
A fourth embodiment according to claim 4 of the present invention will be described with reference to FIG. The fourth embodiment is a method of forming the protective film 21 in the protective film forming method described in the first embodiment by cooling the electrode 16 of the head chip 11 to increase the efficiency of deposition of the film forming gas. This utilizes the fact that in the CVD film forming apparatus, the film forming gas adheres to the film forming body and the film forming gas has a high efficiency when the temperature of the film forming body is low.

  FIG. 10A is a perspective view showing a state in which the electrode 16 of the head chip 11 is extended to the outside of the channel 15 as described in the explanation of FIG. The same components as those in FIG. 7 are given the same numbers. The portion 16-a inside the channel 15 of the electrode 16 is cooled by heat conduction through the portion 16-b by cooling the bottom portion 16-c of the substrate 17. As shown in FIG. 10B, cooling is performed by providing a Peltier element 20 between the head chip 11 and the base 19. The Peltier element is well known and will be described briefly. As shown in FIG. 10C, the positive electrode 20-1, the N-type semiconductor 20-2, a heat absorbing plate 20-3 made of a metal material, P When the type semiconductor 20-4 and the negative electrode 20-5 are connected in this order and are energized in the direction indicated by the symbol I, the temperature of the heat absorbing plate 20-3 decreases, and the positive electrode 20-1 and the negative electrode 20-5 Temperature rises. The positive electrode 20-1 and the negative electrode 20-5 are in close contact with the pedestal 19, and the pedestal 19 is in close contact with the rotating member 12-5, whereby the rotating member 12-5 becomes a heat sink, and the positive electrode 20-1 and the negative electrode 20-5. The heat is dissipated toward the rotating member 12-5, and the temperature rise of the base 19 can be suppressed. The substrate 17 side of the head chip 11 is placed on the heat absorbing plate 20-3 so as to be in contact with the heat absorbing plate 20-3 of the Peltier element 20.

  The electrode 16 is formed of a metal material and usually includes a material having a particularly high thermal conductivity among metal materials such as aluminum, copper or gold. In the head chip 11 shown in FIG. 7, the electrode 16 is formed of aluminum. ing. The thermal conductivity of aluminum is about 240 W / (m · K), the thermal conductivity of PZT is about 2 W / (m · K), and there is a difference of about two digits. As described above, since the thermal conductivity is greatly different, when the portion of the electrode 16-c is cooled, the temperature of the portion of the electrode 16-a on the inner surface of the channel 15 becomes lower than the temperature of the portion without the electrode. . In FIG. 10C, the channel 15 and the electrode 16 are drawn larger than the actual size ratio for easy understanding. As the Peltier element 20, FPH1-12702 Peltier module (30 mm × 30 mm × 4.8 mm (thickness)) manufactured by Fujitaka Co., Ltd. can be used.

  By forming the protective film 21 in a state where the electrode 16 is cooled in this way, the polyparaxylylene protective film 21 having a thickness of 3 μm or more and 7 μm or less is formed on the inner surface of the channel 15, particularly the electrode 16-a portion. The film thickness was 5 μm or more.

  In the fourth embodiment, the method for cooling the electrode 16-a shown in FIG. 10 is combined with the protective film forming method described in the first embodiment, but in the second and third embodiments, It can also be performed in combination with the protective film formation method described, and is within the scope of the present invention.

(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to FIG. The fifth embodiment is a method for efficiently forming a protective film on a large number of head chips 11. FIG. 11A is a view of the state of performing the protective film forming method of the fifth embodiment viewed from above, and FIG. 11B is a view viewed from the horizontal direction.

  In the fifth embodiment, the head chip 11 is arranged at substantially equiangular intervals on the circumference of a circle centered on the rotation axis indicated by the symbol C of the rotating member 12-5, and the length direction of the channel 15 is set to the circle. It is arranged in parallel with the radial direction of. A large number of head chips 11 can be arranged by arranging the channels 15 of the head chips 11 in the vertical direction on the rotating member 12-5. Along with this, the direction in which the nozzle holding cylinder 54 holding the nozzle 55 is attached to the side wall of the extending portion 53 of the film forming gas introducing means 5 is changed, and the plurality of channels 15 and the four nozzles 55 of the head chip 11 are arranged. The direction is matched. In order to arrange a large number of head chips 11, the rotating member 12-5 of the first holding means 12 has a larger upper surface diameter than that used in the first embodiment.

  In addition to the arrangement described above, the steps described in the description of the first embodiment are performed on one head chip 11, and then the rotating member 12-5 is rotated at the same angular interval to be arranged adjacently. By repeating the same process on the head chip 11, it becomes possible to efficiently form a protective film on a large number of head chips 11.

  The method described with reference to FIG. 11 is a method in which a method for forming a protective film on a large number of head chips 11 using the apparatus shown in FIG. 11 is combined with the method described in the first embodiment. It can also be performed in combination with the methods of the second to fourth embodiments, and is within the scope of the present invention.

  According to the embodiment of the present invention described above, a protective film of polyparaxylylene can be formed on the inner surface of the channel of the head chip for the inkjet head, and the film thickness can be set to 7 μm at the maximum and 3 μm at the minimum. A protective film forming method for forming a protective film having a necessary and sufficient thickness over the entire length direction of the channel was realized, and the object of the present invention was achieved. In addition, a protective film having a sufficient thickness could be formed on the surface of the electrode portion where the necessity of a protective film was particularly high even inside the channel. The maximum film thickness of the protective film of 7 μm is 14 μm or less in total on both sides, and the channel width can be reduced within 8% with respect to the channel width of 0.18 mm (180 μm).

  By applying the protective film forming method of the present invention to the protective film formation of the head chip of the inkjet head, it is possible to realize an inkjet head having durability of tens of thousands of hours or more in operation time.

  Although the case where polyparaxylylene is used as the protective film has been described, tetrachloropolyparaxylylene, difluoropolyparaxylylene, etc., which are derivatives thereof, may be used depending on the characteristics required for the protective film. In addition, if a material other than polyparaxylylene or a derivative thereof can be ejected as a gas, the protective film should be formed using a material suitable for the droplet discharge head on which the protective film is formed. Are also within the scope of the present invention.

It is a figure which shows the whole film forming apparatus which implements this invention. It is a figure which shows the film forming chamber inside of the film forming apparatus which implements this invention. It is a figure which shows the example of the nozzle holding cylinder for ejecting film forming gas, a nozzle, and a gas jet nozzle. It is a figure which shows the other example of the nozzle holding cylinder for ejecting film forming gas, a nozzle, and a gas jet nozzle. It is a figure which shows the other example of the gas jet nozzle for ejecting film forming gas. It is a figure which shows the 1st holding means which hold | maintains a head chip | tip movably. It is a figure which shows the head chip in which a protective film is formed with the method of forming the protective film of this invention. It is a figure which shows the method of inserting a nozzle in the inside of a channel and introduce | transducing film-forming gas into the inside of a channel. It is a figure which shows the method of ejecting film forming gas from the outside in the vicinity of the opening part of a channel, and introducing it into the inside of a channel. It is a figure which shows the method of forming a protective film in the state which cooled the electrode. It is a figure which shows the method for forming a protective film efficiently in the inside of the channel of a some head chip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film forming apparatus 4 Film forming chamber 5 Film forming gas introducing means 11 Head chip 12 First holding means 13 Second holding means 15 Channel 16 Electrode 17 Substrate 18 Cover material 20 Peltier element 21 Protective film 54 Nozzle holding cylinder 55 Nozzle 56 Gas outlet

Claims (4)

A film-forming chamber provided with a film-forming gas introducing means having a nozzle having a gas outlet, and a protective film is formed on the inner surface of a tunnel-like channel having an opening formed in a head chip used for a droplet discharge head In the protective film forming method to be formed,
Depressurizing the film forming chamber;
Inserting the gas outlet from the opening into the channel;
Forming a protective film on the inner surface of the channel by blowing a film-forming gas from the gas outlet under reduced pressure, introducing the film-forming gas into the channel, and
A method for forming a protective film, comprising: A film-forming chamber provided with a film-forming gas introducing means having a nozzle having a gas outlet, and a protective film is formed on the inner surface of a tunnel-like channel having an opening formed in a head chip used for a droplet discharge head In the protective film forming method to be formed,
Depressurizing the film forming chamber;
Under reduced pressure, the gas ejection port is relatively moved from the outside of the opening to the inside of the channel, and the deposition gas is ejected from the gas ejection port to introduce the deposition gas into the channel. And forming a protective film on the inner surface of the channel;
A method for forming a protective film, comprising: A film-forming chamber provided with a film-forming gas introducing means having a nozzle having a gas outlet, and a protective film is formed on the inner surface of a tunnel-like channel having an opening formed in a head chip used for a droplet discharge head In the protective film forming method to be formed,
Depressurizing the film forming chamber;
Bringing the gas outlet close to the opening;
Forming a protective film on the inner surface of the channel by injecting the film-forming gas directly from the gas outlet toward the opening under reduced pressure, introducing the film-forming gas into the channel, and
A method for forming a protective film, comprising: The inner surface of the channel is at least partly formed as an electrode,
The method for forming a protective film according to claim 1, wherein a film forming gas is introduced in a state where the electrode is cooled to form a protective film on the inner surface of the channel.

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