JP2017094636A - Method for manufacturing liquid discharge head, and liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin liquid discharge head having a high energy efficiency having a smooth discharge port surface.SOLUTION: A recess 12 is formed on a resin layer B having a refractive index n1, and a photosensitive material layer is laminated on the recess which has a refractive index n2 smaller than n1 so as to cover the recess 12. The surface of the photosensitive material layer is exposed with light so as to pass the irradiation light through the recess, and the photosensitive material layer is developed. Thereby, a discharge port 2 passing through the resin layer and the photosensitive material layer is formed in a state of having a taper shaped portion 2b and a linearly shaped portion 2c.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a liquid discharge head for discharging a liquid such as ink and a manufacturing method thereof.

  A liquid discharge head mounted in an ink jet recording apparatus or the like imparts an ejection port for ejecting liquid as a droplet, a liquid path for guiding the liquid to the ejection port, and energy discharged from the ejection port. Therefore, the energy generating elements are arranged with high density. In such a liquid discharge head, it is important from the viewpoint of energy efficiency how to efficiently convert the energy generated by the energy generating element into discharge energy.

  At this time, the ink to which energy is applied from the energy generating element can move in two directions, that is, the direction of the ejection port and the direction of the liquid path to which the ink has been supplied. Therefore, in order to improve energy efficiency, a device for guiding the ink to which energy has been applied in the direction of the ejection port as much as possible is required.

  For example, in Patent Document 1 and Patent Document 2, the tubular portion from the pressure chamber that imparts energy to the ink toward the discharge port is tapered, and the flow resistance in the discharge port direction is kept low, giving priority to the direction of the discharge port. An arrangement for guiding ink is disclosed. According to Patent Document 1, a method for manufacturing a liquid discharge head in which such a tapered shape is formed using electroforming is disclosed. Patent Document 2 discloses a method for manufacturing a liquid discharge head in which such a tapered shape is formed by employing photolithography.

JP 2007-231309 A US Pat. No. 7,855,616

  However, in Patent Document 1, after a plurality of discharge ports having a tapered tubular portion are formed in the discharge port plate, it is necessary to attach the discharge port plate to the substrate on which the energy generating element is formed. Thinning is difficult. In particular, in inkjet recording heads that require high-resolution images as in recent years, it is necessary to arrange a large number of discharge ports at high density. If priority is given to thinning, the strength required for pasting is ensured. You will not be able to.

  On the other hand, in Patent Document 2, which employs photolithography to manufacture a liquid discharge head, there is no sticking process as in Patent Document 1, so that thinning is relatively easy. However, in the configuration of Patent Document 2, as a result, individual discharge ports are formed in the depressions of the discharge port plate. For this reason, even if the discharge port surface is cleaned using a wiper, the wiper does not reach the position of the discharge port, and there is a possibility that an adhering matter of ink remains in the vicinity of the discharge port and hinders subsequent discharge.

  The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide a thin liquid discharge head having high energy efficiency and having a smooth discharge port surface.

  Therefore, the present invention discharges liquid from the discharge port of the tubular portion formed by connecting the tapered portion and the linear portion by applying energy to the liquid supplied from the liquid flow path using an energy generating element. A method of manufacturing a liquid discharge head, the step of forming a first resin layer at a position covering the energy generating element of a substrate on which the energy generating element is disposed, and the first resin on the surface of the substrate A step of forming a second resin layer using a photosensitive material having a refractive index n1 at a position covering the layer, and a region excluding a region corresponding to the energy generating element on the surface of the second resin layer And applying heat treatment to form a recess in a region corresponding to the energy generating element of the second resin layer, and to cover the second resin layer in which the recess is formed , N1 A step of forming a photosensitive material layer having a smooth surface by applying a photosensitive material having a small refractive index n2, and a region of the surface of the photosensitive material layer corresponding to the recess is irradiated with the light. A discharge port forming step of forming the tubular portion extending through the second resin layer and the photosensitive material layer and extending to the first resin layer by performing exposure and passing through a recess. And the linear shape portion is formed in a region where the irradiation light in the ejection port forming step proceeds through the photosensitive material layer, and the tapered shape portion is refracted when the irradiation light passes through the recess. After that, the second resin layer is formed in a traveling region.

  ADVANTAGE OF THE INVENTION According to this invention, the thin liquid discharge head with a high energy efficiency which has a smooth discharge port surface can be provided.

(A) And (b) is a figure of the liquid discharge head which can be used by this invention. (A) And (b) is a figure for demonstrating the discharge element of 1st Embodiment. (A) And (b) is a figure for demonstrating the discharge element as a comparative example. (A) And (b) is a figure for demonstrating the discharge element as a comparative example. (A)-(i) is a figure for demonstrating the manufacturing process of a liquid discharge head. It is an enlarged view for demonstrating the irradiation state in a discharge outlet formation process. It is a figure which shows the relationship between a relative refractive index and a taper angle. (A) And (b) is a figure for demonstrating the discharge element of 2nd Embodiment.

  1A and 1B are a perspective view and a cutaway view of a liquid discharge head that can be used in this embodiment. FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG. The liquid discharge head 100 according to this embodiment has a three-layer structure including a substrate 34, a flow path component 4, and a discharge port plate 8.

  The liquid supply chamber 10 penetrating the substrate 34 in the Z direction and extending in the Y direction is connected to the supply port 3 extending in the Y direction in the flow path component 4 at the opening in the + Z direction. A plurality of liquid flow paths 7 are connected to both sides of the supply port 3 in the X direction, and a pressure chamber 5 is provided at an end portion where the liquid flow path 7 extends in the X direction. The pressure chamber 5 is connected to the discharge port 2 formed in the discharge port plate 8, and the energy generating element 1 is disposed at a position on the substrate 34 facing the discharge port 2 through the pressure chamber 5. . Such a combination of the discharge port 2, the pressure chamber 5, and the energy generating element constitutes one discharge element 200 for discharging a liquid as a droplet. In the present embodiment, the plurality of ejection elements 200 are arranged at a density of 600 dpi (dots / inch) in the Y direction. A detailed configuration of the ejection element will be described later.

  The liquid supplied from the liquid supply chamber 10 to each pressure chamber 5 through the supply port 3 and the common liquid chamber 6 is discharged from the discharge port 2 by applying energy from the energy generating element 1 at a predetermined timing. The In the present embodiment, the energy generating element 1 is an electrothermal transducer (heater) that generates heat with the application of a voltage pulse. When the voltage pulse is applied, the energy generating element 1 generates heat rapidly, and liquid film boiling occurs in the pressure chamber 5, and the liquid in the pressure chamber 5 is guided to the discharge port 2 by the growth energy of the generated bubbles. It is a mechanism to be discharged.

  FIGS. 2A and 2B are an enlarged top view and a cross-sectional view for explaining a detailed configuration of the ejection element 200 in the present embodiment. As shown in FIG. 2A, the discharge port 2 is a circle with a diameter of 20 μm, and the energy generating element 1 (heater) is a square with a size of 30 × 30 μm.

  Referring to FIG. 2B, the discharge port 2 has a tubular portion 2a that connects the pressure chamber 5 and the discharge port surface 8a. And this tubular part 2a is comprised by the taper-shaped part 2b in the liquid flow path side, and the linear shape part 2c in the discharge port surface 8a side. In the Z direction, the distance L from the energy generating element 1 to the ceiling of the liquid flow path 7 is 20 μm. Further, the height L2 of the tapered portion 2b is 15 μm, the height L1 of the linear portion 2c is 10 μm, and the overall height L of the tubular portion 2a is L = 10 + 15 = 25 μm.

  Hereinafter, the effect of having the tapered portion 2b in a part of the tubular portion 2a as in the present embodiment will be described. FIGS. 3A and 3B and FIGS. 4A and 4B are diagrams for comparison with the liquid ejection head according to the present embodiment described in FIGS. 2A and 2B. In both figures, the diameter of the discharge port 2, the size of the energy generating element 1, the distance L0 from the energy generating element 1 to the ceiling of the liquid flow path 7, and the overall height L of the tubular portion 2a are shown in FIG. Equal to (b). However, in FIGS. 3A and 3B, the tapered portion 2b as in the present embodiment is not provided, and the entire tubular portion 2a is a linear portion 2c. On the other hand, in FIGS. 4A and 4B, the linear portion 2c is not provided, and the entire tubular portion 2a is a tapered portion 2a.

  The flow resistance in the tubular portion 2a connecting the discharge port 2 and the pressure chamber 5 depends on the length and cross-sectional area. The shorter the length of the tubular portion 2a and the larger the cross-sectional area, the smaller the flow resistance and the higher the energy efficiency. Therefore, in the configuration of FIGS. 3A and 3B without the tapered portion 2b, the cross-sectional area is smaller than that of the present embodiment and the configurations of FIGS. It gets bigger. As a result, the configurations of FIGS. 3A and 3B have the lowest energy efficiency among the above three configurations.

  On the other hand, the height L of the tubular portion 2a inevitably varies to some extent in the manufacturing process of the liquid ejection head 100. At this time, if the linear shape portion 2c is arranged on the discharge port surface 8a side like the tubular portion 2a of the present embodiment, the size of the discharge port 2 on the discharge port surface 8a even if the height L varies slightly. Will not change. However, as shown in FIGS. 4A and 4B, when the entire tubular portion 2a has a tapered shape, the size of the discharge port 2 also changes as the height L varies. Since the size of the discharge port 2 greatly affects the discharge amount, the discharge speed, etc., in the configuration shown in FIGS. 4A and 4B, the discharge amount for each liquid discharge head or for each lot at the time of manufacture. Varies, and the quality of the result becomes unstable.

  That is, the configuration of the tubular portion 2a described with reference to FIGS. 2A and 2B can be said to be an effective configuration in order to realize a liquid discharge head with high energy efficiency and suppressed discharge amount variation.

  5A to 5I are diagrams for explaining a manufacturing process of the liquid discharge head 100 of this embodiment. First, as shown in FIG. 5A, a substrate 34 on which the energy generating element 1 is formed is prepared. In this embodiment, a silicon substrate is used as the substrate 34.

  Next, 20 μm of polymethylisopropenyl ketone (ODUR-1010 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied and exposed with an exposure apparatus UX3000 (Ushio Electric). Thereby, as shown in FIG.5 (b), the resin layer A used as the subsequent liquid flow path 7 is patterned.

  Further, a cationic polymerizable photosensitive resin is applied from the surface of the substrate 34 at a film pressure of 40 μm so as to cover the resin layer A, and heat treatment is performed at a predetermined temperature and time. As a result, a resin layer B to be a later flow path wall is formed as shown in FIG. As the liquid agent for the resin layer B, an epoxy resin, a cationic polymerizable initiator, a silane coupling agent, an additive, a solvent and the like can be employed. The refractive index of the resin layer B is n1.

Next, as shown in FIG. 5D, the mask 11 is disposed above the resin layer B in the Z direction so that the position where the discharge port 2 is to be formed is a non-exposed portion. Then, the surface of the resin layer B is exposed at 2500 J / m ² through the mask 11. In this process, an I-line exposure stepper (manufactured by Canon Inc.) is used.

  Thereafter, a heat treatment (Post Exposure Bake) is performed at a temperature equal to or higher than the softening point of the resin layer B. As a result, the exposed portion (the unmasked region) of the resin layer B is cured and contracts. On the other hand, the non-exposed portion (masked region) located above the energy generating element 1 is softened by overheating and is attracted as the surrounding exposed portion contracts and hardens. As a result, as shown in FIG. 5 (e), the recessed portion 12 corresponding to the contracted volume is formed on the surface of the resin layer B corresponding to the hole of the mask 11.

  Further, a photosensitive material having a refractive index n2 (n1> n2) is applied to the surface of the resin layer B in which the recesses 12 are formed. As a result, as shown in FIG. 5F, a new photosensitive material flows into the recess 12 formed on the surface of the resin layer B, and a photosensitive material layer C having a smooth surface is formed.

  Next, as shown in FIG. 5G, a mask is provided, and a position where the discharge port 2 of the photosensitive material layer C is to be formed is exposed and developed. Thereby, the tubular part 2a having the tapered part 2b and the linear part 2c is formed.

  FIG. 6 is an enlarged view for explaining an irradiation state in the discharge port forming step of FIG. A photosensitive material layer C having a smaller refractive index n2 is laminated above the resin layer B in which the concave portion 12 is formed and has a refractive index n1, and light is irradiated from the surface thereof. Since the boundary surface between the resin layer B and the resin layer C having different refractive indexes is a curved surface, this plays the role of a lens, and when passing through the boundary portion, the irradiation light is refracted so as to spread outward. The relative refraction angle at this time is determined by the refractive index n1 of the resin layer B, the refractive index n2 of the photosensitive member layer C, and the inclination angle of the recess. The relative refractive index N can be expressed as N = n1 / n2. The larger the refractive index N, the larger the refraction angle and the wider the tapered portion 2b.

  FIG. 7 is a diagram showing the relationship between the relative refractive index N and the taper angle. Here, the case where the angle of the recess 12 is 15 °, 30 °, and 45 ° is shown. The taper angle increases as the relative refractive index N increases, and the taper angle increases as the angle of the recess 12 increases (that is, the curvature of the boundary surface increases).

  When the relative refractive index N is increased in order to increase the taper angle, the refractive index n2 of the resin layer C may be increased and the refractive index n1 of the resin layer B may be decreased. However, if the refractive index n1 is too large, the transmittance in the resin layer B is reduced, and the sensitivity may be lowered. From FIG. 7, it is preferable that the relative refractive index is N ≦ 3 considering that the increase rate of the taper angle decreases as the relative refractive index N increases.

  Returning to FIG. After the tubular portion 2a as shown in FIG. 5G is formed, the liquid supply chamber 10 as shown in FIG. As a technique, an anisotropic etching technique using a difference in etching rate depending on the crystal orientation of silicon may be used.

  Further, by removing the resin layer A by dipping in a solvent, the common liquid chamber 6 that connects the nozzle 2 formed in FIG. 5G and the liquid supply chamber 10 formed in FIG. A passage 7 and a pressure chamber 5 are formed. Thereby, the liquid discharge head 100 is completed as shown in FIG.

  As described above, according to the steps described in FIGS. 5A to 5I, it is possible to manufacture a thin liquid discharge head in which discharge elements having a tapered shape are arranged at high density toward the discharge opening. As a result, it is possible to execute a high-density discharge operation with high energy efficiency.

(Second Embodiment)
The ejection element of this embodiment basically has the same configuration as the ejection element of the first embodiment. Only differences from the ejection element of the first embodiment will be described below.

  8A and 8B are an enlarged top view and a cross-sectional view for explaining the detailed configuration of the ejection element 200 in the present embodiment. 2 (a) and 2 (b) is that, in the discharge port 2, two opposing protruding portions 21 protrude from the inner wall of the tubular portion 2a. The protruding portion 21 extends along the inner wall of the tubular portion 2a in the Z direction, that is, from the tapered portion 2b to the entire linear portion 2cb.

  In the present embodiment, such a protrusion 21 is provided in order to reduce the occurrence of mist accompanying the discharge operation. By providing the protruding portion 21, a portion having a high flow resistance and a portion having a low flow resistance are formed in the tubular portion 2. According to the earnest study by the inventors of the present application, the effect of reducing the mist increases as the difference in the flow resistance increases. It has been confirmed that it will increase. That is, in the configuration of the present embodiment, the larger the protrusion length D from the inner wall of the tubular portion and the longer the length L1 of the linear portion 2c, the larger the drop in flow resistance in the tubular portion 2 becomes. Can be suppressed.

  The liquid discharge head according to the present embodiment can also be manufactured by the steps described with reference to FIGS. 5A to 5I basically as in the first embodiment. At this time, if the mask used in the step of FIG. 5 (g) is changed to a mask having a shape in which the protrusion is attached to a circle instead of a simple circle, the discharge port 2 as shown in FIG. Can be formed. And if the discharge head of this embodiment created in such a process is used, high-density discharge operation with high energy efficiency can be performed in a state where mist is suppressed.

  In addition, about the number of the projection parts 21, and the cross-sectional shape of a discharge outlet, it is not restricted to the said form. Any shape other than a circle may be used as long as it can be handled by the mask, and any number of protrusions may be provided. Of course, in the present embodiment, the purpose of providing the protrusion 21 is not limited to the reduction of mist. Regardless of the shape for any purpose, it is possible to improve energy efficiency while maintaining the performance for the purpose by forming a part of the tubular portion into a tapered shape. This is an effect of the embodiment.

  By the way, in the process demonstrated in FIG. 5 (a)-(i), the length L1 of the linear shape part 2c and the taper-shaped part 2b are adjusted by adjusting the application quantity in FIG.5 (c) and (f). The length L2 and the length L of the entire tubular portion 2a can be changed. Further, the angle of the tapered portion 2b can be changed by adjusting the refractive indexes n1 and n2 of these materials within a range satisfying the relationship of n1> n2. Further, the extent of the taper-shaped portion 2b depends on the size of the concave portion 12, and the size is not only the mask used in FIG. 5D (specifically, the shape of the non-exposed portion) but also the exposure during irradiation. It can also be adjusted by the amount, temperature and time during heat treatment. In the present invention, by adjusting various parameters as described above, it is only necessary to form an optimal ejection port according to various conditions such as the type of liquid used, the array resolution of ejection elements in the ejection head, and the ejection frequency. .

  For example, in the second embodiment, the protrusion length D and the length L1 of the linear portion 2c are optimized so that sufficient mist reduction hardening can be obtained, and then the tapered shape is realized so as to realize a desired energy efficiency. The length L2 of the part 2b can be adjusted. However, it is preferable to set the length L1 of the linear shape portion as small as possible from the viewpoint of energy efficiency. In the case of the second embodiment, it is desirable to set L1 <L2 within a range in which a mist reduction effect is sufficiently obtained while covering manufacturing tolerances.

  In the above two embodiments, a silicon substrate is used as the substrate 34, and the discharge port plate 8 and the flow path component 4 are made of the same member. However, such a form is not particularly limited. As for the substrate 34, any material other than silicon can be effectively used as long as it can supply liquid while supporting the above-described laminated structure.

  Also, the discharge port plate 8 and the flow path component 4 may be manufactured from different members as long as the above functions can be sufficiently achieved. As the photosensitive material layer C to be the discharge port plate 8, a material similar to the resin layer B can be used as long as a suitable refractive index contrast can be realized with the resin layer B to be the flow path component 4. . For example, in view of the fact that the photosensitive material layer C is disposed on the surface of the discharge port, it is possible to improve the antifouling property of the discharge port surface by containing a material having water repellency.

1 Energy generating element
2 Discharge port
2a Tubular part
2b Tapered part
2c Straight part
4 Flow path component (resin layer B)
7 Liquid flow path
8 Discharge port plate (photosensitive material layer)
12 recess
34 Substrate
100 Liquid discharge head

Claims (8)

Method of manufacturing liquid discharge head for discharging liquid from discharge port of tubular portion formed by connecting tapered shape portion and linear shape portion by applying energy to liquid supplied from liquid flow path using energy generating element Because
Forming a first resin layer at a position covering the energy generating element on a substrate on which the energy generating element is disposed;
Forming a second resin layer at a position covering the first resin layer on the surface of the substrate using a photosensitive material having a refractive index n1,
A region of the surface of the second resin layer excluding a region corresponding to the energy generating element is exposed to light, and further subjected to heat treatment, whereby a recess is formed in the region corresponding to the energy generating element of the second resin layer. Forming a step;
Forming a photosensitive material layer having a smooth surface by applying a photosensitive material having a refractive index n2 smaller than n1 so as to cover the second resin layer in which the concave portion is formed;
A region corresponding to the concave portion of the surface of the photosensitive material layer is exposed so that irradiation light passes through the concave portion, and further developed to penetrate the second resin layer and the photosensitive material layer. A discharge port forming step of forming the tubular portion extending to the first resin layer;
Have
The linear shape portion is formed in a region where irradiation light in the ejection port forming step proceeds through the photosensitive material layer, and the tapered shape portion is refracted when the irradiation light passes through the concave portion and then the second portion. A method for manufacturing a liquid discharge head, wherein the liquid discharge head is formed in a region where the resin layer advances.   The method of manufacturing a liquid ejection head according to claim 1, wherein the refractive indexes n1 and n2 satisfy a relationship of n1 / n2 ≦ 3.   The method of manufacturing a liquid discharge head according to claim 1, wherein the tapered portion is longer than the linear portion in a direction in which the liquid in the tubular portion is discharged. Forming a liquid supply chamber for supplying a liquid to the liquid flow path on the substrate;
4. The liquid discharge head according to claim 1, further comprising a step of forming the liquid flow path by immersing in a solvent to remove the first resin layer. 5. Manufacturing method.   5. The method of manufacturing a liquid ejection head according to claim 1, wherein the photosensitive material layer has water repellency.   6. The liquid discharge head according to claim 1, wherein a mask used for exposure in the discharge port forming step is a mask in which an irradiated region is not circular. Manufacturing method. The energy generating element is composed of an electrothermal converter,
7. The liquid according to claim 1, wherein the liquid is discharged from the discharge port by growth energy of bubbles generated in the liquid as the electrothermal converter generates heat. Manufacturing method of liquid discharge head. A liquid discharge head that discharges liquid from a discharge port of a tubular portion formed by connecting a tapered shape portion and a linear shape portion by applying energy to the liquid supplied from the liquid flow path using an energy generating element. ,
Forming a first resin layer at a position covering the energy generating element on a substrate on which the energy generating element is disposed;
Forming a second resin layer using a photosensitive material having a refractive index n1 at a position covering the first resin layer of the substrate;
A region of the surface of the second resin layer excluding a region corresponding to the energy generating element is exposed to light, and further subjected to heat treatment, whereby a recess is formed in the region corresponding to the energy generating element of the second resin layer. Forming a step;
Forming a photosensitive material layer having a smooth surface by applying a photosensitive material having a refractive index n2 smaller than n1 so as to cover the second resin layer in which the concave portion is formed;
A region corresponding to the concave portion of the surface of the photosensitive material layer is exposed so that irradiation light passes through the concave portion, and further developed to penetrate the second resin layer and the photosensitive material layer. A discharge port forming step of forming the tubular portion extending to the first resin layer;
Manufactured by a manufacturing method having
The linear shape portion is formed in a region where irradiation light in the ejection port forming step proceeds through the photosensitive material layer, and the tapered shape portion is refracted when the irradiation light passes through the concave portion and then the second portion. A liquid discharge head, characterized in that the liquid discharge head is formed in a region in which the resin layer advances.