JP2020146974A - Manufacturing method for liquid ejection head - Google Patents

Abstract

To provide a manufacturing method for a liquid ejection head, whereby chip shrink of the liquid ejection head can be achieved using existing equipment, by stably forming a PVA layer at a required position of a liquid supply port.SOLUTION: A manufacturing method for a liquid ejection head comprises: a step of forming, in a substrate with an energy generation element disposed on a first surface thereof, a liquid supply port penetrating the substrate; a step of covering an opening at a first surface side of the liquid supply port with a tape; a step of forming a PVA layer covering the opening at the first surface side of the at least liquid supply port by inserting a dispense nozzle into the liquid supply port from a second surface side and injecting a PVA solution into the liquid supply port; a step of removing the tape; a step of forming a nozzle layer on the first surface of the substrate with the PVA layer formed thereon; and a step of removing the PVA layer. The manufacturing method for the liquid ejection head satisfies one or both of conditions (1) and (2) defined in the description.SELECTED DRAWING: Figure 5-1

Description

The present invention relates to a method for manufacturing a liquid discharge head.

In recent years, various silicon devices have been applied to various devices such as liquid discharge heads such as inkjet recording heads, thermal sensors, pressure sensors, and acceleration sensors by micromachining technology.

In order to satisfy various demands such as high density, high precision, cost reduction and tact-up, such various silicon devices use microfabrication technology, which is a micromachining technology, in manufacturing.

Here, the liquid discharge head has a nozzle layer having a discharge port for discharging liquid arranged on an element substrate having an energy generating element and a liquid supply port from the viewpoint of connection with an external liquid supply system and holding of the substrate. It has a structure in which the liquid discharge head substrate is joined to some kind of support member.

The following method can be considered as a method of providing an inexpensive and high-definition liquid discharge head while maintaining this configuration. That is, in the case of a liquid discharge head that discharges a plurality of types of liquids, for example, a color-based inkjet recording head, it is conceivable to narrow the pitch between liquids on the substrate, that is, the pitch between adjacent liquid supply ports. As a result, it is possible to achieve chip shrink of the liquid discharge head by increasing the number of chips produced from one wafer and reducing the cost.
However, if the pitch between adjacent liquid supply ports is narrowed, the thickness of the portion corresponding to the liquid supply port wall that defines the shape of the liquid supply port becomes thin, and the chip cracks when an impact is received from the outside. , The physical strength may decrease.

Therefore, various studies have been conducted to narrow the liquid supply port itself instead of the liquid supply port wall.
Specifically, before forming the nozzle layer, a method of forming a liquid supply port having a narrow opening width by cutting, penetrating laser, wet etching, dry etching or the like can be considered.
However, since it is usually difficult to apply a nozzle layer forming material on a substrate on which a liquid supply port is formed by using a spin coating method or the like, a method of forming the material into a film and then attaching the material is used. Taken. However, with such a method, capital investment increases and processing costs increase, and as a result, cost reduction may not occur.

Therefore, in Patent Document 1, before forming the nozzle layer, a liquid supply port penetrating the substrate is formed in advance on the substrate on which the energy generating element is formed. Then, by filling the liquid supply port with a filler in a state where the specific opening of the liquid supply port is closed with tape, a filler layer that closes the opening on the nozzle layer side is formed, and a dry film is used. Nozzle layer is formed.

JP-A-2002-326363

As described above, since the method described in Patent Document 1 forms a liquid supply port in advance, it is effective in narrowing the inter-liquid pitch and performing chip shrink in a liquid discharge head that discharges a plurality of types of liquids. Method.

However, when the filler is filled in the liquid supply port by using the method described in Patent Document 1, the filler is injected from above the liquid supply port without inserting the dispense nozzle into the liquid supply port. For this reason, there are cases where the filler adheres around the liquid supply port, or it is difficult to dispose the filler at a desired position with a desired thickness. Further, in this method, the filler filled in the liquid supply port may be unevenly dried, or the dispense nozzle may be clogged when the filler is injected into the liquid supply port.
Therefore, in order to achieve chip shrink of the liquid discharge head, further improvement is required in the method of manufacturing the liquid discharge head using the filler.

Therefore, the present invention provides a method for manufacturing a liquid discharge head, which can achieve chip shrink of the liquid discharge head by using existing equipment by stably forming a filler layer at a desired position of the liquid supply port. The purpose is.

The present invention for solving the above problems includes a nozzle layer having a discharge port for discharging a liquid, an energy generating element for discharging the liquid from the discharge port, and a liquid supply port for supplying the liquid to the discharge port. A method of manufacturing a liquid discharge head having an element substrate having the above.
A step of forming the liquid supply port penetrating the first surface of the substrate and the second surface facing the first surface on the substrate on which the energy generating element is arranged on the first surface, and the liquid. The step of covering the opening on the first surface side of the supply port with tape, and inserting the dispense nozzle into the liquid supply port from the second surface side, and injecting the PVA aqueous solution from the dispense nozzle into the liquid supply port. Then, at least a PVA layer forming step of forming a PVA layer covering an opening on the first surface side of the liquid supply port, a step of removing the tape, and the first step of the substrate on which the PVA layer is formed. It has a step of forming the nozzle layer and a step of removing the PVA layer on the surface of the surface, and is characterized in that one or both of the following conditions (1) and (2) are satisfied. This is a method for manufacturing a liquid discharge head.
(1) The PVA concentration of the PVA aqueous solution is 18% by mass or more and 30% by mass or less, and the degree of polymerization of PVA used in the PVA aqueous solution is 200 or more and 400 or less.
(2) The PVA layer is formed so that the liquid supply port extends in the direction of the discharge port row of the liquid discharge head, and is perpendicular to the direction of the discharge port row and parallel to the substrate surface. The thickness of the liquid supply port at the center is 15 μm or more and 60 μm or less.

According to the present invention, a PVA layer serving as a filler layer can be stably formed at a desired position of a liquid supply port, and a tip shrink of the liquid discharge head can be achieved by using existing equipment. A manufacturing method can be provided.

It is a figure which shows the liquid discharge head obtained from one Embodiment of this invention, (a) is a schematic perspective view of the liquid discharge head, (b) is a schematic cross-sectional view of the liquid discharge head. 5 is an X-ray analysis cross-sectional photograph for showing uneven drying due to the filler filled in the liquid supply port. It is an X-ray analysis sectional photograph of the PVA layer in the liquid supply port in a plurality of embodiments of this invention. It is a schematic cross-sectional view which shows an example of the conventional liquid discharge head. It is a process sectional view for demonstrating a part ((a)-(h)) of each process in one Embodiment of this invention. It is a process sectional view for demonstrating a part ((i)-(o)) of each process in one Embodiment of this invention. (A) and (b) are diagrams for explaining the PVA layer formed in the liquid supply port of the present invention and the conventional one, respectively. It is a figure for demonstrating the relationship between the degree of polymerization of PVA of a PVA aqueous solution, and PVA layer. It is a figure for demonstrating the relationship between the PVA concentration of a PVA aqueous solution, and the clogging of a dispense nozzle.

As described above, when the filler is filled in the liquid supply port based on the method described in Patent Document 1, the filler may adhere to the periphery of the liquid supply port, or the filler may be filled in a desired position with a desired thickness. It was sometimes difficult to place the agent.
However, in the present invention, the dispensing nozzle is inserted into the liquid supply port, and the filler (PVA) is in a state where the dispense nozzle is brought close to the nozzle layer side opening of the liquid supply port, that is, the opening on the first surface side. (Polyvinyl alcohol) aqueous solution) is injected into the liquid supply port. Therefore, the filler layer (PVA layer) can be stably formed at a desired position of the liquid supply port without the filler adhering to the periphery of the liquid supply port. Thereby, in the present invention, the nozzle layer can be stably formed on the element substrate without using the dry film, and the chip shrink of the liquid discharge head can be achieved by using the existing equipment. The dried PVA aqueous solution, that is, the PVA layer is most suitable as a filler because it has solvent resistance that does not dissolve in a solvent or the like normally used when forming the nozzle layer. When a filler having low solvent resistance is used, as shown in FIG. 6B, the filler layer may be dissolved by the organic solvent contained in the mold material 18 or the like when the nozzle layer is formed, which is desired. It may not be possible to form a nozzle layer.

Further, based on the method described in Patent Document 1, when a filler is filled in a liquid supply port in which a specific opening is closed with a tape to form a filler layer, FIGS. 2 (a) and 2 (b) show. As shown, uneven drying 12a of the filler may occur in the liquid supply port, or the filler layer may be torn. Then, there is a case where a manufacturing defect such as the material for forming the nozzle layer dripping into the liquid supply port through the torn portion may occur. The drying unevenness 12a that occurs in the drying process of the filler is caused when the filler is filled by pushing it into the liquid supply port by screen printing technology, or after the filler is placed on the substrate under vacuum conditions, the liquid is supplied at atmospheric pressure. It occurred even when it was pushed into the mouth. Note that FIG. 2A corresponds to a cross-sectional view when the substrate 6 on which the PVA layer is formed is cut along the direction of the discharge port row, and FIG. 2B corresponds to the substrate in the discharge port row. It corresponds to a cross-sectional view when cut perpendicular to the direction.

However, in the present invention, the thickness of the filler layer (at a specific location) in the liquid supply port can be set within a specific range, whereby such uneven drying and tearing of the filler layer can be easily prevented. be able to. Further, in the present invention, the injection amount of the filler, the arrangement of the dispense nozzles at the time of injection, and the like can be set as specific conditions. Thereby, for example, the thickness of the filler layer formed in the liquid supply port can be easily controlled as compared with the case where the filling amount is not controlled (for example, when the filler is filled so as to fill the entire liquid supply port). , The above-mentioned uneven drying and tearing of the filler layer can be prevented more easily.

Further, when a PVA aqueous solution prepared by the following method is used as a filler and continuously injected into the liquid supply port based on the method described in Patent Document 1, the discharge of the PVA aqueous solution gradually becomes unstable. In some cases, the nozzle (for dispensing) could get clogged.
This PVA aqueous solution is mixed with water and PVA, dissolved by heating, and then allowed to stand for several hours to remove air bubbles in the PVA aqueous solution, and filtered with a filter having a diameter smaller than that of the dispense nozzle used to remove foreign substances. It was a thing. Nozzle clogging did not occur when water and PVA were mixed and immediately after being heated and dissolved.
From this, it was found that the nozzle clogging was caused by the following causes. That is, while the PVA aqueous solution is allowed to stand for several hours to remove air bubbles, the temperature of the PVA aqueous solution drops to room temperature (for example, 23 ° C.), and PVA once dissolved in water is precipitated, that is, It was found that it was caused by the difference in the solubility of PVA depending on the temperature.

However, in the present invention, the PVA concentration and the degree of polymerization of the PVA aqueous solution can be set in a specific range. As a result, it is possible to easily prevent PVA from being precipitated and clogging the nozzle even at room temperature, a stable PVA aqueous solution can be discharged, and a PVA layer having a desired thickness can be easily formed.
Further, by setting the viscosity and the degree of saponification of the PVA aqueous solution used as the filler in a specific range, it is easy to place a PVA layer having a desired thickness at a desired position without clogging the nozzle while maintaining an appropriate solvent resistance. Can be formed into.

As described above, in the present invention, in addition to being able to stably form the PVA layer at a desired position of the liquid supply port, it is possible to easily prevent uneven drying, tearing, nozzle clogging, etc. of the PVA layer. Therefore, the nozzle layer can be easily formed on the element substrate by using the spin coating method or the like, and a narrow liquid supply port can be easily formed before forming the nozzle layer. As a result, an inexpensive and reliable liquid discharge head can be easily obtained without requiring new capital investment and without thinning the liquid supply port wall as in the conventional liquid discharge head shown in FIG. be able to. As a result, in the present invention, the tip shrink of the liquid discharge head can be easily achieved. Note that FIG. 4 is a diagram showing an example of a conventional liquid discharge head in which the pitch between adjacent liquid supply ports is narrowed by thinning the liquid supply port wall.

<Liquid discharge head>
The liquid discharge head obtained from the present invention can be mounted on a printer, a copier, a facsimile having a communication system, and an industrial recording device combined with various processing devices in a complex manner. In the following description, the description may focus on the inkjet recording head as the liquid ejection head, but the present invention is not limited to this form.

The liquid discharge head obtained from the present invention will be described in detail below with reference to the drawings. In the following description, configurations having the same function may be given the same number in the drawings, and the description thereof may be omitted.
FIG. 1 is a diagram showing a liquid discharge head obtained from an embodiment of the present invention, (a) is a schematic perspective view of a state in which a part of the liquid discharge head is broken, and (b) is a schematic perspective view. It is a schematic cross-sectional view when the liquid discharge head is cut along the line AA'. The liquid discharge head obtained from the present invention may have a configuration in which a substrate for a liquid discharge head having a nozzle layer and an element substrate, which will be described later, is joined to a support member. However, in the present specification, the description of the support member will be described. It may be omitted. As the support member, a member known in the field of the liquid discharge head can be appropriately used.

As shown in FIG. 1, the liquid discharge head 7 has an element substrate 2 having an energy generating element 4 and a liquid supply port 5, and a nozzle layer 1 having a discharge port 3.

(Nozzle layer)
The nozzle layer 1 is provided on the first surface 6a of the substrate 6 constituting the element substrate 2. The nozzle layer 1 may have at least a (liquid) discharge port 3 for discharging a liquid (for example, a recording liquid such as ink), and may also have a (liquid) flow path 8 communicating with the discharge port 3.
The discharge port 3 is for discharging the liquid, and is formed by opening on the front surface (the surface on the upper side of the paper surface) of the liquid discharge head as shown in FIG. 1 (b). Further, the discharge ports 3 can be formed above the energy generating element 4 (on the front surface side of the liquid discharge head), and are usually formed in a plurality of discharge ports 3 in one liquid discharge head. In FIG. 1A, six discharge port rows formed by arranging the discharge ports at substantially the same pitch along one direction of the liquid discharge head are arranged.
The flow path 8 can be used as a liquid chamber for holding the liquid, and communicates with the discharge port 3 and the liquid supply port 5.
The nozzle layer 1 may be composed of a single layer or a plurality of layers. For example, the nozzle layer 1 may be composed of an orifice plate having a discharge port 3 and a flow path wall member having a flow path 8.

(Element board)
The element substrate 2 is a substrate 6 having a first surface 6a and a second surface 6b facing the first surface 6a, an energy generating element 4 arranged on the first surface 6a, and a first surface. A liquid supply port 5 penetrating the surface 6a and the second surface 6b is formed. In FIG. 1B, the description of the energy generating element 4 is omitted.
As the substrate 6 used for the element substrate 2, for example, a silicon substrate can be used.
The energy generating element 4 is for discharging a liquid from the discharge port 3, and may be any as long as it can generate energy for that purpose. As the energy generating element 4, an electric heat conversion element (heat generating resistor element, heater element) for boiling a liquid, an element for applying pressure to a liquid by volume change or vibration (piezo element, piezoelectric element), or the like can be used. .. The number and arrangement of energy generating elements can be appropriately selected according to the structure of the liquid discharge head to be manufactured. For example, a plurality of these elements are arranged in a row in the direction of the discharge port row described above at a predetermined pitch. It can be provided on the first surface 6a of the substrate. In FIG. 1, the energy generating element 4 is provided at a position facing the discharge port 3 arranged in the nozzle layer 1.

Further, the element substrate 2 includes an electric wiring (not shown) for supplying electric power to the energy generating element 4, a protective film 9 for protecting the energy generating element 4, a thermal oxide film 10 which can also function as an etching mask for a liquid supply port, and the like. Can also have.

The liquid supply port 5 is for supplying the liquid to the discharge port 3, and is open on the first surface 6a and the second surface 6b. The shape of the liquid supply port is not particularly limited, but when the filler is injected into the liquid supply port, the dispense nozzle is arranged from the second surface side into the liquid supply port to be located on the first surface side of the liquid supply port. The shape is such that the dispense nozzle can be maintained in a state of being close to the opening. In FIG. 1, the liquid supply port extends in the direction of the discharge port row (hereinafter, may be referred to as the first direction). Further, the liquid supply port is second in a direction perpendicular to the direction of the discharge port row and parallel to the substrate surface (the left-right direction on the paper surface shown in FIG. 1B, hereinafter referred to as the second direction). It is formed so that the opening width at the opening on the surface side of the above is the largest. The opening width of the liquid supply port may be constant or different in the substrate thickness direction. However, from the viewpoint of filling, the opening width of the liquid supply port on the second surface side in the second direction is preferably 360 μm or more and 730 μm or less, and preferably 360 μm or more and 530 μm or less. More preferred.
In FIG. 1, the opening width of the opening on the first surface side of the liquid supply port is formed to be the minimum. The opening width of the opening on the first surface side is preferably 100 μm or more from the viewpoint of filling. Further, as shown in FIG. 1, a plurality of liquid supply ports extending in the first direction can be formed in the second direction.

<Manufacturing method of liquid discharge head>
The method for manufacturing a liquid discharge head of the present invention has the following steps.
-A step of forming a liquid supply port penetrating the first surface and the second surface of the substrate on a substrate on which an energy generating element is arranged on the first surface (liquid supply port forming step).
-A step of covering the opening on the first surface side of the liquid supply port with tape (coating step).
-The dispense nozzle is inserted into the liquid supply port from the second surface side, and the PVA aqueous solution is injected into the liquid supply port from the dispense nozzle to cover at least the opening on the first surface side of the liquid supply port. A step of forming a layer (PVA layer forming step).
-A step of removing the tape (tape removal step).
A step of forming a nozzle layer on the first surface of the substrate on which the PVA layer is formed (nozzle layer forming step).
-A step of removing the PVA layer (PVA layer removing step).

In the present invention, one or both of the following conditions (1) and (2) are satisfied.
(1) The PVA concentration of the PVA aqueous solution is 18% by mass or more and 30% by mass or less, and the degree of polymerization of PVA used in the PVA aqueous solution is 200 or more and 400 or less.
(2) The liquid supply port is formed so as to extend in the direction of the discharge port row, and the thickness of the PVA layer at the center of the liquid supply port in the second direction described above is 15 μm or more and 60 μm or less. ..
Hereinafter, the embodiment of the present invention satisfying the above condition (1) will be referred to as a first embodiment, and the embodiment of the present invention satisfying the above condition (2) will be referred to as a second embodiment. The first embodiment may satisfy the above condition (2), or the second embodiment may satisfy the above condition (1). That is, the first embodiment and the second embodiment may be the same embodiment.

In addition, the PVA layer forming step can include the following steps.
-A step of drying the PVA aqueous solution injected into the liquid supply port (drying step).
Furthermore, the production method of the present invention can include the following steps.
-A process of preparing a substrate having an energy generating element on the first surface (board preparation process).
-A process of attaching a support member to the obtained substrate (support member attachment process).
Each of these steps may be performed sequentially, or a plurality of steps (for example, a nozzle layer forming step and a PVA layer removing step) may be performed in parallel.
Each process will be described in detail below with reference to the drawings. In addition, FIG. 5-1 and FIG. 5-2 are process cross-sectional views for explaining each process in one embodiment of the method for manufacturing a liquid discharge head of the present invention. The cross-sectional view in each step corresponds to a cross-sectional view when the liquid discharge head is cut perpendicularly to the direction of the discharge port row.

(Board preparation process)
First, as shown in FIG. 5-1 (a), a substrate 6 having an energy generating element (not shown) on the first surface 6a is prepared. As the substrate 6, for example, a silicon substrate can be used. Further, as the energy generating element, for example, a heater element that generates energy used for discharging a liquid and generates thermal energy that causes a film to boil in the liquid according to conduction can be used. At this time, on the first surface 6a of the substrate, an electric wiring (not shown) for supplying electric power to the energy generating element, a protective film (insulating film) 9 such as SiN for protecting the element, and the like are applied by photolithography technology (photolithography). It can be formed by multi-layer wiring technology using technology). Further, in FIG. 5-1 (a), a sacrificial layer 14 (for example, aluminum) for determining the opening width of the liquid supply port on the first surface side of the substrate is formed on the first surface 6a of the substrate 6. There is. Further, a thermal oxide film 10 serving as a patterning mask for the liquid supply port on the second surface side is formed on the second surface 6b of the substrate.

(Liquid supply port forming process)
Subsequently, as shown in FIG. 5-1 (b), the mask material 15 is applied onto the first surface 6a of the substrate. The mask material is installed so that the protective film 9 and the like are not damaged by the strong alkali etching solution or the like used when forming the liquid supply port, and is, for example, having alkali resistance.

Next, as shown in FIG. 5-1 (c), a through hole 16 is formed through the obtained substrate substantially perpendicular to the substrate surface. Specifically, for example, a YAG laser or the like is used to form through holes that penetrate the mask material 15, the sacrificial layer 14, the substrate 6, and the thermal oxide film 10. At this time, the thermal oxide film 10 formed on the second surface of the substrate can be patterned so as to scrape off the opening that determines the position of the liquid supply port on the second surface side with a laser. The thermal oxide film 10 may be processed by a patterning method other than the laser.

Subsequently, as shown in FIG. 5-1 (d), the substrate on which the through holes 16 were formed was placed in a TMAH (tetramethylammonium hydroxide) aqueous solution or the like whose temperature was adjusted to a predetermined temperature and concentration for a predetermined time (for example). , 2-4 hours) Immersion and anisotropic etching is performed. As a result, the liquid supply port 5 that penetrates the substrate is formed. At that time, the sacrificial layer 14 is also removed at the same time. In FIG. 5-1 the liquid supply port is formed so as to extend in the direction of the discharge port row (direction perpendicular to the paper surface).
Next, as shown in FIG. 5-1 (e), the unnecessary mask material 15 is removed by immersing it in a removal solution suitable for the material for a predetermined time.
The opening width of the liquid supply port is preferably within the above range from the viewpoint of filling the filler.

(Coating process)
Next, as shown in FIG. 5-1 (f), the opening on the first surface side of the substrate is covered with the tape 13. The tape 13 is a peelable tape having a two-layer structure consisting of a base material 13b and an adhesive layer 13a. Since this tape is peeled off after the formation of the PVA layer, it is preferable to use, for example, a UV peeling type tape whose adhesive strength is lowered by irradiation with ultraviolet rays, or a slightly adhesive tape which is easily peeled off at room temperature (for example, 23 ° C.).

(PVA layer forming step)
Subsequently, as shown in FIGS. 5-1 (g) and 5-1 (h), the dispense nozzle 17 is inserted into the liquid supply port from the second surface 6b side. Then, the filler (PVA aqueous solution) 11 is injected into the liquid supply port with the dispense nozzle 17 close to the opening (first surface 6a) on the first surface side of the liquid supply port 5. As shown in FIG. 8A, at each liquid supply port, the dispense nozzle 17 injects the PVA aqueous solution 11 while moving along the direction of the discharge port row (left-right direction on the paper surface).
At this time, since the dispense nozzle 17 is used by being inserted into the liquid supply port, it is preferable to use an ultra-fine dispense nozzle having a tapered tip, and of course, the second direction (short) of the liquid supply port. It is preferable that the width is narrower than the opening width (in the hand direction). By using a high-definition dispense filling technology that can use ultra-fine needles, it is possible to easily fill each hole of the liquid supply port with an appropriate amount of PVA aqueous solution, and easily solve conventional problems such as uneven drying. can do. For example, a dispense nozzle having an inner diameter φ (diameter) of 100 μm or less, which is narrower than the width of the liquid supply port 5, can be used.

The distance between the tip of the dispense nozzle 17 and the opening on the first surface side of the liquid supply port 5 when injecting the PVA aqueous solution into the liquid supply port can be appropriately set. Is preferably 10 μm or more and 400 μm or less. When the distance between the two is within this range, the thickness of the PVA layer can be easily controlled, and uneven drying or tearing of the PVA layer can be easily prevented by injecting a small amount of the PVA aqueous solution. From the same viewpoint, the distance is more preferably 10 μm or more and 100 μm or less.

The injection amount of the PVA aqueous solution injected into the liquid supply port is preferably 50% or less, and more preferably 20% or less of the volume of the liquid supply port 5. If the filling amount of the PVA aqueous solution is 50% or less, solid content gathers in the vicinity of the opening on the second surface as shown in FIG. 2 even in the case of natural drying or when a drying operation is applied, resulting in uneven drying. Can be easily prevented. As a result, a PVA layer having a desired thickness can be formed at a desired position, and the PVA layer can be easily prevented from being torn in the tape removing step.
As shown in FIG. 2, the mechanism by which uneven drying occurs when the PVA layer is dried is presumed as follows. That is, first, when the surface of the PVA layer near the opening on the second surface side of the liquid supply port where water can easily escape is dried and a difference in solid content concentration in the PVA layer occurs inside the liquid supply port, the solid content concentration Moisture becomes easier to move to the higher side. For this reason, solids also gather near the opening on the second surface side where the drying speed is fast, resulting in uneven drying, and the thickness of the PVA layer becomes thin near the opening on the first surface side of the liquid supply port. , A phenomenon occurs in which the PVA layer is torn in the tape removing step. In the present invention, in order to prevent this uneven drying, a specific PVA layer can be formed using a specific PVA aqueous solution.
For example, 0.2 to 1.1 mg of a heated solution prepared by adjusting the temperature of a PVA aqueous solution, which is a mixture of PVA and water, to 90 ° C. or higher is filled in, for example, a liquid supply port having a volume of 2.28 mm ^3. Therefore, the PVA aqueous solution can be filled at 50% or less with respect to the volume of the liquid supply port.

Here, the PVA aqueous solution filled in the liquid supply port will be described in detail. There are four important parameters for determining the properties of the PVA aqueous solution: the degree of saponification, the degree of polymerization, the PVA concentration (solid content concentration), and the viscosity. Each parameter and its appropriate range will be described below.

The degree of saponification of PVA used in the PVA aqueous solution is a parameter related to solvent resistance, and the higher the value, the higher the solvent resistance. The degree of saponification of PVA is preferably 80 mol% or more and 99 mol% or less. When the degree of saponification of PVA is within this range, the organic solvent contained in the material (for example, the mold material 18 and the nozzle layer forming material 19 described later) used when forming the nozzle layer on the element substrate can be used. It is possible to easily prevent the PVA layer produced in the liquid supply port from being dissolved.

The degree of polymerization of PVA used in an aqueous PVA solution is a parameter that determines how much PVA can be dissolved in water when the viscosity of the aqueous PVA solution is constant. The lower the value, the more PVA can be dissolved in water. Can be dissolved. The degree of polymerization of PVA is preferably 200 or more and 400 or less. In the first embodiment of the present invention, the degree of polymerization of PVA is 200 or more and 400 or less. When the degree of polymerization of PVA is 200 or more, an appropriate mechanical strength can be imparted to the produced PVA layer, and the PVA layer can be easily prevented from being torn in the tape removing step. Further, when the degree of polymerization of PVA is 400 or less, the PVA concentration in the PVA aqueous solution can be easily kept within a desired range, and after the drying step, the filling amount of the PVA aqueous solution is not increased or the PVA concentration is not increased. The thickness of the PVA layer can be easily kept within a desired range.

Here, FIG. 7 shows a diagram showing the relationship between the degree of polymerization of PVA and the PVA layer when the viscosity of the aqueous PVA solution is constant. 7 (a-1) and (a-2) show an aqueous PVA solution having a degree of polymerization of PVA of 250, and FIGS. 7 (b-1) and 7 (b-2) show a degree of polymerization of PVA of 600. It is sectional drawing which shows before and after filling the liquid supply port with the same amount of PVA aqueous solution, and baking process. As shown in these figures, the higher the degree of polymerization of PVA, the thinner the film thickness of the PVA layer tends to be after the baking treatment. Therefore, FIGS. 7 (c-1) and 7 (c-2) show schematic cross-sectional views before and after the baking treatment when the filling amount of the PVA aqueous solution having a PVA polymerization degree of 600 is increased. In this case, uneven drying 12a of the PVA layer 12 may occur during the baking process, solid content collects in the vicinity of the opening on the second surface side, and the PVA layer covers the opening on the first surface side of the liquid supply port. May become thin. In such a case, the PVA layer may be torn in the tape removing step. Therefore, it is preferable to select the degree of polymerization of PVA so that a PVA layer having a desired thickness can be obtained with a filling amount of 50% or less in the liquid supply port described above.

The solid content concentration and viscosity of the PVA aqueous solution are determined using PVA that satisfies the above-mentioned degree of saponification and degree of polymerization. The solid content concentration of the PVA aqueous solution is the concentration of PVA in the PVA aqueous solution, and the film thickness of the PVA layer is determined by the filling amount in the liquid supply port of the PVA aqueous solution. The PVA concentration of the PVA aqueous solution is preferably 10% by mass or more and 30% by mass or less, and more preferably 18% by mass or more and 30% by mass or less.
When the PVA concentration is 10% by mass or more, the amount of the PVA aqueous solution to be filled in the liquid supply port can be reduced, and the filling time can be shortened. Further, when the PVA concentration is 30% by mass or less, stable discharge can be performed without precipitation of PVA at room temperature, and a PVA layer having a desired thickness can be easily formed without clogging the dispense nozzle. be able to. For example, when a PVA aqueous solution having a very high PVA concentration is used, as shown in FIG. 8B, if continuous discharge is performed using the dispense nozzle 17 into the liquid supply port, the discharge gradually becomes unstable. Become. Eventually, the dispense nozzle may be clogged, and it may not be possible to form a PVA layer having a uniform thickness.
In the first embodiment of the present invention, the PVA concentration (solid content concentration) of the PVA aqueous solution is 18% by mass or more and 30% by mass or less. By setting the PVA concentration in this range, a PVA layer having a desired thickness can be formed in a shorter time without clogging the nozzles. The PVA concentration of the PVA aqueous solution can be specified by a viscometer.

At this time, the viscosity of the PVA aqueous solution at 23 ° C. is preferably 0.01 Pa · s or more (10 cP or more) and 1 Pa · s or less (1,000 cP or less) in consideration of filling property. The viscosity of the PVA aqueous solution can be specified by a viscometer.

As the PVA used in the PVA aqueous solution, for example, trade names: JMR-10H and JP-03 (both manufactured by Japan Vam & Poval) can be used.
By using these PVAs, it is possible to easily prevent the PVA layer formed in the liquid supply port from being dissolved in the nozzle layer forming material or the like when the nozzle layer is formed.

Subsequently, as shown in FIG. 5-2 (i), the PVA aqueous solution 11 injected into the liquid supply port is dried (drying step) to form the PVA layer (filler layer) 12. The drying method is not particularly limited, but for example, in order to make the dried state of the PVA layer 12 uniform in the wafer surface, the PVA layer can be dried using a hot plate or the like. The drying time and the drying temperature are not particularly limited, but the PVA layer can be dried, for example, at a setting of 120 ° C. and 300 seconds.

At that time, the thickness of the PVA layer 12 after drying at the liquid supply port is preferably in the following range. That is, it is preferable that the thickness of the PVA layer in the central portion (and its vicinity) of the liquid supply port in the above-mentioned second direction (left-right direction on the paper surface shown in FIG. 5-2) is 15 μm or more and 60 μm or less. If the thickness of the portion is 15 μm or more, it can be easily prevented from being torn after the PVA layer is formed, and if the thickness of the portion is 60 μm or less, uneven drying can be easily prevented. The PVA layer formed in the liquid supply port preferably has a thickness within the above range, but at least the PVA layer in the portion covering the opening on the first surface side of the liquid supply port is in the above range. It is preferable to have an inner thickness.
Here, FIGS. 3 (a) and 3 (b) show cross-sectional photographs of X-ray analysis in the liquid supply port where the thickness of the portion of the PVA layer is 15 μm and 60 μm, respectively. In the second embodiment of the present invention, the thickness of the portion is 15 to 60 μm.

(Tape removal process)
Next, as shown in FIG. 5-2 (j), the tape 13 including the base material 13b and the adhesive layer 13a is removed from the first surface 6a of the substrate. The method for removing the tape is not particularly limited. For example, when a UV peeling type tape whose adhesive strength is lowered by ultraviolet irradiation is used as the tape, the tape can be removed by the following method. That is, the tape can be peeled off from the substrate by irradiating the tape with ultraviolet rays of, for example, 200 mJ or more in a nitrogen atmosphere.

(Nozzle layer forming process)
Subsequently, as shown in FIG. 5-2 (k), the mold material 18 for forming the flow path for supplying the liquid to the discharge port is formed on the first surface 6a of the substrate by the photolithography technique. In the present invention, since the PVA layer 12 can be formed using a specific aqueous PVA solution, even if an organic solvent is used to form the mold material, the solvent resistance of the PVA layer makes it possible to form the mold material in the liquid supply port 5. The mold material 18 can be easily formed without dripping. The material for forming the mold material is not particularly limited, and a material known in the field of the liquid discharge head (for example, a photosensitive resin material) can be used.

Next, as shown in FIG. 5-2 (l), the nozzle layer forming material 19 is applied on the mold material 18 to an arbitrary thickness. The material for forming the nozzle layer is not particularly limited, and a material known in the field of the liquid discharge head (for example, a photosensitive resin material) can be used.
Then, as shown in FIG. 5-2 (m), exposure development and the like are performed to form the discharge port 3. In FIG. 5-2, two rows of discharge ports arranged at substantially equal pitches in the first direction are arranged for one liquid supply port.
Next, as shown in FIG. 5-2 (n), the unnecessary PVA layer 12 is removed by immersing it in water for a predetermined time (PVA layer removing step), and the substrate is dried. Next, as shown in FIG. 5-2 (o), the mold material 18 that is no longer needed is removed by immersing it in a removal liquid corresponding to the mold material 18 used for a predetermined time. Then, by appropriately joining the support member to the obtained substrate (support member attaching step), it is possible to obtain a liquid discharge head in which the liquid supply port 5, the flow path 8 and the discharge port 3 communicate with each other.

As described above, in the production method of the present invention, a specific PVA aqueous solution can be filled in the penetrating liquid supply port, and by forming a specific PVA layer in the liquid supply port, the rigidity and strength of the substrate are sacrificed. The nozzle layer can be formed on the substrate on which the liquid supply port is formed. As a result, it is possible to provide the customer with an inexpensive liquid discharge head with a reduced manufacturing cost.

Hereinafter, the method for manufacturing the liquid discharge head of the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to these examples. In addition, Examples 1 to 3 and Comparative Examples 1 and 2 are examples related to the first embodiment of the present invention, and Examples 4 to 7 and Comparative Examples 3 and 4 are examples of the present invention. It is an example related to the second embodiment.

First, each example related to the first embodiment of the present invention will be described.
[Example 1]
First, as shown in FIG. 5-1 (a), a silicon substrate is prepared as the substrate 6, and a heater element as an energy generating element (not shown) and this element are protected on the first surface 6a of the substrate. A protective film (insulating film) 9 made of SiN was formed. Further, an aluminum sacrificial layer 14 for determining the size of the liquid supply port on the first surface side was formed on the first surface of the substrate. Then, a thermal oxide film (SiO2) 10 serving as a patterning mask for the liquid supply port was formed on the second surface 6b side of the substrate. These formations used a multi-layer wiring technology using photolithography technology (board preparation process).

Next, as shown in FIG. 5-1 (b), a mask material (trade name: HIMAL, manufactured by Hitachi Chemical) 15 was formed on the first surface of the substrate 6. Then, as shown in FIG. 5-1 (c), a through hole 16 penetrating the mask material 15, the aluminum sacrificial layer 14, and the substrate 6 was formed by using a YAG laser. Specifically, in order to form a one-hole liquid supply port, a 220-Pulse laser was irradiated to form a through hole 16. At this time, the thermal oxide film 10 formed on the second surface of the substrate was patterned by hollowing out an opening for determining the position of the liquid supply port on the second surface side with a laser.

Next, as shown in FIG. 5-1 (d), the substrate on which the through holes 16 were formed was immersed in a TMAH aqueous solution having a concentration of 22% by mass adjusted to 83 ° C. for 6 hours, and the mixture was different. Sexual etching was performed to form a plurality of liquid supply ports 5 penetrating the substrate (liquid supply port forming step).
Each liquid supply port 5 was formed so as to extend in the first direction (direction perpendicular to the paper surface). The (average) volume of each liquid supply port 5 was 2.28 mm ³ , and the opening width of the liquid supply port 5 on the second surface side in the second direction was 360 μm. As shown in FIG. 5-1 (d), the formed liquid supply port had the minimum opening width on the first surface side, and the opening width on the first surface side was 120 μm. Subsequently, as shown in FIG. 5-1 (e), the unnecessary mask material 15 was removed by immersing it in a special removing liquid (xylene) for a predetermined time.

Next, as shown in FIG. 5-1 (f), a peelable tape 13 having a two-layer structure of a base material (PET) 13b and an adhesive layer (acrylic) 13a on the first surface 6a of the substrate 6. Was pasted (coating process). Since this tape 13 is peeled off after the drying step of the PVA aqueous solution, a UV peeling type tape whose adhesive strength is lowered by ultraviolet irradiation was selected.

Subsequently, as shown in FIGS. 5-1 (g) and 5-1 (h), a dispense nozzle 17 having an inner diameter φ (diameter) of 70 μm, which is narrower than the width of the liquid supply port 5, is inserted into the liquid supply port and inside the liquid supply port. Was injected with an aqueous PVA solution. At that time, the distance between the opening on the first surface side of the liquid supply port and the tip of the dispense nozzle was set to 40 μm, and the PVA aqueous solution was injected. In Example 1, 0.47 mg of a PVA aqueous solution was injected into a volume of 2.28 mm ³ of each liquid supply port to obtain a filling amount of 12% with respect to the volume of the liquid supply port. Further, as the PVA aqueous solution, the PVA aqueous solution shown in Table 1 prepared by the following method was used. Specifically, PVA having a saponification degree of 80 mol% and a degree of polymerization of 250 (trade name: JMR-10H (manufactured by Japan Vam & Poval) is mixed with water at a PVA concentration of 30% by mass, and heated and dissolved at 90 ° C. An aqueous PVA solution having a viscosity at 23 ° C. of 0.5 Pa · s was prepared. As shown in the evaluation results described later, no precipitates are generated in this aqueous PVA solution at room temperature. As shown in FIG. 8A, even if the PVA aqueous solution is continuously discharged into the liquid supply port, the dispense nozzle 17 is not clogged due to PVA precipitation, and the PVA aqueous solution is stably discharged from the start to the end of the injection. It was possible.

Next, as shown in FIG. 5-2 (i), the substrate into which the PVA aqueous solution was injected into the liquid supply port was dried using a hot plate at a temperature of 120 ° C. and a drying time of 300 seconds, and was desired. A PVA layer 12 was formed at the position. The PVA layer 12 was uniformly dried on the wafer surface, and no chipping or uneven drying occurred (drying step). The thickness of the PVA layer near the center of the liquid supply port in the second direction described above was 25.0 μm. As described above, in Example 1, the PVA layer could be stably formed at a desired position of the liquid supply port.

Next, as shown in FIG. 5-2 (j), after irradiating the tape with ultraviolet rays of 200 mJ in a nitrogen atmosphere, the tape was peeled off from the first surface 6a of the substrate (tape removing step). ..

Subsequently, as shown in FIG. 5-2 (k), a mold material 18 for forming a flow path is placed on the first surface 6a of the substrate by using a photosensitive material (trade name: ODUR1010A, manufactured by Tokyo Ohka). , Formed by photolithography technology. The PVA layer 12 formed so as to close the opening on the first surface side of the liquid supply port 5 prevented the mold material 18 from dripping into the liquid supply port. Further, although an organic solvent (trade name: MP5050, manufactured by Hayashi Junyaku Kogyo Co., Ltd.) was used as a developing solution when forming the mold material 18, the PVA layer 12 has solvent resistance as shown in the evaluation results described later. However, the PVA layer did not dissolve in this organic solvent.

Next, as shown in FIG. 5-2 (l), a nozzle layer forming material (trade name: CR2.0, manufactured by ADEKA CORPORATION) 19 was applied onto the mold material 18 to an arbitrary thickness. Subsequently, as shown in FIG. 5-2 (m), exposure development was performed by a photolithography technique to form a discharge port 3. Then, as shown in FIG. 5-2 (n), the unnecessary PVA layer 12 was immersed in water for a predetermined time (60 minutes) to remove it, and the obtained substrate was dried (PVA layer). Removal process).

Subsequently, as shown in FIG. 5-2 (o), the obtained substrate was immersed in a special removing liquid (trade name: Lucclean) for a predetermined time to remove the unnecessary mold material 18 (nozzle layer). Formation process). As shown in FIG. 6A, the produced PVA layer was not dissolved in the organic solvent contained in the material used for forming the nozzle layer until it was removed by the PVA layer removing step. Subsequently, a support member was attached to the obtained substrate to obtain a liquid discharge head. In the obtained liquid discharge head, chip shrink can be achieved without narrowing the width of the liquid supply port wall.

Here, using the substrate obtained during the manufacturing process of Example 1, the solvent resistance of the PVA layer, the mechanical strength due to uneven drying, and the precipitation and filling property of the PVA aqueous solution at room temperature (23 ° C.) 4 One item was evaluated by the following method. The evaluation results are shown in Table 1. In addition, Table 1 below shows the above-mentioned four parameters that are important in determining the properties of the PVA aqueous solution.

-Solvent resistance The substrate on which the PVA layer was formed in the liquid supply port obtained from the above drying step was immersed in a solvent (trade name: MP5050, manufactured by Hayashi Junyaku Kogyo Co., Ltd.) for 15 minutes. Then, it was visually confirmed whether the PVA layer was dissolved in the solvent, and the solvent resistance of the PVA layer was evaluated based on the following evaluation criteria.
Evaluation Criteria ◯: No change was observed in the PVA layer before and after immersion, and dissolution of the PVA layer in the solvent was not confirmed.
Δ: The surface of the PVA layer was soggy after immersion, but dissolution of the PVA layer in the solvent was not confirmed.
X: The thickness of the PVA layer changed before and after immersion, and it was confirmed that the PVA layer was dissolved in the solvent.

-Mechanical strength due to uneven drying When the tape attached on the PVA layer was peeled off in the above tape removal step, the PVA layer after the tape was peeled off was observed, and the PVA layer was dried based on the following evaluation criteria. The mechanical strength caused by unevenness was evaluated.
Evaluation Criteria ◯: The PVA layer was not torn when the tape was peeled off.
Δ: When the tape was peeled off, the PVA layer was not torn, but a change (elongation) was observed in the shape of the PVA layer.
X: The PVA layer was torn when the tape was peeled off.

・ Precipitation at room temperature (nozzle clogging)
The PVA aqueous solution used for forming the PVA layer was stored in a glass container at room temperature (23 ° C.) for 3 weeks. Then, it was visually confirmed whether or not there was a precipitate in the PVA aqueous solution, and the precipitation of the PVA aqueous solution at room temperature was evaluated based on the following evaluation criteria.
Evaluation Criteria ◯: No precipitate was confirmed in the PVA aqueous solution after long-term storage.
X: After long-term storage, precipitates were confirmed in the PVA aqueous solution.

-Fillability After the tape removal step, the substrate on which the PVA layer was formed in the liquid supply port was observed with a metallurgical microscope, and the fillability of the PVA layer was evaluated based on the following evaluation criteria.
Evaluation Criteria ◯: No tearing of the PVA layer was observed, and the PVA layer was filled in the liquid supply port without any gaps.
Δ: No tearing of the PVA layer was observed, but bubbles (air bubbles) were mixed in the PVA layer.
X: Gap, holes, and tears were found in the PVA layer.

[Examples 2 and 3, Comparative Examples 1 and 2]
A liquid discharge head was prepared in the same manner as in Example 1 except that the PVA aqueous solution to be injected into the liquid supply port was changed to the PVA aqueous solution shown in Table 1 below, and the evaluation was performed in the same manner as in Example 1. It was. In these examples, the filling amount was appropriately changed so that the thickness of the PVA layer near the center of the liquid supply port in the second direction after the drying step was 25.0 μm as in Example 1. Specifically, the filling amount with respect to the volume of the liquid supply port was 12% in Example 2, 17% in Example 3, 12% in Comparative Example 1, and 9% in Comparative Example 2. The evaluation results for each example are shown in Table 1.
The following PVA was used as the PVA aqueous solution used in each example.
Example 2: PVA (trade name: JMR-10M, manufactured by Japan Vam & Poval Co., Ltd., degree of saponification: 50 mol%, degree of polymerization: 250).
Example 3: PVA (trade name: JP-03, manufactured by Japan Vam & Poval Co., Ltd., degree of saponification: 88 mol%, degree of polymerization: 340).
Comparative Example 1: PVA (trade name: JMR-20H, manufactured by Japan Vam & Poval Co., Ltd., degree of saponification: 80 mol%, degree of polymerization: 600).
In Comparative Example 2, the same PVA as in Example 1 was used, and the PVA concentration in the PVA aqueous solution was changed to 40% by mass.

As shown in Table 1, in Examples 1 and 3, a PVA aqueous solution in which the above four parameters were all within the above-mentioned preferable numerical range was used. Therefore, it was possible to easily inject the PVA aqueous solution into the liquid supply port without causing problems such as nozzle clogging while easily maintaining the solvent resistance of the PVA aqueous solution and the removal characteristics with water. As a result, there was no chipping or uneven drying, and a PVA layer having a desired thickness could be easily formed more stably in the liquid supply port.
Further, in Example 2, although the solvent resistance is inferior to that of these Examples, the obtained liquid discharge head can achieve chip shrink without narrowing the width of the liquid supply port wall. It was.
On the other hand, in Comparative Example 1 and Comparative Example 2, air bubbles are mixed into the PVA layer formed in the liquid supply port, uneven drying occurs, and the like, the PVA layer stretches when the tape is peeled off, and the dispense nozzle is clogged. was there.

Next, each example related to the second embodiment of the present invention will be described.
[Example 4]
First, as shown in FIG. 5-1 (a), a silicon substrate is prepared as the substrate 6, and a heater element as an energy generating element (not shown) and this element are protected on the first surface 6a of the substrate. A protective film (insulating film) 9 made of SiN was formed. Further, an aluminum sacrificial layer 14 for determining the size of the liquid supply port on the first surface side was formed on the first surface of the substrate. Then, a thermal oxide film (SiO2) 10 serving as a patterning mask for the liquid supply port was formed on the second surface 6b side of the substrate. These formations used a multi-layer wiring technology using photolithography technology (board preparation process).

Next, as shown in FIG. 5-1 (b), a mask material (trade name: HIMAL, manufactured by Hitachi Chemical) 15 was formed on the first surface of the substrate 6. Then, as shown in FIG. 5-1 (c), a through hole 16 penetrating the mask material 15, the aluminum sacrificial layer 14, and the substrate 6 was formed by using a YAG laser. Specifically, in order to form a one-hole liquid supply port, a 220-Pulse laser was irradiated to form a through hole 16. At this time, the thermal oxide film 10 formed on the second surface of the substrate was patterned by hollowing out an opening for determining the position of the liquid supply port on the second surface side with a laser.

Next, as shown in FIG. 5-1 (d), the substrate on which the through holes 16 were formed was immersed in a TMAH aqueous solution having a concentration of 22% by mass adjusted to 83 ° C. for 6 hours, and the mixture was different. Sexual etching was performed to form a plurality of liquid supply ports 5 penetrating the substrate (liquid supply port forming step).
Each liquid supply port 5 was formed so as to extend in the first direction (direction perpendicular to the paper surface). The (average) volume of each liquid supply port 5 was 2.28 mm ³ , and the opening width of the liquid supply port 5 on the second surface side in the second direction was 360 μm. As shown in FIG. 5-1 (d), the formed liquid supply port had the minimum opening width on the first surface side, and the opening width on the first surface side was 120 μm. Subsequently, as shown in FIG. 5-1 (e), the unnecessary mask material 15 was removed by immersing it in a special removing liquid (xylene) for a predetermined time.

Next, as shown in FIG. 5-1 (f), a peelable tape 13 having a two-layer structure of a base material (PET) 13b and an adhesive layer (acrylic) 13a on the first surface 6a of the substrate 6. Was pasted (coating process). Since this tape 13 is peeled off after the drying step of the PVA aqueous solution, a UV peeling type tape whose adhesive strength is lowered by ultraviolet irradiation was selected.

Subsequently, as shown in FIGS. 5-1 (g) and 5-1 (h), a dispense nozzle 17 having an inner diameter of 70 μm, which is narrower than the width of the liquid supply port 5, is inserted into the liquid supply port to enter the liquid supply port. Was injected with an aqueous PVA solution. At that time, the distance between the opening on the first surface side of the liquid supply port and the tip of the dispense nozzle was set to 40 μm, and the PVA aqueous solution was injected. As the PVA aqueous solution, the same PVA aqueous solution as the PVA aqueous solution used in Example 1 described above was used. In Example 4, 0.47 mg of a PVA aqueous solution was injected into a volume of 2.28 mm ³ of each liquid supply port, and the filling amount was 12% with respect to the volume of the liquid supply port.

Next, as shown in FIG. 5-2 (i), the substrate in which the PVA aqueous solution was injected into the liquid supply port was dried using a hot plate at a temperature of 120 ° C. and a drying time of 300 seconds, and at a desired position. A PVA layer 12 was formed on the surface. The PVA layer 12 was uniformly dried in the wafer surface, and no uneven drying occurred (drying step). The thickness of the PVA layer near the center of the liquid supply port in the second direction described above was 25.0 μm. As described above, in Example 4, the PVA layer could be stably formed at a desired position of the liquid supply port.

Next, as shown in FIG. 5-2 (j), after irradiating the tape with ultraviolet rays of 200 mJ in a nitrogen atmosphere, the tape was peeled off from the first surface 6a of the substrate (tape removing step). .. At this time, the mechanical strength caused by the uneven drying of the PVA layer was evaluated using the evaluation method described above. The evaluation results are shown in Table 2.

Subsequently, as shown in FIG. 5-2 (k), a mold material 18 for forming a flow path is placed on the first surface 6a of the substrate by using a photosensitive material (trade name: ODUR1010A, manufactured by Tokyo Ohka). , Formed by photolithography technology. The PVA layer 12 formed so as to close the opening on the first surface side of the liquid supply port 5 prevented the mold material 18 from dripping into the liquid supply port. Further, an organic solvent (trade name: MP5050, manufactured by Hayashi Junyaku Kogyo Co., Ltd.) was used as a developing solution when forming the mold material 18, but as described above, the PVA layer 12 has solvent resistance, so that the PVA layer is formed. It did not dissolve.

Next, as shown in FIG. 5-2 (l), a nozzle layer forming material (trade name: CR2.0, manufactured by ADEKA CORPORATION) 19 was applied onto the mold material 18 to an arbitrary thickness. Subsequently, as shown in FIG. 5-2 (m), exposure development was performed by a photolithography technique to form a discharge port 3. Then, as shown in FIG. 5-2 (n), the unnecessary PVA layer 12 was immersed in water for a predetermined time (60 minutes) to remove it, and the obtained substrate was dried (PVA layer). Removal process).

Subsequently, as shown in FIG. 5-2 (o), the obtained substrate was immersed in a special removing liquid (trade name: Lucclean) for a predetermined time to remove the unnecessary mold material 18 (nozzle layer). Formation process). Subsequently, a support member was attached to the obtained substrate to obtain a liquid discharge head. In the obtained liquid discharge head, chip shrink can be achieved without narrowing the width of the liquid supply port wall.

[Examples 5 to 7]
A liquid discharge head was produced and evaluated in the same manner as in Example 4 except that the following points were changed. That is, in Examples 5 to 7, the injection amounts of the PVA aqueous solution for the volume of 2.28 mm ³ of each liquid supply port (1 hole) were changed to 0.80 mg, 1.07 mg and 0.70 mg, respectively, and the thickness was 45. PVA layers of 0.0 μm, 60.0 μm and 30.0 μm were formed. The filling amounts of the PVA aqueous solution with respect to the volume of each liquid supply port in Examples 5 to 7 were 21%, 29%, and 15%, respectively. After drying, the obtained PVA layer was not chipped or unevenly dried in any of the examples, and the PVA layer could be stably formed at a desired position in these examples. Therefore, in the obtained liquid discharge head, chip shrink can be achieved without narrowing the width of the liquid supply port wall.

[Comparative Examples 3 to 4]
A liquid discharge head was produced and evaluated in the same manner as in Example 4 except that the following points were changed. That is, in Comparative Examples 3 and 4, the injection amount of the PVA aqueous solution for the volume of 2.28 mm ³ of each liquid supply port was changed to 1.81 mg and 2.43 mg, respectively, and the PVA layers having thicknesses of 100.0 μm and 130.0 μm were changed. Was formed. The filling amounts of the PVA aqueous solution with respect to the volume of the liquid supply port in Comparative Examples 3 and 4 were 49% and 60%, respectively. In these comparative examples, uneven drying occurred unevenly toward the opening side on the second surface side of the liquid supply port, which is the direction in which moisture escapes when the PVA layer is dried. For this reason, the formed PVA layer has a thin film thickness near the center of the liquid supply port and has holes.

The results for each example are shown in Table 2 below. In Examples 4 to 7 and Comparative Examples 3 and 4, even if the PVA aqueous solution is continuously discharged into the liquid supply port, the dispense nozzle is not clogged due to PVA precipitation, and the PVA aqueous solution is stable from the start to the end of the injection. Was able to be discharged.

1 Nozzle layer 2 Element substrate 3 Discharge port 4 Energy generating element 5 Liquid supply port 6 Substrate 6a First surface 6b Second surface 7 Liquid discharge head 11 Filler (PVA aqueous solution)
12 Filler layer (PVA layer)
13 Tape 17 Dispens nozzle

Claims (9)

A nozzle layer having a discharge port for discharging liquid and
An element substrate having an energy generating element for discharging a liquid from the discharge port and a liquid supply port for supplying the liquid to the discharge port.
It is a method of manufacturing a liquid discharge head having
A step of forming the liquid supply port penetrating the first surface of the substrate and the second surface facing the first surface on the substrate on which the energy generating element is arranged on the first surface.
A step of covering the opening on the first surface side of the liquid supply port with tape, and
A dispense nozzle is inserted into the liquid supply port from the second surface side, and a PVA aqueous solution is injected into the liquid supply port from the dispense nozzle to cover at least the opening on the first surface side of the liquid supply port. The PVA layer forming step of forming the PVA layer and
The step of removing the tape and
A step of forming the nozzle layer on the first surface of the substrate on which the PVA layer is formed, and
The step of removing the PVA layer and
Have,
A method for manufacturing a liquid discharge head, which satisfies any one or both of the following conditions (1) and (2):
(1) The PVA concentration of the PVA aqueous solution is 18% by mass or more and 30% by mass or less, and the degree of polymerization of PVA used in the PVA aqueous solution is 200 or more and 400 or less.
(2) The PVA layer is formed so that the liquid supply port extends in the direction of the discharge port row of the liquid discharge head, and is perpendicular to the direction of the discharge port row and parallel to the substrate surface. The thickness of the liquid supply port at the center is 15 μm or more and 60 μm or less. The method for manufacturing a liquid discharge head according to claim 1, which satisfies the condition (1). The method for manufacturing a liquid discharge head according to claim 1 or 2, which satisfies the condition (2). The method for manufacturing a liquid discharge head according to any one of claims 1 to 3, wherein the PVA layer forming step includes a step of drying the PVA aqueous solution injected into the liquid supply port. The liquid discharge according to any one of claims 1 to 4, wherein in the PVA layer forming step, the amount of the PVA aqueous solution injected into the liquid supply port is 50% or less of the volume of the liquid supply port. How to manufacture the head. Claimed that the distance between the tip of the dispense nozzle and the opening on the first surface side of the liquid supply port when the PVA aqueous solution is injected into the liquid supply port is 10 μm or more and 400 μm or less. Item 8. The method for manufacturing a liquid discharge head according to any one of Items 1 to 5. Any of claims 1 to 6, wherein the opening width on the second surface side of the liquid supply port in a direction perpendicular to the direction of the discharge port row and parallel to the substrate surface is 360 μm or more and 730 μm or less. The method for manufacturing a liquid discharge head according to item 1. The method for manufacturing a liquid discharge head according to any one of claims 1 to 7, wherein the viscosity of the PVA aqueous solution at 23 ° C. is 1 Pa · s or less. The method for producing a liquid discharge head according to any one of claims 1 to 8, wherein the degree of saponification of PVA used in the PVA aqueous solution is 80 mol% or more.