KR100477703B1 - Inkjet printhead and manufacturing method thereof - Google Patents

Abstract

An inkjet printhead and a method of manufacturing the same are disclosed. The disclosed inkjet printhead includes an ink flow path for supplying ink from an ink reservoir and a nozzle plate having a plurality of nozzles for discharging supplied ink, the inkjet printhead having a water repellent layer formed on the nozzle plate; The water repellent layer is characterized in that its thickness is 10 to 30 kPa. According to this, it is not necessary to use expensive equipment such as CVD and PVD when forming a water repellent layer on the surface of the nozzle plate. In addition, the water-repellent layer can be formed on the nozzle surface by simple contact printing, and furthermore, by forming a water-repellent coating layer inside the nozzle stage, it prevents ink sticking at the nozzle stage and stabilizes the meniscus of the ink to improve print quality. Can be improved.

Description

Inkjet printheads and manufacturing method thereof

The present invention relates to a method of manufacturing an inkjet printhead, and more particularly, to an inkjet printhead and a method of manufacturing a water repellent layer thin film formed on the surface of a nozzle plate.

In general, an inkjet printhead is an apparatus for ejecting a small droplet of printing ink to a desired position on a recording sheet to print an image of a predetermined color. In such an inkjet printhead, ink is supplied from an ink reservoir into an ink chamber via an ink feed hole and a restrictor. Ink filled in the ink chamber is heated by a heating element provided therein, and is discharged in the form of droplets through the nozzle by the pressure of the bubble generated thereby.

On the other hand, if the surface of the nozzle plate has hydrophilicity when the ink is discharged through the nozzle, the influence of the droplet state or the meniscus action of the ink inside the nozzle collects the ink around the nozzle. To be. In other words, the nozzle of the nozzle plate is wetted. Ink locally accumulated around the nozzle distorts the ejection direction of the ink, and also reduces the ejection speed of the ink. Therefore, the ink cannot be brought into contact with the desired position on the recording paper, resulting in poor print performance. This wetting phenomenon is closely related to the physical properties of the ink, that is, the surface tension of the ink, but more directly related to the hydrophobicity of the nozzle plate. In recent years, the trend of inkjet printers is to prevent the deterioration of image quality due to the discharge direction distortion and the speed reduction due to wetting in order to realize high resolution and high image quality such as photographs.

Conventionally, in order to solve the problem mentioned above, the process of forming the water-repellent layer of several micrometers thickness in the surface of a nozzle plate is employ | adopted. That is, the Ni-PTFE film was plated to a thickness of several μm by Ni electroplating containing poly tetrafluoro ethylene (PTFE) on the surface of the nozzle plate made of stainless steel. Heat treatment at 300-330 ° C., which is the melting temperature of PTFE, allowed PTFE to be uniformly applied to the entire surface of the Ni-PTFE film to form a water repellent coating layer.

On the other hand, the nickel plating bath used for Ni electroplating contains nickel sulfa PTFE particles, sulfamic acid, boric acid, various additives, and water. The deposition thickness of PTFE is controlled by controlling the total current density and plating time applied to the plating bath.

However, it is very difficult to manage the plating solution and to manage the process conditions for Ni electroplating, and the yield of the water-repellent coated nozzle plate is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and in particular, provides a inkjet printhead and a manufacturing method for forming a stable water repellent coating layer using a contact printing method when the nozzle plate forms a water repellent layer on its surface. There is a purpose.

In order to achieve the above technical problem, the present invention includes a nozzle plate formed with an ink flow path for supplying ink from an ink reservoir and a plurality of nozzles for discharging the supplied ink, and a water repellent layer is formed on the nozzle plate. For inkjet printheads:

The water repellent layer is to provide an inkjet printhead, the thickness of which is 10 to 30 kPa.

It is preferable that the said water repellent layer is an organic silane absorber, and is a low molecular weight substance with a molecular weight of 500 or less.

The organosilane absorber is a compound represented by the following formula,

R1 is any one of chlororines, ethoxy, and methoxy,

R2 is preferably any one of CF3CF2-, CF3CH2-, CH3- and CH2 = CH-.

In addition, it is preferable that the water repellent layer coating is further formed at a predetermined depth from the surface of the nozzle plate at the nozzle end.

The nozzle plate may be made of at least one of the group consisting of epoxy, polyimide, and polyacrylate, or may be made of a metal material, and the surface of the nozzle plate may be plasma oxidized.

In order to achieve the above technical problem, the present invention includes a nozzle plate formed with an ink flow path for supplying ink from an ink reservoir and a plurality of nozzles for discharging the supplied ink, and a water repellent layer is formed on the nozzle plate. In a method of making an inkjet printhead:

Heating the ink to a predetermined portion of the surface of the substrate to form a heating element for generating bubbles;

Applying a positive photoresist to a predetermined thickness on the substrate on which the heating element is formed;

Patterning and forming a portion forming an ink chamber and a restrictor of the ink flow path;

Forming a negative photoresist overlying the patterned positive photoresist on the substrate;

An exposure step of curing the negative photoresist using a photomask provided with a pattern of the nozzle; And

Dissolving and removing the uncured portion of the negative photoresist using a solvent in the exposing step to form a nozzle;

Dissolving and removing the positive photoresist using a solvent to form the ink chamber and the restrictor; And

And forming a water repellent layer having a thickness of 10 to 30 mm on the surface of the nozzle plate on which the nozzles are formed.

After the negative photoresist forming step, the substrate is etched to form an ink supply port.

The water repellent layer forming step,

Preferably, the step of contact printing on the surface of the nozzle plate by moistening the organosilane absorber on the surface of the sheet.

In order to achieve the above technical problem, the present invention includes a nozzle plate formed with an ink flow path for supplying ink from an ink reservoir and a plurality of nozzles for discharging the supplied ink, and a water repellent layer is formed on the nozzle plate. In a method of making an inkjet printhead:

Preparing a nozzle plate having a plurality of nozzles formed by micro-punching or electroforming the plate;

Plasma oxidation the surface of the nozzle plate; And forming a water repellent layer having a thickness of 10 to 30 mm on the surface of the nozzle plate on which the nozzles are formed.

The nozzle plate is made of a metal material,

The water repellent layer forming step,

Preferably, the step of contact printing on the surface of the nozzle plate by moistening the organosilane absorber on the surface of the sheet.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the examples exemplified below are not intended to limit the scope of the present invention, but are provided to fully explain the present invention to those skilled in the art. In the drawings, like reference numerals refer to like elements, and the size of each element may be exaggerated for clarity and convenience of description. In addition, when one layer is described as being on top of a substrate or another layer, the layer may be present over and in direct contact with the substrate or another layer, with a third layer in between.

1A to 1H are cross-sectional views showing respective steps of a method of manufacturing an inkjet printhead according to the present invention.

The photolithography process is basically used in the method of the present invention, and unlike the prior art, the nickel electroplating process is not employed.

First, as shown in FIG. 1A, the ink is heated on the head chip substrate 110 to form a heating element 112 for generating bubbles.

Here, the substrate 110 uses a silicon substrate. This is because silicon wafers widely used in the manufacture of semiconductor devices can be used as they are and are effective for mass production.

In addition, the heating element 112 may be formed by sputtering a metal, such as a tantalum-aluminum alloy, on the substrate 110 as a resistive heating element to a thickness of 300-1200 kPa and then patterning it. The sputtered thin film is patterned by a photo process using a photomask and a photoresist and an etching process by etching the photoresist pattern as an etching mask.

FIG. 1B shows an ink chamber and a rectifier by applying a thick film positive photoresist 120 having a thickness of several tens of micrometers on a head chip substrate 110 having a heating element 112 made of a resistive heating element and exposing with a mask. The developed part is shown with the flow path remaining.

The positive photoresist 120 may satisfy the various dimensions because the height of the ink chamber (124 of FIG. 1E) and the size of the restrictor (126 of FIG. 1E) may cover the amount of droplets according to the resolution. It may be applied to a thickness of about 10 to 100㎛.

FIG. 1C illustrates a state where the negative photoresist 130 is applied to the head chip substrate 110 to cover the thick film positive photoresist 120 of the portion to be a flow path. As the negative photoresist 130, an epoxy, polyimide, or polyacrylate photoresist resin may be used. For example, the SU-8 of Microchem, the polyimide photoresist of DuPont, or the negative dry film resist of TOK, JSR are negative photoresist 130 Can be used as

The negative photoresist 130 changes from low molecular weight to high molecular weight when exposed, and has a property that the polymer chain is cured by forming a network strusture. In addition, by adjusting the exposure amount, it is possible to control the crosslinking density of the network structure and the depth of the crosslinked layer. This cured portion exhibits chemical resistance and high mechanical strength. In addition, the uncured portion of the negative photoresist 130 is present in a low molecular weight, such as a monomer or oligomer, such a portion is a solvent, acetone, a solvent containing a halogen element, Easily dissolved by alkaline solvents.

Then, using the properties of the negative photoresist 130 as described above, as shown in Figure 1d, the first photomask for protecting the negative photoresist 130, the site where the nozzle (122 of Figure 1e) is to be formed And selectively exposed using 131. At this time, the exposed part is overexposed at a dose of about thousands mJ / cm 2, preferably about 1000 to 4000 mJ / cm 2. As a result, the over-exposed portion is changed into a polymer having a high crosslinking degree and cured to have chemical resistance and high mechanical strength. The portion cured by the overexposure thus forms sidewalls of the flow path forming wall 120a and the nozzle 122 surrounding the ink chamber 124 of FIG. 1E and the restrictor 126 of FIG. 1E.

Next, as shown in FIG. 1E, the negative photoresist 130 is sequentially formed by using a solvent in which the negative photoresist 130 and the positive photoresist 120 are dissolved, respectively, as shown in FIG. 1E. ) And the positive photoresist 120 are dissolved and removed. Thereby, the nozzle 122 surrounded by the flow path forming wall 120a, the ink chamber 124, and the restrictor 126 are formed. The restrictor 126 is generally well known as a flow path for supplying ink to the ink chamber 124 from the ink supply port (114 in FIG. 1H) described later, and thus detailed drawings are omitted.

Subsequently, as shown in FIGS. 1F and 1G, the wet sheet 140 is contact printed on the surface of the nozzle plate 127 by immersing in the organic silane absorbent solution. Finally, when the organosilane absorbent solution is dried, a water repellent layer 141 is formed on the nozzle plate 127.

FIG. 2 is an enlarged view of a portion A of FIG. 1G. FIG. Referring to FIG. 2, it is shown that the organic silane absorbent solution of the sheet 140 penetrates to a part of the inner surface of the nozzle 122 during contact printing. Meniscus movement of the ink becomes unstable when the entire water repellent coating layer is formed inside the nozzle 122, but when only the inner end is water-repelled, as shown in FIG. 2, ink accumulation at the nozzle end can be largely prevented. Meniscus movements also become very stable.

The organosilane absorbent used here is a low molecular weight unit compound whose molecular weight is 500 or less. When the compound encounters a hydroxyl group (OH), as shown in FIG. 3, the hydroxyl group and the terminal group R ₁ of the silane undergo a chemical reaction, thereby forming a semi-crystalline structure. to form a structure. Because of this property, it is also called a self-assembled monolayer. At this time, the bonding with the surface of the nozzle plate 127 is made by chemical covalent bonding, not physical bonding. That is, the adhesion between the resulting thin film 141 and the surface of the nozzle plate 127 is strong. The thickness of the film 127 to be formed is about 10-30 mm 3, which is an ultra thin film.

The organosilane absorbent solution is prepared by dissolving the organosilane absorbent in a cosolvent composed of alcohol, acetic acid, toluene and nucleic acid in an amount of 0.01-2% by mass. The silane absorbent showing water repellency is a fluorosilanes family.

3 shows the molecular structure of the organosilane absorbent. The molecular structure of organosilane absorbers typically consists of straight-chain alkanes. R1 is preferably composed of any one of chlororines, ethoxy, or methoxy. The functional molecule of this terminal R1 covalently bonds to the surface with hydroxyl (OH) groups to crystallize to form a stable thin film on the surface. The negative photoresist 130 forming the nozzle plate 127 is a thermosetting polymer, and since the main component is epoxy-based, it absorbs water vapor on the surface and contains a large amount of hydroxyl (OH) groups. It also tends to become more hydrophilic as it is left to stand, ie time after product completion.

On the other hand, an epoxy-based material is not used as the nozzle plate, and when the hydroxyl (OH) group is insufficient on the surface, the surface may be exposed to a plasma oxidation treatment or a humid environment to generate hydroxyl groups. It may be.

The other terminal group R2 may be composed of any one of methyl fluorine, methyl and vinyl groups CF3CF2-, CF3CH2-, CH3- and CH2 = CH-, and the terminal group may be selected according to the required degree of water repellency.

Subsequently, as shown in FIG. 1H, the ink supply port 114 is formed by etching the back surface of the substrate 110. Specifically, an ink supply port 114 is formed when an etching mask defining an area to be etched is formed on the back surface of the substrate 110 and the area is wet or dry etched. At this time, when wet etching using TMAH (Tetramethyl Ammonium Hydroxide) as an etchant, as shown in FIG. 1H, a predetermined angle inclined ink supply port 114 may be formed.

In the above embodiment, a monolithic inkjet printhead in which a nozzle plate is formed on a silicon substrate and a water repellent layer is formed thereon, but the hybrid inkjet printhead in which the nozzle plate is bonded to a substrate having a flow path is also described. The water repellent layer can be formed by contact printing.

That is, a nozzle plate in which a nozzle plate made of a metal material such as gold, nickel or silver is formed by a micropuncher or electro-forming the metal material is prepared. The surface of the nozzle plate is exposed to a plasma oxidation treatment or a humid environment to generate hydroxyl groups on the surface of the nozzle plate. Subsequently, as described above, an organic silane absorber is contact printed on the nozzle plate to form a water repellent layer of a thin film having a thickness of 10 to 30 mm 3. Hereinafter, the process of joining the substrate on which the flow path is formed is possible because the process similar to the process of forming on the substrate described above is omitted.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and equivalent other embodiments are possible. For example, although the manufacturing method of the present invention is shown and described as being applied to an inkjet printhead of an upward ejection method, the basic technical concept may be applied to an inkjet printhead of another ejection method, and furthermore, The pressure generated by the MEMS sensor and the actuator used may also be applied to a device for controlling the flow of fluid.

In addition, in the present invention, a material used to construct each element of the printhead may use a material which is not illustrated. That is, the substrate may be replaced with another material having good processability even if it is not necessarily silicon.

In addition, the order of each step of the inkjet printhead manufacturing method of the present invention may be different from that illustrated. For example, etching of the substrate for forming the ink supply port may be performed not only at the step shown in FIG. 1H but also at the step shown in FIG. 1C as described above.

In addition, the specific values exemplified in each step may be adjusted outside the exemplified ranges as long as the manufactured inkjet printhead can operate normally.

As described above, the inkjet printhead according to the present invention does not need to use expensive equipment such as CVD and PVD when forming a water repellent layer on the surface of the nozzle plate. In addition, by forming a water-repellent coating layer inside the nozzle stage by simple contact printing, ink sticking at the nozzle stage can be prevented and meniscus of the ink can be stabilized to improve print quality.

1A to 1H are cross-sectional views illustrating a method of manufacturing an inkjet printhead according to a preferred embodiment of the present invention.

FIG. 2 is an enlarged view of portion A of FIG. 1G.

3 is a chemical formula showing the chemical bonds of the water repellent layer of the present invention.

<Explanation of symbols for the main parts of the drawings>

110 ... head chip substrate 112 ... heating element

114 Ink supply port 120 Positive photoresist

120a ... Euro-forming wall 122 ... Nozzle

124 ... ink chamber 126 ... restrictor

127: nozzle plate 130 negative photoresist

131 Photomask 140: Sheet

141: water repellent layer

Claims (21)

An inkjet printhead having an ink flow path for supplying ink from an ink reservoir and a nozzle plate having a plurality of nozzles for discharging supplied ink, wherein a water repellent layer is formed on the nozzle plate: The water repellent layer, An inkjet printhead, the thickness of which is 10 to 30 microseconds. The method of claim 1, The water repellent layer, An inkjet printhead, characterized in that the organosilane absorber. The method of claim 2, The organosilane absorber, An inkjet printhead, wherein the molecular weight is a low molecular weight material of 500 or less. The method of claim 2, The organosilane absorber, Compound represented by the following formula, R1 is any one of chlororines, ethoxy, and methoxy, R2 is any one of CF3CF2-, CF3CH2-, CH3- and CH2 = CH-. The method of claim 1, And the water repellent layer coating is formed at the nozzle end in a predetermined depth from the surface of the nozzle plate. The method of claim 1, The nozzle plate is an inkjet printhead, characterized in that made of at least one of the group consisting of epoxy, polyimide and polyacrylate. The method of claim 1, And the nozzle plate is made of a metallic material. The method according to claim 6 or 7, And the surface of the nozzle plate is plasma oxidized. Claims [1] A method of manufacturing an inkjet printhead comprising: an ink flow path for supplying ink from an ink reservoir; and a nozzle plate having a plurality of nozzles for ejecting the supplied ink, wherein a water repellent layer is formed on the nozzle plate: Heating the ink to a predetermined portion of the surface of the substrate to form a heating element for generating bubbles; Applying a positive photoresist to a predetermined thickness on the substrate on which the heating element is formed; Patterning and forming a portion forming an ink chamber and a restrictor of the ink flow path; Forming a negative photoresist overlying the patterned positive photoresist on the substrate; An exposure step of curing the negative photoresist using a photomask provided with a pattern of the nozzle; And Dissolving and removing the uncured portion of the negative photoresist using a solvent in the exposing step to form a nozzle; Dissolving and removing the positive photoresist using a solvent to form the ink chamber and the restrictor; And Forming a water-repellent layer having a thickness of 10 to 30 mm 3 on a surface of the nozzle plate on which the nozzles are formed. The method of claim 9, And forming the ink supply hole by etching the substrate after the negative photoresist forming step. The method of claim 10, And forming the ink supply hole by etching the substrate after the water repellent layer forming step. The method of claim 9, The substrate is a method of manufacturing an inkjet printhead, characterized in that the silicon wafer. The method of claim 9, In the heating element forming step, the heating element is formed by sputtering a metal, which is a resistive heating element, on the substrate. The method of claim 9, The water repellent layer forming step, And wet-printing the organic silane absorbent material on the surface of the sheet and contact printing the surface of the nozzle plate. The method of claim 14, The organosilane absorber, An inkjet printhead manufacturing method according to claim 1, wherein the molecular weight is 500 or less. The method of claim 13, The organosilane absorber, Compound represented by the following formula, R1 is any one of chlororines, ethoxy, and methoxy, R2 is any one of CF3CF2-, CF3CH2-, CH3- and CH2 = CH-. The method of claim 13, And the water repellent layer coating is formed at the nozzle end in a predetermined depth from the surface of the nozzle plate. The method of claim 13, The negative photoresist is an inkjet printhead, characterized in that made of at least one selected from the group consisting of epoxy-based, polyimide-based and polyacrylate-based. Claims [1] A method of manufacturing an inkjet printhead comprising: an ink flow path for supplying ink from an ink reservoir; and a nozzle plate having a plurality of nozzles for ejecting the supplied ink, wherein a water repellent layer is formed on the nozzle plate: Preparing a nozzle plate having a plurality of nozzles formed by micro-punching or electroforming the plate; Plasma oxidation the surface of the nozzle plate; And Forming a water-repellent layer having a thickness of 10 to 30 mm 3 on a surface of the nozzle plate on which the nozzles are formed. The method of claim 19, And the nozzle plate is made of a metal material. The method of claim 19, The water repellent layer forming step, And wet-printing the organic silane absorbent material on the surface of the sheet and contact printing the surface of the nozzle plate.