Patent Application
20060290743
1. Field of the Invention
The present invention relates to an ink-jet printhead. More particularly, the present invention relates to a thermally driven, monolithic, ink-jet printhead having a nozzle plate that is formed integrally with a substrate and a hydrophobic coating layer formed on a surface of the nozzle plate, and a method for manufacturing the same.
2. Description of the Related Art
In general, ink-jet printheads are devices for printing a predetermined image, color or black, by ejecting a small volume ink droplet of a printing ink at a desired position on a recording sheet. Ink-jet printheads are largely classified into two types depending on the ink droplet ejection mechanisms: a thermally driven ink-jet printhead, in which a heat source is employed to form and expand a bubble in ink thereby causing an ink droplet to be ejected, and a piezoelectrically driven ink-jet printhead, in which a piezoelectric crystal bends to exert pressure on ink, thereby causing an ink droplet to be expelled.
An ink droplet ejection mechanism of the thermally driven ink-jet printhead will now be described in detail. When a pulse current flows through a heater formed of a resistive heating material, heat is generated by the heater to rapidly heat ink near the heater to approximately 300° C. Accordingly, the ink boils and bubbles are formed in the ink. The formed bubbles expand and exert pressure on the ink contained within an ink chamber. This causes a droplet of ink to be ejected through a nozzle from the ink chamber.
The thermally driven ink-jet printhead may be further subdivided into top-shooting, side-shooting, and back-shooting types depending on the direction of ink droplet ejection and the direction in which a bubble expands. The top-shooting type refers to a mechanism in which an ink droplet is ejected in a direction that is the same as a direction in which a bubble expands. The back-shooting type is a mechanism in which an ink droplet is ejected in a direction opposite to the direction in which the bubble expands. In the side-shooting type, the direction of ink droplet ejection is perpendicular to the direction in which the bubble expands.
Thermally driven ink-jet printheads need to meet the following conditions. First, a simple manufacturing process, low manufacturing cost, and mass production must be provided. Second, to produce high quality color images, a distance between adjacent nozzles must be as small as possible while still preventing cross-talk between the adjacent nozzles. More specifically, to increase the number of dots per inch (DPI), many nozzles must be arranged within a small area. Third, for high-speed printing, a cycle beginning with ink ejection and ending with ink refill must be as short as possible. That is, the heated ink and heater should cool down quickly to increase an operating frequency. Fourth, heat load exerted on the printhead due to heat generated by the heater must be small, and the printhead must operate stably under a high operating frequency.
Referring to
The process of manufacturing a conventional top-shooting type ink-jet printhead configured as above involves separately manufacturing the nozzle plate 18, which includes the nozzle 16 and the substrate 10, which includes the ink chamber 26 and the ink channel 24, and bonding them together. The manufacturing process is complicated and misalignment may occur during the bonding of the nozzle plate 18 and the substrate 10. Furthermore, since the ink chamber 26, the ink channel 24, and the manifold 22 are arranged on a same plane, there is a restriction on increasing the number of nozzles 16 per unit area, i.e., the density of nozzles 16. This restriction makes it difficult to implement a high printing speed, high-resolution ink-jet printhead.
Recently, in an effort to overcome the above problems of conventional ink-jet printheads, ink-jet printheads having a variety of structures have been proposed.
Referring to
The nozzle plate 40 has a nozzle 47 formed at a location corresponding to a central portion of the ink chamber 32. A heater 45 connected to a conductor 46 is disposed around the nozzle 47. A nozzle guide 44 extends along an edge of the nozzle 47 toward a depth direction of the ink chamber 32. Heat generated by the heater 45 is transferred through an insulating layer, which is the lowermost passivation layer 41, to ink 48 within the ink chamber 32. The ink 48 then boils to form bubbles 49. The formed bubbles 49 expand to exert pressure on the ink 48 contained within the ink chamber 32, thereby causing an ink droplet 48′ to be ejected through the nozzle 47. Then, the ink 48 flows through the ink channel 34 from the manifold 36 due to surface tension of the ink 48 contacting the air to refill the ink chamber 32.
A conventional monolithic ink-jet printhead configured as above has an advantage in that the silicon substrate 30 is formed integrally with the nozzle plate 40 thereby simplifying the manufacturing process and eliminating the chance of misalignment. Another advantage is that the nozzle 46, the ink chamber 32, the ink channel 34, and the manifold 36 are arranged vertically to increase the density of nozzles 46, as compared with the conventional ink-jet printhead shown in
In a conventional ink-jet printhead, since ink is ejected as an ink droplet, the ink must be ejected in a discrete ink droplet form to provide acceptable printing performance. In an ink-jet printhead, a size, a shape, and a surface property of the nozzle greatly affect a size of the ejected ink droplet, a stability of the ink droplet ejection, and an ejection speed of the ink droplet. In particular, the surface property of the nozzle plate greatly affects the characteristic of the ink ejection.
In the ink-jet printhead shown in
In the ink-jet printhead shown in
It is a feature of an embodiment of the present invention to provide a monolithic ink-jet printhead having a nozzle plate, which includes a thick metal layer, that is formed integrally with a substrate and a hydrophobic coating layer that is formed exclusively on an outer surface of the metal layer of the nozzle plate, thereby increasing the directionality of ink ejection and the ejection performance.
It is another feature of an embodiment of the present invention to provide a method for manufacturing the monolithic ink-jet printhead.
According to a feature of the present invention, there is provided a monolithic ink-jet printhead including a substrate having an ink chamber to be supplied with ink to be ejected, a manifold for supplying ink to the ink chamber, and an ink channel for providing communication between the ink chamber and the manifold, a nozzle plate including a plurality of passivation layers sequentially stacked on the substrate, a metal layer formed on the plurality of passivation layers, and a nozzle, through which ink is ejected from the ink chamber, that penetrates the nozzle plate, a heater provided between adjacent passivation layers of the plurality of passivation layers, the heater being located above the ink chamber for heating ink within the ink chamber, a conductor provided between adjacent passivation layers of the plurality of passivation layers, the conductor being electrically connected to the heater for applying a current to the heater, and a hydrophobic coating layer formed exclusively on an outer surface of the metal layer.
Preferably, the hydrophobic coating layer is made of a material having appropriate chemical resistance and abrasion resistance. Preferably, the hydrophobic coating layer is made of at least one material selected from the group consisting of a fluorine-containing compound and a metal. Preferably, the fluorine-containing compound is selected from the group consisting of polytetrafluoroethylene (PTFE) and fluorocarbon. Preferably, the metal is gold (Au).
Preferably, the metal layer is made of a material selected from the group consisting of nickel (Ni) and copper (Cu) and is formed by electroplating to a thickness of about 30-100 μm.
Preferably, the nozzle includes a lower nozzle formed through the plurality of passivation layers, and an upper nozzle formed through the hydrophobic coating layer and the metal layer. Preferably, the upper nozzle has a tapered shape in which a cross-sectional area decreases gradually toward an exit.
Preferably, the nozzle plate further includes a heat conductive layer, which is located above the ink chamber and insulated from the heater and the conductor, the heat conductive layer thermally contacting the substrate and the metal layer. Also preferably, the heat conductive layer is made of any one of a material selected from the group consisting of aluminum, aluminum alloy, gold, and silver.
According to another feature of the present invention, there is provided a method for manufacturing a monolithic ink-jet printhead including preparing a substrate; sequentially stacking a plurality of passivation layers on the substrate and forming a heater and a conductor connected to the heater between adjacent passivation layers of the plurality of passivation layers; forming a lower nozzle by etching to penetrate the plurality of passivation layers; forming a metal layer on the plurality of passivation layers, forming a hydrophobic coating layer exclusively on an outer surface of the metal layer, and forming an upper nozzle in communication with the lower nozzle by etching to penetrate the hydrophobic coating layer and the metal layer and etching an upper surface of the substrate exposed through the upper nozzle and the lower nozzle to form an ink chamber to be supplied with ink; and etching the substrate to form a manifold for supplying ink and an ink channel for providing communication between the ink chamber and the manifold.
Preferably, the substrate is made of a silicon wafer.
The method may further include forming a heat conductive layer which is located above the ink chamber, insulated from the heater and the conductor for thermally contacting the substrate and the metal layer between the passivation layers, during the sequentially stacking of the plurality of passivation layers on the substrate and the formation of the heater and the conductor. The heat conductive layer and the conductor may be simultaneously formed from the same metal. The heat conductive layer may be formed on the insulating layer after forming the insulating layer on the conductor. Preferably, the heat conductive layer is made of any one material selected from the group consisting of aluminum, aluminum alloy, gold, and silver.
Forming the lower nozzle may include dry etching the passivation layers within an area defined by the heater using reactive ion etching (RIE).
Forming the metal layer, forming the hydrophobic coating layer and forming the upper nozzle may include forming a seed layer for electroplating on the plurality of passivation layers, forming a plating mold for forming the upper nozzle on the seed layer, forming the metal layer on the seed layer by electroplating, forming the hydrophobic coating layer exclusively on the outer surface of the metal layer, and removing the plating mold and the seed layer formed under the plating mold. Forming the seed layer may include depositing at least one material selected from the group consisting of titanium and copper on the plurality of passivation layers. The seed layer may include a plurality of metal layers formed by sequentially stacking titanium and copper.
Forming the plating mold may include depositing a layer selected from the group consisting of photoresist and a photosensitive polymer on the seed layer to a predetermined thickness and then patterning the deposited layer in a shape corresponding to a shape of the upper nozzle. Forming the plating mold may further include patterning the deposited layer in a tapered shape, in which a cross-sectional area gradually increases in a downward direction, by a proximity exposure for exposing the deposited layer using a photomask which is installed to be separated from a surface of the deposited layer by a predetermined distance. An inclination of the plating mold may be adjusted by varying a distance between the photomask and the deposited layer and by varying an exposure energy.
The metal layer may be formed of a material selected from the group consisting of nickel and copper to a thickness of about 30-100 μm.
Preferably, the hydrophobic coating layer is made of at least one material selected from the group consisting of a fluorine-containing compound and a metal. Preferably, the fluorine-containing compound includes a material selected from the group consisting of polytetrafluoroethylene (PTFE) and fluorocarbon. Preferably, the metal is gold (Au).
Forming the hydrophobic coating layer may include compositely plating PTFE and nickel on the surface of the metal layer to a thickness of about 0.1 μm to several μm.
Forming the hydrophobic coating layer may include depositing fluorocarbon on the surface of the metal layer using a plasma enhanced chemical vapor deposition (PECVD) process to a thickness of several angstroms to hundreds of angstroms.
Forming the hydrophobic coating layer may include depositing gold on the surface of the metal layer using an evaporator to a thickness of about 0.1-1 μm.
Forming the ink chamber may include isotropically dry etching the substrate exposed through the nozzle. Forming the manifold and the ink chamber comprises etching a lower surface of the substrate to form the manifold, and etching to penetrate the substrate between the manifold and the ink chamber to form the ink channel.
The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail preferred embodiments thereof with reference to the attached drawings in which:
Korean Patent Application No. 2002-77000, filed on Dec. 5, 2002, end entitled: “Monolithic Ink-Jet Printhead and Method for Manufacturing the Same,” is incorporated by reference herein in its entirety.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the invention is shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thickness of layers and regions and the sizes of components may be exaggerated for clarity. It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like elements throughout.
Referring to
A silicon wafer widely used to manufacture integrated circuits (ICs) may be used as the substrate 110. The ink chamber 132 may be formed in a hemispherical shape or another shape having a predetermined depth on an upper surface of the substrate 110. The manifold 136, which is connected to an ink reservoir (not shown) for storing ink, may be formed on a lower surface of the substrate 110 to be positioned under the ink chamber 132. The ink channel 134 is formed between the ink chamber 132 and the manifold 136 to perpendicularly penetrate the substrate 110. The ink channel 134 may be formed in a central portion of a bottom surface of the ink chamber 132, and a horizontal cross-sectional shape is preferably circular. However, the ink channel 134 may have various horizontal cross-sectional shapes such as an oval or a polygonal shape. Further, the ink channel 134 may be formed at any other location that can provide communication between the ink chamber 132 and the manifold 136 by perpendicularly penetrating the substrate 110.
A nozzle plate 120 is formed on an upper surface of the substrate 110 having the ink chamber 132, the ink channel 134, and the manifold 136 formed thereon. The nozzle plate 120, which forms an upper wall of the ink chamber 132, has a nozzle 138, through which ink is ejected, at a location corresponding to a center of the ink chamber 132 by perpendicularly penetrating the nozzle plate 120.
The nozzle plate 120 includes a plurality of material layers stacked on the substrate 110. The plurality of material layers includes first, second, and third passivation layers 121, 122, and 126, a metal layer 128 stacked on the third passivation layer 126 by electroplating, and a hydrophobic coating layer 129 formed exclusively on an outer surface of the metal layer 128. A heater 142 is provided between the first and second passivation layers 121 and 122, and a conductor 144 is provided between the second and third passivation layers 122 and 126. A heat conductive layer 124 may be further provided between the second and third passivation layers 122 and 126.
The first passivation layer 121, the lowermost layer among the plurality of material layers forming the nozzle plate 120, is formed on the upper surface of the substrate 110. The first passivation layer 121 provides electrical insulation between the overlying heater 142 and the underlying substrate 110 and protection of the heater 142. The first passivation layer 121 may be made of silicon oxide or silicon nitride.
The heater 142 overlying the first passivation layer 121 and located above the ink chamber 132 for heating ink contained within the ink chamber 132 is centered around the nozzle 138. The heater 142 consists of a resistive heating material, such as polysilicon doped with impurities, tantalum-aluminum alloy, tantalum nitride, titanium nitride, and tungsten silicide. The heater 142 may have a shape of a circular ring centered around the nozzle 138, as shown in
A second passivation layer 122 for protecting the heater 142 is formed on the first passivation layer 121 and the heater 142. Similarly to the first passivation layer 121, the second passivation layer 122 may be made of silicon nitride or silicon oxide.
The conductor 144 electrically connected to the heater 142 for applying a pulse current to the heater 142 is formed on the second passivation layer 122. A first end of the conductor 144 is connected to the heater 142 through a first contact hole C1 formed in the second passivation layer 122. The conductor 144 may be made of a highly conductive metal, such as aluminum, aluminum alloy, gold, or silver.
The heat conductive layer 124 may be provided above the second passivation layer 122. The heat conductive layer 124 functions to conduct heat from the heater 142 to the substrate 110 and the metal layer 128 which will be described later, and is preferably formed as widely as possible to entirely cover the ink chamber 132 and the heater 142. The heat conductive layer 124 needs to be separated from the conductor 144 by a predetermined distance for insulation purposes. The insulation between the heat conductive layer 124 and the heater 142 can be achieved by interposing the second passivation layer 122 therebetween. Furthermore, the heat conductive layer 124 contacts the upper surface of the substrate 110 through a second contact hole C2 formed by penetrating the first and second passivation layers 121 and 122.
The heat conductive layer 124 is made of a metal having good conductivity. When both the heat conductive layer 124 and the conductor 144 are formed on the second passivation layer 122, the heat conductive layer 124 may be made of the same material as the conductor 144, such as aluminum, aluminum alloy, gold, or silver.
If the heat conductive layer 124 is formed thicker than the conductor 144 or made of a metal different from that of the conductor 144, an insulating layer (not shown) may be interposed between the conductor 144 and the heat conductive layer 124.
The third passivation layer 126 is provided on the conductor 144 and the second passivation layer 122 for providing electrical insulation between the overlying metal layer 128 and the underlying conductor 144 and for protecting of the conductor 144. The third passivation layer 126 may be made of tetraethylorthosilicate (TEOS) oxide or silicon oxide. It is preferable to avoid forming the third passivation layer 126 on an upper surface of the heat conductive layer 124 for contacting the heat conductive layer 124 and the metal layer 128.
The metal layer 128 is made of a metal having a high thermal conductivity, such as nickel or copper. The metal layer 128 is formed to a thickness in a range of about 30-100 μm, preferably, 45 μm or more, by electroplating the metal on the third passivation layer 126. To form the metal layer, a seed layer 127 for electroplating of the metal is provided on the third passivation layer 126. The seed layer 127 may be made of a metal having good electric conductivity and etching selectivity between the metal layer 128 and the seed layer 127, for example, titanium (Ti) or copper (Cu).
The metal layer 128 functions to dissipate the heat from the heater 142. Particularly, since the metal layer 128 is relatively thick due to the plating process, effective heat sinking is achieved. That is, the heat residing in or around the heater 142 after ink ejection is transferred to the substrate 110 and the metal layer 128 via the heat conductive layer 124 and then dissipated. This allows rapid heat dissipation after ink ejection and lowers the temperature around the nozzle 138, thereby providing stable printing at a high operating frequency.
As described above, the hydrophobic coating layer 129 is formed exclusively on the outer surface of the metal layer 128. Thus, the ink can be ejected in discrete ink droplet form due to the hydrophobic coating layer 129, thereby rapidly stabilizing the meniscus formed in the nozzle 138 after ink ejection. Further, the hydrophobic coating layer 129 can prevent the surface of the nozzle plate 120 from being contaminated by the ink or a foreign substance and provide improved directionality of the ink ejection. In the present invention, the hydrophobic coating layer 129 is formed exclusively on the outer surface of the metal layer 128 and is not formed on the inner surface of the nozzle 138. More specifically, the inner surface of the nozzle 138 maintains a hydrophilic property. Thus, the nozzle 138 can be sufficiently filled with the ink and the meniscus can be maintained in the nozzle 138.
Meanwhile, since the surface of the nozzle plate 120 is continuously exposed to the ink and air under a high temperature, the nozzle plate 120 corrodes due to ink and oxidizes due to oxygen in the air. The surface of the nozzle plate 120 is wiped periodically to remove residual ink. Thus, the hydrophobic coating layer 129 is required to have an appropriate chemical resistance to oxidization and corrosion and an appropriate abrasion resistance to friction. Therefore, in the printhead according to the present invention, the hydrophobic coating layer 129 is made of a material having an appropriate chemical resistance and abrasion resistance as well as a hydrophobic property. For example, the hydrophobic coating layer 129 may be formed of at least one of a fluorine-containing compound or a metal. Examples of the fluorine-containing compound preferably include polytetrafluoroethylene (PTFE) or fluorocarbon; an example of the metal preferably includes gold (Au).
As described above, the nozzle 138 is formed in the nozzle plate 120. The cross-sectional shape of the nozzle 138 is preferably circular. Alternately, the nozzle 138 may have other various cross-sectional shapes, such as an oval or a polygonal shape. The nozzle 138 includes a lower nozzle 138a and an upper nozzle 138b. The lower nozzle 138a is formed by perpendicularly penetrating the first, second, and third passivation layers 121, 122, and 126. The upper nozzle 138b is formed by perpendicularly penetrating the hydrophobic coating layer 129 and the metal layer 128. While the lower nozzle 138a has a cylindrical shape, it is preferable that the upper nozzle 138b has a tapered shape, in which a cross-sectional area gradually decreases toward an exit, as shown in
Further, as described above, since the metal layer 128 of the nozzle plate 120 is relatively thick, the length of the nozzle 138 can be sufficiently secured. Thus, stable high-speed printing can be provided and the directionality of an ink droplet that is ejected through the nozzle 138 is improved. More specifically, the ink droplet can be ejected in a direction exactly perpendicular to the substrate 110.
An ink ejection mechanism for the ink-jet printhead according to the preferred embodiment of the present invention, as shown in
Referring to
Referring to
A meniscus in the surface of the ink 150 formed within the nozzle 138 retreats toward the ink chamber 132 after the separation of the ink droplet 150′. In this arrangement, the nozzle 138 is sufficiently long due to the thick nozzle plate 120 so that the meniscus retreats only within the nozzle 138 and not into the ink chamber 132. Thus, this prevents air from flowing into the ink chamber 132 and quickly restores the meniscus to an original state, thereby stably maintaining high speed ejection of the ink droplet 150′. Further, since heat residing in or around the heater 142 after the separation of the ink droplet 150′ passes through the heat conductive layer 124 and the metal layer 128 and is dissipated, either into the substrate 110 or out of the printhead, the temperature in or around the heater 142 and the nozzle 138 drops even more rapidly.
Next, referring to
A method for manufacturing a monolithic ink-jet printhead as presented above according to the preferred embodiment of the present invention, as shown in
Referring to
While
Initially, the first passivation layer 121 is formed on an upper surface of the prepared silicon substrate 110. The first passivation layer 121 may be formed by depositing silicon oxide or silicon nitride on the upper surface of the substrate 110.
Next, the heater 142 is formed on the first passivation layer 121 on the upper surface of the substrate 110. The heater 142 may be formed by depositing a resistive heating material, such as polysilicon doped with impurities, tantalum-aluminum alloy, tantalum nitride, titanium nitride, or tungsten silicide, on the entire surface of the first passivation layer 121 to a predetermined thickness and then patterning the same. Specifically, the polysilicon doped with impurities, such as a phosphorus (P)-containing source gas, may be deposited by low-pressure chemical vapor deposition (LPCVD) to a thickness of about 0.7-1 μm. Tantalum-aluminum alloy, tantalum nitride, titanium nitride, or tungsten suicide may be deposited by sputtering to a thickness of about 0.1-0.3 μm. The deposition thickness of the resistive heating material may be determined in a range other than that given here to have an appropriate resistance considering the width and length of the heater 142. The resistive heating material is deposited on the entire surface of the first passivation layer 121 and then patterned by a photo process using a photomask and a photoresist and an etching process using a photoresist pattern as an etch mask.
Subsequently, as shown in
Alternatively, if the heat conductive layer 124 is to be formed thicker than the conductor 144 or if the heat conductive layer 124 is to be made of a metal different from that of the conductor 144, or to provide further insulation between the conductor 144 and the heat conductive layer 124, the heat conductive layer 124 can be formed after the formation of the conductor 144. More specifically, in the step shown in
Next, as shown in
Next, as shown in
Next, as shown in
During formation of the hydrophobic coating layer 129, the PTFE, fluorocarbon, or gold can be coated on the surface of the metal layer 128 to a predetermined thickness by an appropriate method. For example, when using PTFE, a metaflon process for compositely plating PTFE and nickel (Ni) on the surface of the metal layer 128 to a thickness of about 0.1 μm to several μm can be employed. Meanwhile, in a case of using fluorocarbon, fluorocarbon can be deposited on the surface of the metal layer 128 using a plasma enhanced chemical vapor deposition (PECVD) process to a thickness of several angstroms to hundreds of angstroms. At this time, fluorocarbon is deposited on the plating mold 139 and then the fluorocarbon deposited on the plating mold 139 can be removed together with the plating mold 139 in a subsequent process of removing the plating mold 139, which will be described below. When gold is used, gold can be formed on the surface of the metal layer 128 using an evaporator to a thickness of about 0.1-1 μm.
As described above, in the present invention, since the metal layer 128 and the hydrophobic coating 129 are formed after forming the plating mold 139 in a portion where the nozzle 138 will be formed, the hydrophobic coating 129 is formed exclusively on the outer surface of the metal layer 128 and is not formed inside the nozzle 138.
Subsequently, the plating mold 139 is removed, and then a portion of the seed layer 127 exposed by the removal of the plating mold 139 is removed. The plating mold 139 can be removed using a general photoresist removal method, for example, acetone. The seed layer 127 can be wet-etched using an etching solution, in which only the seed layer 127 can be selectively etched considering the etching selectivity between a material consisting of the metal layer 128 and a material consisting of the seed layer 127. For example, when the seed layer 127 is made of copper (Cu), an acetate base solution can be used as an etching solution, and when the seed layer 127 is made of titanium (Ti), an HF base solution can be used as an etching solution. As a result, as shown in
After having undergone the above steps, the monolithic ink-jet printhead according to the preferred embodiment of the present invention having the structure as shown in
As described above, a monolithic ink-jet printhead and a method for manufacturing the same according to the present invention have the following advantages.
First, since a metal layer and a hydrophobic coating layer are formed after forming a plating mold in a portion where a nozzle will be formed, the hydrophobic coating layer is formed exclusively on an outer surface of the metal layer so that the nozzle has a hydrophobic property. Thus, ink ejection factors such as directionality, size, and ejection speed of an ink droplet are improved, thereby increasing an operating frequency and improving a printing quality. Further, a surface of the printhead can be prevented from being contaminated and can have improved chemical resistance and abrasion resistance.
Second, the thick metal layer can be formed by electroplating so that a heat sinking capability is increased, thereby increasing the ink ejection performance and an operating frequency. Further, a sufficient length of the nozzle can be secured according to the thickness of the metal layer so that a meniscus can be maintained within the nozzle, thereby providing a stable ink refill operation, and improving the directionality of the ink droplet to be ejected.
Third, since a nozzle plate having a nozzle is formed integrally with a substrate having an ink chamber and an ink channel formed thereon, an ink-jet printhead can be manufactured on a single wafer using a single process. This process eliminates the conventional problem of misalignment between the ink chamber and the nozzle.
A preferred embodiment of the present invention has been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. For example, materials used to form the constitutive elements of a printhead according to the present invention may not be limited to those described herein. In addition, the stacking and formation method for each material are only examples, and a variety of deposition and etching techniques may be adopted. Furthermore, specific numeric values illustrated in each step may vary within a range in which the manufactured printhead can operate normally. In addition, a sequence of process steps in a method of manufacturing a printhead according to this invention may vary. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-77000 | Dec 2002 | KR | national |
This is a divisional application based on pending application Ser. No. 10/726,515, filed Dec. 4, 2003, the entire contents of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10726515 | Dec 2003 | US |
| Child | 11512330 | Aug 2006 | US |
