Patent Grant
9205650
1. Field of the Invention
The present invention relates to a liquid ejection head.
2. Description of the Related Art
A liquid ejection head is included in a liquid ejecting apparatus such as an ink jet recording apparatus. A liquid ejection head includes a channel wall member and a substrate. In Japanese Patent Laid-Open No. 2005-205916, a liquid ejection head including a channel wall member formed on a substrate is described.
The channel wall member comprises a resin, in particular, a photosensitive resin. The channel wall member serves as the wall of a channel through which a liquid flows. In some cases, liquid ejection ports are formed in the channel wall member. Generally, the substrate is a silicon substrate composed of silicon. A supply port through which a liquid is supplied is formed in the substrate. Energy generating devices are disposed on the upper surface of the substrate. A liquid is supplied through the liquid supply port into the channel, energized by the energy generating devices, and thereby ejected from the liquid ejection ports onto a record medium such as paper.
Aspects of the present invention provide a liquid ejection head including a substrate and a channel wall member formed on the surface of the substrate, the channel wall member comprising a photosensitive resin. The channel wall member has a first region and a second region that are arranged in a direction parallel to the surface of the substrate. The crosslink density of the first region is lower than that of the second region.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Generally, a substrate and a channel wall member have different coefficients of linear expansion. The difference in coefficients of linear expansion causes a stress in the substrate due to, for example, an environmental change that occurred during the manufacturing process. According to studies conducted by the inventors of the present invention, in the liquid ejection head described in Japanese Patent Laid-Open No. 2005-205916, the channel wall member might be removed from the substrate due to a stress that was applied to the substrate. Furthermore, the shape of liquid ejection ports might be deformed, which affected the direction in which a liquid was ejected. Removal of the channel wall member from the substrate is caused by deformation of the substrate or deformation of the channel wall member.
Accordingly, aspects of the present invention provide a liquid ejection head in which a channel wall member is less likely to be removed from a substrate.
An embodiment of the present invention is described below.
The substrate 1 is composed of, for example, Si, Ge, SiC, GaAs, InAs, GaP, diamond, ZnO that is an oxide semiconductor, InN and GaN that are nitride semiconductors, a mixture of these materials, or an organic semiconductor. Alternatively, the substrate 1 may be a substrate composed of glass, Al2O3, a resin, or a metal on which a circuit including a thin-film transistor or the like is formed. An SOI substrate or the like may also be used as the substrate 1. In particular, the substrate 1 is preferably a silicon substrate composed of Si. A liquid supply port 3 is formed in the substrate 1. In the liquid supply port 3, a beam and a filter for a channel may be disposed.
Energy generating devices 4 and connection terminals (not shown) are formed on the surface 5 of the substrate 1. Examples of an element that can be used as the energy generating devices 4 include a resistance heating element and an electromagnetic heating element that use thermal energy, a piezoelectric element and an ultrasonic element that use mechanical energy, and an element that ejects a liquid using electric energy or magnetic energy. The energy generating devices 4 may be disposed so as to be in contact with the surface of the substrate 1. A part of each energy generating device 4 may be hollow. The energy generating devices 4 may be covered with an insulation layer or a protective layer.
A channel wall member 2, which serves as the wall of a channel through which a liquid flows, is formed on the surface 5 of the substrate 1. The channel wall member 2 comprises a photosensitive resin. Examples of the photosensitive resin includes a negative photosensitive resin and a positive photosensitive resin. In particular, the channel wall member 2 is preferably composed of a negative photosensitive resin. A liquid flow passage 6 and liquid ejection ports 7 are formed in the channel wall member 2.
As shown in
The first region and the second region are arranged in a direction parallel to the surface of the substrate. This reduces the stress applied to the substrate 1 by a sufficient degree. The expression “arranged in a direction parallel to the surface of the substrate” means that both the first region and the second region are present on a plane parallel to the surface of the substrate. It is preferable that a half or more the first region overlaps the second region in a direction perpendicular to the surface of the substrate. The first region and the second region are two regions in the channel wall member each having a uniform crosslink density. Thus, the crosslink density is uniform in the first region. The crosslink density is uniform in the second region. Note that, the first region 8 has a lower crosslink density than the second region 9. As for the expression “the crosslink density is uniform”, when different portions of the same photosensitive material are exposed to light under the same conditions, the crosslink density of each portion is considered to be uniform. Errors such as manufacturing errors are ignored.
In the case where the first region 8 has a lower crosslink density than the second region 9, differences in heat shrinkage, the Young's modulus, hardness, adhesion, tensile stress, and the like between the first region 8 and the second region 9 arise. This may cause a change in the shape of the surface of the channel wall member, that is, the shape of the ejection port-plane in which liquid ejection ports 7 are formed, as shown in
Thus, on the basis of the shape of the surface of the ejection port-plane, formation of the first region 8 and the second region 9 in the channel wall member 2 can be estimated. Even in the case where the shape of the surface of the ejection port-plane is substantially uniform, formation of the first region 8 and the second region 9 on the channel wall member 2 can be estimated by irradiating the ejection port-plane with an electromagnetic wave, a sound wave, or the like that has a different absorption property and a different reflection property with respect to the first region 8 and the second region 9, and then analyzing the response. A method in which the first region 8 and the second region 9 comprise different materials having different colors may also be employed. This method makes it easy to observe the surface of the ejection port-plane. In addition, the colors of the first region 8 and the second region 9 may be used for controlling the alignment, widths, thicknesses, and the like of the first region 8 and the second region 9.
In the case where the first region 8 has a lower crosslink density than the second region 9, one or more properties of the Young's modulus, hardness, adhesion, and tensile stress of the first region 8 is likely to be lower than those of the second region 9. The Young's modulus is the ratio of stress to strain. The smaller the Young's modulus, the smaller the stress. The Young's modulus of the first region 8 is preferably 90% or less of that of the second region 9. In many cases, the lower the crosslink density, the lower the hardness. The hardness of the first region 8 is preferably lower than that of the second region 9. The term “adhesion” used herein refers to the adhesion between each region of the channel wall member and the substrate. A low crosslink density may lead to a reduction in adhesion. In both of the second region and the first region, the higher the adhesion, the higher the reliability of the liquid ejection head.
The degree of crosslink density may also be relatively determined by Raman spectroscopy, nuclear magnetic resonance, X-ray diffractometry, a photoacoustic analysis, time-of-flight mass spectrometry, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, a thermal analysis, a hardness measurement, or a nanoindentation technique. Alternatively, a difference in crosslink density may be determined on the basis of the state of chemical bonding or molecular shape by measuring viscoelasticity, Young's modulus, solubility, or the like.
The lower the crosslink density of the first region, the greater the stress reduction effect. In order to effectively produce the stress reduction effect, the ratio of the crosslink density of the first region to that of the second region is preferably higher than 0% and 90% or less. Since a reduction in crosslink density results in a reduction in the stress applied to the substrate, the ratio of the crosslink density of the first region to that of the second region is more preferably 70% or less. The ratio of the crosslink density of the first region to that of the second region is further preferably 50% or less because disconnection of the three-dimensional network of a bridge structure increases the stress reduction effect. Note that, the state where “the ratio of the crosslink density of the first region to that of the second region is 0%” refers to a state where no crosslink is formed in the first region. In the case where a photosensitive resin is used as in this embodiment, it is difficult to form the first region while setting the ratio to exactly 0% due to an environmental influence on the photosensitive resin. However, it is still possible to make this ratio close to 0%. In this case, a resin that does not cause crosslinking when being irradiated with an electromagnetic wave, a radiation, or the like that are generated in the manufacturing environment or the operating environment, that does not cause crosslinking in air or the atmosphere of the manufacturing process, and that does not cause crosslinking due to heat generated during the manufacturing process or operation of the product may be employed. On the other hand, according to the embodiment, good selectivity of materials, a high degree of flexibility in the manufacturing process, a short manufacturing process, a little limitation to the operation environment of the liquid ejection head, and the like may be realized.
A case where the channel wall member has the first region and the second region is described below. As described above, the crosslink density in the first region is uniform, and the crosslink density in the second region is also uniform. The ratio of the volume of the first region to the total volume of the first region and the second region is preferably 10% or more and 90% or less in order to achieve the stress reduction while keeping a skeleton capable of maintaining an adequate strength. The volume fraction of the first region is more preferably 70% or less in order to enhance a strength to an external force. The volume fraction of the first region is further preferably 50% or less in order to enhance the durability of the first region when the first region is brought into contact with a liquid by covering the first region with the second region.
The channel wall member is in direct contact with the surface of the substrate or in contact with the surface of the substrate via a layer formed on the surface of the substrate. The ratio of the area of the surface of the first region at which the first region is in contact with the surface of the substrate to the area of the surface of the channel wall member at which the channel wall member is in contact with the surface of the substrate is preferably 0% or more and 90% or less from the viewpoint of the adhesion between the channel wall member and the substrate.
The channel wall member comprises a photosensitive resin. The photosensitive resin may be a negative photosensitive resin. Considering the degree of the flexibility of the manufacturing process and the reliability of the product, the photosensitive resin is preferably a resin having high resistance to heat and chemicals, that is, specifically, at least one of a polyimide resin, a polyamide resin, an epoxy resin, a polycarbonate resin, and a fluororesin. In particular, among these photosensitive resins, an epoxy resin is preferably used.
Using the same material for forming the first region and the second region simplifies the manufacturing process since the number of types of materials used is reduced. The photosensitive resin may include a photoacid generating agent, a sensitizing agent, a reducing agent, an adhesion-enhancing adhesive, a water repellent, an electromagnetic wave-absorbing member, and the like. The photosensitive resin may also include a thermoplastic resin, a softening point-controlling resin, a resin for increasing strength, and the like. The photosensitive resin may also include an inorganic filler, carbon nanotube, and the like. The photosensitive resin may also include a conductive material in order to take measures against static electricity. The above-described components may be added to the photosensitive resin in order to control the crosslink density.
Examples of the first region 8 and the second region 9 formed in the channel wall member are shown in
The reliability of the liquid ejection head may be further enhanced by covering the first region with the second region, the substrate, or another member. In the case where the adhesion between the first region and the substrate is poor, the second region may be interposed between the first region and the substrate in order to enhance the adhesion. On the right side of the channel in
The channel wall member may have a third region 10 in addition to the first region 8 and the second region 9. As shown in
As shown in
The channel wall member include a water-repellent film, a hydrophilic film, a protection film, or the like formed thereon. The channel wall member may have a relief structure, a vesicular structure, or the like. The channel wall member may have a ditch or a hole formed therein in order to further reduce the stress applied to the substrate. The channel wall member may be constituted by an inorganic member that covers the channel and a resin member that fills spaces. In this case, by applying the structure according to the embodiment to the portions in which the resin member is used, the stress caused in the resin member may be reduced, which increases the strength of the channel wall member while reducing the damage to the inorganic member. An adhesion-improving layer or a planarization layer may be interposed between the substrate and the channel wall member.
The liquid ejection head according to the embodiment may be used for producing a liquid ejection system. The liquid ejection system herein refers to apparatuses such as a printer, a copying machine, a facsimile including a communication system, a word processor and a portable device that include a printer unit, and industrial equipment formed by combining these processing devices. The object onto which a liquid is ejected may have a two-dimensional structure or a three-dimensional structure. A liquid may be ejected toward a space. The above-described liquid ejection system may be used in a semiconductor manufacturing system or a medical system.
A method for manufacturing the liquid ejection head according to the embodiment is described below with reference to
As shown in
As shown in
As shown in
As shown in
As shown in
As needed, a supply port may be formed in the substrate 1. The timing at which a step for forming the supply port is conducted is not limited. For example, the supply port may be formed before or after a step for forming the energy generating devices or before or after a step for forming the channel wall member. The supply port may be formed by, for example, wet etching, dry etching, or laser processing.
The liquid ejection head is manufactured as described above. The liquid ejection head includes a channel wall member having a first region 8 and a second region 9 that are arranged in a direction parallel to the surface of a substrate 1. The crosslink density of the first region 8 is lower than that of the second region 9.
Another method for manufacturing the liquid ejection head is described below with reference to
As shown in
As shown in
Development is performed, and the liquid ejection head shown in
Another method for manufacturing a liquid ejection head in which the first region and the second region are created at positions distant from the substrate is described below with reference to
As shown in
As shown in
As shown in
Development is performed, and the liquid ejection head shown in
The liquid ejection head according to the embodiment may also be manufactured by another method in which, as shown in
In addition, for example, a method shown in
As shown in
As shown in
As shown in
As shown in
The methods described with reference to
The crosslink densities of the first region 8 and the second region 9 may be further increased by, for example, exposing the first region 8 and the second region to light or performing a heat treatment of the first region 8 and the second region. This further enhances the reliability of the liquid ejection head.
In consideration of the manufacturing process, a region having a relatively low crosslink density may be created in a member other than the channel wall member. For example, the edges of the negative photosensitive resin viewed in a direction parallel to the surface of the substrate serve as regions having a relatively low crosslink density, and the other region of the negative photosensitive resin serves as a region having a relatively high crosslink density. The regions having a relatively low crosslink density are finally removed. In this method, the warpage of the substrate that occurs during the manufacturing process may be reduced.
The present invention is specifically described with reference to examples below.
As shown in
As shown in
As shown in
As shown in
As shown in
The substrate 1 was etched by reactive ion etching to form a liquid supply port in the substrate 1. Then, a heat treatment was performed at 160° C. using an oven in a nitrogen atmosphere. Thus, a liquid ejection head was prepared.
The ratio of the crosslink density of the first region 8 to that of the second region 9, which was calculated from the amount of epoxy groups remaining in each region on the basis of infrared absorption spectra of the first region 8 and the second region 9 of the liquid ejection head, was 90%. The Young's moduli of the first region 8 and the second region 9 at 25° C. were measured using a nanoindenter. The ratio of the Young's modulus of first region 8 to that of the second region 9 was 90%. The ratio of the area of the surface of the first region 8 at which the first region 8 was in contact with the substrate 1 to the area of the surface of the channel wall member at which the channel wall member was in contact with the substrate 1 was 80%. The ratio of the volume of the first region to the total volume of the first region and the second region was 90%. The liquid ejection head was immersed in an ink (“BCI-7C” produced by CANON KABUSHIKI KAISHA) for 48 hours and subsequently observed using a metallurgical microscope in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was not observed.
As shown in
The first layer was formed as described below. A PET film including a dry film mainly comprising a negative photosensitive resin (“157S70” produced by Japan Epoxy Resin Co., Ltd), which was laminated on the PET film, was prepared. The PET film was laminated on the substrate 1 using a roll laminator. Subsequently, the PET film was peeled off, and the resulting substrate 1 was cleaned with pure water. The first layer was exposed to light so as to form a pattern thereon and baked at 50° C. using a hot plate. The region that had been exposed to light served as a second region 9, and the region that had not been exposed to light served as a first region 8.
As shown in
Developed was performed using propylene glycol methyl ether acetate (PGMEA). A heat treatment was performed using a hot plate at 180° C. in air. Thus, the liquid ejection head shown in
The liquid ejection head was subjected to a measurement as in Example 1. The ratio of the crosslink density of the first region 8 to that of the second region 9 was 70%. The ratio of the Young's modulus of the first region 8 to that of the second region 9 was 70%. The ratio of the area of the surface of the first region 8 at which the first region 8 was in contact with the substrate 1 to the area of the surface of the channel wall member at which the channel wall member was in contact with the substrate 1 was 70%. The ratio of the volume of the first region to the total volume of the first region and the second region was 50%. The liquid ejection head was observed as in Example 1 in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was not observed.
As shown in
As shown in
As shown in
Development was performed using propylene glycol methyl ether acetate (PGMEA). A heat treatment was performed using a hot plate at 200° C. in a nitrogen atmosphere. Thus, the liquid ejection head shown in
The liquid ejection head was subjected to a measurement as in Example 1. The ratio of the crosslink density of the first region 8 to that of the second region 9 was 30%. The ratio of the Young's modulus of the first region 8 to that of the second region 9 was 20%. The ratio of the area of the surface of the first region 8 at which the first region 8 was in contact with the substrate 1 to the area of the surface of the channel wall member at which the channel wall member was in contact with the substrate 1 was 0%. That is, the first region 8 was not in contact with the substrate 1. The ratio of the volume of the first region to the total volume of the first region and the second region was 30%. The liquid ejection head was observed as in Example 1 in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was not observed.
As shown in
An ejection port formation layer 16 was formed on the negative photosensitive resin layer. The ejection port formation layer 16 was formed as in the formation of the negative photosensitive resin layer using a dry film mainly comprising a negative photosensitive resin (“157S70” produced by Japan Epoxy Resin Co., Ltd). The ejection port formation layer 16 was exposed to light to create regions in which liquid ejection ports were to be formed.
Development was performed, and a heat treatment was performed using a hot plate at 220° C. in a nitrogen atmosphere. Thus, the liquid ejection head shown in
The liquid ejection head was subjected to a measurement as in Example 1. The ratio of the crosslink density of the first region 8 to that of the second region 9 was 40%. The ratio of the Young's modulus of the first region 8 to that of the second region 9 was 20%. The ratio of the area of the surface of the first region 8 at which the first region 8 was in contact with the substrate 1 to the area of the surface of the channel wall member at which the channel wall member was in contact with the substrate 1 was 70%. The ratio of the volume of the first region to the total volume of the first region and the second region was 70%. The liquid ejection head was observed as in Example 1 in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was not observed.
A liquid ejection head was prepared as in Example 4 except that the volume fractions of the first region 8 and the second region 9 were changed.
The liquid ejection head was subjected to a measurement as in Example 1. The ratio of the crosslink density of the first region 8 to that of the second region 9 was 40%. The ratio of the Young's modulus of the first region 8 to that of the second region 9 was 20%. The ratio of the area of the surface of the first region 8 at which the first region 8 was in contact with the substrate 1 to the area of the surface of the channel wall member at which the channel wall member was in contact with the substrate 1 was 80%. The ratio of the volume of the first region to the total volume of the first region and the second region was 80%. The liquid ejection head was observed as in Example 1 in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was not observed.
As shown in
As shown in
As shown in
As shown in
The liquid ejection head was subjected to a measurement as in Example 1. The ratio of the crosslink density of the first region 8 to that of the second region 9 was 50%. The ratio of the Young's modulus of the first region 8 to that of the second region 9 was 24%. The ratio of the area of the surface of the first region 8 at which the first region 8 was in contact with the substrate 1 to the area of the surface of the channel wall member at which the channel wall member was in contact with the substrate 1 was 30%. The ratio of the volume of the first region to the total volume of the first region and the second region was 30%. The liquid ejection head was observed as in Example 1 in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was not observed.
A liquid ejection head was prepared as in Example 1 except for the following. In Example 1, the coating layer 12 was exposed to light so as to create the first region 8 and the second region 9 in the coating layer 12 in the step shown in
In the liquid ejection head, the crosslink density of the coating layer (channel wall member) was uniform over the entire coating layer. The liquid ejection head was observed as in Example 1 in order to examine whether the channel wall member was removed from the substrate or not. The removal of the channel wall member was partly observed.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-248451, filed Nov. 29, 2013, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-248451 | Nov 2013 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20040036744 | Cho et al. | Feb 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 2005205916 | Aug 2005 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20150151543 A1 | Jun 2015 | US |
