Patent Grant
10239317
The present disclosure relates to a method for manufacturing a liquid discharge head for discharging a liquid, a liquid discharge head, and a method for manufacturing a liquid discharge head substrate.
An inkjet recording apparatus as a liquid discharge apparatus includes an inkjet recording head as a liquid discharge head. The inkjet recording apparatus performs recording by discharging liquid ink from the inkjet recording head, and applies the ink onto a record medium.
The liquid discharge head includes a liquid discharge head substrate (hereinafter also referred to as the substrate) and a flow path forming member. The substrate has a silicon base, a pressure generation element, and a supply port. The pressure generation element generates pressure for discharging the liquid. The supply port supplies the liquid to a pressure generation portion corresponding to the pressure generation element. The flow path forming member has a groove that forms a flow path and a discharge port. The substrate and the flow path forming member are bonded together to form a flow path for supplying the liquid to a pressure chamber containing the pressure generation portion, as well as to the pressure generation portion.
As a method for forming the supply port passing through the silicon base, a silicon anisotropic wet etching method is known. Japanese Patent Application Laid-Open No. 10-181032 discusses this type of method, which forms the supply port with high dimensional accuracy by providing a sacrificial layer on the front surface of the base. In a case where a heater is used as the pressure generation element, a heat accumulation layer for efficiently transmitting heat to the liquid is formed on the sacrificial layer. Further, a protective layer for protecting the pressure generation element from the liquid is formed on the sacrificial layer. When the supply port is formed by the anisotropic wet etching from the back surface of the base, a cover layer for covering the sacrificial layer such as the heat accumulation layer and the protective layer functions as an etching-resistant layer for stopping progress of the etching.
Meanwhile, Japanese Patent Application Laid-Open No. 2007-160624 discusses a conceivable disadvantage. Specifically, during formation of the supply port, a crack may be formed in the protective layer located in a region inside the supply port because of warpage of the base. The warpage is caused by internal stress of the flow path forming member. To prevent such a disadvantage, Japanese Patent Application Laid-Open No. 2007-160624 discusses a configuration in which the protective layer is not provided in the region inside the supply port, and an end of the protective layer and an end of the supply port are covered with an end covering layer.
In a case where the cover layer for covering the sacrificial layer such as the heat accumulation layer and the protective layer is provided, a following undesirable situation may occur. That is, in a process of removing the sacrificial layer by etching the base to form the supply port, a crack may be formed in an end covering portion of the cover layer which covers an end of the sacrificial layer.
It can be thought that the crack may be formed in the end covering portion of the cover layer for covering the heat accumulation layer and the protective layer or the like, in the following manner. When etching is performed from the back surface of the base, warpage may occur in the base because of internal stress of, for example, the heat accumulation layer, the protective layer, and the flow path forming member provided on the front surface of the base. Here, the end covering portion of the cover layer is a part that covers a step formed by the sacrificial layer, and therefore has a film thickness less than that of a part provided on a flat surface of the base. This is because, when the cover layer is provided, gas and precursor radicals if a chemical vapor deposition (CVD) method is used, or sputtered atoms if sputtering is used, become resistant to creep and adhesion in a region near the step of the sacrificial layer.
Moreover, the heat accumulation layer and the protective layer also function as the etching-resistant layer which stops the progress of the etching, for an etchant used in forming the supply port. Therefore, the etchant may change the quality of the flow path forming member, if a crack is formed in the heat accumulation layer and the protective layer in the process of forming the supply port.
The present disclosure is directed to suppression of a possibility that a crack may be formed in the end covering portion that covers the end of the sacrificial layer.
According to an aspect of the present disclosure, a method for manufacturing a liquid discharge head including a liquid discharge head substrate and a flow path forming member, the liquid discharge head substrate having a base, a pressure generation portion provided at a front surface of the base to generate pressure for discharging a liquid, and a supply port for supplying the liquid to the pressure generation portion, and the flow path forming member forming a flow path for feeding the liquid supplied from the supply port to the pressure generation portion, includes providing a sacrificial layer on the front surface of the base, providing a cover layer at the front surface of the base, the cover layer covering the sacrificial layer and including an end covering portion for covering an end of the sacrificial layer, providing a resin layer for covering the end covering portion, providing a flow path mold member on a front surface of the cover layer and a front surface of the resin layer, providing the flow path forming member on a front surface of the flow path mold member, and removing the sacrificial layer by etching the base from a back surface of the base, in a state in which the end covering portion is covered with the resin layer, wherein, in providing the resin layer, an opening which has an area smaller than an area of the sacrificial layer viewed from a direction orthogonal to the front surface of the base, is formed in the resin layer, and a surface of a part of the cover layer which covers the sacrificial layer, is exposed from the opening.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
The liquid discharge head substrate 10 has a supply port 11 provided to pass through the liquid discharge head substrate 10. The supply port 11 is provided to supply the liquid to the heat application portion 12. Further, a bubble generation chamber 22 serving as a pressure chamber is provided to communicate with the discharge port 21 and to surround the heat application portion 12. The bubble generation chamber 22 is formed by the flow path forming member 20. The supply port 11 has an opening edge portion 11a shaped like a rectangle and extended in a direction of the array of the bubble generation chambers 22 and the array of the discharge ports 21.
The flow path forming member 20 and the liquid discharge head substrate 10 are bonded together to form a flow path 23 and a common liquid chamber 24 (see
Thermal energy generated by the heater is applied, via the heat application portion 12, to the liquid supplied into the bubble generation chamber 22. This causes film boiling, thereby generating bubbles in the bubble generation chamber 22. Bubbling pressure of these bubbles increases pressure in the bubble generation chamber 22. This applies kinetic energy to the liquid, so that a droplet is discharged from the discharge port 21. In this process, power and a drive signal are supplied from the main body of the liquid discharge apparatus 1 to the heater via a connection pad 17 provided on the liquid discharge head substrate 10, so that the heater is driven to generate the thermal energy. A dot is formed on a record medium P by discharge of a droplet from the discharge port 21 of the liquid discharge head 14 to the record medium P, so that an image is recorded on the record medium P.
A configuration of the liquid discharge head 14 according to a first exemplary embodiment will be described.
A silicon base is used as a base 10a of the liquid discharge head substrate 10. A heat accumulation layer 210 made of a material such as silicon oxide is formed on the front surface of the base 10a. Elements including a heater 220 made of tantalum nitride, a switching element for driving the heater 220, and a selection circuit (not illustrated) are provided on the front surface of the heat accumulation layer 210. The heater 220 is connected to a heater electrode (not illustrated). Further, a protective layer 230 for protecting the heater 220 is formed on the front surface of the heat accumulation layer 210 and the heater 220. The protective layer 230 is made of a material such as silicon nitride. The flow path forming member 20 is formed at the front surface of the liquid discharge head substrate 10, i.e., at the front surface of the protective layer 230. The flow path forming member 20 is made of, for example, an epoxy-based resin material.
Further, an intermediate layer 101 is formed between the protective layer 230 of the liquid discharge head substrate 10 and the flow path forming member 20. The intermediate layer 101 is made of a material having more strength of adhesion to (strength of bonding with) the protective layer 230 than that of the flow path forming member 20. This can suppress peeling of the flow path forming member 20 off the liquid discharge head substrate (the protective layer 230). The intermediate layer 101 may be formed of a material having the above-described characteristic. Examples of this material include resin materials such as HIMAL (produced by Hitachi Chemical Co., Ltd.) and SU-8 (produced by Kayaku MicroChem Corporation).
Furthermore, a resin layer 102 is provided over the opening edge portion 11a of the supply port 11 formed on the front surface of the liquid discharge head substrate 10, as illustrated in
The resin layer 102 has a part contacting the front surface of the liquid discharge head substrate 10 (the front surface of the protective layer 230), and a part extending above the region inside the supply port 11 along this front surface, as illustrated in
The resin layer 102 has a width of, for example, 8 μm to 12 μm. The resin layer 102 is provided to surround the opening edge portion 11a of the supply port 11. Specifically, the resin layer 102 has an opening having an area smaller than an opening area of the supply port 11. From the viewpoint of supplying the liquid, a width W1 of a part which is located inside the supply port 11, of the resin layer 102 is desirably about 1/30 to 1/200 of an opening width W2 of the supply port 11.
Next, a method for manufacturing the liquid discharge head 14 will be described with reference to
First, as illustrated in
A portion 211 of the heat accumulation layer 210 and a portion 231 of the protective layer 230 cover the end of the sacrificial layer 310 (
Further, the intermediate layer 101 (which has desirably a thickness of 1 μm to 4 μm) made of a polyether-amide-based resin material is formed by spin coating on the front surface of the protective layer 230 located near the heater 220. Furthermore, the resin layer 102 is formed to provide the step portion 103 that covers the portion 211 of the heat accumulation layer 210 and the portion 231 of the protective layer 230. The intermediate layer 101 and the resin layer 102 are formed as one layer by using the same material in the same process. However, the intermediate layer 101 and the resin layer 102 may be formed using different materials. In this process, an opening 104 is desirably provided in the resin layer 102. In this way, it becomes unnecessary to add a process of forming the opening 104 through which the liquid flows from the supply port 11. Since the opening 104 is provided, the front surface of a part, which covers the sacrificial layer 310, of the protective layer 230 is exposed from the opening 104. The opening 104 has an area smaller than the opening area of the supply port 11, and smaller than the area of the sacrificial layer 310 viewed from a direction orthogonal to the front surface of the liquid discharge head substrate 10.
Next, a flow path mold member 320 made of a resist material is formed by spin coating, on the front surface of the protective layer 230, the intermediate layer 101, and the resin layer 102, as illustrated in
Next, a front surface protective layer 330 made of a resist material is formed by spin coating, on the front surface of the flow path forming member 20 and the flow path mold member 320, as illustrated in
Next, silicon anisotropic wet etching is performed using tetramethylammonium hydroxide (TMAH) from the back surface side of the base 10a, by using the supply port forming mask layer 340 as a mask, as illustrated in
Next, a portion located in the region inside the supply port 11 of the heat accumulation layer 210 is removed by wet etching using buffered hydrogen fluoride (BHF), as illustrated in
Next, the front surface protective layer 330 and the supply port forming mask layer 340 are removed by asking and rinsing, as illustrated in
Here, when the base 10a is etched in the process of forming the supply port 11 illustrated in
Therefore, as described above, the base 10a is etched to form the supply port 11, in a state in which the front surface side of the portion 211 of the heat accumulation layer 210 and the portion 231 of the protective layer 230 is covered by the resin layer 102, as illustrated in
The resin layer 102 is desirably formed in the same process as the process of forming the intermediate layer 101 disposed between the flow path forming member 20 and the liquid discharge head substrate 10. This can suppress the formation of a crack without adding more process. Further, the heat accumulation layer 210 and the protective layer 230 can be used as an etching-resistant layer during silicon anisotropic etching, by disposing the heat accumulation layer 210 and the protective layer 230 in the region inside the supply port 11.
The resin layer 102 can be formed thicker than the cover layer such as the heat accumulation layer 210 and the protective layer 230. In this way, the end covering portion of the heat accumulation layer 210 and the protective layer 230 can be more firmly reinforced by using the resin layer 102.
As for Japanese Patent Application Laid-Open No. 2007-160624, in which the protective layer is not provided inside the opening region of the supply port, it may become difficult in a manufacturing process to implement the configuration discussed therein. This is because, in a case where the protective layer is formed of a material containing a silicon compound such as silicon nitride, it may become difficult to ensure a difference in etching rate between the protective layer and the base 10a made of silicon, and thus process control may become difficult. In contrast, the heat accumulation layer 210 and the protective layer 230 are provided inside a region that becomes the supply port 11, before the supply port 11 is formed. It is therefore possible to suppress the formation of the above-described crack in the cover layer while adopting a simple manufacturing method.
The second exemplary embodiment assumes a configuration in which an intermediate layer and a resin layer are formed as one layer while using the same material. Therefore, the intermediate layer and the resin layer in the first exemplary embodiment are combined and may be referred to as an intermediate layer 401. The intermediate layer 401 includes a part provided between the flow path forming member 20 and the liquid discharge head substrate (the protective layer 230), a part facing the common liquid chamber 24 (a part of the intermediate layer 401), and a part extending to the region inside the supply port 11. In addition, these parts of the intermediate layer 401 are connected to each other. The intermediate layer 401 is not provided inside the bubble generation chamber 22.
The intermediate layer 401 has a step portion 402 which comes close to the flow path forming member 20 in the region inside the supply port 11. The step portion 402 reinforces the portion 211 of the heat accumulation layer 210 and the portion 231 of the protective layer 230 in a process of forming the supply port 11. It is therefore possible to suppress the formation of a crack in these parts.
The supply port 11 may be formed to be a large port because of variations in a manufacturing process. This may locate the resin layer 102 surrounding the opening edge portion 11a of the supply port 11 according to the first exemplary embodiment, in the region inside the supply port 11 of the base 10a. In this case, the resin layer 102 may be formed to be sunk to the supply port 11, if the intermediate layer 101 and the resin layer 102 are separated, i.e., not connected to each other, as in the first exemplary embodiment.
In contrast, the intermediate layer 401 has a part formed between the flow path forming member 20 and the protective layer 230, and a part located in the region inside the supply port 11 which includes the step portion 402. These parts are formed to be connected to each other. This prevents such a situation that the entire intermediate layer 401 is located in the region inside the supply port 11 even if the supply port 11 is formed as a large port. It is therefore possible to suppress sinking of the intermediate layer 401 to the supply port 11 due to variations in manufacturing the supply port 11.
The third exemplary embodiment assumes a configuration in which an intermediate layer and a resin layer are formed as one layer using the same material. Therefore, the intermediate layer and the resin layer in the first exemplary embodiment are combined and referred to as an intermediate layer 601. The intermediate layer 601 has a step portion 602 which comes close to the flow path forming member 20 in the region inside the supply port 11. The step portion 602 reinforces the portion 211 of the heat accumulation layer 210 and the portion 231 of the protective layer 230 in a process of forming the supply port 11. It is therefore possible to suppress the formation of a crack in these parts.
Further, as with the second exemplary embodiment, the intermediate layer 601 has a part provided between the flow path forming member 20 and the liquid discharge head substrate 10 (the protective layer 230), a part facing the common liquid chamber 24, and a part extending to the region inside the supply port 11. In addition, these parts of the intermediate layer 601 are connected to each other. It is therefore possible to suppress sinking of the intermediate layer 601 to the supply port 11 due to variations in manufacturing the supply port 11.
Here, a part of the intermediate layer 601 formed between the flow path forming member 20 and the protective layer 230 is referred to as a first part 611. Further, a part of the intermediate layer 601 including the step portion 602 and provided over the opening edge portion 11a of the supply port 11 is referred to as a second part 612. Furthermore, a part of the intermediate layer 601 provided at a position facing the common liquid chamber 24 and connecting the first part 611 and the second part 612 is referred to as a third part 613. The intermediate layer 601 is not provided in the bubble generation chamber 22 and the flow path 23.
Further, the flow path forming member 20 has a wall 25 formed between the adjacent bubble generation chambers 22, and between the adjacent flow paths 23. The first part 611 is located between the wall 25 and the liquid discharge head substrate 10. The third part 613 connects the first part 611 and the second part 612 along an extending direction of the wall 25, as illustrated in
In this way, in addition to the configuration of the second exemplary embodiment, a configuration is adopted which does not provide the intermediate layer 601 in the part 24a that communicates with the flow path 23 of the common liquid chamber 24. This can suppress an increase in resistance to the flow from the supply port 11 to the bubble generation chamber 22. Therefore, it is possible to ensure supply of the liquid to the bubble generation chamber 22, while suppressing the sinking of the intermediate layer 601 to the supply port 11.
In order to further suppress the increase in resistance to the flow, a width W3 (a length in the array direction of the heat application portions 12) of the third part 613 is desirably shorter than each of a width W4 and a width W5 of the first part 611 located between the wall 25 and the liquid discharge head substrate 10.
While the present disclosure 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. 2016-150418, filed Jul. 29, 2016, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-150418 | Jul 2016 | JP | national |
| Number | Date | Country |
|---|---|---|
| 10-181032 | Jul 1998 | JP |
| 2007-160624 | Jun 2007 | JP |
| 2007160624 | Jun 2007 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20180029367 A1 | Feb 2018 | US |
