Patent Application
20220161560
The present disclosure generally relates to a liquid ejection head for ejecting liquid such as ink.
Japanese Patent Application Laid-Open No. 2017-205903 discloses a liquid ejection head having a recording element substrate provided with an energy generating element for generating ejection energy. The recording element substrate is fixed to the support member with an adhesive agent. The end portion of the electric wiring substrate is fixed to the support member so as to be adjacent to the end portion of the recording element substrate. Electrically connecting portions are provided on the end portions of the electric wiring substrate and the recording element substrate, and the electrically connecting portions are electrically connected by an electrically connecting member such as a wire bonding. The entire portion including the electrically connecting portion of the electric wiring substrate, the electrically connecting portion of the recording element substrate, and the electrically connecting member is covered with a sealing member such as resin.
In the above liquid ejection head, a sealing member having higher rigidity is used in order to obtain a higher insulation property or to prevent liquid penetration. Also, an adhesive agent with higher rigidity is used to enhance adhesiveness.
However, in the liquid ejection head disclosed in Japanese Patent Application Laid-Open No. 2017-205903 with a sealing member or adhesive agent having high rigidity, strong stress occurs in the contact surface between the sealing member and the recording element substrate and the support member when a temperature change occurs because the coefficient of thermal expansion of the recording element substrate and that of the support member are different. As a result, a crack may occur in the recording element substrate which has a lower mechanical strength than the support member.
Aspects of the present disclosure provide a liquid ejection head capable of suppressing the occurrence of cracking in the recording element substrate.
A liquid discharge head of the present disclosure features a liquid ejection head with a recording element substrate for ejecting liquid and a support member for supporting the recording element substrate. An adhesive layer is provided between the recording element substrate and the support member. A first electrically connecting portion is provided at an end portion of the recording element substrate, and a sealing member covers the end portion of the recording element substrate including the first electrically connecting portion. Wherein the sealing member is in contact with a side surface of the end portion of the recording element substrate and an end surface of the adhesive layer, and the adhesive layer includes a first adhesive portion and a second adhesive portion which is positioned between the first adhesive portion and the sealing member. Wherein the rigidity of the second adhesive portion is less than the rigidity of the sealing member and also less than the rigidity of the first adhesive portion.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. In the attached drawings, the same numbers are given to the components having the same functions, and the description thereof may be omitted. The components described in the embodiments are merely illustrative, and the scope of the present disclosure is not limited thereto.
Referring to
The liquid ejection module 2200 is provided on a flow passage member in which the first flow passage member 2050 and the second flow passage member 2060 are laminated. The second flow passage member 2060 has a common supply flow passage 2211 and a common collection flow passage 2212. The common supply flow passage 2211 communicates with the liquid communication orifice 31 of the support member 2030 via communication orifices 61, 53 and 51. The liquid is supplied from the common supply flow passage 2211 to the recording element substrate 2010. A part of the liquid supplied to the recording element substrate 2010 is collected to the common collection flow passage 2212 through a communication orifice which is not shown in the figure.
Referring to
Multiple terminals 16 for driving the recording element are provided in an end portion 500 of the recording element substrate 2010. The terminal 16 is an example of a first electrically connecting portion. In this case, the terminals 16 are arranged at the both end portions in the direction of the row of the ejection orifices of the recording element substrate 2010 (long sides).
The support member 2030 has a support surface 2030a for supporting a back surface 2010b which is a surface opposite to the ejection surface 2010a of the recording element substrate 2010. The adhesive layer 4000 is provided between the recording element substrate 2010 and the support member 2030. The adhesive layer 4000 bonds the back surface 2010b of the recording element substrate 2010 to the support surface 2030a of the support member 2030.
The sealing member 110 covers at least the end portion 500 of the recording element substrate 2010 including the terminal 16. The sealing member 110 is in contact with the side surface of the end portion 500 of the recording element substrate 2010 and the end surface of the adhesive layer 4000.
The flexible wiring substrate 40 is an example of the wiring substrate. Multiple terminals 41 are formed in the end portion of the flexible wiring substrate 40. The terminal 41 is an example of a second electrically connecting portion. The terminal 16 of the recording element substrate 2010 and the terminal 41 of the flexible wiring substrate 40 are electrically connected through an electrically connecting member 402. The electrically connecting member 402 is, for example, wire bonding. The end portion of the flexible wiring substrate 40 is fixed to the support member 2030 so as to be adjacent to the end portion 500 of the recording element substrate 2010. The sealing member 110 covers the electrically connecting member 402, the end portion of the flexible wiring substrate 40, and the end portion 500 of the recording element substrate 2010. By increasing the rigidity of the sealing member 110, the electrically connecting member 402, the terminal 16 of the recording element substrate 2010 and the terminal 41 of the flexible wiring substrate 40 can be more effectively protected and further protected from corrosion by liquid. As the sealing member 110, for example, a material with high elastic modulus can be used. Here, the elastic modulus is a physical property value indicating the resistance in deformation.
The adhesive layer 4000 has a first adhesive portion 400 consists of a first adhesive agent and a second adhesive portion 401 consists of a second adhesive agent. The second adhesive portion 401 is positioned between the first adhesive portion 400 and the sealing member 110. The contact surface between the second adhesive portion 401 and the sealing member 110 is provided so as to be flush with the side surface of the end portion 500 of the recording element substrate 2010. In order to firmly bond the recording element substrate 2010 and the support member 2030 and to prevent leakage of liquid, a high-strength adhesive agent having strong adhesive force is used as the first adhesive agent. The first adhesive portion 400 is located closer to the opening edge of the liquid communication orifice 31 of the support member 2030 than the second adhesive portion 401. The first adhesive portion 400, which is composed of a high strength adhesive agent, has high rigidity. The rigidity of the second adhesive portion 401 is less than the rigidity of the sealing member 110 and also less than the rigidity of the first adhesive portion 400.
Specifically, the elastic modulus of the second adhesive portion 401 is less than the elastic modulus of the first adhesive portion 400 and also less than the elastic modulus of the sealing member 110. For example, the elastic modulus of second adhesive portion 401 is less than or equal to ⅓ of the elastic modulus of first adhesive portion 400 or sealing member 110. Preferably, the elastic modulus of the first adhesive portion 400 or the sealing member 110 may be 10 GPa or greater, and the elastic modulus of the second adhesive portion 401 may be less than 10 GPa. For example, for the first adhesive portion 400, the second adhesive portion 401, and the sealing member 110, an anionic curing epoxy resin having good adhesiveness can be used. Desirably, as the first adhesive portion 400 and the sealing member 110, a resin having higher rigidity, for example, an acid anhydride curing epoxy resin having 50% or more of silica fillers can be used. For the second adhesive portion 401, an amine-based epoxy resin can be used.
The liquid ejection module 2200 described above may be manufactured by the following procedure. First, the recording element substrate 2010 and the flexible wiring substrates 40 are bonded onto the support member 2030 so that their end portions are adjacent to each other. Next, the terminal 16 of the recording element substrate 2010 and the terminal 41 of the flexible wiring substrate 40 are electrically connected by the electrically connecting member 402. The entire portion including terminals 16, 41 and electrically connecting portion 402 is then sealed with the sealing member 110.
The support member 2030 is a support body for supporting the recording element substrate 2010, and is also a flow passage member for supplying liquid to the recording element substrate 2010 and collecting a part of the liquid. For this reason, it may be preferable that the material of the support member 2030 has a high flatness and can be bonded to the recording element substrate 2010 with sufficient reliability. The material of the support member 2030 may be preferably, for example, alumina (aluminum oxide) or a resin material.
Next, the effect of the liquid ejection head of the present embodiment will be described with reference to a comparative example.
In the first comparative example and the second comparative example, the following problem occurs when the sealing member 110 having a high elastic modulus is used.
The coefficient of thermal expansion of recording element substrate 2010 is different from the coefficient of thermal expansion of support member 2030. Therefore, when a temperature change occurs in the recording element substrate 2010 and the support member 2030, strong stress is generated in the contact surface between the sealing member 110 and the recording element substrate 2010 and the contact surface between the sealing member 110 and the support member 2030. As a result, recording element substrate 2010, which has a lower mechanical strength than support member 2030, is susceptible to crack. For example, when the recording element substrate 2010 is composed of a silicon substrate, a crack susceptibly occurs at an edge portion of the end portion of the recording element substrate 2010. Here, the coefficient of thermal expansion indicates the rate of expansion in the length or volume of the object due to the temperature rise per degree.
In addition, in case that the elastic modulus of the first adhesive portion 400 for bonding the recording element substrate 2010 and the support member 2030 is small, the recording element substrate 2010 largely moves with respect to the support member 2030 when the above temperature change occurs. As a result, strong stress occurs in the contact surface between the sealing member 110 and the recording element and the contact surface between the sealing member 110 and the support member 2030.
In the adhesive structure of the first comparative example, when the elastic modulus of the first adhesive portion 400 is high, the entire end portion (including the edge portion) of the recording element substrate 2010 is covered with materials (first adhesive portion 400 and sealing member 110) having high rigidity. As a result, when the above temperature change occurs, strong stress is generated in the edge portion of the end portion of the recording element substrate 2010 due to the difference in the coefficient of thermal expansion between the recording element substrate 2010 and the support member 2030.
On the other hand, in the adhesive structure of the second comparative example, because the auxiliary adhesive portion 403 partially functions as a buffer material, even if the elastic modulus of the first adhesive portion 400 is high, the entire end portion of the recording element substrate 2010 is not covered with a material of high rigidity. However, the edge portion of the end portion of the recording element substrate 2010 on the side of the support member 2030, which is most likely to be stressed, is fixed to the support member 2030 with the first adhesive portion 400 having a high elastic modulus. As a result, a strong stress is generated at the edge portion.
In addition, the sealing member 110 mechanically protects the electrically connecting member 402, the terminal 16 of the recording element substrate 2010, and the terminal 41 of the flexible wiring substrate 40, and further protects against liquid corrosion. In this sealing structure, it is not preferable for the auxiliary adhesive portion 403 to be exposed. Therefore, also in the adhesive structure of the second comparative example, the sealing member 110 covers the auxiliary adhesive portion 403 and firmly fixes the recording element substrate 2010 onto the support member 2030. At the edge portion of the end portion of the recording element substrate 2010 which is fixed by the sealing member 110 as above, strong stress occurs due to the difference in the coefficient of thermal expansion between the recording element substrate 2010 and the support member 2030 when the above temperature change occurs.
In addition to the first comparative example and the second comparative example, there may be a configuration in which a space is formed between the sealing member 110 and the support member 2030. However, as in the case with the auxiliary adhesive portion 403, it is necessary to cover the space with the sealing member 110 from an electrical viewpoint, and it is difficult to form such a configuration.
According to the liquid ejection head of the present embodiment, against the first comparative example and the second comparative example, the edge portion on the support member 2030 side of the end portion 500 of the recording element substrate 2010, which is most likely to be stressed, is bonded to the support member 2030 via the second adhesive portion 401 having a low elastic modulus. Therefore, the end portion 500 of the recording element substrate 2010 can move easily with respect to the support member 2030. Therefore, when temperature changes occur in the recording element substrate 2010 and the support member 2030, it is possible to reduce stress generated in the edge portion due to the difference in the coefficient of thermal expansion between the recording element substrate 2010 and the support member 2030.
As shown in
Under the conditions shown in
As described above, in the liquid ejection head of the present embodiment, the adhesive layer 4000 disposed between the recording element substrate 2010 and the support member 2030 has the first adhesive portion 400 and the second adhesive portion 401. The second adhesive portion 401 is provided closer to the sealing member 110 than the first adhesive portion 400. The rigidity (or elastic modulus) of the second adhesive portion 401 is less than the respective rigidity (or elastic modulus) of the first adhesive portion 400 and the sealing member 110. With such a structure, stress generated at the end portion 500 of the recording element substrate 2010 can be reduced, and generation of a crack in the recording element substrate 2010 can be suppressed.
In the liquid ejection head of the present embodiment, the following modifications can be made.
As shown in
The second adhesive portion 401 extends along the end portion of the recording element substrate 2010. The first adhesive portion 400 has multiple belt-shaped adhesive portions 400a. Each of the belt-shaped adhesive portions 400a extends in a direction intersecting the longitudinal direction of the second adhesive portion 401. Multiple liquid supply orifices 31 are provided. Belt-shaped adhesive portions 400a and liquid supply orifices 31 are alternately arranged. According to this structure, the first adhesive portion 400 with high elastic modulus is separated into multiple belt-shaped adhesive portions 400a in a direction along the end portion of the recording element substrate 2010 which is likely to be stressed. This separation can further reduce the stress at the edge portion due to the difference in the coefficient of thermal expansion between the recording element substrate 2010 and the support member 2030.
The liquid ejection head of the second modified example was subjected to the same test as the thermal shock test described above. The sample with the first adhesive portion 400 which is not separated into belt-shaped adhesive portions 400a could crack after 120 cycles. In contrast, the sample with the first adhesive portion 400 which is separated into belt-shaped adhesive portions 400a did not crack even after 200 cycles.
Note that the second adhesive portion 401 does not necessarily have to be provided between the sealing member 110 and the first adhesive portion 400 over the entire area. Some belt-shaped adhesive portions 400a may protrude to the sealing member 110 with beyond the second adhesive portion 401. Also in this case, since the first adhesive portion 400 is separated into multiple belt-shaped adhesive portions 400a, the stress is dispersed, so that the occurrence of cracks can be suppressed.
According to the liquid ejection head of the second modified example, the first adhesive portion 400 is separated into the belt-shaped adhesive portions 400a in the space surrounded by the liquid supply passage 31 of the support member 2030, the supply passage 18 of the recording element substrate 2010 and the sealing members 110, thereby achieving the following effects.
In the adhesive layer 4000 shown in
The first adhesive portion 400 and the second adhesive portion 401 are not limited to the arrangements described above. The first adhesive portion 400 and the second adhesive portion 401 may be arranged in any manner as long as the occurrence of cracks can be suppressed. Several patterns of structure in which the first adhesive portion 400 and the second adhesive portion 401 surround the liquid supply orifice 31 in a planer view of the liquid ejection head are described below.
The liquid ejection head of the present disclosure described above may preferably be applied in the following cases.
When the outer-shape of the recording element substrate 2010 is a parallelogram having an obtuse vertex and an acute vertex, due to the difference between the coefficient of thermal expansion of the recording element substrate 2010 and the support member 2030, the recording element substrate 2010 tries to deform so as to rotate in parallel to the joint plane with respect to the support member 2030. Therefore, stronger stress is generated at the edge portion of the end portion near the acute vertex of the recording element substrate 2010, and a crack of the recording element substrate 2010 is likely occurred. In such a case the occurrence of cracks in the recording element substrate 2010 can be suppressed by applying the liquid ejection head of the present disclosure.
If terminals 16 are formed at both end portions of the recording element substrate 2010, sealing members 110 with high elastic modulus fix both end portions of the recording element substrate 2010 to support member 2030. Therefore, stronger stress is generated at the edge portion of the end portion near the acute vertex of the recording element substrate 2010, and a crack of the recording element substrate 2010 is likely generated. In such a case, the occurrence of a crack in the recording element substrate 2010 can be suppressed by applying the liquid ejection head of the present disclosure.
Further, in a configuration in which the liquid ejection head controls the temperature of the recording element substrate 2010 to perform high-quality ejection, a large thermal change is repeatedly applied to the recording element substrate 2010 and the support member 2030. As a result, a crack of the recording element substrate 2010 is likely to occur. In such a case, the liquid ejection head of the present disclosure can be applied to suppress the occurrence of a crack in the recording element substrate 2010.
In addition, to protect the electrically connecting member 402, the terminal 16 and the terminal 41 mechanically and also to protection them from liquid corrosion, it may be preferable to set the curing temperature of the sealing member 110 higher. For example, the curing temperature may be preferably 150° C. or higher. However, when the curing temperature is raised to a high temperature, the thermal stress when the sealing member 110 cured at the curing temperature returns to the normal temperature becomes larger, and a crack of the recording element substrate 2010 is likely to occur. Also in this case, the liquid ejection head of the present disclosure can be applied to suppress the occurrence of a crack in the recording element substrate 2010. Further, in the case where frequent and long-term use is required, for example for industrial applications, the recording element substrate 2010 and the support member 2030 repeatedly undergo large thermal changes. As a result, a crack in the recording element substrate 2010 is likely to occur. Also in this case, the liquid ejection head of the present disclosure can be applied to suppress the occurrence of a crack in the recording element substrate 2010.
Further, it may be preferable that the first adhesive agent of the first adhesive portion 400 and the second adhesive agent of the second adhesive portion 401 are both heat-curable materials, and the curing temperature of the second adhesive agent is lower than the curing temperature of the first adhesive agent. In order to strongly bond the recording element substrate 2010 to the support member 2030, the adhesive agent may be a thermosetting adhesive agent and has a high curing temperature in some cases. However, when the recording element substrate 2010 is bonded to the support member 2030 with an adhesive agent which cures at a high temperature, the relative positional relationship between the recording element substrate 2010 and the support member 2030 changes after the temperature returns to normal because the linear expansion coefficients of the members are different from each other. To the problem, in general, another adhesive agent having a lower curing temperature is used as an auxiliary agent for temporal fixation at a lower temperature to achieve both high adhesive strength and high placement accuracy. However, in order to effectively protect the side with the electrically connecting portion where the electrically connecting portion is located, it is not desirable to place an adhesive agent for temporal fixation on the side of the recording element substrate 2010 such exemplified by the auxiliary adhesive portion 403 in
The above-described configuration does not limit the scope of the present disclosure. A thermal system for ejecting liquid by generating bubbles by a heating element has been described as an example but the present disclosure can also be applied to liquid ejection head adopting a piezo system or other various liquid ejecting systems.
Further, the present disclosure can be applied to a so-called line type head having a length corresponding to the width of a recording medium or a so-called serial type liquid ejection head for performing recording while scanning a recording medium.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure 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 priority from Japanese Patent Application No. 2020-196092, filed Nov. 26, 2020, and Japanese Patent Application No. 2021-050143, filed Mar. 24, 2021, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-196092 | Nov 2020 | JP | national |
| 2021-050143 | Mar 2021 | JP | national |
