Patent Grant
11820142
The present invention relates to an element substrate, a liquid discharge head, and a manufacturing method of the same.
Ink jet recording apparatuses (hereinafter, referred to simply as “recording apparatus”) have features such as being capable of high-density and high-speed recording on various types of recording media, making little noise when recording, and so forth. As a representative ink discharge method by ink jet recording heads (hereinafter, referred to simply as “recording head”) mounted in such recording apparatuses, there is known an arrangement in which ink is heated by electrothermal conversion elements having heating resistance elements, and ink droplets are discharge by the effect of film boiling.
In a recording head that uses electrothermal conversion elements, the electrothermal conversion elements are provided in recording liquid chambers. Electric pulses that serve as recording signals are supplied to the electrothermal conversion elements which are heated thereby, thermal energy is imparted to ink, and minute ink droplets are discharged from minute discharge orifices using bubble pressure generated from the recording liquid bubbling due to phase change of the recording liquid at this time, thereby performing recording on recording media. The recording head has ink jet recording nozzles for discharging ink droplets, and a supply system for supplying ink to these nozzles.
Manufacturing of a recording head involves a step of electrically connecting a bump on an electrode terminal on a recording element substrate configured having a substrate in which a heater and so forth are formed, and a nozzle-formation material, with an electrode lead (hereinafter, simply referred to as “lead”) of electric wiring tape for electric connection to the apparatus main body. In recent years, the number of nozzles has increased to raise printing speeds, and recording element substrate sizes are becoming smaller in order to increase the number of recording elements substates per wafer to reduce costs. Accordingly, the number of electrode terminals, i.e., the number of bumps disposed per wafer is in an increasing trend. Accordingly, forming each bump individually as with ball bumps, performing leveling to make the height of the bumps uniform, and connecting leads and electrode terminals individually results in long step takt. With regard to this point, electroplated bumps that are formed, with gold being grown by electroplating, enable a plurality of bumps to be formed by batch processing on each wafer, and variance in height of the bumps can be suppressed. As a result, the step takt can be shortened, and accordingly, using electroplated bumps is now mainstream for electrode terminals of recording element substrates.
Japanese Patent No. 4994968 uses gang bonding as a method for connecting to the recording element substrate. In gang bonding, leads are pressure-bonded under heat and pressure in batch fashion, to be joined to electroplated bumps of electrode terminals on the recording element substrate. Accordingly, all leads are bonded by a broad bonding tool, which has a feature in that the work takt for bonding can be made to be approximately the same regardless of the number of leads.
In an assembly method of a recording head including the step of electrically connecting the recording element substrate and the electric wiring tape, electric connection portions are subjected to no small load up to an adhesion fixing step to a base member, which is a subsequent step, due to shock, vibrations, and so forth that occur during conveyance and handling. These items are more noteworthy the further the increase in the size of the recording element substrate, increase in the number of electrode terminals, reduction in size of electrode terminals, and increasingly narrow pitches of electrode terminal rows, advance, and more care must be taken to avoid electric connection defects such as peeling, fracturing, and so forth, from occurring. Examples of methods for preventing electric connection defects such as peeling, fracturing, and so forth include raising bonding conditions, such as bonding tool temperature, shock load applied to the electroplated bumps, and the pressing load, thereby increasing the bonding strength of the electroplated bumps and leads.
However, in bonding in which electroplated bumps and leads are electrically connected, there have been cases in which applying pressure to the electroplated bumps by the bonding tool ruptures bent portions of a protective film layer on the outer side of the electroplated bumps and forms cracks. Formation of cracks can lead to moisture from ink and so forth intruding into the cracks, and the wiring covered by the protective film layer corroding.
Accordingly, it is an object of the present invention to provide an element substrate, a liquid discharge head, and a manufacturing method of the same, that are capable of suppressing corrosion of wiring due to moisture even if cracks occur in the bent portions of the protective film layer.
Accordingly, an element substrate used in a liquid discharge head that discharges liquid to a recording medium according to the present invention includes:
a substrate;
an energy generating element that generates energy used to discharge the liquid;
circuit wiring that has an electrode portion for external electrical connection and that drives the energy generating element, and that is implemented on the substrate;
a first protective film layer that has an opening portion for exposing the electrode portion and that covers the circuit wiring;
an electroplating ground layer formed on the electrode portion; and
an electroplated bump layer made of a metal material formed on the electroplating ground layer,
wherein
a bent portion is formed in the first protective film layer by the first protective film layer covering a protruding portion that the circuit wiring has, and
a second protective film layer is formed on the first protective film layer and covers the bent portion.
According to the present invention, even if cracks occur in the protective film layer formed below a resin film layer (elastic resin film), intrusion of moisture from ink and so forth from the cracks can be prevented by the resin film layer, and the problem of electric wiring film covered by the protective film layer corroding can be prevented.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An ink jet recording apparatus according to the present invention will be described below. A description of embodiments (examples) of the present invention will be given. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments.
The carriage 102 is supported by a guide shaft 103 disposed in an apparatus main body so as to extend in a main scanning direction so as to be capable of reciprocal movement following the guide shaft 103. The carriage 102 is driven by a transmission mechanism including a motor pulley 105, a slave pulley 106, a timing belt 107, and so forth, by a main scanning motor (carriage motor) 104, and the position and movement thereof are controlled thereby. A home position sensor 130 is provided on the carriage 102. A position serving as a home position is detected when the home position sensor 130 on the carriage 102 passes a position of a shielding plate 136.
A recording medium 108, such as paper, thin sheets of plastic, and so forth, serving as recording material, is separated and fed from an automatic sheet feeder (ASF) 132 one sheet at a time, by a sheet feeding motor 135 rotating a pickup roller 131 via gears. Further, the recording medium 108 is conveyed over a position (recording region) facing the faces of the recording heads H1000 and H1001 on which discharge orifices are formed (sub-scanned), by a conveying motor 134 rotating a conveying roller 109 driven via gears. Determination of whether or not a recording medium 108 has been fed, and final determination of a leading edge position of the recording medium at the time of feeding, are performed at the point in time of the recording medium 108 passing a paper end sensor 133. This paper end sensor 133 is also used for determining where the trailing edge of the recording medium 108 actually is, and ultimately determining the current recording position from the actual trailing end. Note that the rear face of the recording medium 108 is supported by a platen (omitted from illustration) so as to form a flat recording face in the recording region. In this case, the recording heads H1000 and H1001 mounted on the carriage 102 are held with the discharge orifice faces thereof protrude downward from the carriage 102 so as to be parallel with the recording medium 108, and main scanning thereof is performed in the recording region.
The recording heads H1000 and H1001 are mounted to the carriage 102 such that the direction of array of discharge orifices in each of the discharge portions is in a direction intersecting the main scanning direction of the carriage 102 (e.g., sub-scanning direction). Recording over a breadth corresponding to a discharge orifice layout range is performed by discharging ink that is a liquid from these discharge orifice rows in the process of main scanning.
The recording heads (liquid discharge heads) according to the present embodiment are configured integrally with ink tanks that are casing storing liquid therein. A first recording head H1000 has an ink storage portion filled with black ink, and a discharge portion for discharging black ink supplied from the ink storage portion. A second recording head H1001 has ink storage portions filled with each color ink (cyan ink, magenta ink, and yellow ink), and discharge portions for discharging color ink supplied from the respective ink storage portions. These recording heads H1000 and H1001 are fixedly supported on the carriage 102 by a positioning unit and electric contacts, and have forms of cartridges that are detachably mountable to the carriage. In a case in which the ink filled therein is consumed and gone, the recording head can be replaced.
Of the recording heads H1000 and H1001 used in the embodiments below, the basic configuration of the color recording head H1001 will be described with reference to
As illustrated in
The electric connection between the electric wiring tape H1301 and the recording element substrate H1101 is performed by electric bonding of electroplated bumps formed on the electrode portions H1104 of the recording element substrate H1101 and the lead H1304 of the electric wiring tape H1301 by gang bonding.
As illustrated in
Also, electric wiring for supplying electric power to the electrothermal conversion elements H1103, fuses, a logic circuit for driving the electrothermal conversion elements in accordance with recording data, the electrode portions H1104 for externally electrically connecting the portions, and so forth, are formed on the Si substrate H1110. Further, electroplated-bump-shaped electrode terminals H1105 of gold (Au) or the like are formed in the electrode portions H1104. Note that the electrothermal conversion elements H1103 and so forth can be formed using existing film formation technology.
As illustrated in
The configuration of the electrode terminals and bump portions on the element substrate for the recording head according to the present embodiment will be described.
Next, a conventional method of forming electroplated bumps will be described with reference to
As illustrated in
However, in the conventional bonding method in which the electroplated bump and lead are electrically connected, applying the pressure to the electroplated bump using a bonding tool sometimes damaged the bent portion of the protective film layer on the outer side of the electroplated bump (portion 212 in
The process of the protective film layer being damaged and cracks occurring will now be described. The bonding tool applies a load (shock load, pressing load) to the electroplated bump via the lead for electric bonding of the electroplated bump and the lead. The lead and the electroplated bump are crushed by the pressing force applied to the electroplated bump by the bonding tool. Further, the first and second electric wiring layers made of aluminum formed beneath the electroplated bump directly under the lead are also crushed by the pressing force applied to the electroplated bump by the bonding tool. Materials harder than aluminum are used for the thermal storage layer formed below the first electric wiring film and for the silicon substrate, and accordingly these are not crushed under the load applied to the electroplated bump by the bonding tool.
The electroplated bump and the first and second electric wiring films crushed by the pressing force applied to the electroplated bump by the bonding tool will move to the protective film layer side on the outer side of the region where the crushing occurred. At this time, the protective film layer that is formed on the upper side of the second electric wiring film and on the lower side of the electroplated bump, and that adheres to the second electric wiring film and the electroplated bump also moves along with the movement of the second electric wiring film and the electroplated bump. As a result, stress is concentrated at the bent portion of the protective film layer on the outer side of the edge of the electroplated bump, and cracks occur in the protective film layer. In a case of increasing the pressing force at the time of bonding to prevent electric connection defects, such as peeling, fracturing, and so forth, the size and number of cracks occurring in the protective film layer tend to increase.
When cracks are formed at the bent portion of the protective film layer, a problem occurs in that moisture from ink and so forth enters from the cracks, and the electric wiring film made up of aluminum, which was covered by the protective film layer, is corroded. Although a sealant is coated on the electric connection portion in order to protect the electric connection portion from moisture from ink and so forth in the manufacturing process of the recording head, there is a possibility that moisture absorbed by the sealant will enter from the cracks, and cause corrosion of the electric wiring film.
Accordingly, a feature of the present embodiment is that following formation of the thick metal film 210, a resin film layer 211 (elastic resin film) is formed as a second protective film layer, so as to cover the bent portion 212 of the protective film layer 207 on the outer side of the edge of the electroplated bump. When the bent portion 212 of the protective film layer 207 is exposed as in conventional electrode terminal configurations, cracks sometimes occurred at the bent portion of the protective film layer on the outer side of the electroplated bump at the time of batch bonding of the leads to the electroplated bumps on the electrode terminals by gang bonding. However, according to the configuration of the present embodiment, even when cracks are formed at the bent portion of the protective film layer, the cracked portions are protected by the resin film layer 211 that is the second protective film layer. Accordingly, the problem of moisture from ink and so forth, and moisture absorbed by the sealant applied to protect the electric connection portion, entering from the cracks and causing corrosion of the aluminum wiring covered by the protective film layer, can be prevented.
A manufacturing method of the electrode terminal having the configuration of the present embodiment will be described with reference to
In the first embodiment, the formation region of the resin film layer 211 annularly covers the entire region of the bent portion of the protective film layer 207, as illustrated in
Now, there is a bonding step in which a discharge orifice formation member (channel formation member), in which ink channel walls and discharge orifices are formed, is positioned and bonded upon the recording element substrate. In order to increase adhesion at the time of bonding, an adhesion improvement layer is sometimes provided on the recording element substrate. In the present embodiment, this adhesion improvement layer is used as the second protective film layer. That is to say, the adhesion improvement layer is formed on the bent portion of the protection film layer. According to this arrangement, increase in the number of steps by separately disposing the resin film layer as in the first and second embodiments can be prevented.
As described above, according to the configuration of the present embodiment, even though cracks may be formed at the bent portion of the protective film layer at the time of electric bonding of the recording element substrate and the lead by gang bonding, the resin film layer covers and protects the crack portions. Accordingly, the problem of moisture from ink or the like intruding from the cracks and corroding the aluminum wiring covered by the protective film layer can be prevented, and also deterioration in electric reliability and trouble when printing can be prevented. Note that while a case of performing gang bonding has been described in the present embodiment, it is needless to say that the present invention is effective in a case of performing single-point bonding as well.
Also, in the present invention, the manufacturing process of the ink jet recording head may be carried out by with the step of electrically connecting the recording element substrate and the electric wiring substrate first, or by first individually fixing each of the recording element substrate and the electric wiring substrate to a base member, and thereafter performing electric connection of the two.
Further, in the present embodiment, an example is described in which the present invention is applied to the configuration of a color recording head that discharges ink of the three colors of cyan, magenta, and yellow. However, it is needless to say that the same configuration can be used with a black ink recording head. It also goes without saying that the types and numbers of color tones (colors and tones) of the ink used in the recording head can be decided as appropriate.
In addition, a case of applying the present invention to a recording head in which the ink storage portion is inseparably integrated has been exemplified in the present embodiment. However, from the perspective of reduction of the load on electrode terminals, protective layers, and so forth, application may be made to a recording head form in which the ink tank is separably integrated, or in which the ink tank is separate.
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. 2021-064778, filed on Apr. 6, 2021, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-064778 | Apr 2021 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8007076 | Ono | Aug 2011 | B2 |
| 8858812 | Furusawa | Oct 2014 | B2 |
| 20090002453 | Ono | Jan 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 4994968 | Aug 2012 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20220314618 A1 | Oct 2022 | US |
