JP4817936B2 - Liquid discharge head - Google Patents

Description

The present invention relates to a liquid ejection head and a manufacturing method thereof, specifically relates to an ink jet recording heads for performing recording by discharging a recording liquid to the recording medium.

  Conventionally, a flexible wiring board used as an electric circuit board includes, for example, a base film (base material) made of polyimide resin, a wiring layer such as copper foil, a cover coat material made of polyimide resin or a thin film resist material, and bonding them. It is composed of an adhesive for Since this flexible wiring board is a thin and flexible board, it is punched and molded by means such as a mold, a laser, and a drill, and is used in various parts such as a personal computer and an ink jet recording apparatus.

  In many cases, a flexible wiring board is used while being fixedly joined to a support member of a product. For example, it is suitably used as an electric wiring member for a liquid discharge head. When used for a typical inkjet recording head as an application example of a liquid ejection head, mist generated by ink ejection or the like may cause peeling or swelling of the flexible wiring board or elution due to ink depending on the type of ink. There is. For this reason, the method of protecting the end surface (henceforth punching end surface) of the punching part of a flexible wiring board with a sealing agent is taken.

  Patent Document 1 and Patent Document 2 disclose an ink jet recording head in which an end surface of a punched portion of a flexible wiring board as shown in FIG. 1 is protected. Specifically, a thermosetting adhesive or sealant made of an epoxy resin or the like is used for covering the electrical connection portion between the flexible wiring substrate and the discharge element substrate and the punched end surface of the flexible wiring substrate. .

  FIG. 2 is a view showing a state in the vicinity of the electrical connection portion where the flexible wiring board is joined to the support member of the ink jet recording head by a thermosetting adhesive made of epoxy resin or the like.

  2 corresponds to an enlarged view of the vicinity of the electrical connection portion in the AA ′ cross section of the ink jet recording head 100 having the configuration shown in FIG. Referring to FIG. 2, the ejection element substrate 101 includes an orifice plate 106 having an ejection port 105 for ejecting ink and an electrode 107, and the electrode 107 and the electrode 108 of the flexible wiring substrate 102 are electrically connected. ing. Further, the ejection element substrate 101 is fixed to the support member 103 by an adhesive A111.

In the conventional example shown in FIG. 2, the flexible wiring board 102 is first formed into a desired shape by punching with a mold. Next, a thermosetting adhesive B112 made of an epoxy resin or the like is transferred by a transfer plate to a predetermined position on the support member 103 to which the discharge element substrate 101 is bonded. Then, the flexible wiring board 102 is crimped and heated, so that the flexible wiring board 102 and the support member 103 are joined by thermocompression bonding. Next, a thermosetting sealant 110 made of epoxy resin or the like is injected into the electrical connection portion between the ejection element substrate 101 and the flexible wiring substrate 102 by a syringe. Then, the punched end face and the electrical connection portion of the flexible wiring board 102 are covered by curing in a heating furnace.
Japanese Patent Laid-Open No. 10-044418 Japanese Patent Laid-Open No. 2002-19120

  However, in the configuration of an ink jet recording head that has become more complicated in recent years, mounting using the methods of Patent Documents 1 and 2 may be difficult. For example, as shown in FIG. 3, the case where the flexible wiring board 230 and the discharge element substrate are electrically connected on the back surface of the discharge element substrate 210 on which the orifice plate 238 is provided corresponds to this case. In the case of the electrical connection example as shown in FIG. 3, the punched end surface 235 with the flexible wiring substrate 230 must be sealed on the back surface of the orifice plate 238 of the ejection element substrate 210. At the same time, the flexible wiring board 230 must be bonded to both the ejection element substrate 210 and the support member 220. In such a case, it is conceivable that the above-described method by injection cannot provide sufficient coating accuracy with an adhesive. Specifically, since the above-mentioned adhesive is in a liquid state before being cured and has dripping or spreading, it may be difficult to adjust the fine coating shape in the sealing region when mounting on the back surface of the discharge element substrate. is there.

  The inventors of the present invention have made various studies with the aim of optimizing the covering state in sealing the punched end face of the flexible wiring board described above. As a result, we focused on using a hot-melt adhesive from the viewpoint of being solid when mounted.

  The hot-melt adhesive is mainly composed of a thermoplastic resin. The ink jet recording head is usually driven by an electric signal, and thus the ejection element substrate generates heat when the product is used. In particular, in the case of using a heating resistor as an energy generating element as a means for obtaining discharge energy, the discharge element substrate reaches about 80 ° C. when performing normal discharge. For this reason, in the case of using a thermoplastic resin as an adhesive used for mounting an ink jet recording head, ensuring of adhesion reliability has been a concern.

  At the same time, in the configuration as shown in FIG. 3, the punched surface 235 of the flexible wiring board is often in contact with the ink flow path, and the adhesive and the material used for the sealant are strong as well as adhesive. Ink resistance is required.

  The present invention has been made in view of the above problems, and provides a liquid discharge head mounted with an adhesive having excellent heat resistance and ink resistance by optimizing the adhesive state of the flexible wiring board and the covering state of the punched end face. For the purpose.

The present invention provides an ejection element provided with an orifice plate in which an ejection port for ejecting liquid is formed, and a supply port that opens on the back surface of the surface on which the ejection port is provided and supplies the liquid to the ejection port A substrate; a support member having a supply path for supplying a liquid to the supply port; and a flexible wiring board provided with a punching site and transmitting a signal for discharging the liquid to the discharge element substrate; The ejection element substrate is electrically connected to the flexible wiring board at a surface where the supply port opens, and the flexible wiring board is bonded to both the ejection element substrate and the support member by an adhesive, and the punching is performed. The edge of the part is covered with the adhesive, and the punched part where the coating is performed communicates with the supply port. The adhesive is made of a modified polyolefin. A liquid discharge head is a hot melt adhesive having a higher maximum temperature of the softening point of the discharge element substrate during liquid discharge.

  In the present invention, a polyolefin having excellent chemical resistance is modified to increase the adhesive strength with a metal member, and is used for joining and sealing between the flexible wiring board and another member. In addition, since the hot-melt adhesive is a thermoplastic resin, it is melted by heating and instantly joined to various members, so that it can be mounted with high accuracy at a complicated component of the ink jet recording head. In addition, since it uses a heat-meltable adhesive that is thermoplastic but has excellent heat resistance, it has excellent reliability when used.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, components having the same function may be given the same reference numerals in the drawings, and the description thereof may be omitted.

  Further, the following description will be given by exemplifying an ink jet recording head, but the present invention is applicable to a liquid discharge head using a flexible wiring board, and is not limited to the ink jet recording head. For example, in addition to biochip creation and electronic circuit printing, it can also be applied to medical liquid ejection heads for drug ejection.

  FIG. 4 is an external perspective view showing the first embodiment of the ink jet recording head according to the present invention. Referring to FIG. 4, the ink jet recording head of the present invention includes a support member 220, a discharge element substrate 210, and a flexible wiring substrate 230.

  Next, the configuration of the first embodiment of the ink jet recording head of the present invention will be described in detail with reference to FIG.

  FIG. 5 is an enlarged view of the vicinity of the electrical connecting portion of the cross section taken along line BB ′ in FIG.

  Referring to FIG. 5, in the inkjet recording head 200, the ejection element substrate 210 has an ejection port and energy generation elements (not shown) used for ejecting ink arranged on the surface, and an electric signal is sent to the end. An electrode 212 for sending is formed. A penetrating wiring 213 that penetrates the ejection element substrate 210 is provided from the electrode 212, and the wiring is connected to a back electrode 214 formed on the back surface side of the ejection element substrate 210. Under the discharge element substrate 210, a flexible wiring substrate 230 having a wiring layer 231 on a base material 216 is disposed. Bumps 232 are formed on electrode terminals formed by the wiring layer 231 on the upper surface of the flexible wiring board 230. The discharge element substrate 210 and the flexible wiring substrate 230 are provided on the support member 220, and the support member 220 and the wiring layer on the lower surface of the flexible wiring substrate 230 are bonded together by an adhesive 233. The liquid supply port of the ejection element substrate 210 is formed so that the center line of the liquid supply port 234 of the support member 220 and the hole formed by punching the flexible wiring substrate 230 are aligned to communicate with each other. As the adhesive 233 for joining the flexible wiring board 230 to the support member 220, a hot-melt adhesive that is a modified polyolefin is used. At the same time, the punched end surface 235 which is the end of the flexible wiring board 230 on the liquid supply hole 234 side is covered and sealed so as to be completely shielded from the liquid.

  When the hot melt adhesive 233 is melted by heat generated from the ink jet recording head during recording, the adhesive strength is remarkably reduced, the flexible substrate is not sufficiently fixed, and the shape of the punched end face 235 is found. The problem occurs. In order to prevent this, the hot-melt adhesive 233 used in the inkjet recording head of the present invention is required to have a softening point of 80 ° C. or higher, which is the highest temperature achieved during normal use of the inkjet recording head.

[Punching process of flexible wiring board]
The flexible wiring board used in the ink jet recording head of the present invention is provided with a hot-melt adhesive layer mainly composed of polyolefin on the flexible wiring board, and then molded into a desired shape by punching with a mold.

  The punching process of the flexible wiring board is not limited to this, and it is sufficient that a desired meltable adhesive layer is formed on the flexible wiring board, and a hot-melt adhesive layer is formed after punching the flexible wiring board. May be.

  Moreover, the hot-melt adhesive layer should just be formed in the required surface with respect to a flexible wiring board, and should just use it properly with one side and both surfaces as needed.

[Joint and sealing process of flexible wiring board]
With reference to FIG. 6, the manufacturing method of the liquid discharge head of this invention is demonstrated as 2nd embodiment of this invention.

  First, as shown in FIG. 6A, the flexible wiring board 230 on which the hot-melt adhesive layer 237 is formed is disposed at a predetermined position on the support member 220.

  Next, as illustrated in FIG. 6B, the ejection element substrate 210 is disposed at a position where the liquid supply port 236 and the liquid supply hole 234 communicate with each other.

  Next, as shown in FIG. 6 (c), an electrical connection is ensured by applying ultrasonic waves while heating, and then heating is performed from above and below with a heat tool. The flexible wiring substrate 230 and the discharge element substrate 210 and the flexible wiring substrate 230 and the support member 220 are simultaneously bonded by thermal welding, and the punched end surface 235 of the flexible wiring substrate 230 exposed to the liquid supply hole 234 is formed. Cover.

  In this case, when the orifice plate 238 provided on the ejection element substrate 210 is formed of a cured product of a resin composition such as a negative photosensitive resin, the cured product further cures by heating from a heat tool. Can be considered. As a result, there is a concern that the discharge port is deformed and the discharge performance is lowered. Therefore, the heating from the heat tool can be suppressed to a relatively low temperature in consideration of the influence on the orifice plate. For example, when the orifice plate is formed of a cured product of the resin composition, it is desirable to shorten the heating time as much as possible if the heating from the heat tool is equal to or lower than the curing temperature of the resin composition. . Therefore, a material having a softening point equal to or lower than the above-described curing temperature is preferably used for the hot-melt adhesive layer 237.

  Through the above steps, the coated end surface of the flexible substrate 230 is sealed with high accuracy without dripping.

  Next, each component of the hot-melt adhesive used in the present invention will be described.

  In the present invention, the hot-melt adhesive is mainly composed of polyolefin. As the polyolefin, polyethylene, polypropylene, or a modified product thereof is preferably used from the viewpoint of adhesion and chemical resistance. In order to ensure the adhesion of polyolefin, a modifier or various additives can be used.

  Specific examples of the polyolefin as the main component include the following.

  For example, high-pressure polyethylene (LDPE); various linear high-density polyethylenes produced by vapor phase method, solution method, liquid phase slurry method, etc. using Ziegler-type catalyst, Phillips-type catalyst, metallocene-type catalyst ( HDPE), polypropylene, medium density polyethylene (MDPE); linear low density polyethylene (LLDPE) and very low density polyethylene (VLDPE, ULDPE); ethylene-propylene random copolymer or block copolymer, low crystalline ethylene Ethylene / α-olefin copolymers such as butene-1 random copolymer (EBM).

  Examples of the α-olefin of the ethylene / α-olefin copolymer include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene.

  Specific examples of the modifying agent for modifying the polyolefin include the following.

  Unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides or derivatives thereof (eg (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid or their anhydrides or amides, imides, derivatives etc.); hydroxy Hydroxy group-containing polymerizable unsaturated compounds such as alkyl (meth) acrylate; Epoxy group-containing polymerizable unsaturated compounds such as 1-vinyl-3,4-epoxycyclohexene and 3,4-epoxycyclohexylmethyl (meth) acrylate; Isocyanate Isocyanate group-containing polymerizable unsaturated compounds such as modified (meth) acrylate; silane-containing polymerizable unsaturated compounds such as vinyltrimethoxysilane and vinyltriethoxysilane.

  These modifiers may be copolymerized at the time of polyolefin production or may be graft polymerized to the polyolefin.

  Examples of the additive include a pressure-sensitive adhesive, a silane coupling agent, and other polymers.

  Examples of the pressure-sensitive adhesive include petroleum resins, rosin resins, terpene resins, and hydrogenated products thereof. Specific examples of petroleum resins include aliphatic petroleum resins, aromatic petroleum resins, copolymers or hydrogenated products thereof, and the like. Specific examples of the rosin-based resin include natural rosin, polymerized rosin, and derivatives thereof (for example, pentaeryst ester rosin, glycerin ester rosin and hydrogenated products thereof). Specific examples of terpene resins include polyterpene resins, terpene phenol resins, and hydrogenated products thereof.

  Examples of the silane coupling agent include vinyl silane, acrylic silane, epoxy silane, mercapto silane, amino silane, methyl silane, chloro silane, and phenyl silane. Specific examples of vinyl silane include vinyl trichlorosilane, vinyl trimethoxy silane, vinyl triethoxy silane and the like. Specific examples of acrylic silane include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltris (β-methoxyethoxy) silane, and the like. Specific examples of the epoxy silane include β-glycidoxypropyl trimethoxysilane. Specific examples of mercaptosilane include γ-mercaptopropyltrimethoxysilane. Specific examples of aminosilane include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. Specific examples of methylsilane include methyltrimethoxysilane and methyltriethoxysilane. Specific examples of chlorosilane include γ-chloropropyltrimethoxysilane. Specific examples of phenylsilane include phenyltrimethoxysilane.

  Examples of the other polymer include a block copolymer having at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound, or a hydrogenated product thereof. Thing etc. are mentioned. These are block copolymers represented by general formulas A-B; A-B-A; B-A-B-A; A-B-A-B-A and the like. (In the formula, A represents a polymer block mainly composed of a vinyl aromatic compound exhibiting thermoplasticity, and B represents a polymer block composed mainly of a conjugated diene compound exhibiting properties of an elastomer, or the polymer block thereof. The hydrogenated product of Examples of the compound mainly composed of a vinyl aromatic compound constituting the polymer block part A include styrene, α-methylstyrene, vinyltoluene, or a mixture thereof. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, or a mixture thereof. As other polymers, for example, ethylene / vinyl acetate, or saponified ethylene / vinyl alcohol can be used.

  Moreover, the adhesiveness with respect to various members is remarkably improved by using what is generally called an ionomer which mix | blended the metal compound with the copolymer, such as polyolefin mentioned above and unsaturated carboxylic acid.

  Hereinafter, the present invention will be described in more detail with reference to examples.

<Example 1>
According to the embodiment described above (FIG. 6), an ink jet recording head provided with a flexible wiring board was produced. In this example, MODIC-AP (trade name, manufactured by Mitsubishi Chemical Corporation) mainly composed of polypropylene (melting point: 140 ° C.) was used as the hot-melt adhesive layer 237. The heating conditions of the heat tool were 200 ° C. and 120 seconds.

<Evaluation>
In order to evaluate the durability and print quality of the ink jet recording head of Example 1, pure water / glycerin / direct black 154 (water-soluble black dye) = 65/30/5 (mass ratio) was added to each ink jet recording head. Were stored and stored at 60 ° C. for 2 months. It was mounted on an ink jet recording apparatus and A4 size test print was performed. As a result, there was no problem in printing quality. Further, no ink permeation or exudation from the adhesive region of the flexible substrate of the ink jet recording head was observed, and at the same time, the fixing strength did not change.

1 is an external perspective view showing an embodiment of an ink jet recording head (liquid ejection head). FIG. 10 is an enlarged cross-sectional view in the vicinity of an electrical connection portion showing a bonding state of a flexible wiring board in an inkjet recording head (liquid ejection head) of a conventional example. It is typical sectional drawing which shows the example of joining of the flexible wiring board in an inkjet recording head (liquid discharge head). 1 is an external perspective view showing an example of an ink jet recording head (liquid ejection head) according to an embodiment of the present invention. 1 is a schematic cross-sectional view of an ink jet recording head (liquid ejection head) according to an embodiment of the present invention. It is a typical sectional view showing a manufacturing method of an ink jet recording head (liquid discharge head) concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Inkjet recording head 101 Discharge element board | substrate 102 Flexible wiring board 103 Support member 105 Discharge port 106 Orifice plate 107 Electrode 108 Electrode 110 Thermosetting sealing agent 111 Adhesive A
112 Thermosetting adhesive B
200 Inkjet recording head 210 Discharge element substrate 212 Electrode 213 Through wiring 214 Back electrode 216 Base material 220 Support member 230 Flexible wiring substrate 231 Wiring layer 232 Bump 233 Adhesive 234 Liquid supply port 235 Punching end surface 236 Liquid supply port 237 Thermomelting property Adhesive layer 238 Orifice plate

Claims (3)

An ejection element substrate provided with an orifice plate in which an ejection port for ejecting liquid is formed, and a supply port that opens on the back surface of the surface on which the ejection port is provided and supplies the liquid to the ejection port;
A support member having a supply path for supplying a liquid to the supply port; and
A flexible wiring board provided with a punched portion and transmitting a signal for discharging liquid to the discharge element substrate;
Have
The discharge element substrate is electrically connected to the flexible wiring substrate at a surface where the supply port opens,
The flexible wiring board is bonded to both the ejection element substrate and the support member by an adhesive,
The end of the punched portion is covered with the adhesive, and the punched portion where the coating is performed communicates with the supply port,
The liquid discharge head, which is a hot melt adhesive made of a modified polyolefin and having a softening point equal to or higher than a maximum temperature of the discharge element substrate during liquid discharge. Orifice plate, the photosensitive formed by the cured product of the resin, the liquid discharge head according to claim 1, wherein the softening point of the hot melt adhesive is less than the curing temperature of the cured product. The liquid discharge head according to claim 1, wherein the polyolefin is polypropylene.