JP2010000633A - Substrate for inkjet recording head, inkjet recording head, and manufacturing method for inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for an inkjet recording head, capable of obtaining high tightness between an electric power wiring part and a nozzle forming member, and capable of reducing generation of corrosion of the wiring part caused by contact of the wiring part with ink, electrolysis thereof or the like. <P>SOLUTION: This substrate for the inkjet recording head is provided with a heating resistor 103 on a surface of the substrate 101, an electric power wire 130 for supplying electric power to the heating resistor, and an organic layer 111 formed on a surface of the electric power wire. A close contact layer 110 comprising metal having chemical stability lower than that of the electric power wire 130 is provided in a space with respect to the organic layer 111 contacting with the electric power wire 130. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate for an ink jet recording head that performs recording on a recording medium by discharging ink droplets, and an ink jet recording head. Specifically, the present invention relates to an improvement in adhesion between a power wiring for supplying power to a heating resistor element that generates thermal energy for discharging ink droplets and a discharge port forming member that forms a discharge port for discharging ink droplets.

  In recent years, with the advancement of recording technology, there has been a demand for high-speed recording and high image quality in inkjet recording apparatuses. In order to realize this requirement, in addition to increasing the print width of the recording head, the nozzles (also referred to as ejection ports) are arranged with higher density in the inkjet recording head substrate, which is a component of the recording head. It is necessary. Therefore, an increase in the number of heating resistance elements formed on the ink jet recording head substrate and a narrow pitch are achieved. Accordingly, in the power wiring that supplies power to the heating resistor elements, it is necessary to reduce the resistance of the power wiring in order to supply stable and uniform power to each heating resistor element. For this reason, conventionally, in addition to the formation of wiring using a low-resistance material, it has been considered to increase the thickness of the wiring on the substrate.

  As a technique for increasing the thickness of such wiring, there is an inkjet recording head substrate disclosed in Patent Document 1. In this inkjet recording head substrate, power wiring is formed of thick gold (Au) by a plating method to achieve low resistance.

JP 2005-199701 A

  In general, since the power wiring layer formed on the substrate for the inkjet recording head is required to have corrosion resistance, a precious metal such as gold (Au) is used for the material, and the power wiring layer is protected from ink. Therefore, an insulating protective film is formed on the upper layer. As a method of forming this protective film, there is a method of forming an inorganic film such as SiN or SiO by a vacuum film forming technique or the like. However, at present, it is also considered to form an insulating protective film by applying an organic film such as polyimide or a resin such as polyether amide which is an adhesion improving layer of the nozzle forming member using a spin coating method. Here, the reason why an organic material is used as the insulating protective film will be described.

  In an inkjet recording head, an organic film or a resin layer is laminated on a substrate in the process of forming a nozzle forming member for forming an ink flow path or an ink discharge port on the substrate. Therefore, if a film is formed of an organic material on the power wiring layer formed on the substrate, this film can be used as an insulating protective film and a nozzle forming member, thereby simplifying the manufacturing process of the recording head.・ It is possible to reduce material costs.

  However, since the power wiring formed of the noble metal material has high chemical stability, the adhesion with the organic material is poor. For this reason, the adhesion between the nozzle forming member formed of an organic material and the power wiring is low at the interface between the two. Further, when an organic material is used as an insulating protective film for the power wiring layer, the insulating protective film made of an organic material provided on the substrate surface is exposed to ink and swells, or receives stress caused by heating of the heating resistor element. And easily peeled off from the substrate. For this reason, in an ink jet recording head using an organic material as an insulating protective film, ink penetrates between the nozzle forming member and the power wiring layer and enters the wiring portion, and the ink corrodes the wiring portion. And electrolysis occurs.

  The present invention can obtain high adhesion between the power wiring portion and the nozzle forming member, and can reduce the occurrence of corrosion and electrolysis of the wiring portion due to contact between the wiring portion and the ink. An object is to provide a recording head substrate, an ink jet recording head, and the like.

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided a heating resistor that converts electrical energy into thermal energy, a substrate that includes power wiring for supplying power to the heating resistor, and an organic layer that covers the surface of the power wiring. An inkjet recording head substrate provided with an adhesive layer made of a metal having lower chemical stability than the power wiring between the resin layer and the resin layer in contact with the power wiring.

  According to a second aspect of the present invention, there is provided a heating resistor that converts electrical energy into thermal energy, a substrate that has power wiring on the surface for supplying power to the heating resistor, and an organic material formed on the surface of the power wiring. A nozzle forming member comprising: an ink jet recording head that discharges ink from a discharge port formed in the nozzle forming member by heat generated from the heating resistor, the power wiring and the nozzle forming member being An adhesion layer made of a metal different from that of the power wiring is provided therebetween.

  According to a third aspect of the present invention, a step of forming a heating resistor on the surface of the substrate and a power wiring for supplying power to the heating resistor, and a step of providing a nozzle forming member made of an organic material on the surface of the power wiring And a step of forming an ink discharge port and an ink flow path for supplying ink to the ink discharge port. In the method of manufacturing an ink jet recording head, the power wiring is connected between the power wiring and the resin layer. And a step of forming an adhesion layer made of a metal having low chemical stability.

  According to the present invention, in the substrate for an ink jet recording head in which the power wiring portion is arranged on the substrate surface and the resin layer constituting the nozzle also serves as a protective film for the power wiring portion, the power wiring portion and the resin layer It becomes possible to improve the adhesiveness between the two. For this reason, it becomes possible to reduce the peeling of the resin layer from the substrate and the corrosion of the wiring part due to the ingress of ink, and it is possible to provide a durable and highly reliable inkjet recording head substrate and an inkjet recording head. Become.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a view showing the structure of an ink jet recording head substrate according to the present invention.
In FIG. 1, on a silicon substrate 101, a power wiring 130 for supplying power to the recording head, a first electrode pad 120 for electrically connecting the power wiring 130 and the outside, and a surface of the power wiring 130 A protective film 140 is formed to cover (upper surface in the figure). In addition, a nickel plating layer 110 having a lower chemical stability than the power wiring is formed between the protective film 140 and the power wiring 130 as an adhesion layer for bringing the power wiring 130 and the protective film 140 into close contact. Chemical stability refers to the property that the compound does not decompose easily and does not react with other compounds. Further, the adhesion layer (nickel plating layer) 110 is not formed on the electrode pad 120. That is, the adhesion layer 110 is formed only on the surface of the power wiring at a position facing the protective film 140 (below the protective film 140 in the figure). This is for maintaining good reliability of bonding between the first electrode pad 120 and a wiring board (such as a flexible printed circuit board TAB lead) connected thereto. That is, when the nickel plating layer 110 is formed on the electrode pad 120, the electrode pad 120 and an electric wiring board (not shown) are electrically bonded using a method such as bonding. At this time, if the nickel plating layer 110 is provided on the electrode pad 120, the adhesiveness between the electric wiring board and the electrode pad 120 is lowered, and the reliability of electrical bonding may be impaired. Note that in this specification, the lower layer refers to a layer closer to the surface (upper surface in the drawing) side of the substrate than a certain target layer. On the other hand, the upper layer refers to a layer that is further away from the surface of the substrate with respect to a certain target layer.

  As described above, in the present embodiment, the nickel plating layer 110 is formed only on the power wiring surface below the protective film 140. For this reason, without impairing the reliability of the electrical bonding of the first electrode pad 120, the adhesion between the power wiring 130 and a resin layer which is an organic layer described later can be improved, and the resin layer It becomes possible to suppress peeling. As a result, it is possible to reduce the intrusion of ink from the outside into the power wiring 130, it is possible to reduce the corrosion of the wiring portion, and it is possible to provide a highly reliable inkjet recording head substrate.

  Here, the structure of the ink jet recording head substrate 100 shown in FIG. 1 will be described in more detail with reference to FIG. 2 is a cross-sectional view of the inkjet recording head substrate shown in FIG. 1, (a) is a cross-sectional view taken along line AA of FIG. 1, and shows a cross-sectional structure in the vicinity of the electrode pad, (b). It is the BB sectional view of FIG. 1, and has shown the cross-sectional structure of the nozzle vicinity.

  In FIG. 2A, a heat storage layer 102 is formed on the surface of the substrate 101 (upper surface in the drawing), and an aluminum wiring layer 104 is provided on the surface of the heat storage layer 102. A plating conductor 107 is formed on the surface of the aluminum wiring layer 104 via a diffusion prevention layer 106, and a power wiring 130 and an electrode pad 120 are provided on the surface of the plating conductor 107. The power wiring 130 is electrically connected to the plating conductor 107.

  Further, a protective layer 105 is provided between the surfaces of the aluminum wiring 104 and the heat storage layer 102 and the back surface (the lower surface in the drawing) of the diffusion prevention layer 106. Furthermore, a resin layer 111 made of a polyetheramide resin is laminated on the upper layer of the power wiring 130 via an adhesion layer 110, and an ink discharge port 115 and an ink flow path 114 are formed on the surface of the resin layer 111. A nozzle forming member 112 is provided. Further, as shown in FIG. 2B, a heat storage layer 102 made of SiO 2 and a heating resistor layer 103 for converting electric energy into heat energy are formed on a silicon substrate 101, and aluminum is formed thereon. A wiring layer 104 and its protective film 105 are formed.

  In the inkjet recording head substrate configured as described above, the electric power supplied from the outside to the electrode pad 120 is supplied to the heat generating portion 113 through the power wiring 130 and the aluminum wiring layer 104 to cause the heat generating portion 113 to generate heat. . This heat causes the ink in the ink flow path to foam, and ink droplets are ejected from the ejection port by the pressure at the time of foaming.

Next, a method for manufacturing the ink jet recording head according to the first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 3, a heat storage layer 102 made of SiO 2, a heating resistor layer 103 (see FIG. 2B), and an aluminum wiring layer 104 are sequentially formed on a silicon substrate 101. Thereafter, a SiN film to be the insulating protective layer 105 is laminated on the surfaces of the heat storage layer 102 and the aluminum wiring layer 104 by a vacuum film forming method or the like. Then, a through hole 105a for obtaining electrical continuity between a power wiring 130 and an aluminum wiring 104, which will be described later, is formed by photolithography, dry etching technology, or the like. As a result, the power supplied from the power wiring 130 can be supplied to the aluminum wiring 104 through the through hole 105a, and the heat generating portion 113 (see FIG. 2B) connected to the aluminum wiring 104 can be supplied. It becomes possible to generate heat.

  Next, as shown in FIG. 4, a diffusion prevention layer 106 (barrier metal) is formed on the surfaces of the insulating protective layer 105 and the aluminum wiring layer 104. This is performed by depositing the entire surface of a refractory metal material such as titanium tungsten by vacuum deposition or the like.

  Next, as shown in FIG. 5, a plating conductor 107 excellent as a wiring metal is formed on the entire surface of the diffusion prevention layer 106 by vacuum film formation or the like. In this embodiment, gold (Au) is used as the conductor metal. At this time, in order to improve the adhesion between the diffusion preventing layer 106 and the plating conductor layer 107, it is desirable to remove the oxide film by performing reverse sputtering or the like.

  Next, as shown in FIG. 6, a photoresist 108 is applied to the surface of the plating conductor 107 by spin coating. At this time, the photoresist 108 is applied so as to be thicker than the thickness of the power wiring 130 to be formed. For example, when the plating thickness of the power wiring 130 is formed to 15 μm, the photoresist is applied under the condition that the film thickness of the photoresist 108 is 20 μm.

  Thereafter, in order to expose the gold layer of the plating conductor in the portion where the power wiring is to be formed, the portion surrounded by the one-dot chain line in FIG. 6 is removed from the applied photoresist 108. In this removing step, first, resist exposure / development is performed by a photolithography method, and then the photoresist is removed so that the surface of the plating conductor 107 in a portion where the power wiring 130 is formed is exposed. At this time, the remaining photoresist is formed into a shape that will be a plating mold to be applied in the next step.

  Next, in an electrolytic bath of gold sulfite by electrolytic plating, a predetermined current is passed through the gold serving as the plating conductor 130 to deposit gold 109 in a predetermined region not covered with the photoresist 108 (FIG. 7).

  Here, as shown in FIG. 8, the photoresist 108 is again applied to the surface of the power wiring 130 by spin coating. Thereafter, a portion indicated by a one-dot chain line in FIG. 8 is removed from the applied photoresist 108 to expose a gold layer corresponding to a portion where nickel plating is to be formed. In this removal step, first, resist exposure / development is performed by a photolithography method, and then the photoresist 108 is exposed so that the surface of the power wiring 130 in the portion 130a where the nickel plating layer 110 as the adhesion layer is formed is exposed. Remove. At this time, the remaining photoresist 108 is formed into a shape to be a plating mold material to be applied in the next step. The electrode pad 120 is covered with a photoresist 108 so that the nickel plating layer 110 as an adhesion layer is not formed.

  Next, a predetermined current is passed through the power wiring 130 which is a plating conductor in an electrolytic bath of sulfamic acid by an electrolytic plating method, and nickel 110 ( Ni) is deposited (see FIG. 9). After that, the photoresist 108 is removed by immersing the laminate shown in FIG. 9 on which the nickel 110 is laminated in a stripping solution of the photoresist 108 for a predetermined time. As a result, as shown in FIG. 10, the conductive gold (Au) layer for plating on the base including the diffusion prevention layer 106 is exposed.

  Next, using the power wiring 130 as a mask, the plating conductor 107 is immersed in an etching solution containing a nitrogen-based organic compound, iodine, and potassium iodide for a predetermined time, so that the outermost layer of the power wiring 130 and the plating are plated. The conductor 107 is removed by etching (see FIG. 11). Thereby, the diffusion preventing layer 106 (barrier metal) made of a refractory metal material such as TiW is exposed.

  Thereafter, the diffusion preventing layer 106 (barrier metal) made of a refractory metal material such as TiW is immersed in an H 2 O 2 -based etching solution for a predetermined time using the power wiring 130 as a mask. As a result, the exposed diffusion prevention layer 106 made of a refractory metal material is etched and removed (see FIG. 12).

  Thereafter, a resin layer 111 that also functions as an insulating film and a function of improving the adhesion between the flow path forming layer 112 and the power wiring 130 for forming the ink flow path and the nozzle for discharging the ink droplets, It is applied by a spin coat method at an arbitrary thickness. Here, as the resin layer 111, for example, a polyether amide resin is applied with an arbitrary thickness by a spin coat method.

  Further, a resin material for forming the flow path forming layer 112 is applied on the resin layer 111 at an arbitrary thickness from above the post-molded mold material corresponding to the ink flow path. Thereafter, exposure and development are performed by photolithography. As a result, as shown in FIG. 2B, the inkjet recording head substrate in which a plurality of ejection openings 115 for ejecting ink and ink flow paths 114 communicating with the ejection openings are formed (see FIG. 13). Can be obtained.

(Second Embodiment)
Next, a second embodiment of the method for manufacturing an ink jet recording substrate according to the present invention will be described.
Also in the second embodiment, the steps (the steps from FIG. 3 to FIG. 7) until the plated gold layer to be the power wiring is formed by the electrolytic plating method are performed in the same manner as in the first embodiment. However, in the second embodiment, after the steps shown in FIG. 7, the following steps different from those of the first embodiment are performed. That is, in the first embodiment, as shown in FIG. 7, a plating gold layer constituting the power wiring is formed by electrolytic plating, and then a photoresist 108 is applied as shown in FIG. On the other hand, in the second embodiment, after the step shown in FIG. 7, all the remaining photoresist 180 is removed with a stripping solution, and then the photoresist is applied again. Then, the applied photoresist is subjected to resist exposure / development by a photolithography method, and the photoresist is partially removed so as to expose the plated gold layer at the site where the power wiring is formed. Thereby, a resist to be a mold material for nickel plating is formed.

Next, by electrolytic plating, a predetermined current is passed through the gold of the plating conductor in an electrolytic bath of sulfamic acid, and nickel (Ni) 110 is selectively applied to the surface of the gold layer of the plating conductor deposited in the previous step. To precipitate.
Thereafter, the photoresist is removed by immersing it in the photoresist stripping solution for a predetermined time, and the conductive gold (Au) layer for plating and the power wiring layer are exposed.
Subsequently, after removing the plating conductor layer (gold layer) and the diffusion prevention layer by the same process as in the first embodiment, a polyether amide resin is applied to an arbitrary thickness by a spin coating method. Furthermore, a material for forming the flow path forming layer is applied by an arbitrary thickness by a spin coat method, and a plurality of discharge openings for discharging ink by a photolithography method, and an ink flow path communicating with the discharge openings And form. Thereby, an ink jet recording head substrate can be formed.

  As described above, in the second embodiment, after all the photoresist used for forming the power wiring layer is removed, the resist is applied and patterned to form the nickel plating layer again. For this reason, it is possible to selectively form a nickel plating layer including not only the region on the power wiring layer but also the region on the plating conductor layer.

  In the present embodiment, the power wiring and the electrode pad are formed at the same time, and they are connected to each other on the substrate surface. However, as another embodiment, as shown in FIG. 14, the power wiring and the electrode pad can be formed independently and electrically connected by different metal layers under the substrate. It is.

  In the form of the ink jet substrate according to the present embodiment, the adhesion layer 110 formed on the surface of the power wiring 130 is formed of nickel (Ni) which is a metal (base metal) having a chemical stability lower than that of gold. However, for the adhesion layer formed on the surface of the power wiring 130, for example, a gold-nickel alloy containing nickel can be used as a metal having a lower chemical stability than gold (a metal having a high ionization tendency).

  FIG. 15 is a diagram showing the adhesive relationship between the gold-nickel alloy film and the organic film when the nickel concentration in the gold-nickel alloy film is changed. An organic film was formed by spin coating on a gold-nickel alloy film formed by plating on a silicon substrate, and after baking, the adhesion was evaluated by cross-cut peel.

As shown in FIG. 15, when the nickel content in the gold-nickel alloy constituting the adhesion layer increases, the adhesion between the adhesion layer and the resin layer that is an organic film is improved. This is considered to be due to the fact that gold which is excellent in chemical stability contains nickel, which is a base metal, becomes chemically active and improves the adhesion to the organic film.
In this example, when the nickel content in the gold-nickel alloy was 1.4 wt% or more, the adhesion between the resin layer, which is an organic film, and the adhesion layer was good. In addition, when the nickel content was 0.3 wt% or less, sufficient adhesion was not obtained between the resin layer and the adhesion layer. In FIG. 15, a circle indicates a state with high adhesion, and a cross indicates a state with low adhesion.

  As described above, since the gold-nickel alloy layer constituting the adhesion layer has a nickel content equal to or higher than a certain threshold value, it becomes possible to improve the adhesion between the power wiring and the resin layer protecting the resin. It becomes possible to suppress peeling of the layer. For this reason, the reliability of the ink jet recording head substrate and the ink jet recording head using the same is greatly improved.

1 is a perspective view schematically showing an embodiment of an ink jet recording head substrate according to the present invention. 2A and 2B are cross-sectional views of the inkjet recording head substrate illustrated in FIG. 1, in which FIG. 1A is a cross-sectional view taken along line AA, and FIG. It is sectional drawing which shows typically the manufacturing method of the board | substrate for inkjet recording heads shown in FIG. 1, and has shown the state in which the heat storage layer, the aluminum wiring layer, and the insulating protective layer were formed on the board | substrate. It is sectional drawing which shows typically the state which formed the diffusion prevention layer in what was shown in FIG. It is sectional drawing which shows typically the state which formed the conductor for plating in what was shown in FIG. It is sectional drawing which shows typically the state which apply | coated the photoresist to what was shown in FIG. It is sectional drawing which shows typically the state which formed the power wiring in what was shown in FIG. It is sectional drawing which shows typically the state which apply | coated the photoresist to what was shown in FIG. It is sectional drawing which shows typically the state which formed the contact | adherence layer in what was shown in FIG. FIG. 10 is a cross-sectional view schematically showing a state where the photoresist is removed from what is shown in FIG. 9. It is sectional drawing which shows typically the state which removed the conductor for plating from what was shown in FIG. It is sectional drawing which shows typically the state which removed the diffusion prevention layer from what was shown in FIG. It is sectional drawing which shows typically the state which formed the resin layer and the nozzle formation member in what was shown in FIG. It is sectional drawing which shows typically the structure in other embodiment of the board | substrate for inkjet recording heads which concerns on this invention. In embodiment of this invention, it is a table | surface which shows the adhesiveness of a gold- nickel alloy film and a resin layer when changing the nickel concentration in a gold- nickel alloy film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Silicon substrate 102 Thermal storage layer 103 Heating resistor layer 104 Aluminum wiring layer 105 Protective film 106 Barrier metal layer 107 Conductor for plating 108 Photoresist 110 Adhesion layer 111 Resin layer 112 Nozzle formation member 113 Heat generating part 114 Ink flow path 115 Discharge port 120 Electrode pad 130 Power wiring part 140 Resin protective film

Claims (10)

An inkjet recording head substrate comprising a heating resistor that converts electrical energy into thermal energy, a substrate that has power wiring on the surface for supplying power to the heating resistor, and an organic layer that covers the surface of the power wiring. And
An ink jet recording head substrate comprising an adhesion layer formed of a metal having lower chemical stability than the power wiring between the organic layer in contact with the power wiring.   2. The ink jet recording head substrate according to claim 1, wherein the power wiring is made of a noble metal.   3. The ink jet recording head substrate according to claim 1, wherein the adhesion layer is made of a base metal.   4. The ink jet recording head according to claim 1, wherein the adhesion layer is made of an alloy of a base metal and a noble metal.   The said adhesion layer forms nickel (Ni) or the gold- nickel alloy layer which has nickel content of 1.4 wt% or more by a plating method, The Claim 1 thru | or 4 characterized by the above-mentioned. Inkjet recording head substrate.   2. The ink jet recording head substrate according to claim 1, wherein the organic layer has a resin layer formed of a polyetheramide resin. A heating resistor that converts electrical energy into thermal energy, a substrate that has power wiring on the surface for supplying power to the heating resistor, and a nozzle forming member made of an organic material formed on the surface of the power wiring, An ink jet recording head that ejects ink from an ejection port formed in the nozzle forming member by heat generated from the heating resistor;
An inkjet recording head comprising an adhesion layer made of a metal different from the power wiring between the power wiring and the nozzle forming member. Forming a heating resistor on the surface of the substrate and power wiring for supplying power to the heating resistor;
In a method for manufacturing an ink jet recording head, comprising: a step of providing a nozzle forming member made of an organic material on a surface of the power wiring; and a step of forming an ink discharge port and an ink flow path for supplying ink to the ink discharge port. ,
Forming an adhesion layer made of a metal having lower chemical stability than the power wiring between the power wiring and the resin layer;
An ink jet recording head manufacturing method comprising: The step of forming the power wiring includes:
After applying a photoresist to the plating conductor layer formed on the substrate, the photoresist located on the portion where the power wiring is to be formed is removed to remove the photoresist on the substrate and thereby form a plating mold. Forming a step;
Forming a power wiring by depositing a noble metal by a plating method in a plating mold formed of the photoresist,
The step of forming the adhesion layer includes
Forming a mold for plating with the photoresist remaining on the substrate by applying a photoresist to the surface of the power wiring and then removing the photoresist corresponding to the nozzle forming member; and
Forming an adhesion layer by depositing a base metal by a plating method in a mold for plating formed by the photoresist;
The method of manufacturing an ink jet recording head according to claim 8, comprising: The step of forming the power wiring includes:
After applying a photoresist to the plating conductor layer formed on the substrate, the photoresist located on the portion where the power wiring is to be formed is removed to remove the photoresist on the substrate and thereby form a plating mold. Forming a step;
Forming a power wiring by depositing a noble metal by a plating method in a plating mold formed of the photoresist,
The step of forming the adhesion layer includes
Removing the photoresist remaining on the substrate after the power wiring is formed;
A step of forming a mold for plating with the photoresist remaining on the substrate by removing the photoresist at least corresponding to the nozzle forming member after applying the photoresist to the surface of the substrate and the power wiring When,
Forming a base metal layer by depositing a base metal in a plating mold formed of the photoresist by a plating method;
The method of manufacturing an ink jet recording head according to claim 9, comprising:

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