JP4689313B2 - Wiring sheet manufacturing method - Google Patents

Description

The present invention requires a large number of wires, a method of manufacturing a wiring sheet to be used in particular to a wiring board suitably used for a flat panel display having a large screen.

  In a flat panel display such as a plasma display (PDP), a display using a planar electrode type electron-emitting device, or an active matrix liquid crystal display using a thin film transistor (TFT), as a method of forming wirings arranged on a substrate Is a method in which a conductive material and an insulating material are printed on a substrate in a predetermined pattern shape, and a conductive material mixed with a photosensitive material is applied to the entire surface of the substrate and patterned by pattern exposure and development. In general, a low resistance metal material such as copper or aluminum is deposited on a substrate by a vacuum process such as sputtering, a metal thin film is formed, and patterning is performed by photolithography. is there.

  For example, Patent Document 1 discloses a multilayer wiring structure in which a lower wiring surface is anodized and insulated as an insulating layer between mutually intersecting wirings.

Japanese Patent Laid-Open No. 10-133231

  As the screen size of the display increases and the number of high-definition patterns, that is, the number of pixels increases, the wiring pattern formation process on the substrate becomes complicated and the required accuracy increases. Therefore, it is difficult to guarantee the quality when forming the conductive layer and the insulating layer, and the yield at the time of forming each layer is lowered, so that there is a problem that the overall yield is lowered. In general, formation of each layer involves a high-temperature heating process, and the substrate is repeatedly heated. Therefore, substrate deformation and thermal damage to the layer forming material are serious problems. In addition, when the wiring length becomes longer as the screen becomes larger, the wiring resistance causes a voltage drop at the center of the screen, causing variations in the brightness of the screen, slowing down the response and not following the video There was a problem.

  Therefore, in order to reduce the wiring resistance, measures such as using a material with low electrical resistance as the wiring material or increasing the cross-sectional area of the wiring are taken, but the current technology is satisfactory. Absent.

In a method in which a conductive material is directly applied as a conductive paste by screen printing or a method in which a conductive paste in which a photosensitive material and a conductive material are mixed is applied on a substrate and then patterned, the resistance of the conductive paste is reduced by the conductive material. It will be twice as large. For example, when the conductive material is silver, the resistance value is about 1.6 × 10 ⁻⁸ Ω · cm. When the conductive material is a conductive paste, 5 × 10 ⁻⁸ to 8 × 10 ⁻⁸ Ω · cm. It will be about. In addition, if the conductive paste is repeatedly printed to increase the cross-sectional area of the wiring, the accuracy is lowered and the manufacturing cost is increased. There is also a problem in terms of flatness.

  In addition, in a method in which a conductive material is formed into a thin film by a vacuum process such as sputtering, and patterning is performed by mask exposure and etching, a film thickness that can be deposited by sputtering can be secured only about 0.1 to 0.2 μm.

  The object of the present invention is to solve the above problems and provide a technique for accurately forming a low-resistance wiring corresponding to high definition and large screen of a flat panel display by a low temperature process, and a highly reliable wiring sheet. And providing a wiring board.

  1st of this invention is a manufacturing method of a wiring sheet, Comprising: The 1st ceramic film which has an uneven | corrugated shape on the surface by anodizing the metal foil processed into the predetermined pattern shape in the suspension of an inorganic filler Next, a second ceramic film is formed by a sol-gel method as a base material, and a wiring composed of a conductive layer having a predetermined pattern shape is formed on at least one surface of the base material. To do.

In the said manufacturing method, the following structure is included as a preferable aspect. That is, the metal foil is any one of aluminum, titanium, tantalum, and alloys thereof , the inorganic filler is any one of TiO ₂ and SiO ₂ , and the metal foil is processed by photolithography and etching. be by law, it is to form on the substrate by plating the conductive layer.

In the method for manufacturing a wiring sheet of the present invention, since the wiring can be formed by a plating method, it is possible to form a thick film wiring having the inherent low resistance of the conductive material. Specifically, a wiring having a thickness of 10 to 100 μm can be formed with low resistance using copper or silver. Further, in the wiring substrate using the wiring sheet produced by the present invention, since the surface of the wiring of the insulating substrate side is covered with a substrate having a ceramic coating having good insulation and high heat resistance, due to the discharge Circuit damage is prevented, and it can sufficiently withstand high temperature processes. Therefore, according to the present invention, it is possible to configure a highly reliable large-screen and high-definition display.

This onset Ming, a metal foil of the first ceramic coating provided on the surface by anodic oxidation in a suspension of the inorganic filler, then a second ceramic coating is provided by a sol-gel method, further, on the coating film Ru manufacturing method der wiring sheet forming the wiring.

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

Figure 2 is a preferred cross-sectional view schematically showing a step of embodiments view of a manufacturing method of the present onset Ming wiring sheet, in the figure, 1 is a metal foil, 2 a photosensitive resist film, 3 is a photomask, the resist 4 5 is a through hole, 6a is a first ceramic coating by an anodic oxidation method, 6b is a second ceramic coating by a sol-gel method, 7 is a substrate made of the metal foil 1 and ceramic coatings 6a and 6b, and 8 is photosensitive. 10a, 9b are resists, 12a, 12b are wiring, and 13 is a wiring sheet. In FIG. 2, only a cross section is shown for convenience.

  In the method for manufacturing a wiring sheet of the present invention, first, a metal foil 1 processed into a predetermined pattern shape is prepared. By the processing, a wiring board is formed using the wiring sheet, and further, a through hole 5 for making an electrical connection required when a device such as a display is configured using the wiring board is formed.

As the metal foil 1 used in the present invention, aluminum, titanium, tantalum or the like is preferably used, and these metals alone or two or more alloys selected from these metals are preferably used. Moreover, as thickness of this metal foil 1, 5 micrometers or more are preferable and 30 micrometers or more are preferable when handling property is considered. Moreover, as an upper limit, 500 micrometers or less are preferable. Is not particularly restricted but includes the processing method of the metal foil 1, a press method, etc. are also used, but from the viewpoint of accuracy, it is preferred the method according to photolithography method and an etching method, showing the step in FIG. That is, a photosensitive resist film 2 on both sides of the metal foil 1 was laminated, exposed to light through the same photomask 3 [FIGS. 2 (a)], a resist 4 of a predetermined pattern and developed [2 ( b)]. Next, the metal foil 1 is etched using the resist 4 as a mask to form a predetermined pattern (for example, a through hole 5) [FIG. 2 (c)].

  The processed metal foil 1 is anodized to form a first ceramic film 6a on the surface.

In the present invention, the anodic oxidation of the metal foil 1 is performed in an inorganic filler suspension. Thereby, the inorganic filler contained in the suspension forms the porous first ceramic coating 6 a on the surface of the metal foil 1. The inorganic filler used in the present invention is preferably TiO ₂ or SiO _{2 and} preferably has a filler diameter of 10 μm or less, more preferably 1 μm or less. The shape is preferably granular or piece-like. As the liquid for suspending the inorganic filler, an aqueous solution of silicate or sulfate is preferably used, and these inorganic fillers are used in the suspension at a rate of 10 to 200 g / L. A commercially available suspension is also preferably used. For example, “Ceraplating SI-001” (trade name; SiO ₂ concentration = 180 g / L) manufactured by Dipsol is used. As an anodic oxidation condition, a SiO ₂ film having a thickness of 25 μm can be obtained in 0.5 A / dm ² , 250 V for 10 minutes. The thickness of the first ceramic coating 6a according to the present invention is preferably 10 μm or more, and can be adjusted by the voltage and time of anodization.

  Next, a second ceramic coating 6b is formed on the surface by a sol-gel method.

  In the present invention, the formation of the ceramic coating by the sol-gel method is performed by immersing the metal foil 1 on which the first ceramic coating 6a is formed in a solution containing a metal cation, and then preheating at around 250 ° C. to remove the solvent. Then, by firing at around 400 ° C., a ceramic film having a uniform and excellent insulating property and degassing property and having a concavo-convex shape necessary for conductor formation is formed. In this method, a film thickness of 2 to 3 μm is obtained by several times of application and baking. Examples of the sol-gel liquid include “Ceramate CIP” manufactured by Catalyst Kasei Kogyo Co., Ltd.

The metal foil 1 having a two-layer ceramic film formed on the surface by the above steps is used as the base material 7 according to the present invention [FIG. 2 (d)].

In the present invention, the wiring is formed on at least one surface of the base material 7 having the predetermined pattern shape obtained in the above process. FIG. 2 shows a process of forming predetermined wirings on both sides.

Photosensitive resist films 8 are laminated on both surfaces of the base material 7, and exposed through photomasks 9a and 9b corresponding to the wiring patterns to be formed respectively (FIG. 2 (e)), and resists 10a and 10b having predetermined patterns. [FIG. 2 (f)]. Next, after the wirings 12a and 12b are formed by the through-hole plating method [FIG. 2 (g)], the resists 10a and 10b are removed and the wirings 12a and 12b having a predetermined pattern shape are arranged on the substrate 7. The wiring sheet 13 of the invention is obtained [FIG. 2 (h)].

  In the present invention, as a method for forming the wirings 12a and 12b, a paste method, a vapor deposition method, a metal foil laminating method, or the like can be used, and a photolithography method or the like is also used if necessary. According to the hole plating method, the inherent resistivity of the metal can be obtained as the wiring resistance. Therefore, the low resistance wiring can be freely formed on both surfaces of the substrate 7 as compared with the vapor deposition method or the printing method using the paste. Can be preferred.

In the present invention, as a metal species applied to the plating method, nickel (specific resistance = 6.9 × 10 ⁻⁸ Ω · m) or copper (specific resistance = 1.7 ×) in relation to the specific resistance. 10 ⁻⁸ Ω · m), gold (specific resistance = 2.6 × 10 ⁻⁸ Ω · m), silver (specific resistance = 1.6 × 10 ⁻⁸ Ω · m) and the like are preferably used.

  In the plating method, since the surface of the base material 7 is insulative, a conductive treatment is required once. For example, by performing an immersion treatment with a “melt plate activator 331 solution” manufactured by Meltec, A Pd film is formed on the surface of the second ceramic coating 6 b of the substrate 7. Next, the Ni layer can be formed by electroless plating by immersing the base material 7 on which the Pd film is formed in “Melplate Ni-802 solution” manufactured by Meltex.

In the present invention, specifically as a method of forming the wiring 12a, 12b other than the plating method, for example, conductive layer by vacuum laminating a whole surface metal foil on at least one surface of a substrate 7 shown in FIG. 2 (d) It is also possible to laminate a photosensitive resist film on the conductive layer, expose and develop through a photomask, obtain a resist with a predetermined pattern, and etch the resist as a mask to form a wiring shape. .

In FIG. 2 , the wirings 12 a and 12 b are insulated from each other through the base material 13, but can be electrically connected through the through hole 5 by the pattern of the resists 10 a and 10 b.

  The wiring board of the present invention is obtained by superimposing the wiring sheet of the present invention manufactured as described above on an insulating substrate having a conductive layer having a predetermined pattern shape in which necessary conductive members such as electrodes and wiring are formed. It is configured by electrically connecting the wiring of the wiring sheet and the conductive layer on the insulating substrate. Further, the surface of the insulating substrate and the wiring are bonded as necessary.

  The insulating substrate used for the wiring substrate of the present invention is an insulating substrate used for a normal wiring substrate, and a glass substrate or a plastic substrate is preferably used. The conductive layer formed on the insulating substrate is a conductive member such as an element electrode, and is a member provided by a conductive material and a manufacturing method that are used in a conventional wiring substrate.

  In the present invention, an adhesive is preferably used as the electrical connection between the wiring of the wiring sheet and the conductive layer on the insulating substrate and the method of joining the insulating substrate surface and the wiring. Adhesives shall not deteriorate during heat treatment in the subsequent process, have sufficient electrical conductivity, and do not generate gas that adversely affects the performance of the device in the final form display device using such a wiring board. For example, a baked type silver paste material is preferably used. Further, when the difference in thermal expansion coefficient between the adhesive and the insulating substrate 1 is large, the insulating substrate 1 may be warped or the adhesive may be peeled off by the heat treatment in the subsequent process. It is desirable that the difference in thermal expansion coefficient between the agent and the insulating substrate 1 is as small as possible.

  Adhesive is applied to the insulating substrate using a dispenser, ink-jet method, screen printing, etc., in a line or dot form corresponding to the connection or joining location of the wiring, and a wiring sheet is placed on it. Baked to solidify the adhesive. Further, after the wiring sheet is overlaid on the insulating substrate, an adhesive may be applied to the through hole of the wiring sheet to perform connection and bonding. A plurality of methods may be used in combination.

FIG. 1 shows a schematic cross-sectional view of the process when connecting through the through hole 5. In the figure, 14 is an insulating substrate, 15 is a conductive layer, 16 is a conductive adhesive, and 17 is a contact portion. The wiring sheet of the present invention is overlaid with the wiring 12b facing the substrate 14 side (FIG. 1 (a)), and an adhesive 16 is applied by the ink jet method through the through hole 5 (FIG. 1 (b)) and fired. As a result, the contact portion 17 is formed to electrically connect the wiring 12b and the conductive layer 15 [FIG. 1 (c)]. In this case, an adhesive may be applied to the surface of the conductive layer 15 in advance, and the conductive layer 15 and the wiring 12 may be directly connected at the contact surface.

  In the present invention, it is also possible to electrically connect the wiring 12 a on the front side of the wiring sheet 13 and the conductive layer 15 on the insulating substrate 14 through the through hole 5 of the wiring sheet 13.

Example 1
A wiring sheet and a wiring board were produced according to the steps of FIGS.

A photosensitive dry film (resist film) having a thickness of 30 μm was laminated on both sides of an aluminum foil having a thickness of 50 μm, and exposed with the same photomask on both sides, thereby producing a latent image. Next, after developing with 5% sodium carbonate solution to obtain a resist, the aluminum foil was etched with 10% hydrochloric acid to form through holes, and the resist was peeled off with caustic soda. The aluminum foil processed into a predetermined pattern shape is anodized with a suspension of SiO ₂ (“Cera-plated SI-001” manufactured by Dipsol) to form a first ceramic film having a thickness of 5 μm on the surface. Then, a SiO ₂ film (catalyst-formed ceramate CIP series) is formed by a sol-gel method by an immersion method, a preheating step is repeated 5 times at 250 ° C., and baked at 400 ° C. A 2 μm SiO ₂ film was formed as a second ceramic coating to obtain an insulating substrate.

  The substrate is immersed in Meltex Ni-802 solution made by Meltex, treated with palladium catalyst, and then a 30 μm thick photosensitive dry film is laminated on both sides and exposed through different photomasks on the front and back. A latent image was produced. Next, after developing with 5% sodium carbonate to obtain a resist, a copper plating film having a thickness of 5 μm including the through hole was formed by electroless copper plating. The dry film was removed with caustic soda to obtain the wiring sheet of the present invention.

  A glass substrate was used as the insulating substrate, and predetermined element electrodes were formed on the glass substrate. Alignment is performed so that the wiring of the wiring sheet is connected to the element electrode, the wiring sheet and the glass substrate are temporarily bonded, and then a silver paste for bonding is applied to the through hole by an ink jet method to wire the wiring sheet. And the device electrode were connected to obtain a wiring board of the present invention. In the obtained wiring board, the wiring sandwiched between the glass substrate and the base material exhibits high conductivity, and is covered with an insulating base material, so that it is damaged by electric discharge and intersects via the base material. Short-circuiting with the wiring on the opposite side was well prevented.

(Example 2)
As a wiring forming process, a copper foil with a thickness of 30 μm is vacuum-laminated on both surfaces of a base material, and then a photosensitive dry film is laminated, exposed and developed through a photomask to form a resist, and second chloride A wiring sheet and a wiring board were produced in the same manner as in Example 1 except that the copper foil was etched with an iron solution and patterned into a desired pattern shape, and similar effects were obtained.

(Example 3)
In Example 1, the ceramic coating and the conductive layer were variously changed to compare the insulating properties of the ceramic coating. A schematic configuration of the measurement system is shown in FIG. In the figure, 31 is a metal foil, 32 is a ceramic coating, 33 is a conductive layer, and 34 is an insulation tester. The results are shown in Table 1. The evaluation criteria are as follows.
A: MΩ or more Δ: kΩ to MΩ
×: Leakage (display = 0Ω)

It is process drawing of an example of the manufacturing method of the wiring board of this invention. It is process drawing of one Embodiment of the manufacturing method of the wiring sheet of this invention. It is the schematic which shows the system which measures the insulation of a ceramic film in the Example of this invention.

It is process drawing of one Embodiment of the manufacturing method of the wiring sheet of this invention. It is process drawing of an example of the manufacturing method of the wiring board of this invention. It is the schematic which shows the system which measures the insulation of a ceramic film in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal foil 2 Photosensitive resist film 3 Photomask 4 Resist 5 Through hole 6a, 6b Ceramic coating 7 Base material 8 Photosensitive resist film 9a, 9b Photomask 10a, 10b Resist 12a, 12b Wiring 13 Wiring sheet 14 Insulating substrate 15 Conductive layer 16 Adhesive 17 Contact portion 31 Metal foil 32 Ceramic coating 33 Conductive layer 34 Insulation tester

Claims (5)

  A method for producing a wiring sheet, in which a metal foil processed into a predetermined pattern shape is anodized in a suspension of an inorganic filler to form a first ceramic film having a concavo-convex shape on a surface, and then a sol-gel A method for producing a wiring sheet, comprising: forming a second ceramic film by a method as a base material; and forming a wiring made of a conductive layer having a predetermined pattern shape on at least one surface of the base material.   The method for producing a wiring sheet according to claim 1, wherein the metal foil is any one of aluminum, titanium, tantalum, and alloys thereof. The method for manufacturing a wiring sheet according to claim 1, wherein the inorganic filler is any one of TiO ₂ and SiO ₂ . The manufacturing method of the wiring sheet as described in any one of Claims 1-3 by the process of the said metal foil by the photolitho method and an etching method. The manufacturing method of the wiring sheet as described in any one of Claims 1-4 which forms the said conductive layer on a base material by the plating method.

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