JP2004356255A - Manufacturing method for high-density wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a board with a high-density wiring more surely and simply. <P>SOLUTION: The manufacturing method for the high-density wiring board contains a process in which a fine mold working is carried out to a mold material and a mold having a specified pattern is manufactured, a process in which the mold is transferred and the board having a non-conductive trench-shaped pattern is manufactured, and a process in which a conductive material is injected into the specified trench of the substrate and the wiring is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a substrate having high-density wiring and a method for manufacturing the substrate.
[0002]
[Prior art]
In order to reduce the size, weight, and cost of information equipment, high-definition wiring manufacturing technology for printed wiring boards is key. At present, a lithography technique is mainly used for manufacturing a substrate having such fine wiring. According to the conventional lithography technology, a metal film is formed on a substrate, a thin resist is applied thereon, exposed to ultraviolet light or the like through a photomask, developed, etched, and the resist is removed. As a result, a wiring is formed. As described above, the production of a substrate having fine wiring requires an extremely large number of complicated steps, and cannot be performed unless a factory is well-equipped. There are also environmental problems such as the generation of a large amount of waste liquid. Further, in order to form a three-dimensional wiring, a punching step and a conductive paste injecting step for conducting between the stacked wirings are also required.
[0003]
In order to solve these problems, a method of drawing wiring directly on a substrate using an inkjet device has been developed (see Patent Document 1). According to this method, the wiring board can be manufactured by simple steps without using a large-scale factory facility. However, variations occur when the wiring material discharged from the inkjet head lands on the substrate, and the dots of the discharged wiring material may be interrupted and disconnected. Cannot be formed at a high density. Therefore, a method of processing a substrate in advance has been proposed (see Non-Patent Document 1). For example, there is a method of irradiating a laser beam only to a portion on a substrate where a wiring is to be formed, and changing the surface characteristics of the portion to a property having an affinity with a wiring material. Alternatively, there is a method of digging a groove on the substrate using a focused ion beam and discharging a wiring material into the groove. However, in the former method, it is necessary to trace the wiring twice on the substrate, that is, the laser beam and the ink jet, and in the latter method, it is necessary to dig a groove with a focused ion beam for each substrate. As described above, each requires a fine and laborious process for each substrate.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H11-274671 [Non-Patent Document 1]
NIKKEI ELECTRONICS 2002.6.17, pp. 67-78
[Problems to be solved by the invention]
An object of the present invention is to provide a method for more reliably and easily manufacturing a substrate having high-density wiring.
[0006]
[Means for Solving the Problems]
The present invention provides a method for manufacturing a high-density wiring board, the method comprising: subjecting a mold material to fine mold processing to produce a mold having a predetermined pattern; Manufacturing a substrate having a non-conductive groove pattern; and injecting a conductive material into a predetermined groove of the obtained substrate to form a wiring.
[0007]
In a preferred embodiment, the fine mold processing is performed by at least one processing means selected from the group consisting of laser processing, focused ion beam processing, cutting processing, and electric discharge processing.
[0008]
In another preferred embodiment, the injection is performed by an inkjet head.
In a preferred embodiment, the width of the wiring is 50 μm or less.
[0010]
In another preferred embodiment, the groove has an aspect ratio of 0.5 or more.
[0011]
In still another preferred embodiment, the transfer is performed by embossing, compression molding, transfer molding, injection molding, or casting.
[0012]
In another preferred embodiment, the substrate includes a portion having a function other than wiring.
[0013]
In a more preferred embodiment, the portion having a function other than the wiring is an insulating layer formed of a space layer.
[0014]
In still another preferred embodiment, the portion having a function other than the wiring is a conductive material layer independent of the wiring.
[0015]
In a preferred embodiment, the high-density wiring board forms a part of a housing or a part of a product.
[0016]
The present invention also provides a high-density wiring board manufactured by any of the above methods.
[0017]
The present invention further provides a high-density wiring board having wiring formed in a groove, wherein the high-density wiring board has a width of the wiring of 50 μm or less and an aspect ratio of the groove of 0.5 or more. It is.
[0018]
In a preferred embodiment, the high-density wiring board has an insulating layer including a space layer.
[0019]
In a more preferred embodiment, the high-density wiring board has a conductive material layer independent of the wiring.
[0020]
In a preferred embodiment, in the high-density wiring board, the wiring and a portion having a function other than the wiring are connected.
[0021]
In a more preferred embodiment, the high-density wiring board forms a part of a housing or a part of a product.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
(High density wiring board)
In the present invention, the high-density wiring board refers to a board having a wiring having a width smaller than the wiring width (about 50 to 70 μm) of a conventional wiring board. Preferably, the width of the wiring is 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. Since the high-density wiring board of the present invention has a narrow wiring width, it can have high-density wiring with respect to the substrate area.
[0023]
The wiring is formed from a conductive material. The conductive material may be any material that is generally used for wiring of a printed wiring board, such as Au, Ag, Ag ₂ O, Pt, In, an In—Ga alloy, Ga, RuO ₂ , IrO ₂ , and OsO _2. , MoO ₂ , ReO ₂ , WO ₂ , solder, Cu, Al and the like.
[0024]
In the high-density wiring board of the present invention, the wiring is formed in a groove provided in the board. This groove has an opening width equal to or smaller than the wiring width, and the depth and shape are not particularly limited. The aspect ratio (groove depth / opening width) of the groove is preferably 0.5 or more, more preferably 1.0 or more. When the wiring has a large aspect ratio, a sufficient cross-sectional area can be obtained even if the width of the wiring is small. Also, if necessary, a part of the groove may penetrate the substrate. In this case, the wiring formed in the through portion plays a role of connecting the upper and lower wirings of the substrate.
[0025]
The material of the substrate of the high-density wiring board of the present invention is not particularly limited as long as it can be transferred from a mold, and a non-conductive material is preferably used. When a conductive material is used, the surface of the substrate may be coated with a non-conductive material. Examples of non-conductive materials that can be used for the substrate include glass, epoxy resin, polyurethane resin, silicone resin, diallyl phthalate resin, formaldehyde resin, phenol resin, amino resin, and ceramics. If necessary, a release agent may be contained.
[0026]
In the present invention, the portion having a function other than the wiring may be a portion having any function, and the function and shape are not particularly limited. Such portions include, for example, an insulating layer composed of a space layer (FIG. 1), a conductive material layer independent of wiring (FIG. 2), and passive components (capacitor, resistor, antenna, etc.) (FIG. 3). Is mentioned.
[0027]
Explaining concretely with an example, in the high-density wiring board 10 shown in FIG. 1A, the space layer 16 provided separately from the wiring 14 is an air layer having a very low relative dielectric constant. A substrate that functions as an insulating layer and can handle high frequencies is obtained. That is, it is possible to reduce noise due to charges induced by a change in current (voltage). Instead of the space layer 16, an insulating layer made of another insulating material having a low dielectric constant may be formed. In addition, the space layer 26 as shown in FIG. 1B can insulate between the upper and lower wirings 24 when the high-density wiring boards 20 are stacked.
[0028]
In the high-density wiring board 30 shown in FIG. 2, a conductive material layer 36 independent of the wiring 34 is provided, and can function as an electromagnetic wave absorber. For example, when the conductive material layer 36 is an antenna element, it is also possible to block only an electromagnetic wave of a specific frequency.
[0029]
In the high-density wiring board 40 shown in FIG. 3, there is a passive component 46 formed in a larger groove in the middle of the wiring 44 formed in the fine groove. In this manner, the high-density wiring board 40 can incorporate the wiring 44 and the passive component 46 into the board 42 at the same time.
[0030]
In the substrate of the high-density wiring board of the present invention, the wiring and a portion having a function other than the wiring may be connected. For example, the wiring and the passive component may be connected directly or by another wiring different from the wiring formed in the groove.
[0031]
Further, the substrate itself may be a housing or a component of a product. In the present invention, the case or part of a product refers to a case or part that can be manufactured by a mold. For example, housings and components of mobile phones and personal computers are mentioned. For example, a part of the back surface of the housing can be used as a high-density wiring board.
[0032]
(Production method of high-density wiring board)
The method for manufacturing a high-density wiring board according to the present invention includes the steps of: subjecting a mold material to fine mold processing to produce a mold having a predetermined pattern; transferring the mold to form a non-conductive groove. A step of manufacturing a substrate having the pattern described above; and a step of forming a wiring by injecting a conductive substance into a predetermined groove of the obtained substrate. Hereinafter, each step will be described in order.
[0033]
In the method of the present invention, first, the mold material is subjected to fine mold processing to manufacture a mold having a predetermined pattern.
[0034]
Mold materials include metals, ceramics, intermetallic compounds, and amorphous carbon.
[0035]
Examples of the metal include Fe, Ni, Cu, Ag, Au, W, and Si, alloys thereof, and stainless steel.
[0036]
Examples of the ceramics include oxides, carbides, nitrides, borides and the like.
[0037]
Examples of the intermetallic compound include TiAl, Ni ₃ Al, NiAl, NiTi, FeSi ₂ , and WC (hard metal).
[0038]
Amorphous carbon is formed, for example, by molding a resin such as a phenol resin, a polyimide resin, an epoxy resin, a polycarbodiimide resin, a furan resin, and a furfural resin, in a non-oxygen atmosphere (in a vacuum or in an inert gas atmosphere such as nitrogen or argon). ), At 500 to 3000 ° C. It is preferable that the amorphous carbon content after firing is 65% by weight or more in order to maintain the flatness of the mold. In particular, amorphous carbon is excellent in the releasability of the substrate.
[0039]
The fine die processing is performed by at least one processing means selected from the group consisting of laser processing, focused ion beam (FIB) processing, cutting processing, and electric discharge processing. It is preferable to perform appropriate combinations in accordance with the size of a pattern to be formed. Examples of the laser processing include excimer laser processing, femtosecond laser processing, a combination of photolithography processing using an Ar laser or He-Cd laser and etching processing, and anisotropic etching of Si or the like. Cutting includes milling, shaving, and the like. In particular, FIB processing is particularly suitable for processing a part which will be a groove mold in which a wiring is to be formed, since a finer and sharper pattern can be obtained as compared with cutting processing, electric discharge processing, laser processing, or the like. After photolithography of the resist material using the laser, the resist material can be cured by heat treatment and used as a mold.
[0040]
As the FIB apparatus, for example, an FIB processing observation apparatus (for example, FB-2000A or the like) manufactured by Hitachi High-Technologies Corporation is used. The variable iris of these devices can be adjusted to form micrometer-sized as well as nanometer-sized patterns.
[0041]
For example, when engraving a pattern using an FIB apparatus, the ceramics, the intermetallic compound, and the amorphous carbon are less susceptible to surface oxidation than metals such as iron, and the accuracy can be maintained. It is preferred.
[0042]
Thus, a mold having a predetermined pattern is manufactured. The mold may be single-sided or both male and female, depending on the transfer method described below. A wiring layout that allows vertical alignment when stacking wiring substrates is provided.
[0043]
Next, the mold is transferred to manufacture a substrate having a non-conductive groove pattern.
[0044]
The transfer may be performed by any means, but is preferably performed by embossing, compression molding, transfer molding, injection molding, or casting.
[0045]
Specifically, the material of the above substrate, dissolved or dispersed in a suitable solvent as needed or melted by heating, using the mold, a method suitable for each material, for example, solvent After transfer of a method such as removal, solidification, hardening, polymerization, melting, sintering, etc., alone or in combination, it is separated from the mold. The supply of the material to the mold is performed by a means usually used by those skilled in the art according to the transfer means. For example, a substrate is prepared by inserting a thermoplastic resin, which has been cut to a predetermined size in advance, between upper and lower molds heated to a predetermined temperature, pressurizing, and then releasing.
[0046]
Thus, a substrate having a groove-like pattern is manufactured. When manufactured from a non-conductive material, it can be used as it is in the next step. When manufactured from a conductive material, it is necessary to further coat a non-conductive substance on the surface of the groove in which the wiring is to be formed. The coating of the non-conductive material can be performed by a method commonly used by those skilled in the art. Further, the obtained substrate may be a part of a housing or a part of a product. Alternatively, if necessary, a pattern for forming a portion having a function other than the wiring may be provided in addition to the groove for forming the wiring.
[0047]
Next, a conductive substance is injected into a predetermined groove of the obtained substrate to form a wiring.
The injection may be performed by any means, but in the present invention, since the groove in which the wiring is to be formed has a very narrow opening width, the injection is preferably performed using an inkjet head having a nozzle having a fine structure. . More preferably, the injection amount from the inkjet head is 4 pL or less, and further preferably 2 pL or less.
[0048]
For the conductive material forming the wiring, metal nanoparticle dispersed ink, metal complex ink, and low melting point metal are generally used, and are dissolved in an appropriate solvent or, in the case of a low melting point metal, are melted by heating to flow. Used for injection as a body. Suitable solvents include butyl carbitol acetate, 3-dimethyl-2-imidazolidine, tetradecane, alcohol, water, xylene and the like.
[0049]
When the substrate is provided with a pattern for forming a portion having a function other than wiring, if necessary, a portion having the function, for example, a conductive material layer independent of wiring, a passive component, and the like. Form. For example, in the case where a concave portion for forming a conductive material layer independent of a wiring is provided, a conductive material may be injected into the concave portion as in the case of forming a wiring. Even when a concave portion (for example, a large groove) for forming a capacitor is provided, a dielectric material may be injected. It is preferable to use an ink jet head for the injection for forming such a portion.
[0050]
In this manner, a substrate having fine wiring with high density and high conductivity can be manufactured. Also, a wiring board provided with a function other than the wiring can be easily manufactured.
[0051]
【The invention's effect】
According to the method for manufacturing a high-density wiring board of the present invention, the high definition and high conductivity that cannot be achieved due to the spread of ink and the difficulty of securing a sufficient wiring cross-sectional area in the direct drawing technique by ink jet are achieved. Wiring boards that can achieve both are obtained by utilizing grooves having a high aspect ratio. Further, a large amount of waste liquid is not generated as in the conventional lithography technology.
[0052]
According to the method of the present invention, the manufacturing process of the mold is a time-consuming process as compared with the direct drawing technology using the ink jet, but it is considered to be the same as the manufacturing process of the masking pattern in the lithography technology. Once the mold is manufactured, mass production of the wiring board is easily possible.
[0053]
In the present invention, by using a mold, it is easy to impart various functions to the substrate itself, and for example, it is also possible to easily incorporate a functional part into the substrate. Therefore, the step of mounting other functional parts later can be simplified. Furthermore, since wiring can be provided on the back surface of the housing of the product and on the surface of the components, the number of components can be reduced, which leads to a reduction in size and weight of the product.
[Brief description of the drawings]
FIGS. 1A and 1B are schematic views of one embodiment of a high-density wiring board of the present invention having an insulating layer composed of a space layer.
FIG. 2 is a schematic view of another embodiment of a high-density wiring board of the present invention having a conductive material layer independent of wiring.
FIG. 3 is a schematic view of still another embodiment of the high-density wiring board of the present invention, which incorporates passive components together with wiring.
[Explanation of symbols]
10 High-density wiring board 12 of one embodiment of the present invention 14 Substrate 14 Wiring 16 Space layer 20 High-density wiring board 22 of another embodiment of the present invention Substrate 24 Wiring 26 Space layer 30 High-density wiring of another embodiment of the present invention Wiring board 32 Substrate 34 Wiring 36 Conductive material layer 40 High-density wiring board 42 of another embodiment of the present invention Substrate 44 Wiring 46 Passive component

Claims (16)

A method for manufacturing a high-density wiring board,
A step of subjecting the mold material to fine mold processing to produce a mold having a predetermined pattern;
Transferring the mold to produce a substrate having a non-conductive groove-shaped pattern; and injecting a conductive material into predetermined grooves of the obtained substrate to form wiring. Including, methods. The method according to claim 1, wherein the fine mold processing is performed by at least one processing means selected from the group consisting of laser processing, focused ion beam processing, cutting processing, and electric discharge processing. The method according to claim 1, wherein the injection is performed by an inkjet head. 4. The method according to claim 1, wherein the width of the wiring is 50 μm or less. The method according to claim 1, wherein an aspect ratio of the groove is 0.5 or more. The method according to claim 1, wherein the transfer is performed by embossing, compression molding, transfer molding, injection molding, or casting. The method according to claim 1, wherein the substrate includes a portion having a function other than wiring. The method according to claim 7, wherein the portion having a function other than the wiring is an insulating layer including a space layer. The method according to claim 7, wherein the portion having a function other than the wiring is a conductive material layer independent of the wiring. The method according to claim 7, wherein the high-density wiring board forms a part of a product housing or component. A high-density wiring board manufactured by the method according to claim 1. A high-density wiring board having wiring formed in a groove, wherein the width of the wiring is 50 μm or less, and the aspect ratio of the groove is 0.5 or more. The high-density wiring board according to claim 12, further comprising an insulating layer including a space layer. The high-density wiring board according to claim 12, comprising a conductive material layer independent of said wiring. The method according to claim 12, wherein the wiring and a portion having a function other than the wiring are connected. The high-density wiring board according to any one of claims 12 to 15, which forms a part of a housing or a part of a product.

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