Method for manufacturing composite body of compound containing cellulose and metal material

Abstract

To provide a method for manufacturing a composite body which has a function of discharging heat generated from an electronic device and a power supply circuit such as a semiconductor device and a sensor connected to a wiring board or a wiring cable of an electric / electronic component, to a shield electrode wire for protecting a semiconductor circuit and an electronic device circuit from external electromagnetic noise, through wiring, and has a heat dissipation function that is difficult to be impaired to curvature and bending of a composite body.SOLUTION: There is provided a method for manufacturing a composite body of a cellulose material and a metal material in which metal material wiring is coated with a compound containing cellulose, shield wiring as a part of the metal material wiring has a heat dissipation function, and the compound containing cellulose has a multilayer structure formed of a plurality of layers having different compositions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wiring board or a wiring cable of an electric / electronic component using a composite of a compound containing cellulose and a metal material.

Background Art

[0002] In recent years, with the progress of wireless communication technology, due to the generation update of wireless communication networks such as those called 5G for example, wireless communication functions are being routinely utilized among various devices such as computers, data servers, electrical and mechanical products equipped with electronic circuits, automobiles, and construction machinery.

[0003] Also, due to the progress of AI technology, the performance requirements for the accumulation of large-scale databases called big data required for the machine learning that forms its basis and for information calculation processing using such databases have increased. For electronic device circuit components such as semiconductor circuit components, sensors, and display elements, which are the core technologies supporting these, miniaturization of circuit processing and speeding up of circuit clocks are required, and heat dissipation design technology for suppressing the temperature rise of the circuit becomes important.

[0004] On the other hand, regarding the materials used in industrial products, not only conventional plastics and polymers that rely on imported oil, but also the development and practical application of natural-derived alternative materials that can be domestically procured are important in view of efforts towards a sustainable society such as responses to SDGs goals and responses to the microplastic problem.

[0005] Patent Document 1 discloses a composite material technology in which functionality is imparted by the composite of fibers and a matrix material for a wiring board using a fiber-reinforced composite material. Patent Document 2 discloses a manufacturing method technology for a wiring board using a cellulose fiber composite film having excellent toughness and high planarity. In Non-Patent Document 1, materials with different functional groups of cellulose molecules and material shapes such as sheet-like, powder-like, and slurry-like are disclosed for cellulose nanofiber materials, and there are descriptions of adding various functions by attaching metal ions or metal nanoparticles to some functional groups.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the application examples of films using cellulose fibers disclosed in Patent Documents 1 and 2, etc., to circuit boards, there is no description regarding the necessity of maintaining the adhesion between the film material and the metal wiring material against bending and flexure of the film, and the adhesion between the film material and the metal wiring material when the shield electrode protecting the circuit from external electromagnetic noise assumes the heat dissipation function from the semiconductor circuit or the electronic device circuit. In the examples of cellulose nanofiber materials disclosed in Non-Patent Document 1, etc., there is no description regarding the adhesion between the cellulose material and the metal wiring material and the combination of different shapes, for example, a sheet-like material and a slurry-like material.

[0009] The present invention relates to a method for manufacturing a structure such as a wiring board or a wiring cable of a flexible electrical or electronic component using a composite of a naturally-derived cellulose material and a metal material, and heat generated from an electronic device such as a semiconductor device or a sensor connected to the wiring board or the wiring cable, or a power circuit is discharged via the wiring to a shield electrode line that protects a semiconductor circuit or an electronic device circuit from external electromagnetic noise, and it is an object to provide a composite in which the heat dissipation function is hardly impaired by bending or curving of the composite.

Means for Solving the Problems

[0010] A composite of a cellulose material and a metal material, in which a metal material wiring is coated with a compound containing cellulose by the manufacturing method of the present invention, a shield wiring which is a part of the metal material wiring has a heat dissipation function, and the compound containing cellulose has a multilayer structure formed in a plurality of layers with different compositions, is used as the means for solving the above problems.

[0011] In the present invention, in the portion where the compound containing cellulose coats the metal material wiring, at least a part of the functional groups of the molecules of cellulose or its derivative compound and the atoms of the metal material have a chemical bond, so that the adhesion between the compound containing cellulose and the metal material wiring in the coated portion is maintained, and even when the composite is bent, means is provided to prevent the shield function or the heat dissipation function from being impaired.

Effects of the Invention

[0012] According to the present invention, it is possible to provide a composite of a cellulose material and a metal material which has a shield mechanism for protecting a semiconductor circuit or an electronic device circuit from external electromagnetic noise and a heat dissipation mechanism from the semiconductor circuit or the electronic device circuit, and in which the heat dissipation function is maintained even when the composite is bent, using a naturally-derived cellulose material.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described. The description given below is a typical embodiment of the present invention, but the present invention is not limited to this embodiment. For example, the functional group of the cellulose molecule described in the following examples is not limited to a carboxyl group, and the metal material is not limited to copper.

Examples

[0015] A composite of a compound containing cellulose and a metal material (hereinafter, also referred to as "the composite of the present invention") according to the manufacturing method of the present invention is composed of a sheet made of cellulose fibers or cellulose nanofibers (hereinafter, also referred to as "cellulose sheet") and a slurry in which cellulose nanofibers are dispersed in a solvent (hereinafter, also referred to as "cellulose slurry"), and a film made of a metal such as copper (hereinafter, also referred to as "metal film"). As described in Non-Patent Document 1, among cellulose nanofiber materials, there are those in which the functional group of the cellulose molecule is substituted with a carboxy group. On the other hand, for example, carboxylato ligands are known to form organometallic complexes with metal atoms. Hereinafter, examples of the present invention will be shown. A cellulose slurry with a concentration of 2% by weight in which carboxyl groups are introduced onto the surface of cellulose nanofiber crystals was applied onto a cellulose sheet with a size of about 5 cm × 8 cm and a thickness of about 0.2 mm and whose surface of cellulose nanofibers was not chemically modified. A copper mesh with a size of about 4 cm × 8 cm and a thickness of about 0.1 mm was placed thereon, and further, the above-mentioned cellulose slurry with a concentration of 2% by weight was applied thereon, and the above-mentioned cellulose sheet was stacked thereon. Next, after applying the above carboxyl group-introduced cellulose slurry, a plurality of copper wirings with a thickness of about 0.1 mm, a width of about 0.5 mm, and a length of about 7 cm are arranged, the above carboxyl group-introduced cellulose slurry is applied thereon, and further, a cellulose sheet that is not chemically modified with a size of about 5 cm × 6 cm and a thickness of about 0.2 mm is superposed thereon. In the composite according to the production method of the present invention, in the cellulose sheet in contact with the metal film, the functional group of the cellulose molecule and the metal atom on the surface of the metal film have a chemical bond, so that the adhesion between the cellulose sheet and the metal film is enhanced. However, it is not preferable for such a cellulose sheet having such a functional group to be in contact with the external environment, for example, from the viewpoint of moisture resistance. In the composite of the present invention, the cellulose sheet is formed of a cellulose material composed of at least two or more layers of cellulose molecules having different functional groups. In FIG. 1, two sets of multilayer cellulose sheets cover the upper and lower sides of a plurality of copper film wirings processed into a tape shape, a copper film is arranged in the lower layer, and a multilayer cellulose sheet is further arranged in the lower layer. The above slurry layer is not described. The copper film in the lower layer may be processed into a mesh shape. Although not shown in FIG. 1, an electronic device component such as a semiconductor circuit component or a sensor is mounted on an uncovered portion provided on the uppermost multilayer cellulose sheet, that is, a portion where the surface of the metal material is exposed without being covered by the cellulose material, and power is supplied to the semiconductor circuit component or signal input / output is performed through the copper film wiring processed into the tape shape. The copper film in the lower layer has a shielding function and a heat dissipation function. Although not shown in FIG. 1, the composite of the present invention has a curved portion in a part thereof, and the shape of the curved portion can be optimized according to the industrial application scene described later.

[0016] Next, another embodiment of the present invention is shown. A cellulose slurry with a concentration of 2% by weight in which carboxy groups are introduced onto the surface of cellulose nanofiber crystals was applied to the surface of a copper wire with a wire diameter of about 1 mm and a length of about 8 cm, and the cellulose sheet was processed into a tape shape with a width of about 0.5 cm and a thickness of about 0.2 mm where the surface of the cellulose nanofiber is not chemically modified, and then used to cover the bandage and dried. In FIG. 2, using the above manufacturing method, a multilayer cellulose sheet processed into a tape shape is used to cover a metal material such as copper processed into a linear or rod shape to form an electric wire shape (hereinafter also referred to as a “coated electric wire”). The above slurry layer is not described. At this time, in the cellulose sheet in contact with the metal film, the functional group of the cellulose molecule and the metal atom on the surface of the metal film have a chemical bond. The cellulose material of the inner sheet has a carboxy group, and the cellulose material of the outer sheet in contact with the external environment containing moisture does not have a carboxy group. A second cellulose slurry was applied and adhered to the surfaces of each of the first composite manufactured by covering the copper wire with a cellulose sheet using the cellulose slurry as an adhesive, and the second composite manufactured in the same manner, and then dried. In FIG. 2, using the above manufacturing method, a plurality of coated electric wires are arranged in a matrix shape, and some of the coated electric wires are used as power supply lines or signal lines, and the other coated electric wires located around the power supply lines or signal lines are used as shield lines and heat dissipation lines. Although not shown in FIG. 2, the composite of the present invention has a curved portion in a part thereof, and the shape of the curved portion can be optimized according to the industrial application described later. Although not shown in FIG. 2, electronic device components such as semiconductor circuit components or sensors or power supply components are mounted on the non-coated portion at the end or in the middle of the composite of the present invention, that is, the portion where the surface of the metal material is exposed without being covered by the cellulose material.

Industrial Applicability

[0017] As an industrial applicability of the composite of the present invention described above, it may be used for the purpose of enhancing electromagnetic noise shielding and heat dissipation of a part of a circuit board incorporated in a computer, a data server, an automobile, a train, a construction machine, an aircraft, a drone, a robot, etc. Also, when introducing electronic devices such as semiconductor circuits and sensors in the future electrification such as IoT in fields and livestock farms, that is, in indoor and outdoor sites, it may be used for the purpose of enhancing electromagnetic noise shielding and heat dissipation. In these industrial applications, it goes without saying that the replacement of some of the conventionally used petroleum-derived materials with the naturally-derived cellulose materials can contribute to the realization of a sustainable society.

Explanation of Signs

[0018] 11 ···· Multilayer cellulose sheet, 12 ···· Metal wiring 13 ···· Shielding and heat dissipation layer 21 ···· Multilayer cellulose sheet, 22 ···· Metal wire 23 ···· Signal line or power line, 24 ···· Shielding and heat dissipation line

Claims

1. A method for manufacturing a composite of a compound containing cellulose or its derivative processed into a sheet, tube, tape, or filament form and a metal material processed into a sheet, mesh, elongated strip, rod, or wire form, comprising coating a part or all of the metal material with a slurry-like compound containing the cellulose or its derivative, and adhering a sheet, tube, tape, or filament compound containing cellulose or its derivative with a composition different from that of the cellulose or its derivative to the coated part. A method for manufacturing a composite of a compound containing cellulose or its derivative and a metal material, characterized by the above.

2. On the surface opposite to the adhesion surface of the metal material of the first compound containing cellulose or its derivative processed into a sheet form coated by adhesion with the metal material processed into the above sheet, mesh, elongated strip, rod, or wire form, a second metal material layer processed into a sheet or mesh form is adhered with a slurry-like compound containing cellulose or its derivative with a composition different from that of the cellulose or its derivative, and further, the second metal material layer is adhered with a compound containing cellulose or its derivative processed into a sheet form with a composition different from that of the third slurry-like compound containing cellulose or its derivative with a slurry-like compound containing cellulose or its derivative. A method for manufacturing a composite of a compound containing cellulose or its derivative and a metal material according to claim 1, characterized by the above.

3. The coating of the metal material processed into a rod or wire form with the compound containing cellulose or its derivative processed into a sheet, tube, or filament form by adhesion is to bandage the metal material with the compound containing the cellulose or its derivative, and the first composite composed of the cellulose or its derivative bandaging the metal material and the metal material and the second composite composed of the cellulose or its derivative bandaging the metal material and the metal material are adhered on the outer surface of the composite with a slurry-like compound containing cellulose or its derivative with a composition different from that of the compound containing the cellulose or its derivative. A method for manufacturing a composite of a compound containing cellulose or its derivative and a metal material according to claim 1, characterized by the above.

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