Composite between compound containing cellulose and metallic material

Abstract

To provide a composite having a function of releasing heat generated from a power supply circuit and electronic devices such as semiconductor devices and sensors, connected to the wiring board or wiring cable, through the wiring, to a shield electrode line that protects semiconductor circuits and electronic device circuits from external electromagnetic noise, and being not easily damaged by bending or curvature of the composite.SOLUTION: A composite of cellulose materials and metal materials is formed by coating metal material wiring with a compound containing cellulose, where the 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 by multiple layers with different compositions.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a structure such as a wiring board or wiring cable for electric / electronic components, which is made of a composite of a cellulose-containing compound and a metal material. [Background technology]

[0002] In recent years, with the advancement of wireless communication technology, for example with the upgrade of wireless communication networks called 5G, wireless communication functions are being used on a daily basis between a variety of devices, such as electronic computers, data servers, electrical and mechanical products that are equipped with electronic circuits, automobiles, and construction machinery.

[0003] Furthermore, advances in AI technology are driving increased demand for the accumulation of large-scale databases known as "big data," which is necessary for the machine learning that underpins AI technology, as well as for the performance requirements for information processing using these databases. This will require the miniaturization of circuit processing and faster circuit clocks for the core technologies that support these technologies, such as semiconductor circuit components and electronic device circuit components such as sensors and display elements, and will also make heat dissipation design technologies that suppress temperature increases in circuits important.

[0004] On the other hand, when it comes to materials used in industrial products, in addition to the conventional plastics and polymers that rely on petroleum imports, it is important to develop and put into practical use natural alternative materials that can be procured domestically, in light of efforts toward a sustainable society, such as responding to the SDGs and addressing the problem of microplastics.

[0005] Patent Document 1 discloses a composite material technology for a wiring board using a fiber-reinforced composite material, in which functionality is imparted by combining fibers with a matrix material. Patent Document 2 discloses a manufacturing method for a wiring board using a cellulose fiber composite film that has excellent toughness and high flatness. Non-Patent Document 1 discloses cellulose nanofiber materials with different functional groups on the cellulose molecules, and describes attaching metal ions or metal nanoparticles to some of the functional groups to add various functions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication 2010-180416 [Patent Document 2] Patent Publication No. 2017-78151 [Non-patent literature]

[0007] [Non-Patent Document 1] Kansai Bureau of Economy, Trade and Industry website "List of cellulose nanofiber related sample offers" Summary of the Invention [Problem to be solved by the invention]

[0008] In the application examples of films using cellulose fibers to circuit boards disclosed in Patent Documents 1 and 2, etc., there is no description of the adhesion between the film material and the metal wiring material when the film is curved or bent, or the need to maintain the adhesion between the film material and the metal wiring material when a shield electrode that protects the circuit from external electromagnetic noise is assigned the function of dissipating heat from a semiconductor circuit or an electronic device circuit. In the case of cellulose nanofiber materials disclosed in Non-Patent Document 1 and elsewhere, there is no description of the adhesion between the cellulose material and the metal wiring material.

[0009] The present invention has an object to provide a flexible structure, such as a wiring board or wiring cable for electric / electronic components, which uses a composite of a naturally derived cellulose material and a metal material, and which has a function of dissipating heat generated from electronic devices such as semiconductor devices and sensors and power circuits connected to the wiring board or wiring cable, via the wiring, to a shield electrode wire that protects the semiconductor circuits and electronic device circuits from external electromagnetic noise, and which is not easily impaired by curvature or bending of the composite. [Means for solving the problem]

[0010] The above-mentioned problems are solved by the present invention by providing a composite of a cellulose material and a metal material, in which a metal material wiring is coated with a compound containing cellulose, a shield wiring that is part of the metal material wiring has a heat dissipation function, and the cellulose-containing compound has a multilayer structure formed of multiple layers with different compositions.

[0011] In the present invention, in the portion where the cellulose-containing compound coats the metal material wiring, at least some of the functional groups of the molecules of cellulose or its derivative compound are chemically bonded to the atoms of the metal material, thereby maintaining adhesion between the cellulose-containing compound in the coating portion and the metal material wiring, thereby providing a means for preventing the shielding function or heat dissipation function from being impaired even when the composite is bent. Effect 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 is made using a naturally occurring cellulose material and has a shielding mechanism for protecting a semiconductor circuit or an electronic device circuit from external electromagnetic noise and a heat dissipation mechanism for the semiconductor circuit or the electronic device circuit, and which retains the heat dissipation function even when the composite is curved. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a wiring board, which is an example of the composite of a cellulose material and a metal material of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a distribution cable, which is an example of the composite of a cellulose material and a metal material of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will now be described. The following description is a representative 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] The composite of the cellulose-containing compound of the present invention and a metal material (hereinafter also referred to as the "composite of the present invention") is composed of a sheet made of cellulose fibers or cellulose nanofibers (hereinafter also referred to as the "cellulose sheet") and a film made of a metal such as copper (hereinafter also referred to as the "metal film"). As described in Non-Patent Document 1, some cellulose nanofiber materials have functional groups of cellulose molecules substituted with carboxyl groups. On the other hand, for example, carboxylate ligands are known to form organometallic complexes with metal atoms. In the composite of the present invention, the adhesion between the cellulose sheet and the metal film is enhanced by chemical bonds between the functional groups of the cellulose molecules in the cellulose sheet in contact with the metal film and the metal atoms on the surface of the metal film. However, it is not preferable for a cellulose sheet having such functional groups to come into contact with the external environment from the viewpoint of, for example, moisture resistance, and the cellulose sheet in the composite of the present invention is formed from a cellulose material consisting of at least two or more layers of cellulose molecules having different functional groups. In Fig. 1, two sets of multilayer cellulose sheets are used to cover the top and bottom of multiple copper film wirings processed into a tape shape, with a copper film placed underneath and a multilayer cellulose sheet placed underneath that. The copper film on the bottom layer may be processed into a mesh shape. In Fig. 1, the uncovered part of the top multilayer cellulose sheet, i.e., the part where the metal surface is exposed and not covered by the cellulose material, is where semiconductor circuit components or electronic device components such as sensors are mounted, and power supply and signal input / output to the semiconductor circuit components are carried out through the copper film wiring processed into a tape. The copper film in the lower layer performs shielding and heat dissipation functions. Although not shown in FIG. 1, the composite body of the present invention has a curved portion in part, and the shape of the curved portion can be optimized depending on the industrial application scene described below.

[0016] In Fig. 2, a multi-layered cellulose sheet processed into a tape shape is bandaged around a metal material such as copper processed into a wire or rod shape to form an electric wire (hereinafter also referred to as a "coated electric wire"). In this case, the cellulose material of the inner sheet has carboxyl groups so that the functional groups of the cellulose molecules in the cellulose sheet in contact with the metal film are chemically bonded to the metal atoms on the surface of the metal film, while the cellulose material of the outer sheet in contact with the external environment containing moisture does not have carboxyl groups. In FIG. 2, multiple insulated electric wires are arranged in a matrix, some of which are used as power supply lines and signal lines, and the other insulated electric wires positioned around the power supply lines and signal lines are used as shielding wires and heat dissipation wires. 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 depending on the industrial application described later. Although not shown in Figure 2, semiconductor circuit components or electronic device components such as sensors or power supply components are mounted on the uncoated portions at the ends or middle portions of the composite of the present invention, i.e., the portions that are not covered with cellulose material and where the surface of the metal material is exposed. [Industrial Applicability]

[0017] The industrial applicability of the composite of the present invention described above is that it may be used for the purpose of strengthening electromagnetic noise shielding and heat dissipation of a part of a circuit board built into an electronic computer, data server, automobile, train, construction machine, aircraft, drone, robot, etc. In addition, it may be used for the purpose of strengthening electromagnetic noise shielding and heat dissipation when future computerization such as IoT in farm fields and livestock farming sites, that is, when introducing semiconductor circuits and electronic device circuits such as sensors at indoor and outdoor sites. Needless to say, in these industrial applications, naturally derived cellulose materials can contribute to the realization of a sustainable society by partially replacing conventional petroleum-derived materials. [Explanation of symbols]

[0018] 11 ... multi-layer cellulose sheet, 12 ... metal wiring 13. Shielding and heat dissipation layer 14 Semiconductor device or electronic device 21 .... Multi-layer cellulose sheet, 22 .... Metal electric wire 23: Signal line or power line, 24: Shield and heat dissipation line

Claims

1. A composite of a compound containing cellulose or a derivative thereof processed into a sheet, tube, or thread, and a metal material processed into a sheet, elongated strip, rod, or wire, wherein the metal material has a coated portion coated with the compound containing cellulose or a derivative thereof and an uncoated portion, which is a part of the surface of the metal material that is not coated with the cellulose or its derivative molecules, and the sheet, tube, or thread processed from the compound containing cellulose or its derivative has a multilayer structure formed of multiple layers each having a different composition.

2. 2. The composite of a metal material and a compound containing cellulose or a derivative thereof according to claim 1, characterized in that the metal material processed into the long, thin band is a plurality of signal wires or power wires, each of which is arranged between two layers of the compound containing cellulose or a derivative thereof processed into a sheet, and each of which has the coated portion and an uncoated portion, and a second metal material layer is arranged between the layer of the compound containing cellulose or a dielectric thereof processed into a sheet, the second metal material layer being a shield electrode that reduces external electromagnetic noise in the transmission of the signal and power, and the shield electrode having a heat dissipation function of absorbing at least a portion of the heat transmitted from the signal wire or the power wire.

3. 2. The composite of a metal material and a compound containing cellulose or a derivative thereof according to claim 1, wherein the metal material processed into a rod or wire shape has the covered portion wrapped with the compound containing cellulose or a derivative thereof processed into the sheet, tube, or thread shape and the uncovered portion not wrapped, and the metal material processed into a rod or wire shape is a signal wire or a power wire and a shielded wire, a plurality of which are arranged in parallel, and at least two or more shielded wires are arranged around the signal wire or the power wire, and the shielded wire has a heat dissipation function of absorbing at least a portion of the heat transmitted from the signal wire or the power wire.

4. 4. A composite of a metal material and a compound containing cellulose or a derivative thereof according to claim 2 or 3, characterized in that in the coating portion in which the metal material is coated with a compound containing cellulose or a derivative thereof, at least some of the functional groups of the compound molecules containing cellulose or a derivative thereof are chemically bonded to atoms of the metal material.

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