WO2023145440A1 - Method for producing film wire - Google Patents

Abstract

The present invention provides a method for producing a novel electrical wiring line which is suited to the demands for weight saving and space saving, and which can be produced at a low cost.　A method for producing a film wire, wherein an electrical wiring line is obtained by separating a film, which comprises a base film that is formed of an insulating resin, a conductive layer that is formed on the upper surface of the base film and a cover layer that is formed on the upper surface of the conductive layer, into a predetermined shape. It is preferable that: the conductive layer and the cover layer are formed by a sputtering method; the conductive layer has an electrical resistivity of 10 µΩcm or less, while being mainly composed of any one of Al, Cu and Ag; and the cover layer is a non-magnetic alloy film that is mainly composed of any one of Ti, Cr, Mo and Ni.

Description

Film wiring manufacturing method

The present invention relates to a method for manufacturing film wiring.

In recent years, automobiles, motorcycles, and the like powered by internal combustion engines are gradually being electrified from the viewpoint of environmental protection. It is essential to reduce the weight of structural materials in order to improve the fuel and electricity consumption of automobiles, and the ratio of use of lighter Al-based materials and carbon composite materials to iron-based materials is increasing. In addition, the exterior such as the body is also being replaced from metal to resin or the like. However, automobiles are equipped with an increasing number of electrical components for various safety and comfort equipment, and the weight of the electrical wiring that connects them is increasing. Current electrical wiring uses coated wiring in which copper wires are covered with resin. A drive-by-wire that is wirelessly controlled (Patent Document 2) and the like are being studied.
In addition, as wiring for space saving, flexible printed circuit boards, etc., which are formed by plating fine copper wires on resin films, are used in many home appliances, TVs, personal computers, mobile phone internal boards and connection of terminals. used.

JP 2016-108617 JP 2017-144945

Aluminum-coated wiring, which is being considered for weight reduction as mentioned above, requires a space equivalent to the current copper resin coating, so it cannot be used to save space. Although it can be expected to be space-saving, it has the problem of being expensive and susceptible to electromagnetic noise in the space. In addition, there is a limit to the size of flexible printed circuit boards that can be manufactured. Generally, the length of a flexible printed circuit board is only a few centimeters. There is a problem that it is expensive because it is necessary. In addition, since the exterior mainly made of resin has low conductivity, there is also a problem that a new ground wiring (earth wire) is required.

The purpose of the present invention is to provide a new electrical wiring that can be manufactured at low cost, meeting the demands for weight reduction and space saving.

In view of the above problems, the present inventors diligently studied various electrical wiring that can replace the covered wiring and achieve light weight and space saving. As a result, the present inventors have found that light-weight, space-saving electric wiring can be obtained at low cost by forming a thin film on a film and separating it into a predetermined size.
That is, the present invention separates a film having a base film made of an insulating resin, a conductive layer formed on the upper surface of the base film, and a coating layer formed on the upper surface of the conductive layer into predetermined shapes. It is a manufacturing method of the film wiring used as an electric wiring.
Moreover, it is preferable that the thickness of the conductive layer is 300 nm or more, and the thickness of the coating layer is 10 to 200 nm.
Moreover, the conductive layer and the coating layer are preferably formed by a sputtering method, and the conductive layer preferably has an electrical resistivity of 10 μΩcm or less, and is mainly composed of Al, Cu, or Ag.
Also, the coating layer is preferably made of a non-magnetic alloy film containing any one of Ti, Cr, Mo and Ni as a main component.
Moreover, the coating layer is preferably an alloy containing Mo as a main component and a total of 60 at % or less of Ni and Ti.
Moreover, the coating layer is preferably an alloy containing Ni as a main component and containing 60 at % or less of Cu, Mn, and Mo in total.

According to the present invention, it is possible to provide film wiring that is lightweight, space-saving, and inexpensive to manufacture, in place of covered wiring that is used for electrical wiring in automobiles, motorcycles, and the like.

It is an example of the cross-sectional schematic diagram of the film wiring of this invention.

One of the important features of the film wiring of the present invention is the production of film wiring by forming a conductive layer and a coating layer covering it on a base film to form a film, and then separating it into pieces of a predetermined size to form electric wiring. in the method. The film wiring of the present invention will be described in detail below. The film wiring of the present invention uses a coated wiring in which a copper wire is coated with a resin. It can be applied to applications in which low-current electronic devices are arranged.

Until now, thin-film wiring has generally been done by using a photo-etching process to create a precise wiring pattern only on the thin film on the substrate. It is used only for expensive products because it needs to be processed using a strong photoresist or chemicals, and then cleaned using an organic solvent or a large amount of pure water. Furthermore, the larger the area, the larger the manufacturing equipment required and the larger the capital investment required.
On the other hand, if the covered wiring used in current automobiles etc. is substituted, a precise wiring pattern is not required, and the conductive layer and the covering layer formed on the base film of the present invention are attached together with the base film. By cutting (separating into predetermined shapes) to form wiring, it is possible to manufacture electric wiring at a low cost. This will contribute to the reduction of the environmental load associated with the improvement of fuel and electricity consumption of automobiles and motorcycles.
Moreover, it is possible to cut the film of the present invention into stripes (straight lines) to form film wiring. It is also possible to suppress the occurrence of electromigration. It is also possible to attach a film wiring along the shape of a low-conductivity resin body to serve as a ground wiring (earth). As for the method of separation, a cutting tool such as scissors or a cutter knife may be used, or a method of burning off by irradiating a laser may be used. The film wiring can be formed by inexpensively forming a conductive layer and a coating layer on a current resin film with a width of several tens of centimeters by using a sputtering method or the like, and then cutting the film into predetermined pieces of several millimeters to several tens of centimeters.

An insulating resin is used for the base film of the film wiring of the present invention. This is to prevent the conductive layer from coming into contact with other metals or the like and causing an electrical short circuit. For example, an inexpensive PET film or a polyimide film with high heat resistance may be used. The thinner the thickness, the easier it is to cut into the film wiring as long as it has the strength necessary for handling the film wiring and the flexibility for easy handling. Furthermore, it is more preferable to laminate an insulating film having a shape conforming to the shape of the vehicle body of an automobile or the like to the conductive layer forming surface of the cut film wiring. Further, in order to improve adhesion, a coating having the same components as the coating layer may be formed as a base layer between the base film and the conductive layer. The thickness of the base film may be set to 1 to 1000 μm, for example, as long as it exhibits strength enough to withstand film wiring applications. The lower limit of the thickness is 10 μm, and the upper limit of the thickness is 500 μm, which is a desirable range for easy handling.

A sputtering method is preferably used to form the conductive layer and coating layer for the film wiring of the present invention. Methods for forming a conductive layer include plating, which is one of the wet methods, and several physical vapor deposition methods, which form a dry method in a vacuum. Sputtering is the most suitable method for forming the film.

The conductive layer of the film wiring of the present invention requires high electrical conductivity, and an alloy or an alloy containing any of Al, Cu, and Ag as a main component (containing 80 at% or more), which can easily obtain an electrical resistance of 10 μΩcm or less. Pure metals with a purity of 98% or higher are suitable. In addition, Al and Cu, which are less expensive than Ag, are preferable, and Cu, which has a higher melting point than Al, is more preferable in consideration of long-term reliability such as electromigration.

The coating layer used in the film wiring of the present invention protects the conductive layer from the external environment. Then, environmental resistance for suppressing corrosion of the conductive layer, and improvement of adhesion with the film substrate (base film) when a coating with the same components as the coating layer is formed as a base layer are required, so Ti, Cr , Mo and Ni as main components are desirable. The reason why it is non-magnetic is that it uses the magnetron sputtering method, which has a high film formation speed. With a magnetic material, it is necessary to use a very thin target material in order to obtain a film formation speed, which shortens the life of the target material. This is because productivity decreases.
The term "environmental resistance" refers to surface deterioration under high-temperature and high-humidity conditions and under heating in the atmosphere. It can be confirmed by a color change and can be quantitatively evaluated, for example, by reflectance.
Cr and Ti are metals with high corrosion resistance, but Cr has a large internal stress when formed by sputtering, and the film may warp. At high temperatures, Ti and Ni may thermally diffuse into Cu to increase electrical resistance. Mo is an element that is difficult to thermally diffuse into Al, Ag, and Cu, which are low-stress and conductive films that easily suppress warping of the film, but has low high-temperature and high-humidity resistance, and because it is a high-melting-point metal, it easily becomes brittle and bends the film. It has the disadvantage that the film is likely to crack when it is applied.
For this reason, in order to improve moisture resistance and to have an amorphous structure that is less likely to crack, it is preferable to use a Mo alloy to which Ni or Ti is added. More preferably, it contains 25 to 40 at % of Ni and 5 to 30 at % of Ti.
In order to improve moisture resistance and improve electrical connectivity with the control substrate and Cu-coated wiring, it is preferable to use a Ni alloy to which Cu, Mn, and Mo are added for the coating layer in the case of soldering. , Mn and Mo in total is 60 at % or less, more preferably 10 to 40 at % of Cu, 7 to 25 at % of Mn and 5 to 30 at % of Mo.

The thickness of the conductive layer of the film wiring of the present invention is desirably 300 nm or more in order to achieve low electrical resistance. Moreover, the thickness of the coating layer is preferably at least 10 nm or more in order to suppress deterioration of the conductive layer due to moisture permeating the film surface or the film. If the thickness is less than 10 nm, the continuity of the film is lowered and the protective function becomes insufficient. In addition, if the thickness is increased, the electrical resistance increases and it takes a long time to form the film, resulting in a decrease in productivity. A more preferable lower limit of the coating layer is 30 nm, and a more preferable upper limit of the coating layer is 100 nm.
Further, by forming a magnetic film having soft magnetic properties, such as permalloy, on the lower surface or upper surface of the coating layer, it is possible to obtain a composite film that serves both as a wiring and a magnetic shield.

(Example 1)
A PET film having a thickness of 100 μm was cut into 200×100 mm as a base film for producing film wiring. A model number SME-200E manufactured by ULVAC, Inc. was used as a sputtering device for forming the conductive layer and the coating layer. The target material attached to the sputtering device has a diameter of 100 mm and a thickness of 5 mm. It was prepared by sintering powders of Mo, Ni—Mo alloy and Ti. These target materials were brazed to a copper backing plate and then attached to the sputtering apparatus. After fixing the cut PET film to the substrate holder of the sputtering device and evacuating to 5 × 10 ^-5 Pa, the sputtering gas Ar was introduced, and the atmosphere was set to 0.5 Pa to create a Mo-Ni-Ti base layer. An alloy was formed to a thickness of 30 nm at a power of 300 W, a conductive layer of Cu was formed to a thickness of 500 nm at a power of 500 W, and then a Mo--Ni--Ti alloy was formed to a thickness of 30 nm as the coating layer under the same conditions as the underlayer. A cross-section of the layered structure is shown in FIG. Also, for comparison, only a Cu film as a conductive layer was formed on a PET film to a thickness of 500 nm. The electrical resistivity of this Cu film was 2.1 μΩcm.

A PET film formed with a Cu conductive layer and a Mo-Ni-Ti coating layer and a PET film formed with only a Cu conductive layer were cut into 25 x 50 mm pieces and placed in a high-temperature and high-humidity bath set at a relative humidity of 85% and a temperature of 85 ° C. When left to stand for 300 hours, the case where the Mo--Ni--Ti coating layer was formed had little discoloration and had a metallic luster, but the case where only the Cu conductive layer was formed turned brown. It was confirmed that the formation of the Mo--Ni--Ti coating layer can greatly improve the moisture resistance.

A PET film on which a coating layer and a conductive layer were formed was cut to a length of 200 mm and a width of 3 mm using a rotary cutter (manufactured by Lion Business Machine Co., Ltd.: model RC-B4) to prepare film wiring of the present invention example. The terminal of the T10 type LED light bulb and one end of the film wiring (on the side where the conductive film is formed) were fixed, and when the other end of the film wiring was connected to a 12 V power supply, the LED lit up and the film wiring was confirmed. As a result, the existing covered wiring with an outer diameter of about 0.5 to 1.5 mm can be made into a thinner and wider area film wiring, and the effect of making it a light weight, space-saving and inexpensive electric wiring. considered to be large.

(Example 2)
A polyimide film having a thickness of 50 μm was cut into a size of 280×100 mm as a base film for producing film wiring. A model number: CS-200 manufactured by ULVAC, Inc. was used as a sputtering device for forming the conductive layer and the coating layer. The target material attached to the sputtering device has a diameter of 100 mm and a thickness of 5 mm, and is processed from a plate of 4N oxygen-free copper for the conductive film. After weighing predetermined amounts of Ni, blocks of oxygen-free copper, massive Mn and Mo raw materials, ingots were produced by melting and casting in a vacuum melting furnace, and then machined. These target materials were brazed to a copper backing plate and then attached to the sputtering apparatus. After fixing the cut polyimide film to the substrate holder of the sputtering device and evacuating to 7×10 ⁻⁵ Pa, the sputtering gas Ar was introduced and the atmosphere of 0.5 Pa was applied to Ni—Cu—Mo as the underlying layer. A -Mn alloy was formed to a thickness of 30 nm at a power of 300 W, a conductive layer of Cu was formed to a thickness of 500 nm at a power of 500 W, and then a Ni--Cu--Mo--Mn alloy was formed to a thickness of 30 nm as the coating layer under the same conditions as the underlayer. A cross-section of the layered structure is shown in FIG. For comparison, only a Cu film as a conductive layer was formed on a polyimide film to a thickness of 500 nm.

A polyimide film having a Cu conductive layer and a Ni—Cu—Mo—Mn coating layer (film of the present invention) and a polyimide film having only a Cu conductive layer (film of a comparative example) were cut into 25×50 mm pieces. When left for 300 hours in a high-temperature and high-humidity bath set at a humidity of 85% and a temperature of 85° C., the Ni—Cu—Mo—Mn coating layer was hardly discolored and had a metallic luster, but Cu conductivity. When only a layer was formed, the color turned dark brown. It was confirmed that the formation of the Ni--Cu--Mo--Mn coating layer can greatly improve the moisture resistance.

A polyimide film having a Ni—Cu—Mo—Mn coating layer and a Cu conductive layer (film of the present invention) was cut into stripes with a width of 5 mm and a length of 100 mm using a rotary cutter (manufactured by Lion Business Machine Co., Ltd.: model RC-B4). It was cut into pieces to prepare film wiring of an example of the present invention. Then, the Cu conducting wire portion of the existing coated wiring (wiring in which the Cu conducting wire is coated with resin) with Sn-based solder attached to the end portion of the film wiring of the present invention is pressed while being heated with a soldering iron, and the Sn-based solder melts. After that, the soldering iron was released to cool. The covered wiring and the film wiring were joined, and continuity was confirmed. Subsequently, in the same manner as in Example 1, the terminal of a 10-inch LED light bulb and one end of the film wiring (the side on which the conductive film is formed) were fixed to the terminal of the T10-type LED light bulb, and the coated wiring side was connected to a 12 V power source. However, the LED lit up, and it was confirmed that the film wiring could be brazed and joined to the existing coated wiring. It is thought that the conventional coated wiring that requires a large current and the device that can use the film wiring for power saving can be mixed and used separately, and it is possible to make a useful electric wiring.

1. base film2. Underlayer 3 . conductive layer4. covering layer

Claims (7)

1. A film comprising a base film made of an insulating resin, a conductive layer formed on the upper surface of the base film, and a coating layer formed on the upper surface of the conductive layer is separated into a predetermined shape and used for electrical wiring. A method for manufacturing film wiring, characterized by:
2. The method for manufacturing film wiring according to claim 1, wherein the conductive layer has a thickness of 300 nm or more, and the coating layer has a thickness of 10 to 200 nm.
3. The method for manufacturing film wiring according to claim 1 or 2, wherein the conductive layer and the coating layer are formed by a sputtering method.
4. 3. The method of manufacturing a film wiring according to claim 1 or 2, wherein the conductive layer has an electrical resistivity of 10 μΩcm or less and is mainly composed of any one of Al, Cu, and Ag.
5. 3. The method of manufacturing a film wiring according to claim 1 or 2, wherein the coating layer is made of a non-magnetic alloy film containing any one of Ti, Cr, Mo and Ni as a main component.
6. The method of manufacturing a film wiring according to claim 5, wherein the coating layer is an alloy containing Mo as a main component and a total of 60 at% or less of Ni and Ti.
7. 6. The method of manufacturing a film wiring according to claim 5, wherein the coating layer is an alloy containing Ni as a main component and a total content of Cu, Mn and Mo of 60 at % or less.
   
   

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