JPH0124323B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is an electrical insulating material made of an aromatic polyamide film manufactured by a special method and having excellent heat resistance, electrical insulation, chemical resistance, mechanical properties, etc. The present invention relates to a method of manufacturing an electrical member made of a conductor composite material. [Prior Art] Recently, wiring materials in which copper foil or the like is bonded to films such as polyester films, fluororesin films, and polyimide films have been used for electrical components such as flexible printed circuits. However, electrical components such as flexible printed circuits need to be sufficiently heat resistant and stable in a solder bath for bonding with other wiring, but electrical components using polyester film as a substrate do not
The heat shrinkage rate of polyester film is extremely large at temperatures above 200°C, and the current situation is that it is necessary to extremely shorten the contact time with the solder bath or to greatly sacrifice wiring density and precision. On the other hand, polyimide films, fluororesin films, etc. have almost no problems in terms of solder resistance, but they have the problem of being expensive and economically disadvantageous. On the other hand, p-phenylene terephthalamide series, halogen-substituted p-phenylene terephthalamide series, m-phenylene terephthalamide series, p-
Films made of aromatic polyamides such as phenylene isophthalamide and m-phenylene isophthalamide are generally excellent in heat resistance and mechanical properties, and are polymeric materials that have attracted particular attention in recent years. However, when compared to polyimide films, films made of aromatic polyamides have
It is inferior in heat resistance and moisture absorption dimensional change rate, and further improvement is required in order to expand its use in the field of electrical components. [Object of the Invention] Therefore, the main object of the present invention is to provide a method for producing a good electrical component based on an aromatic polyamide film. [Structure of the Invention] The present inventors first impregnated an aromatic polyamide film with at least 1% by weight of an amide solvent, heat-treated it at a temperature of 100°C or higher, and then heated it at a temperature of 100°C or higher.
It has been found that by performing relaxation heat treatment at a temperature of .degree. C. or higher, a significant improvement in mechanical properties and a significant reduction in dimensional change rate can be achieved. When an aromatic polyamide film with improved mechanical properties and dimensional stability is combined with an electrical conductor such as copper foil to form a composite material, the above-mentioned problems are solved, and heat resistance, dimensional accuracy, and economic efficiency are improved. The present invention was completed after recognizing the fact that excellent electrical components could be manufactured. That is, in the present invention, an aromatic polyamide film is made to contain at least 1% by weight or more of an amide solvent, and after being heat-treated at a temperature of 100°C or more,
Furthermore, at 100℃ or higher in a substantially solvent-free state,
This is a method for manufacturing an electrical member insulated with an aromatic polyamide film by combining an electrical conductor with an aromatic polyamide film electrical insulating material that has been subjected to relaxation heat treatment at a temperature of preferably 200° C. or higher. The aromatic polyamide polymer used as a raw material in the present invention has the general formula and/or

An aromatic polyamide polymer containing repeating structural units represented by the formula either singly or in copolymerized form, and preferably containing 75 mol% or more of the structural units. Here, Ar ₁ and Ar ₂ are divalent aromatic groups,
These may be the same or different. The following structural formula is a typical example.

【formula】

【formula】

【formula】

【formula】

【formula】,

[Formula] [However, R is lower alkyl, lower alkoxy,
is a halogen or nitro group, and is 0 and 4
is an integer from 0 to 4 including

【formula】

[Formula] -O-,

【formula】

[In the above formulas (1) and (2), a represents parts by weight of the aromatic polyamide, b represents parts by weight of the amide solvent, and c represents parts by weight of the solubilization aid. ]

This is a wet film forming method in which an aromatic polyamide composition represented by the formula is introduced into an aqueous coagulation bath. At least 75 mole% of polymer repeating structural units
In the case of aromatic polyamides having the above-mentioned meta-structure, the preferred composition ratio of the aromatic polyamide composition depends on the polymer concentration and is defined as follows. When 0.25≦a/a+b≦0.336, 0.1≦c/a...(3) When 0.336<a/a+b≦0.5, 2.8×a/a+b-0.84<c/a...(4) Aqueous coagulation of such a composition By introducing it into the bath, film formation can be performed satisfactorily. As the amide solvent used here, the same amide solvents as those mentioned above can be used. The above-mentioned amide solvent preferably contains a plasticizing aid, and such plasticizing aids include metal salts of Groups and/or Groups of the Periodic Table and ammonium halides. Such salts are dissolved in the polymer solution and serve to enhance the stability of the solution, as described in, for example, Japanese Patent Publication No. 35-16027. Preferred solubilizing aids include lithium chloride, calcium chloride, and magnesium chloride, with calcium chloride being particularly preferred. The aromatic polyamide composition is usually in a viscous liquid or semi-solid state at room temperature.
However, even if it is semi-solid at room temperature, 80℃
It flows easily at the above temperature, and proper fluidity can be ensured in the temperature range up to the boiling point of the solvent used, and the solution has good thermal stability. Therefore, it is possible to form a film using not only a conventional wet molding machine but also a melt molding machine. The molding temperature varies depending on the composition ratio of the aromatic polyamide composition used and the molding method applied, but 60
A range of ~180°C is preferred. If the molding temperature is less than 60°C, the solution viscosity of the composition will be high, making it difficult to obtain a homogeneous film, and sufficient productivity may not be obtained. On the other hand, at temperatures above 180°C, coloring of the molded product and foaming due to moisture in the composition may occur, which may cause operational problems. The aromatic polyamide composition can be formed into a film by a wet method or an air discharge wet method, and a uniform film can be obtained. Generally, when using an aromatic polyamide composition with a low solution viscosity, a wet molding method is applied, and when the solution viscosity is relatively high, an air discharge-wet molding method is often applied, but this is not always the case. The method is not limited, and a more preferable molding method can be selected depending on the purpose of film production and the physical properties of the stock composition. In particular, the air discharge wet molding method is extremely advantageous over conventionally known molding methods in the following points. (a) Since molding with extremely high polymer concentration is possible, the amount of expensive amide solvents used is small. (b) A molding method similar to melt molding can be applied, and a molding method with extremely high productivity such as improved extrusion speed can be provided. (c) A homogeneous and highly transparent film can be stably produced up to a relatively large thickness. (d) Energy costs for manufacturing are reduced. In the case of wet molding from a stock solution composition containing a solubilizing aid, a wet washing step is required and the process is complicated. In contrast, the method of the present invention basically consists of only a wet molding step, and the process is simple. As the coagulating bath, at least one bath having the following composition is preferably used for forming the aromatic polyamide film. (i) Inorganic salt aqueous solution (ii) Organic solvent aqueous solution (iii) Mixed aqueous solution of (i) and (ii) Coagulation is a particularly important factor in facilitating the stretching process and producing a transparent and strong film. By combining the above-mentioned aromatic polyamide composition and the above-mentioned coagulation bath, it becomes possible to carry out the stretching described later, and it is possible to obtain a high-performance film. Preferred inorganic salts contained in the inorganic salt aqueous solution (i) above include CaCl ₂ , LiCl, MgCl ₂ and ZnCl ₂ , with LiCl and CaCl ₂ being particularly preferred. It is also generally advantageous for the solubilization aid in the aromatic polyamide composition and the inorganic salt in the coagulation bath to be the same compound. The preferable inorganic salt concentration varies depending on the type of inorganic salt, the composition or composition ratio of the aromatic polyamide composition, molding conditions, etc., but an aqueous solution containing 20% by weight or more of the above-mentioned inorganic salt is preferable. When such a coagulation bath is used, it is possible to produce a film with excellent mechanical performance and transparency. Furthermore, although the coagulation bath composition, temperature, and immersion time are not constant depending on the desired thickness and transparency of the film, the preferred coagulation bath temperature when using an aqueous inorganic salt solution is 40 to 110°C. An organic solvent aqueous solution can also be used as the coagulation bath. As organic solvents, various alcohols,
Amide solvents can also be used. Among various alcohols, alkylene glycol is one of the organic solvents that can be preferably selected. As typical alkylene glycols, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, etc. can be used. The concentration of the polyalkylene glycol or glycerin aqueous solution is selected from a range of 30° C. to the boiling point of the coagulation bath, although it varies depending on the composition or composition ratio of the aromatic polyamide composition, the molding method, and other factors. In preferred embodiments, multi-stage coagulation baths are often used. As a multistage coagulation bath, it is possible to use systems with different inorganic salt aqueous solutions at different concentrations and temperatures, systems with completely different coagulation compositions, etc., depending on the need, but from an industrial standpoint, it is possible to use a combination of coagulation systems of the same type. Multistage coagulation baths are preferred. In this way, a water-containing aromatic polyamide film is obtained. Examples of methods for incorporating an amide solvent into the aromatic polyamide film include: (1) immersion in an amide solvent bath; (2) mixed solvent of an amide solvent and water, alcohol, alkylene glycol, halogenated hydrocarbon, etc. Methods such as immersion in a bath (3) vapor absorption into the film in an amide solvent vapor atmosphere (4) and application of the amide solvent to the film surface by spraying or the like can be employed. According to the method of the present invention, as described above, an aromatic polyamide film containing a predetermined amount of an amide solvent is heat-treated at a high temperature of at least 100°C or higher, and the heat-treated film is substantially free of the solvent. A film with good dimensional stability can be obtained by heat-treating the polyamide in a relaxed state at a high temperature of 100° C. or higher, preferably 200° C. or higher and lower than the decomposition temperature of the polyamide. On the other hand, the electrical conductor used to combine with the film in the present invention may be any conductor containing carbon, copper, tungsten, nickel, chromium, iron, silver, aluminum, lead, tin, etc. However, typical electrical conductors include metal wires, metal plates, metal foils, and metal vapor-deposited films. A typical example of the composite material consisting of an electrically insulating material and an electrical conductor, which is the object of the present invention, is a printed wiring board in which a metal thin film is bonded to the surface of the aromatic polyamide film with a heat-resistant adhesive. It is mentioned as. The metal thin film has a thickness of 1 to 200 μm, especially 5 μm.
A thin copper film, such as a copper foil, having a thickness of about 100 μm is preferred. The adhesive is preferably a heat-resistant adhesive, such as aromatic polyamic acid, fluororesin, polyamideimide, silicone resin, epoxy-novolac resin, nitrile rubber-phenol resin, or the like. In addition, as a printed wiring board, an electrical conductor layer is formed without using an adhesive by chemically plating the surface of the aromatic polyamide film or depositing copper using a vacuum evaporation method. Substrates can also be manufactured. [Effects of the Invention] According to the method of the present invention as described above, an aromatic polyamide film with extremely good thermal dimensional stability can be obtained, so electrical components using this film as an insulating material are particularly useful as printed wiring boards. . [Example] The present invention will be explained in more detail below by giving examples. Example 1 Production of aromatic polyamide film Poly-m-phenylene isophthalamide was used as the aromatic polyamide, and N- as the amide solvent.
Methyl-2-pyrrolidone, as a solubilization aid
An aromatic polyamide composition having the following composition was prepared using _CaCl2 . (Aromatic polyamide) / (Aromatic polyamide) + (Amide solvent) = 0.33 CaCl ₂ /Aromatic polyamide = 0.2 Using a 30 m/m extruder, the above composition was heated to 0.1 mm,
It was extruded from a T-die with a width of 400 mm onto a casting roller at 110°C, and introduced into a 43% calcium chloride aqueous solution at 90°C. Subsequently, it was washed in cold water at 10°C or lower, and then stretched 1.9 times in the machine direction (MD) and further 1.9 times in the vertical direction (TD) in hot water at 95°C. This film was immersed in a 30% by weight NMP aqueous solution for 10 minutes at room temperature, and then placed in a dry air dryer at 60°C for 10 minutes.
After drying for a minute, it was heat-treated at 270°C for 10 minutes.
During this time, NMP was dried off. The obtained film was heat-treated again at 270°C for 30 minutes in a relaxed state to obtain an aromatic polyamide film. The performance of the obtained aromatic polyamide film is as follows. Breaking strength 24.0Kg/mm ^2Elongation at break 88% Initial Young's modulus 497Kg/mm ^2Volume resistivity 10 ¹⁶ Ω-cm Dimensional change rate after drying at 120℃ for 30 minutes and after moisture absorption at 65%RH for 96 hours 0.4% Flexible printed wiring board Manufacturing: The aromatic polyamide film was coated with an epoxy-novolac resin adhesive, a 35μ electrolytic copper foil was layered on top of the film, and the film was pressed with a pressure roller and heated at 95°C for 2 hours.
A flexible printed wiring board was manufactured by heating at 200°C for 1 hour and then at 220°C for 5 hours. The performance of the obtained printed wiring board is as follows. Surface resistivity of substrate film 10 ¹⁶ Ω Copper foil adhesive strength (180° direction) 1.2Kg/cm Solder immersion (260℃ 30 seconds) No abnormality Chemical resistance (24 hours at room temperature) Triclean No change Methyl ethyl ketone 〃 10% NaOH aqueous solution 〃 10%HCl 〃 〃 10%H ₂ SO ₄ 〃 〃 Example 2 Production of aromatic polyamide film In Example 1, phenyl-modified silicone oil (manufactured by Toshiba Silicon Corporation, TSF433), δ-glycidoxypropyltrimethoxysilane (Toray Silicon Co., Ltd.)
Film formation and treatment were carried out in exactly the same manner as in Example 1, except that 2% by weight/polymer of each of SH-6040) was added and used. The properties of the obtained film are as follows. Breaking strength 21.8Kg/mm ^2Elongation at break 60% Initial Young's modulus 497Kg/mm ^2Volume resistivity 10 ¹⁶ Ω-cm Dimensional change rate after drying at 120℃ for 30 minutes and after moisture absorption at 65%RH for 96 hours 0.3% Flexible printed wiring board Production A flexible printed wiring board was produced in the same manner as in Example 1 by bonding the aromatic polyamide film and copper foil. The performance of the obtained printed wiring board was as excellent as in Example 1.

Claims (1)

[Claims] 1. An aromatic polyamide film containing at least 1% by weight of an amide solvent, heat treated at a temperature of 100°C or higher, and then subjected to relaxation heat treatment at a temperature of 100°C or higher in a state substantially free of solvent, resulting in an aromatic aroma. On the surface of polyamide film electrical insulation material,
A method for producing an aromatic polyamide film insulating electrical member, which comprises forming a composite material by providing an electrical conductor layer.