JP4671388B2 - Film for flexible printed circuit boards - Google Patents

Description

  The present invention relates to a film for a flexible printed circuit board comprising a thermoplastic resin composition, which has a polyphenylene ether-based resin composition and is excellent in heat resistance, flame retardancy, flex resistance, electrical characteristics, and moisture absorption resistance.

  In recent years, the development of the electronics field has been remarkable, and in particular, electronic devices for communication and consumer use have been reduced in size, weight and density, and the demands for these performances have become increasingly sophisticated. In response to such demands, flexible printed wiring boards are flexible and have the characteristics of withstanding repeated bending, so that three-dimensional and high-density mounting is possible in a narrow space. Applications are expanding as composite parts with wiring, cable, or connector functions. A flexible printed circuit board is a laminate of an electrically insulating base film with high heat resistance and excellent electrical and mechanical properties and a metal foil laminated with an adhesive, and is required for this flexible printed circuit board. Properties include adhesion, heat resistance, electrical properties, workability, flex resistance, moisture resistance, flame resistance, and the like. Conventionally, polyimide has been widely used as a base film or a coverlay film in these flexible printed boards (Patent Document 1).

However, with recent high-density mounting, further improvements such as electrical characteristics typified by low dielectric constant and low dielectric loss tangent, and stability of electrical characteristics after moisture resistance are required. The polyimide film is highly functional, but is often a thermosetting resin. For example, the precursor polyamic acid is used as a starting polymer, and is cured and cured while removing the solvent from the solution state. It is obtained through a very complicated process. Thus, in addition to the expensive raw materials, the process was also expensive. Therefore, an inexpensive and high quality film has been awaited. In particular, a film obtained from a thermoplastic resin has a relatively simplified process, and it is possible to recycle surplus products other than products generated during molding. Therefore, although the thermoplastic resin is inexpensive, there are very few thermoplastic resins suitable for a flexible printed circuit board film having high functionality represented by heat resistance, electrical characteristics, flame retardancy, and bending resistance.
Japanese Patent Laid-Open No. 5-13902

  An object of this invention is to provide the film for flexible printed circuit boards which consists of a thermoplastic resin composition which is excellent in heat resistance, a flame retardance, bending resistance, an electrical property, and moisture absorption resistance.

As a result of intensive studies to solve the above problems, the present inventor has found that a resin composition having a resin composition containing 85% by weight or more of a polyphenylene ether-based resin can meet the purpose, and this The present invention has been made based on the findings.
That is, the present invention
1. (A) A film for a flexible printed circuit board having a resin composition containing 85 % by weight or more of a polyphenylene ether resin,
2. (A) 85 to 99.5 parts by weight of a polyphenylene ether resin and (B) a film for a flexible printed circuit board having a resin composition consisting of 0.5 to 15 parts by weight of a liquid crystal polyester,

3. A resin containing 0.1 to 10 parts by weight of a compound containing (C) an I-valent, II-valent, III-valent or IV-valent metal element with respect to a total of 100 parts by weight of the component (A) and the component (B) The film for flexible printed circuit board according to 2 above, having a composition,
4). (C) The film for flexible printed circuit board according to 3 above, wherein the metal element of I value, II value, III value or IV value is Zn element and / or Mg element,
5. (D) Flexible printed circuit board in any one of said 2-4 which has a resin composition containing 0.1-20 weight part of flame retardants with respect to a total of 100 weight part of (A) component and (B) component. For film,

6). (D) The film for flexible printed circuit board according to 5 above, wherein the flame retardant is a phosphate ester compound and / or a phosphazene compound,
7). The flexible printed circuit board film according to any one of 1 to 6, wherein the resin constituting the flexible printed circuit board film according to any one of 1 to 6 is a thermoplastic resin,
8). The film for flexible printed circuit boards according to any one of 1 to 7 above, wherein the average thickness is 5 to 100 μm,
9. The flexible printed circuit board which consists of a film for flexible printed circuit boards in any one of said 1-8,
Is to provide.

  The flexible printed circuit board film of the present invention is excellent in heat resistance, flame retardancy, bending resistance, electrical properties, and moisture absorption resistance, and particularly excellent in electrical properties represented by moisture absorption resistance, low dielectric constant, and low dielectric loss tangent. .

Hereinafter, the present invention will be specifically described.
The (A) polyphenylene ether resin of the present invention is a repeating unit structure of (Formula 1)

(R ₁ and R ₄ each independently represents hydrogen, primary or secondary lower alkyl, phenyl, aminoalkyl or hydrocarbon oxy. R ₂ and R ₃ each independently represent hydrogen Represents primary or secondary lower alkyl or phenyl.)
And a reduced viscosity (0.5 g / dl, chloroform solution, measured at 30 ° C.) is a homopolymer and / or copolymer in the range of 0.15 to 1.0 dl / g. A more preferred reduced viscosity is in the range of 0.20 to 0.70 dl / g, most preferably in the range of 0.40 to 0.60.

  Specific examples of the (A) polyphenylene ether resin include poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), Poly (2-methyl-6-phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-phenylene ether), and the like, and 2,6-dimethylphenol and other phenols. Also included are polyphenylene ether copolymers such as copolymers with a class (for example, 2,3,6-trimethylphenol and 2-methyl-6-butylphenol). Of these, poly (2,6-dimethyl-1,4-phenylene ether) and a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol are preferable, and poly (2,6-dimethyl-1 , 4-phenylene ether).

As an example of the method for producing (A) polyphenylene ether used in the present invention, there is a method of oxidative polymerization of 2,6-xylenol using a complex of cuprous salt and amine described in US Pat. No. 3,306,874 as a catalyst. is there.
The methods described in U.S. Pat. Nos. 3,306,875, 3,257,357 and 3,257,358, Japanese Patent Publication Nos. 52-17880, and JP-A-50-51197 and 63-152628 are also available ( A) It is preferable as a method for producing polyphenylene ether.
The (A) polyphenylene ether-based resin of the present invention may be used as it is after the polymerization process, or using an extruder or the like, under a nitrogen gas atmosphere or a non-nitrogen gas atmosphere, under devolatilization or non-devolatilization. You may use it by pelletizing by melt-kneading below.

  The (A) polyphenylene ether resin of the present invention includes polyphenylene ethers functionalized with various dienophile compounds. Examples of various dienophile compounds include maleic anhydride, maleic acid, fumaric acid, phenylmaleimide, itaconic acid, acrylic acid, methacrylic acid, methyl allylate, methyl methacrylate, glycidyl acrylate, glycidyl methacrylate, stearyl acrylate, styrene, and the like. Can be mentioned. Furthermore, as a method of functionalizing with these dienophile compounds, an extruder or the like may be used in the presence or absence of a radical generator, and functionalization may be performed in a molten state under devolatilization or non-devolatilization. Alternatively, it may be functionalized in the non-molten state, that is, in the temperature range from room temperature to the melting point in the presence or absence of a radical generator. In this case, the melting point of polyphenylene ether is defined by the peak top temperature of the peak observed in the temperature-heat flow graph obtained when the temperature is raised at 20 ° C./min in the differential thermal scanning calorimeter (DSC) measurement. If there are a plurality of peak top temperatures, the peak top temperature is defined as the highest temperature.

  The polyphenylene ether resin (A) of the present invention is a polyphenylene ether resin alone or a mixture of a polyphenylene ether resin and an aromatic vinyl polymer, and further includes a mixture of other resins. Examples of the aromatic vinyl polymer include atactic polystyrene, high impact polystyrene, syndiotactic polystyrene, acrylonitrile-styrene copolymer, and the like. When a mixture of a polyphenylene ether resin and an aromatic vinyl polymer is used, the polyphenylene ether resin is 70 wt% or more, preferably 80 wt%, based on the total amount of the polyphenylene ether resin and the aromatic vinyl polymer. More preferably, it is 90 wt% or more.

The film for flexible printed circuit boards of the present invention is obtained by molding from a resin composition having a resin composition containing 85 % by weight or more of the above (A) polyphenylene ether resin.
The (B) liquid crystal polyester of the present invention is a polyester called a thermotropic liquid crystal polymer, and known ones can be used. For example, a thermotropic liquid crystal polyester mainly composed of p-hydroxybenzoic acid and polyethylene terephthalate, a thermotropic liquid crystal polyester mainly composed of p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid, p-hydroxybenzoic acid Examples thereof include thermotropic liquid crystal polyesters mainly composed of acid, 4,4'-dihydroxybiphenyl and terephthalic acid, and are not particularly limited. As the (B) liquid crystalline polyester used in the present invention, those composed of the following structural units (A) and (B) and, if necessary, (C) and / or (D) are preferably used.

  Here, the structural units (A) and (B) are respectively a structural unit of a polyester generated from p-hydroxybenzoic acid and a structural unit generated from 2-hydroxy-6-naphthoic acid. By using the structural units (a) and (b), it is possible to obtain the thermoplastic resin composition of the present invention having an excellent balance of mechanical properties such as excellent heat resistance, fluidity and rigidity. X in the structural units (c) and (d) can be arbitrarily selected from the following (Formula 2), respectively.

  In the structural formula (c), preferred are structural units formed from ethylene glycol, hydroquinone, 4,4′-dihydroxybiphenyl, 2,6-dihydroxynaphthalene, and bisphenol A, and more preferred are ethylene glycol, 4 4,4'-dihydroxybiphenyl and hydroquinone, and particularly preferred are ethylene glycol and 4,4'-dihydroxybiphenyl. In the structural formula (d), preferred are structural units formed from terephthalic acid, isophthalic acid and 2,6-dicarboxynaphthalene, and more preferred are terephthalic acid and isophthalic acid.

  In the structural formula (c) and the structural formula (d), at least one or two or more of the structural units listed above can be used in combination. Specifically, when two or more kinds are used in combination, in the structural formula (c), 1) a structural unit generated from ethylene glycol / a structural unit generated from hydroquinone, 2) a structural unit generated from ethylene glycol / 4,4 Examples include structural units formed from '-dihydroxybiphenyl, 3) structural units formed from hydroquinone / 4, structural units formed from 4,4'-dihydroxybiphenyl, and the like.

  In the structural formula (d), 1) a structural unit generated from terephthalic acid / a structural unit generated from isophthalic acid, 2) a structural unit generated from terephthalic acid / 2, a structural unit generated from 2,6-dicarboxynaphthalene , Etc. Here, the amount of terephthalic acid is preferably 40 wt% or more, more preferably 60 wt% or more, and particularly preferably 80 wt% or more in the two components. By setting the amount of terephthalic acid to 40 wt% or more of the two components, a resin composition having relatively good fluidity and heat resistance can be obtained. The division of use of the structural units (A), (B), (C), and (D) in the liquid crystal polyester (B) component is not particularly limited. However, the structural units (c) and (d) are basically in equimolar amounts.

  Moreover, the structural unit (e) consisting of the structural units (c) and (d) can also be used as the structural unit in the component (B). Specifically, 1) a structural unit produced from ethylene glycol and terephthalic acid, 2) a structural unit produced from hydroquinone and terephthalic acid, 3) a structural unit produced from 4,4'-dihydroxybiphenyl and terephthalic acid, 4) And structural units formed from 4,4'-dihydroxybiphenyl and isophthalic acid, and 5) structural units formed from bisphenol A and terephthalic acid.

  The liquid crystal polyester component (B) of the present invention is formed from other aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids within a small range that does not impair the features and effects of the present invention as necessary. Structural units can be introduced. The temperature at which the liquid crystal state at the time of melting of the component (B) of the present invention (hereinafter referred to as the liquid crystal start temperature) is preferably 150 to 350 ° C, more preferably 180 to 320 ° C. It is preferable to set the liquid crystal start temperature within this range because black foreign matters are reduced in the obtained resinous film.

  The (C) compound containing an I-valent, II-valent, III-valent or IV-valent metal element of the present invention is an inorganic compound or organic compound containing a metal. The component (C) of the present invention is a compound essentially comprising a metal element as a main constituent component. Specific examples of metal elements that can take I, II, III, or IV in the component (C) include Li, Na, K, Zn, Cd, Sn, Cu, Ni, Pd, Co, Fe, Ru, Examples include Mn, Pb, Mg, Ca, Sr, Ba, Al, Ti, Ge, and Sb. Of these, Zn, Mg, Ti, Pb, Cd, Sn, Sb, Ni, Al, and Ge elements are preferable, and Zn, Mg, and Ti elements are more preferable. It is particularly preferable that the metal element of I, II, III, or IV is a Zn element and / or an Mg element from the viewpoint of greatly improving the toughness of the film without peeling as the resin composition or the film itself. .

(C) As specific examples of the compound containing a metal element of I, II, III, or IV, oxides, hydroxides, alkoxide salts, aliphatic carboxylates, and acetates of the above metal elements are desirable. . Furthermore, examples of preferable oxides include ZnO, MgO, TiO ₄ , TiO ₂ , PbO, CdO, SnO, SbO, Sb ₂ O ₃ , NiO, Al ₂ O ₃ , and GeO. Examples of preferred hydroxides include Zn (OH) ₂ , Mg (OH) ₂ , Ti (OH) ₄ , Ti (OH) ₂ , Pb (OH) ₂ , Cd (OH) ₂ , Sn (OH ) ₂ , Sb (OH) ₂ , Sb (OH) ₃ , Ni (OH) ₂ , Al (OH) ₃ , Ge (OH) _{2 and the} like. Examples of preferable alkoxide salts include Ti (OiPr) ₄ and Ti (OnBu) ₄ . Examples of preferred aliphatic carboxylates include zinc stearate, magnesium stearate, titanium stearate, lead stearate, cadmium stearate, tin stearate, antimony stearate, nickel stearate, aluminum stearate, stearic acid. Examples include germanium. Among these, particularly preferred specific examples include ZnO, Mg (OH) ₂ , Ti (OiPr) ₄ , Ti (OnBu) ₄ , zinc acetate, zinc stearate, and aluminum stearate. Furthermore, ZnO and Mg (OH) ₂ are preferable from the viewpoint of no delamination. Moreover, these (C) components may contain the impurity in the range which does not impair the effect of this invention.

(A) It is preferable that the compounding quantity of polyphenylene ether-type resin is 85 weight% or more. Furthermore, it is 85 to 99.5 parts by weight, preferably 85 to 99 parts by weight, and more preferably 85 to 98 parts by weight. When the blending amount is more than 99.5 parts by weight, the fluidity is greatly reduced, and it is necessary to increase the set temperature of the extruder from the viewpoint of torque (extruder load), which is included in the film. The amount of black foreign matter is increased, which is not preferable. If the blending amount is less than 85 parts by weight, the heat resistance and electrical characteristics of the film are deteriorated. Here, the black foreign matter is called a black spot, a shadow or a char, and has an effect of lowering the insulating properties of the film.

The blending amount of the liquid crystal polyester as the component (B) in the present invention is 0.5 to 15 parts by weight, preferably 1 to 15 parts by weight, and more preferably 2 to 15 parts by weight. When the blending amount is more than 15 parts by weight, the thickness unevenness of the film is reduced due to the anisotropy of the liquid crystal polymer. When this compounding quantity is less than 0.5 weight part, fluidity | liquidity will fall large and the black foreign material in a film will increase.
The blending amount of the component (C) in the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight with respect to 100 parts by weight as a total of (A) and (B). Particularly preferred is 0.4 to 3 parts by weight. When the content of the component (C) is less than 0.1 parts by weight, delamination of the film itself becomes remarkable. When the content is more than 10 parts by weight, the specific gravity increases and the electrical characteristics may be deteriorated. .

The flame retardant (D) of the present invention is a phosphorus flame retardant, an organic flame retardant represented by a silicone polymer, and an inorganic flame retardant represented by magnesium hydroxide, aluminum hydroxide or ammonium polyphosphate. Among the flame retardants (D), examples of the phosphorus-based flame retardant include red phosphorus, phosphate ester compounds, phosphite ester compounds, and phosphazene compounds. Among these, phosphate compounds and phosphazene compounds are preferable from the viewpoints of adhesion to metals, particularly copper foil, and from the viewpoints of insulation, flame retardancy, and environment. These phosphate ester compounds and phosphazene compounds may be used alone or in combination.
Particularly preferred examples of the phosphoric ester compound include those selected from the group of compounds represented by the following formula (3).

(In the formula, Q ₁ , Q ₂ , Q ₃ and Q ₄ represent an alkyl group having 1 to 6 carbon atoms or hydrogen, n is an integer of 1 or more, and m ₁ , m ₂ , m ₃ and m ₄ are 0. To X, and X is selected from any of the following formulas (4).)

_{(Wherein, S 1, S 2, S} 3 is _{.n 1, n 2,} n ₃ represents methyl group or hydrogen is an integer from 0 to 2.)

Specifically, CR-741, CR-747, CR-733S manufactured by Daihachi Chemical Co., Ltd. are suitable.
The blending amount of the flame retardant (D) in the present invention is preferably contained in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the total of the components (A) and (B). Preferably it is 1-15 weight part, More preferably, it is 3-10 weight part. When this content is less than 0.1 parts by weight, sufficient flame retardancy cannot be obtained, and when it is more than 20 parts by weight, the heat resistance is lowered.

  In the present invention, in addition to the above-described components, other additional components, for example, antioxidants, elastomers (ethylene / propylene copolymers, ethylene / 1, as necessary, as long as the characteristics and effects of the present invention are not impaired. -Butene copolymer, ethylene / propylene / nonconjugated diene copolymer, ethylene / ethyl acrylate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / vinyl acetate / glycidyl methacrylate copolymer and ethylene / propylene -G-Maleic anhydride copolymer, olefin copolymer such as ABS, polyester polyether elastomer, polyester polyester elastomer, vinyl aromatic compound-conjugated diene compound block copolymer, vinyl aromatic compound-conjugated diene compound block Copolymer hydrogenated product), plasticizer (oi , Low molecular weight polyethylene, epoxidized soybean oil, polyethylene glycol, fatty acid esters), flame retardant agents, weathering (light) resistance improvers, various colorants, may be added such as mold release agents.

The film for flexible printed circuit boards of this invention is a thermoplastic film which has said resin composition. The thickness of the film is 5 to 100 μm. From the viewpoint of flexibility, the thickness is further preferably 10 to 70 μm, particularly preferably 20 to 60 μm.
The resin composition of the present invention can be produced by various methods. For example, a heat melt kneading method using a single screw extruder, a twin screw extruder, a roll, a kneader, a Brabender plastograph, a Banbury mixer or the like can be mentioned. Among them, a melt kneading method using a twin screw extruder is most preferable. Although the melt kneading temperature in this case is not particularly limited, it can usually be arbitrarily selected from 150 to 350 ° C.

In particular, from the viewpoint that the molding process is simple, these resin compositions are preferably thermoplastic resins. Molding can be obtained by extrusion film molding, or can be obtained by directly charging each component, which is a raw material of the resin composition of the present invention, into an extrusion film molding machine and simultaneously performing blending and film molding.
The flexible printed circuit board film of the present invention can be produced by an extrusion tubular method, and in some cases, a method called an inflation method. In order to prevent the parison coming out of the cylinder from being cooled immediately, the temperature of the parison is appropriately selected from the temperature range of 50 to 290 ° C., and the temperature of the parison can be made uniform, and the sheet does not have delamination Is extremely important in creating. And the film for flexible printed circuit boards of this invention can be manufactured also by T-die extrusion molding. In this case, it may be used without stretching, may be uniaxially stretched, or may be obtained by biaxially stretching. Stretching is effective for increasing the strength and rigidity of the sheet.

  Although the thickness measuring method of the film for flexible printed circuit boards of this invention is not specifically limited, For example, it can measure with a micro gauge. The thickness is obtained by measuring the flow method and at least 20 points in the direction perpendicular to the average value. The preferred thickness is 5 to 100 μm, further 10 to 70 μm, further 15 to 60 μm, and more particularly 20 to 50 μm. If it is less than 5 μm, handling of the film becomes difficult, and if it exceeds 100 μm, flexibility may be lowered.

The flexible printed circuit board of the present invention is obtained from a film having a resin composition containing the polyphenylene ether resin of the present invention. The basic structure consists of a base film, a metal wiring typified by copper foil, and a coverlay film, and is bonded to each other with an epoxy resin adhesive. In order to cure the uncured adhesive as the method, the temperature is less than 250 ° C., preferably 200 ° C. or less, more preferably 50 to 200 ° C., particularly 80 to 200 ° C., and particularly about 80 to 180 ° C. , Pressure bonding at a pressure of 50 kg / cm ² or less for about 0.5 to 60 minutes, filling the line / space of the flexible printed circuit board with an adhesive, and if necessary, at a temperature of 100 to 200 ° C. under pressure release, The adhesive is cured by heating for about 10 minutes to 30 hours. Furthermore, the flexible printed circuit board of the present invention can be obtained by using a plurality of layers.

A film having a resin composition containing the polyphenylene ether resin of the present invention may be used as a coverlay film, a base film, or both a coverlay film and a base film.
Moreover, when manufacturing the said flexible printed circuit board, a release film is inserted between a press board and the film of this invention as a release material. Materials that can be used as the release film include polyethylene film, polypropylene film, 4-methylpentene-1 resin film, polyethylene film with silicone release agent, polypropylene film with silicone release agent, polyethylene resin-coated paper, polypropylene Examples include resin-coated paper and 4-methylpentene-1-based resin-coated paper. The thickness of the release material is preferably 10 to 75 μm for a film-based material and 50 to 200 μm for a paper-based material. The appropriate thickness is used.
Next, the present invention will be described with reference to examples and reference examples.

The present invention will be described below based on examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.
Production Example 1: Production Example of Polyphenylene Ether (PPE-1) Powdered poly (2,6-dimethyl-1,4-phenylene ether) having a reduced viscosity of 0.43 obtained by oxidative polymerization of 2,6-dimethylphenol ).
Production Example 2: Production Example of Liquid Crystalline Polyester (LCP-1) In a nitrogen atmosphere, p-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, acetic anhydride was charged, heated and melted, and subjected to polycondensation. A liquid crystal polyester (LCP-1) having the following theoretical structural formula was obtained. In addition, the component ratio of a composition represents molar ratio.

Film formation and physical property evaluation of each resin composition and flexible printed circuit board were performed according to the following methods.
(1) T-die extrusion molding The pellet obtained was discharged at a rate of 60 kg / hr and the thickness of the T-die slit using a vented single screw extruder with a screw diameter of 65 mm set at a cylinder temperature of 300 ° C and a T-die temperature of 300 ° C. Extrusion film molding was carried out by controlling the take-up speed so that the thickness was 0.15 mm, the die slit width was 650 mm, the rolling roller surface temperature was 130 ° C., and the thickness was 50 μm.

(2) Fabrication of flexible printed circuit board Using the film obtained in (1) above or a commercially available film as a base film, a copper foil having a thickness of 35 μm and a width of 50 μm is bonded via an epoxy adhesive having a thickness of 20 μm. A copper-clad laminate (a) was obtained. Next, an epoxy-based adhesive having a flow start temperature of 80 ° C. was applied to the film having a thickness of 50 μm at a thickness of 20 μm to obtain a coverlay film (A). A 4-methylpentene-1 resin film (manufactured by Mitsui Chemicals, Inc., TPX (registered trademark) film, MX 004) was used as a release film (c). The films are stacked in the order of (C), (A), (B), and (C) so that the epoxy adhesive layer of (A) is in contact with the copper foil side of (A), and 190 ° C., 50 kgf / cm ^2. A hot press was performed for 1 minute to obtain a flexible printed circuit board.

(3) Heat resistance The film obtained in (1) above is placed horizontally, and a piece of 260 ° C solder with a diameter of about 3 mm that has been previously melted is dropped vertically from a height of 5 cm from the surface of the film. The site was visually observed and the heat resistance was judged according to the following criteria.
○: No deformation was observed in the film.
X: Deformation was observed in the film.

(4) Flame retardance Using the film obtained in (1) above, adjusting the film shape (cylindrical shape) and flame according to the UL-94 film standard of Underwriters Laboratories, the flame contact time for each three sheets The test was carried out once for 2 seconds and judged according to the following criteria.
○: No dripping, all 3 sheets self-extinguished within 10 seconds.
Δ: Dropped only once and self-extinguished, the other two sheets were not dripped and self-extinguished.
X: At least one piece dripped vigorously while continuing to burn.

(5) Flexibility The film obtained in the above (1) was rolled to a diameter of 5 mm and allowed to stand for 1 day, and whether or not the film had cracks was judged according to the following criteria.
○: No crack in both the film flow direction and the direction perpendicular to the flow direction.
X: When a crack is observed in at least one of the flow direction of the film and the direction perpendicular to the flow direction.
(6) Dielectric constant Precision LCR meter HP4284A (Agilent Technology Co., Ltd.) in an atmosphere of 22 ° C. and 60% relative humidity in accordance with JIS-K6911 standard test method using the film obtained in (1) above. The dielectric constant at a frequency of 1 MHz was measured using a device) and an electrode for measurement SE-70 (manufactured by Ando Electric Co., Ltd.).

(7) Moisture absorption resistance Using the flexible printed circuit board obtained in (2) above, cut into a size of 100 × 50 mm square, and using a constant temperature and humidity chamber (PL-3FP, manufactured by Tabai Espec Co., Ltd.), 85 ° C. After being exposed to a warm and humid environment with 95% relative humidity for 120 hours, the weight increase rate (Δw) was determined according to the following formula. The average value of each two circuits was taken.
Weight increase rate (Δw) (%) = (w1−w0) / w0 × 100
(W1: circuit weight after heating / humidification (g), w0: film weight (g) dried in a hot air dryer at 100 ° C. for 2 hours and then cooled to room temperature in a desiccator before heating / humidification)
A smaller weight increase rate (Δw) means better moisture absorption resistance.

[Example 1]
Top feed side barrel temperature of polyphenylene ether (PPE-1), liquid crystal polyester (LCP-1) and zinc oxide (ZnO, Ginbao-A, manufactured by Toho Zinc Co., Ltd.) in the proportions (parts by weight) shown in Table 1. The mixture was melt-kneaded using a twin-screw extruder with a vent port (ZSK-25; manufactured by WERNER & PFLEDERER) at a temperature of only 250 ° C., and the other barrel temperatures and die head temperatures all set at 310 ° C. to obtain pellets. Using this pellet, it was molded by the method shown in (1) above to obtain a film having an average thickness of 48 μm. According to the method shown above, the flexible printed circuit board was produced and the film and the flexible printed circuit board were evaluated. The results are shown in Table 1.

[Example 2]
Polyphenylene ether (PPE-1) and high impact polystyrene (A & M Co., Ltd., H9405, sometimes abbreviated as “HIPS”) and elastomer 1 (Asahi Kasei Co., Ltd., Tuftec (registered trademark) H1051, Table "Elastomer 1" may be abbreviated as "Elastomer 1" and Elastomer 2 (Asahi Kasei Co., Ltd., Tuftec (registered trademark) H1081, may be abbreviated as "Elastomer 2" in the table). Except doing, it carried out similarly to Example 1, and after forming a pellet, film shaping was implemented. The average thickness of the obtained film was 50 μm. Furthermore, according to the method shown above, the flexible printed circuit board was produced and the film and the flexible printed circuit board were evaluated. The results are shown in Table 1.

[Example 3]
(D) As a component, a phosphoric acid ester compound (made by Daihachi Chemical Industry Co., Ltd., CR-741) was used, and it was carried out in the same manner as in Example 1 except that it was blended in the proportions shown in Table 1. After being obtained, film forming was performed. The average thickness of the obtained film was 51 μm. Furthermore, according to the method shown above, the flexible printed circuit board was produced and the film and the flexible printed circuit board were evaluated. The results are shown in Table 1.

[Comparative Example 1]
Polyphenylene ether (PPE-1) and high impact polystyrene (A & M Co., Ltd., H9405, sometimes abbreviated as “HIPS”) and polystyrene (A & M Co., Ltd., 685, abbreviated as “GP” in the table) Except that it is blended in the proportions shown in Table 1, and the same procedure as in Example 1 was carried out to obtain pellets, followed by film forming. The average thickness of the obtained film was 49 μm. Furthermore, according to the method shown above, the flexible printed circuit board was produced and the film and the flexible printed circuit board were evaluated. The results are shown in Table 1.

[Comparative Example 2]
Using a polyimide film having a thickness of 50 μm (manufactured by Toray DuPont Co., Ltd .: Kapton (registered trademark) 200H), a flexible printed circuit board was produced according to the method described above, and the film and the flexible printed circuit board were evaluated. . The results are shown in Table 1.

  From the above, the film having a resin composition mainly composed of the polyphenylene ether resin according to the present invention is excellent in heat resistance, flame retardancy, bending resistance, electrical properties, and moisture absorption resistance. It can be seen that the obtained flexible printed circuit board is excellent in moisture absorption resistance, and therefore a circuit with less dielectric loss due to water absorption can be obtained.

  The present invention is excellent in heat resistance, flame retardancy, flex resistance, electrical properties, moisture absorption resistance and is inexpensive, and is therefore suitable for a flexible printed circuit board with high density mounting.

Claims (8)

(A) A film for a flexible printed circuit board comprising a thermoplastic resin having a resin composition containing 85% by weight or more of a polyphenylene ether resin. (A) A film for a flexible printed circuit board comprising a thermoplastic resin having a resin composition comprising 85 to 99.5 parts by weight of a polyphenylene ether resin and 0.5 to 15 parts by weight of (B) a liquid crystal polyester.   A resin containing 0.1 to 10 parts by weight of a compound containing (C) an I-valent, II-valent, III-valent or IV-valent metal element with respect to a total of 100 parts by weight of the component (A) and the component (B) The film for flexible printed circuit boards of Claim 2 which has a composition.   4. The flexible printed circuit board film according to claim 3, wherein the metal element of (C) I, II, III, or IV is Zn element and / or Mg element.   The flexible print according to any one of claims 2 to 4, which has a resin composition containing 0.1 to 20 parts by weight of a flame retardant (D) with respect to 100 parts by weight of the total of the component (A) and the component (B). Film for substrates.   6. The flexible printed circuit board film according to claim 5, wherein the flame retardant is a phosphate ester compound and / or a phosphazene compound. The film for flexible printed circuit boards according to any one of claims 1 to 6 , having an average thickness of 5 to 100 µm. Flexible printed board circuit consisting of a flexible printed circuit board film according to any one of claims 1-7.