JP4608342B2 - Resin molded product having low dielectric loss tangent and method for producing the same - Google Patents

Description

  The present invention relates to a resin molded article suitable for use in a field requiring high-frequency characteristics, using a resin composition containing a liquid crystalline polyester as a main component, and a method for producing the same.

  Conventionally, liquid crystalline polyesters having excellent electrical characteristics and solder heat resistance as well as chemical resistance, flame retardancy, and mechanical characteristics have been widely used as materials for electronic parts and mechanical parts. For example, a circuit board obtained by forming a metal film on a resin substrate containing a liquid crystalline polyester has good moldability, dimensional stability, high elastic modulus, and strength, so that it can be used as a material for a three-dimensional circuit board (MID). Is also attracting attention.

Examples of circuit boards using liquid crystalline polyester include sputtering, ion plating, and vacuum deposition while heating a resin substrate obtained by molding liquid crystalline polyester so that the surface temperature is 60 ° C. or higher in a vacuum chamber. A circuit board (Patent Document 1) obtained by coating a metal film by any of the methods described above, or a resin composition containing a liquid crystalline polyester and an inorganic filler is formed to produce a resin board, and the surface of the resin board A resin molded product for fine wire circuit (Patent Document 2) obtained by forming a metal film on a substrate by sputtering, ion plating, or vacuum deposition after performing an etching process on the substrate has been proposed. .
Japanese Patent No. 2714440 Japanese Patent Publication No. 7-24328

  By the way, when a circuit board obtained by molding a resin material is placed in an AC electric field, the greater the dielectric loss tangent of the resin material, the greater the amount of internal heat generated by the circuit board. Liquid crystalline polyester has a relatively low dielectric loss tangent (tan δ) among engineering plastics and super engineering plastics. However, in a field requiring high frequency characteristics such as a high frequency circuit board, liquid crystalline polyester has a lower dielectric loss tangent. Development of a system board is desired.

  Accordingly, a main object of the present invention is to provide a resin molded article having a low dielectric loss tangent using a liquid crystalline polyester resin composition.

That is, the resin molded article of the present invention has a residual oxygen concentration of 1 in a molded article for a three-dimensional circuit board obtained by molding a resin composition containing a liquid crystalline polyester and an epoxy group-containing ethylene copolymer by injection molding. % Under an inert gas atmosphere at a temperature between a lower limit temperature 120 ° C. lower than the flow start temperature of the liquid crystalline polyester and an upper limit temperature 20 ° C. lower than the flow start temperature. The dielectric loss tangent is smaller than that of a resin molded product obtained from the resin composition without heat treatment.

The dielectric loss tangent of the resin molded product of the present invention is preferably 90% or less of the dielectric loss tangent of the resin molded product obtained from the resin composition without heat treatment. Also, the content of the epoxy group-containing ethylene copolymer is preferably 0.1 to 25 parts by weight per 100 parts by weight liquid crystalline polyester.

The further objective of this invention is to provide the manufacturing method of an above-described resin molded product. That is, in this production method, a resin composition containing a liquid crystalline polyester and an epoxy group-containing ethylene copolymer is molded by injection molding, and the resulting molded article for a three-dimensional circuit board has a residual oxygen concentration of 1% or less. The resin composition is subjected to heat treatment in an inert gas atmosphere at a temperature between a lower limit temperature 120 ° C. lower than the flow start temperature of the liquid crystalline polyester and an upper limit temperature 20 ° C. lower than the flow start temperature. A resin molded product having a dielectric loss tangent smaller than that obtained from the above is obtained.

  According to the present invention, the dielectric loss tangent can be reduced by subjecting the liquid crystalline polyester resin composition to a heat treatment. Further, when a metal film is formed on a substrate made of this liquid crystalline polyester resin composition, a circuit substrate having improved adhesion and heat resistance as well as a low dielectric loss tangent can be obtained. Thus, the resin molded product of the present invention is suitable for use in the electrical and electronic industry, particularly in technical fields where high frequency characteristics are required.

  Examples of the liquid crystalline polyester having an aromatic skeleton that is a main component of the resin composition constituting the resin molded article of the present invention and preferably forms a melt phase having optical anisotropy include, for example, aromatic diol and aromatic Obtained by transesterification / polycondensation reaction between an acylated product obtained by acylating at least one phenolic hydroxyl group of an aromatic hydroxycarboxylic acid with a fatty acid anhydride and at least one of an aromatic dicarboxylic acid and an aromatic hydroxycarboxylic acid It is preferred to use the product obtained.

  Examples of the aromatic diol include 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, methylhydroquinone, chlorohydroquinone, acetoxyhydroquinone, nitrohydroquinone, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6- Dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2 , 2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-chlorophenyl) propane, Bis- (4-hydroxy Phenyl) methane, bis- (4-hydroxy-3,5-dimethylphenyl) methane, bis- (4-hydroxy-3,5-dichlorophenyl) methane, bis- (4-hydroxy-3,5-dibromophenyl) methane Bis- (4-hydroxy-3-methylphenyl) methane, bis- (4-hydroxy-3-chlorophenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis- (4-hydroxyphenyl) ketone Bis- (4-hydroxy-3,5-dimethylphenyl) ketone, bis- (4-hydroxy-3,5-dichlorophenyl) ketone, bis- (4-hydroxyphenyl) sulfide, bis- (4-hydroxyphenyl) Sulfone can be used. These may be used alone or in combination of two or more. Among these, the use of 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, 2,6-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane, bis- (4-hydroxyphenyl) sulfone, It is preferable from the viewpoint of availability.

  On the other hand, examples of the aromatic hydroxycarboxylic acid include parahydroxybenzoic acid, metahydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-3-naphthoic acid, 1-hydroxy-4-naphthoic acid, 4 -Hydroxy-4'-carboxydiphenyl ether, 2,6-dichloro-parahydroxybenzoic acid, 2-chloro-parahydroxybenzoic acid, 2,6-difluoro-parahydroxybenzoic acid, 4-hydroxy-4'-biphenylcarboxylic acid Can be used. These may be used alone or in combination of two or more. Among these, use of parahydroxybenzoic acid and 2-hydroxy-6-naphthoic acid is preferable in terms of availability.

  Furthermore, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, methyl terephthalic acid, methyl isophthalic acid, Diphenyl ether-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, diphenyl ketone-4,4′-dicarboxylic acid, 2,2′-diphenylpropane-4,4′-dicarboxylic acid are used. be able to. These may be used alone or in combination of two or more. Among these, use of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid is preferable in terms of availability.

  Examples of the fatty acid anhydride include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, pivalic anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromo anhydride Acetic acid, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, and β-bromopropionic anhydride can be used. These may be used individually by 1 type, and may mix and use 2 or more types. Of these, acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride are preferable, and acetic anhydride is more preferable from the viewpoints of price and handleability.

  The transesterification / polycondensation reaction is preferably performed in the presence of an imidazole compound represented by the following chemical formula (1).

Examples of the imidazole compound represented by the formula (1) include imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 4-ethylimidazole, 1, 2-dimethylimidazole, 1,4-dimethylimidazole, 2,4-dimethylimidazole, 1-methyl-2-ethylimidazole, 1-methyl-4-ethylimidazole, 1-ethyl-2-methylimidazole, 1-ethyl- 2-ethylimidazole, 1-ethyl-2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-benzyl-2-methylimidazole, 2 -Phenyl-4-methyl Ruimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 4-cyanoethyl-2-ethyl-4-methylimidazole, 1-aminoethyl-2-methylimidazole can be used. In particularly preferred imidazole compounds, “R ₁ ” is an alkyl group having 1 to 4 carbon atoms, and “R ₂ ” to “R ₄ ” are hydrogen atoms. Furthermore, use of 1-methylimidazole and 2-methylimidazole is preferable from the viewpoint of availability.

  In the transesterification / polycondensation reaction described above, the amount of acylated product and aromatic dicarboxylic acid and / or aromatic hydroxycarboxylic acid is determined by the amount of aromatic diol and / or aromatic hydroxycarboxylic acid used to prepare the acylated product. The amount of the phenolic hydroxyl group is preferably set to 0.8 to 1.2 in terms of the number of hydroxyl groups equivalent to the carboxyl group of the aromatic dicarboxylic acid and / or aromatic hydroxycarboxylic acid. Further, the transesterification reaction is preferably carried out at a rate of 0.1 to 50 ° C./min in the range of 130 to 400 ° C., and 0.3 to 5 ° C./in the range of 150 to 350 ° C. More preferably, the temperature is raised at a rate of minutes.

  As the acylated product, a product obtained by acylating a phenolic hydroxyl group with a fatty acid anhydride in a reactor, or an acylated product having an acylated phenolic hydroxyl group, that is, a fatty acid ester can be used. The amount of fatty acid anhydride is the number of equivalents of the phenolic hydroxyl group of aromatic diol or aromatic hydroxycarboxylic acid, and is set to be in the range of 1.0 to 1.2, more preferably 1.05 to 1.1. It is preferable to do. If the amount of the fatty acid anhydride is less than 1.0 in terms of the number of equivalents of phenolic hydroxyl groups, the raw material may be sublimated during polymerization into a liquid crystalline polyester due to the shift of the equilibrium to the fatty acid anhydride during acylation. is there. In this case, the reaction system is likely to be blocked. On the other hand, when the amount of the fatty acid anhydride exceeds 1.2 times in terms of the number of equivalents of the phenolic hydroxyl group, coloring of the obtained liquid crystalline polyester may be a problem. The acylation is preferably carried out at 130 to 180 ° C. for 30 minutes to 20 hours, more preferably 140 to 160 ° C. for 1 to 5 hours.

  In order to promote the transesterification reaction between the fatty acid ester and the carboxylic acid by utilizing the deviation of the equilibrium, it is preferable to evaporate the by-product fatty acid and the unreacted fatty acid anhydride and remove them from the reaction system. When part of the distilled fatty acid is refluxed to the reaction vessel, the evaporated or sublimated raw material components can be returned to the reactor together with the refluxed fatty acid by condensation or reverse sublimation.

  In the transesterification / polymerization reaction, the amount of the imidazole compound represented by the formula (1) is 100 masses in total of the aromatic dicarboxylic acid, aromatic diol, and aromatic hydroxycarboxylic acid used for the synthesis of the liquid crystal polyester. It is preferable that it is 0.005-1 mass part with respect to a part. From the viewpoint of color tone and productivity of the liquid crystal polyester, the addition amount is more preferably 0.05 to 0.5 parts by mass. If the addition amount is less than 0.005 parts by mass, sufficient contribution to the transesterification / polymerization reaction of the imidazole compound cannot be obtained, and conversely if it exceeds 1 part by mass, it may be difficult to control the reaction. The timing of adding the imidazole compound is not limited on the condition that the imidazole compound is present in the reaction system at the time of transesterification. For example, an imidazole compound may be added immediately before or during the transesterification / polycondensation reaction.

  A catalyst may be used as needed to accelerate the transesterification / polymerization reaction. For example, catalysts include germanium compounds such as germanium oxide, stannous oxalate, stannous acetate, dialkyl tin oxide, tin compounds such as diaryl tin oxide, titanium dioxide, titanium alkoxide, alkoxy titanium silicates. Titanium compounds, antimony compounds like antimony trioxide, metal salts of organic acids like sodium acetate, potassium acetate, calcium acetate, zinc acetate, ferrous acetate, Lewis like boron trifluoride and aluminum chloride Inorganic acids such as acids, amines, amides, hydrochloric acid and sulfuric acid are included.

  The liquid crystalline polyester of the present invention prepared by the transesterification / polymerization reaction described above has an aromatic ring skeleton that forms a melt phase having optical anisotropy. In order to impart heat resistance and impact resistance to the liquid crystalline polyester in a well-balanced manner, it is preferable that at least 30 mol% of a repeating unit represented by the following chemical formula (2) is included. The molecular weight of the liquid crystalline polyester is not limited. For example, the weight average molecular weight of the liquid crystalline polyester is preferably in the range of 10,000 to 50,000.

Moreover, it is preferable that the repeating unit contained in liquid crystalline polyester is selected from the following combinations (a)-(f) based on aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and aromatic diol.
(A): a structural unit based on 2-hydroxy-6-naphthoic acid, a structural unit based on 2,6-naphthalenedicarboxylic acid, or a structural unit based on a mixture of 2,6-naphthalenedicarboxylic acid and terephthalic acid, and 4 Combination with structural unit based on 4,4′-dihydroxybiphenyl (b): In the above combination (a), by replacing part or all of the structural unit based on 4,4′-dihydroxybiphenyl with a structural unit based on hydroquinone Resulting combination (c): In the above combination (a), a combination obtained by replacing part or all of the structural units based on 4,4′-dihydroxybiphenyl with structural units based on 2,6-dihydroxynaphthalene (d ): In the above combination (a), 2,6-naphthalene Combination (e) obtained by replacing part or all of the structural unit based on carboxylic acid with the structural unit based on isophthalic acid: In the above combination (a), part of the structural unit based on 2,6-naphthalenedicarboxylic acid Or a combination (f) obtained by replacing the whole with a structural unit based on a mixture of terephthalic acid and isophthalic acid: In the above combination (a), part or all of the structural unit based on 2-hydroxy-6-naphthoic acid A combination obtained by replacing with structural units based on parahydroxybenzoic acid.

  Among the above (a) to (f), the liquid crystalline polyester contains 30 to 80 mol% of repeating structural units derived from 2-hydroxy-6-naphthoic acid and 10 to 35 mol% of repeating structural units derived from an aromatic diol. And 10 to 35 mol% of repeating structural units derived from aromatic dicarboxylic acid. In this case, it is possible to obtain a higher effect of reducing the dielectric loss tangent together with the excellent characteristics of the liquid crystalline polyester.

  Next, the epoxy group-containing ethylene copolymer, which is an important component of the resin composition constituting the resin molded product of the present invention, will be described. In the present invention, the epoxy group-containing ethylene copolymer contains 80 to 95% by mass of ethylene units and 5 to 15% by mass of at least one of unsaturated carboxylic acid glycidyl ester units and unsaturated glycidyl ether units in the molecule. It is preferable. If the ethylene unit is less than 80% by mass, the heat resistance and toughness of the resin substrate may be reduced. In addition, as described later, when producing a molded circuit board by forming a metal film on the resin molded product of the present invention, in order to improve the adhesion of the metal film, an unsaturated carboxylic acid glycidyl ester unit and It is preferable to contain 5% by mass or more of at least one of unsaturated glycidyl ether units. In addition to these units, an ethylenically unsaturated ester unit can be included as necessary. In this case, the ethylenically unsaturated ester unit is preferably 50% by mass or less.

  For example, a compound giving an unsaturated carboxylic acid glycidyl ester unit or an unsaturated glycidyl ether unit is represented by the following chemical formulas (3) and (4).

  Specifically, glycidyl acrylate, glycidyl methacrylate, itaconic acid glycidyl ester, allyl glycidyl ether, 2-methylallyl glycidyl ether, styrene-p-glycidyl ether, and the like can be used.

  As the epoxy group-containing ethylene copolymer, use is made of a ternary system copolymer having an ethylene-based unsaturated ester in addition to ethylene, unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether, or more. May be. Examples of such ethylenically unsaturated ester compounds include vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and the like. Or an α, β-unsaturated carboxylic acid alkyl ester. Of these, vinyl acetate, methyl acrylate, and ethyl acrylate are particularly preferable.

  And the epoxy group-containing ethylene copolymer usually gives a compound giving an ethylene unit, a compound giving an unsaturated carboxylic acid glycidyl ester unit or an unsaturated glycidyl ether unit, and, if necessary, an ethylenically unsaturated ester unit. The compound can be produced by a method of copolymerizing in the presence of a radical generator under conditions of 500 to 4000 atmospheres and 100 to 300 ° C. Copolymerization may be carried out in the presence of a suitable solvent or chain transfer agent.

  Specifically, as the epoxy group-containing ethylene copolymer, for example, a copolymer comprising an ethylene unit and a glycidyl methacrylate unit, a copolymer comprising an ethylene unit, a glycidyl methacrylate unit and a glycidyl methyl acrylate unit, an ethylene unit and a glycidyl methacrylate A copolymer composed of units and glycidylethyl acrylate units, or a copolymer composed of ethylene units, glycidyl methacrylate units and vinyl acetate units can be used. In particular, the use of a copolymer composed of ethylene units and glycidyl methacrylate is preferred.

  The epoxy group-containing ethylene copolymer preferably has a melt index (MFR: JIS K7210, measurement conditions: 190 ° C., 2.16 kg load) in the range of 0.5 to 100 g / 10 min, more preferably 2 ~ 50 g / 10 min. In this range, there is an advantage that good mechanical properties of the resin substrate and compatibility with the liquid crystal polyester can be obtained.

  In the resin molded product of the present invention, the content of the epoxy group-containing ethylene copolymer is preferably 0.1 to 25 parts by mass, more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the liquid crystalline polyester. It is. In this range, the heat treatment effect for reducing the dielectric loss tangent becomes higher. If the content is less than 0.1 parts by mass, the adhesion of the metal film for circuit pattern provided on the resin molded product is likely to be lowered, making it difficult to use the resin molded product of the present invention as a circuit board. There is a fear. On the other hand, if the content exceeds 25 parts by mass, the moldability and heat resistance of the resin composition may be reduced.

  If necessary, an inorganic filler may be added to the resin composition in order to reinforce the resin substrate. The kind of inorganic filler is not limited. For example, fibrous inorganic fillers, whiskers, plate-like inorganic fillers, and powdery inorganic fillers can be added to the resin composition as the inorganic filler.

  The resin molded product of the present invention is obtained by molding a resin composition containing the above-described liquid crystalline polyester, an epoxy group-containing ethylene copolymer, and, if necessary, an inorganic filler, and flowing the liquid crystalline polyester into the obtained molded product. It is obtained by applying a heat treatment at a temperature lower than the starting temperature. The resin molded product that has been heat-treated in this manner has a smaller dielectric tangent than a resin molded product obtained from the resin composition without the heat treatment.

Heat treatment is to heat treatment to the substrate at a temperature between 20 ° C. lower maximum temperature than 120 ° C. and a low minimum temperature than the flow temperature flow initiation temperature of the liquid-crystalline polyester. The flow starting temperature is a capillary rheometer having a nozzle with an inner diameter of 1 mm and a length of 10 mm. Under a load of 100 kgf / cm ² (980 N / cm ² ), the heated melt is discharged from the nozzle at a heating rate of 4 ° C./min. It means the temperature at which the melt viscosity exhibits 48000 poise when extruded. The related standard in JIS is K6719-1977. If the heat treatment temperature is lower than the lower limit temperature, the effect of the heat treatment cannot be sufficiently obtained, and if the heat treatment temperature is higher than the upper limit temperature, the resin substrate may be warped or deformed. This heat treatment residual oxygen concentration of 1% or less, preferably under conditions that 0.5% or less, rows that will in inert gas such as a nitrogen gas atmosphere. Moreover, it is preferable that the heat processing time is the range for 1-4 hours from a viewpoint of preventing the quality change of the resin substrate.

  According to the heat treatment, the heat resistance of the resin substrate can be improved in addition to the improvement of the electrical characteristics such as the high frequency characteristics due to the decrease of the dielectric loss tangent. Furthermore, when using the resin molded product of this invention as a circuit board, the adhesiveness of the metal film formed on it can be improved. Of course, the resin molded product of the present invention stably maintains the excellent chemical resistance, low linear expansion coefficient, flame retardancy, mechanical strength, electrical insulation, vibration damping and elastic modulus inherent in liquid crystalline polyester. Yes. Therefore, the resin molded product according to the present invention will be suitably used as, for example, an antenna, a waveguide, or a substrate for optical transmission in addition to the circuit board.

  As an example, a method of manufacturing a circuit board by forming a metal film on a resin substrate provided by the resin molded product of the present invention will be introduced below.

  Prior to forming the metal coating, it is preferable to perform plasma treatment on the surface of the heat-treated resin substrate. Since the epoxy group-containing ethylene copolymer in the resin composition has a highly reactive functional group, the surface of the resin substrate is effectively activated by plasma treatment. Therefore, the effect of the plasma treatment on the adhesion of the metal film is high.

The plasma processing can be performed using an existing plasma processing apparatus. For example, it is possible to use a plasma processing apparatus including a pair of electrodes opposed to each other in the chamber and a high frequency unit for applying a high frequency electric field between the electrodes. In this case, the resin substrate is disposed on one electrode, and the chamber is decompressed to about 10 ⁻⁴ Pa. Next, a plasma forming gas such as N ₂ or NH ₃ is introduced into the chamber so that the pressure inside the chamber is 8 to 15 Pa. Next, using a high frequency unit, 300 W high frequency power (13.56 MHz) is applied between the electrodes for 10 to 100 seconds to generate plasma between the electrodes, and the resin substrate is generated by cations and radicals in the generated plasma. To activate the surface. During the plasma treatment, nitrogen polar groups and oxygen polar groups that are easily bonded to the metal are imparted to the surface of the resin substrate by collision with cations, so that the adhesion of the metal coating is further improved.

  The plasma processing conditions can be arbitrarily set as long as the surface of the resin substrate is not excessively roughened by the plasma processing. Also, the type of plasma forming gas is not limited. For example, as described above, nitrogen is preferably used as the plasma forming gas. When nitrogen plasma is used, the desorption of carbon dioxide gas due to the cleavage of the ester bond of the resin substrate can be reduced as compared with the case where oxygen plasma treatment is used. As a result, the strength reduction of the surface layer portion of the resin substrate can be avoided.

  For the formation of the metal coating, it is preferable to use a physical vapor deposition method such as sputtering, vacuum vapor deposition, or ion plating. When performing the above-described plasma treatment, it is preferable to continuously perform film formation without bringing the resin substrate into contact with the atmosphere. The metal material which comprises a metal film is not limited. For example, it can be selected from the group consisting of copper, nickel, gold, aluminum, titanium, molybdenum, chromium, tungsten, tin, lead, brass, nichrome, and alloys thereof.

When the DC sputtering method is employed as sputtering, for example, the chamber having a resin substrate inside is decompressed to 10 ⁻⁴ Pa or less, and then an inert gas such as argon is introduced into the chamber so that the internal pressure becomes about 0.1 Pa. To introduce. Next, a copper film having a thickness of 200 to 500 nm can be formed on the resin substrate as a metal film by applying a DC voltage of 500 V to bombard the copper target.

When the electron beam heating vacuum deposition method is adopted as the vacuum deposition, for example, a chamber having a resin substrate inside is decompressed to 10 ⁻⁴ Pa or less, and an electron current of 400 to 800 mA is made to collide with the metal material in the crucible. To evaporate the metal material. Thereby, a copper film having a film thickness of about 300 nm can be formed on the resin substrate as a metal film.

In the case of employing ion plating, for example, a chamber having a resin substrate inside is decompressed to 10 ⁻⁴ Pa or less, and the metal material is evaporated in the same manner as in the case of vacuum deposition. Further, an inert gas such as argon is introduced between the resin substrate and the crucible so that the internal pressure becomes 0.05 to 0.1 Pa. Next, with a desired bias voltage applied to the electrode holding the resin substrate, 500 W of high frequency power (13.56 MHz) is applied to the induction antenna to generate plasma in the chamber. Thereby, a copper film having a thickness of 200 to 500 nm can be formed on the resin substrate as a metal film.

Next, a circuit pattern is formed on the metal film formed on the resin substrate. For example, it is recommended to employ laser patterning from the viewpoint of efficiently removing unnecessary metal coating other than the circuit portion without reducing the adhesion of the metal coating. According to the present invention, it is not necessary to perform a roughening treatment for improving the adhesion of the metal coating prior to the formation of the coating, which causes the formation of the metal coating on the roughened surface of the resin substrate. A fine circuit pattern can be accurately formed by laser patterning without lowering the wiring accuracy. Therefore, the resin molded article of the present invention, Ru der suitable for three-dimensional circuit board (MID).

  After the laser patterning, an additional metal film such as copper may be formed on the formed circuit pattern by electrolytic plating so that the total thickness becomes, for example, 5 to 20 μm. Soft etching may be performed to reliably remove an unnecessary metal film remaining on the resin substrate. Further, a nickel plating layer or a gold plating layer having a thickness of about several μm may be provided on the additional metal film. Thus, the molded circuit board which has a desired circuit pattern can be obtained by using the resin molded product of this invention.

  The present invention will be specifically described based on examples.

(Synthesis of liquid crystalline polyester “S1”)
911 g (6.6 mol) of p-hydroxybenzoic acid, 409 g (2.2 mol) of 4,4′-dihydroxybiphenyl, 274 g (1.65 mol) of terephthalic acid, and 91 g (0.55 mol) of isophthalic acid ) And 1235 g (12.1 mol) of acetic anhydride, 0.17 g of 1-methylimidazole, and a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser. The inside was sufficiently replaced with nitrogen gas. Subsequently, it heated up to 150 degreeC over 15 minutes under nitrogen gas stream, and was made to recirculate | reflux at 150 degreeC for 3 hours.

  Next, 1.69 g of 1-methylimidazole was further added, and the temperature was raised to 320 ° C. over 2 hours and 50 minutes while distilling off by-product acetic acid and unreacted acetic anhydride. The content was taken out as deemed complete. The solid content obtained from the contents was cooled to room temperature, pulverized with a coarse pulverizer, and the resulting powder was heated from room temperature to 250 ° C. over 1 hour in a nitrogen atmosphere, and from 250 ° C. to 288 ° C. The temperature was raised over time and held at 288 ° C. for 3 hours to proceed the solid phase polymerization reaction. In this way, liquid crystalline polyester “S1” was obtained. The flow start temperature of this liquid crystalline polyester measured using a flow tester [manufactured by Shimadzu Corporation, “CFT-500 type”] is 320 ° C.

(Synthesis of liquid crystalline polyester “S2”)
752.72 g (4.00 mol) of 2-hydroxy-6-naphthoic acid, 220.22 g (2.00 mol) of hydroquinone, 432.38 g (2.00 mol) of 2,6-naphthalenedicarboxylic acid, anhydrous Acetic acid 986.19 (9.2 mol) was put in a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, and 0.143 g of 1-methylimidazole was further added as a catalyst. . The resulting mixture was stirred at room temperature for 15 minutes and then heated to 145 ° C. with stirring. At this temperature, the resulting mixture was further stirred for 1 hour.

  Next, the temperature was increased from 145 ° C. to 310 ° C. over 3 hours while distilling off by-product acetic acid and unreacted acetic anhydride. After further adding 1.427 g of 1-methylimidazole, the mixture was kept at 310 ° C. for 30 minutes to obtain an aromatic polyester. The obtained aromatic polyester was cooled to room temperature and pulverized by a pulverizer to obtain an aromatic polyester powder (particle diameter of about 0.1 mm to about 1 mm).

  The powder obtained above was heated from 25 ° C. to 250 ° C. over 1 hour, then heated from the same temperature to 320 ° C. over 5 hours, and then kept at that temperature for 3 hours to promote the solid-state polymerization reaction. did. Thus, liquid crystalline polyester “S2” was obtained. The flow starting temperature of this liquid crystalline polyester measured using a flow tester [manufactured by Shimadzu Corporation, “CFT-500 type”] was 333 ° C.

  On the other hand, “bond first (registered trademark)” “BF-E”, “BF-2C”, “BF-7M” and “BF-2B” manufactured by Sumitomo Chemical Co., Ltd. are used as the ethylene copolymer containing epoxy group. It was used. Bond first “BF-E” is an ethylene-glycidyl methacrylate copolymer (glycidyl methacrylate content 12 mass%, MFR = 3 g / 10 min). Bond first “BF-2C” is an ethylene-glycidyl methacrylate copolymer (glycidyl methacrylate content: 6 mass%: MFR = 3 g / 10 min). Bond First “BF-7M” is an ethylene-glycidyl methacrylate-methyl acrylate copolymer (glycidyl methacrylate content 6 mass%, methyl acrylate content 30 mass%: MFR = 9 g / 10 min). Bond First “BF-2B” is an ethylene-glycidyl methacrylate-vinyl acetate copolymer (glycidyl methacrylate content 12 mass%, vinyl acetate 5 mass%: MFR = 3 g / 10 min). MFR (melt flow rate) is a value measured under conditions of 190 ° C. and 2160 g load in accordance with JIS-K7210.

  If necessary, as an inorganic filler, milled glass fiber (MGF: “EFH-7501” manufactured by Central Glass Co., Ltd .: fiber diameter 10 μm, aspect ratio 10), barium titanate (“NPO-S” manufactured by Fuji Titanium): An average particle size of 2.1 μm) and strontium titanate (“ST-1” manufactured by Fuji Titanium Co., Ltd .: average particle size of 1.1 μm) were used.

Example 1
Resin composition by mixing 100 parts by mass of liquid crystalline polyester “S1” with 10 parts by mass of an epoxy group-containing ethylene copolymer “BF-E” and 100 parts by mass of barium titanate powder “NPO-S” as an inorganic filler. Was prepared. Using a twin screw extruder (Ikegai Iron Works Co., Ltd. “PCM-30”), pellets of this resin composition were prepared at 340 ° C. The obtained pellets were injection molded at a cylinder temperature of 350 ° C. and a mold temperature of 130 ° C. using an injection molding machine “PS40E5ASE” manufactured by Nissei Plastic Industry Co., Ltd. to obtain a resin substrate of 40 mm × 30 mm × thickness 1 mm. .

Next, the resin substrate was heat-treated at 300 ° C. for 3 hours in a nitrogen atmosphere. Thereafter, the surface of the resin substrate was subjected to plasma treatment. That is, first, the resin substrate was set in the chamber of the plasma processing apparatus, and the chamber was decompressed to about 10 ⁻⁴ Pa. Further, N ₂ was introduced into the chamber so that the gas pressure in the chamber was 10 Pa. Thereafter, a 300 W high-frequency voltage (13.56 MHz) was applied between the electrodes of the plasma processing apparatus for 30 seconds to perform plasma processing on the resin substrate. After the plasma treatment, a metal film was formed on the plasma treated surface of the resin substrate using a DC magnetron sputtering apparatus. That is, after reducing the pressure of the chamber to 10 ⁻⁴ Pa or less, argon gas was introduced into the chamber so that the gas pressure in the chamber was 0.1 Pa, and a DC voltage of 500 V was further applied, so that the copper target And a copper film having a thickness of 400 nm was formed as a metal film on the resin substrate.

  Next, a pattern having a width of 5 mm was formed on the metal film by laser irradiation, and a copper pattern was plated on the metal film pattern by electrolytic plating to obtain a circuit pattern for a peel strength test having a thickness of 15 μm on the resin substrate. .

(Examples 2 to 4)
In each of Examples 2 to 4, as shown in Table 1, peeling was performed based on the same method as Example 1 except that different amounts of an epoxy group-containing ethylene copolymer “BF-E” was used. A resin substrate having a circuit pattern for strength test was manufactured.

(Comparative Example 1)
A resin substrate having a circuit pattern for peel strength test was manufactured based on the same method as in Example 1 except that the epoxy group-containing ethylene copolymer was not used and heat treatment was not performed.

(Comparative Example 2)
A resin substrate having a circuit pattern for peel strength test was manufactured based on the same method as in Example 1 except that no heat treatment was performed.

(Comparative Example 3)
A circuit pattern for peel strength test was formed based on the same method as in Example 1 except that the addition amount of the epoxy group-containing ethylene copolymer “BF-E” was 24 parts by mass and no heat treatment was performed. A resin substrate having the same was manufactured.

  About said Examples 1-4 and Comparative Examples 1-3, the dielectric loss tangent (tan (delta)) of the resin substrate and the 90 degree | times peel strength of a circuit pattern were measured. That is, the dielectric loss tangent of the resin substrate at 1 GHz was obtained by performing impedance measurement based on the RF IV method using an RF impedance / material analyzer (HP 4291A). On the other hand, the peel strength was measured using a universal testing machine (“EG Test” manufactured by Shimadzu Corporation). The results are shown in Table 1.

  As can be seen from a comparison between Example 1 and Comparative Example 2 using a resin substrate having the same composition as Example 1, the dielectric loss tangent is significantly reduced by performing the heat treatment. That is, the dielectric loss tangent of the heat-treated resin substrate of Example 1 corresponds to approximately 77% of the dielectric loss tangent of the resin substrate of Comparative Example 2 without heat treatment. Similarly, from the results of Example 4 and Comparative Example 3 using a resin substrate having the same composition as Example 4, the dielectric loss tangent of the heat-treated resin substrate of Example 3 is that of the resin substrate of Comparative Example 3 without heat treatment. This corresponds to approximately 60% of the dielectric loss tangent. Moreover, in Comparative Examples 1-3 without heat processing, a dielectric loss tangent also increases with the increase in content of an epoxy-group-containing ethylene copolymer. On the other hand, in Examples 1 to 4 in which the heat treatment of the present invention was performed, the dielectric loss tangent decreases as the content of the epoxy group-containing ethylene copolymer increases. Thus, the heat treatment of the present invention provides a special effect of reducing the dielectric loss tangent when the liquid crystalline polyester resin substrate contains an epoxy group-containing ethylene copolymer. Furthermore, the comparison between Examples 1 and 4 and Comparative Examples 2 and 3 shows that the heat treatment is also effective for improving the adhesion of the circuit pattern.

(Example 5)
Except that 100 parts by mass of liquid crystalline polyester “S1” was mixed with 15 parts by mass of an epoxy group-containing ethylene copolymer “BF-E” and 67 parts by mass of milled glass fiber “MGF” to prepare a resin composition. A resin substrate having a peel strength test circuit pattern was produced based on the same method as in Example 1.

(Examples 6 to 8)
In each of Examples 6 to 8, as shown in Table 2, Example 5 and Example 5 were used except that an epoxy group-containing ethylene copolymer different from the epoxy group-containing ethylene copolymer “BF-E” was used. A resin substrate having a circuit pattern for peel strength test was produced based on the same method.

  For Examples 5 to 8, as in the case of Example 1, the dielectric loss tangent (tan δ) and the 90-degree peel strength of the circuit pattern were measured. Further, the deflection temperature under load (DTUL) at a load of 1.82 MPa was measured according to ASTM D648. The results are shown in Table 2.

  As can be seen from the results in Table 2, the dielectric loss tangent of the resin substrate in Examples 5, 6, and 8 using the epoxy group-containing ethylene copolymer in which the content of ethylene units in the molecule is 80% or more is The ethylene unit content is significantly lower than the dielectric loss tangent of the resin substrate in Example 7 using an epoxy group-containing ethylene copolymer of less than 80 wt%. Further, the resin substrates in Examples 5, 6, and 8 have a DTUL higher than that of the resin substrate in Example 7 while maintaining good adhesion of the circuit pattern. For these reasons, it is preferable to use an epoxy group-containing ethylene copolymer in which the content of ethylene units in the molecule is 80 wt% or more.

Example 9
A resin composition was prepared by mixing 10 parts by mass of epoxy group-containing ethylene copolymer “BF-E” and 200 parts by mass of strontium titanate powder “ST-1” with 100 parts by mass of liquid crystalline polyester “S2”. A resin substrate having a peel strength test circuit pattern was produced based on the same method as in Example 1.

(Example 10)
A resin composition was prepared by mixing 10 parts by mass of epoxy group-containing ethylene copolymer “BF-E” and 200 parts by mass of strontium titanate powder “ST-1” with 100 parts by mass of liquid crystalline polyester “S1”. A resin substrate having a peel strength test circuit pattern was produced based on the same method as in Example 1.

(Comparative Example 4)
A resin substrate having a circuit pattern for peel strength test was manufactured based on the same method as in Example 9 except that no heat treatment was performed.

(Comparative Example 5)
A resin substrate having a circuit pattern for peel strength test was manufactured based on the same method as in Example 10 except that no heat treatment was performed.

  For Examples 9 and 10 and Comparative Examples 4 and 5, as in Example 1, the dielectric loss tangent (tan δ) and the 90-degree peel strength of the circuit pattern were measured. The results are shown in Table 3.

  As can be seen from a comparison between Example 9 and Comparative Example 4 using a resin substrate having the same composition as Example 9, the dielectric loss tangent is significantly reduced by performing the heat treatment. That is, the dielectric loss tangent of the heat-treated resin substrate of Example 9 corresponds to approximately 88% of the dielectric loss tangent of the resin substrate of Comparative Example 4 without heat treatment. Similarly, the results of Example 10 and Comparative Example 5 using the resin substrate having the same composition as Example 10 show that the dielectric loss tangent of the heat-treated resin substrate of Example 10 is that of the resin substrate of Comparative Example 5 without heat treatment. This corresponds to approximately 98% of the dielectric loss tangent. Further, these results indicate that the liquid crystalline polyester “S2” is more preferable than the liquid crystalline polyester “S1” from the viewpoint of reducing the original dielectric loss tangent and further reducing the dielectric loss tangent.

(Examples 11-14)
In each of Examples 11 to 14, 67 parts by mass of milled glass fiber (MGF) “EFH-7501” was used as an inorganic filler instead of barium titanate powder “NPO-S”, and Table 4 shows. A resin substrate having a peel strength test circuit pattern was manufactured based on the same method as in Example 1 except that the resin substrate was subjected to heat treatment under conditions.

(Comparative Example 6)
A resin substrate having a circuit pattern for peel strength test was produced based on the same method as in Example 11 except that no heat treatment was performed.

(Comparative Example 7)
A resin substrate having a circuit pattern for peel strength test was produced based on the same method as in Example 11 except that the epoxy group-containing ethylene copolymer was not used and heat treatment was not performed.

(Comparative Example 8)
It has a peel strength test circuit pattern based on the same method as Example 11 except that the epoxy group-containing ethylene copolymer was not used and the resin substrate was heat-treated under the conditions shown in Table 4. A resin substrate was manufactured.

  For Examples 11 to 14 and Comparative Example 6 described above, the peel strength (90-degree peel strength), dielectric loss tangent (tan δ), and DTUL of the peel strength test pattern circuit were measured in the same manner as in the above Examples. Moreover, the solder heat resistance temperature of the resin substrate was evaluated based on the following method. That is, after the resin substrate sample was immersed in a solder bath for 60 seconds, the occurrence of deformation was checked. The minimum solder bath temperature at which deformation occurred was determined as the heat resistant temperature. The results are shown in Table 4.

  As can be seen from the results in Table 4, each of the resin substrates of Examples 11 to 14 that had been subjected to heat treatment had a smaller dielectric tangent than the resin substrate of Comparative Example 6 without heat treatment. For example, in the comparison between Example 11 and Comparative Example 6 using a resin substrate having the same composition as Example 11, the dielectric loss tangent is significantly reduced by performing heat treatment. That is, the dielectric loss tangent of the heat-treated resin substrate of Example 11 corresponds to approximately 76% of the dielectric loss tangent of the resin substrate of Comparative Example 6 without heat treatment. Solder heat resistance and DTUL were also improved by heat treatment. Furthermore, the results of Examples 11 to 14 indicate that the dielectric loss tangent decreases and the adhesion of the circuit pattern tends to increase as the heat treatment temperature increases. On the other hand, the results of Comparative Examples 7 and 8 indicate that the dielectric loss tangent may be increased by heat treatment when the resin substrate does not contain an epoxy group-containing ethylene copolymer.

Claims (9)

An inert gas atmosphere on a molded article for a three-dimensional circuit board obtained by molding a resin composition containing a liquid crystalline polyester and an epoxy group-containing ethylene copolymer by injection molding under a condition where the residual oxygen concentration is 1% or less And obtained by performing a heat treatment at a temperature between a lower limit temperature 120 ° C. lower than the flow start temperature of the liquid crystalline polyester and an upper limit temperature 20 ° C. lower than the flow start temperature, and obtained from the resin composition without heat treatment. A resin molded product characterized by having a dielectric loss tangent smaller than the resin molded product obtained.   2. The resin molded product according to claim 1, wherein the dielectric tangent of the resin molded product is 90% or less of the dielectric loss tangent of the resin molded product obtained from the resin composition without heat treatment. The content of the epoxy group-containing ethylene copolymer, a resin molded article according to claim 1 or 2, characterized in that 0.1 to 25 parts by weight per 100 parts by weight liquid crystalline polyester. The epoxy group-containing ethylene copolymer contains 80 to 95% by mass of ethylene units and 5 to 15% by mass of at least one of an unsaturated carboxylic acid glycidyl ester unit and an unsaturated glycidyl ether unit in the molecule. The resin molded product according to any one of claims 1 to 3 . The liquid crystalline polyester comprises 30 to 80 mol% of repeating units derived from 2-hydroxy-6-naphthoic acid, 10 to 35 mol% of repeating units derived from an aromatic diol, and repeating units derived from an aromatic dicarboxylic acid. The resin molded product according to any one of claims 1 to 4, comprising 10 to 35 mol%. Resin molded article according to any one of claims 1 to 5, characterized in that it has a metal film formed on the circuit patterns. A resin composition containing a liquid crystalline polyester and an epoxy group-containing ethylene copolymer is molded by injection molding, and the resulting molded article for a three-dimensional circuit board is subjected to an inert gas atmosphere under a condition where the residual oxygen concentration is 1% or less. Among them, heat treatment is performed at a temperature between a lower limit temperature that is 120 ° C. lower than the flow start temperature of the liquid crystalline polyester and an upper limit temperature that is 20 ° C. lower than the flow start temperature, and a resin molded product obtained from the resin composition without heat treatment A method for producing a resin molded product comprising obtaining a resin molded product having a small dielectric loss tangent. The liquid crystalline polyester includes an acylated product obtained by acylating at least one phenolic hydroxyl group of an aromatic diol and an aromatic hydroxycarboxylic acid with a fatty acid anhydride, and at least one of an aromatic dicarboxylic acid and an aromatic hydroxycarboxylic acid. The method for producing a resin molded article according to claim 7 , wherein the resin molded article is prepared by transesterification / polycondensation reaction with a seed. The method for producing a resin molded product according to claim 8 , wherein the transesterification reaction and the polycondensation reaction are carried out in the presence of an imidazole compound represented by the following chemical formula.

(However, each of R _{1 to} R ₄ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxymethyl group, a cyano group, a cyanoalkyl group having 1 to 4 carbon atoms, or a cyanoalkoxy having 1 to 4 carbon atoms. Selected from a group, a carboxyl group, an amino group, an aminoalkyl group having 1 to 4 carbon atoms, an aminoalkoxy group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, a phenylpropyl group, and a formyl group.