JP4912603B2 - Method for producing resin-impregnated base material for circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin-impregnated base material for a circuit board which base material can be produced constantly, and can be used in response to a high-density circuit board. <P>SOLUTION: The resin-impregnated base material for the circuit board is made by impregnating a nonwoven fabric formed on a carrier sheet made of aromatic group liquid crystal polyester fibers with a matrix resin made of an aromatic group liquid crystal polyester, and drying the nonwoven fabric. It is desirable that the carrier sheet be a metal foil for a circuit board, that the weight per square meter of the nonwoven fabric made of the aromatic group liquid crystal polyester fibers be 6 to 10 g/m<SP>2</SP>, and that the melting point of aromatic group liquid crystal polyester fibers be 290&deg;C or lower. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a resin-impregnated base material for circuit boards.

  As electronic devices have become smaller and more multifunctional in recent years, circuit boards have also been increased in density and wiring patterns, and means for achieving such conditions include multilayer circuit boards. . A multilayer circuit board formed by laminating a plurality of wiring layers is generally referred to as a through hole, via hole, or interstitial via hole, and has a pore such as a through hole or a non-through hole whose inner wall is covered or filled with a metal conductive layer. Each layer is electrically connected to each other, and the diameter of the hole is being reduced with the miniaturization of the circuit. Along with the reduction in the diameter of the hole, a hole drilling method using a laser is becoming common as a hole drilling method instead of a conventional drilling method.

  As an insulating substrate for a printed wiring board, a resin-impregnated substrate in which a glass woven fabric is impregnated with a matrix resin such as an epoxy resin or a polyimide resin is common, but the laser piercing process of the glass woven fabric is low, There was a problem that the shape of the inner wall surface of the hole deteriorated.

  In order to solve such a problem, a nonwoven fabric such as a glass nonwoven fabric or an aramid nonwoven fabric is used in place of the glass woven fabric. In the case of a non-woven fabric, the laser drilling processability is improved and the shape of the inner wall surface is stabilized.

  However, the nonwoven fabric has lower mechanical strength than the woven fabric. Therefore, in the matrix resin impregnation process, when the nonwoven fabric is pulled up from the impregnation tab, the nonwoven fabric may be cut. In particular, in the case of a thin non-woven fabric corresponding to the higher density of the circuit board, there is a problem that the cutting frequency is high.

In order to solve such a problem in the matrix resin impregnation process, a heat resistant temperature of 150
After applying a liquid matrix resin on one side of a carrier sheet made of synthetic resin film or circuit metal foil at ℃ or higher, laminate a nonwoven fabric or woven fabric on it, impregnate the resin, and then dry and semi-cure A method of manufacturing a resin-impregnated base material by processing is proposed (Patent Documents 1 and 3). In this method, when the non-woven fabric is laminated on the carrier sheet, it is necessary to apply a matrix resin or the like in advance instead of the adhesive, and there is a disadvantage that the number of steps increases. Further, there has been a problem that delamination easily occurs between the matrix resin instead of the adhesive and the matrix resin impregnated thereafter.

  In addition, after applying a liquid matrix resin on one side of the circuit metal foil, a nonwoven fabric or woven fabric is laminated, and then heated at a temperature at which the resin is reflowed to impregnate the nonwoven fabric or woven fabric with the resin component. Thus, a method for producing a resin-impregnated base material has been proposed (Patent Documents 2 and 3). In this way, in order to produce a uniform resin-impregnated substrate, the matrix resin must be reheated during reflow. The matrix resin has a disadvantage that it is completely cured when heated at a temperature higher than the curing temperature, or even when the temperature is lower than the curing temperature for a long time, and the semi-cured resin-impregnated substrate state cannot be maintained. . Therefore, there has been a problem that the temperature and time of reflow must be controlled with high accuracy.

  Furthermore, if the metal foil for circuit boards comes into direct contact with the nonwoven fabric or woven fabric, metal migration may occur along the fibers from this contact area, impairing the insulation of the resin-impregnated base material for circuit boards. (Patent Document 3).

WO99 / 28126 JP 2003-249739 A JP 2004-82687 A

  An object of the present invention is to provide a resin-impregnated base material for a circuit board that can be stably produced and can cope with a higher density of the circuit board.

As a result of intensive studies to solve the above problems, the present inventors have impregnated a matrix resin composed of an aromatic liquid crystal polyester into a nonwoven fabric composed of an aromatic liquid crystal polyester fiber provided on a carrier sheet, and then dried the circuit board. Found a resin-impregnated base material. Further, the carrier sheet is a metal foil for circuit boards, the basis weight of the nonwoven fabric made of aromatic liquid crystal polyester fiber is 6 to 10 g / m ² , and the melting point of aromatic liquid crystal polyester fiber is 290 ° C. or less. Thus, it has been found that a higher performance resin-impregnated base material for circuit boards can be provided.

  In the present invention, a nonwoven fabric is provided on a carrier sheet in a resin-impregnated base material obtained by impregnating a matrix resin into an ultrathin nonwoven fabric corresponding to high densification, and the mechanical strength of the nonwoven fabric is compensated. By using a nonwoven fabric made of aromatic liquid crystal polyester fiber as the nonwoven fabric, the carrier sheet and the nonwoven fabric can be completely bonded even when there is no adhesive by pressing the carrier sheet and the nonwoven fabric at a temperature equal to or higher than the melting point of the fiber. Can be integrated.

  Further, when a metal foil is used as a carrier sheet, if a nonwoven fabric or woven fabric made of a resin having a high water absorption rate is used, metal migration may occur along the fiber from the contact portion between the metal foil and the nonwoven fabric. In the resin-impregnated base material of the present invention, both the nonwoven fabric and the matrix resin used for the insulating base material are aromatic liquid crystal polyesters and have a characteristic of low hygroscopicity, so that metal migration hardly occurs.

  The aromatic liquid crystal polyester used in the aromatic liquid crystal polyester fiber according to the present invention and the aromatic liquid crystal polyester used in the matrix resin are polyesters called a thermotropic liquid crystal polymer, and are optically different at a temperature of 450 ° C. or lower. It forms a melt exhibiting directionality.

As an aromatic liquid crystal polyester, for example,
(1) What is obtained by polymerizing a combination of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid and an aromatic diol,
(2) those obtained by polymerizing different kinds of aromatic hydroxycarboxylic acids,
(3) What is obtained by polymerizing a combination of an aromatic dicarboxylic acid and an aromatic diol,
(4) A product obtained by reacting an aromatic hydroxycarboxylic acid with a crystalline polyester such as polyethylene terephthalate,
Etc. In addition, you may use those ester-forming derivatives instead of these aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, or aromatic diol.

  Examples of the ester-forming derivative of carboxylic acid include those in which the carboxyl group is a highly reactive derivative such as an acid chloride or an acid anhydride that promotes the polyester formation reaction, and the carboxyl group is an ester. Examples include those that form esters with alcohols, ethylene glycol, or the like that form polyesters by an exchange reaction.

  Examples of the ester-forming derivative of a phenolic hydroxyl group include those in which a phenolic hydroxyl group forms an ester with a carboxylic acid so that a polyester is produced by a transesterification reaction.

  In addition, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids and aromatic diols are halogen atoms such as chlorine atoms and fluorine atoms, alkyl groups such as methyl groups and ethyl groups, phenyl groups, as long as they do not inhibit ester formation. It may be substituted with an aryl group such as a group.

  The repeating structural unit of the aromatic liquid crystal polyester can be exemplified by the following chemical formulas 1 to 3, but is not limited thereto.

上記の繰り返し構造単位は、ハロゲン原子またはアルキル基で置換されていてもよい。 Repeating structural units derived from aromatic hydroxycarboxylic acids:

The above repeating structural unit may be substituted with a halogen atom or an alkyl group.

上記の繰り返し構造単位は、ハロゲン原子、アルキル基またはアリール基で置換されていてもよい。 Repeating structural units derived from aromatic dicarboxylic acids:

The above repeating structural unit may be substituted with a halogen atom, an alkyl group or an aryl group.

上記の繰り返し構造単位は、ハロゲン原子、アルキル基またはアリール基で置換されていてもよい。 Repeating structural units derived from aromatic diols:

The above repeating structural unit may be substituted with a halogen atom, an alkyl group or an aryl group.

  In addition, as said alkyl group, a C1-C10 alkyl group is preferable and a methyl group, an ethyl group, or a butyl group is more preferable. As said aryl group, a C6-C20 aryl group is preferable and a phenyl group is more preferable.

Heat resistance, aromatic liquid crystal polyester from the balance of mechanical properties, preferably contains a repeating unit represented by A ₁ expression at least 30 mol%. Examples of preferable combinations of repeating structural units include the following (a) to (f).
(A):
A combination of the repeating structural units (A ₁ ), (B ₂ ) and (C ₃ ).
A combination of the repeating structural units (A ₂ ), (B ₂ ) and (C ₃ ).
A combination of the repeating structural units (A ₁ ), (B ₁ ), (B ₂ ) and (C ₃ ), or
A combination of the repeating structural units (A ₂ ), (B ₁ ), (B ₂ ) and (C ₃ ).
(B): In each of the combination of said (a), by substituting a part or all of _{(C 3)} to _{(C 1)} in combination.
(C): In each of the combination of said (a), by substituting a part or all of _{(C 3)} to _{(C 2)} combined.
(D): In each of the combination of said (a), by substituting a part or all of _{(C 3)} to _{(C 4)} combinations.
(E): In each of the combination of said (a), was replaced with a mixture of _{(C 3)} of some or all the _{(C 4) (C 5)} combinations.
(F): In each of the combination of said (a), by replacing part of _{(A 1)} to _{(A 2)} in combination.

The aromatic liquid crystal polyester used for the aromatic liquid crystal polyester fiber according to the present invention includes a total of structural units composed of p-hydroxybenzoic acid (A ₁ ) and 2-hydroxy-6-naphthoic acid (A ₂ ). It is preferable that it is 65 mol% or more, and it is preferable that the ratio of 2-hydroxy-6-naphthoic acid is 5-45 mol% with respect to the total amount of both units.

  The aromatic liquid crystal polyester used for the aromatic liquid crystal polyester fiber according to the present invention includes, as necessary, polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyester ether ketone, polyarylate. In addition, one or more of other polymers such as fluorine-containing resin may be contained. In addition, one or more of various additives such as inorganic substances such as titanium oxide, kaolin, silica, barium oxide, carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers, and light stabilizers. It may be blended. Components other than the aromatic liquid crystal polyester in the aromatic liquid crystal polyester fiber are preferably 50% by mass or less.

  The nonwoven fabric made of the aromatic liquid crystal polyester fiber according to the present invention, when extruding the aromatic liquid crystal polyester from the nozzle, blows a high-temperature and high-pressure gas stream from a slit provided in the vicinity of the nozzle tip, thereby finely spinning the spinning polymer. It is preferably a melt blown nonwoven fabric produced by being blown off into a fibrous form and collected on a suction collecting net. The melt-blown nonwoven fabric can be made thin and has continuous fibers, so it has the advantage of good formation and high mechanical strength when compared to other nonwoven fabrics with the same basis weight. There is.

In the nonwoven fabric made of the aromatic liquid crystal polyester fiber according to the present invention, the average fiber diameter is 0.3 to 35 μm, preferably 1 to 15 μm. Moreover, 6-30 g / m < ² > is preferable and basic weight has more preferable 6-10 g / m < ² >.

  In the nonwoven fabric comprising the aromatic liquid crystal polyester fiber according to the present invention, the aromatic liquid crystal polyester preferably has a melting point of 290 ° C. or lower. Lamination treatment is performed when laminating the nonwoven fabric and the carrier sheet. In the case of aromatic liquid crystal polyester fibers having a melting point exceeding 290 ° C., not only high temperature and high pressure are required in the lamination treatment, but also the carrier sheet is damaged. Problem arises.

  The aromatic liquid crystal polyester used as the matrix resin according to the present invention is derived from at least one compound selected from the group consisting of p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid from the viewpoint of heat resistance. Selected from the group consisting of 30 to 80 mol% of repeating structural units, 10 to 35 mol% of repeating structural units derived from at least one compound selected from the group consisting of hydroquinone and 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid It is preferable that it consists of 10 to 35 mol% of repeating structural units derived from at least one kind of compound.

  Moreover, the mass average molecular weight of the aromatic liquid crystal polyester is not particularly limited, but is preferably 10,000 to 100,000.

  The method for producing the aromatic liquid crystal polyester used in the present invention is not particularly limited. For example, at least one selected from the group consisting of an aromatic hydroxycarboxylic acid and an aromatic diol is acylated with an excess amount of a fatty acid anhydride. A method of melt polymerization by obtaining an acylated product and subjecting the obtained acylated product to at least one selected from the group consisting of an aromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid by transesterification (polycondensation) may be mentioned. As the acylated product, a fatty acid ester obtained by acylation in advance may be used.

  In the acylation reaction, the addition amount of the fatty acid anhydride is preferably 1.0 to 1.2 times equivalent, more preferably 1.05 to 1.1 times equivalent to the phenolic hydroxyl group. If the amount of fatty acid anhydride added is small, acylated products, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, etc. will sublimate during transesterification (polycondensation), and the reaction system tends to be clogged. The resulting aromatic liquid crystal polyester tends to be remarkably colored.

  The acylation reaction is preferably performed at 130 to 180 ° C. for 5 minutes to 10 hours, more preferably at 140 to 160 ° C. for 10 minutes to 3 hours.

  The fatty acid anhydride used in the acylation reaction is not particularly limited. For example, acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, pivalic anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride , Dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, β- Examples thereof include bromopropionic acid, and two or more of these may be used in combination. From the viewpoint of price and handleability, acetic anhydride, propionic anhydride, butyric anhydride, or isobutyric anhydride is preferably used, and acetic anhydride is more preferably used.

  In the transesterification, the acyl group of the acylated product is preferably 0.8 to 1.2 times the carboxyl group.

  The transesterification is preferably performed while increasing the temperature at 130 to 400 ° C. at a rate of 0.1 to 50 ° C./min, and at 150 to 350 ° C. while increasing the temperature at a rate of 0.3 to 5 ° C./min. It is more preferable.

  When transesterifying a fatty acid ester obtained by acylation with a carboxylic acid, it is preferable to distill out the by-product fatty acid and the unreacted fatty acid anhydride by evaporating or the like in order to move the equilibrium. .

  The acylation reaction and transesterification may be performed in the presence of a catalyst. As the catalyst, those conventionally known as polyester polymerization catalysts can be used, such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, antimony trioxide and the like. And organic compound catalysts such as N, N-dimethylaminopyridine and N-methylimidazole. The catalyst is usually added when the monomers are added, and it is not always necessary to remove the catalyst after acylation. If the catalyst is not removed, transesterification can be carried out as it is.

  Polycondensation by transesterification is usually performed by melt polymerization, but melt polymerization and solid phase polymerization may be used in combination. The solid phase polymerization is preferably carried out by a known solid phase polymerization method after the polymer is extracted from the melt polymerization step and then pulverized into powder or flakes. Specifically, for example, a method of heat treatment in a solid state at 20 to 350 ° C. for 1 to 30 hours under an inert atmosphere such as nitrogen can be used. Solid phase polymerization may be carried out while stirring or in a state of standing without stirring. In addition, by providing an appropriate stirring mechanism, the melt polymerization tank and the solid phase polymerization tank can be made the same reaction tank. After the solid state polymerization, the obtained aromatic liquid crystal polyester may be pelletized and molded by a known method. The aromatic liquid crystal polyester can be produced using, for example, a batch apparatus, a continuous apparatus or the like.

［式中、Ａはハロゲン原子またはトリハロゲン化メチル基を表わし、ｉはＡの個数であって１〜５の整数を表わす。ｉが２以上の場合、複数あるＡは互いに同一でも異なっていてもよいが、同一であることが好ましい。ｉは好ましくは１〜３であり、より好ましくは１または２である。ｉが１のときのＡの置換位置は４位であることが好ましく、ｉが２以上のとき少なくとも一つのＡの置換位置は４位であることが好ましい（但し、水酸基の置換位置を１位とする）。］ In the present invention, the matrix resin comprising the aromatic liquid crystal polyester is used in a state dissolved in a suitable solvent. The solvent used for obtaining the aromatic liquid crystal polyester solution is a solvent containing 30% by mass or more of the halogen-substituted phenol compound represented by the following general formula (I), and dissolves the aromatic liquid crystal polyester at room temperature or under heating. . The solvent is preferably a solvent containing 60% by mass or more of the phenol compound, and more preferably 100% by mass of the phenol compound is used as the solvent because it is not necessary to mix with other components. .

[Wherein, A represents a halogen atom or a trihalogenated methyl group, and i represents the number of A and an integer of 1 to 5.] When i is 2 or more, a plurality of A may be the same or different from each other, but are preferably the same. i is preferably 1 to 3, more preferably 1 or 2. The substitution position of A when i is 1 is preferably the 4-position, and when i is 2 or more, the substitution position of at least one A is preferably the 4-position (provided that the hydroxyl substitution position is the 1-position). And). ]

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. A fluorine atom or a chlorine atom is preferable, and a chlorine atom is particularly preferable. Examples of the halogen-substituted phenol compound represented by the general formula (I) in which the halogen atom is a fluorine atom include pentafluorophenol and tetrafluorophenol. Examples of the halogen-substituted phenol compound represented by the general formula (I) in which the halogen atom is a chlorine atom include o-chlorophenol and p-chlorophenol, and p-chlorophenol is preferable from the viewpoint of solubility. Examples of the halogen of the trihalogenated methyl group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the halogen-substituted phenol compound represented by the general formula (I) in which the halogen of the trihalogenated methyl group is a fluorine atom include 3,5-bistrifluoromethylphenol.

  As the halogen-substituted phenol compound represented by the general formula (I), chlorine-substituted phenol compounds such as o-chlorophenol and p-chlorophenol are preferably used from the viewpoint of price and availability. -Chlorophenol is more preferably used.

  The solvent may contain other components in addition to the halogen-substituted phenolic compound as long as the aromatic liquid crystalline polyester is not precipitated during storage of the solution or casting described later. Other components that may be contained are not particularly limited, and examples thereof include chlorine compounds such as chloroform, methylene chloride, and tetrachloroethane.

  The aromatic liquid crystal polyester solution used in the present invention contains 0.5 to 100 parts by mass of the aromatic liquid crystal polyester with respect to 100 parts by mass of the solvent, and 1 to 50 from the viewpoint of workability or economy. The content is preferably 3 parts by mass, and more preferably 3 to 10 parts by mass. When the amount of the aromatic liquid crystal polyester is small, the production efficiency tends to decrease, and when the amount is large, the dissolution tends to be difficult.

  The aromatic liquid crystal polyester solution used in the present invention can be obtained by dissolving the aromatic liquid crystal polyester in the above solvent, and the solution is included in the solution by filtration with a filter or the like, if necessary. It is preferable to remove fine foreign matters.

  In addition, the aromatic liquid crystal polyester solution includes an inorganic filler such as silica, aluminum hydroxide, and calcium carbonate, an organic filler such as a cured epoxy resin, a crosslinked benzoguanamine resin, and a crosslinked acrylic polymer, as long as the object of the present invention is not impaired. Thermosetting such as polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenyl ether and its modified products, polyetherimide, thermosetting resin such as phenol resin, epoxy resin, polyimide resin, cyanate resin Various additives such as a resin, a silane coupling agent, an antioxidant, and an ultraviolet absorber may be added alone or in combination.

  As the carrier sheet according to the present invention, it is preferable to use a heat-resistant synthetic resin film such as polyethylene terephthalate, polyphenylene sulfide, polyether imide, polyallyl ether nitrile. The carrier sheet made of the heat-resistant synthetic resin film is peeled off when using the resin-impregnated base material for circuit boards of the present invention. Moreover, when metal foil is used as a carrier sheet, it can be used as it is as a metal foil for forming a circuit board. As the metal, copper, iron, aluminum, and the like can be used, and it is particularly preferable to use copper.

  When a metal foil is used as a carrier sheet, if a nonwoven fabric or woven fabric made of a resin having a high water absorption rate is used, metal migration may occur along the fiber from the contact portion between the metal foil and the nonwoven fabric. In the resin-impregnated base material of the present invention, both the nonwoven fabric and the matrix resin used for the insulating base material are aromatic liquid crystal polyesters and have a characteristic of low hygroscopicity, so that metal migration hardly occurs.

Although the thickness of a carrier sheet is not specifically limited, It is preferable that it is 20-200 micrometers. As a method of providing the nonwoven fabric on the carrier sheet, there is a method in which the nonwoven fabric is directly provided on the carrier sheet by the melt blow method and then thermocompression bonded, or the nonwoven fabric obtained by the melt blow method is thermocompression bonded on the carrier sheet. Can be mentioned. As thermocompression bonding conditions, a pressure of 50 to 220 kgf / cm ² is preferable at a temperature from 100 ° C. to the melting point of the aromatic liquid crystal polyester fiber.

  A conventionally known method can be used for the impregnation of the matrix resin. For example, an impregnation method, a coating method, a transfer method, or the like can be used, but a method in which a non-woven fabric provided on a carrier sheet is impregnated with a varnish prepared by dissolving a matrix resin in a solvent and dried is preferable. Moreover, it is good to dry in a non-contact state with a vertical dryer. In the present invention, since the mechanical strength is improved by providing the nonwoven fabric on the carrier sheet, problems such as tearing and generation of wrinkles do not occur even when dried with a vertical dryer.

  In the resin-impregnated base material of the present invention, an aromatic liquid crystal polyester solution is obtained by impregnating a nonwoven fabric composed of aromatic liquid crystal polyester fibers provided on a carrier sheet and removing the solvent. As for the thickness of the part except a carrier sheet, 30-200 micrometers is preferable.

Non - woven fabric made of aromatic liquid crystal polyester fiber Aromatic liquid crystal polyester made of 2-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid (manufactured by Polyplastics; Vectra A950) is sufficiently dried with a low dew point air dryer. The mixture was extruded by a twin screw extruder and supplied to a melt blown nonwoven fabric manufacturing apparatus having a nozzle having a width of 1 m and a hole number of 1000. Single hole discharge rate 0.3 g / min, resin temperature 310 ° C., hot air drying temperature 310 ° C., 20 Nm ³ / min, basis weight 8.7 g / m ² , average fiber diameter 7.8 μm, thickness 49 μm, tensile strength (MD ) 3N / 15 mm non-woven fabric A was produced.

The nonwoven fabric A is laminated on a polyallyl ether nitrile resin film having a laminated film thickness of 60 μm with a carrier sheet, and laminated at a temperature of 310 ° C., a pressure of 100 kgf / cm ² , and a speed of 15 cm / min. Were laminated.

Preparation of aromatic liquid crystalline polyester In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer and reflux condenser, 128 g (0.68 mol) of 2-hydroxy-6-naphthoic acid, 4,4 ′ -63.3 g (0.34 mol) of dihydroxybiphenyl, 56.5 g (0.34 mol) of isophthalic acid and 152.7 g (1.50 mol) of acetic anhydride were charged. After sufficiently replacing the inside of the reactor with nitrogen gas, the temperature was raised to 150 ° C. over 15 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 3 hours. Thereafter, while distilling off distilling by-product acetic acid and unreacted acetic anhydride, the temperature was raised to 320 ° C. over 170 minutes. The time point at which an increase in torque was observed was regarded as completion of the reaction, and the contents were taken out. The obtained solid content was cooled to room temperature, pulverized with a coarse pulverizer, held at 250 ° C. for 3 hours in a nitrogen atmosphere, and the polymerization reaction proceeded in a solid phase. In the obtained powder, a schlieren pattern peculiar to the liquid crystal phase was observed at 350 ° C. with a polarizing microscope.

  0.4 g of the obtained aromatic liquid crystal polyester powder was compression molded using a flow tester CFT-500 manufactured by Shimadzu Corporation under a 100 kg load at 250 ° C. for 10 minutes, and a disk-shaped test piece having a thickness of 3 mm. Got. Using this test piece, the water absorption rate at 85 ° C./85% RH 168 hours was measured with a constant temperature and humidity machine ADVANTEC AGX type manufactured by Toyo Seisakusho. As a result, it was confirmed that the water absorption rate was 0.1% or less. Moreover, when the dielectric loss tangent was measured using the HP impedance analyzer, it was 0.0010 (1 GHz).

Preparation of Aromatic Liquid Crystalline Polyester Solution Aromatic liquid crystal polyester powder 0.5 g obtained by the above process was added to 9.5 g of p-chlorophenol and heated to 120 ° C. Obtained.

The aromatic liquid crystal polyester solution B is applied to the nonwoven fabric made of aromatic liquid crystal polyester fiber provided on the impregnated carrier sheet by a kiss coating method, and the solvent is evaporated using a vertical hot air dryer (130 ° C.). The nonwoven fabric was impregnated with an aromatic liquid crystal polyester as a matrix resin. It was 0.0016 (1 GHz) when the dielectric loss tangent was measured about the resin impregnation base material after carrier sheet peeling using the HP impedance analyzer.

  Thereafter, the resin-impregnated base material was heat-treated at 320 ° C. for 1 hour using a hot air dryer. The amount of the matrix resin attached was 67% by mass. When the surface state was observed by immersing in a solder bath having a solder temperature of 280 ° C. for 1 minute, neither deformation nor swelling was observed. Moreover, when the dielectric loss tangent was measured using the HP impedance analyzer, it was 0.0005 (1 GHz).

A copper foil having a thickness of 18 μm was laminated on both surfaces of the five resin-impregnated base materials after treatment at 320 ° C. for 1 hour from a copper migration resistant hot air dryer. This was placed between stainless steel mirror plates and heated under pressure at 280 ° C. for 20 minutes and 5 Mpa, followed by pressure heating at 340 ° C. for 20 minutes at 5 Mpa to perform lamination molding. The thickness of the obtained copper clad laminate was 149 μm. In the copper clad laminate, 0.2 mm through holes were opened at 1 mm intervals, electroless plating treatment and copper plating treatment were performed, and 25 μm plated copper was provided on the entire surface of the copper clad laminate. When the insulation resistance was measured in an environment of a temperature of 85 ° C., a relative humidity of 85%, and a direct current of 100 V, an insulation resistance of 10 ¹⁰ Ω or more could be maintained for 1000 hours or more.

The nonwoven fabric A obtained in Example 1 is laminated on a copper foil for circuit having a laminated film thickness of 18 μm with a carrier sheet , laminated at a temperature of 310 ° C., a pressure of 100 kgf / cm ² , and a speed of 15 cm / min. A sheet and a nonwoven fabric were laminated.

The aromatic liquid crystal polyester solution B obtained in Example 1 was applied to the nonwoven fabric made of aromatic liquid crystal polyester fibers provided on the impregnated carrier sheet by a kiss coating method, and a vertical hot air dryer (130 ° C.) was used. Then, the solvent was evaporated, and the nonwoven fabric was impregnated with the aromatic liquid crystal polyester as the matrix resin. It was 0.0016 (1 GHz) when the dielectric loss tangent was measured about the resin impregnation base material after carrier sheet peeling using the HP impedance analyzer.

  Thereafter, the resin-impregnated base material was heat-treated at 320 ° C. for 1 hour using a hot air dryer. The matrix resin adhesion amount was 71 mass%. When the surface state was observed by immersing in a solder bath having a solder temperature of 280 ° C. for 1 minute, neither deformation nor swelling was observed. Moreover, when the dielectric loss tangent was measured using the HP impedance analyzer, it was 0.0005 (1 GHz).

  The resin-impregnated base material obtained in Example 2 can be used as it is, with the copper foil as a carrier sheet used as a circuit board forming copper foil.

Copper migration resistance Resin-impregnated base material obtained in Example 1 (320 ° C. by hot air dryer, treated for 1 hour on the opposite side to the copper foil which is the carrier sheet of the resin-impregnated base material obtained in Example 2 ), And a copper foil having a thickness of 18 μm was laminated thereon. This was placed between stainless steel mirror plates and heated under pressure at 280 ° C. for 20 minutes and 5 Mpa, followed by pressure heating at 340 ° C. for 20 minutes at 5 Mpa to perform lamination molding. The thickness of the obtained copper clad laminate was 153 μm. In the copper clad laminate, 0.2 mm through holes were opened at 1 mm intervals, electroless plating treatment and copper plating treatment were performed, and 25 μm plated copper was provided on the entire surface of the copper clad laminate. When the insulation resistance was measured in an environment of a temperature of 85 ° C., a relative humidity of 85%, and a direct current of 100 V, an insulation resistance of 10 ¹⁰ Ω or more could be maintained for 1000 hours or more.

Lamination of non-woven fabric made of aromatic liquid crystal polyester fiber and carrier sheet Aromatic liquid crystal polyester made of 2-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid (manufactured by Polyplastics; Vectra A950) is dried at low dew point. It was sufficiently dried by a machine, extruded by a twin screw extruder, and supplied to a melt blown nonwoven fabric production apparatus having a nozzle having a width of 1 m and a hole number of 1000. A mesh-shaped copper foil (carrier sheet) having a thickness of 18 μm is poured on the nonwoven fabric collecting surface (wire net) of the melt blown nonwoven fabric manufacturing apparatus, the single hole discharge rate is 0.3 g / min, the resin temperature is 310 ° C., the hot air drying temperature is 310 ° C., Nonwoven fabric C having a basis weight of 6.9 g / m ² , an average fiber diameter of 5.8 μm, and a thickness of 40 μm is produced on a carrier sheet at 20 Nm ³ / min, and then a temperature of 300 ° C., a pressure of 90 kgf / cm ² , and a speed of 15 cm / Laminating treatment was performed in minutes, and the carrier sheet and the nonwoven fabric C were laminated.

The aromatic liquid crystal polyester solution B is applied to the nonwoven fabric made of aromatic liquid crystal polyester fibers provided on the impregnation treatment carrier sheet by an impregnation method, and the solvent is evaporated using a vertical hot air dryer (130 ° C.). The nonwoven fabric was impregnated with an aromatic liquid crystal polyester as a matrix resin. It was 0.0016 (1 GHz) when the dielectric loss tangent was measured about the resin impregnation base material after carrier sheet peeling using the HP impedance analyzer.

  Thereafter, the resin-impregnated base material was heat-treated at 320 ° C. for 1 hour using a hot air dryer. The matrix resin adhesion amount was 72 mass%. When the surface state was observed by immersing in a solder bath having a solder temperature of 280 ° C. for 1 minute, neither deformation nor swelling was observed. Moreover, when the dielectric loss tangent was measured using the HP impedance analyzer, it was 0.0006 (1 GHz).

A copper foil having a thickness of 18 μm was laminated on both surfaces of the five resin-impregnated base materials after treatment at 320 ° C. for 1 hour from a copper migration resistant hot air dryer. This was placed between stainless steel mirror plates and heated under pressure at 280 ° C. for 20 minutes and 5 Mpa, followed by pressure heating at 340 ° C. for 20 minutes at 5 Mpa to perform lamination molding. The thickness of the obtained copper clad laminate was 165 μm. In the copper clad laminate, 0.2 mm through holes were opened at 1 mm intervals, electroless plating treatment and copper plating treatment were performed, and 25 μm plated copper was provided on the entire surface of the copper clad laminate. When the insulation resistance was measured in an environment of a temperature of 85 ° C., a relative humidity of 85%, and a direct current of 100 V, an insulation resistance of 10 ¹⁰ Ω or more could be maintained for 1000 hours or more.

Non - woven fabric made of aromatic liquid crystal polyester fiber Aromatic liquid crystal polyester made of 2-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid (manufactured by Polyplastics; Vectra A950) is sufficiently dried with a low dew point air dryer. The mixture was extruded by a twin screw extruder and supplied to a melt blown nonwoven fabric manufacturing apparatus having a nozzle having a width of 1 m and a hole number of 1000. Single hole discharge rate 0.3 g / min, resin temperature 310 ° C., hot air drying temperature 310 ° C., 20 Nm ³ / min, basis weight 13.6 g / m ² , average fiber diameter 7.8 μm, thickness 58 μm, tensile strength (MD ) A nonwoven fabric D of 10 N / 15 mm was produced.

The non-woven fabric D is laminated on a polyallyl ether nitrile resin film having a laminated film thickness of 60 μm with a carrier sheet , laminated at a temperature of 310 ° C., a pressure of 100 kgf / cm ² , and a speed of 15 cm / min. Were laminated.

An aromatic liquid crystal polyester solution B is applied to a non-woven fabric made of aromatic liquid crystal polyester fibers provided on an impregnation treatment carrier sheet by a kiss coating method, and the solvent is evaporated using a vertical hot air dryer (130 ° C.). The nonwoven fabric was impregnated with an aromatic liquid crystal polyester as a matrix resin. It was 0.0026 (1 GHz) when the dielectric loss tangent was measured about the resin impregnation base material after carrier sheet peeling using the HP impedance analyzer.

  Thereafter, the resin-impregnated base material was heat-treated at 320 ° C. for 1 hour using a hot air dryer. The amount of the matrix resin attached was 67% by mass. When the surface state was observed by immersing in a solder bath having a solder temperature of 280 ° C. for 1 minute, neither deformation nor swelling was observed. The dielectric loss tangent was measured using an HP impedance analyzer and found to be 0.0009 (1 GHz).

A copper foil having a thickness of 18 μm was laminated on both surfaces of the five resin-impregnated base materials after treatment at 320 ° C. for 1 hour from a copper migration resistant hot air dryer. This was placed between stainless steel mirror plates and heated under pressure at 280 ° C. for 20 minutes and 5 Mpa, followed by pressure heating at 340 ° C. for 20 minutes at 5 Mpa to perform lamination molding. The thickness of the obtained copper clad laminate was 193 μm. In the copper clad laminate, 0.2 mm through holes were opened at 1 mm intervals, electroless plating treatment and copper plating treatment were performed, and 25 μm plated copper was provided on the entire surface of the copper clad laminate. When the insulation resistance was measured in an environment of a temperature of 85 ° C., a relative humidity of 85%, and a direct current of 100 V, an insulation resistance of 10 ¹⁰ Ω or more could be maintained for 1000 hours or more.

(Comparative Example 1)
A sheet (FR-4, manufactured by Hitachi Chemical Co., Ltd., thickness 800 μm) impregnated with glass cloth with an epoxy resin was immersed in a solder bath with a solder temperature of 280 ° C. for 1 minute, and the surface state was observed. A part of the epoxy resin impregnated sheet was thermally deteriorated, and the substrate itself was also deformed. Moreover, when the dielectric loss tangent was measured using the HP impedance analyzer, it was 0.012 (1 GHz).

(Comparative Example 2)
A commercially available glass cloth (10 g / m ² ) is laminated on a polyallyl ether nitrile resin film having a laminated film thickness of 60 μm with a carrier sheet and laminated at a temperature of 310 ° C., a pressure of 100 kgf / cm ² , and a speed of 15 cm / min. However, the carrier sheet and the glass cloth could not be bonded. Moreover, it was not able to adhere | attach, when using a 18-micrometer-thick copper foil instead of a polyallyl ether nitrile resin film.

Impregnation treatment Aromatic liquid crystal polyester solution B was applied to a commercially available glass cloth (10 g / m ² ) by a kiss coating method, the solvent was evaporated using a vertical hot air dryer (130 ° C.), and a matrix was formed on the glass cloth. Although the resin was impregnated with aromatic liquid crystalline polyester, the sheet was cut during the coating process.

A commercially available glass cloth (10 g / m ² ) is immersed in a pad containing the aromatic liquid crystal polyester solution B, and the solvent is evaporated using a hot air dryer (130 ° C.). Some aromatic polyester was impregnated. It was 0.0041 (1 GHz) when the dielectric loss tangent was measured about the resin impregnation base material using the HP impedance analyzer.

  Thereafter, the resin-impregnated base material was heat-treated at 320 ° C. for 1 hour using a hot air dryer. The matrix resin adhesion amount was 62 mass%. When the surface state was observed by immersing in a solder bath having a solder temperature of 280 ° C. for 1 minute, no deformation or swelling was observed. Moreover, when the dielectric loss tangent was measured using the HP impedance analyzer, it was 0.0037 (1 GHz).

A copper foil having a thickness of 18 μm was laminated on both surfaces of the five resin-impregnated base materials after treatment at 320 ° C. for 1 hour from a copper migration resistant hot air dryer. This was placed between stainless steel mirror plates and heated under pressure at 280 ° C. for 20 minutes and 5 Mpa, followed by pressure heating at 340 ° C. for 20 minutes at 5 Mpa to perform lamination molding. The thickness of the obtained copper clad laminate was 195 μm. In the copper clad laminate, 0.2 mm through holes were opened at 1 mm intervals, electroless plating treatment and copper plating treatment were performed, and 25 μm plated copper was provided on the entire surface of the copper clad laminate. When the insulation resistance was measured in an environment of a temperature of 85 ° C., a relative humidity of 85%, and a direct current of 100 V, an insulation resistance of 10 ¹⁰ Ω or more could be maintained only for 700 hours.

(Comparative Example 3)
The non-woven fabric A obtained in Example 1 was coated with the aromatic liquid crystal polyester solution B obtained in Example 1 by a kiss coating method, and the solvent was evaporated using a vertical hot air dryer (130 ° C.). When the nonwoven fabric was impregnated with an aromatic liquid crystal polyester as a matrix resin, wrinkles were generated and the sheet was broken in the middle.

  As described above, in the example, in the resin-impregnated base material obtained by impregnating the matrix resin into the ultra-thin nonwoven fabric corresponding to the high density, the nonwoven fabric is provided on the carrier sheet to supplement the mechanical strength of the nonwoven fabric. High production stability. Further, by using a nonwoven fabric made of aromatic liquid crystal polyester fiber, the carrier sheet and the nonwoven fabric can be pressure-bonded at a temperature equal to or higher than the melting point of the fiber.

  In addition, the resin-impregnated base material obtained in the examples of the present invention has a very low dielectric loss because both the nonwoven fabric and the matrix resin used for the insulating base material are low-hygroscopic aromatic liquid crystal polyesters. Low. When such a resin-impregnated base material is used, there is an advantage that metal migration caused by moisture hardly occurs.

  The present invention can be suitably used for a printed wiring board such as a cellular phone, a semiconductor package, a multilayer printed board for a motherboard, a flexible printed wiring board, a rigid printed wiring board and the like.

Claims (4)

A method for producing a resin-impregnated base material for circuit boards, comprising impregnating and drying a matrix resin comprising an aromatic liquid crystal polyester into a nonwoven fabric comprising aromatic liquid crystal polyester fibers provided on a carrier sheet by thermocompression bonding .   The method for producing a resin-impregnated base material for a circuit board according to claim 1, wherein the carrier sheet is a metal foil for a circuit board. The process according to claim 1 or 2 for the circuit board resin-impregnated substrate according basis weight of the nonwoven fabric made of liquid-crystalline polyester fiber is 6-10 g / m ^2.   The method for producing a resin-impregnated base material for a circuit board according to any one of claims 1 to 3, wherein the aromatic liquid crystal polyester fiber has a melting point of 290 ° C or lower.