JP4954446B2 - Fiber reinforced substrate - Google Patents

Description

  The present invention relates to a fiber reinforced substrate.

In recent years, in the field of electronic / electronic equipment, development of insulating resin base materials having excellent characteristics such as heat resistance, low moisture absorption, dimensional stability, and high frequency characteristics has been desired.
As an insulating resin base material, a fiber reinforced base material in which a sheet-like fiber reinforcing material such as glass cloth is impregnated with an epoxy resin has been conventionally known (see Patent Document 1).
However, due to the increase in soldering temperature (260 ° C or higher) accompanying the recent lead-free soldering, the fiber reinforced base material in which the glass cloth is impregnated with epoxy resin has insufficient heat resistance, and the high temperature of 260 ° C or higher When soldering is performed, there is a problem that the epoxy resin is thermally deteriorated and the fiber-reinforced base material is deformed (see Patent Document 1).

JP-A-5-8224

  An object of the present invention is to provide a fiber-reinforced substrate with less deformation when soldering at a high temperature of 260 ° C. or higher.

（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の整数を表わし、ｉが２以上の場合に複数あるＡは互いに同一でも異なっていてもよい。） That is, the present invention is obtained by impregnating a sheet-like fiber reinforcing material with an aromatic liquid crystal polyester solution containing 100 parts by weight of the following solvent and 0.5 to 100 parts by weight of an aromatic liquid crystal polyester and removing the solvent. It is applied to the fiber reinforced substrate.
Solvent: A solvent containing 30% by weight or more of the halogen-substituted phenol compound represented by the following general formula (I).

(In the formula, A represents a halogen atom or a trihalogenated methyl group, i represents the number of A and represents an integer of 1 to 5, and when i is 2 or more, a plurality of A's are the same or different from each other. May be good.)

  According to the present invention, it is possible to provide a fiber-reinforced substrate with less deformation when soldering at a high temperature of 260 ° C. or higher.

Hereinafter, the present invention will be described in detail.
The fiber reinforced substrate of the present invention is obtained by impregnating a sheet-like fiber reinforcement with an aromatic liquid crystal polyester solution and removing the solvent.
The aromatic liquid crystal polyester used in the present invention is a polyester called a thermotropic liquid crystal polymer, and forms a melt exhibiting optical anisotropy at a temperature of 450 ° C. or lower.

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) Crystalline polyesters such as polyethylene terephthalate are reacted with an aromatic hydroxycarboxylic acid.
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, and the like, as long as they do not inhibit ester formation. It may be substituted with an aryl group such as a group.

  Examples of the repeating structural unit of the aromatic liquid crystal polyester include the following, but are 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.

  As the aromatic liquid crystal polyester, from the viewpoint of heat resistance, 30 to 80 mol% of repeating structural units derived from at least one compound selected from the group consisting of p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid, 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, derived from at least one compound selected from the group consisting of terephthalic acid and isophthalic acid It preferably consists of 10 to 35 mol% of repeating structural units.

  Moreover, the weight 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（水酸基の置換位置を１位とする）。 The solvent used for obtaining the aromatic liquid crystal polyester solution in the present invention is a solvent containing 30% by weight or more of the halogen-substituted phenol compound represented by the following general formula (I), and the aromatic liquid crystal polyester is heated at room temperature or under heating. Dissolve. The solvent is preferably a solvent containing 60% by weight or more of the phenol compound, and more preferably 100% by weight of the phenol compound is used as the solvent because it is not necessary to mix with other components. .

In the formula, A represents a halogen atom or a trihalogenated methyl group, 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 (the hydroxyl substitution position is the 1-position). ).

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 weight of the aromatic liquid crystal polyester with respect to 100 parts by weight of the solvent, and 1 to 50 weights from the viewpoint of workability or economy. It is preferable to contain 3 parts by weight, and more preferably 3 to 10 parts by weight. 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 resins such as polyamide, polyester, polyphenylene sulfide, polyetherketone, polycarbonate, polyethersulfone, polyphenylether and modified products thereof, polyetherimide, thermoplastic resin, phenolic 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.

Examples of the sheet-like fiber reinforcement used in the present invention include woven fabrics, knitted fabrics, and nonwoven fabrics made of reinforcing fibers.
Examples of the reinforcing fibers include glass fibers, carbon fibers, ceramic fibers, polyester fibers, and aramid fibers, and glass fibers are preferably used from the viewpoint of cost and heat resistance.
Although glass fiber is not specifically limited, For example, alkali-containing glass fiber, alkali-free glass fiber, low dielectric glass, etc. can be used.
The reinforcing fiber may be surface-treated with a coupling treatment agent such as an aminosilane coupling agent, an epoxysilane coupling agent, or a titanate coupling agent.
The thickness of the sheet-like fiber reinforcement is usually about 5 to 500 μm.

  The fiber-reinforced substrate of the present invention is obtained by impregnating the aromatic liquid crystal polyester solution into the sheet-like fiber reinforcing material and removing the solvent, and the thickness is usually about 10 to 1000 μm.

The method for removing the solvent is not particularly limited, but it is preferably performed by evaporation of the solvent. Examples of the method for evaporating the solvent include methods such as heating, decompression, and ventilation.
You may heat-process the obtained fiber reinforced board | substrate as needed.

Although the obtained fiber reinforced board | substrate may be used independently, you may laminate | stack and use another sheet | seat, a film | membrane, etc.
The lamination method is not particularly limited, and examples thereof include a method in which another sheet or film (film) is adhered to the obtained fiber reinforced substrate with an adhesive, and a method in which heat fusion is performed by hot pressing.
Here, as another sheet | seat and film (film | membrane) laminated | stacked, a metal film, a resin film, etc. are mentioned, for example.

The fiber reinforced substrate of the present invention preferably has a conductive layer on one side or both sides of the fiber reinforced substrate. As a method for forming a conductive layer, a method of laminating a metal film as described above, a method of forming a conductive layer by coating metal powder on a fiber reinforced substrate, and the like are common. The fiber reinforced substrate of the present invention is more preferably one in which a metal film is laminated on at least one surface of the fiber reinforced substrate.
Examples of the metal of the metal film or metal powder include copper, aluminum, silver, etc., but copper is preferably used from the viewpoint of conductivity and cost.
As a method for laminating a metal film, a method of bonding a metal film and a glass fiber reinforced substrate using an adhesive, or a method of heat-sealing by hot pressing is generally used. Moreover, as a coating method of the metal powder, a plating method, a screen printing method, a sputtering method, or the like can be used.
A fiber reinforced substrate having a conductive layer on one side or both sides can be used as a printed wiring substrate.
A cover film may be further laminated on the obtained printed wiring substrate for the purpose of protecting the conductive layer.

  The fiber reinforced substrate of the present invention, in addition to the feature of high heat resistance, taking advantage of excellent characteristics such as low hygroscopicity derived from aromatic liquid crystal polyester, multilayer printed circuit boards for mobile phones, semiconductor packages, motherboards, etc., It is suitably used for printed wiring boards such as flexible printed wiring boards and rigid printed wiring boards.

  EXAMPLES Hereinafter, although this invention is demonstrated using an Example, it cannot be overemphasized that this invention is not what is limited by an Example.

Example 1
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser, 141 g (1.02 mol) of p-hydroxybenzoic acid, 63.3 g of 4,4′-dihydroxybiphenyl (0. 34 mol), 56.5 g (0.34 mol) of isophthalic acid, and 191 g (1.87 mol) of acetic anhydride. 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 layer. In the obtained powder, a schlieren pattern peculiar to the liquid crystal phase was observed at 350 ° C. with a deflection 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 by a constant temperature and humidity machine ADVANTEC AGX type manufactured by Toyo Seisakusho, and it was confirmed that the water absorption rate was 0.1% or less. .

  As a result of adding 0.5 g of the aromatic liquid crystal polyester powder obtained in the above step to 9.5 g of p-chlorophenol and heating to 120 ° C., a completely dissolved solution was obtained. This solution was impregnated into a glass cloth (⇒Asahi Fiber Glass MS100 thickness 110 μm), which is a sheet-like fiber reinforcement, and heated on a hot plate at a set temperature of 100 ° C. for 1 hour to evaporate the solvent. Thereafter, heat treatment was performed at 300 ° C. for 1 hour using a hot air dryer to obtain an aromatic liquid crystal polyester resin-impregnated sheet having a thickness of 100 μm. The obtained aromatic liquid crystal polyester resin-impregnated sheet was used alone as a fiber reinforced substrate, and immersed in a solder bath having a solder temperature of 280 ° C. for 1 minute, and the surface state was observed. The fiber reinforced substrate was not deformed or swollen.

Comparative Example 1
A glass cloth impregnated with an epoxy resin (FR-4, manufactured by Hitachi Chemical Co., Ltd.) was immersed in a solder bath having a solder temperature of 280 ° C. for 1 minute, and the surface state was observed. A part of FR-4 was thermally deteriorated, and the substrate itself was also deformed.

Claims (3)

A method for producing a fiber-reinforced substrate, comprising impregnating a glass cloth with an aromatic liquid crystal polyester solution containing 100 parts by weight of the following solvent and 0.5 to 100 parts by weight of an aromatic liquid crystal polyester, and removing the solvent.
Solvent: A solvent containing 30% by weight or more of the halogen-substituted phenol compound represented by the following general formula (I).

(In the formula, A represents a halogen atom or a trihalogenated methyl group, i represents the number of A and represents an integer of 1 to 5, and when i is 2 or more, a plurality of A's are the same or different from each other. May be good.)   A method for producing a fiber reinforced substrate having a conductive layer, wherein a fiber reinforced substrate is obtained by the production method according to claim 1 and a conductive layer is formed on at least one surface thereof.   The manufacturing method according to claim 2, wherein the fiber reinforced substrate having a conductive layer is for a printed wiring board.