JP2003342382A - Resin impregnated fiber sheet and circuit substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin impregnated fiber sheet which is suitable as an insulation base material having excellent processability such as high-frequency properties, low hygroscopicity, flame retardance, heat resistance, thermal dimensional stability, through-hole processability by a laser and the like as a circuit substrate. <P>SOLUTION: The resin impregnated fiber sheet is obtained by impregnating a fiber sheet composed of polyphenylene sulfide fibers having a coefficient of thermal expansion at 30-100°C of ≤10 ppm/°C with a resin composition. The circuit substrate uses the fiber sheet. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fiber sheet composed of highly oriented polyphenylene sulfide fiber,
Regarding a resin-impregnated fiber sheet impregnated with a resin composition,
The present invention relates to a circuit board which is excellent in thermal dimensional stability and suitability for laser processing.

[0002]

2. Description of the Related Art In the fields of electric and electronic parts, various characteristics such as solder heat resistance, high dimensional stability against heat and humidity, low water absorption and high frequency characteristics are highly dimensional from the viewpoint of miniaturization and high functionality of equipment. The demand for balanced insulating base materials is increasing.

Conventionally, as a circuit board used as a component of electric / electronic equipment, a base material (hereinafter abbreviated as a glass epoxy base material) in which glass cloth is impregnated with an epoxy resin, a polyimide film, an aramid fiber and an epoxy resin are used. For example, a base material impregnated with is used. Furthermore, as a circuit board, polyphenylene sulfide (hereinafter referred to as PP
S) has been proposed as a base material. Specifically, as a circuit board using PPS as a base material, a fiber sheet (JP-A-5-310957) in which a fibrous material is impregnated with PPS resin is known.

[0004]

However, each of these conventional base materials has the following problems. The glass epoxy base material is inferior in high frequency characteristics and has a problem in hygroscopicity. Therefore, there is a problem that the dielectric characteristics are further deteriorated when the frequency is increased. Further, although the polyimide film is excellent in heat resistance, it is inferior in high frequency characteristics and moisture absorption dimensional stability. Also, the base material in which the aramid fiber is impregnated with the epoxy resin has a problem in the moisture absorption property, and therefore, there is a problem that the dielectric property is further deteriorated when the wave number becomes high. There is a problem that the surface (inner wall of the hole, cut surface, etc.) becomes rough due to carbonization and decomposition.

In the case of an unstretched sheet, the PPS film alone satisfies the characteristics such as low hygroscopicity, flame retardancy and high frequency characteristics, but is not sufficiently heat resistant as compared with the biaxially oriented film. Also, since the coefficient of thermal expansion is large, warpage occurs due to the difference with the coefficient of thermal expansion of the laminated copper foil. When crystallization is promoted by heat treatment, heat resistance is improved but the coefficient of thermal expansion does not change.

The biaxially oriented PPS film has a low thermal expansion coefficient due to the stretched orientation, but is not sufficient, and when heat-bonded to a copper foil, the orientation is relaxed and the thermal expansion coefficient increases. I have a problem.

Further, in the case of a sheet-like material obtained by impregnating a fibrous material such as glass cloth with PPS resin, it is excellent in heat resistance, thermal dimensional stability, hygroscopicity, flame retardancy and high frequency characteristics.
There was a problem with the workability of the circuit board, such as cracks when heat such as bending is applied, poor heat-sealing properties, laser drilling is difficult due to the presence of glass cloth, and through-hole processing is difficult. .

An object of the present invention is to solve the above-mentioned problems, that is, by utilizing the excellent high frequency characteristics, low hygroscopicity and flame retardancy of PPS, a circuit excellent in thermal dimensional stability and processability by laser. To provide a substrate.

[0009]

In order to solve the above problems, the resin-impregnated fiber sheet of the present invention mainly has the following constitution. That is, the coefficient of thermal expansion from 30 ° C to 100 ° C is 1
A resin-impregnated fiber sheet, characterized in that a fiber sheet made of polyphenylene sulfide fiber of 0 ppm / ° C. or less is impregnated with a thermosetting resin.

The circuit board of the present invention mainly has the following structure. That is, the circuit board is characterized in that an electric circuit made of a metal layer is formed on at least one surface of the resin-impregnated fiber sheet.

In the resin-impregnated fiber sheet of the present invention,
The thermal expansion coefficient of the polyphenylene sulfide fiber from 30 ° C. to 200 ° C. is 20 ppm / ° C. or less, and the thermosetting resin is an epoxy resin, an acrylic resin, a melamine resin, a phenol resin, a vinyl ester resin, a polyimide resin, or these. It is a preferred embodiment that each is one or more selected from the group consisting of any mixture of two or more.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

In the present invention, the polyphenylene sulfide is preferably a resin containing a PPS component in an amount of 80 mol% or more, further 90 mol% or more. When the PPS component is in such a preferable range, the crystallinity and thermal transition temperature of the polymer are high, and the heat resistance, dimensional stability, mechanical properties, dielectric properties, etc., which are the characteristics of the resin composition containing PPS as a main component, are sufficient. Can be demonstrated.

In the above PPS resin, if it is less than 20 mol%, preferably less than 10 mol% of the repeating unit,
A unit containing other copolymerizable sulfide bond may be contained. Examples of such a unit containing another copolymerizable sulfide bond include a trifunctional unit, an ether unit, a sulfone unit, a ketone unit, a meta bond unit, an aryl unit having a substituent such as an alkyl group, and a biphenyl unit. , Terphenylene units, vinylene units, carbonate units and the like, as specific examples,
One or more of these can coexist. In this case, the copolymer may be a random type or block type copolymer. The PPS resin may be used alone or as a polymer alloy with another polymer. Other polymers for forming a polymer alloy include polyester, liquid crystal polyester, polyamide, polyolefin, polyimide, polyamideimide, polyetherimide, polyarylate, modified polyphenylene sulfide, polyetheretherketone, polyethersulfone, polysulfone and the like. It can be preferably used.

The PPS fiber sheet used in the present invention can be obtained by melt spinning of the above PPS resin. As the melt spinning method, any conventionally known method can be adopted. In the present invention, the preferred PPS fiber melt spinning speed is 3000 m / min to 8000 m / min, and more preferably 4000 m / min to 6000 m / min. Also,
After melt spinning, it may be stretched at a predetermined ratio or may be heat treated after stretching.

The PPS fiber used in the present invention has a temperature of 30 ° C.
It is necessary in the present invention that the coefficient of thermal expansion up to 100 is 10 ppm / ° C. or less. When the coefficient of thermal expansion from 30 ° C. to 100 exceeds 10 ppm / ° C., when a copper foil is laminated on the surface layer as a circuit board, curling or wrinkling occurs due to the difference in coefficient of thermal expansion from the copper foil.

In the present invention, the coefficient of thermal expansion is measured by thermomechanical analysis (TMA), and the temperature rising / falling rate is 20 ° C. /
It can be obtained from the slope of the thermal deformation curve when the temperature is lowered when the temperature is lowered from 20 ° C. to 200 ° C. under a tensile load of 2 g.

The PPS fiber used in the present invention is 30
The coefficient of thermal expansion from ℃ to 200 ℃ is preferably 20 ppm / ℃ or less, more preferably 15 ppm / ℃ or less.

A fiber sheet is obtained from the PPS fibers thus obtained, and the fiber sheet means a thin leaf body composed of an aggregate of fibers, for example, a woven fabric composed of fibers, This refers to knitting, non-woven fabric, paper or the like, and as the non-woven fabric, for example, non-woven fabric manufactured by a dry method, a spun bond method, a melt blow method, a needle punch method, a thermal bond method, a water jet method, a papermaking method or the like can be used. Of course, the fibers may be long fibers or short fibers. In the non-woven fabric produced by the papermaking method, a binder may be used for binding the fibers to each other.

The resin-impregnated fiber sheet of the present invention is a sheet obtained by impregnating the above fiber sheet with a thermosetting resin. In the present invention, the thermosetting resin to be impregnated is preferably one or more selected from the group consisting of epoxy resin, acrylic resin, melamine resin, phenol resin, vinyl ester resin, polyimide resin and a mixture of any two or more thereof. Can be used.

To obtain the resin-impregnated fiber sheet of the present invention,
For example, the fiber sheet may be impregnated with the thermosetting resin and then dried at 100 ° C. to 250 ° C. for 1 minute to 100 minutes. The impregnated state of the curable resin can be observed and measured, for example, from a cross-sectional photograph taken with an electron microscope. The resin impregnation rate obtained from this cross-sectional photograph as described below is preferably 85% or more, more preferably 90% or more. When the resin impregnation rate is in such a preferable range, the through hole processability can be made excellent.

Regarding the thermosetting resin layer of the resin-impregnated fiber sheet of the present invention and the PPS fiber sheet thickness ratio, when observing each layer with a microscope from the cross section of the resin-impregnated fiber sheet,
Ratio (b / b) of thickness (b) of layer composed of thermosetting resin alone to thickness (a) of fiber sheet layer impregnated with thermosetting resin
The range of a) is preferably 0.2 to 2.0, more preferably 0.2 to 1.5. Such a preferable range is preferable in terms of the impregnation rate of the resin-impregnated fiber sheet, thermal dimensional stability, dielectric properties, and through-hole processability.

The resin-impregnated fiber sheet of the present invention thus obtained preferably has a thickness of 50 μm to 1000 μm, more preferably 50 μm to 700 μm.

Further, another base material (metal, sheet) may be laminated on at least one surface of the resin-impregnated fiber sheet of the present invention, or another resin or coating agent may be coated or molded. Good. Further, the resin-impregnated fiber sheet of the present invention may be oxidatively cross-linked with heat or ultraviolet rays.

The resin-impregnated fiber sheet of the present invention is particularly suitable as a base material for a circuit board. The circuit board of the present invention is one in which an electric circuit is formed on at least one surface of the resin-impregnated fiber sheet.

The electric circuit is an electric passage in which a conductor is patterned, and as the conductor, a metal such as copper or aluminum, or a conductive paint containing copper, silver, carbon or the like is usually used. . Moreover, an electric component or an electronic component may be mounted on the electric circuit. Further, the circuit board may be laminated in two or more layers. Such a circuit board can be easily drilled with a drill or a laser. The circuit is formed by applying a photosensitive resin to a metal foil attached to a resin-impregnated fiber sheet, baking the circuit shape with light, and then removing the unexposed resin, and in the case of copper foil, an aqueous solution of ferric chloride. The method of etching can be used.

The resin-impregnated fiber sheet of the present invention has particularly excellent thermal dimensional stability and is excellent in through-hole processability when forming holes by a laser.

Next, the resin-impregnated fiber sheet of the present invention and the method for producing a circuit board using the resin-impregnated fiber sheet will be described, but the present invention is not limited thereto.

The resin-impregnated fiber sheet of the present invention is a sheet obtained by impregnating a resin composition into a fiber sheet made of PPS.
The method for manufacturing the PPS fiber sheet will be described below.

A typical method for producing the PPS polymer used in the present invention is to use p-dichlorobenzene and sodium sulfide as monomers, and to use as a crosslinking agent in N-methyl-2-pyrrolidone as necessary. There is a method of pressure polymerization by adding 2,2,4-trichlorobenzene and lithium acetate as an auxiliary agent. It is preferable that the polymer thus obtained is not subjected to air oxidation for thickening after the completion of the polymerization, and if air oxidation is carried out, the spinnability and the properties of the product yarn are deteriorated.

The amount of the trihalo-substituted benzene used as the cross-linking agent varies depending on the polymerization conditions and the target molecular weight of the final product, but it is usually 0 to 0.
About 5 mol% is good.

Next, the PPS resin is melt-spun to form PP.
Obtain an S fiber sheet. The PPS fiber sheet is obtained by quantitatively spinning PPS melted by a spinning machine through a spinneret having a porous structure, and further stretching the fiber to obtain a fiber. The spinning speed is preferably 3000 m / min or more, more preferably 5000 m / min or more, still more preferably 60.
It is more than 00 m / min. As a method for obtaining a fiber sheet from high-speed spun PPS fibers, a dry method, a spun bond method, or the like can be used. The dry method is a method of making the obtained fibers into a cotton shape and making a fiber sheet of short fibers by a spinning card or a random weber by an air flow, and generally, the fiber layers coming out from the card are cross-laminated or laminated as they are. Combine to make a cotton-like fiber sheet. In the air flow method, short fibers are blown off by a land weber and collected as a uniform fiber sheet.

The spunbond method is a method in which the filaments coming out of the spinneret are directly and randomly dispersed and accumulated on a net-shaped conveyor to produce a fiber sheet.

The fiber sheet obtained as described above is subjected to processing such as needle punching, calendering roll and impregnation with an adhesive, if necessary. Further, for the purpose of improving adhesiveness, surface treatment such as corona discharge treatment or plasma treatment is performed. The fiber sheet thus obtained is impregnated with a thermosetting resin such as an epoxy resin, an acrylic resin, a melamine resin, a vinyl ester resin or a polyimide resin. As the method of impregnation, continuous or batch treatment can be performed by immersing in a liquid bath of thermosetting resin.

Next, an electric circuit is formed on at least one surface of the resin-impregnated fiber sheet obtained as described above. The method for forming the electric circuit is not particularly limited,
Usually, after adhering metal foil or forming a vapor deposition film, the metal foil or vapor deposition film is etched by a known method. When forming a circuit with a conductive paint, a generally known screen printing method is used.

Further, through holes may be provided in the above circuit board. The through holes can be provided by a method such as a drill or a laser, but the circuit board of the present invention is preferably processed by laser. Further, the layers can be connected to each other by a method such as a plating method. In addition, electronic components and the like are mounted on the circuit board by soldering or the like as necessary. [Physical property measuring method] The physical property measuring method used in the present invention will be described below. (1) Coefficient of thermal expansion The coefficient of thermal expansion was measured using a thermomechanical analysis (TMA) device TMA / SS6100 manufactured by Seiko Instruments Inc.
A tensile load of 2 g is applied to the test sample, and the temperature is 20 ° C to 20 ° C.
After raising the temperature to 0 ° C at a heating rate of 20 ° C / min, 2
The coefficient of thermal expansion (α) from 20 ° C to 200 ° C is divided by the following formula by dividing the dimensional change amount (B) in the temperature decreasing process when returning to 0 ° C at a temperature decreasing rate of 20 ° C / min by the initial length (A). I asked.

Α (× 10 ⁻⁶ / ° C.) = B / A × 1 / (200-20) (2) Dielectric Properties (Dielectric Loss) Changes in the dielectric loss were examined by changing the frequency. JIS C
It was measured according to 6481. (3) Resin impregnation rate Photograph the cross section of the resin impregnated fiber sheet with an electron microscope,
Obtained from the ratio of the sum of the arc lengths of the elementary fibers in which the elementary fibers are in contact with the resin or the adjacent elementary fibers to the sum of the diameters of the elementary fibers of the fiber sheet, and the measurement visual field is randomly set to 20 visual fields. The average value was defined as the resin impregnation rate (%). However, the magnification of the electron microscope was 3000 times. (4) Flatness The circuit board made of the resin-impregnated fiber sheet was passed through a furnace (hot air system) set at 240 ° C. for 30 seconds to examine the flatness of the circuit board. Regarding the planarity of the circuit board, samples cut into 150 mm square were placed in parallel on a flat table, and the floating height of the film from the table was measured and divided into the following four ranks.

◎: Less than 2 mm △: 2 mm or more and less than 5 mm ×: 5 mm or more (5) Through hole processability In order to evaluate the through hole processability of the circuit board as a model, ESI was applied to the resin-impregnated fiber sheet. Through holes were formed using a UV YAG laser manufactured by the company. Cut the laminate so that it passes through the center of the through hole, and then use an electron microscope to measure the inner diameter of the through hole (A).
Was measured, and the through-hole rate with respect to the thickness (B) of the laser beam was calculated.

Through-hole rate (%) = A / B × 100 ○: Through-hole rate of 90% or more Δ: Through-hole rate of 60% or more and less than 90% X: Through-hole rate is less than 60%

[0040]

Example 1 Sodium sulfide and p were added in N-methyl-2-pyrrolidone.
− Dichlorobenzene at high temperature in the presence of sodium benzoate
The PPS pellets having an apparent viscosity of 3700 poises at 300 ° C. obtained by reacting under high pressure were spun at a spinning temperature of 330.
The obtained fiber was heat-set at 200 to 250 ° C. to obtain a PPS fiber having a thermal expansion coefficient of 7 ppm / ° C. at 30 to 100 ° C. The PP
S fiber is used as short fiber, then the short fiber is laminated, needle punched under the condition of needle depth of 5 mm and needle density of 150 needles / cm ² , calendered at a temperature of 249 ° C., thickness of 100 μm, and basis weight of 40 g / to obtain a PPS fiber sheet of m ^2. The obtained PPS fiber sheet was impregnated with a PPS fiber sheet made of epoxy resin (HHR: manufactured by Mitsubishi Electric Corporation). Next, the resin-impregnated fiber sheet was dried by a tenter at 220 ° C. for 3 minutes. The thermal expansion coefficient of the obtained resin-impregnated fiber sheet was 18 ppm / ° C. The characteristics of the resin-impregnated fiber sheet are shown in Table 1.

An epoxy adhesive (Chemit: manufactured by Toray Industries, Inc.) was applied to the surface of the resin-impregnated fiber sheet with a gravure roll coater to a thickness of 15 μm / dry, and the solvent was dried at 100 ° C. for 3 minutes. Next, a 1 ounce (36 μm thick) rolled copper foil was laminated by a hot press roll method. The lamination conditions are a temperature of 125 ° C. and a pressure of 3 kg / cm ² . Furthermore, 1
The adhesive was cured under the condition of 50 ° C. for 1 hour. The obtained circuit board was excellent in thermal dimensional stability and through-hole processability. The results are also shown in Table 1.

[0042]

[Table 1] Example 2 The PPS pellets obtained in Example 1 were subjected to a spunbond method at a spinning temperature of 330 ° C. and a take-up speed of 5500 m / m.
For 30 to 1 minute by heat setting at 200 ℃ to 250 ℃
A PPS fiber having a thermal expansion coefficient of 00 ° C. of 8 ppm / ° C. was obtained. Then, with an embossing roll at 230 ° C, a linear pressure of 60 kg
Thermocompression-bonding was carried out at a pressure of 1 cm / cm to produce a long-fiber nonwoven fabric. Then
Needle punch processing is performed using the 20th conical felt needle manufactured by Groz-Beckert, and the thickness is 100μ.
Thus, a PPS fiber sheet having m and a basis weight of 50 g / m ² was obtained. The obtained PPS fiber sheet was impregnated with an epoxy resin in the same manner as in Example 1 to obtain a resin-impregnated fiber sheet. The thermal expansion coefficient of the obtained resin-impregnated fiber sheet was 20 ppm / ° C. The characteristics of the resin-impregnated fiber sheet are also shown in Table 1.

A circuit board was produced in the same manner as in Example 1 on the surface of the resin-impregnated fiber sheet. The obtained circuit board was excellent in thermal dimensional stability and through-hole processability. The results are also shown in Table 1. Example 3 The PPS pellets obtained in Example 1 were spun at a spinning temperature of 330.
℃, take-off speed 3000m / min spinning, then 11
After stretching 1.5 times in the stretching process at 0 ° C, 200
It was heat-set at ℃ to 250 ℃ to obtain PPS fiber having a thermal expansion coefficient of 7 ppm / ℃ at 30 to 100 ℃. Then, the PPS
A fiber was obtained in the same manner as in Example 1 to obtain a PPS fiber sheet.
The obtained PPS fiber sheet was impregnated with an epoxy resin in the same manner as in Example 1 to obtain a resin-impregnated fiber sheet. The thermal expansion coefficient of the obtained resin-impregnated fiber sheet was 19 ppm / ° C. The characteristics of the resin-impregnated fiber sheet are also shown in Table 1.

A circuit board was prepared in the same manner as in Example 1 on the surface of the resin-impregnated fiber sheet. The obtained circuit board was excellent in thermal dimensional stability and through-hole processability. The results are also shown in Table 1. Comparative Example 1 The PPS pellets obtained in Example 1 were collected at a take-up speed of 1
PPS fibers were obtained in the same manner as in Example 1 except that the speed was 500 m / min. The thermal expansion coefficient of the obtained PPS fiber at 30 to 100 ° C was 50 ppm / ° C. The PPS fiber was prepared in the same manner as in Example 1 so as to have a thickness of 100 μm and a weight per unit area of 40 g / m ² .
A PS fiber sheet was obtained. The obtained PPS fiber sheet was impregnated with an epoxy resin in the same manner as in Example 1 to obtain a resin-impregnated fiber sheet. The thermal expansion coefficient of the obtained resin-impregnated fiber sheet was 70 ppm / ° C. The characteristics of the resin-impregnated fiber sheet are also shown in Table 1.

A circuit board was prepared on the surface of the resin-impregnated fiber sheet in the same manner as in Example 1. The circuit board obtained was excellent in through-hole processability, but the flatness of the circuit board deteriorated under high temperature conditions. Comparative Example 2 As the fiber sheet, a cloth EPC050 made of glass fiber manufactured by Arisawa Manufacturing Co., Ltd. was used. The glass cloth is
The density ratio of the warp yarn to the weft yarn was 1.1, the basis weight was 47 g / m ² , and the thickness was 55 μm. The glass cloth was impregnated with an epoxy resin in the same manner as in Example 1, and dried at 220 ° C. for 3 minutes with a tenter to obtain a resin-impregnated fiber sheet. The thermal expansion coefficient of the obtained resin-impregnated sheet was 19 ppm / ° C. The characteristics of the resin-impregnated fiber sheet are also shown in Table 1.

A rolled copper foil was laminated on the surface of the resin-impregnated fiber sheet in the same manner as in Example 1. The obtained circuit board had a problem in through hole processability. The results are shown in Table 1. Comparative Example 3 P that is a thermoplastic resin in place of the thermosetting resin in Example 1
A resin-impregnated fiber sheet was obtained in the same manner as in Example 1 except that the PS resin was impregnated. The PPS pellets used in Example 1 were used as the PPS resin. A composition in which 0.2% by weight of silica fine powder having an average particle size of 0.7 μm was uniformly dispersed in the PPS pellets was melted at 310 ° C. by an extruder having a diameter of 40 mm, and a 95% cut pore size was 10 μm using a metal wire mesh. After filtering with a filter of 400m, the length is 400m
m, a T die having a linear lip with a gap of 0.5 mm, and cast on a metal drum whose surface temperature was kept at 25 ° C. to obtain a 50 μm thick PPS unstretched, unoriented sheet. The PPS sheet / PPS fiber sheet / PPS sheet were superposed in this order and impregnated by the hot plate pressing method to be laminated. Press conditions are 20 kg / c at a temperature of 280 ° C
It was a pressure of m ² . The thickness of the obtained resin-impregnated fiber sheet was 160 μm. The coefficient of thermal expansion of the resin-impregnated fiber sheet was 50 ppm / ° C. The characteristics of the resin-impregnated fiber sheet are also shown in Table 1.

A rolled copper foil was laminated on the surface of the resin-impregnated fiber sheet in the same manner as in Example 1. The obtained circuit board had a low resin impregnation rate and thus had insufficient through-hole processability, and the flatness of the circuit board deteriorated under high temperature conditions. The results are also shown in Table 1.

[0048]

According to the present invention, a resin-impregnated fiber sheet suitable as an insulating base material for a circuit board, which is excellent in thermal dimensional stability and laser through-hole processability, and a circuit board using the same can be obtained. .

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Claims (4)

[Claims] 1. The coefficient of thermal expansion from 30 ° C. to 100 ° C. is 10.
A resin-impregnated fiber sheet, which is obtained by impregnating a thermosetting resin into a fiber sheet made of polyphenylene sulfide fiber having a ppm / ° C or less. 2. A polyphenylene sulfide fiber at 30 ° C.
The resin-impregnated fiber sheet according to claim 1, wherein the thermal expansion coefficient up to 200 ° C is 20 ppm / ° C or less. 3. The thermosetting resin is one or more selected from the group consisting of epoxy resin, acrylic resin, melamine resin, phenol resin, vinyl ester resin, polyimide resin and a mixture of any two or more thereof. The resin-impregnated fiber sheet according to claim 1 or 2, which is characterized. 4. A circuit board comprising the resin-impregnated fiber sheet according to any one of claims 1 to 3, and an electric circuit comprising a metal layer formed on at least one surface thereof.