JP4957079B2 - Printed circuit board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a glass fiber reinforced composite material, a method for producing the same, and a printed circuit board.

  In order to increase the signal transmission speed of the printed circuit board, it is necessary to lower the dielectric constant of the electrical insulator layer. In order to reduce the transmission loss of the printed circuit board, it is necessary to lower the dielectric loss tangent of the electrical insulator layer. Therefore, in applications where an increase in signal transmission speed and a reduction in transmission loss are required, for example, in electronic equipment that performs signal transmission in a high frequency band, a printed circuit using a fluororesin having a low dielectric constant and a low dielectric loss tangent as an electrical insulator layer A substrate is used.

As a printed circuit board using a fluororesin as an electrical insulator layer, a conductive material made of a metal foil such as a copper foil on at least one surface of a prepreg in which a glass fiber woven fabric such as a glass cloth is impregnated with a fluororesin dispersion is used. A printed circuit board having a body layer is known (see Patent Documents 1 and 2).
In the printed circuit board, the dielectric constant and transmission loss of the electrical insulator layer can be lowered by increasing the impregnation rate of the fluororesin in the prepreg.

However, the printed circuit board has the following problems.
(1) In order to increase the impregnation rate of the fluororesin in the prepreg, it is necessary to repeat the impregnation of the dispersion of the fluororesin into the woven fabric of glass fibers a plurality of times. Therefore, the productivity of the printed circuit board is significantly reduced.
(2) As a fluororesin, polytetrafluoroethylene (PTFE) having a low dielectric constant and a low dielectric loss tangent is often used. However, since PTFE has low adhesion to metal, when plating is performed on the through hole of the electrical insulator layer, the plating does not adhere to the through hole or the plating is easily peeled off from the through hole. This problem causes a conduction failure in the through hole.

(3) In order to improve the adhesion of the plating to the through hole, it is known that the prepreg contains inorganic fine particles (Patent Document 2). However, since the dielectric constant of inorganic fine particles is higher than that of fluororesin, in order to maintain a low dielectric constant while adding inorganic fine particles, the amount of woven fabric of glass fiber is reduced and the impregnation rate of fluororesin is maintained. There is a need. Therefore, the coefficient of thermal expansion (CTE) of the electrical insulator layer is increased, and the mechanical strength (such as elastic modulus) is decreased.
JP 2002-158415 A JP 2005-276926 A

  The present invention is a glass fiber reinforced composite material having a low dielectric constant and dielectric loss tangent, high adhesion to metal, low thermal expansion coefficient, and high mechanical strength; the glass fiber reinforced composite material can be produced with high productivity. Manufacturing method: Provided is a printed circuit board having a high signal transmission speed, low transmission loss, suppression of peeling of a conductor layer and plating, a low thermal expansion coefficient, and a high mechanical strength.

The printed circuit board of the present invention includes an electrical insulator layer (A) made of a glass fiber reinforced composite material containing the following fluorine-containing copolymer (F) and glass fiber (G), and the electrical insulator layer (A And a conductor layer (B) in direct contact with the substrate .
A repeating unit (a) based on tetrafluoroethylene and / or chlorotrifluoroethylene, a repeating unit (b) based on a fluorine monomer (excluding tetrafluoroethylene and chlorotrifluoroethylene), and an acid anhydride residue And a repeating unit (c) based on a monomer having a polymerizable unsaturated bond, and the repeating unit (a) is 50 to 99.% of the total 100 mol% of the repeating units (a) to (c). The fluorine-containing copolymer (F) which is 89 mol%, the said repeating unit (b) is 0.1-49.99 mol%, and the said repeating unit (c) is 0.01-5 mol%.

The fluorine-containing copolymer (F) further has a repeating unit (d) based on a non-fluorine monomer (excluding a monomer having an acid anhydride residue and a polymerizable unsaturated bond), and the repeating unit The molar ratio (((a) + (b) + (c)) / (d)) of the sum of (a) to (c) and the repeating unit (d) is 100/5 to 100/90. It is preferable.
The monomer having an acid anhydride residue and a polymerizable unsaturated bond may be at least one selected from the group consisting of itaconic anhydride, citraconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride. preferable.

In the method for producing a printed circuit board according to the present invention, the glass fiber reinforced composite material is obtained by combining the fluorine-containing copolymer (F) film and the glass fiber (G) fabric by a thermal lamination method. It is characterized by that.
The melt viscosity of the fluorine-containing copolymer (F) during thermal lamination is preferably 100 to 10,000 Pa · s.

In the printed circuit board of this invention, it is preferable that a part or all of glass fiber (G) exists in the depth of 1-40 micrometers from the surface of the said electrical insulator layer (A).
The glass fiber (G) is a glass cloth composed of warp and weft, and the porosity determined by the following formula (I) is preferably 0 to 25%.
Porosity = {(t ₁ −s ₁ ) × (t ₂ −s ₂ )} / (t ₁ × t ₂ ) × 100 (I).
Here, s ₁ is the average value (μm) of the cross-sectional width of the warp yarn bundle, t ₁ is the average value (μm) of the warp yarn bundle interval, and s ₂ is the weft yarn bundle. It is an average value (μm) of the cross-sectional width, and t ₂ is an average value (μm) of the yarn bundle interval of the weft yarn.

The glass fiber reinforced composite material of the present invention has a low dielectric constant and dielectric loss tangent, high adhesion to metal, low thermal expansion coefficient, and high mechanical strength.
According to the method for producing a glass fiber reinforced composite material of the present invention, a glass fiber reinforced composite material having low dielectric constant and dielectric loss tangent, high adhesion to metal, low thermal expansion coefficient and high mechanical strength is produced. Can be manufactured with good performance.
The printed circuit board of the present invention has a high signal transmission speed, low transmission loss, suppression of peeling of the conductor layer and plating, a low thermal expansion coefficient, and high mechanical strength.

  In the present specification, a compound represented by the formula (1) is referred to as a compound (1). The same applies to compounds represented by other formulas.

<Glass fiber reinforced composite material>
The glass fiber reinforced composite material of the present invention contains a fluorine-containing copolymer (F) and glass fiber (G).
FIG. 1 is a cross-sectional view showing an example of the glass fiber reinforced composite material of the present invention. The glass fiber reinforced composite material 10 includes a fluorine-containing copolymer (F) 12 and glass fibers (G) 14 embedded in the fluorine-containing copolymer (F) 12.

(Fluorine-containing copolymer (F))
The fluorine-containing copolymer (F) has the following repeating units (a) to (c). The fluorine-containing copolymer (F) may have the following repeating unit (d).
(A) a repeating unit based on tetrafluoroethylene (hereinafter referred to as TFE) and / or chlorotrifluoroethylene (hereinafter referred to as CTFE),
(B) a repeating unit based on a fluorine monomer (excluding TFE and CTFE),
(C) a repeating unit based on a monomer having an acid anhydride residue and a polymerizable unsaturated bond (hereinafter referred to as AM monomer);
(D) Repeating units based on non-fluorine monomers (excluding AM monomers).

Examples of the fluorine monomer include the following compounds.
Fluoroolefin: vinyl fluoride, vinylidene fluoride (hereinafter referred to as VdF), trifluoroethylene, hexafluoropropylene (hereinafter referred to as HFP), etc.
CF ₂ = CFOR ¹ (1),
CF ₂ = CFOR ² SO ₂ X ¹ (2),
CF ₂ = CFOR ³ CO ₂ X ² (3),
CF ₂ = CF (CF ₂ ) _p OCF = CF ₂ (4),
CH ₂ = CX ³ (CF ₂ ) _q X ⁴ (5),
Perfluoro (4-methyl-1,3-dioxole),
Perfluoro (2,2-dimethyl-1,3-dioxole) and the like.

However, R ¹ represents a perfluoroalkyl group having 1 to 10 carbon atoms which may atoms contain an oxygen atom,
R ² represents a C 1-10 perfluoroalkylene group which may contain an oxygen atom between carbon atoms, X ¹ represents a halogen atom or a hydroxyl group,
R ³ represents a C 1-10 perfluoroalkylene group which may contain an oxygen atom between carbon atoms, X ² represents a hydrogen atom or an alkyl group having 3 or less carbon atoms,
p represents 1 or 2,
X ³ represents a hydrogen atom or a fluorine atom, q represents an integer of 2 to 10, and X ⁴ represents a hydrogen atom or a fluorine atom.

As a fluorine monomer, VdF, HFP, a compound (1), or a compound (5) is preferable, and a compound (1) or a compound (5) is more preferable.
Examples of the compound (1) include the following compounds.
CF ₂ = CFOCF ₂ CF ₃ (1-1),
CF ₂ = CFOCF ₂ CF ₂ CF ₃ (1-2),
CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ (1-3),
CF ₂ = CFO (CF ₂ ) ₈ F (1-4) and the like.
As the compound (1), the compound (1-2) is preferable.

Examples of the compound (5) include the following compounds.
CH ₂ = CH (CF ₂ ) ₂ F (5-1),
CH ₂ = CH (CF ₂ ) ₃ F (5-2),
_{CH 2 = CH (CF 2)} 4 F ··· (5-3),
CH ₂ = CF (CF ₂ ) ₃ H (5-4),
CH ₂ = CF (CF ₂ ) ₄ H (5-5) and the like.
As the compound (5), the compound (5-1) or the compound (5-3) is preferable.

As the AM monomer, itaconic anhydride (hereinafter referred to as IAH), citraconic anhydride (hereinafter referred to as CAH), 5-norbornene-2,3-dicarboxylic anhydride (hereinafter referred to as NAH), Fluorine-containing copolymer having an acid anhydride residue without using a special polymerization method (see Japanese Patent Application Laid-Open No. 11-193132) required when maleic anhydride is used. IAH, CAH, or NAH is preferable, and IAH or CAH is more preferable from the viewpoint that the combined product can be easily produced.
The fluorine-containing copolymer (F) has repeating units based on dicarboxylic acids such as itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid, etc., which are hydrolyzed by AM monomers. Also good. When having a repeating unit based on the dicarboxylic acid, the amount of the repeating unit (c) is the total amount of the repeating unit based on the AM monomer and the repeating unit based on the dicarboxylic acid.

Examples of the non-fluorine monomer include the following compounds.
Olefin having 3 or less carbon atoms: ethylene (hereinafter referred to as E), propylene (hereinafter referred to as P), etc.
Vinyl ester: vinyl acetate (hereinafter referred to as VOA), etc.
Vinyl ether: ethyl vinyl ether, cyclohexyl vinyl ether, etc.
As the non-fluorine monomer, E, P, or VOA is preferable, and E is more preferable.

The repeating unit (a) is 50 to 99.99 mol%, preferably 50 to 99.4 mol%, and preferably 50 to 98.9 mol, out of a total of 100 mol% of the repeating units (a) to (c). % Is more preferable.
The repeating unit (b) is 0.1 to 49.99 mol%, preferably 0.5 to 49.9 mol%, out of a total of 100 mol% of the repeating units (a) to (c). 49.9 mol% is more preferable.
The repeating unit (c) is 0.01 to 5 mol%, preferably 0.1 to 3 mol%, preferably 0.1 to 2 mol, out of a total of 100 mol% of the repeating units (a) to (c). % Is more preferable.
When the repeating units (a) to (c) are in this range, the obtained glass fiber reinforced composite material is excellent in heat resistance and chemical resistance. When the repeating unit (b) is in this range, the fluorine-containing copolymer (F) is excellent in moldability and excellent in mechanical strength such as stress crack resistance. When the repeating unit (c) is in this range, the obtained glass fiber reinforced composite material is excellent in adhesion to metal.

The total of repeating units (a) to (c) is preferably 60 mol% or more, more preferably 65 mol% or more, and 68 mol% or more of all repeating units constituting the fluorinated copolymer (F). Particularly preferred.
When the repeating unit (d) is included, the molar ratio (((a) + (b) + (c)) / (d)) of the total of the repeating units (a) to (c) and the repeating unit (d) is 100/5 to 100/90 are preferable, 100/5 to 100/80 are more preferable, and 100/10 to 100/66 is particularly preferable.
The ratio of each repeating unit is determined by a known method from the results of melt NMR analysis, fluorine content analysis, and infrared absorption spectrum analysis.

As the fluorine-containing copolymer (F), the following copolymers are preferable.
TFE / compound (1-2) / IAH copolymer,
TFE / compound (1-2) / CAH copolymer,
TFE / HFP / IAH copolymer,
TFE / HFP / CAH copolymer,
TFE / VdF / IAH copolymer,
TFE / VdF / CAH copolymer,
TFE / compound (5-3) / IAH / E copolymer,
TFE / compound (5-3) / CAH / E copolymer,
TFE / compound (5-1) / IAH / E copolymer,
TFE / compound (5-1) / CAH / E copolymer,
CTFE / compound (5-3) / IAH / E copolymer,
CTFE / compound (5-3) / CAH / E copolymer,
CTFE / compound (5-1) / IAH / E copolymer,
CTFE / compound (5-3) / CAH / E copolymer.

  The fluorine-containing copolymer (F) is an ester group, a carbonate group, a hydroxyl group, a carboxyl group, a carbonyl fluoride group, an acid anhydride as a polymer end group from the viewpoint of adhesion between the glass fiber reinforced composite material and the metal. It may have a functional group such as The polymer end group can be introduced by appropriately selecting a radical polymerization initiator, a chain transfer agent and the like used in the production of the fluorine-containing copolymer (F).

As a manufacturing method of a fluorine-containing copolymer (F), the method of superposing | polymerizing each monomer using a radical polymerization initiator is mentioned.
As the polymerization method, a bulk polymerization method; a solution polymerization method using an organic solvent such as fluorinated hydrocarbon, chlorinated hydrocarbon, fluorinated chlorohydrocarbon, alcohol, hydrocarbon; an aqueous medium and an appropriate organic solvent as required Suspension polymerization method used; emulsion polymerization method using an aqueous medium and an emulsifier can be mentioned, and solution polymerization method is particularly preferable.

The radical polymerization initiator is preferably a radical polymerization initiator having a half-life of 10 hours at a temperature of 0 to 100 ° C., more preferably a radical polymerization initiator having a temperature of 20 to 90 ° C.
Examples of the radical polymerization initiator include the following compounds.
Azo compound: azobisisobutyronitrile, etc.
Non-fluorinated diacyl peroxide: isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, lauroyl peroxide, etc.
Peroxydicarbonate: Diisopropyl peroxydicarbonate, etc.
Peroxy ester: tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, tert-butyl peroxyacetate, etc.
Fluorine-containing diacyl peroxide: Compound (6), etc.
Inorganic peroxide: potassium persulfate, sodium persulfate, ammonium persulfate and the like.
(Z (CF ₂ ) _r COO) ₂ (6).
However, Z shows a hydrogen atom, a fluorine atom, or a chlorine atom, r shows the integer of 1-10.

In order to control the melt viscosity of the fluorinated copolymer (F), a chain transfer agent may be used. Examples of the chain transfer agent include the following compounds.
Alcohol: methanol, ethanol, etc.
Chlorofluorohydrocarbon: 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, etc.
Hydrocarbon: pentane, hexane, cyclohexane, etc.
Chain transfer agent having the functional group: acetic acid, acetic anhydride, methyl acetate, ethylene glycol, propylene glycol and the like.
As the chain transfer agent, a chain transfer agent having a functional group is preferable from the viewpoint that adhesion between the fluorine-containing copolymer (F) and the metal is improved by introducing the functional group into the polymer terminal group.

The polymerization temperature is preferably 0 to 100 ° C, and more preferably 20 to 90 ° C.
The polymerization pressure is preferably from 0.1 to 10 MPa, more preferably from 0.5 to 3 MPa.
The polymerization time is preferably 1 to 30 hours.
The concentration of the AM monomer is preferably from 0.01 to 5 mol%, more preferably from 0.1 to 3 mol%, particularly preferably from 0.1 to 1 mol%, based on 100 mol% of all monomers. When the concentration of the AM monomer is within this range, the polymerization rate is moderate, and the resulting fluorine-containing copolymer (F) has good adhesion. When the concentration of the AM monomer is too high, the polymerization rate tends to decrease. During the polymerization, it is preferred to supply the consumed amount continuously or intermittently as the AM monomer is consumed in the polymerization, and to maintain the AM monomer concentration in this range.

(Glass fiber (G))
Examples of the glass fiber (G) include fabrics such as woven fabrics (glass cloth, etc.) and glass nonwoven fabrics, and fabrics are preferred, and glass cloths are particularly preferred from the viewpoint of a high effect of reducing the thermal expansion coefficient.
Examples of the glass fiber (G) material include E glass, C glass, A glass, S glass, D glass, NE glass, T glass, quartz, low dielectric constant glass, and high dielectric constant glass. Therefore, E glass, S glass, T glass, and NE glass are preferable.

The glass fiber (G) has improved adhesion to the fluorinated copolymer (F), and as a result, the mechanical strength, heat resistance, and through-hole reliability are improved, such as a silane coupling agent. The surface treatment may be performed with a known surface treatment agent.
The amount of the glass fiber (G) is preferably 1 to 90 parts by mass, more preferably 2 to 80 parts by mass, and particularly preferably 5 to 60 parts by mass with respect to 100 parts by mass of the fluorinated copolymer (F). If the amount of glass fiber (G) is within this range, molding is easy and heat resistance can be maintained.

(Inorganic filler)
The glass fiber reinforced composite material may contain an inorganic filler having a low dielectric constant and a low dielectric loss tangent as necessary.
Inorganic fillers include silica, clay, talc, calcium carbonate, mica, diatomaceous earth, alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, calcium hydroxide, magnesium hydroxide, water Aluminum oxide, basic magnesium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dosonite, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass beads, silica Balloons, carbon black, carbon nanotubes, carbon nanohorns, graphite, carbon fibers, glass balloons, carbon balloons, wood powder, zinc borate and the like. An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

As the inorganic filler, a porous inorganic filler is preferable because the dielectric constant and dielectric loss tangent of the glass fiber reinforced composite material are lowered.
The inorganic filler may be surface-treated with a surface treatment agent such as a silane coupling agent or a titanate coupling agent from the viewpoint of improving dispersibility in the fluorine-containing copolymer (F).
100 mass parts or less are preferable with respect to 100 mass parts of fluorine-containing copolymers (F), and, as for the quantity of an inorganic filler, 60 mass parts or less are more preferable.

(Fluororesin fiber, fluororesin fine particles)
The glass fiber reinforced composite material may contain fluororesin fibers and / or fluororesin fine particles as necessary.
Examples of fluororesin fibers or fluororesin fine particles include polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), and polychloro. Trifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), ethylene / tetrafluoroethylene copolymer (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene / hexafluoropropylene / perfluoroalkyl vinyl ether Examples thereof include copolymers (EPE), and PTFE, PFA, and FEP are preferred from the viewpoints of low dielectric constant and dielectric loss tangent, and excellent heat resistance and chemical resistance.
A fluororesin fiber may be used individually by 1 type, and may use 2 or more types together.

The diameter of the fluororesin fiber is preferably 40 μm or less. The length of the fluororesin fiber is preferably 10 mm or less. When the diameter and length of the fluororesin fibers exceed the upper limit, it becomes difficult to produce a thin film.
The particle diameter of the fluororesin fine particles is preferably 40 μm or less. When the particle diameter of the fluororesin fine particles exceeds the upper limit, it becomes difficult to produce a thin film.
A fluororesin fiber may be used individually by 1 type, and may use 2 or more types together. Moreover, fluororesin fine particles may be used individually by 1 type, and may use 2 or more types together.
The total amount of the fluororesin fibers and the fluororesin fine particles is preferably 70 parts by mass or less with respect to 100 parts by mass of the fluorocopolymer (F).

<Method for producing glass fiber reinforced composite material>
The following method is mentioned as a manufacturing method of a glass fiber reinforced composite material.
(I) A thermal lamination method in which a pre-formed film of a fluorinated copolymer (F) and a glass fiber (G) fabric are combined under heating.
(Ii) An extrusion lamination method in which a molten resin of the fluorine-containing copolymer (F) extruded from a die or the like and a glass fiber (G) fabric are combined.
(Iii) An impregnation method in which a glass fiber (G) fabric is immersed in a solution in which the fluorinated copolymer (F) fine particles are dispersed, and then taken out and then combined through a drying step.
As a method for producing a glass fiber reinforced composite material, the method (i) or (ii) is preferred, and the method (i) is more preferred because the production equipment can be simplified and the productivity is higher.

In order to increase the impregnation property of the fluorine-containing copolymer (F) into the glass fiber (G) fabric, the melt viscosity of the fluorine-containing copolymer (F) may be adjusted to an appropriate range.
The melt viscosity of the fluorinated copolymer (F) in the method (i) is preferably 100 to 10000 Pa · s, more preferably 300 to 8000 Pa · s, and particularly preferably 500 to 6000 Pa · s at the temperature during thermal lamination. . By setting the melt viscosity to 100 Pa · s or more, the impregnation property of the fluorocopolymer (F) into the fabric of the glass fiber (G) is improved. By setting the melt viscosity to 10000 Pa · s or less, the mechanical strength of the fluorinated copolymer (F) is improved.
The melt viscosity is measured using a flow tester (for example, manufactured by Shimadzu Corporation) with an orifice having an inner diameter of 1 mmφ and a length of 2 mm under conditions of a pressure of 0.98 MPa and a temperature during thermal lamination.

In the method (i), the temperature during thermal lamination at which the melt viscosity of the fluorinated copolymer (F) is in an appropriate range is preferably 20 to 100 ° C. higher than the melting point of the fluorinated copolymer (F). A temperature 30 to 70 ° C. higher than the melting point of the fluorinated copolymer (F) is more preferable.
In the method (ii), the die temperature at which the melt viscosity of the fluorine-containing copolymer (F) is within an appropriate range is preferably 30 to 100 ° C. higher than the melting point of the fluorine-containing copolymer (F). A temperature 40 to 70 ° C. higher than the melting point of the copolymer (F) is more preferable.
The melting point is measured using a DSC apparatus (for example, manufactured by Seiko Electronics Co., Ltd.) by a method based on JIS K7122.

<Printed circuit board>
The printed circuit board of the present invention has an electrical insulator layer (A) made of the glass fiber reinforced composite material of the present invention and a conductor layer (B) in direct contact with the electrical insulator layer (A). .
FIG. 2 is a cross-sectional view showing an example of the printed circuit board of the present invention. The printed circuit board 20 includes an electrical insulator layer (A) 22 made of the glass fiber reinforced composite material 10 and a conductor layer (B) 24 provided on both surfaces of the electrical insulator layer (A) 22. Composed.

(Electric insulator layer (A))
In the electrical insulator layer (A), it is preferable that a part or all of the glass fiber (G) is present at a depth of 1 to 40 μm from the surface. When part or all of the glass fiber (G) is present in this range, the heat resistance of the printed circuit board is improved, and deformation due to heat of molten solder or the like can be suppressed.

As the glass fiber (G), a glass cloth is preferable because the effect of reducing the thermal expansion coefficient is high.
The glass cloth has a plain weave structure in which warp yarns and weft yarns are alternately floated, and twisted yarns are used as warp yarns and weft yarns. In the glass cloth, there are three types of states: a portion where the warp yarn and the weft yarn overlap, a portion where one of the warp yarn and the weft yarn exists, and a portion where there is no glass yarn (gap portion). ing.
As the glass cloth, in order to increase the dimensional stability of the printed circuit board and to suppress the in-plane variation of the dielectric characteristics, a glass cloth having many overlapping portions of warp yarns and weft yarns, that is, a material having few voids is preferable.

  The area ratio of the voids, that is, the void ratio is preferably 0 to 25%, more preferably 0 to 20%, and particularly preferably 0 to 18%. By setting the porosity to this range, even when the printed circuit board is used in an electronic device that performs high-frequency band signal transmission, in-plane variation in transmission loss can be suppressed.

The porosity is determined as follows.
As shown in FIG. 3, the yarn bundle cross-sectional width s and the yarn bundle interval t of the twisted yarn were measured at 20 points for the warp yarn and the weft yarn, respectively, and the average value s ₁ (μm) of the warp yarn bundle cross-sectional width was determined. The average value t ₁ (μm) of the bundle interval, the average value s ₂ (μm) of the cross-sectional width of the weft yarn, and the average value t ₂ (μm) of the weft yarn bundle interval are obtained. Find the rate.
Porosity = {(t ₁ −s ₁ ) × (t ₂ −s ₂ )} / (t ₁ × t ₂ ) × 100 (I).

  10-500 micrometers is preferable per layer, and, as for the thickness of an electrical insulator layer (A), 20-300 micrometers is more preferable. By setting the thickness to 10 μm or more, the printed circuit board is hardly deformed or bent, and the conductor layer (B) is not easily disconnected. By setting the thickness to 500 μm or less, the flexibility is good and the total thickness when laminated is suppressed, and it is possible to cope with downsizing and weight reduction.

(Conductor layer (B))
As the conductor layer (B), a metal foil having a low electric resistance is preferable. Examples of the metal foil include foil made of metal such as copper, silver, gold, and aluminum. A metal may be used individually by 1 type and may use 2 or more types together. When two or more kinds of metals are used in combination, the metal foil is preferably a metal foil subjected to metal plating, and particularly preferably a copper foil subjected to gold plating.
The thickness of the conductor layer (B) is preferably from 0.1 to 100 μm, more preferably from 1 to 50 μm, particularly preferably from 1 to 30 μm.

The conductor layer (B) preferably has a surface roughness (hereinafter referred to as Rz) of 10 μm or less on the surface that is in direct contact with the electrical insulator layer (A) (hereinafter referred to as a roughened surface). . Rz on the roughened surface of the conductor layer (B) is preferably 0.1 to 5 μm, more preferably 0.1 to 3 μm, in view of reducing the skin effect when performing signal transmission in a high frequency band. 1 to 2 μm is particularly preferable.
Rz is measured by a method based on JIS B0601.
An oxide film such as chromate having antirust property may be formed on the surface opposite to the roughened surface of the conductor layer (B).

  The printed circuit board of the present invention is not limited to the three-layer laminate (double-sided printed circuit board) shown in the illustrated example, and two layers in which the conductor layer (B) is provided only on one side of the electrical insulator layer (A). It may be a laminate (single-sided printed circuit board) or a multilayer printed circuit board in which a plurality of the two-layer laminates are laminated. The two-layer laminate or the like is used as a build-up layer on the surface of the base substrate. A multilayer printed circuit board (build-up board) in which a single layer or a plurality of layers are stacked may be used.

  An electric insulator layer containing a resin other than the fluorine-containing copolymer (F) may be used for the base substrate used for the build-up substrate. As the electrical insulator layer, a woven fabric of inorganic fibers such as glass fibers; a woven fabric of organic fibers such as polyester, polyamide, fluororesin, and cotton; An electrical insulator layer combined with a fluorocopolymer may be mentioned, and an electrical insulator layer formed by combining a fluororesin such as PTFE and a woven fabric such as glass fiber or silica fiber is preferable.

Examples of the method for producing a printed circuit board include a compression molding method (press molding method) and a laminate molding method. The conditions of the press molding method are as follows.
The press temperature is preferably 200 to 380 ° C, more preferably 250 to 360 ° C.
The press pressure is preferably 0.3 to 30 MPa, more preferably 0.5 to 20 MPa, and particularly preferably 1 to 15 MPa.
The pressing time is preferably 3 to 240 minutes, more preferably 5 to 120 minutes, and particularly preferably 10 to 80 minutes.
As a press plate used for press forming, a stainless steel plate is preferable.
Examples of a method for forming a wiring circuit composed of the conductor layer (B) include a method of etching the conductor layer (B), a method of plating the surface of the electrical insulator layer (A), and the like.

  The glass fiber reinforced composite material of the present invention described above has a low dielectric constant and dielectric loss tangent because it contains the fluorinated copolymer (F). Moreover, since a fluorine-containing copolymer (F) has a specific repeating unit in a specific ratio, adhesiveness with a metal is high. In addition, since the adhesiveness with the metal is high, it is not necessary to add inorganic fine particles, and as a result, the coefficient of thermal expansion is low and the mechanical strength is high while keeping the dielectric constant and dielectric loss tangent low.

  Moreover, in the manufacturing method of the glass fiber reinforced composite material of this invention demonstrated above, the method of compounding the film of a fluorine-containing copolymer (F), and the fabric of glass fiber (G) by the thermal lamination method. Therefore, it is not necessary to repeat the impregnation of the dispersion of the fluororesin into the glass fiber woven fabric a plurality of times as in the prior art, and the productivity is high. In addition, it is not necessary to treat the waste liquid of the dispersion.

  In the printed circuit board of the present invention described above, the glass fiber reinforced fiber of the present invention has a low dielectric constant and dielectric loss tangent, high adhesion to metal, low thermal expansion coefficient, and high mechanical strength. Since it has an electrical insulator layer (A) made of a composite material, the signal transmission speed is high, the transmission loss is low, the peeling of the plating in the conductor layer and the through hole is suppressed, the thermal expansion coefficient is low, and the mechanical strength Is expensive. In particular, the adhesion to the plating in the through hole is good, and the electrical reliability of the through hole is higher than that of a printed circuit board having an electrical insulator layer containing conventional PTFE.

  Further, in the printed circuit board of the present invention, if part or all of the glass fiber (G) is present at a depth of 1 to 40 μm from the surface of the electrical insulator layer (A), the heat resistance to the solder is sufficient. It can be expressed. Therefore, the width, length, shape and impedance of the wiring circuit can be maintained as designed values even after the solder reflow process, and the predetermined performance as a printed circuit board can be stably maintained over a long period of time.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
Examples 1 and 2 are examples, and example 3 is a comparative example.

(Rate of each repeating unit)
The ratio of each repeating unit in the fluorine-containing copolymer was determined from melt NMR analysis, fluorine content analysis, and infrared absorption spectrum analysis.

(Infrared absorption spectrum analysis)
The proportion of repeating units based on IAH or CAH in the fluorinated copolymer was determined by the following infrared absorption spectrum analysis.
The fluorine-containing copolymer was press-molded to obtain a 200 μm film. In the infrared absorption spectrum, the absorption peak of C═O stretching vibration in the repeating unit based on IAH or CAH in the fluorine-containing copolymer appears at 1870 cm ⁻¹ . The absorbance of the absorption peak was measured, and the ratio M (mol%) of repeating units based on IAH or CAH was determined from the following formula (II).
M = aL (II).
However, L shows the light absorbency in 1870 cm < ^-1 > and a shows a coefficient. a is a numerical value (0.87) determined using IAH as a model compound.

(Melting point)
The melting point of the fluorine-containing copolymer was measured by a method based on JIS K7122 using a DSC manufactured by Seiko Denshi.

(Melt viscosity)
The melt viscosity at the temperature of lamination of the fluorinated copolymer is measured with an orifice with an inner diameter of 1 mmφ and a length of 2 mm using a flow tester manufactured by Shimadzu Corporation under a pressure of 0.98 MPa and a temperature of thermal lamination. did.

(Dielectric constant and dielectric loss tangent)
The glass fiber reinforced composite material was cut into a size of 200 mm × 120 mm to prepare a test film. The test film was measured for dielectric constant and dielectric loss tangent at 1 GHz at 25 ° C. using a dielectric constant measuring apparatus (manufactured by Agilent, network analyzer 4291B and 16453A fixture).

(Coefficient of thermal expansion)
The thermal expansion coefficient of the glass fiber reinforced composite material was measured by raising the temperature from 100 ° C. to 200 ° C. at a rate of 10 ° C./min using a TMA device (manufactured by Seiko Denshi, TMA120C).

(Elastic modulus)
The elastic modulus of the glass fiber reinforced composite material was measured under conditions of 25 ° C. and 10 Hz using a DMA device (DMS200 manufactured by Seiko Electronics Co., Ltd.).

(Adhesion)
The printed circuit board was cut into a length of 150 mm and a width of 10 mm to prepare a test film. The electrical insulator layer (A) and the conductor layer (B) were peeled from the end in the length direction of the test film to a position of 50 mm. Subsequently, the position of 50 mm from the end in the length direction of the test film was set at the center, and a tensile tester was used to peel 180 degrees at a pulling speed of 50 mm, and the maximum load was defined as peel strength (N / 10 mm). It shows that it is excellent in adhesiveness, so that peeling strength is large.

(Heat-resistant)
The conductor layer (B) of the printed circuit board was removed by etching, and the electrical insulator layer (A) was cut into a size of 50 mm × 50 mm to prepare a test piece. The test piece was held in a pressure cooker tester (121 ° C., 0.22 MPa) for 1 hour, then immersed in 260 ° C. solder for 20 seconds, and the appearance was visually observed. A sample having no occurrence of measling and blistering was evaluated as ◯ (good), and a sample having measling or blistering was evaluated as x (defective).

(Transmission loss)
For measurement of transmission loss, a microstrip line with impedance Z = 50Ω was used. A microstrip line has a structure suitable for mounting surface-mounted components and is easy to manufacture, and is therefore widely used for measuring transmission loss. FIG. 4 is a cross-sectional view showing an example of a microstrip line. The microstrip line 30 includes one of an electrical insulator layer (A) 22 made of a glass fiber reinforced composite material 10 and an electrical insulator layer (A) 22. After etching the conductor layer (B) on the surface, the microstrip line 32 formed by copper plating and the conductor layer (B) on the other surface of the electrical insulator layer (A) 22 are formed. And a ground layer 34.

Both ends of the microstrip line 32 and the ground layer 34 were connected to a network analyzer (not shown), the amount of transmission with respect to the incident wave to the microstrip line 32 was measured, and the transmission loss at 5 GHz was obtained from the following formula (III). The measurement was performed 20 times, and an average value and a standard deviation were obtained.
Transmission loss (dB / mm) = | S21 | / L (III).
However, S21 shows the transmission amount (dB) in 5 GHz with respect to the incident wave to the microstrip line 32, L shows the line length L (mm) of the microstrip line 32.

[Example 1]
The polymerization tank with a stirrer (internal volume 94 L) was degassed and 80 of 1,3-dichloro-1,1,2,2,3-pentafluorohexane (Asahi Glass Co., Ltd., AK225cb; hereinafter referred to as AK225cb). 0.5 kg, 0.077 kg of methanol, and 6.8 kg of compound (1-2) were charged, the temperature in the polymerization tank was raised to 50 ° C., and TFE was charged until the pressure reached 0.38 MPa. As a polymerization initiator solution, 50 mL of an AK225cb solution of 0.25% by mass of di (perfluorobutyryl) peroxide was charged to initiate polymerization. During the polymerization, TFE was continuously charged so that the pressure was constant. As appropriate, the polymerization initiator solution was added to keep the TFE feed rate substantially constant. A total of 120 mL of the polymerization initiator solution was charged. Further, IAH in an amount corresponding to 0.5 mol% was continuously charged with respect to the total TFE (100 mol%) charged during the polymerization. Six hours after the start of polymerization, when 7.0 kg of TFE was charged, the inside of the polymerization tank was cooled to room temperature and unreacted TFE was released.

The slurry-like fluorine-containing copolymer was put into a granulation tank (internal volume 200 L) charged with 75 kg of water, and the temperature was raised to 105 ° C. with stirring to granulate while removing the solvent by distillation. The obtained granulated product was dried at 150 ° C. for 5 hours to obtain 7.5 kg of a fluorinated copolymer 1 granulated product.
The ratio of each repeating unit in the fluorinated copolymer 1 is as follows: repeating unit based on TFE / repeating unit based on compound (1-2) / repeating unit based on IAH = 97.7 / 2.0 / 0.3 (mol) %)Met. The melting point of the fluorinated copolymer 1 was 292 ° C., and the melt viscosity at 340 ° C. was 800 Pa · s.

The granulated product of the fluorinated copolymer 1 was extruded using a 30 mmφ single screw extruder having a 750 mm wide coat hanger die to obtain a film 1 having a thickness of 30 μm. The screw L / D ratio of the device was 24 and the screw CR was 3. The molding conditions were as follows.
Cylinder temperature: C1 = 300 ° C., C2 = 320 ° C., C3 = 340 ° C.,
Adapter temperature: 340 ° C
Head temperature: 340 ° C.
Die temperature: 340 ° C.
Screw rotation speed: 10rpm,
Take-up speed: 5 m / min.

Film 1 and glass cloth 1 (manufactured by Arisawa Manufacturing Co., Ltd., glass cloth 0634NS, unit area mass 48.5 g / m ² , porosity 4.5%) are used as film 1 / glass cloth 1 / film 1 / film 1 / glass. Cloth 1 / film 1 are laminated in order, and heat lamination is performed at a lamination temperature of 340 ° C. and a line speed of 0.2 m / min using a high-temperature laminator (manufactured by Hirano Giken), and a glass fiber reinforced composite material having a thickness of 168 μm 1 (hereinafter referred to as composite material 1) was obtained. The composite material 1 was evaluated for dielectric constant, dielectric loss tangent, thermal expansion coefficient, and elastic modulus. The results are shown in Table 1.

Composite material 1 and copper foil 1 (made by Fukuda Metal Foil Powder Co., Ltd., electrolytic copper foil CF-T4X-SVR-12) are laminated in the order of copper foil 1 / composite material 1 / copper foil 1 and vacuum pressed (Kitakawa Using a Seiki Co., Ltd.), vacuum pressing was performed for 5 minutes under conditions of a temperature of 340 ° C. and a pressure of 3.7 MPa to obtain a printed circuit board 1 having a thickness of 200 μm.
As a result of observing the cross section of the printed circuit board 1 with a microscope, it was confirmed that the glass cloth 1 was disposed at a depth of 22 μm from the surface of the electrical insulating layer (A) made of the composite material 1.
The printed circuit board 1 was evaluated for heat resistance, adhesion, and transmission loss. The results are shown in Table 1.

[Example 2]
The polymerization tank with a stirrer (internal volume 94 L) was degassed, and 71.3 kg of 1-hydrotridecafluorohexane (hereinafter referred to as HTH), 20.4 kg of AK225cb, and 562 g of compound (5-1) were added. First, the temperature in the polymerization tank was raised to 66 ° C., an initial monomer mixed gas of TFE / E = 84/16 (molar ratio) was introduced, and the pressure was increased to 1.5 MPa / G. As a polymerization initiator, 1 L of an HTH solution of 0.7% by mass of tert-butylperoxypivalate was charged to initiate polymerization. During the polymerization, a monomer mixed gas of TFE / E = 54.5 / 45.5 (molar ratio) was continuously charged so that the pressure was constant. Further, the amount of the compound (5-1) corresponding to 3.3 mol% and the amount of IAH corresponding to 0.8 mol% are continuously added to the total (100 mol%) of TFE and E charged during the polymerization. I was charged. 9.9 hours after the start of the polymerization, when 7.28 kg of the monomer mixed gas was charged, the inside of the polymerization tank was cooled to room temperature and the monomer mixed gas was released to normal pressure.

The slurry-like fluorine-containing copolymer was put into a granulating tank (internal volume 200 L) charged with 77 kg of water, and the temperature was raised to 105 ° C. with stirring to granulate while removing the solvent by distillation. The obtained granulated product was dried at 150 ° C. for 15 hours to obtain 6.9 kg of a granulated product of fluorinated copolymer 2.
The ratio of each repeating unit in the fluorinated copolymer 2 is as follows: repeating unit based on TFE / repeating unit based on compound (5-1) / repeating unit based on IAH / repeating unit based on E = 86.0 / 5.7 /0.8/70.4 (mol%). The melting point of the fluorinated copolymer 2 was 270 ° C., and the melt viscosity at 320 ° C. was 6800 Pa · s.

The granulated product of the fluorinated copolymer 2 was extruded using the apparatus of Example 1 to obtain a film 2 having a thickness of 30 μm. The molding conditions were as follows.
Cylinder temperature: C1 = 280 ° C., C2 = 300 ° C., C3 = 320 ° C.,
Adapter temperature: 320 ° C
Head temperature: 320 ° C.
Die temperature: 320 ° C
Screw rotation speed: 8rpm
Take-up speed: 4 m / min.

  Film 2 and glass cloth 1 are laminated in the order of film 2 / glass cloth 1 / film 2 / film 2 / glass cloth 1 / film 2 and the lamination temperature is 320 ° C. and the line speed is 0 using the high temperature laminator of Example 1. Thermal lamination was performed at 2 m / min to obtain a glass fiber reinforced composite material 2 (hereinafter referred to as composite material 2) having a thickness of 168 μm. The composite material 2 was evaluated for dielectric constant, dielectric loss tangent, thermal expansion coefficient, and elastic modulus. The results are shown in Table 1.

The composite material 2 and the copper foil 1 are laminated in the order of copper foil 1 / composite material 2 / copper foil 1, and vacuum-pressed for 5 minutes under the conditions of a temperature of 320 ° C. and a pressure of 3.7 MPa using the vacuum press of Example 1. A printed circuit board 2 having a thickness of 200 μm was obtained.
As a result of observing the cross section of the printed circuit board 2 with a microscope, it was confirmed that the glass cloth 1 was disposed at a depth of 22 μm from the surface of the electrical insulating layer (A) made of the composite material 2.
The printed circuit board 2 was evaluated for heat resistance, adhesion, and transmission loss. The results are shown in Table 1.

[Example 3]
E / TFE copolymer film (Asahi Glass Co., Aflex # 30N, melting point 270 ° C., thickness 30 μm, hereinafter referred to as film 3) and glass cloth 2 (Arisawa Manufacturing Co., Ltd.) having no repeating unit based on AM monomer Glass cloth 1080, unit area mass 48.5 g / m ² , porosity 30%.) In the order of film 3 / film 3 / glass cloth 2 / glass cloth 2 / film 3 / film 3. Using the high-temperature laminator of Example 1, thermal lamination was performed at a lamination temperature of 320 ° C. and a line speed of 0.2 m / min to obtain a glass fiber reinforced composite material 3 (hereinafter referred to as composite material 3) having a thickness of 168 μm. . The composite material 3 was evaluated for dielectric constant, dielectric loss tangent, thermal expansion coefficient, and elastic modulus. The results are shown in Table 1.

Composite material 3 and copper foil 2 (made by Fukuda Metal Foil Powder Industry Co., Ltd., electrolytic copper foil CF-T9FZ-HTE-18) were laminated in the order of copper foil 2 / composite material 3 / copper foil 2, and the vacuum of Example 1 Using a press, vacuum pressing was performed for 5 minutes under the conditions of a temperature of 320 ° C. and a pressure of 3.7 MPa to obtain a printed circuit board 3 having a thickness of 200 μm.
As a result of observing the cross section of the printed circuit board 3 with a microscope, it was confirmed that the glass cloth 2 was disposed at a depth of 52 μm from the surface of the electrical insulating layer (A) made of the composite material 3.
The printed circuit board 3 was evaluated for heat resistance, adhesion, and transmission loss. The results are shown in Table 1.

  In the evaluation of the heat resistance against the solder, measling occurred in the electrical insulating layer (A) of the printed circuit board 3. Further, the adhesion between the electrical insulating layer (A) and the conductor layer (B) of the printed circuit board 3 was insufficient. Furthermore, the transmission loss at 5 GHz of the printed circuit board 3 was insufficient and the variation was large.

  The glass fiber reinforced composite material and the printed circuit board of the present invention are substrates for electronic devices such as radars, network routers, backplanes and wireless infrastructures that require high frequency characteristics; chemical resistance and heat resistance are required. Various sensor boards for automobiles, boards for engine management sensors; build-up printed circuit boards, flexible printed circuit boards, ID tag boards; covers for heat fixing rolls of copying machines, cover materials for heat fixing belts, batteries, etc .; construction Tents used for roofing materials, etc .; various rolls and belts for industrial machines; used for resin-impregnated packing, sealing materials, spacers, gaskets, O-rings, etc.

It is sectional drawing which shows an example of the glass fiber reinforced composite material of this invention. It is sectional drawing which shows an example of the printed circuit board of this invention. It is sectional drawing which shows an example of a glass cloth. It is sectional drawing which shows the microstrip line used for the measurement of the transmission loss in an Example.

Explanation of symbols

10 Glass fiber reinforced composite material 12 Fluorine-containing copolymer (F)
14 Glass fiber (G)
20 Printed Circuit Board 22 Electrical Insulator Layer (A)
24 Conductor layer (B)

Claims (7)

The following fluorine-containing copolymer (F) Glass fibers (G) and consisting Ruga Las fiber-reinforced composite material to contain electrical insulator layer (A), the electrical insulator layer (A) in direct contact with the conductor A printed circuit board having a layer (B) .
Repeating units (a) based on tetrafluoroethylene and / or chlorotrifluoroethylene;
A repeating unit (b) based on a fluorine monomer (excluding tetrafluoroethylene and chlorotrifluoroethylene);
Having a repeating unit (c) based on a monomer having an acid anhydride residue and a polymerizable unsaturated bond,
Of the total 100 mol% of the repeating units (a) to (c), the repeating unit (a) is 50 to 99.89 mol%, and the repeating unit (b) is 0.1 to 49.99 mol. % Of the fluorine-containing copolymer (F), wherein the repeating unit (c) is 0.01 to 5 mol%. The fluorine-containing copolymer (F) further has a repeating unit (d) based on a non-fluorine monomer (excluding a monomer having an acid anhydride residue and a polymerizable unsaturated bond),
The molar ratio (((a) + (b) + (c)) / (d)) of the total of the repeating units (a) to (c) and the repeating unit (d) is 100/5 to 100 / The printed circuit board of claim 1, wherein the printed circuit board is 90. The monomer having an acid anhydride residue and a polymerizable unsaturated bond is at least one selected from the group consisting of itaconic anhydride, citraconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride. Item 3. The printed circuit board according to Item 1 or 2. The printed circuit board according to any one of claims 1 to 3 , wherein a part or all of the glass fiber (G) is present at a depth of 1 to 40 µm from the surface of the electrical insulator layer (A). The said glass fiber (G) is a glass cloth comprised from a warp and a weft, and the porosity calculated | required by the following Formula (I) is 0 to 25%, It is any one of Claims 1-4. Printed circuit board.
Porosity = {(t ₁ −s ₁ ) × (t ₂ −s ₂ )} / (t ₁ × t ₂ ) × 100 (I).
Here, s ₁ is the average value (μm) of the cross-sectional width of the warp yarn bundle, t ₁ is the average value (μm) of the warp yarn bundle interval, and s ₂ is the weft yarn bundle. It is an average value (μm) of the cross-sectional width, and t ₂ is an average value (μm) of the yarn bundle interval of the weft yarn. It is a manufacturing method of the printed circuit board according to any one of claims 1 to 5 ,
A method for producing a printed circuit board, wherein the glass fiber reinforced composite material is obtained by combining a film of a fluorinated copolymer (F) and a glass fiber (G) fabric by a thermal lamination method. The manufacturing method of the printed circuit board of Claim 6 whose melt viscosity of the said fluorine-containing copolymer (F) at the time of thermal lamination is 100-10000 Pa.s.

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