JPH07272534A - Manufacture of compound dielectric - Google Patents

Abstract

PURPOSE:To provide such a manufacture for compound dielectric material having high relative permittivity that eliminates a problem of largely deteriorating electric characteristics (especially, in dielectric tangent) after moisture absorption treatment. CONSTITUTION:Prepreg which is obtained by repeatedly impregnating and drying fluorocarbon resin dispersion of 20 or more in relative permittivity, is laminated on prepreg which is obtained by impregnating and drying dispersion of FEP and/or PFA formed by adding nonorganic powder body of 20 or more in relative permittivity to glass fiber base material so as to be formed. Fluorocarbon resin films including nonorganic powder of 20 or more in relative permittivity are arranged above/under prepreg which is obtained by impregnating and drying dispersion of FEP and/or PFA formed by adding nonorganic powder of 20 or more in relative permittivity to glass fiber base material so as to be laminatedly formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a composite dielectric used in electronic parts such as printed circuit boards.

[0002]

2. Description of the Related Art In the advanced information age, information transmission tends to be faster and higher in frequency. And mobile radio such as car telephone and personal radio, satellite broadcasting, satellite communication, C
In fields such as ATV, miniaturization of devices is being promoted, and accordingly, miniaturization of microwave circuit elements such as dielectric resonators is strongly desired.

The size of the microwave circuit element is based on the wavelength of the electromagnetic wave used. The wavelength λ of the electromagnetic wave propagating through the dielectric having the relative permittivity ε _r is λ = λ ₀ / (ε _r ) ^0.5 when the propagation wavelength in vacuum is λ ₀ . Therefore, when the microwave circuit element is formed on the printed circuit board, the higher the relative dielectric constant of the board used, the smaller the circuit element. Moreover, when the relative permittivity of the substrate is high, electromagnetic energy is concentrated in the substrate, which is convenient because there is little electromagnetic wave leakage.

As a printed circuit board having a high relative dielectric constant,
For example, as disclosed in JP-A-3-5140,
A circuit board made of a fluororesin and a glass fiber base material to which an inorganic powder (barium titanate or the like) having a high relative dielectric constant is added is known. Such a circuit board is attracting attention because it is superior to a ceramic-based board made of alumina or the like in that it has a large area and is excellent in workability such as cutting and hole processing. As the fluororesin used for the above-mentioned circuit board, high-frequency characteristics are good, and the water absorption rate is also small.
FE) is widely used, but it has a drawback that it has a high melt viscosity (10 ¹⁰ to 10 ¹¹ poise at 380 ° C.). Therefore, even if it is heated above the melting point of PTFE and pressure is applied to it, the PTFE to which the inorganic powder is added has poor fluidity, and voids are likely to remain between the fibers of the glass reinforcing material. However, there was a problem that the value changed (deteriorated) significantly. In particular, there is a problem that the dielectric loss tangent after the moisture absorption treatment is greatly deteriorated. In order to solve such a problem, Japanese Patent Laid-Open No. 4-125140 discloses that a fibrous base material is first impregnated with a fibrous base material, and then a finely powdered inorganic filler is further impregnated with the fibrous base material to absorb moisture. A method of improving insulation resistance after treatment is disclosed.

[0005]

However, in the above-described method of first impregnating the glass fiber base material with the fluororesin and then impregnating the fluororesin with the addition of the inorganic filler fine powder, the impregnation of the fluororesin is first performed. Since no inorganic powder having a high relative dielectric constant is added to the resin, there is a problem that the relative dielectric constant of the finally obtained substrate cannot be increased so much.

Therefore, the present invention does not have a problem that the electrical characteristics (especially dielectric loss tangent) after the moisture absorption treatment are significantly deteriorated,
Moreover, it is an object of the present invention to provide a method for producing a composite dielectric, which can obtain a composite dielectric having a high relative dielectric constant.

[0007]

According to a first aspect of the present invention, there is provided a method for producing a composite dielectric, which comprises impregnating a glass fiber base material with a fluororesin dispersion containing inorganic powder having a relative dielectric constant of 20 or more, A method for producing a composite dielectric, in which a prepreg obtained by drying is further impregnated with a fluororesin dispersion obtained by adding an inorganic powder having a relative dielectric constant of 20 or more, and the prepreg obtained by drying is laminated and molded. The fluororesin used in the first impregnation step is characterized by being a tetrafluoroethylene-6-fluoropropylene copolymer and / or a tetrafluoroethylene-perfluorovinyl ether copolymer.

According to a second aspect of the present invention, there is provided a method for producing a composite dielectric material, wherein a tetrafluoroethylene-6-fluorinated propylene copolymer is obtained by adding an inorganic powder having a relative dielectric constant of 20 or more to a glass fiber base material. Impregnated with a dispersion of polymer and / or tetrafluoroethylene-perfluorovinyl ether copolymer,
The relative permittivity above and below the prepreg obtained by drying is 20.
It is characterized in that the fluororesin film containing the inorganic powder as described above is arranged and laminated.

The present invention will be described in detail below. The fluororesin used in the present invention will be described. In addition to PTFE, which has been widely used for fluororesin, tetrafluoroethylene-6-fluoropropylene copolymer (hereinafter abbreviated as FEP)
And tetrafluoroethylene-perfluorovinyl ether copolymer (hereinafter abbreviated as PFA), the dielectric properties of FEP and PFA are not so different from PTFE, and the melt viscosity is 380.
It has a low property of about 10 ⁴ poise at ° C. Therefore, when the glass fiber base material is impregnated with FEP or PFA, the voids between the fibers of the glass fiber base material are easily filled with FEP or PFA when heated and pressed. It is characterized in that (especially dielectric loss tangent) does not change significantly. Therefore, in the present invention, FEP and / or PFA is used as the fluororesin in the first impregnation step of the glass fiber base material.

Further, in the method for producing a composite dielectric according to claim 1, after the first impregnation step, a fluororesin dispersion containing an inorganic powder having a relative dielectric constant of 20 or more is repeatedly impregnated. , Dried to obtain a prepreg. By repeating impregnation and drying in this way, a prepreg having a desired fluororesin content can be obtained. The fluororesin used in the second and subsequent impregnation steps is not limited to FEP and PFA, and other fluororesins such as PTFE can be used. In particular, when PTFE is used in the second and subsequent impregnation steps, a composite dielectric having excellent heat resistance and low water absorption is obtained, and since FEP and / or PFA are used in the first impregnation step. The voids between the fibers of the glass fiber base material are FEP and PF.
Since it is filled with A, it is desirable to obtain a composite dielectric whose electric characteristics (especially dielectric loss tangent) after moisture absorption treatment do not change significantly.

Further, in the method for producing a composite dielectric according to claim 2, a glass fiber base material is impregnated with a dispersion of FEP and / or PFA in which an inorganic powder having a relative dielectric constant of 20 or more is impregnated and dried. A fluororesin film containing an inorganic powder having a relative dielectric constant of 20 or more is arranged on the upper and lower sides of the prepreg thus obtained, and laminated and molded to produce a substrate having a desired fluororesin content. The fluororesin used for this fluororesin film is not limited to FEP and PFA, and other fluororesins such as PTFE can be used. Further, the prepreg used in the method for producing a composite dielectric according to claim 2 only needs to use FEP and / or PFA as the fluororesin in the first impregnation step, and was obtained by repeating impregnation and drying. It may be a prepreg.

The glass fiber base material used in the present invention includes glass cloth, glass non-woven fabric and the like, and E glass (ε _r = 6.0 to 6.8) and the like can be used as the material of the glass. It is preferable to use a material having a dielectric constant of 9.0 or more in order to increase the relative dielectric constant of the composite dielectric.

The inorganic powder having a relative permittivity of 20 or more used in the present invention preferably has an average particle size of 0.3 to 10 μm (more preferably 1 to 5 μm), and the types thereof have a relative permittivity. There is no particular limitation as long as it is 20 or more.
Examples of the inorganic powder having a relative dielectric constant of 20 or more that can be used in the present invention include titanium oxide (TiO ₂ etc.), barium titanate (BaTi _0.7 Zr _0.3 O ₃ etc.), strontium titanate (SrTiO ₃ ), PbTi _0.5 Zr _0.5 O
Titanium-based inorganic powder or Pb containing titanium element such as ₃ type
(Mg _2/3 Nb _2/3) O ₃ system, Ba (Sn _x Mg _y Ta
_Examples thereof include powders having a perovskite type crystal structure (or a complex perovskite type crystal structure) such as _z ) O ₃ type and Ba (Zr _x Zn _y Ta _z ) O ₃ type. (Note that
x, y, and z represent positive numbers such that x + y + z = 1. The shape of this inorganic powder is not particularly limited, and for example, spherical shapes and various shapes of block pieces can be used.

Further, when the surface of the glass fiber base material and the inorganic powder having a relative dielectric constant of 20 or more used in the present invention is surface-treated with a coupling agent such as phenylsilane, a moisture absorption treatment is performed. This is preferable because it provides a composite dielectric with a small change in electrical characteristics (particularly dielectric loss tangent).

[0015]

By using FEP and / or PFA as the fluororesin in the first impregnation step, the melt viscosity of the fluororesin filling the voids between the fibers of the glass fiber base material can be changed to PTFE.
Acts to make it lower than.

The use of a fluororesin dispersion containing an inorganic powder having a relative dielectric constant of 20 or more in the first impregnation step serves to increase the relative dielectric constant of the composite dielectric.

[0017]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples.

(Example 1) Titanium oxide having a relative dielectric constant of about 100 (average particle size 1 μm, manufactured by Fuji Titanium Industry Co., Ltd .: TR
-840) 1 part of phenylsilane coupling agent (TSL8173 manufactured by Toshiba Silicone Co., Ltd.) to 99 parts by weight.
The inorganic powder was obtained by dry-type surface treatment using parts by weight. This inorganic powder was added to FEP dispersion (manufactured by Daikin Industries, Ltd .: ND-1) so that the ratio of the inorganic powder was 35% by volume to prepare an inorganic powder additive liquid. This liquid is called the first liquid.

A plain woven glass cloth (style 216) made of E glass was subjected to a surface treatment by a wet treatment method using a phenylsilane coupling agent (TSL8173 manufactured by Toshiba Silicone Co., Ltd.). The obtained glass cloth was impregnated with the above-mentioned first liquid, dried at 370 ° C., and baked to obtain a prepreg. In the obtained prepreg, the ratio of the total amount of the inorganic powder and the resin to the prepreg is 60.
It was weight% (58 volume%).

Next, the above-mentioned surface-treated inorganic powder was treated with PTFE dispersion (D-
Inorganic powder was added to 2) so that the ratio was 35% by volume to prepare an inorganic powder additive liquid. This liquid is called the second liquid.

In addition to the prepreg obtained above, a second
The liquid was impregnated, dried at 370 ° C., and baked to obtain a prepreg. In the obtained prepreg, the proportion of the total amount of the inorganic powder and the resin in the prepreg was 72% by weight (70
% By volume). Four prepregs thus obtained were stacked, copper foils (thickness 18 μm) were placed on the top and bottom of the prepregs, and pressure molding was performed at a temperature of 360 ° C. and a pressure of 30 kg / cm ² for 60 minutes to obtain a double-sided copper-clad laminate (Composite dielectric) was prepared.

Example 2 The same procedure as in Example 1 was repeated except that PFA dispersion (AD-2 manufactured by Daikin Industries, Ltd.) was used instead of the FEP dispersion used in the preparation of the first liquid of Example 1. To prepare a double-sided copper-clad laminate (composite dielectric).

(Example 3) Instead of the FEP dispersion used in the preparation of the first liquid of Example 1, an FEP dispersion (ND-1 manufactured by Daikin Industries, Ltd.) and a PFA dispersion (AD-manufactured by Daikin Industries: AD-) were used. A double-sided copper-clad laminate (composite dielectric) was produced in the same manner as in Example 1 except that the fluororesin dispersion obtained by mixing 2) in a weight ratio of 1: 1 was used.

(Embodiment 4) In the same manner as in Embodiment 1, the first
A liquid was prepared, and then glass cloth was impregnated with the first liquid, dried and fired to obtain a prepreg. In the obtained prepreg, the proportion of the total amount of the inorganic powder and the resin in the prepreg was 60% by weight (58% by volume) as in the case of the prepreg obtained after the first impregnation and drying in Example 1. Met.

Separately from the above prepreg, a fluororesin film containing an inorganic powder having a relative dielectric constant of 20 or more was prepared as follows.

25 parts by weight of the above-mentioned surface-treated inorganic powder was mixed with 75 parts by weight of PTFE dispersion (D-2 manufactured by Daikin Industries, Ltd.) and coagulated and separated. The obtained PTFE containing inorganic powder was used, with an outer diameter of 100 mm and a height of 1
Pressure molded into a 00 mm cylinder, then 60 at 360 ° C
Bake for minutes. A film having a thickness of 50 μm was cut out from the obtained cylindrical molded product to obtain a fluororesin film containing inorganic powder.

Four prepregs obtained above and inorganic powder
Using five fluororesin films containing
Fluororesin film containing inorganic powder is placed above and below
Fluorine resin surface layer by placing one sheet and stacking
A film that consists of a fluororesin film and a prepreg
It was a laminated product that was alternately laminated. And this stack
Copper foil (18 μm thick) is placed on the top and bottom of the product, and the temperature is 360
℃, pressure 30kg / cm ²Press molding for 60 minutes at
A copper-clad laminate (composite dielectric) was produced.

(Example 5) In the same manner as in Example 1, glass cloth was impregnated with the first liquid, dried and fired to obtain a prepreg. The obtained prepreg was further impregnated with the second liquid, and 370 It was dried at ℃ and baked to obtain a prepreg. In the obtained prepreg, the proportion of the total amount of the inorganic powder and the resin in the prepreg is the same as in Example 1, 72
It was% by weight (70% by volume).

Separately from the above prepreg, a fluororesin film containing an inorganic powder having a relative dielectric constant of 20 or more was prepared in the same manner as in Example 4.

Four prepregs obtained above and inorganic powder
Using five fluororesin films containing
Fluororesin film containing inorganic powder is placed above and below
Fluorine resin surface layer by placing one sheet and stacking
A film that consists of a fluororesin film and a prepreg
It was a laminated product that was alternately laminated. And this stack
Copper foil (18 μm thick) is placed on the top and bottom of the product, and the temperature is 360
℃, pressure 30kg / cm ²Press molding for 60 minutes at
A copper-clad laminate (composite dielectric) was produced.

(Comparative Example 1) A plain weave glass cloth (style 216) made of E glass was used, and a phenylsilane coupling agent (TSL8173 manufactured by Toshiba Silicone Co.)
Was subjected to a surface treatment by a wet treatment method in the same manner as in Example 1. The obtained glass cloth was impregnated with FEP dispersion (ND-1 manufactured by Daikin Industries, Ltd.) to which no inorganic powder was added, dried at 370 ° C., and baked to obtain a prepreg. In the obtained prepreg, the proportion of the resin in the prepreg is 53% by weight (58% by volume).
Met.

Next, four prepregs obtained as described above are stacked, copper foil (thickness 18 μm) is further arranged on the upper and lower sides,
A double-sided copper-clad laminate (composite dielectric) was produced by pressure molding at a temperature of 360 ° C. and a pressure of 30 kg / cm ² for 60 minutes.

(Comparative Example 2) Instead of the first liquid in Example 1, the second liquid in Example 1 (PTF to which inorganic powder was added) was used.
E-dispersion) was used for the first impregnation of the glass cloth.
In the same manner as above, a prepreg and a double-sided copper-clad laminate (composite dielectric) were prepared.

As described above, the relative dielectric constants before and after the PCT treatment (moisture absorption treatment) at 135 ° C., 3 atm (vapor pressure) and 2 hours for each double-sided copper-clad laminate obtained in the examples and comparative examples The dielectric loss tangent was measured, and the obtained results are shown in Tables 1 and 2. The relative permittivity and the dielectric loss tangent were measured at measurement frequencies f of 1 KHz and 3 GHz.

[0035]

[Table 1]

[0036]

[Table 2]

As can be seen from Tables 1 and 2, the copper clad laminates of Examples are stable with much less change in dielectric loss tangent before and after PCT treatment (moisture absorption treatment) than those of Comparative Example 2. It was also confirmed that the relative permittivity was higher than that of Comparative Example 1.

[0038]

EFFECTS OF THE INVENTION According to the method for producing a composite dielectric of the present invention, it is possible to produce a composite dielectric having a high relative permittivity without the problem that the dielectric loss tangent after moisture absorption treatment is significantly deteriorated. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H05K 1/03 K 7011-4E // C08L 27:18 (72) Inventor Kiyoshiro Yamakawa Kadoma City, Osaka Prefecture 1048, Kadoma, Matsushita Electric Works Co., Ltd.

Claims (2)

[Claims] 1. A prepreg obtained by impregnating a fluororesin dispersion obtained by adding an inorganic powder having a relative dielectric constant of 20 or more to a glass fiber base material and drying the prepreg, and further, an inorganic powder having a relative dielectric constant of 20 or more. In a method for producing a composite dielectric body, in which a prepreg obtained by repeatedly impregnating and drying a fluororesin dispersion containing a body is molded, wherein the fluororesin used in the first impregnation step is tetrafluoroethylene-6. A method for producing a composite dielectric, which is a fluorinated propylene copolymer and / or a tetrafluoroethylene-perfluorovinyl ether copolymer. 2. A tetrafluoroethylene-6-fluoropropylene copolymer and / or tetrafluoroethylene-perfluorovinyl ether copolymer obtained by adding an inorganic powder having a relative dielectric constant of 20 or more to a glass fiber base material. A prepreg obtained by impregnating and drying a coalesced dispersion, and a fluororesin film containing an inorganic powder having a relative dielectric constant of 20 or more are arranged on the upper and lower sides of the prepreg to laminate-mold the composite resin. Production method.