JP2003211616A - Ptfe resin laminated sheet and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a PTFE resin laminated sheet modified so as to be made high in elastic modulus and low in the coefficient of thermal expansion. <P>SOLUTION: A laminated sheet, obtained by laminating a plurality of PTFE resin prepregs to heat them under pressure, is irradiated with radiation and subsequently subjected to annealing treatment. By this method, the PTFE resin laminated sheet is increased in elastic modulus, reduced in the coefficient of thermal expansion and improved in handleability or drilling precessability in a processing process and through-hole reliability. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a high elastic modulus,
PTF with a low coefficient of thermal expansion and suitable for high frequency equipment
The present invention relates to a method for manufacturing an E resin laminated board.

[0002]

2. Description of the Related Art Fluororesin is an industrial polymer material having a very specific property among polymer compounds, and various applied products are provided on the market.

In particular, a typical PTFE (polytetrafluoroethylene) resin, which accounts for 70% of the demand for fluororesin, has characteristics not found in other engineering plastics, such as a melting point of 327 ° C. and a dielectric constant of 2.1 (1 MHz). There is. Its specific characteristics are excellent in heat resistance, chemical resistance, solvent resistance, moisture resistance, low dielectric properties, insulation, abrasion resistance, lubricity, non-adhesiveness, water repellency, weather resistance, purity, etc. Are listed.

Various PTFE resin products that make use of these characteristics are diversified, and fluororesin parts such as films, sheets, laminates, laminates with metal foil, and pipes are used in many industrial fields. No other material is changing.

In particular, in the field of laminated plates used for high-frequency equipment, copper-clad PTFE resin laminated plates, which are excellent in terms of dielectric properties, are mainly used, and their demand will increase in the advanced information and communication society in the future. Is expected.

However, the fluororesin is essentially composed of a flexible polymer chain and has a drawback of low elastic modulus. For this reason, for example, a thin laminated plate is not stiff, and warps or warps occur, which makes it difficult to handle in a processing step.

Further, since the caulking does not work and it is necessary to caulking using a special tool / part, the manufacturing process becomes complicated and there are many problems in processing.

On the other hand, since it is thermoplastic, there is a problem that the coefficient of thermal expansion of the fluororesin itself is large, the through-hole reliability is low, and it cannot be used in applications where heat history is required.

Several measures have been published for these problems, and for example, a method of forming a compound by adding a filler such as an inorganic filler to reinforce it has been proposed. In addition to the effects of deterioration and increase of impurities, the cost also rises and sufficient practical performance cannot be obtained.

Further, in order to improve the elastic modulus of the fluororesin itself, the PTFE resin is irradiated with an electron beam at a high temperature just above 327 ° C. in the absence of oxygen to cross-link the PTFE molecules with a covalent bond to obtain strength and elastic modulus. However, oxygen-free high temperature conditions are disadvantageous in a normal laminated plate manufacturing process.

Therefore, P used in high-frequency equipment and the like
The TFE resin laminated plate generally has the drawbacks of low elastic modulus and high thermal expansion coefficient.

[0012]

Therefore, the present invention is
Suitable for applications such as high-frequency equipment with high elastic modulus, low thermal expansion coefficient, improved processability and through-hole reliability while maintaining excellent electrical characteristics such as low dielectric constant and low dielectric loss tangent. The present invention aims to provide a method for producing a PTFE resin laminated plate which can be manufactured.

[0013]

As a result of various studies to solve the above-mentioned problems, the present invention has been made in consideration of a plurality of PTs.
A laminated plate obtained by laminating FE resin prepreg and heating / pressurizing it is irradiated with radiation and then annealed to increase the elastic modulus of the PTFE resin laminated plate and reduce the coefficient of thermal expansion. It has been found that it is possible to improve the handling property, drilling processability, and through hole reliability.

That is, in the amorphous PTFE molecular chain, thermal motion is activated by annealing, and if a crystallized region is present in the vicinity, a part of the crystallized secondary crystallizes. In addition, P in an amorphous region partially cut by irradiation with an appropriate amount of electron beam or γ-ray
Since the TFE molecular chain easily moves, secondary crystallization can be performed even at room temperature if there is a crystallization region in the vicinity.

As described above, the thermal recrystallization of the PTFE molecules in the crystalline / amorphous interface region can be promoted by the combined use of the annealing and the radiation irradiation.

By the progress of secondary crystallization, PTFE
The crystallinity of the resin is increased, and the intermolecular force is increased as a whole. As a result, it is considered that molecular motion due to external stress or heat is suppressed, leading to an increase in elastic modulus and a decrease in thermal expansion coefficient.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The PTFE resin prepreg used in the present invention uses a glass base material made of glass fiber manufactured by a usual method. Although the glass fiber is not limited, it is preferable to use E glass in consideration of electrical characteristics, processability, and cost. Apart from the price, Q, D, and
If glass fibers such as T and NE are used, the dielectric characteristics can be further improved.

Such glass fibers are used in the form of woven cloth or non-woven cloth. Woven fabrics include plain weave, twill weave, and satin weave.

The PTFE resin is usually supplied as a dispersion liquid called a dispersion, and the glass cloth base material wound in a roll shape is continuously fed out and impregnated therewith,
The PTFE resin is fixed to the glass cloth substrate in the subsequent drying and firing steps. This impregnation step can be repeated a plurality of times as necessary to obtain a uniform and even PTFE resin prepreg.

Next, the obtained PTFE resin prepreg is cut into a predetermined size and, if necessary, one or a plurality of layers are laminated, and then these laminated bodies are generally vacuumed to 3
Press at a temperature of about 00 ° C under a predetermined pressure for a predetermined time, and press P
Obtain a TFE resin laminate. In the case of printed wiring board, after stacking copper foil on the outer layer of PTFE resin prepreg,
Similarly, heat and pressure are applied to obtain a copper clad laminate.

In these steps, the thickness of the laminated plate is not particularly limited, and the copper foil may be used on only one side or may not be used.

Although the above-mentioned batch method is generally used for the press, there is no problem even if it is a method of continuously laminating copper foil using rolls.

Further, even if the multilayer board obtained by etching the surface of the obtained copper clad laminate to a predetermined circuit pattern, punching it, etc., and then again pressing it with PTFE resin prepreg a predetermined number of times, No problem.

In the present invention, the P produced by the above method is used.
Irradiate the TFE resin laminate with a predetermined dose of radiation at room temperature and pressure. As the radiation, α rays, β rays, γ rays, electron rays, X rays and the like can be used. However, α rays and β rays preferably use γ rays and electron rays because they have a low see-through power and are poor in efficiency.
Although γ rays were used in the present invention, it is commercially more preferable to use an electron beam which does not require a radiation source and whose dose can be controlled relatively easily.

Absorbed dose of 1 to 500 kG as γ-ray irradiation dose
The range of y can be used, but from the viewpoint of efficiency, 10 kGy or more is suitable, and when it exceeds 100 kGy, the physical properties of the PTFE resin are deteriorated, so 10 to 100 kGy is preferable.

Irradiation can be performed with a single laminated plate or a plurality of laminated plates, and the optimum conditions can be appropriately selected.

Another feature of the present invention is to subject the PTFE resin laminated plate to an annealing treatment. Specifically, PT
The FE resin laminated plate is put in a generally used heating furnace under the conditions of air and normal pressure for annealing. The combination of temperature and time is not particularly limited, but considering efficiency, it is preferably 250 to 320 ° C. and 1 to 5 hours.

The intended effect can be obtained by using radiation irradiation and annealing in combination.

As described above, the modified PTFE resin laminate is obtained by using the apparatus normally used for producing a PTFE resin laminate with the modification process of increasing the elastic modulus and decreasing the thermal expansion coefficient, which is the object of the present invention. The plate can be easily manufactured.

[0030]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited thereto.

Example PTFE resin dispersion (Polyflon: made by Daikin) was used as a plain woven glass cloth (WE-0) having a thickness of 0.05 mm.
5: Nitto Boseki) was impregnated, dried and fired several times to prepare a prepreg. A stack of 19 sheets of this prepreg sheet cut to a predetermined size is heated and pressed at a temperature of about 300 ° C. under vacuum to 1.6 mm.
A thick PTFE resin laminate was obtained. 50kG on this laminate
A γ-ray dose corresponding to y was irradiated and an annealing treatment was performed at 300 ° C. for 2 hours.

Comparative Example 1 PTFE resin dispersion (Polyflon: made by Daikin) was used as a plain weave glass cloth (WE-0) having a thickness of 0.05 mm.
5: Nitto Boseki) was impregnated, dried and fired several times to prepare a prepreg. A stack of 19 sheets of this prepreg sheet cut to a predetermined size is heated and pressed at a temperature of about 300 ° C. under vacuum to 1.6 mm.
A thick PTFE resin laminate was obtained.

Comparative Example 2 Comparative Example 1 except that a γ dose equivalent to 50 kGy was applied.
I went the same way.

Comparative Example 3 The procedure of Comparative Example 1 was repeated except that the annealing treatment was carried out at 300 ° C. for 2 hours. The flexural modulus and the coefficient of thermal expansion of the samples obtained in Examples and Comparative Examples were measured. The results are shown in Table 1.

[0035]

[Table 1]

Test method Flexural modulus: The test was carried out according to JIS standard K69115.17 (General test method for thermosetting plastics). Coefficient of thermal expansion: 30 ° C to 2 using RMA's TMA test report
The expansion in the thickness direction was measured between 60 ° C., and it was shown as the rate of change relative to the original thickness.

[0037]

As described above, according to the present invention, PT
It is possible to increase the flexural modulus and reduce the coefficient of thermal expansion by irradiating the FE resin laminated plate with radiation and annealing it. As a result, the PTFE resin laminated plate conventionally used for high-frequency equipment can be manufactured. It is possible to improve the handling property during the working process, the drill workability, and the through hole reliability, which are problems.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/00 H05K 3/00 R (72) Inventor Takashi Kobiya 4-Minamitsukaguchi-cho, Amagasaki-shi, Hyogo 2-37 Risho Industry Co., Ltd. Development Headquarters (72) Inventor Seiichi Nishimoto 1-17-20 Suzaku, Nara City, Nara Prefecture F-17 (Reference) 4F100 AB17C AB33C AK42A AK42B BA03 BA07 BA10A BA10C DH01A DH01B EJ172 EJ413 EJ422 EJ523 EJ822 GB41

Claims (4)

[Claims] 1. A laminated plate obtained by laminating a plurality of PTFE resin prepregs, heating and pressurizing them, and irradiating with radiation.
Then, a method of manufacturing a PTFE resin laminate, which is subjected to an annealing treatment. 2. The method for producing a PTFE resin laminate according to claim 1, wherein a copper foil is laminated on the outer layers of a plurality of PTFE resin prepregs. 3. The method for producing a PTFE resin laminate according to claim 1, wherein gamma rays are used as the radiation. 4. A PTFE resin laminate obtained by the manufacturing method according to claim 1.