JPH03133194A - Sheet for printing wiring board - Google Patents

Abstract

PURPOSE:To obtain a sheet for a printed wiring board excellent in resistance to heat and size stability, by impregnating a sheet with heat resistant resin and curing it, which sheet contains microfibrillated material composed of aromatic polyamide short fibers having aromatic group in main chain and aromatic polyamid, and is subjected to paper making. CONSTITUTION:A sheet contains the following as inevitable components; microfibrillated material composed of aromatic polyamide short fibers having aromatic group in main chain, and aromatic polyamide. Said sheet is impregnat ed with heat resistant resin. As the heat resistant resin for impregnation, the following are quoted; thermosetting polyester amide resin, epoxy resin, phenol resin, polyimide resin, etc. One or more kinds of the above thermosetting resin are mixed and used. Thereby a sheet for a printed wiring board excellent in resistance to heat and size stability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a printed circuit board sheet having excellent electrical properties, heat resistance, and dimensional stability.

[Prior Art] A printed wiring board generally consists of a metal foil such as copper foil laminated on an electrically insulating sheet with or without a heat-resistant adhesive, and a predetermined wiring pattern is formed on the metal foil. obtained by forming. The insulating sheets used for this are required to have excellent properties such as heat resistance and dimensional stability. Mixtures of heat-resistant synthetic pulp and heat-resistant synthetic fibers or glass cloth or glass paper impregnated with heat-resistant resin and cured are known, and these are selected and used according to the required performance and cost. .

[Problems to be Solved by the Present Invention] However, although polyimide films have good heat resistance, they have the disadvantages of poor moisture resistance and dimensional stability, and are expensive.

Furthermore, in dry or wet papermaking, a binder is required to obtain a thin sheet with excellent strength that can withstand the resin impregnation process. Even if the main fiber has excellent heat resistance, the binder has the disadvantage of poor heat resistance.Also, in order to obtain strength that does not interfere with the resin impregnation process, a large amount of binder is required, and the resin The disadvantage is that the content is reduced.

Further, although glass cloth and glass paper have excellent resin impregnation properties, they have the disadvantage that the dimensional stability of the resin cured sheet is poor.

As heat-resistant synthetic fibers, aromatic polyamide short fibers, especially para-based short fibers, have excellent heat resistance and dimensional stability, and sheets mainly made of these fibers have been proposed. Those using low-oriented polyester staple fibers as a binder for the fibers (JP-A-62-274689, JP-A-62-26)
No. 26), microfibrillated thermoplastic polymer and aramid pulp (fibrillated material obtained by grinding aramid fibers or fibrids) (Japanese Unexamined Patent Publication No. 63-35900), aramid fibrous material A product using a fibrous binder made of a binder (pulp-like aromatic polyamide) and a thermoplastic heat-resistant polymer (Japanese Patent Laid-Open No. 61-17
No. 0089, Japanese Unexamined Patent Publication No. 60-260626) are disclosed.

Compared to aromatic polyamides, polyesters are inferior in heat resistance and dimensional stability, and thermoplastic polymers are also inferior in heat resistance and dimensional stability, making them undesirable.

In addition, a method in which fibrids of meta-aromatic polyamide are used as short fibers and/or fibrids of para-aromatic polyamide has been disclosed (Japanese Patent Application Laid-open No. 6O-207216), but compared to para-aromatic polyamide, , meta-aromatic polyamide, which is inferior in heat resistance and dimensional stability, is used, which is not preferable.

The present invention solves the above-mentioned conventional problems, and aims to provide a printed wiring board sheet having excellent electrical properties, heat resistance, and dimensional stability.

[Means for Solving the Problems] The present inventor conducted extensive research to solve the above problems. As a result, by using microfibrillated aromatic polyamide as a binder for aromatic polyamide short fibers having aromatic groups in the main chain, the thickness is uniform, the heat-resistant resin is uniformly impregnated, and the heat resistance and size are improved. It was discovered that a sheet for printed wiring boards with excellent stability could be obtained, and the present invention was completed. Furthermore, it has been found that a similar effect can be obtained by blending an aromatic polyamide pulp in combination with the above-mentioned microfibrillated product.

That is, the present invention relates to a short aromatic polyamide having an aromatic group in the main chain, and a sheet containing fibers and a microfibrillated product of aromatic polyamide as essential components, for use in printed wiring boards obtained by impregnating a heat-resistant resin. It is a sheet.

The sheet further contains a pulp-like aromatic polyamide.

The present invention will be described in detail below.

The aromatic polyamide having an aromatic group in the main chain used in the present invention is a homopolymer whose main components are an aromatic dicarboxylic acid and/or its acid chloride and an aromatic diamine.
or a copolymer.

Aromatic dicarboxylic acids and aromatic diamines can each take a meta form or a para form. Poly-P-phenylene terephthalamide, which has excellent dimensional stability of the obtained sheet,
Alternatively, fibers made of poly-P-phenylene/3,4' diaminodiphenyl ether/terephthalamide are preferred. The fineness of the fibers used is preferably 1 denier to 6 denier, and the fiber length is preferably 2 mm to 10 mm.

As shown in JP-A-56-100801, the microfibrillated aromatic polyamide used in the present invention is processed using a homogenizer, unlike the refiner used in general papermaking processes. It is microfibrillated. That is, 200 kg of slurry of aromatic polyamide fibers dispersed in water was placed before and after the slurry.
When the slurry particles are passed through an orifice with a pressure difference of /cnf or more at high speed and then immediately decelerated to apply shear force to the slurry particles, the aromatic polyamide fibers become microfibril-shaped vertically divided in the direction of the fiber axis.

This product was obtained by repeating this process.

A specific example is MFC-400 (manufactured by Daicel), which is a microfibrillated para-aromatic polyamide fiber (Kevlar fiber, manufactured by DuPont).

The pulp-like aromatic polyamide used in the present invention is a pulp-like material made of an aromatic polyamide polymer, and fiber fibrillated products and fibrids are preferable. Fibrillated material refers to fibrils generated by grinding fibers.

Fibrids are fiber fibrils or particles obtained by the method disclosed in Japanese Patent Publication No. 40-9044, which are obtained by dropping a polymer solution onto a polymer coagulant under high shear to coagulate and precipitate it.

The microfibrillated material has a fine fiber diameter that cannot be obtained by grinding the fibers or by forming them into fibrids. That is, since the microfibrillated material has a very fine fiber diameter of 0.7 μm or less, the entanglement between the fibers is large and the effect as a binder is remarkable.

However, the pulp-like material has a larger fiber diameter than the microfibrillated material, and cannot form a sheet as strong as the microfibrillated material alone.

Rather, there is an advantage that the yield of the microfibrillated product can be improved by mixing the aromatic polyamide short fibers with the slurry of the microfibrillated product.

Further, although aromatic polyamide has excellent heat resistance and dimensional stability, inorganic fillers and inorganic fibers may be mixed therein as long as these functions are not inhibited.

The sheet is obtained by uniformly dispersing and mixing the aromatic polyamide staple fibers and the microfibrillated product, making paper using a conventional paper machine, and drying the mixture. If necessary, a dense and smooth sheet can be obtained by pressing with or without heating using a calendar or the like.

The amount of microfibrillated aromatic polyamide is 5% to 40%, more preferably 10% to 40%, based on the weight of the sheet.
It is 40%. If it is less than 5%, the sheet strength will decrease,
The sheet is cut during resin impregnation. If it exceeds 40%, drainage properties will deteriorate and this is not preferable in the papermaking process.

The amount of pulp-like aromatic polyamide mixed in order to improve the yield of microfibrillated aromatic polyamide is preferably 3% to 30% based on the weight of the sheet. Pulp has a lower function as a binder than microfibrils and is less effective when used alone, but when used in combination with microfibrils, it not only functions as a binder but also improves the yield of microfibrils within the sheet. It also had the effect of At this time, the total amount of pulp and microfibrils is 8% to 60% of the sheet weight, preferably 10% to 50%. If it is less than 8%, the sheet strength will decrease, and if it is more than 60%, the drainage property will deteriorate, which is not preferable.

Moreover, if necessary, this pulp-like material may be beaten with a beating machine and used.

The heat-resistant resin to be used and impregnated in the present invention includes:
Examples include thermosetting resins such as thermosetting polyesteramide resin, epoxy resin, phenol resin, and polyimide resin, and these resins may be used alone or in combination of two or more. Further, if necessary, a material containing an inorganic filler can be used.

Next, a method for forming the printed wiring board sheet of the present invention will be described. The aromatic polyamide fiber sheet obtained as described above may be impregnated with a thermosetting resin, and after drying the solvent, the resin may be cured.

For impregnation with the resin solution, a commonly used horizontal or vertical impregnation machine can be used. Drying after impregnation also does not require special measures. If the impregnated sheet is sticky when dried, a release sheet may be optionally used in an appropriate step.

Furthermore, if necessary, a plurality of the above-mentioned impregnated sheets can be stacked and heated and pressed to integrate them.

To further laminate metal foil on the printed wiring board sheet of the present invention, it is possible to laminate the sheet with an adhesive resin, but without using an adhesive, the metal foil can be laminated before the sheet completely completes the curing reaction. They can also be directly bonded together and then cured.

[Function] The sheet for printed wiring boards of the present invention is a sheet made of aromatic polyamide short fibers having aromatic groups in the main chain and a microfibrillated product of the same aromatic polyamide as a binder. A substrate impregnated and cured with a synthetic resin functions effectively as a substrate with excellent electrical properties, heat resistance, and dimensional stability.

[Example] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

In the examples, all parts and percentages are by weight.

Examples 1 to 3 Poly-P-phinyl terephthalamide fiber (Kevlar 49, manufactured by DuPont, fiber length f3 + nm, after nm 12
microfibrillated poly-P-phenylene terephthalamide (MF) was dispersed in water at a concentration of 0.5%.
e2O4, solid content 2%, manufactured by Daicel Chemical Co., Ltd.) was added and mixed. At this time, each slurry was prepared by changing the blending ratio of the microfibrillated material to the fibers to 10%, 20%, and 40%.

Next, water was added to the above mixed slurry to dilute each to 0.2%, and in order to uniformly disperse the fibers, high molecular weight polyacrylamide (Acriverse-P-NS) was added.

(manufactured by Diafloc) 0. Add 1% aqueous solution as appropriate;
The mixture was stirred, made into paper by a conventional method, and dried to obtain a resin-impregnated sheet having a basis weight of 100 g/rd.

The obtained sheet was impregnated with a methyl ethyl ketone solution (solid content concentration 60%) of bismuth rayimide-triazine resin (BT resin, manufactured by Mitsubishi Gas Chemical Co., Ltd.), and excess resin was squeezed out with a glass bar to ensure uniform resin adhesion. I made it. 145℃
The sheet was dried for 8 minutes at 175° C. and then hot-press molded at 20 kg 1/car for 1 hour to obtain a sheet for a printed wiring board.

Example 4.5 Kevlar 49 fiber and MFe2 in the same manner as Examples 1-3
O4 was dispersed in water and a pulp of poly-P-phenylene terephthalamide (Kevlar pulp, manufactured by DuPont) was prepared.
were added and mixed. At this time, Kevlar 49/MFC400
/ The blending ratio of pulp-like material is 70/20/10.50/3
Each slurry was adjusted by changing the ratio by 0/20. A printed wiring board sheet was obtained in the same manner as in Example 1.

Comparative Example 1 A resin-impregnated sheet was obtained in the same manner as in Examples 1 to 3, using a Kevlar 49/Kevlar pulp blending ratio of 50,150. An attempt was made to impregnate the sheet with resin and hot-press mold it, but the resin-impregnated sheet was damaged by the press.

Comparative Example 2 10 parts of polymetaphenylene isoterephthalamide with a logarithmic viscosity of 1.5 in sulfuric acid are dissolved in 90 parts of dimethylacetamide containing 3% LiCl and this polymer solution is introduced into glycerin in a household mixer with high speed stirring. The mixture was filtered and washed with water to obtain meta-aromatic polyamide fibrids. 49.70 parts of Kevlar and 30 parts of the above-mentioned fibrids were stirred and mixed in water to prepare a slurry with a solid content concentration of 0.2%, and after adding Acriverse aqueous solution to uniformly disperse the fibers, papermaking was carried out by a conventional method. It was dried to obtain an impregnated sheet. Using this sheet, BT-resin was impregnated and cured in the same manner as in Examples 1 to 3.

Comparative Example 3 A test was carried out in the same manner as in Comparative Example 1, using polymetaphenylene isophthalamide fiber (Avielle, manufactured by Unitika, fineness 2 denier, fiber length 5 mm) in place of Kevlar 49 in Comparative Example 1.

Examples 6-8 Impregnated sheets were obtained in the same manner as in Examples 1-3. However, the basis weight of the sheet was 40 g/rd. The obtained sheet was impregnated with an epoxy resin solution consisting of 100 parts of epoxy resin (Epicote 1001, manufactured by Yuka Shell Co., Ltd.), 6 parts of dicyanamide, 0.4 parts of benzyldimethylamine, and 67 parts of methyl ethyl ketone, and dried at 120°C for 10 minutes. 17
Hot pressure molding was carried out at 0° C. and 20 kgf/al for 1 hour to obtain a sheet for a printed wiring board.

Example 9 An impregnated sheet having a basis weight of 40 g/rrf was obtained in the same manner as in Example 4.5. An attempt was made to obtain a printed circuit board sheet using the obtained sheet in the same manner as in Examples 6 to 8, but as in Comparative Example 1, the sheet was damaged. Example 10 Poly-P instead of Kevlar 49 short fibers in Examples 6 to 8
-Phenylene 3,4' diaminodiphenyl ether-terephthalamide staple fiber (Technora T-320,
Manufactured by Kijinsha, fineness 1.5 denier, fiber length 5 mm) 80,
Sheets for printed wiring boards were obtained in the same manner as in Examples 6 to 8 using 20 parts of MFe2O4.

Comparative Example 4 An impregnated sheet with a basis weight of 40 g/- was obtained in the same manner as in Comparative Example 1. Sheets for printed wiring boards were obtained in the same manner as in Examples 6-8.

Comparative Example 5 An impregnated sheet having a basis weight of 40 g/rri was obtained in the same manner as in Comparative Example 2. Printed circuit board sheets were obtained in the same manner as in Examples 6-8.

The physical property measurement methods used in the present examples and comparative examples are as follows.

(1) Resin-impregnated sheet The impregnated sheet is cut into 1.5 cm wide pieces and soaked in resin up to 2 cm from the lower end. After 30 seconds, the height of the resin liquid level rising in the sheet was measured.

(2) Dimensional change rate (thermal expansion coefficient) The dimensional change rate of a resin-impregnated and hot-press molded sample before and after treatment at 150° C. for 30 minutes was determined by the IPCFC241 method.

(3) Solder resistance Swelling and color changes were observed according to JIS C6481.

(4) Water absorption rate Water absorption rate of seeds soaked in water at 23°C for 24 hours.

The results of Examples 1 to 5 and Comparative Examples 1 to 3 conducted by the above method are shown in Table 1, and the results of Examples 6 to 10 and Comparative Examples 4.5 are shown in Table 2.

[Effect of the invention] A sheet made of a microfibrillated product of the same aromatic polyamide as the short aromatic polyamide fibers unique to the present invention, or a sheet further containing a pulp-like aromatic polyamide impregnated with a heat-resistant resin and cured is obtained. This is a resin sheet useful for the electrical insulation layer of printed wiring circuit boards. That is, resin impregnation is performed quickly and uniformly, and the film has excellent heat resistance and moisture resistance. Furthermore, since it has excellent dimensional stability, it is very preferable from the point of view of fine circuit design.

Procedural amendment (from 岨) October 29, 1990 1. Indication of the case 1999 Patent Application No. 272203 Filing date October 18, 1999 2. Name of the invention Printed wiring board sheet 3. Make amendments Name of address related to the incident

Claims (5)

[Claims] (1) For a printed wiring board characterized by impregnating and curing a heat-resistant resin into a paper-made sheet containing aromatic polyamide short fibers having an aromatic group in the main chain and a microfibrillated product of aromatic polyamide. sheet. (2) The printed wiring board sheet according to claim 1, which contains a pulp-like aromatic polyamide. (3) The printed wiring board sheet according to claim 1 or 2, wherein the aromatic polyamide comprises poly-P-phenylene terephthalamide. (4) The printed wiring board sheet according to claim 1 or 2, wherein the aromatic polyamide staple fibers are composed of poly-P-phenylene/3,4'diaminodiphenyl ether/terephthalamide. (5) The printed wiring board sheet according to claim 1, wherein the blending ratio of the microfibrillated aromatic polyamide is 5% to 40%.