JP2002293962A - Method for producing prepreg and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting resin-impregnated prepreg having excellent impregnating properties and a method for producing a thermosetting resin laminate having excellent punchability and reliability in insulation between through-holes by using a low-density organic fiber nonwoven fabric substrate. SOLUTION: This method for producing the prepreg is characterized by impregnating the organic fiber nonwoven fabric substrate having 0.005-0.4 g/cm<3> density with a liquid or a slurry resin composition consisting essentially of a thermosetting resin or the thermosetting resin and a curing agent and drying the impregnated substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a prepreg and a laminate having excellent impregnation properties. Industrial Applicability The manufacturing method of the present invention is used for manufacturing printed wiring board materials used in industrial equipment and electronic equipment, and is particularly suitable for manufacturing a phenolic resin laminate excellent in insulation reliability between through holes and its prepreg. Used.

[0002]

2. Description of the Related Art Printed wiring boards are used in electrical appliances in a very wide range of fields, from household consumer electronics to high-performance industrial equipment. Generally, as a printed wiring board material, one or more prepregs obtained by impregnating and drying a base material with a resin composition containing a thermosetting resin and a curing agent as main components (hereinafter referred to as a resin varnish) are used. Are laminated with a metal foil such as a copper foil and formed by heating and pressing. There are various grades of these depending on the type of the thermosetting resin and the base material used, and they are used properly depending on the performance and application.

[0003] The printed wiring board material mainly used in the field of consumer electronics is a phenolic resin-clad laminate of paper base material. Wiring boards are also becoming smaller and denser, and the use of double-sided copper-clad laminates is increasing.Furthermore, higher circuit densities have reduced through-hole gaps, resulting in further improvements in insulation reliability between through-holes. Improvement is required.

[0004] In order to ensure insulation reliability between through holes in a printed wiring board, it is necessary to manufacture a prepreg excellent in impregnating property with little voids remaining as an intermediate product. However, the paper substrate conventionally used for printed wiring boards weighs 110 to 200 g.
/ M ² and a density of 0.5 to 1.5 g / cm ³ were the mainstream. To improve the impregnation of the resin varnish into the substrate, the coating speed during the production of the prepreg was reduced. In many cases, a two-stage impregnation method is employed in which the impregnation time is extended or a solvent such as water or a low-viscosity resin varnish diluted with these solvents is impregnated first. However, these methods have problems such as lower productivity and larger equipment.

[0005]

SUMMARY OF THE INVENTION The present invention provides a thermosetting resin-impregnated prepreg excellent in impregnation by using a low-density organic fiber nonwoven fabric substrate, and a punching process.
An object of the present invention is to provide a manufacturing method for obtaining a thermosetting resin laminate having excellent insulation reliability between through holes.

[0006]

According to the present invention, there is provided (1) a liquid or slurry-like resin composition containing a thermosetting resin or a thermosetting resin and a curing agent as essential components.
A method for producing a prepreg, which is obtained by impregnating and drying an organic fiber nonwoven fabric substrate having a weight of 0.5 to 0.4 g / cm ³ , and (2) a weight of the organic fiber nonwoven fabric substrate is 20 to 100 g.
/ M ² , wherein (3) the organic fiber nonwoven fabric substrate is made of vegetable fiber, animal fiber or chemical fiber. (1) The method for producing a prepreg according to the item (1) or (2), (4) One or more prepregs obtained by the method according to any one of the items (1) to (3) are stacked. And heat and pressure molding.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is characterized in that a low-density organic fiber nonwoven fabric base material is used when producing a prepreg impregnated with a thermosetting resin.

[0008] The organic fiber nonwoven fabric substrate used in the present invention
The density is 0.005 to 0.4 g / cm ^ThreeGood to be
More preferably, 0.02 to 0.4 g / cm^Threeso
is there. 0.4g / cm^ThreeIf it is larger, the resin
The impregnation rate is not sufficient due to the reduced varnish impregnation rate
With 0.02 g / cm^ThreeIf smaller, same as base fiber
Entanglement of the technician is reduced,
The strength of the substrate may be insufficient for the applied stress. Pre
Considering impregnation and practicality during prepreg production,
Preferably 0.04 to 0.2 g / cm^ThreeIt is.

[0009] The weight of the organic fiber nonwoven fabric substrate is 20
Is preferably to 100 g / m ^2. 100g / m
^Although it is possible to use a substrate that is heavier than ^{2, the} increase in thickness may increase the cost of the substrate,
If it is less than 20 g / m ^2, it may be difficult to process it into a sheet that can be used as a non-woven fabric substrate for prepreg production. More preferably, 30 to 80 g / m ²
It is.

The raw material of the organic fiber nonwoven fabric substrate used in the present invention includes wood such as hardwood and conifer, vegetable fiber such as hemp and cotton, animal fiber such as wool, and synthetic fiber such as polyamide fiber and polyester fiber. Can be used. When processing these organic fibers into a sheet-shaped nonwoven fabric suitable for the production of prepreg, any of a dry method and a wet method may be used, but when a low-density substrate used in the present invention is produced, a general method is used. The dry method is used. Further, a binder resin such as an epoxy resin, a phenol resin, and an acrylic resin can be used for bonding the fibers. The amount of the binder resin is preferably 5 to 30% by weight based on the entire weight of the base material.

In the present invention, a prepreg having a large weight per unit area can be produced by using a low-density organic fiber nonwoven fabric substrate. Conventionally, when a large amount of resin is impregnated or coated on a base material, a large amount of resin remains on the base material surface, so that problems such as uneven coating and warpage are likely to occur, and it is not easy to increase the weight of the prepreg. Therefore, it was difficult to reduce the number of laminated plies, but since the base material used in the present invention has a low density, a large amount of the resin composition can be contained in the fiber, so that it is easy to increase the weight of the prepreg,
The number of laminated plies can be reduced.

The thermosetting resin used in the present invention is not particularly limited, but a phenol resin obtained by reacting phenols such as phenol and cresol with formaldehyde is generally used. Those can also be used. A mixture of these phenolic resins with a bisphenol-type epoxy resin may be used. In addition, epoxy resins, unsaturated polyester resins, melamine resins, and the like can also be used. Further, a flame retardant may be added to provide a flame retardant effect.

The resin varnish used in the present invention may optionally contain an inorganic filler. By adding an inorganic filler, it is possible to impart properties such as improvement in tracking resistance and heat resistance of the laminate and a decrease in the coefficient of thermal expansion. Examples of the inorganic filler having such an effect include aluminum hydroxide, magnesium hydroxide, calcium carbonate, talc, wollastonite, alumina, silica, unfired clay, fired clay, and barium sulfate.

The above-mentioned thermosetting resin is dissolved in a solvent, adjusted to an appropriate concentration and viscosity, and then impregnated into a low-density organic fiber nonwoven fabric substrate and dried to obtain a prepreg. That is, the base material is impregnated or coated with a resin varnish,
By drying at a temperature of 0 ° C., a prepreg for a laminate is obtained.

The present invention is characterized in that one or more of the prepregs are laminated together with a metal foil, if necessary, and heated and pressed to obtain a laminate. In the present invention, conditions generally used for the resin and the base material to be used can be applied to the conditions for heating and pressing the prepreg. For example, when using a prepreg in which a phenol resin is impregnated into a pulp fiber nonwoven fabric substrate, the temperature is 130 to 190 ° C., and the pressure is 50 to 120 kg / c.
A phenol resin laminate is obtained by heating and pressing at m ² for 20 to 100 minutes.

[0016]

EXAMPLES [Production of phenolic resin varnish] 1600 g of phenol and 1000 g of tung oil were reacted at 95 ° C. for 2 hours in the presence of p-toluenesulfonic acid, and 650 g of paraformaldehyde, 30 g of hexamethylenetetramine,
After adding 2000 g of toluene and reacting at 90 ° C. for 2 hours, the mixture was concentrated under reduced pressure, and diluted with a mixed solvent of toluene and methanol to obtain a tung oil-modified phenol resin varnish having a resin content of 50%.

Example 1 Weight 45 g / m ² , density 0.
The phenolic resin varnish was immersed and impregnated in a 10 g / cm ³ pulp fiber non-woven fabric base material (JS45HD manufactured by Havix Corporation) for 10 seconds, and then immersed in a hot air drier at 150 ° C. for 3 seconds.
After drying for minutes, a prepreg having a weight of 250 g / m ² was obtained. Eight prepregs are superimposed, and a 35 μm-thick electrolytic copper foil (Nihon Denki FGH-35) is placed above and below the prepreg.
At 160 ° C. and a pressure of 100 kg / cm ² .
It was heated and pressed for 0 minutes to obtain a phenol resin copper-clad laminate having a thickness of 1.6 mm.

Example 2 Weight 75 g / m ² , density 0.
The phenolic resin varnish was immersed and impregnated in a pulp fiber non-woven fabric substrate of 05 g / cm ³ (JS75HB manufactured by Havix Corporation) for 10 seconds, and then dried with a hot air drier at 150 ° C.
After drying for minutes, a prepreg having a weight of 250 g / m ² was obtained. Eight sheets of this prepreg are superimposed, and a 35 μm-thick electrolytic copper foil (Nihon Denki FGH-35) is placed above and below the prepreg.
At 160 ° C. and a pressure of 100 kg / cm ² .
It was heated and pressed for 0 minutes to obtain a phenol resin copper-clad laminate having a thickness of 1.6 mm.

Example 3 Weight 75 g / m ² , density 0.
The phenolic resin varnish was immersed and impregnated in a pulp fiber non-woven fabric substrate of 05 g / cm ³ (JS75HB manufactured by Havix Corporation) for 10 seconds, and then dried with a hot air drier at 150 ° C.
After drying for 1 minute, a prepreg having a weight of 1000 g / m ² was obtained. Two of these prepregs are overlapped, and a 35 μm-thick electrolytic copper foil (Nihon Denki FGH-35) is placed above and below the prepreg.
At 160 ° C. and a pressure of 100 kg / cm ² .
It was heated and pressed for 0 minutes to obtain a phenol resin copper-clad laminate having a thickness of 1.6 mm.

Comparative Example 1 Kraft paper having a weight of 190 g / m ² and a density of 0.95 g / cm ³ (ENSO, EN
SO-190) was immersed and impregnated with the phenol resin varnish for 20 seconds, and then dried with a hot air dryer at 150 ° C. for 3 minutes to obtain a prepreg having a weight of 250 g / m ² . The eight prepregs are stacked, and a thickness of 35
A μm electrolytic copper foil (Nihon Denki FGH-35) was overlaid and heated and pressed at 160 ° C. and a pressure of 100 kg / cm ² for 60 minutes to obtain a 1.6 mm thick phenolic resin-clad laminate. .

Table 1 shows the results of evaluating the characteristics of the laminates obtained in the above Examples and Comparative Examples.

[Table 1]

(Measurement method) Insulation reliability between through-holes (migration resistance): 100-mm holes are drilled in copper-clad laminates with a 0.5 mm gap between walls, filled with silver paste, and treated at 90% humidity and 40 ° C for 96 hours. The insulation resistance between the walls was measured. 2. 2. Punching workability: According to ASTM D617-44. Impregnating property: 0.6mmφ hole in copper-clad laminate between walls.
After opening at 4 mm, the solution was put into a pressure vessel together with a 0.01% by weight aqueous solution of methylene blue, and the pressure was adjusted at 125 ° C. and 1.5 atm.
After permeation for a time, the cross section between the through holes was observed with a metallographic microscope.

In each of Examples 1 and 2, a prepreg was produced by impregnating a low-density organic fiber nonwoven fabric base material with a phenolic resin varnish, and was subjected to heat and pressure molding. A laminate having excellent punching workability and good impregnation was obtained. In Example 3, a high weight prepreg was used, but the same effect was obtained. On the other hand, in Comparative Example 1, a substrate having a conventional density was used.
In each case, the characteristics were inferior to those of the above examples.

[0024]

According to the present invention, a low-density organic fiber nonwoven fabric substrate is impregnated with a thermosetting resin or a liquid or slurry resin composition containing a thermosetting resin and a curing agent as essential components and dried. A method for producing a prepreg and a laminate using the same, which is suitable as a method for industrially obtaining a thermosetting resin laminate having excellent through-hole insulation reliability.

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Claims (4)

[Claims] 1. A thermosetting resin or a thermosetting resin and a curing agent
Or slurry resin set containing as an essential component
The product is prepared with a density of 0.005 to 0.4 g / cm. ^Three Is
It is characterized by being impregnated into a nonwoven fabric substrate and dried.
Prepreg manufacturing method. 2. The organic fiber nonwoven fabric substrate has a weight of 20 to 10
Method for producing a prepreg according to claim 1, characterized in that the 0 g / m ^2. 3. The method for producing a prepreg according to claim 1, wherein the organic fiber nonwoven fabric base is made of vegetable fiber, animal fiber or chemical fiber. 4. A method for producing a laminate, comprising laminating one or more prepregs obtained by the method according to any one of claims 1 to 3, and subjecting them to heat and pressure molding.