JPH1142637A - Production of prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the generation of copper foil wrinkles by a method in which after a fiber backing being impregnated with a kind of thermosetting resin varnish, the backing is heat-dried, a prepreg main body in which the thermosetting resin was cured to a B stage is pressurized while being cooled, and the surface is smoothed. SOLUTION: A lengthy fiber backing 1 such as a glass cloth, after being impregnated in an impregnation tank 3 with a kind of epoxy resin varnish 2 deformed by vacuum deaeration, is heat-dried continuously by a drier 4 to prepare a prepreg in a B stage. The prepreg which is discharged continuously from the drier 4, in the course of being cooled, is passed through two press rolls 6 and press-pinched, and the surface is smoothed. In this way, by using the remaining heat of the prepreg, the surface of the prepreg discharged continuously from the drier 4 can be smoothed. Even when the prepreg is used for copper-clad laminated board using very thin copper foil, the generation of copper foil wrinkles can be reduced.

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 suitably used for producing a printed wiring board.

[0002]

2. Description of the Related Art After impregnating a fiber base material such as pulp paper, glass woven cloth or glass nonwoven cloth with a thermosetting resin varnish composed of a thermosetting resin such as an epoxy resin, an imide resin and a phenol resin and an organic solvent, The prepreg manufactured by heating, drying and curing the thermosetting resin to the B stage is stacked in an arbitrary number, a copper foil is arranged outside the prepreg, and heated and pressed to be integrated, and the printed wiring board is integrated. It is used for the production of a copper-clad laminate that is used as a material.

[0003] Copper-clad laminates have come to require high precision and high reliability of printed wiring boards used in the electronics field. For this reason, the performance and quality required for prepregs have become strict, and in particular, there is a high demand for lightness and shortness,
In order to reduce the weight, the copper foil used for the copper-clad laminate has become extremely thin. For example, conventionally, copper foils forming circuit patterns have been mainly used in thicknesses of 18 μm and 35 μm, but copper foils of 12 μm and 9 μm have come to be used.

[0004] However, as the copper foil becomes extremely thin, wrinkles of the copper foil have been observed. This is because, as the thickness of the copper foil decreases, smoothness defects such as protrusions of the prepreg existing on the surface of the prepreg are reflected on the copper foil, and copper foil wrinkles occur.

[0005] A commonly used prepreg is formed using a fibrous base material such as pulp paper, glass woven fabric, or glass nonwoven fabric. After impregnating this fiber base material with a thermosetting resin varnish consisting of a thermosetting resin of a cyanate resin and an organic solvent, an imide resin, a phenol resin, and an organic solvent,
The thermosetting resin is heated, dried, and cured to a semi-cured state, B stage, to produce a prepreg.

However, the fibers constituting the fiber base material protrude from the surface of the base material, and so-called fluff is generated. As a cause of the generation of the fluff, the fiber is often rubbed or frayed in a spinning or weaving process. When the prepreg is manufactured by impregnating the thermosetting resin varnish into the fiber base having the fluff, the resin is liable to agglomerate in the fluff portion, and the portion becomes excessively adhered to the resin. Further, the curing proceeds from the surroundings and may be completely cured.

When a copper-clad laminate of ultra-thin copper foil is manufactured using the above prepreg, copper foil wrinkles due to the fluff are generated on the surface of the copper foil.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to manufacture a copper-clad laminate using ultra-thin copper foil. In particular, it is an object of the present invention to provide a method for producing a prepreg capable of reducing the occurrence of wrinkles of a copper foil.

[0009]

According to a first aspect of the present invention, there is provided a method for producing a prepreg, comprising the steps of impregnating a fiber base material with a thermosetting resin varnish, heating and drying the fiber base material, The method is characterized in that a surface is smoothed by applying pressure in a process of cooling a prepreg body in which a resin is cured to a B stage.

According to a second aspect of the present invention, there is provided the prepreg manufacturing method according to the first aspect, wherein the surface temperature of the prepreg during the cooling step is 80 ° C.
~ 130 ° C.

According to a third aspect of the present invention, there is provided a method for producing a prepreg according to the first aspect, wherein the pressure for pressing the main body of the prepreg is 1 kg / cm.
It is characterized by being ^{2 to} 30 kg / cm ² .

[0012]

Embodiments of the present invention will be described below.

[0013] In the method for producing a prepreg of the present invention, a fiber substrate is impregnated with a thermosetting resin varnish, and heated and dried to form a continuously formed prepreg.
That is, the surface is smoothed by pressing the surface while the prepreg itself has a residual heat of 80 ° C. to 130 ° C. By using the residual heat of the prepreg itself, economical smoothing can be performed, and since the surface of the prepreg continuously discharged from the dryer is smoothed, productivity is also improved. The temperature of the prepreg discharged from the dryer varies depending on the resin to be impregnated. In general, if the resin is an epoxy resin, if the temperature is lower than 80 ° C., a resin crack occurs at the time of pressing. The resin adheres to the pressurized portion in a state where is melted. Therefore, in order to keep the prepreg in the above-mentioned temperature range in the pressurizing section, it is preferable to provide a warming device or a cooling device.

Further, the main body of the prepreg is 1 kg / cm ²
By applying a pressure of ｋｇ30 kg / cm ² , the surface can be smoothed without causing deformation of the resin.

As a method of pressurizing, it is preferable to use a pressurized pinch roll in order to continuously pressurize the prepreg, and the roll is not limited. For example, a roll with a heat retaining jacket, A roll whose surface is coated with a fluororesin is preferred.

The method for producing a prepreg according to the present invention is characterized in that the surface of the prepreg is smoothed to obtain a prepreg of 12 μm or 9 μm.
The production of copper foil wrinkles can be suppressed even when a copper-clad laminate is manufactured using the ultra-thin copper foil.

FIG. 1 shows a production apparatus showing one embodiment of a method for producing a prepreg according to the present invention.
Tank 3 for impregnating the resin, a dryer 4 for heating and drying the fiber base material 1 impregnated with the resin varnish 2, a drawer roll 5 for drawing out the fiber base material 1, and a pressurization provided at an outlet of the dryer 4. And a roll 6. [Example 1] MIL spec # 76 manufactured by Asahi Schabel
Epoxy resin varnish (Epoxy resin; YDB-500KEK80, manufactured by Toto Kasei Co., Ltd .: 72.50%, epoxy resin; YDCN220EK75, manufactured by Toto Kasei Co., Ltd.): 6.27 %, Disindiamide: 1.41%, dimethylformamide: 9.88%, propylene glycol monomethyl ether: 9.91%, imidazole: 0.03%), and continuously heat-dried with a dryer at a temperature of 170 ° C to form a B-stage prepreg. did. The impregnation amount was 42% (calculated with glass cloth + varnish being 100%).

In the process of cooling the prepreg continuously discharged from the dryer, the prepreg was passed through two pressure rolls, and was pressed and pinched at 5 kg / cm ² for smoothing. At this time, the surface temperature of the prepreg was 110 ° C. [Example 2] MIL spec # 76 manufactured by Asahi Schabel
28 long glass cloth was impregnated with epoxy resin varnish from which air bubbles had been removed by vacuum degassing, and the temperature was continuously 17 ° C.
It was dried by heating in a dryer at 0 ° C. to form a B-stage prepreg.

In the process of cooling the prepreg continuously discharged from the dryer, the prepreg was passed through two pressure rolls and subjected to a pressure pinch at 25 kg / cm ² for smoothing. At this time, the surface temperature of the prepreg was 110 ° C. [Example 3] MIL spec # 76 manufactured by Asahi Schabel
28 long glass cloth was impregnated with epoxy resin varnish from which air bubbles had been removed by vacuum degassing, and the temperature was continuously 17 ° C.
It was dried by heating in a dryer at 0 ° C. to form a B-stage prepreg.

In the process of cooling the prepreg continuously discharged from the dryer, the prepreg was passed through two pressure rolls, and was pressed and pinched at 5 kg / cm ² for smoothing. At this time, the surface temperature of the prepreg was 85 ° C. [Example 4] MIL spec # 76 manufactured by Asahi Schabel
28 long glass cloth was impregnated with epoxy resin varnish from which air bubbles had been removed by vacuum degassing, and the temperature was continuously 17 ° C.
It was dried by heating in a dryer at 0 ° C. to form a B-stage prepreg.

In the process of cooling the prepreg continuously discharged from the dryer, the prepreg was passed through two pressure rolls and subjected to a pressure pinch at 25 kg / cm ² for smoothing. At this time, the surface temperature of the prepreg was 85 ° C. Comparative Example 1 A B-stage prepreg was formed in the same manner as in Example 1 and cooled without applying pressure to obtain a prepreg. Evaluation To evaluate the prepregs obtained in the above Examples 1 to 4 and Comparative Example, a copper foil having a thickness of 9 μm was placed above and below each prepreg, and heated and pressed to obtain a copper-clad laminate. Was. The surface of each of the obtained copper-clad laminates was visually inspected for wrinkle defects. One copper-clad laminate
100 sheets were inspected with m-sided copper-clad laminates. The results are shown in Table 1 for the probability of occurrence of wrinkle defects due to fluff.

[0022]

[Table 1]

As shown in Table 1, the copper-clad laminate using the prepreg manufacturing method of the present invention can provide a stable copper-clad laminate with less wrinkling.

[0024]

According to the method for producing a prepreg according to the present invention, after impregnating a thermosetting resin varnish on a fibrous base material, the fibrous base material is heated and dried to cure the thermosetting resin to the B stage. The prepreg body is pressurized in the process of cooling, so the surface of the prepreg continuously discharged from the dryer can be smoothed using the residual heat of the prepreg, and copper-clad lamination using ultra-thin copper foil Even if the prepreg is used for a plate, the occurrence of copper foil wrinkles can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a manufacturing method device used in a prepreg manufacturing method of the present invention. It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber base material 2 Resin varnish 3 Impregnation tank 4 Dryer 5 Pull-out roll 6 Pressure roll

Claims (3)

[Claims] After impregnating a thermosetting resin varnish on a fiber base material, the fiber base material is heated and dried, and the prepreg body obtained by curing the thermosetting resin to the B stage is pressurized in a process of cooling. A method for producing a prepreg, characterized by smoothing the surface. 2. The method for producing a prepreg according to claim 1, wherein the surface temperature of the prepreg in the cooling step is:
A method for producing a prepreg, wherein the temperature is from 80C to 130C. 3. The method for producing a prepreg according to claim 1, wherein the pressure for pressing the main body of the prepreg is 1 kg.
Method for producing a prepreg, which is a / cm ² ~30kg / cm ^2.