JPH01215517A - Manufacture of metallic foil plated laminated sheet - Google Patents

Abstract

PURPOSE:To manufacture a metallic foil plated laminated sheet having smoothness by controlling expansion of a base material, by a method wherein after press molding by laminating the resin impregnated base material to a metallic foil, pressurization/cooling are performed immediately. CONSTITUTION:Press molding of a resin impregnated base materials 5, 5 to a metallic foil 4 is performed and a laminated sheet 8 is obtained. Immediately after molding, the laminated sheet 8 (which is under a high temperature) is sent to a cooling zone 10, pressurization/cooling are performed with a pair or two pairs or more pressurization/cooling rolls 11, 11 and a metallic foil plated laminated sheet is obtained. As the cooling is performed while pressurizing the laminated sheet immediately after the press molding, expansion of the base material such as glass cloth is controlled. Therefore, appearance of unevenness of the base material is controlled and a metallic foil plated laminated sheet whose surface roughness is fine is obtained without transferring the unevenness to the surface of the metallic foil.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a continuous manufacturing method for metal foil-clad laminates used for printed wiring boards and the like.

[Conventional technology]

Conventionally, resin-impregnated base materials (prepreg) impregnated with a thermosetting resin are laminated and heated and pressed to produce a laminate used for printed wiring boards, etc., using a multistage press machine to form a laminate. The daylight press method, which involves press forming in multiple stages, has been used. However, with this method, a laminate equivalent to several product bones is inserted between the hot plates and pressed, resulting in high-pressure forming, resulting in large distortions remaining in the laminate. There are some difficulties. In addition, because it is difficult to arrange the heating plates exactly parallel to each other, the thickness of the laminated plates is not constant between the center and the ends or between one end and the other, resulting in a lack of dimensional stability of the product. There were also problems. On the other hand, the heat transfer state is different between the laminates close to the hot plate surface and the laminates located far away, which can cause voids and other defects in product appearance.Furthermore, since the process is done in batches, production Problems also remained in terms of performance and efficiency.

Therefore, as a method that can be formed at relatively low pressure and also achieve high productivity and dimensional stability, a long strip-shaped laminate is formed between the opposing surfaces of a pair of heated metal belts (endless belts). A so-called double-belt press method has been developed in which a laminate is obtained by continuously feeding a molded object and press-forming it while moving it between the belts. According to this double belt press method, it is possible to produce a laminate with improved plate thickness accuracy, 9 dimensional stability, etc. compared to the daylight press method.

[Problem to be solved by the invention]

Although the double belt press method has such advantages and is expected to be a useful method in the future, there are still some issues to be considered, one of which is the surface roughness of the laminate. Normally, base materials such as glass cloth used for resin-impregnated base materials expand when cooled after molding, while thermosetting resins in resin-impregnated base materials conversely contract. Due to these properties, the unevenness of the base material such as glass cloth will be reflected on the surface of the metal foil of the laminate, making it inevitable that the surface of the product will become rough.

This is especially noticeable when the metal foil such as copper foil is as thin as 35 nm or 18 nm. The copper foil surface roughness of the plate was about 4.5 to 5.5 n (value measured in the diagonal direction of the glass cloth, the same applies hereinafter). By the way, when a laminate with the same combination is manufactured using the daylight press method, its surface roughness is 4.
0-5. The daylight press method allows the laminate to be cooled to a certain extent while maintaining the pressurized state after press forming. This is thought to be due to the fact that the expansion of the base material due to cooling is suppressed, making it difficult to form irregularities.

Nowadays, metal foil-clad laminates with low surface roughness are desired so that they can provide printed wiring boards suitable for surface mounting various electronic components. has become an issue that requires an urgent solution.

Therefore, it is an object of the present invention to provide a manufacturing method that allows continuous production of metal foil-clad laminates with low surface roughness. More specifically, the surface roughness of the metal foil is at least equal to or lower than that produced by the conventional day press method, for example, in the above combination of copper foil and glass cloth, the surface roughness of the metal foil is 4°0IIN or less. The goal is to achieve this in the double belt press method.

[Means to solve the problem]

In order to solve the above-mentioned problems, in the present invention, when a metal foil-clad laminate is continuously produced by a double belt press method, the metal foil-clad laminate is cooled while being pressurized immediately after press forming.

[For production]

Since the high-temperature laminate immediately after press-forming is cooled while being pressurized, expansion of the base material such as glass cloth that occurs due to cooling is suppressed. Therefore, the appearance of irregularities on the base material is suppressed, and the irregularities do not transfer to the surface of the metal foil, resulting in a laminate with a small surface roughness.

〔Example〕

An embodiment of the method for manufacturing a metal foil-clad laminate according to the present invention will be described below with reference to the drawings. 2 is a perspective view of the same, as shown in FIG. It is equipped with a heating and pressing means 9 that performs heating while applying pressure in the direction. The above pair of belts 1゜1 are
They rotate in opposite directions at the same speed in accordance with the rotation of the inlet roll (inlet drum) 2.2 and the outlet roll (exit drum) 3.3, and in their opposing parts, they both move in the same direction (arrow B) at the same speed. It is now progressing. Further, as shown in FIG. 2, the clearance between the inlet roll 2.2 and the outlet rolls 3, 3 can be adjusted depending on the thickness of the object to be formed by a cylinder mechanism or the like.

The long strip-shaped metal foil 4.4 and the long strip-shaped resin-impregnated base material 5 are each guided by guide rolls 6 and sent into a press molding apparatus, and are laminated into the above-mentioned state. Bell) 1.1 is sandwiched between the opposing parts.

Here, the laminate (molded object) 7 consisting of the metal foil 4 and the resin-impregnated base material 5 is subjected to the action of the heating and pressing means 9 through the belt 1, and is pressed in the direction of arrow A while being heated. Press molding is performed continuously, and at this time, the semi-cured resin impregnated into the resin-impregnated base material 5 is melted and cured while adhering to each other, so that strip-shaped metal foil-clad laminates (
Product) 8 is taken out.

A feature of this invention is that the laminated plate 8 in a high temperature state immediately after press forming is cooled under pressure.

For example, as shown in the figure, the formed laminate 8 is immediately sent to a cooling zone 10 and passed between one or more pairs of pressure/cooling rolls 11, 11, . . . . After cooling is completed, the metal foil-clad laminate 8 is cut into a desired size using a cutter (not shown) or the like.

The pressurized cooling conditions are not particularly limited, but for example, 1
It is preferable to carry out at about 0 to 25 kg/ad and about 20°C or less.

Note that the apparatus used to carry out the present invention is not limited to that shown in the drawings, and for example, as the pressurized cooling means, after cutting the laminated plate into a predetermined size, cutting the laminated plate into a predetermined size and then cutting the laminated plate into a predetermined size and then cutting the laminated plate into a predetermined size and then cutting the laminated plate into a predetermined size and then cutting the laminated plate into a predetermined size, A method such as passing through the cooling zone while being sandwiched between them and applying pressure may be adopted, and there is no particular limitation.

In addition, in this invention, the laminate does not need to be a double-sided metal foil-clad laminate with metal foil arranged on both sides, and it is sufficient that the metal foil is arranged on at least one side of the laminate. This also includes foil-clad laminates, in which case a release film is placed instead on the side without the metal foil to prevent the laminate from adhering to an endless belt, etc. during molding. Bye.

The resin-impregnated base material in this invention is not particularly limited, and includes various base materials such as glass, inorganic fibers such as asbestos, woven or non-woven fabrics made of inorganic fibers such as asbestos, organic synthetic fibers such as nylon and Tetron, mats, and paper. ,Epoxy resin,
Common examples include those impregnated with various thermosetting resins such as diallyl phthalate resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, and polybutadiene resin.

The impregnation and drying methods of the resin varnish are not particularly limited, and additives such as a curing agent (crosslinking agent), curing accelerator, catalyst (1-coin initiator), etc. may be added to the resin and solvent as necessary. After preparing a resin varnish and impregnating the base material with the resin varnish in a conventional manner, the resin may be cured to a semi-cured state while being dried. Here, the impregnated resin is preferably fast-curing due to the manufacturing method of continuous molding.
It is preferable that the time is adjusted to approximately 0 seconds.

The resin content of the resin-impregnated base material is usually 40 to
It is adjusted to about 55% by weight (value after drying), but is not limited to this. The number of resin-impregnated base materials to be laminated is also set arbitrarily, and for example, about 2 to 10 sheets are laminated. Further, a heat-fusible plastic film (for example, polyphenylene oxide, polyphenylene sulfide, epoxy resin, polyimide resin, etc.) having electrical insulation properties, heat resistance, etc. may be used in combination with the resin-impregnated base material.

The type of metal used as the metal foil is also not particularly limited, and includes commonly used metals such as copper, aluminum, and nickel. Further, the thickness can be set arbitrarily, and the effects of the present invention are particularly remarkable when a thin metal foil of 35 μl or 18 nm is used, for example.

It is preferable to use steel as the endless belt in terms of thermal conductivity, friction coefficient, etc.
It is not limited to this.

Furthermore, the heating and pressing means is, for example, a plurality of heated pressing rolls, heating and pressing plates, etc., and the temperature and pressure are determined depending on the type of resin in the resin-impregnated base material, so that the resin softens,
It is preferable that the temperature at which the resin is melted and cured from a semi-hardened state to a fully hardened state, and the pressure at which the molten resin can be pressed without causing it to flow more than necessary and be removed, are preferably set as appropriate, for example, In the case of epoxy resin, 1
It is appropriate that the temperature is 60 to 180°C and about 5 to 10 kg/cA.

Next, more specific examples and comparative examples will be described.

(Examples 1 and 2) As the base material, long strip-shaped glass cloth 7628W (Nitto Boseki side part 1 product name -E18 to -104, plain weave, thickness 0.18
m.

Width 104C11, weight 210 g/m", warp density 42/25m, weft density 32/25m).
This was impregnated with the following epoxy resin varnish to a resin content of 45% by weight in a conventional manner, and dried to obtain a prepreg.

*Composition of epoxy resin varnish Three sheets of the above prepreg were layered, copper foil with a thickness of 18μ was placed on top and bottom, and this was sent into a double belt press machine equipped with a pressurized cooling device as shown in the figure and press-molded. . The molding conditions were a temperature of 170° C., a pressure of 10 kg/cd, and a belt running speed of 1 pawl/min. In addition, pressurized cooling is performed at a pressure of 1
The test was carried out at a pressure of 5 kg/ad and a temperature of 20° C. or less, and in Example 1, a pressure/cooling roll (water-cooled roll) was used, and in Example 2, a pressure/cooling press was used.

(Comparative Example 1) A metal foil-clad laminate was manufactured in the same manner as in the above example except that pressure cooling after press molding was not performed.

(Comparative Example 2) A laminate having the same structure as the above example was placed between the hot plates for 12 minutes.
A Jii slope was manufactured by the daylight press method in which the sheets were inserted and stacked in 30 stages. The molding conditions are temperature 16
The temperature was 5°C, the pressure was 40 kg/cj, and the time was 120 minutes. After molding, it was cooled in a daylight press to obtain a metal foil-clad laminate.

The surface roughness of the metal foil-clad laminates of Examples and Comparative Examples obtained above in the diagonal direction of the glass cloth was measured using a surface roughness meter.

The above results are shown in Table 1.

As shown in Table 1, in the double belt press method,
In the metal foil clad laminate of the example in which pressure cooling was performed immediately after press forming, the metal foil surface roughness was 4. On or below is achieved,
A laminate with highly excellent smoothness was obtained.

〔Effect of the invention〕

According to the method for producing a metal foil-clad laminate according to the present invention, the surface roughness of the laminate produced by the double belt press method can be improved more than that produced by the daylight press method, making it suitable for surface mounting, etc. This makes it possible to provide printed wiring board materials.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an apparatus used in carrying out the method for manufacturing a metal foil-clad laminate according to the present invention, and FIG. 2 is a perspective view thereof. 1...Endless belt 4...Metal foil 5...
Resin-impregnated base material 8...Metal foil-clad laminate 9...Heat and pressure means 11...Pressure/cooling roll Agent Patent attorney Takehiko Matsumoto Figure 1, Figure 211

Claims (1)

[Claims] 1. A method for manufacturing a metal foil-clad laminate in which a predetermined number of resin-impregnated base materials and metal foil are transferred and sandwiched between a pair of heated endless belts and press-formed, the method comprising: A method for manufacturing a metal foil clad laminate, which comprises cooling the clad laminate while applying pressure immediately after the press forming.