JP2001138437A - Method for manufacturing laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable laminate having good quality including moldability with reduced energy consumption at a low cost by continuous molding. SOLUTION: The method for manufacturing a laminate 5 comprises the steps of superposing metal foils 3 or films on one or both surfaces of one or a plurality of prepregs 1 each made by adhering a resin to a sheet-like fiber base material, passing the superposed laminate between rolls 4 heated in a vacuum atmosphere of 500 Torr or less, laminating and molding the laminate. In this case, it is preferable to preheat the laminate in a vacuum state of 500 Torr or less before passing the prepreg 1 between the rolls 4. In these cases, the prepreg 1 is vertically moved from above to below.

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 laminated board, and more particularly to a method for continuously producing a laminated board suitable for a printed circuit board used for electric equipment, electronic equipment, communication equipment and the like.

[0002]

2. Description of the Related Art As for printed circuit boards, demands for miniaturization and high functionality are increasing, but price competition is intense. In particular, laminated boards for multilayer printed circuit boards used for printed circuit boards and epoxy resin laminates for glass cloth base are used. The cost reduction has become a major issue for any plate or laminate using a glass nonwoven fabric as an intermediate layer substrate and a glass woven fabric as a surface layer substrate. In recent years, digitalization has progressed in electrical equipment, electronic equipment, communication equipment, and the like, and a stable impedance on a printed circuit board has been required, and accordingly, a copper-clad laminate, which is a raw material of a printed circuit board, has been required. Sheet thickness accuracy has been required.

In the case of laminating and forming a laminate used for a printed circuit board as described above, a multi-stage batch in which a number of copper foils, prepregs, mirror plates and the like are stacked between hot plates and heated and pressed. Presses are common. However, in such a multi-stage press, since the heat history applied to each laminate during lamination molding differs depending on the position of each laminate in the hot plate, there is a difference in quality such as moldability, warpage, and dimensional change rate. It was difficult to supply products with low quality variation. Furthermore, since the laminated plate is formed at a high pressure of ^{20 to} 100 kg / cm ² , there is a problem that the thickness accuracy is insufficient due to the flow of the resin. In addition, the multi-stage batch press requires an enormous amount of heat to heat and cool a jig required for forming a laminated plate such as a hot plate, a mirror surface plate, and a cushioning material. This facility is difficult to handle.

Conventionally, horizontal continuous belt presses, continuous roll presses, and the like have been developed as devices for manufacturing laminated boards with little quality variation or as devices that can save energy. As shown in an example in FIG. 3, in forming a laminate by a continuous roll press, a prepreg 21 is unwound and, if necessary, preheated by a heating device 22 to supply a metal foil or a film 23 from both upper and lower sides of the prepreg. Then, they are superposed by one pair (or a plurality of pairs) of heating rolls 24, and heated and pressed to form a laminated plate 25. Thereafter, the sheet is cut by a cutting machine 26 or wound around a winding machine 27. The laminate 25 is usually after-baked before or after cutting. However, in any of these systems, when the prepreg is sandwiched between the rolls or the belt, there is a problem that a resin pool is generated, and there is a problem that good molding cannot be performed due to entrapment of voids. In the case of belt presses, pressure unevenness and temperature unevenness tend to occur when sandwiched, and in horizontal belt presses and roll presses, due to the difference in vertical direction due to gravity and the difference in material entry angle, moldability and copper foil adhesion There is a problem in that there is a difference between the front and back surfaces due to force or the like, and there is a large warp or dimensional change due to a difference in the tension of the copper foil or the base material.

[0005]

As described above, in the conventional multi-stage press machine, there is a large variation in the quality such as formability, warpage, dimensional change, and plate thickness due to simultaneous heating of a large number of sheets. There is a problem that an enormous amount of heat is required to heat and cool a device necessary for molding the slab. In addition, in conventional horizontal continuous belt presses and continuous roll presses, poor molding due to entrainment of voids, pressure differences due to gravity, temperature variations, variations in tension to the material, etc. There were problems such as reduction and warpage. An object of the present invention is to solve the problems of the conventional laminate forming method, eliminate residual voids in the laminate forming, improve the dimensional stability of the laminate, and provide an inexpensive laminate manufacturing method by energy saving. It is in.

[0006]

According to the present invention, a metal foil or a film is laminated on one or both sides of one or more prepregs comprising a sheet-like fiber base material and a resin, and the prepreg has a thickness of 500 tons.
The present invention relates to a method for manufacturing a laminated plate, comprising passing between heated rolls in a vacuum atmosphere at or below orr to form a laminate, and further, before passing a prepreg between rolls in a vacuum atmosphere at 500 torr or less. In this case, the present invention relates to a method for manufacturing a laminate in which the prepreg is preferably moved vertically from above to below.

In the present invention, the sheet-like fiber base material includes glass fiber base materials such as glass cloth, glass non-woven cloth and glass paper, as well as woven and non-woven fabrics made of paper, synthetic fibers, etc., metal fibers and carbon fibers. And woven fabrics, nonwoven fabrics, mats and the like made of mineral fibers, etc., and these base materials may be used alone or in combination. As a resin to be attached to these sheet-like fiber base materials for producing a prepreg, generally, a thermosetting resin is preferable, and an epoxy resin, a polyimide resin, a phenol resin, a melamine resin or a modified resin thereof is preferable. Although used, other resins such as a thermoplastic resin and a natural resin are also used, and are not limited thereto. The form of the resin when the resin is adhered to the base material is usually a varnish dissolved in a liquid, particularly a solvent, but may be a powdery resin or a state in which a solid resin is heated and melted. In the case of a thermosetting resin, a curing agent and a curing accelerator are added as necessary. Further, a filler, a coloring agent, and a reinforcing material can be compounded in the resin. When an inorganic filler is added as the filler, characteristics such as tracking resistance, heat resistance, and a decrease in coefficient of thermal expansion can be imparted. Such inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, talc, wollastonite, alumina, silica, unfired clay, fired clay, barium sulfate and the like.

Next, the obtained resin is uniformly applied on a sheet-like fiber base material. The amount of the resin adhered at this time varies depending on the fiber material, properties, and weight (per unit area) of the sheet-like fiber base material, but is usually 40 to 40% of the weight of the sheet-like fiber base material.
It is about 60%. However, in the case of adhering to both surfaces of the base material, it is preferable that approximately half the amount of the adhering amount be adhered to one surface. The method for adhering the resin to the sheet-like fiber substrate is not particularly limited, as long as the resin adheres well, such as a method of dipping the substrate in a resin varnish, an application method using various coaters, or a spraying method using a spray. Further, especially when the resin is solvent-free, the sheet-like fiber base material may be pre-heated. In this case, when the resin is applied to the sheet-like fiber base material, the base material is horizontal. May also be vertical. Therefore, it can be attached to the upper or lower surface of the sheet-like fiber substrate or the vertical surface by coating. The prepreg is obtained by the subsequent heating. The prepreg obtained as described above is usually once wound by a winder or the like. Thereafter, it is unwound and one or more sheets are stacked. The prepreg is not wound up,
One sheet or a plurality of sheets may be directly stacked.

Next, the prepreg is laminated and formed by passing between prepregs in a vacuum atmosphere of 500 torr or less. As the degree of vacuum is closer to 0 torr, the formability is improved. However, if the degree of vacuum is 500 torr or less, it is effective in removing voids and the like. Further, the prepreg is preferably pre-heated with far infrared rays or the like in a vacuum atmosphere of 500 torr or less before passing between the heating rolls, so that molding failure due to insufficient heat of the heating roll at the time of molding can be prevented. The preheating temperature is, for example, usually about 120 to 180 ° C. for an epoxy resin and usually about 170 to 240 ° C. for a polyimide resin. In the present invention, roll forming is performed through one or more pairs of heated rolls. It is preferable that the prepreg be passed between the rolls in a substantially vertical direction from above to below, in order to minimize bias in pressure due to gravity. The material of the roll is usually metal, rubber, ceramic or the like. In roll forming, it is possible to use a cut prepreg, but it is preferable to form continuously. Regarding the temperature of the roll, the applicable range is 110 to 280 ° C. For example, the range of 150 to 220 ° C for epoxy resin and the range of 210 to 280 ° C for polyimide resin is preferable.

Hereinafter, the method for producing a laminate of the present invention will be described.
A typical example of the lamination molding process will be sequentially described for each process with reference to FIG. (Supply of prepreg) The wound prepreg 1 is unwound, transferred from above to below, and transferred to a molding box 8 under a vacuum atmosphere on the way. Preheating is preferably performed by the heating device 2 in a vacuum atmosphere. (Supply of metal foil) The rolled-up metal foil 3 is unwound, transferred into a molding box 8 under a vacuum atmosphere, and supplied to both sides (or one side) of the prepreg 1. (Heating roll) In a forming box 8 in a vacuum atmosphere, the metal foil 4 is superimposed on the prepreg 1 and a pair (or a plurality of pairs) of heating rolls 4 are passed from above to form a laminate. (After-baking and Cutting or Winding) The formed laminated plate 5 is cut to a required length by a cutting machine 6 or wound around a winding machine 7. Laminates are usually after-baked before or after cutting.

[0011]

The present invention will be described below with reference to examples and comparative examples. The amounts are in parts by weight.

Example 1 100 parts of an epoxy resin (brominated epoxy resin Ep5048, epoxy equivalent 675, manufactured by Yuka Shell Epoxy Co., Ltd.)
A varnish was obtained by mixing 5 parts of a curing agent (dicyandiamide), 1 part of a curing accelerator (2-ethyl-4-methylimidazole) and 100 parts of methylcellosolve. A glass cloth of 100 g / m ² was immersed in the obtained varnish to impregnate the resin so that the solid content was 100 g / m ^2.
After drying in a dryer at 0 ° C. for 3 minutes, the obtained prepreg was wound up on a winder. This wound prepreg,
As shown in FIG. 1 (however, no preheating is performed), the wafer is transferred substantially vertically downward from above into a forming box decompressed to 60 torr, and copper foil having a thickness of 18 μm is supplied to both sides of the prepreg at 200 ° C. Was heated and pressed between a pair of heating rolls (gap: 0.1 mm) heated to form a laminate.
After cutting to a predetermined length, after-curing was performed at 180 ° C. for 60 minutes to produce a double-sided copper-clad laminate having a thickness of 0.1 mm.

Example 2 As shown in FIG. 1, a prepreg prepared in the same manner as in Example 1 was transferred almost vertically downward from above into a molding box reduced in pressure to 60 torr, and the prepreg temperature was set to 160 ° C. Preheated with a far-infrared ray device, and further supplied copper foil with a thickness of 18 μm on both sides of the prepreg at 200 ° C.
Was heated and pressed between a pair of heating rolls (gap: 0.1 mm) heated to form a laminate. After cutting to a predetermined length, after-curing was performed at 180 ° C. for 60 minutes to produce a double-sided copper-clad laminate having a thickness of 0.1 mm.

Comparative Example 1 A prepreg prepared in the same manner as in Example 1 was transported almost vertically downward from above, as shown in FIG. 2 (but without preheating), and copper of 18 μm thickness was placed on both sides thereof. The foil was supplied and heated and pressed between a pair of heating rolls (gap 0.1 mm) heated to 200 ° C. at normal pressure to form a laminate. After cutting to a predetermined length, after-curing was performed at 180 ° C. for 60 minutes to produce a double-sided copper-clad laminate having a thickness of 0.1 mm.

Comparative Example 2 A prepreg prepared in the same manner as in Example 1 was horizontally transferred as shown in FIG. 3 (but without preheating), and a copper foil having a thickness of 18 μm was supplied from both upper and lower sides. , 2 at normal pressure
A pair of heating rolls heated to 00 ° C. (gap 0.1 m
Heating and pressurizing was performed during m) to form a laminate. After cutting to a predetermined length, after-curing was performed at 180 ° C. for 60 minutes to produce a double-sided copper-clad laminate having a thickness of 0.1 mm.

Comparative Example 3 A prepreg produced in the same manner as in Example 1 was cut into a predetermined length, and copper foil having a thickness of 18 μm was superposed on the upper and lower surfaces thereof, and placed between mirror plates. ^They were superposed and heated and pressed at a temperature of 165 ° C. and a pressure of 8 kg / cm ² for 90 minutes to produce a double-sided copper-clad laminate.

The formability of each of the copper-clad laminates obtained as described above was evaluated, and properties such as dimensional change, copper foil peeling strength and solder heat resistance were measured. Further, the energy cost required for molding was determined. Table 1 shows the results.

[0018]

[Table 1]

(Measurement method) Energy cost: The amount of fuel used at the time of lamination molding was determined as a ratio to Comparative Example 3. 2. Formability: The copper foil of the copper-clad laminate is etched, and the presence or absence of voids is visually evaluated. 3. Dimensional change rate: The dimensional change rate of the hole interval after heating a test piece of a copper-clad laminate having a hole interval of 250 mm at 170 ° C. for 30 minutes was measured. 4. Copper foil peel strength: Measured according to JIS C6481. 5. Solder heat resistance: A laminate of 50 × 50 mm square was converted to 260
The sample was floated in a solder bath at a temperature of 3 ° C. for 3 minutes, and the presence or absence of blister was measured. 6. Insulation resistance: Measured according to JIS C6481.

[0020]

The method of the present invention is characterized in that a prepreg is supplied between heating rolls in a vacuum atmosphere, and the laminate is formed by the vacuum and the heating rolls. Therefore, by performing molding in a vacuum atmosphere, there is no void generated during conventional molding, and the quality of the laminated board is improved. By moving the prepreg in the vertical direction, the tension on the prepreg and the like becomes uniform without the influence of gravity as compared with the continuous molding by the conventional horizontal movement, so that the quality of the laminated board is better, such as the warpage is extremely small. Becomes Further, since the laminated plate can be cut to an arbitrary length by the roll press, the end materials such as ears which are conventionally generated are reduced, and the yield is improved. In addition, since the equipment is downsized and the fuel used is reduced, it is possible to achieve a reduction in energy cost, a reduction in air pollution due to exhaust gas from the heat source equipment, and resource saving. Thus, it is excellent in terms of cost reduction of raw materials, equipment, and processes, and is suitable as an industrial method for manufacturing a laminated board.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a manufacturing process of a laminate according to the present invention.

FIG. 2 is a schematic view showing a manufacturing process of a laminate by a vertical continuous roll forming method.

FIG. 3 is a schematic view showing a manufacturing process of a laminated board by a conventional horizontal continuous roll forming method.

[Explanation of symbols]

 1,11,21 Prepreg 2,12,22 Preheating device 3,13,23 Metal foil or film 4,14,24 Heating roll 5,15,25 Laminate 6,16,26 Cutting machine 7,17,27 winding Removal machine 8 Vacuum atmosphere forming box

Claims (3)

[Claims] 1. A prepreg composed of a sheet-like fiber base material and a resin, a metal foil or a film is superimposed on one or both surfaces of one or a plurality of prepregs, and passed between heated rolls in a vacuum atmosphere of 500 torr or less. A method for producing a laminate, comprising forming. 2. The method according to claim 1, wherein the prepreg is preheated in a vacuum atmosphere of 500 torr or less before passing between the rolls. 3. The method according to claim 1, wherein the prepreg is moved vertically from above to below.