JP2002052558A - Method for producing laminated plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminated plate of good, stable quality at low costs while energy consumption is reduced by continuous molding. SOLUTION: In a method for producing the laminated plate, at least one prepreg which has an unreacted resin layer in the surface layer and a cured central part is moved vertically from above to below, after metal foil or a metal film is laid at least on one side of the prepreg to overlap each other, preheated at a temperature higher than the temperature of heating rolls before it is inserted between the rolls, inserted from above between the rolls, and laminated/molded.

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 becoming stronger, but price competition is fierce. In particular, a glass cloth base epoxy resin laminate used for printed circuit boards or a glass non-woven fabric is used as an intermediate layer. As for the laminates using glass woven fabric as the surface layer substrate as the base material, reduction of the price is a major issue in any case. 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, in multi-stage batch press, hot plate,
An enormous amount of heat is required to heat and cool a jig necessary for forming a laminated plate such as a mirror plate and a cushion material, and it is difficult to cope with energy saving demanded in recent years.

Conventionally, horizontal continuous belt presses and the like have been developed as laminated sheets having low quality variation and energy-saving equipment. However, there is a problem that pressure unevenness and temperature unevenness easily occur when sandwiched between belts, or due to gravity. Due to the difference in the vertical direction and the angle of entry of the material, there is a difference between the front and back due to the moldability (especially the occurrence of voids) and the adhesive strength of the copper foil. There was a big problem.

[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 for heating and cooling an apparatus necessary for molding the slab. In addition, in the conventional horizontal continuous press, due to pressure differences due to gravity, temperature variations, tension variations in the material, etc., molding defects (voids), reduced copper foil adhesion, reduced dimensional stability, warpage, etc. There was a problem. The present invention solves the problems of the conventional laminate molding method, eliminates the internal residual stress in the laminate molding, improves the dimensional stability of the laminate, further improves the formability without voids, and achieves energy saving. An object of the present invention is to provide an inexpensive method for manufacturing a laminate.

[0006]

According to the present invention, one or more prepregs having an unreacted resin layer on a surface layer and a center layer in a cured state are moved vertically from above to below, After laminating a metal foil or film on one or both sides, pre-heat to a temperature higher than the temperature of the heating roll before inserting it between the heating rolls, then insert from above between the heating rolls to form a laminate. The present invention relates to a method for manufacturing a laminated board, which is a feature of the present invention.

[0007] The prepreg used in the present invention is obtained by adhering a resin to a sheet-like fiber base material. The form of the resin when the resin is adhered to the base material is usually a liquid, particularly a varnish dissolved in a solvent, but a powdery resin,
Alternatively, the solid resin may be heated and melted.

Examples of the sheet-like fiber substrate include glass fiber substrates such as glass cloth, glass non-woven cloth and glass paper, woven and non-woven fabrics made of paper and synthetic fibers, metal fibers, carbon fibers, mineral fibers and the like. Woven, non-woven,
Mats and the like may be mentioned, and the raw materials for these substrates may be used alone or as a mixture.

The resin adhered to the sheet-like fiber base material is generally a thermosetting resin, and an epoxy resin, a polyimide resin, a phenol resin, a melamine resin or a modified resin thereof is preferably used. In addition, resins such as a thermoplastic resin and a natural resin are also used, and are not limited thereto. 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 by applying to the upper or lower surface of the sheet-like fiber substrate or the vertical surface. Thereafter, the curing reaction proceeds while the resin is impregnated into the fiber base material by heating. Next, a prepreg used in the present invention is obtained by attaching a resin to both surfaces. The surface layer of the obtained prepreg is uncured, and its resin thickness depends on the surface shape of the metal foil or film to be laminated. For example, in the case of copper foil used for a laminate, the copper foil substrate side (adhesion The surface is usually in the form of irregularities in order to increase the adhesive strength, and it is sufficient that the surface has a thickness that fills the irregularities, and a thickness of 3 to 20 μm is preferable. 3 μm
When the thickness is smaller, it is difficult to attach the resin to a predetermined thickness, and the adhesive strength and the heat resistance are apt to decrease in terms of characteristics. On the other hand, when the thickness is larger than 20 μm, a resin pool is formed at the time of subsequent roll forming, and a void is entangled therein. Also, in this prepreg, the center layer has been hardened,
Since the ratio of uncured resin is significantly reduced, the after-curing time after molding with a roll can be significantly reduced. The prepreg center layer is a state in which the resin is cured, but the cured state is a state in which the prepreg does not substantially flow in the next molding step and the thickness of the prepreg is maintained after molding. The thickness of the center layer is substantially determined by the thickness of the sheet-like fiber base material such as glass cloth, and is usually 50 to 200 μm.

The prepreg obtained as described above is usually wound up once by a winder or the like and then unwound or, as it is, one or a plurality of prepregs are vertically moved from above to below. A metal foil or a film such as a copper foil is laminated on one or both sides. Next, after these are preheated, they are inserted into the space between the heating rolls to form a laminate. In the roll forming of the present invention, it is possible to use a cut prepreg, but it is preferable to form continuously. In this case, 1
Forming between pairs or pairs of rolls. The material of the roll includes metal, rubber and the like. Regarding the temperature of the heating roll, the applicable range is 100 to 200 ° C, and for example, the range of 100 to 160 ° C for an epoxy resin is preferable.

Before lamination molding between heating rolls,
By preheating to a temperature higher than the heating roll in a state where the prepreg and the metal foil or film are superimposed on each other to make the resin have a predetermined melt viscosity, a shortage of heat from the heating roll is compensated for in the subsequent molding by the heating roll, and molding defects ( Particularly, voids) can be prevented. As a method of preheating, the prepreg and the metal foil which have been superimposed are preheated by a preheater such as a far-infrared heater, a hot air drying oven, or a high frequency heating, and the resin of the prepreg is melted to thermally expand the copper foil. The resin melts to a minimum melt viscosity at that temperature in about 30 to 60 seconds after the start of heating, so that contact with a heated roll results in an insufficiently molten state. Therefore, the prepreg is heated to a temperature higher than the temperature of the heating roll in advance to make the resin have a predetermined melt viscosity, whereby the roll can be formed in a stable state. Here, when heating to a temperature higher than the heating roll temperature, the temperature difference with respect to the heating roll is preferably 20 to 50 ° C. If the temperature is lower than 20 ° C., the molten state of the resin becomes insufficient and molding failure may occur. If the temperature is higher than 50 ° C., the viscosity of the resin increases due to the reaction of the resin, and molding failure tends to occur. The temperature of the preheating is, for example,
In the case of an epoxy resin, the temperature is usually about 120 to 180 ° C.

Hereinafter, the method for producing a laminate of the present invention will be described.
A typical example of the laminating process will be described for each process sequentially with reference to the drawings. (Supply of prepreg) The prepreg 2 is unwound from the prepreg supply unit 1 and supplied to the heating roll while being transferred from above to below. (Metal foil supply) The metal foil 4 is unwound from the metal foil supply unit 3 and supplied to both sides (or one side) of the prepreg. (Overlap Roll) The prepreg 2 and the metal foil 4 are overlaid by the overlay roll 5. The overlapping roll 5 may be heated at normal temperature or in order to heat the metal foil in advance. (Preheating) Laminated prepreg 2 and metal foil 4
Is preheated by a preheater 6 such as a far-infrared heater to melt the resin of the prepreg and thermally expand the copper foil. (Molding by Heating Roll) Lamination forming is performed by passing between one or more pairs of heating rolls 7 from above. (Cutting or Winding) The formed laminate is cut to a required length by a cutting machine 8 or wound around a winding machine 9. (Aftercure) Next, aftercure is performed in a heating and drying oven at 170 to 250 ° C.

[0014]

The present invention will be described below with reference to examples and comparative examples.

Example 1 100 parts by weight of an epoxy resin (brominated epoxy resin Ep5048 manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 675), 5 parts by weight of a curing agent (dicyandiamide), and a curing accelerator (2-ethyl- 1 part by weight of 4-methylimidazole) and 100 parts by weight of methylcellosolve were mixed to obtain a varnish. 100 g /
85g a solid resin content component by immersing the glass cloth m ²
/ M ^{2, and} then heated in a drier at 170 ° C. for 6 minutes to advance the reaction of the resin. Thereafter, the resin was applied so as to adhere to both surfaces in a solid content of 8 g / m ² (about 7 μm in thickness) and dried in a dryer at 150 ° C. for 3 minutes. The obtained prepreg was wound on a winder. In this prepreg, the resin of the center layer was cured to such an extent that it did not substantially flow, and the resin of the surface layer was uncured.

The wound prepreg is vertically transferred from above to below as shown in FIG.
m of copper foil was supplied and superimposed, and then preheated from both sides to 170 ° C. using far-infrared heater preheaters. Subsequently, a roll heated to 120 ° C. (gap 0.1 mm)
Heat and pressure molding was performed by inserting from above into the gap. Thereafter, after-curing was performed at 180 ° C. for 15 minutes to prepare a double-sided copper-clad laminate having a thickness of 0.1 mm.

Comparative Example 1 100 g / m ^{2 of the} above varnish
Immersed in a glass cloth and the resin content was 100 g / solid
After impregnating so as to adhere m ^2, it was dried in a dryer at 170 ° C. for 3 minutes. The obtained prepreg was wound on a winder. The wound prepreg was vertically transferred from above to below as shown in FIG.
And then pre-heated from both sides to 170 ° C. using far infrared heater preheaters. Subsequently, it was heated and pressed by being inserted from above into a roll (gap: 0.1 mm) heated to 120 ° C. Thereafter, after-curing was performed at 180 ° C. for 15 minutes to prepare a double-sided copper-clad laminate having a thickness of 0.1 mm.

(Comparative Example 2) The prepreg obtained in Comparative Example 1 was cut into a predetermined length, and the upper and lower surfaces thereof were 18 μm thick.
Are placed between the mirror-surfaced plates, 10 sets of these are laminated, and heated and pressed at a temperature of 165 ° C. and a pressure of 8 kg / cm ² for 90 minutes to form a 0.1 mm-thick double-sided copper-clad laminate. Produced.

The appearance, moldability (presence or absence of voids), plate thickness, and various properties of each of the copper-clad laminates obtained as described above were measured.

[0020]

[Table 1]

(Measurement method) Appearance: Observed visually. 2. Formability: The copper foil of the copper-clad laminate was etched to observe the presence of voids in the resin layer and the strand. 3. Laminate thickness: Cut out to a size of 500 × 600 mm, the thickness was measured at 42 locations with a micrometer, and the average value, standard deviation, and the difference (R) between the maximum value and the minimum value were determined. 4. Copper foil peel strength: Measured according to JIS C6481. 5. Solder heat resistance: 50 × 50 mm test pieces (three test pieces each) were subjected to (1) boiling water treatment for 2 hours and (2) 121 ° C. pressure cooker treatment for 1 hour, and then to a 260 ° C. solder bath. For 30 seconds, and the presence or absence of blisters was observed. ：: No blistering in all three, ×: Blistering in one to three. Insulation resistance: Measured according to JIS C6481. The test piece was previously subjected to a moisture absorption treatment (96 ° C., 20 ° C., 65% humidity).

According to the results shown in Table 1, the copper-clad laminate obtained in Example 1 has almost no voids and has good moldability.
It can be seen that the thickness accuracy is also excellent. Other characteristics of the laminate are also equal to or higher than those of the conventional multi-stage press system.

[0023]

According to the method of the present invention, a metal foil is formed by moving a prepreg having a resin layer adhered to a sheet-like fiber base material, an unreacted resin layer on a surface layer and a hardened center portion in a vertical direction. Alternatively, the film is characterized in that the films are laminated and inserted through a heating roll through a preheating step to form a laminate. Therefore, the molding equipment is reduced in size, and as a result, the amount of fuel used is reduced. As a result, it is possible to achieve a reduction in energy costs, a reduction in air pollution caused by exhaust gas from the heat source equipment, and resource saving. Also, during the production of the laminate, since the prepreg is moved in the vertical direction, the tension of the prepreg and the like is uniform since there is no influence of gravity as compared with the conventional continuous molding by the lateral movement, so that the laminate is extremely warped. Preliminary heating is carried out after laminating the prepreg and the metal foil or film, and then forming with a heating roll, eliminating voids and achieving extremely stable thickness accuracy and obtaining a high quality laminated board be able to. Further, since the laminated plate can be cut to an arbitrary length by roll forming, a portion of the end material such as an ear which has conventionally occurred is reduced, and the yield is improved. 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.

[Description of Signs] 1 Pre-preg supply unit 2 Pre-preg 3 Metal foil supply unit 4 Metal foil 5 Laminating roll 6 Preheater 7 Heating roll 8 Cutting machine 9 Winding machine

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 105: 06 B29K 105: 06 B29L 9:00 B29L 9:00 F term (Reference) 4F100 AB17C AB17D AB33C AB33D AG00 AK01C AK01D AK53 BA03 BA05 BA06 BA10C BA10D DG12 DH01A DH01B DH01E GB43 JL02 4F204 AC03 AD03 AD05 AD20 AD29 AD35 AG03 AH36 AK07 FA08 FA16 FB02 FB13 FB20 FB24 FE06 FFGN FHN

Claims (1)

[Claims] 1. A method according to claim 1, wherein one or more of the prepregs having an unreacted resin layer in the surface layer and having a cured state in the center layer are moved vertically from above to below, and a metal foil or After laminating the films, pre-heating to a temperature higher than the temperature of the heating roll before inserting between the heating rolls, and then inserting between the heating rolls from above to perform laminating, characterized in that: .