JPH03110152A - Production of laminated sheet - Google Patents

Abstract

PURPOSE:To make it possible to produce a laminated sheet with excellent high frequency characteristics in a continuous technique by laminating a prepreg made of a fluororesin porous sheet as a base material and a prepreg made of a glass fabric as a base material in layers, feeding continuously them in a double belt and performing laminate molding thereof. CONSTITUTION:A prepreg 1a is prepd. by using a porous sheet of a fluororesin and a prepreg 1b is prepd. by using a glass fabric as a base material. These two prepregs 1a and 1b are used in combination and are prepd. each in continuous lengths. The prepregs 1a and 1b are continuously fed through guide rolls 6 and are continuously put in layers by means of laminating rolls 7. While a laminate 5 wherein the prepregs 1a and 1b and if necessary, a metal foil 10 are put in layers is continuously transferred and preheated, the laminate 5 is continuously introduced in a double belt 2. The laminate 5 is heat-pressed by means of press-heating apparatus 11 between upper and lower endless belts 3 and 4 through the double belt 2 to laminate and adhere the prepregs 1a and 1b and the metal foil 10 to obtain a laminated sheet A.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing a laminated board used as a printed wiring board by a continuous method.

[Conventional technology]

Laminated boards are usually prepared by preparing prepreg by using paper or glass cloth as a base material, impregnating it with thermosetting Ut resin and drying it, and cutting this prepreg into a predetermined size. Multiple sheets of prepreg and metal foil such as copper foil are stacked as necessary, and 10 to 14 sets of these are stacked and set in a press machine via plates, and multi-stage lamination molding is performed by heating and pressing for a predetermined period of time using upper and lower heating plates. Manufacturing is done by doing things. but,
When a laminate is manufactured by multi-stage lamination molding in this manner, the work efficiency is poor due to patch work, and there are many problems in productivity. For this purpose, the present applicant has proposed a method of manufacturing a laminate using a continuous method, such as in Japanese Patent Laid-Open No. 189439/1983. In other words, multiple sheets of long prepreg are piled up and continuously fed, and if necessary, a long metal foil is piled up, and this is continuously passed through a double belt and heated and pressurized by the double belt. ,
This allows the laminated plates to be formed continuously. According to this method, since the laminate can be manufactured by continuous molding operations, the production efficiency is dramatically improved compared to multi-stage lamination molding using patch operations.

[Problem to be solved by the invention]

On the other hand, the frequencies used in fields such as the electronics industry, communications, and computers are being shifted to high-frequency regions, and printed wiring board laminates used in such high-frequency regions are designed to shorten signal propagation delays. Moreover, a smaller dielectric constant is required. For this reason, in order to obtain such a laminate with excellent high frequency characteristics, a resin constituting the laminate, that is, a prepreg resin, which has excellent frequency characteristics, such as a patent application published in 1988-5004, has been developed.
Aromatic polyisocyanates such as No. 34 have been used, but resins with excellent high frequency properties are generally used at high temperatures (250 to 300°C in some cases) for long periods of time (
In some cases, it may be necessary to perform FIR molding at 1 to 2 o'clock. However, when the prepreg is continuously passed through a double belt and molded under heat and pressure, it is impossible to sustain the molding for a long time at high temperatures. It is not possible to manufacture laminates using the above-mentioned continuous method using double belts, and the current situation is that it is difficult to manufacture laminates with excellent high frequency characteristics using the continuous method. . The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a laminate that can manufacture a laminate with excellent high frequency characteristics by a continuous method.

[Means to solve the problem]

The method for manufacturing a laminate according to the present invention includes a long prepreg 1a prepared using a porous fluororesin sheet as a base material, and a long prepreg 1 prepared using glass cloth as a base material.
b and the required number of prepregs 1 while continuously feeding
It is characterized in that at 1 b are superimposed and continuously fed into the double belt 2 to form a laminate. The present invention will be explained in detail below. The prepreg 18t 1 b is prepared as a long prepreg by impregnating a base material with resin varnish and drying it. In the present invention, prepreg 1a is prepared using a porous sheet of fluororesin (polytetrafluoroethylene) as the base material, and prepreg 1b is prepared using glass cloth as the base material. 1a and 1b are used in combination. A porous fluororesin sheet is a sheet of 77 base resin made porous by providing a large number of small pores with an average particle size of about 1 μm or less, and for example, a sheet commercially available from Nitto Denko Corporation can be used. can. Because this sheet is porous with small pores, it can be soaked in thermosetting resin varnish in the same way as paper or glass cloth, allowing the thermosetting resin varnish to penetrate well. Prepreg 1 can be easily prepared using the same method as when cloth is used as a base material. Further, as the glass cloth, a woven cloth or a non-woven cloth of glass fiber can be used. In the present invention, the resin to be impregnated into the 7-component resin porous sheet or the plus cloth is not limited to a specific one and any resin can be used, but thermosetting resins such as epoxy resins are particularly preferred. . As shown in Figure 11, these prepregs 1a, 1
b is unwound from a roll and a predetermined number of prepregs are continuously fed through an idle roll 6, and each prepreg 1 at 1 b is continuously overlapped by a stacking roll 7. At this time, it is preferable to alternately stack prepregs 1a having a fluororesin porous sheet as a base material and prepregs 1b having a plush cloth as a base material. On the other hand, a metal M10 such as a #l whistle is also formed into a long length and wound into a roll, which is unwound and superimposed on the outer surface of the outermost layer of the above-mentioned superimposed prepregs 1 at i b. When manufacturing a double-sided metal foil-clad laminate, prepregs 1 at 1 are prepared by overlapping two metal foils 10.
When producing a single-sided metal foil-covered laminate, the metal foil 10 should be overlapped only on one outermost layer, and the other outermost layer should be covered with a 7-layer resin film, etc. The film should be layered with a film that can withstand temperatures of 150°C or more and has excellent high frequency characteristics. Here, any metal M10 can be used, such as one coated with an adhesive or a foil made of a combination of an aluminum carrier and an ultra-thin copper foil. While continuously feeding the laminate 5 in which a plurality of prepregs 1 a, 1 b and metal foil 10 are stacked as necessary, the laminate 5 is preheated to form prepregs 1 a, 1 b,
After the resin contained in 1b is melted, the drum 9
Upper and lower endless belts continuously driven by 3.4
The laminate 5 is successively introduced into a double belt 2 comprising: Preheating is preferably carried out by dielectrically heating the laminate 5 under no pressure or under contact pressure by passing the laminate 5 through the upper and lower high frequency application electrodes 8, 8. When dielectric heating is performed, the heating temperature becomes higher inside the prepregs 1 at 1 b rather than at the surface, and as in the case of external heating using electric heating, the surface is heated to a high temperature and the surface of the prepregs 1a, 1b is heated to a high temperature. This prevents the curing reaction of the resin from proceeding quickly (and reduces the possibility that air bubbles cannot be completely removed from the prepreg 1 at i b even if pressure is applied with the double belt 2, and voids are included in the laminate. When passing the laminate 5 through the double belt 2 and pressurizing the laminate 5 between the upper and lower endless belts 3 and 4, a pressurizing and heating device 11 such as a heating plate is installed inside each endless belt 3 and 4.
．． 11 is provided, and the laminate 5 can be heated and pressurized by this pressurizing/heating device 11, and the resin of the prepregs 1 at 1 b is cured, and the plurality of prepregs 18t 1 b and metal foils are cured. 10 are laminated and bonded together. Pressure is 20k8/e+n2~30
It is carried out at a low pressure of about kg/ca+2 or less, and in some cases it is carried out at a contact pressure. The laminated body thus laminated is continuously drawn out as the double belt 2 is driven, and is led to the idle roller 12 and cut by the cutter 13, thereby cutting the metal foil into a fixed size. It is possible to obtain a laminate A with a high tension. When performing stack N forming using the continuous method as described above,
The 7-carbon resin porous sheet that is the base material of prepreg 1a has high high frequency properties because the fluororesin that is its material has a low dielectric constant and excellent high frequency properties. It is not necessary to use a resin with excellent high frequency properties as the impregnating resin, and even if a resin commonly used for laminated plates such as epoxy resin is used, the laminate A with high high frequency properties can be manufactured. Therefore, there is no need for long-time molding at high temperatures, which is required when using resin with high high frequency characteristics, and laminate A with high high frequency characteristics can be produced using the conventional continuous method.
This makes it possible to manufacture . In addition, when superimposing each prepreg 1 at 1 b and sending it to the double belt 2, the prepreg 1a whose base material is a fluororesin porous sheet and the prepreg 1 whose base material is glass cloth are stacked.
By alternately stacking the layers B and B, the layer structure of the base material of the laminate A becomes uniform, and it is possible to prevent the laminate A from being warped and deformed as in the case where the base material is uneven.

[Examples] The present invention will be specifically explained below using Examples. 520 parts by weight of a brominated epoxy resin with a monovalent epoxy equivalent of 520, 9 parts by weight of dicyanamide, 2-ethyl-4-
0.5 parts by weight of methyl imiguzole was added and dissolved in a solvent to obtain an epoxy resin varnish. The gel time of this varnish at 160°C was 10 minutes. As a base material, a polytetrafluor-a ethylene porous sheet manufactured by Nitto Denko Corporation (thickness 50μ, porosity 85%,
By impregnating with the above epoxy resin varnish and drying it, the resin content is 50% by weight.
, a prepreg with a gel time of 180 seconds at 160°C was obtained. Further, a lath woven fabric having a thickness of 50 μm was used as a base material, and by impregnating it with the above-mentioned epoxy resin varnish and drying it, a prepreg having an at blood content of 50% by weight and a gel time at 160° C. of 180 seconds was obtained. Next, a laminate was manufactured using the continuous construction method shown in FIG. 1 using five sheets of each prepreg. That is, five sheets of each prepreg were stacked alternately, and copper foils with a thickness of 0.035 mm were stacked on top and bottom of the prepregs, and a high-frequency dielectric heating device with an oscillation frequency of 13.56 MHz was used to heat the central part of the laminate to a temperature of 120 to 125 MHz. ℃, the prepreg resin is melted and introduced into a double belt rotating at a speed of 0.1a+/min, and the pressure is 25℃.
kg/am2 and a temperature of 170° C. for 20 minutes through a double belt to form a laminate, and further cut to a predetermined size to obtain a laminate with copper cladding on both sides. Salt 1: 205 g/m of the epoxy resin varnish used in the above example
By impregnating 2 into lath cloth and drying it, the resin content is 45% by weight and the gel time at 160°C is 180°C.
prepreg was obtained. This prepreg is 50++eX
Cut to a fixed size of 500 mm, stack 8 pieces, and further layer copper foil with a thickness of 0.035IIIll on top and bottom, sandwich this between stainless steel plates with a thickness of 1.5IIIm, and heat it in a multi-stage hydraulic press. A laminate with copper cladding on both sides was obtained by inserting the laminate into a disc opening and performing multi-stage laminate molding by heating and pressurizing at 170° C. for 25 minutes. Regarding the laminates obtained in the above examples and comparative examples, JIS
The dielectric constant was measured based on C6481. In addition, it was measured how many laminates could be manufactured in the example within the time required to manufacture 100 laminates in the comparative example. These results are shown in the table below. As seen in the results in the table, 7
It is confirmed that the example using a porous sheet of 7-component resin has a low dielectric constant and excellent frequency characteristics. It is confirmed that the continuous method using the double belt has high production efficiency. [Effects of the Invention] As described above, in the present invention, a long prepreg prepared using a porous fluororesin sheet as a base material and a long prepreg prepared using a glass cloth as a base material are continuously produced. The required number of sheets of prepreg are stacked together while being fed, and then continuously fed into a double belt for laminated molding.The porous fluororesin sheet, which is the base material of the prepreg, has a low dielectric constant and high frequency characteristics. This makes it possible to produce laminates with excellent high-frequency properties even when using epoxy resin, which is commonly used for laminates, without the need to use a resin with excellent high-frequency properties as the impregnating resin. Therefore, it is possible to manufacture a laminate with high high frequency characteristics using the conventional continuous method without the need for long-term molding at high temperatures.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the apparatus used in the present invention, 1a,
1B is a prepreg, 2 is a double belt, and A is a laminate.

Claims (1)

[Claims] (1) While continuously feeding a long prepreg prepared using a porous fluororesin sheet as a base material and a long prepreg prepared using a glass cloth as a base material, the required number of prepregs are stacked together. A method for producing a laminate, characterized by laminated forming by continuously feeding the plate onto a double belt.