JPH03110159A - Production of laminated sheet - Google Patents

Abstract

PURPOSE:To produce a laminated sheet with excellent high frequency characteristics in a continuous technique and to improve dimensional stability by laminating prepregs made of a fluororesin fabric as a base material in layers, performing laminate molding thereof, cutting it into a specified dimension, performing aftercuring thereof and thereafter quenching it. CONSTITUTION:A prepreg 1 is prepd. in continuous lengths by using a fabric of a fluororesin as a base material and. The prepregs 1 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 1 and if necessary, a metal foil 10 are put in layers is continuously transferred, it is preheated and continuously introduced in a double belt 2. The laminate 5 is passed through the double belt 2 and heat-pressed by means of press-heating apparatus 11 between upper and lower endless belts 3 and 4 to obtain a laminated sheet A. The laminated sheet A cut in a specified dimension is introduced in an aftercuring oven to perform aftercuring thereof and the laminated sheet A is quenched just after it is taken out of the aftercuring oven.

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 plastic cloth as a base material and impregnating it with a thermosetting resin and drying it.The prepreg is then cut into a predetermined size, and a plurality of sheets are cut into a predetermined size. Layer sheets of prepreg and metal foil such as copper foil as necessary, set 10 to 14 stacks of these in a press via plates, and perform multi-stage lamination molding by heating and pressing for a predetermined period of time using upper and lower heating plates. Manufacturing is carried out by this. However, when a laminate is manufactured by multi-stage lamination molding in this manner, the work efficiency is poor due to batch 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 continuous molding of laminated plates. 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 molding for 1 to 2 hours. 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-mentioned truth, and it is possible to manufacture a laminate with excellent high frequency characteristics by a continuous method,
In addition, it is an object of the present invention to provide a method for manufacturing a laminate that can improve dimensional stability.

[Means to solve the problem]

The method for manufacturing a laminate according to the present invention involves continuously feeding a long prepreg 1 prepared using fluororesin cloth as a base material, and stacking a required number of prepregs 1, 1...
It is characterized in that it is continuously fed into a double belt 2 to be laminated and formed, and after being cut into a predetermined size, it is after-cured and rapidly cooled after footer curing. The present invention will be explained in detail below. The prepreg 1 is prepared as a long prepreg by impregnating a base material with a resin varnish and drying it. In the present invention, a fluororesin (polytetrafluoroethylene) cloth is used as the base material. The fluororesin cloth is made as a woven or non-woven fabric of fluororesin fibers, and for example, a polyurethane cloth commercially available from Daikin Industries, Ltd. can be used. Further, in the present invention, any resin can be used to impregnate the fluororesin cloth, but thermosetting resins such as epoxy resins are particularly preferred. Then, as shown in FIG. 1, this prepreg 1 is unwound from a roll, a predetermined number of sheets are continuously fed through an idle roll 6, and each prepreg 1 is continuously overlapped by a stacking roll 7. . On the other hand, a metal foil 10 such as a copper foil 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. When manufacturing a double-sided metal foil-clad laminate, two sheets of metal 9i10 are used to overlap the same amount of the outer layer of the stacked prepreg 1, and when manufacturing a single-sided metal foil-clad laminate, one The metal foil 10 is layered only on the outermost layer, and a film such as a 7-layer resin film that can withstand temperatures of 150° C. or more and has excellent high frequency characteristics is layered on the other outermost layer. Here, any metal foil 10 can be used, such as one coated with an adhesive or 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 and metal foils 10 are piled up as necessary, the laminate 5 is preheated to melt the resin contained in the prepreg 1, and then , the laminate 5 is successively introduced into a double belt 2 constituted by upper and lower endless belts 3.4 which are continuously driven by a drum 9. 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 dielectrically heated, the heating temperature is higher inside the prepreg 1 rather than on the surface, and as in the case of external heating using electric heating, the surface is heated to a high temperature and the curing reaction of the resin on the surface of the prepreg 1 is slowed down. It is possible to reduce the occurrence of voids in the laminate due to the air bubbles not being able to escape from the prepreg 1 even when pressurized by the double belt 2. is passed through the double belt 2 to pressurize the laminate 5 between the upper and lower endless belts 3.4.
, 4 is provided with a pressure/heating device 11.11 such as a heating plate, which can heat and press the laminate 5 to harden the resin of the prepreg 1. and a plurality of prepregs 1 and metal 9i10
This is a method for laminating and bonding. Pressure is 20 kg/e
It is carried out at a low pressure of about ta2 to 30 kg/cm2 or less, and in some cases it may be 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. In lamination molding using the continuous method using the double belt 2 as described above, the 7-component resin cloth that is the base material of the prepreg 1 has excellent high frequency characteristics because the fluororesin that is the material has a low dielectric constant. Therefore, it has high high frequency characteristics, so there is no need to use a resin with excellent high frequency characteristics as the impregnating resin, and even if you use a resin commonly used for laminates such as epoxy resin, It is possible to manufacture a laminate A with a high Therefore, there is no need for long-time molding at high temperatures, which is required when using resin with high high-frequency characteristics, and the conventional continuous method using double belts 2 can be used as is to produce laminate A with high high-frequency characteristics. This makes it possible to manufacture. However, in the continuous construction method using double belt 2, heating can only be performed for a short time with low pressure (at least contact pressure in some cases), so the curing of the resin may be insufficient due to insufficient heat, and the laminate A The dimensional stability is not as good as that produced by multi-stage lamination molding, and there is a risk of significant deformation such as warping. Therefore, in the present invention, the laminate A that has been continuously formed using the double belt 2 and then cut into a predetermined size is introduced into an after-cure furnace to perform after-curing, and the laminate A that has been after-cured in this way is then used as a footer cure. I try to quickly cool it down immediately after taking it out of the furnace. By performing after-curing, the dimensional stability of laminate A can be increased by compensating for the lack of heat in the resin of laminate A, and furthermore, by rapidly cooling after the after-curing, the crystallinity of the resin of laminate A can be increased and the laminated board can be laminated. The dimensional stability of plate A can be further improved. When performing footer curing, the heating temperature is preferably set to a temperature approximately 10 to 50° C. lower than the heating temperature by the double belt 2, and the heating time is preferably about the same as the forming time by the double belt 2. Further, it is preferable to rapidly cool the laminate A after the after-cure by immersing it in water (at a room temperature of about 25°C), and it is preferable to take it out of the water after it has been cooled to 60°C or less. preferable.

【Example】

The present invention will be explained in detail below using examples. 520 parts by weight of a brominated epoxy resin with a K19 epoxy equivalent of 520, 9 parts by weight of dicyandiamide, 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. Then, using a 0°1 mm thick polyurethane cloth (polytetrafluoro-roethylene resin woven fabric manufactured by Daikin Industries, Ltd.) as a base material, the resin content was reduced to 50% by weight by impregnating it with the above epoxy resin varnish and drying it. A prepreg with a del time of 180 seconds at 160°C was obtained. Next, using this prepreg, a laminate was manufactured using the continuous construction method shown in FIG. That is, prepreg 8
At the same time, copper foil with a thickness of 0°035 am is placed on top and bottom of the stack, and a high frequency dielectric heating device with an oscillation frequency of 13.56 MHz is used to heat the center of the laminate to 120 to 125°C.
Heat the prepreg resin to a molten state and introduce it into a double belt rotating at a speed of 0.1+o/min. Laminate molding was carried out by passing the material through, and a laminate plate with copper cladding on both sides was obtained by cutting the material into a size of 1+*X1. Next, the laminate immediately after being cut in this manner was placed in a footer cure furnace at 150° C. for 20 minutes to perform after-curing. Put it in the footer cure furnace like this 2
After 0 minutes had elapsed, the laminate was taken out of the footer cure furnace and put into water at 25°C for quenching, and when the laminate had cooled to 60°C, it was taken out of the water. Female 19 A double-sided copper-clad laminate was formed using a continuous method using double belts in the same manner as in the above example, and was left to cool at room temperature without after-curing to obtain Comparative Example 1. For K1, a double-sided copper-clad laminate was formed using a continuous method using a double belt in the same manner as in the above example, and after-cured in the same manner as in the example.The laminate was taken out of the after-cure furnace and left at room temperature. Comparative example 2 is the one that was left to cool.
And so. 1” - 205g/m of the epoxy resin varnish used in the above example
By impregnating the glass cloth in Step 2 and drying it, the resin content was 45% by weight and the gel time at 160°C was 180°C.
prepreg was obtained. This prepreg was cut into regular dimensions of lm x 1m, 8 sheets were stacked together, and copper foil with a thickness of 0.035II11 was layered on top and bottom, and this was sandwiched between stainless steel plates with a thickness of 1.5mm, and a multistage hydraulic press was used. A double-sided copper-clad laminate was obtained by inserting the laminate between hot platens and heating and pressing at 170° C. for 25 minutes to perform multi-stage laminate molding. Regarding the laminates of the above Examples and Comparative Examples 1 to 3, JI
The dielectric constant was measured based on SC6481. Also,
In order to measure dimensional stability, the maximum amount of diagonal warp deformation of each laminate was measured. These results are shown in the table below. As seen in the results in the table, the prepreg of Example using fluororesin cloth as the base material has a lower dielectric constant and superior high frequency characteristics than Comparative Example 3 that uses plus cloth as the base material. This is confirmed. In addition, by performing after-curing and rapid cooling, the dimensional stability of the example was significantly improved compared to that of Comparative Example 1, which was not subjected to after-curing. It is confirmed that the dimensional stability can be improved compared to that of Comparative Example 2 which does not contain the above.

【Effect of the invention】

As described above, in the present invention, a long prepreg prepared using fluororesin cloth as a base material is continuously fed, a required number of prepregs are stacked, and the sheets are continuously fed to a double belt to be laminated. I decided to mold it, so
Fluororesin cloth, which is the base material for prepreg, has a low dielectric constant and excellent high-frequency properties, so there is no need to use a resin with excellent high-frequency properties as the impregnating resin, which is commonly used for laminates such as epoxy resin. It is possible to manufacture a laminate with high high frequency characteristics even by using
It is possible to manufacture laminates with high high frequency characteristics using the conventional continuous method that requires long-term forming at high temperatures.Moreover, after forming the laminate and cutting it to the specified size, Since the footer is cured and rapidly cooled after the footer cure, the after-cure compensates for the lack of heat in the resin in the laminate, and the rapid cooling increases the crystallization of the resin in the laminate, which improves the dimensions of the laminate. This can improve stability.

[Brief explanation of drawings]

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

Claims (1)

[Claims] (1) A long prepreg prepared using fluororesin cloth as a base material was continuously fed, the required number of prepregs were stacked together, and this was continuously fed to a double belt to form a laminate, and then cut into a predetermined size. A method for manufacturing a laminate, which is characterized by performing after-curing and rapidly cooling after the after-curing.