JPS63153110A - Production of paper-phenol laminated sheet - Google Patents

Abstract

PURPOSE:To produce a paper-phenol laminated sheet showing no warpage and twist and excellent characteristics with low cost, by surrounding outside of a laminate consisting of prepregs and cupper foils with a frame on both top and bottom sides of which packings are provided and heating and compressing the laminate while a vacuum atmosphere is being set within this frame. CONSTITUTION:A pile where prepregs prepared by impregnating kraft papers with a flame-retardant phenol resin diluted with methanol are piled up and cupper foils with adhesives are put on both faces of the piled prepregs is placed between pressing hot plates within a metal frame 3 having a structure where silicone rubber packings 2 are adhered on both top and bottom sides of a frame 1 made of aluminum or stainless steel. The laminated sheet is heated and pressed while the inside of the frame is being sucked from vacuum holes 4 by means of a vacuum pump. As a pile consisting of a polurality of paper-phenol prepregs and cupper foils is heated and pressed under a vacuum atmosphere of 10-200 Torr to mold them into an integral body, condensation curing reaction of the phenol resin accompanied with dehydration is accelrated by vacuum sucking and monolithic molding can be done at low temp. under low pressure in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing paper-phenolic laminates.

(Prior Art) In recent years, paper-phenol laminates have been widely used, especially as wiring boards for consumer devices. Traditionally, this paper-phenol laminate is made by stacking multiple sheets of prepreg made by impregnating a paper base material such as kraft paper or cotton linter paper with phenolic resin, and then placing copper foil on each side through an adhesive layer. It is manufactured by integrally molding a laminated product using a large Delight type press at a high temperature of 170 to 190° C. and a high pressure of 100 to 150 kg/aj for 1.5 to 2 hours.

The reason why high temperature and high pressure are applied for a long time during molding is as follows.

In other words, prepreg made by impregnating a paper base material with phenolic resin has a higher degree of impregnation than glass-epoxy prepreg made by impregnating glass cloth with epoxy resin, and resin flow is less likely to occur. In addition, the curing reaction of phenolic resin involves a dehydration condensation reaction while releasing water, and the reaction cannot be carried out unless the condensed water is removed from the system. Because high pressure is applied for a reason, it is difficult for water to be released outside the system. Therefore, it is necessary to accelerate the curing reaction of the phenol resin by applying high temperature for a long time.

(Problems to be solved by the invention) In this way, in the conventional manufacturing method of paper-phenol laminates, forming is performed by applying high temperature and high pressure for a long time, resulting in large energy costs. Not only that, but the laminate tends to warp and twist, and its properties such as dimensional accuracy and punching workability tend to deteriorate.

It is also possible to solve these problems by using a vacuum press, which has traditionally been used to manufacture glass-epoxy laminates, especially multilayer plates, but this method is usually done using an autoclave method or a compact Delight. Productivity is low because heat and pressure are performed using a method. Furthermore, since special molds, equipment, etc. are required to maintain a high degree of vacuum, this method is not suitable for manufacturing paper-phenol laminates for consumer use, which are produced with a focus on low cost and mass production.

The present invention has been made to address these points, and is designed to prevent warping and
It is an object of the present invention to provide a method for producing a paper-phenol laminate having excellent properties without twisting at a low cost.

[Structure of the Invention] (Means for Solving the Problems) The method for producing a paper-phenol laminate of the present invention involves stacking a plurality of sheets of prepreg made by impregnating a paper base material with a phenol resin, After applying one layer of copper foil via an adhesive layer, this is heated and pressurized to form an integral piece.
The method is characterized in that the outer side of the prepreg and copper foil laminate is surrounded by a frame body provided with backings on the top and bottom, and the space between the frames is heated and pressurized with a reduced pressure atmosphere.

In the present invention, the degree of reduced pressure (
For the following reason, the degree of vacuum during vacuum forming of glass-epoxy laminates and multilayer plates does not need to be as high as 0 to 20 Torr, and is preferably in the range of 10 to 200 Torr.

In other words, in the production of paper-phenol laminates, the impregnability of phenol resin at the prepreg stage is far superior to that of glass-epoxy prepreg, and there is almost no risk of voids occurring after molding. There is no need to raise the degree and remove voids. On the contrary, if the degree of vacuum during molding is increased too much, the curing reaction of the phenol resin will proceed too much, which may cause cracks, chipping, etc. during punching or shearing processing.
It is desirable to maintain the degree of vacuum at ~200 Torr.

Therefore, in the present invention, there is no need to use special equipment to maintain a high degree of vacuum during the heating, pressurizing, and molding processes.
For example, a desired degree of pressure reduction can be maintained by using a metal frame with a rubber backing for sealing attached, and by reducing the pressure inside this frame with a normal vacuum pump.

(Function) In the method of the present invention, a plurality of sheets of paper-phenol, prepreg, and copper foil are stacked at 10 to 200 To
Since it is heated and pressurized and molded into one piece in the reduced pressure atmosphere of RR, the condensation curing reaction of the phenol resin accompanied by dehydration is promoted by vacuum suction, and it can be molded into one piece at a lower temperature and lower pressure in a shorter time than with conventional methods. I can do it. Therefore, not only the energy cost is reduced, but also the characteristics of the laminate such as warping, torsional dimensional accuracy, workability, etc. are improved, and the appearance is improved by reducing the occurrence of scratches at the edges.

In addition, since forming is performed at a relatively low degree of vacuum, there is no need for special vacuum equipment, and it can be applied to conventional large presses by simply preparing a simple mold frame, thereby reducing productivity. It never occurs.

(Example) Examples of the present invention will be described below.

Examples 1 to 4 Eight sheets of 0.2 mm thick prepreg impregnated with 10 mils Kraft low flame retardant phenolic resin diluted with methanol were stacked, and each side was coated with a 35 μm thick adhesive. As shown in FIGS. 1 and 2, the silver foil is pressed in a mold frame 3 having a structure in which silicone rubber gaskets 2 are fixed to the top and bottom surfaces of a frame 1 made of aluminum or stainless steel. The laminated plate was placed between hot plates, and the laminate was heated and pressurized while vacuum suction was applied to the inside of the frame through the vacuum hole 4 using a vacuum pump.

The respective molding conditions are shown in the table. In the table, the degree of vacuum indicates the standard degree of pressure reduction in the entire molding process, the molding temperature represents the temperature of the press hot plate, and the molding pressure represents the secondary molding pressure.

For comparison, a well-known vacuum press was used to
Under vacuum conditions of Torr, a laminate of the same prepreg and copper foil as in the example was heated, pressed, and molded at different temperatures, pressures, and times.

Furthermore, the same laminate as in the example was sandwiched as it was between press hot plates, and heated and heated under the molding conditions shown in the table in a normal pressure atmosphere.
Pressure and molding were performed.

In this way, various properties of the paper-phenol laminates obtained in Examples and Comparative Examples were measured.

The measurement results are shown in the table. In the table, warping and twisting are for thickness 1
．． 6n indicates the amount of warpage when a laminate with a size of 200 x 150n and a heat treatment condition of E-1/160 is placed flat on a flat plate, and the dimensional shrinkage rate is E-0.5/160.
The lateral shrinkage rate after treatment is shown.

In addition, cracks during the punching process should be avoided by heating the laminate to 60°C115.
The presence or absence of cracks is shown when punched with a tOn press at a hole pitch of 1.78u, and the appearance misalignment and shearability are the results of visual observation of the as-is condition and the hole-to-hole pitch of 1.78u. , O is good, Δ
indicates poor condition, and OΔ indicates slightly poor condition.

Furthermore, insulation resistance, water supply rate, solder heat resistance, and peel strength were based on JIS-C-6481.

(Margin below) Back 3 [Effects of the Invention] As is clear from the above explanation, in the method for producing a paper-phenol laminate of the present invention, a frame with backings provided on the top and bottom of the outside of the prepreg and silver foil laminate is used. Heating, pressurization, and molding are performed under reduced pressure inside the body, and the reaction of phenolic resin proceeds quickly even under relatively low temperature and low pressure conditions, which not only reduces energy costs but also reduces molding time. can be reduced.

In addition, a Wt layer plate with excellent electrical properties without voids or scratches can be obtained.

Furthermore, since molding can be performed at a lower pressure than conventionally, residual strain can be reduced, and as a result, a laminate with excellent workability without warping or twisting can be obtained.

Furthermore, since a very high degree of vacuum is not required during molding, manufacturing can be carried out using conventional equipment almost as is by simply adding an inexpensive jig.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a mold frame used in an embodiment of the present invention, Fig. 2 is a plan view of a mold frame used in an embodiment of the present invention;
The figure is a sectional view taken along the line nm' in FIG. 1...Aluminum or stainless steel frame 2...Silicone rubber seal Applicant Toshiba Chemical Co., Ltd. agent Patent attorney Satoshi Suyama - Figure 2

Claims (2)

[Claims] (1) After stacking multiple sheets of prepreg made by impregnating a paper base material with phenolic resin and laminating copper foil on both sides through an adhesive layer, the sheets are heated and pressurized to form an integral piece. A method for manufacturing a paper-phenol laminate, characterized in that the outer side of the prepreg and copper foil laminate is surrounded by a frame body provided with backings on the top and bottom, and heating and pressurizing the space between the frames in a reduced pressure atmosphere. (2) The method for producing a paper-phenol laminate according to claim 1, wherein the degree of vacuum is 10 to 200 torr.