JPH01272416A - Manufacture of prepreg - Google Patents

Abstract

PURPOSE:To enhance the surface smoothness of a prepreg by collapsing the resin projections generated on the surface of the prepreg, by pressing the prepreg by a roll during or after a drying process. CONSTITUTION:A base material 1 wound in a roll form is passed through a resin solution tank 5 filled with a resin solution 2 of a thermosetting resin and the excessively bonded resin solution on the base material 1 is squeezed by a pair of rolls so as to be set to a predetermined thickness while the obtained prepreg material is guided to a drying chamber 3. Continuously, the prepreg is passed between the rolls 4 mounted to the outside or interior of the drying chamber and pressed to obtain the prepreg 6. Since the prepared prepreg has no resin projections on the surface thereof, a laminated sheet or multilayer copper clad laminated sheet formed from said prepreg by hot press molding is prevented from the generation of a light spot on the surface of the copper foil thereof and the partial lowering of peel strength is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing prepreg used for producing thermosetting resin laminates used for printed wiring boards for industrial equipment, electronic equipment, etc. be.

[Conventional technology]

Copper-clad laminates, which are used as substrates for printed wiring boards for industrial equipment and electronic equipment, are made by layering multiple sheets of prepreg within a membrane and then layering copper foil on one or both sides as necessary. Manufactured by hot-press molding using a pressure molding machine. Moreover, a multilayer copper-clad laminate is produced by placing prepreg on both sides of an inner-layer printed wiring board, and further disposing copper foil on the outside thereof, and then hot-pressing the prepreg.

This prepreg is made by impregnating a base material such as woven fabric with resin liquid,
Next, by drying this and scattering the solvent, B
Stage and produce. When a copper-clad laminate or a multilayer copper-clad laminate is produced by thermoforming using this prepreg,
There were problems such as the occurrence of light spots on the surface of the copper foil and a partial decrease in beer strength.

[Problem to be solved by the invention]

The present invention aims to provide a method for producing prepreg for producing copper-clad laminates and multilayer copper-clad laminates, which is free from problems such as the occurrence of light spots on the surface of copper foil and partial reduction in beer strength. .

[Means to solve the problem]

The present inventors investigated that the cause of the above problem was the large number of resin protrusions on the surface of the prepreg, which was impregnated with a conventional resin liquid and then led to a drying chamber and turned into a B stage. The cause of this is that there are filaments protruding from the strands on the surface of the base material before resin coating, such as the woven fabric itself, and the resin liquid accumulates in these areas during the process of impregnating the woven fabric with resin liquid and leading it to the drying room. Therefore, it was discovered that resin protrusions are formed on the surface of B-staged prepreg, and the present invention was completed.

Until now, attempts have been made to eliminate the partial protrusion of filaments from a base material such as glass cloth with the aim of obtaining a flat prepreg, but it has been difficult to completely eliminate defects in the glass cloth.

In view of the above points, the present invention relates to a method for manufacturing a prepreg that can produce a flat prepreg without resin protrusions without reducing productivity. A method for producing prepreg by drying, characterized in that during the drying process or after the completion of drying, the prepreg is pressed with a roll to crush convex resin protrusions that occur on the surface of the prepreg and improve the smoothness of the surface. The present invention provides a method for manufacturing prepreg.

As shown in FIG. 1, this prepreg manufacturing method involves passing a base material, for example, a woven fabric 1, through a resin liquid 2 to impregnate the woven fabric 1 with the resin liquid 2, and then leading it to a drying chamber 3 to form a B stage. In manufacturing the prepreg 6, the prepreg is pressed by a pair of rolls or a plurality of rolls installed outside or inside the drying chamber to crush the convex resin protrusions that occur on the prepreg surface and improve the surface smoothness. improve.

The figure shows an example of the present invention, in which a base material wound into a roll is passed through a resin liquid tank 5 which is filled with resin liquid 2 of a thermosetting resin, etc., and excessive adhesion occurs. The resin liquid is squeezed to a predetermined thickness using a pair of rolls, etc., and then introduced into the drying chamber 3. Subsequently, this prepreg is pressurized by passing between rolls 40 provided at the outside or inside of the drying chamber to obtain prepreg 6. There are no restrictions on the material of the rolls, but it is preferable to treat the roll surfaces so that the prepreg resin does not adhere to them.Also, by slightly changing the hardness of each roll in a pair of rolls, pressure can be applied more evenly to the prepreg surfaces. However, the hardness of both rolls may be the same.If the temperature of the prepreg is above the softening point, there is no need to particularly heat the roll, but if the temperature is below the softening point, the roll temperature should be lower than the softening point. It is preferable to set the temperature to a slightly higher temperature. It is also possible to carry out this operation outside the drying chamber.

The present invention uses woven fabric as a base material for producing prepreg.
It is particularly suitable for use when using long fibers such as glass cloth. The resin liquid may be a solution of various thermosetting resins such as epoxy resin, polyester resin, or polyimide resin, or may be a solvent-free resin without any particular limitation.

〔Example〕

Example 1 A methyl ethyl ketone solution of epoxy resin mixed with a curing agent, viscosity 1 void (25°C) resin content 65% by weight
Using resin liquid, thickness 0.18mm, basis weight 209g/nf
A B-staged prepreg was prepared by impregnating a glass cloth with a wafer coater, drying it at 150°C, and pressurizing the prepreg with a roll installed immediately after the exit of the drying chamber. As a result of observing the surface of this prepreg, it was possible to obtain a flat prepreg with no resin protrusions.

Comparative Example 1 A prepreg was obtained by impregnating the same resin liquid and glass cloth as in the example in the same manner as in the example and then converting it into a B stage. As a result of observing the surface of this prepreg, it was found that many resin protrusions were generated.

The prepreg obtained in this way is cut into predetermined dimensions or continuously wound up and used according to each purpose. There were no light spots on the copper foil surfaces of the laminates and multilayer copper-clad laminates that were thermoformed using the prepreg of Example 1, and there was no local decrease in beer strength.

〔Effect of the invention〕

Since the prepreg manufactured according to the present invention has no resin protrusions on its surface, the laminates and multilayer copper-clad laminates made using this prepreg do not have any light spots on the copper foil surface and have a beer-strength area. It has excellent quality with no physical deterioration.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view explaining the present invention in detail. Explanation of symbols 1. Woven fabric 2. resin liquid

Claims (1)

[Claims] 1. In a method of manufacturing prepreg by passing a base material into a resin liquid and drying it after immersion, convex resin protrusions that occur on the surface of the prepreg are removed by pressing the prepreg with a roll during the drying process or after drying. A method for producing prepreg characterized by improving the smoothness of the crushed surface.