JPS63214411A - Production of prepreg - Google Patents

Abstract

PURPOSE:To obtain a prepreg containing no bubbles without lowering the productivity, by coating a woven fabric with a resin by passing it through between a kiss roll and a threaded roll before passing the woven fabric in a resin solution. CONSTITUTION:Movement of a resin occurs in the strands of a woven fabric because the woven fabric passes through while being wiped by a rotating threaded roll, and bubbles are easily cut into extremely fine sizes. The bubbles are also moved in the width direction of the woven fabrics because being pressed by the thread and the bubbles in the strands thereby easily come out. After passed through between a kiss roll 4 and the threaded roll, the woven fabric is guided into a resin solution tank 8 and immersed in the resin solution, and a necessary amt. of the resin solution required as a prepreg is added thereto. The woven fabric 1 impregrated with the resin solution is then introduced in a drying zone 9 and becomes to a prepreg 3. The prepreg 3 thus obtained contains very few bubbles and it is thereby possible to obtain a laminated plate with no bubble even if press-heat molding is done at low pressure.

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 substrates of printed wiring boards for industrial equipment, electronic equipment, etc. It is something.

[Conventional technology]

Laminated boards used as substrates for printed wiring boards for industrial equipment and electronic equipment are generally made by impregnating woven fabric with resin, drying it, and removing the solvent to create a B-stage prepreg. It can be obtained by stacking a plurality of prepregs, further stacking metal foil on one or both sides of the prepreg as needed, and then hot-pressing the prepreg using a pressure molding machine. In producing this prepreg, a woven fabric is passed through a resin liquid to impregnate the woven fabric with the resin liquid.

The impregnation methods include immersing the woven fabric in the resin liquid, squeezing it with a pair of rolls while immersed in the resin liquid, and impregnating the woven fabric from one side with the resin liquid using a kiss roll. Afterwards, a method is generally used in which the excess resin liquid is squeezed to a predetermined thickness using a pair of rolls, etc., and then introduced into a drying chamber to remove the solvent. In prepregs manufactured by these methods, air bubbles do not escape from within the strands of the woven fabric, and the prepregs are converted to the B stage with many air bubbles ranging in length from several tens of micrometers to several cranes generated inside the prepregs. For this reason, when this is laminated and used as a printed wiring board or as an adhesive sheet for the same, air bubbles are removed by applying a large amount of pressure during hot-press molding so as not to adversely affect the properties.

However, when a large amount of pressure is applied during hot-pressing molding, residual stress is likely to occur in the molded product, and the residual stress is released during reheating, resulting in problems such as decreased dimensional stability and increased warping and twisting. .

In particular, if many long air bubbles occur within the strand,
During molding, the B-staged resin cannot be filled completely and remains in the laminate as bubbles, which adversely affects properties such as water resistance, heat resistance, and electrical properties, resulting in a decrease in reliability.

In order to obtain a laminate with excellent dimensional stability and no warping, twisting, or bubbles, it is preferable to mold it at low pressure, but since conventional prepregs have many bubbles, a prepreg without bubbles is required.

Up until now, in order to obtain prepreg without bubbles, methods of immersing the woven fabric in a resin liquid for a long time, applying ultrasonic waves to the woven fabric through the resin liquid, and impregnating the woven fabric in a vacuum have been studied. has been done.

However, these methods are not realistic because they each have problems such as decreased production efficiency, heat generation, and difficulty in producing continuous woven fabrics.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above points, and an object of the present invention is to provide a prepreg manufacturing method that can obtain a prepreg without air bubbles without reducing productivity.

[Means for solving problems]

The present inventor investigated a method of impregnating a woven fabric used for prepreg with resin, and found that, before immersing the woven fabric in resin,
The inventors have discovered that the above object can be achieved by applying the resin in advance using a specific roll, and have completed the present invention.

That is, the present invention provides a method for producing prepreg by passing a woven fabric through a resin liquid, dipping it, and then drying it, in which the resin is passed between a kiss roll and a threaded roll before passing the woven fabric through the resin liquid. It is characterized by being applied.

The present invention will be explained below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of an apparatus used in the prepreg manufacturing method of the present invention.

1 is a woven fabric that serves as the base material of the prepreg, and is usually made from long fibers such as glass.

The resin liquid tank 7.8 is filled with resin liquid 2 to be impregnated into the fabric. The kiss roll 4 is partially immersed in the resin liquid tank 7 and is rotated so as to always lift a certain amount of the resin liquid, and the threaded roll is also rotated in accordance with the rotation of the kiss roll. The pressure of the kiss roll 4 and the threaded roll 5 may be uniformly applied throughout the woven fabric within a range that does not cause fiber breakage or concave bending of the woven fabric.

The number of threaded rolls installed on one kiss roll may be plural, and moreover, multiple kiss rolls in such a combination may be installed.The threaded thread shape of the threaded roll is trapezoidal. Although it is preferable to have a shape similar to that of the thread, the tip of the thread may be flat or curved, and is not particularly limited. It is preferable that the height of the thread is 1.0 or more so that air bubbles in the fabric can easily escape from the valley of the thread to the outside.

In the method of the present invention, it is necessary to pass the resin between the kiss roll and the threaded roll before passing the woven fabric through the resin solution and immersing it.

As the woven fabric passes through a rotating threaded roll while being squeezed, the resin moves within the strands of the woven fabric, causing very fine air bubbles (easily broken up), and air bubbles being compressed by the screwing process. As the strands move in the width direction of the woven fabric, air bubbles within the strands can easily escape.

The woven fabric passed between the kiss roll and the threaded roll is led to a resin liquid tank 8 and immersed in the resin liquid, thereby depositing the amount of resin liquid required for the prepreg.

In the present invention, solutions of various thermosetting resins such as epoxy resins, polyester resins, and polyimide resins are used as the resin liquid.

Next, the woven fabric 1 impregnated with the resin liquid is introduced into a drying zone 9 and becomes a prepreg 3. Since the prepreg 3 thus obtained has almost no air bubbles, it is possible to obtain a air bubble-free laminate even when pressure molded at low pressure. By realizing this low-pressure molding, it is possible to manufacture laminates and multilayer printed wiring boards with excellent dimensional change and less warpage and twisting.

〔Example〕

Example 1 Using a resin liquid of methyl ethyl ketone, an epoxy resin mixed with a curing agent and having a viscosity of 3.5 voids (25°C) and a resin content of 70%, a glass cloth (Nittobo Co., Ltd.) with a thickness of 0.18 m and a weight of 210 g/rrf was used. (manufactured by Manufacturer, product name: W218K), and for one kiss roll with an outer diameter of 400 m, an outer diameter with a trapezoidal thread shape, a thread height of 1.3 fl, and a thread pitch of 2.5 counters is used. Two sets of one 300 m threaded roll were installed, a glass cloth was passed between them, a prescribed resin was applied, and a prepreg was obtained through a drying zone at 16α°C. This prepreg was observed under a microscope at a magnification of 80 times to examine the state of bubble generation, but no bubbles with a maximum length of 50 μm or more were found.

Comparative Example 1 The same resin liquid and glass cloth as in the example were used, except that the threaded roll was not used, and the glass cloth was immersed in the resin liquid bath for the same time as in the example, and then A prepreg was obtained by drying under the following conditions. As a result of observing this prepreg under the same conditions as in the above-mentioned example to examine the state of air bubble generation in the prepreg, it was found that air bubbles having a maximum length of five foreheads were generated over the entire surface.

〔Effect of the invention〕

By the manufacturing method of the present invention, a prepreg with almost no bubbles could be obtained without reducing productivity. This prepreg can be thermoformed at low pressure, and as a result,
It has become possible to produce laminates and multilayer printed wiring boards with excellent dimensional change and less warpage and twisting.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an example of an apparatus used in the present invention. Explanation of symbols 1. Woven fabric 2. Resin liquid 3, prepreg 4. Kiss roll 5, threaded roll 6. Resin liquid 7, resin liquid tank 8. Resin liquid tank 9, drying zone Figure 1

Claims (1)

[Claims] 1. In a method of manufacturing prepreg by passing a woven fabric through a resin liquid and drying it after dipping, the resin is applied by passing the woven fabric between a kiss roll and a threaded roll in advance before passing the woven fabric through the resin liquid. A method for producing prepreg characterized by: