JPH051723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a method for producing prepregs used in the production of insulating laminates or printed circuit laminates used in various electrical devices.

<Background of the Invention> Laminated boards for printed circuits are generally produced by impregnating a base material such as paper or glass cloth with a varnish made by dissolving various resins in a solvent, and then drying the solvent to create a prepreg. It is manufactured by cutting into a predetermined size and shape, stacking a predetermined number of sheets, overlapping metal foil such as copper foil on one or both sides, and then heat-processing using a hot press.

If air bubbles are mixed inside this type of laminate, it may impair the heat dissipation properties of the laminate when it is used as an electrical component, or the air bubbles may form during the heating process such as soldering when manufacturing circuit boards. This can become a core and cause problems such as not being able to perform normal soldering.

In order to prevent air bubbles from forming in the laminate from the above point of view, a method has been adopted in which the air bubbles mixed in the prepreg are forced out by applying high pressure during the laminate forming process. Due to the high pressure during molding, there is a risk that the resulting laminate may have poor dimensional stability, or may warp or twist.

As a method to solve these problems and prevent air bubbles from being mixed in the prepreg, there is a method of supplying and impregnating a resin liquid that has been subjected to reduced pressure treatment (Japanese Patent Publication No. 60-1169),
Alternatively, a method has been proposed in which pressure is applied to the base material during the process of impregnating the base material with resin (Japanese Patent Application Laid-open No. 60-90719). However, the latter method requires a driving device for pressurizing the impregnated substrate with a belt press, making the device complex and increasing equipment costs.

Therefore, the present inventors conducted extensive research with the aim of providing a prepreg manufacturing method with less air bubbles that can solve these problems, and have completed the present invention.

<<Means for solving the problems>> In order to achieve the above object, the structure of the present invention is as follows:
When manufacturing a prepreg by impregnating a resin into a base material woven from yarn, the base material has an axis that is oblique to the longitudinal direction of the base material and is passed through a pair of parallel opening rollers. The fibers of the base material are opened while changing the direction of travel through the fibers, and then the base material is impregnated with a resin.

To explain in more detail, for example, glass cloth, which is often used as a base material, is woven using glass yarns, which are made by bunching and twisting many glass fibers with a diameter of about 5 to 11 μm, as warp and weft threads. A resin selected from epoxy resin, unsaturated polyester, vinyl ester resin, diallyl phthalate resin, polyimide resin, phenolic resin, etc. depending on the performance of the laminate is applied to the glass cloth base material. When impregnating, prior to impregnation, a glass cloth base material or the like is prepared using two materials having an axis that intersects without being perpendicular to the longitudinal direction of the base material, and that are parallel to each other and spaced at an appropriate interval.
While changing the running direction through the base material, a fiber opening roller consisting of parallel rollers is used to spread the fibers of the base material, ie, glass yarn, etc. This opening is achieved by bending the raw yarns by switching them in different directions when the warp and weft yarns constituting the base material pass through a spreading roller. Since the fibers that are fixed together are opened and the resin is easily impregnated afterwards, the diameter of the roller, the axis of the opening roller, and the longitudinal direction of the base material are adjusted depending on the condition of the yarn. It is necessary to set the angle between the vehicle and the travel direction as appropriate.

In addition to the above-mentioned glass cloth, the method of the present invention can also be applied to cloths whose raw threads are synthetic fibers, asbestos yarns, carbon fibers, etc., and the opening effect can be obtained.

Note that when the axis of the opening roller is perpendicular, the opening effect on the weft is small, and the effect of preventing air bubbles from being mixed in cannot be obtained.

The base material opened in this way is immersed in an impregnating bath according to a conventional method, or it is impregnated with resin using a coating roller, etc., and the resin thickness is adjusted using an appropriate number of guide bars or rollers. This is heated and dried to volatilize the solvent to obtain a suitable B state, and then wound to form a prepreg for a laminate.

<<Operation>> According to the prepreg manufacturing method having the above structure, the base material woven by the spreading rollers whose axes intersect obliquely passes through the spread rollers in a twisted manner, so that it is difficult to The fixed fibers become open, making it easier for them to be impregnated with resin, and the air bubbles trapped between the fibers to be released.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Example 1 Glass yarn of 67.5 tex, which was made by bundling 400 single fibers with a diameter of 9 μm, was used as the warp and weft, and the weaving density was
It is a glass cloth with a plain weave structure of 42 threads/inch and weft of 32 threads/inch. After weaving, oils such as starch and fat used in the glass yarn are removed, and the chemical adhesion with the matrix resin is improved. In order to achieve this, glass cloth with a basis weight of 200 g/m ² manufactured by Company A and treated with a coupling agent was selected as the base material. This rolled glass cloth A was attached to a stand 1 shown in FIG. 1 and fed into a fiber opening device 4 via guide rolls 2 and 3.

As shown in detail in FIG. 2, the opening device 4
are a pair of parallel opening rollers 5, 6 and 7,
The angle θ ₁ between the axes of the opening rollers 5 and 6 and the supply direction (longitudinal direction) of the glass cloth A is
is set to 45°, and the angle θ ₂ of the axis of the other opening rollers 7 and 8 is adjusted to 45°, and these rollers 5, 6,
7 and 8 with an external diameter of 30 mm were used.

By passing it through the fiber opening device 4, the weft threads of the glass cloth, which had the shape of a rod of FRP due to the coupling agent before passing through the fiber opening device 4, are twisted between the rollers 5, 6, 7, and 8. The fibers were loosened by the opening action of passing through the fibers, and were in a soft state. In this case, in order to spread the fibers more efficiently, it is necessary to place a presser roller 1 above the spreader roller 5.
2 may be installed.

The glass cloth A thus opened is then immersed in an impregnating tank 9 filled with an epoxy resin varnish consisting of an epoxy resin, a hardening agent, and a solvent and having a viscosity of 100 centipoise (measured at 25°C) to impregnate it with the varnish. After passing this through a slit bar 10 for thickness adjustment, it was introduced into a drying device 11 and heated at 150° C. for 5 minutes to obtain a prepreg with a resin content of 42% by weight.

8 sheets of this prepreg were stacked, copper foil with a thickness of 35 μm was layered on both sides, and this was sandwiched between stainless steel templates and heated at a temperature of 170℃ and a pressure of 30Kg/cm ² for 60 minutes.
A copper-clad laminate can be manufactured by pressurizing and heating for minutes.

When the prepreg according to this example was observed under a microscope with a magnification of 50 times, no air bubbles were observed, as is clear from the attached microscopic reference photograph 1, and no air bubbles were observed when it was made into a laminate.

Example 2 In comparison with Example 1, the pair 2 of the opening device 4
The third set of opening rollers 5, 6, 7, and 8 are made so that the inclination angles with respect to the longitudinal direction of the glass cloth A are almost the same.
As shown in the figure, four rollers 5, 6, 7, and 8 were arranged obliquely and parallel to each other, and the glass cloth A was opened to produce a prepreg.

Similarly to Example 1, no air bubbles were observed in the prepreg obtained by this method when microscopically observed.

Comparative Example 1 Using the same glass cloth A and resin varnish as in the above example, impregnation was performed without using the opening device 4, and the glass cloth A was heated at 150°C for 5 minutes.
A prepreg with a resin content of 42% by weight was obtained.

The thus obtained prepreg was heat-formed under the same configuration and conditions as in Example 1 to produce a copper-clad laminate.

As clearly seen from the attached microscopic reference photograph 2, the prepreg of this comparative example had many air bubbles along the glass fibers, and voids were observed in the center of the laminate.

In addition, in the above embodiment, a manufacturing method using two pairs of opening rollers diagonally intersecting the longitudinal direction of the glass cloth A was exemplified, but in the present invention, it is of course possible to use one or three or more pairs. good.

<<Effects of the Invention>> According to the prepreg manufacturing method according to the present invention,
The warp or weft yarns constituting the base material are fixed into a rod shape by a coupling agent or the like, and then the weft yarns are fixed by a spreading roller having an axis that intersects the running direction of the base material at an appropriate angle. can be opened effectively. By tilting the rollers with respect to the running direction of the base material, the weft threads that are perpendicular to the longitudinal direction of the fabric are gradually bent and deformed as the fabric runs, making the weft threads appear as if they were being kneaded. This seems to be because it receives a relaxing force.
Of course, the warp yarns are also opened by being subjected to bending deformation according to the diameter of the roller.

In this way, the raw yarn that makes up the base fabric is
The fibers that are fixed by the coupling agent and other processing agents are mechanically opened.
Afterwards, the resin varnish can be impregnated into the inside of the raw yarn, and the air in the raw yarn is expelled, resulting in a prepreg with extremely few air bubbles.

As described above, according to the prepreg manufacturing method of the present invention, by passing the base material through a relatively simple fiber opening device, prepreg with extremely low air bubbles can be obtained, and this can be used as a laminate. When hot forming, it is not necessary to apply high pressure to expel air bubbles, which is advantageous in terms of forming equipment and energy saving.Also, since high pressure is not applied, there is no need to worry about deformation such as warping or twisting of the laminate. It is possible to provide a novel and extremely useful prepreg manufacturing method.

[Brief explanation of drawings]

FIG. 1 is an overall view showing the prepreg manufacturing process according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the arrangement of a fiber opening roller showing a first embodiment of a fiber spreading device used in the present invention, and FIG. FIG. 2 is an explanatory diagram showing another embodiment of the same device. A... Base material, 4... Opening device, 5, 6, 7, 8... Opening roller, 9... Impregnation tank, 10... Dryer.

Claims (1)

[Claims] 1. When manufacturing a prepreg by impregnating a resin into a base material woven from raw threads, a pair of parallel openings having an axis obliquely intersecting the longitudinal direction of the base material. A method for manufacturing a prepreg, which comprises passing the base material through a textile roller, opening the fibers of the base material while changing the running direction, and then impregnating the base material with a resin. 2. The prepreg manufacturing method according to claim 1, wherein the opening rollers are comprised of two sets each inclined in different directions.