JPH10296725A - Manufacture of resin-impregnated base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain a resin-impregnated base material having the favorable impregnability of the base material with resin by a method wherein a base material is pre-impregnated with an organic solvent, the water content of which is reduced to a specified wt.% or less through defoaming under reduced pressure and then impregnated with resin varnish and finally dried. SOLUTION: As an organic solvent 2, one, which is compatible with the organic solvent in a resin warnish 3, such as a methyl alcohol, an acetone, a methyl ethyl ketone, a methyl Cellosolve, an 1-methoxy-2-propanol, a dimethyl formamide or the like can preferably be used. The organic solvent 2 is charged to a solvent tank 11 under the condition being defoamed under reduced pressure to 150 Torr or more in a vacuum tank 10. As the organic solvent 2, one having the water content above 3 wt.% is preferably used. If the organic solvent 2 includes water content above 3 wt.%, bubbles tend to leave in the resin- impregnated base material due to this water content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a resin-impregnated base material used for producing a laminate.

[0002]

2. Description of the Related Art Conventionally, a resin-impregnated base material has been manufactured by impregnating a base material such as glass cloth or paper with a resin varnish such as a phenol resin or an epoxy resin and drying the impregnated resin varnish. Then, a plurality of the resin-impregnated base materials are stacked, heated and pressed to form a laminate, thereby obtaining a laminate.

However, the resin-impregnated base material often has air bubbles remaining or non-impregnated portions of the resin varnish, which deteriorates the fluidity of the resin during lamination.
Lamination occurred in the laminate, and as a result, the laminate was not only inferior in transparency, but also inferior in heat resistance and moisture resistance. In order to prevent such lamination of the laminate, the resin impregnation amount of the resin-impregnated base material is increased or a resin having a high fluidity is used, but in this case, misalignment tends to occur during molding. As a result, there was a problem that the moldability was poor.

[0004] In order to eliminate the residual air bubbles in the resin-impregnated base material and the non-impregnation of the resin varnish, attempts have been made to impregnate the resin varnish using a pressure roll or ultrasonic waves. Attempts to impregnate resin varnish under vacuum have been attempted, but this method has problems that it is difficult to achieve continuity and that the apparatus becomes large and expensive.

On the other hand, Japanese Patent Publication No. 6-89161 discloses that
There is provided a method for producing a resin-impregnated substrate by pre-impregnating the substrate with a solvent under reduced pressure and then impregnating the substrate with a resin varnish, followed by drying. According to this method, when the substrate is impregnated with the resin varnish, the solvent preliminarily impregnated in the substrate is replaced with the resin varnish, and the resin varnish can be well penetrated into the substrate. Thus, it is possible to obtain a resin-impregnated base material having less residual air bubbles and less impregnation of the resin varnish.

[0006]

As described above, Japanese Patent Publication No.
According to the method provided in JP-89161-A, it is possible to obtain a resin-impregnated base material having a good impregnation property with a resin varnish on the base material. There was variation, and it was impossible to stably produce a resin-impregnated base material having little residual air bubbles and no impregnation of resin varnish.

The present invention has been made in view of the above points, and provides a method for producing a resin-impregnated base material capable of stably obtaining a resin-impregnated base material having a good resin impregnation property to the base material. It is intended to do so.

[0008]

According to a first aspect of the present invention, there is provided a method for producing a resin-impregnated base material, wherein the base material 1 is pre-impregnated with an organic solvent 2 having a water content of 3% by weight or less and degassed under reduced pressure. Let
Next, the substrate 1 is impregnated with the resin varnish 3 and then dried. In the method for producing a resin-impregnated base material according to claim 1 of the present invention, the base material 1 is pre-impregnated with the organic solvent 2 degassed under reduced pressure, and then the base material 1 has a water content of 3% by weight or less. The resin varnish 3 is impregnated and then dried.

The method for producing a resin-impregnated base material according to claim 1 of the present invention is characterized in that the base material 1 is pre-impregnated with an organic solvent 2 having a water content of 3% by weight or less and degassed under reduced pressure. The method is characterized in that the material 1 is impregnated with a resin varnish 3 having a water content of 3% by weight or less and then dried. Further, the invention of claim 4 is characterized in that a substrate 1 having an attached moisture content of 0.5% by weight or less is used.

The invention of claim 5 is characterized in that the partial pressure of water vapor in the atmosphere in the step 4 of impregnating the organic solvent 2 or the resin varnish 3 is 15
mmHg or less.

[0011]

Embodiments of the present invention will be described below. In the present invention, as the substrate 1, any material such as glass cloth or paper can be used, and the substrate 1 is dried by a dryer or the like so that the amount of adhering water becomes 0.5% by weight or less. It is preferable to use those that have been used. If the amount of water adhering to the substrate 1 exceeds 0.5% by weight, air bubbles tend to remain on the resin-impregnated substrate due to the effect of the water. It is desirable that the amount of water adhering to the substrate 1 be as small as possible, but it is practically difficult to reduce the amount of water adhering to 0.1% by weight or less, and this is the practical lower limit.

In the present invention, the organic solvent 2 includes
It is preferable to use one having compatibility with the organic solvent in the resin varnish 3 described below, and methyl alcohol, acetone,
Methyl ethyl ketone, methyl cellosolve, 1-methoxy-2-propanol, dimethylformamide and the like can be used. The organic solvent 2 is added to the
The solvent is supplied to the solvent tank 11 in a defoamed state by reducing the pressure to 0 Torr or more. In the present invention, the organic solvent 2 having a water content of 3% by weight or less is used. If the organic solvent 2 contains more than 3% by weight of water, bubbles tend to remain on the resin-impregnated base material due to the effect of the water. The smaller the water content of the organic solvent 2 is, the better, and ideally it is 0% by weight. However, it is practically difficult to reduce the water content to 0.05% by weight or less. It is.

A solvent tank 1 to which the organic solvent 2 is supplied.
The substrate 1 can be impregnated with the organic solvent 2 by immersing the substrate 1 in the organic solvent 2 while continuously feeding the long substrate 1 to the substrate 1. It is preferable that the substrate 1 is sufficiently impregnated with the organic solvent 2 by immersing the substrate 1 in the organic solvent 2 for about 5 to 30 seconds. here,
The organic solvent 2 that has been defoamed under reduced pressure has the ability to dissolve air. By impregnating the organic solvent 2 into the substrate 1, the air in the substrate 1 is dissolved in the organic solvent 2 and Can reduce residual air.

In the present invention, the resin varnish 3 may be a resin varnish prepared by dissolving an arbitrary thermosetting resin for a laminate such as a phenol resin, an epoxy resin or a polyimide resin in an organic solvent. is there. Further, in the present invention, a resin varnish 3 having a water content of 3% by weight or less is used. Resin varnish 3
Contains more than 3% by weight of water, bubbles tend to remain in the resin-impregnated base material due to the influence of the water.
The smaller the water content of the resin varnish 3 is, the better and ideally it is 0% by weight. However, it is practically difficult to reduce the water content to 0.05% by weight or less. It is.

In the embodiment shown in the drawings, the substrate 1 is impregnated with the resin varnish 3 by using both the contact method and the dipping method. That is, using the contact tank 13 provided with the lower part of the kiss roll 12 immersed in the resin varnish 3 and the immersion tank 15 provided with the immersion roll 14 immersed in the resin varnish 3, the organic solvent 2 is supplied as described above. While continuously feeding the impregnated substrate 1, one side of the substrate 1 is first brought into contact with a kiss roll 12, and a resin varnish 3 is applied to one side of the substrate 1 by the kiss roll 12, and the resin varnish is applied to the substrate 1 from one side. 3 infiltrate. By infiltrating the resin varnish 3 into the substrate 1 from one side in this way, it becomes easy to expel air in the substrate 1 from the other side. Next, the base material 1 is immersed in the resin varnish 3 of the immersion tank 15 by the immersion roll 14 to impregnate the base material 1 with the resin varnish 3. The air in the substrate 1 is squeezed out together with the varnish 3.

As described above, when the resin varnish 3 is impregnated after the base material 1 is impregnated with the organic solvent 2, the resin varnish 3 penetrates the base material 1 smoothly so as to replace the organic solvent 2, The material 1 can be impregnated with the resin varnish 3 without generating an unimpregnated portion. In addition, substrate 1
It is preferable that the humidity atmosphere in the step 4 of impregnating the organic solvent 2 or the resin varnish 3 with the organic solvent 2 or the resin varnish 3 is adjusted so that the partial pressure of water vapor is 15 mmHg or less. Water vapor partial pressure is 15mmHg
By adjusting the atmosphere so as to be as follows, the influence of moisture in the atmosphere on the base material 1, the organic solvent 2, and the resin varnish 3 can be reduced, and the impregnating property can be stably maintained even after continuous production for a long time. A good state can be maintained. Although the lower the water vapor partial pressure, the better, but it is difficult to make the water vapor partial pressure of the atmosphere lower than 5 mmHg,
This is a practical lower limit.

After the substrate 1 is impregnated with the resin varnish 3 as described above, the resin varnish 3 is heated and dried to obtain a B-stage resin impregnated substrate. A plurality of resin-impregnated base materials obtained in this manner are stacked, and a laminate can be manufactured by laminating and molding by heating and pressurizing the resin-impregnated base materials. By laminating a metal foil such as a copper foil on one or both sides and heating and pressurizing the same to form a laminate, a metal foil-attached laminated board processed into a printed wiring board can be manufactured.

Here, the resin-impregnated base material obtained as described above has good impregnating properties with little residual air bubbles and no impregnation of the resin varnish. It can improve the molding pressure and reduce the molding time and shorten the molding time. Not only the conventional daylight press, but also the autoclave molding and the method of heating by energizing the metal foil Also in molding, it is possible to perform good lamination molding.

[0019]

Next, the present invention will be described specifically with reference to examples. (Example 1) Glass cloth of MIL specification standard 7628 (made by Asahi Schwebel, thickness 0.18 mm) as the substrate 1
1-methoxy-2-propanol defoamed under reduced pressure at a reduced pressure of 20 Torr for 15 minutes as an organic solvent 2, and a resin varnish 3 having the following composition was used. 90 parts by weight of brominated bisphenol A type epoxy resin (epoxy equivalent 500) 10 parts by weight of cresol novolak type epoxy resin (epoxy equivalent 220) 5 parts by weight of dicyandiamide 30 parts by weight of dimethylformamide 30 parts by weight of methyl cellosolve 2 Ethyl-4-methylimidazole 0.2 part by weight First, using the base material 1 having an attached moisture content of 0.6% by weight, and adding 15% to the organic solvent 2 whose moisture content was adjusted to 1% by weight.
After dipping for 2 seconds to impregnate the base material 1 with the organic solvent 2, the resin varnish 3 whose moisture content was adjusted to 4% by weight was applied to one surface of the base material 1 with the kiss roll 12. By impregnating and then dipping the substrate 1 in the resin varnish 3 to impregnate it, squeezing out the excess resin varnish 3 with the pressure roll 16, and then heating and drying at 155 ° C. for 5 minutes,
A resin-impregnated base material having a resin content of 50% was obtained. Here, the atmosphere in the step of impregnating the organic solvent 2 and the resin varnish 3 was a water vapor partial pressure of 9 mmHg.

The moisture content of the substrate 1 and the moisture content of the organic solvent 2 and the resin varnish 3 are numerical values measured by a micro moisture analyzer "CA-05" manufactured by Mitsubishi Chemical Corporation. (Examples 2 to 4, Comparative Examples 1 and 2) Moisture content of substrate 1
A resin-impregnated base material was obtained in the same manner as in Example 1, except that the water content of the organic solvent 2 and the resin varnish 3 were adjusted as shown in Table 1 and used.

The surfaces of the resin-impregnated substrates obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were observed with an optical microscope, and the number of bubbles per square centimeter was measured. Table 1 shows the results. Examples 1 to 4
A laminate was formed using the resin-impregnated substrates obtained in Comparative Examples 1 and 2. That is, a resin-impregnated base material is laminated on both sides of a 1.2-mm-thick copper-clad laminate having a 70-μm-thick copper foil on both sides, and a 18-μm-thick copper foil is further laminated on the outside thereof. 3 at a temperature of 130 ° C
0k for 10 minutes while heating at 170 ° C for 60 minutes
By pressing at a pressure of g / cm ² , a four-layer laminate was formed. Then, the copper foil on the surface of the laminate thus formed was removed by etching, and the amount of scrap from each corner of the laminate was measured. The maximum value is shown in Table 1.

[0022]

[Table 1]

As shown in Table 1, the amount of water adhering to the substrate 1 and the amount of water contained in the organic solvent 2 and the resin varnish 3 are regulated to improve the impregnation of the resin varnish 3 into the substrate 1. It is confirmed that the number of air bubbles in the resin-impregnated base material can be reduced, and the amount of thinning of the laminate can be reduced.

[0024]

As described above, according to the first aspect of the present invention, a base material is pre-impregnated with an organic solvent having a water content of 3% by weight or less under reduced pressure and then impregnated with a resin varnish. After drying, it is possible to reduce bubbles from remaining due to the effect of moisture contained in the organic solvent to be pre-impregnated, and to stably obtain a resin-impregnated base material having good impregnation properties. Can be done.

According to a second aspect of the present invention, the substrate is pre-impregnated with an organic solvent degassed under reduced pressure, and then the substrate is impregnated with a resin varnish having a water content of 3% by weight or less, followed by drying. As a result, it is possible to reduce bubbles from remaining due to the effect of moisture contained in the resin varnish to be impregnated, and to stably obtain a resin-impregnated base material having good resin impregnation property to the base material. Can be done.

According to a third aspect of the present invention, a base material is pre-impregnated with an organic solvent having a moisture content of 3% by weight or less and degassed under reduced pressure. After being impregnated with the varnish, the drying is performed, so that the bubbles remaining due to the influence of the organic solvent to be pre-impregnated and the moisture contained in the resin varnish to be impregnated can be reduced, and the resin to the base material can be reduced. A resin-impregnated base material having good impregnation properties can be stably obtained.

According to the fourth aspect of the present invention, since a substrate having a moisture content of 0.5% by weight or less is used as a base material, bubbles are prevented from remaining due to the effect of moisture contained in the base material. Thus, a resin-impregnated substrate having a good resin impregnation property to the substrate can be stably obtained. In the invention of claim 5, the atmosphere in the step of impregnating with an organic solvent or a resin varnish is adjusted to have a water vapor partial pressure of 15 mmHg or less, so that the influence of moisture in the atmosphere on the base material, the organic solvent, and the resin varnish is reduced. It can be reduced in size, and can maintain a good impregnating state stably even after continuous production for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an example of an embodiment of the present invention.

[Explanation of symbols]

 1 base material 2 organic solvent 3 resin varnish 4 impregnation process

Claims (5)

[Claims] 1. A resin characterized in that a base material is pre-impregnated with an organic solvent having a water content of 3% by weight or less and has been degassed under reduced pressure, and then the base material is impregnated with a resin varnish and then dried. A method for producing an impregnated substrate. 2. A resin characterized in that a substrate is pre-impregnated with an organic solvent degassed under reduced pressure, and then a resin varnish having a water content of 3% by weight or less is impregnated in the substrate and then dried. A method for producing an impregnated substrate. 3. Preliminarily impregnating a substrate with a degassed organic solvent having a water content of 3% by weight or less and then impregnating the substrate with a resin varnish having a water content of 3% by weight or less. And drying the resin-impregnated substrate. 4. The method for producing a resin-impregnated substrate according to claim 1, wherein the substrate has a moisture content of 0.5% by weight or less. 5. The method for producing a resin-impregnated substrate according to claim 1, wherein the partial pressure of water vapor in the atmosphere in the step of impregnating with an organic solvent or a resin varnish is 15 mmHg or less.