JP2000061939A - Resin varnish impregnation method, manufacture of prepreg and resin impregnation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a prepreg almost free from voids using a soaking process by first feeding a fiber base material onto an introduction roll in an impregnation tank and impregnating the fiber base material with a resin varnish in such a manner that the fiber base material is fed onto an impregnation roll so as to make the face coming into contact with the introduction roll come into contact with the opposite side face to the former. SOLUTION: An outward pressure from an introduction roll 3, that is, a pressure to be applied to the opposite side face (b) to the face (a) coming into contact with the introduction roll 3 from the face (a), works following the feeding of a fiber base material 1 onto the introduction roll 3. Next the pressure makes a resin varnish flow from the face (a) to the face (b) and in turn, air bubbles are pushed out of the face (b) side. After that, the fiber base material 1 is fed onto the impregnation roll 7 in such a manner that the opposite side face (b) to the face (a) coming into contact with the introduction roll 3 comes into contact with the impregnation roll 7. Consequently the pressure to be applied to the opposite side face (a) from the face (b) coming into contact with the impregnation roll 7 works to force air bubbles out of the face (a) side. Thus the air bubbles are removed from the resin varnish with which the resin base material 1 is impregnated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin varnish impregnation method, a prepreg manufacturing method, and a resin impregnation apparatus.

[0002]

2. Description of the Related Art A prepreg is made by stacking a plurality of sheets and heating and pressing them to form a laminated board. Also, an inner layer circuit board of a copper clad laminated board for a multilayer printed wiring board is adhered to an outer layer board or an outer layer of copper foil, or an inner layer. Used for adhesion between circuit boards.

The prepreg is manufactured in a non-sticky state by impregnating a fiber varnish with a resin varnish and then heating it to remove volatile components such as a solvent and to accelerate the curing reaction of the resin to some extent. This heating step is generally called a drying step.

As a method for impregnating a fiber varnish with a resin varnish, the fiber varnish 1 is drawn into a impregnation tank 4 by a guide roll 2 and an introducing roll 3 so as to be dipped in the resin varnish 5 and adhered thereto, and an adjusting bar 6 is used. A method of making a predetermined adhesion amount (immersion method, see FIG. 2) is widely adopted. However, the resin varnish is a thermosetting resin composition in which a thermosetting resin composition is dissolved in a solvent or a liquid thermosetting resin composition, and because of its high viscosity, its permeability to a fiber substrate is not good,
Air bubbles may remain inside the prepreg. The bubbles remaining inside the prepreg are called voids. Most of the voids are discharged to the outside of the system when the resin of the prepreg is melted in the heating / pressurizing step when manufacturing a laminate or a copper clad laminate for a multilayer printed wiring board. A part may remain inside the insulating layer of the copper clad laminate for board. When it is necessary to distinguish the void inside the laminate or the copper clad laminate for a multilayer printed wiring board from the void of the prepreg, it is called a molding void. The presence of molding voids inside the insulating layer not only causes swelling in a solder dip or reflow furnace for mounting components as a printed wiring board, but also impairs the reliability of the incorporated electronic device.

Since many prepreg voids tend to increase the number of molding voids, various ideas have been proposed and put to practical use for preventing bubbles from remaining when the fiber varnish is impregnated with the resin varnish. ing. For example, by contacting the fiber varnish with a roll having a resin varnish attached thereto, the resin varnish is permeated from one side of the fiber base and the bubbles are pushed out to the other side so that the bubbles do not remain ( Kiss coating method), a method of immersing the fiber base material in a solvent and then immersing it in a resin varnish (solvent replacement method), and a method of immersing the fiber varnish under reduced pressure (vacuum impregnation method).

[0006]

However, all of these methods bring about an increase in cost, and are therefore limited to applications where particularly few voids are required,
The dipping method was directly adopted for general purposes. The invention described in claim 1 or 2 is made in view of such circumstances, and an object thereof is to provide a resin varnish impregnation method capable of producing a prepreg with few voids by a dipping method. Another object of the present invention is to provide a method for producing a prepreg with few voids. It is another object of the present invention to provide a resin varnish impregnating apparatus capable of producing a prepreg with few voids by a dipping method.

[0007]

According to the invention described in claim 1, after the fiber base material 1 is hung on the introducing roll 3 in the impregnation tank 4 equipped with the introducing roll 3 and the impregnating roll 7, In the resin varnish impregnation method, the resin varnish 5 is impregnated into the impregnating roll 7 such that the fiber base material 1 is hung on the impregnating roll 7 so that the surface b opposite to the contacting surface a is in contact. Yes (see Figure 1).

When the fiber base material 1 is hung on the introducing roll 3, an outward pressure from the introducing roll 3, that is, a pressure from the surface a in contact with the introducing roll 3 to the opposite surface b is applied. This pressure causes the resin varnish to flow from the surface a toward the surface b, and the bubbles on the surface b side are pushed out. Next, the fibrous base material 1 is hung on the impregnating roll 7 so that the surface b opposite to the surface a contacting the introducing roll 3 comes into contact with the impregnating roll 7. The air pressure on the surface a side is pushed out by the pressure acting on the surface a. Since air bubbles are removed in this way,
A resin varnish-impregnated fiber base material with few bubbles can be obtained.

Further, since the air bubbles are removed in this manner, two or more impregnating rolls 71, 72 ... Are provided.
It is preferable that the surface a contacting the introducing roll 3 and the surface b opposite to this surface be hung on the impregnating rolls 71, 72 so as to alternately contact the impregnating rolls 71, 72.

That is, according to the second aspect of the invention, two or more impregnating rolls 7 are provided, and the surface a in contact with the introducing roll 3 is
And the surface b on the side opposite to this surface are alternately provided with the impregnating roll 7
The method for impregnating resin varnish according to claim 1, wherein the impregnating rolls 71, 72 ... Are hung so as to come into contact with the resin varnishes.

When the fiber varnish 1 is impregnated with the resin varnish by the resin varnish impregnation method according to claim 1 or 2, a resin varnish-impregnated fiber base material having few bubbles is obtained. By heating the resin to a semi-cured state, a prepreg with few voids can be manufactured. That is, the invention described in claim 3 is characterized in that the resin varnish is impregnated into the fiber base material 1 by the resin varnish impregnation method according to claim 1 or 2, and then the resin is heated to a semi-cured state. It is a method of manufacturing a prepreg.

The invention according to claim 4 is the impregnation tank 4
A resin impregnating device, in which an introducing roll 3 is provided below the impregnation tank 4 and a plurality of impregnating rolls 71, 72, ... Are provided above and below the impregnation tank 4 in a zigzag shape in the impregnation tank 4. Is.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The fiber base material 1 used in the present invention may be a conventionally known fiber base material and is not particularly limited. For example, paper, glass cloth, glass non-woven fabric, glass mat, synthetic fiber cloth, synthetic fiber non-woven fabric, paper-
Examples include glass mixed paper.

The thermosetting resin used for the resin varnish 5 may be a conventionally known thermosetting resin and is not particularly limited. For example, epoxy resin, phenol resin,
Examples include unsaturated polyester resins and polyimide resins. A thermosetting resin composition obtained by adding a curing agent, a curing accelerator, a flame retardant, a filler and the like to these thermosetting resins as necessary is dissolved or dispersed in a solvent to impregnate the fiber base material 1 as a resin varnish 5. To do.

The solvent used for the resin varnish 5 may be any conventionally known solvent capable of dissolving the thermosetting resin used and is not particularly limited. When a liquid thermosetting resin is used, it may be solventless. Examples of the solvent include water, methanol, ethanol, propyl alcohol, butyl alcohol, acetone, methyl ethyl ketone (also referred to as butanone), toluene, xylene,
Dioxane, ethylene glycol monomethyl ether,
Examples of the solvent include ethylene glycol monoethyl ether, and these solvents may be used alone, or may be mixed and used as necessary.

The resin impregnating apparatus of the present invention can be manufactured by modifying the conventional resin impregnating apparatus and adding the impregnating roll 7. The introduction roll 3 has a diameter of 150 to
A 400 mm corrosion resistant metal roll is used. A stainless steel roll is preferable as the corrosion-resistant metal roll,
It may be a metal roll that has been rust-proofed. The impregnating roll 7 (71, 72, 73, 74 ...) Same as the introducing roll is used.

As described above, the fibrous base material 1 is hung on the introducing roll 3 so that the pressure from the introducing roll 3 is outward, that is, the surface a in contact with the introducing roll 3 is directed to the opposite surface b. A pressure acts, and this pressure causes the resin varnish to flow from the surface a toward the surface b, the bubbles on the surface b side are extruded, and then the surface b on the side opposite to the surface a in contact with the introducing roll 3 is removed. When the fiber base material 1 is hung on the impregnating roll 7 so as to come into contact with the impregnating roll 7, pressure is applied from the surface b in contact with the impregnating roll 7 to the surface a on the opposite side, and the bubbles on the surface a side are extruded. Since the air bubbles are removed from the resin varnish with which the fiber base material 1 is impregnated in this manner, the air bubbles can be removed more reliably by increasing the number of impregnating rolls 7. However, as the number of impregnating rolls 7 increases, the amount of bubbles removed also decreases. That is, the increase in the effect by increasing the number of impregnating rolls 7 becomes small. Therefore, for example, in an epoxy resin varnish, four impregnating rolls 7 are used.
It is preferable to arrange as shown in FIG.

The speed at which the fiber base material 1 passes through the resin varnish 5 is determined in the same manner as in the conventional case. That is,
If the speed is too high, the resin varnish is not sufficiently impregnated, and if the speed is too low, the productivity is inferior.
It is necessary to determine the optimum speed in consideration of these. However, the optimum speed is determined individually because it depends on the viscosity of the resin varnish 5 and the material of the fiber base material 1. The fiber base material 1 is sent to the drying step after passing through the resin varnish 5.
It is made into a prepreg by being dried. The conditions of this step may be the same as conventional ones and are not particularly limited. Since the obtained prepreg has few voids, it is particularly useful as an adhesive amount between the inner layer circuit boards and as an adhesive material between the inner layer circuit board and the outer layer copper foil in the production of the multilayer board.

[0019]

[Example] Preparation of resin varnish Brominated epoxy resin (using Epicoat 5040B80 (trade name) manufactured by Yuka Shell Epoxy Co., Ltd.) 90
Parts (parts by weight, the same hereinafter), 10 parts of cresol novolac type epoxy resin (using Dow Chemical Co., ECN1273 (trade name)), 1.5 parts of dicyandiamide and 2 parts
A resin varnish was prepared by dissolving 0.05 part of -ethyl-4-methylimidazole in 15 parts of methyl ethyl ketone.

Example 1 As the fiber base material 1, a basis weight of 210 g / m ² and a width of 1050 m
m, 0.2 mm thick glass cloth (MIL standard: 76
29 type), one introduction roll 3 and four impregnation rolls 71, 72, 73, 74 were arranged in a zigzag shape in the impregnation tank 4 as shown in FIG. Then, the resin varnish prepared above is supplied into the impregnation tank 4, and the fiber base material 1
The introduction roll 3 and the four impregnation rolls 71, 72, 7
3, 74 were passed in this order and passed through the resin varnish at a speed of 9 m / min. As the introduction roll 3 and the four impregnation rolls 71, 72, 73, 74, those made of stainless steel and having a diameter of 200 mm were used. Then, the amount of the adhered resin was made constant with the adjusting bar 6, and the resin was passed through a drying tower at 160 ° C. to produce a prepreg. The amount of resin attached to the prepreg was 42.3% by weight.

Example 2 The fiber base material 1 was changed to a glass cloth having a basis weight of 108 g / m ² , a width of 1050 mm and a thickness of 0.1 mm (MIL standard: 2116 type), and the speed of passage through a resin varnish was set to 9. 5
A prepreg was produced in the same manner as in Example 1 except that the prepreg was changed to m / min. The amount of the attached prepreg resin was 52.1% by weight.

COMPARATIVE EXAMPLE 1 Without using the impregnating roll, the speed of the fiber substrate was set to 6.
A prepreg was produced in the same manner as in Example 1 except that the prepreg was changed to 1 m / min. Adhesive resin content of prepreg is 42.4
% By weight.

Comparative Example 2 Without using the impregnating roll, the speed of the fiber substrate was set to 6.
A prepreg was produced in the same manner as in Example 2 except that the prepreg was changed to 5 m / min. The amount of resin attached to the prepreg is 51.9.
% By weight.

With respect to the prepreg manufactured as described above, the void remaining rate was examined. The results are shown in Table 1. The void remaining rate was obtained by scanning the surface of the prepreg with an image processing apparatus to obtain the area occupied by the voids, and calculating the ratio with the scanned area. The numerical values shown in Table 1 are average values for 10 samples.

A double-sided copper-clad laminate having copper foil of 70 μm in thickness on both sides (MCL-manufactured by Hitachi Chemical Co., Ltd.)
E-67 (trade name) was used for circuit processing, and copper foil of 70 μm in thickness was superposed on both sides of the inner layer circuit board produced by the circuit processing through one piece of the prepreg produced above, and a temperature of 175
A four-layer board was produced by heating and pressurizing at a temperature of 2.45 MPa for 90 minutes. Then, the entire surface of the copper foil was etched to check the number of forming voids. The results are also shown in Table 1. The number of forming voids is 3 for a 4-layer board.
It was determined by cutting to a size of 00 × 500 mm, removing the entire surface of the copper foil by etching, and visually counting. The numerical values shown in Table 1 are average values for two samples.

[0026]

[Table 1]

From Table 1, the void residual ratio of the prepregs produced in Examples 1 and 2 and the molding voids of the four-layer board produced using this prepreg were better than those of the prepregs produced in Comparative Examples 1 and 2. Is shown.

[0028]

As described above, according to the present invention, it is possible to manufacture a prepreg having few voids and molding voids.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a resin impregnating apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view of a conventional resin impregnation device.

[Explanation of symbols]

1 Fiber substrate 2 Guide roll 3 Introduction roll 4 Impregnation tank 5 resin varnish 6 Adjustment bar 7, 71, 72, 73, 74 Impregnation roll a Surface contacting the introduction roll b Surface opposite to the surface in contact with the introduction roll

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Claims (4)

[Claims] 1. A fiber-impregnated roll impregnated with a fibrous base material in such a manner that the fibrous base material is hung on the introduction roll in an impregnation tank equipped with the introduction roll and the impregnation roll, and then the surface opposite to the surface in contact with the introduction roll is in contact. A method for impregnating a resin varnish, characterized in that the fiber varnish is impregnated with the resin varnish. 2. An impregnating roll is provided such that two or more impregnating rolls are provided, and a surface in contact with the introducing roll and a surface opposite to this surface are alternately hung on the impregnating roll. Item 2. The resin varnish impregnation method according to Item 1. 3. A method for producing a prepreg, which comprises impregnating a fiber base material with a resin varnish by the resin varnish impregnating method according to claim 1 or 2, and then heating the resin to a semi-cured state. 4. A resin impregnation apparatus comprising an introduction roll provided below the impregnation bath in the impregnation bath, and a plurality of impregnation rolls provided in a zigzag pattern above and below the impregnation bath in the impregnation bath.