JP2008290331A - Method for production of prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg production method capable of preventing the thinning of the surface resin layer of a prepreg on the side to be roughened when roughening the organic insulation layer of hardened prepreg using an oxidant in a production process of a multilayer wiring board by a buildup method. <P>SOLUTION: The prepreg production method includes an impregnation process of impregnating a traveling long substrate 1 with a resin varnish 2, a regulation process of regulating the thickness of the impregnated resin varnish, and a drying process of heating and drying the resin varnish. The method is characterized in that when the substrate passes through a thickness regulation means in its process, the substrate is traveled in such a state that the traveling direction of the substrate just after passing through the thickness regulation means is different from that immediately before passing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a prepreg used for producing a multilayer printed wiring board or the like.

In recent years, attention has been paid to a build-up type multilayer wiring board manufacturing technique in which an organic insulating layer and a conductor layer are alternately stacked on a conductor layer of an inner circuit board. For example, an epoxy resin is applied to a circuit-formed inner layer circuit board, an organic insulating layer is formed by heat curing, a roughened surface is formed on the surface of the organic insulating layer with a roughening agent, and a conductive layer is plated Has been proposed (see, for example, Patent Document 1). However, when only the resin that does not contain a reinforcing substrate such as glass cloth is used as the organic insulating layer, the rigidity is poor, and the thin wiring board that meets the demand for weight reduction has the disadvantage of poor mechanical strength. It was.
Thus, a build-up type multilayer wiring board manufacturing technique using a base material made of glass cloth or organic fiber nonwoven fabric and a prepreg made of resin has been proposed (see Patent Document 2). In this technique, after a prepreg is laminated and integrated on a patterned inner layer circuit board under pressure and heating conditions to form an organic insulating layer, the surface of the organic insulating layer is roughened with an oxidizing material, A method of forming a conductor layer on the conversion surface by plating is employed.

On the other hand, there are two types of prepreg production methods that are currently known: a batch production method and a continuous production method. The former is a method of impregnating a resin substrate with a resin base varnish cut to the required size and heat drying, whereas the latter is a method of impregnating a long fiber substrate traveling with resin varnish and heat drying. (See, for example, Patent Document 3), and the latter is considered preferable for mass production.
By the way, since it is preferable in terms of reliability to provide a thin layer (hereinafter, also referred to as “surface resin layer”) composed only of a resin not containing a base material on the surface of the prepreg, the base material is impregnated in the prepreg manufacturing method. It is necessary to control the amount of resin varnish. For this purpose, usually, an excessive amount of resin varnish is once impregnated into the substrate, and then the excess resin varnish is scraped off by passing between slits or rolls having a certain width. As a result, the surface resin layer of the prepreg after heat drying is formed in a state of almost the same thickness on the front and back of the substrate. Specifically, in the case of a prepreg used for a printed wiring board in which a conductor pattern is created by an etching method, the thickness of both the front and back surfaces is about 0.002 to 0.015 mm, and the conductor pattern is created by a plating method. In the case of a prepreg used for a wiring board, it is usually thicker.

JP-A-7-304932 JP 2001-181375 A Japanese Patent Laid-Open No. 9-87401

  In the manufacturing process of the build-up type multilayer wiring board, when the organic insulating layer obtained by curing the prepreg is roughened with an oxidizing material, the thickness of the surface resin layer on the roughening side of the prepreg becomes 2 μm or thinner. . Therefore, when a conventional prepreg is used, it is necessary to use a prepreg having a thick surface resin layer so that the surface resin layer after roughening becomes too thin to adversely affect reliability. The present invention aims to provide a method for solving this problem.

The present inventors solve the above-mentioned problems by manufacturing prepregs having a surface resin layer thickness of 2 μm or more different between the front and back surfaces, and setting the thick side of the surface resin layer of the prepreg to the roughening side. As a result of studying a method for producing prepregs having different surface resin layer thicknesses on both sides, the present invention has been made.
That is, the present invention
1. A method for producing a prepreg including an impregnation step of impregnating a resinous varnish into a traveling long base material, an adjustment step of adjusting the amount of the resin varnish impregnated in the base material, and a drying step of heating and drying the resin varnish. When the substrate passes through the thickness adjusting means in the adjusting step, the traveling direction of the substrate immediately after passing through the thickness adjusting means is the traveling direction of the substrate immediately before passing through the thickness adjusting means. A method for producing a prepreg characterized by running a substrate in different states,

2. The angle (A) between the traveling direction of the base material immediately after passing through the thickness adjusting means and the traveling direction of the base material immediately before passing through the thickness adjusting means is 0.5 to 10 degrees. 1. Prepreg manufacturing method,
3. 1. It has a lamination process which laminates a support base film or metal foil on one side or both sides of a prepreg after a drying process. Or 2. A method for producing the prepreg according to claim 1,
4). 1. The substrate is a glass cloth. ~ 3. A method for producing the prepreg according to any one of
5. The glass cloth has a thickness of 0.010 to 0.050 mm. The manufacturing method of the prepreg as described in 2. above.

  The method for producing a prepreg of the present invention makes it possible to produce prepregs having different surface resin layers on the front and back sides.

Hereinafter, preferred embodiments of the present invention will be described.
As a base material used by this invention, the arbitrary things conventionally used as a base material of a prepreg can be used. For example, a glass fiber substrate such as glass cloth or glass nonwoven fabric, an organic fiber substrate formed of woven fabric or nonwoven fabric such as polyester fiber or aramid fiber, liquid crystal polymer, or paper substrate is preferable. In addition, the long base means a base having a longer length than the width, and is usually supplied in a roll form for handling reasons.
In particular, when glass cloth is used as the substrate, one having a thickness of 0.010 to 0.050 mm is preferable because it is suitable for a build-up type multilayer wiring board. Further, it is more preferable to use a glass cloth having a small filament hole diameter of 3 to 5 μm and a thickness of 0.010 to 0.030 mm with a small basket hole, since the laser cloth is excellent. Specifically, glass cloth such as trade names 1027, 1037, and 1067 manufactured by Asahi Kasei Electronics Corporation is suitable.

The resin varnish used in the present invention is a composition containing a resin that softens by heating, has a film forming performance, and satisfies the characteristics required for an insulating material such as heat resistance and electrical characteristics by high-temperature thermosetting, The viscosity is not particularly limited as long as it is adjusted to a viscosity suitable for impregnation with a solvent as required. The thickness of the surface resin layer of the prepreg is generally not less than the conductor thickness of the inner circuit board to be laminated and not more than the conductor thickness + (10 to 120 μm), and the substrate thickness + ( 10 to 120 μm) or less is preferable.
Examples of the resin include an epoxy resin, a phenol resin, a polyimide resin, a polyamideimide resin, a polycyanate resin, a polyphenylene ether resin, an unsaturated polyester resin, a single resin, and a modified product or a mixture of the resin The thermosetting resin represented by can be used. The resin varnish contains the thermosetting resin as an essential component,
If necessary, the thermosetting resin can contain at least one optional component selected from the group consisting of a curing agent, a curing accelerator, and an inorganic filler.

In addition, as the solvent, any solvent conventionally used as a resin varnish solvent such as methyl ethyl ketone, acetone, propylene glycol monomethyl ether, methyl cellosolve, xylene, toluene, cyclohexanone, or dimethylformamide can be used. The resin varnish may contain a solvent, but if the amount of the solvent is small, the working environment, safety, and the like are improved, and depending on the resin, application without solvent is possible.
The method for producing a prepreg of the present invention includes an impregnation step of impregnating a running long base material with a resin varnish, an adjustment step of adjusting the amount of the resin varnish impregnated into the base material, and a drying step of heating and drying the resin varnish. including.

In the impregnation step, the traveling long base material passes through the resin varnish stored in the resin varnish bath, thereby impregnating the resin varnish (hereinafter also referred to as “impregnated base material”). It is a process to do. Here, the solid content in the resin varnish (including solvent-free resin varnish) (generally referred to as components other than the solvent of the resin varnish) is controlled to ± 5% between 30% and 100%, and the temperature of the resin varnish Is controlled to ± 5 ° C. between 10 and 80 ° C., and the viscosity of the resin varnish is preferably controlled to ± 100 Pa · s between 10 and 3000 Pa · s.
The adjustment step is a step of scraping off excess resin varnish from the impregnated substrate that has been excessively impregnated with the resin varnish when the traveling long impregnated substrate passes through the thickness adjusting means. Examples of the thickness adjusting means include a slit having a constant width and a pair of rotating rolls or a pair of knife rolls capable of adjusting the interval. The material is a hard metal that is not easily deformed, and is preferably a material that is less susceptible to deterioration such as rust in consideration of reliability, such as stainless steel plated with hard chrome. The roll preferably has a diameter of 50 to 150 mm.

  In the manufacturing method of the present invention, in the adjusting step, the base material travels immediately after passing through the thickness adjusting means in a state different from the base material travel direction immediately before passing through the thickness adjusting means. By running the material, a difference is provided in the amount of scraping off the resin varnish on both sides of the base material. For example, when the traveling direction of the base material immediately after passing through the thickness adjusting means is the vertical direction, the traveling direction of the base material immediately before passing through the thickness adjusting means is from the vertical direction to the delivery side or the winding side. By giving the take-off side an angle of several degrees, it is possible to make a difference in the thickness of the surface resin layers on both surfaces of the impregnated substrate. The angle formed by the traveling direction of the substrate immediately after passing through the thickness adjusting means and the immediately preceding traveling direction is preferably 0.5 to 10 degrees, and more preferably 1 to 3 degrees. If the angle is higher than 10 degrees, the base material may extremely come into contact with the thickness adjusting means, and problems such as cutting of the base material and fluff of constituent fibers may occur. If the angle is smaller than 0.5 degrees, the base material enters the thickness adjusting means almost vertically, and a prepreg having a difference in the thicknesses of the surface resin layers on both sides cannot be created.

The drying process is a process of removing a part of the solvent of the impregnated resin varnish and heating the thermosetting resin to a semi-cured state (B stage) by heating the traveling long impregnated base material. As the heating means, for example, a hot-air dryer can be used, and the heating conditions are preferably an atmosphere temperature of 100 to 200 ° C. and a time of about 10 to 100 seconds.
Moreover, you may have the lamination process which laminates | stacks a support base film or metal foil on the single side | surface or both surfaces of the prepreg after a drying process. This supporting base film or metal foil facilitates handling of the prepreg and adhesion of dust etc. when the prepreg is pressed and heated on the circuit board to be laminated (then roughened and plated). It is a thing which peels before this lamination operation (namely, peelable support base film or metal foil). The supporting base film is preferably made of a polyolefin such as polyethylene, a resin such as polyethylene terephthalate or polycarbonate, and has a thickness of about 10 to 150 μm. The metal foil is preferably a copper foil or aluminum foil having a thickness of 10 to 150 μm. The support film may be subjected to a release treatment in addition to the corona treatment and the plasma treatment. The lamination step of laminating the support base film or the metal foil on the prepreg may be before or after the drying step as long as it is after the adjustment step. Further, the prepreg laminated with the support base film or the metal foil is preferably wound and stored on a roll, but there is no particular problem even if it is cut and stored as a single wafer. Moreover, in the prepreg in which the support base film is laminated, the area of the prepreg is preferably the same as the area of the support base film or smaller than the support base film.

Next, an apparatus suitable for carrying out the above-described prepreg manufacturing method will be described. FIG. 1 shows a cross-sectional view of an example of the apparatus. The apparatus includes a resin varnish bath (5) whose upper surface is open and a thickness adjusting means (4) comprising a pair of rolls. The resin varnish bath (5) stores the resin varnish (2) to form a varnish reservoir. The dip roll (3) is disposed in the resin varnish bath (5) so as to be immersed in the resin varnish (2), and is driven to rotate in a certain direction shown in FIG.
The shape of the thickness adjusting means is not particularly limited as long as the thickness adjustment is appropriately performed. However, a roll having a substantially circular cross section shown in FIG. A pair of knife rolls having a shape provided over the entire length in the width direction is preferable. As can be understood from the shape, the knife roll is used as a fixed slit without rotating.

Moreover, it is preferable to arrange | position the thickness adjustment means (4) within 1 m or less from the liquid level of the resin varnish (2) stored by the resin varnish bath (5). When the thickness adjusting means (4) is disposed above 1 m from the liquid level of the resin varnish (2) stored in the resin varnish bath (5), the resin varnish contained in the impregnated base material flows down due to gravity. As a result, the resin varnish is not completely buried in the gap of the thickness adjusting means (4), so that the surface of the prepreg is not smooth and the thickness may be uneven.
And in impregnating the long base material (1) with the resin varnish (2) using such an apparatus, first, the base material (1) is brought into contact with the lower side of the dip roll (3). Is introduced into the resin varnish (2) stored in the resin varnish bath (5), the base material (1) is immersed in the resin varnish (2), and the base material (1) is impregnated with the resin varnish (2). . At this time, the arrangement of the dip roll (3) is such that the angle (A) formed by the traveling direction of the base material immediately before the thickness adjusting means (4) and the traveling direction of the base material immediately after is 0.5 to 10 degrees. It is preferable to arrange such that.

In order to set the angle (A) formed by the traveling direction of the substrate immediately before the thickness adjusting means (4) and the traveling direction of the substrate immediately after the thickness to 0.5 degrees to 10 degrees, as shown in FIG. There is a method of moving the arrangement of (3) to the sending side or moving to the winding side. Further, there is a method of installing the thickness adjusting means (4) on the winding side or the sending side from the position shown in FIG. Further, there is a method of setting a winding roll (not shown) so that the traveling direction of the base material (1) after passing through the thickness adjusting means (4) is inclined from the vertical direction shown in FIG. 1 to the winding side or the feeding side. is there.
In the conventional method described in Patent Document 3 described above, the base material impregnated with the resin varnish is pulled up vertically from the resin varnish in the resin varnish bath, and vertically passed between the pair of thickness adjusting means, A method for removing excess varnish adhering to the surface of a substrate is described. However, this method could not produce a prepreg having surface resin layers with different thicknesses on the front and back sides.

In this way, by running a long base material with the apparatus shown in FIG. 1, a predetermined amount of resin varnish is provided on the base material so that the front and back surfaces have different surface resin layers. It is possible to continuously impregnate and adjust the thickness. Thereafter, the base material impregnated with the resin varnish is dried and the resin in the base material is heated to form a B stage, whereby a prepreg can be formed.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.
[Composition of epoxy resin varnish]
5046B80 (Japan Epoxy Resin Co., Ltd., trade name): 70% by mass, 180S75B70 (Japan Epoxy Resin Co., Ltd., trade name): 14% by mass, Dicyandiamide: 1.6% by mass, 2-ethyl-4-methyl- Imidazole: 0.2% by mass, dimethylformamide: 7.1% by mass, methyl cellosolve: 7.1% by mass

[Example 1]
The substrate (1) was impregnated with the resin varnish (2) using the apparatus shown in FIG. As the substrate (1), glass cloth (product name: 1027MS thickness: 0.020 mm) manufactured by Asahi Kasei Electronics Co., Ltd. was used. The above-mentioned epoxy resin varnish was used for the resin varnish (2).
Further, the angle (A) formed by the traveling direction of the base material immediately before the thickness adjusting means (4) and the traveling direction of the base material immediately after is 1 ° (the height of the thickness adjusting means (4) and the height of the dip roll (3)). The difference in thickness was set to 255 mm). Then, after impregnating the base material (1) into the resin varnish (2), it is dried at a drying temperature of 160 ° C. for a time of 1 minute and 30 seconds, and the resin in the base material (1) is B-staged. A prepreg was obtained.

[Example 2]
The substrate (1) was impregnated with the resin varnish (2) using the apparatus shown in FIG. As the substrate (1), glass cloth (product name: 1027MS thickness: 0.020 mm) manufactured by Asahi Kasei Electronics Co., Ltd. was used. The epoxy resin varnish described above was used as the resin varnish.
Further, the angle (A) formed by the traveling direction of the base material immediately before the thickness adjusting means (4) and the traveling direction of the base material immediately after is 2 ° (the height of the thickness adjusting means (4) and the height of the dip roll (3)). The difference in thickness was set to 255 mm). Then, after impregnating the base material (1) into the resin varnish (2), it is dried at a drying temperature of 160 ° C. for a time of 1 minute and 30 seconds, and the resin in the base material (1) is B-staged. A prepreg was obtained.

[Example 3]
The substrate (1) was impregnated with the resin varnish (2) using the apparatus shown in FIG. As the substrate (1), glass cloth (product name: 1027MS thickness: 0.020 mm) manufactured by Asahi Kasei Electronics Co., Ltd. was used. The epoxy resin varnish described above was used as the resin varnish.
Further, the angle (A) formed by the traveling direction of the substrate immediately before the thickness adjusting means (4) and the traveling direction of the substrate immediately after is 3 ° (the height of the thickness adjusting means (4) and the height of the dip roll (3)). The difference in thickness was set to 255 mm). Then, after impregnating the base material (1) into the resin varnish (2), it is dried at a drying temperature of 160 ° C. for a time of 1 minute and 30 seconds, and the resin in the base material (1) is B-staged. A prepreg was obtained.

[Comparative Example 1]
The substrate (1) was impregnated with the resin varnish (2) using the apparatus shown in FIG. As the substrate (1), a glass cloth (product name: 1027MS, thickness 0.020 mm) manufactured by Asahi Kasei Electronics Co., Ltd. was used. The epoxy resin varnish described above was used as the resin varnish.
Further, the angle (A) formed by the traveling direction of the base material immediately before the thickness adjusting means (4) and the traveling direction of the base material immediately after is 0 ° (the height of the thickness adjusting means (4) and the height of the dip roll (3)). The difference in height is 255m
m). Then, after impregnating the base material (1) into the resin varnish (2), it is dried at a drying temperature of 160 ° C. for a time of 1 minute and 30 seconds, and the resin in the base material (1) is B-staged. A prepreg was obtained.

The prepregs formed in Examples 1 to 3 and Comparative Example 1 were embedded and polished with an epoxy resin cured at room temperature, and the prepreg cross section was cut out. A photograph was taken (magnification 1000). Table 1 shows the results of measuring the thickness of the surface resin layer of each prepreg for each of the back surface. The unit is mm. The thickness of the surface resin layer was defined as the distance from the filament closest to the surface to the surface in the cross section of the yarn bundle, and the surface resin layer having the larger thickness was used as the back surface for convenience.
As can be seen from Table 1, the surface resin layer thicknesses of the prepregs of Examples 1 to 3 have surface resin layers with different thicknesses on the front and back sides. Regarding Comparative Example 1, the thickness of the surface resin layer was the same on the front and back of the prepreg.

  The present invention is suitable as a method for producing a prepreg particularly suitable for producing a multilayer wiring board.

It is sectional drawing of an example of the principal part of the apparatus suitably used with the method of this invention. It is an example of the suitable cross-sectional shape of a thickness adjustment means.

Explanation of symbols

1. . . Base material 2. . . Varnish 3. . . Dip roll 4. . . 4. Thickness adjusting means comprising a pair of rolls . . Resin varnish bath A. . . Thickness adjusting means (4) The direction of travel of the base material immediately before and the direction of travel of the base material immediately after
Angle B. . . Actual dip roll for virtual dip roll when angle (A) is 0 degree
Position shift amount of (3) C.I. . . Contact point between thickness adjusting means (4) and traveling substrate

Claims (5)

  A method for producing a prepreg including an impregnation step of impregnating a resinous varnish into a traveling long base material, an adjustment step of adjusting the amount of the resin varnish impregnated in the base material, and a drying step of heating and drying the resin varnish. When the substrate passes through the thickness adjusting means in the adjusting step, the traveling direction of the substrate immediately after passing through the thickness adjusting means is the traveling direction of the substrate immediately before passing through the thickness adjusting means. A method for producing a prepreg, characterized in that a substrate is caused to travel in different states.   The angle (A) between the traveling direction of the base material immediately after passing through the thickness adjusting means and the traveling direction of the base material immediately before passing through the thickness adjusting means is 0.5 to 10 degrees. The method for producing a prepreg according to claim 1.   The method for producing a prepreg according to claim 1 or 2, further comprising a laminating step of laminating a support base film or a metal foil on one side or both sides of the prepreg after the drying step.   The method for producing a prepreg according to any one of claims 1 to 3, wherein the substrate is a glass cloth.   The thickness of a glass cloth is 0.010-0.050 mm, The manufacturing method of the prepreg of Claim 4 characterized by the above-mentioned.

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