JP2003198142A - Multilayer board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer board having a high thickness accuracy for an insulation layer over an inner layer circuit, and also to provide a multilayer board manufactured by the method. <P>SOLUTION: In the method of manufacturing a multilayer board by heating and pressurizing a laminate 8, a resin composite of a prepreg 1a includes a resin composition layer 3a having a high viscosity in a molten state and a small fluidity. In laminating formation, therefore, even a portion of the resin composition layer above the inner layer circuit 6 where an area of the inner layer circuit 6 formed on the surface of a substrate 5 for an inner layer is relatively small can be prevented from becoming thin due to the fluidity with application of pressure. Consequently, an unevenness in thickness of the insulation layer 9 which depends on the relative size of areas dominated by the inner layer circuits 6 formed on the surface of the substrate 5 for an inner layer can be reduced, leading to the unification of the overall thickness of the insulation layer 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multilayer board having an insulating layer having a good thickness accuracy and a multilayer board produced by this method.

[0002]

2. Description of the Related Art A multilayer printed wiring board is manufactured by forming a circuit on the surface of a metal foil-clad multilayer board. This multilayer board is manufactured using a prepreg. For the prepreg, for example, a resin composition containing a thermosetting resin such as an epoxy resin as a main component is prepared, a base material such as glass cloth is impregnated in the resin composition, and the impregnated resin is semi-cured. It is obtained by setting the state (so-called B stage state). A metal foil-clad multilayer board is obtained by disposing a metal foil such as a copper foil on both sides or one side of a laminate obtained by stacking a required number of the prepregs and the inner layer substrate, and heating and pressing.

[0003]

However, in the production of the above-mentioned multilayer board, when attention is paid to the areas where the areas of the inner layer circuits on the surface of the inner layer boards are different from each other, the insulation formed on both inner layer boards is high. There is a problem that it is difficult to make the layer thickness uniform.

That is, at a portion of the surface of the inner layer substrate where the area of the inner layer circuit is small, when the prepreg is laminated on the surface of the inner layer substrate, a part of the semi-cured resin in the prepreg flows out from the prepreg. Therefore, the thickness of the insulating layer formed on the upper part of the inner layer circuit tends to be thinned, and conversely, in the part where the area of the inner layer circuit on the surface of the inner layer substrate is large, Since the thickness of the insulating layer formed on the upper part of the inner layer circuit tends to be thick, it is difficult to make the thickness of the insulating layer on the upper part of the inner layer circuit uniform in the entire multilayer board. As a result, this has been a cause of problems such as difficulty in controlling the impedance depending on the thickness of the insulating layer above the inner layer circuit.

The present invention has been made in view of the above circumstances, and an object of the present invention is to manufacture a multilayer board in which an insulating layer above an inner layer circuit has good thickness accuracy and a method for manufacturing the same. To provide a multilayer board.

[0006]

In order to solve the above-mentioned problems, in the method for producing a multilayer board of the invention according to claim 1, a resin composition is applied to the surface of an inner layer substrate on which an inner layer circuit is formed. In a method for manufacturing a multilayer board, in which a prepreg formed by impregnating a substrate and heating is laminated to obtain a multilayer board, a resin-impregnated substrate formed by impregnating the substrate with the resin composition as the prepreg and heating. Of at least one side of the resin composition is applied, using a prepreg obtained by heating, and a resin composition layer formed by applying the resin composition to the surface of the inner layer substrate is It is characterized in that the prepregs are laminated and formed so as to be in contact with each other.

In the method for manufacturing a multilayer board according to the second aspect of the present invention, a prepreg formed by impregnating a base material with a resin composition and heating to form a prepreg is laminated on the surface of the inner layer substrate on which the inner layer circuit is formed. In the method for producing a multilayer board by obtaining
As the prepreg, a substrate is impregnated with the resin composition,
A resin-impregnated base material formed by heating is impregnated with the resin composition, and a prepreg obtained by heating is used, and the surface of the inner layer substrate is newly impregnated with the resin composition. It is characterized in that the prepreg is laminated and molded so that the formed resin composition layers are in contact with each other.

In the multilayer board of the invention according to claim 3,
A multilayer board manufactured by the method for manufacturing a multilayer board according to claim 1 or claim 2.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The method for producing a multilayer board of the present invention and the multilayer board produced by the method are not limited to the following embodiments, and various modifications may be made without departing from the scope of the present invention. Of course. Here, FIG. 1 shows a manufacturing procedure of the prepreg 1a used in the method for manufacturing a multilayer board according to the present invention.
(A) is a schematic sectional view showing the base material 2, (b) is a schematic sectional view showing the resin-impregnated base material 3, and (c) a new layer 4 of the uncured resin composition is formed on at least one side surface. FIG. 3D is a schematic cross-sectional view showing the resin-impregnated base material 3 prepared, and FIG. 3D is a schematic cross-sectional view showing the prepared prepreg 1a. FIG. 2 is a schematic cross-sectional view schematically showing the laminated body 8 used for the method for manufacturing a multilayer board of the present invention for each constituent material. FIG. 3 is a cross-sectional view showing a main part of a multilayer board 10 obtained by laminating and molding the laminated body 8.

A method of manufacturing the multilayer board of the present invention will be described. First, as shown in FIG. 1, a prepreg is prepared. That is, as the prepreg 1, a resin composition varnish (here, “resin composition varnish” refers to a liquid mixture obtained by diluting an uncured resin composition with a solvent).
A new layer 4 of the uncured resin composition is formed on at least one side of a resin-impregnated base material 3 (FIG. 1 (b)) formed by impregnating and heating (FIG. 1 (a)) (FIG. 1 (c)), two types of resin composition layers 3 having different degrees of curing by heating
A prepreg 1a (FIG. 1 (d)) having a and 4a is prepared. The formation of the new layer 4 of the uncured resin composition described above is specifically achieved by a method of applying the resin composition varnish to at least one side surface of the resin-impregnated base material 3 or newly impregnating the resin composition varnish. To be done.

Further, in this case, the resin composition layer 3a is derived from the resin composition which the resin-impregnated base material 3 originally has, and the uncured resin composition layer 4 formed after the above is formed. Since the degree of curing is higher than that of the derived resin composition layer 4a, it is considered that the viscosity at the time of melting is relatively high and the fluidity is relatively small.

Next, as shown in FIG. 2, a multilayer board 10 is prepared using the prepreg 1a. That is, the prepreg 1a is laid on the surface 5a of the inner layer substrate 5 on which the inner layer circuit 6 is formed so that the resin composition layer 4a of the prepreg 1a is in contact with the metal layer 7 made of a metal foil such as copper foil. 3 is produced, and further, as shown in FIG. 3, the laminate 8 is heated and pressed to make resin composition layers 3a and 4a (both layers are in a so-called semi-cured state (B
Although it is in a stage state), since the resin composition layer 3a has a higher degree of curing than the resin composition layer 4a as described above, it is considered that the resin composition layer 3a has a relatively high viscosity during melting and a low fluidity. To be ) Is cured to form the insulating layer 9 to obtain the multilayer board 10.

That is, in the method for producing a multilayer board of the present invention, the prepreg 1 formed by impregnating the base material 2 with the resin composition and heating it is laminated on the outer side of the inner layer substrate 5 having the inner layer circuit 6 formed on the surface. In the method for producing a multilayer board by molding to obtain a multilayer board,
As the prepreg 1, a new layer 4 of the uncured resin composition is formed on at least one side surface of the resin-impregnated base material 3 formed by impregnating the base material with the resin composition and heating.
The prepreg 1a obtained by heating is used, and the prepreg 1 is formed on the surface 5a of the inner layer substrate 5.
a so that the resin composition layer 4a of a is in contact with the prepreg 1
a is stacked and a metal layer 7 made of a metal foil such as a copper foil is further stacked on the outer side to form a laminated body 8 (FIG. 2), and the laminated body 8 is heated and pressed to semi-cured the prepreg 1a. (So-called B stage state) resin composition layers 3a and 4
This is to cure a and form the insulating layer 9 to manufacture the multilayer board 10 (FIG. 3).

The prepreg 1 usable here is
By the heat treatment for a relatively long time, the resin composition layer 3a that has been hardened further is formed, while a new layer 4 of the uncured resin composition is formed on at least one side surface. As long as it has a resin composition layer 4a in a stage state and can be laminated so as to be in contact with the surface 5a of the substrate 5 for inner layer, the resin composition layer 4a can be formed as shown in the above embodiment. The present invention is not limited to the prepreg 1a formed only on the side surface, but may be a prepreg 1b (not shown) having the resin composition layer 4a formed on both side surfaces, and is not particularly limited.

As described above, according to the method for producing a multilayer board of the present invention, a laminate 8 is produced by stacking the prepreg 1a so that the resin composition layer 4a of the prepreg 1a is in contact with the surface 5a of the inner layer substrate 5. Further, the laminated body 8 is heated and pressed to cure the resin composition layers 3a and 4a in the semi-cured state (so-called B-stage state) to form the insulating layer 9 to produce the multilayer board 10. However, as will be described later, in the multilayer board manufactured by the manufacturing method according to the present invention, the insulation is dependent on the relative area of the inner layer circuit 6 formed on the surface of the inner layer substrate 5 during the lamination molding. The problem of variations in the thickness of layer 9 is mitigated to a considerable extent,
It has been found that the thickness of 1 is more uniform over the entire surface of the multilayer board 10. The reason may be as follows.

That is, in the resin composition layers 3a and 4a, as described above, since the resin composition layer 3a has a higher degree of curing than the resin composition layer 4a, the viscosity at the time of melting is relatively higher. It is thought to be high and low in liquidity,
Compared with the case where the resin composition of prepreg 1 has a low viscosity when melted and is composed only of a resin composition layer having a large fluidity, the resin composition of prepreg 1 has a high viscosity when melted, Since the resin composition layer 3a having a low fluidity is included, even in a region where the area of the inner layer circuit 6 formed on the surface of the inner layer substrate 5 is relatively small at the time of laminate molding,
It is possible to prevent the resin composition layer above the inner layer circuit 6 from becoming extremely thin due to the flow at the time of pressurization, and as a result, the relative amount occupied by the inner layer circuit 6 formed on the surface of the inner layer substrate 5 is It is considered that the variation in the thickness of the insulating layer 9 depending on the size of the area is alleviated and the thickness of the insulating layer 9 is made more uniform over the entire surface.

That is, according to this method for manufacturing a multilayer board, it is possible to manufacture a multilayer board in which variations in the thickness of the insulating layer are reduced, and as a result, the multilayer wiring board manufactured by processing the multilayer board 10 is manufactured. Can reliably maintain insulation between circuit patterns formed on different layers, prevent short-circuit defects from occurring in the circuit patterns, and make it easier to control impedance. I can say.

Further, according to this method for producing a multilayer board, the resin composition layer 3a and the resin composition layer 4a having a low viscosity at the time of melting during lamination molding and a high fluidity are also provided. Since the prepreg 1 is laminated so as to be in contact with the surface 5a on which the inner layer circuit 6 of the inner layer substrate 5 is formed, the resin composition layer having a high viscosity and a low fluidity at the time of lamination molding is used as the inner layer substrate 5 It can be said that the effect of suppressing the generation of voids and the like near the surface 5a of the inner layer substrate 5 is large as compared with the case of contacting the surface 5a.

On the other hand, as the thermosetting resin constituting the above resin composition, bisphenol A type epoxy resin, cresol novolac type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin,
Further, epoxy resins such as bromides thereof can be mentioned. These resins may be used alone or in combination of two or more.

The above resin composition may, of course, contain a curing agent. Examples of such a curing agent include acid anhydrides such as dicyandiamide, phenol novolac, and trimellitic anhydride.

The above resin composition may be used, if necessary.
A curing accelerator and other additives may be included. Examples of the curing accelerator include imidazoles such as 2-ethyl-4-methylimidazole, 2-methylimidazole and 2-phenyl-4-methylimidazole, dimethylbenzylamine, triethylenediamine, benzyldimethylamine and triethanolamine. Amines such as Organic phosphines such as triphenylphosphine, diphenylphosphine and phenylphosphine, tetra-substituted phosphonium / tetra-substituted borate such as tetraphenylphosphonium / ethyltriphenylborate, 2
Examples thereof include phenylboron salts such as -ethyl-4-methylimidazole / tetraphenylborate.

The above-mentioned resin composition is prepared by blending the above-mentioned thermosetting resin and, if necessary, a curing agent, a curing accelerator and other additives, and uniformly mixing them with a mixer, a blender or the like. It can be prepared by These can be used as a resin varnish impregnating a base material or a resin varnish applied to a resin-impregnated base material. In addition, a solvent such as methyl ethyl ketone (MEK), methoxypropanol (MP), dimethylformamide (DMF) or the like may be used for this preparation, or may be performed without using a solvent.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples.

The epoxy resin is a brominated epoxy resin (manufactured by Tohto Kasei Co., Ltd., "YDB-500": epoxy equivalent 500, bromine content about 21% by mass), cresol novolac type epoxy resin (Dainippon Ink and Chemicals Incorporated). "N-690" manufactured by the company: Epoxy equivalent 225) was used.

Further, dicyandiamide (molecular weight 84, theoretical active hydrogen equivalent 21) was used as a curing agent, 2-ethyl-4-methylimidazole was used as a curing accelerator, and methyl ethyl ketone (ME
K), methoxypropanol (MP) and dimethylformamide (DMF) were used.

<Preparation of Resin Composition Varnish> As an epoxy resin, a brominated epoxy resin (manufactured by Toto Kasei Co., Ltd.,
"YDB-500": Epoxy equivalent of 500, bromine content of about 21% by mass, 90% by mass, cresol novolac type epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., "N-6")
90 ": 10% by mass of epoxy equivalent 225), 2.5% by mass of dicyandiamide as a curing agent, and 0.1% by mass of 2-ethyl-4-methylimidazole as a curing accelerator. A resin composition (uncured) and a solvent such as methyl ethyl ketone (ME
K) and dimethylformamide (DMF) were mixed in a ratio of 1: 1 (mass ratio), and the mixture was diluted and mixed so that the content of the resin composition (uncured) was 60% by mass. To prepare a resin composition varnish (herein, “resin composition varnish” means a liquid mixture obtained by diluting an uncured resin composition with a solvent).

<Preparation of prepreg> (Example 1) A glass cloth (manufactured by Nitto Boseki Co., Ltd., 101 type cloth) was used as a substrate, and the resin composition varnish prepared as described above was applied to the glass cloth at room temperature. After that, the solvent was dried and removed by heating at 130 to 170 ° C. for 3 minutes with a non-contact type heating unit, and the resin composition was semi-cured to prepare a resin-impregnated base material.

Further, the above resin composition varnish is applied to the above resin-impregnated base material at room temperature by a die coater, and then 130 to 17 by a non-contact type heating unit.
The resin composition was semi-cured by heating at 0 ° C. for 3 minutes to obtain a prepreg.

Example 2 A glass cloth (101 type cloth manufactured by Nitto Boseki Co., Ltd.) was used as a base material, and the glass composition was impregnated with the resin composition varnish prepared as described above at room temperature, Then, the solvent was dried and removed by heating at 130 to 170 ° C. for 3 minutes with a non-contact type heating unit, and the resin composition was semi-cured to prepare a resin-impregnated base material.

Further, the above resin composition varnish is impregnated at room temperature, and then, by a non-contact type heating unit,
The resin composition was semi-cured by heating at 130 to 170 ° C. for 3 minutes to obtain a prepreg.

Comparative Example A glass cloth (101 type cloth manufactured by Nitto Boseki Co., Ltd.) was used as a substrate, and the resin composition varnish of Example 1 prepared as described above was applied to the glass cloth at room temperature. After impregnation, the solvent was dried and removed by heating at 130 to 170 ° C. for 3 minutes with a non-contact type heating unit, and the resin composition was semi-cured to obtain a prepreg.

(Manufacture and Evaluation of Multilayer Plate) Using the prepregs of Examples 1 and 2 and Comparative Example, the following multilayer plates were prepared and evaluated.

<Evaluation of Variation in Thickness of Insulating Layer> As an inner layer substrate, a 0.5 mm wide linear circuit pattern was previously formed on a copper foil (thickness 35 μm) on the surface of a double-sided copper-clad laminate having a thickness of 0.2 mm. (Hereinafter, referred to as "line-shaped circuit".)
In addition, a circular circuit pattern having a diameter of 5 cm (hereinafter referred to as “circular circuit”) is formed, and the prepregs of Examples 1 and 2 and Comparative Example described above are superposed on both surfaces of the inner layer substrate. , Furthermore, overlay copper foil on both sides of this outside, 17
Heat and pressure molding was performed for 90 minutes at 0 ° C. and 2.94 MPa to obtain a multilayer board. After that, the thickness of the insulating layer formed on the line-shaped circuit and the circular circuit was measured at 30 points with an optical microscope, and the difference between the respective average values was calculated to obtain the variation in the thickness of the insulating layer.

Table 1 shows the above evaluation results.

[0035]

[Table 1] As can be seen from Table 1, from the results of Example 1 and Example 2, as described above, the resin composition layer having a high degree of curing, a relatively high melt viscosity, and a low fluidity was obtained. In Examples 1 and 2 using the prepreg which is considered to have, the resin composition of the prepreg used a prepreg composed only of a resin composition layer having a low melt viscosity and a large fluidity. In comparison with the case (comparative example), the area of the inner layer circuit formed on the surface of the inner layer substrate is relatively small, and the area of the inner layer circuit is relatively large. It was found that the difference between the average values of the thickness of the insulating layer in each part of the "circular circuit", that is, "the variation in the thickness of the insulating layer" was small. This is because, as described above, the prepregs used in Examples 1 and 2 are considered to have a resin composition layer having a relatively high melt viscosity and a low fluidity, so that the inner layer This is because variation in the thickness of the insulating layer, which depends on the relative size of the inner layer circuit formed on the surface of the insulating substrate, is reduced, and the thickness of the insulating layer is made more uniform over the entire surface. Conceivable.

[0036]

As described above, in the method for producing a multilayer board of the invention according to claim 1, the resin composition is impregnated into the base material and heated on the surface of the inner layer substrate on which the inner layer circuit is formed. In a method for producing a multilayer board by laminating a prepreg formed by laminating to obtain a multilayer board, as the prepreg, the resin composition is impregnated in a base material, and the resin is formed on at least one side of a resin-impregnated base material formed by heating. A prepreg obtained by applying a composition and heating is used, and the prepreg is laminated so that a resin composition layer formed by applying the resin composition on the surface of the inner layer substrate is in contact with the prepreg. Since it is characterized by being molded, it has an excellent effect that it is possible to manufacture a multilayer board in which variations in the thickness of the insulating layer are reduced.

In the method for producing a multilayer board according to the second aspect of the present invention, a prepreg formed by impregnating a base material with a resin composition and heating to form a prepreg is laminated on the surface of the inner layer substrate on which the inner layer circuit is formed. In the method for producing a multilayer board by obtaining
As the prepreg, a substrate is impregnated with the resin composition,
A resin-impregnated base material formed by heating is impregnated with the resin composition, and a prepreg obtained by heating is used, and the surface of the inner layer substrate is newly impregnated with the resin composition. Since the prepreg is laminated and molded so that the formed resin composition layer is in contact,
Similar to the invention of the method for manufacturing a multilayer board according to the first aspect, there is an excellent effect that it is possible to manufacture a multilayer board in which variation in the thickness of the insulating layer is reduced.

In the multilayer board of the invention according to claim 3,
Since it is a multilayer board manufactured by the method for manufacturing a multilayer board according to claim 1 or claim 2, it has an excellent effect that variation in thickness of the insulating layer is reduced.

[Brief description of drawings]

FIG. 1 shows a manufacturing procedure of a prepreg used in a method for manufacturing a multilayer board according to the present invention, in which (a) is a schematic sectional view showing a base material, and (b) is a schematic sectional view showing a resin-impregnated base material. Figure,
(C) A schematic cross-sectional view showing a resin-impregnated base material in which a new layer of the uncured resin composition is formed on at least one side surface,
(D) is a schematic sectional drawing which shows the produced prepreg.

FIG. 2 is a schematic cross-sectional view schematically showing a laminated body used for the method for producing a multilayer board of the present invention for each constituent material.

FIG. 3 is a cross-sectional view showing a main part of a multilayer board obtained by laminating and molding a laminate.

[Explanation of symbols]

1 prepreg 1a prepreg 2 base materials 3 Resin impregnated base material 3a resin composition layer 4a resin composition layer 4 uncured resin composition layer 5 Inner layer substrate 5a surface (inner layer substrate) 6 Inner layer circuit 7 metal layers 8 laminate 9 Insulation layer 10 Multi-layer board

Continued front page    F term (reference) 5E346 AA05 AA06 AA12 AA15 AA32                       AA38 BB01 CC04 CC09 CC32                       DD02 DD12 EE02 EE06 EE09                       EE13 GG02 GG28 HH11

Claims (3)

[Claims] 1. A method for producing a multi-layer board, comprising: forming a multi-layer board by laminating a prepreg formed by impregnating a substrate with a resin composition and heating the prepreg on the surface of the inner-layer substrate on which the inner-layer circuit is formed; As the above, the resin composition is impregnated into a base material, the resin composition is applied to at least one side of a resin-impregnated base material formed by heating, and a prepreg obtained by heating is used, and, A method for producing a multilayer board, wherein the prepreg is laminated and molded so that a resin composition layer formed by applying the resin composition to the surface of an inner layer substrate is in contact therewith. 2. A method for producing a multilayer board, comprising: forming a multilayer board by laminating a prepreg formed by impregnating a base material with a resin composition and heating the prepreg on the surface of the inner layer substrate having the internal circuit formed thereon, As the above, using a prepreg obtained by impregnating the resin composition into a resin-impregnated base material formed by heating the resin composition-impregnated base material, and heating, and, A method for producing a multilayer board, wherein the prepreg is laminated and molded so that a resin composition layer formed by newly impregnating the resin composition on the surface is in contact with the surface. 3. A multilayer board manufactured by the method for manufacturing a multilayer board according to claim 1.