JPH09232756A - Manufacture of multilayered printed-wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufactuting a multilayered printed-wiring board of a build-up system, which makes the adhesion of an insulating layer to a conductor layer enhance and makes to provide the printed-wiring board with a high-adhesion conductor circuit. SOLUTION: An insulating layer consisting of a resin composition formed by dispersing an inorganic filler soluble to a hydrogen fluoride solution in a matrix resin refractory to the hydrogen fluoride solution is formed on the surface of a core board having a conductor circuit on its surface and thereafter, a perforating is conducted in the above insulating layer by a laser beam. Then, the surface of the insulating layer including the wall surface of the hole is subjected to a surface treatment with a hydrogen fluoride solution, then, a plated layer is formed on the surface of the insulating layer including the wall surface of the hole and moreover, a prescribed conductor circuit is formed on this plated layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a build-up type multilayer printed wiring board in which a circuit pattern is formed on an insulating layer.

[0002]

2. Description of the Related Art In recent years, as electronic and electric devices have become smaller and lighter, there has been a demand for thinner multilayer printed wiring boards. In order to meet this demand, a build-up type multilayer printed wiring board, in which a circuit pattern is stacked and formed on the surface of a core substrate via an insulating layer, has been receiving attention. In this build-up type multilayer printed wiring board, compared to the conventional multilayer printed wiring board in which the conductor circuits of each layer are connected after they are multilayered at once, the wiring is not obstructed by the through holes, so the wiring pitch is the same. Since the density is improved and the insulating layer can be formed thin, there is an advantage that the multi-layer printed wiring board can be made higher in density and thinner. As a manufacturing method thereof, a method of sequentially performing the following steps is known. An insulating layer made of a resin composition is formed on the surface of a core substrate (including a multilayer substrate) having a conductor circuit on the surface. A via hole is formed in the obtained insulating layer. The surface of the insulating layer in which the via hole is formed is roughened by the desmear treatment. A conductor layer is formed on the insulating layer by a method such as copper plating, and then a predetermined circuit pattern is formed on the conductor layer. At this time, a conductor is also provided on the wall surface of the via hole, and the conductor circuit of the core substrate and the conductor circuit on the insulating layer are electrically connected by this conductor. Hereinafter, the above steps are repeated to manufacture a desired multilayer printed wiring board.

Regarding the method of manufacturing the above-mentioned build-up type multilayer printed wiring board, a method of forming an insulating layer by using a photosensitive resin and forming a via hole by a photolithography method (JP-A-62-206899, (JP-A-4-199783, etc.) or a method of forming an insulating layer using a thermosetting resin and forming via holes by laser processing (JP-A-62-291).
No. 095, JP-A-3-233997, etc.) have been proposed.

However, in the above build-up method for manufacturing a multilayer printed wiring board, when the insulating layer is formed by using a thermosetting resin, the curing agent remaining on the surface of the cured thermosetting resin is not reacted. It is considered that the degree of surface roughening of the insulating layer due to desmear treatment becomes uneven depending on the location due to the influence of the components, the degree of hardening, and the oxidation of the surface of the thermosetting resin due to the oxidizing atmosphere. There is a problem that the adhesion between the conductor layer and the insulating layer formed by a method such as copper plating on the roughened insulating layer is insufficient,
The improvement was required.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the adhesion between the insulating layer and the conductor layer. Provided is a method for manufacturing a build-up type multilayer printed wiring board, which can obtain a multilayer printed wiring board having a conductor circuit having high adhesion.

[0006]

According to a first aspect of the present invention, there is provided a method for manufacturing a multilayer printed wiring board, comprising: a core resin having a conductor circuit on the surface thereof; After forming an insulating layer made of a resin composition in which an inorganic filler soluble in a hydrogen fluoride-based solution is dispersed, the insulating layer is laser-drilled, and then the surface of the insulating layer including the wall surface of the hole is formed. Is surface-treated with a hydrogen fluoride-based solution, then a plating layer is formed on the surface of the insulating layer including the wall surface of the hole, and then a predetermined conductor circuit is formed on this plating layer.

According to a second aspect of the present invention, there is provided a method for producing a multilayer printed wiring board according to the first aspect, wherein the hydrogen fluoride-based solution is a solution containing ammonium hydrogen fluoride or hydrogen fluoride. Characterize.

A method for manufacturing a multilayer printed wiring board according to a third aspect of the present invention is the method for manufacturing a multilayer printed wiring board according to the first or second aspect, wherein the insulating layer formed on the surface of the core substrate is composed of two layers. The content of the inorganic filler in the insulating layer on the side in contact with the surface of the substrate is lower than the content of the inorganic filler in the insulating layer on the side far from the surface of the core substrate.

According to a fourth aspect of the present invention, there is provided a method for producing a multilayer printed wiring board according to any one of the first to third aspects, wherein the inorganic filler is mica or silica. .

In the present invention, an insulating layer made of a resin composition in which an inorganic filler soluble in a hydrogen fluoride solution is dispersed is formed, and the surface of the insulating layer is surface-treated with the hydrogen fluoride solution. Next, by forming a plating layer on the surface of the insulating layer, the inorganic filler present on the surface of the insulating layer is selectively removed by the hydrogen fluoride-based solution, so that a so-called anchor effect is generated, and the plating with the insulating layer is performed. It has the effect of improving the adhesion with the layer (conductor layer).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, on a surface of a core substrate having a conductor circuit on its surface, an inorganic filler soluble in a hydrogen fluoride-based solution is contained in a matrix resin which is hardly soluble in the hydrogen fluoride-based solution. An insulating layer made of the dispersed resin composition is formed. Examples of the core substrate having a conductor circuit used in the present invention include a substrate having a conductor circuit formed on the surface by etching a copper-clad laminate of FR-4 grade or FR-5 grade. . The term "hydrogen fluoride solution" as used herein refers to a solution containing a hydrogen fluoride component capable of substantially etching an inorganic component such as a SiO ₂ component, such as an aqueous solution of ammonium hydrogen fluoride or Examples thereof include an aqueous solution of hydrogen fluoride (hydrofluoric acid). Further, the matrix resin which is hardly soluble in the hydrogen fluoride-based solution is not particularly limited, but an epoxy resin-based thermosetting resin used for FR-4 grade or FR-5 grade copper-clad laminate Examples thereof include polyimide resin-based thermosetting resins, and an optimum matrix resin may be selected depending on the operating temperature range of the multilayer printed wiring board. The inorganic filler soluble in the hydrogen fluoride solution is not particularly limited, but crushed silica,
Examples include crushed mica and spherical silica, and the most suitable one may be selected according to the characteristics required for the multilayer printed wiring board. Regarding the shape of the inorganic filler used in the present invention, a crushed or spherical shape is preferable to a short fiber shape in order to improve the adhesion between the insulating layer and the plating layer. The particle size of the inorganic filler is not particularly limited, but an average particle size of about 2 to 15 μm is preferable for improving the adhesion between the insulating layer and the plating layer. Moreover, the content of the inorganic filler in the resin composition forming the insulating layer is not particularly limited, but is preferably in the range of 5 to 40% by weight. 5
If it is less than 40% by weight, the effect of improving the adhesion between the insulating layer and the plating layer tends to be insufficient, and if it exceeds 40% by weight, the film-forming property of the insulating layer may be impaired.

As a method for forming the insulating layer on the surface of the core substrate, a curtain coater method, a spray method and the like can be exemplified, but there is no particular limitation. Then, depending on the matrix resin used, a resin composition for forming an insulating layer may be applied, followed by drying and curing to form a cured film. Furthermore, the insulating layer formed on the surface of the core substrate has a two-layer structure, and as shown in FIG. 1, the inorganic filler content ratio of the insulating layer 3a on the side in contact with the surface of the core substrate 1 on which the conductor circuit 2 is provided is the core. It is preferable to lower the content of the inorganic filler in the insulating layer 3b on the side farther from the surface of the substrate, because it is possible to prevent the adhesion between the surface of the core substrate and the insulating layer from decreasing due to the presence of the inorganic filler. Also, 2
In the case of a layered structure, the type of matrix resin of each layer may be different.

In the present invention, the insulating layer formed on the surface of the core substrate as described above is laser-drilled. If a conductor circuit serving as a protection portion against the laser is provided on the core substrate at the position where the laser is irradiated, the laser is reflected by the conductor circuit, and only the insulating layer is selectively perforated. The laser used in the present invention is not particularly limited, but a carbon dioxide gas laser can be exemplified. In the present invention, after the insulating layer is perforated with a laser, the surface of the insulating layer including the wall surface of the hole is surface-treated with a hydrogen fluoride-based solution. As the hydrogen fluoride-based solution to be used, an aqueous solution of ammonium hydrogen fluoride or an aqueous solution of hydrogen fluoride (hydrofluoric acid) can be exemplified as described above, but an aqueous solution of ammonium hydrogen fluoride is preferable from the viewpoint of handleability. .
An additive such as a surfactant for improving the wettability of the substrate may be added to the hydrogen fluoride-based solution,
You may make it heat to about 40-60 degreeC.

In the present invention, after the surface of the insulating layer is surface-treated with a hydrogen fluoride-based solution, a plating layer is formed on the surface of the insulating layer including the wall surfaces of the holes, and then a predetermined conductor circuit is formed on the plating layer. To do. The method for forming the plating layer is not particularly limited, and a method of performing electroless plating followed by electrolytic plating may be used. The method of forming the conductor circuit on the plating layer is not particularly limited, and may be a method of covering the non-etched portion with an etching resist, etching the resist, and then peeling the resist.

[0015]

EXAMPLES In the following Examples and Comparative Examples, the step of laser drilling in the insulating layer was omitted, a plating layer was formed, and the adhesion between the plating layer and the insulating layer was evaluated.

(Examples 1 to 3) Brominated bisphenol A
Type epoxy resin (Dow Chemical Co., trade name: DER5
11) 70 parts by weight, cresol novolac type epoxy resin (manufactured by Tohto Kasei Co., trade name: YDCN702P) 30 parts by weight, dicyandiamide 3.5 parts by weight, 2-ethyl 4-methylimidazole 0.08 parts by weight dissolved in an organic solvent Then, a resin varnish A was prepared. An inorganic filler was added to this resin varnish A as shown in Table 1 and mixed to prepare a resin varnish containing an inorganic filler. In addition, the addition amount shown in Table 1 shows weight% in the solid content of the whole resin varnish containing an inorganic filler.

[0017]

[Table 1]

The resin varnish containing the inorganic filler obtained above was applied to the surface of a core substrate having a circuit formed on a FR-4 grade copper-clad laminate using a curtain coater, and then,
Multi-stage heating at 120 ° C./20 minutes + 145 ° C./30 minutes was performed to form an insulating layer having a thickness of 50 μm and made of a resin composition in which an inorganic filler was dispersed. Next, a desmear process is performed for the purpose of removing the oxide film on the surface of the formed insulating layer.
As the desmear liquid, a swelling liquid manufactured by Shipley (product number MLB
211) and KMnO ₄ liquid (product number MLB213),
Each liquid was treated at 80 ° C for 10 minutes. Then, the surface of the insulating layer is treated at 60 ° C./10 with a hydrogen fluoride solution.
The inorganic filler on the surface of the insulating layer was dissolved and removed by performing the surface treatment under the condition of minutes. As the hydrogen fluoride-based solution, a glass etching agent (mixed liquid of trade name Enplate MLB498 and trade name Enplate MLB glass etch additive) manufactured by Meltex Co. containing hydrogen fluoride as a component was used. Then, a plating layer made of a copper film having a thickness of 10 μm was formed on the surface of the insulating layer. The plating layer is formed by using a Rochelle salt type electroless copper plating solution manufactured by Shipley Co., Ltd. and forming a thin film by an electroless plating method, and then using a copper sulfate-based electroplating solution. The electroplating was performed for 60 minutes under the condition of / dm.

Next, the adhesion between the obtained plated layer and the insulating layer was evaluated by the peel strength. The peel strength was measured by cutting the core substrate on which the plating layer was formed to form a strip having a width of 1 cm, and measuring the L-shaped peel strength between the plating layer and the insulating layer. The measurement was performed at a peeling speed of 1 mm / min. Table 2 shows the obtained results.

Example 4 FR-4 used in Example 1
A core substrate having a circuit formed on a grade copper-clad laminate was also used as the core substrate in Example 4. On the surface of this core substrate, the above resin varnish A (without addition of inorganic filler) was applied with a curtain coater, and then 120 ° C./20 minutes + 1
The thickness is 25 μm after being subjected to multi-stage heating at 45 ° C / 30 minutes.
The underlying insulating layer made of the resin composition in which the inorganic filler was not dispersed was formed. Next, the resin varnish containing the inorganic filler used in Example 1 was applied onto the underlying insulating layer with a curtain coater, and then 120 ° C./20 minutes + 145.
By performing multi-step heating at 30 ° C./30 minutes, a surface insulating layer having a thickness of 25 μm and made of a resin composition in which an inorganic filler is dispersed was formed. In this way, a two-layer insulating layer was formed on the surface of the core substrate. Then, in the same manner as in Example 1, desmear treatment, surface treatment of the surface of the insulating layer with a hydrogen fluoride-based solution, formation of a plating layer, and evaluation of the adhesion between the plating layer and the insulating layer were performed. Table 2 shows the obtained evaluation results.

(Comparative Example 1) In place of the resin varnish containing an inorganic filler used in Example 1, only the resin varnish A containing no inorganic filler was used to form the insulating layer. In the same manner as in Example 1, formation of an insulating layer, desmear treatment, surface treatment of the surface of the insulating layer with a hydrogen fluoride-based solution, formation of a plated layer, and evaluation of adhesion between the plated layer and the insulating layer were performed. Table 2 shows the obtained evaluation results.

[0022]

[Table 2]

[0023]

According to the present invention, on the surface of a core substrate having a conductor circuit on its surface, an inorganic filler soluble in a hydrogen fluoride solution is dispersed in a matrix resin which is hardly soluble in the hydrogen fluoride solution. After forming the insulating layer made of the resin composition,
The surface of the insulating layer is surface-treated with a hydrogen fluoride-based solution, and then a plating layer is formed on the surface of the insulating layer. Therefore, compared with the case where the insulating layer is formed only by using the resin composition containing no inorganic filler, the insulating layer is insulated. The adhesion between the layer and the conductor layer is improved. Therefore, according to the present invention, it becomes possible to manufacture a multilayer printed wiring board including a conductor circuit having high adhesion.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining an embodiment of the present invention.

[Explanation of symbols]

 1 core substrate 2 conductor circuit 3a, 3b insulating layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Sugiyama 1048, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Works Ltd. (72) Inventor, Shingo Yoshioka, 1048, Kadoma, Kadoma, Osaka Prefecture 72) Inventor Shinichi Ikeya, 1048, Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Works Co., Ltd. (72) Hiroaki Fujiwara, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Inventor, Katsuhiko Ito, Osaka Prefecture 1048 Kadoma, Kadoma City, Matsushita Electric Works Co., Ltd. (72) Inventor, Kiyoaki Ihara, 1048 Kadoma, Kadoma City, Osaka Prefecture Osaka, Ltd. (72), Satoru Ogawa, 1048 Kadoma, Kadoma City, Osaka Matsushita Denko stock company

Claims (4)

[Claims] 1. A resin composition in which an inorganic filler soluble in a hydrogen fluoride-based solution is dispersed in a matrix resin which is hardly soluble in the hydrogen fluoride-based solution, on the surface of a core substrate having a conductor circuit on the surface. After forming an insulating layer made of a material, the insulating layer is perforated with a laser, then the surface of the insulating layer including the wall surface of the hole is surface-treated with a hydrogen fluoride-based solution, and then the insulating layer including the wall surface of the hole is formed. A method for manufacturing a multilayer printed wiring board, comprising forming a plating layer on the surface and then forming a predetermined conductor circuit on the plating layer. 2. The method for producing a multilayer printed wiring board according to claim 1, wherein the hydrogen fluoride-based solution is a solution containing ammonium hydrogen fluoride or hydrogen fluoride. 3. The insulating layer formed on the surface of the core substrate is composed of two layers, and the inorganic filler content of the insulating layer on the side in contact with the surface of the core substrate is the inorganic filler on the side far from the surface of the core substrate. The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the content is lower than the filler content. 4. The method for producing a multilayer printed wiring board according to any one of claims 1 to 3, wherein the inorganic filler is mica or silica.