JP2001085840A - Method for manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adhesion between conductor circuit layers and an insulating resin layer having openings formed as via holes and to thereby ensure stable peel strength, by irradiating the surface of the insulating resin layer with short-wavelength UV rays. SOLUTION: Firstly, an insulating resin layer is formed on an insulating substrate having a first circuit layer formed thereon. Next, an opening is formed in the insulating resin layer as a via hole for electrical interconnection of the first circuit layer with a second circuit layer. Subsequently, the surface of the resultant insulating resin layer is roughened using a roughening agent after or before being irradiated with short-wavelength UV rays. Then, the insulating resin layer is plated, and the second circuit layer and the via hole is formed, for interlayer connection of the first and second circuit layers through the via hole. The steps, the formation of the insulating resin layer and the opening, irradiation of the insulating resin layer with the UV rays and its roughening, and the formation of the circuit layers are repeated as required.

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 multilayer printed wiring board having excellent reliability by preventing a reduction in peel strength of a conductor due to unevenness in roughness. suggest.

[0002]

2. Description of the Related Art As a method of manufacturing a multilayer printed wiring board, there is conventionally known a technique called a so-called sequential lamination method in which a copper foil is laminated on a surface of an inner layer circuit board via a prepreg, and integrally formed by heating with a hot plate press. Have been. However, in this sequential lamination method, there is a limit in reducing the thickness in order to make a prepreg by impregnating a base material such as a glass cloth with an epoxy resin or the like. I can no longer respond.

On the other hand, recently, in order to cope with high-density and thinning of a multilayer printed wiring board, so-called hot-press molding by a hot plate press is not performed, and a glass cloth is not used as an interlayer insulating material. 2. Description of the Related Art A technique for manufacturing a multilayer printed wiring board by a build-up method has attracted attention.

According to this method of manufacturing a multilayer printed wiring board by the build-up method, since the conductive circuit layers and the insulating resin layers are alternately built up and multilayered, the wiring board is made denser and thinner. Can be adequately dealt with.

[0005]

However, multilayer printed wiring boards manufactured by this build-up method generally have conductor peeling more than multilayer printed wiring boards manufactured by heating and pressing using a prepreg. The strength tended to decrease, and particularly during mass production, a significant decrease in peel strength due to roughening unevenness was observed. There is a problem that the decrease in the peel strength greatly affects the connection reliability of the conductor circuit and the deterioration of the interlayer insulation.

Accordingly, the present invention has been made to solve such a problem, and a main object of the present invention is to improve the adhesion between a conductive circuit layer and an insulating resin layer to thereby ensure a stable peel strength. An object of the present invention is to provide a method for manufacturing a plate.

[0007]

Means for Solving the Problems The inventors of the present invention have intensively studied for realizing the above-mentioned object, and as a result, have conceived a method of forming the following contents as the gist of the present invention. That is, in order to solve the above problems, the method for manufacturing a multilayer printed wiring board according to the present invention comprises: (a) a step of forming an insulating resin layer on an insulating substrate on which a first circuit layer is formed; providing a via hole opening in the insulating resin layer formed in (a), (c) irradiating the surface of the insulating resin layer provided with the via hole opening in (b) with a short wavelength ultraviolet ray, (d) A step of roughening the surface of the insulating resin layer with a roughening agent; (e) plating the insulating resin layer to form a second circuit layer and a via hole; Performing a layer connection between the layer and the second circuit layer.

In another aspect, the method of manufacturing a multilayer printed wiring board according to the present invention comprises: (a) forming an insulating resin layer on an insulating substrate having a first circuit layer formed thereon;
(a) providing a via-hole opening in the insulating resin layer formed in (a), (c) roughening the surface of the insulating resin layer provided with the via-hole opening in (b) with a roughening agent (D) irradiating the roughened surface of the insulating resin layer surface with short-wavelength ultraviolet rays, (e) plating the insulating resin layer to form a second circuit layer and a via hole, and using the via hole Making an interlayer connection between the first circuit layer and the second circuit layer. As still another embodiment, a step of irradiating short-wavelength ultraviolet light before and after the step of roughening the surface of the insulating resin layer may be added. In the above-described embodiment,
The short-wavelength ultraviolet ray means one having a wavelength peak in a range of 150 to 280 nm. In the present invention, it is particularly preferable to use a low-pressure mercury lamp as the short-wavelength ultraviolet ray.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for manufacturing a multilayer printed wiring board according to the present invention is characterized in that the surface of the insulating resin layer or the surface of the insulating resin layer is roughened with a roughening agent. It is characterized in that the roughened surface of the insulating resin layer is subjected to a step of irradiating short-wavelength ultraviolet rays.

As a result, as a pretreatment, the wettability of the surface of the insulating resin layer with the roughening solution is improved, the roughening process is facilitated, and uniform roughening can be realized without causing unevenness of the roughening. On the other hand, as the post-treatment, the adsorptivity of the catalyst to the insulating resin surface is improved, and the electroless plating property is improved. As a result, stable conductor peel strength can be ensured.
Further, the process of irradiating short-wavelength ultraviolet rays is also effective as a process for removing smear generated when, for example, a via hole is formed in the insulating resin layer with a laser. High connection reliability can be maintained.

In the modification of the insulating resin layer, the energy intensity of ultraviolet light having a wavelength peak of 185 nm irradiated from short-wave ultraviolet light is as high as 647 kJ / mol, and most of the molecular bond energies (OH: 462.8 kJ / mol) are obtained. mo
1, CH: 413.4 kJ / mol, CC: 34
7.7 kJ / mol or the like) and has energy to cut the main chain and side chains on the surface of the insulating resin layer. In contrast, long-wavelength ultraviolet light such as a high-pressure mercury lamp having a wavelength peak at 365 nm, which is generally used, is
Since there is no energy to decompose and break these bonds, no modification of the insulating resin layer occurs.

It is desirable that the modification of the insulating resin layer by irradiation with such short-wavelength ultraviolet rays be performed at an intensity of ^{20 to} 2000 mJ / cm ² for 5 to 600 seconds. If the irradiation amount of the short-wavelength ultraviolet ray is too large, the main chain of the polymer component of the insulating resin layer,
There is a risk that the polymer will be degraded more than necessary because a number of side chain cuts are performed.On the other hand, if the irradiation amount is too small, the above-described roughening treatment solution for the insulating resin layer will not be sufficiently cut off the polymer. This is because the effect of improving the wettability of the catalyst and the adsorptivity of the catalyst cannot be obtained.

Hereinafter, a method for manufacturing a multilayer printed wiring board according to the present invention will be specifically described. (1) First, an insulating resin layer is formed on an insulating substrate on which a first circuit layer has been formed. Here, the insulating substrate used in the present invention is not particularly limited as long as it can be used as a substrate of a printed wiring board, for example, a glass epoxy substrate, a polyimide substrate, a ceramic substrate, a phenol resin substrate,
Metal substrates and the like can be mentioned. The first circuit layer is formed by etching the copper clad laminate to form a copper pattern, or by performing electroless plating via a resist to form a copper pattern.

The insulating resin layer is made of a thermosetting resin, a photosensitive resin, a thermoplastic resin, a photocuring thermosetting resin obtained by appropriately combining these resins, a sea-island structure, an IPN structure (interpenetrating network structure), or the like. It can be formed using a composite resin having the following. Specifically, it is not particularly limited as long as it has heat resistance, insulation properties, and plating solution resistance. For example, epoxy resin, epoxy acrylate, modified epoxy resin, phenol resin, epoxy-PES resin And a complex. The insulating resin layer is, for example, applied on a substrate by a known and common method such as a screen printing method, a spray method, a curtain coating method, or the like, or is dried, or is laminated with an insulating resin film and then cured. Can be formed.

Before the formation of the insulating resin layer, the insulating resin is buried in the concave portion between the first circuit layers, so that the surface of the substrate can be smoothed in advance. Thereby, the thickness of the insulating resin layer becomes uniform, and the reliability in the subsequent steps can be obtained.
After the step (1), a step of physically polishing the surface of the insulating resin layer by buffing or the like may be added to improve the roughening property. In this physical polishing, polishing removal of 3 to 10 μm is preferable from the viewpoint of improving conductor peel strength, and smoothness is more preferably unevenness of 1 to 3 μm.

(2) Next, an opening for forming a via hole for electrically connecting the first circuit layer and the second circuit layer is provided in the insulating resin layer formed in (1). Here, as a method of providing an opening, for example, when a photosensitive resin is used as a material of the insulating resin layer, a photo method is used, and when a thermosetting resin is used, a laser or drilling method is used. .

(3) In particular, in the present invention, the surface of the insulating resin layer in which the opening for forming the via hole is perforated in the above (2) is irradiated with a short-wave ultraviolet ray or before the irradiation with the short-wave ultraviolet ray. Performs a roughening process. Examples of the roughening agent include oxidizing agents such as potassium permanganate, potassium dichromate, ozone, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, N-methyl-2-pyrrolidone, N, N-dimethylformamide, dimethyl Organic solvents such as sulfoxide, methoxypropanol, dimethylformamide (DMF),
An alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be used. For example, when an oxidizing agent is used as a roughening agent, the resin insulating layer is swollen with the above organic solvent, and then subjected to a surface roughening treatment with the oxidizing agent. By this surface roughening treatment, fine-grained rubber components and / or fillers such as calcium carbonate present in the surface layer portion of the insulating resin layer are eluted or decomposed into the roughening agent, and the surface of the cured resin insulating layer or the via hole portion In addition, the roughened surface in the form of irregularities can be easily formed on the inner wall surface of the through hole, and the smear of the through hole generated at the time of drilling is also removed at the same time (desmear treatment).

(4) Next, a second circuit layer and a via hole are formed by plating the insulating resin layer, and the first circuit layer and the second circuit layer are connected to each other through the via hole. . Here, the second circuit layer is a so-called subtractive method in which an unnecessary portion of the thick film conductor formed on the entire surface of the substrate by plating or the like is selectively removed by, for example, etching to form a conductor pattern, or a plating resist. A thick-film conductor is formed by electroless plating through a so-called full-additive method, or a thin-film conductor is formed by electroless plating over the entire surface of an insulating resin layer, and then electroplating is performed through a plating resist. Is formed by a known method such as a so-called semi-additive method for removing the electroless plating film. The type of metal such as copper plating and nickel plating is not particularly limited, and generally known electroless plating or electrolytic plating is used.

(5) If necessary, the above-described series of steps of forming the insulating resin, forming the opening for the via hole, irradiating the short-wavelength ultraviolet ray, roughening the surface of the insulating resin layer, and forming the circuit layer are repeated. Thus, a multilayer printed wiring board having a predetermined number of layers is manufactured.

The multilayer printed wiring board thus manufactured according to the present invention comprises at least an insulating resin layer and a circuit layer alternately laminated, and the insulating resin layer is provided with an opening, and the opening is provided in the opening. The upper and lower circuit layers are electrically connected to each other through via holes formed.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but it is needless to say that the present invention is not limited to the following examples. In the following, “parts” are based on weight unless otherwise specified.

Example 1 (1) First, a first circuit layer was formed on a glass epoxy copper clad laminate by a subtractive method. Next, a liquid insulating resin layer forming material is applied on the first circuit layer with a curtain coater, and dried at 110 ° C. for 20 minutes.
The composition was cured at 0 ° C. for 30 minutes to form an insulating resin layer having a thickness of 60 μm. The component composition of the insulating resin layer forming material is as follows.

(Component composition of insulating resin layer forming material) Epoxy resin (Eicoat 1001 manufactured by Yuka Shell Co., Ltd.): 100 parts Epoxy resin (Epicoat 828 manufactured by Yuka Shell Co., Ltd.): 50 parts Rubber-modified epoxy resin (Toto Kasei Co., Ltd., YR-450): 50 parts ・ Imidazole epoxy curing agent (Shikoku Chemicals Co., Ltd., Curesol 2MZ-A): 5 parts ・ Phenol resin (Meiwa Kasei Co., Ltd.) HF-1): 20 parts ・ Light calcium carbonate (average particle size: 3 μm or less): 35 parts ・ Fine powdered silica (average particle size: 1.5 μm or less): 15 parts

(2) Next, an opening for forming a via hole was formed in the insulating resin layer formed in the above (1) using a carbon dioxide gas laser. The processing conditions at this time are: pulse width 15
/ 12/5 μS Shot number 1/1/1 (laser processing machine LCO-1B21 manufactured by Hitachi Via Mechanics Co., Ltd.).

(3) Next, a low-pressure mercury lamp is used as the short-wavelength ultraviolet light on the surface of the insulating resin layer, and the intensity is 200 mW / cm ² .
Irradiated for 0 seconds.

(4) Next, the substrate after the step (3) is replaced with a swelling solution composed of an alkali and a solvent (Swelling Dip Securigant P, manufactured by Atotech Co., Ltd.).
At 75 ° C. for 10 minutes and washed with water, and then immersed in a roughening agent composed of potassium permanganate (concentrate compact CP, manufactured by Atotech Co., Ltd.) at 75 ° C. for 20 minutes, washed with water, and further reduced. Liquid (Atotech Co., Ltd.)
The solution was immersed in Reduction Solution Securiganto P) at 40 ° C. for 5 minutes, neutralized, and washed with water to roughen the surface of the insulating resin layer.

(5) Next, the substrate having a roughened insulating resin surface was treated with an electroless plating solution (manufactured by Atotech Co., Ltd.) for 3 hours.
Immerse at 5 ° C for 10 minutes, apply electroless plating, wash with water,
Annealing was performed at 100 ° C. for 30 minutes. The film thickness of the obtained electroless copper plating was 0.3 μm.

(6) Next, an electrolytic copper plating layer having a thickness of 18 μm was formed by electrolytic plating using an 80 g / l copper sulfate solution, and after-baked at 150 ° C. for 60 minutes.

(7) Next, an etching resist is formed on the copper plating layer so that a predetermined circuit can be formed, unnecessary conductors are removed by etching by a known method, and the resist is removed. Thus, a multilayer printed wiring board was manufactured.

Example 2 (1) First, a first circuit layer was formed on a glass epoxy copper clad laminate by a subtractive method. Next, a liquid insulating resin layer forming material is applied on the first circuit layer with a curtain coater, and dried at 110 ° C. for 20 minutes.
The composition was cured at 0 ° C. for 30 minutes to form an insulating resin layer having a thickness of 65 μm. The composition of the material for forming the insulating resin layer is the same as in Example 1.

(2) Next, in order to facilitate roughening, the surface of the insulating resin layer formed in (1) is buffed (# 600,
In step # 1000), the insulating resin layer was polished and removed by about 5 μm, and the thickness of the insulating resin layer was set to 60 μm.

(3) Next, an opening for forming a via hole was formed in the same manner as in Example 1. (4) Next, the substrate after the step (3) is immersed in a swelling solution (Swelling Dip Securigant P, manufactured by Atotech Co., Ltd.) composed of an alkali and a solvent at 75 ° C. for 5 minutes and washed with water, Then, it is immersed in a roughening agent composed of potassium permanganate (Concentrate Compact CP, manufactured by Atotech Co., Ltd.) for 10 minutes at 70 ° C., washed with water, and further reduced with a reducing solution (Reduction Solution Securigant, manufactured by Atotech Co., Ltd.). The surface of the insulating resin layer was roughened by immersing in P) at 40 ° C. for 5 minutes to neutralize and wash with water.

(5) Next, a low-pressure mercury lamp was used as the short-wavelength ultraviolet light on the surface of the insulating resin layer at a strength of 200 mJ / cm ² .
Irradiated for 0 seconds.

(6) Thereafter, electroless copper plating and electrolytic copper plating were performed in the same manner as in Example 1 to form a second circuit layer, and a multilayer printed wiring board was manufactured.

Comparative Example 1 A multilayer printed wiring board was manufactured in the same manner as in Example 1 except that the surface of the insulating resin layer was not irradiated with short-wavelength ultraviolet rays.

Comparative Example 2 A multilayer printed wiring board was manufactured in the same manner as in Example 2 except that the surface of the insulating resin layer was not irradiated with short-wavelength ultraviolet rays.

Comparative Example 3 A multilayer printed wiring board was manufactured in the same manner as in Example 1 except that the surface of the insulating resin layer was irradiated with long-wavelength ultraviolet rays (high-pressure mercury lamp) at an intensity of 200 mJ / cm ² for 10 seconds. .

The multilayer printed wiring boards manufactured in Examples and Comparative Examples as described above were subjected to JIS C6481.
Strength (Max value, Min value, A
ve value) and the results are shown in Table 1.

As is clear from the results shown in Table 1, the multilayer printed wiring boards in Examples 1 and 2 have almost no difference between the Max value and the Min value of the conductor peel strength, and exhibit stable conductor peel strength. I understand. In contrast, the multilayer printed wiring boards in Comparative Examples 1 and 2
It can be seen that the fluctuation of the conductor peel strength due to the roughening unevenness is large. In the examples according to the present invention, it was confirmed that the electrical connection reliability between the conductors via the via holes could be maintained high.

[0040]

[Table 1] * Number of samples: 10

[0041]

As described above, according to the method for manufacturing a multilayer printed wiring board according to the present invention, the irradiation of short-wavelength ultraviolet light reduces the peel strength of the conductor due to unevenness particularly during mass production. Can be reliably prevented, and a multilayer printed wiring board that ensures stable conductor peel strength can be provided. Further, according to the present invention, the reliability of electrical connection between conductors via via holes formed by a laser process can be kept high.

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Claims (3)

[Claims] (A) forming an insulating resin layer on an insulating substrate on which a first circuit layer is formed; (b) providing a via hole opening in the insulating resin layer formed in (a); (c) the above (b)
In the step of irradiating the surface of the insulating resin layer provided with openings for via holes with short-wavelength ultraviolet light, (d) a step of roughening the surface of the insulating resin layer with a roughening agent, (e) the insulating resin layer A step of forming a second circuit layer and a via hole by plating, and making an interlayer connection between the first circuit layer and the second circuit layer in the via hole. Manufacturing method. (A) forming an insulating resin layer on the insulating substrate on which the first circuit layer is formed; (b) providing a via hole opening in the insulating resin layer formed in (a); (c) the above (b)
In the step of roughening the surface of the insulating resin layer provided with openings for via holes with a roughening agent, (d) irradiating the roughened surface of the insulating resin layer surface with short-wavelength ultraviolet light, (e) Forming a second circuit layer and a via hole by plating the insulating resin layer, and performing interlayer connection between the first circuit layer and the second circuit layer in the via hole. A method for manufacturing a multilayer printed wiring board. 3. The method according to claim 1, wherein a low-pressure mercury lamp is used as the short-wavelength ultraviolet light.