JPH08279682A - Manufacture of multilayered circuit board - Google Patents

Abstract

PURPOSE: To obtain a high density multilayered printed circuit board at a low cost, by repeating a process wherein an insulating layer, an interstitial viahole, a through hole, etc., are formed on a double-sided board in which a first conductor circuit is formed, and then a second conductor circuit is formed by etching or the technique of pattern copper-plating. CONSTITUTION: A viahole 3 is formed in an insulating substratum 1 and conductor layers on both surfaces are connected. A first conductor circuit 2 is formed. After roughing by a method like blackening, alkali developing type liquid state insulating resin is spread, and an interlayer insulating layer 4 is formed. An art work film or the like for forming an interstitial viahole (IVH) is aligned to the insulating resin and exposed to light, thereby forming an IVH 5. Necessary and minimum viaholes 6 are drill-worked. The surface is roughened, and a conductor layer 7 is formed by electroless plating, panel electrolytic copper plating, etc., whose layer is connected with the first conductor circuit 2. When the number of layers is increased, the process from the formation of the insulating layer to the formation of the conductor circuit is repeated.

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 multi-layer circuit board having interstitial via holes (hereinafter referred to as IVH), and more specifically, it imparts photosensitivity to an insulating layer which can be developed with an alkaline aqueous solution. A manufacturing technique for applying a special roughening treatment to the resin surface in order to improve the adhesion reliability between a multilayer circuit board that forms an IVH by exposure and development using an insulating resin and a conductor circuit of the multilayer circuit board and an insulating layer. Regarding

[0002]

2. Description of the Related Art Conventionally, a via hole for connecting layers in a multilayer printed circuit board is generally formed by forming a through hole by drilling or the like, but in order to cope with high density, a surface layer circuit and an inner layer circuit are formed. Multilayer circuit boards with IVHs that only connect only are becoming popular. However, the conventional method for forming IVH is a method of drilling each layer, conducting each by plating, and adhering via a prepreg of a thermosetting resin, which makes the process complicated and Since it is formed by drilling, there is a limit in reducing the diameter of the IVH, and there are drawbacks that the cost is significantly increased.

On the other hand, a build-up method, which is a method of forming IVH by a photoetching process such as exposure and development, has been known as a conventionally known method.

According to this method, first, a first conductor circuit having a desired pattern is formed on the surface of an insulating base material, and then a liquid insulating resin is applied thereon, or a dry film type insulating resin is laminated or the like. After forming an interlayer insulating layer by bonding, IVH is formed through an exposure process, a development process, and the like. Further, if necessary, the minimum necessary through via hole is formed here by drilling. After roughening the surface of the insulating layer,
The second conductor layer is formed and the first conductor circuit and the second conductor layer are connected by panel copper plating or the like, and a desired second conductor circuit is further formed by etching or the like.
By repeating this operation sequentially, a multilayer circuit board having a desired number of layers is formed.

[0005]

The build-up method described above is capable of forming via holes having a small diameter in the shape of IVH, and is an effective means as a method for manufacturing a high-density multilayer printed circuit board.

However, when this method is applied to a multi-layer printed circuit board, when an alkali-developing insulating resin is used for the interlayer insulating layer, the adhesion reliability between the conductor circuit and the insulating layer is poor, and it is unavoidable that a solvent such as an epoxy type solvent is used. At present, a developing type insulating resin is used. For this reason,
It is not possible to use the existing equipment for alkaline development, which is already becoming the mainstream, and the processing conditions for forming IVH are, for example, an epoxy resin is a large amount of light of about 3 J or more when exposed to light when exposed. It requires energy, has a narrow range of condition management from coating to complete curing, and has the disadvantage of high running cost because it is developed with an organic solvent. Furthermore, it is hard to say that the adhesion strength between the conductor circuit and the insulating resin is 0.6 to 1.0 kg / cm, which is sufficient reliability.

Also, from the environmental point of view, the conventional build-up method using a solvent-developable resin uses a chlorine-based organic solvent, so that the health of workers is impaired and the global warming phenomenon is prevented. Was expected to be adversely affected, and there was concern about the future.

The present invention solves the above-mentioned problems in manufacturing a multilayer printed circuit board by the build-up method, utilizes the advantages of the build-up method, and inexpensively manufactures a high-density multilayer printed circuit board having IVH with a small diameter. You can
Moreover, it aims to provide a manufacturing technology that is safe and has no adverse effect on the environment.

[0009]

As a result of earnest studies, the inventors of the present invention have achieved the above object by using an alkali developing type insulating resin as the interlayer insulating resin in the above-mentioned build-up method.

That is, according to the present invention, an insulating layer is formed on a double-sided substrate on which a first conductor circuit is formed, an interstitial via hole is formed by exposure and development, and then drilling is carried out if necessary. A through hole is formed, the surface of the interlayer insulating layer is roughened, and panel copper plating is performed to ensure continuity, and then a desired second conductor circuit is etched using an etching method or a pattern copper plating and etching method. The present invention relates to a method for manufacturing a multi-layer circuit board, which comprises repeating the steps of forming.

The method of the present invention will be described in detail below with reference to FIG. 1 by taking a four-layer circuit board as an example.

First, the insulating base material (1) is processed into via holes (3) by a drill, etc., and the conductor layers on both sides are connected by known copper plating or the like, and then the first conductor circuit (2) is etched or the like. To form a double-sided circuit board. At this time, the via hole (3) may be omitted in some cases.

Next, after the conductor circuit is roughened by a method such as blackening treatment, an alkali developing type liquid insulating resin is used by a method such as a curtain coating method, a screen printing method, a spray method or a dip coating method. The interlayer insulating layer (4) is formed by applying and temporarily drying, or laminating a film type insulating resin by laminating or hot pressing. Arrange an IVH forming artwork film, etc. on this insulating resin as desired.
After the exposure, the solution is heated to about 25 to 30 ° C. and alkali-developed with about 1 to 2% sodium carbonate aqueous solution to obtain IVH
(5) is formed.

At this time, as the alkali developing type insulating resin, epoxy-acrylate type or heat resistant acrylic type can be used, and the thickness of the interlayer insulating layer (4) influences the influence of the first conductor circuit (2). In order to prevent the resin surface from becoming uneven when receiving it, and to secure better insulation reliability,
It is preferably about 40 to 100 μm.

Since the resin used for the interlayer insulating layer (4) needs to be completely cured, it is cured by heating in a hot air circulation drying oven at about 120 to 150 ° C. for about 20 to 60 minutes, or by far infrared rays. It is cured by heating in a drying oven at about 150 to 180 ° C. for about 3 to 8 minutes, or by UV irradiation of 1 to 3 J in a UV drying oven.

Next, the minimum required via hole
Process (6) with a drill.

Further, in order to make the surface of the insulating layer smooth and improve the adhesion of the second conductor circuit (8), the surface of the insulating resin may be subjected to mechanical polishing such as puff polishing or jet scrub polishing. is there.

Here, in order to improve the adhesion of the second conductor circuit (8), it is necessary to chemically polish the surface of the resin used for the interlayer insulating layer (4). In general, the method of chemically polishing the insulating resin such as epoxy with potassium permanganate was used for the above insulating resin, but in the case of the alkali development type epoxy-acrylate resin, the adhesion reliability is secured only by the permanganate treatment. Therefore, the roughening condition required is not achieved. Therefore, the chemical reliability is improved by the following method to improve the adhesion reliability with the conductor circuit. That is, the resin surface of the interlayer insulation layer (4) is immersed in a strong alkaline aqueous solution composition consisting of a mixed aqueous solution containing three components of an inorganic alkali, a water-soluble amine and an organic solvent to carry out the first roughening treatment. Further, after this treatment, the epoxy-based component of the interlayer insulating layer (4) is chemically polished with potassium permanganate or the like, whereby the roughened state necessary for ensuring the adhesion reliability can be finished.

Here, examples of the inorganic alkali used for the first-stage roughening treatment include sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, etc. These may be used alone or in combination of two or more. However, it can be used. Water-soluble amines are amino alcohols represented by the following formula,

[0020]

Embedded image

(In the formula, R represents hydrogen, a methyl group, a hydroxylmethyl group or a hydroxypropyl group, which may be the same or different groups, R'represents an ethylene group, and n represents 0 to 3). Is the number of.).

Examples of the water-soluble amine used here include monoethanolamine, diethanolamine, diisopropanolamine, methylethanolamine, ethylenediamine, triethylenetetramine, ethylene oxide or propylene oxide 1 to 4 mol adduct of ethylenediamine, and the like. , These are 2 alone
More than one species can be used. Examples of the organic solvent include dioxane, methyl ethyl ketone, acrylonitrile, dimethyl succinate, dimethyl glutarate, ester solvents such as dimethyl adipate, or methyl diglycol, methyl triglycol, methyl propylene glycol, methyl propylene diglycol, propyl diglycol, Examples thereof include water-soluble organic solvents such as glycol ethers such as propyl propylene glycol and butyl diglycol, and these may be used alone or in combination of two or more.

The mixing ratio of the above three components in 100 parts by weight of the strong alkaline aqueous solution composition is preferably 15 to 35 parts by weight of inorganic alkali, 10 to 30 parts by weight of water-soluble amine, and 10 to 30 parts by weight of organic solvent.

Further, it is also useful to add various kinds of surfactants serving as penetrants and chelating agents serving as precipitation preventing agents such as calcium salts.

After the surface of the insulating resin is roughened, a desired thickness is obtained by thin electroless plating and panel electrolytic copper plating.
For example, the second conductor layer (7) is formed and the first conductor circuit (2) and the second conductor layer (7) are connected to each other at about 10 to 50 μm.

Next, in order to further secure the adhesion reliability between the conductor layer (7) and the interlayer insulating layer (4), a hot air circulation drying furnace is used for about 120
Heat treatment at ~ 150 ° C for about 10-60 minutes.

Further, by removing unnecessary copper by a known etching method, a desired second conductor circuit (8) can be formed, and a high-density multilayer printed circuit board having IVH with a small diameter can be obtained.

For formation of the second conductor circuit (8), the surface of the interlayer insulating layer (4) is roughened, and the thickness of the electrolytic copper plating on the panel after thin electroless plating is set to about 1 to 5 μm. Or about 1 to 5 with thick electroless copper plating only
After forming a copper circuit of a desired thickness, for example, about 5 to 50 μm by patterned copper electroplating to a thickness of μm, and subsequently pattern electroplating different metals such as solder, nickel and chromium, and then etching this different metals. It is also possible to remove unnecessary copper as a resist by etching, and by omitting pattern electrolytic plating of these dissimilar metals and performing quick etching of unnecessary copper, a second conductor circuit can be obtained.
It is also possible to form (8).

When the number of layers is further increased, the steps of forming the interlayer insulating layer to forming the conductor circuit are sequentially repeated after the second conductor circuit (8) is roughened by a method such as blackening treatment. By doing so, a desired multilayer circuit board can be obtained.

[0030]

According to the method of the present invention, since the via hole is formed by photoetching, it is possible to inexpensively provide the IVH having a small diameter, which was difficult by the drilling process. Further, since a photoresist material that can be developed with an epoxy-acrylate-based or heat-resistant acrylic-based alkaline aqueous solution is used for the interlayer insulating resin, it is cheaper than a conventional solvent-developing insulating resin such as an epoxy-based resin. It is possible to provide a multilayer circuit board which is a safe manufacturing method which does not have an adverse effect on the environment and at the same time has a highly reliable adhesion strength of a conductor circuit of 1.0 kg / cm or more.

[0031]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) First, a conductor circuit (1) was formed on a double-sided copper-clad laminate having a copper foil thickness of 35 μm by a known panel plating method, a double-sided circuit board was prepared, and a conductor was blackened. circuit
The surface of (1) was roughened. Next, an epoxy-acrylate type alkali-development type liquid photoresist is applied to a thickness of 80 μm by the curtain coating method, and then it is dried in a hot air circulating drying oven.
A step of temporary drying at 75 ° C. for 20 minutes was performed on both sides. An artwork film for IVH formation is arbitrarily aligned with this photoresist, exposed to 400 mJ with an ultra-high pressure mercury lamp and left for 10 minutes, then developed at a liquid temperature of 30 ° C. and a 1 wt% sodium hydrogencarbonate aqueous solution to produce IVH. Was formed. After heating at 150 ° C for 30 minutes in a hot air circulation drying oven to harden the photoresist and form the interlayer insulating layer (4), potassium hydroxide is added.
25 parts by weight, diethanolamine 20 parts by weight, methylpropylene diglycol 20 parts by weight, ethylenediaminetetraacetic acid tetrasodium salt 1 part by weight, water 34 parts by weight to roughen the surface, wash thoroughly with water, and then wash with permanganese. So-called chemical polishing, which is a sodium acid treatment, was performed. Next, 0.3 μm thick copper is electroless copper plated on the interlayer insulating layer (4), and further 25 μm thick copper is deposited by panel electrolytic copper plating. Minute baking was performed to form a conductor layer (7). After the entire surface of the second conductor layer (7) is conditioned by puffing and scrubbing, and the pattern of the second conductor circuit is imaged using a dry film,
A second conductor circuit (8) was formed by etching away unnecessary copper with a ferric chloride solution, and a four-layer circuit board having IVH was obtained. The results of measuring the performance characteristics of this circuit board are shown in Table 1. Adhesion strength is 1.2 to 1.3 kg
The result was good as / cm.

(Example 2) 25 parts by weight of potassium hydroxide, 25 parts by weight of diethanolamine, 15 parts by weight of a mixture of dimethyl succinate, dimethyl glutarate and dimethyl adipate, and 4 parts by weight of ethylenediaminetetraacetic acid were used. A substrate was prepared in the same manner as in Example 1 except that a mixed solution of 1 part by weight of sodium salt and 34 parts by weight of water and a sodium permanganate solution were used, and the performance characteristics of the circuit board were measured.
The results such as the adhesion strength of the conductor circuit are the same as those in Table 1, and the adhesion strength was a good result of 1.2 to 1.3 kg / cm.

Example 3 25 parts by weight of potassium hydroxide, 15 parts by weight of monoethanolamine, 25 parts by weight of methyldiglycol, 1 part by weight of ethylenediaminetetraacetic acid tetrasodium salt, and 34 parts of water were used. Substituting parts by weight of the mixed solution and the sodium permanganate solution, a board was prepared in the same manner as in Example 1, and the performance characteristics of the circuit board were measured. The results of the adhesion strength of the conductor circuit are the same as in Table 1,
The adhesion strength was 1.2 to 1.3 kg / cm, which was a good result.

(Comparative Example 1) The same measurement was conducted using the chemical polishing treatment liquid of the above-mentioned embodiment as a mixed liquid of 25 parts by weight of potassium hydroxide, 1 part by weight of tetrasodium ethylenediaminetetraacetic acid salt and 74 parts by weight of water, and sodium permanganate. However, the adhesion strength of the conductor circuit was 0.2 kg / cm or less, and no good result was obtained.

[0036]

[Table 1]

[Brief description of drawings]

FIG. 1 is a diagram showing steps of a build-up method in a manufacturing method of the present invention.

[Explanation of symbols]

 1 Insulating Base Material 2, 8 Conductor Circuit 3, 6 Via Hole 4 Interlayer Insulating Layer 5 Interstitial Via Hole 7 Conductor Layer

[Procedure amendment]

[Submission date] May 10, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010] Namely, the present invention, the first double-sided substrate having conductor circuits are formed by forming an insulating layer, exposure and development I
After VH is formed, if necessary, a through hole is formed by drilling, the surface of the interlayer insulating layer is roughened, and panel copper plating is performed to ensure continuity, and then a desired second conductor circuit is formed. The present invention relates to a method for manufacturing a multi-layer circuit board, which is characterized by repeating the steps of forming using an etching method or a pattern copper plating and etching method.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Furthermore interlayer insulating layer (4) The surface was smooth, and bar off polishing the surface of the insulating resin in order to improve the adhesion of the second conductor circuit (8), the mechanical polishing, such as jet scrubbing polishing It is also possible to apply.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

(Example 1) First, a conductor circuit (1) was formed on a double-sided copper-clad laminate having a copper foil thickness of 35 μm by a known panel plating method, a double-sided circuit board was prepared, and a conductor was blackened. circuit
The surface of (1) was roughened. Next, an epoxy-acrylate type alkali-development type liquid photoresist is applied to a thickness of 80 μm by the curtain coating method, and then it is dried in a hot air circulating drying oven.
A step of temporary drying at 75 ° C. for 20 minutes was performed on both sides. An artwork film for IVH formation is arbitrarily aligned with this photoresist, exposed to 400 mJ with an ultra-high pressure mercury lamp and left for 10 minutes, then developed at a liquid temperature of 30 ° C. and a 1 wt% sodium hydrogencarbonate aqueous solution to produce IVH. Was formed. After heating at 150 ° C for 30 minutes in a hot air circulation drying oven to harden the photoresist and form the interlayer insulating layer (4), potassium hydroxide is added.
25 parts by weight, diethanolamine 20 parts by weight, methylpropylene diglycol 20 parts by weight, ethylenediaminetetraacetic acid tetrasodium salt 1 part by weight, water 34 parts by weight to roughen the surface, wash thoroughly with water, and then wash with permanganese. So-called chemical polishing, which is a sodium acid treatment, was performed. Next, 0.3 μm thick copper is electroless copper plated on the interlayer insulating layer (4), and further 25 μm thick copper is deposited by panel electrolytic copper plating. Minute baking was performed to form a conductor layer (7). After the entire surface of the second conductive layer (7) facing integer in bus off and scrub polishing and imaging the pattern of the second conductive circuit by using a dry film,
A second conductor circuit (8) was formed by etching away unnecessary copper with a ferric chloride solution, and a four-layer circuit board having IVH was obtained. The results of measuring the performance characteristics of this circuit board are shown in Table 1. Adhesion strength is 1.2 to 1.3 kg
The result was good as / cm.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG.

Front page continuation (72) Inventor Hiroshi Ishio 7-35 Higashiohisa, Arakawa-ku, Tokyo Asahi Denka Kogyo Co., Ltd. (72) Inventor Tatsuo Wada 5-14-15 Oue, Ayase City, Kanagawa Stock Company In Meiko (72) Inventor Atsushi Yoshino 5-14-15 Oue, Ayase City, Kanagawa Stock Company Meiko (72) Inventor Katsuro Aoshima 5-14-15 Oue, Ayase City, Kanagawa In Meiko Co., Ltd. (72 ) Inventor Keiichi Murakami 5-14-15 Oue, Ayase City, Kanagawa Prefecture Meiko Co., Ltd.

Claims (5)

[Claims] 1. An insulating layer is formed on a double-sided substrate on which a first conductor circuit is formed, an interstitial via hole is formed by exposure and development, and then a through hole is drilled if necessary. A step of forming, roughening the surface of the interlayer insulating layer, and ensuring continuity by performing panel copper plating, and then forming a desired second conductor circuit using an etching method or a pattern copper plating and etching method. A method of manufacturing a multi-layer circuit board, characterized by repeating. 2. The method for producing a multilayer circuit board according to claim 1, wherein an epoxy-acrylate-based or heat-resistant acrylate-based insulating resin is used as the insulating resin that can be developed in the interlayer insulating layer with an alkaline aqueous solution. . 3. A method of roughening the surface of an interlayer insulating resin with a strong alkaline aqueous solution composition and a sodium permanganate aqueous solution for improving the adhesion between the interlayer insulating layer and the conductor circuit. 2. The method for manufacturing a multilayer circuit board according to item 2. 4. The method for producing a multilayer circuit board according to claim 3, wherein the strong alkaline aqueous solution composition is a mixed aqueous solution containing three components of an inorganic alkali, a water-soluble amine and an organic solvent. 5. The heat treatment is applied to the surface of the interlayer insulating resin after panel copper plating in order to improve the adhesion between the interlayer insulating layer and the conductor circuit. A method for manufacturing the multilayer circuit board according to.