JPH0298995A - Manufacture of multilayer wiring board - Google Patents

Abstract

PURPOSE:To make a cross section of a blind through-hole in a tapered shape whose upper part is enlarged and to improve operativity by using photosensitive resin of negative photosensitive resin containing light scattering filler. CONSTITUTION:When manufacturing a multilayer wiring board whereon a conductor circuit is further formed on an inner surface of a hole made as a blind through-hole and on a surface of an interlayer insulating layer, negative photosensitive resin containing light scattering filler is used as negative photosensitive resin. According to this constitution, an exposure section of photosensitive resin is enlarged downward and a hole whose diameter is enlarged upward can be shaped as a blind through-hole. Connection reliability between conductor circuits can be thereby ensured relatively readily and securely, thereby improving operativity.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for manufacturing a multilayer wiring board, and particularly to a method for manufacturing a multilayer wiring board using the so-called build-up method, in which 4n layers of conductive circuits and organic insulating layers are alternately formed. This relates to a manufacturing method.

(Prior Art) In recent years, with the progress of electronic technology, electronic devices such as large-sized computers have been made to have higher density and faster calculation functions. As a result, multilayer wiring boards in which wiring circuits are formed in multiple layers are also used in printed wiring boards for the purpose of increasing density.

Conventionally, multilayer wiring boards include, for example, a multilayer wiring board in which multiple circuit boards on which inner layer circuits are formed are laminated using prepreg as an insulating layer, heat pressed to integrate them, and then the eyebrows are connected through through holes for continuity. was used.

However, as the number of layers increases and the density of the multilayer wiring board as described above increases, the number of through holes for connecting between the eyebrows increases, and the area for passing conductor circuits becomes narrower, resulting in the formation of complex circuits. Moreover, it was difficult to increase the density.

A multilayer wiring board that can overcome these difficulties is the build amplifier method multilayer wiring, in which conductor circuits and organic insulating layers are alternately laminated, and only where interlayer connections are necessary are connected using blind through holes. Development of the board is actively underway. This kind of build amplifier method multilayer wiring board eliminates unnecessary through hole space, and the area for passing conductor circuits is not narrowed, making it possible to form complex circuits and increase density. .

The organic material used in this build amplifier method multilayer wiring board
Considering the diameter of the blind through hole to be formed, it is desirable to use photosensitive resin as the edge i.

However, when a photosensitive resin is used as an organic insulating material and a blind through hole is formed by photolithography, the side wall of the blind through hole becomes almost vertical, so this is completely impossible! When a thermal shock is applied to the multilayer VAFy, which has a conductor circuit formed on the top of the layer, disconnections tend to occur frequently at the shoulders of the blind through holes, resulting in the problem that the connection reliability of the blind through holes cannot be guaranteed. there were.

In order to solve this problem, a method has conventionally been disclosed in which the shape of the blind through hole is made into a tapered shape that widens upward to ensure the reliability of the blind through and toll connections.

For example, Japanese Unexamined Patent Publication No. 18989/1989 discloses a method in which a means for reducing the contrast ratio around the blind through hole is introduced between a photomask and a photosensitive resin to make the cross section of the blind through hole tapered. There is. However, with this method, the photomask, photosensitive resin,
Unless the positional relationship of the main means of reducing the contrast ratio around the blind through hole is strictly controlled, it is not possible to make the cross section of the blind through hole tapered with good reproducibility, which has the disadvantage of poor workability. ing.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems of the prior art, and makes the cross-section of the blind through hole easily tapered to the top, thereby improving workability of pill doors and blocks. An object of the present invention is to provide a method for manufacturing a multilayer wiring board.

(Means and effects for solving the problem) In order to achieve the above object, the present inventors have conducted extensive research on the manufacturing process of multilayer wiring boards, and have found that a light-scattering filler is incorporated into the photosensitive interlayer insulating material. By scattering actinic rays by scattering actinic rays through the blind-through ball, we came up with the idea that it is possible to form a blind-through ball into a shape whose diameter tapers upward, thereby making it relatively easy to improve the connection reliability between conductor circuits. Moreover, we have completed a method for manufacturing multilayer wiring boards that can be reliably produced.

That is, in the present invention, a negative photosensitive resin is applied onto a substrate on which a conductor circuit is formed, and then actinic rays are irradiated from above onto the photosensitive resin at locations other than the locations where blind through holes are to be formed. A method for producing a multilayer wiring board, which comprises forming a hole between the eyebrows 1@I [ having a hole to become a blind through hole, and then further forming a conductor circuit on the inner surface of the hole to become a blind through hole and on the surface of an interlayer insulating layer. By using a negative photosensitive resin containing a light-scattering filler as the negative photosensitive resin, the exposed area of the photosensitive resin is expanded downward and the diameter is increased upward. It is possible to form a hole that should become a blind through hole with an enlarged shape, and as a result, an extremely reliable multilayer wiring board can be created. It is possible to build A.

The present invention will be described in detail below in accordance with a method for manufacturing a multilayer wiring board.

First, a negative photosensitive resin containing a light-scattering filler is applied onto a substrate on which a conductive circuit is to be formed.

In the present invention, the negative photosensitive resin forming the interlayer insulating film is at least selected from acrylic resin, photosensitive phenol resin, photosensitive epoxy resin, epoxy-modified polyimide resin imparted with photosensitivity, and photosensitive polyimide resin. It is advantageous to use one species.

Further, as the light-scattering filler used in the present invention, both organic fine particles and inorganic fine particles can be used.

As the organic particles, it is advantageous to use at least one selected from epoxy resins, phenol resins, benzoguanamine resins, and polyimide resins, and preferably resin particles that have been previously hardened.

The reason for using organic particles that have been pre-cured is that if they are not cured, the photosensitive resin
Alternatively, this is because when the resin is added to a solution in which the resin is dissolved using a solvent, it is dissolved in the resin solution. Inorganic fine particles include silica, talc, alumina, titanium oxide,
It is advantageous to use at least one selected from zirconia. Furthermore, it is also possible to use a combination of these organic fine particles and inorganic FF fine particles. In the case of both organic particles and inorganic particles, it is desirable that they have a certain degree of difference in optical refractive index from the photosensitive resin.If the difference in optical refractive index is large, a large effect can be obtained by adding a small amount. However, if the difference in optical refractive index is too large, it is very difficult to control the shape of the blind through hole and it is not practical. Therefore, the difference in optical refractive index between the photosensitive resin and the fine particles is 0.1 to 0.7. It is desirable that the

The amount of the light-scattering filler is closely related to the optical refractive index of the photosensitive resin and the added fine particles and the taper angle of the blind through hole shape, so it cannot be specified in part, but it is generally 20 to 50%. It is advantageous to do so.

The particle size of the light-scattering filler is preferably 0.1 μm to 10 μm. This is because if the particle size is larger than 108 m, the degree of light scattering becomes uneven and it is difficult to accurately control the shape of the blind through hole. This is because you will not be able to do it.

More preferably, the particle size of the light scattering filler is 0°5 μm.
~5 μm.

Further, at least a portion of the light-scattering filler used in the present invention may be soluble in a specific chemical solution, such as chromic acid. By treating the insulating layer cured using such a filler with a specific chemical solution, the surface of the insulating layer becomes a tag, and it becomes possible to firmly adhere the conductive circuit formed on the upper edge surface. Examples of the light-scattering filler soluble in the specific chemical solution include organic particles such as epoxy resin, polyester resin, and bismaleide-triazine resin, and inorganic particles such as silica, zinc oxide, and calcium carbonate. In addition, the specific chemicals include oxidizing chemicals such as chromic acid, chromate, permanganic acid, and ozone; acids such as hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride;
Alternatively, an alkaline solution may be used.

As a coating method, various methods can be used, such as a roller coating method, dip coating method, spinner coating method, curtain coating method, and screen printing method.

methyl ethyl ketone to dissolve the photosensitive resin;
Solvents such as cellosolve, cellosolve acetate, dimethylformamide, and pyrrolidone can be used. Further, a coupling agent for increasing the adhesion between the photosensitive resin and the filler, an antifoaming agent for improving coating performance, a leveling agent, and other necessary additives can be added.

Further, there is no problem even if a thermosetting resin is added as necessary.

Next, the solvent contained in the photosensitive resin is evaporated to form a photosensitive resin film. A photomask for forming a blind through hole is placed on top of this, and the photosensitive resin is exposed to light. Then, through development and curing treatment, a blind through hole with a diameter tapered upward is formed between the eyebrows. Form an insulating layer.

The conductor circuit can be formed on the cured insulating layer by a PVD method or an additive method by roughening the cured insulating layer.

Roughening the cured insulating layer using an additive method is a very advantageous method in terms of productivity and cost.

Further, by repeating the above steps, a build amplifier method multilayer wiring board in which conductor circuits and insulating layers are alternately laminated is obtained.

(Example) Examples and comparative examples will be described below, but the present invention is not limited thereto. In addition, the symbol "parts" in the C1"L position indicating the combination in the examples means parts by weight.

Example 1 1) Photosensitive polyimide resin (Hitachi Chemical Co., Ltd., trade name:
T-14) ao part, benzoguanamine resin fine particles (
Manufactured by Nippon Shokubai Kagaku, product name: Eposter M, average particle size 2μ
m) After mixing 20 parts, the viscosity was adjusted to 11:1 to 300 CPS using a homodisper stirrer, and then kneaded using three rolls to prepare a photosensitive resin solution.

2) Next, the photosensitive resin solution was applied using a spin coater onto the printed wiring board obtained by photoetching the surface of the copper-clad laminate using a conventional method, and after being left in a horizontal position for 20 minutes, so Let it dry to the touch and FJ approximately 50μ
A photosensitive resin layer of m was formed.

3) Next, a photomask film on which a black circle of 100 μmΦ was formed was closely attached to this, and exposure was performed at 450 m j / c + rl using a short arc lamp. This is N-
By developing with methylpyrrolidone solution, lO
A blind through hole of 0 μmΦ was formed in the film, which was then exposed to 3 J/crd using an ultra-high pressure mercury lamp and further heat-treated at 200°C for 1 hour, resulting in interlayer insulation with excellent dimensional accuracy equivalent to a photomask film. A film was obtained.

When I looked at the cross section of the blind through hole part, I found that
The blind through hole had a diameter tapered upward, with a diameter of 100 μm at the top and a diameter of 90 μm at the bottom.

The optical refractive index of the photosensitive polyimide resin of this example was about 1.4, and the optical refractive index of the benzoguanamine resin particles was about 1.5.

4) Copper was deposited to a thickness of 20 μm by vapor deposition on the interlayer insulating film in which the blind through holes were formed, and then an etching mask was formed according to a conventional method, and copper other than the circuit was etched away to form a wiring circuit. Example 2 1 ) 80 parts of 50% acrylic compound of Talesol novolac type epoxy resin (manufactured by Kuchimoto Kasaku, trade name: EOCN-104S), bisphenol A type epoxy resin (manufactured by Yuka Shell, trade name: Ebicoat 3001) 211! ,
Penzyl alkylkecool (manufactured by Ciba Geigy, trade name: Coil Gacure 651) 6 parts, imidazole (manufactured by Shikoku Kasei, trade name: 2 parts 4MH2) 6 parts, epoxy resin fine particles (manufactured by Toshi, trade name: Trevar, Average particle size 1.
After mixing 15 parts of silica fine particles (manufactured by Ryumori Co., Ltd., trade name: Crystallite XX, average particle size 2 μm), the viscosity was adjusted to 600 CPS using a homodisper stirrer, and then kneaded with three rolls and exposed to light. A liquid resin solution was prepared.

2) Next, the surface of the copper-clad laminate is photoetched using a conventional method, and the photosensitive resin is applied onto the printed wiring board.
Apply solution A using a knife coater, leave it in a horizontal position for 20 minutes, and dry to the touch at 70°C to a thickness of about 50μ.
A photosensitive resin layer of m was formed.

3) Next, a photomask film on which a black circle of 100 μmΦ was formed was closely attached to this, and light was emitted at 450 mj/crrrl using a short arc lamp. By developing this with a chlorocene solution, a blind through hole with a diameter of 100 μm was formed.

By further heat-treating at 100°C for 1 hour and 150°C for 10 hours, it becomes a photomask film.
A glabellar insulating skin with excellent dimensional accuracy was obtained.

When I observed the cross section of the blind through hole part,
The diameter of the blind through hole was tapered upward, and the diameter at the top was 1100 a and the diameter at the bottom was 85 μm.

In this example, the optical refractive index of the photosensitive resin matrix was about 1.45, the optical refractive index of the epoxy resin particles was about 1.45, and the optical refractive index of the silica particles was about 1.3. .

4) When this insulating film between the eyebrows is treated with chromic acid, the epoxy resin powder that is soluble in chromic acid is dissolved and removed, forming a very complex roughened surface, and when a conductor is formed on this roughened surface. For example, a blind through hole can be formed with very high adhesion! The insulating film between σ and temperature 70
°C, phased with chromic acid at a concentration of 500 g/l, and neutralized solution (
Dip in PM950 (manufactured by Sibley, Inc., product name: PM950) and wash with water. Next, as a chemical copper plating pretreatment, a palladium catalyst (manufactured by Sibley Co., Ltd., trade name: Catabosite 44) was applied to activate the surface, and after immersing it in a chemical copper plating solution with the following composition for 15 minutes, electrolytic copper with the following composition was applied. Copper with a thickness of 20 μm was uniformly deposited on the upper part of the interlayer insulating film using a plating solution.

Chemical copper plating solution composition Sibley 32BA I2.5% 328L
12.5% 328C1.5% Pure water 73.5% temperature
Degree 25°C Electrolytic copper plating solution composition Cu5On ・5oto 150 g
/ 111zS0. 40
g7N'' -200ppm Additive Predetermined amount Temperature 25°C Cathode current density 28/d-tomo 5) Next, an etching mask was formed according to a conventional method, and copper other than the circuit was etched away to form a wiring circuit.

Comparative Example 1 The only difference in the resin composition of Example 1 was that it did not contain benzoguanamine resin fine particles, and the other conditions were the same.

When I observed the cross section of the blind through hole part,
The blind through hole had a diameter of 1100 a at the top and a diameter of 100 μm at the bottom, and had a vertical shape.

Table 1 shows the evaluation results of the connection reliability of blind through holes in Example 1.2 and Comparative Example. The shape of the cross-section of the ball can be easily made into a tapered shape that spreads upward, and the connection reliability between conductor circuits can be ensured relatively easily and easily, and the multi-layer build-up method has better workability. A method for manufacturing a wiring board can be provided, and the effect of contributing to industry is extremely large.

that's all

Claims (1)

[Claims] 1) A method for producing a multilayer wiring board in which a conductive circuit and an organic insulating layer made of a photosensitive resin are laminated in multiple layers, wherein the photosensitive resin contains a light-scattering filler. 1. A method for producing a multilayer wiring board, characterized in that the negative photosensitive resin is used as a negative photosensitive resin. 2) The light-scattering filler has an average particle diameter of 0.1 to
2. The method for manufacturing a multilayer wiring board according to claim 1, wherein the thickness is 10 μm. 3) The method of manufacturing a multilayer wiring board according to claim 1, wherein the light-scattering filler has an optical refractive index difference of 0.1 to 0.7 with respect to the photosensitive resin.