JPH06310856A - Manufacture of multilayer wiring board - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a high density multilayer wiring board having excellent heat resistance as well as high bonding strength to a heat resisting resin film and a conductor circuit. CONSTITUTION:After the formation of the first conductor having a land part on the surface of an insulating substrate (alumina ceramic substrate 1) with a through hole 4 formed therein, the surface of the first conductor excluding the through hole 4 and the land part as well as the exposed surface of the insulating substrate are coated with a heat resisting regin next, after blasting, roughening and ultrasonics sound a cleaning the surface of the heat resisting resin film, the second conductor is formed and after exposing, developing, etching and peeling a resin film, the necessary parts only of the second conductor are left to form a conductor circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has high adhesion strength,
In particular, it relates to a method for manufacturing a high-density multilayer wiring board having through holes.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for electronic devices to have higher functionality and higher density, and multilayer wiring boards for the purpose of higher density are also used in the wiring boards constituting these. Conventionally, as a multilayer wiring board, a prepreg is interposed as an insulating layer between a plurality of circuit boards each having a conductor circuit formed on the surface thereof and these are pressed, then through holes are formed, and plating is performed in each of the through holes. A multilayer wiring board in which conductor circuits are connected has been used.

However, in these multilayer wiring boards, since a plurality of conductor circuits are formed and then through holes are formed to connect the conductor circuits, it is difficult to satisfy the demands for high functionality and high density. there were.

As a multilayer wiring board capable of solving such a problem, a multilayer wiring board in which conductor circuits and organic insulating films are alternately laminated has been recently developed. A method for producing such a multilayer wiring board is disclosed in Japanese Patent Laid-Open No.
There is a method as disclosed in Japanese Patent Laid-Open No. 2-5704. The multilayer wiring board manufactured by this method, after forming an adhesive layer containing oxidatively decomposable rubber or synthetic rubber on the surface of the heat-resistant resin film formed on the insulating substrate, the surface of the adhesive layer is roughened, It is composed of a step of forming a conductor circuit by electroless copper plating.

[0005]

However, in the above method, the work for forming the adhesive layer is required, and the process becomes complicated. There are drawbacks such that the conductor circuit is peeled off by the heat generated when soldering to the multilayer wiring board, the adhesion strength of the conductor circuit is low, and it cannot be applied to the formation of fine wiring.

The present invention provides a method for manufacturing a multilayer wiring board which does not have the above-mentioned drawbacks.

[0007]

According to the present invention, after forming a first conductor having a land portion on a surface of an insulating substrate having a through hole formed therein, a first conductor excluding the through hole and the land portion is formed.
Cover the surface of the conductor and the exposed surface of the insulating substrate with heat resistant resin,
Next, the surface of the heat-resistant resin coating film is blasted, roughened, and ultrasonically cleaned, and then a second conductor is formed, followed by exposure, development, and
The present invention relates to a method for manufacturing a multilayer wiring board in which a conductor circuit is formed by etching, removing a resist film, and leaving only a necessary portion of a second conductor.

In the present invention, a glass epoxy substrate, a glass polyimide substrate, an alumina ceramic substrate, a glass substrate, an aluminum nitride substrate, or the like is used as the insulating substrate, but it is preferable to use a material having high heat resistance as much as possible.

Epoxy resin, polyimide resin, phenol resin, acrylic resin and the like are used as the heat resistant resin. In these resins, a photosensitive material is applied and cured by the screen printing method from the viewpoint of workability of forming a through hole. It is preferable to use the above resin. The thickness of the heat resistant resin coating is not particularly limited, but it is 10 from the viewpoint of workability.
It is preferably about 100 μm.

The abrasive used for the blast treatment is not particularly limited, but alumina particles having a particle size of # 220 to # 1000 are used, and the discharge pressure is 9.8 × 10 ⁴ Pa to 3.9 ×.
Treatment under the condition of 10 ⁵ Pa is preferable since the surface roughness of the heat resistant resin coating can be freely controlled to 0.2 to 10.0 μm (Rmax).

The oxidizing agent or acid used as a roughening liquid for roughening is an oxidizing agent containing at least one selected from chromic acid, chromate salts and permanganate salts, or hydrochloric acid, sulfuric acid, fluorine. Although an acid solution containing at least one selected from hydrofluoric acid is used, it is preferable to use an oxidant solution containing permanganate, which has a relatively small amount of etching to the exposed conductor circuit.

There are no particular restrictions on the ultrasonic cleaning conditions, but from the standpoint of workability, water or warm water having a temperature of 40 to 80 ° C. and an ultrasonic output of 300 watts / 50 liters will be used.
It is preferable to wash for 0 minutes. Further, exposure, development, etching and peeling of the resist film are not particularly limited and may be carried out by conventionally known methods.

In the present invention, a via hole is formed by removing a part of the heat resistant resin coating on the first conductor, if necessary. Further, as the first conductor and the second conductor, C
Metals such as u and Ni are used, and if necessary, Au is used for the second conductor.

[0014]

EXAMPLES Examples of the present invention will be described below. Example 1 As shown in FIG. 1A, the dimensions are 80 × 80 mm,
A through hole 4 having a diameter of 0.6 mm is formed by laser processing at a predetermined position of an alumina ceramic substrate (trade name: Harox 552, manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 0.635 mm. After roughening the surface by a conventionally known method, a copper coating 3 is formed by an electroless plating method, a resist film (not shown) is further formed on the upper surface of the copper coating 3, and then exposure, development and etching are performed. , The resist film is peeled off, and only the necessary portions of the copper coating 3 are left, and the conductor circuit of the inner layer as shown in FIG.
A wiring board having the conductor 3 ') formed thereon was obtained.

Next, a photosensitive resist ink (PSR-4000-Z404, manufactured by Taiyo Ink Mfg. Co., Ltd.) is applied to the surface of the first conductor 3'excluding the through hole 4 and the land 2 and the exposed surface of the alumina ceramic substrate 1. The entire surface was applied by a screen printing method, a negative film (not shown) was further attached to the upper surface thereof, and then exposed to cure the photosensitive resist ink provided on the lower surface of the transparent portion of the negative film. Next, the negative film is removed, and the photosensitive resist ink in the unhardened part, more specifically, the unexposed part is developed and removed, and as shown in FIG. Further, a heat resistant resin coating 5 was formed on the portion excluding the through hole 4 and the land portion 2 and cured in an oven at 150 ° C. for 60 minutes.

Next, a blast machine (manufactured by Fuji Seisakusho, trade name S
C-6B) was used to uniformly blast the heat-resistant resin coating 5 and the exposed surface of the first conductor 3 '. The blasting treatment was carried out by using # 600 alumina particles (manufactured by Fuji Manufacturing Co., Ltd., trade name WA-600) as an abrasive material under a discharge pressure of 19.6 × 10 ⁴ Pa for 30 seconds, and then, as shown in FIG. ), The heat-resistant resin film 5 has a surface roughness of 4.
A double-sided wiring board of 0 μm (Rmax) was obtained. FIG. 1D 'shows an enlarged view of the surface of the heat resistant resin coating 5 after the blast treatment.

After roughening, the above-mentioned double-sided wiring board is immersed and washed in a degreasing liquid (Hitachi Chemical Co., Ltd., trade name HCR-201), and then a roughening liquid having a liquid temperature of 50 ° C. (trade name, manufactured by Ebara Densan Co., Ltd.) It was roughened by immersion in permanganate 465) for 10 minutes. After washing with water, the surface of the heat resistant resin coating 5 was roughened by immersing it in a neutralizing solution (product name: Neutralizer N-466, manufactured by Ebara Densan) having a liquid temperature of 30 ° C. for 3 minutes. A roughened state is shown in FIG. 2 (e), and an enlarged view of the heat resistant resin coating 5 is shown in (e '). A reaction product (fragile layer) 10 was formed on the surface of the heat resistant resin film 5.

Next, the above-mentioned double-sided wiring board is immersed in tap water, and vibration energy by ultrasonic waves (output 300 watts) is applied for 10 minutes to produce a reaction product (fragile layer) formed on the surface of the heat resistant resin coating 5. 10 was removed. This state is shown in Figure 2.
(F), and (f ') is an enlarged view of the heat resistant resin coating 5.

After that, the above-mentioned double-sided circuit board is washed and electroless Ni-P plating (manufactured by Okuno Seiyaku Co., Ltd., trade name TMP chemical nickel) is performed for 10 minutes, and as shown in FIG. A Ni-P coating 7 having a thickness of 0.6 μm was formed.

Next, it is immersed in a H ₂ SO ₄ solution having a concentration of 10% by weight for 1 minute, washed with water, and then electro-Cu plated (PC-606, manufactured by Ebara Densan Co., Ltd.) for 30 minutes, and the upper surface of the Ni-P coating 7 is coated. As shown in FIG. 2 (h), a Cu coating 8 having a thickness of 10 μm is formed.
Was formed to obtain a second conductor.

After this, after pickling with a H ₂ SO ₄ solution having a concentration of 10% by weight, a photosensitive resist film (PHT-862AF-40, manufactured by Hitachi Chemical Co., Ltd.) was attached on the entire surface of the Cu coating film 8. Further, a negative film (not shown) was attached to the upper surface of the negative film, which was then exposed to cure the photosensitive resist film provided on the lower surface of the transparent portion of the negative film. Next, the negative film was removed, and the photosensitive resist film 9 in the unhardened portion, more specifically, the unexposed portion as shown in FIG. 3 (i) was developed and removed.

Next, etching was performed by a spray etching method using a CuCl ₂ etching solution to remove the Ni-P coating 7 and the Cu coating 8 of the second conductor, which are unnecessary portions of the conductor circuit. Then, the photosensitive resist film which has been cured with a NaOH solution having a concentration of 5% by weight is peeled off, washed with pure water and dried to have a size of 2 × 2 as shown in FIG.
A multi-layer wiring board (A) having a conductor circuit 13 of mm was obtained.

Thereafter, the multilayer wiring board (A) obtained above was washed with a degreasing liquid (HCR-201, manufactured by Hitachi Chemical Co., Ltd.), washed with water and then pickled with a H ₂ SO ₄ solution having a concentration of 10% by weight. Then, after soft etching with (NH ₄ ) ₂ S ₂ C ₈ aqueous solution having a concentration of 10% by weight, electroless Ni-P plating is performed for 15 minutes, and as shown in (k) of FIG. -P coating 11 was formed. The electroless Ni-P plating solution used was Nicolon-U, a trade name of Okuno Seiyaku, and was used at a liquid temperature of 85 ° C for 15
Plated for minutes.

After washing the multilayer wiring board (A) having the Ni-P coating film 11 with pure water, electroless primary Au plating (EEJ) is performed.
Electroless Ni-P coating 1 as shown in FIG.
An Au coating 12 having a thickness of 0.06 μm was formed on the surface of No. 1. Then, after washing with pure water, electroless secondary Au plating (EE
Made by JA, product name RECTROLES MT, liquid temperature 85 ℃) 30
After that, a multilayer wiring board (B) having a 0.5 μm-thick Au coating 12 applied thereon was obtained.

Next, the adhesion strength was measured by the pull test method using 20 pieces of the multilayer wiring board (B) having the Au coating 12 thickened. In the following comparative examples, the adhesion strength was measured by the same method. As a result, in the range of 22 to 28 MPa, the adhesion strength was an average value of 25 MPa, which was good. Moreover, the appearance was observed, but no blister was observed in the conductor circuit.

Furthermore, 20 pieces of the multilayer wiring board (B) obtained in Example 1 were immersed in 6: 4 solder (Pb: Sn = 6: 4) which was heated and melted at 240 ° C. for 5 seconds and then pulled up.
The process of immersing again for 5 seconds was repeated 5 times, and the adhesion strength was measured by the pull test method. As a result, 20-27M
Within the range of Pa, the adhesive strength was good, showing an average value of 25 MPa. Moreover, the appearance was observed, but no blister was observed in the conductor circuit.

Comparative Example 1 A multilayer wiring board having a thickened Au film was obtained through the same steps as in Example 1 except that the step of removing the reaction product by ultrasonic cleaning after roughening in Example 1 was omitted. Obtained.

When the adhesion strength of the obtained multilayer wiring board was measured, the average value was as weak as 6 MPa in the range of 0 to 15 MPa, and the variation was large. In addition, when the appearance was observed, minute blisters were found in some parts of the conductor circuit. The adhesion strength after soldering heat resistance, which was performed in the same manner as in Example 1, was not measured because a minute swelling occurred in the conductor circuit.

Comparative Example 2 A multilayer wiring board having a thick Au coating was obtained through the same steps as in Example 1 except that the blasting step in Example 1 was omitted.

When the adhesion strength of the obtained multilayer wiring board was measured, the average value was as weak as 6 MPa in the range of 0 to 16 MPa, and the variation was large. In addition, when the appearance was observed, minute swelling occurred in the conductor wiring. The adhesion strength after soldering heat resistance, which was performed in the same manner as in Example 1, was not measured because a minute swelling occurred in the conductor circuit.

[0031]

According to the present invention, it is possible to inexpensively manufacture a high-density multilayer wiring board having a high adhesion strength between a heat-resistant resin film and a conductor circuit, a small variation in the adhesion strength, and an excellent heat resistance. You can

[Brief description of drawings]

1 (a) to 1 (d) are cross-sectional views showing a manufacturing operation state of a multilayer wiring board in an example of the present invention.

2 (e) to (h) are cross-sectional views showing a manufacturing operation state of the multilayer wiring board in the example of the present invention.

3 (i) to (l) are cross-sectional views showing a manufacturing operation state of the multilayer wiring board in the example of the present invention.

[Explanation of symbols]

 1 Alumina Ceramic Substrate 2 Land Part 3 Cu Coating 3'First Conductor 4 Through Hole 5 Heat Resistant Resin Coating 6 Via Hole 7 Ni-P Coating 8 Cu Coating 9 Photosensitive Resist Film 10 Reaction Product 11 Ni-P Coating 12 Au Coating 13 conductor circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Okishima 1380 Nishihara, Katsuta City, Ibaraki Prefecture 1380 Nishihara, Hitachi Chemical Co., Ltd. (72) Takayoshi Yabuki 1380 Nishihara, Katsuda City, Ibaraki Prefecture 1380 Nishihara, Hitachi Within Kasei Ceramics Co., Ltd. (72) Inventor Kazuhisa Suzuki, 1380 Nishihara, Katsuta-shi, Ibaraki, Osaka, 1380 Hitachi Chemicals Co., Ltd. (72) Tetsuo Takeoka 1380 Nishihara, Katsuta, Ibaraki, Nishihara, Hitachi 1 Within the corporation

Claims (1)

[Claims] 1. A first conductor having a land portion is formed on the surface of an insulating substrate having a through hole, and the surface of the first conductor excluding the through hole and the land portion and the exposed surface of the insulating substrate are heat-resistant. After coating the surface of the heat-resistant resin film with a resin, blasting, roughening and ultrasonic cleaning the second conductor, and then exposing, developing, etching, peeling the resist film, and the need for the second conductor. A method for manufacturing a multilayer wiring board, characterized in that a conductor circuit is formed by leaving only the above portions.