JPH05218644A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To provide the manufacture of a multilayer printed wiring board which has an interlayer insulating film made of organic resin and a conductor layer excellent in adhesion. CONSTITUTION:In the manufacture of a multilayer printed wiring board, wherein organic resin is used as interlayer insulating films 14 and 24, it is so constituted as to precipitate electroless palladium platings 16 and 26 on infer layer insulating films 14 and 24 as the plating base films 16 and 26 of conductor layers when forming the conductor layer on each interlayer insulating film 14 and 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board using a polyimide resin having a low dielectric constant as an interlayer insulating film.

Printed wiring boards are expected to grow significantly in the future with the development of semiconductors, and with the demand for miniaturization, high performance, and multi-functionalization of electronic equipment and devices, the printed wiring boards used for them are being demanded. In particular, higher densities, higher integration, and finer circuits are required, and printed wiring board manufacturing technology that meets these requirements is required.

Specifically, as a method of densifying and highly integrating a printed wiring board, a plurality of wiring layers are laminated and the wiring layers are connected by through holes and via holes. There is a method of miniaturizing and using a small-diameter via hole for front and back connection.

In a method of manufacturing a multilayer printed wiring board using a polyimide resin or the like having a low dielectric constant as an interlayer insulating film among the multilayer printed wiring boards, copper polyimide wiring technology, especially formation of a conductor layer is required in order to meet the demand for a high-speed circuit mounting package. Technology and technology for forming via holes for interlayer connection have become important issues.

[0005]

2. Description of the Related Art In a conventional method for manufacturing a multilayer printed wiring board using an organic resin such as a polyimide resin as an interlayer insulating film, an electroless plating method, a vapor deposition method or a sputtering method is used to form a plating base film for a conductor layer. Had formed.

In the electroless plating method, a first polyimide layer is formed on a ceramic substrate, and an electroless copper plating film as a plating base film is formed on the polyimide layer in an amount of 0.2 to 0.2.
Precipitate to a thickness of 0.3 μm. Next, an electrolytic copper-plated film is uniformly formed on the electroless copper-plated film, and patterned to remove unnecessary portions of the copper-plated film.

Next, after forming the second polyimide layer uniformly, patterning is performed to remove the second polyimide layer on the copper plating film. Further, after the second-layer electroless copper-plated film is uniformly deposited, the second-layer electrolytic copper-plated film is formed, whereby the first-layer electrolytic copper-plated film and the second-layer electrolytic copper-plated film are formed. And the electrolytic copper-plated film are connected at the via hole portion.

A multilayer printed wiring board manufactured by the electroless copper plating method is shown in FIG. 2 is a ceramic substrate, 3 is a first-layer polyimide layer, 4 is a first-layer electrolytic copper plating film, 5 is a second-layer polyimide layer, 6 is a second-layer electrolytic copper-plating film, 7 Is a via hole for interlayer connection.

In the conventional method for manufacturing a multilayer printed wiring board using the vapor deposition method, a plating base film of chromium or nickel is deposited on the polyimide layer. A multilayer printed wiring board manufactured by the vapor deposition method is shown in FIG.
The same components as those in (A) are designated by the same reference numerals. 7'is a via hole for interlayer connection.

[0010]

In the conventional method for manufacturing a multilayer printed wiring board using the electroless copper plating method,
Since the electroless copper plating has a large plating stress, there is a problem that adhesion failure 8 occurs between the conductor and the polyimide layer 3 as shown in FIG. there were.

Further, in the method of manufacturing a multilayer printed wiring board using the vapor deposition method, as shown in FIG. 4 (B), the coverage of the vapor deposition film of chromium or nickel is insufficient at the via hole portion 7'for interlayer connection. Therefore, there is a problem that the defective connection portion 9 occurs.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a multilayer printed wiring board having an interlayer insulating film formed of an organic resin and a conductor layer having excellent adhesion. It is to provide a manufacturing method of.

[0013]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a multilayer printed wiring board using an organic resin as an interlayer insulating film, wherein a conductor layer is formed on each interlayer insulating film. In this case, there is provided a method for producing a multilayer printed wiring board, characterized in that electroless palladium plating is deposited on the interlayer insulating film as a plating base film for the conductor layer.

[0014]

[Function] Since electroless palladium plating has much smaller plating stress than conventional electroless copper plating, strong adhesion with an organic resin can be obtained. As a result, unlike the conventional electroless copper plating method, the adhesion failure with the organic resin does not occur when the conductor is formed.

Further, the organic resin is chemically weak against alkali, but the electroless palladium plating bath is weakly acidic, so that the chemical resistance to the organic resin is higher than that of the conventional strong alkaline electroless copper plating bath. improves.

[0016]

EXAMPLE A manufacturing process of a multilayer printed wiring board according to an example of the present invention will be described in detail below with reference to FIG.

First, as shown in FIG. 1 (a), the first polyimide layer 14 is coated on the ceramic substrate 12 using a spin coater and heated to about 400 ° C. to cure the first polyimide layer 14. ..

Then, after roughening the surface of the first polyimide layer 14, electroless palladium plating 16 is uniformly deposited to a thickness of about 2 μm, and a photoresist 18 is applied thereon. A dry film may be laminated as the photoresist 18. Next, when patterning is performed using a mask, the state shown in FIG. 1B is obtained.

Next, an electrolytic copper plating film 20 is deposited in a thickness of about 25 μm on the portion where the photoresist 18 is removed, and an electrolytic nickel plating film 22 is thinly formed thereon. The state in which the electrolytic nickel plating film 22 is formed is shown in FIG.
It is shown in (c).

A nickel plating film 22 is formed on the copper plating film 20.
Is formed in order to improve the peeling of the second polyimide layer applied in the step described later at this portion. Next, the photoresist 18 is peeled off, and the electroless palladium plating film 16 is removed by etching. This state is shown in FIG.

Then, the second polyimide layer 24 is uniformly applied using a spin coater, and the second polyimide layer 24 is semi-cured at about 160 ° C.
When patterning 4 is performed, the state shown in FIG.

After roughening the surface of the second polyimide layer 24, a second electroless palladium plating film 26 is uniformly deposited to a thickness of about 2 μm, and a photoresist 28 is uniformly applied thereon. .. When the photoresist 28 is patterned using the mask, the state shown in FIG. 1F is obtained.

In this state, an electrolytic copper plating film 30 is deposited on the removed portion of the photoresist 28 to a thickness of about 25 μm, and the photoresist 28 is peeled off. This state is shown in FIG.

Finally, the electroless palladium plating film 26 is removed by etching to manufacture a two-layer printed wiring board in which the conductor layers are connected to each other at the via holes 32 as shown in FIG. 1 (h). it can. Figure 1
An enlarged view of (h) is shown in FIG.

A printed wiring board having three or more layers can be easily manufactured by repeating the above steps. Connection of three or more conductor layers should not be made in the same via hole portion, but via holes for interlayer connection should be formed at gradually separated locations, and two conductor layers should be connected in each via hole. desirable.

In the above-mentioned embodiment, the electrolytic copper plating film 20 and the electrolytic nickel film 22 are formed in the step of FIG. 1 (c), but the present invention is not limited to this, and each is electroless. You may make it deposit a copper plating film and an electroless nickel plating film. Similarly, FIG.
Instead of the electrolytic copper plating film 30 deposited in the step (g), an electroless copper plating film may be deposited.

A method of manufacturing a multilayer printed wiring board according to another embodiment of the present invention will be described with reference to FIG. In this embodiment, first of all, a first substrate is formed on the ceramic substrate 42.
The polyimide layer 44 is formed, and the first electroless palladium plating film 46 is formed on the first polyimide layer 44 by using the additive method.

Further, after the second polyimide layer 48 is uniformly applied and patterned, the second electroless palladium plating film 50 is similarly formed by the additive method to form the first electroless palladium plating film 50.
The electroless palladium plating film 46 and the second electroless palladium plating film 50 are connected.

Since the electroless palladium plating bath is weakly acidic, it is chemically stable with respect to the polyimide resin. Therefore, it becomes possible to perform thick plating on the polyimide resin as in this embodiment, and the conductor layer can be formed only by electroless palladium plating.

According to this embodiment, since the conductor layer is formed by the additive method, there is an advantage that the etching process is unnecessary. In the above-mentioned embodiment, the embodiment in which the polyimide resin is adopted as the interlayer insulating film has been described, but the interlayer insulating film of the present invention is not limited to this, and other organic resin such as Teflon resin is adopted. You can also

[0031]

EFFECTS OF THE INVENTION Since the present invention uses electroless palladium plating with very low plating stress as the plating base film of the conductor layer, it has excellent adhesion to the polyimide resin and can prevent peeling of the conductor layer. Play.

Since the electroless palladium plating is weakly acidic, it is chemically stable to the polyimide resin. Therefore, it becomes possible to perform thick plating on the polyimide resin, and the conductor layer can be formed only by electroless palladium plating.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process according to an embodiment of the present invention.

FIG. 2 is an enlarged view of FIG. 1 (h).

FIG. 3 is a diagram showing another embodiment.

FIG. 4 is a diagram illustrating a problem of a conventional example.

[Explanation of symbols]

 12 Ceramic Substrate 14 First Polyimide Layer 16,26 Electroless Palladium Plating Film 20 Copper Plating Film 22 Nickel Plating Film 24 Second Polyimide Layer 30 Copper Plating Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Ishida, 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor: Makoto Ishihara, 1015, Ueda-anaka, Nakahara-ku, Kawasaki, Kanagawa

Claims (5)

[Claims] 1. In a method for manufacturing a multilayer printed wiring board using an organic resin as an interlayer insulating film (14, 24), when a conductor layer is formed on each interlayer insulating film (14, 24), A method for producing a multilayer printed wiring board, which comprises depositing electroless palladium plating (16, 26) on an interlayer insulating film (14, 24) as a plating underlayer film (16, 26). 2. The electroless palladium plating (16,2) is used as the conductor layer.
6) The method for producing a multilayer printed wiring board according to claim 1, which has a two-layer structure in which copper plating (20, 30) is applied on the top. 3. The method for manufacturing a multilayer printed wiring board according to claim 2, wherein the conductor layer has a three-layer structure in which nickel plating (22) is further applied on copper plating (20). 4. The method for producing a multilayer printed wiring board according to claim 1, wherein the organic resin is a polyimide resin. 5. The method for producing a multilayer printed wiring board according to claim 1, wherein the electroless palladium plating bath is acidic.