JPH0964493A - Wiring structure of circuit board and its formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a fine circuit wiring of high density by improving adhesion between a circuit wiring, and a base board and an insulation layer and preventing metal of a circuit wiring from diffusing to a circumferential insulation layer and generating migration. SOLUTION: When a required circuit conductor layer is board on a seed layer for a plating lead applied on an insulation base board or an insulation layer by a semiadditive method, the seed layer 2 is formed of a material which is different from that of a circuit conductor layer 4, a conductive coating layer 6 is formed of a material which is the same or different from that of the seed layer 2 in an outer circumference of the circuit conductor layer 4 and an enclosing conductive layer 7 is formed on an outer circumference of the circuit conductor layer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves the adhesion between circuit wiring and a base substrate or an insulating layer, and prevents the metal of the circuit wiring from diffusing into the surrounding insulating layer. The present invention also relates to a wiring structure of a circuit board capable of forming high-density circuit wiring and a method for forming the same.

[0002]

2. Description of the Related Art In order to manufacture a laminated circuit board which can be highly densified by an insulating layer and a circuit conductor layer formed on the insulating layer in the form of required circuit wiring, as shown in FIG. ,
First, using a metal for forming circuit wiring on a suitable base substrate or insulating layer 10, as shown in FIG. 1A, a sheet which becomes a plating lead by a sputtering method or an electroless plating method is formed.
The layer 11 is uniformly formed.

Next, as shown in FIG. 2B, the seed layer 11 is formed.
After forming a mask layer 12 with a photoresist member in an area where no circuit wiring is to be formed, the circuit wiring 1 as shown in FIG.
3 is formed. Therefore, as shown in (4) of FIG.
After the peeling process of 2 is performed, etching is performed to the extent that the exposed region of the seed layer 11 is removed, so that a desired circuit is formed on the base substrate or the insulating layer 10 via the seed layer portion 11A. The wiring 13 can be provided.

Further, another insulating layer 14 is formed on the circuit wiring 13 as shown in FIG. 5 (5), and by repeating the above-described method, a multilayer laminated circuit board having a desired number of layers can be manufactured. it can.

[0005]

In the above circuit board, copper having a low conductor resistance is generally used as a material suitable for the seed layer 11 and the circuit wiring 13, and the insulating layer 1 is also used.
For 0 or 14, polyimide having a low relative dielectric constant is used as a suitable material.

However, since the adhesion between copper and polyimide is weak, there is one problem that peeling is liable to occur between them. On the other hand, copper ions diffuse into the polyimide and electromigrate. This will cause insulation failure and cause short circuit between circuit wirings.
This is a major limitation when manufacturing a circuit board that requires fine and high-density circuit wiring.

Therefore, the present invention improves the adhesion between the circuit wiring and the base substrate or the insulating layer, while preventing the metal of the circuit wiring from diffusing into the surrounding insulating layer and causing migration. The present invention provides a wiring structure of a circuit board and a method for forming the same, by which fine and high-density circuit wiring can be formed by preventing.

[0008]

Therefore, in the wiring structure of the circuit board according to the present invention, a circuit conductor layer provided so as to form a required circuit wiring above the insulating base substrate or the insulating layer, And a surrounding conductive layer formed by adhering a part of the circuit conductive layer to the insulating base substrate or the insulating layer, and the surrounding conductive layer is formed on the insulating base substrate or the insulating layer. It is characterized in that it is formed of a material that does not diffuse.

In the case of such a wiring structure, the region of the surrounding conductive layer which is in close contact with the insulating base substrate or the insulating layer can be formed of the same material as or different from that of the surrounding conductive layer. .

In order to obtain such a wiring structure of the circuit board, a required circuit is formed on the insulating base board or the seed layer for the plating lead deposited on the upper surface of the insulating layer by the semi-additive method. In a wiring forming method of a circuit board for forming a conductor layer, the seed layer is formed of a material different from that of the circuit conductor layer, and then the circuit is formed by plating means using a mask layer on the seed layer. The circuit conductor is formed by forming a conductor layer, then forming a conductive coating layer on the outer periphery of the circuit conductor layer with the same or different material as that of the seed layer, and further removing an unnecessary region of the seed layer. A method of forming a surrounding conductive layer with a part of the seed layer and the conductive coating layer on the outer circumference of the layer is adopted.

Here, the conductive coating layer can be formed by plating means by forming a gap between the circuit conductor layer and the mask layer, and the mask layer can be formed by a positive photoresist. When it is formed of a material, the gap can be formed by re-exposing and developing the mask layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 (1) to 1 (7) are views showing a manufacturing process according to an embodiment of a wiring structure of a circuit board according to the present invention. As shown in FIG. The insulating base 1 is made of a conductive material such as nickel, chromium, tungsten or titanium, which has high adhesion to the insulating layer 1 and does not diffuse to the upper surface of the insulating layer 1 such as a polyimide resin or the like by electroless plating or sputtering. -Approximately 50 layers
It is uniformly formed to a thickness of 0Å to 1000Å.

Next, a positive photoresist is applied to the upper surface of the seed layer 2 and then exposed and developed to form an area other than the area for forming the required circuit wiring. The mask layer 3 is formed as shown in FIG. Therefore, by using the seed layer 2 as a plating lead and plating the exposed area of the seed layer 2 with copper to a thickness of several .mu.m by electrolytic copper plating, a circuit conductor as shown in FIG. Layer 4 can be formed. As the material of the circuit conductor layer 4, other than copper, other good conductor material different from the seed layer 2 can be used.

Then, as shown in FIG. 4 (4), a gap 5 of about several μm is formed in a region adjacent to the circuit conductor layer 4 and the mask layer 3 so that a part of the seed layer 2 is exposed. 3 is re-exposed and developed, a conductive coating layer 6 is formed by depositing a nickel film on the upper surface and both side surfaces of the circuit conductor layer 4 by electrolytic nickel plating as shown in FIG. To do. The conductive coating layer 6 is the same as the seed layer 2 and can be formed of the same kind of material as or a different material from the seed layer 2. It uses a material that has excellent adhesion and has no diffusion that induces electromigration to the insulating layer.

Therefore, after removing the mask layer 3 by peeling, the unnecessary area of the exposed seed layer 2 is completely removed by etching means as shown in FIG. As described above, the surrounding conductive layer 7 that completely surrounds the part of the seed layer 2 and the conductive coating layer 6 can be formed.

Here, in order to obtain a single-layer circuit board, a surface protective layer is formed on the upper surface of the circuit conductor layer 4 having the surrounding conductive layer 7 by using an appropriate insulating film member or insulating resin as required. Although it may be formed, when a multilayer circuit board is formed, a suitable insulating material such as a photosensitive polyimide resin is provided on the upper surface of the circuit conductor layer 4 having the surrounding conductive layer 7, as shown in FIG. By forming the insulating layer 8 using the same and then repeating the above method, it is possible to fabricate a multilayer circuit board having circuit conductor layers surrounded by the surrounding conductive layers. In the case of such a laminated circuit board, although not shown, a multilayer structure in which required portions in upper and lower circuit conductor layers are electrically connected to each other by using via holes formed in insulating layers between layers The laminated circuit board of can also be manufactured.

As shown in (6) and (7) of FIG. 1, by adopting the method of the present invention, the surrounding conductive layer 7 consisting of a part of the seed layer 2 and the conductive coating layer 6 is formed. It is possible to form a wiring structure that surrounds the entire circumference of each circuit conductor layer 4. According to this structure, a good conductor material is arbitrarily used for the circuit conductor layer 4, and the seed layer 2 and the conductive layer are made conductive. As the coating layer 6, it is possible to use an appropriate conductive material which is different from the circuit conductor layer 4 and has a high adhesion to the insulating layers 1 and 8 and does not cause migration. It will be understood from the above description that the seed layer 2 and the conductive coating layer 6 can be formed of the same kind or different materials.

[0018]

According to the present invention, the surrounding conductor layer is formed so as to surround the circuit conductor layer formed as the required circuit wiring, and the surrounding conductor layer is formed of a conductive material different from that of the circuit conductor layer inside. This makes it possible to construct a suitable wiring structure for a circuit board that can prevent migration while ensuring adhesion with the insulating base board or the insulating layer.

Therefore, insulation failure and short circuit between wirings can be surely prevented, so that a highly functional laminated circuit board having a fine and high-density wiring structure can be provided with good quality.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram for explaining a wiring structure of a circuit board according to the present invention.

FIG. 2 is a manufacturing process diagram for explaining a wiring structure of a circuit board according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating base substrate or insulating layer 2 Seed layer 3 Mask layer 4 Circuit conductor layer 5 Gap 6 Conductive coating layer 7 Surrounding conductive layer 8 Insulating layer

Claims (6)

[Claims] 1. An insulating base substrate or a circuit conductor layer provided above an insulating layer so as to form required circuit wiring, and a part of the insulating base substrate surrounding the periphery of the circuit conductor layer. Or a surrounding conductive layer formed in close contact with an insulating layer, wherein the surrounding conductive layer is formed of a material that does not diffuse into the insulating base substrate or the insulating layer. Wiring structure. 2. A region of the surrounding conductive layer, which is in close contact with the insulating base substrate or the insulating layer, is made of the same material as or different from that of the surrounding conductive layer. Circuit board wiring structure. 3. A wiring forming method for a circuit board, wherein a required circuit conductor layer is formed by a semi-additive method on a seed layer for plating lead deposited on the upper surface of an insulating base board or an insulating layer. In that, after the seed layer is formed of a material different from that of the circuit conductor layer, the circuit conductor layer is formed on the seed layer by a plating means using a mask layer, and then the circuit conductor layer is formed. A conductive coating layer is formed on the outer periphery of the same or different material as that of the seed layer, and an unnecessary region of the seed layer is removed to remove one of the seed layers on the outer periphery of the circuit conductor layer. A method for forming wiring on a circuit board, characterized in that an electrically conductive surrounding layer is formed by the portion and the electrically conductive coating layer. 4. The wiring forming method for a circuit board according to claim 3, wherein the conductive coating layer is formed by a plating means by forming a gap between the circuit conductor layer and the mask layer. 5. The circuit board wiring forming method according to claim 3, wherein the mask layer is formed of a positive photoresist material. 6. The circuit board wiring forming method according to claim 4, wherein the gap is formed by subjecting the mask layer to re-exposure and development.