JPH0629665A - Multilayer circuit board and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to improve the reliability of electrical continuity of a conductive portion that connects wiring patterns and to efficiently manufacture a multilayer circuit board. A multi-layer circuit board in which a wiring pattern is formed in multiple layers with an electrically insulating layer interposed between the layers, and a conductive portion electrically connecting the wiring patterns is provided between the layers,
The conductive portion is formed by covering the surface of an insulator standing in a columnar shape on the insulating layer 16 with a conductor metal film 22. The conductor metal film 22 on the top of the columnar body 20 of the conductive portion is one wiring pattern 28. And the conductor metal film 22 on the outer wall base of the columnar body is connected to the other wiring pattern 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer circuit board and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a circuit board on which a semiconductor element is mounted, there is a so-called thin film multi-layer circuit board in which a plurality of wiring patterns are formed in layers with an insulating layer having electrical insulation such as polyimide interposed between layers. This circuit board is intended to enable propagation of high-speed signals and the like by forming fine wiring patterns in multiple layers. FIG. 4 shows a state in which wiring patterns are formed in multiple layers by thin film formation. In the figure, 2 is a support substrate, 3 is an insulating layer, and 4 is a wiring pattern. Electrical connection between the wiring patterns 4 sandwiching the insulating layer 3 is established by the conducting portion 5. In order to manufacture such a thin film multilayer circuit board, the wiring pattern 4 is formed on the support substrate 2 in a predetermined pattern, and an electrical insulator such as polyimide is formed in a thin film thereon to form an insulating layer, It can be formed by sequentially continuing the method of forming a wiring pattern by providing a conductive thin film on the insulating layer.

[0003]

By the way, the wiring patterns 4 are connected by the conducting portions 5 as described above. When the conducting portions 5 are formed, conventionally, a conducting hole is formed in the insulating layer 3, There are known a method of swelling plating in the conductive hole by an additive method and a method of forming a conductive metal film on the inner wall of the conductive hole by a sputtering method. However, when the aspect ratio of the conductive hole becomes large, the above method has a problem in that the connection between the wiring pattern and the conductive portion lacks reliability. This is because when the aspect ratio increases, the insulator remains on the wiring pattern upper surface on the inner bottom surface of the conductive hole when the insulating layer 3 is etched to form the conductive hole, or the underlying metal is oxidized by the subsequent heat treatment. This makes it difficult for plating to adhere. Further, in the sputtering method, wire breakage or partial cracking occurs in the inner wall of the conduction hole or in the vicinity of the opening of the conduction hole.

Further, when the conductive portion is formed by plating, it is necessary to make the plated portion conductive to the plating electrode. However, since the conductive portion is conventionally made through the lead pin for mounting, the work for obtaining this conduction is performed. However, there is a problem in that the manufacturing process is inefficient and the manufacturing process becomes inefficient. Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a multilayer circuit board and its manufacture, which can ensure electrical connection between wiring patterns and are easy to manufacture. There is a way to provide.

[0005]

The present invention has the following constitution in order to achieve the above object. That is, in a multi-layer circuit board in which a wiring pattern is formed in multiple layers with an electrically insulating layer interposed between layers, and a conductive portion electrically connecting the wiring patterns is provided between layers, the conductive portion is pillar-shaped on the insulating layer. A conductor metal film is formed on the surface of an insulator standing upright, and the conductor metal film on the top of the columnar body of the conducting portion is connected to one wiring pattern, and the conductor metal of the outer wall base of the columnar body is connected. The film is connected to the other wiring pattern. In addition, the conductive portion is formed in a conductive hole that connects an insulating layer interposed between the opposing wiring patterns in the thickness direction, and an inner bottom surface of the conductive hole facing one wiring pattern and an inner wall of the conductive hole. And a conductor metal film formed on the inner wall is connected to the one wiring pattern, and a conductor metal film provided on the inner wall is connected to the other wiring pattern. The inside is filled with the insulating layer. In addition, in the method for manufacturing a multilayer circuit board, in which a wiring pattern is formed in multiple layers with an electrically insulating layer interposed between the layers, and a conductive portion that electrically connects the wiring patterns is provided between the layers, a wiring pattern is formed on the first wiring pattern. An insulating layer is formed, the insulating layer is etched to form a conductive hole reaching the wiring pattern, and a columnar body made of an insulator is erected on the insulating layer. The insulating layer, the surface of the columnar body, and the conductive hole are formed. Forming a conductor metal on the inner bottom surface and the inner wall of the inner conductor, forming a conductor metal film on the inner bottom surface, the inner wall and the top of the columnar body, and the outer wall, and forming a second wiring pattern on the insulating layer, An insulating layer is further formed on the layer, and a third wiring pattern is formed on the insulating layer with a conductive metal, whereby a wiring pattern can be formed in multiple layers with the conduction holes and the columnar body portions as conduction portions. The features.

[0006]

When the conductive patterns are provided between the wiring patterns, a columnar body of an insulator is provided on the insulating layer, and the insulating layer and the columnar body are covered with the conductor metal film, so that the conductor metal film provided on the columnar body is electrically connected. As a part, the wiring patterns are connected. In the case where the conductive hole is provided, the wiring patterns are connected by the conductive metal film provided on the inner bottom surface and the inner wall of the conductive hole. By forming a conductive hole in the insulating layer and forming a columnar body on the insulating layer to form a conductor metal film, a wiring pattern is formed in the insulating layer and the insulating layer is sandwiched on both sides of this wiring pattern. Thus, the conductive portion that electrically connects the lower layer wiring pattern and the upper layer wiring pattern adjacent to each other can be easily formed, and the multilayer circuit board can be efficiently manufactured.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. First, a method for manufacturing a multilayer circuit board according to the present invention will be described with reference to FIG. 1 in FIG.
Reference numeral 0 is a support base for the multilayer circuit board. First, the wiring pattern 12 of the first layer is formed on the support base 10. Although a ceramic substrate is used as the support base 10 in the embodiment, the wiring pattern 12 is formed by metallizing the support base 10 in advance, or by plating the support base 10.
It is formed by a method of forming a thin film of a conductive metal on the substrate and forming a pattern by etching.

Since the wiring pattern 12 is formed with a step corresponding to the thickness thereof, the step due to the wiring pattern 12 is eliminated by applying an insulating pattern 14 made of a heat-resistant polymer such as polyimide to the same thickness as the wiring pattern 12. .
After applying the insulating pattern 14, the upper layer is coated with polyimide to form an insulating layer 16. When a wiring pattern is formed in multiple layers by forming a thick film, undulations are likely to occur on the surface of each layer. The insulating pattern 14 is used to form the surface of the insulating layer 16 into a flat surface. FIG. 1A shows a state in which the wiring pattern 12 is formed, the insulating pattern 14 is applied, and the insulating layer 16 is formed.

Next, the insulating layer 16 is etched to form a conductive hole 18 for conducting the wiring pattern of the first layer (FIG. 1 (b)). The conductive hole 18 is formed in the wiring pattern 1 under the insulating layer 16 as in the case of forming a conventional conductive portion.
The insulating layer 16 is formed by etching until 2 is exposed. After forming the conduction hole 18, the insulating layer 16 is cured to form the complete insulating layer 16. Next, a polyimide columnar body 20 is formed on the insulating layer 16 (FIG. 1 (c)). The columnar body 20 is formed by applying polyimide to the insulating layer 16 and forming a pattern by etching and leaving the columnar body 20. The columnar body 20 is for connecting the wiring pattern 24 of the second layer formed on the insulating layer 16 and the wiring pattern 28 of the upper third layer. In the embodiment, the columnar body 20 is formed relatively thick in order to increase the interlayer distance. The conduction hole 18 and the columnar body 20 are provided at appropriate positions in the plane according to the patterning of the wiring pattern, and of course, may be provided at a plurality of places.

After the columnar body 20 is formed, a conductor metal is sputtered to form a conductor metal film 22 on the upper surface of the insulating layer 16, the conductive hole 18, and the entire surface of the columnar body 20. FIG. 1D shows a state in which the conductor metal film 22 is formed and then the conductor metal film 22 is patterned to form the second layer wiring pattern 24. In the portion of the conduction hole 18, the conductor metal film 22 covers the inner bottom surface and the inner wall of the conduction hole 18, and electrically connects the wiring pattern 12 in the lower layer and the wiring pattern 24 in the upper layer sandwiching the insulating layer 16. The conductor metal film 22 forms a conductive portion that connects the wiring patterns. The top and outer wall of the columnar body 20 are covered with the conductor metal film 22. The conductor metal film 22 also serves as a conductive portion that connects the wiring pattern 24 of the second layer and the wiring pattern of the upper third layer. When forming the conductor metal film 22 on the insulating layer 16 of polyimide and the columnar body 20, it is preferable to first sputter a metal such as Cr having good adhesion to the polyimide and then sputter Cu or the like having excellent conductivity. Good.

After forming the wiring pattern 24 of the second layer,
The insulating layer 26 is formed on the insulating layer 16, and a conductor metal is sputtered on the upper surface of the insulating layer 26, and the conductor metal film is etched in a predetermined pattern to form a wiring pattern 2 of the third layer.
8 is formed (FIG. 1 (e)). The insulating layer 26 is the insulating layer 1.
6 The upper surface is formed by spin coating with polyimide. At this time, the surface position of the insulating layer 26 and the height of the columnar body 20 are made to coincide with each other. The conductor metal film 22 on the upper surface of the columnar body 20 is formed by sputtering the conductor metal.
And the wiring pattern 28 of the third layer are connected, and the wiring pattern 24 of the second layer and the wiring pattern 28 of the third layer are electrically connected. Thus, the wiring pattern 12 of the first layer, the wiring pattern 24 of the second layer, and the wiring pattern 28 of the third layer
Are electrically connected to each other through the conduction hole 18 portion and the columnar body 20 portion.

Although the above-mentioned embodiment describes an example in which three layers of wiring patterns are provided, wiring patterns can be continuously formed on the wiring pattern 28 of the third layer by a similar method. In this way, a multilayer circuit board having a multilayer wiring pattern can be obtained. In the present embodiment, as described above, when forming the wiring pattern 24 of the second layer, the conductive portion connected to the wiring pattern 12 of the lower layer and the conductive portion connected to the wiring pattern 28 of the upper layer are simultaneously formed. It is possible to manufacture more efficiently than the method of stacking and forming from the lower layer in order. In particular, by using the columnar body, the thickness of the columnar body can be utilized, and even if the interlayer distance is large, it is possible to easily establish conduction.

Although the wiring patterns may be stacked by forming the conductive holes and the pillars in combination as in the above example, a method of simply forming the pillars and sequentially stacking the wiring patterns may also be used. can do. FIG. 2 shows a method of forming a wiring pattern in multiple layers using a columnar body. 2A, when the columnar body 30 is formed on the supporting substrate 10 in the same manner as the above example, a conductor metal is sputtered on the columnar body 30 to form a conductor metal film 32 and a pattern is formed. A wiring pattern 34 is formed (FIG. 2 (b)). Next, the insulating layer 36 is formed to the same thickness as the columnar body 30 (FIG. 2C), and the columnar body 30 is further formed on the insulating layer 36 (FIG. 2D). Then, the insulating layer 36
A conductive metal is sputtered on the columnar body 30 to form the second layer wiring pattern 38.

The wiring pattern 34 of the first layer and the wiring pattern 38 of the second layer are electrically connected by the conductor metal film 32 provided on the columnar body 30 to electrically connect the wiring patterns. Thus, the multilayer circuit board can be formed by continuing the method of providing the insulating layer and the columnar body and sputtering the conductive metal. In this method, since the wiring patterns are electrically connected via the columnar body 30, it is possible to make a reliable electrical connection even when the interlayer distance is considerably large as described above. . Further, by forming an insulating layer having the same thickness as the columnar body 30 and stacking the insulating layers, the film thickness of each layer becomes uniform, the flatness of the wiring pattern becomes good, and a multilayer circuit board having excellent electrical characteristics and the like is obtained. There is a feature that you can

FIG. 3 shows a method for forming a wiring pattern in multiple layers by etching conductive holes in an insulating layer. Figure 3 (a)
Forms a first layer wiring pattern 40 on the support base 10,
This is a state in which the insulating layer 42 is formed. Here, in order to form a conductive portion between the wiring patterns, the insulating layer 42 is etched to form a conductive hole 44 (FIG. 3B), and a conductive metal is further sputtered and a second layer wiring pattern 46 is formed. Then, a conductor metal film 48 is formed in the conduction hole 44 (see FIG. 3).
(c)). By the conductor metal film 48 in the conduction hole 44, the first
The wiring pattern 40 of the layer and the wiring pattern 46 of the second layer are electrically connected. Next, as shown in FIG. 3D, the insulating layer 50 is formed on the second-layer wiring pattern 46. Then, in order to connect the wiring pattern 46 of the second layer and the wiring pattern formed on the surface of the insulating layer 50, a conductive hole 52 is formed in the insulating layer 50, and the formation of a conductive portion with the upper layer is performed (FIG. 3).
(e)).

In this way, a multi-layer circuit board in which a conductive hole is formed in the insulating layer and a conductive metal is sputtered to form a multi-layered wiring pattern and the wiring patterns are electrically connected to each other is obtained. can get. In addition,
In the case of this method, since it is necessary to form the conductive holes by etching and it is necessary to form the conductive metal film on the inner bottom surface and the inner wall of the conductive holes by sputtering, the insulating layers 42 and 50 should be thinner. Of course, it is suitable when the wiring patterns are formed close to each other to form a multilayer structure.

The method of manufacturing a multi-layer circuit board by forming a thin film by the method of the present invention has been described above. The method of establishing continuity between wiring patterns by the above-mentioned conduction hole or columnar conductive portion is a multi-layer circuit board of various patterns. The number of layers of the wiring pattern and the like can be appropriately set. Further, in the above example, the example in which the ceramic substrate is used as the support substrate 10 is described, but the support substrate is used as a support when forming the wiring patterns in multiple layers, and various usage forms are possible. For example, T
In AB (Tape Automated Bonding) products, etc., a wiring pattern is formed on the surface of an insulating film such as polyimide.
It can be similarly applied to the case where wiring patterns are formed on the front and back surfaces of the insulating film and the front and back surfaces are connected by a conductive portion, or when the wiring pattern is formed in multiple layers on one surface of the insulating film. .

[0018]

As described above, according to the multilayer circuit board and the method of manufacturing the same of the present invention, it is possible to improve the reliability of the electrical continuity of the conductive portion connecting the wiring patterns. Further, by forming the conductive hole and the columnar body in the insulating layer, and forming the conductive metal on the inner bottom surface and the inner wall of the insulating layer and the columnar body and the conductive hole, it is possible to easily form the conductive portion between the wiring patterns, which is efficient. It is possible to produce a multi-layer circuit board, which is very effective.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a method for manufacturing a multilayer circuit board.

FIG. 2 is an explanatory view showing another embodiment of the method for manufacturing a multilayer circuit board.

FIG. 3 is an explanatory view showing still another embodiment of the method for manufacturing a multilayer circuit board.

FIG. 4 is an explanatory diagram showing an example of forming a conventional wiring pattern on a multilayer circuit board.

[Explanation of symbols]

 3 Insulating layer 4 Wiring pattern 5 Conducting part 10 Support substrate 12, 34, 40 First layer wiring pattern 16, 26, 36, 42, 50 Insulating layer 18, 44 Conducting hole 20, 30 Columnar body 22, 32, 48 Sputter Films 24, 38, 46 Second layer wiring pattern 28 Third layer wiring pattern

Claims (3)

[Claims] 1. A multi-layer circuit board in which wiring patterns are formed in multiple layers with an electrically insulating layer interposed between the layers, and a conductive portion electrically connecting the wiring patterns is provided between the layers, wherein the conductive portion is an insulating layer. A conductor metal film is formed on the surface of an insulator standing upright in a columnar shape, and the conductor metal film on the top of the columnar body of the conducting portion is connected to one wiring pattern, and the outer wall base of the columnar body is formed. A multilayer circuit board, wherein the conductor metal film is connected to the other wiring pattern. 2. In a multi-layer circuit board, wherein a wiring pattern is formed in multiple layers with an electrically insulating layer interposed between the layers, and a conductive portion electrically connecting the wiring patterns is provided between the layers, the conductive portions face each other. An insulating layer interposed between layers of the wiring pattern is formed in a conductive hole that connects in the thickness direction, and an inner bottom surface of the conductive hole facing the wiring pattern and an inner wall of the conductive hole are covered with a conductive metal film. Formed, the conductor metal film on the inner bottom surface is connected to the one wiring pattern, the conductor metal film provided on the inner wall is connected to the other wiring pattern, and the inside of the conduction hole is filled with the insulating layer. A multilayer circuit board characterized by the above. 3. A method for manufacturing a multilayer circuit board, wherein a wiring pattern is formed in multiple layers with an electrically insulating layer interposed between the layers, and a conductive portion electrically connecting the wiring patterns is provided between the layers. An insulating layer is formed on the pattern, the insulating layer is etched to form a conductive hole reaching the wiring pattern, and a columnar body made of an insulator is erected on the insulating layer, and the surface of the insulating layer and the columnar body is formed. And forming a conductor metal on the inner bottom surface and the inner wall of the conduction hole to form a conductor metal film on the inner bottom surface, the inner wall and the top of the columnar body, and the outer wall, and forming a second wiring pattern on the insulating layer, , Further forming an insulating layer on the insulating layer, and forming a third wiring pattern on the insulating layer with a conductive metal, thereby forming a multilayer wiring pattern with the conductive hole and the columnar body portion as a conductive portion. Method of manufacturing a multilayer circuit board, characterized in that formed.