JPH0923064A - Manufacture of printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method wherein a post can be formed without using nonelectrolytic plating, when a printed circuit board in which a lower layer conductor circuit is electrically connected with an upper layer conductor layer by using the post. SOLUTION: Before a metal film 13 for forming a lower layer conductor circuit is patterned, a post 17 is formed on the metal film 13 by electrolytic plating using the metal film 13 as a feeding body. A mask 21 for covering the surface of a part of the metal film 13 which part is to be left as a lower conductor circuit and for covering the post 17 is formed on the metal film 13 on which the post 17 has been formed, by electrolytic plating. By etching a part of the metal film 13 which part is not covered with the mask 21, a lower layer conductor circuit 13a is formed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In the case of manufacturing a printed circuit board having a structure in which a lower layer conductor circuit and an upper layer conductor circuit are electrically connected by posts (metal columns), the following procedure is generally taken. First, a copper thin film as a metal film for forming the lower conductor circuit is patterned into the shape of the lower conductor circuit. Here, this copper thin film is formed on the interlayer insulating film when it is formed on the insulating substrate or when it is the second layer or more of the printed circuit board having three layers or more. Next, on this copper thin film, a power supply film to be used for electrolytic plating which will be performed later for forming a post is formed by electroless plating. Next, a mask is formed on the power feeding film to cover a portion of the power feeding film other than the portion where the post is to be formed. Next, electrolytic plating for forming the posts is performed to form the desired posts. Next, the mask is removed, and then the part of the power supply film not covered with the posts is removed. Next, a resin for forming an interlayer insulating film is applied to the entire surface of this sample and further cured. The cured resin is polished until the surface of the post is exposed to form an interlayer insulating film. A metal film for forming an upper-layer conductor circuit (this corresponds to a metal film for forming a lower-layer conductor circuit in the case of further forming multiple layers) is formed on the interlayer insulating film, and then this metal film is formed into a desired film. The upper conductor circuit is obtained by patterning into a shape.

[0003]

However, in the method of manufacturing the printed circuit board described above, it is necessary to previously form the power supply film used in the electroplating for forming the posts by electroless plating. Electroless plating requires many steps such as a pretreatment step and a plating step, and it is difficult to control the chemical liquid. Further, the cost is high. The smaller the amount, the better. In addition, the power supply member formed above is to be removed except for the portion immediately below the post after the electroplating for forming the post is completed. During this removal, the post and the lower layer conductor circuit should be particularly covered with an etching mask or the like. I don't. This is because the thickness of the power feeding film itself is considerably smaller than the thickness of the posts and the lower layer conductor circuit, and therefore it is considered that the power feeding film can be selectively removed without damaging the posts and the lower layer conductor circuit. However, for example, the etching solution may damage the posts and the lower conductor circuit. In addition, when the film formed by electroless plating (generally copper) itself can be removed in the removal of this power supply film, the palladium applied to the base during the pretreatment of electroless plating cannot be completely removed and remains. In some cases, therefore, the insulation resistance required due to the characteristics of the printed circuit board cannot be ensured due to this.

[0004]

Therefore, according to the present invention, in manufacturing a printed circuit board having a structure in which a lower layer conductor circuit and an upper layer conductor circuit are electrically connected by a post, a metal for forming a lower layer conductor circuit is manufactured. Posts are formed on the film before patterning the metal film into the shape of the lower conductor circuit. Then, on the metal film on which the post has been formed, a mask for covering the partial surface to be left as a lower layer conductive circuit of the metal film and a mask for covering the post, and a means for etching the metal film. A mask made of a material having resistance is formed, and then a portion of the metal film which is not covered with the mask is etched to form a lower conductor circuit.

Here, the mask can be formed by any suitable method. For example, a method using electrolytic plating, or
A method of patterning a dry film resist, for example, an ultraviolet photosensitive dry film resist so that it remains in the mask formation portion, or a film is formed on the metal film on which posts have been formed with a coating solution containing a suitable organic material. It can be formed by a method of forming the film and patterning the film into the mask shape. However, among these methods, the method using electroplating is better than other methods for both the surface of the part to be left as the lower conductor circuit of the metal film for forming the lower conductor circuit and the post because the post itself is a metal compared to other methods. It is particularly preferable as a method of forming a mask, since it can be coated on.

[0006]

According to the structure of the present invention, the post is formed on the metal film for forming the lower conductor circuit before forming the lower conductor circuit. This is because an insulating mask that exposes only the surface of the metal film for forming the lower conductor thin film, where the post is to be formed, is formed on the metal film, and the metal film itself for forming the lower conductor thin film is used as a power supply film. It means that the post can be formed by electrolytic plating. Therefore, the step of electroless plating, which has been conventionally necessary for forming the power supply film for forming the posts, can be omitted in the present invention.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. However, the drawings used for the description schematically show the dimensions, shapes, and arrangement relationships of the respective constituents to the extent that the present invention can be understood. In each of the drawings used for description, the same components are denoted by the same reference numerals, and overlapping description may be omitted.

[0008] 1. First Embodiment First, a first embodiment of the present invention will be described with reference to the process drawings shown in FIGS.

A structure is prepared in which, for example, a copper thin film is formed as a metal film 13 for forming a lower conductor circuit on an insulating base 11 (FIG. 1A). In addition, this structure is
If the wiring structure to be formed is a wiring structure composed of the lowermost conductor circuit and the second conductor circuit of the printed circuit board, typically an insulating substrate such as a glass epoxy substrate and the like In the case where the wiring structure to be formed from a copper thin film formed by, for example, a hot pressing method is a wiring structure of a second or more layers in a printed circuit board having a three or more layers structure, Typically, it is a structure including an interlayer insulating film and a metal film for forming a conductor circuit formed thereon.

Next, according to the present invention, a post is formed on the metal film 13 for forming the lower conductor circuit before patterning the metal film 13 into the shape of the lower conductor circuit. In this embodiment, this is performed in the following procedure.

First, a metal film 1 for forming a lower conductor circuit
A mask 15 having an opening 15a for exposing a portion of the metal film 13 where a post is to be formed (this is referred to as a "post plating mask 15") is formed on the metal layer 3 (FIG. 1).
(B)). The post plating mask 15 is, for example,
It can be formed by forming a UV-sensitive resist film (not shown) on the metal film 13 for forming the lower conductor circuit, selectively exposing the film, and then developing.

Next, electrolytic plating such as copper plating is performed using the metal film 13 for forming the lower conductor circuit as a power supply film.
In this electroplating, the post 17 is formed by plating the portion of the metal film 13 for forming the lower conductor circuit, which is not covered with the plating mask 15.
(C)). Then, the post plating mask 15 is removed (FIG. 1D). Conventionally, it was necessary to form a dedicated power feeding film by electroless plating before forming the posts, but it is understood that this can be eliminated in the present invention.

Next, on the metal film 13 for forming the lower layer conductor on which the post 17 has been formed, a mask for covering the partial surface to be left as the lower layer conductor circuit of the metal film 13 and the post 17 is formed. A mask made of a material resistant to the means for etching the film 13 (hereinafter
It is also referred to as a “mask for forming a lower conductor circuit and the like”. ) Is formed. In this embodiment, this is formed by the electrolytic plating method as follows.

First, an ultraviolet-sensitive resist layer 19 is formed on the metal film 13 for forming the lower conductor after the formation of the posts 17 (FIG. 2A). Then, the resist layer 19 is exposed and developed so that a part of the resist layer 19 which is formed on the mask formation planned region for forming the lower conductor circuit etc. of the metal film 13 is removed. Then
A resist pattern 19a is obtained (FIG. 2 (B)).

Next, electrolytic plating is performed using the metal film 13 for forming the lower conductor circuit as a power supply film. At this time, a material having resistance to the means for etching the metal film 13 is plated. In this case, since an etching solution having a basic composition of NH ₄ OH and NH ₄ Cl is used as the etching means as described later, electrolytic solder plating is performed as a material that can withstand this. In this electrolytic plating, the post 17 and the portion of the metal film 13 for forming the lower conductor circuit which is not covered with the resist pattern 19a are plated, so that the lower conductor circuit forming mask 21 made of solder is formed. (Hereinafter, it may be abbreviated as the mask 21.) can be formed (FIG. 2C). Note that it is preferable to form the mask 21 by electrolytic plating, because the periphery of the post 17 is also covered with the mask 21 satisfactorily. In addition, the metal film 13
If the mask 21 is made of solder when is made of copper, only the solder can be selectively removed by an appropriate stripping solution as described later, so it is suitable when the mask 21 is not left behind. Is. After that, the resist pattern 19a is removed (FIG. 3A).

Next, this sample is used as an etching solution that dissolves (etches) the copper thin film that is the metal film 13 for forming the lower conductor circuit and does not dissolve the solder that constitutes the mask 21 for forming the lower conductor circuit. Here, the metal film 13 for forming the lower conductor circuit is formed by immersing in an etching solution containing NH ₄ OH and NH ₄ Cl as a basic composition, or by spraying the etching solution onto the sample with a sprayer or the like. Then, the portion not covered with the mask 21 is removed. As a result, the lower conductor circuit 13a can be formed (FIG. 3 (B)).

After the formation of the lower conductor circuit 13a, an etching solution for dissolving the solder forming the mask 21 without dissolving the copper forming the lower conductor circuit 13a, for example, an electro bright solder stripper 880 ( The mask 21 is removed by a solder stripping solution manufactured by Ebara Densan Co., Ltd. (FIG. 3C).

Next, a resin layer 23 for forming an interlayer insulating film is formed on this sample and further cured (FIG. 4).
(A)). Any suitable resin can be used as the resin forming the resin layer. The resin layer can be formed by any suitable method depending on the resin. For example, when the resin is liquid, it can be performed by any suitable method such as screen printing, curtain coating, or spray coating. When the resin is sheet-shaped, it can be bonded by pressure.

Next, the resin layer 23 is polished until the head of the post 17 is exposed. As a result, the interlayer insulating film 23a is obtained (FIG. 4 (B)).

Next, a copper thin film, for example, is formed as a metal film 25 for forming the upper conductor circuit on the interlayer insulating film 23a by, for example, electroless plating and electrolytic plating (FIG. 4).
(C)).

Next, the metal film 2 for forming the upper conductor circuit is formed.
An upper layer conductor circuit forming mask 27 made of, for example, a resist pattern is formed on the surface 5 (FIG. 5A). Next, a portion of the metal film 25 for forming the upper conductor circuit which is not covered with the mask 27 is etched to form an upper conductor circuit 25a (FIG. 5B). After that, the mask 27 is removed (FIG. 5C). Thereby, the lower conductor circuit 13a,
A printed circuit board having a structure having an upper conductor circuit 25a as a build-up conductor layer and electrically connecting these conductor circuits with a post 17 is obtained.

In the first embodiment, the example in which the lower layer conductor circuit forming mask 21 is formed by electrolytic solder plating has been described, but the material for electrolytic plating is not limited to this. Any other metal may be used as long as it is a metal resistant to the chemical used when etching the metal film 13 for forming the lower conductor circuit. For example, tin, gold, rhodium, silver, nickel, paradium, etc. can be used as the mask forming material. Further, in the above-described embodiment, the example in which the mask 21 is removed after the lower layer conductor circuit 13a is formed is described, but in the case where there is no hindrance to the subsequent steps and the long-term stability of the printed circuit board is not impaired. For example, the mask 21 does not necessarily have to be removed and may be left. For example, gold and rhodium are chemically and physically stable materials, and therefore, when the mask 21 is formed using this, it is considered to be one of the examples in which the mask need not be removed.

2. Second Embodiment In the first embodiment described above, the mask 2 for forming the lower conductor circuit and the like is used.
The example in which 1 is formed by electrolytic plating has been described. But,
The mask 21 may be formed using a dry film resist. This second embodiment is such an example. This explanation will be given mainly with reference to the process diagrams shown by the sectional views in FIGS.

First, in the first embodiment, as shown in FIG.
The post 17 is formed on the metal film 13 for forming the lower conductor circuit according to the procedure described with reference to FIG.
(A)).

Next, an ultraviolet-sensitive dry film 31 as a dry film resist is pressure-bonded to the surface of the sample on which the posts 17 are formed (FIG. 6 (B)). This dry film resist 31 can substantially bury the post 17,
Moreover, it is preferable to have a thickness that can substantially protect the posts when patterning the metal film 13 for forming the lower conductor circuit.

Next, this dry film resist 31
Is subjected to patterning, that is, exposure and development, so that the metal film 31 for forming the lower layer conductor circuit is left on the surface of the portion to be left as the lower layer conductor circuit and on the post 17. As a result, the lower layer conductor circuit forming mask 31a (hereinafter referred to as the mask 3) formed of the dry film resist is formed.
Also referred to as 1a. ) Is obtained (FIG. 6 (C)).

Next, the metal film 13 for forming the lower conductor circuit
The portion not covered with the mask 31a is removed by a suitable etching liquid to obtain the lower conductor circuit 13a (FIG. 7A). The etching solution used at this time is the metal film 1.
Any mask can be used as long as it can remove 3 and the mask 31a made of resist has resistance. In the case of the first embodiment, since the mask 21 was made of solder, it was not possible to use an etching solution such as iron chloride or hydrochloric acid, but in the second embodiment such an etching solution can also be used. Becomes Therefore, in the case of the second embodiment, as compared with the first embodiment (an example in which the mask 21 is formed by electrolytic plating), various kinds of etching liquids can be used for forming the lower layer conductor circuit. Benefits are obtained. That is, the degree of freedom in selecting the etching liquid for forming the lower conductor circuit is improved.

Next, the mask 31a is removed (see FIG. 7).
(B)). After that, the interlayer insulating film and the upper conductor circuit may be formed by the procedure described with reference to FIGS. 4 and 5 in the first embodiment.

3. Third Embodiment In each of the first and second embodiments described above, an example of manufacturing a printed circuit board having one buildup conductor layer has been described.
However, the invention according to this application can of course be applied to the manufacture of a printed circuit board having two or more build-up conductor layers. As an example thereof, in the third embodiment, an example of manufacturing a printed circuit board having two buildup conductor layers by the manufacturing method of the present invention will be described. This explanation is shown in FIG.
~ This is performed with reference to the process diagram shown in the sectional view of FIG.

First, in the first embodiment, as shown in FIG.
According to the procedure described with reference to FIG.
7. The steps of forming the lower conductor circuit 13a, the interlayer insulating film 23a, and the metal film for forming the upper conductor circuit are sequentially performed. However, the metal film for forming the upper conductor circuit formed in this case is different from the metal film 41 for forming the lower conductor circuit (hereinafter,
It may be abbreviated as the metal film 41. )) (FIG. 8 (A)).

Next, on the metal film 41, a mask 15 having an opening 15a for exposing a portion where a post is to be formed is formed by using, for example, an ultraviolet-sensitive resist (FIG. 8).
(B)).

Next, using the metal film 41 as a power supply film, electrolytic plating such as copper plating is performed to form the post 17 (FIG. 9A). Then, the post plating mask 15 is removed (FIG. 9B).

Next, the metal film 4 on which the post 17 has been formed
A mask for covering the surface of the portion of the metal film 41 to be left as a conductor circuit and the post 17 on the substrate 1 and made of a material having resistance to the means for etching the metal film 13 (hereinafter, referred to as “mask”). Also referred to as a “mask for forming an intermediate conductor circuit, etc.”). This is formed as follows in this embodiment.

First, the metal film 4 on which the post 17 has been formed
On top of this, a layer of UV-sensitive resist (not shown) is formed. Next, the resist layer is exposed and developed so that a part of the resist layer, which is formed on the mask formation planned region for forming the intermediate conductor circuit etc. of the metal film 41, is removed, A resist pattern 43 is obtained (FIG. 10 (A)).

Next, electrolytic plating is performed using the metal film 41 as a power supply film. At this time, a material having resistance to the means for etching the metal film 41 is plated. Here, electrolytic solder plating is performed as in the first embodiment. In this electrolytic plating, the post 17 and the portion of the metal film 41 that is not covered with the resist pattern 43 are plated, so that an intermediate conductor circuit forming mask 45 (hereinafter referred to as a mask 45) made of solder is formed. (Sometimes abbreviated) can be formed (FIG. 10B). After that, the resist pattern 43 is removed (FIG. 11A). Of course, the material for forming the mask 45 is not limited to solder, and other materials such as those exemplified in the first embodiment can also be used.

Next, this sample is treated, for example, with NH ₄ OH and N _4.
The portion of the metal film 41 which is not covered with the mask 45 is removed by immersing it in an etching solution containing H ₄ Cl as a basic composition, or by spraying the etching solution onto the sample with a spray device or the like. To do. Thereby, the conductor circuit 41a (hereinafter, referred to as "intermediate conductor circuit 41a").
Can be formed (FIG. 11B).

After formation of the intermediate conductor circuit 41a, for example, an electro bright solder stripper 880 is formed.
(The product name of the solder stripper manufactured by Ebara Densan Co., Ltd.)
The mask 45 is removed (FIG. 12A).

Next, an arbitrary suitable resin layer 23 for forming an interlayer insulating film is formed on this sample and further cured (FIG. 12B). The resin layer 23 is polished until the head of the post 17 is exposed. Thereby, the interlayer insulating film 23
a is obtained (FIG. 13 (A)).

Next, a copper thin film, for example, is formed as a metal film 25 for forming the upper conductor circuit on the interlayer insulating film 23a by, for example, electroless plating and electrolytic plating (FIG. 13).
(B)). On the metal film 25 for forming the upper conductor circuit,
For example, an upper layer conductor circuit forming mask 27 having a resist pattern is formed (FIG. 14A). Then, the portion of the metal film 25 for forming the upper conductor circuit which is not covered with the mask 27 is etched to form the upper conductor circuit 25a, and then the mask 27 is removed (FIG. 14B).
As a result, a printed circuit board having a structure in which the lower-layer conductor circuit 13a and the two-layer conductor circuits 41a and 25a as build-up conductor layers are electrically connected to each other by the post 17 Is obtained.

In the third embodiment, it can be understood that the present invention also has the following effects. In the case of a printed circuit board having two or more build-up conductor layers, an upper layer conductor circuit forming layer is formed for the purpose of improving the adhesion between the interlayer insulating film and the upper layer conductor circuit forming metal film formed thereon. Before the metal film is formed, the surface of the interlayer insulating film is mechanically polished by a buff and roughened by a chemical solution. In such a roughened surface, deep in the recess, palladium or the like used in the pretreatment prior to the electroless plating step in forming the metal film for forming the upper conductor circuit, or copper deposited during the electroless plating It comes to be adsorbed. However, it is almost impossible to remove the palladium and copper adsorbed deep in the recess in this way by a short-time chemical solution treatment for removing only the power supply film, which has been done in the prior art. On the other hand, according to the method of the present invention, the unnecessary portions of the metal film for forming the posts and the conductor circuit are removed while the necessary portions of the metal film for forming the conductor circuit are covered with the mask 45 for forming the intermediate conductor circuit as described above. Processing is performed (see FIGS. 11A and 11B).
Therefore, even if the chemical treatment is performed for a relatively long time so as to remove the palladium or copper adsorbed deeply in the concave portion of the roughened surface of the interlayer insulating film, the post and the necessary portion of the metal film for forming the conductor circuit are damaged. It will not be done.

Although some embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above-described embodiment, an example has been described in which the lower conductor circuit forming masks 21 and 31a and the intermediate conductor circuit forming mask 45 are formed by electrolytic plating or dry film resist. However, these masks are formed by, for example, a method of forming a film on the metal film for forming the lower conductor circuit for which the post has been formed with a coating solution containing a suitable organic material, and patterning this film into the mask shape. May be. As a specific example thereof, for example, a liquid material or solution of alkylbenzimidazole is formed on a metal film for forming a lower conductor circuit on which a post has been formed by a suitable method such as a dipping method, and then patterned. Mask 2
Examples of the method include a method of obtaining 1, 31a, and 45, or a method of forming a liquid ultraviolet photosensitive resist and patterning the resist.

[0042]

As is apparent from the above description, according to the present invention, in manufacturing a so-called post connection type printed circuit board having a structure in which the lower layer conductor circuit and the upper layer conductor circuit are electrically connected by posts, Posts are formed on the metal film for forming the lower conductor circuit before patterning the metal film into the shape of the lower conductor circuit. Then, on the metal film on which the posts have been formed, a mask for covering the partial surface to be left as the lower layer conductor circuit of the metal film and the post, which is resistant to the means for etching the metal film. A mask made of a material having the above is formed, and then a portion of the metal film which is not covered with the mask is etched to form a lower conductor circuit. Therefore, the post can be formed by electrolytic plating using the metal film for forming the lower conductor circuit as the power supply film. Therefore,
In the present invention, the electroless plating step which has been conventionally required for forming the power supply film for forming the post can be omitted, so that the number of electroless plating steps itself in the printed circuit board manufacturing process can be reduced. In addition, the electroless plating required to form the power supply film for forming the posts can be omitted, so that the damage to the post due to the removal of the power supply film, the damage to the lower layer conductor circuit, and the insulation resistance due to palladium. In the first place, there is no decrease.

[Brief description of drawings]

FIG. 1 is a process diagram for explaining a first embodiment.

FIG. 2 is a process diagram following FIG. 1 for explaining the first embodiment.

FIG. 3 is a process diagram following FIG. 2 for explaining the first embodiment.

FIG. 4 is a process chart following FIG. 3 for explaining the first embodiment.

FIG. 5 is a process chart following FIG. 4 for explaining the first embodiment.

FIG. 6 is a main part process chart for use in explaining the second embodiment.

FIG. 7 is a main part process chart for explaining the second embodiment, which is subsequent to FIG. 6;

FIG. 8 is a process drawing for explaining the third embodiment.

FIG. 9 is a process diagram following FIG. 8 for explaining the third embodiment.

FIG. 10 is a process chart following FIG. 9 for explaining the third embodiment.

FIG. 11 is a process chart following FIG. 10 for explaining the third embodiment.

FIG. 12 is a process chart following FIG. 11 for explaining the third embodiment.

FIG. 13 is a process chart following FIG. 12 for explaining the third embodiment.

FIG. 14 is a process diagram which follows the process of FIG. 13 for explaining the third embodiment.

[Explanation of symbols]

11: Insulating Underlayer 13: Metal Film for Forming Lower Layer Conductor Circuit 13a: Lower Layer Conductor Circuit 15: Post Plating Mask 15a: Opening 19: Resist Layer 19a: Resist Pattern 21: Lower Layer Conductor Circuit Forming Mask ( 23: Resin layer 23a: Interlayer insulating film 25: Metal film for forming upper conductor circuit 25a: Upper conductor circuit 27: Mask for forming upper conductor circuit 31: Ultraviolet sensitive dry film resist 31a: Lower conductor Mask for forming circuits, etc. (by dry film resist) 41: Metal film for forming lower layer conductor circuits on the third layer 41a: Intermediate conductor circuit 43: Resist pattern 45: Mask for forming intermediate conductor circuits, etc.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yutaka Karasuno 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Ho Ho Nakakugi 1-7-12 Toranomon, Minato-ku, Tokyo No. Oki Electric Industry Co., Ltd.

Claims (3)

[Claims] 1. When manufacturing a printed circuit board having a structure in which a lower layer conductor circuit and an upper layer conductor circuit are electrically connected to each other by posts, the metal film is formed on a metal film for forming the lower layer conductor circuit. A pattern for forming a post before patterning into a shape, and a mask for covering the partial surface to be left as a lower layer conductor circuit of the metal film and the post on the metal film on which the post has been formed. A mask made of a material having resistance to a means for etching the metal film is formed, and then a portion of the metal film not covered with the mask is etched to form a lower conductor circuit. Method of manufacturing printed circuit board. 2. The method for manufacturing a printed circuit board according to claim 1, wherein the mask is formed by electrolytic plating. 3. The method of manufacturing a printed circuit board according to claim 1, wherein the mask is formed by patterning a dry film resist so that the dry film resist remains in a corresponding portion. Method.