JP2002176255A - Method of manufacturing connecting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a connecting structure for materializing an interlayer connection or the like which is high in density of integration or productivity and is extremely low in connection resistance. SOLUTION: Nickel plating 3 is applied to the whole face of one side of a copper foil 1 (main conductor layer), tin plating 2 with a pattern is applied to its opposite side, and copper plating 5 (substratum conductor layer) is made on the surface of the nickel plating 3. With the tin plating 2 as a mask, the copper foil 1 is etched to make it into separated protuberant bodies 10, and with the protuberant bodies 1 as masks, the nickel plating 3 is etched. As a result, connecting material where most of the conductive path at a connection place is constituted of solid metal (copper foil 1 or the like) is obtained. Next, an adhesive layer 5 is made to pierce the protuberant body 10, and the tin plating 2 is applied with light etching. Then, an object to be connected is placed on the tin plating 2 and is pressed, whereby a connecting structure is obtained.

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 connection structure for connecting between layers in a wiring board or connecting a wiring board to a mounted component.

[0002]

2. Description of the Related Art Conventionally, in a wiring board, an interlayer connection structure for making electrical connection between conductor layers is formed at various places. Also, a connection structure between the wiring board and the mounted component is appropriately formed. As a method to realize these connection structures with high density and high productivity, "Development of high-density printed wiring board by new interlayer connection method" (Circuit Packaging Society of Japan Vo
l.11, No. 2, pp. 106-112 (1996)). Here, a technique of forming a conductive bump using a conductive paste by a printing technique is introduced as a connection method instead of an interlayer connection technique by a copper through-hole plating method.

[0003]

However, the connection structure manufactured by the above-mentioned conventional technique has the following problems. That is, in this technique, since the connection structure is basically formed using a conductive paste, the conductivity of the bumps forming the conductive path is not so high, and the connection resistance cannot be ignored. For this reason, there was concern about the reliability of the connection, and it was difficult to use for high current applications.

The present invention has been made to solve the above-mentioned problems of the conventional connection structure. That is, an object of the present invention is to provide a method of manufacturing a connection structure for realizing interlayer connection or the like having high integration density and high productivity and extremely low connection resistance.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, a method of manufacturing a connection structure according to the present invention comprises the steps of: forming a first plating layer having a material different from that of a main conductor layer in a pattern on one surface of the main conductor layer; Forming a second plating layer having a material different from that of the main conductor layer and the first plating layer on the entire other surface of the main conductor layer;
A base conductor layer made of a material different from that of the second plating layer is formed on the entire other surface of the second plating layer, and the main conductor layer is etched using the first plating layer as a mask to form discrete convex portions. After the surface of the first plating layer is etched after penetrating the resin layer through the protruding portion, an object to be connected is disposed on the surface on the first plating layer side, and the top of the protruding portion is interposed through the first plating layer. Thus, the connection structure is obtained by connecting the connection object and the base conductor layer by the convex portions.

Here, it is desirable that after the main conductor layer is etched, the second plating layer is etched using the main conductor layer as a mask, and the first plating layer is left at that time.

[0007] In the connection structure obtained by the manufacturing method of the present invention, the "convex portion" constitutes a connection conduction path. The protruding portion is a residue obtained by etching the “main conductor layer”. Therefore, by forming the main conductor layer with a metallic material such as copper foil, a connection structure having a much lower resistance than that containing an insulating component such as a paste can be obtained.
Further, the pattern mask formation by photolithography or the like only needs to be performed once at the time of forming the first plating layer, so that the productivity is high.

Further, in the manufacturing method of the present invention, the surface portion of the first plating layer is etched after the resin layer is made to penetrate the convex portion. Therefore, the resin remaining on the top of the convex portion (more precisely, on the first plating layer) after penetrating the resin layer is removed. Therefore, when the object to be connected is arranged on the surface on the first plating layer side, no resin is interposed between the first plating layer and the object to be connected. That is, there is almost no thing containing an insulating component in the conduction path of the connection. This results in a connection structure with a very low resistance.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings.

First, a starting state for manufacturing the connection structure according to the present embodiment will be described. The connection structure according to the present embodiment is manufactured using a copper foil having a thickness of about 100 μm as a starting material (FIG. 1). This copper foil 1 is a main conductor layer. First, the copper foil 1 is plated on both sides (FIG. 2). At that time, the upper surface in the figure (hereinafter, referred to as the upper surface) is a tin plating 2 with a pattern, and the lower surface in the figure (hereinafter, referred to as the upper surface).
The lower surface is referred to as nickel plating 3 on the entire surface. The thickness may be about 3 μm. The formation of the tin plating 2 with a pattern on the upper side may be performed by once plating the entire surface and performing pattern etching, or by forming a mask resist of a negative pattern in advance and forming plating only in a portion without the mask resist. May be.

Subsequently, an entire mask is formed on the upper surface. In this state, copper plating 5 having a thickness of about 20 μm is formed on the entire lower surface (FIG. 3). This copper plating 5 is a base conductor layer. In this state, the copper foil 1 (main conductor layer) and the copper plating 5
(Base conductor layer) and nickel plating 3 are located.

Next, the mask resist on the upper surface is entirely removed, and a mask on the entire surface is formed on the lower surface. In this state, etching is performed using an alkaline etching solution. Then, only the copper foil 1 as the main conductor layer is etched. At that time, the tin plating 2 functions as an etching mask. Therefore, only the portions of the copper foil 1 where there is no tin plating 2 are etched to form discrete convex bodies 10 (FIG. 4). At this time, since the metal plating (tin plating 2) acts as an etching mask, the adhesion to the copper foil 1 is stronger than that of a resin-based resist mask. For this reason, there is no separation due to the liquid pressure (spray pressure) during the etching. Therefore, the convex body 10 having a pattern faithful to the pattern of the tin plating 2 is reliably formed.

Subsequently, etching is performed with a nitric acid-based etchant (such as a solder stripper). At this time, since nickel is more easily etched than copper, the nickel plating 3 is also etched at the same time except for the portion covered by the convex body 10. In view of the relative etching rate, since the convex body 10 acts as an etching mask at this time, the copper plating 5 is exposed upward at a portion where there is no convex body 10 (FIG. 5). In this state, nickel plating 3
Exists only under the convex body 10. In this state, the upper tin plating 2 remains.

Next, an adhesive layer is combined. That is,
The adhesive layer is pressed from above each convex body 10 in the state of FIG. 5 so that the convex body 10 penetrates the adhesive layer 6 (FIG. 6). Here, as the adhesive layer 6, any of glass cloth prepreg, non-woven fabric prepreg, resin sheet and the like can be used. Alternatively, a liquid resin may be applied. In the state of FIG. 6, the tin plating 2 on the convex body 10
However, there is a face on the upper part of the adhesive layer 6. Further, the adhesive layer 6 remains on the tin plating 2. Thus, light etching is performed on the tin plating 2 located on the convex body 10 in the state of FIG. Then, by etching the surface portion of tin plating 2, adhesive layer 6 remaining on tin plating 2 is removed (FIG. 7). It should be noted that the etching of the tin plating 2 may be of such an extent that the surface of the tin plating 2 is melted. This is because it is sufficient that the adhesive layer 6 remaining on the tin plating 2 can be removed.

Subsequently, the copper foil 7 is combined with the one shown in FIG. 7 so that the top of each convex body 10 comes into contact with the copper foil 7 via the tin plating 2 (FIG. 8). Then, this is pressed to obtain the state shown in FIG. The pressing at this time is set to about 390 N / cm ² which is higher than the normal pressing pressure. This is because the top of each convex body 10 and the copper foil 7 are firmly adhered to each other. In the state of FIG. 9, each convex body 10 is made of tin plating 2
And copper foil 5 (base conductor layer) via nickel plating 3.
That is, each convex body 10 has an interlayer connection structure between the copper plating 5 (base layer conductor layer) and the copper foil 7 (upper layer). Thereafter, the copper plating 5 (base conductor layer) and the copper foil 7 (upper layer) may be appropriately patterned.

In this structure, the conductive path of the interlayer connection portion is formed by nickel plating 3, convex body 10, and tin plating 2 from below. The conductive path does not include a portion made of the conductive paste. Further, the adhesive layer 6 does not remain between the tin plating 2 and the copper foil 7. That is, most of them are made of solid metal. Therefore, its via resistance is extremely low. In addition, patterning for the configuration of interlayer connection requires only one mask resist for forming the tin plating 2 on the upper side in FIG. There is no complicated process such as via hole plating. Therefore, it is also excellent in productivity. This also contributes to achieving a high degree of integration. Further, the one in the state of FIG. 5 or the one in the state of FIG. 9 (the arrangement of the convex bodies 10 is standard) is stocked, and the subsequent process (copper plating 5 (lower layer)) is performed depending on the order. And patterning of the copper foil 7 (upper layer). Therefore,
The state shown in FIG. 5 can be referred to as a “connecting material”.

Next, a modified example will be described. As a modification of the above, not the interlayer connection in the wiring board, but the wiring board and I
An example of application to connection with a mounting component such as a C chip is given. That is, as shown in FIG. 10, the mounting component 9 is combined with the component in the state of FIG. Then, this is pressed so that the top of each convex body 10 and the pad of the mounting component 9 are in close contact with each other. The press at that time is, as described above, 3 presses higher than the normal press pressure.
It is about 90 N / cm ² . In the state after pressing, each convex body 10 is firmly adhered to the pad of the mounting component 9 via the tin plating 2 and is in contact with the copper plating 5 (base conductor layer) via the nickel plating 3. are doing. That is, each convex body 10 forms an interconnection structure between the copper plating 5 (base conductor layer) and the mounting component 9. Thereafter, the copper plating 5 (base conductor layer) may be appropriately patterned.

As described in detail above, in the present embodiment, nickel plating 3 is formed on one entire surface of copper foil 1 (main conductor layer) as a starting material, and tin plating with a pattern is formed on the opposite surface. 2 and nickel plating 3
Is formed with copper plating 5 (base conductor layer). Then, the copper foil 1 is etched using the tin plating 2 as an etching mask to form a discrete convex body 10,
Nickel plating 3 using convex body 10 as an etching mask
Is to be etched. As a result, a connection material is obtained in which most of the conductive paths at the connection points are made of a solid metal (such as the copper foil 1). Next, the adhesive layer 6 is penetrated through the convex body 10, and the surface of the tin plating 2 is lightly etched. Then, by pressing the upper layer (copper foil 7) or the mounting component 9,
Connection structure has been obtained. Therefore, the adhesive layer 6 does not remain on the upper layer (copper foil 7) or the tin plating 2 that directly contacts the mounted component 9. That is, the conduction path contains almost no insulating component. Thus, a method of manufacturing a connection structure having extremely low resistance at the conductive portion and having excellent integration and productivity has been realized.

The present embodiment is merely an example, and does not limit the present invention. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, in the present embodiment, the main conductor layer (copper foil 1, convex body 10) and the base conductor layer (copper foil 5) are made of copper, the pattern plating is made of tin, and the entire plating is made of nickel. However, the combination of the metal types of these parts may be different. However, it is a condition that they can be appropriately formed by plating and that they can be selectively etched. As an example, use of solder plating instead of tin plating 2 can be cited.

[0020]

As is apparent from the above description, according to the present invention, there is provided a method of manufacturing a connection structure for realizing an interlayer connection having a high integration density and a high productivity and a very low connection resistance. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a copper foil as a starting material for manufacturing a connection structure according to an embodiment.

FIG. 2 is a cross-sectional view showing a state where pattern tin plating and nickel plating are applied to the entire surface of the copper foil of FIG. 1;

FIG. 3 is a cross-sectional view showing a state where the entire lower surface in the state of FIG. 2 is plated with copper;

FIG. 4 is a cross-sectional view showing a state in which copper foil is etched to form discrete convex bodies in the state of FIG. 3;

5 is a cross-sectional view showing a state where an exposed portion of the entire surface nickel plating in the state of FIG. 4 is etched.

FIG. 6 is a sectional view showing a state where an adhesive layer is combined with the state of FIG. 5;

7 is a cross-sectional view showing a state in which tin plating located on the convex body in the state of FIG. 6 is etched.

8 is a cross-sectional view showing a state where a copper foil is combined with the state shown in FIG. 7;

9 is a cross-sectional view showing a state in which the structure shown in FIG. 8 is pressed to form an interlayer connection structure.

FIG. 10 is a cross-sectional view showing a situation where mounting components are combined with the state of FIG. 7;

[Explanation of symbols]

 Reference Signs List 1 copper foil (main conductor layer) 2 tin plating (first plating layer) 3 nickel plating (second plating layer) 4 gold plating (first plating layer) 5 copper plating (base conductor layer) 7 copper foil (connection object) 9) mounted component (connected object) 10 convex body

Claims (2)

[Claims] A first plating layer having a material different from that of the main conductor layer is formed in a pattern on one surface of the main conductor layer;
Forming a second plating layer having a different material from the plating layer; forming a base conductor layer having a different material from the second plating layer on the entire other surface of the second plating layer; The main conductor layer is etched to form discrete convex portions, and after the resin layer is penetrated through the convex portions, the surface portion of the first plating layer is etched, and then the surface on the first plating layer side is formed. The object to be connected is arranged so that the top of the convex portion is in contact with the object to be connected via the first plating layer, and the object and the base conductor layer are connected by the convex portion. A method for manufacturing a connection structure, comprising: 2. The manufacturing method according to claim 1, wherein the second plating layer is etched using the main conductor layer as a mask after the main conductor layer is etched, and the first plating layer is left at that time. The manufacturing method characterized by the above-mentioned.