JP2002176257A - 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 the nickel plating 3 is etched together with the nickel plating 2 with the protuberant bodies 10 as masks. As a result, connecting material is obtained where most of the conductive path at a connection place is constituted of solid metal (copper foil 1 or the like). Next, an adhesive layer 6 is made to pierce the protuberant body 10, and the top of the protuberant body 10 is light etched. Then, an object to be connected is placed on the top of the protuberant body 10 and is pressed to get a connecting structure.

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 different material from the main conductor layer on the entire other surface of the main conductor layer, and 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 plating layer is etched using the first plating layer as a mask to form discrete convex portions. The second plating layer is etched using the main conductor layer as a mask, and the first plating layer is removed. After penetrating the resin layer through the convex portion and etching the top portion of the convex portion, the object to be connected is arranged on the surface on the side where the first plating layer was, and the top portion of the convex portion contacts the object to be connected. To connect the object to be connected and the base conductor layer by the convex portion. Ri, thereby obtaining a connection structure.

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 top of the convex portion is etched after the resin layer penetrates the convex portion. For this reason, the resin remaining on the top of the convex portion after penetrating the resin layer is removed. Therefore, when the object to be connected is arranged on the surface on the side where the first plating layer was, no resin is interposed between the convex portion 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.

[0008]

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, nickel plating is applied to both surfaces of the copper foil 1 (FIG. 2). At this time, the nickel plating 2 on the upper surface (hereinafter, referred to as an upper surface) in the drawing is a pattern plating, and the nickel plating 3 on the lower surface (hereinafter, referred to as a lower surface) in the drawing is a whole plating. The thickness is about 3 μm. The formation of the nickel plating 2 with a pattern on the upper side may be performed by once plating the entire surface and then performing pattern etching, or by forming a mask resist of a negative pattern in advance and forming plating only in a portion having no mask resist. May be.

Next, 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 is formed on the entire 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 this time, the nickel plating 2 acts as an etching mask. Therefore, only the portions of the copper foil 1 where there is no nickel plating 2 are etched to form discrete convex bodies 10 (FIG. 4). At this time, since the metal plating (nickel 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 nickel plating 2 is reliably formed.

Subsequently, etching is performed with a nitric acid-based etchant (such as a solder stripper). Then, only nickel is etched without etching copper. At this time, all of the upper nickel plating 2 is melted, but the convex body 10 acts as an etching mask for the lower nickel plating 3. As a result, the copper plating 5 is exposed upward at locations where there is no convex body 10 (FIG. 5). In this state, the nickel plating 3 exists only under the convex body 10. In this state, the upper nickel plating 2 has disappeared.

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 top of the convex body 10 is exposed above the adhesive layer 6. Further, the adhesive layer 6 remains on the top of the convex body 10. Therefore, light etching is performed on the top of the convex body 10 in the state of FIG. Then, the adhesive layer 6 remaining on the top of the convex body 10 is removed by etching the top surface of the convex body 10 (FIG. 7). The etching of the top of the convex body 10 may be performed to such an extent that the surface of the top of the convex body 10 is melted. This is because it is sufficient that the adhesive layer 6 remaining on the convex body 10 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 is in contact with the copper foil 7 (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 in contact with the copper foil 7 and is in contact with the copper plating 5 (base conductor layer) via the 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, copper plating 5 (base conductor layer) and copper foil 7
(Upper layer) may be appropriately patterned.

In this structure, the conductive path of the interlayer connection portion is constituted by the nickel plating 3 and the convex body 10 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 convex body 10 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 nickel 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). Then, the thing of the state of FIG. 5 can be called a "connection material."

Next, a modification 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. 4, the mounting component 9 is combined with the mounting component 9 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 set to about 390 N / cm ^2, which is higher than the normal press pressure, as described above. In a state after pressing, each convex body 10 is mounted on the mounting component 9.
And is in contact with the copper plating 5 (base conductor layer) via the nickel plating 3.
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 above in detail, 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 nickel plating 3 with a pattern is formed on the opposite surface. 2 and a copper plating 5 (base conductor layer) is formed on the surface of the nickel plating 3. Then, the copper foil 1 is etched using the nickel plating 2 as an etching mask to form discrete convex bodies 10.
Then, the nickel plating 2 is etched and the nickel plating 3 is etched using the convex body 10 as an etching mask. As a result, most of the conductive paths at the connection points are solid metals (such as copper foil 1)
Has been obtained. Next, the convex body 1
0, the adhesive layer 6 is penetrated, and the top surface of the convex body 10 is lightly etched. Then, the connection structure is obtained by pressing the upper layer (copper foil 7) or the mounted component 9. Therefore, the adhesive layer 6 does not remain on the top layer (copper foil 7) or on the top of the convex body 10 that directly contacts the mounting 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, nickel plating 3
Is formed thicker, and the copper plating 5 is eliminated.
The nickel etching in FIG. 5 may be a quick etching to the extent that the upper nickel plating 2 is melted. In this case, the nickel plating 3 forms the main conductor layer.

[0019]

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 a pattern nickel plating and an entire surface nickel plating are applied to 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 sectional view showing a state where an exposed portion of the pattern nickel and 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;

FIG. 7 is a cross-sectional view showing a state in which the top of 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

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E351 AA01 BB01 BB23 BB24 BB30 BB33 BB35 BB49 CC06 DD04 DD06 DD19 GG01 GG09 5E317 AA24 BB01 BB11 BB12 BB15 CC31 CC52 CC60 CD25 GG11 GG14 GG16

Claims (1)

[Claims] 1. 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, and a material different from the main conductor layer is formed on the entire other surface of the main conductor layer. Forming a second plating layer, forming a base conductor layer having a material different from that of the second plating layer on the entire other surface of the second plating layer, etching the main conductor layer using the first plating layer as a mask; Forming a discrete convex portion by using the main conductor layer as a mask, etching the second plating layer, removing the first plating layer, and allowing the resin layer to penetrate the convex portion and then forming the convex portion. After etching the top of the protruding portion, an object to be connected is arranged on the surface on the side where the first plating layer was, so that the top of the convex portion comes into contact with the object to be connected,
A method for manufacturing a connection structure, wherein the object to be connected and the base conductor layer are connected by the convex portion.