JP2002134187A - Connection material, connection structure and method for manufacturing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide connection material, a connection structure and a method for manufacturing the same materializing connection or the like between layers of high integration density, high productivity and very low connection resistance. SOLUTION: A copper foil 1 (main conductor layer) has a nickel plating layer 3 on the whole surface of one side and a thicker patterned nickel plating layer 2 on the surface of the opposite side, and has a gild plating layer 4 on a surface of the nickel plating layer 2 and a copper plating layer 5 (base layer conductor layer) on the surface of the nickel plating layer 3. The copper foil 1 is etched with the gold plating layer 4 and the nickel plating layer 2 as a mask, to form a scattered protrusion body 10, and the nickel plating layer 3 is etched with a mask of the protrusion body 10. Consequently, connection material, having most of electrical conduction path of connection part composed of a solid metal (copper foil 1 or the like), is obtained. By pressing the connection material on an object to be connected, the connection 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 connection material or a connection structure for connecting between layers in a wiring board or connecting a wiring board to a mounted component, and a method of manufacturing the same.

[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. The connection structure between the wiring board and the mounted components is also formed as appropriate. 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)). It introduces a technique of forming a conductive bump using a conductive paste by a printing technique as an alternative to an interlayer connection technique by a copper through-hole plating method.

[0003]

However, the connection structure according to the prior art described above 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 were concerns about the reliability of the connection, and it was difficult to use for large current applications.

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

[0005]

Means for Solving the Problems A connecting material according to the present invention made for solving this problem includes a base conductor layer, a main conductor layer existing on the base conductor layer, and a pattern formed on the main conductor layer. And a material different from that of the main conductor layer.
And the main conductor layer is etched using the first plating layer as a mask to form discrete convex portions. In the connection structure of the present invention, the connection material is used, and the top of the convex portion is in contact with the object to be connected via the first plating layer. Are connected.

The connecting material or the connecting structure according to the present invention has a second plating layer which is located between the base conductor layer and the main conductor layer and is made of a different material from the base conductor layer and the main conductor layer. It is desirable that the thickness is smaller than the thickness when the first plating layer is formed, and that the second plating layer is also etched where the main conductor layer is etched.

In the connecting material of the present invention, a first plating layer having a material different from that of the main conductor layer is formed on one surface of the main conductor layer in a pattern, and a base conductor layer is formed on the entire other surface of the main conductor layer. It is manufactured by etching the main conductor layer using the first plating layer as a mask to form discrete convex portions. further,
The object to be connected is arranged on the surface on the first plating layer side so that the top of the convex portion comes into contact with the object to be connected via the first plating layer. Are connected to form the connection structure of the present invention.

[0008] Here, the main conductor layer and the base conductor layer are formed of a second plating layer having a different material and thinner than the first plating layer on the entire other surface of the main conductor layer, and then the base conductor layer is formed. Main conductor layer (convex portion) after etching layer
It is preferable that the second plating layer is etched using the mask as a mask, and the first plating layer is left at that time.

In 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 of 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.

[0010]

Embodiments of 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 the upper surface) in the drawing is a pattern plating having a thickness of 5 μm, and the nickel plating 3 on the lower surface (hereinafter, referred to as the lower surface) in the drawing is the entire plating having a thickness of 3 μm. And The formation of the nickel plating 2 with a pattern on the upper side may be carried out by once plating the entire surface and etching the pattern. However, a method in which a mask resist having a negative pattern is formed in advance and plating is formed only in a portion having no mask resist. Is better. This is because the mask resist can be used as it is in the subsequent gold plating. In either case, the difference between the thicknesses of the plating layers on both sides can be easily realized by controlling the current density on each side.

Next, a gold plating 4 is formed on the surface of the nickel plating 2 with a pattern (FIG. 3). At this time, the mask resist used for forming the nickel plating 2 may be used as it is. Note that a mask is formed entirely on the lower surface. A thickness of the gold plating 4 of 1 μm is sufficient.
Subsequently, the entire mask on the lower surface is removed, and a full mask is formed on the upper surface instead. In this state, a thickness of 20
Copper plating 5 of about μm is formed (FIG. 4). The copper plating 5 is a base conductor layer. In this state, nickel plating 3 is located between copper foil 1 (main conductor layer) and copper plating 5 (base conductor layer).

Next, all the mask resist on the upper surface is removed, and a whole mask is formed again 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. that time,
Gold plating 4 and nickel plating 2 act as an etching mask. Therefore, only the portions of the copper foil 1 where there is no gold plating 4 and nickel plating 2 are etched to form discrete convex bodies 10 (FIG. 5). At this time, the metal plating (nickel plating 2 and gold plating 4) acting as an etching mask has a stronger adhesion to the copper foil 1 than a resin-based resist mask. Therefore, 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 patterns of the gold plating 4 and 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. This etching is quick etching to the extent that the nickel plating 3 having a thickness of 3 μm is melted. At this time, since the convex body 10 acts as an etching mask, the copper plating 5 is exposed upward at a portion where there is no convex body 10 (FIG. 6). In this state, the nickel plating 3 exists only under the convex body 10. In this state, although the lower surface of the nickel plating 2 is slightly cut off,
Most remain. This is because the etching time is short, the nickel plating 2 is originally thicker than the nickel plating 3, and the upper surface of the nickel plating 2 is protected by the gold plating 4.

Next, an adhesive layer is combined. That is,
The adhesive layer is pressed from above each convex body 10 in the state shown in FIG. 6 so that the convex body 10 penetrates the adhesive layer 6 (FIG. 7). 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. 7, the nickel plating 2 and the gold plating 4 on the convex body 10 are exposed above the adhesive layer 6.

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 nickel plating 2 and the gold plating 4 (FIG. 8). . Then, this is pressed to obtain the state shown in FIG. The press at that time is 390 N /
cm ² . 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 via the nickel plating 2 and the gold plating 4, 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 has an interlayer connection structure between the copper plating 5 (base layer conductor layer) and the copper foil 7 (upper layer). Then, the copper plating 5 (base layer conductor layer) and the copper foil 7 (upper layer)
An appropriate patterning may be performed.

In this structure, the conductive path of the interlayer connection portion is formed by nickel plating 3, convex body 10, nickel plating 2, and gold plating 4 from below. The conductive path does not include a portion made of the conductive paste. That is, most of them are made of solid metal. Therefore, its via resistance is extremely low. In addition, patterning for forming the 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 shown in FIG. 6 or the one in the state shown in FIG. 9 (the arrangement of the convex bodies 10 is assumed to be standard) is stocked, and the subsequent processes (copper plating 5 (lower layer)) And copper foil 7
(Including patterning of (upper layer)). Then, the thing of the state of FIG. 6 can be called a "connection material."

Next, a modified example will be described. As a first modified example described above, there is an example in which the range from FIG. 6 to FIG. 9 during the manufacturing process is manufactured by another method. That is, as shown in FIG. 10, the copper foil with resin 8 is arranged above each convex body 10 in the state of FIG. 6 and pressed. Naturally, the copper foil with resin 8 is arranged such that the copper foil 81 faces upward in the figure and the resin layer 82 faces each convex body 10. Pressing is performed at about 390 N / cm ^2, which is higher than normal pressing pressure, as described above. Thereby, each convex body 10 breaks through the resin layer 82 and contacts the copper foil 81,
The top of each convex body 10 comes into tight contact with the copper foil 81 via the nickel plating 2 and the gold plating 4. That is, a state similar to that of FIG. 9 is obtained.

Next, as a second modified example, there is an example in which the present invention is applied to connection between a wiring board and a mounted component such as an IC chip, instead of interlayer connection in the wiring board. That is, as shown in FIG. 11, the mounting component 9 is combined with the component in the state of FIG. 7, and the top of each convex body 10 is in contact with the pad of the mounting component 9 via the nickel plating 2 and the gold plating 4. I do. 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 this time is the same as the above, and 390 which is higher than the normal press pressure is used.
N / cm ² . In the state after the pressing, each convex body 10 is firmly adhered to the pad of the mounting component 9 via the nickel plating 2 and the gold plating 4 and the copper plating 5 (the base layer conductor) via the nickel plating 3. Layer). 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 is formed thicker, gold plating 4 is formed on the surface of nickel plating 2, and copper plating 5 (base conductor layer) is formed on the surface of nickel plating 3. Then, the copper foil 1 is etched into a discrete convex body 10 using the gold plating 4 and the nickel plating 2 as an etching mask, and the nickel plating 3 is etched using the convex body 10 as an etching mask. 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). The connection structure is obtained by pressing the upper layer (copper foil 7) or the mounted component 9 on the connection material. Thus, a connection material, a connection structure, and a method of manufacturing the connection material, which have extremely low resistance at the conductive portion and are excellent in the degree of integration and productivity, have 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 more thickly, and copper plating 5 is eliminated.
The nickel etching shown in FIG. 6 may not be performed.
In this case, the nickel plating 3 forms the main conductor layer. Further, it is conceivable that the difference in thickness between the nickel plating 2 and the nickel plating 3 is further increased, and the gold plating 4 is not used. Alternatively, in the present embodiment, the main conductor layer (copper foil 1, convex body 10) and the base conductor layer (copper foil 5)
Is made of copper, and the pattern plating and the entire surface plating are made of nickel. However, the combination of these metal types may be different. However, it is a condition that they can be appropriately formed by plating and that they can be selectively etched.

[0022]

As is apparent from the above description, according to the present invention, a connection material for realizing interlayer connection with high integration density and productivity and extremely low connection resistance, and a connection structure thereof, and Methods for their manufacture are provided.

[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 gold plating is performed on the pattern nickel plating of FIG. 2;

FIG. 4 is a cross-sectional view showing a state where the entire lower surface in the state of FIG. 3 is plated with copper;

FIG. 5 is a cross-sectional view showing a state in which copper foil is etched to form discrete convex bodies in the state of FIG. 4;

FIG. 6 is a cross-sectional view showing a state where an exposed portion of the entire nickel plating in the state of FIG. 5 is etched.

FIG. 7 is a cross-sectional view showing a state where an adhesive layer is combined with the state of FIG. 6;

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 state where a copper foil with resin is combined with the state of FIG. 6;

FIG. 11 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 nickel 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

Continued on the front page F term (reference) 5E023 AA04 AA16 BB01 BB11 BB16 BB22 CC26 EE01 FF07 HH06 HH11 HH28 5E051 CA04

Claims (7)

[Claims] 1. A base conductor layer, a main conductor layer present on the base conductor layer, and a first plating layer present on the main conductor layer in a pattern and different in material from the main conductor layer Wherein the main conductor layer is etched using the first plating layer as a mask to form discrete convex portions. 2. The connecting member according to claim 1, further comprising a second plating layer located between the base conductor layer and the main conductor layer, the second plating layer being made of a material different from the second plating layer.
A connection material, wherein a thickness at the time of formation of the plating layer is smaller than a thickness at the time of formation of the first plating layer, and the second plating layer is also etched where the main conductor layer is etched; . 3. A base conductor layer, a main conductor layer present on the base conductor layer, and a first plating layer present on the main conductor layer in a pattern and different in material from the main conductor layer. The main conductor layer is etched using the first plating layer as a mask to form discrete projections, and the tops of the projections are connected to each other through the first plating layer. A connection structure wherein the object to be connected and the base conductor layer are connected by the convex portion. 4. The connection structure according to claim 3, wherein
A second plating layer located between the base conductor layer and the main conductor layer and made of a different material from the second plating layer, and the thickness of the second plating layer when forming the first plating layer is The connection structure according to claim 1, wherein the second plating layer is also etched at a portion where the main conductor layer is etched. 5. A first plating layer having a material different from that of the main conductor layer is formed on one surface of the main conductor layer in a pattern, and a base conductor layer is formed on the entire other surface of the main conductor layer. A method of manufacturing a connecting material, wherein the main conductor layer is etched using a plating layer as a mask to form discrete convex portions. 6. A first plating layer having a material different from that of the main conductor layer is formed on one surface of the main conductor layer in a pattern, and a base layer conductor layer is formed on the entire other surface of the main conductor layer. The main conductor layer is etched using the plating layer as a mask to form discrete convex portions, and a connection object is arranged on the surface on the first plating layer side, and the top of the convex portion is the first portion. A method for manufacturing a connection structure, wherein a state is established in which a connection object is brought into contact with a connection object via a plating layer, and the connection object and the base layer conductor layer are connected by the convex portion. 7. The manufacturing method according to claim 5, wherein the material of the main conductor layer and that of the base layer are different from each other over the entire other surface of the main conductor layer. After forming the second plating layer, forming the base conductor layer, etching the main conductor layer, etching the second plating layer using the main conductor layer as a mask,
In this case, the first plating layer is left.