JPH0846083A - Hybrid integrated circuit device - Google Patents

Abstract

PURPOSE:To suppress generation of whiskers caused by the formation of overhangs at the brushing for bonding and dust removal by laying a Ni film on a conductive pad. CONSTITUTION:A shape of a conductive pad 10 is formed to be circular. As a shape of a bristle of a brush is formed with non-linear contour, the region of contact of it is a point and the generation of the whiskers is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrated circuit device, and in particular, when a nickel (Ni) film is formed on a copper (Cu) wiring pattern in consideration of bonding property, short circuit caused by the beard due to Ni is caused. It is related to prevention of occurrence of.

[0002]

2. Description of the Related Art Generally, Cu is often used in a hybrid integrated circuit device because of its low resistance. But this Cu
Has a drawback in that it is apt to be oxidized and has a high thermal conductivity and thus has a poor bonding property.
It is common to apply i. Japanese Patent Application No. 5-295722 is a detailed known technology, and will be described below with reference to FIG. 4, for example. For example, a conductive path (2) for achieving a desired circuit is formed on an insulating substrate (1), and a semiconductor chip, a chip resistor, etc. are mounted on the conductive path (2) or a conductive pad integrated with the conductive path (2). In addition, electrical connection is achieved between the semiconductor chip and the conductive pad by a thin metal wire, and the circuit is realized.

Here, the substrate (1) is made of Al metal, the surface is anodized to form aluminum oxide (3), and an epoxy resin (4) is formed on the entire surface in consideration of adhesiveness with a conductive path. It is covered. In the above structure, Ni (6) is plated on the surface in consideration of the oxidation prevention of Cu (5) and the bonding property of the fine metal wire.

On the other hand, there are two types of etching, dry etching and wet etching, but wet is the mainstream in consideration of throughput. Generally several μm
This is because, when a metal having a thickness of up to several tens of μm is dried, it takes several hours or more, but a shower-type wet etching can be performed in a few minutes to several tens of minutes. In particular, Ni is deposited on the entire surface or a part of Cu to form a second chloride.
When wet etching is performed with an etchant of iron (FeCl3), since Cu has a higher etching rate, Ni eaves (7) are formed as shown in FIG.

[0005]

[Problems to be Solved by the Invention] During the manufacturing process,
Brushing is performed in consideration of removal of resist dust and other dust to be attached and improvement of bonding property because the Ni surface is flat. In other words, this brushing removes dust and the surface of Ni becomes rough.

However, as shown in FIG. 4, since the eaves are provided on the Ni, the bristles of the brush hit the eaves to generate Ni beards (8), which causes a short circuit between the conductive paths (2). , Film peeling and the like occurred. Further, FIG. 3 is a schematic view when conductive pads are brought close to each other for high-density mounting of the hybrid integrated circuit device. Although it depends on the pad size, the interval indicated by the arrow indicates the interval between the side of the pad and the wiring and is set to about 100 μm. However, the eaves are also formed on the conductive pads, and there is a problem that whiskers are generated and short circuits occur. Moreover, in the conductor circuit for large current, Cu
There is a problem that the thickness of the foil is required, the width of the Ni whiskers increases with the thickness of the conductor, and short circuits frequently occur. That is, depending on the current value, the film thickness of Cu (5) is 35 μm, 70 μm and 10 μm.
Unlike 5 μm, the length of the eaves when patterned by the wet etching is about 5 μm, 10 μm and 15 μm.
It becomes longer with m. Therefore, when attempting to achieve a high-current, high-density hybrid integrated circuit device, this short circuit due to whiskers becomes a very serious problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the first problem is to solve the problem by forming the conductive pad into a non-linear shape.
Secondly, the problem is solved by making the shape of the conductive pad into a circle or an ellipse.

[0008]

First, by forming the shape of the electric pad to be non-linear, the contact area of the bristles of the brush can be set as a point, and film peeling due to contact can be prevented. For example, in FIG. 1, assuming that the brush rotates in the vertical direction of the paper, if the side of the pad is a straight line, this side is always in contact with the bristle. Therefore, the force that causes the film peeling always acts on Ni, but if the shape of the pad is non-linear, there is only one contact area, so the force that causes the film peeling can be greatly reduced. Moreover, if the pad is formed into a circle, the position of the arrow A shown in FIG. 1 is the shortest distance, and other than that, it is longer than this distance A. Therefore, even if a beard having a length of A occurs, the short circuit is at the position of the arrow, and the other parts are effective in preventing the short circuit.

Secondly, by making the shape of the conductive pad a circle or an ellipse, the contact of the fluff is point contact as described above, and since the area can be secured, wire bonding of fine metal wires is also possible.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hybrid integrated circuit device according to the present invention will be described below with reference to FIGS. First, as shown in FIG. 4, there is a substrate (1) at least the surface of which has an insulating property, on which a conductive path (2) is formed. This substrate (1) is made of an Al substrate here, aluminum oxide (3) is produced on the surface by anodic oxidation, and the epoxy resin (4) is considered in consideration of the adhesiveness with the conductive path (2). Is coated. However, at least the surface should be insulated, and if a conductive path can be directly formed by another method (for example, sputtering), a conductive material may be deposited on a ceramic, a printed circuit board, a glass substrate or the like.

The conductive path (2) has a two-layer structure, and the lower first conductive path (5) is made of a metal such as Cu. Here, the conductive path (2) has a thickness of 35 μm. )
Become the master of. Further, on the first conductive path (5), several μm to
The second is made of Ni of about 10 μm, actually 5 μm here.
Of the conductive paths (6) are applied. Further, the figure shows a state in which the bonding pads are integrated in one region in consideration of the bonding property and the high density.

A first feature of the present invention is that the conductive pad (1
0), that is, a non-linear shape. The conventional conductive pad has a rectangular shape as shown in FIG. 3, and when the brush rotates in a direction parallel to the opposite sides of this rectangular shape, the probability of contact with the parallel sides is very high. Although it is high, if it is in the shape of a circle or an ellipse, there is only one contact area regardless of the brush rotation direction, and the contact probability of the bristles of the brush can be significantly reduced compared to the conventional shape. it can.

Further, as shown in FIG. 1, the distance between the arrows A is
It shows the shortest distance between the conductive pad and the wiring on the right side.
It is unknown where the beard occurs, but if the beard generated at this arrow is shorter than the distance A, the distance around the other pads is longer than that and there is no problem. Also, except for the part indicated by the arrow A, it is getting more and more away from the wiring on the right,
Depending on the length of the beard, contact with the adjacent wiring is reduced.

Next, the manufacturing method will be briefly described. First, a metal substrate (1) is prepared, the surface thereof is anodized to form aluminum oxide (3), an epoxy resin (4) is formed, and then the entire surface of the metal substrate is used by utilizing the adhesiveness of this resin. Cu foil (5) is press-bonded to the surface, and Ni layer (6) is further formed on the entire surface.
Is formed by plating. Then, a photoresist is formed in a region where the conductive path (2) is to be formed by photolithography, and wet etching is performed so that a new etchant is constantly supplied to the surface to be etched. The method of supplying this new etchant to the surface to be etched and at the same time giving a flow to the etchant to remove the reactant is tentatively referred to as a forced supply method. This method can be variously considered, such as a shower and a method of circulating in a liquid layer. Here, the etchant of the conventional method is ferric chloride, and the shower was adopted as a forced circulation method. Second chloride
Since the etching rate R of iron is R (Cu)> R (Ni), the first conductive path (5) and the second conductive path (5) can be formed with the eaves (7) as shown in FIG. A path (6) is formed.

Finally, to simplify the explanation, even if brushing is performed for roughening the Ni film and removing dust, the film peeling can be eliminated unlike the conventional structure. After that, although not shown in the drawing, a chip resistor, a semiconductor chip, and the like are fixed, and a metal thin wire (11) is wire-bonded to a necessary portion to achieve a predetermined circuit. If necessary, leads are connected and a resin mold or a case is attached to complete the process.

[0016]

As is apparent from the above description, the first
In addition, by forming the conductive pad in a non-straight line, since the bristles of the brush contact only at one point, Ni whiskers can be significantly suppressed as compared with the conventional square shape. Further, although the description is omitted in the embodiment, it is effective even if the conventional structure is formed in a non-straight line. In other words, although the eaves are formed, the contact area of the fluff is only one point, so that the beard can be prevented from occurring.

Further, since it is a circular conductive pad, the shortest distance is one point, and other points are gradually longer, so that the probability of short circuit becomes smaller as the distance becomes longer. Second
In addition, if a circle or an ellipse is used as the shape, a bonding area that requires a relatively large area can be secured, so that good wire bonding can be performed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of the present invention.

FIG. 2 is a pattern diagram in which the conductive pad of FIG. 1 is adopted.

FIG. 3 is a diagram of a conventional conductive pad.

FIG. 4 is a perspective view illustrating a conventional problem.

[Explanation of symbols]

 1 Substrate 2 Conductive Path 5 First Conductive Path 6 Second Conductive Path 10 Conductive Pad 11 Thin Metal Wire

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Jun Sakano 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Sadamichi Takasagi 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A substrate having at least a surface of insulation, a first conductive path and a conductive pad made of copper formed on the surface of the substrate, and electrically connected to the conductive path and fixed to the substrate. A passive element and an active element, and at least one of the passive element or the active element and a thin metal wire that electrically connects the conductive pad, the conductive pad has a shape A hybrid integrated circuit device having a shape constituted by non-linear lines. 2. The hybrid integrated circuit device according to claim 1, wherein the conductive pad has a shape of a circle or an ellipse.