JP2989478B2 - Hybrid integrated circuit device - Google Patents

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 more particularly, to a case where a nickel (Ni) film is formed on a copper (Cu) wiring pattern in consideration of a bonding property, a short circuit caused by the whiskers caused by the Ni. This is related to the prevention of occurrence of phenomena.

[0002]

2. Description of the Related Art In general, a hybrid integrated circuit device often uses Cu because of its low resistance. But this Cu
Has disadvantages such as poor bondability due to easy oxidation and high thermal conductivity.
It is common to apply i. As these known techniques, Japanese Patent Application No. 5-295722 is described in detail, and will be described below with reference to, for example, FIG. 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, and the like are mounted on the conductive path (2) or a conductive pad integrated therewith. Further, electrical connection is achieved between the semiconductor chip and the conductive pad or the like by a thin metal wire, and the circuit is realized.

[0003] Here, the substrate (1) is made of Al metal, the surface of which is anodized to produce aluminum oxide (3), and an epoxy resin (4) is coated on the entire surface in consideration of adhesion to the conductive path. Has been adhered. In the above structure, Ni (6) is plated on the surface in consideration of oxidation prevention of Cu (5) and bonding property of the thin 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 of up to several tens of μm is dried, it takes several hours or more, but if it is performed by a shower type wet etching, it can be etched in several minutes to several tens of minutes. In particular, Ni is deposited on the entire surface or a part of Cu,
When wet etching is performed using an etchant of iron (FeCl 3), since the etching rate of Cu is higher, a Ni overhang (7) is formed as shown in FIG.

[0005]

SUMMARY OF THE INVENTION During the manufacturing process,
Brushing is performed in consideration of removal of resist dust and other dust and adhesion, and improvement of bonding properties since the Ni surface is flat. That is, dust is removed by this brushing, and the surface of Ni becomes rough.

However, since the eaves are provided on Ni as shown in FIG. 4, the bristle of the brush hits the eaves, and generates Ni whiskers (8) to cause a short circuit between the conductive paths (2). , Film peeling and the like occurred. FIG. 3 is a schematic diagram when conductive pads are brought close to each other for high-density mounting of the hybrid integrated circuit device. The distance indicated by the arrow, which varies depending on the pad size, indicates the distance 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 pad, and there is also a problem that a beard is generated and a short circuit occurs. Moreover, in the conductor circuit for large current, Cu
The thickness of the foil is required, and the width of the Ni whiskers increases with the thickness of the conductor. 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 an attempt is made to achieve a high-density hybrid integrated circuit device with a large current, the short circuit due to the 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, first, is to solve the problem by making the conductive pad a non-linear shape.
Second, the problem is solved by making the shape of the conductive pad a circle or an ellipse.

[0008]

First, by forming the shape of the electric pad in a non-linear manner, the contact area of the bristle of the brush can be set as a point, and film peeling due to the contact can be prevented. For example, in FIG. 1, if the rotation direction of the brush rotates in the vertical direction on the paper surface, if the side of the pad is a straight line, the side is always in contact with the bristle feet. Therefore, the force causing the film peeling always acts on Ni, but if the shape of the pad is non-linear, the contact area becomes one point, so that the force causing the film peeling can be greatly reduced. Moreover, if the pad is circular, the point indicated by arrow A in FIG. 1 is the shortest distance, and the other points are longer than this distance A. Therefore, even if a beard having a length of A occurs, the short-circuited portion is indicated by the arrow, and the other portions are effective in preventing the short-circuit.

Second, by making the shape of the conductive pad a circle or an ellipse, as described above, the contact of the hair is point contact, and the area can be secured, so that wire bonding of a thin metal wire can be performed.

[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) having at least an insulating surface, on which a conductive path (2) is formed. Here, the substrate (1) is made of an Al substrate, the surface of which is formed with aluminum oxide (3) by anodic oxidation, and furthermore, an epoxy resin (4) in consideration of adhesiveness with the conductive path (2). Is coated. However, it is sufficient that at least the surface is insulated, and if a conductive path can be directly formed by another method (for example, sputtering or the like), a conductive material may be applied to a ceramic, a printed board, a glass substrate, or the like.

The conductive path (2) has a two-layer structure, and the lower first conductive path (5) is formed of, for example, a metal made of Cu. In this case, the conductive path (2) has a thickness of 35 μm. )
The main. On the first conductive path (5), several μm to
A second layer made of Ni of about 10 μm,
The conductive path (6) is applied. The figure shows a state in which bonding pads are integrated in one region in consideration of bonding properties and high density.

A first feature of the present invention is that a conductive pad (1
0), that is, a non-linear shape. The shape of a conventional conductive pad is a square as shown in FIG. 3, and when the brush rotates in a direction parallel to the opposite sides of the square, the probability of contact with the parallel sides is very high. Although it is high, for example, in the case of a circular or elliptical shape, the contact area is one point regardless of the direction of rotation of the brush, and the contact probability of the bristle of the brush is considerably lower than the conventional shape. it can.

As shown in FIG. 1, the interval between arrows A is
It shows the shortest distance between the conductive pad and the wiring on the right.
It is unknown where the whiskers occur, but if the whiskers generated at this arrow are shorter than the distance A, the distance around the other pads is longer than that, so there is no problem at all. Also, except for the location indicated by the arrow A, it goes away from the wiring on the right side more and more.
Depending on the length of the whiskers, contact with adjacent wiring is reduced.

Next, the manufacturing method will be briefly described. First, a metal substrate (1) is prepared, its surface is anodically oxidized to form aluminum oxide (3), and an epoxy resin (4) is formed into a film. Press-bond Cu foil (5) to the surface, and further Ni layer (6)
Is formed by plating. Subsequently, 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 always supplied to the surface to be etched. The method of supplying the new etchant to the surface to be etched and simultaneously applying a flow to the etchant to remove a reactant is temporarily referred to as a forced supply method. Various methods can be considered for this method, such as a shower and a method of circulating in a liquid layer. Here, the etchant of the conventional method is ferric chloride, and a 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) are formed in a state where the eaves (7) as shown in FIG. 4 are formed. A path (6) is formed.

Finally, for simplicity of explanation, even if brushing is performed to roughen the Ni film and remove dust, unlike the conventional structure, film peeling can be eliminated. Thereafter, although omitted in the drawings, a chip resistor, a semiconductor chip, and the like are fixed, and a thin metal wire (11) is wire-bonded to a required portion to achieve a predetermined circuit. Further, if necessary, connection of leads and mounting of a resin mold or a case are performed to complete the process.

[0016]

As is clear from the above description, the first
In addition, by forming the conductive pad in a non-linear manner, the bristle of the brush abuts at only one point, so that the Ni whiskers can be greatly suppressed as compared with the conventional rectangular shape. Although the description is omitted in the embodiment, the effect can be obtained even if the non-linear shape is formed in the conventional structure. In other words, the eaves are formed, but since the contact area of the hair foot is only one point, the occurrence of beard can be suppressed.

Further, the shortest distance is one point because of the circular conductive pad, and the distance is gradually increased in other areas. Therefore, the probability of short-circuiting decreases as the distance increases. Second
In addition, if a circle or an ellipse is used as the shape, a bonding area requiring a relatively large area can be secured, so that good wire bonding can be performed.

[Brief description of the drawings]

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

FIG. 2 is a pattern diagram employing the conductive pad of FIG. 1;

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

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

[Explanation of symbols]

 Reference Signs List 1 substrate 2 conductive path 5 first conductive path 6 second conductive path 10 conductive pad 11 thin metal wire

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jun Sakano 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Sadamichi Takagusagi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (56) References JP-A-5-55284 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23/12 H05K 3/34 501

Claims (2)

(57) [Claims] 1. A substrate having at least an insulating surface and a conductive pad made of copper formed on the surface of the substrate
And a passive element and an active element fixed to the substrate ,
It said passive element or at the hybrid integrated circuit device having at least a thin metal wires for electrically connecting one and the conductive pads of the active element, the conductive pad is a copper foil and a Ni layer are sequentially stacked And said
Ni that constitutes the conductive pad has an eaves formed
In both cases, the shape of the conductive pad is substantially circular or elliptical.
A hybrid integrated circuit device characterized by a certain point. 2. The method according to claim 1, wherein the copper foil is approximately 35 μm to 105 μm.
m, the Ni is several μm to 10 μm,
The Ni surface is roughened by brushing.
2. The hybrid integrated circuit device according to 1.