JPH0766954B2 - Semiconductor 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 semiconductor device having a semiconductor chip such as an IC or LSI, and more particularly to the shape of a finger connected to an electrode of the semiconductor chip.

[0002]

2. Description of the Related Art Conventionally, a metal lead frame has been used for assembling a semiconductor device in which a semiconductor chip is integrated with a resin mold and a plurality of pins are provided in a protruding manner. This lead frame is formed by punching a thin metal plate with a press, etching or the like, and its shape is shown in FIG.
, A tab lead 3 for supporting a rectangular tab 2 to which the semiconductor chip 1 is attached at its four corners, and a tab 2
A large number of fingers 4 whose inner ends are exposed to the peripheral edge of the frame 4, and a frame portion 5 which supports the outer ends of the fingers 4 and the tab leads 3.
It is composed of sprocket holes 6 provided at regular intervals along both edges of the frame portion 5.

In order to assemble a semiconductor device using such a lead frame 7, first, the semiconductor chip 1 is mounted on the tab 2 and each electrode of the semiconductor chip 1 and the inner end (tip portion) of the finger 4 corresponding to the electrode. Directly connected to the frame 5
A flat lead or in-line type semiconductor device was obtained by molding the inside region of the above with a synthetic resin to cover the semiconductor chip 1 and then cutting off the frame portion 5.

[0004]

By the way, the conventional finger 4 connected to each electrode of the semiconductor chip 1 has a rectangular cross section at a portion facing the electrode and has an edge at the edge, and does not have a self-guiding function. Therefore, if the position of the facing portion is displaced and rides on the protective film around the electrode, it is connected at that position, the protective film is broken, or the connection between the finger 4 and the electrode becomes incomplete or impossible. There is a problem with operational reliability.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a semiconductor device in which the finger and the electrode of the semiconductor chip are surely connected to each other and which has high operation reliability.

[0006]

In order to achieve the above object, the present invention is directed to a semiconductor device having a finger which extends toward the device hole and is connected to an electrode of a semiconductor chip arranged in the device hole. It is what

Further, the semiconductor chip of the finger is characterized in that an inclined surface formed of, for example, a curved surface which is convexly curved outward is formed at a side end portion of the finger opposite to the electrode.

[0008]

As described above, the present invention is provided on the side end portion of the finger.
By forming the inclined surface, the part where the inclined surface is formed
The electrode bonding area at the tip of the finger can be reduced by just that much.
Noh. Therefore, the tip of the finger and the electrode of the semiconductor chip
By increasing the pressure per unit area with
Therefore, it is possible to improve the reliability of bonding.

Further, when the semiconductor chip electrode is applied to a type in which the periphery of the electrode is surrounded by a protective film, a semiconductor device is used.
When mounting and assembling the tip of the finger against the electrode of the semiconductor chip
Even if the position of the
Surface and hit the tip of the finger by guiding the inclined surface.
Guide to the electrode side and make sure the tip of the finger is appropriate for the electrode.
The finger and the electrode can be joined securely.
It ’s true. Also, by providing the finger with an inclined surface,
The destruction of the protective film due to the conventional edge is also eliminated.
From this, a semiconductor device with high operational reliability is obtained.
You can

[0010]

Embodiments of the present invention will now be described with reference to the drawings.
1 is a perspective view showing a cross section of a part of a finger, FIG. 2 is a vertical cross section of the tip of the finger, FIG. 3 is a plan view showing a part of the finger, and FIG. 4 is a finger showing another embodiment. FIG. 5 is a perspective view showing a cross section of a part of FIG. 5, FIG. 5 is a view showing a manufacturing process of the lead frame, FIG. 6 is a plan view showing a resist pattern of a finger portion, FIG. 7 is a plan view of the lead frame, and FIG.
FIG. 6 is a cross-sectional view showing a connecting portion between a finger and an electrode of a semiconductor chip.

The finger 4 is made of a metal foil and is electrically conductive, and has a groove 4a on the lower surface of the central portion thereof along the longitudinal direction F (see FIG. 1) of the semiconductor chip, as shown in FIG. Arcuate flange portions 4b and 4c having a curved surface 20 are provided on both sides of the upper surface connected to the electrodes. As shown by the chain double-dashed line in FIG. 3, the groove 4a is formed in an intermediate portion of the finger 4 excluding the base portion 4d and the tip end portion (inner end portion) 4e, and the cross-sectional shape of this intermediate portion is substantially U-shaped. The second moment of area for bending is increased with less material.

Further, as shown in FIG. 2, a tip portion 4e of the finger 4 is formed with a thick bump 4f which is connected to the electrode of the semiconductor chip 1. A concave portion 4g extending in a direction substantially orthogonal to the groove 4a is formed on a lower surface of a portion connecting the tip portion 4e and the intermediate portion, and a bump 4f protruding from the upper surface of the intermediate portion is formed ahead of the concave portion 4g. ing.

FIG. 4 is a perspective view showing another example of the finger 4, and a metal thin film 4h is further formed on the upper surface of the finger 4 of the above embodiment.
Are laminated. By doing so, the rigidity of the finger 4 can be further increased. In this case
Is an arc-shaped flange portion 4 on both sides of the upper surface of the metal thin film 4h.
A curved surface 20 is formed along b and 4c.

FIG. 5 shows a manufacturing process of the lead frame having the finger structure.

First, as shown in FIGS. 1A and 1B, a thickness 35 to 7 made of synthetic resin such as polyimide or polyester.
A device hole 9 is formed in a film 8 having a thickness of about 0 μm by pressing using a push back method. In the push back method, as shown in (a), first, a desired part is punched out by a die,
Then, the receiving mold is raised again and (b) the cutout piece 10 as shown in the figure.
Is a processing method of fitting and holding in the device hole 9 that has been once drilled. Therefore, after processing, the film 8 is maintained in the state of the device hole 9 in which the device holes 9 are not opened, and can be handled as a single sheet. When the device hole 9 is formed, other window portions such as the sprocket hole 6 (see FIG. 7) can be formed at the same time.

Next, on the film 8 which is not opened,
(C) As shown in the figure, a conductive metal layer 11 such as copper is formed by a thin film forming means such as electroless plating or vapor deposition. Further, a photoresist layer 12 is applied on the conductive metal layer 11 as shown in FIG. 3D, or a dry film-like resist layer having a thickness of about 150 μm is adhered to the photoresist mask 13.
Then, the exposed portion is removed by exposing it to a desired pattern and then washing to form a resist layer 12 on the conductive metal layer 11 as shown in FIG. After the push back, the conductive metal layer 11 and the photoresist layer 12 are
Has a function as a temporary fixing means for preventing unnecessary removal of the cut-out piece 10.

Next, the film 8 is stripped with selenious acid, caustic soda, etc., and a metal such as nickel is electroformed, so that the resist layer 12 is formed as shown in FIG.
The lead frame 7 having a desired pattern is formed on the conductive metal layer 11 on which the layers are not formed.

When the lead frame 7 is electroformed with a metal such as nickel, 0.07% or less of a brightening agent (carbon is less than 0.
01 to 0.04%, sulfur 0.01 to 0.04%, and the sum of these is 0.07% or less) is used. The content of the brightening agent is usually about 0.1%, but if the content is high as described above, the temperature of the lead frame 7 during the joining with the IC chip causes the nickel to become brittle. Therefore, the content of the brightening agent needs to be limited to 0.07% or less. Further, if no brightening agent is contained, sufficient mechanical strength cannot be obtained, and there is a risk of contact with an adjacent lead and short-circuiting due to deformation during processing.

After electroforming, the resist layer 12 is removed, and then the cut-out piece 10 that closes the device hole 9 is pulled out to form a lead frame 7 having a cross section as shown in FIG. To be done. In this case, since the conductive metal layer 11 has a thickness, for example, about 5 to 10 μm, which is provided to ensure conductivity for electroforming, the pull-out force is small and the lead frame 7 cannot be deformed. Absent.

Although the lead frame 7 is formed on the synthetic resin film 8 in the above embodiment, a conductive metal film such as stainless steel may be used in place of the synthetic resin film 8.

In this case, it is not necessary to newly provide a conductive metal layer 11 made of copper or the like as shown in FIG. 7C, and a photoresist layer 12 is formed on the metal film and directly electroformed. It is possible to form the lead frame 7 made of nickel, copper, gold or an alloy thereof on the metal film.

FIG. 6 is a diagram showing a resist pattern of a finger portion in the manufacturing process.

In the finger portion, in addition to the resist layer 12 for the finger having a desired pattern, a resist portion 12a along the longitudinal direction is formed at the center of the non-resist portion 14 at a position corresponding to the finger 4, and this resist portion 12a is formed. The aforementioned groove 4a is formed corresponding to the portion 12a.

A circular non-resist portion 15 separated by the resist layer 12 is formed at the tip of the non-resist portion 14, and when a metal having such a resist layer 12 is subjected to electroforming. In the initial stage after the start of electroforming, the finger 4 main body is formed separately from the metal layer grown on the circular non-resist portion 15 separated by the resist layer 12, but the electroforming is further performed. As it advances, the metal on the non-resist portion 15 and the main body of the finger 4 which have been separated are connected together beyond the resist layer 12. Since the thickness of the metal laminated by electroforming depends on the current density, the metal layer on the dot-shaped non-resist portion 15 becomes thicker than that of the flat-shaped finger 4 main body portion. A bump 4f as shown in 2 is formed. During this electroforming, the non-resistive
As shown in FIG. 1, the metal layer on the metal parts 14 and 15 is a resist.
It grows so as to partially cross the edge of the layer 12, and
The finger 4 having the flange portions 4b and 4c is formed.
It Since the resist layer 12 is electrically insulating, it has a flange portion.
There is a limit to the growth of 4b and 4c.
Since the current concentrates on the central side of 14 and 15,
As shown in FIG. 1, the upper surfaces of the protrusions 4b and 4c are necessarily inclined.
It becomes a mountain shape having a slope (curved surface 20).

When forming the metal thin film 4h as shown in FIG. 4, a second electroforming process may be performed in addition to the above electroforming process.

Further, when the lead frame 7 is electroformed with a metal such as nickel, the lead frame 7 can be made by superposing two layers, a layer not containing a brightening agent and a layer containing a brightening agent. If electroforming is performed without adding a brightener, the surface will be roughened and the irregularities will become remarkable, so temperature concentration during joining with the IC chip, especially when joining under pressure welding, tends to occur, and the hardness is also high. It becomes low, and it is not necessary to apply a large stress to the semiconductor chip, and the bonding can be ensured.

On the other hand, if a layer containing a brightening agent is provided on the side opposite to the joint surface, the mechanical strength of the lead frame 7 can be secured. The content of the brightening agent is preferably limited to 0.07% or less as described in the above embodiment.

[0028]

As described above, the present invention forms the inclined surface by forming the inclined surface at the side end portion of the finger.
The contact area of the electrode at the tip of the finger can be reduced only
And are possible. Therefore, the tip of the finger and the semiconductor chip
Increase the pressure per unit area with the electrodes of the
It is possible to increase the reliability of bonding.

Further, when the semiconductor chip electrode is applied to a type in which the periphery of the electrode is surrounded by a protective film, a semiconductor device is used.
When mounting and assembling the tip of the finger against the electrode of the semiconductor chip
Even if the position of the
Surface and hit the tip of the finger by guiding the inclined surface.
Guide to the electrode side and make sure the tip of the finger is appropriate for the electrode.
The finger and the electrode can be joined securely.
It ’s true. Also, by providing the finger with an inclined surface,
The destruction of the protective film due to the conventional edge is also eliminated.
From this, there is an advantage that a semiconductor device having high operation reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cross section of a part of a finger according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the finger.

FIG. 3 is a plan view showing a part of the finger.

FIG. 4 is a perspective view showing another embodiment of the finger of the present invention.

FIG. 5 is a diagram showing a manufacturing process of the lead frame according to the embodiment of the present invention.

FIG. 6 is a diagram showing a resist pattern of a finger portion.

FIG. 7 is a plan view showing the shape of a lead frame.

[Explanation of symbols]

1 Semiconductor Chip 2 Tab 3 Tab Lead 4 Finger 4b, 4c Flange 4e Tip 4f Bump 7 Lead Frame 9 Device Hole 20 Curved Surface

Claims (2)

[Claims] 1. A semiconductor device having a finger extending to the device hole side and connected to an electrode of a semiconductor chip arranged in the device hole, wherein a side end of the finger facing the electrode of the semiconductor chip is formed. A semiconductor device characterized in that an inclined surface is formed in the portion. 2. The semiconductor device according to claim 1, wherein the inclined surface is a curved surface that is convexly curved toward the outside.