JPH06104318A - Intermediate product of semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To provide a highly reliable intermediate product of a semiconductor device on which the connection between fingers can be surely connected to the electrodes of a semiconductor chip. CONSTITUTION:A base material 8 which has conductivity at, at least, its surface, a device hole 9 at a prescribed position, and punched piece 10 in the hole 10 and the finger of a lead frame 7 formed on the material 8 are held on the piece 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing intermediate used during the manufacturing of a semiconductor device having a semiconductor chip such as an IC or LSI, and a manufacturing method thereof.

[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 or by wire bonding, the inner region of the frame 5 is molded with synthetic resin to cover the semiconductor chip 1, and then the frame 5 is cut off to obtain a flat lead or in-line type semiconductor device. Was there.

[0004]

By the way, the tip of the conventional finger 4 connected to each electrode of the semiconductor chip 1 is
As shown in FIG. 7, since it is free and is not held by anything, the tip portion of the finger 4 may be damaged by external force or shock when the lead frame 7 is transferred to another process or wound on a reel for that purpose. Since the pitch intervals cannot be properly maintained due to the deviation in the arrangement direction, the semiconductor chips 1 are misaligned and bonded to the electrodes of the semiconductor chip 1, or the adjacent fingers 4 come into contact with each other to cause a short circuit. .

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a highly reliable intermediate for manufacturing a semiconductor device and a manufacturing method thereof, in which a finger and an electrode of a semiconductor chip are reliably connected. To do.

[0006]

In order to achieve the above object, the first aspect of the present invention is that at least the surface thereof has conductivity,
A base material made of a synthetic resin film or a metal film having a device hole formed in a predetermined position and holding a cutout in the device hole, for example, a conductive metal layer formed on the surface, and formed on the base material The finger portion of the formed lead frame is held on the cutout piece, for example, directly or via the conductive metal layer.

To achieve the above object, the second aspect of the present invention is to punch a device hole at a predetermined position of a synthetic resin base material, and fit a punching piece formed by the punching into the device hole. A push back step of holding, a step of uniformly forming a conductive metal layer on the synthetic resin film containing the punched piece, and a lead frame on the conductive metal layer as desired by the finger in the device hole. And a step of forming.

[0008]

As in the first aspect of the invention described above, since the cutout piece is held in the device hole of the base material and the finger portion of the leadframe is held on the cutout piece, the leadframe is transferred to another process. The tip interval of the finger does not shift in the direction in which the fingers are aligned due to an external force or an impact when the reel is wound around the reel, and the pitch interval can be normally maintained. Therefore, as in the conventional case, the fingers are displaced from the electrodes of the semiconductor chip and joined, or the defects such as short-circuiting by contact with the adjacent fingers are effectively eliminated, and a highly reliable semiconductor device is efficiently manufactured. be able to.

Further, according to the above-mentioned second invention, since the conductive metal layer is uniformly formed on the synthetic resin film including the punched pieces, the conductive metal layer can be used in the manufacturing process. It is possible to reliably prevent the punched pieces from falling off.

Further, since the fingers are formed and held on the conductive metal layer supported by the synthetic resin film, external force or impact when transferring the lead frame to another process or winding it on a reel for that purpose is carried out. As a result, the tip end of the finger does not shift in the direction in which it is aligned, and the pitch interval can be normally maintained. Therefore, as in the conventional case, the fingers are displaced and joined to the electrodes of the semiconductor chip,
The drawbacks such as short-circuiting due to contact with adjacent fingers can be effectively eliminated, and a highly reliable semiconductor device can be efficiently manufactured.

[0011]

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. On both sides of the upper surface connected to the electrodes, there are provided flange portions 4b and 4c whose ridge lines are arcuate. 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 portion (inner end portion) 4e. The second moment of area for bending is increased with less material.

Further, as shown in FIG. 2, the tip end 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, in which 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.

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

First, as shown in FIGS. 1A and 1B, as a base material, a device hole 9 is formed by press working by a push back method on a film 8 made of a synthetic resin such as polyimide or polyester and having a thickness of about 35 to 70 μm. Set up. In the push back method, as shown in (a), a desired portion is first punched out by a pressing die, and then the receiving die is raised again, and (b) as shown in the figure, a device hole 9 is formed by cutting a cutout piece 10 once.
It is a processing method of fitting and holding inside. 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 is formed.
The photoresist layer 12 has a function as a temporary fixing means for preventing the cut-out piece 10 from falling off, and is particularly effective for temporary fixing of a thin material such as a push-backed material that easily falls off. is there.

Next, a peeling treatment is performed on the film 8 with selenious acid, caustic soda, or the like, 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 content of 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.

By removing the resist layer 12 after the electroforming, the lead frame 7 is formed on the entire surface of the conductive base material, and the finger 4 of the lead frame 7 is formed on the cutout piece 10 by the conductive metal. It is retained via the layer 11.

When the cut-out piece 10 which closes the device hole 9 for joining with the semiconductor chip is pulled out, the lead frame 7 having a cross section as shown in FIG. 3G is formed on the synthetic resin film 8. In this case, the conductive metal layer 11 has a thickness such as 5 for providing conductivity for electroforming.
Since the surface of the conductive metal layer 11 on which the lead frame 7 is formed is subjected to a peeling process, the pull-out force is small and the lead frame 7 is not deformed.

After the cut-out piece 10 is pulled out in this way, the semiconductor chip 1 is mounted and connected to the finger 4.

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

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, a photoresist layer 12 is formed on the metal film, and direct electroforming is performed. 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 in the center of the non-resist portion 14 at a position corresponding to the finger 4. 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. 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.

When the metal thin film 4h as shown in FIG. 4 is formed, 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, it is possible to form the lead frame 7 by superposing two layers of 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.

[0032]

As in the first aspect of the invention described above, since the cutout piece is held in the device hole of the base material and the finger portion of the leadframe is held on the cutout piece, the leadframe is removed from other steps. The tip interval of the finger does not shift in the arrangement direction thereof due to external force or impact when it is transferred to or due to winding on a reel, and the pitch interval can be maintained normally. Therefore, as in the conventional case, the fingers are displaced from the electrodes of the semiconductor chip and joined, or the defects such as short-circuiting by contact with the adjacent fingers are effectively eliminated, and a highly reliable semiconductor device is efficiently manufactured. be able to.

Further, according to the above-mentioned second invention, since the conductive metal layer is uniformly formed on the synthetic resin film including the punched pieces, the conductive metal layer can be used in the manufacturing process. It is possible to reliably prevent the punched pieces from falling off.

Further, since the fingers are formed and held on the conductive metal layer supported by the synthetic resin film, external force or impact when transferring the lead frame to another process or winding it on a reel for that purpose is carried out. As a result, the tip end of the finger does not shift in the direction in which it is aligned, and the pitch interval can be normally maintained. Therefore, as in the conventional case, the fingers are displaced and joined to the electrodes of the semiconductor chip,
The drawbacks such as short-circuiting due to contact with adjacent fingers can be effectively eliminated, and a highly reliable semiconductor device can be efficiently manufactured.

[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 4 Finger 4e Tip 7 Leadframe 8 Film 9 Device Hole 10 Cutout Piece 11 Conductive Metal Layer 12 Photoresist Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Eiji Sakata Inventor Eiji Sakata 4680 Ikata, Katshiro-machi, Tagawa-gun, Fukuoka Prefecture Kyushu Hitachi Maxell, Ltd.

Claims (3)

[Claims] 1. A base material having conductivity on at least the surface thereof, a device hole formed at a predetermined position, and a cutout piece fitted and held in the device hole, and a lead frame formed on the base material. 2. The intermediate portion for manufacturing a semiconductor device, wherein the finger portion of the above is held on the cut-out piece. 2. The semiconductor device manufacturing intermediate according to claim 1, wherein the lead frame forming surface of the conductive surface of the base material is peeled off. 3. A push backing step of punching a device hole in a predetermined position of a synthetic resin base material, and fitting and holding a punching piece formed by the punching in the device hole, and the punching step. A step of uniformly forming a conductive metal layer on the synthetic resin film, and a step of forming a lead frame on the conductive metal layer as desired by a finger in the device hole. Manufacturing method of semiconductor device manufacturing intermediate.