JPH0685129A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To produce a semiconductor device with high reliability at low cost, by selectively using a supporting bar in accordance with a structure of a semiconductor chip. CONSTITUTION:A lead frame 20 made up of a lead 21, a stage 22 and a support bar 23 is formed by punching a base material made of a ferro-alloy like a 4-2 ferro-alloy or a copper alloy like MF-202, with a die in a press machine. Out of a plurality of support bars 23a and 23b, those other than a support bar that meets to a semiconductor chip 24 mounted on the stage 22 are selectively cut and removed. The productive cost for the semiconductor device doesn't increase by adding a simple support bar cutting step, and the overall cost can be reduced remarkably as compared with a conventional case, in which each die should be formed according to the shape of lead frames.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device having a lead frame forming step.

In general, a semiconductor device having a plastic package is manufactured by mounting a semiconductor chip after forming a lead frame, wire-bonding it, resin-molding it to form a plastic package, and then performing a lead molding process and the like. ing.

Further, in recent years, there has been a strong demand for cost reduction of semiconductor devices, and efficiency is being promoted in each manufacturing process of semiconductor devices.

Therefore, it is desired to reduce the product cost by improving the efficiency in the lead frame manufacturing process.

[0005]

2. Description of the Related Art FIG. 10 is a sectional view of a general semiconductor device 1. This semiconductor device 1 has a QFP (Quad Flat Pckag).
e) It is called a type. In the figure, 2 is a semiconductor chip, 3 is a stage to which a semiconductor element is attached,
4 is a lead, 5 is a support bar that supports the stage 3,
Reference numerals 6 denote plastic packages (shown in satin), respectively.

The semiconductor chip 2 is protected by being sealed in a plastic package 6. The lead 4 is composed of an inner lead 8 and an outer lead 9, the inner lead 8 is wire-bonded to the semiconductor chip 2, and the outer lead 9 is extended from the package 6 to the outside to be connected to an external circuit. Has become. Further, the support bar 5 is joined to, for example, four corner positions of the stage 3 according to the structure of the semiconductor chip 2 and has a function of supporting the stage 3 arranged in the central portion. In the above structure, the stage 3, the lead 4, and the support bar 5 are integrally treated as a lead frame in the middle of the manufacturing process of the semiconductor device 1.

Next, a method of manufacturing the semiconductor device 1 having the above structure will be described. The manufacturing process of the semiconductor device 1 roughly includes a lead frame forming process, a chip mounting process, a package forming process, a lead forming process, and the like.

In the lead frame forming step, a lead frame having lead 4, stage 3, support bar 5 and the like shown in FIG. 11 is formed by punching a lead frame base material with a die using a press machine. Form. Reference numeral 7 in the figure is a cradle, and the lead 4, stage 3, and support bar 5 are the cradle 7.
, The lead 4, the stage 3, and the support bar 5 can be integrally handled.

11 and 12 show conventional lead frames 10 and 11. The lead frame 10 shown in FIG. 11 has a configuration in which the four corner positions of the stage 3 are supported by four support bars 5a to 5d. Further, the lead frame 11 shown in FIG. 12 shows a structure in which the center position of the stage 3 is supported by two support bars 5e and 5f.

As shown in each figure, the support bar 5a
Various arrangement numbers and arrangement positions of 5f are provided, and the number and arrangement positions of the 5f to 5f are determined by the structure of the semiconductor chip 2 mounted on the stage 3 (for example, the number of pads to be wire-bonded or Position).

When the lead frame forming step is performed as described above, the chip mounting step is subsequently performed. In the chip mounting process, the semiconductor chip 2 is mounted on the stage 3 supported by the support bars 5a to 5f as described above. Subsequently, wire bonding is carried out, and the semiconductor chip 2
A wire is connected between the pad formed on the wire and the lead 4.

When the lead frame forming step is completed, the lead frame 10 on which the semiconductor chip 2 is mounted,
A package forming step of forming a package 6 for resin-sealing the semiconductor chip 2 by performing a resin molding process on 11 is performed.

Subsequently, a lead forming step of removing unnecessary portions of the lead frames 10 and 11 such as the cradle 7 and forming the lead 4 (outer lead 9) into a predetermined shape is carried out, and the above series of steps are performed. The semiconductor device 1 was manufactured by.

[0014]

As described above, various numbers and positions of the support bars 5a to 5f are provided, and the numbers and positions of the support bars 5a to 5f are mounted on the stage 3. It is set according to the structure of the semiconductor chip 2.

Conventionally, when the semiconductor chips to be mounted are determined and the number and positions of the support bars are determined, molds corresponding to the numbers and positions of the support bars are manufactured,
A lead frame has been formed using this mold.

However, there is a problem that the cost required for manufacturing the die is great, and the die cost raises the product cost and the cost of each semiconductor device rises.

Further, in order to suppress the cost increase due to the die cost, various semiconductor chips are forcibly arranged for one type of lead frame.
In this case, although the product cost can be reduced, the number of support bars and the positions of the support bars are not adapted to the semiconductor chip, which causes inconveniences such as easy occurrence of a short circuit of the wire, and the reliability of the semiconductor device is reduced. There is a problem that it will decrease.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of reducing the product cost while maintaining high reliability.

[0019]

The above-mentioned problem is solved by punching a base material to form a lead to which a wire is connected,
A lead frame forming step of forming a lead frame having a stage on which a semiconductor chip is mounted and a plurality of support bars supporting the stage, and among the plurality of support bars, only a support bar suitable for the mounted semiconductor chip And a support bar cutting step of selectively cutting and removing other support bars, and a chip mounting step of mounting the semiconductor chip on the stage and connecting the pads and leads of the semiconductor chip by wire bonding. A package forming step of performing a resin molding process on the lead frame on which the semiconductor chip is mounted to form a package for resin-sealing the semiconductor chip, removing unnecessary portions of the lead frame, and forming the lead into a predetermined shape. And a lead forming step of forming It can be solved by the manufacturing method of the body device.

Further, in the support bar cutting step, the support bar to be cut and removed can be effectively solved by cutting the support bar so that it has substantially the same shape as the lead after cutting.

Further, the support bar cutting step can be effectively solved by using a simple press.

[0022]

According to the invention of claim 1, in the lead frame forming step, a plurality of support bars are formed by one die, and in the subsequent support bar cutting step,
Only the support bars suitable for the mounted semiconductor chips are left, and the other support bars are selectively cut and removed. Therefore, it is not necessary to raise the mold for each semiconductor chip to be mounted in the lead frame forming step, so that the product cost can be reduced. Further, in the support bar cutting step, unnecessary support bars are removed, and only the support bars suitable for the semiconductor chip to be mounted are left, so that there is no problem such as wire short circuit and the like. The reliability can be improved.

According to the second aspect of the present invention, the support bar cut and removed in the support bar cutting step is cut so as to have substantially the same shape as the lead after cutting, so that the cut support bar serves as a lead. It can be used, and the degree of freedom in wiring the wire can be improved.

According to the third aspect of the invention, the support bar cutting step is performed by using a simple press which is inexpensive in equipment cost, so that the product cost of the semiconductor device can be further reduced.

[0025]

Embodiments of the present invention will now be described with reference to the drawings.

The semiconductor device manufacturing method according to the present invention is, as shown in FIG. 1, roughly, a lead frame forming step (P1), a support bar cutting step (P2), a chip mounting step (P3), and a package forming step (P3). P4), the lead forming step (P5) and the like. Among these steps, the lead frame forming step (P1) and the support bar cutting step (P2) are the features of the method of the present invention, and the other step P3.
~ P5 is a step of performing well-known processing similar to the conventional one. Therefore, the processes of the lead frame forming step (P1) and the support bar cutting step (P2) will be described in detail, and only the main parts of the steps similar to the conventional one will be described.

First, the lead frame forming step (P1) will be described. This lead frame forming step (P1)
For example, by punching a base material made of an iron alloy such as 42 alloy or a copper alloy such as MF-202 with a die using a press machine, the lead 21, the stage 22,
And a step of forming the lead frame 20 having the support bar 23 and the like. FIG. 2 shows a lead frame 20 formed by the method of the present invention.

In this embodiment, eight support bars 23 are formed in total (indicated by reference numerals 23a to 23h). As shown in FIG. 11, for example, the number of support bars 5 in the related art is at most 4 (5a to 5d), and is determined by the shape of the mold used in the lead frame forming step. Therefore, when it is attempted to form the lead frame 11 including the two support bars 5e and 5f as shown in FIG. 12, it is necessary to create a mold different from the mold for forming the lead frame 10 shown in FIG. As described above, this is the reason why the product cost of the semiconductor device is increased.

In the present invention, the support bars 23a to 23h formed as described above are not all used as support bars, but the semiconductor chip 24 mounted on the stage 22 in the subsequent chip mounting step (P3) (see FIG. 6). , 7)), the support bars 23a to 23h are selectively used.

In FIG. 2, reference numeral 25 is a cradle, and the lead 21, the stage 22, and the support bars 23a to 23h are integrally connected to the cradle 25, and thus the lead 21, the stage 22. ，
The support bars 23a to 23h can be handled integrally.

After the lead frame 20 is formed as described above, the support bar cutting step (P2) is subsequently performed. In this support bar cutting step (P2), among the plurality of support bars 23a to 23h formed as described above, only the support bar adapted to the semiconductor chip 24 mounted on the stage 22 is left and the other support bars are replaced. Cut off selectively. As a device for performing this cutting process,
Since it suffices to have a function of selectively cutting the thin support bars 23a to 23h, it is possible to carry out, for example, a simple press working at a low equipment cost.

Therefore, by providing the support bar cutting step (P2), the product cost of the semiconductor device does not increase, but rather the mold is individually manufactured according to the shape of the lead frame unlike the conventional case. The cost can be significantly reduced as compared with the cost required in some cases.

3 and 4 show examples of cutting the support bar. As described above, the support bar to be cut is determined by the structure of the semiconductor chip 24 to be mounted. The lead frame 20-1 shown in FIG. 3 leaves the support bars 23b and 23f, and other support bars 23a and 23f.
23c-23e, 23g, and 23h are removed. The lead frame 20-2 shown in FIG. 4 has support bars 23a, 23 located at the four corners of the stage 22.
c, 23e, 23g are left, and other 23b, 23d, 23
f and 23h are removed. Further, the lead frame 20-3 shown in FIG. 5 is one in which the support bars 23a, 23c, 23f are left so as to support the stage 22 at three places, and the other 23b, 23d, 23e, 23g, 23h are removed. .

In this way, the semiconductor chip 24 to be mounted is mounted.
8 support bars 23a-2 to adapt to the structure of
A support bar to be left or a support bar to be removed can be arbitrarily selected from 3h.

The structure of the semiconductor chip 24 here means the shape and size of the semiconductor chip 24, the number of pads (electrode pads for wire bonding) provided,
Refers to the position etc. Further, the removal of the support bars 23a to 23h means that not all the support bars 23a to 23h are removed from the lead frame 20, but a part joined to the stage 22 is removed.

Here, paying attention to the shape of the support bars 23a to 23h, the shape of each of the support bars 23a to 23h is similar to that of the lead 21 arranged adjacently. Further, as described above, in a state where a part of the lead 22 joined to the stage 22 is removed, the lead 21 has substantially the same shape and has the same function as the lead. That is, the removed support bars 23a to 23h
Acts as a lead. Therefore, the support bars 23a to 23h after cutting and removal can be used as leads, and the degree of freedom of wiring of wires connecting the leads and the semiconductor chip 24 can be improved.

When the above-mentioned cutting process of the saute bar (P2) is completed, the chip mounting process (P3) is carried out. In the chip mounting step (P3), the semiconductor chip 24 is first mounted and fixed on the stage 22, and then the semiconductor chip 24 is mounted.
A wire bonding process is performed between the pad formed on the upper surface of the substrate and the lead 21 (including the cut support bar), and the semiconductor chip 24 and the lead 21 are electrically connected by the wire 26. FIG. 7 shows a state in which the wire 26 is connected.

During the bonding process of the wire 26,
As shown in FIG. 6, due to the structure of the semiconductor chip 24, the pads 27 are arranged in proximity to the corners thereof, and in the structure in which the support bar 23g is arranged at the corners, the pads 27 and the leads 2 are provided.
Since the wire 26 is obliquely wired between the wire 26 and the wire 1, the wiring of the wire 26 becomes difficult. If the wiring is forcibly performed, a short circuit may occur between the adjacent wires 26, or the wires 26 may be broken by the molding resin in the packager forming step (P4) performed later.

However, as described above, according to the method of the present application, the plurality of support bars 23a to 23h are formed in the lead frame forming step (P1), and the structure of the semiconductor chip 24 is formed in the subsequent support bar cutting step (P2). The support bars 23a-23h can be selected to accommodate.

In the example shown in FIG. 6, the support bar 23g is removed in the support bar cutting step (P2), and the support bar 23f located at a position where the pitch of the pads 27 is relatively large is shown in FIG. By leaving the structure, the wiring of the wires 26 at the corners of the semiconductor chip 24 can be configured without difficulty. This is the removed support bar 23g
Acts as a lead.

Therefore, it is possible to reliably prevent a short circuit between the adjacent wires 26 and disconnection of the wires 26 in the resin molding process to be performed later, and the yield and reliability of the manufactured semiconductor device are improved. Can be improved.

When the chip mounting process (P3) is completed as described above, the package forming process (P4) is subsequently performed. In the package forming step (P4), as shown in FIG. 8, the lead frame 20 on which the semiconductor chip 24 is mounted is mounted on the mold die 28, and the package 29 is filled with the mold resin to form the package 29. Form. In this resin molding process, since the wiring of the wire 26 is not unreasonable as described above, disconnection does not occur.

When the package forming step (P4) is completed and the semiconductor chip 24 is sealed by the package 29,
The lead frame 20 on which the package 29 is formed is released from the mold 28, and then the lead forming step (P5) is performed. In the lead forming step (P5), burrs generated during resin molding are removed, and then the leads 21 (outer leads) extending outside from the package 29 are formed into a predetermined shape, for example, a gull wing shape. The semiconductor device 30 shown is manufactured.

In the above embodiments, the structure of the semiconductor device has been described by taking the QFP (Quad Flat Pckage) type as an example, but the method of the present invention can be applied to semiconductor devices having other structures. Is.

In this embodiment, the number of support bars is eight, but the number of support bars can be appropriately selected according to the structure of the semiconductor device to be manufactured.

Further, although the lead frame is formed by pressing in the above embodiment, the lead frame can be formed by another method such as etching.

[0047]

As described above, according to the present invention, the following various effects are exhibited.

According to the first aspect of the present invention, in the lead frame forming step, a plurality of support bars are formed by one die, and in the subsequent support bar cutting step, the support bar suitable for the semiconductor chip to be mounted is formed. Only the remaining support bars are selectively removed by cutting. Therefore, it is not necessary to raise the mold for each semiconductor chip to be mounted in the lead frame forming step, so that the product cost can be reduced. Further, in the support bar cutting step, unnecessary support bars are removed, and only the support bars suitable for the semiconductor chip to be mounted are left, so that there is no problem such as wire short circuit, and the semiconductor device The reliability can be improved.

According to the second aspect of the present invention, the support bar cut and removed in the support bar cutting step is cut so as to have substantially the same shape as the lead after cutting, so that the cut support bar serves as a lead. It can be used, and the degree of freedom in wiring the wire can be improved.

According to the third aspect of the present invention, the support bar cutting step is performed by using the simple press which is inexpensive in equipment cost, whereby the product cost of the semiconductor device can be further reduced.

[Brief description of drawings]

FIG. 1 is a process drawing of the method of the present invention.

FIG. 2 is a diagram showing a lead frame formed in a lead frame forming step.

FIG. 3 is a diagram showing an example of a lead frame processed in a support bar cutting step.

FIG. 4 is a view showing an example of a lead frame processed in a support bar cutting step.

FIG. 5 is a diagram showing an example of a lead frame processed in a support bar cutting step.

FIG. 6 is a diagram for explaining a chip mounting process.

FIG. 7 is a diagram for explaining a chip mounting process.

FIG. 8 is a diagram for explaining a package forming process.

FIG. 9 is a diagram showing an example of a manufactured semiconductor device.

FIG. 10 is a diagram showing a cross-sectional structure of a semiconductor device.

FIG. 11 is a diagram showing an example of a lead frame used in a conventional manufacturing method.

FIG. 12 is a diagram showing an example of a lead frame used in a conventional manufacturing method.

[Explanation of symbols]

 20, 20-1 to 20-2 Lead frame 21 Lead 22 Stage 23, 23a to 23h Support bar 24 Semiconductor chip 25 Credor 26 Wire 27 Pad 28 Mold 29 Package 30 Semiconductor device

Claims (3)

[Claims] 1. A substrate is punched to support a lead (21) to which a wire (26) is connected, a stage (22) on which a semiconductor chip (24) is mounted, and the stage (22). Multiple support bars (23a-
23h) forming a lead frame (20) having a lead frame (20), and leaving only a support bar suitable for the semiconductor chip (24) to be mounted among the plurality of support bars (23a to 23h), Support bar cutting step of selectively cutting and removing the support bar of step (a), the semiconductor chip (24) is mounted on the stage (22), and the pad (27) of the semiconductor chip (24) and the lead (21) And a chip mounting step for connecting the semiconductor chip (24) by wire bonding, and a package for resin-sealing the semiconductor chip (24) by resin-molding the lead frame (20) on which the semiconductor chip (24) is mounted. 29), a package forming step is performed, unnecessary portions of the lead frame (20) are removed, and the leads (21) are formed in a predetermined shape. And a lead forming step of forming into a shape. 2. The semiconductor device according to claim 1, wherein, in the support bar cutting step, the support bar to be cut and removed is cut so as to have substantially the same shape as the lead (21) after cutting. Device manufacturing method. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the support bar cutting step is performed using a simple press.