JP3028167B2 - Lead frame manufacturing method and lead frame manufacturing apparatus - Google Patents

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 lead frame and a mold apparatus used for the method, and more particularly to a mold structure thereof.

[0002]

2. Description of the Related Art Along with miniaturization and high integration of a semiconductor device, a lead frame used for assembling the semiconductor device having a lead number exceeding 200 pins has been proposed.

In such a die apparatus for punching a multi-pin lead frame, the number of punching stations is increased, and the load of the press is also increased. Are sequentially processed via

[0004]

However, in today's high-mix low-volume production, the production of the lead frame required for the expensive mold apparatus before the end of its life is completed.
There has been a problem that the mold price per product is high, and the product price is soaring.

In order to solve this problem, a method has been proposed in which a lead frame is divided by a symmetrical axis having its planar shape, and each divided portion is formed using the same mold (Japanese Patent Publication No. 62-35270). issue). in this way,
Since each portion is punched, stress is locally applied, and distortion and deformation are likely to occur. This is a serious problem particularly in the case of a high-density pattern. In particular, as the number of pins increases, the pitch between the inner leads becomes smaller, the manufacturing technique becomes more difficult, the tip of the inner lead is more likely to be deformed, and the distance between the inner lead tip and the semiconductor chip becomes longer. There is also a problem that it is deformed and short-circuited during molding.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a low-cost and highly reliable manufacturing method of a lead frame which hardly causes distortion or deformation.

[0007]

Therefore, according to the method of the present invention, a mold configured to form almost every other inner lead in one lead frame unit pattern is placed in a mold.
The strip material is supplied from a first reel installed in the strip material supply unit, and the first group is sequentially punched while being wound on a second reel installed in the strip material winding unit, and the strip material is wound. After that, the second reel is installed again in the strip material supply section, the strip material is supplied into the mold, and the second reel is taken up by the third reel installed in the strip material winding section. The punching is performed sequentially.

Further, in the method of the present invention, the inner leads in one lead frame unit pattern are installed at the strip material supply portion in a mold configured so as to be formed at intervals of a plurality of leads so as to be substantially uniform over the whole. The first group is supplied from the set first reel, and the first group is sequentially punched while being wound on the second reel provided in the strip winding section. After the first group is wound, the second group is wound again. Is installed in the strip supply section, the strip is supplied into the mold, and the second group is sequentially punched while being wound on a third reel installed in the strip winding section. Rotating the mold by a predetermined angle, installing the third reel again in the strip supply section, supplying the strip in the mold, and setting the third reel in the strip winding section. The third group is punched sequentially while being wound up. Characterized in that so as to sequentially perform a predetermined times of punching as.

Further, in the lead frame manufacturing apparatus of the present invention, a die configured to form almost every other inner lead in one lead frame unit pattern, and a first die installed in a strip material supply section. From the reel of
The first group is sequentially punched while being wound on a second reel installed in the strip winding section, and after winding the strip, the second reel is installed again in the strip supply section and the gold is removed. Supplying the strip into the mold, and installing the third strip at the strip winding section
And a strip material supply mechanism configured to sequentially perform punching of the second group while winding on a reel. Furthermore, in the lead frame manufacturing apparatus of the present invention, the inner leads in one lead frame unit pattern are divided into a plurality of groups so as to be substantially equally rotationally symmetric, and the inner leads for one group are formed. A configured die, a die rotation mechanism for rotating the die by an angle that is rotationally symmetric, and a strip supplied from a first reel installed in the strip supply unit, and fed to a strip winding unit. The first group is sequentially punched out while being wound on a second reel installed, and after winding the strip, the second reel is installed again in the strip supply section and the strip is placed in the mold. And a strip supply mechanism configured to sequentially perform punching of the second group while winding on a third reel installed in the strip winding section.

[0010] Here, the reason that the inner leads are arranged approximately every other line is, in principle, every other line. However, due to the symmetry, even if there is a region that is not every other line, It means good.

[0011]

According to the above method, the sequence is symmetrical,
The inner leads are divided into two groups so as to be formed almost every other line, and are punched out sequentially using a mold configured to form the other group. Since a uniform force is applied without applying local stress as in the case of punching, a high-density pattern can be formed at low cost without causing distortion or deformation. Here, the pattern density of the mold is
Since only half the pattern density of the lead frame pattern as a finished product is required, the formation of the mold is easy and the cost is low. In addition, it can be formed only by repeating a normal winding process twice without moving the mold, and is extremely easy to form.

According to the second method, it is possible to form a lead frame which takes a long time but has less distortion and deformation, and furthermore, the cost of the mold is reduced.

[0013] The equipment is low cost.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing a lead frame of an embodiment of the present invention, FIG. 2 is a view showing a manufacturing process of the lead frame, and FIG. 3 is an explanatory view showing a lead frame manufacturing apparatus of the embodiment of the present invention. .

The lead frame has a plurality of inner leads 2 extending radially from the periphery of the die pad 1 and outer leads 3 extending integrally from the inner leads and integrally formed. 4 is a support bar, 5 is a tie bar,
6 is a side bar.

Further, the lead frame manufacturing apparatus includes a die apparatus 100a composed of a die and a punch configured to form almost every other inner lead in one lead frame unit pattern; The die material is supplied from a die device 100b formed of a die and a punch formed so as to punch out the cavity region 8 therebetween, and the first reel 201 installed in the material supply portion 200, and the material winding portion is provided. The first group is sequentially punched while being wound on the second reel 202 installed on the second reel 300, and after the strip is wound, the second reel 202 is again formed.
Is installed in the strip material supply unit 200, the strip material is supplied into the mold apparatus 100, and the second group is sequentially punched while being wound on a third reel 203 installed in the strip material winding unit 300. Strip supply control device 40 configured to perform
0.

Next, a method of manufacturing the lead frame will be described.

First, a strip material made of a copper alloy wound on a first reel 201 is set in a strip material supply section 200 by a stamping method, and a die and a punch of a mold apparatus 100 are set. It is wound around the second reel 202 while punching the inter-lead area 7a every other time. FIG. 2A shows a punched area in this step.

In this manner, punching is performed over the entire length of the strip, and when the strip is completely wound on the second reel 202,
The second reel 202 is set on the strip material supply unit 200, and the die and the punch of the mold apparatus 100 used in the above step are again used without being moved, while punching the inter-lead region 7b every other ( FIG. 2 (b) shows a punched area in this step), and a cavity area 8 between the tip of the inner lead and the die pad 1 is punched further downstream (FIG. 2 (a) shows a punched area in this step). ), And take up the third reel 203.

The lead frame thus shaped is subjected to a treatment such as noble metal plating to obtain a lead frame as shown in FIG.

Further, the semiconductor chip is fixed on the die pad 1 which is the semiconductor element mounting portion, and is connected to the inner lead 2 of the lead frame main body portion and the bonding pad of the semiconductor chip via a wire by a wire bonding method.

Thereafter, a semiconductor device is completed through a molding step, a cutting step of the frame, and a molding step of folding the outer lead into a desired shape.

This lead frame is divided into two groups so that the inner leads are formed almost every other so that the arrangement is symmetrical, and a mold configured to form one of the groups is formed. , So that a uniform force is applied without applying local stress as in the case of punching out every part, so that distortion and deformation do not occur, and low cost and high cost A density pattern can be formed. Here, since the pattern density of the mold may be half the pattern density of the lead frame pattern as a finished product, the cost of the mold is greatly reduced.

Further, it can be formed only by repeating the usual winding step twice without moving the mold, and the formation is extremely easy.

Next, as a second embodiment of the present invention, an inter-lead area is formed so as to form approximately every third lead in one lead frame unit pattern, and the lead frame is completed by punching four times. An example will be described.

In this example, as shown in FIG. 4, punching is performed so as to form a lead-to-lead area so that almost every third lead is formed. After punching out the area between the leads at the point symmetrical position, the die is rotated by 90 degrees, the reel that has been wound up again is placed on the strip supply section, and the lead is rotated by 90 degrees. By punching the area, setting the reel wound up with the mold as it is again in the strip supply section, and punching the area between the leads at the point symmetric position,
A lead frame having a lead spacing of four times the density with the mold is formed.

FIG. 5 shows a lead frame manufacturing apparatus used here. The device is the same as that shown in FIG. 2 except that the pattern of the mold is different and a rotating device 500 is added.

In this apparatus, a die apparatus 100 composed of a die and a punch, which is formed so that inner leads in one lead frame unit pattern are formed approximately every third lead.
c, a die apparatus 100b formed of a die and a punch formed so as to punch out the cavity region 8 between the tip of the inner lead and the die pad 1, and a first reel 201 installed in the strip material supply unit 200. The material is supplied, the first group is sequentially punched while being wound on the second reel 202 provided on the strip winding section 300, and after the strip is wound, the second reel 202 is again moved to the strip. The third reel 203 installed in the material supply unit 200 and supplies the strip material into the mold apparatus 100, and the third reel 203 installed in the strip material winding unit 300.
A strip material supply control device 400 configured to sequentially perform the punching of the second group while being wound up, and a mold rotating device 500.

Next, a method of manufacturing the lead frame will be described.

First, a strip-shaped material made of a copper alloy spread on the first reel 201 is set in the strip material supply section 200 by a stamping method, and a die and a punch of the mold apparatus 100 are set and every three pieces are set. The first reel 202 is wound around the second reel 202 while punching the inter-lead area 17a. FIG. 4A shows a punched area in this step.

In this way, when the entire length of the strip is punched and completely wound on the second reel 202,
This second reel is set in the strip material supply unit 200, and the die and punch of the mold apparatus 100 used in the above step are again used without moving, and the inter-lead area 17b is punched out every other reel (FIG. 4 (b) shows a punched area in this step), and is wound around a third reel 203.

Further, the mold is moved to 90 by the rotating device 500.
After the rotation, the third reel 20 is
3 and the die and the punch of the mold apparatus 100 are installed, and the lead 17
While c is punched, it is wound around the second reel 202 (FIG. 4C shows a punched area in this step).

In this way, when the entire length of the strip is punched and completely wound on the second reel 202,
This second reel is set in the strip material supply unit 200, and the die and punch of the mold apparatus 100 used in the above step are again used without moving, while punching the lead-to-lead area 17d every other (see FIG. 4 (d) shows the punched area in this step), and further punches the cavity area 18 between the tip of the inner lead and the die pad 1 on the downstream side (FIG. 4 (e) shows the punched area in this step). , Third
The reel 203 is wound up.

The lead frame thus shaped is subjected to a treatment such as precious metal plating to obtain a lead frame as shown in FIG.

The inner lead of the lead frame formed by punching a plurality of times as described above has a reduced stress and requires less deformation. Further, when the chip is mounted on the lead frame, the bonding pad of the chip and the inner pad are not used. -Due to the heat history in the wire bonding process with the tip of the lead and the heat history in the molding process, the tip of the inner lead is fixed at the correct position, so there is no connection failure and reliability Semiconductor device with high reliability can be obtained.

In the above-described embodiment, the case where the punching is performed twice and four times with one die has been described.
The number can be changed as appropriate, such as eight times. The rotation angle of the rotation device is selected depending on the case.

[0038]

As described above, according to the present invention, a low-cost and highly reliable semiconductor device can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing a lead frame of a lead frame obtained by a method according to an embodiment of the present invention.

FIG. 2 is a lead frame manufacturing apparatus.

FIG. 3 is an explanatory view showing a lead frame manufacturing process according to the first embodiment of the present invention.

FIG. 4 is an explanatory view showing a lead frame manufacturing process according to a second embodiment of the present invention.

FIG. 5 is a lead frame manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die pad 2 Inner lead 3 Outer lead 4 Support bar 5 Tie bar 6 Side bar 7a Punching area between leads 7b Punching area between leads 8 Cavity punching area 100 Die apparatus 200 Strip supply section 201 First reel 202 Second reel 203 Third reel 300 strip take-up section 400 strip supply control device 500 rotating device

Claims (4)

(57) [Claims] 1. A strip material is supplied from a first reel installed in a strip material supply unit into a mold configured to form inner leads in one lead frame unit pattern approximately every other. A first punching step of sequentially punching a first group while winding the second reel provided on the strip winding section; and winding the second reel again on the strip after winding the strip. A second punching step of setting the material in the material supply unit, supplying the material into the mold, and sequentially punching a second group while winding the material on a third reel provided in the material take-up unit; A method for manufacturing a lead frame, comprising: 2. A first reel mounted on a strip supply section in a mold configured to form inner leads in one lead frame unit pattern at intervals of a plurality of lines so as to be substantially uniform over the entirety. And a first punching step in which the first group is punched while the first group is being punched while being wound on a second reel provided in the strip winding section. A second reel, in which a reel is set in the strip supply section, the strip is supplied into the mold, and the second group is sequentially punched while being wound on a third reel installed in the strip winding section. A punching step and a rotation step of rotating the mold by a predetermined angle, and the third reel is again installed in the strip supply section, the strip is supplied into the mold, and installed in the strip winding section. The third group is driven while being wound on the third reel. And a third punching step of sequentially performing punching. 3. A die configured to form substantially every other inner lead in one lead frame unit pattern, a strip supply section, a strip take-up section, and a strip installed in the strip supply section. The strip is supplied from the first reel, and the first group is sequentially punched while being wound on the second reel provided in the strip winding section. After the strip is wound, the second reel is again taken up Is installed in the strip material supply section, the strip material is supplied into the mold, and the second group is sequentially punched while being wound on a third reel installed in the strip material winding section. A lead frame manufacturing apparatus, comprising: 4. A mold configured to divide inner leads in one lead frame unit pattern into a plurality of groups so as to be substantially equally rotationally symmetric, and to form one group of inner leads. A mold rotating mechanism that rotates the mold by an angle that is rotationally symmetric; and a second material that supplies a material from a first reel installed in the material supply unit and is installed in a material winding unit. The first group is punched while being wound on a reel, and after winding the strip, the second reel is installed in the strip supply section again, and the strip is supplied into the mold. A lead frame manufacturing apparatus comprising: a strip material supply mechanism configured to sequentially perform punching of a second group while winding on a third reel installed in a winding unit.