JPH09181239A - Manufacture of lead frame and punching die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mass-productivity of a lead frame so as to reduce the cost of the frame. SOLUTION: A punching die which punches and removes a connecting piece between at least part of inner leads and a stage for mounting a semiconductor chip is provided with heating means which are constituted by respectively installing heaters la and 2a to the stripper plate 1 and the die 2 of the die section and punches the connecting piece after heat-treating the piece with the heating means. Therefore, the productivity of a lead frame 100 can be improved and the cost of the frame 100 can be reduced, because no process is required for carrying the lead frame 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame manufacturing method for manufacturing a lead frame using a punching die and a punching die.

[0002]

2. Description of the Related Art A lead frame used in a semiconductor device is manufactured by a punching die forming method, an etching technique forming method, or the like. According to the conventional lead frame manufacturing method using a punching die, stress (strain) remains inside the material due to punching, bending, etc., and the residual stress causes lead shift and lead step problems after punching. , It may lead to product defects.

As a method for solving the problems of the lead shift and the lead step, for example, there is a punching method disclosed in Japanese Patent Publication No. 62-44422. FIG. 3 shows a lead frame 100 used in this punching method. The lead frame 100 has a rectangular stage 101 formed in the center thereof, and the stage 101 has a frame portion 103 via a pair of stage support bars 102 connected to both sides.
It is connected to. Further, connecting pieces 104 are provided on both sides of the lead frame 100 in the longitudinal direction.
The tip ends of a plurality of linear or L-shaped inner leads 105 are radially connected to 04. In addition, a part of the inner lead 105 is provided on the stage support bar 10
It is provided in parallel with 2. The other end of each inner lead 105 is connected to the frame portion 103. Therefore, all the tips of the inner leads 105 are connected to the stage 101 or the connecting pieces 104.

The process for punching until the tip of the inner lead is connected is referred to as step i. After completion of this step i, heat treatment is performed on the lead frame 100 as a step ii. Residual stress can be removed by this heat treatment. Then, in step iii, the connecting piece 104 is punched out and removed, and the lead frame 106 having a shape in which the tips of the inner leads 105 are not connected to the stage 101 or the connecting piece 104 is manufactured.

Further, in Japanese Patent Application Laid-Open No. 3-123062, etc., press working is performed with the connecting portion attached to the tip of the inner lead, and then heat treatment is performed to remove processing strain, and then the connecting portion is formed. The punching method shown in FIG. 3 in the state of step iii is shown.

[0006]

However, in the conventional lead frame manufacturing method, the lead frame 100 is punched out from the die each time the process moves from step i to step ii and from step ii to step iii in FIG. It is very time-consuming because it needs to be taken out and moved to each process. As a result,
There is a limit to improvement in mass productivity (productivity), and a limit to reduction in production cost.

Therefore, an object of the present invention is to provide a method for manufacturing a lead frame and a punching die which can improve the mass productivity while preventing the deformation of the inner leads.

[0008]

In order to achieve the above object, the present invention comprises a connecting piece for connecting at least a part of an inner lead, and a lead frame which is punched and removed after heat treatment. In the method, the inner lead is punched out by removing the connecting piece while heating the inner lead.

According to this method, the lead frame in which the connecting piece is formed can be carried into the punching die, and the heat treatment and the punching process can be continuously performed in this die. As a result, the lead frame is transported. It is possible to improve the workability and shorten the time by reducing the number of. Therefore, mass productivity is improved and cost can be reduced. Further, the above-mentioned object is to hold a lead frame material at a predetermined position in a lead frame punching die for removing a connecting piece formed between at least a part of an inner lead and a stage on which a semiconductor chip is mounted. And a die including a die and a punch, and the die is also provided with a heating part for heating the lead frame material and a punching part for punching out the inner lead. .

The heating unit may be a heater arranged on at least one of the stripper plate and the die. According to this configuration, the heating means can be easily included in the mold part without worrying about the installation space. Further, the heating unit may be composed of a heater provided on a heat treatment stage formed adjacent to the mold unit.

According to this structure, the heat treatment is performed in the space adjacent to the die portion prior to the punching, and after the heat treatment is completed, the lead frame is brought slightly into the die portion and punched. You can Therefore, the waiting time in the die part can be minimized, and the mass productivity can be further improved. In this case, the heat treatment stage may include a second stripper plate and a second die provided on the same plane as the stripper plate and the die, and a heater may be disposed on at least one of the second stripper plate and the second die.

According to this structure, with a simple structure,
It is also possible to construct a punching die by adding it to an existing die. Further, if it is a new design, the degree of freedom in design can be increased.

[0013]

1 is a front sectional view showing an embodiment of a die for punching a lead frame according to the present invention. In the present invention, step ii and step iii in FIG.
Is performed at the same time, and movement (conveyance) of the lead frame is unnecessary. That is, the connecting piece 1 manufactured in step i of FIG.
The lead frame 100 with 04 is set between the stripper plate of the punching die and the die (the punch for punching is the final operation), and the punch is lowered while being heated by the heating means built in the stripper plate and the die. Perform punching. By this heating, the lead frame 100
Punching is performed without residual stress (strain) on the lead frame, and a lead frame conforming to the standard without lead deformation can be manufactured.

As shown in FIG. 1, the lead frame 100 having the structure shown in FIG. 3 is held by a stripper plate 1 and a die 2 each having a trapezoidal shape and a hole corresponding to the outer shape of the punch is formed in the center. The lead frame 100 is disposed between the two. Stripper plate 1
A heater 1a as a heating means is built in so as to face the position of the connecting piece 104 and face the connecting piece. Similarly, the die 2 also has a built-in heater 2a (heating means) facing the position of the connecting piece 104.

The die 2 is supported by the lower holder 3, and the stripper plate 1 is supported by the upper holder 4. Further, columns 5a and 5b are erected on the lower holder 3, and the upper holder 4 is vertically movably engaged with the columns 5a and 5b. The upper ends of the columns 5a and 5b are the lower top plate 6.
Has been fixed by. Further, columnar guides 7 a and 7 b are provided upright on the upper holding tool 4, and the upper end portion thereof penetrates the lower top plate 6. An upper top plate 8 is attached to the upper surface of the lower top plate 6, and holes 9a and 9b are provided in portions of the upper top plate 8 facing the guides 7a and 7b.
Springs 10a and 10b are provided in a and 9b, and their lower ends are in pressure contact with the upper end surfaces of the guides 7a and 7b.

Further, the upper top plate 8 has a columnar support 11
The columns a and 11b penetrate therethrough, and the columns 11a and 11b can be used as guides to move up and down. This pillar 11a,
A bottom plate 12 on which the lower holder 3 is placed is fixed to the lower surface of 11b. A fixed plate 13 is attached to the center of the lower surface of the lower top plate 6, and a punch 14 whose lower half is machined to have a small diameter is attached to the center of the lower plate. It is fitted in the holder 4 and the die 2.

In the above structure, the lead frame 10
0 is set at a predetermined position on the upper surface of the die 2 heated by the heaters 1a and 2a. Then, the upper holding tool 4
Is driven downward by a drive mechanism (not shown), and the lead frame 100 is clamped by the stripper plate 1 and the die 2. When the upper top plate 8 is lowered in this state, the punch 14 is lowered together with the upper top plate 8, the tip of the punch 14 punches out the portion of the connecting piece 104 of the lead frame 100, and a scrap 15 is generated. At the time of punching, since the portion of the connecting piece 104 of the lead frame 100 is sufficiently heated, residual stress does not occur and lead deformation does not occur. The scraps 15 produced by punching enter the die 2, and thereafter, the scraps 15 are deposited in the die 2 every time the number of punches advances, and finally fall into the bottom plate 12.

FIG. 2 is a partial sectional view showing another embodiment of a die for punching a lead frame according to the present invention. In the punching die having the structure shown in FIG. 1, the stripper plate 1 and the die 2 are provided with heating means, and the heat treatment area and the punching area are located at the same place. On the other hand, the punching die shown in FIG. 2 has a conventional die structure. The heat treatment stage 17 is provided adjacent to the punching stage 16 with respect to the punching stage 16.

The heat treatment stage 17 is provided with a die 18 on the bottom plate 12 (the bottom plate 12 in FIG. 1 is enlarged) adjacent to the die 2. The die 18 is set at the same height position and the same thickness as the die 2, and the lead frame 100 is punched from the heat treatment stage 17 by the punching stage 1.
It is possible to punch the heat-treated lead frame 100 simply by moving the lead frame 100 horizontally.

Further, a stripper plate 19 is provided adjacent to the stripper plate 1 at the same height position, and springs 20a, 20b are provided between the stripper plate 19 and the upper top plate 8, and the stripper plate 19 is provided. It is configured so that it can be raised and lowered. And
A heater 18 is provided on the die 18 and the stripper plate 19.
a and the heater 19a are built in.

In the structure shown in FIG. 2, first, the stripper plates 19 and 1 are kept raised, and the lead frame 100 is carried into the heat treatment stage 17 to remove the die 1 from the die 1.
Set on 8. Then, the stripper plate 19 is lowered to be brought into close contact with the lead frame 100. Die 18
Since the stripper plate 19 is heated by the heaters 18a and 19a, heating of the lead frame 100 is started from the time when the lead frame 100 is set. When a predetermined time has elapsed, the stripper plate 19 is raised and the lead frame 100 is horizontally moved toward the die 2.

After the lead frame 100 is set on the die 2, the stripper plate 1 is lowered to press the lead frame 100 against the die 2. After this, punch 1
4 is lowered and the connecting piece 104 is punched out, the process of step iii described in FIG. 3 is completed. According to the mold of FIG. 3, since the lead frame 100 that has been heat-treated in the heat treatment stage 17 is transferred to the punching stage 16 and positioned and fixed by the stripper plate 1, punching can be performed immediately, so that the waiting time can be shortened. The mass productivity can be further improved as compared with the configuration of.

Further, according to the configuration of FIG. 2, since the heater can be used as the heat source and the stripper plate and the die can be used for positioning and fixing the lead frame, the punching die can be added to the existing die. It can be constructed. Further, if it is a new design, the degree of freedom in design can be increased.

[0024]

As is apparent from the above, according to the present invention, the heat treatment is performed in the die for punching the connecting piece, and the connecting piece is punched immediately after the completion of the heat treatment. The number of steps for transporting the frame is reduced, workability can be improved and time can be shortened. Therefore, mass productivity is improved and cost can be reduced.

Further, according to the present invention, a heating means for heating the lead frame is integrally provided to a die part including a stripper plate for positioning and holding the lead frame, a die and a punch. Therefore, the heat treatment for the lead frame set in the mold part and the subsequent punching process can be performed at the same place, and it is not necessary to carry the lead frame for these processes. As a result, mass productivity can be improved and cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a die for punching a lead frame according to the present invention.

FIG. 2 is a partial cross-sectional view showing another embodiment of a die for punching a lead frame according to the present invention.

FIG. 3 is an explanatory view showing a manufacturing process of a conventional lead frame.

[Explanation of symbols]

 1, 19 Stripper plate 2, 18 Die 1a, 2a, 18a, 19a Heater 14 Punch 16 Punching stage 17 Heat treatment stage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kunio Nakagawa, 3-1-1 Sukegawa-cho, Hitachi-shi, Ibaraki Hitachi Cable Company, Ltd. (72) Kosuke Sato 3-1-1, Sukegawa-cho, Hitachi, Ibaraki No. 1 in the electric wire factory of Hitachi Cable, Ltd.

Claims (5)

[Claims] 1. A method for manufacturing a lead frame, comprising: a connecting piece for connecting at least a part of an inner lead, wherein the connecting piece is punched and removed after heat treatment, wherein the connecting piece is removed while heating the inner lead. A method of manufacturing a lead frame, comprising punching out the inner lead. 2. A die for punching a lead frame for removing a connecting piece formed between at least a part of an inner lead and a stage on which a semiconductor chip is mounted, wherein a lead frame material is held at a predetermined position. A die including a stripper plate for punching out leads, a die and a punch, wherein the die includes a heating part for heating the lead frame material and a punching part for punching out the inner leads. Punching die. 3. The punching die for a lead frame according to claim 2, wherein the heating portion is a heater disposed on at least one of the stripper plate and the die. 4. The punching die for a lead frame according to claim 2, wherein the heating portion is a heater provided on a heat treatment stage formed adjacent to the die portion. 5. The heat treatment stage includes a second stripper plate and a second die provided on the same plane as the stripper plate and the die, and the heater is disposed on at least one of the second stripper plate and the second die. The punching die for a lead frame according to claim 4, wherein.