JP2684247B2 - Lead frame manufacturing method - Google Patents

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, and more particularly to a lead frame manufacturing method using a punching method.

[0002]

2. Description of the Related Art Shape processing of a lead frame used for assembling a semiconductor device is roughly classified into an etching method and a press processing (stamping method) using a progressive die.

When the stamping method is used to perform shape processing, the stamping method is usually performed sequentially as shown in FIGS. 4 (a) and 4 (b).

That is, first, as shown in FIG. 4 (a), the side edges of the inner lead 2 and the outer lead 3 are punched out from the strip-shaped material 1, and then the tip end portion is cut as shown in FIG. 4 (b). The cavity area 4 is punched out to obtain a lead frame.

In recent years, in the field of semiconductor devices, there is an increasing tendency for a small amount and a wide variety of products, and the pad sizes are also diversifying accordingly.

If the lead frame is to be formed by the stamping method in such a situation, there is a problem that various types of dies are required and the cost is increased.

[0007]

As described above, the conventional method has a problem that various types of molds are required because of the necessity of forming lead frames of various kinds in small quantities, and the cost increase cannot be avoided. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a lead frame which can be used for manufacturing a large number of lead frames in small quantities.

[0009]

Therefore, in the present invention, after the inner lead side edge is punched out, the inner leads are connected to each other by taping through plating or the like, and the leading end portion of the inner lead is formed by punching out the cavity region. After that, the semiconductor element mounting portion is fixed via a tape that connects the inner leads to each other.

[0010]

According to the above-mentioned method, the die can be formed by the same die without depending on the chip size up to the punching of the cavity region. That is, it is sufficient to punch the inner lead side edge using the same die and prepare the die corresponding to the chip size for the first time in the cavity region punching process. Therefore, the die cost can be reduced.

Furthermore, from punching of the inner lead side edge to taping, all can be performed with the same die without depending on the chip size.
If the steps up to this step are performed, it is sufficient to punch out the cavity region and fix the semiconductor element mounting portion after the order is received, and the period from the order to the delivery can be greatly shortened.

In addition, since the support bar is unnecessary,
The lead occupying area can be increased accordingly, and the number of leads or the lead pitch can be increased.

[0013]

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

1 (a) to 1 (c) are views showing a manufacturing process of a lead frame of an embodiment of the present invention.

First, as shown in FIG. 1 (a), a strip-shaped material 11 called an alloy 42 is placed in a progressive die, and side edges of the inner leads 12 and the outer leads 13 are sequentially formed.

After forming the side edges of the inner leads and the outer leads in this way, noble metal plating is performed. Here, coining is carried out by preparing a necessary type of mold in accordance with the lead tip removal dimension, that is, the chip size, and selecting and using it as necessary. When the chip size is large, coining is unnecessary. Moreover, you may perform an annealing process as needed.

After that, taping is performed on the back surface of the inner leads using a polyimide double-sided tape T to connect the inner leads to each other. Then, with the inner leads thus connected to each other, as shown in FIG. 1B, the cavity region C is punched out in accordance with the chip size to form the lead frame body 14.

Finally, as shown in FIG. 1 (c), a heat spreader 1 as a semiconductor device mounting portion is formed by punching out a copper plate having a good heat dissipation property in advance.
5 is attached to the back surface of the double-sided tape T to complete the lead frame.

FIG. 2 shows a semiconductor device in which the semiconductor chip 16 is mounted on the lead frame thus formed.

Since the lead frame thus obtained does not require a support bar, the lead occupying area can be increased correspondingly, and the number of leads or the lead pitch can be increased. It is highly reliable even when miniaturized.

Further, until punching out of the cavity area,
All of them can be formed with the same die without depending on the die size, and it is only necessary to prepare the die corresponding to the die size in the coining process and the punching process of the cavity area, which makes the die size versatile. Yes,
Mold cost can be reduced.

Further, since the material of the heat spreader 15 as the semiconductor device mounting portion can be selected as required, the heat dissipation effect is greatly improved.

Furthermore, from the punching of the side edges of the inner leads to the plating process, all can be performed with the same mold regardless of the chip size.
It is sufficient to perform these steps up to the time of receiving an order, and after the order is received, the cavity region is punched out and the semiconductor element mounting portion is fixed, so that the period from the order to the delivery can be greatly shortened.

Although the dam bar 17 is formed in the above embodiment, since the inner leads are interconnected by the insulating tape, the dam bar may be omitted as shown in a part of the manufacturing process in FIG. May be.

Further, in the above embodiment, the polyimide tape is used as the connecting member of the inner lead, but the present invention is not limited to this, and any other insulating tape may be used.

[0026]

As described above, according to the method of the present invention, after the inner lead side edges are punched out, the inner leads are connected to each other by taping, and the cavity regions are punched out so that the innermost lead portions are removed. After forming, the semiconductor element mounting part is fixed via the tape that connects the inner leads to each other, so the same mold is used regardless of the chip size until the cavity area is punched out. Therefore, the productivity can be improved, and the die cost can be reduced even when a large number of products are manufactured in small quantities.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a lead frame according to an embodiment of the present invention.

FIG. 2 is a diagram showing a semiconductor device using a lead frame formed by the method of the embodiment of the present invention.

FIG. 3 is a diagram showing a part of a manufacturing process of a lead frame according to another embodiment of the present invention.

FIG. 4 is a manufacturing process diagram of a conventional lead frame.

[Explanation of symbols]

 1 strip material 2 inner lead 3 outer lead 4 cavity area 11 strip material 12 inner lead 13 outer lead C cavity area 14 lead frame body 15 heat spreader (semiconductor element mounting part) 16 semiconductor chip 17 dam bar

Claims (1)

(57) [Claims] 1. A side edge punch for punching a side edge of an inner lead in a method of manufacturing a lead frame including a semiconductor element mounting portion and a lead frame main body having a plurality of inner leads arranged around the semiconductor element mounting portion. The tape is attached between the process and the inner leads, and the tape is connected, and the cavity region between the inner leads and the semiconductor element mounting part is punched out to form the leading end of the inner leads. And a semiconductor element mounting portion fixing step of adhering a semiconductor element mounting portion on which a semiconductor chip is mounted to the lead frame body via the lead frame manufacturing method.