JPH10154784A - Manufacture of lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a twist and the concave phenomenon of a ship bottom in the inner leads of a lead frame by a method wherein both side surfaces, which comprises the parts extending over from the resin-sealed boundary scheduled surfaces of the inner leads to tie bars, of the inner leads are simultaneously punched by a press and the side surfaces of the other inner leads are punched by a press one by one. SOLUTION: The side surfaces 7, which are located on the side of a die pad 4, out of side surfaces 7 divided into two from a metal strip material 6 to the longitudinal directions of the side surfaces of inner leads 1, are formed one by one by punching using a press. Both side surfaces 9 comprising the parts extending over from the resin-encapsulated boundary scheduled surfaces 8 of the inner leads 1 to tie bars 2 are simultaneously punched by a press and with the side surfaces of the inner leads made to complete, the side surfaces, which are located on the sides of the inner leads, of the tie bars 2 and a support bar 5 are made to complete. Then, outer leads, the die pad 4 and the points of the inner leads are formed by punching using a press. Thereby, the generation of a twist and the concave shape in the inner leads is prevented and a resin-encapsulation mold is made to closely adhere to the inner leads to prevent the generation of resin burrs due to resin leakage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a lead frame used for a resin-sealed semiconductor device.

[0002]

2. Description of the Related Art Conventionally, in a method of punching a lead frame used for a resin-encapsulated semiconductor device, both sides of each inner lead cannot be punched at the same time due to a problem of strength of a die used for punching. The surfaces are sequentially punched and formed one by one.

[0003]

However, when the side surfaces of each inner lead are formed one by one, as shown in FIG. 7, the side surface punched in a later step is twisted so as to be inclined in the punching direction, Bottom shape 14
The problem that occurs occurs.

For this reason, a semiconductor device is formed by mounting a semiconductor chip on a die pad of a lead frame, electrically connecting the semiconductor chip to the inner lead, and sealing the resin with a resin. When the resin is sealed up to the resin sealing area near the side base end, the upper and lower surfaces of the inner leads other than the resin sealing portion and the upper and lower surfaces of the tie bars so that the resin does not flow out of the resin sealing portion. A resin sealing mold is adhered to the lower surface, but a gap 15 is formed between the upper surface and the lower surface of the inner lead and the resin sealing mold 10 due to the problem of the twist and the boat bottom shape 14, and the resin flows into the gap 15. Then, resin burrs are generated on inner leads other than the resin sealing portion.

In order to remove the resin burrs after the resin sealing step, a resin burr removal step using a water jet or an air jet or the like is required, which increases the number of semiconductor device manufacturing steps and deteriorates production efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method of manufacturing a lead frame in which the inner lead from the resin sealing boundary expected surface to the tie bar does not cause twisting or a boat bottom phenomenon. This eliminates the need for a resin burr removal step in the manufacture of the device.

[0007]

In the method for manufacturing a lead frame according to the present invention, both side surfaces including a portion from a resin sealing boundary expected surface of the inner lead to a tie bar are simultaneously punched by a press, and the other inner lead side surfaces are pressed. The punching is performed one side at a time.

[0008]

Hereinafter, embodiments of the present invention will be described.
This will be described in detail with reference to the drawings.

FIG. 1 is a view showing a lead frame according to the present invention, which comprises an inner lead 1, a tie bar 2, an outer lead 3, a die pad 4, and a support bar 5, and is formed by pressing.

As shown in FIG. 2 (a dashed line represents a region to be a lead frame), the side surface of the inner lead 1 is divided into two parts in the longitudinal direction from the metal strip material 6 and the punching for forming the side surface 7 on the die pad 4 side is performed. Is performed on each side of each inner lead 1, and then, as shown in FIG. 3 (a dashed line indicates a region to be a lead frame), both side surfaces including a portion from the resin sealing boundary expected surface 8 to the tie bar 2 of the inner lead 1. 9 is simultaneously punched to complete the punching of the inner lead side surface, and the side surface of the tie bar 2 on the inner lead side and the support bar 5 are formed.

Next, punching for forming the outer lead 3 is performed, and then punching for forming the die pad 4 and the tip of the inner lead is performed, thereby completing the lead frame.

If the above-described method is used, no twisting or boat bottom shape is generated as shown in FIG. 4 which shows a cross-sectional view of a portion from the resin sealing boundary expected surface of the inner lead to the tie bar. Since there is no gap between the upper and lower surfaces of the inner lead 11 and the inner leads 11 and the upper and lower surfaces of the tie bars, resin burrs due to resin leakage do not occur, and the resin burrs removing step can be omitted.

In addition, if such a method is used, both sides 9 of each inner lead are simultaneously punched out only from the resin sealing boundary expected surface 8 of the inner lead to the tie bar 2, and the side 7 on the die pad side is one side at a time. Since the punching is performed, even when a long and thin portion such as a lead frame is punched in close proximity, the load on the die is reduced, and damage can be prevented.

In this embodiment, of the side surfaces of each inner lead, the side surface 7 on the die pad side is formed first, and then both side surfaces including the portion from the resin sealing boundary expected surface 8 to the tie bar 2 of the inner lead. 9, but this is optional and the invention is not limited thereto.

Further, in this embodiment, the outer leads are machined after the inner leads are punched, but the order can be changed.

In this embodiment, the entire lead frame is formed by punching with a press. However, the present invention is not limited to this, and the outer leads and the like may be formed by a method such as etching. good.

[0017]

FIG. 5 shows an embodiment utilizing the present invention.
The punching is divided into two as a method for eliminating the punch sagging 12 and the punch burr 13 in the press working as shown in FIG. 1 and punching is performed so that the second punching portion is minute in the first punching and is left in the second punching. Although the shaving method of punching out a minute portion is generally used, a combination of the present invention and shaving processing is performed so that both side surfaces of the inner lead side surface including a portion from a resin sealing boundary scheduled surface of the inner lead to a tie bar are formed. If the punching is performed in separate times, the first punching or the second punching or the first and second punching are performed simultaneously as in the present embodiment, the twisting and the bottom shape are prevented as shown in FIG. In addition to removing the burrs and burrs, the inner lead resin Since adhesion of the upper surface and the lower surface and the resin-sealing mold of the upper and lower surfaces and a tie bar in the portion other than the stopper portion is increased, it is possible to more satisfactorily prevent the resin burr due to resin leakage.

[0018]

According to the present invention, in a lead frame which is used for another semiconductor device by resin encapsulation, both side surfaces including a portion from the resin encapsulation boundary surface of the inner lead to the tie bar on the inner lead side surface are simultaneously formed. Since punching is performed, no twist or boat bottom shape occurs in the portion of the inner lead that is not sealed with resin, so that no resin burr occurs in the portion of the inner lead that is not sealed with resin in the resin sealing process. The process becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a plan view showing a lead frame manufactured according to the present invention.

FIG. 2 is a plan view showing a part of a lead frame in the process of manufacturing according to the present invention.

FIG. 3 is a plan view showing a part of a lead frame in the process of manufacturing according to the present invention.

FIG. 4 is a cross-sectional view in which an inner lead is enclosed in a resin-sealing mold when a semiconductor device is resin-sealed using a lead frame manufactured according to the present invention.

FIG. 5 is a cross-sectional view of an inner lead manufactured by punching with a normal press.

FIG. 6 is a cross-sectional view in which an inner lead is enclosed in a resin sealing mold when a semiconductor device is sealed with a resin using a lead frame manufactured according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view in which an inner lead is enclosed in a resin sealing mold when a semiconductor device is sealed with a resin using a lead frame according to a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner lead 2 Tie bar 3 Outer lead 4 Die pad 5 Support bar 6 Metal strip 7 Side surface on die pad side 8 Resin sealing boundary scheduled surface 9 Both side surfaces 10 Resin sealing mold 11 Inner lead cross section 12 Pull out 13 Drop burr 14 Boat Bottom shape 15 gap

Claims (1)

[Claims] 1. A method of manufacturing a lead frame used in a resin-sealed semiconductor device, wherein both side surfaces including a portion from a resin sealing boundary scheduled surface to a tie bar of each inner lead are simultaneously punched by a press, and the like. The method for manufacturing a lead frame, wherein the side surfaces of the inner lead are punched one by one by a press.