JPH1070229A - Semiconductor lead frame and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent twisting and warp of an inner lead at the time of punching process by a press in order to improve the processing accuracy. SOLUTION: The left end part of the first lead 15a is formed by a first punch 16A and the right end part is formed by a second punch 16B. The first lead 15a is twisted to the side A punched by the second punch 16B. The left side end of the third lead 15c is formed by the third punch 16C and the right end part is formed by the fourth punch 16D. The third punch lead 15c is twisted to the side A punched by the fourth punch 16D. The right end part of the second lead 15b is formed by the fifth punch 16E and the left end part is formed by the sixth punch 16F. The second lead 15b is twisted toward the side B punched by the sixth punch 16F and the twisting in the direction A of the first and third leads 15a, 15c is reset.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor lead frame and a method of manufacturing the same, and more particularly, to a semiconductor lead frame with improved inner lead punching and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a conventional semiconductor lead frame,
For example, there is one shown in FIG. The semiconductor lead frame 1 has a dam bar 2 for preventing resin flow during molding and an island 3 on which a semiconductor element is mounted.
And suspension leads 4 for supporting the island 3 from the dam bar 2, and a plurality of inner leads 5 radially extending from the dam bar 2 toward the island 3. The dam bar 2, the island 3, the suspension leads 4, and the inner leads 5 are integrally formed by punching a metal plate by pressing (hereinafter, also simply referred to as “punching”).

When the inner lead 5 is formed by a punching process, one side end of the inner lead 5 is pressed from the root to the tip as shown in FIG. 1 punch 6
A, and then the other side end is punched once from the root to the tip by the second punch 6B, and then the tip is punched by the third punch 6C to complete the inner lead 5.

The inner lead 5 generally becomes thinner as the number of pins increases, and a gap between the leads 5 (see FIG. 5).
(The thicknesses of the first and second punches 6A and 6B) also become narrower, and the punching process becomes finer as the number of pins increases.

[0005]

However, according to the conventional method of manufacturing the semiconductor lead frame 1, both ends of the inner lead 5 are punched out once from the root to the tip, and the inner lead 5 is formed by increasing the number of pins. The force which presses the inner lead 5 is dispersed and cannot be effectively suppressed as the length becomes longer.

For this reason, as shown in FIG. 6, when punching is performed with the second punch 6B, the side punched out by the first punch 6A (first punching side) becomes free, and the inner lead 5 is removed from the second lead 6A.
Is twisted toward the punch 6B side (rear punch side) A. Further, since the inner leads 5 cannot be effectively held down, there is a problem that warping is more likely to occur as the inner leads 5 are elongated.

If the length of the punch 6 is long, it is difficult to adjust the clearance between the punch 6 and the female die.

Accordingly, it is an object of the present invention to provide a semiconductor lead frame which prevents twisting and warping of the inner lead during punching by a press and improves processing accuracy, and a method of manufacturing the same.

[0009]

In order to achieve the above object, the present invention provides a semiconductor lead frame having a plurality of inner leads, wherein the inner leads are provided with a step at both ends along a longitudinal direction. A semiconductor lead frame is provided. According to the above configuration, since the portion of the lead divided before and after the step is shortened, it is possible to effectively hold the divided lead portion. Can be suppressed.

[0010] By punching in a divided manner, the length of the punch is shortened, and the clearance between the punch and its female die can be easily adjusted, so that the processing accuracy is improved. The step absorbs the position shift of the punch and improves the processing accuracy.

Further, in order to achieve the above object, the present invention provides a method for manufacturing a semiconductor lead frame in which inner leads are formed by punching first and second side ends and a front end on both sides in a predetermined order. A method of manufacturing a semiconductor lead frame is provided, wherein the first and second side edges are punched by dividing each side edge in a predetermined order.

According to the above structure, the divided lead portion is shortened, so that the portion can be effectively held down. Further, by punching in a predetermined order,
Twisting and warping can be further suppressed.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing a main part of a semiconductor lead frame according to an embodiment of the present invention. The semiconductor lead frame 10 includes a dam bar 2 for preventing resin flow during molding, an island 3 on which a semiconductor element is mounted, a suspension lead 4 supporting the island 3 from the dam bar 2, and an island Inner leads 1 extending radially toward 3
5 is provided. The dam bar 2, the island 3, the suspension leads 4 and the inner leads 15 are integrally formed by punching a metal plate.

FIG. 2 is a plan view showing details of the inner lead 15. The inner lead 15 includes a first lead portion 15a and a second lead portion 1 in order from the root in the longitudinal direction.
5b and a third lead portion 15c. Step portions 15d, 15d are provided on both side surfaces between the first lead portion 15a and the second lead portion 15b and between the second lead portion 15b and the third lead portion 15c, respectively.

Next, a method for forming the inner leads 15 will be described with reference to FIG. FIG. 3 is a diagram showing a method of forming the inner leads 15. First, the left side end of the first lead portion 15a is formed by punching with the first punch 16A while pressing down the portion of the metal plate to be the first lead portion 15a, and punching with the second punch 16B. First
The right side end of the lead portion 15a is formed. During this formation, the first lead portion 15a is twisted to the side A punched by the second punch 16B.

Next, the left side end of the third lead portion 15c is formed by punching with a third punch 16C while pressing down the portion of the metal plate serving as the third lead portion 15c. The right side end of the third lead portion 15c is formed by punching with 16D. During this formation, the third lead 15c is twisted to the side A punched by the fourth punch 16D.

Subsequently, the right side end of the second lead portion 15b is formed by punching with a fifth punch 16E while pressing down the portion of the metal plate to be the second lead portion 15b.
The left side end of the second lead portion 15b is formed by punching with the sixth punch 16F. At the time of this formation, the second lead portion 15b is on the side B punched by the sixth punch 16F.
Twist, the twist in the direction A of the first lead portion 15a and the third lead portion 15c is returned.

Finally, while pressing the third lead portion 15c or the entire inner lead 15, the seven punches 16G
The tip of the inner lead 15 is formed by punching. In this way, the inner leads 15 with less twist and warpage are formed.

According to the semiconductor lead frame 10 or the method of manufacturing the same, the following effects can be obtained. (1) Since the length of one lead 15a, 15b, 15c is short, each lead 15a, 15b, 15c can be effectively pressed, so that twisting and warping can be suppressed. In addition, since the twist of the first lead 15a and the third lead 15c is returned when the second lead 15c is punched, the twist of the inner lead 15 can be further suppressed. (2) As the length of the punch 16 is shortened, the punch 16
And the clearance between the die and the female die can be easily adjusted, and the processing accuracy can be improved. (3) The deburring operation of the inner lead 15 can be performed by dividing the deburring operation into the three lead portions 15a, 15b, and 15c. (4) The step 15d increases the bonding force between the inner lead 15 and the resin during molding. In addition, since the displacement of the punch 16 can be absorbed by the step 15d,
Processing accuracy can be improved. (5) Since each of the leads 15a, 15b, 15c can be effectively held down, it is possible to cope with an increase in the number of pins.

The present invention is not limited to the above embodiment, but various embodiments are possible. For example, in the above embodiment, the inner lead 15 is divided into three, but may be divided into two or four or more. Further, the order of forming the side ends of each of the divided lead portions is not limited to the above-described embodiment, but can be determined so as to reduce twisting and warping according to the material, shape, and the like of the inner leads 15.

[0021]

As described above, since the divided lead portion is shortened, the lead portion can be effectively suppressed, and twisting and warping can be suppressed. Furthermore, twisting and warping can be further suppressed by dividing and punching out both side ends of the inner lead in a predetermined order at each side end.

Further, since the divided lead portion is short, the length of the punch is also reduced, and the clearance between the punch and its female die can be easily adjusted, so that the processing accuracy is improved. Can be. Further, by absorbing the displacement of the punch by the step, the processing accuracy can be further improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a semiconductor lead frame according to the present invention.

FIG. 2 is a plan view showing details of an inner lead according to the present invention.

FIG. 3 is a plan view for explaining a method of forming an inner lead according to the present invention.

FIG. 4 is a plan view showing a main part of a conventional semiconductor lead frame.

FIG. 5 is a plan view for explaining a conventional method for forming an inner lead.

FIG. 6 is a sectional view taken along line II of FIG. 5;

[Description of Signs] 2 Dam bar 3 Island 4 Suspended lead 10 Semiconductor lead frame 15 Inner lead 15a First lead 15b Second lead 15c Third lead 15d Step 16A First punch 16B Second punch 16C Third punch 16D Fourth punch 16E Fifth punch 16F Sixth punch 16G Seventh punch

Claims (4)

[Claims] 1. A semiconductor lead frame having a plurality of inner leads, wherein the inner leads are provided with steps at both ends along a longitudinal direction. 2. A method of manufacturing a semiconductor lead frame in which inner leads are formed by punching first and second side ends and a front end on both sides in a predetermined order, wherein the first and second side ends are punched. A method of manufacturing a semiconductor lead frame, wherein each side end is cut in a predetermined order and punched out. 3. The method for manufacturing a semiconductor lead frame according to claim 1, wherein the predetermined order in which the semiconductor device is divided and punched is a punching order in which the twist generated in the inner lead is minimized. 4. The method of manufacturing a semiconductor lead frame according to claim 1, wherein the step of punching at each side end forms a step at each side end.