JPS6074460A - Lead frame - Google Patents

Abstract

PURPOSE:To facilitate a press-punching work by a method wherein the third widely-formed part which is narrower than the first widely-formed part is provided between the first widely-formed part, which will be turned to an element fixing part, and the second widely-formed part which is extending from the first widely-formed part. CONSTITUTION:A plurality of punched-out parts, to be extended toward the center part, are formed using the first press mold 12. The tip of the punching parts are concentrated in such a manner that they are positioned within a virtual square. Then, the second punching-out part is formed using a press mold 13 having a pair of U-shaped punching part 14 which are facing each other. As the height H of the punching part 14 of the press mold 13 is reduced in measurements, the generation of swarf is prevented by the displacement of the punching part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a plate-like member, particularly a lead frame material for an iC.

In general, known methods for forming lead frames for ICs (integrated circuits) include etching, in which a lead frame material is subjected to corrosion treatment using a photographic technique, and press processing, in which press punching is performed using a press die.

The etching process takes a relatively long time because it corrodes the lead frame material, so it is not suitable for thick lead frames or for small production quantities because it takes too much time and effort. For this reason, molding is often performed by multi-step press punching using a press die.

This press molding process will be explained using a conventional IC lead frame punching press die shown in FIG. A punched portion 2 is formed.

The tips 2a of each of the first punched parts 2 are concentrated so as to be located within a virtual square.

Next, a second punching part is formed using a press die having a pair of U-shaped punch parts 3a and 3b facing each other. The outer diameter dimensions of these punch portions 3a, 3b are determined to match the virtual square, and the U-shaped top edges 4 of these punch portions 3a, 3b are aligned with the predetermined side edge 2a of the punch portion 2. It is placed in a position that exactly matches 5.

Therefore, when punching with the second press die, the cut will be made with a predetermined glue remaining, but in this case,
Since it is virtually impossible to match the U-shaped top edge 4 of the punch parts 3a, 3b with the side edge 5 of the punch part 2a, the punched edge may sag due to deviation of the punch parts 3a, 3b, or this cut Finer chips are generated and these chips are deposited on the surface of the lead frame material. These chips damage the surface of the lead frame material during the next punching process, reducing product yield.

The present invention has been made in order to eliminate such conventional drawbacks.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

In FIGS. 2 and 3, the shape and dimensions of the first punching section 12 having a plurality of punch sections 11 indicated by two-dot chain lines are completely the same as those of the prior art, and the shape and dimensions of the first punching section 12 having a plurality of punch sections 11 indicated by two-dot chain lines are completely the same as those of the prior art.
The height H of both sides of the U-shaped punch portion 14 of No. 3 is slightly smaller than that of the conventional punch portion 14. That is, by reducing the height H dimension, the U-shaped top edge of the punch portion 14 of the second press die 13 and the side edge of the lead forming groove (not shown) punched by the first press die 12 are reduced. It is made so that they do not substantially match. To be more specific about these dimensional relationships, the punch portion 14
The width a of the U-shape is 0811+11, and the first punched part 1
1 is 0.45 mm, and the dimension C of both punch overlapping portions 15 is Q, 3 nm, the O79 ramp portion d of the overlapping portion 15 will fit the Riet-Freh □. The distance e between the pair of sides of the U-shape is determined to be 0.5 mm, the longitudinal dimension f of the inside of the U-shape is 2 mm, and the relative dimension g of the inside of the pair of U-shapes is determined to be 2 mm. ing.

Since the punching press die according to the present invention has the above-described structure, by sequentially using these press dies, the third
A lead frame A as shown in the figure is obtained. That is,
This lead frame A has a wide part C in the part where the IC element is fixed, but the existence of this wide part C not only does not adversely affect the electrical characteristics of the lead frame A, but also When performing multi-step punching, the positions of the corresponding outer edges of the first punching part and the second punching part are intentionally made to be different, so that fine chips are generated during the punching process, which can cause damage to the product. There is no risk of adversely affecting yield.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of main parts showing a conventional punching press mold for an IC lead frame, FIG. 2 is an enlarged plan view of main parts showing a punching press mold for an IC lead frame according to the present invention,
Figure 3 shows an IC punched and pressed using the press die shown in Figure 2.
FIG. 1. Punch part, 12...-1st press mold, 13. 2nd press mold, 14... Punch part, 15... Overlapping part, Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. A first wide part that becomes a semiconductor element fixing part;
a second wide part extending from the wide part of the lead frame and having a width narrower than the first wide part, the lead frame having the first wide part between the first wide part and the second wide part; A linear frame characterized in that there is a third wide portion having a width narrower than the wide portion.