JP2006202812A - Process for manufacturing lead frame and lead frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for manufacturing a lead frame in which punching of an inner lead and manufacture of a die are facilitated, and wear of the punch and die due to punching can be inspected without requiring a long time, and to provide a lead frame. <P>SOLUTION: In a lead frame 10 having a plurality of inner leads 13 formed around a semiconductor chip mounting region 12 by punching a metal plate 11 by means of a press die device, and its manufacturing process, the portion 17 being punched between adjacent inner leads 13 is divided into a plurality of sections in the length direction of the inner lead 13 at the time of punching the inner lead 13. Each section is then punched by means of a punch and a die having cutting edges opposing in parallel thus forming parallel grooves 20-22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a lead frame formed by stamping a metal plate by press working and a manufacturing method thereof.

Semiconductor devices are required to have high functionality and downsizing, and the number of pins is increased in order to meet this demand. Such lead frames for semiconductor devices (hereinafter simply referred to as “lead frames”) are multi-pin, and the intervals between the leads are becoming extremely narrow. In general, the lead frame is often formed by press working in terms of productivity and cost.
As shown in FIG. 4, the lead frame is formed by press working. As shown in FIG. 4, every one or a plurality of inner leads 51 of the unit lead frame 50, punching removal portions 52 between the leads from the inner lead 51 base portion to the tip portion are formed. The flat cross-sectional shape of the blade edge is punched with a taper type punch and die (for example, see Patent Document 1). In FIG. 4, reference numeral 54 denotes an outer lead. Further, pilot holes and the like are omitted.

By the way, the lead frame 50 becomes a defective product when the inner lead 51 whose lead width and interval are narrow and easily deformed is twisted or shifted in the lateral direction (width direction). , Requires strict inspection. Further, in order to form a lead frame 50 free from defects, it is necessary to inspect the punch and die of the press mold apparatus and perform maintenance.

JP-A-6-302739

However, punches and dies with a conventional blade tip having a tapered cross-sectional shape (that is, gradually becoming narrower toward the semiconductor chip mounting region) are difficult to manufacture and have a punched shape due to wear due to use. Even if the presence or absence of a change is inspected, the reference position must be determined one by one, and there is a problem that time and high skill are required. In addition, there is a problem that the inspection of inspection such as wear and the difficulty of inspection contribute to lead frame punching failure.
The present invention has been made in view of such circumstances, and it is easy to manufacture punches and dies for punching and forming narrow inner leads, and inspection and inspection of wear and the like by punching can be performed in a time-saving manner. It is a first object of the present invention to provide a lead frame manufacturing method and a lead frame capable of manufacturing a lead frame free from defects with high productivity. It is a second object of the present invention to provide a lead frame manufacturing method and a lead frame for obtaining a lead frame having excellent bonding strength with a sealing resin.

The lead frame manufacturing method according to the first aspect of the present invention is the lead frame manufacturing method in which a plurality of inner leads are formed around a semiconductor chip mounting region by punching a metal plate with a press die device. When punching and forming the inner lead, a punch removal portion between adjacent inner leads is divided into a plurality of areas in the length direction of the inner lead, and each of the plurality of areas is punched with parallel cutting blades. And punched with a die to make parallel grooves. Accordingly, since the punch and the die are parallel blades corresponding to the punched portion, it is not necessary to determine the measurement reference position, the blade width can be easily measured, and the maintenance inspection of the punch and the die is easy.
Furthermore, since the formed inner lead has the same width in each of the divided areas, the width of the removed portion that is punched in a plurality of areas in the length direction of the inner lead is checked for beginners. But it can be done easily.
In the method for manufacturing a lead frame according to the first aspect of the invention, the parallel grooves have different groove widths stepwise in the length direction of the inner leads.

A lead frame according to a second aspect of the present invention that meets the above-mentioned object is a lead frame comprising a plurality of inner leads formed around a semiconductor chip mounting region by punching a metal plate with a press die device. All or a main part between them is formed by connected parallel grooves.
Here, in the lead frame according to the second invention, the parallel grooves may be bent stepwise, or the parallel grooves may have stepwise different groove widths. .
In the above invention, the semiconductor chip mounting area includes the case where the semiconductor chip mounting area is formed as a semiconductor chip mounting part on the lead frame, and the present invention is also applied to the case where the semiconductor chip mounting area is a space part. Is done.

The lead frame manufacturing method according to claim 1 and the lead frames according to claims 3 to 5, wherein when the inner lead is punched and formed, the inner lead is removed by punching and removing the inner lead. Easily manufacture punches and dies by dividing them into multiple parts in the length direction of the lead and making each of the multiple punched parts removed into parallel grooves by punching them with punches and dies that face each other in parallel. It becomes.
In addition, punches and dies corresponding to the divided punching removal portions do not need to be provided with a reference point as in the prior art in checking whether or not punching is good, so that even beginners can easily make them.
The punch and die corresponding to the divided punching removal parts have a parallel cross-sectional shape of the cutting edge, so the inner lead punching inspection is easy, the quality can be easily judged, and if a defect occurs, maintenance is immediately performed. It is possible to prevent the occurrence of defective products.
In particular, as in the lead frame manufacturing method according to claim 2 and the lead frame according to claim 5, when the groove width of the divided punching removal portion (that is, the parallel groove) is changed stepwise, or When the parallel groove is bent stepwise as in the lead frame described in item 4, the adhesive strength with the sealing resin is increased, and disconnection and resin peeling are prevented.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is a plan view of a lead frame in a process of punching out a lead frame according to an embodiment of the present invention, and FIG. 2 is a partially enlarged view thereof. FIG. 3 is a plan view of a lead frame manufactured by the lead frame manufacturing method according to the embodiment of the present invention.

As shown in FIGS. 1 to 3, a lead frame 10 according to an embodiment of the present invention has a metal strip (an example of a metal plate) 11 having a thickness of, for example, about 0.1 to 0.3 mm, A plurality of inner leads 13 and outer leads 14 connected to the semiconductor chip mounting region 12 are formed around the semiconductor chip mounting region 12, which is formed by pressing using a press die device having a die. Each inner lead 13 has a linear portion 15 connected to the outer lead 14 and an inner lead inclined portion 16 that becomes narrower toward the semiconductor chip mounting region 12.
The adjacent inner leads 13 are separated by a punching removal portion 17, and the punching removal portion 17 is punched by press working with a punch and a die having parallel cutting edges, and is stepped in the length direction of the inner lead 13. The width is different.

The punching formation of the inner lead 13 will be further described with reference to FIGS.
The punching removal portion 17 has a corner punching portion 18 connected to the straight portion 15 of the inner lead 13 and a slope punching portion 19 that separates the adjacent inner lead sloped portions 16. The portion 19 is formed by a plurality of parallel grooves 20 to 22 which are divided into a plurality of areas in the length direction of the inner lead 13 and whose width gradually decreases toward the semiconductor chip mounting region 12 side.
A press die apparatus (not shown) for punching the punching removal portion 17 includes a plurality of punches and dies that individually form the corner punching portion 18 constituting the punching removal portion 17 and the connected parallel grooves 20 to 22. Thus, each punch and die have corresponding cutting edges in parallel.

From the above, in both the punch and the die, the facing cutting blades are parallel, and both the outer surfaces of the punch and the inner surfaces of the die forming the parallel grooves 20 to 22 are constant along the length direction. ing. Therefore, when checking the state of wear of the punch and die, the punching width can be checked at any position within the length direction of the processed corner punched portion 18 and the parallel grooves 20 to 22, and the punch and die can be directly checked. Measure the die dimensions and check and grasp the wear status.
The lead frame 10 shown in FIG. 3 manufactured by the lead frame manufacturing method according to the embodiment of the present invention is between the punching removal portions 17 between the inner leads 13 of the lead frame 10 in the manufacturing process shown in FIG. This is done by forming a new punching removal portion 17 in the same manner.
In order to form the outer lead 14, rectangular punch holes 23 are formed on both sides thereof by another punch and die. A tie bar portion 24 is formed between the rectangular punched hole 23 and the square punched portion 18, a predetermined semiconductor chip is mounted on the completed lead frame 10, and wire bonding between the semiconductor chip and the tip of the inner lead 13 is performed. After resin sealing, the tie bar portion 24 is cut off. In this lead frame 10, pilot holes and the like are omitted. Moreover, in FIG. 2, the codes | symbols 26-28 show the location which changed the extraction width | variety of the parallel grooves 20-22.

In the above-described embodiment, the inclined cut portion 19 is formed by the three parallel grooves 20 to 22, but may be formed by two or four or more parallel grooves.
Further, in the above-described embodiment, the width of the inclined punched portion 19 is reduced in the direction toward the semiconductor chip mounting region 12, but when it is enlarged, it is a case where it is bent and bent with the same width. The present invention also applies.

It is a top view of the lead frame in one process of lead frame punching concerning one embodiment of the present invention. FIG. 3 is a partially enlarged view of the lead frame. It is a top view of the lead frame manufactured by the manufacturing method of the lead frame concerning one embodiment of the present invention. It is a top view of the lead frame concerning a conventional example.

Explanation of symbols

10: Lead frame, 11: Metal strip, 12: Semiconductor chip mounting area, 13: Inner lead, 14: Outer lead, 15: Straight part, 16: Inner lead inclined part, 17: Punching removal part, 18: Square punching Part, 19: Inclined punching part, 20-22: Parallel groove, 23: Rectangular punching hole, 24: Tie bar part, 26-28: Location where the punching width is changed

Claims (5)

In a manufacturing method of a lead frame in which a metal plate is punched with a press die device and a plurality of inner leads are formed around a semiconductor chip mounting region.
In punching and forming the inner lead, a punching removal portion between adjacent inner leads is divided into a plurality of areas in the length direction of the inner leads, and each of the plurality of areas has parallel cutting blades. A method for manufacturing a lead frame, characterized by punching with a punch and a die to form parallel grooves. 2. The method of manufacturing a lead frame according to claim 1, wherein the parallel grooves have stepwise different groove widths in the length direction of the inner leads. In a lead frame provided with a plurality of inner leads formed around a semiconductor chip mounting region by punching a metal plate with a press mold device,
A lead frame characterized in that all or main parts between the adjacent inner leads are formed by connected parallel grooves. 4. The lead frame according to claim 3, wherein the parallel grooves are bent stepwise. 5. The lead frame according to claim 3, wherein the parallel grooves have different groove widths in a stepwise manner.

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