JPS6120361A - Manufacture of lead frame for semiconductor device - Google Patents

Abstract

PURPOSE:To carry out pressing accurately and efficiently by a method wherein many streaks of metallic band are put on each other, fixed suitably by spot welding or the like, then successively fed to a press metal mold, punched at the same time into required patterns with the press metal mold, and separated into each form of metal band. CONSTITUTION:Streaks of metallic band 10 are unrolled out of reels 12a and 12b and fed toward the press metal mold 14 by being put on each other. Using a streak of metallic band 10 wider than in the case of being finally formed into a lead frame 16, the streaks are spot-welded with a welding machine 18 at fixed intervals in front of the press metal mold 14 at a position of being guided in linear form at both edges in the width direction, then being fed into the mold 14. The rigidity increases as a whole, and the phenomenon of rippling does not generate even by feeding in the forcing system. The press metal mold 14 successively punches the band into patterns of lead frame and separate it by cutting off the unnecessary part of the edges including welding points.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a lead frame for a semiconductor device, and more specifically, the present invention relates to a method for manufacturing a lead frame for a semiconductor device. The present invention relates to a method of manufacturing a lead frame for a semiconductor device, in which the lead frame can be press-worked with high precision and efficiency.

In recent years, due to the demand for further miniaturization and higher density for semiconductor devices, the lead frames used therein are also required to have higher density, and thinner materials have become necessary.

The processing of this lead frame is generally carried out by press working, in which a metal strip of raw material is continuously fed and punched into a desired pattern using a press die. There are two methods for feeding the metal strip during the above-mentioned press processing: a tension method and a push method to the press die. is convenient.

However, even with this pushing method, if the thickness of the metal strip becomes thin as described above, the metal strip will become wavy due to the pressing force during feeding, and the mold There are some disadvantages such as getting caught inside, which makes press processing difficult. In addition, as the density of semiconductor devices has increased in recent years, lead frame patterns have become extremely dense. When press working, a lead frame with satisfactory pattern accuracy cannot be obtained, which causes a decrease in yield.

On the other hand, this is a general problem with press processing, but even a slight dent on the front and back surfaces of the workpiece has the disadvantage of physically affecting the product and causing deformation, as well as impairing the appearance of the product. There are drawbacks.

As a result of intensive studies to resolve the above-mentioned difficulties, the inventor found that
By feeding multiple metal strips in layers, we give the metal strip overall rigidity and prevent the metal strip from waving during feeding, while at the same time minimizing the occurrence of dents. I came up with this idea.

However, simply stacking the metal strips causes a waving phenomenon of the metal strips and misalignment (feeding misalignment) of each metal strip, which makes it difficult to obtain the required pattern accuracy.

Therefore, the inventor discovered that the above-mentioned problem could be solved by fixing the overlapping metal strips and then simultaneously applying press working.

In other words, the object of the present invention is that even if the lead frame material is a thin metal strip, there will be no undulating phenomenon during feeding during press working, there will be no scratches or deformation, and there will be no undulations, and there will be no scratches or deformation, and the lead frame can be processed with high accuracy. , to provide a method for manufacturing lead frames for semiconductor devices that can be efficiently pressed.The feature is that a metal strip is progressively fed and punched into a desired pattern using a press die, thereby manufacturing lead frames for semiconductor devices. In the method, multiple metal strips are prepared,
These multiple metal strips are stacked one on top of the other, fixed by spot welding, etc. as appropriate, and then sent sequentially to a press die, where they are punched simultaneously into the desired pattern and separated into individual metal strips. .

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

As shown in FIG. 1, the metal strip 10 is wound around the loop 12a.
, 12b, and the unwound metal strips 10 are overlapped and sent toward the press mold 14. As shown in FIG. 2, the metal strip 10 is slightly wider than the width it will have when it is finally formed into the lead frame 16, and is placed in a straight line at a position in front of the press die 14. At the guided position, the welding machine 18 spot-welds the metal strip 10 at regular intervals at both end edges in the width direction, and then feeds the metal strip 10 into the press die 14 . By spot welding in this way, the overall rigidity of the overlapping metal strips 10 increases,
No waving phenomenon occurs even when feeding by the so-called pushing method.

In the press die 14, the two metal strips 10 fixed at both end edges as described above are simultaneously punched out in sequence into the desired lead frame pattern, and the welding points described above are punched out in the same press die 14. By cutting off unnecessary portions of the included edge portions and separating them, lead frames each having the same pattern of a desired width are formed.

Incidentally, unnecessary parts of the end edges of the metal strip 10 including the welded parts after press working are cut off using a cut-off die provided separately from the press die 14, and the parts are cut off after the press work and separated into each lead frame. It's okay.

Further, the means for fixing the overlapped metal strips 10 is not limited to spot welding, but may be fixed using a suitable adhesive or the like.

Furthermore, if an adhesive that can be easily peeled off by chemical treatment or the like is used, the metal strip 10 can have the same width as the lead frame to be obtained.

That is, in this case, the metal strip may be fixed at appropriate locations using an adhesive, pressed while being fixed, and after the press processing is completed, it may be passed through a chemical solution to be separated into each lead frame.

Note that even if the overlapping metal strips are three or more, they can be similarly fixed to increase the overall rigidity and press working can be performed.

As described above, according to the present invention, since a plurality of metal strips are properly fixed by spot welding or the like and then press worked, even if the metal strips are thin, a waving phenomenon occurs due to feeding. Pressing can be performed without causing scratches or deformation. In addition, since the overlapped metal strips do not shift in position, press working can be performed with high precision, and the overall yield can be improved.

Furthermore, even if dents occur on the surface side of the top layer and the bottom layer of stacked metal strips due to press working, each metal strip is fixed as one, and the overall material thickness is Because the lead frame is thick, deformation on the lead frame is alleviated, and no dents occur on the inner surface (3).
When stacking two or more metal strips, there will be no dents on both the front and back sides of the metal strips sandwiched inside), making it possible to use the inner surface with no dents as the use surface as a lead frame. . Furthermore, since multiple strips can be pressed at the same time, efficiency is greatly improved, and various other effects are achieved.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the metal strip used, and FIG. 2 is an explanatory diagram showing an example of the manufacturing process. DESCRIPTION OF SYMBOLS 10... Metal strip, 12a, 12b... Reel, 14... Press mold, 16... Lead frame, 18... Welding machine.

Claims (1)

[Claims] 1. In a method for manufacturing a lead frame for a semiconductor device, in which a metal strip is sequentially fed and punched into a desired pattern using a press die, a plurality of metal strips are prepared, and the plurality of metal strips are overlapped, and as appropriate. A method for producing a lead frame for a semiconductor device, which comprises fixing the lead frame by spot welding or the like, then sequentially feeding the lead frame to a press mold, simultaneously punching it into a desired pattern in the press mold, and separating it into metal strips.