JPS63171223A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE:To form a lead frame having less width camber by feeding a metal strip bar to a progressive die and after punching one part of a lead frame pattern feeding it to the progressive die by turning over the metal strip bar and punching the remaining part of the feeding to the progressive die from the reverse direction. CONSTITUTION:In order to form the lead frame 10 used for a resin sealing type semiconductor device a metal strip bar 11 is first fed to a progressive die to subject the inner pattern part 24 surrounded by a broken line as shown in A on the figure and a guide hole 21 to a pressing. The metal strip bar 11 pressing the inner pattern part 24 is thereafter turned backside out. It is then located with the guide hole 21 formed by pressing as shown by B on the figure as the reference and formed in a specified shape by subjecting an external part lead part 12, damper 22 and rail part 20 excepting the inner pattern part 24 to a pressing. A plating treatment, cutting with bend, etc., are thereafter performed. The width camber due to punching is thus canceled each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a lead frame that can prevent width warping of the lead frame.

(Prior Art and its Problems) Conventionally, lead frames used in resin-sealed semiconductor devices have been formed by pressing or etching a strip-shaped metal plate for manufacturing lead frames (hereinafter referred to as metal strip). In press working, metal strips are sequentially supplied onto a lower die of a fixed progressive mold, and the upper die is lowered to sequentially punch out a predetermined shape.

However, in the conventional manufacturing method of lead frames by press working, the lower mold is fixed and the upper mold is moved for processing, so the processed lead frame has flashing only on one side (back side). However, it is curved in a convex manner toward the surface side (non-burr generation side), resulting in a condition called width warpage.

In these lead frames whose widths are warped, variations in the steps at the lead tips become large, which causes breakage of the wires connecting the semiconductor element and the internal leads after molding, and poor contact.

Additionally, problems such as getting caught during automatic transportation during the mounting process occur.

Furthermore, lead frames with warped widths formed by press processing must be forcibly flattened in a post-process. It will be difficult to make corrections.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a lead frame in which the width warping of the metal strips is canceled out by partially changing the punching direction of the metal strips.

(Means for Solving the Problems) The present invention has been made in view of the above problems, and includes the following configuration.

That is, a metal strip is fed into a progressive die, a part of the lead frame pattern is continuously punched out by the progressive die, then the metal strip is turned inside out and fed into the progressive die, and the remaining part of the lead frame pattern is punched out. Characterized by punching.

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

FIG. 1 shows a part of the procedure for forming a lead frame 10 used in a resin-sealed semiconductor device.

In FIG. 1B, 16 is a stage portion, which is plated with a noble metal such as gold or silver, and is a portion to which a semiconductor element is fixed by gold-silicon eutectic alloy or the like.

Reference numeral 14 denotes an internal lead section provided surrounding the stage section 16, the ends of which are similarly plated with a noble metal such as gold or silver, and connected to the semiconductor element mounted on the stage section 16 by wires. Further, the portion surrounded by the broken line is the inner pattern portion 24.

18 is a stage support bar.

Reference numeral 12 denotes an external lead portion following the internal lead portion 14.

A dam bar 22 serves to dam the resin during resin sealing.

Reference numeral 20 denotes a rail portion, in which guide holes 21 are bored at predetermined positions.

First, the metal strip 11 is fed into a progressive die, and as shown in FIG.
Press 1.

Thereafter, the metal strip 11 with the inner pattern portion 24 pressed is turned over. Then, as shown in FIG. 1B, the position is determined based on the guide hole 21 formed by press working, and the external lead part 12, dam bar 22, and rail part 20 other than the inner pattern part 24 are pressed into a predetermined shape. to form.

After that, plating treatment, bending and cutting, etc. are performed.

In addition, contrary to the above embodiment, the parts other than the inner pattern part 24 may be pressed first, and then the metal strip may be turned over and the inner pattern part 24 may be pressed. Also,
The inner pattern portion and the other portions may not be press-worked separately, but may be press-worked by dividing the portions as appropriate.

(Effects of the Invention) In the present invention, since the metal strip is processed by partially reversing the punching direction using a progressive die, the width warpage caused by punching cancels each other out, forming a lead frame with less width warpage. can do.

Further, it is also effective in that the direction of the pattern can be determined in consideration of processing in the post-processing step.

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

[Brief explanation of the drawing]

FIG. F is an explanatory diagram showing the manufacturing process of the metal strip. DESCRIPTION OF SYMBOLS 10... Lead frame, 11... Metal strip, 12... External lead part, 14
...Internal lead part, 16...Stage part, 2
4...Inner pattern section.

Claims (1)

[Claims] 1. Feed the metal strip into a progressive die, punch out part of the lead frame pattern continuously with the progressive die, then turn the metal strip inside out and feed it into the progressive die to punch out the remaining part of the lead frame pattern. A method for manufacturing a lead frame characterized by punching.