JPH03280563A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE:To prevent the generation of burr by a method wherein, after cut line parts of a part to be punched are half-etched and turned into very thin parts, said part to be punched is punched along said cut line parts and separated. CONSTITUTION:A metal thin plate 2 is subjected to a specified pattering, and a desired position of an inner lead part 6 is tape-fixed, thereby obtaining a lead frame 1. Cut line parts (b) on the outer peripheral side of a part 9 to be punched and the inner peripheral side of the part 9 are subjected to half etching and turned into very thin parts. The part 9 to be punched whose cut line parts are made very thin is punched and separated by press working from the side which is not subjected to the half etching. A lead frame 1 can be obtained in which the deviation of a cutting edge 4a of a mounting part and a cutting edge 6a of the inner lead part is in the thickness range of a metal thin plate 2. Since the cutting edges 4a, 6a are in the thickness range of the metal thin plate 2, the lead frame 1 is constituted in a flat shape where burr (a) of the cut line parts (b) does not protrude on the single surface in the punching direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a lead frame used in a semiconductor integrated circuit device.

[Conventional technology]

Conventionally, this type of lead frame has been made by cutting out a thin metal plate or the like using a method such as etching and forming it into a predetermined pattern.As shown in FIG. It is constructed in the form of a cane in which a plurality of frame parts 3 are arranged side by side in a thin plate 2, and a semiconductor chip mounting part 4 is arranged approximately at the center of the frame part 3. A hanging lead portion 5 is attached to the frame portion 3 and the mounting portion 4.
supports the placing part 4 continuously, and inner lead parts 6 are formed radially apart from each other around the placing part 4, and a space 7 is located so as to surround the placing part 4. Further, an outer lead portion 8 extending outward is continuous with the inner lead portion 6, and this outer lead portion 8 is continuous with the frame portion 3.

By the way, in order to manufacture the above-mentioned lead frame, that is, a lead frame corresponding to an extremely large number of pins, when the above-mentioned pattern is obtained on a thin metal plate through die-cutting such as etching, the above-mentioned mounting section is supported by a thin hanging lead section. Moreover, each reed in the inner reed section was in a cantilevered position, making it unstable. For this reason, plating processing and taping processing (
This is a problem because the mounting part and the inner lead part are easily deformed and displaced when passing through the parts (to support the individual leads when they are finally separated). This becomes an obstacle to mass production, which attempts to manufacture lead frames continuously.

To deal with these problems, for example, Japanese Patent Application Laid-open No. E30-13624
As shown in Japanese Patent No. 8, etching is now being performed in a pattern in which the tip portions of the inner lead portions are connected. This is as shown in Figures 6 and 7.
A punched part 9 is provided so as to surround the placing part 4, and at least a part of the inner edge is continuous, and the inner lead part 6 is continuous to the outer edge. (Although it is different from the pattern in FIG. 5, it is shown schematically for ease of judgment). Then, plating and taping are performed on the tip of the inner lead part and the mounting part supported by T[, and then the part to be punched 9 is punched and separated by press work to ensure insulation between the lead tips. In addition to obtaining the inner lead part,
An attempt was made to obtain a space around the mounting section.

This is shown in the order of steps: frame part 3, mounting part 4, hanging lead part 5, inner lead part 6, outer lead part 8.
, and the step of obtaining a pattern having the punched portion 9 on the thin metal plate 2 through a predetermined process (such as the plating process) to the step of fixing the desired position of the inner lead portion 6 with tape, After this, a step of punching and separating the punched portion 9 of the lead frame 1 is performed.

[Problem to be solved by the invention]

However, when the above-mentioned part to be punched is punched out, as shown in FIG. 8, the cut edge 6a of the lead tip and the cut edge 4a of the placement part are pushed out by the cutting die and protrude to one side of the lead frame. There is an inconvenience in that it causes a paris a. When a plurality of punched lead frames are stacked and handled (e.g. during transportation work, packaging work, etc.), the pads may scrape the plating surfaces of other lead frames or displace or deform the inner lead parts. In addition, there have been problems such as the inner lead part and the mounting part being displaced or deformed due to the part getting caught on other articles. Therefore, the present invention is designed to prevent the protrusion of holes in a lead frame in which the inner lead part and the mounting part are etched in a continuous pattern in the part to be punched out, and the part to be punched out is die-cut. The object of the present invention is to mass-produce lead frames that are easy to handle and do not suffer from damage or deformation due to the above-mentioned cracks.

[Means to solve the problem]

The present invention has been made in consideration of the above-mentioned problems, and includes a frame portion, a semiconductor chip mounting portion located approximately in the center of the frame portion, and a hanging portion continuous to the frame portion and the mounting portion. a lead part, an inner lead part formed radially apart around the mounting part, and a punched part located so as to surround the mounting part and having the inner lead part continuous to its outer edge; a first step of forming an outer lead portion continuous to the inner lead portion and extending outward and continuous to the frame portion in a thin metal plate; and a second step of fixing a desired position of the inner lead portion with tape. process and
a third step of performing half-etching on the cut line portion of the punched portion to make the cut line portion extremely thin; a fourth step of punching and separating the punched portion;
The present invention provides a method for manufacturing a lead frame characterized by the following.

[For production]

In the present invention, the part to be punched is located in the space before this punching process, and the placing part and the inner lead part are continuous through the part to be punched, and are separated only by punching to form the inner lead part. Insulation between the leads is also provided. Since the punched part is punched out so that the periphery, that is, the cut line part, is thinner than the thin metal sheet, the deviation of the cut edge that occurs at the cut line part is kept within the thickness of the thin metal sheet.

〔Example〕

Next, the present invention will be explained in detail based on an embodiment shown in FIGS. 1 to 4. It should be noted that portions whose configurations overlap with those of the conventional example shown in FIGS. 5 to 8 are given the same reference numerals, and the explanation thereof will be omitted.

In the present invention, in the first step such as etching, the thin metal plate 2 is patterned into a predetermined pattern, that is, a frame part 3, a mounting part 4, a suspension lead part 5, an inner lead part 6, a part to be punched 9, and an outer lead. After patterning the inner lead portion 8 and fixing the desired position of the inner lead portion 6 with tape, the punched portion 9 is formed.
A lead frame 1 is obtained in which the mounting part 4 and the inner lead part 6 are in a continuous state via the lead frame 1. The steps to obtain the lead frame 1 of the pattern are the same as those of the conventional method, and a predetermined processing operation such as plating may be performed before the second step of taping.

In the third step, that is, the step of performing half-etching, half-etching is applied to the cut line portions on the outer and inner circumferential sides of the part to be punched 9, for example, from one side, so that the cut line portions are completely etched. Place it thinly (
See Figures 1 and 2. Note that the pattern shown in FIG. 1 is schematically described. ), and then proceed to a fourth step of punching and separating the punched portion 9 to form a lead having a space 7 and ensuring insulation between the leads of the inner lead portion 6, as shown in FIG. Frame 1 is obtained (note that the pattern in FIG. 3 is depicted schematically).

In the fourth step, the part to be punched 9 whose cut line portion has become extremely thin is punched and separated from the side where the half-etching process has not been performed by pressing. A lead frame 1 is obtained in which the deviation of the edge 4a and the cut edge 6a of the inner lead portion is within the thickness of the thin metal plate 2 (see FIG. 4).

In lead frame 1, cutting a4a, 13
Since a is within the thickness of the thin metal plate 2, the cut line portion is already provided in a flat shape so that the paris a does not protrude to one side in the punching direction.

〔Effect of the invention〕

As explained above, according to the structure of the present invention, half-etching is performed on the cut line portion of the part to be punched to make this cut line part extremely thin, and then the part to be punched is separated by punching along the cut line part. Therefore, the misalignment of the cutting edge of the mounting part and the cutting edge of the inner lead part is contained within the thickness of the thin metal plate, and there is no possibility of a protrusion protruding to one side, and damage, displacement, or
8 lead frames that can prevent deformation can now be obtained. Furthermore, since the part to be punched is separated by cutting, which is extremely thin at the cut line part, die cutting can be performed with less pressure, thereby eliminating deformation of the lead frame during press processing. This has the effect of extending the life of the cutting die. In addition, the half-etching process, which makes the cut line part of the punched part extremely thin, can be performed on the same production line in the same way as the etching process for patterning, and does not require handling work outside the line. become able to.

Furthermore, although step processing may be applied to the lead frame during or after the process, it is possible to obtain a lead frame with no unnecessary protrusions protruding and with the protrusions and recesses reliably smoothed. , which has excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a half-etched part in an embodiment of the lead frame manufacturing method according to the present invention;
Fig. 2 is an explanatory diagram showing a section of the part to be punched which has become extremely thin, Fig. 3 is an explanatory diagram showing the area around the mounting part in an embodiment of the lead frame of the present invention, and Fig. 4 is an explanatory diagram showing the part to be punched in an extremely thin state. FIG. 5 is an explanatory diagram showing a lead frame in a cross-sectional state, FIG. 6 is an explanatory diagram showing a conventional example with a punched part, and FIG. 7 is an explanatory diagram showing a conventional example with a punched part. FIG. 8 is an explanatory view showing a punched portion in cross section, and FIG. 8 is an explanatory view showing a state in which the punched portion in a conventional example is punched and separated. 1...Lead frame 2...Thin metal plate 3...Frame part 4...Placement part 5...Hanging lead part 6... ... Inner lead part 7 ... Space part 8 ... Outer lead part 9 ... Part to be punched 4a ... Cutting edge 6a ... Cutting edge a...Paris b...Cut line part

Claims (1)

[Claims] A frame portion, a semiconductor chip mounting portion located approximately at the center of the frame portion, a hanging lead portion continuous to the frame portion and the mounting portion, and a periphery of the mounting portion. an inner lead part formed radially apart from each other; a punched part located so as to surround the placement part and having the inner lead part continuous to the outer edge thereof; a first step of forming an outer lead portion extending and continuous with the frame portion into a thin metal plate; a second step of fixing a desired position of the inner lead portion with tape; and a cut line portion of the punched portion. a third step of half etching the cut line portion to make it extremely thin; a fourth step of punching and separating the punched portion;
A method for manufacturing a lead frame characterized by the following.