JPH03200358A - Lead frame and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent any damage and deformation due to burr from being produced and facilitate handling, and further realize mass-production by locating a blanked cut edge made by blanking a part to be blanked within the thickness of a metal sheet. CONSTITUTION:By locating a blanked cut edge 4a, 6a of a lead frame 1 within the thickness of a metal sheet, any burr (a) is prevented from being protruded onto a side surface part and both face and back of the lead frame 1 are made flat. Further, a part 9 to be blanked is located in a space part 7, and a placing part 4 and an inner lead part 6 are in communication with each other through the part 9 and are separated by blanking also for insulation among leads of the inner lead part 6. By blanking the part 9 which is thinner than the metal sheet any displacement of a cut edge produced at the edge part is limited within the thickness of the metal sheet. Hereby, any damage and deformation due to burr is prevented from being produced and handling is facilitated with mass- production realized.

Description

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

[Conventional technology]

Conventionally, this type of lead frame has been made by cutting out a thin metal plate or the like using a technique such as etching and forming it into a predetermined pattern.As shown in FIG. 2, a plurality of frame portions 3 are arranged in parallel, and a semiconductor chip mounting portion 4 is disposed approximately at the center of the frame portion 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 lead in the inner lead section was in a cantilevered state, 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 (for supporting each lead when it is finally separated into individual leads). This poses an obstacle to mass production in which lead frames are manufactured continuously.

To deal with these problems, for example, Japanese Patent Application Laid-Open No. 60-136248
As shown in the above publication, etching has come to be performed in a pattern in which the tips of the inner lead portions are connected. As shown in FIGS. 6 and 7, this is a part 9 to be punched, which is located so as to surround the placing part 4, and has at least a part of its inner edge continuous and the inner lead part 6 continuous with its outer edge. (Please note that the sixth
Although the diagram differs from the pattern in Figure 5, it is depicted schematically for ease of understanding). Then, with the tips of the inner lead parts and the mounting part supported, plating and taping are performed, 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 portion, a space around the mounting portion is also obtained.

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 part to be punched that is located so as to surround the mounting part and has the inner lead part continuous to the outer edge thereof. In a lead frame formed of a thin metal plate, a space portion formed by punching and separation, and an outer lead portion extending outward continuously from the inner lead portion and continuing to the frame portion, the punched portion The present invention provides a lead frame characterized in that a punched cut edge formed by punching is located within the thickness of the thin metal plate.

The present invention also provides a frame portion, a semiconductor chip mounting portion located approximately at the center of the frame portion, a suspension lead portion continuous to the frame portion and the mounting portion, and a mounting lead portion extending around the mounting portion. Inner lead parts formed radially apart, a punched part located so as to surround the placement part and having the inner lead part continuous to the outer edge thereof, and a part to be punched which extends outward continuously from the inner lead part. A first step of forming an outer lead portion continuous with the frame portion in a thin metal plate, a second step of fixing a desired position of the inner lead portion with tape, and half etching the punched portion. The present invention provides a method for manufacturing a lead frame, comprising: a third step of making the punched portion extremely thin; and a fourth step of punching and separating the punched portion.

[For production]

In the present invention, since the punched cut edges of the lead frame are located within the thickness of the thin metal plate, the edges do not protrude to one side and both the front and back sides of the lead frame are flat.
This will prevent you from getting caught by others. In addition, the part to be punched, which has become extremely thin due to half etching, is located in the space until before this punching process, and the mounting part and the inner lead part are continuous through this part to be punched, and are separated only by punching. , insulation between the leads of the inner lead portion is also performed. Since the part to be punched is punched out, which is thinner than the thin metal sheet, the deviation of the cut edge that occurs at the edge of the half-etched 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. A second process is performed in which the desired position of the inner lead part 6 is fixed with tape, and then the part to be punched 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 patterned lead frame 1 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 half-etching step, the punched portion 9 is half-etched, for example, from one side to make the punched portion 8 extremely thin (see FIGS. 1 and 2).

Note that the pattern shown in FIG. 1 is schematically illustrated. ), 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 punched part 9 which has become extremely thin is
It is separated by punching from the side that has not been half-etched, that is, the edge of the half-etched side is used as the cut line, and the cut edge of the mounting section is separated. A lead frame 1 is obtained in which the misalignment of the cut 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 the lead frame 1, the cutting edge 4area
Since the gap is accommodated within the thickness of the thin metal plate 2, the gap a is provided in a flat shape so that it does not protrude to one side in the punching direction at the cut line portion.

〔Effect of the invention〕

As explained above, according to the configuration of the present invention, the cutting edge of the mounting part and the cutting edge of the inner lead part of the lead frame are located within the thickness of the thin metal plate, so that the edge is on one side of the lead frame. It will not stick out and will not get caught on other items. In other words, the lead frame becomes flat and easy to handle, and even when a single lead frame is pulled out from a stacked state, no damage, displacement, or deformation will occur. Furthermore, although the lead frame may be stepped during or after the process, the result is a lead frame with no unnecessary projections protruding, and with the convex and concave portions reliably smoothed.

In addition, the part to be punched is half-etched to make it extremely thin, and then the part to be punched is separated by punching, so the edge part of the half-etched surface becomes the cut line, and the cut edge It is possible to easily obtain a lead frame in which the misalignment is contained within the thickness of the metal thin plate and does not cause a protrusion protruding to one side, and can prevent damage, displacement, and deformation due to catching of the protrusion. Furthermore, since the extremely thin part to be punched is separated by punching, die cutting can be performed with less pressure.
Therefore, the lead frame is not deformed during press working, and the life of the cutting die is also extended. Half-etching, which makes the part to be punched extremely thin, can be performed on the same production line in the same way as etching for patterning, and can be handled without the need for handling operations outside the line.
It 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. 8 is an explanatory diagram showing a state in which a conventional example has a punched part, and FIG. FIG. 8 is an explanatory diagram showing a punched portion in cross section, and FIG. 8 is an explanatory diagram showing a state in which the punched portion in a conventional example is punched and separated. Fig. 1 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 a... Paris 4a... ...Cut edge 6a...Cut edge Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (2)

[Claims] (1) A frame portion, a semiconductor chip placement portion located approximately at the center of the frame portion, a suspension lead portion continuous to the frame portion and the placement portion, and a radially extending portion around the placement portion. an inner lead part formed apart from each other; a space formed by punching and separating a part to be punched that is located so as to surround the placement part and on which the inner lead part is continuous on the outer edge; and the inner lead part. In a lead frame formed of a thin metal plate, the outer lead portion extends outwardly from the frame portion and is continuous with the frame portion. A lead frame characterized by being located within. (2) a frame portion, a semiconductor chip placement portion located approximately in the center of the frame portion, a suspension lead portion continuous to the frame portion and the placement portion, and a radially extending portion around the placement portion; an inner lead part formed 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; and a part to be punched which extends outward continuously from the inner lead part and the frame. a first step of forming an outer lead portion that is continuous with the outer lead portion on a thin metal plate; a second step of fixing the desired position of the inner lead portion with tape; and half-etching the punched portion to cover it. A method for manufacturing a lead frame, comprising: a third step of making the punched portion extremely thin; and a fourth step of punching and separating the punched portion.