JPH11145365A - Lead frame for ic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate bending separation from a lead retaining part, without bending it many times by stretching the width of a lead, and largely arranging the lead in the vicinities of both ends of a long edge direction of a rectangular half etch part. SOLUTION: At the center of a lead bending separation part 14 of a lead 12, a rectangular half etch part 16, e.g. whose short edge is set to be almost 0.5 times a width A of the lead, and whose long edge is set to be almost 1.2 times the width A of the lead is arranged. In the vicinities of both the ends of the long edge direction of the rectangular half etch part 16 which is formed at the center of the lead bending separation part 14, the width of the lead is stretched, and the lead is largely arranged. That is, the size of the section in the widthwise direction of the lead becomes sufficient. As a result, bending from the lead bending separation part is not generated in an etching process for manufacturing the lead frame and a post-working process. Bending separation from a lead retaining part can be facilitated by bending the lead frame at the lead bending separation part 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC lead frame manufactured by a photo-etching method, and more particularly to an IC lead frame that facilitates separating a lead from a lead support.

[0002]

2. Description of the Related Art Conventionally, when manufacturing an IC lead frame having a plate thickness of, for example, about 0.15 mm to 0.25 mm using a photo-etching method, it is easy to separate a lead from a lead supporting portion. Therefore, a half-etched portion is provided in the lead separation portion, and the width of the lead separation portion is narrowed.

FIG. 4 is a plan view showing an example of an IC lead frame. In FIG. 4, the lead (2) is supported by a lead support (5). A dotted line 3 indicates an area where a package made of, for example, plastic is formed after the IC chip is mounted. After the package is formed, the lead frame is bent at the lead separating section (4) and separated from the lead supporting section (5). tt ′ is a lead separation part (4) where the lead frame is separated from the lead support part (5).
Of the lead (2) is indicated by a line.

[0005] More specifically, FIG. 5 is an enlarged plan view of a lead separating portion (4) of a lead frame, which is an example of a conventional method. As shown in FIG. A square half-etched portion (6) having one side of approximately 1/4 of the width of the lead is provided at the center of ()). The lead separation portion (4) is provided with a narrow lead in an arc shape (7).

FIGS. 6A, 6B and 6C show p in FIG.
7 (a), 7 (b) and 7 (c) are ss ′, FIG. 5 (b) and FIG.
It is sectional drawing of each of tt 'and uu'. As shown in FIGS. 6 (a), 6 (b) and 6 (c), the cross-sectional shape of the lead separation portion (4) according to the conventional method is as follows. 7A, 7B, and 7C, the original thickness is not etched, the original thickness is not etched, the half-etch is, and the original thickness is not etched. It is thick.

For example, when a lead frame is bent at a lead separating section (4) after a plastic package is molded and separated from a lead supporting section (5), the lead frame according to the conventional method is difficult to separate. It bends many times, at least four times,
Further, the separated lead may be deformed.
In addition, instead of being separated by bending at the lead separating portion (4), separation may be performed by shearing at the lead separating portion (4). In this case, a square half-etch portion (6) is used. It is not easy to adjust the shear position.

On the other hand, in order to facilitate separation by bending, the square half-etched portion (6) in the lead separation portion (4) is made large and the width (d) of the lead in the arc-shaped (7) portion. Is narrow, the bending from the lead separation part (4) is likely to occur in the etching step for manufacturing the lead frame and the post-processing step.

The thickness of the metal sheet is about 0.2 m.
When using 42 materials of about m (42% by weight of nickel and the balance of iron), the width (a) of the lead in FIG.
To the extent, the size of the lead separation part (4) (a
× e) is about 0.1 × 0.1 mm, and the size (b × c) of the square half-etched portion (6) is about 0.025 × 0.
The depth (g) is about 0.1 mm, which is １ ／ of the original plate thickness, as shown in FIG. In the lead separation part (4), the width (d) of the lead in the arc-shaped part (7) is about 0.025 mm.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for folding a lead frame for an IC at a lead separating portion after the package is formed and separating the lead frame from the lead supporting portion.
An object of the present invention is to provide an IC lead frame that can be easily separated without performing bending many times. It is another object of the present invention to provide an IC lead frame in which a separated lead is not deformed. Another object of the present invention is to provide an IC lead frame in which the shearing position can be easily adjusted when the lead is separated by a shearing process at the lead separating portion instead of the bending at the lead separating portion. It was done. It is another object of the present invention to achieve the above object without causing bending from a lead separation portion in an etching step for manufacturing a lead frame and a post-processing step.

[0010]

According to the present invention, in order to achieve the above object, in a lead frame for an IC manufactured by using a photo-etching method, a lead separating portion near a connecting portion between a lead supporting portion and a lead is provided. And an IC lead frame characterized in that a half-etched portion is provided and the width of the lead separation portion near both ends of the half-etched portion is extended to be large.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An IC lead frame according to the present invention will be described below based on one embodiment. FIG. 1 is a plan view showing an embodiment of an IC lead frame according to the present invention, and is an enlarged plan view of a lead separation portion of a lead in the lead frame. As shown in FIG.
In the center of the lead separation part (14) of the lead (12),
A rectangular half-etch portion (16) having a short side approximately 0.5 times the width (A) of the lead and a long side approximately 1.2 times the width (A) of the lead is provided.

In the vicinity of both ends in the long side direction of the rectangular half-etch portion (16) provided at the center of the lead separation portion (14), the width of the lead is extended to the position 18 in FIG. Largely provided. As shown in FIG. 1, both sides of the lead separation portion (14) are arc-shaped (1).
7).

FIGS. 2A, 2B, and 3C show P in FIG.
3 (A), 3 (B), and 3 (C) are SS ′, FIG. 3 (A), FIG. 3 (B), and FIG.
It is sectional drawing of each of TT 'and UU'. The cross-sectional shape of the lead separating portion (14) is shown in FIG.
As shown in (a), (b) and (c), the original plate thickness is not etched / half-etched / original plate thickness is not etched, and the width direction of the lead is shown in FIG.
As shown in (a), (b) and (c), the original plate thickness is not etched / half-etched / the original plate thickness is not etched.

The thickness of the metal sheet is about 0.2 m.
When about 42 m (nickel 42% by weight, balance iron) is used, the lead width (A) in FIG. 1 is about 0.1 mm.
The size (A ′ × E) of the lead separation part (14) is about 0.12 × 0.12 mm, and the size (B × C) of the rectangular half-etch part (16) is about 0 .0
The depth (G) is about 0.14 mm, which is about 0.7 times the original thickness, as shown in FIG. In the lead separation portion (14), the width (D) of the lead in the arcuate (7) portion is about 0.025.
mm, and the extended size (F) is about 0.02 mm.

As shown in FIG. 1, the lead separating portion (1
In the half-etched portion (16) provided at the center of 4), the short side of the rectangle is approximately 0.05 m, which is approximately 0.5 times the lead width (A).
m, and the long side is about 0.2 times about 1.2 times the lead width (A).
It is about 12mm, but rectangular half-etched part (16)
In the vicinity of both ends in the long side direction of the lead, the width of the lead is extended to the position of 18 in FIG. 1 and provided so as to be large, and as shown in FIG. It has become something. Therefore, in the etching step for manufacturing the lead frame and the post-processing step, bending from the lead separation portion does not occur.

The half-etched portion (16) provided at the center of the lead separating portion (14) has a rectangular short side having a length of approximately 0.05 mm, which is approximately 0.5 times the lead width (A), and a length of approximately 0.5 mm. The side is about 0.12 mm, which is about 1.2 times the width (A) of the lead, and the depth (G) of the half-etched portion (16) is about 0.7 times the thickness of the plate. Since the depth is about 0.14 mm, the IC lead frame is easily bent at the lead separating section (14) and separated from the lead supporting section. Further, the separated lead is not deformed. Further, instead of the separation by bending at the lead separation section (14), when cutting by shearing at the lead separation section (14), it is easy to adjust the shearing position. .

FIG. 8A to FIG.
FIG. 4 shows an embodiment of a manufacturing process of a lead frame for C, and the lead separating portion (14) in FIG.
It is explanatory drawing represented by T 'cross section. In FIG. 8A,
As the plate-shaped metal thin plate (10) serving as an IC lead frame, for example, a plate thickness of about 0.2 mm and a size of about 50 × 50
cm of 42 materials are used. The IC lead frame is manufactured by arranging a large number of IC lead frames. As described above, in FIG. 8, the vicinity of the lead separation portion (14) is enlarged.

First, as shown in FIG. 8B, a photoresist layer (20) is formed on a thin metal plate (10). Next, as an exposure mask having a predetermined pattern, for example, a surface exposure mask (30), a half-etched portion (1
The portion that becomes the pattern of the lead (12) except for 6) is a light transmitting portion, and the half-etch portion (16) and the lead (1)
The light shielding part other than the part which becomes the pattern of 2)
As the back surface exposure mask (31), a lead (12)
As shown in FIG. 8C, a surface exposure mask (see FIG. 8C) is used on one surface of the metal thin plate (10). 30), and a mask (31) for back exposure is applied to the other surface of the thin metal plate (10).

Next, light irradiation (8
By performing step (0), the photoresist layer at the portion where the pattern of the lead (12) is to be formed is light-cured. Subsequently, by performing development, the unexposed portion of the photoresist layer is removed, and as shown in FIG. 8D, the surface photoresist film exposing the metal other than the portion that becomes the pattern of the lead (12). (40), a backside photoresist film (41) is obtained.

Next, as shown in FIG. 8E, first etching is performed in which the etching solution (90) is brought into contact only with the surface of the thin metal plate. The exposed metal sheet portion, that is, the metal sheet other than the portion that becomes the pattern of the lead (12) is selectively dissolved and removed, but as shown in FIG. 8F, about 40% of the sheet thickness on the metal sheet surface side. The first etching is performed until about 0.08 mm is dissolved and removed. In FIG. 8, reference numeral 50 denotes an etched portion after the first etching.

Next, as shown in FIG. 8 (g), a second etching is performed in which an etching solution (90) is brought into contact with the front and back surfaces of the thin metal plate. Similarly to the first etching, the exposed metal sheet portion, that is, the metal sheet other than the portion serving as the pattern of the lead (12) is selectively dissolved and removed. As shown in FIG. 8 (h), the metal sheet other than the part where the pattern of the lead (12) is formed is simultaneously etched from the front and back surfaces, and about 0.5% which is about 60% of the remaining sheet thickness of the metal sheet.
The second etching is performed until 12 mm is etched and through holes are formed from the front and back surfaces. Half etch part (1
In (6), since etching is performed only from the front surface, about 0.06 mm, which is about 30% of the sheet thickness on the back side of the thin metal sheet, is not etched and remains as a half-etched portion (16).

The etching is performed by a spray etching method using a strongly acidic etching solution, for example, a ferric chloride solution. Next, the metal thin plate is washed with water and washed, the front photoresist film (40) and the back photoresist film (41) are stripped, washed with water and dried to obtain an IC lead frame shown in FIG.

[0023]

According to the present invention, the half-etched portion provided at the center of the lead separation portion has a rectangular short side approximately 0.5 times the lead width and a long side approximately 1.2 times the lead width. However, in the vicinity of both ends in the long side direction of the rectangular half-etch portion,
Since the width of the lead is extended to be large, the size of the cross section in the width direction of the lead is sufficient.
Therefore, in the etching step for manufacturing the IC lead frame and the post-processing step, bending from the lead separation portion does not occur. In the half-etched portion provided at the center of the lead separating portion, the short side of the rectangle is approximately 0.5 times the width of the lead and the long side is approximately 1.2 times the width of the lead.
Since the depth of the half-etched part is about 0.7 times the thickness of the board, the IC lead frame is bent at the lead separation part and separated from the lead support part. In addition, an IC lead frame that can be easily separated without performing bending many times is provided. In addition, an IC lead frame in which the separated leads do not deform is obtained. Further, in place of the separation by bending at the lead separation section, it is easy to adjust the shearing position when performing separation by shearing processing at the lead separation section.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view showing a lead separation portion of an embodiment of an IC lead frame according to the present invention.

FIGS. 2A, 2B and 2C show PP ′ in FIG.
It is sectional drawing of each of QQ 'and RR'.

FIGS. 3A, 3B, and 3C show SS ′ in FIG. 1;
It is sectional drawing of each of TT 'and UU'.

FIG. 4 is a plan view showing an example of an IC lead frame according to a conventional method.

FIG. 5 is an enlarged plan view showing an example of a lead separation portion in a conventional method.

6 (a), (b) and (c) show pp ′,
It is sectional drawing of each of qq 'and rr'.

7 (a), (b), and (c) show ss ′,
It is sectional drawing of each of tt 'and uu'.

FIGS. 8A to 8I show an embodiment of a manufacturing process of an IC lead frame according to the present invention.

[Explanation of symbols]

 1 Lead frame for IC 2, 12 Lead 3 Area where package is molded 4, 14 Lead break-off part 5 Lead support part 6 Half-etch part in conventional method 7 Conventional Arc shape in the method 10 Metal thin plate 16 Half etched portion 17 Arc shape 18 Extended position 20 Photoresist layer 30 Front surface exposure mask 31 Back surface exposure mask 40 Front surface photo Resist film 41 {backside photoresist film 50} etched portion after first etching 80} light irradiation 90} etchant A, a {lead width ExA ', exa} lead separation Part size B × C, b × c ‥‥ half-etch part size D, d ‥‥ arc-shaped part lead width F ‥‥ extended size G, g ‥‥ half-etch part depth

Claims (1)

[Claims] 1. An IC manufactured by using a photo-etching method.
In the lead frame for use, a half-etch portion is provided in a lead separation portion near the connection portion between the lead support portion and the lead,
A lead frame for an IC, wherein the width of the lead separation portion near both ends of the half-etched portion is extended to be large.