JPH06295966A - Processing method of metallic plate and lead frame and lead frame - Google Patents

Abstract

PURPOSE:To enable a metallic plate and lead frame to be processed in a fine and excellent processing shape while dimemsional precision to be increased without being affected by thermal deformation, adhering drosses and formation of oxide film within the processing method of metallic plate and lead frame. CONSTITUTION:Both surfaces of a metallic plate 301 are coated with a resist film 1 to form an etching pattern corresponding to the parts excluding the inner leads 303. Next, the parts corresponding to the inner leads 303 are irradiated with laser beams to form notch holes 3 penetrating this metallic plate 301 further etching away the sidewall parts 5 around these notch holes 3. At this time, the parts excluding the inner leads 303 are formed by the etching step simultaneously removing the drosses 4 near the notch holes 3 and oxide film so that the tapered shape of the notch holes 3 may be corrected thereby enabling the inner leads 303 in fine rectangular section to be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a metal plate capable of finely processing a metal plate into a finely processed shape and a method for processing a lead frame using the same.

[0002]

2. Description of the Related Art A lead frame is a metal plate on which fine processing patterns such as inner leads and outer leads are formed. In this lead frame, after the semiconductor chip is mounted, the terminals of the semiconductor chip and the inner lead are Are electrically connected.

By the way, in recent years, there has been a strong demand for higher density mounting and higher integration of semiconductor chips.
In order to deal with this, a lead frame on which a semiconductor chip is mounted has been developed with a fine and highly precise size and shape. In particular, the number of pins of the lead frame is being emphasized, and along with this, a processing technique capable of finely processing the pitch of the inner lead tips is required.

Etching has been the mainstream of recent processing techniques for forming such a multi-pin narrow-pitch lead frame from a metal plate. By this processing, a fine and well-processed shape can be easily obtained.

On the other hand, as a method for processing a metal plate, particularly a lead frame, which is a combination of etching and laser processing, Japanese Patent Laid-Open No. 123063/1992 and Japanese Patent Laid-Open No. 37/1992 are cited.
There is a method described in Japanese Patent No. 493. The former JP-A-3
In the processing method described in Japanese Patent No. 123063, a narrow pitch portion of an inner lead, particularly a portion having a lead gap of 70% or less of a plate thickness, is processed by laser light, and a portion having a narrow pitch such as an outer lead portion is pressed or etched. It is processed by. The latter Japanese Patent Laid-Open No. 4-374
In the processing method described in Japanese Patent Publication No. 93, a curved concave portion is formed by etching a predetermined amount of the total processing amount in the plate thickness direction, and then a portion not penetrated by etching is completely removed by laser light. The inner leads having a narrow pitch are processed by penetrating them.

The above laser processing is suitable for fine processing because the laser beam can be focused into a very small beam diameter, and it is easy to process a metal plate, especially a narrow pitch inner lead in a lead frame. Can be done reliably and reliably.

[0007]

When a fine portion is processed only by the above-described etching processing, side etching, that is, a phenomenon in which corrosion in the direction perpendicular to the plate thickness progresses, and the processed portion is The concave portion becomes a curved surface, and when fine processing is attempted, the etched portion does not penetrate in the plate thickness direction, so that processing becomes impossible. That is, there is a processing limit in the etching process. For example, in a lead frame, the pitch is 200 μm for a plate thickness of 150 μm.
Even if an attempt is made to process a narrow-pitch inner lead that is lower than the above by only etching, the processed portion becomes a concave portion having a curved surface due to side etching, and it cannot be processed without penetrating in the plate thickness direction.

On the other hand, according to the methods described in Japanese Patent Laid-Open Nos. 3-123063 and 4-37493,
Taking advantage of the characteristics of laser processing, it is possible to process fine parts such as high-density, narrow-pitch lead frames used for highly integrated semiconductor chips beyond the processing limit of etching, but in this case, laser light irradiation Due to the accompanying heat input, thermal deformation occurs, which makes it impossible to achieve a good shape and high dimensional accuracy. Further, the molten metal generated by laser processing adheres to the end surface after cutting as a dross, which causes a decrease in dimensional accuracy and a short circuit between leads. In addition, since the metal plate which has become high in temperature by laser processing forms an oxide film, it causes a contact failure at the time of connecting terminals. In this way, the above two conventional techniques are
No consideration is given to problems caused by laser processing, which is thermal processing.

Further, in the method described in Japanese Patent Laid-Open No. 4-37493, since the incompletely processed portion which was not penetrated by the etching process is penetrated by the laser beam, the sectional shape of the inner lead after the machining is not rectangular. The shape is polygonal and the flat parts required for terminal connection do not remain sufficiently on the inner leads. Therefore, it will be difficult later to electrically connect to the terminals of the semiconductor chip by wire bonding or the like.

Further, the above problem is not limited to the processing of the lead frame, but it is a common problem also in the case of finely processing other than the above by laser processing.

The object of the present invention is to be able to process finely and in good shape without being affected by thermal deformation, adhesion of dross, and formation of oxide film, and to improve dimensional accuracy. A method for processing a metal plate and a method for processing a lead frame using the same.

[0012]

In order to achieve the above object, according to the present invention, in a method of processing a metal plate for forming a gap of a predetermined shape in a metal plate, a resist for etching processing on both surfaces of the metal plate. A first step of coating the film, a second step of irradiating the metal plate with laser light from the surface of the resist film to form a notch hole penetrating the metal plate together with the resist film, and the metal And a third step of supplying an etching solution to the cutout holes of the plate to finish the cutout holes to form a gap having a predetermined shape.

Preferably, a fourth step of exposing the resist film to form an etching pattern is provided between the first step and the second step, and the third step is provided. In, the etching solution is also supplied to the etching pattern to simultaneously etch this portion.

Preferably, the etching solution is
It is supplied from the surface opposite to the surface irradiated with the laser light.

Preferably, the width of the gap having a predetermined shape finished by etching in the third step is
It is narrower than the thickness of the metal plate.

In order to achieve the above object, according to the present invention, a lead frame having a large number of inner leads connected to each terminal of a semiconductor chip and outer leads continuous with the inner leads is made of metal. In a method of processing a lead frame formed from a plate, a first step of coating both surfaces of a metal plate with a resist film for etching, and the resist film by irradiating the metal plate with laser light from the surface of the resist film. And a second step of forming a cutout hole penetrating the metal plate, and a step of finishing the cutout hole by supplying an etching solution to the cutout hole of the metal plate to form at least the inner lead. There is provided a method for processing a lead frame, comprising:

Preferably, the method further comprises a fourth step between the first step and the second step for exposing the resist film to form an etching pattern based on the lead frame shape. In the third step, the etching liquid is also supplied to the etching pattern to simultaneously etch this portion.

Further, in order to achieve the above object, according to the present invention, there is provided a lead frame processed by the above method for processing a lead frame.

[0019]

In the present invention constructed as described above, firstly, the first
In the step, both surfaces of the metal plate are covered with a resist film for etching. Then, in the second step, as a preliminary process, the metal plate is irradiated with laser light from the surface of the resist film to form a notch hole penetrating the metal plate together with the resist film. At this time, the resist film is naturally processed by the heat input by the laser light irradiation to form the opening, but the opening is slightly larger than the cutout hole penetrating therethrough. The size of the cutout hole to be formed by laser processing may be extremely smaller than the size of the finally formed gap because the cutout hole is slightly expanded by etching as described later. That is, the amount of processing with laser light can be reduced as compared with the case of processing with only conventional laser light. Therefore, the range affected by heat input is extremely small, and the effect of thermal deformation is almost eliminated.

Then, in a third step, the etching liquid is supplied to the cutout holes of the metal plate so that the inside of the cutout holes penetrated by the laser beam is sufficiently filled with the etching liquid, and the side wall portion around the cutout holes is filled with the etching liquid. The inside is surely etched, and finally removed near the opening of the resist film to form a gap having a predetermined shape. At this time, the dross and oxide film near the laser processed portion are also removed at the same time. That is, after the preliminary processing is performed with the laser light, the finishing processing is performed by etching, and the cross section of the processed portion of the metal plate becomes a clean rectangular cross section.

As described above, according to the present invention, since the finishing process is finally performed by etching which is a non-thermal process, there is no influence by heat, and the dross, the oxide film, etc. are removed, and the finally remaining portion. The processed shape (hereinafter, referred to as a residual portion) becomes good, and therefore the dimensional accuracy can be improved. Further, since the laser light can be condensed in an extremely small amount, the cutout hole can maintain a fine dimension even if the surrounding side wall portion is removed by the subsequent etching process. That is, it is possible to surely process a fine portion.

In the fourth step between the first step and the second step, the resist film is exposed to light to form an etching pattern, so that the notch is formed by the etching solution in the third step. The side wall portion of the hole is finished and at the same time, the etching liquid is supplied to the portion corresponding to the above etching pattern to perform etching. In this way, it is possible to perform the processing efficiently by simultaneously performing the etching processing on the portion preliminarily processed by the laser beam and the portion corresponding to the etching pattern which is not preliminarily processed. Further, since it is possible to reduce the laser processing which requires a relatively long time, it is possible to shorten the processing time.

In many cases, the shape of the cutout hole is a taper shape which becomes narrower in the traveling direction of the laser light due to the influence of the shape of the focused laser light. Further, the molten metal generated by the laser light irradiation adheres as a dross to the surface opposite to the surface irradiated with the laser light (hereinafter sometimes referred to as the back surface). In the present invention, the etching liquid is supplied from the back surface of the metal plate, so that the etching liquid is sufficiently spread inside the cutout hole formed by the laser beam, and the dross attached to the back surface is reliably removed. The tapered shape of is also corrected, and the cross section of the final remaining portion becomes a clean rectangular cross section. Therefore, when the remaining portion is used as the inner lead of the lead frame, it is possible to sufficiently secure the flat portion required for connecting the terminals.

Further, as described above, since the notch hole penetrating the metal plate is previously formed by the laser processing, the etching liquid is sufficiently supplied also into the notch hole penetrating during the finishing process by the etching process. It Therefore, even when performing extremely fine processing such as forming a gap having a width narrower than the plate thickness, a situation such as the conventional etching process in which the metal plate does not penetrate in the plate thickness direction does not occur, The etching process is surely performed.

The above-described processing method allows the metal plate to be processed finely and with a good processing shape,
It is suitable for forming a lead frame having a fine and highly accurate size and shape from a metal plate. In particular, it is preferable that at least the inner leads having a large number of pins and a narrow pitch are formed by a method of performing preliminary processing by laser processing and then finishing processing by etching.

Further, a large non-fine portion other than the inner lead is formed by forming an etching pattern corresponding to it on the resist film and simultaneously processing the portion corresponding to this etching pattern when performing the above etching process. You may.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for processing a metal plate and a method for processing a lead frame according to the present invention will be described with reference to FIGS. The present embodiment is an example in which a lead frame is formed by appropriately cutting a metal plate.

First, FIG. 2 shows an example of a lead frame processed by the metal plate processing method of this embodiment. In FIG. 2, a die pad 302 on which a semiconductor chip (not shown) is mounted is provided in the central portion of the metal plate 301. A large number of inner leads 303 surround the die pad 302 and these inner leads 303.
An outer lead 304 continuous with the above is provided. These inner lead 303 and outer lead 30 adjacent to each other
4 are supported by a dam bar 305 so as to be connected to each other. In addition, a cutout portion 306 is provided around the die pad 302 except for the arm 302a.
The inner leads 303 are separated from the die pad 302 by 6, and the adjacent inner leads 303 are divided by the notches 306. Further, a positioning hole 3 is formed on the outer peripheral portion of the metal plate 301 so as to position the semiconductor chip terminals and the inner leads 303 when the terminals are connected.
07 is provided. The dam bar 305 has a role of blocking the resin when the semiconductor chip is molded and a role of reinforcing the inner leads 303 and the outer leads 304, and is removed after the molding.

Further, the inner lead 303 extends so as to converge toward the die pad 302, and the tip portion thereof is electrically connected by wire bonding or the like after mounting a semiconductor chip (not shown) on the die pad 302. Wide enough to do. Therefore, the gap 303a between the inner leads 303 adjacent to each other has an extremely fine structure in which the gap in the inner portion is narrower than the plate thickness, and the processing of this portion is the most dimensional accuracy and cleanliness in the processing of the lead frame. Is the tough part.

Next, the process of processing the lead frame will be described. FIG. 1 is a cross-sectional view of a metal plate processed by the metal plate processing method of this embodiment, and FIG. 3 is a diagram for explaining the lead frame processing process. First, in step S1 of FIG. 3, preparation for processing is performed. That is, a strip-shaped metal plate wound in a coil shape, for example, a metal plate of steel, copper alloy, 42 alloy, Kovar, or the like is applied to the leveler to remove the curl. Then, the surface of the metal plate is washed to remove dirt, oil and the like. By using a strip-shaped metal plate wound in a coil shape as a material as described above, it is possible to continuously unwind and process a large number of lead frames.

Next, in step S2, resist processing is performed. That is, the photosensitizer is applied to the entire surfaces of both sides of the metal plate 301, and after drying, the resist film 1 shown in FIG.
Are coated. Then, an original plate (not shown) having a predetermined etching pattern based on the shape of the lead frame in FIG. 2 is superposed on this and exposed, and the pattern is transferred. Further, the exposed metal plate is dipped in a developing solution and developed using the solubility difference created by the exposure. In this way, a predetermined etching pattern based on the lead frame shape is formed on the resist film 1. However, the etching pattern formed by this resist processing corresponds to a relatively large portion such as the outer lead 304 and the positioning hole 307 other than the inner lead 303 in FIG. 2, and all the portions corresponding to the inner lead 303. It is covered with the resist film 1.

Next, in step S3, laser processing is performed. This laser processing is applied to the portion of the inner lead 303 in FIG. 2 where the etching pattern is not formed in step S2, that is, the portion having a narrow pitch and strict dimensional accuracy and cleanliness. Further, the laser processing device for generating the laser beam used at this time may be a general one known in the related art. An example of the optical system of such a laser processing apparatus is shown in FIG.

In FIG. 4, the laser beam 102 generated by the laser oscillator 101 is incident on the bending mirror 104 provided in the processing head 103 and guided toward the metal plate 301. Then, the laser beam 102 emits the nozzle 1
The light is incident on the condenser lens 106 located inside 05, is sufficiently condensed so as to have a required energy density that enables processing, and the processing position A of the metal plate 301 from the tip of the nozzle 105.
Is irradiated. Further, the nozzle 105 is provided with an assist gas supply port 107, and the assist gas is ejected coaxially from the tip of the nozzle so as to wrap the laser beam 102.

In step S3 of FIG. 3, first, in the laser processing apparatus as described above, various factors such as the oscillation period and energy density of the laser beam 102, the focus position of the condenser lens 106, the pressure of the assist gas, and the processing position are set. The conditions are set and the laser processing apparatus is prepared.

Subsequently, the metal plate 301 is subjected to laser processing by the laser processing apparatus. FIG. 5 is a view conceptually showing a cross section of the metal plate to be laser processed at this time.
In FIG. 5, the laser light 102 is condensed by the condenser lens 106 so that sufficient heat energy can be supplied, and the irradiated portion of the surface of the metal plate 301 is melted, and this serves as a heat source, and this melting is the surface. From then on, the metal plate 301 penetrates the metal plate 301 in the depth direction. The shape of the cut-out hole 3 that penetrates is a tapered shape that becomes thinner in the traveling direction of the laser light due to the influence of the shape of the focused laser light 102.

The resist film 1 is also processed by heat input by laser light irradiation. That is, the resist film 1 on the front surface is processed by laser light to form the opening 2 on the front surface side, and the resist film 1 on the back surface is processed after the notch hole 3 is penetrated to open the opening 2 on the back surface side. It is formed. The dimensions of the openings 2 on the front surface side and the back surface side are almost the same,
As shown in the figure, it is slightly larger than the cutout hole 3.

At this time, the size of the notch hole 3 to be formed is larger than the size of the gap finally formed by etching because the notch hole 3 is expanded by etching as described later. An extremely small size is sufficient, and the amount of processing with laser light can be reduced as compared with the case of processing with only conventional laser light. Therefore,
The range affected by heat input is extremely small, and the effect of thermal deformation is almost eliminated.

Further, the molten metal generated by the laser irradiation falls to some extent from the back surface of the metal plate 301, but the remaining molten metal solidifies as it is to form the dross 4. This dross is peculiar to laser processing, which is thermal processing, and causes a decrease in dimensional accuracy and a short circuit between leads.
Moreover, the vicinity of the portion of the metal plate 301 irradiated with the laser beam 102 becomes high in heat, so that an oxide film (not shown) is formed, which causes a contact failure at the time of terminal connection. However, these dross and oxide film are removed by etching as described later.

By the above laser processing, the cutout holes 3 penetrating the metal plate 301 as shown in FIG. 1B are sequentially formed. Then, the surface of the metal plate 301 is cleaned.

Next, in step S4, etching processing is performed. An example of the etching processing apparatus used at this time is shown in FIG. In FIG. 6, the metal plate 301 is a band-shaped material, and is carried into the etching apparatus 200 by the roller 201, and the etching solution 20 is supplied from the nozzle 202.
3 is jetted and the etched metal plate 301 is carried out by the roller 204. The surface on which the etching liquid 203 is sprayed is the back surface of the metal plate 301, that is, the surface opposite to the surface irradiated with the laser light. In FIG. 6, the etching liquid 203 is jetted from below on the paper surface, assuming that the laser beam is irradiated from above on the paper surface.

By this etching process, in the inner lead 303, the etching liquid is sufficiently spread even inside the notch hole 3, and the side wall portion 5 around it shown in FIG. 1C is surely etched to the inside. Metal plate 3
01 is removed to the vicinity of the end of the opening 2 of the resist film 1. Finally, the gap 303a is formed and the inner lead 303 is formed. Moreover, inner lead 3
The cross section of 03 is a clean rectangle (see FIG. 1 (d)).
At this time, the dross 4 and the oxide film attached to the back surface are also surely removed by the jetting etching solution, and the tapered shape of the cutout hole 3 is also corrected neatly to form a smooth surface. Removing dross 4 and oxide film
Although it was difficult in the past, in the present embodiment, these are easily removed by etching.

By this etching process, the portion corresponding to the etching pattern formed in step S2 is also processed at the same time, and outer leads 304, positioning holes 307, etc. are formed. That is, a relatively large portion is not preliminarily processed by laser light, but is processed only by etching having higher processing efficiency than laser processing. Therefore, it is possible to perform the processing efficiently, and it is possible to reduce the laser processing by performing the laser processing, which requires a relatively long time, only on a fine portion such as the inner lead 302, so that the processing time can be shortened. Is.

In this case, however, the volume of the portion removed by corrosion is greatly different between the fine portion such as the side wall portion 5 around the cutout hole 3 and the portion corresponding to the large non-fine pattern. However, there is a concern that the time until the etching process ends may be different. But,
The corrosion rate of the part with a small area in contact with the etching solution is
Since the corrosion rate is slower than the corrosion rate of the part where the area in contact with the etching solution is large, the difference in this rate is almost offset by the volume to be removed, and there is not much difference in the time until the etching processing of both ends. it is conceivable that.

After that, as shown in FIG. 1D, the resist film 1 on the surface of the metal plate 301 is removed, and further, cleaning and drying are performed, and the processing of the metal plate 301 is completed.

The lead frame processed as described above is used in a semiconductor device as shown in FIG. That is, the semiconductor chip 31 is attached to the die pad 302 (see FIG. 2).
0 is mounted, the inner lead 303 and the semiconductor chip 3
The terminals 10 are electrically connected by wires 311 such as gold wires, and the semiconductor chip 310 is connected by the resin mold 312.
The portion including the inner lead 303 and the inner lead 303 is sealed, the dam bar 305 (see FIG. 2) is cut, and the outer lead 3
The semiconductor device 320 is manufactured by bending 04.

In the above-described method for processing a metal plate of the present embodiment, when the cutout hole 3 is laser-processed, the amount of processing by laser light can be reduced as compared with the conventional case where only laser light is processed. Therefore, the range affected by heat input is reduced, and thermal deformation can be prevented. After that, since the side wall portion 5 is removed by the etching process which is a non-thermal process, the etching solution is not influenced by heat at this time, and the etching liquid is sprayed from the back surface of the metal plate 301.
The dross 4 and the oxide film are removed, and the tapered shape of the cutout hole 3 is also corrected, so that the cross section of the inner lead 303 becomes a clean rectangle. Further, since the laser light can be condensed in a very small amount, the cutout hole 3 can maintain a fine dimension even if the surrounding side wall portion 5 is removed by the subsequent etching processing, and a gap having a width narrower than the plate thickness is formed. can do.

Further, the method of performing the pre-processing by the laser processing and then the etching processing as in the present embodiment is capable of processing the metal plate finely and in a good processing shape and with high accuracy. If it is applied to the processing of the inner lead 303 having a narrow pitch and strict dimensional accuracy and cleanliness as described above, the effect can be utilized to the maximum extent.

Further, the outer lead 304, the positioning hole 307, and the like are not preliminarily processed with a laser beam, but the side wall portion 5 of the cutout hole 3 formed in the inner lead 303 is etched at the same time. It can be processed efficiently. Further, since the laser processing which requires a relatively long time can be performed only on the fine portion such as the inner lead 302 to reduce the laser processing, the processing time can be shortened.

Further, since a strip-shaped metal plate wound in a coil shape can be used as a material, it is possible to continuously unwind this and to process a large number of lead frames. By continuously processing in this way, not only the above-mentioned effects can be obtained, but also mass production becomes possible and cost reduction can be achieved.

Another embodiment of the method for processing a metal plate and the method for processing a lead frame according to the present invention will be described with reference to FIGS. This embodiment is also an example in which a metal plate is appropriately cut out to form a lead frame as shown in FIG.

First, in step S11 of FIG. 8, processing preparation and press processing are performed. That is, the strip-shaped metal plate wound in the coil shape is applied to the leveler to remove the curl. Then, a large part of the outer lead 304, the positioning hole 307, etc. (see FIG. 2) is punched by a press. Although this press working is not suitable for fine processing because the processing end surface is rough, it can be efficiently processed in a shorter time than laser processing or etching processing, and is therefore suitable for processing a large portion as described above. Further, the surface of the metal plate is washed to remove dirt, oil and the like.
Also in this case, a strip-shaped metal plate wound in a coil shape can be used as a raw material to unwind and continuously process a large number of lead frames.

Next, in step S12, a first resist process is performed. That is, the resist resin is applied to both surfaces of the metal plate and dried to cover the entire surfaces of both surfaces of the metal plate with the resist film. In this first resist process, no etching pattern is formed, and the outer lead 304 and the positioning hole 3 that have been pressed are processed.
A large portion such as 07 is also covered with the resist film in this step.

Next, in step S13, laser processing is performed by the same method as described with reference to FIG. That is, first, various conditions for laser processing are set, and after preparation of the laser processing apparatus, laser light is irradiated from the resist film surface to form a cutout hole penetrating the metal plate.
Then, the surface of this metal plate is cleaned. Here, the laser processing is performed on a portion corresponding to the inner portion 303A of the inner lead 303 in FIG. 2, which is a portion having an extremely narrow pitch and having strict dimensional accuracy and cleanliness. Therefore,
The outer portion 303B, which is a relatively larger portion than the inner portion 303A of the inner lead, and the cutout portion 306 are not yet formed, and the large portion such as the pressed outer lead 304 and the positioning hole 307 is a resist film. Remains covered with.

Next, in step S14, a first etching process is performed. Also at this time, the etching liquid is sprayed from the back surface of the metal plate, that is, the surface opposite to the surface irradiated with the laser light. By this etching process, the etching solution is sufficiently spread inside the notch hole in the portion corresponding to the inner portion 303A of the inner lead, and the side wall portion around it is surely etched to the inside, and finally the gap is formed. Then, the inner portion 303A of the inner lead is formed. Also at this time, the dross attached to the back surface and the oxide film are surely removed by the jetting etching solution, and the tapered shape of the notch hole is also corrected neatly. However, the outer portion 303 of the inner lead
B and the notch 306 have not been formed yet, and the outer lead 304 and the positioning hole 307 that have been pressed are processed.
Since such portions are covered with the resist film, they are not etched.

After that, the resist film is removed, and the metal plate is washed and dried. Also in this embodiment, as in the above-described embodiments, the remaining portion of the metal plate, that is, the cross section of the inner lead 303 has a clean rectangular shape.

Next, in step S15, a second resist process is performed by the same method as described in step S2 of FIG. That is, the photosensitizer is applied to both surfaces of the metal plate, and a predetermined etching pattern based on the shape of the lead frame is transferred by exposure and developed. The etching pattern formed by the second resist treatment corresponds to the outer portion 303B and the cutout portion 306 of the inner lead which are left without being formed. Therefore, the inner portion 303A of the inner lead processed in steps S13 and S14, and step S11
Large parts such as the outer leads 304 and the positioning holes 307, which have been pressed by, are entirely covered with the resist film in this step.

Next, in step S16, a second etching process is performed. At this time, the etching solution does not necessarily have to be sprayed from the back surface of the metal plate, but when unwinding a strip-shaped metal plate wound in a coil shape and continuously processing a large number of lead frames, the equipment is simple. In consideration of this, the etching solution may be sprayed from the back surface of the metal plate as in step S14. By this etching process, the outer portion 303B of the inner lead and the cutout portion 306 are formed. Since this portion is a relatively larger portion than the inner portion 303A, it can be sufficiently processed by etching without performing preliminary processing with laser light. However, the inner portion 303A of the inner lead which has already been processed, and the large portion such as the pressed outer lead 304 and the positioning hole 307 are covered with the resist film and are not etched.

After that, the resist film is removed, cleaning and drying are performed, and the processing of the metal plate 301 is completed.

As described above, according to this embodiment, the same effect as that of the above-mentioned embodiment can be obtained, and the outer lead 3
04, the positioning hole 307, and the like, the largest part is punched by a conventional press, and the inner part 303
The outer portion 303B of the inner lead and the cutout portion 306, which are relatively larger than A, are etched in the same manner as in the prior art without being preliminarily processed with laser light. It can be processed in a short time. In this way, processing including preprocessing by laser light, that is, by combining processing that emphasizes fine and good processing shape and processing that emphasizes processing efficiency such as conventional etching or press processing,
The processing efficiency can be improved.

The order of the first etching process and the second etching process may be reversed. In addition, without performing the pressing process, all the parts other than the inner part 303A of the inner lead are processed by the second etching process, or conversely, the second etching process is not performed, and the parts other than the inner part 303A of the inner lead are not processed. All parts may be processed by pressing.

Further, although the case where the lead frame is formed from the metal plate has been described in the above two embodiments, the processing method of the metal plate of the present invention can be applied to the case of processing other than the lead frame.

[0062]

EFFECTS OF THE INVENTION According to the present invention, it is possible to perform processing so as to finally obtain a good processed shape without being affected by thermal deformation, adhesion of dross, and formation of an oxide film, and it is possible to perform fine processing. Can be realized and the dimensional accuracy can be improved.

Further, when finishing the portion preliminarily processed by the laser beam, the portion not preliminarily processed is also etched at the same time, so that the processing can be efficiently carried out.
The processing time can be shortened by reducing the laser processing which requires a relatively long time.

Further, since the processing which attaches importance to the fine and favorable processing shape and the processing which attaches importance to the processing efficiency such as the conventional etching processing or press processing are combined, the processing efficiency can be improved.

Further, according to the present invention, it is possible to process fine inner leads with a narrow pitch in a lead frame with good cleanliness and dimensional accuracy, and to unwind a strip-shaped metal plate wound in a coil shape. Since a large number of lead frames can be continuously processed, mass production becomes possible and cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an inner lead of a lead frame formed by a method for processing a metal plate according to an embodiment of the present invention, (a) showing a state where both surfaces of the metal plate are coated with a resist film. , (B) shows a state in which a notch hole is formed in a metal plate by laser processing, (c) shows a side wall portion removed by etching, and (d) shows a gap formed by etching. FIG. 6 is a view showing a state in which the resist film is removed.

FIG. 2 is a view showing an example of a lead frame processed by the method for processing a metal plate shown in FIG.

FIG. 3 is a diagram illustrating a process of processing the lead frame shown in FIG.

FIG. 4 is a diagram showing an example of an optical system of a laser processing apparatus used in step S3 of FIG.

5 is a view conceptually showing a cross section of a metal plate which is laser-processed by a laser processing device having the optical system shown in FIG.

FIG. 6 is a diagram showing an example of an etching processing apparatus used in step S4 of FIG.

FIG. 7 is a diagram showing an example of a semiconductor device manufactured using the lead frame of FIG.

FIG. 8 is a diagram showing a method for processing a metal plate according to another embodiment of the present invention, which is a view for explaining a process for processing a lead frame.

[Explanation of symbols]

 1 Resist Film 2 (Resist Film) Opening 3 Notch Hole 4 Dross 5 Sidewall Part (Around Notch Hole) 102 Laser Light 106 Condenser Lens 200 Etching Machine 202 Nozzle 203 Etching Liquid 301 Metal Plate 303 Inner Lead 303a (inner lead) gap 303A (inner lead) inner part 303B (inner lead) outer part 304 outer lead 306 notch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeyuki Sakurai 650 Kazutachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd.Tsuchiura factory (72) Inventor Yoshiya Nagano 650 Kintate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co. Ceremony Company Tsuchiura Factory

Claims (7)

[Claims] 1. A method of processing a metal plate for forming a gap of a predetermined shape in a metal plate, comprising: a first step of coating both surfaces of the metal plate with a resist film for etching processing; A second step of irradiating the metal plate with laser light to form a cutout hole penetrating the metal plate together with the resist film; and supplying an etching solution to the cutout hole of the metal plate to form the cutout hole. And a third step of performing a finishing process to form a gap having a predetermined shape. 2. A fourth step of exposing the resist film to form an etching pattern between the first step and the second step, further comprising the step of forming the etching pattern in the third step. The method for processing a metal plate according to claim 1, wherein an etching liquid is also supplied to the etching pattern to simultaneously etch this portion. 3. The method for processing a metal plate according to claim 1, wherein the etching liquid is supplied from a surface opposite to a surface irradiated with the laser light. 4. The method for processing a metal plate according to claim 1, wherein the width of the gap having a predetermined shape finished by etching in the third step is narrower than the plate thickness of the metal plate. 5. A method of processing a lead frame, which comprises forming a lead frame having a large number of inner leads connected to respective terminals of a semiconductor chip and outer leads continuous with the inner leads from a metal plate. A first step of coating a resist film for etching on both surfaces of the metal plate, and irradiating the metal plate with laser light from the surface of the resist film to form a notch hole that penetrates the metal plate together with the resist film. A lead frame comprising: a second step; and a third step of supplying an etching liquid to the cutout hole of the metal plate to finish the cutout hole to form at least the inner lead. Processing method. 6. A fourth step is provided between the first step and the second step, in which the resist film is exposed to light to form an etching pattern based on the lead frame shape. 6. The method for processing a lead frame according to claim 5, wherein in the step of 3, the etching liquid is also supplied to the etching pattern to simultaneously etch this portion. 7. A lead frame processed by the method for processing a lead frame according to claim 5.