JP2843645B2 - Metal plate processing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for finely processing a metal plate, and is particularly effective for finely processing a relatively small metal plate such as a lead frame as a semiconductor assembly member. And a method of processing a metal plate.

[Prior Art] In recent years, there has been an even more intense demand for high-density mounting of semiconductor elements, and under such circumstances, the number of pins of a lead frame has been developed. At present, lead frames having more than 300 pins are also manufactured. With the increase in the number of pins in the lead frame, the pitch of the inner leads of the lead frame has been
Lead frames that have been reduced from about 200 μm to less than 200 μm are now being developed. As a method of manufacturing such a multi-pin, narrow-pitch lead frame, manufacturing by etching has conventionally been the mainstream. This manufacturing method by etching is easy to increase the number of pins and narrow the pitch compared to the manufacturing method by stamping.However, when manufacturing a lead frame having an inner lead pitch of less than 200 μm, a reduction in etching factor and pattern correction are required. It is accompanied by various obstacles such as limitations and yield deterioration.

As one means to cope with the increase in the number of pins and the reduction in the number of pins of the lead frame, it is conceivable to form a metal plate as a processing base material from a thin plate having a small thickness. Therefore, there is a limit in reducing the plate thickness.

As another means for increasing the number of pins and reducing the number of pins, improvement of an etching factor by an additive of an etching solution or the like can be considered, but it has not yet been possible to effectively improve the etching factor.

[Problems to be Solved by the Invention] Under such circumstances, a metal plate whose thickness cannot be reduced so much is processed by etching to obtain a multi-pin of 300 pins or more and a lead frame of a narrow pitch of 200 μm or less. When it is attempted to form, the outer lead portions that do not require much fine processing are penetrated by etching, but the inner lead portions that require fine processing are not penetrated by etching. In addition, even if the inner leads are penetrated, there arises a problem that a flat width of the leads and a desired narrow pitch of the leads required for wire bonding and molding cannot be secured.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a metal plate processing method capable of performing fine processing of a metal plate with high accuracy, easily and in a short time. It is.

Another object of the present invention is to provide a method for manufacturing a lead frame capable of easily manufacturing a lead frame having, for example, 300 pins or more and a narrow pitch of, for example, 200 μm or less.

[Means for Solving the Problems] In order to solve the above problems, a method for processing a metal plate according to the first aspect of the present invention is characterized in that a predetermined portion is etched by etching a predetermined portion of a total thickness in the thickness direction of the metal plate. And a laser beam processing step of irradiating a laser beam to at least a part of the etched portion to process the remaining amount of the entire processing amount.

The invention of claim 2 is characterized in that, in the etching step, a resist having a predetermined pattern is made on one or both surfaces of the metal plate, and etching is performed using the resist.

Further, the invention of claim 3 is characterized in that the laser beam processing step is performed before the resist is stripped.

Further, the invention of claim 4 is characterized in that the laser beam diameter in the laser beam processing step is set to be larger than the width of a predetermined pattern opening of the resist.

Further, the invention of claim 5 is characterized in that the laser beam processing step is performed after the resist is stripped.

Further, in the invention according to claim 6, in the laser beam processing step,
It is characterized in that a predetermined area or the whole surface including at least the etched portion of the metal plate is irradiated with a laser beam.

Further, the invention of claim 7 is characterized in that the laser beam diameter in the laser beam processing step is set smaller than the width of the opening of the predetermined pattern of the resist.

Further, according to the invention of claim 8, the etching step
In the fine processing part of the metal plate, a predetermined amount of the total processing amount in the thickness direction is processed, and in the processing parts other than the fine processing part of the metal plate, the entire processing amount in the thickness direction is processed. It is characterized in that the remaining amount of the entire processing amount of the fine processing portion is processed.

Furthermore, in the invention of claim 9, in the etching step, a resist having a predetermined pattern is made on the surface of the metal plate on which the etching processing is performed, and the etching is performed using the resist. It is characterized in that the predetermined pattern opening width of the resist in a processing portion other than the fine processing portion of the metal plate is set to be larger than the opening width.

A tenth aspect of the present invention is characterized in that a positioning mark is formed at the time of etching, and the positioning accuracy of the laser beam is managed by the positioning mark.

Further, the invention of claim 11 is characterized in that the metal plate is a lead frame.

[Operation] In the method for processing a metal plate of the present invention having the above-described configuration, first, a processing portion of a metal plate whose thickness is reduced by a predetermined amount in the thickness direction by etching is processed by laser beam processing. , The laser beam processing time is greatly reduced. In addition, since the amount of metal dissolved by the laser beam processing is smaller by the amount of the etching processing, dross (dissolution and reattachment) generated by the laser beam processing is reduced.

Further, in the case of processing by only etching as in the past, fine processing is limited due to the relationship between the processing plate thickness and the processing allowance by etching. However, according to the present invention, a predetermined amount of the processing plate thickness is etched. , Not only does not require much processing allowance, but also cuts the metal plate with a laser beam, so that a higher level of fine processing is possible.

Further, by performing the laser beam processing step before the resist is stripped, the resist functions as a mask for the laser beam. Therefore, processing can be performed with a relatively large laser beam diameter, and the positional accuracy of the laser beam does not need to be so strict.
Not only processing becomes extremely simple, but also processing can be performed in a short time.

Further, in the etching process, the metal plate is processed by a predetermined amount of the total processing amount in the micro-processed portion, but is processed in the processing portion other than the micro-processed portion of the metal plate, and the laser processing is performed. By processing the remaining amount of the entire processing amount of the fine processing portion by the beam processing step, the laser beam processing portion is reduced, so that the fine processing time by the laser can be reduced.

Further, by forming positioning marks on the metal plate during the etching process, and by controlling the positioning accuracy of the laser beam with the positioning marks, the positioning of the laser beam can be performed easily and with high accuracy, and the fine processing time can be improved. Can be further reduced, and the processing accuracy can be further improved.

Further, by applying the metal processing method of the present invention to the processing of a lead frame, it becomes possible to perform even higher-level fine processing.
A lead frame having leads with a narrow pitch of not more than 00 μm can be manufactured with high precision and easily.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing an example of a lead frame manufactured by using the metal plate processing method according to the present invention.

As shown in FIG. 1, a lead frame 1 is a QFP (Quad Flat Package) type lead frame made of a metal plate having a predetermined thickness such as steel, copper alloy, 42 alloy, and Kovar, and is arranged vertically. And a pair of rails 2, 2 arranged in parallel with each other. A die pad 4 on which the semiconductor element 3 is mounted is provided between the pair of rails 2. A predetermined number of inner leads 5,5,... And outer leads 6,6,... Which are continuous with the inner leads 5 are arranged so as to surround the die pad 4. The inner leads 5 and the outer leads 6 Are supported by the rails 2,2.

FIG. 2 is a view showing a process for manufacturing such a lead frame 1.

In manufacturing the lead frame 1, first, an etching process is performed. That is, resists 9 and 10 having a predetermined pattern P are made on both upper and lower surfaces of a metal plate 8 having a predetermined thickness shown in FIG. 2 (a), as shown in FIG. 2 (b). Next, using the resists 9 and 10 made as shown in FIG.
Chemical etching is performed on both surfaces of the metal plate 8 by a predetermined etching depth of the total processing amount in the thickness direction.
Therefore, the etched part by this etching
The thickness t of the metal plate 8 at e ₁ and e ₂ is the thickness t of the other unprocessed portion.
_It is thinner than ₀ , and the etched portions e ₁ and e ₂ are half-etched portions. Conventionally known resists and etching solutions can be used.

Next, a laser beam processing step is performed on the metal plate 8. That is, the laser beam L is applied to the etched portions e ₁ and e ₂ whose thickness has been reduced as shown in FIG. In this case, the laser beam L has a spot diameter φ smaller than the width h (for example, 30 μm) of the opening 9a of the resist 9 (for example, 30 μm), and is a laser beam L having a minute spot size. When the laser beam L is irradiated for a predetermined time, the metal plate is etched.
the laser beam irradiation position is dissolved in e _1, e _2, since it is removed, etching portions e _1, e ₂ into the through hole 11 of the metal plate 8 as shown in FIG. (e) is formed, the etching-processed portion Is disconnected. The cutting size at this time is extremely small because the spot size of the laser beam L is very small.

When irradiating the laser beam L, the laser beam L may be applied to the entire surface of the resist 9 as shown in FIG. 1A, or the inner lead may be applied as shown in FIG. 1B. The laser beam L can be partially applied only to the etched portions e ₁ and e ₂ that require fine processing, such as the tip 5. When the laser beam L is partially applied only to the micro-processed portion, the other processed portion is penetrated and cut only by etching. In order to perform such processing, it is necessary to use a resist
By setting the opening width of 9, 10 to be smaller than the opening width of the resist 9, 10 in the part other than the micromachined part,
The amount of etching processing is reduced in the finely processed portion, and is increased in portions other than the finely processed portion. As a result, the time required for fine processing by the laser beam L can be shortened, and the amount of metal dissolved in the laser beam processing is reduced by the amount of the etching processing, thereby reducing dross (dissolved and reattached matter) generated in the laser beam processing. it can.

Finally, as shown in FIG. 2 (f), the resists 9 and 10 on both sides of the metal plate 8 are peeled off and removed, whereby the lead frame 1 is manufactured.

According to such a method of manufacturing the lead frame 1, since only a predetermined amount of the thickness t ₀ of the metal plate, that is, the entire processing amount, is etched, the etching width e _h1 ,
e _h2 is not very large. Therefore, the etching allowance is not so large. Moreover, since the remaining amount of the entire processing amount of the metal plate 8 is processed by the laser beam L having a small spot diameter, ultra-fine processing can be performed. As a result, for example, the lead frame 1 having a lead of 300 pins or more and a lead pitch of 200 μm or less can be manufactured. In this manner, according to the present embodiment, it is possible to reliably cope with an increase in the number of pins and a narrow pitch of the lead frame, which are increasingly required in the future.

In the above-described embodiment, the laser beam processing step is performed before the resists 9 and 10 are removed.
The laser beam processing step may be performed after removing 10. That is, after the resist 9 and 10 are removed as shown in FIGS. 3A to 3D after the etching shown in FIG. 2C, the metal plate 8 is Process. In this case as well, when irradiating the laser beam L, the laser beam L can be applied to almost the entire surface of the metal plate 8, or only the etched portions e ₁ and e ₂ that require fine processing are applied.
The laser beam L can be partially irradiated. 4th
As shown in the drawing, in this laser beam processing, the laser beam L is directly irradiated on the metal plate 8 because it is not blocked by the resist 9. And, the laser beam L of the metal plate 8
The irradiated surface is melted and removed to a certain thickness, so that the half-etched portion penetrates and cuts first.

FIG. 5 is a view showing another embodiment of the present invention. In this embodiment, as in the embodiment shown in FIG. 2, a laser beam processing step is performed before the resists 9 and 10 are peeled off. In this case, the spot diameter φ of the laser beam L is set to be larger than the width h of the opening 9a of the resist 9 without being narrowed. Therefore, when the resist 9 is irradiated with the laser beam L, the resist 9 functions as a mask, and the laser beam L passes through the opening 9a of the resist 9.
Is irradiated on the metal plate 8. Then, a through hole 11 having the same size as the opening width h is formed. According to this embodiment, the laser beam processing can be performed without narrowing the spot diameter φ of the laser beam L, so that it is not necessary to control the positioning of the laser beam L so strictly, so that the manufacturing becomes easy.

Also, as shown in FIG. 1 (a), positioning marks 12 are formed on the metal plate of the lead frame 1. The positioning mark 12 is formed at the same time as the etching process is performed, and processing positioning of the laser beam L is performed using the positioning mark 12. By managing the processing position of the laser beam L in this way, the etching position and the laser beam processing position do not significantly shift. Therefore, matching between the etching process and the laser beam process is facilitated, and the processing accuracy is improved.

The present invention is not limited to the above-described embodiment, and various design changes are possible.

For example, in any of the above-described embodiments, the etching process is performed on both surfaces of the metal plate 8, but the present invention is such that the etching process is performed only on either the upper surface or the lower surface of the metal plate 8. Can also.

In each of the embodiments described above, only the method of manufacturing a QFP type lead frame is described. However, the present invention can be applied not only to the manufacture of other lead frames such as a DIP type, but also to a method other than the lead frame. It is needless to say that the present invention can also be applied to fine processing of a metal plate. In that case, in the case of fine processing of a relatively small metal plate, the positional deviation when making a resist plate is small, so the metal plate processing method of the present invention is particularly effective for the fine processing of such a relatively small metal plate. It is something.

[Effects of the Invention] As is apparent from the above description, according to the metal plate processing method of the present invention, the thickness is reduced by etching.
Since the thinned portion is processed by laser beam processing, the laser beam processing time can be significantly reduced. In addition, since the amount of metal dissolved by laser beam processing is reduced by the amount of the etching processing, dross (molten and reattached matter) generated by laser beam processing can be reduced.

Further, in the case of the conventional processing using only the etching, the fine processing is limited due to the relationship between the processed plate thickness and the processing allowance by the etching. However, according to the present invention, the processing allowance by the etching is not so much required. In addition, since the metal plate is cut by the laser beam, higher-level fine processing can be performed.

Furthermore, by performing the laser beam processing step before removing the resist in the etching processing, processing can be performed with a relatively large laser beam diameter, and the position accuracy of the laser beam does not need to be so strict, so processing is extremely simple. Not only can it be processed, but it can be processed in a short time. This improves productivity.

Furthermore, by applying the metal plate processing method of the present invention to the manufacture of a lead frame, it is possible to perform a higher level of fine processing. It can be manufactured easily and easily. Therefore, it is possible to surely cope with an increase in the number of pins and an ultra-narrow pitch of a lead frame that are increasingly required in the future.

Furthermore, when applied to a lead frame that can be manufactured only by etching as in the past, the etching is almost half-etched, and furthermore, processing of fine parts is not required, so that adjustment of the etching process is easier than in the past. .

[Brief description of the drawings]

1A and 1B show an example of a lead frame manufactured using an embodiment of a method for processing a metal plate according to the present invention, wherein FIG. 1A shows a case where a laser beam is applied to the entire surface, and FIG. FIG. 2 is a diagram illustrating a case where a laser beam is partially irradiated, FIG. 2 is a diagram illustrating an embodiment of a method for manufacturing a lead frame according to the present invention, FIG. 3 is a diagram illustrating another embodiment of the present invention, FIG. 4 is a view for explaining penetration of a metal plate by a laser beam, and FIG. 5 is a view for explaining still another embodiment of the present invention. 1 ... lead frame, 4 ... die pad, 5 ... inner lead, 6 ... outer lead, 8 ... metal plate, 9,
10 ...... resist, 11 ...... through hole, 12 ...... positioning mark, e _1, e ₂ ...... etched portion, L ...... laser beam, h ...... opening width

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B23K 26/00-26/18 H01L 23/50

Claims (11)

(57) [Claims] An etching step of etching a predetermined portion by a predetermined amount out of a total processing amount in a thickness direction of a metal plate, and irradiating a laser beam to at least a part of the etched portion to perform the etching. A method for processing a metal plate, comprising: a laser beam processing step of processing the remaining amount of processing. 2. The processing of a metal plate according to claim 1, wherein in the etching step, a resist having a predetermined pattern is made on one or both surfaces of the metal plate, and etching is performed using the resist. Method. 3. The method according to claim 2, wherein the laser beam processing step is performed before removing the resist. 4. The metal plate processing method according to claim 3, wherein a laser beam diameter in the laser beam processing step is set to be larger than a predetermined pattern opening width of the resist. 5. The method for processing a metal plate according to claim 2, wherein the laser beam processing step is performed after removing the resist. 6. The method for processing a metal plate according to claim 5, wherein in the laser beam processing step, a laser beam is applied to a predetermined region or an entire surface including at least an etched portion of the metal plate. 7. The metal plate processing method according to claim 3, wherein a laser beam diameter in the laser beam processing step is set smaller than a predetermined pattern opening width of the resist. 8. An etching process in which a predetermined amount of the total processing amount in the thickness direction is processed at the fine processing portion of the metal plate, and the total processing amount in the thickness direction is processed at a processing portion other than the fine processing portion of the metal plate. 8. The method for processing a metal sheet according to claim 1, wherein the remaining amount of the total processing amount of the fine processing portion is processed by a laser beam processing step. 9. In the etching step, a resist having a predetermined pattern is formed on a surface of the metal plate to be etched,
The etching process is performed by using the resist, and the predetermined pattern opening width of the resist at a processing portion other than the fine processing portion of the metal plate is set to be larger than the predetermined pattern opening width of the resist at the fine processing portion of the metal plate. The method for processing a metal plate according to claim 8, wherein: 10. The metal plate processing method according to claim 1, wherein a positioning mark is formed at the time of etching, and the positioning accuracy of the laser beam is controlled by the positioning mark. 11. The method for processing a metal plate according to claim 1, wherein the metal plate is a lead frame.