JP2013254864A - Lead frame, process of manufacturing the same, and mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame formed by punching, which is a high density pattern layout and has small deformation such as warpage.SOLUTION: A lead frame 1, arranged in a longer direction of a long metal body, includes a plurality of apertures 3 formed by punching, and a crosspiece 5 positioned between neighboring apertures 3. The surface of the crosspiece 5 is tilted in reference to a surface other than the metal body crosspiece 5 at each position between neighboring apertures 3 in a longer direction, and tilted directions are alternately reversed in the longer direction.

Description

  The present invention relates to a lead frame, a manufacturing method thereof, and a mold.

  A lead frame on which a semiconductor chip or the like is mounted is formed of a long metal body, and is formed of, for example, copper or a copper strip obtained by rolling a copper alloy containing copper as a main component. A plurality of openings are formed in the lead frame in the longitudinal direction of the metal body, and a crosspiece is positioned between adjacent openings. The opening includes one or a plurality of lead frame units for mounting the semiconductor chip. When a semiconductor device is manufactured using a lead frame, a semiconductor chip such as an LED is manufactured by mounting a semiconductor chip on each of the lead frame units, sealing with a resin, and separating the chips.

  The opening of the lead frame is manufactured, for example, by performing punching with a press. Patent Document 1 proposes a method of manufacturing a lead frame by forming an opening by a press using a progressive die, for example.

Specifically, a lead frame is manufactured as shown in FIGS. Here, as shown in FIGS. 5A to 5F, an example in which three lead frame units 104 are included in the opening 103 (openings 103a to 103e) will be described.
First, the long metal body 102 is transported by feeding a predetermined amount in the longitudinal direction (right direction in the figure) (FIG. 5A). The feeding amount of the metal body 102 is one pitch which is an amount corresponding to the interval between the adjacent openings 103 of the lead frame 100 to be formed. Next, by punching with the mold 120, three lead frame units 104 arranged in the width direction are formed in the metal body 102 as the first opening 103a (FIG. 5B). Next, a second opening 103b is formed so as to be adjacent to the first opening 103a by further punching the metal body 102 sent out by one pitch. At this time, a crosspiece 105 is formed between the adjacent openings 103a and 103b (FIG. 5C). Then, the operation of feeding the metal bodies 102 one pitch at a time and forming the openings 103c to 103e one row at a time is repeated (FIGS. 5D to 5F). In this way, a plurality of openings 103 arranged in the longitudinal direction are formed, and the lead frame 100 including the plurality of openings 103 and the crosspieces 105 positioned between the adjacent openings 103 is manufactured.

Japanese Patent Laid-Open No. 10-70229

  By the way, in the lead frame, as the number of openings formed in the metal body per unit increases, the number of lead frame units that can be collected increases, and the manufacturing cost of the lead frame can be reduced. In order to reduce the cost, in order to increase the number of lead frame units, the layout of openings in the lead frame (hereinafter referred to as pattern layout) is increased in density. Examples of increasing the density of the pattern layout include downsizing the opening including the lead frame unit and narrowing the pitch between the openings.

However, in the conventional lead frame manufacturing method, when the pattern layout is increased in density, there is a problem that the lead frame is deformed.
That is, when the interval between the openings 103 is narrowed to increase the density of the pattern layout, as shown in FIGS. 5A to 5F, the crosspieces 105 positioned between the adjacent openings 103 are arranged. There is a need to reduce the width. When punching is performed so that the width of the crosspiece 105 becomes narrow, the narrow crosspiece 105 is low in strength and easily deformed. Therefore, as shown in FIG. It is inclined (twisted) with respect to the main surface. Similarly, each of the crosspieces 105 formed each time the punching process is inclined with respect to the main surface of the lead frame 100 as shown in FIGS. 5 (d) to 5 (f). Moreover, each of the crosspieces 105 has the same inclination direction. Residual stress and distortion are generated in the lead frame 100 due to the inclination of the crosspiece 105, and residual stress and distortion accumulate in the leadframe 100 due to an increase in the crosspiece 105 inclined in the same direction. As a result, the lead frame 100 is deformed mainly by warping. In the deformed lead frame 100, processing such as mounting a semiconductor chip becomes difficult, and production efficiency is lowered.

  On the other hand, there is an etching process as a method for forming the opening of the lead frame. However, the etching process has a problem that the manufacturing cost is remarkably increased although deformation such as warpage can be suppressed as compared with the punching process.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a lead frame which is formed by punching and has a suppressed deformation such as warpage even in a high-density pattern layout, and a manufacturing method thereof. Is to provide.

  According to the first aspect of the present invention, the plurality of openings formed by punching and arranged in the longitudinal direction of the elongated metal body, and the crosspieces positioned between the adjacent openings, A surface of the crosspiece is inclined with respect to the surface of a portion other than the crosspiece of the metal body in each of the gaps between the openings adjacent in the longitudinal direction. A lead frame is provided in which the direction to be alternately reversed along the longitudinal direction.

  According to a second aspect of the present invention, there is provided the lead frame according to the first aspect, wherein the opening further includes a crosspiece that divides the opening in the longitudinal direction.

  According to the third aspect of the present invention, in the first aspect or the second aspect, a die pad on which a semiconductor chip is mounted and a lead electrically connected to the semiconductor chip are formed in the opening. Lead frames are provided.

  According to a fourth aspect of the present invention, there is provided the lead frame according to any one of the first to third aspects, wherein a width of the crosspiece is not less than 0.3 mm and not more than 3.0 mm.

  According to the fifth aspect of the present invention, the plurality of openings formed by punching and arranged in the longitudinal direction of the elongated metal body, and the crosspieces positioned between the adjacent openings, A lead frame manufacturing method comprising: a first punching step of forming a spaced opening by punching the elongated metal body by separating one opening in the longitudinal direction; and A plurality of openings and a second punching step for forming the plurality of openings and the crosspieces, and a surface of the crosspieces is formed between the openings adjacent to each other in the longitudinal direction. In each of the above, there is provided a method of manufacturing a lead frame that is inclined with respect to the surface of a portion other than the crosspiece of the metal body, and the direction of inclination is alternately opposite along the longitudinal direction.

According to a sixth aspect of the present invention, there is provided a die used in the method for manufacturing a lead frame according to the fifth aspect, the die for placing the elongated metal body, and the die placed on the die. There is provided a mold having a stripper plate for fixing the elongated metal body, and a protrusion provided on the die, the stripper plate, or both.

  According to the present invention, it is possible to obtain a lead frame which is formed by punching and in which deformation such as warpage is suppressed even with a high-density pattern layout.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the lead frame which concerns on one Embodiment of this invention, Comprising: (a) is a top view, (b) is a figure for demonstrating the relationship of a crosspiece in the AA cross section of (a). (C) is a partially enlarged view of (a). It is process drawing of the manufacturing method of the lead frame which concerns on one Embodiment of this invention. (A) is an example of the structure schematic diagram of the progressive die for punching, (b) is the elements on larger scale in the punching process part of (a). (A) is the cross-sectional photograph of the unextracted part of the lead frame of Example 1, (b) and (c) are the elements on larger scale of (a). (A)-(f) is process drawing of the manufacturing method of the conventional lead frame. (A) is the cross-sectional photograph of the lead frame of the comparative example 1, (b) is the elements on larger scale of (a). FIG. 6B is an enlarged view of FIG. 6B, where FIG. 6A is an enlarged view of a portion A, FIG. 6B is an enlarged view of a portion B, and FIG. 6C is an enlarged view of a portion C;

  As described above, conventionally, when a lead frame having a high-density pattern layout is manufactured by punching, there is a problem that deformation such as warpage occurs.

  This problem is because each of the crosspieces formed by punching is inclined in the same direction with respect to the main surface of the lead frame, and residual stress and distortion due to the inclination of the crosspieces are accumulated in the lead frame. Arise. Therefore, the present inventors diligently studied the above-described problems, and by reversing the slanting direction of the crosspieces alternately, the residual stress and distortion due to the slanting of the crosspieces are alleviated, and the lead frame The present inventors have found that the residual stress and strain accumulated can be reduced and have created the present invention.

  Hereinafter, a lead frame and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings. 1A and 1B are schematic views of a lead frame according to an embodiment of the present invention, in which FIG. 1A is a plan view, and FIG. 1B is a diagram illustrating a relationship between crosspieces in the AA cross section of FIG. (C) is the elements on larger scale of (a). 2A to 2F are process diagrams of a lead frame manufacturing method according to an embodiment of the present invention.

(Lead frame)
A lead frame 1 according to the present embodiment is arranged in the longitudinal direction of a long metal body 2 and includes a plurality of openings 3 formed by punching, and crosspieces 5 positioned between adjacent openings 3. The surface of the crosspiece portion 5 is inclined with respect to the surface of the portion other than the crosspiece portion 5 of the metal body 2 at each of the openings 3 adjacent in the longitudinal direction. The direction is alternately reversed along the direction.

The opening 3 is formed by punching a long metal body 2. One opening 3 is formed by one punching process. In the lead frame 1, as shown in FIG. 1A, a plurality of openings 3 are formed by a plurality of punching processes. The plurality of openings 3 are arranged in the longitudinal direction of the lead frame 1. A crosspiece 5 is located between adjacent openings 3, and the plurality of openings 3 are partitioned by the crosspiece 5.

  One opening 3 includes one or more lead frame units 4 on which, for example, a semiconductor chip is mounted. When the opening 3 includes a plurality of lead frame units 4, the opening 3 further includes a crosspiece 5 that partitions the opening 3. A plurality of lead frame units 4 are arranged in the opening 3 in the width direction of the metal body 2 or in a plurality of rows in the longitudinal direction of the metal body 2. In the present embodiment, as shown in FIG. 1A, the opening 3 is formed with lead frame units 4 (4a, 4b, 4c) arranged in one row in the longitudinal direction and three in the width direction. Shows the case. That is, in the lead frame 1 of the present embodiment, one row in which three lead frame units 4 are arranged in the width direction is formed in a plurality of rows in the longitudinal direction, and a plurality of lead frame units 4 are formed in a matrix. Has been.

  The crosspieces 5 are located between the lead frame units 4 arranged in a matrix, that is, between the adjacent lead frame units 4. The crosspiece 5 partitions a plurality of lead frame units 4 arranged in a matrix, and has a lattice shape as shown in FIG. The crosspiece 5 includes a first crosspiece 5a positioned between the lead frame units 4 adjacent in the longitudinal direction, a second crosspiece 5b positioned between the leadframe units 4 adjacent in the width direction, It is made up of. The first crosspiece 5a is an interval between the openings 3 to be formed, and the second crosspiece 5b indicates an interval between the adjacent lead frame units 4 in the opening 3. The width of the first crosspiece 5a and the second crosspiece 5b is determined by the pattern layout of the opening 3 and the lead frame unit 4 formed in the metal body 2. In the case of increasing the density of the pattern layout, it is preferably 0.3 mm or more and 3.0 mm or less. If the width of the crosspiece is less than 0.3 mm, it is difficult to suppress deformation of the lead frame, and if it exceeds 3.0 mm, it is difficult to increase the density of the pattern layout.

Of the crosspieces 5, the first crosspiece 5a is formed of a metal body by the punching pressure when forming the opening 3 including the lead frame units 4a, 4b, 4c, as shown in FIG. It inclines with respect to surfaces other than the 2nd 1st crosspiece part 5a. That is, the surface of the first crosspiece 5a is inclined with respect to the surface of the metal body 2 other than the first crosspiece 5a. The inclination direction is one side or the other side in the longitudinal direction with respect to the surface of the metal body 2 other than the first crosspiece 5a. Alternatively, the inclination direction is above or below the surface of the metal body 2 other than the first crosspiece 5a.
In each of the first crosspieces 5 a arranged via the lead frame unit 4, the inclination direction is alternately reversed along the longitudinal direction of the metal body 2. Specifically, as shown in FIG. 1B, the inclination direction of each first crosspiece 5a is along one side of the longitudinal direction (right direction in the drawing) along the longitudinal direction. The direction is alternately opposite to the other side (the left direction in the figure) and is staggered.
According to this configuration, the residual stress and distortion of the lead frame 1 due to the inclination of the first crosspiece 5a are locally relieved and weakened. For this reason, the accumulation of residual stress or the like is reduced in the entire lead frame 1, and deformation such as warpage is unlikely to occur.

  In other words, the first crosspiece 5a on both sides of each opening 3 (lead frame unit 4) is on the main surface of the lead frame 1 in the longitudinal section of the lead frame 1 (cross section AA in the drawing). On the other hand, it inclines to the one side or the other side of the longitudinal direction, and the inclining directions are opposite to each other. Alternatively, in the longitudinal section of the lead frame 1, each of the first crosspieces 5 a located between the openings 3 (lead frame units 4) adjacent in the longitudinal direction is on one side or the other side in the longitudinal direction. It is twisted, and the twisting direction is alternately reversed.

In addition, in the 2nd crosspiece part 5b located between the lead frame units 4 arranged in the width direction, since the lead frame units 4a, 4b, and 4c are formed at the same time, the first crosspiece part 5a In comparison, tilting and twisting are less likely to occur.

  Each of the lead frame units 4a, 4b, 4c has a predetermined wiring pattern 10 as shown in FIG. The predetermined wiring pattern 10 includes a die pad 11 on which a semiconductor chip is mounted, a suspension lead 12 that supports four corners of the die pad 11, and a lead 13 that is electrically connected to the semiconductor chip. The wiring pattern 10 is supported by the crosspiece 5 and is formed integrally with the lead frame 1. One of the lead frame units 4 is mounted on one semiconductor chip and is separated into one semiconductor device.

(Lead frame manufacturing method)
The manufacturing method of the lead frame 1 according to the present embodiment includes a crosspiece that is arranged in the longitudinal direction of the long metal body 2 and is located between a plurality of openings formed by punching and adjacent openings. A first method of forming the opening 3 to be separated by punching out the long metal body 2 while separating one of the openings 3 in the longitudinal direction. A punching step and a second punching step of punching between the spaced apart openings 3 to form a plurality of openings 3 and crosspieces 5.

  First, a metal body 2 as a material for the lead frame 1 is prepared. Although it does not specifically limit as the metal body 2, For example, the copper strip etc. which rolled copper or the copper alloy which has copper as a main component can be used. In copper strips or the like wound in a coil shape, winding gusset is generated, and therefore it is preferable to remove and correct the wound gusset by a leveler that is a correction device before conveying the material to the press machine. Moreover, as thickness of a metal body, it is preferable to set it as 100 micrometers or more and 200 micrometers or less, for example.

  Subsequently, the prepared metal body 2 is installed in a rotary material delivery device and delivered to a press machine. The fed metal body 2 is sent through a material standby device to a material conveying device installed in a press machine. Then, the metal body 2 is transported by the material transport device, and the metal body 2 is supplied to a punching progressive mold 20 (hereinafter also referred to as a mold 20) installed in the press machine (FIG. 2A). As shown in FIG. 2A, the metal body 2 is transported in the longitudinal direction (left-right direction in the figure), and the metal body 2 is supplied to the mold 20. In addition, when supplying the metal body 2 into the mold 20, the lubricity of the metal body 2 can be improved by supplying the processing oil to the metal body 2 by an automatic supply type processing oil supply device.

  Subsequently, a plurality of openings 3 arranged in the longitudinal direction of the metal body 2 are formed by performing press processing (punching) using the mold 20 a plurality of times on the metal body 2 to be conveyed. In the present embodiment, a first punching process and a second punching process are performed as the punching process. In addition, the opening 3 formed by one punching process is divided into three by the crosspiece 5, and is divided into three openings arranged in the width direction. Each of the three openings has a predetermined wiring pattern 10 and is composed of three lead frame units 4a, 4b, and 4c.

  In the first punching step, the long metal body 2 is punched by separating one of the openings 3 in the longitudinal direction, thereby forming the spaced openings 3. Specifically, when the amount corresponding to the interval between adjacent openings 3 of the lead frame 1 to be formed is 1 pitch, the long metal body 2 is transported by 2 pitches in the longitudinal direction and punched. Then, the punching process is intermittently performed to form the opening 3 that separates one pitch (one opening 3).

First, as shown in FIG. 2B, three lead frame units 4 a, 4 b, 4 c arranged in the width direction are formed by the mold 20 as the opening 3 a. Thereafter, as shown in FIG. 2 (c), the metal body 2 is fed out by two pitches to form one row of lead frame units 4 as openings 3b. Similarly, as shown in FIG. 2 (d), the metal body 2 is fed out by two pitches to form one row of lead frame units 4 as the openings 3c. That is, the punching process is performed so that each of the openings 3 a, 3 b, 3 c formed in the first punching process separates one row of the openings 3. As shown in FIG. 2D, the spaced apart openings 3a, 3b, 3c are arranged via a predetermined region. The predetermined region is a punching scheduled region T (region indicated by a broken line in the drawing) that is scheduled to be punched in a second punching step described later. Thus, in the first punching step, a plurality of lead frame units 4 are formed as the openings 3a, 3b, 3c arranged via the planned punching region T.

As described above, when the opening 3 is formed so that the width of the crosspiece 5 (the first crosspiece 5a) positioned between the openings 3 adjacent in the longitudinal direction is narrow, the crosspiece 5 is not stamped. The lead frame 1 is deformed by being inclined (twisted) by the pressure. In this regard, in the first punching step, the opening 3 is formed so as to be separated via the planned punching region T, so that the inclination of the planned punching region T is suppressed. The punched region T includes one row of the openings 3 and has a wide width and high strength. For this reason, in the scheduled punching region T, inclination (twist) due to pressure during punching is suppressed. That is, in the first punching step, the residual stress and distortion of the metal body 2 caused by the punching pressure can be suppressed by punching and forming the opening 3 through the planned punching region T.
Note that the second crosspiece 5b positioned between the lead frame units 4a, 4b, and 4c serving as the openings 3 adjacent in the width direction is formed simultaneously with the lead frame units 4a, 4b, and 4c. In comparison with the crosspiece 5a in the width direction, inclination and twist are less likely to occur.

  Subsequently, the metal body 2 in which the opening 3 is formed in the first punching process is sent out of the press machine and wound into a coil shape. The metal body 2 wound up in a coil shape is again installed in the rotary material feeding device, and the winding material is corrected by a leveler which is a correction device in the same manner as in the first punching process, and after passing through a material standby device, press Send it to the machine.

  Subsequently, the metal body 2 in which the opening 3 is formed in the first punching process is conveyed to perform the second punching process. In the second punching step, punching is performed between the openings 3 that are not punched intermittently in the first punching step and are separated via the planned punching region T. That is, the punching scheduled region T is punched to form the opening 3.

Specifically, the opening 3 is formed in a region that is not punched in the first punching process by transporting the metal body 2 while being shifted by one pitch from the first punching process. As shown in FIG. 2E, a punching process is performed on the planned punching region T located between the opening portions 3a and 3b that are separated from each other, and one row of lead frame units 4 is formed as the opening portions 3d. At this time, the crosspiece 5 is positioned between the adjacent openings 3a and 3d and between the openings 3d and 3b. The crosspieces 5 (first crosspiece 5a) formed on both sides of the opening 3d are inclined inwardly of the opening 3d by the punching pressure. That is, each of the first crosspieces 5a on both sides of the opening 3d is inclined to one or the other in the longitudinal direction of the metal body 2, and the inclined directions are opposite to each other. Similarly, as shown in FIG. 2 (f), when the second punching process is performed, each of the crosspieces 5a on both sides of the opening 3e to be formed is inclined, and the inclination directions are opposite to each other. Direction.
In this way, by performing the second punching process on the metal body 2 that has been subjected to the first punching process, the inclination of each of the first crosspieces 5a formed by the punching process is along the longitudinal direction. Can be alternately reversed. For this reason, the residual stress and distortion accompanying the inclination of the first crosspiece 5a are locally relaxed and weakened, and accumulation of residual stress and the like in the entire lead frame 1 can be suppressed.

  Subsequently, the manufactured lead frame 1 is conveyed to a cleaning device to remove processing oil and other contaminants. Then, the cleaned lead frame 1 is conveyed to a plating apparatus, plated with tin, silver, nickel or the like, and the obtained lead frame 1 is again wound into a coil shape.

  In the above-described embodiment, a case has been described in which openings including three lead frame units in the width direction and one row in the longitudinal direction are formed by one punching process, but the present invention is limited to this example. Not. For example, an opening including one or a plurality of lead frame units in the width direction can be formed by a single punching process. Moreover, it is also possible to form openings including lead frame units of 2 to 4 rows in the longitudinal direction.

  Moreover, in the said embodiment, although the case where the 1st punching process and the 2nd punching process were repeatedly performed with one press machine was demonstrated, the 1st punching is carried out by tandem-izing with two press machines. It is also possible to perform the process and the second punching process continuously. In this case, manufacturing efficiency can be improved by omitting operations such as winding of the metal body and re-installation of the metal body into the material feeding device.

  In the above embodiment, the case where the opening includes a lead frame unit in which a die pad or a lead is formed has been described. However, the opening is used for transporting the metal body, and the end side in the width direction of the metal body One or a plurality of sprocket holes may be formed.

(Press machine and progressive die for punching)
Next, an example of a press machine used for manufacturing the lead frame described above and a progressive die for punching installed in the press machine will be described. The press machine is provided with a progressive die for punching for punching a metal body and a material conveying device for supplying the metal body to the progressive die for punching. FIG. 3 shows the structure of the punching progressive die, (a) is a schematic configuration diagram of the punching progressive die, and (b) is a partially enlarged view of the punching portion of (a).

  As shown in FIG. 3A, the punching progressive die 20 includes a lower die 30, an upper die 40, and a guide post 50. The lower mold 30 includes a lower die set 31, a die plate 32 fixed to the lower die set 31, and a die 33 that is held at the center of the die plate 32 and places the metal body 2 thereon. The upper die 40 has an upper die set 41, a punch plate 43 that is fixed to the upper die set 41 and has a punch 42 for punching out the metal body 2, and a through hole 45 in which the punch 42 moves up and down, and a spring 44. And a stripper plate 46 which is connected to the punch plate 43 and fixes the metal body 2 placed on the die 33. The upper die 40 is supported by the lower die 30 by guide posts 50 and has a structure that can be raised and lowered.

  In the punching progressive die 20, as shown in FIGS. 3A and 3B, first, the stripper plate 46 installed on the upper die 40 is lowered, and the metal body on the die 33 of the lower die 30. 2 is sandwiched and fixed by the stripper plate 46 and the die 33. When the upper die 40 is further lowered, the punch 42 stored in the stripper plate 46 is lowered, and the metal body 2 is pushed into the hole side of the die 33 while being deformed. Then, a crack progresses from the edge of the punch 42 and the die 33 to the metal body 2, and the metal body 2 breaks when this crack is connected. Since the punch 42 continues to descend after that, the punched portion is pushed into the die 33 and discharged to the lower die 30.

As the above-described progressive die 20 for punching, it is preferable that the stripper plate 46 is provided with a protrusion 60 as shown in FIG. The metal body 2 is punched by the punch 42 after being fixed between the stripper plate 46 and the die 33. The metal body 2 is drawn toward the hole side of the die 33 by the pressure of the punch 42 at the time of punching. For this reason, the edge (crosspiece) of the opening 3 of the metal body 2 is deformed. In this respect, the protrusion 60 formed on the stripper plate 46 generates a frictional force in the direction opposite to the direction in which the metal body 2 is pulled into the hole side of the die 33, so that the metal body 2 is firmly fixed. Then, it becomes possible to suppress the pull-in. And the deformation | transformation of the crosspiece 5 of the lead frame 1 can be suppressed. 3B illustrates the case where the stripper plate 46 includes the protrusions 60, the protrusions 60 may be included in the die 33, the stripper plate 46, or both.

  The material of the protrusion 60 is not particularly limited as long as it increases the frictional resistance, and a material different from the mold part and having a high frictional resistance, such as rubber, can also be used. Moreover, the frictional resistance of the protrusion 60 may be increased by increasing the roughness of the contact surface of the protrusion 60 with the metal body. However, it is preferable to appropriately set the roughness of the protrusion 60 in consideration of causing scratches on the metal body.

(Effect of this embodiment)
According to the present embodiment, the following one or more effects are achieved.

  According to this embodiment, it has the 1st punching process which forms the opening part which spaces apart, and the 2nd punching process which punches between the opening parts which space apart. With this configuration, in the lead frame, the inclination of the crosspieces positioned between the openings adjacent in the longitudinal direction can be alternately reversed. For this reason, residual stress and distortion accompanying the inclination of the crosspiece can be relaxed, accumulation of residual stress and the like in the entire lead frame can be suppressed, and deformation such as warpage can be suppressed.

  In the said embodiment, it is preferable that the width | variety of a crosspiece is 1 mm or more and 5 mm or less. According to this configuration, the width of the crosspiece can be narrowed, and the pattern layout of the openings formed in the metal body can be densified.

  In addition, when forming the opening, by using a die, a stripper plate, or a mold having protrusions on both, the inclination of the crosspiece itself that occurs during the punching process is suppressed, and residual stress and distortion accumulated in the lead frame are suppressed. Can be further suppressed.

  The lead frame according to the present invention was manufactured by the following method and conditions. These embodiments are examples of the lead frame according to the present invention, and the present invention is not limited to these embodiments.

Example 1
As the metal body 2, a coil (hereinafter referred to as material) having a diameter of about 1 m around which a copper alloy strip rolled to a thickness of about 0.2 mm was wound was installed in a rotary material feeding device. Next, the material was sent out and corrected with a leveler, which is a correction device, so as to remove the winding gusset. The straightened material was sent to a press machine having a maximum output of about 150 t through a material standby device provided in front of the press machine. The press machine is equipped with a feeder that is a material conveying device unique to the press machine, and the material is sent to a mold installed in the press machine. At this time, the processing oil was supplied to the material by an automatic supply type processing oil supply device to improve the lubricity of the material. The material was conveyed to a punching section in the mold, and the mold was pressed by a press machine to punch the material.

In the first punching step, the feed amount of the material is set to 2 pitches, and one row of the opening portions 3 in the width direction is separated from each other, so that the opening portions 3 are formed every other row, about 300 rpm. The press was performed at a speed of and punched. The materials were sent out of the press in the order in which the punching was completed, and once wound up in a coil shape.

  After that, the material is again set in the rotary type material feeding device, and the second punch is not punched in the first punching step, and the second row is located in the region corresponding to one row located between the plurality of openings 3 between one row separation. The punching process was applied. In the 2nd punching process, it sent out in the state shifted 1 pitch from the 1st punching process, and the punching process was performed.

  In the first punching process and the second punching process, a plurality of openings 3 in which die pads and leads are formed are arranged in a matrix, and the width of the crosspieces 5 positioned between the adjacent openings 3 is 0. The lead frame 1 was manufactured to be 3 mm or more and 3.0 mm or less. The manufactured lead frame 1 was sent to a cleaning device to remove processing oil and other contaminants, and tin plating was applied to the entire surface of the lead frame with a plating device.

  When the cross section of the crosspiece 5 was observed for the lead frame 1 obtained in Example 1, it was confirmed that the cross section was as shown in FIG. The crosspieces 5 are inclined with respect to the main surface of the lead frame 1 between the openings 3 (lead frame units 4) adjacent in the longitudinal direction, and the inclined directions are alternately opposite to each other. It was.

  In addition, when the cross section of the part where the punching process of the lead frame was not performed (uncut part) was observed, it was confirmed that the cross section was as shown in FIGS. 4 (a) to 4 (c). FIG. 4 is a cross-sectional photograph of an unextracted portion of the lead frame, where (a) is an overall view, and (b) and (c) are partially enlarged views of (a).

  Further, the warpage deformation amount of the lead frame obtained in Example 1 was measured. As the amount of warp deformation, a lead frame cut to a length of about 300 mm was placed on a flat table, and the warp at the tip was measured with reference to the center of the lead frame. When the amount of warp deformation of the lead frame of the example was measured, the amount of warp deformation was about 10 mm or less, which was confirmed to be suitable for manufacturing a semiconductor device.

(Example 2)
In the second embodiment, the lead frame 1 is formed in the same manner as in the first embodiment except that punching is performed using a press machine in which the mold 20 having the protrusions 60 is installed for the purpose of strengthening the fixing force of the material. Manufactured. As the mold 20, a mold 20 in which a protrusion 60 (thickness: 10 μm, width: about 100 μm) is provided at the edge portion of the punched portion of the stripper plate 46 was used.

  When the cross section of the crosspiece 5 was observed for the lead frame 1 obtained in Example 2 in the same manner as in Example 1, it was confirmed that it was the same as the cross section of Example 1.

  Further, in the same manner as in Example 1, the amount of warp deformation of the lead frame 1 obtained in Example 2 was measured. When the amount of warp deformation of the lead frame 1 of Example 2 was measured, the amount of warp deformation was about 5 mm or less, which was confirmed to be suitable for manufacturing a semiconductor device.

(Comparative example)
In the comparative example, the lead frame 100 was manufactured by a conventional manufacturing method. The lead frame 100 was manufactured by punching the openings 103 so as to be adjacent to the formed openings 103 with the feed amount of the metal body 102 being one pitch, and forming the openings 103 one by one.

When the cross section of the crosspiece 105 of the obtained lead frame 100 of the comparative example was observed in the same manner as in the example, it was confirmed that the cross section was as shown in FIGS. 6A and 6B are cross-sectional photographs of the lead frame, where FIG. 6A is an overall view and FIG. 6B is a partially enlarged view of FIG. FIGS. 7A and 7B are enlarged views of FIG. 6B, where FIG. 7A is an enlarged view of the A portion, FIG. 7B is an enlarged view of the B portion, and FIG. 7C is an enlarged view of the C portion. .

  Further, when the amount of warpage deformation of the lead frame obtained in the comparative example was measured, the amount of warpage deformation was about 15 mm, and it was confirmed that the deformation mainly due to warpage was large and was not suitable for manufacturing a semiconductor device. It was.

(Reference example)
As a reference example of Example 1, as in the comparative example, the metal bodies are sent out one pitch at a time, and openings are formed one row at a time, and punching is performed by a press machine having the mold used in Example 2 as a mold. The lead frame was manufactured.
When the amount of warp deformation of the lead frame of the reference example was measured in the same manner as in Example 1, it was 10 mm or less.

DESCRIPTION OF SYMBOLS 1 Lead frame 2 Metal body 3 Opening part 4 Lead frame unit 5 Crosspiece

Claims (6)

A lead frame that is arranged in a longitudinal direction of a long metal body and includes a plurality of openings formed by punching, and a crosspiece positioned between adjacent openings,
The surface of the crosspiece is inclined with respect to the surface of the portion other than the crosspiece of the metal body in each of the openings adjacent in the longitudinal direction, and the inclined direction is the longitudinal direction. A lead frame characterized in that the directions are alternately opposite to each other.   The lead frame according to claim 1, wherein the opening further includes a crosspiece that divides the opening in the longitudinal direction.   The lead frame according to claim 1, wherein a die pad on which a semiconductor chip is mounted and a lead electrically connected to the semiconductor chip are formed in the opening.   The lead frame according to any one of claims 1 to 3, wherein the crosspiece has a width of not less than 0.3 mm and not more than 3.0 mm. A method of manufacturing a lead frame comprising a plurality of openings formed by punching and arranged in the longitudinal direction of a long metal body, and a crosspiece located between adjacent openings,
A first punching step of forming the opening to be separated by punching the elongated metal body by separating one opening in the longitudinal direction.
Punching between the spaced apart openings, and a second punching step for forming the plurality of openings and the crosspiece, and
The surface of the crosspiece is inclined with respect to the surface of the portion other than the crosspiece of the metal body in each of the openings adjacent in the longitudinal direction, and the inclined direction is the longitudinal direction. A method for manufacturing a lead frame, wherein the directions are alternately opposite to each other. A mold used in the method of manufacturing a lead frame according to claim 5,
A die for placing the elongated metal body;
A stripper plate for fixing the elongated metal body placed on the die,
A mold comprising a protrusion on the die, the stripper plate, or both.