JP2011146736A - Leadframe and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for manufacturing a leadframe, which is capable of forming dimples on the leadframe with a high density and of suppressing the occurrence of warping deformation of the leadframe due to the formation of dimples. <P>SOLUTION: After first dimples 16 arrayed at intervals of a fixed space Sp in a row direction and a column direction perpendicular to each other are formed on a die pad 12 of the leadframe 1, second dimples 16 arrayed at intervals of the same space Sp as that of the first dimples 16 in the row direction and the column direction are formed to have such a positional relationship that the second dimples 16 are shifted from the first dimples by a distance Sp/2 being half the space Sp, in the row direction and the column direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a manufacturing method and a manufacturing apparatus for a lead frame used in a resin-encapsulated semiconductor device.

A typical resin-sealed semiconductor device has a structure in which a semiconductor chip 91 is sealed together with a metal lead frame 92 with a resin package 93 as shown in FIG. The lead frame 92 includes a die pad (island) 94 that supports the semiconductor chip 91, and a plurality of leads 95 provided around the die pad 94. Each lead 95 penetrates the side surface of the package 93, and a portion sealed by the package 93 forms an inner lead portion connected to the electrode 96 formed on the surface of the semiconductor chip 91 by a bonding wire 97. The portion exposed from the package 93 forms an outer lead portion for connection to a substrate on which the semiconductor device is mounted.

In such a resin-encapsulated semiconductor device, if the adhesion between the lead frame 92 (die pad 94) and the package 93 is low, a crack (package crack) due to the difference in thermal expansion coefficient between them occurs in the package 93. . Therefore, the adhesiveness between the die pad 94 and the package 93 is improved by forming a large number of dimples (concave portions) in the die pad 94 and inserting the package 93 into these dimples (see, for example, Patent Document 1). ).

JP-A-7-161896

The formation of dimples is achieved by press working using a press die. That is, the press die has a pattern of protrusions arranged in a matrix at regular intervals. By hitting this press die against the die pad 94 and causing each protrusion to bite into the die pad 94, a large number of die pads 94 are provided. Dimples are formed together.
However, in press working using a press die, warpage occurs in the die pad 94 such that the surface on which the dimples are formed becomes convex. This warpage deformation is caused by the metal being pushed out to the periphery when the protrusion bites into the die pad 94, and becomes more noticeable as the density of dimples formed on the die pad 94 is higher. When the warp deformation amount of the die pad 94 is large, the accuracy of die bonding of the semiconductor chip 91 to the die pad 94 is adversely affected. Therefore, in the conventional method, the density of dimples in the die pad 94 must be suppressed, and at present, there is no lead frame in which the dimples are formed on the die pad 94 with an interval of 0.3 mm or less. To the extent that dimples are formed on the die pad 94 at intervals greater than 0.3 mm, the adhesion between the die pad 94 and the package 93 cannot be improved as expected.

Accordingly, an object of the present invention is to provide a lead frame manufacturing method and a manufacturing apparatus capable of forming dimples in a lead frame with high density and suppressing occurrence of warping deformation of the lead frame due to the dimple formation. Is to provide.

The invention according to claim 1 for achieving the above object is a method of manufacturing a lead frame formed by punching a thin metal plate, and the predetermined thin metal plate is formed by pressing using a first press die. In the region, the first dimple forming step for forming the first dimple arranged in a row direction and the column direction orthogonal to each other at a predetermined interval, and a pressing process using a second press die, Positions that are arranged in a predetermined region in the row direction and the column direction at regular intervals, and that are shifted from the first dimple by half the distance in the row direction and the column direction, respectively. And a second dimple forming step of forming a second dimple having a relationship.

According to this method, after the first dimples arranged in the row direction and the column direction orthogonal to each other at a predetermined interval are formed in a predetermined region of the thin metal plate, the same as the first dimples in the row direction and the column direction The second dimples aligned at intervals are formed at positions shifted from the first dimples in the row and column directions by a distance that is half the interval.
Even if warpage deformation occurs in the metal thin plate due to the formation of the first dimple, the warpage deformation is corrected by hitting the second press die against the metal thin plate when the second dimple is formed. . When the second dimple is formed, since the first dimple is already formed around the position where the second dimple is formed, the projection of the second press die bites into the metal thin plate. Sometimes the metal pushed out of that part escapes by being pushed into the first dimple. Therefore, the metal thin plate is hardly warped and deformed depending on the formation of the second dimple. Accordingly, dimples can be formed at a high density on a lead frame made of a thin metal plate, and the occurrence of warping deformation of the lead frame due to the formation of the dimples can be suppressed.

The first press die includes a protrusion disposed at a position facing a position where the first dimple is to be formed when facing the predetermined region, and the second press die You may provide the protrusion arrange | positioned in the position which opposes the position which should form the said 2nd dimple when it opposes a predetermined area | region. That is, the first press die has protrusions arranged in the row direction and the column direction at regular intervals, and the second press die has the row direction and the column direction. Are arranged at regular intervals and are opposed to the predetermined region, and are opposed to positions shifted by a half of the interval in the row direction and the column direction with respect to the first dimple, respectively. It may have a protrusion. In this case, in the second dimple formation step, the relative positional relationship between the predetermined region and the second press die is set as the relative position between the predetermined region and the first press die in the first dimple formation step. By using the same positional relationship as the above, the first dimple and the second dimple can be shifted in the row direction and the column direction by a distance that is half the distance.

Such a method can be performed by the lead frame manufacturing apparatus according to the third aspect. The lead frame manufacturing apparatus is a lead frame manufacturing apparatus formed by punching a thin metal plate, and has protrusions arranged in a row and a column direction orthogonal to each other at regular intervals, A first press die for forming a first dimple in the predetermined region by pressing the protrusion against the predetermined region of the metal thin plate, and the first press die are provided side by side, and the row direction and When arranged in the column direction at a constant interval and opposed to the predetermined region, the first dimple is displaced by half the interval in the row direction and the column direction with respect to the first dimple. A second press for forming a second dimple in the predetermined region by pressing the protrusion against the predetermined region of the thin metal plate. When, and a conveying means for conveying along the metal sheet in the direction of arrangement of said second press die and the first press die.

According to a second aspect of the present invention, the first dimple is arranged in the predetermined region at a certain interval in the row direction and the column direction by press working using a third press die. And a positional relationship shifted by a half distance of the interval in the row direction, and a positional relationship shifted by a half distance of the interval in the column direction with respect to the second dimple. A third dimple forming step for forming the dimple and a pressing process using the fourth press die, and arranged in the predetermined region at a certain interval in the row direction and the column direction, A positional relationship that is shifted by a half distance of the interval in the column direction with respect to the first dimple, and a positional relationship that is shifted by a distance of a half of the interval in the row direction with respect to the second dimple. Have the second Characterized in that it comprises further a fourth dimple formation step of forming a dimple, a method for fabricating a lead frame according to claim 1.

According to this method, after the first dimple and the second dimple are formed in the predetermined region of the thin metal plate, the third dimple aligned in the row direction and the column direction at the same interval as the first dimple is provided. The first dimple is formed at a position shifted by a half of the interval in the row direction and at a position shifted by a half of the interval in the column direction with respect to the second dimple. In addition, the fourth dimple aligned in the row direction and the column direction at the same interval as the first dimple is shifted from the first dimple by a half distance in the column direction with respect to the second dimple. It is formed at a position shifted in the row direction by a distance that is half the distance.

When the third dimple is formed, the first dimple and the second dimple are already formed around the position where the third dimple is formed. When the metal bites into the metal, the metal pushed out of the portion escapes by being pushed into the first dimple and the second dimple. Therefore, warp deformation hardly occurs in the metal thin plate depending on the formation of the third dimple. Similarly, even when the fourth dimple is formed, the metal thin plate is hardly warped and deformed. Therefore, while dimples can be formed at a higher density on the lead frame made of a thin metal plate, it is possible to suppress the warping deformation of the lead frame due to the formation of the dimples.

The third press die includes a protrusion disposed at a position facing the position where the third dimple is to be formed when facing the predetermined region, and the fourth press die is You may provide the protrusion arrange | positioned in the position which opposes the position which should form the said 4th dimple when it opposes the said predetermined area | region. That is, the third press die is arranged in the row direction and the column direction so as to be aligned at a certain interval, and is opposed to the predetermined region in the row direction with respect to the first dimple. A protrusion may be provided that is shifted by a distance that is half the interval and that is opposed to a position that is shifted by a distance that is half the interval in the row direction with respect to the second dimple. Further, the fourth press die is arranged in the row direction and the column direction so as to be aligned at a constant interval, and is opposed to the predetermined region in the column direction with respect to the first dimple. A protrusion may be provided that is shifted by a distance that is half the distance and that is opposed to a position that is shifted by a distance that is half the distance in the row direction with respect to the second dimple. In this case, the relative positional relationship between the predetermined region and the third press die in the third dimple forming step, and the relative position between the predetermined region and the fourth press die in the fourth dimple forming step. By making the relative positional relationship the same as the relative positional relationship between the predetermined region and the first press die in the first dimple formation step, the third dimple and the fourth dimple are The first dimples can be formed at positions shifted by a half the distance in the row direction and the column direction, respectively.

Such a method can be performed by the lead frame manufacturing apparatus according to the fourth aspect. In addition to the configuration of the manufacturing apparatus according to claim 3, the lead frame manufacturing apparatus is provided side by side in the alignment direction with respect to the first press die, and is constant in the row direction and the column direction. When arranged in alignment with each other and facing the predetermined region, the first dimple is displaced by half the distance in the row direction with respect to the first dimple, and the column direction with respect to the second dimple. And a projection facing the position shifted by a half of the distance, and pressing the projection against the predetermined area of the thin metal plate to form a third dimple in the predetermined area. 3 press dies and the first press dies arranged side by side in the arrangement direction, arranged in the row direction and the column direction at regular intervals, and facing the predetermined region , There is a protrusion that is offset from the first dimple by half the distance in the column direction and opposed to the second dimple by a half distance in the row direction from the second dimple. And a fourth press die for forming a fourth dimple in the predetermined area by pressing the protrusion against the predetermined area of the thin metal plate.

The first press die, the second press die, the third press die, and the fourth press die are arranged in the row direction and the column direction at regular intervals. A single press die having protrusions may be used. In this case, in the second dimple formation step, the relative positional relationship between the predetermined region and the press die is set such that the position where the protrusion of the press die is opposed to the predetermined region is the first dimple formation step. In the dimple formation step, the position of the press die is determined so as to be shifted from the position where the protrusion of the press die is opposed to the predetermined region by a half the distance in the row direction and the column direction. Further, in the third dimple formation step, the relative positional relationship between the predetermined region and the press die is such that the position of the projection of the press die facing the predetermined region is the first dimple formation step. Then, it is determined so as to be a position shifted by a half of the interval in the row direction from the position where the projection of the press die faces the predetermined region. Furthermore, in the fourth dimple formation step, the relative positional relationship between the predetermined region and the press die is such that the position where the projection of the press die faces the predetermined region is the first dimple formation step. Then, it is determined so as to be a position shifted by a half the distance in the row direction from the position where the projection of the press die faces the predetermined region. In this way, the second dimple can be formed at a position shifted from the first dimple by a half distance of the interval in the row direction and the column direction, respectively. The dimples and the fourth dimples can be formed at positions shifted from the first dimple by half the distance in the row direction and the column direction, respectively.

Such a method can be performed by the lead frame manufacturing apparatus according to the fifth aspect. This lead frame manufacturing apparatus is a lead frame manufacturing apparatus formed by punching a thin metal plate, and has a press die having protrusions arranged at regular intervals in a row direction and a column direction orthogonal to each other. A press mold moving mechanism for moving the press mold to press the protrusion against the metal thin plate, and a relative movement of the metal thin plate and the press mold relative to each other in the row direction and the column direction. A first dimple arranged in a predetermined region of the metal thin plate at a predetermined interval in the row direction and the column direction by controlling the moving means, the press mold moving mechanism, and the relative moving means; , Arranged in the row direction and the column direction at regular intervals, and half the interval in the row direction and the column direction with respect to the first dimple. Second dimples having a positional relationship that is shifted by a distance of the first dimple, arranged in a row at a constant interval in the row direction and the column direction, and half the interval in the row direction with respect to the first dimple. A third dimple having a positional relationship that is shifted by a distance and having a positional relationship that is shifted by a half of the distance in the column direction with respect to the second dimple; and the row direction and the column direction The first dimples are arranged in alignment and have a positional relationship that is shifted in the column direction by a half distance of the interval, and the second dimples in the row direction. Control means for forming a fourth dimple having a positional relationship shifted by a half of the distance.

It is a top view of the lead frame manufactured by the manufacturing method concerning one embodiment of this invention. It is a top view which expands and shows the back surface (surface on the opposite side to the surface where a semiconductor chip is mounted) of a die pad. It is a figure which shows the structure of the apparatus for manufacturing a lead frame schematically. It is a figure which shows the process of forming a dimple. It is a top view which shows a mode that dimples are formed. It is sectional drawing for demonstrating the positional relationship of a 1st dimple and the protrusion of a 2nd upper side press die. It is process drawing for demonstrating other embodiment of this invention. It is process drawing for demonstrating other embodiment of this invention. It is sectional drawing which shows typically the structure of a resin sealing type semiconductor device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view of a lead frame manufactured by a manufacturing method according to an embodiment of the present invention.
The lead frame 1 is formed by punching a long strip-shaped metal thin plate (for example, a copper thin plate), and a plurality of unit portions lead between a pair of rails 11 forming both ends extending in the longitudinal direction of the metal thin plate. The frame 1 is configured to be continuous in the longitudinal direction.

Each unit portion includes one die pad 12 and a plurality of leads 13 arranged around the die pad 12.
The die pad 12 is formed in a substantially rectangular shape in plan view. The die pad 12 is supported between the rails 11 by suspension leads 14 that connect the rails 11 and the sides facing the rails 11.

For example, four leads 13 are provided on both sides of the die pad 12 in the longitudinal direction of the lead frame 1. The four leads 13 on each side are arranged at equal intervals in a direction orthogonal to the longitudinal direction of the lead frame 1, and extend linearly along the longitudinal direction of the lead frame 1. Further, the four leads 13 are supported between the pair of rails 11 by tie bars 15 that connect intermediate portions in the longitudinal direction.

The lead frame 1 is used for a resin-encapsulated semiconductor device. In the manufacturing process of the resin-encapsulated semiconductor device, first, a semiconductor chip is mounted on the die pad 12 (die bonding). Subsequently, the electrode formed on the surface of the semiconductor chip and the end of each lead 13 on the die pad 12 side are connected by a bonding wire such as a gold thin wire. Thereafter, a resin package is formed, and the semiconductor chip and the bonding wire are sealed by the package. The package is formed so that the die pad 12 is housed inside together with the semiconductor chip and the bonding wire, the lead 13 and the suspension lead 14 penetrate the side surface, and the tie bar 15 is exposed to the outside. Then, the semiconductor device separated from the pair of rails 11 is obtained by cutting away the suspension leads 14 and tie bars 15 exposed to the outside of the package.

FIG. 2 is an enlarged plan view showing the back surface of the die pad 12 (the surface opposite to the surface on which the semiconductor chip is mounted).
A large number of dimples 16 are formed on the back surface of the die pad 12. The dimples 16 are provided at regular intervals (intervals between the deepest portions of the dimples 16) Sd in the row direction and the column direction orthogonal to each other, and are arranged in a matrix as a whole. As will be described later, the distance Sd between the dimples 16 is much smaller than the distance (about 0.3 mm) between the dimples in the conventional lead frame and is 0.3 mm or less. The density of the dimples 16 is the same as that in the conventional lead frame. It is much higher than the density of dimples. Each dimple 16 has a substantially quadrangular pyramid shape, and the depth from the back surface of the die pad 12 to the deepest portion is about 0.02 to 0.03 mm.

Thus, the dimples 16 are formed on the back surface of the die pad 12 of the lead frame 1 with high density. Therefore, by using this lead frame 1 for a resin-encapsulated semiconductor device, good adhesion between the die pad 12 and the package can be exhibited, and the metal that is the material of the die pad 12 and the resin that is the material of the package. The generation of package cracks due to the difference in thermal expansion coefficient with respect to can be prevented.

FIG. 3 is a diagram schematically showing a configuration of an apparatus for manufacturing the lead frame 1.
The lead frame manufacturing apparatus 2 includes, for example, a plurality of sets of feed rollers 22 for feeding a thin metal plate serving as a base material of the lead frame 1 from the supply reel 21A to the take-up reel 21B, and these feed rollers 22 A roller driving mechanism 23 for driving, a punching machine (not shown) for punching a thin metal plate to form the rail 11, die pad 12, lead 13, suspension lead 14, and tie bar 15; And a press working machine 24 for forming the dimples 16.

The thin metal plate is wound around the supply reel 21A, is fed by the feed roller 22, and is wound around the take-up reel 21B. In the middle of this, the thin metal plate sequentially passes through the punching machine and the press machine 24 and is subjected to punching by the punching machine and press processing by the press machine 24. Thereby, the lead frame 1 having the above-described configuration is obtained.

The press machine 24 is disposed above the lower block 25 facing the front surface (surface on which the semiconductor chip is mounted) of the lead frame 1 (metal thin plate), and is opposed to the back surface of the lead frame 1. An upper block 26 and a press elevating mechanism 27 for elevating the upper block 26 relative to the lower block 25 are provided.
In the lower block 25, four lower press dies 28A, 28B, 28C, 28D have the same pitch as the die pad 12 in the lead frame 1 in the lead frame 1 feed direction (hereinafter simply referred to as “feed direction”). Are arranged side by side. Each of the lower press dies 28A, 28B, 28C, 28D has a flat surface in contact with the lead frame 1 passing between the lower block 25 and the upper block 26.

In the upper block 26, four upper press dies 29A, 29B, 29C, and 29D are provided at positions that vertically oppose the lower press dies 28A, 28B, 28C, and 28D, respectively. A large number of substantially quadrangular pyramidal projections 30 are formed on the surface of each upper press die 29A, 29B, 29C, 29D facing the lead frame 1. The protrusions 30 are provided at a constant interval (interval between the apexes of the protrusions 30) Sp in the row direction along the feed direction and the column direction perpendicular thereto, and are arranged in a matrix as a whole. In this embodiment, the interval Sp of the protrusions 30 is set to 0.12 mm, which is the minimum interval that can be realized with the current processing technology.

Further, the lead frame manufacturing apparatus 2 includes a control device 31 for controlling the operation of each part including the roller driving mechanism 23 and the press elevating mechanism 27.
FIG. 4 is a diagram illustrating a process of forming the dimple 16. FIG. 5 is a plan view schematically showing how the dimples 16 are formed.
Hereinafter, with reference mainly to FIGS. 4 and 5, focusing on one of the plurality of die pads 12 provided in the lead frame 1, a process of forming the dimples 16 on the die pad 12 will be described.

Under the control of the control device 31, the feed roller 22 is driven by the roller drive mechanism 23, and the die pad 12 faces the upper press die 29A as the first press die located on the most upstream side in the feed direction (step) S1), the drive of the feed roller 22 is stopped.
Subsequently, the upper block 26 is lowered by the press elevating mechanism 27, the upper press die 29A is struck onto the die pad 12 (press), and the protrusion 30 of the upper press die 29A bites into the back surface of the die pad 12, A dimple 16 corresponding to the protrusion 30 is formed (step S2). Since the protrusions 30 are formed at a constant interval Sp in the row direction and the column direction, the back surface of the die pad 12 has a constant interval in the row direction and the column direction as indicated by a circle in FIG. The dimples 16 aligned with Sp are formed.

In the following, the upper press die 29A is referred to as “first upper press die 29A”, and the dimple 16 formed by the protrusion 30 of the first upper press die 29A is referred to as “first dimple 16”. That's it.
Thereafter, the feed roller 22 is driven and the lead frame 1 is fed. When the die pad 12 faces the upper press die 29B as the second press die (step S3), the drive of the feed roller 22 is stopped.

Subsequently, the upper block 26 is lowered by the press elevating mechanism 27, the upper press die 29B is struck onto the die pad 12 (press), and the protrusion 30 of the upper press die 29B bites into the back surface of the die pad 12, thereby As indicated by Δ in 5 (b), the dimples 16 corresponding to the protrusions 30 are formed at regular intervals Sp in the row and column directions (step S4).

Hereinafter, the upper press die 29B is referred to as a “second upper press die 29B”, and the dimple 16 formed by the protrusion 30 of the second upper press die 29B is referred to as a “second dimple 16”. That's it.
As shown in FIG. 6, the protrusion 30 of the second upper press die 29B is shifted from the first dimple 16 by a distance Sp / 2 that is half the interval Sp of the protrusion 30 in the row direction and the column direction. It is arranged so as to face the position. Therefore, the second dimple 16 has a positional relationship shifted from the first dimple 16 indicated by a circle in FIG. 5B by a distance Sp / 2 in the row direction and the column direction.

Thereafter, the feed roller 22 is driven, and the lead frame 1 is further fed. Then, when the die pad 12 faces the upper press die 29C as the third press die (step S5), the drive of the feed roller 22 is stopped.
Subsequently, the upper block 26 is lowered by the press elevating mechanism 27, the upper press die 29C is struck onto the die pad 12 (press), and the protrusion 30 of the upper press die 29C bites into the back surface of the die pad 12. As indicated by a cross in 5 (c), the dimples 16 corresponding to the protrusions 30 are formed at regular intervals Sp in the row and column directions (step S6).

In the following, the upper press die 29C is referred to as “third upper press die 29C”, and the dimple 16 formed by the protrusion 30 of the third upper press die 29C is “third dimple 16”. That's it.
The projections 30 of the third upper press die 29C are shifted in the row direction by a distance Sp / 2 that is half the spacing Sp of the projections 30 with respect to the first dimple 16, and in the column direction with respect to the second dimple 16. It is arranged so as to face a position shifted by a distance Sp / 2 that is half the interval Sp. For this reason, the third dimple 16 has a positional relationship shifted by a distance Sp / 2 in the row direction with respect to the first dimple 16 indicated by a circle in FIG. 5C, and FIG. The second dimple 16 indicated by the Δ mark has a positional relationship shifted by a distance Sp / 2 in the column direction.

Thereafter, the feed roller 22 is driven, and the lead frame 1 is further fed. When the die pad 12 faces the upper press die 29C as the fourth press die located on the most downstream side in the feed direction (step S7), the drive of the feed roller 22 is stopped.
Subsequently, the upper block 26 is lowered by the press elevating mechanism 27, the upper press die 29D is struck onto the die pad 12 (press), and the protrusion 30 of the upper press die 29D bites into the back surface of the die pad 12, thereby As indicated by □ in FIG. 5C, the dimples 16 corresponding to the protrusions 30 are formed at regular intervals Sp in the row and column directions (step S8).

Hereinafter, the upper press die 29D is referred to as a “fourth upper press die 29D”, and the dimple 16 formed by the protrusion 30 of the fourth upper press die 29D is referred to as a “fourth dimple 16”. That's it.
The protrusions 30 of the fourth upper press die 29D are shifted from the first dimples 16 in the column direction by a distance Sp / 2 that is half the spacing Sp of the protrusions 30, and in the row direction with respect to the second dimples 16. It is arranged so as to face a position shifted by a distance Sp / 2 that is half the interval Sp. Therefore, the fourth dimple 16 has a positional relationship that is shifted by a distance Sp / 2 in the column direction with respect to the first dimple 16 indicated by a circle in FIG. 5D. FIG. The second dimple 16 indicated by the Δ mark has a positional relationship shifted by a distance Sp / 2 in the row direction. As a result, the dimples 16 are formed in the die pad 12 so as to be aligned in the row direction and the column direction with a spacing Sd = Sp / 2 = 0.06 mm which is half the spacing Sp of the protrusions 30.

As described above, after the first dimples 16 are formed on the die pad 12 of the lead frame 1 so as to be aligned in the row direction and the column direction orthogonal to each other at a constant interval Sp, the first dimples are formed in the row direction and the column direction. The second dimples 16 aligned at the same interval Sp as 16 are formed at positions shifted from the first dimple 16 by a distance Sp / 2 that is half the interval Sp in the row direction and the column direction. Thereafter, the third dimples 16 aligned in the row direction and the column direction at the same interval Sp as the first dimples 16 are shifted from the first dimple 16 by a distance Sp / 2 that is half the interval Sp in the row direction. The second dimple 16 is formed at a position shifted in the column direction by a distance Sp / 2 that is half of the interval Sp. Further, the fourth dimple 16 aligned at the same interval Sp as the first dimple 16 in the row direction and the column direction is shifted from the first dimple 16 by a distance Sp / 2 that is half the interval Sp in the column direction. The second dimple 16 is formed at a position shifted in the row direction by a distance Sp / 2 that is half of the interval Sp.

Even if warpage deformation occurs in the die pad 12 due to the formation of the first dimple 16, the warpage deformation causes the second upper press die 29B to be struck against the die pad 12 when the second dimple 16 is formed. It is corrected by this. When the second dimple 16 is formed, the first dimple 16 is already formed around the position where the second dimple 16 is formed, so that the protrusion of the second upper press die 29B is formed. When 30 bites into the die pad 12, the metal pushed out from that portion escapes by being pushed into the first dimple 16. Therefore, the die pad 12 is hardly warped and deformed depending on the formation of the second dimple 16. When the third dimple 16 is formed, the first dimple 16 and the second dimple 16 are already formed around the position where the third dimple 16 is formed. When the protrusion 30 of the press die 29C bites into the die pad 12, the metal pushed out from the portion escapes by being pushed into the first dimple 16 and the second dimple 16. Therefore, the die pad 12 is hardly warped and deformed depending on the formation of the third dimple 16. Further, even when the fourth dimple is formed, the warp deformation hardly occurs in the die pad 12 as in the case of the third dimple. Accordingly, the dimples 16 can be formed on the die pad 12 with high density, and the occurrence of warp deformation of the die pad 12 (lead frame 1) due to the formation of the dimples can be suppressed.

Four lower press dies 28A, 28B, 28C, 28D are arranged at the same pitch as the die pad 12 in the lead frame 1 in the feed direction, and four upper press dies 29A, 29B, 29C, 29D are respectively provided. Since the lower press dies 28A, 28B, 28C, and 28D are provided at positions that face vertically, the die pad 12 can be simultaneously opposed to the lower press dies 28A, 28B, 28C, and 28D. Therefore, the first to fourth dimples 16 can be simultaneously formed on the die pad 12 facing each of the lower press dies 28A, 28B, 28C, and 28D by one raising / lowering (stroke) of the upper block 26, respectively. it can. Therefore, the unit portion of the lead frame 1 including the die pad 12 on which the dimples 16 are formed can be obtained at the same speed as the stroke speed (the number of strokes per minute) of the upper block 26 in the press machine 24. For example, if the stroke speed of the upper block 26 in the press machine 24 is 100 to 600 strokes per minute, 100 to 600 unit parts can be obtained in one minute.

FIG. 7 is a process diagram for explaining another embodiment of the present invention.
In the above-described embodiment, as the press working machine 24 for forming the dimples 16 on the die pad 12, four lower press dies 28A, 28B, 28C, 28D can be arranged in the lower block 25, and the upper block 26 In this example, four upper press dies 29A, 29B, 29C, and 29D can be arranged. On the other hand, even if the press machine 24 has a configuration in which only one lower press die and one upper press die can be arranged in the lower block 25 and the upper block 26, respectively, the above-described configuration The lead frame 1 can be manufactured.

First, the lower press die 28A and the upper press die 29A are attached to the lower block 25 and the upper block 26 of the press machine 24, respectively. Then, the lead frame 1 (metal thin plate) is conveyed from the supply reel 21A to the take-up reel 21B, and on the way, the die pad 12 is sequentially pressed by the lower press die 28A and the upper press die 29A, and all the die pads are pressed. First dimples 16 are formed on the substrate 12 (step T1).

Next, the lead frame 1 on which the first dimple 16 is formed is set on the supply reel 21A. Further, the lower press die 28A and the upper press die 29A are respectively removed from the lower block 25 and the upper block 26 of the press machine 24, and the lower press die 28B and the upper block 26A are respectively attached to the lower block 25 and the upper block 26. A press die 29B is attached. Then, the lead frame 1 is conveyed from the supply reel 21A to the take-up reel 21B, and the die pad 12 on which the first dimples 16 are formed is pressed by the lower press die 28B and the upper press die 29B in order. Then, the second dimples 16 are formed on all the die pads 12 (step T2).

Thereafter, the lead frame 1 on which the first and second dimples 16 are formed is set on the supply reel 21A. Further, the lower press die 28B and the upper press die 29B are removed from the lower block 25 and the upper block 26 of the press machine 24, respectively, and the lower press die 28C and the upper press die are respectively attached to the lower block 25 and the upper block 26. A press die 29C is attached. Then, the lead frame 1 is conveyed from the supply reel 21A to the take-up reel 21B, and on the way, the die pad 12 on which the first and second dimples 16 are formed is sequentially connected to the lower press die 28C and the upper press die. Press at 29C to form the third dimples 16 on all the die pads 12 (step T3).

Subsequently, the lead frame 1 on which the first to third dimples 16 are formed is set on the supply reel 21A. Further, the lower press die 28C and the upper press die 29C are respectively removed from the lower block 25 and the upper block 26 of the press machine 24, and the lower press die 28D and the upper block 26C are respectively attached to the lower block 25 and the upper block 26. A press die 29D is attached. Then, the lead frame 1 is transported from the supply reel 21A to the take-up reel 21B, and the die pad 12 on which the first to third dimples 16 are formed in the middle of the lower press die 28D and the upper press die. The fourth dimple 16 is formed on all the die pads 12 by pressing at 29D (step T4). As a result, the dimples 16 are formed on all the die pads 12 so as to be aligned in the row direction and the column direction at intervals Sd = Sp / 2 = 0.06 mm, which is half the interval Sp of the protrusions 30.

FIG. 8 is a process diagram for explaining still another embodiment of the present invention.
In the above-described embodiment, the dimple 16 is formed on the die pad 12 by using the four lower press dies 28A, 28B, 28C, and 28D and the upper press dies 29A, 29B, 29C, and 29D corresponding to the lower press dies 28A, 28B, 28C, and 28D, respectively. I took up the case. On the other hand, for example, one lower press die 28A and an upper press die 29A corresponding thereto are arranged on the lower block 25 and the upper block 26 of the press machine 24, respectively, so that the lower press die 28A is disposed. The above-described configuration is also achieved by adding a relative movement mechanism (not shown) for relatively moving the upper press die 29A and the lead frame 1 (metal thin plate) in the row direction orthogonal to the feed direction. The lead frame 1 can be manufactured.

In this configuration, the lead frame 1 is transported from the supply reel 21A to the take-up reel 21B, and the die pad 12 of the lead frame 1 faces the lower press die 28A and the upper press die 29A in the middle (step E1). The transport of the lead frame 1 is interrupted. Then, the die pad 12 is pressed by the lower press die 28A and the upper press die 29A, and the dimple 16 indicated by a circle in FIG. 5D is formed on the die pad 12 (step E2).

Subsequently, the lower press die 28A and the upper press die 29A or the lead frame 1 are shifted to one side in the column direction by a distance Sp / 2 = 0.06 mm which is a half of the interval Sp of the protrusions 30 (step E3). . Then, the die pad 12 is pressed by the lower press die 28A and the upper press die 29A. As a result, the dimples 16 indicated by □ in FIG. 5D are formed on the die pad 12 (step E4).

Thereafter, the lead frame 1 is fed in the feeding direction by a distance Sp / 2 = 0.06 mm which is a half of the interval Sp between the protrusions 30 (step E5). Then, the die pad 12 is pressed by the lower press die 28A and the upper press die 29A. As a result, the dimples 16 indicated by Δ in FIG. 5D are formed on the die pad 12 (step E6).
Subsequently, the lower press die 28A and the upper press die 29A or the lead frame 1 are shifted to the other side in the column direction by a distance Sp / 2 = 0.06 mm which is a half of the interval Sp between the protrusions 30 (step E7). . Then, the die pad 12 is pressed by the lower press die 28A and the upper press die 29A. As a result, the dimples 16 indicated by x in FIG. 5D are formed on the die pad 12 (step E8). As a result, the dimples 16 are formed on all the die pads 12 so as to be aligned in the row direction and the column direction at intervals Sd = Sp / 2 = 0.06 mm, which is half the interval Sp of the protrusions 30.

As mentioned above, although several embodiment of this invention was described, this invention can also be implemented with another form. For example, the protrusions 30 of the upper press dies 29A, 29B, 29C, and 29D are provided at regular intervals Sp in the row direction along the feed direction and in the column direction perpendicular to the feed direction. The direction does not have to be along the feed direction, and may be a direction crossing the feed direction.

In each of the above-described embodiments, the dimple 16 is formed on the die pad 12 of the lead frame 1. However, the dimple 16 may be formed not only on the die pad 12 but also on the lead 13.
Further, the steps S5 to S8 shown in FIG. 4 may be omitted, and the lead frame 1 in which the dimples 16 indicated by ◯ and Δ in FIG. 5B are formed may be manufactured. The lead frame 1 in which the dimples 16 indicated by ◯ and Δ in FIG. 5B are formed can also be formed by omitting the steps T3 and T4 shown in FIG. 7, and the steps shown in FIG. It can also be formed by omitting E4, E7, and E8.

Further, when facing the die pad 12, a position shifted by a distance Sp / 4 that is ¼ of the interval Sp of the protrusions 30 in the row direction and the column direction with respect to the dimples 16 indicated by ◯ in FIG. A press die having opposing protrusions is further used, and is shifted by a distance Sp / 4 that is ¼ of the spacing Sp of the protrusions 30 in the row direction and the column direction with respect to the dimples 16 indicated by ◯ in FIG. A dimple 16 may be additionally formed at the position.

Furthermore, when the protrusion 30 bites into the die pad 12, a part of the metal pushed out from the portion rises on the peripheral edge of each dimple 16, so that after the dimple 16 is formed, the back surface of the die pad 12 is pressed with a plane. The protruding metal may protrude toward the inside of each dimple 16, so that a flange that protrudes inward may be formed on the periphery of each dimple 16. By forming the flange portion, the adhesion between the resin entering each dimple 16 and the die pad 12 can be further enhanced.

In addition, various design changes can be made within the scope of matters described in the claims.

DESCRIPTION OF SYMBOLS 1 Lead frame 2 Lead frame manufacturing apparatus 12 Die pad (predetermined area)
13 Lead 16 Dimple 22 Feed roller (conveying means, relative moving means)
23 Roller drive mechanism (conveying means, relative moving means)
27 Press lifting mechanism (press type moving mechanism)
29A, 29B, 29C, 29D Upper press mold 30 Protrusion 31 Control device (control means)

Claims (5)

A method of manufacturing a lead frame formed by punching a thin metal plate,
A first dimple forming a first dimple arranged in a predetermined region of the metal thin plate at a predetermined interval in a row direction and a column direction perpendicular to each other by pressing using a first press die Forming process;
A press working using a second press die is arranged in the predetermined region so as to be aligned in the row direction and the column direction at a constant interval, and the row direction and the column with respect to the first dimple. And a second dimple forming step for forming a second dimple having a positional relationship shifted in the direction by a distance of half the distance. By press working using a third press die, the predetermined region is arranged in the row direction and the column direction at a constant spacing, and the spacing in the row direction with respect to the first dimple. Forming a third dimple having a positional relationship shifted by a half of the distance and having a positional relationship shifted by a half of the distance in the column direction with respect to the second dimple Process,
By the press working using the fourth press die, the predetermined region is arranged in the row direction and the column direction at regular intervals, and is arranged in the column direction with respect to the first dimple. A fourth dimple forming a fourth dimple having a positional relationship shifted by a half distance of the interval and having a positional relationship shifted by a half distance of the interval in the row direction with respect to the second dimple The method for manufacturing a lead frame according to claim 1, further comprising a forming step. A lead frame manufacturing apparatus formed by punching a thin metal plate,
Protrusions arranged at regular intervals in a row direction and a column direction orthogonal to each other, and pressing the protrusions against a predetermined region of the thin metal plate forms a first dimple in the predetermined region A first press die for
Provided side by side in the first press die, arranged in the row direction and the column direction at a constant interval, and when facing the predetermined region, the row direction with respect to the first dimple And a projection facing the position displaced by half the distance in the row direction, and pressing the projection against the predetermined area of the thin metal plate forms a second dimple in the predetermined area. A second press die for
An apparatus for manufacturing a lead frame, comprising: conveying means for conveying the metal thin plate along an alignment direction of the first press die and the second press die. The first dimples are arranged side by side in the arrangement direction with respect to the first press die, arranged in the row direction and the column direction at a constant interval, and face the predetermined region. The metal thin plate has a protrusion that is opposed to a position that is shifted by a half the distance in the row direction with respect to the second dimple and a position that is shifted by a half the distance in the column direction with respect to the second dimple. A third press die for forming a third dimple in the predetermined region by pressing the protrusion against the predetermined region;
The first dimples are arranged side by side in the arrangement direction with respect to the first press die, arranged in the row direction and the column direction at a constant interval, and face the predetermined region. The metal thin plate has a protrusion that is opposed to a position that is shifted by a half distance of the interval in the column direction with respect to the second dimple and that is shifted by a half distance of the interval in the row direction with respect to the second dimple. The lead frame according to claim 3, further comprising a fourth press die for forming a fourth dimple in the predetermined region by pressing the protrusion against the predetermined region. Manufacturing equipment. A lead frame manufacturing apparatus formed by punching a thin metal plate,
A press die having protrusions arranged at regular intervals in a row direction and a column direction orthogonal to each other;
A press mold moving mechanism for moving the press mold to press the projection against the metal thin plate;
Relative movement means for relatively moving the metal thin plate and the press die in the row direction and the column direction;
A first dimple arranged in the row direction and the column direction at a predetermined interval in the row direction and the column direction by controlling the press-type moving mechanism and the relative movement means, and the row direction; And a second dimple that is arranged in the column direction at a constant interval and has a positional relationship that is shifted from the first dimple by a half distance of the interval in the row direction and the column direction, respectively. , Arranged in the row direction and the column direction at regular intervals, and having a positional relationship that is shifted with respect to the first dimple by a half distance of the interval in the row direction, A third dimple having a positional relationship shifted in the column direction by a distance of half of the interval with respect to the dimples, and aligned in the row direction and the column direction at a constant interval. And has a positional relationship that is shifted by a half of the interval in the column direction with respect to the first dimple, and is shifted by a half of the interval in the row direction with respect to the second dimple. And a control means for forming a fourth dimple having a positional relationship.

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