JPH08204091A - Lead cutter for semiconductor device - Google Patents

Abstract

PURPOSE: To prevent solder from being separated and a cut end portion from being widened when cutting an external lead so that solder plating is left on its cut end surface. CONSTITUTION: External lead pressing surfaces 13a, 14a of a die 13 and a shedder 14 and a scooping surface 15a of a cut punch 15 are inclined. An inclination angle is set so that, as directing to a top end side of an external lead 12, these surfaces are gradually omnipresent on a front side in a progress direction of the cut punch 15 when cutting. A cut part of the external lead 12 is extended by the cut punch 15 when cut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device lead cutting apparatus for cutting external leads of a surface mount semiconductor device by using a die and a punch.

[0002]

2. Description of the Related Art Conventionally, in manufacturing a resin-encapsulated semiconductor device, first, a semiconductor element is mounted on an element mounting portion of a lead frame, and the semiconductor element and an internal lead are connected by a thin metal wire. The mounting part was sealed with resin. Then, after the resin was sealed, the external leads were subjected to solder plating, and then the external leads were cut.

In a surface mount type semiconductor device, an external lead is cut into a predetermined length and then bent. In addition,
The external lead may be cut into a predetermined shape after being bent.

When the external lead is cut after the solder plating is performed as described above, the solder plated portion is removed from the end surface of the external lead, and the material of the lead frame is exposed. For this reason, the tip end surfaces of the external leads after cutting are easily oxidized, and the solder wettability when mounting on a printed circuit board is reduced. In particular, QFP in which the external lead is bent into a so-called gull-wing shape
(Quad Flat Package), SOP (Small Outline Packa)
In ge), the fillet formed by the solidification of the solder that wets the tip surface of the external lead is not sufficiently formed, causing a problem in connection strength. This will be described with reference to FIGS.

FIG. 4 is a cross-sectional view showing a schematic structure of a conventional semiconductor device lead cutting device for cutting external leads by a punch and a die. FIG. 5 is a diagram showing the external leads cut by the cutting device of FIG. It is sectional drawing which shows the state which attached. In these figures, reference numeral 1 denotes an external lead of the surface-mount type semiconductor device, and the external lead 1 is connected to a resin sealing portion on the left side in FIG. 2 is die, 3
Is a shedder for holding the external lead 1 together with the die 2 and 4 is a punch. This punch 4 is an external lead 1
Is cut in a direction orthogonal to the extending direction. In FIG. 5, reference numeral 5 denotes a printed circuit board. Solder lands (not shown) are formed on the semiconductor device mounting surface of the printed circuit board 5. 6 is solder.

[0006] In order to cut the external lead 1 by the cutting device shown in FIG. 4, the external lead 1 after the solder plating is mounted on the printed board by the die 2 and the shedder 3 by positioning the mounting surface 1 a on the printed board on the side of the shedder 3. Then, the punch 4 is held, and then the punch 4 is moved downward in the drawing. When cut in this manner, the solder plated on the mounting surface 1a of the external lead 1 slightly extends to the portion of the cut end surface that is closer to the mounting surface 1a.

After cutting, the outer lead 1 is bent into a gull wing shape, and then the tip end of the outer lead 1 is overlapped with the semiconductor device mounting surface of the printed circuit board 5 as shown in FIG. Solder to the soldering land.

When soldering is performed in this manner, the external leads 1
Since the solder plating layer is formed on the mounting surface 1a and the side surfaces of the external leads 1
In the cut end face 7 of FIG. 5, the solder 6 only wets the slight solder plating layer on the mounting surface 1a side. That is, the fillet is not sufficiently formed on the cut end face 7 and the connection strength is reduced.

As a lead cutting device capable of leaving a solder plating layer over substantially the entire area of the tip of an external lead, there is, for example, one disclosed in Japanese Patent Application Laid-Open No. H4-150063. The lead cutting technique disclosed in this publication will be described with reference to FIG.

FIG. 6 is a view showing a conventional lead cutting method for cutting an external lead while leaving a solder plating layer substantially over the entire area. FIG. 6A is a schematic configuration diagram of a cutting apparatus for cutting the external lead from one side. FIG. 2B is an enlarged cross-sectional view showing the distal end portion of the external lead cut by the cutting device shown in FIG. 1A, and FIG. 2C is a schematic configuration diagram of a cutting device for cutting the external lead from both sides. FIG. 4D is a cross-sectional view showing, on an enlarged scale, the distal end of the external lead cut by the cutting device shown in FIG. In these figures, the same or equivalent members as those described in FIG. 4 are designated by the same reference numerals and detailed description thereof will be omitted.

In the cutting apparatus shown in FIG. 6A, a lead forming projection 8 is provided on the external lead holding surface of the die 2 so as to project therefrom. The projection 8 is inclined such that the upper surface thereof is gradually unevenly distributed upward as it goes to the cut end side. Then, when the punch 4 is lowered and cut in a state where the external lead 1 after the solder plating is held by the die 2 and the shedder 3 under pressure, as shown in FIG. The pressure molding is performed obliquely so as to substantially follow the inclined surface of the projection 9. That is, the solder layer 9 on the lower surface of the external lead extends along the inclined surface, and substantially the entire area of the cut end is covered with the solder.

The cutting device shown in FIG.
A cutting die 10 is provided so as to face with. The cutting die 10 has a structure in which pressure is applied in a direction opposite to that of the punch 4 to cut the external lead 1 together with the punch 4. The cutting surfaces (rake faces) of the punch 4 and the cutting die 10 are inclined so as to gradually protrude toward the tip of the external lead.

In order to cut the external lead 1 by the cutting device shown in FIG. 6C, the punch 4 and the cutting die 10 hold the external lead 1 while holding the external lead 1 between the die 2 and the shedder 3. Cut to sandwich. When cut in this manner, the cut end of the external lead 1 is obliquely pressed by the punch 4 and the inclined surface of the cutting die 10, as shown in FIG. 6D. That is, the solder layers 9 on the upper and lower surfaces of the external leads extend along the inclined surface,
Substantially the entire area of the cut end is covered with the solder.

That is, by employing the method shown in FIG. 6, a fillet can be sufficiently formed when the gull-wing-shaped external lead is mounted on a printed circuit board.

As a cutting device for cutting external leads, there is a cutting device having a structure in which bending and cutting of external leads are performed at the same time, as disclosed in Japanese Patent Application Laid-Open No. Hei 4-51551. This cutting device will be described with reference to FIG.
FIG. 7 is a schematic configuration diagram of a conventional cutting device that simultaneously performs bending and cutting of external leads. In this figure, the same or equivalent members as those described in FIGS. 4 and 6 are denoted by the same reference numerals, and detailed description is omitted.

The cutting device shown in FIG. 7 is configured such that the punch 4 faces the die 2, and the facing surfaces of the punch and the die gradually move downward (the advance of the punch 4) as they face the tip of the external lead 1. (Front side in the direction). A cutting die 10 is arranged on the side of the die 2 with its cut surface protruding above the inclined surface of the die 2. For this reason, the cutting angle of the punch 4 of this cutting device is acute.

In the cutting device thus constructed, when the punch 4 is lowered while the external lead 1 is sandwiched and held by the die 2 and the shedder 3, the external lead 1 is bent by the die 2 and the punch 4. By doing so, the variation of the plurality of external leads 1 arranged in parallel is corrected, and the tips of the external leads are cut by the cutting die 10 and the punch 4. In this cutting device, since the cutting angle of the punch 4 is acute, the solder does not extend to the cut end surface of the external lead 1. That is, similarly to the cutting apparatus shown in FIG. 4, a fillet is not sufficiently formed at the time of mounting on a printed circuit board.

[0018]

However, when the tip of the external lead is press-formed as in the method shown in FIG. 6, the solder layer 6 plated on the surface of the external lead, especially on the side surface, is required.
May be easily peeled off, and the peeled solder may be bridged between the external leads 1 and short-circuited between the external leads. In addition, there is a problem that the tip portion of the external lead is plastically deformed by the pressure molding and its width is widened, and a solder bridge is likely to occur during mounting on the printed board.

Further, as shown in FIG.
If the cutting die 10 sandwiches the outer lead 1 to cut it, the punch 4 and the cutting die 10 may be damaged due to a large load. Moreover, since both the punch 4 and the cutting die 10 must be driven, the structure of the mold becomes complicated.

The present invention has been made in order to solve such a problem. In cutting the external lead so that the solder plating remains on the cut end surface, the solder may be peeled off or the cut end may be expanded. An object of the present invention is to provide a semiconductor device lead cutting device that does not have a simple structure and that does not easily damage a punch.

[0021]

According to a first aspect of the present invention, there is provided a lead cutting apparatus for a semiconductor device, which gradually cuts an external lead pressing surface of a die and a shedder and a rake face of a punch toward the tip of the external lead. The punch is inclined so as to be unevenly distributed on the front side in the traveling direction of the punch.

A lead cutting device for a semiconductor device according to a second aspect of the present invention is the lead cutting device for a semiconductor device according to the first aspect of the present invention, wherein a lead pressing projection is provided on a portion of the rake face of the punch that is on the tip side of the external lead. It is a thing.

[0023]

According to the first aspect of the invention, the punch is moved in the cutting direction while the external lead is being held by the die and the shedder, so that the cut portion of the external lead is cut while being stretched by the punch. . For this reason, the solder layer at the portion where the external lead is stretched is extended widely to the cut end surface.

According to the second aspect of the present invention, since the distal end of the external lead contacts the projection of the punch and is bent forward in the traveling direction of the punch at the time of cutting, the cut portion of the external lead is cut while being bent and stretched. Is done.

[0025]

【Example】

Example 1. Hereinafter, an embodiment of the first invention will be described in detail with reference to FIGS. FIGS. 1A and 1B are cross-sectional views showing the configuration of a semiconductor device lead cutting device according to the first invention. FIG. 1A shows a state where external leads are clamped, and FIG. 1B shows a state during cutting. . FIG. 2 is an enlarged cross-sectional view showing a cut end portion of an external lead cut by the lead cutting device according to the first invention. FIG. 2A shows a state after cutting is completed, and FIG. Indicates a state of being soldered to the printed circuit board.

In these figures, 11 is a resin sealing portion of the semiconductor device, 12 is an external lead, and the external lead 12 protrudes from the side of the resin sealing portion 11 to the side. A plurality are arranged side by side in a direction orthogonal to the paper surface.
The surface of the external lead 12 is plated with solder.

Reference numeral 13 denotes a die, and 14 denotes a shedder for holding the external lead 12 together with the die 13 under pressure. The shedder 14 is connected to a lifting device (not shown) so as to be movable up and down. Further, the external lead pressing surfaces 13a, 1 of these die 13 and shedder 14 are provided.
4a is about 20 to the lower right with respect to the horizontal line indicated by H in the figure.
It is formed with an inclination.

The die 13 and the shedder 1
A cutting punch 15 is arranged on the side of 4. The cutting punch 15 is connected to a pressure device (not shown) and is configured to move up and down along the side surfaces of the die 13 and the shedder 14. The rake face 15a serving as a cutting face of the cutting punch 15 is formed so that the cutting angle becomes an obtuse angle.
Similarly to 4a, it is inclined downward by about 20 ° with respect to the horizontal line H.

In other words, the rake face 15a and the external lead pressing surfaces 13a and 14a are inclined so as to be gradually eccentric to the front side in the traveling direction of the cutting punch 15 at the time of cutting as the tip faces the external lead 12. I have.

In order to cut the external lead 12 by the lead cutting device thus configured, first, FIG.
As shown in FIG.
Is held at the clamping pressure. At this time, the external leads 12 are positioned so that the surface to be soldered to the printed circuit board faces the shedder 14.

Thereafter, as shown in FIG. 1B, the cutting punch 15 is lowered to perform cutting. At this time, since the cutting angle of the cutting punch 15 is an obtuse angle, the external lead 12
Will be severely stretched and cut. FIG. 2 shows the shape of the cut end of the external lead 12 after cutting.
(A).

As shown in FIG. 2A, the external lead 12
The tip end surface of the cut end portion 12a is inclined downward to the right from the upper edge, and the solder layer 16 is extended from above to the inclined end surface, and the solder layer 16 covers substantially the entire area. The solder layer 16 covering the end surface of the external lead 12 is thickest on the upper side and gradually thinner toward the lower side.

The external lead 12 thus cut is
It is bent into a gull wing shape in the same manner as before, and FIG.
As shown in FIG. 2B, when the surface facing the shedder 14 at the time of cutting is directed toward the printed circuit board 17 {upside down from FIG. (Not shown). When soldering is performed in this manner, the cut end portion of the external lead 12 is synergized by the fact that the tip end surface of the cut end portion 12a is obliquely inclined and that substantially the entire tip end surface is covered with the solder layer. A sufficient solder fillet 18 is formed on 12a.

Therefore, by sufficiently forming the solder fillet 18, the external lead 12 is soldered to the printed board 17 with high connection strength. Moreover, since the external leads 12 are cut so as to be stretched, the solder layer plated on the surface of the external leads 12 is hard to peel off, so that the external leads 12 are not short-circuited by the peeled solder. Moreover, since the cut end portion 12a is not plastically deformed and its lateral width is not expanded, a solder bridge is not formed at the time of mounting on the printed board.

Further, since the cutting punch 15 does not have a structure which is vertically moved to the side of the die 13 and the shedder 14 and faces the die 13, the cutting punch 15 does not collide with the die 13 and be damaged. Further, the cutting load is applied to the cutting punch 1.
Since it is only 5, the mold manufacturing cost can be kept low, and a pressing device having a simple structure can be used.

In the above embodiment, an example is shown in which the external lead pressing surfaces 13a and 14a of the die 13 and the shedder 14 and the rake surface 15a of the cutting punch 15 are each set to about 20 ° with respect to the horizontal line H. If the cutting angle of the rake face 15a is obtuse, the inclination angles of these faces can be changed as appropriate. Therefore, the external lead pressing surface 1
The 3a, 14a and the rake face 15a can be set at different angles.

Example 2. The cutting punch may be provided with a protrusion as shown in FIG. FIG. 3 is a cross-sectional view showing a schematic configuration of a semiconductor device lead cutting apparatus according to a second invention. In FIG. 3, the same or equivalent members as those described in FIG. 1 and FIG. Detailed description is omitted.

In FIG. 3, reference numeral 21 is a lead pressing protrusion, and this protrusion 21 is a rake face 15 a of the cutting punch 15.
The rake face 15 at the part of the outer lead tip side of the
It is integrally provided so as to protrude downward with a step with respect to a. When the lead pressing projection 21 is provided on the cutting punch 15 in this way, the cutting punch 15 descends at the time of cutting so that the tip end of the outer lead 12 comes into contact with the projection 21 and is bent downward.

That is, since the external lead 12 is bent and stretched and cut, the external lead 12 is used.
The upper surface of the external lead 12 is stretched more than in the case where the cutting is performed by the cutting device shown in FIG. As a result, the area of the cut end portion covered with solder increases, and soldering can be performed more reliably on the printed circuit board.

[0040]

As described above, the lead cutting apparatus for a semiconductor device according to the first aspect of the present invention gradually cuts the outer lead pressing surface of the die and the shedder and the rake face of the punch toward the tip of the outer lead. Since the punch is inclined so as to be unevenly distributed in the front side in the traveling direction of the punch, by moving the punch in the cutting direction while holding the external lead by the die and the shedder, the cut portion of the external lead is stretched by the punch. While being cut.

For this reason, since the solder layer at the portion of the external lead to be extended is extended widely to the cut end face, the cut end face can be covered with solder. Therefore, according to the semiconductor device lead cutting apparatus of the present invention, the external leads can be cut so that the external leads can be reliably soldered to the printed circuit board.

Further, since the punch does not have a structure facing the die, the punch does not collide with the die and is not damaged, so that stable cutting can be performed. Moreover, since only the punch applies the cutting load, the manufacturing cost of the mold can be kept low, and a pressing device having a simple structure can be used.

A lead cutting device for a semiconductor device according to a second aspect of the present invention is the lead cutting device for a semiconductor device according to the first aspect of the present invention, wherein a lead pressing projection is provided on a portion of the rake face of the punch that is on the leading end side of the external lead. Therefore, at the time of cutting, the tip of the external lead comes into contact with the projection of the punch and is bent forward in the traveling direction of the punch. Therefore, the cut portion of the external lead is cut while being bent and stretched.

For this reason, since the external lead is bent and stretched and cut, the upper surface of the external lead is stretched larger than when cut by the cutting device according to the first invention. As a result, the area of the cut end portion covered with solder increases, and soldering can be performed more reliably on the printed circuit board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a semiconductor device lead cutting device according to a first invention, wherein FIG. 1 (a) shows a state where external leads are clamped, and FIG. 1 (b) shows a state during cutting. Show.

FIG. 2 is an enlarged sectional view showing a cut end portion of an external lead cut by a lead cutting device according to the first invention, and FIG. 2 (a) shows a state after cutting is completed, and FIG. )
Indicates a state of being soldered to the printed circuit board.

FIG. 3 is a sectional view showing a schematic configuration of a lead cutting device for a semiconductor device according to a second invention.

FIG. 4 is a cross-sectional view showing a schematic configuration of a conventional semiconductor device lead cutting apparatus for cutting external leads by a punch and a die.

FIG. 5 is a cross-sectional view showing a state in which external leads cut by the cutting device of FIG. 4 are soldered to a printed circuit board.

FIG. 6 is a view showing a conventional lead cutting method for cutting an external lead while leaving a solder plating layer in substantially the entire area thereof. FIG. 6 (a) is a schematic configuration diagram of a cutting device for cutting the external lead from one side; FIG. 2B is an enlarged cross-sectional view showing the tip of the external lead cut by the cutting device shown in FIG. 2A, and FIG. 2C is a schematic configuration diagram of a cutting device for cutting the external lead from both sides. FIG. 4D is an enlarged cross-sectional view showing the tip of the external lead cut by the cutting device shown in FIG.

FIG. 7 is a schematic configuration diagram of a conventional cutting device that simultaneously performs bending and cutting of an external lead.

[Explanation of symbols]

12 ... External lead, 13 ... Die, 14 ... Sheder, 13
a, 14a: external lead pressing surface, 15: cutting punch, 1
5a ... rake face, 21 ... protrusion.

Claims (2)

[Claims] 1. A semiconductor device lead cutting device for cutting a solder-plated external lead of a semiconductor device through a punch on a side of the die while holding the external lead by a die and a shedder. A lead cutting device for a semiconductor device, wherein an outer lead pressing surface of a shedder and a rake surface of a punch are inclined so as to be gradually eccentric to a front side in a traveling direction of a punch at the time of cutting as approaching an outer lead tip side. 2. The lead cutting device for a semiconductor device according to claim 1, wherein a lead pressing projection is provided on a portion of the rake face of the punch, which is on a tip side of the external lead.