JPH0669393A - Method for bending lead - Google Patents

Abstract

PURPOSE:To perform a highly flexible bending work of leads wherein its yield is good and there is no change with the passage of time in the bent shapes of the leads, by performing the fixing of the mounting parts of the leads extended from the main body of a semiconductor device to the outside, and by grasping the end parts of the leads with a holding part, and further, by moving the holding part along a preset locus through a numerical control. CONSTITUTION:The fixing of a plurality of leads 32 extended from one side surface of a resin body 30 to the outside are performed, grasping them with a lead chuck 33. Then, the leads are bent preliminarily reciprocating the lead chuck 33 by a numerical control. Subsequently, in the vertical plane including the center line of the lead 32, the lead chuck 33 is so moved downward that its end part on the side of the resin body 30 generates the circular arc, whose radial length is equal to the lead length between the lead chuck 33 and a lead clamp 34, using the fixing end of the lead as its center. Further, moving the lead chuck 33 so as to approach the resin body 30, the decisive bending of the lead is performed. Thereby, the bend work of the leads, whose flexibility is high, can be accomplished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of bending a lead by numerical control.

[0002]

2. Description of the Related Art There are many types of semiconductor device packages, which are classified into a surface mounting type and an insertion mounting type when classified by a mounting method on a wiring board. FIG. 5 is a perspective view showing an example of the surface mount type, and this package is called SOP (Small Outline Package). In the figure, 50 is a resin body molded of resin, and a semiconductor chip is sealed inside. Five
Numerals 1, 51 ... Are leads connected to the internal terminals of the semiconductor chip, and extend from the side wall of the resin body 50 to the outside and are bent in a gull wing shape.

FIG. 6 is a perspective view showing an example of an insertion mounting type semiconductor device. This package is a DIP (Dual I).
nline Package) is called. In the figure, 60 is a resin body in which a semiconductor chip is sealed. 61, 61 ... Leads connected to the internal terminals of the semiconductor chip, extending from the side wall of the resin body 60 to the outside so that they can be inserted and mounted in a through-hole type wiring board. It is bent.

Conventionally, both types of bent shapes of the leads 51, 51 ... And 61, 61 ... Are processed by a mold. FIG. 7 is a sectional view of the mold. In the figure, 70 is a bending die, and 71 is a stripper for pressing and fixing the resin body 72 and the leads 73 to the bending die by the spring force of the spring 74. A bending punch 75 is dropped on the lead 73 to cause plastic deformation of the lead 73 sandwiched between the bending punch 75 and the bending die 70.

The reason why the resin body 72 and the leads 73 are fixed by using the spring force in the above-mentioned mold is as follows. A plurality of leads 73 are connected to each other by a tie bar, but the tie bar is cut off from each lead 73 before bending. Then, the cut of the tie bar of each lead 73 has a burr in which a part of the tie bar is left uncut. Therefore, in order to remove this burr, 500 kg / cm ² Although some high-pressure water is sprayed on all the leads 73, the pressure of the high-pressure water causes the respective leads 73 to warp. Therefore, if all the leads 73 are fixed to the mold with a strong force, they will not warp when they are fixed, but if the stripper 71 that is fixed after bending the leads is removed, the leads will warp again. . As a result, the lead 73 cannot be bent according to the designed shape. Therefore, the lead 73 needs to be fixed to the mold with a weak force that does not eliminate the warp, and the spring force is conventionally used as described above.

Next, the manner in which the lead 73 is sandwiched between the bending die 70 and the bending punch 75 that falls to cause plastic deformation and bends in the shape of a gull wing will be described with reference to FIGS. In the figure, the arrow indicated by P indicates the load point on the lead 73 of the punch 75. As shown in (a), the load of the punch 75 is applied to the tip of the lead 73 at first, but as the punch 73 falls, the lead bends downward, so that the lead is applied near where it is fixed by the die 70 and the stripper. Become. When the punch 75 further falls, the tips of the leads 73 collide with the die 70 as shown in (b). Further punch
As 75 falls, as shown in (c), it begins to bend into an L-shape with the tip of the lead 73 and the fixed point as a fulcrum, and the tip of the lead slides on the die 70 and approaches the fixed point as it bends. . And if you remove the punch 75 that was dropped,
As shown in (d), the lead 73 elastically springs back away from the die 70. There are the following problems in the lead bending process using the above mold.

As shown in FIG. 8C, the corner of the punch 75, which is the load point, rubs the surface of the lead 73 as the punch falls. For this reason, the outer layer portion of the surface of the lead 73, for example, solder plating or the like may be scraped and an electrical short circuit with the neighboring lead 73 may occur.

Further, the size of the spring back changes with the change of the material or the thickness of the lead. Therefore, even if the leads have the same bent shape, it may be necessary to manufacture or adjust the mold parts. Moreover, the die parts are expensive because they require ultra-precision processing technology, and because the lead time is long, it is not possible to quickly respond to various changes in the leads, including changes in the bent shape of the leads.

Further, the mold has to be made in accordance with the size of the resin body, and must be newly made every time the size of the resin body is changed.

Further, since the spring is used for fixing the lead to the mold, the force for fixing the lead to the mold is attenuated as the number of times the mold is used increases, so that the lead is bent. The shape changes with time. For this reason, the mold needs to be regularly maintained.

Further, in the above-mentioned mold, since there are no left and right guides with respect to the longitudinal direction of the lead, the lead may be bent by misaligning from the direction perpendicular to the mounting surface to the resin body. When the misalignment is large, the semiconductor device cannot be mounted on the wiring board because the lead distance is different from the wiring distance on the wiring board.

[0012]

As described above, in the lead bending process using the mold, the yield is poor due to the short circuit between the leads and the misalignment of the leads, and the bend shape changes with time. However, there is a problem in that the versatility of changing the lead, resin body, and bending shape of the mold used for is poor.

The present invention has been made to solve the above problems, and an object thereof is to provide a lead bending method which has a high yield, does not cause a change in bending shape over time, and is highly versatile. Is.

[0014]

According to a lead bending method of the present invention, a lead mounting portion extended from a semiconductor device main body is fixed, and a tip portion of the lead is sandwiched by a holding portion whose movement is numerically controlled. The lead bending process is performed by moving the holding unit along a preset track.

[0015]

According to the above-described lead bending method, it is possible to change the lead bending shape by changing the trajectory setting.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a bending apparatus according to the first embodiment of the present invention. In the figure, 10 is an X table unit, and a moving table is moved left and right by a feed screw which is driven by a motor. 11 is an X table unit
It is a Z table unit mounted on 10 moving tables, and the moving table moves up and down by a feed screw that is driven by a motor. Reference numeral 12 is a mechanical chuck (lead chuck), which is driven by a motor to rotate about a rotation axis, and the rotation axis is orthogonal to the central axes of both the X table unit 10 and the Z table unit 11 so that the Z table unit moves. Is attached to. 13
Is the upper part of the package clamp, and 14 is the lower part of the package clamp, and the semiconductor device is sandwiched between the upper part and the lower part and fixed so that the central axis of the lead is orthogonal to the rotation axis.

The movement of the movable table of each of the X table unit 10 and the Z table unit 11 and the rotation of the lead chuck 12 are numerically controlled by the driving force of separate motors whose rotation is controlled by an electric signal from the CPU. ing. Then, the CPU outputs the electric signal according to the program written in the storage device such as the ROM. Therefore, the tips of the leads sandwiched by the lead chuck 12 move along the trajectory set in the program.

In FIG. 2, the upper part 13 and the lower part 14 of the package clamp are the resin body 15 of the semiconductor device and the leads 16, 16 ...
It is sectional drawing which has sandwiched. The upper part 13 is composed of a sliding substrate 20, a pair of left and right body clamps 21 and 22 and lead clamps 23 and 24, respectively. Body clamps 21 and 22
Is attached to the lower surface side of the sliding board 20, and can be slid to the left and right on the sliding board 20 and can be fixed. The left lead clamp 23 is attached at a right angle to the left end of the left body clamp 21, and can be vertically slid and fixed with respect to the body clamp 21. The right lead clamp 24 is attached to the right end of the right body clamp 22 at a right angle, and can be vertically slid and fixed with respect to the body clamp 22. Similarly to the upper part 13, the lower part 14 is also composed of a sliding board 25, a pair of left and right body clamps 26 and 27, and lead clamps 28 and 29. The body clamps 26 and 27 are attached to the upper surface of the sliding board 25. Has been.

When the size of the semiconductor device is changed, in the upper part 13 of the package clamp, the body clamps 21 and 22 are slid to the left and right, and the lead clamps 23 and 24 are slid up and down, so that the size is increased. Can be changed. Further, also in the lower portion 14 of the package clamp, the body clamps 26 and 27 can be slid to the left and right, and the lead clamps 28 and 29 can be slid up and down, so that the above size change can be dealt with. Therefore, this package clamp is highly versatile for changing the size of the semiconductor device.

Next, a process for bending a lead into a gull wing shape by the above bending device will be described with reference to process sectional views of FIGS. First,
As shown in (a), clamp the resin body 30 to the body clamp.
It is pinched from the top and bottom with 31 and fixed. At this time, the lead clamp is slid so that the leads are not pinched. And
A plurality of leads 32 extending from one side surface of the resin body 30 are sandwiched and fixed by a lead chuck 33. Next, the tip of the lead 32 is centered on the extending portion of the resin body 30 of the lead 32, and an arc whose radius is the length of the lead is drawn in the vertical plane including the center line of the lead. 33
Preliminary bending is performed by reciprocating several times. The movement of the lead chuck 33 is performed by numerical control as described with reference to FIG. 1, and the lead 32 is pulled during the movement. By performing this preliminary bending, the warp generated in the lead 32 in the deburring process of the lead 32 can be removed as described above.

Then, as shown in FIG.
After loosening the body clamp 31 that sandwiches 30, the resin body 30 is fixed by sandwiching the resin body 30 with the body clamp 31 and the vicinity of the root of the lead 32 with the lead clamp 34 from above and below. Then, within the vertical plane including the center line of the lead 32, the lead chuck 33 has an arc centered on the fixed end of the lead and having a radius of the lead length between the lead chuck 33 and the lead clamp 34 of the chuck 33. The chuck 33 is moved downward so that the end portion of the resin body 30 is drawn. During this movement, the surfaces of the lead chuck 33 that sandwich the leads are parallel to the upper and lower surfaces of the resin body 30. The movement of the lead chuck 33 causes the lead 32 to bend into a gull wing shape.

Further, as shown in (c), the lead chuck 33 is moved so as to approach the resin body 30, and the central portion of the lead 32 is placed between the side surfaces of the upper lead chuck 33 and the lower lead clamp 34. Bend the pinch. By the way, as shown in (b), the side surfaces of the upper lead chuck 33 and the lower lead clamp 34 are both formed to have a clearance angle θ of about 10 ° from the vertical plane. Therefore, the bent portion of the lead 32 is bent at an acute angle smaller than the right angle by the clearance angle θ due to the bending.

Then, the lead chuck 33 is loosened to release the lead 32. Then, the lead 32 becomes the lead chuck.
Since the stress received from 33 disappears, springback occurs due to elasticity, and the bent portion of the lead 32 returns to an escape angle θ of about 90 °. The above-described bending is performed so that the bent shape as designed can be obtained when the lead springs back. By the way, by increasing the clearance angle θ, the lead 32
It is also possible to make the bent part of the acute angle. Further, the texture bending angle can be arbitrarily changed as long as it is equal to or less than the clearance angle θ. Then, although the leads open outward due to the spring back, since the leads are bent to a certain extent, they can be mounted on the wiring board with a smaller area than before. Then, the body clamp 31 and the lead clamp 34 are opened, the semiconductor device is taken out from the bending device, and the lead bending process is completed.

In the above bending method, the bending shape of the lead can be changed by changing the trajectory of the lead / read chuck that moves by numerical control. Further, even if the size of the spring back of the lead is changed due to the change of the material or the like, the variation of the spring back can be canceled by simply changing the track of the lead chuck in the texture bending process. Since the change of the trajectory can be made by changing the program, it can be performed more quickly and at a lower cost than changing the mold. It should be noted that preliminary bending and texture bending may not be performed if they are unnecessary.

Further, in the embodiment, since the leads are sandwiched by the lead chucks, unlike the conventional case, the leads are not bent so that the distance between the leads changes during bending. Therefore, in this embodiment, the intervals between the leads do not change during the bending process, and the leads cannot be mounted on the wiring board. Furthermore, since the surface of the lead is not rubbed during bending, electrical shorts between the leads do not occur due to shavings on the surface of the lead. Therefore, in the embodiment, since the lead interval deviation and the lead-to-lead short circuit which are the causes of the yield reduction in the conventional bending process do not occur in the embodiment, the yield is improved.

Further, in the embodiment, since the warp of the lead can be eliminated by performing the pre-bending, it is not necessary to fix the semiconductor device with the spring. Change can be eliminated.

FIG. 4 shows an SO according to the second embodiment of the present invention.
It is a perspective view of the semiconductor device of P. In the figure, 40 is a resin body molded of resin, and a semiconductor chip is sealed inside. 41, 41 ... Leads connected to terminals provided on the semiconductor chip, and extend from the side wall of the resin body 40 to the outside. Resin body
The side wall of 40 has a step-like shape with the lower part protruding outward from the height of the lead extension part. The side surface of this staircase portion is inclined downward, and each lead 41 extends from the top surface to the side surface.
A groove 42 is formed for each of them to fit into it.
Each lead 41 is fitted in a groove 42 and bent into a gull wing shape.

The method of bending the leads 41, 41 ... is different only in the use of the lead clamps, and the rest is as described with reference to FIG. In the first embodiment, the lead clamp 34 directly sandwiches the vicinity of the root of the lead 32, but in this embodiment, the upper and lower surfaces of the stepped portion are lead clamped.
The leads 41, 41, which are fitted into the grooves 42, 42 of the step-like portion by sandwiching the leads 34, are sandwiched. Further, since the side surface of the stepped portion is inclined downward, the bent portions of the leads 41, 41 ... Can be bent at an acute angle. Therefore, when the lead chuck 33 is opened and the leads 41, 41 ... Spring-back, the bent portion can be made 90 degrees or an acute angle.

In the second embodiment, the leads 41, 41, ... Are fitted in the grooves 42, 42 ..
The leads 41, 41, and the like collide with each other during transportation, and the interval is hardly changed. Therefore, in the second embodiment, it is possible to prevent the lead interval from changing not only during the manufacturing process but also after the manufacturing process, which prevents mounting on the wiring board.

[0031]

As described above, according to the present invention, it is possible to provide a lead bending method which has a high yield, does not cause a change in bending shape over time, and has high versatility.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a lead bending apparatus used in an embodiment method of the present invention.

FIG. 2 is a sectional view of a package clamp portion of a lead bending apparatus used in the method according to the embodiment of the present invention.

FIG. 3 is a process cross-sectional view of a lead bending process according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a conventional semiconductor device.

FIG. 6 is a perspective view of a conventional semiconductor device.

FIG. 7 is a cross-sectional view of a mold used for bending a lead.

FIG. 8 is a sectional view of a lead bending process using a mold.

[Explanation of symbols]

10 ... X table unit, 11 ... Z table unit, 1
2, 33 ... Mechanical chuck, 13 ... Package clamp upper part, 14 ... Package clamp lower part, 15, 30, 40 ... Resin body, 16, 32, 41 ... Lead, 20, 25 ... Sliding board, 2
1, 22, 26, 27, 31… Body clamp, 23, 24, 28, 2
9, 33 ... Lead clamp, 42 ... Groove.

Front page continuation (72) Inventor Masanobu Echizenya 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Tamagawa factory

Claims (4)

[Claims] 1. A mounting portion of a lead extending from a semiconductor device main body is fixed, a tip portion of the lead is sandwiched by a holding portion whose movement is numerically controlled, and the holding portion is moved along a preset trajectory. A method of bending a lead in which the bending of the lead is performed by doing so. 2. The method for bending a lead according to claim 1, wherein the semiconductor device body is provided with a vertical groove extending from the lead extending portion to the lower surface of the device body and having a width wider than at least the lead. 3. A semiconductor device main body is fixed, and a tip portion of a lead extended from the semiconductor device main body is sandwiched by a holding portion whose movement is numerically controlled, and the holding portion of the lead connects the lead and the semiconductor device main body. It is necessary to reciprocally move the holding part several times while drawing an arc centered on the mounting part and having the radius of the lead as a radius in the vertical plane including the center line of the lead and applying tension to the lead. The method for bending a lead according to claim 1 or 2, wherein the method is performed. 4. The track is centered on the fixed end of the lead in a vertical plane including the center line of the lead while keeping the portion sandwiched by the holding portions of the lead parallel to the main plane of the semiconductor device body. , The holding portion of the lead is moved downward so that the holding portion of the lead draws an arc whose radius is the length between the fixing portion of the lead and the holding portion, and this movement causes a straight line connecting the fixing portion of the lead and the holding portion with the semiconductor. The lead bending method according to claim 1 or 2, wherein the setting is performed until the angle formed by the main plane of the device body becomes an acute angle.