JPH06120393A - Bending method for lead of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a bending method adequate for various leads regardless of their shapes, by preventing solder from adhering to a bending punch or a die without inflicting damage on the lead in a bending step. CONSTITUTION:A lead bending method for a resin sealed semiconductor device with leads elongated outward from the resin part comprises a first step of bending a first bend part 3A of a lead 3 provided at a given distance away from an outgoing resin part and the end of the lead 3 is made upward, and a second step of clamping a second bend part 3B provided halfway between the outgoing lead part and the first bend part 3A by a clamper 14 and bending the second bend part 3B by rotating the clamper 14 so that an end part of the lead 3 is made downward.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a method for bending a lead of a semiconductor device which is resin-sealed.
2. Description of the Related Art In recent years, when mounting a semiconductor device on a substrate, a surface mounting technique has been widely used because of high integration and the like. In the case of surface mounting, the lead surface of the semiconductor device is plated with solder, and the lead shape is bent in a crank shape so that the tip portion is flat. In the bending process for forming such leads, it is desired to prevent lead damage and variations in bending dimensions.

2. Description of the Related Art A conventional lead bending method will be described with reference to FIGS. FIG. 4 is a sectional view for explaining the most general bending method. First, the semiconductor device 21 which is resin-sealed and whose leads are led to the outside is placed on the bending die 22.
The bending die 22 has a concave portion 23 for mounting a resin portion and a convex portion 24 adjacent to the concave portion 23 for molding the lead 29 into a curved shape. After that, as shown in FIG. 4A, the semiconductor device 21 is pressed and fixed from above by the pressing member 25, and the bending punch 26 is lowered from both sides of the pressing member 25 as indicated by the arrow. The bending punch 26 includes
The curved portion 27 is also formed, and the surface of the lead 29 is slidably bent by the curved portion 27, as shown in FIG.
The state shown in FIG. FIG. 5 is a cross-sectional view for explaining an example in which the lead 29 is bent while the lead 29 is connected to the lead frame, and is a method of cutting the lead simultaneously with the bending described in FIG. FIG. 5A shows a state in which the semiconductor device 21 is mounted on the bending die 22 and is fixed by the pressing member 25. As shown in FIG. 5A, a cutting die 28 is installed on the side of the bending die 22, the bending punch 26 is lowered as shown by an arrow, and unnecessary portions of the leads 29 are cut off. Bending is performed in the same manner as in the method of FIG. 4, resulting in the state of FIG. With such a bending method as shown in FIGS. 4 and 5, the bending punch 26
Also, since the bending die 22 and the surface of the lead 29 are slidably bent, the solder plated on the surface of the lead 29 is scraped off by the bending punch 26 and the bending die 22, and the lead is damaged and the number of times is increased. Bending punch 2 every time
6. Solder plating adheres to the bending die 22. In particular,
As shown in FIG. 4 (C), it is easy to accumulate at the corners. Figure 4
In (C), 30 is a bending punch 26 and a bending die 22.
Solder plating attached to the corners of the. From the above, quality is deteriorated due to lead damage, and bending punch 2
6. Due to the solder plating 30 which is attached to the bending die 22 and becomes thicker, the processed lead size varies. In order to suppress the dimensional variation, the bending punch 26 and the bending die 22 need to be stopped and frequently cleaned, resulting in poor work efficiency.
FIG. 6 is an alternative to the bending process performed while sliding the surface of the lead 29 as shown in FIGS. 4 and 5, and is for explaining a method of pressing one point of the lead 29 to perform crank-shaped bending. FIG. In FIGS. 6A and 6B, 3
Reference numeral 1 is a bending punch, which has a pressing portion 32 for pressing one point of the lead 29. FIG. 6A shows a state in which the semiconductor device 21 is mounted on the bending die 22 and the semiconductor device 21 is pressed and fixed by the pressing member 25 from above. From this state, the bending punch 31 is operated in an arched shape as indicated by the arrow, and as shown in FIG. 6B, the bending portion of the lead 29 is pressed to perform bending. In this method, since the sliding area between the bending punch 31 and the bending die 22 and the surface of the lead 29 is small, the amount of scraping off the solder plating is reduced, and the solder adhesion to the bending punch 31 and the bending die 22 is as shown in FIG. , About one-third of that in the example of FIG. However, as the number of times is increased, the problem of dimensional variation due to the adhered solder remains. Further, in the case of the conventional example, since the bending work is performed by simply pressing the bending punch 31, the lead 29 is bent while sliding. There is a problem that the dimensional accuracy is deteriorated compared with the examples of FIGS. 4 and 5 in which the processing is performed. Further, another conventional example will be described. FIG. 7 is a cross-sectional view for explaining a conventional example using a bending roller, in which a bending roller 33 is used instead of the bending punch 26 in FIG.
FIG. 7A shows a state in which the semiconductor device 21 is mounted on the bending die 22 and is pressed by the pressing member 25 from above to fix the semiconductor device 21. From this state, the bending roller 33 is rotated as indicated by a thin arrow, so that the bending roller 33 is lowered as indicated by a thick arrow. By this operation, as shown in FIG. 7B, the lead 29 is bent so as to follow the shape of the convex portion 24 of the bending die 22. After that, the unnecessary portion of the lead 29 is cut. With this method, the lead 29 is processed along the convex portion 24 of the bending die 22 without scraping off the solder plating, and thus the lead dimensional accuracy becomes good. However, since the lead is bent while rotating the roller, the lead must have at least a length equal to the circumference of the roller in order to perform reliable bending. Not applicable for short leads that are not connected to the frame. If the unnecessary portion of the lead is cut before the solder plating, the connection strength in the case of surface mounting can be increased. That is, the connection strength becomes greater when the end face of the lead tip portion directly connected to the substrate is also plated with solder. Therefore, in recent years, in many lead frames, the tips of the leads connected to the substrate are formed in a free state. Under such circumstances, the bending method for cutting only the unnecessary portion of the lead after bending as shown in FIG. 7 is not preferable.

[Problems to be Solved by the Invention] As described above,
All of the conventional lead bending methods are applicable to both the lead-unnecessary portion that has been cut in advance and the one that is cut after bending (hereinafter referred to as cut products and closed products), lead damage prevention, and bending punch. It is not possible to simultaneously realize both prevention of solder adhesion to the bending die. The present invention solves the above problems and provides a lead bending method that simultaneously satisfies the above problems.

SUMMARY OF THE INVENTION A method of bending a lead of a semiconductor device according to the present invention which solves the above-mentioned problems is a semiconductor device in which a semiconductor element is sealed with a resin and leads connected to the semiconductor element are led out of the resin. The first bending portion 3A of the lead 3 separated from the resin lead-out portion by a predetermined length.
A first step of bending so that the tip end side of the lead faces upward, and a second bent portion 3B of the lead 3 in the intermediate portion between the resin lead-out portion and the first bent portion 3A is clamped by a clamper 14, The second step of bending the lead tip side by rotating the clamper 14 is directed downward.

According to the present invention as described above, the bending process is divided into two steps, and only the lead tips directly connected at the time of surface mounting are accurately processed by using the bending punch and the bending die, and the lead intermediate part is processed. By performing the bending process of the above with a clamper, the sliding distance at the time of bending process is minimized without deteriorating the dimensional accuracy of the lead.
Solder adhesion to the bending punch and bending die can be minimized. Therefore, the lead quality is improved and the dimensional error due to the solder attached to the punch and the die is reduced. Further, it can be applied to both cut products and closed products.

The method for bending the leads of the semiconductor device of the present invention will be described in detail below. 1A to 1D are cross-sectional views for explaining each step of the first embodiment of the present invention. In FIGS. 1A and 1B, 1 is a semiconductor device including a resin portion 2 containing a semiconductor element and a solder-plated lead 3, and 4 is a recess 5 for supporting the resin portion 2 of the semiconductor device 1.
A lifter having a convex portion 6 that supports a root portion of the lead 3 and supported by a spring (not shown) from below to be lowered by being pressed, and 7 are arranged on both sides of the lifter 4 and a curved portion 8 is provided. A bending die which is fixed above the lifter 4 and the bending die 7 and which can be moved up and down and has a curved portion 10; and 11 is a semiconductor device which moves up and down together with the bending punch 9. It is a holding member that holds down.
The bending die 7 and the bending punch 9 are made of ceramic having poor solder wettability. As shown in FIG. 1A, first, the semiconductor device 1 is mounted on the lifter 4 with the bending punch 9 and the pressing member 11 separated from the lifter 4. At this time, the resin portion 2 of the semiconductor device 1 is supported by the concave portion 5, and the root portion of the lead 3 except the first bent portion 3A is supported by the convex portion 6. From this state, the bending punch 9 and the pressing member 11 are lowered. Holding member 1
Reference numeral 1 holds the resin portion 2 of the semiconductor device 1 from above and sandwiches the semiconductor device 1 between it and the lifter 4. When the bending punch 9 and the pressing member 11 are further lowered, a spring (not shown) that supports the lifter 4 from below is pushed and the lifter 4 is lowered. By lowering the lifter 4, as shown in FIG. 1B, the first bending portion 3A of the lead 3 is sandwiched between the fixed bending die 7 and the bending punch 9, and the respective bending portions 8, It conforms to the shape of 10, and is curved so that the tip side faces upward. At this time, the bending die 7 and the surface of the lead 3 are slid, but the distance is very small, and the lead 3 is not damaged and solder is not attached to the bending die 7. (First Step) The disconnection step of this embodiment described above is performed in the state of the lead frame. This is for the following reason. If the semiconductor device is cut from the lead frame and the bending process is performed in a single state, the positioning in the bending process must be performed by the resin portion. The resin sealing is performed by pouring the resin using the upper mold and the lower mold. At this time, the upper die and the lower die often shift, and the resin portion of the semiconductor device is vertically displaced. That is, if the resin portion is positioned and bent, the lead shape may not be symmetrical between the left and right sides of the semiconductor device. The lead frame of this embodiment is formed with the lead tip portions free. That is, a cut product is used in which the tip end portions of the leads connected to the substrate during surface mounting are not connected to the lead frame. When using a closed product in which the tip portions of the leads are connected to the lead frame, cutting is performed after the bending.
Thus, through the first step, the first bending portion 3 of the lead 3
The bent semiconductor device 1 is fixed by sandwiching it between the support base 12 and the pressing member 13 (different from the one in the first step), as shown in FIG. 1C. Then, the leads 3 on both sides are clamped from above and below by the clamper 14, respectively, and the clamper 14 is rotated by approximately 90 degrees to bend the second bent portion 13B of the lead 3.
(Second Step) Details of the second step will be described with reference to an enlarged perspective view of FIG. The clamper 14 is a pair of plate members 14
A, 14B, and one plate member 14A,
The curved portion 14A ′ is formed so as to correspond to the bent shape of the second bent portion 3B of the lead 3. First, as shown in FIG. 2A, the clamper 1 including the plate-shaped members 14A and 14B is used.
The lead 3 is clamped from above and below by 4. Next, the clamp 14 is moved to the position shown in FIG.
As shown in (B), the second bent portion 3B of the lead 3 is bent by rotating it by about 90 degrees. In this case, there is no looseness between the clamper 14 and the lead 3, and there is almost no damage to the lead 3 or solder attachment to the clamper 14. As described above, the lead 3 is bent into a crank shape through the first step and the second step, and has a shape capable of surface mounting. In this embodiment, in order to more reliably form the first bent portion that comes into contact with the substrate during surface mounting, as shown in FIG. It is sandwiched between two different steps) and fixed, and then the correction punch 17 presses the first bending portion 3A of the lead 3 to correct the bending. Even in this bending correction step, since the correction punch 17 and the lead 3 do not move in a slidable manner, there is no damage to the lead and no solder is attached to the correction punch and the bending die. next,
Another embodiment of the present invention will be described. 3 (A) to (D)
[FIG. 8] is a sectional view for explaining a second embodiment of the present invention. The second embodiment differs from the first embodiment in that a bending roller is used in the first step. Figure 3
As shown in (A) and (B), instead of the bending die of the first embodiment, bending rollers 18 are arranged on both sides of the lifter 4. First, the semiconductor device 1 is mounted on the lifter 4 as shown in FIG. After that, the bending punch 9 and the pressing member 11 are lowered to fix the semiconductor device 1.
Further, by lowering the bending punch 9 and the pressing member 11,
Push down the lifter 4 as shown in FIG.
Bending punch 9 and bending roller 18 at the tip (first bending portion) of
It is sandwiched between and and is bent so as to bend upward. After that, as shown in FIG. 3C, it is fixed by being sandwiched between the support base 12 and the pressing member 13, and the leads 3 on both sides are clamped by the clampers 14 from above and below, respectively. The second bending portion 13B of the lead 3 is bent by rotating 90 degrees. Furthermore, FIG. 3 (D)
As shown in FIG. 5, in order to more reliably form the first bent portion that comes into contact with the substrate during surface mounting, the semiconductor device 1 is sandwiched between the support 15 and the pressing member 16 and fixed, and then the correction punch 17 is used. The first bending portion 3A of the lead 3 is pressed to correct the bending. In the case of the present embodiment, the bending roller 18 is used to bend the lead 3 while rotating the same, so that the first
Further, damage to the leads 3 and adhesion of solder to the bending roller 18 are reduced as compared with the embodiment.

According to the lead bending method for a semiconductor device of the present invention, the bending process is divided into two steps, and only the lead tips directly connected during surface mounting are accurately processed using a bending punch and a bending die. By bending the middle part of the lead with a clamper, the dimensional accuracy of the lead is not deteriorated, and the sliding distance during bending is minimized to prevent damage to the lead, bending punch and bending die. It is possible to minimize the adhesion of solder to the. Therefore, the lead quality is improved and the dimensional error due to the solder attached to the punch and the die is reduced. Further, it can be applied regardless of the form of the lead frame. That is, it can be applied to both cut products and closed products.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a lead portion for explaining bending processing by the clamper of the present invention.

FIG. 3 is a sectional view for explaining a second embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a conventional general lead bending method.

FIG. 5 is a cross-sectional view for explaining a conventional lead bending method for simultaneously performing cutting.

FIG. 6 is a cross-sectional view for explaining a conventional lead bending method by a one-point press.

FIG. 7 is a cross-sectional view for explaining a bending method using a conventional bending roller.

[Explanation of symbols]

 1--semiconductor device 2--resin part 3 ---- lead 3A--first bending part 3B--second bending part 4--lifter 7--bending die 8--bending die 7 Curved part 9 --- Bending punch 10 --- Curved part of bending punch 9 14 --- Clamper

Claims (4)

[Claims] 1. A method for bending a lead of a semiconductor device, wherein a semiconductor element is sealed with a resin, and leads connected to the semiconductor element are led out of the resin, wherein a predetermined length from a resin lead-out portion of a lead (3). A first step of bending the separated first bent portion (3A) so that the tip end side of the lead faces upward; a resin lead-out portion of the lead (3) and the first bent portion (3A)
And a second step of bending the second bent portion (3B) in the middle part of the clamp with a clamper (14) and rotating the clamper (14) so that the lead tip side faces downward. A method for bending a lead of a semiconductor device, comprising: 2. In the first step, the lead (9) is provided between a bending punch (9) and a bending die (7) each having a curved portion (10, 8) corresponding to a lead bending shape which is opposed and meshes. The lead bending of the semiconductor device according to claim 1, wherein the first bending portion (3A) of 3) is inserted, and then the bending punch (9) and the bending die (7) are engaged with each other. Method. 3. The first step comprises bending punch (9) having a curved portion (10) corresponding to a lead bending shape, and vertically while rotating along the curved portion (10) of the bending punch (9). The first bending portion (3A) of the lead (3) is inserted between the moving bending roller (18) and then the bending punch (9) and the bending roller (18) are operated. The lead bending method for a semiconductor device according to claim 1, wherein 4. The bending correction is performed by pressing the first bending portion (3A) of the lead (3) from above by a correction punch (17) after the second step. 4. The method for bending a lead of a semiconductor device according to 3.