JP3946730B2 - Bond wire loop shape, semiconductor device having the loop shape, and wire bonding method - Google Patents

Description

  The present invention relates to a bonding wire loop shape connecting a first bonding point and a second bonding point, a semiconductor device having the loop shape, and a wire bonding method for forming the loop shape.

  FIGS. 11A and 11B show loop shapes of bonding wires (hereinafter abbreviated as “wires”) in a conventional semiconductor chip. FIG. 11A shows an example in which the loop shape of the wire 5 connecting the pad 2 (first bonding point) of the semiconductor chip 1 and the lead 4 (second bonding point) of the lead frame 3 is trapezoidal. FIG. 11B shows an example in which the loop shape of the wire 5 is triangular (see Patent Documents 1 and 2).

  The trapezoidal loop of FIG. 11A is realized by the wire bonding method shown in FIGS. That is, first, as shown in FIGS. 12A and 12B, a ball bonding capillary (hereinafter abbreviated as “capillary”) 6 is lowered to form a ball 7 formed at the tip of the wire 5 at a first bonding point. Bond to the pad 2.

  Next, as shown in FIG. 12 (c), the capillary 6 is raised to the point A and the wire 5 is fed out by a predetermined length. Then, as shown in FIG. 12 (d), the lead 4 as the second bonding point Move horizontally to point B in the opposite direction. Thereby, the wire 5 becomes a shape inclined to the B point. In general, moving the capillary 6 in the direction opposite to the second bonding point as described above is called a reverse operation.

  Next, as shown in FIG. 12E, the capillary 6 is raised to the point C, and the wire 5 is fed out by a predetermined length. As a result, the first brim 5a having a predetermined angle is attached to the B point portion of the wire 5. The portion up to the first flange 5a is the neck portion height H in FIG.

  Subsequently, as shown in FIG. 12F, the capillary 6 is reversely operated to the point D. Thereby, the wire 5 becomes a shape further inclined from the first flange 5a to the point D.

  Next, as shown by a solid line in FIG. 12G, the capillary 6 is raised to point E, and the wire 5 is fed out for a predetermined length. As a result, the second flange 5b having a predetermined angle is attached to the D point portion of the wire 5. A portion from the second ridge 5b to the first ridge 5a is a horizontal portion L in FIG. Further, the portion from the second flange 5b to the point E becomes the inclined portion S in FIG.

  Then, as indicated by a dotted line in FIG. 12G, the capillary 6 is lowered toward the lead 4 as the second bonding point, and the wire 5 is bonded to the lead 4.

  When the bonding between the pad 2 and the lead 4 is completed as described above, as shown in FIG. 12 (h), the capillary 6 is raised to the point F and the wire 5 is fed out for a predetermined length. The wire 5 is grasped by operating, and the capillary 6 is further raised in the state where the wire 5 is grasped. As a result, as shown in FIG. 12 (i), the wire 5 is cut so as to be shredded, and the wire tail 5 c having a predetermined length is exposed from the tip of the capillary 6.

  Next, as shown in FIG. 12 (j), the spark rod 9 is brought close to the wire tail 5c, and discharge is performed between the spark rod 9 and the wire tail 5c, thereby melting the portion of the wire tail 5c. 12 (k), a spherical ball 7 is formed at the tip of the wire 5 by the surface tension. With the above processing, one cycle of the bonding operation is completed, the process returns to FIG. 12A again, and the bonding operation at the next location is repeated.

On the other hand, the triangular loop of FIG. 11B is realized by the wire bonding method shown in FIGS. Basic processing steps in the case of triangular loop is the same as the case of the trapezoidal loop, since loop shape is a triangle, forming the horizontal portion L which definitive trapezoidal loop is not required. Accordingly, when the first ridge 5a is formed in the step of FIG. 13E, the capillary 6 is raised to the point E, and the wire 5 is fed out by an amount corresponding to the inclined portion S (see FIG. 11B). Then, as shown in FIG. 13F, the capillary 6 is lowered toward the lead 4 as the second bonding point, and the wire 5 is bonded to the lead 4. The subsequent steps for forming the ball 7 (FIGS. 13G to 13J) are the same as in the trapezoidal loop.

Japanese Patent Laid-Open No. 10-256297 (FIG. 6) JP 2000-277558 A (FIG. 2)

  Conventionally, the above-mentioned trapezoidal loop and triangular loop are often used for wire bonding of a semiconductor device. However, in order to reduce the size and thickness of the semiconductor device, the height H of the neck portion of the wire 5 should be as small as possible. It is desirable to make it low. In order to realize this, for example, as shown in FIG. 14A, after the wire 5 is bonded to the pad 2 (first bonding point) of the semiconductor chip 1, the wire 5 is bent horizontally from the top of the ball 7. It is only necessary to bond it to the lead 4 (second bonding point).

  However, the conventional wire bonding method using the ball 7 described above cannot form a loop shape as shown in FIG. That is, in the case of the conventional wire bonding method, when the spherical ball 7 is formed at the tip of the wire 5 by discharge (see FIGS. 12 (j) (k), 13 (i) (j)), the molten wire tail When 5c recrystallizes into a spherical ball 7, not only the portion of the ball 7, but also the wire portion near the boundary with the ball 7 is melted and recrystallized.

  For this reason, the wire portion in the vicinity of the ball 7 is somewhat more fragile than the original, and when the wire 5 is bent horizontally from the top of the ball 7 and pulled out as shown in FIG. There is a possibility that the wire 5 may break near the boundary. Further, even when the wire 5 does not break, a large strain is generated in the vicinity of the boundary with the ball 7 due to the 90 ° bending in the horizontal direction, so that the expected electrical and mechanical characteristics may not be obtained. . Therefore, in the case of the conventional wire bonding method, in order to avoid bending the wire at the recrystallized portion, a certain height H of the neck portion has to be adopted.

  In addition, since a certain amount of time is required to form the ball 7 by discharging, the bonding cycle time is also increased correspondingly, which hinders an increase in bonding speed. Furthermore, the formation of balls by electric discharge has variations, which has been one of the causes of unstable bonding characteristics.

  In order to eliminate the problem caused by the ball 7 as described above, for example, as shown in FIG. 14B, the wire 5 may be directly bonded to the pad 2 without forming a ball at the tip of the wire 5. However, since the height of the pad 2 is extremely low and is actually substantially flush with the upper surface of the semiconductor chip 1, there is a gap (neck portion height) between the drawn wire 5 and the semiconductor chip 1. It cannot be taken, and a new problem arises that the drawn wire 5 comes into contact with the semiconductor chip 1.

  The present invention solves the above-mentioned problems, can reduce the height of the neck as much as possible, can reduce the size and thickness of the semiconductor device, and can reduce the bonding speed by shortening the bonding cycle. It is an object of the present invention to provide a wire loop shape capable of realizing high speed and stable bonding characteristics, a semiconductor device having the loop shape, and a wire bonding method for forming the loop shape.

According to the first aspect of the present invention, in a loop shape of a bonding wire in which a first bonding point and a second bonding point are connected using a ball bonding capillary, a wire having a substantially L shape instead of a ball at the wire tip The bonding wire having a tail is folded once or a plurality of times at the first bonding point, and the folded bonding wire is connected to the first bonding point in a state of being vertically stacked. Is.

The invention according to claim 2 is the loop shape of the bonding wire according to claim 1, wherein the bonding wire connected to the first bonding point in the state of being stacked in the vertical direction is pulled out in the horizontal or almost horizontal direction as it is, The wiring is directed toward the second bonding point.

According to a third aspect of the present invention, in a semiconductor device in which a pad of a semiconductor chip mounted on a lead frame and a lead of the lead frame are connected by a bonding wire using a ball bonding capillary , a ball is replaced at the tip of the wire. The bonding wire having a substantially L-shaped wire tail is folded once or a plurality of times at the first bonding point, and the folded bonding wire is stacked in the vertical direction on the pad as the first bonding point. It is characterized by being connected .

According to a fourth aspect of the present invention, in the semiconductor device according to the third aspect, the bonding wire connected to the first bonding point in the state of being stacked in the vertical direction is pulled out in the horizontal or substantially horizontal direction as it is, and the second bonding is performed. The wiring is directed toward the dotted lead.

  According to a fifth aspect of the present invention, in the semiconductor device according to the fourth aspect, the pad has a plurality of pairs of pads and leads, and the plurality of pairs of pads and leads are arranged in a straight line in plan view. Each wire drawn horizontally or substantially horizontally from the wire is drawn to the left and right in a plan view, and is routed to the corresponding lead position while bypassing the other wires.

According to a sixth aspect of the present invention, in a method of wire bonding between a first bonding point and a second bonding point using a ball bonding capillary, a substantially L-shaped wire tail formed at a wire tip is first bonded. A first bonding step for bonding to a point, and loop control while feeding out the bonding wire bonded to the first bonding point, and then turning back once or a plurality of times. Wire folding process to fix in a fixed position by crushing or bonding in the stacked state, and loop control while feeding the bonding wires stacked in the vertical direction to the second bonding point. Is pulled out almost horizontally and bonded to the second bonding point, and the bonding wire bonded to the second bonding point is looped out while being pulled out to form a substantially L-shape at the tip of the bonding wire. And a wire tail forming step of forming a wire tail.

According to a seventh aspect of the present invention, in the wire bonding method according to the sixth aspect , in the wire tail forming step, the capillary is freely moved in a three-dimensional direction with reference to a line connecting the first bonding point and the second bonding point. By doing so, the direction of the horizontal portion of the substantially L-shaped wire tail formed at the tip of the wire is freely controlled.

The invention described in claim 8 is a wire bonding method characterized by performing stitch bonding using the wire bonding method described in claim 6 or 7 .

According to the first and third aspects of the present invention, the bonding wire in which a wire tail having a substantially L shape instead of the ball is formed at the tip of the wire is folded once or a plurality of times at the first bonding point, and then folded. since a bonding wire is connected to a first bonding point in a state of being stacked in the vertical direction, connecting between the first bonding point and a second bonding point without forming a ball by spark wire tip This eliminates the need for a processing step for forming a ball, shortens one cycle time of the bonding operation, and increases the bonding speed.

According to the second and fourth aspects of the present invention, the wire which is folded once or a plurality of times and stacked in the vertical direction on the pad which is the first bonding point is drawn out in the horizontal or substantially horizontal direction. Accordingly, the drawing position of the wire can be raised, and the height of the neck portion can be made as low as possible while ensuring the gap dimension between the wire and the first bonding point (pad). For this reason, it is possible to reduce the size and thickness of the semiconductor device. Furthermore, despite the fact that the neck height can be made as low as possible, there is no case where the wire is bent to a right angle or an angle close thereto at the first bonding point (pad) as in the prior art. Stable bonding characteristics can be realized while maintaining the expected electrical and mechanical characteristics.

According to the fifth aspect of the present invention, the wiring from the pads each wire pulled out in a horizontal or substantially horizontal direction is issued can pull are distributed to the left and right in a plan view, to a read position corresponding with bypassing the other wire Therefore, even in a semiconductor device in which a plurality of pairs of pads and leads are arranged in a straight line, a plurality of wires can be reliably wired without contacting each other.

According to the sixth aspect of the present invention, the wire bonded to the first bonding point is folded once or a plurality of times, and the one or a plurality of folded wires are crushed or bonded in a stacked state in the vertical direction. Then, it is pulled out horizontally or almost horizontally toward the second bonding point and bonded to the second bonding point, so that the first gap is secured while ensuring a gap between the wire and the semiconductor chip surface. The neck height at the bonding point can be made as low as possible. For this reason, it can contribute to size reduction and thickness reduction of a semiconductor device.

Moreover, does not require a ball to the wire tip as in conventional bonding method, the process steps for forming a ball is unnecessary, it is possible to shorten the cycle time correspondingly bonderizing I ing operation, bonding The speed can be increased. Further, by changing the number of turns, the vertical stacking height (neck height) of the wire at the pad as the first bonding point can be changed, so that the size and thickness of the semiconductor chip mounted on the lead frame can be changed. The height of the neck portion of the wire can be freely changed according to the distance between the pad position and the lead, etc., and bonding can be performed with the optimum neck portion height for the semiconductor device.

According to the seventh aspect of the present invention, since the orientation of the horizontal portion of the substantially L-shaped wire tail formed at the wire tip can be freely set, the wire tail of the wire tail according to the electrode pattern of the pad or lead and the wiring direction can be set. The orientation of the horizontal part can be freely changed, and stable and reliable bonding can be realized.

According to the eighth aspect of the present invention, the effect of the present invention described above can be realized even in a stitch bonding type semiconductor device.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A is a schematic side view showing an embodiment of a semiconductor device constructed by adopting the loop shape of the present invention. In addition, the same code | symbol was attached | subjected and shown to the part which is the same as that of a prior art example (FIG. 11), or an equivalent part.

  In the case of this embodiment, the wire 5 is bonded to the pad 2 as the first bonding point in a state of being folded twice so as to be superposed on each other, and a conventional ball is present at the tip of the wire 5. do not do. Then, the wire 5 bonded so as to be superposed on the top and bottom is pulled out in the horizontal or near horizontal direction toward the lead 4 as the second bonding point, and bonded to the lead 4 as the second bonding point. is there.

  In the case of the loop shape as described above, the wire 5 is folded so as to be superposed vertically on the pad 2 as the first bonding point, so that the drawing height in the horizontal direction is equal to the folded height. That is, the neck portion height H can be taken. For this reason, even if the bonded wire 5 is pulled out horizontally or substantially horizontally, a sufficient gap can be formed between the wire 5 and the upper surface of the semiconductor chip 1, and the wire 5 is connected to the upper surface of the semiconductor chip 1. The contact is eliminated, and the semiconductor device can be reduced in size and thickness.

  Further, the wire 5 is bonded onto the pad 2 with its tip portion laid down, and there is no need to form a ball for bonding at the wire tip as in the prior art. This eliminates the need for a processing step for forming a ball at the tip of the wire, thereby shortening one cycle time of the bonding operation and increasing the bonding speed. Further, it is not necessary to melt the wire tail by electric discharge for forming the ball, and the wire portion near the boundary with the ball is not recrystallized and becomes brittle. Furthermore, since balls that tend to vary are not used, the bonding characteristics can be stabilized.

In the example of FIG. 1 (a), an example was given in which folded wire 5 twice, folded number of wires 5 is not limited to two. FIG. 1B shows an example where the number of times of folding is four. Thus, by changing the number of times the wire is folded, the stacking height of the wires 5 can be changed, and the neck portion height H of the wire 5 to be pulled out can be freely adjusted.

  In the case of the example of FIGS. 1A and 1B, since the lead 4 as the second bonding point is located on the right side of the pad 2, the number of turns of the wire 5 is an even number of times (for example, 2, 4, 6, etc.). ), The wire 5 after being folded is preferably pulled out in the direction of the lead 4 as the second bonding point as shown in FIGS. 1 (a) and 1 (b). In the case of an odd number of times (for example, 1, 3, 5, etc.), the wire 5 after being folded is preferably drawn out in the direction opposite to the lead 4 as the second bonding point.

  On the other hand, in FIG. 1A and FIG. 1B, when the lead 4 as the second bonding point is located on the left side of the pad 2, the number of turns of the wire 5 is an odd number (for example, 1, 3, 5). Etc.) If the number of turns of the wire 5 is set to an odd number, the folded wire 5 can be pulled out as it is in the left direction of FIGS. 1 (a) and 1 (b), and is smooth with respect to the lead on the left side of the figure. Wiring can be performed. As described above, the number of times the wire is folded varies depending on the positional relationship between the lead and pad of the semiconductor device to be bonded and the wiring direction of the wire.

As an example of a semiconductor device that is folded back oddly, for example, as shown in FIG. 5A, a pair of pads 2 and leads 4 that are located on a semiconductor chip 1 molded by a resin 13 are connected to the chip. LOC (Lead On Chip) in which one pair is arranged at the left and right positions, and the paired pads 2 and leads 4 are bonded by wires 5, respectively, as shown in FIG. A plurality of pads 2 are arranged in a line on the upper surface of the semiconductor chip, and the leads 4 corresponding to the pads 2 are alternately arranged on the left and right sides of the semiconductor chip 1 so that the pads 2 and the leads 4 between the pairs are arranged. The semiconductor device etc. which were made to bond by the wire 5 by right and left alternately can be mentioned.

The loop shape of the present invention described above can be realized by a wire bonding method as shown in FIG.
The wire bonding method shown in FIG. 2 includes a first bonding step (FIGS. 2A and 2B) for bonding a wire tail 5e having a substantially L shape at the tip of the wire to a pad 2 as a first bonding point, and a first bonding point. A wire folding step of looping a plurality of wires 5 that are bonded to each other by loop-controlling them, and crushing the wires 5 that have been folded back and stacked in a vertical direction or fixing them in a fixed position by bonding. (FIGS. 2 (c) to (g)), and by controlling the loop of the wires 5 stacked in the vertical direction while drawing them out, they are pulled out horizontally or almost horizontally toward the second bonding point, and lead as the second bonding point. 2nd bonding process (FIG.2 (h)-) which bonds to 4 k)) and a wire tail forming step of forming a wire tail 5e having a substantially L shape at the tip of the wire 5 by controlling the loop while feeding the wire 5 bonded to the second bonding point (FIG. 2 (l)) To (n)).

Hereinafter, the wire bonding method of FIG. 2 will be described in detail.
1. First bonding process (FIGS. 2A and 2B)
As shown in FIG. 2 (a), the bonding capillary 6 descends toward the pad 2, the wire tail 5e having a substantially L-shape formed at the distal end of the wire 5 to the first bonding point serving pad 2 (FIG. 2B).

  The wire tail 5e having a substantially L shape is formed by a wire tail forming process shown in FIGS. 2 (l) to (n), which will be described later, at the time of bonding at the previous location. The wire tail 5e does not exist at the time of the initial bonding of the apparatus, but dummy bonding may be performed in advance prior to the start of bonding.

2. Wire folding process (FIGS. 2 (c) to (g))
Next, as shown in FIG. 2 (c), the capillary 6 is raised to the point A, the wire 5 is fed out for a predetermined length, and then reverse to the point B as shown in FIG. 2 (d). Further, as shown in FIG. 2 (e), after the capillary 6 is raised to the point C, it is lowered toward the wire 5 bonded to the pad 2 as shown in FIG. 2 (f). As a result, the wire 5 is folded twice. Then, as shown in FIG. 2 (g), the wires 5 folded up and down and folded up and down are crushed from above or bonded to fix the wires 5 stacked up and down in place, Prevent mold loss.

  FIG. 2 shows a case where the wire 5 is folded twice to form the loop shape of FIG. 1A, but if the above folding operation is repeated twice, the loop shape of FIG. 1B is obtained. In the case of the odd-numbered diffraction, when the wire 5 is in the folded state of FIG. 2 (d), the folding of FIG. 2 (f) may be omitted and the operation of FIG.

3. Second bonding step (FIGS. 2 (h) to (k))
Next, as shown in FIG. 2 (h), the capillary 6 is raised to the point D, the wire 5 is fed out for a predetermined length, and then reverse to the point E as shown in FIG. 2 (i). Thereby, the wire 5 becomes a shape inclined to the point E. The portion extended to the point E becomes a horizontal portion L in FIG.

  Next, as shown in FIG. 2 (j), the capillary 6 is raised to point F, and the wire 5 is fed out by a predetermined length. As a result, the E point portion of the wire 5 has a flange 5b having a predetermined angle. A portion from the flange 5b to the point F is an inclined portion S in FIG.

  Next, as shown in FIG. 2 (k), the capillary 6 is lowered toward the lead 4 as the second bonding point, and the wire 5 is bonded to the lead 4 as the second bonding point.

4). Wire tail formation process (FIGS. 2 (l) to (n))
When the bonding between the pad 2 and the lead 4 is completed as described above, the capillary 6 is raised to the point G as shown in FIG. The wire portion extended to the point G becomes a horizontal portion 5f of an L-shaped wire tail 5e described later.

  Next, as shown in FIG. 2 (m), the capillary 6 raised to the point G is moved obliquely downward, so that the wire 5 fed to the point G is made to follow the surface of the lead 4 again.

  In addition, when the capillary 6 moves obliquely downward in FIG. 2 (m), as shown in FIG. 3 (a), the capillary 6 is paralleled along the extending direction 11 ′ of the pad 2 ′ at the next bonding location. Or move downward in parallel along the bonding direction line 12 'connecting the pad 2' and the lead 4 'at the next bonding location, as shown in FIG. 3B. It is desirable. By performing such movement control, the orientation of the horizontal portion 5f of the wire tail 5e can be freely changed according to the electrode pattern of the pads and leads and the wiring direction, thereby realizing more reliable and accurate bonding. it can.

  Next, as shown in FIG. 2 (n), the wire clamper 8 is actuated to grasp the wire 5, and the capillary 6 is raised while the wire 5 is grasped. As a result, the wire 5 is cut so as to be shredded, and a wire tail 5e having a substantially L-shape for the next bonding is formed at the tip of the wire 5 as schematically shown in FIG. The Then, the processing operation returns to FIG. 2A again, and moves to the bonding operation of the pad 2 'and the lead 4' (see FIG. 3) at the next bonding location.

  As described above, the wire tail 5e having a substantially L shape formed at the tip of the wire 5 has the horizontal portion 5f in the same direction as the extending direction 11 ′ of the pad 2 ′ as the next bonding point, or the pad 2 ′. Since it is formed in the same direction as the bonding direction line 12 ′ that connects the leads 4 ′, bonding between the pad 2 ′, which is the next bonding location, and the lead “4” is performed in the wiring direction of the pads and the electrode pattern of the leads. It can be done smoothly.

The entire movement trajectory of the capillary 6 in the wire bonding method of FIG. 2 described above is shown by a two- dot chain line in FIG.

  In the above embodiment, when a plurality of wires 5 are folded back and stacked on the pad 2 as the first bonding point, as shown in FIG. 6A, the capillary 6 is connected to the first bonding point and the second bonding point. The movement is controlled two-dimensionally in a vertical plane passing through the connecting line mm and the wire 5 is folded along the line mm, but the method of folding the wire 5 is not limited to this, The capillary 6 may be folded back by linear movement, diagonal movement, or curved movement in any direction, up, down, left, and right, with respect to a line mm connecting the first bonding point and the second bonding point. In this way, by performing loop control while controlling the three-dimensional movement of the capillary in the up / down, left / right, and front / rear directions, for example, as shown in FIG. 6B, the capillary can be folded into an arbitrary shape such as a triangle. it can.

  Further, when forming the horizontal portion 5f of the wire tail 5e (see FIGS. 2 (l) to 2 (n)), the capillary 6 is connected to the first bonding point in addition to the two directions in FIGS. 3 (a) and 3 (b). As shown in FIG. 7, by performing loop control while moving linearly, obliquely or curvedly in any direction of up, down, left and right, front and back with reference to a line mm connecting the second bonding point and the second bonding point, The horizontal portion 5f of the wire tail 5e can be directed in an arbitrary direction.

  In the above embodiment, when the inclined portion S following the horizontal portion L is formed, only one ridge 5b is attached (see FIGS. 2 (j) and 2 (k)). As shown in FIG. 8, if two flanges 5b and 5c are attached, even if another element 13 or the like is disposed in the portion of the inclined portion S, wiring is performed while maintaining the height of the inclined portion S so as not to hit this. can do.

  For example, as shown in FIGS. 9A and 9B, even in the case of a semiconductor device in which a plurality of pairs of pads 21 to 23 and leads 41 to 43 are arranged in a straight line, the capillary 6 is Each pad 21 is controlled by performing loop control while moving linearly, obliquely or curvedly in any direction of up, down, left and right, and forward and backward with reference to a line mm connecting the first bonding point and the second bonding point. ˜23 and the wires 41 connecting the leads 41 to 43 can be distributed to the left and right and pulled out, and routed to the corresponding lead position while bypassing so as not to contact other wires.

  Furthermore, although the above embodiment has been described by taking wire bonding in a semiconductor device on which one semiconductor chip is mounted as an example, not only this but also, for example, as shown in FIGS. The present invention can also be applied to so-called stitch bonding in which the pads 2 and the leads 4 of the semiconductor device in which the semiconductor chips 1 (two in the illustrated example) are mounted to be stacked are continuously bonded.

  When performing this stitch bonding, as shown in FIG. 10 (a), it is possible to bond in a state where the wires 5 are folded back and stacked in all the pads 2, or as shown in FIG. 10 (b), Bonding can also be performed in a state where a plurality of layers are folded back and stacked only at an arbitrary pad 2 (upper pad in the illustrated example).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a semiconductor device according to the present invention, wherein (a) is a schematic side view of a semiconductor device in which a wire is folded twice and bonded, (b) is a schematic plan view thereof, and (c) is a schematic plan view thereof. It is a model enlarged view of the pad part at the time of turning the wire four times. (A)-(n) is a process-process figure of the wire bonding method for forming the loop shape shown to Fig.1 (a). It is explanatory drawing of the movement control of the capillary for wire tail formation, Comprising: (a) is an example at the time of moving in parallel along the pad of the following bonding location, (b) is the pad of the next bonding location, An example in the case of being moved parallel to the bonding direction line connecting the leads is shown. It is a model expansion explanatory drawing of wire tail formation operation. An example in which the number of times of wire folding is set to an odd number is shown. (A) is a schematic cross-sectional view showing an example in the case of LOC (lead-on-chip), and (b) is a pad in the center of the chip upper surface. It is a schematic plan view showing an example in the case of a semiconductor device in which leads are arranged in a line and alternately arranged on the left and right. (A) is a figure which shows the example at the time of folding a wire in parallel along the line which ties a 1st bonding point and a 2nd bonding point, (b) is an example at the time of folding a wire in triangle shape by planar view FIG. It is a figure which shows the example of the drawing-out direction of the horizontal part of a wire tail. It is a figure which shows the example at the time of forming two ridges in the inclination part of a wire. An example of a wire routing shape when a plurality of pads and leads are arranged in a vertical row, (a) is a schematic plan view when the wire is linearly routed, and (b) is a curve of the wire FIG. An example in the case where the bonding method of the present invention is applied to stitch bonding is shown. (A) is an example in which a plurality of wires are folded back and bonded by pads of two semiconductor chips stacked one above the other. b) shows an example in which a plurality of wires are folded back and bonded only at the pads of the upper semiconductor chip. The example of the loop shape of the conventional semiconductor device is shown, (a) shows the example in case a loop shape is trapezoid shape, (b) shows the example in case a loop shape is a triangle shape. (A)-(k) is a process flowchart of the bonding method for forming the trapezoidal loop of Fig.11 (a). (A)-(j) is a process flowchart of the bonding method for forming the triangular loop of FIG.11 (b). (A) is a figure which shows the example of a loop shape at the time of bending and pulling out the wire horizontally from the top of the bonded ball | bowl, (b) is a loop shape at the time of bonding in the state which laid the wire directly on the pad. It is a figure which shows the example of.

Explanation of symbols

1, 1 'semiconductor chip 2 pad (first bonding point)
2 'Pad for next bonding point 3 Lead frame 4 Lead (second bonding point)
4 'Lead at next bonding location 5 Bonding wire 5e Wire tail 5f Horizontal portion of wire tail 6 Capillary for ball bonding 7 Ball 8 Wire clamper

Claims (8)

In the loop shape of the bonding wire connecting the first bonding point and the second bonding point using a ball bonding capillary,
A bonding wire in which a wire tail having a substantially L shape instead of a ball is formed at the tip of the wire is folded once or a plurality of times at the first bonding point, and the folded bonding wires are stacked in the vertical direction. A bonding wire loop shape characterized by being connected to one bonding point . In the loop shape of the bonding wire according to claim 1,
A bonding wire loop in which the bonding wires connected to the first bonding point in the state of being stacked in the vertical direction are pulled out in the horizontal or substantially horizontal direction as they are and are wired toward the second bonding point. shape. In a semiconductor device in which a pad of a semiconductor chip mounted on a lead frame and a lead of a lead frame are connected by a bonding wire using a ball bonding capillary,
A bonding wire in which a wire tail having a substantially L shape instead of a ball is formed at the tip of the wire is folded once or a plurality of times at the first bonding point, and the folded bonding wires are stacked in the vertical direction. A semiconductor device connected to a pad as one bonding point . The semiconductor device according to claim 3.
The semiconductor device wherein the bonding wires connected to the first bonding point in the state of being stacked in the vertical direction are pulled out in the horizontal or substantially horizontal direction as they are and are wired toward the lead as the second bonding point. . The semiconductor device according to claim 4.
There are a plurality of pairs of pads and leads, and the plurality of pairs of pads and leads are arranged in a straight line in a plan view, and each bonding wire drawn from each pad in a horizontal or substantially horizontal direction is seen in a plan view. issued can pull by distributing the right and left, the semiconductor device characterized in that it is wired to the lead position corresponding with bypassing the other bonding wires. In a method of wire bonding between a first bonding point and a second bonding point using a ball bonding capillary,
A first bonding step of bonding a substantially L-shaped wire tail formed at the wire tip to a first bonding point;
Loop control is performed once or more times while looping the bonding wire bonded to the first bonding point, and the bonding wires that are returned once or more than once are crushed or bonded in a state where they are stacked vertically. Wire folding process to fix in place by,
A second bonding step in which the bonding wires stacked in the vertical direction are pulled out horizontally or substantially horizontally toward the second bonding point by performing loop control while being drawn out, and bonded to the second bonding point;
A wire tail forming step of forming a wire tail having a substantially L shape at the tip of the bonding wire by loop-controlling and pulling up the bonding wire bonded to the second bonding point. Bonding method. The wire bonding method according to claim 6 , wherein
In the wire tail forming step, the capillary is moved and controlled freely in a three-dimensional direction with reference to a line connecting the first bonding point and the second bonding point, so that a wire tail having a substantially L shape formed at the tip of the wire is formed. A wire bonding method characterized by freely controlling the orientation of a horizontal portion. A wire bonding method, wherein stitch bonding is performed using the wire bonding method according to claim 6 .

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