CN212380392U

CN212380392U - Material taking device and die bonder

Info

Publication number: CN212380392U
Application number: CN202021157351.0U
Authority: CN
Inventors: 王泉泉; 黄远南; 彭宇
Original assignee: Shenzhen Sunson Intelligent Equipment Co ltd
Current assignee: Shenzhen Shengshi Intelligent Equipment Co ltd
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-01-19
Anticipated expiration: 2030-06-19

Abstract

The utility model discloses a extracting device and solid brilliant machine, include: a drive device; the parallelism adjusting device comprises a first mounting plate and a second mounting plate, the first mounting plate is fixed on the output end of the driving device, a reference surface is arranged on the first mounting plate, an adjusting surface is arranged on the second mounting plate, and the parallelism of the adjusting surface relative to the reference surface is adjustable; the material taking head is arranged on the second mounting plate, the material taking head can absorb or release materials, and the driving device can drive the material taking head to be close to or far away from a carrier for attaching and releasing the materials; pressure sensor, pressure sensor set up on the second mounting panel, and pressure sensor can detect and get the stub bar and paste the material and put in power on the carrier. The utility model discloses when the depth of parallelism between the installation face of adjustment wafer and carrier, be difficult to damage pressure sensor.

Description

Material taking device and die bonder

Technical Field

The utility model belongs to the technical field of solid brilliant and specifically relates to a extracting device and solid brilliant machine is related to.

Background

The semiconductor packaging refers to a process of processing a wafer passing a test according to a product model and a functional requirement to obtain an independent chip. The specific packaging process is as follows: cutting the wafer into small chips by a scribing process, then pasting the cut chips on corresponding islands of a substrate frame by glue, and connecting bonding pads of the chips to corresponding pins of the substrate by using superfine metal wires or conductive resin to form a required circuit; and then packaging and protecting the independent wafer by using a plastic shell, and after plastic packaging, carrying out inspection, testing, packaging and other procedures to finish packaging.

The material taking device is a core component of the die bonder, and has the function of sucking up the cut and separated die on the die, placing the die on a carrier (such as a lead frame, a PCB (printed circuit board), and adhering or welding the die. In the wafer bonding process, the wafer needs to be aligned with the mounting surface of the carrier and then attached, so that the wafer is prevented from being inclined, and the wafer is not firmly attached to the carrier. Meanwhile, the acting force between the wafer and the carrier is controlled by arranging a pressure sensor. However, when the parallelism between the wafer and the mounting surface of the carrier is adjusted, the force is sometimes excessive, and the pressure sensor is likely to be damaged.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. Therefore, the utility model provides a material taking device is difficult to damage pressure sensor when adjusting the depth of parallelism between the installation face of wafer and carrier.

The utility model also provides a solid brilliant machine.

In a first aspect, an embodiment of the present invention provides a material taking device, including: a drive device; the parallelism adjusting device comprises a first mounting plate and a second mounting plate, the first mounting plate is fixed on the output end of the driving device, a reference surface is arranged on the first mounting plate, an adjusting surface is arranged on the second mounting plate, and the parallelism of the adjusting surface relative to the reference surface is adjustable; the material taking head is arranged on the second mounting plate, the material taking head can absorb or release materials, and the driving device can drive the material taking head to be close to or far away from a carrier for attaching and releasing the materials; pressure sensor, pressure sensor sets up on the second mounting panel, pressure sensor can detect it pastes the material and puts to get the stub bar the power on the carrier.

The utility model discloses extracting device has following beneficial effect at least: the pressure sensor is arranged on the second mounting plate, the parallelism adjusting device comprises a first mounting plate and a second mounting plate, the first mounting plate is provided with a reference surface, and the second mounting plate is provided with an adjusting surface; when the depth of parallelism of the relative reference surface of adjustment face, with the relative first mounting panel of second mounting panel rotatory can, compare in the structure that traditional pressure sensor is connected with drive arrangement's output, first mounting panel respectively, pressure sensor is difficult to receive and pulls or extrude, therefore is difficult to damage.

According to the utility model discloses a material taking device of other embodiments, it is the suction nozzle to get the stub bar, the suction nozzle can communicate with the negative pressure air supply.

According to the utility model discloses a material taking device of other embodiments, pressure sensor draws pressure sensor for the S type, the S type draw pressure sensor ' S one end with second mounting panel fixed connection, the S type draw pressure sensor ' S the other end with suction nozzle fixed connection, the axle center of suction nozzle with the S type draws pressure sensor ' S center is located the coplanar.

According to the utility model discloses a extracting device of other embodiments, parallelism adjusting device still includes ball, first elastic element and holding screw, the ball centre gripping is in between first mounting panel and the second mounting panel, the second mounting panel can wind the ball rotates, first elastic element can give one of second mounting panel is close to the effort of first mounting panel, holding screw and first mounting panel threaded connection, holding screw's one end supports with the second mounting panel and holds.

According to the utility model discloses a extracting device of other embodiments, first elastic element is first extension spring, first extension spring's one end with first mounting panel supports and holds, first extension spring's the other end with the second mounting panel supports and holds.

According to other embodiments of the utility model discloses a extracting device, extracting device still includes second elastic element, second elastic element can give one direction of drive arrangement's output and the opposite direction's of gravity effort of drive arrangement's output.

In a second aspect, an embodiment of the present invention provides a die bonder, including the above material fetching device.

The utility model discloses solid brilliant machine has following beneficial effect at least: through using foretell extracting device, can avoid the damage of pressure sensor because of the regulation of depth of parallelism leads to, pressure sensor long service life, the cost of maintenance of solid brilliant machine is low.

According to the utility model discloses a solid brilliant machine of other embodiments, gu brilliant machine still includes the fixing base, drive arrangement is voice coil motor, voice coil motor includes mounting bracket, coil and magnet, be provided with the storage tank on the mounting bracket, the coil is fixed in the storage tank, magnet is fixed on the fixing base.

According to the utility model discloses a solid brilliant machine of other embodiments, extracting device is provided with two and more, belongs to two respectively and more voice coil motor the mounting bracket sets up side by side on the fixing base, magnet spanes and belongs to two respectively and more voice coil motor on the coil.

According to the utility model discloses a solid brilliant machine of other embodiments, the coil is provided with two and more.

Drawings

Fig. 1 is an isometric view of a die bonder of a first embodiment;

FIG. 2 is a right side view of the die bonder of FIG. 1;

FIG. 3 is an exploded view of a portion of the die bonder of FIG. 1;

FIG. 4 is a top view of the die bonder of FIG. 1;

fig. 5 is a sectional view taken along a-a in fig. 4.

Detailed Description

The conception and the resulting technical effects of the present invention will be described clearly and completely with reference to the following embodiments, so that the objects, features and effects of the present invention can be fully understood. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive labor based on the embodiments of the present invention all belong to the protection scope of the present invention.

In the description of the embodiments of the present invention, if an orientation description is referred to, for example, the directions or positional relationships indicated by "upper", "lower", "front", "rear", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, only for convenience of description and simplification of description, but not for indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

In the description of the embodiments of the present invention, if a feature is referred to as being "disposed", "fixed", "connected", or "mounted" on another feature, it can be directly disposed, fixed, or connected to the other feature or indirectly disposed, fixed, connected, or mounted on the other feature. In the description of the embodiments of the present invention, if "a plurality" is referred to, it means one or more, if "a plurality" is referred to, it means two or more, if "greater than", "less than" or "more than" is referred to, it is understood that the number is not included, and if "more than", "less than" or "within" is referred to, it is understood that the number is included. If reference is made to "first" or "second", this should be understood to distinguish between features and not to indicate or imply relative importance or to implicitly indicate the number of indicated features or to implicitly indicate the precedence of the indicated features.

Referring to fig. 1 to 3, fig. 1 is an isometric view of a die bonder in accordance with an embodiment of the present invention, fig. 2 is a right side view of the die bonder in fig. 1, and fig. 3 is a partial exploded view of the die bonder in fig. 1. The die bonder of this embodiment includes frame 100 and extracting device 200, and frame 100 includes fixing base 110, connecting plate 120 and third mounting panel 130, and fixing base 110 and third mounting panel 130 are listed as the interval and set up, and the upper end of fixing base 110 passes through screw locking with the rear end of connecting plate 120 fixedly, and the upper end of third mounting panel 130 passes through screw locking with the front end of connecting plate 120 fixedly. The material taking device 200 comprises a sliding assembly 210, a driving device 220, a parallelism adjusting device 230, a pressure sensor 240, a mounting seat 250, a material taking head, a grating scale 270, a photoelectric sensor assembly 280 and a second elastic element.

The material taking head is arranged at the output end of the driving device 220 through the parallelism adjusting device 230, the material taking head can absorb or release the chip, and under the action of the driving device 220, the material taking head can move along the up-and-down direction, so that the wafer is far away after the chip is taken, and the taken chip is attached to the carrier. The parallelism adjusting device 230 can adjust the parallelism between the wafer and the mounting surface of the carrier, so that the wafer is attached to the carrier in a posture parallel to the mounting surface of the carrier, and the wafer is prevented from being skewed. The pressure sensor 240 can detect the force of the material taking head for attaching the wafer to the carrier, and when the pressure sensor 240 detects a predetermined pressure value, the material taking head stops approaching the carrier, so that the wafer is prevented from being attached firmly or the attaching force is prevented from being too large.

Specifically, the driving device 220 is a voice coil motor, and the voice coil motor includes a mounting bracket 221, a coil 222, and a magnet 223. The sliding assembly 210 includes a sliding block and a sliding rail, the sliding rail is locked and fixed on the front side surface of the fixing base 110, the sliding block is slidably connected with the sliding rail, and the sliding block is locked and fixed on the rear side surface of the mounting frame 221, so that the mounting frame 221 can slide in the up-down direction relative to the fixing base 110. The mounting bracket 221 is provided with a receiving groove 225, and the coil 222 is fixed in the receiving groove 225 by using glue or by caulking. The magnet 223 is fixed on the frame 100, and the material taking head is arranged on the mounting frame 221. Thus, when the coil 222 is energized, the coil 222 will generate a magnetic field, and the magnetic field generated by the coil 222 interacts with the magnetic field of the magnet 223, so that the coil 222 carries the mounting bracket 221 to move upwards or downwards, i.e. the pick-up head can move in the up-and-down direction.

In order to improve the working efficiency of the die bonder and save the installation space of the die bonder, two material taking devices 200 are provided. The two material taking devices 200 are disposed at the front side of the fixing base 110, and the two material taking devices 200 are distributed along the left-right direction, and the magnet 223 spans over the coils 222 belonging to the two voice coil motors, respectively. Through the design, the coils 222 which respectively belong to the two voice coil motors are arranged in the magnetic field of one magnet 223, so that the installation space is saved while the two material taking heads are independently driven.

In this embodiment, four magnets 223 are provided, two of which are fixed to the fixing base 110 and the other two of which are fixed to the third mounting plate 130, and the coils 222 belonging to the two voice coil motors, respectively, are located between the magnets 223 which are oppositely disposed.

In this embodiment, a single voice coil motor is provided with two coils 222, and both coils 222 generate magnetic fields when energized, and the generated magnetic fields interact with the magnetic field of the magnet 223, thereby providing greater power to the pick-up head.

Because the magnet 223 and the coil 222 are both rectangular and regular in shape, in another embodiment, when more material taking heads need to be driven, the magnet 223 is lengthened, and one or more groups of mounting frames 221, coils 222 and material taking heads are added, so that independent driving of the plurality of material taking heads can be realized.

In this embodiment, the two material taking heads are all of the same specification, so that the die bonder can take two wafers at one time and attach the two wafers to the carrier at one time. In other embodiments, the material taking heads can be of different types, so that when different chips are pasted, a plurality of die bonder do not need to be manufactured, die bonding efficiency can be improved, and manufacturing cost is reduced.

In other embodiments, the driving device 220 may also select a rod motor.

Referring to fig. 3, 4 and 5, fig. 4 is a top view of the die bonder of fig. 1, and fig. 5 is a sectional view taken along a-a section of fig. 4. The parallelism adjusting means 230 includes a first mounting plate 231, a set screw 232, a ball 233, a first elastic member, a second mounting plate 235, and a cross bar 236. The rear end of the first mounting plate 231 is fixed at the lower end of the mounting frame 221 through screw locking, the second mounting plate 235 is located below the first mounting plate 231, and the second mounting plate 235 and the first mounting plate 231 are arranged at intervals in parallel. The balls 233 are interposed between the first and

second mounting plates

231 and 235, and by providing the set screw 232, the first elastic member, and the cross bar 236, the balls 233 are sandwiched between the first and

second mounting plates

231 and 235, and the second mounting plate 235 can rotate about the center of the balls 233.

The upper surface of first mounting panel 231 is the reference surface (can also take the lower surface of first mounting panel 231 as the reference surface), and the lower surface of second mounting panel 235 is the regulation face, gets the material head and installs on the regulation face. Thus, by rotating the second mounting plate 235 about the center of the ball 233, the adjustment surface can be rotated relative to the reference surface, thereby adjusting the angle of the wafer picked up by the pick-up head relative to the mounting surface of the carrier.

Specifically, in order to mount the balls 233 between the first mounting plate 231 and the second mounting plate 235, the first mounting plate 231 is provided with a first hole 313 in the up-down direction, the second mounting plate 235 is provided with a second hole 314 in the up-down direction, and the first hole 313 and the second hole 314 are coaxially disposed. After the first and second mounting

plates

231 and 235 are brought together, a portion of the balls 233 are disposed in the first holes 313 and another portion of the balls 233 are disposed in the second holes 314, thereby clamping the balls 233 between the first and second mounting

plates

231 and 235.

By controlling the diameter of the balls 233, or alternatively the diameter of the first holes 313 and/or the diameter of the second holes 314, the clearance between the first mounting plate 231 and the second mounting plate 235 can be adjusted, thereby adjusting the desired maximum angle of rotation of the first mounting plate 231 relative to the second mounting plate 235.

In further embodiments, the first hole 313 and/or the second hole 314 may be replaced with an arc-shaped slot, which may also enable a clamping mounting of the ball 233.

The first elastic element is a first extension spring 234. Still be provided with first ladder hole 312 on the first mounting panel 231, first ladder hole 312 has run through first mounting panel 231, still is provided with second ladder hole 315 on the second mounting panel 235, and second ladder hole 315 has run through second mounting panel 235, and first ladder hole 312 and the coaxial setting of second ladder hole 315. The upper end of the first extension spring 234 is disposed in the first stepped hole 312, the lower end of the first extension spring 234 is disposed in the second stepped hole 315, the upper end of the first extension spring 234 abuts against a stepped surface of the first stepped hole 312 through one cross rod 236 (the upper end of the first extension spring 234 is provided with a hook which abuts against the cross rod 236), and the lower end of the first extension spring 234 abuts against a stepped surface of the second stepped hole 315 through the other cross rod 236. Thus, the first extension spring 234 imparts a force to the second mounting plate 235 that approaches the first mounting plate 231, and the first extension spring 234 constrains the first and second mounting

plates

231, 235 together so that the first and second mounting

plates

231, 235 do not become detached inadvertently.

The first mounting plate 231 is further provided with a threaded hole 311 along the vertical direction, the axial center of the threaded hole 311, the axial center of the first stepped hole 312, and the axial center of the first hole 313 are located on the same plane, and the threaded hole 311 and the first hole 313 are located on both sides of the first stepped hole 312, respectively. The set screw 232 is screwed into the threaded hole 311, and the lower end of the set screw 232 abuts against the second mounting plate 235. By rotating the lower end of the set screw 232 out of the threaded hole 311, the point of the second mounting plate 235 that abuts the set screw 232 can be moved away from the first mounting plate 231, and by rotating the lower end of the set screw 232 into the threaded hole 311, the point of the second mounting plate 235 that abuts the set screw 232 will be moved closer to the first mounting plate 231.

The set screws 232 and the first extension springs 234 are provided in two sets, the axis of one set of set screws 232 and the center of the ball 233 are located on the upper, lower, left and right planes, and the axis of the other set of set screws 232 and the center of the ball 233 are located on the upper, lower, front and rear planes, which are perpendicular to each other. Thus, by controlling the two set screws 232, the second mounting plate 235 can be rotated about an axis in the front-rear direction and about an axis in the left-right direction. Get the stub bar and set up on second mounting panel 235, can adjust the depth of parallelism between the installation face of the wafer that gets the stub bar and absorb and the carrier from this for the wafer gets more firm with the carrier laminating, and the yields of solid crystal is high.

In this embodiment, the material taking head is a suction nozzle 260, and the material of the suction nozzle 260 is rubber, bakelite, ceramic or tungsten steel. The suction nozzle 260 is in communication with a source of negative pressure gas to suck the wafer, and when the negative pressure in the suction nozzle 260 is removed, the wafer is released. The suction nozzle 260 is secured to the mounting plate 250 by a screw and nut clamp, and the mounting plate 250 is mounted on the second mounting plate 235.

In other embodiments, the first elastic element may also be a bellows, which is mounted in the same manner as the first tension spring 234 and functions in the same manner.

To detect the force with which the suction nozzle 260 applies the wafer to the carrier, a pressure sensor 240 is provided, and the pressure sensor 240 is selected as an S-shaped pull pressure sensor. The upper end of the S-shaped pull pressure sensor is fixedly connected with the second mounting plate 235, and the lower end of the S-shaped pull pressure sensor is fixedly connected with the mounting base 250. The S-shaped pull pressure sensor can detect the pressure or pull force between the second mounting plate 235 and the mounting seat 250, and since the suction nozzle 260 is fixed on the mounting seat 250, when the force of the wafer on the carrier is calculated, the gravity of the suction nozzle 260 and the mounting seat 250 is also considered, and the force of the wafer on the carrier is obtained by calculating the moment balance of the suction nozzle 260 and the mounting seat 250 as a whole.

By providing the pressure sensor 240, the force with which the wafer is placed on the carrier can be detected in real time. When the bonding force reaches a predetermined target interval, the voice coil motor is controlled to stop the suction nozzle 260 from approaching the carrier, thereby preventing the wafer or the carrier from being damaged or preventing the wafer from being not bonded due to insufficient bonding force.

Compared with the structure that the S-shaped pulling and pressing force sensor is installed between the installation frame 221 and the first installation plate 231, the S-shaped pulling and pressing force sensor is arranged between the second installation plate 235 and the installation seat 250, so that the S-shaped pulling and pressing force sensor can be prevented from being pulled or extruded when the spatial angle of the second installation plate 235 relative to the first installation plate 231 is adjusted (namely, the parallelism of the adjusting surface relative to the reference surface is adjusted). If the S-shaped pull pressure sensor is subjected to overlarge stress, the range is easily exceeded, and the S-shaped pull pressure sensor is damaged. Therefore, the service life of the S-shaped pull pressure sensor can be prolonged, and the maintenance cost is reduced.

For the convenience of the S-shaped pull pressure sensor to detect the force of the suction nozzle 260 attaching to the wafer, the axis of the suction nozzle 260 and the center of the S-shaped pull pressure sensor are both located on the upper, lower, front and rear planes, at this time, the detection is more direct, and the calculation of the moment is simpler.

In further embodiments, the pressure sensor 240 may also use a ceramic pressure sensor or a diffused silicon pressure sensor.

To reduce the burden on the voice coil motor, a second elastic member is provided, and the second elastic member can give an upward force to the mounting bracket 221. In this embodiment, the second elastic element is a second extension spring 290, an upper end of the second extension spring 290 is fixed on the fixing base 110 (a hook is disposed at an upper end of the second extension spring 290, and the hook is hung on the fixing base 110), and a lower end of the second extension spring 290 is fixed on the mounting bracket 221 (the fixing is achieved by the hook at a lower end of the second extension spring 290). The second extension spring 290 gives an upward force to the mounting bracket 221, which counteracts the weight of the mounting bracket 221 itself and the weight of the load fixed to the mounting bracket 221, thereby reducing the load of the voice coil motor and saving energy.

In another embodiment, the second elastic element may also be a compression spring, in which case, the lower end of the compression spring abuts against the fixing base 110, the upper end of the compression spring abuts against the mounting bracket 221, and when the mounting bracket 221 moves downward, the compression spring is compressed, so as to provide an upward acting force to the mounting bracket 221, which counteracts the gravity of the mounting bracket 221 and the gravity of the debt fixed on the mounting bracket 221.

For detecting the displacement of the suction nozzle 260, the material taking device is provided with a grating scale 270. The grating scale 270 includes a scale grating fixed on the mounting frame 221 and a grating reading head fixed on the third mounting plate 130, and when the scale grating moves along with the mounting frame 221, the grating reading head can read a corresponding displacement. By arranging the grating scale 270, the displacement, the speed and the acceleration of the suction nozzle 260 can be detected in time and utilized. For example, when the suction nozzle 260 starts to move toward the carrier, the power of the voice coil motor may be increased so that the suction nozzle 260 moves rapidly, and when the suction nozzle 260 has approached the carrier, the suction nozzle 260 may be decelerated in advance in preparation for die bonding.

To detect whether the suction nozzle 260 is moved up in place, a photo sensor assembly 280 is provided. The photo sensor assembly 280 includes a light shielding sheet 281 and a photo sensor 282, the light shielding sheet 281 is fixed on the mounting bracket 221, and the photo sensor 282 is fixed on the third mounting plate 130. When the suction nozzle 260 moves upward to a proper position, the light shielding sheet 281 triggers the photoelectric sensor 282, and it can be determined that the suction nozzle 260 has picked up the wafer or the suction nozzle 260 has attached the wafer.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.

Claims

1. A material extracting apparatus, comprising:

a drive device;

the parallelism adjusting device comprises a first mounting plate and a second mounting plate, the first mounting plate is fixed on the output end of the driving device, a reference surface is arranged on the first mounting plate, an adjusting surface is arranged on the second mounting plate, and the parallelism of the adjusting surface relative to the reference surface is adjustable;

the material taking head is arranged on the second mounting plate, the material taking head can absorb or release materials, and the driving device can drive the material taking head to be close to or far away from a carrier for attaching and releasing the materials;

pressure sensor, pressure sensor sets up on the second mounting panel, pressure sensor can detect it pastes the material and puts to get the stub bar the power on the carrier.

2. The take off device as claimed in claim 1, wherein the take off head is a suction nozzle capable of communicating with a source of negative pressure air.

3. The material taking device according to claim 2, wherein the pressure sensor is an S-shaped pulling pressure sensor, one end of the S-shaped pulling pressure sensor is fixedly connected with the second mounting plate, the other end of the S-shaped pulling pressure sensor is fixedly connected with the suction nozzle, and the axis of the suction nozzle and the center of the S-shaped pulling pressure sensor are located on the same plane.

4. The reclaiming apparatus as claimed in claim 1 wherein said parallelism adjustment apparatus further comprises a ball, a first resilient member and a set screw, said ball being retained between said first mounting plate and said second mounting plate, said second mounting plate being rotatable about said ball, said first resilient member being capable of imparting a force to said second mounting plate that is closer to said first mounting plate, said set screw being threadably coupled to said first mounting plate, one end of said set screw abutting said second mounting plate.

5. The reclaiming apparatus as claimed in claim 4 wherein said first resilient member is a first extension spring, one end of said first extension spring abuts against said first mounting plate, and the other end of said first extension spring abuts against said second mounting plate.

6. The extracting apparatus as set forth in claim 1, further comprising a second resilient member capable of imparting a force to the output end of the drive apparatus in a direction opposite to the direction of gravity at the output end of the drive apparatus.

7. A die bonder, characterized by comprising the material taking device as claimed in any one of claims 1 to 6.

8. The die bonder of claim 7, further comprising a fixing base, wherein the driving device is a voice coil motor, the voice coil motor comprises a mounting frame, a coil and a magnet, the mounting frame is provided with a receiving groove, the coil is fixed in the receiving groove, and the magnet is fixed on the fixing base.

9. The die bonder of claim 8, wherein the material taking device is provided with two or more than two, the mounting frames respectively belonging to the two or more than two voice coil motors are arranged on the fixing base in parallel, and the magnets cross over the coils respectively belonging to the two or more than two voice coil motors.

10. The die bonder of claim 8, wherein two or more coils are provided.