Method to produce a transponder

A method to produce a transponder comprises the steps of positioning a coil comprising at least one coil end in a predetermined coil position and holding all of said coil ends in a respective holding position, and holding a chip comprising at least one contact pad in a chip fixture so that all of said coil ends of the coil that should be bonded to said chip are located on one side of corresponding contact pads of the chip, and bonding of the coil ends to the contact pads.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of European Patent Application No. 03 009 450.2, filed on Apr. 25, 2003, the subject matter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a method and a device for producing a transponder, and to a transponder itself that comprises an integrated circuit chip and a coil, wherein the chip and the winding of the coil are positioned approximately in the same plane.

Certain problems are appearing at the time of making such components, caused mainly by the small dimensions of the transponder, the coil, and the integrated circuit chip or the encapsulated integrated circuit die. Normally, electronic elements used for manufacturing transponders are in the dimensions of some hundreds or tens micrometers. The wire used for making the coil is normally in the dimension of ten micrometers so that the diameter of the wire is comparable with the dimension of a human hair.

Before bonding or soldering the several components together they have to be brought in the right position. For this step in the manufacturing process a very precise and exact positioning is needed.

Normally, when producing such transponders or electronic devices the electronic circuits, integrated circuit dice or chips are fixed to a core before winding the latter. The fixing of the chip and the core have to be done with a great precision so that the chip and the core remain in the desirable position. This is of importance to secure that the chip is still exact in its position for locating the ends of the coil above the contact regions of the chip for a correct bonding and contacting after winding the coil around the core with an automatic winding machine.

U.S. Pat. Nos. 5,572,410 and 5,634,261 disclose a process avoiding this fixing process. In the respective described process the electronic circuit is held independently of the winding. First, a wire is guided above a first contact region of the held circuit. Then the coil is wound and after winding the coil the wire is placed above a second contact region of the circuit. Thereafter the wire ends are soldered to the contact regions. The process according to U.S. Pat. Nos. 5,572,410 and 5,634,261 has the disadvantage that the guiding and placing of the wire above the contact regions take place in another plane than that used for winding the coil. Therefore, either the wire has to be handled in three dimensions or the core has to be rotated. Anyway, the process has to take place in three dimensions. This is very elaborate and difficult to perform, resulting in a slow production speed. Furthermore, this kind of process results in high investment in the production line and the produced piece itself is relatively high priced.

SUMMARY OF THE INVENTION

Therefore, it is an object underlying the present invention to provide a process and a device for producing a transponder in an easier way, with less investment in the production line, and with lower production costs while preferably providing a faster production speed.

This problem is solved according to one exemplary embodiment of the invention in which there is provided a method to produce a transponder which comprises the following steps: positioning a coil comprising at least one coil end in a predetermined coil position and holding all of said coil ends in a respective holding position, and holding an integrated circuit chip comprising at least one contact pad in a chip fixture so that all of said coil ends of the coil that should be bonded to said chip are located on one side of corresponding contact pads of the chip, and bonding of the coil ends to the contact pads.

A device to produce a transponder according to the present invention comprises a first positioning means for positioning a coil comprising at least one coil end in a predetermined coil position and holding all of said coil ends in a respective holding position, a chip fixture for holding a chip comprising at least one contact pad so that all of said coil ends of the coil that should be bonded to said chip are located on one side of corresponding contact pads of the chip, and a bonding unit for bonding of the coil ends to the contact pads.

In a transponder that comprises an integrated circuit chip or an encapsulated integrated circuit chip with at least one contact pad and a coil with at least one coil end wherein the chip and the winding of the coil are positioned approximately in the same plane according to the present invention at least two of said coil ends cross each other between their respective bonding points on the contact pads of the chip and the coil.

The advantage of the present invention is that the method is clearly partitioned into the following discrete steps: First, the coil is wound which can be done in a separate process or in an integrated process step. Second, the wound coil and the chip are positioned in their holding means after winding the coil or supplying a pre-wound coil. The chip and the coil are positioned in a way that the at least one coil end is positioned on one side of corresponding contact pad(s) of the chip, preferably above corresponding contact pad(s) of the chip. Third, the bonding is done after the positioning step. At the end, the produced transponder is withdrawn of the holding means and of the device.

Every step of the process is clearly delimited from the other steps. This leads to a fast and quick production process, since every production step can be performed with maximum performance without any restrictions in respect to the preceding or the following production step, so that the transponder can be produced with a minimum of time consumption. This is the precondition for producing the transponder efficient and in a large quantity.

Further, there is no need to switch back and forth between the several steps of the process, e.g. positioning, winding and then again positioning, and between the several parts of the production device. This makes the handling relative simple and easy.

Further, the coil and the chip can easily be positioned approximately in the same plane or in parallel planes during the production. So, a very flat transponder can be produced without the need of a later bending of the chip-coil arrangement and all handling and production steps can be accomplished in one plane, which leads to an uncomplicated production line in comparison to a three-dimensional production requirement according to the prior art discussed above.

Moreover, with the method and the device according to the invention it is possible to bond also coils with only one end, meaning that only one end of the wound wire is bonded to the chip. The second end of the wound wire might be a free end. This free end is wound, but not contacted to the chip, so this kind of coil might be similar to an electric antenna like a monopole antenna. Such a coil could only be used to send or receive data but not energy, because in such antenna no voltage can be induced for creating a current in the coil and wire, respectively.

It is clear that also coils with more than two coil ends can be used in the process and handled by the device according to the present invention. Then not all coil ends have to be contacted to the contact pads of the integrated circuit chip, but can be. The coil ends not bonded to the chip can stay as free coil ends or be connected to a second chip, etc . . . .

The chip fixture for holding the integrated circuit chip in his determined position can work with vacuum so that the chip is sucked in its position. Like a nozzle of a vacuum cleaner an opening can be positioned under a specially formed holding mould for the chip in the determined chip position wherein the opening is smaller than the mould and the chip. The chip is then fixed in its position as long as the vacuum exists.

A further advantage of the invention is that a coil with crossed coil ends can be used or integrated in the process. This avoids an unwinding of the wire of the coil during production without any further means, because the ends of the coil are pulled in the direction to the coil. Further, this feature secures the winding also for pre-wound coils.

In a preferred embodiment of the present invention wherein all of said coil ends are held in a first holding position, said chip fixture wherein said chip is loaded gets moved from a chip loading position to a chip bonding position and/or at least one of said coil ends gets moved from its respective first holding position into a respective second holding position by a wirecatcher so that all of said coil ends of the coil that should be bonded to said chip are located on one side of corresponding contact pads of the chip.

In case the coil and the chip or the encapsulated integrated circuit die could not be directly positioned relative to each other so that the coil ends are positioned on one side, preferably above the contact pads of the chip, the above further process is performed so that the coil ends are positioned above the contact pads. As described, this can be done by moving the chip into the bonding position where the contact pad(s) of the chip is/are located under the corresponding coil end(s) and/or by catching the coil end(s) with a wirecatcher and moving the coil end(s) to be located above the corresponding contact pad(s). For reasons of process economy it may be useful to insert this additional step, since the exact positioning can be achieved with less effort and with less technical complexity. Furthermore, a faster positioning can be realised and the accuracy can be elevated.

As indicated, it is further possible to combine these two possibilities of positioning the coil ends above the contact pads of the chip. Therewith the positioning can be speeded up in addition, since each positioning possibility can be kept as simple as possible. Therefore, this combination is preferred according to the present invention.

Moreover, handling the positioning in a separate process step has the advantage that the device parts can be optimised for this kind of wire handling. The handling tool can achieve a high accuracy and speed merged together with relative low costs of investment.

The chip fixture can be formed as a kind of slide on which the chip is held. The slide can be moved very quickly forward and backward. The position of the slide and with it the position of the chip can be reached with high accuracy. A plurality of such chip fixtures can be arranged on a turntable or a kind of merry-go-round or as a turning arms or the like to be positioned at manufacturing or mounting stations corresponding to the discrete manufacturing steps.

According to the present invention, preferably a coil is positioned and held in a coil holder, a first and a second coil end are held in a first and a second wire holder, respectively, at its respective first holding position, the integrated circuit chip is positioned in the chip fixture and moved into the vicinity of the coil so that the first contact pad of the chip is positioned under the first coil end, the second coil end is caught and repositioned and stretched above a second contact pad of the chip with a wirecatcher and the second coil end is fixed in a third wire holder at its respective second holding position, after which the first coil end is bonded to the first contact pad and the second coil end is bonded to the second contact pad.

In this preferred embodiment, the coil holder might be optimised for holding coils with free coil ends. Further, the coil ends are attached in special wire holders to avoid the indefinite positioning and movement of the coil ends.

Preferably the first coil end is-held by the first wire holder and the chip is moved below the coil end and into the vicinity to the coil. So the chip and the coil are relatively close together so the whole workpiece is small. The second coil end is moved with a wirecatcher above the chip and its contact pad. In this preferred embodiment the two possibilities of moving the coil ends into their bonding position above the contact pads of the chip are combined. The advantage of this combination is that production speed can be increased.

Only after both coil ends are in their bonding position the chip and coil are bonded together. Thereafter, the workpiece has not to be moved back into the wire handling position for another wire handling step. This leads to a clear separation of the process steps.

Further preferably, according to the invention the coil holder for positioning and holding the coil has a top part which is covered with a synthetic coating.

The coating of the inner side of the top part of the coil holder with a synthetic material or with plastics secures that the coil gets released easy of the top part when the transponder is finished and has to be plundered. The coating avoids sticking of the coil in the coil holder. In addition the inner side of the bottom part of the coil holder can also be covered. As an example, a polytetrafluorethylene material like teflon is used as coating. Thereover, layering the lower portion of the top part of the coil holder with a synthetic and non-conductive material has the further advantage that the finished transponder can be tested in the test station without releasing it from the coil holder. Plastic materials are best suited for this cover.

Preferably, according to the invention the first coil end gets stretched using a tension arm during and/or after the chip fixture is moving from the chip loading position to the chip bonding position.

The tension arm guarantees that the coil end is stretched and so positioned straight above the contact pads of the chip. It further secures a good connection in the bonding point.

Further preferably, according to the invention the second coil end gets cut off after the wirecatcher caught the second coil end with a cutter so that the second coil end is cut between the wirecatcher and the second wire holder.

This cutting secures that the wire will not tear between the wirecatcher and the coil in which case either the production line would have to be stopped and a manual positioning of the second wire end would have to be performed, if possible at all, or if no manual positioning is possible or desired—the currently produced transponder will not function and be discarded in a later functionality test.

Preferably, according to the invention the coil ends get crossed between the bonding points where the coil ends are bonded to the contact pads of the chip and the coil.

Such a crossing secures that the coil will not unwind. This feature is preferred for both, the production of a transponder with an already finished coil that is delivered to the production line according to the present invention, and the production of a transponder wherein the coil is wound during the production on the production line according to the present invention, as set out in the following and further below in connection with the exemplary elucidated preferred embodiment of the invention that is shown in the figures.

Preferably, according to the invention claims a wire gets held as a first coil end in a first wire holder, the wire gets wound to a coil in a coil holder using a winding tool, and the wire gets held as a second coil end in a second wire holder.

This preferred embodiment enables to very easily produce the coil during the assembly of the transponder and secures that the coil is appropriately positioned in a coil holder that is used in the production line according to the present invention. Further, such a winding according to the present invention can be performed basically in one plane even if the coil would be needed in another plane, i.e. in a perpendicular plane, during the production of the transponder, since it would easily be possible to reposition the coil holder into another plane after the winding is performed and before the coil is fixed to the chip, i.e. before the coil ends are bonded to the contact pads of the chip.

In a preferred embodiment of the method according to the invention comprises the steps: positioning of a turntable with at least a winding position and a wire handling position into the winding position in which the coil is wound by a winding tool, and turning the turntable from the winding position into the wire handling position wherein the winding tool is not moving with the turntable causing that wire that is being supplied from the winding tool is received by a wire holder and forms simultaneously an end coil end of a first coil and a start coil end of a succeeding second coil in their respective first holding position.

Correspondingly, an embodiment of the device according the invention comprises a turntable with at least a winding position and a wire handling position, a winding tool for winding the coil which is fixed above the winding position of the turntable, wherein the winding tool comprises a flyer leading the wire and rotating around a coil holder, the wirecatcher is fixed above the wire handling position of the turntable, and turning of the turntable from the winding position into the wire handling position wherein the winding tool is not moving with the turntable causes that wire that is being supplied from the winding tool is received by a wire holder and forms simultaneously an end coil end of a first coil and a start coil end of a succeeding second coil in their respective first holding position.

According to the invention a turntable with at least a winding position and a wire handling position is used. The turntable can also comprise a bonding position and a plundering position in which the fabricated assemblies or transponders are withdrawn of the turntable. The turntable further comprises several equal parts in which the coil and the chips are held. The advantage is that several components or half-finished products or transponders in different states can be handled, i.e. one per production state.

A preferred example of a turntable consists of four stations for producing the transponder. Each station is in a different position. While a first transponder is finished and will be plundered from the turntable, a second transponder is in the bonding station to be bonded. A third transponder is at this time in the wire handling position in which the first contact pad of the chip is moved to be positioned under the first coil end and thereafter the second coil end is positioned above the second contact pad of the chip. At this time in the first station the wire is wound with a winding tool to a coil held in a coil holder. One advantage of this is that four transponders can be produced “simultaneously”. Therewith the plurality of produced pieces of transponders can be increased.

Another advantage is that the wire can be supported continuously to the winding tool and the wire is positioned automatically in the next free wire holder for holding the coil ends in their right respective first holding position. The wire never has to be handled manually and it is possible to have a continuous process flow.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a typical production line according to the present invention that produces passive RFID transponders, which consists of a coil12, e.g. made out of isolated copper wire with typical dimensions such as a diameter of 0.01-0.15 mm and a microchip11comprising an encapsulated electronic integrated circuit, as shown inFIG. 3. According to the present invention, the coil12is wound and then bonded to the chip11at two points. Thereafter, the production line tests the functionality of a produced transponder and then picks and places it onto a tray or onto various kinds of materials for encapsulation.

In particular, the production line comprises a turntable1with a winding station2, a chip loading/wire handling station3, a bonding station4and a plunder station5. Basically, these stations are predetermined positions of the turntable1at which a respective operation is carried out. The turntable1comprises four coil and chip holders that are brought to the different stations by turning the turntable1in a clockwise direction. At each station a different production step is performed, beginning with the coil winding and ending with the plundering so that transponders can be manufactured in a particular easy and fast way.

To secure such a rapid production various additional devices are arranged around the turntable1to ensure that a robot8can pick the readily manufactured transponders at the plunder station5, bring them to the test station7and thereafter to a round table6to place them onto the tray or various kinds of materials for encapsulation in a fast manner. These components are in particular a (not shown) coil winding tool that is arranged above the winding station2, a chip feeder9and a module chip feeder10that are arranged in the vicinity of the chip loading/wire handling station3. These components deliver the materials needed to produce the transponders, namely the wire needed to produce the coils and the chips to which the coils are bonded, respectively. The chip feeders9and10are standard devices, which comprise a small robot arm that picks up the chip and places it in a chip fixture that is described in detail further below. The winding tool that is shown in detail inFIGS. 4 and 5is also elucidated further below.

FIG. 2shows the principal process that is carried out in the production line according to the present invention. In a first step S1a coil winding is performed at the winding station2. Alternatively, an already finished, i.e. pre-wound, coil could be supplied at this state. Then, the turntable rotates 90° in a clockwise direction to bring the coil to the chip loading/wire handling station3in which a chip feeding is performed in a second step S2. After the chip feeding a third step S3follows in which a wire positioning is performed while the coil and the chip are still in the chip loading/wire handling station3. During the wire positioning the wire and the chip are positioned relative to each other so that in a following step S4, which is performed after the turntable again rotated about 90° in a clockwise direction, the bonding of the wires to the microchip, i.e. a welding on microchip, can be performed. After the welding in step S4the turntable again rotates about 90° so that the transponder is delivered from the bonding station4to the plunder station5and a pick and place, function test and unloading can be performed in step S5. This is performed by means of the robot8, the test station7and the round table6, i.e. the robot arm8picks the manufactured transponder, delivers it to the test station7and after the test to the round table6where it is placed onto a tray or one of various kinds of materials for encapsulation.

FIG. 3shows the transponder according to the present invention that is manufactured in the production line according to the present invention in more detail. The transponder comprises a chip11with a first connection pad11a, an encapsulated integrated circuit11band a second connection pad11c, and a coil12with a first coil end12aand a second coil end12b. The first coil end12aof the coil12is bonded to the first connection pad11aof the chip11and the second coil end12bof the coil12is bonded to the second connection pad11cof the chip11. The coil ends cross each other between the bonding points where the coil ends are bonded on the contact pads of the chip and the actual coil12. This crossing ensures that the wound coil will not unwind during the production, in particular if finished coils are delivered to the turntable1, or after the production, in particular before an encapsulation. The transponder according to the present invention comprises the winding of the coil and the chip substantially in the same plane.

FIG. 4shows the winding tool that is positioned above the winding station2of the turntable1in more detail. The winding tool13comprises a flyer13aand a wire guide13b. A copper wire14arrives at the central axis of the flyer13aat the winding tool13and is guided through the wire guide13bto a position on the outer circumferential area of the flyer13a. Further, the wire14is guided from the top to the bottom to be supplied to the turntable1, in particular to a coil holder15that comprises a top part15aand a bottom part15b, which are arrange one upon the other with a small gap in-between in which a coil is wound by rotating the winding tool around its central axis when the coil holder is located underneath the winding tool13and the central axis of the coil holder15and the-central axis of the winding tool13are aligned with each other.

The positioning of the coil holder15underneath the winding tool13and the guiding of the wire14to the coil holder15and from the coil holder15is elucidated in FIG.5, which shows the coil winding station2and the chip loading/wire handling station3in more detail. InFIG. 5an index1indicates a first assembly or manufacturing place and an index2indicates a second assembly or manufacturing place, which are in the following also referred to as working place. As stated above, the turntable1comprises four such working places which are respectively located underneath one of the assembly or manufacturing stations1to4and moved from station to station by turning the turntable1by 90°. All components with indices are therefore available four times on the turntable1. All other components are uniquely available. In particular, the turntable1comprises four wire holders from which a first wire holder19and a second wire holder20are shown, which wire holders separate the working places, a robot arm18which is located above the chip loading/wire handling station3to perform a part of the wire positioning, and the winding tool13which is arranged above the winding station2. The robot arm18, which is in the following referred to as wirecatcher18, and the winding tool13are not moving when the turntable1rotates.

Each of the working places comprises a slide16with a chip fixture17, a third wire holder21, a tension arm22, and guiding pins23additionally to the fixed bottom part15bof the coil holder15. The chip fixture comprises four guiding pins, namely two first guiding pins17aarranged to guide a wire for positioning above the first contact pad11aof a chip11loaded into the chip fixture17and two second guiding pins17barranged to guide a wire to be located above the second contact pad11cof the chip11loaded into the chip fixture17. The chip11might be held in a predetermined position within the chip fixture17by way of a vacuum.

In the shown state the winding of a coil at the winding station2at which a second working place is located, i.e. index2, is not started and a chip11is already loaded into the chip fixture17of a first working place, i.e. index1, where the winding of the coil was complete before the turntable1was turned by 90°, in other words, the state is shown in which the turntable was just rotated by 90° in a clockwise direction, the spinning of the succeeding coil is not yet started, but the chip11is already loaded into the chip fixture17at the chip loading/wire handling station3. In this state the guiding of the wire prior to the wire positioning according to the present invention can easily be seen. The end of the wire14is held by a first wire holder19and fed along a tension arm221of the first working place as a first coil end12a1within the first working place to the first coil holder151of the first working place. The wire14with which the coil is wound leaves the coil holder151of the first working place and is guided along guiding pins231of the first working place as a second coil end12b1of the coil12within the first working place to a second wire holder20. The same wire guiding is performed for every one of the four working places in this position. As can be seen inFIG. 5, the wire holders that are separating the working places serve simultaneously as second wire holder for holding the second coil end12band as first wire holder for holding the first coil end12aof the succeeding coil.

After the winding of a coil is finalised the two guiding pins23of a working place are raised from a buried position so that the wire that comes out of the spinning winding tool is not guided into the coil holder, but with a simultaneous rotation of the turntable1into the next wire holder that is separating the working place in which the winding of a coil is just finished from the succeeding working place, i.e. the working place in which the next coil will be wound.

For the loading of the chip11into the chip fixture17the slide16of a working place is positioned so that the chip fixture17is in an outermost position with respect to the turntable1. Further, in the shown initial state of the wire handling the wirecatcher18is positioned to be directed to the centre of the turntable1so that the guiding of the wire is not disturbed.

FIG. 6shows a first intermediate state of the wire handling in which the slide161is moved inwardly with respect to the edge of the turntable1so that the first guiding pins17a1of the chip fixture171catch the first coil end12a1which causes that the wire of the first coil end12a1that is in a tensed state due to the pressure of the tension arm221is stretched against both first guiding pins17a1and located above the first contact pad11aof the chip11which is loaded in the chip fixture171. Further, in this state the wirecatcher18is turned to grab the wire of the second coil end12b1between the two guiding pins231of the first working place. To catch the wire in this position the wirecatcher18performs approximately a 180° turn in a counter-clockwise direction from its initial position in which the wirecatcher18is directed inwardly with respect to the turntable1. In the first intermediate state the wirecatcher is directed outwardly with respect to the turntable1. Of course, the wirecatcher might also move 180° in a clockwise direction to catch the wire14of the second coil end12b1in the shown position. The moving direction of the wirecatcher18basically depends on its design and on the design of the whole manufacturing line.

FIG. 7shows a second intermediate state of the wire handling according to the present invention. To reach this second intermediate state the wirecatcher18moves approximately 90° in a clockwise direction in respect to the first intermediate state. The result of this move is that the wire of the second coil end12b1is stretched against the second guiding pins17b1of the chip fixture171to be located above the second contact pad11cof the chip11loaded in the chip fixture171and that the second coil end12b1is further guided into a third wire holder211that is arranged to receive a wire in this position. During the move from the first intermediate state to the second intermediate state the wire is caught by a gripper28that is attached at the wirecatcher18. The wire is kept stretched by the fact that due to the position and the geometry of the wire catcher18the wire is moving away from the chip fixture171and by the fact that the wire is sliding in the gripper28of the wirecatcher18. The strength with which the gripper28is holding the wire is determined by a regulated air pressure applied to the gripper28. Before moving the wire with the wirecatcher18from the first intermediate state to the second intermediate state it is cut between the wirecatcher18and the second wire holder20.

FIG. 8shows the final state of the wire handling in which the wirecatcher18moved back to its initial position by another approximately 90° turn in a clockwise direction and the third wire holder211holds the wire of the second coil end12b1in a tensed state. In this final state both coil ends12a1and12b1of the coil121are properly positioned above the contact pads11a,11cof the chip11loaded into the chip fixture171.

The turntable1then gets rotated by 90° in a clockwise direction so that the properly aligned transponder parts, i.e. the chip11and the coil121, are moved into the bonding station4.FIG. 9elucidates the bonding that is performed in this position schematically. The bonding itself is performed in a generally known manner, however, it should be noted that according to the present invention the bonding of both coil ends is performed simultaneously in order to facilitate a faster production. As described above, the first coil end12a1is positioned above the first contact pad11aof the chip11and the second coil end12b1is positioned above the second connection pad11cof the chip11. The bonding head24moves downwards until its diamonds25hit the contact pads11aand11cof the chip11. In reality the diamonds25of the bonding head24hit the wires of the first coil end12a1and the second coil end12b1and weld them onto the respective pad under a specific pressure and time in case of a thermal compression bonding.

After the bonding the wires might be cut by a cutter261that is provided on the slide161more or less directly behind the bonding points. Thereafter the wire ends in the first and third wire holders19,211are removed, e.g. by opening the wire holders and supplying an air pressure to blow the wire ends away or providing a vacuum to suck the wire ends away.

Then, the turntable1is again rotated by 90° in a clockwise direction so that the finished, but still loaded transponder reaches the plunder station5. In the plunder station5a robot tool27of the robot8moves downwards and docks with the top part15aof the coil holder, preferably while connecting air channels that might be used to create a vacuum in the top part15aof the coil holder15, as shown inFIG. 10. The robot8moves the robot tool27upwards and separates the two halves of the coil holder15. Due to the tendency of the transponder11,12to stick in the coil holder15the inner part of the coil holder15is coated with teflon. The vacuum created in the top part15amakes it possible to hold the transponder11,12, since the coil12is sucked on the top part15aof the coil holder15through the air channels. The robot8moves outwards to the testing station7where the transponder11,12is tested. For testing the transponder11,12without releasing it from the coil holder15the top part15ais layered with a plastic material. Otherwise, the transponder11,12has to be released from the coil holder15and to be set on a metal free testing plate. If the transponder11,12is positively tested, the robot8moves to the round table6and unloads the transponder11,12in an appropriate position. If transponder11,12is negatively tested, the robot8moves the transponder11,12to a reject bin and releases it. As mentioned above, the bottom part15bof the coil holder15is fixed to the turntable1.

The invention has been described in detail with respect to exemplary embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.