Abstract:
In an embodiment, a weld head for use in bonding antennas to IC modules in a sheet of smart card modules includes an integrated test unit, e.g., a reader/writer (R/W) unit. The test unit tests the bonds between the antenna and the IC module in a selected card module by attempting to communicate with the IC module with low-wattage RF waves via the card module&#39;s antenna.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. Provisional Application Serial No. 60/247,413, filed on Nov. 8, 2000 and entitled Integration of Smart Card Reader/Writers in High-Speed Robotic Welding Systems for On-the-Fly Quality Control Testing of Microelectronic Interconnects in the Manufacturing of Contactless Smart Cards. 
     
    
     
       BACKGROUND  
         [0002]    Smart cards are plastic cards that incorporate an integrated circuit (IC) chip with some form of memory. Many smart cards are wallet-sized, as specified by International Standard Organization (ISO) standards. These international standards specify physical characteristics of cards, transmission protocols, and rules for applications and data elements.  
           [0003]    Memory-based smart cards include memory and some non-programmable logic. Such cards may be used as personal identification cards or phone cards. More complex processor-based smart cards may include a central processing unit (CPU) and ROM for storing an operating system, a main memory (RAM), and a memory section for storing application data (usually an EEPROM). Processor-based smart cards may be used where heavy calculations or more security is required.  
           [0004]    Smart cards may fall into one of two categories: contact and contactless. Contact cards must be inserted into a card reader to be accessed. Contact cards include an interconnect module, usually gold plated, with contact pads. The interconnect module may include power, reset, ground, serial input/output (SIO), and clock signal contact pads, as laid out in ISO 7816. The contact pads are physically contacted by pins in the reader to power and communicate with the IC chip. Contact cards are commonly used as telephone prepayment cards and bank cards.  
           [0005]    Contactless cards do not require contact with the reader to be accessed. Contactless cards include an antenna embedded in the card which may be used for power transmission and communication by radio signals or capacitive inductance. Some advantages of contactless cards over contact cards include faster transactions, ease of use, and less wear and tear on the cards and readers.  
           [0006]    Hybrid and dual-interface cards include aspects of both contact and contactless cards. Hybrid cards have two chips, each with its respective contact and contactless interface. Dual-interface, or “combi,” cards have a single chip with both contact and contactless interfaces.  
         SUMMARY  
         [0007]    In an embodiment, the bonds between the antennas and integrated circuit (IC) modules in a batch of smart card modules formed in a sheet substrate are produced and tested by an integrated weld/test apparatus. The bonds are generated at one ore more interconnect sites in a card module with a weld tip and then tested with a test unit (e.g., a reader unit or reader/writer (R/W) unit) prior to the welding operation in the next selected card module in the sheet.  
           [0008]    The test unit includes an antenna which generates electromagnetic waves, e.g., radio frequency (RF) waves, for powering and communicating with an IC module in a card module via the card module&#39;s antenna. The test unit may test the IC module by reading the contents of a memory in the IC module. The test unit may test the IC module by writing information to the IC module memory and then reading back that information via the antenna. The test unit may test the IC module by prompting a processor in the IC module to perform a function. A card module that fails testing may be marked for re-work.  
           [0009]    An integrated R/W unit may be used to program the IC module in a selected card module in a sheet with initialization and/or personalization information after the weld operation in the selected card module and before the weld operation in the next selected card module in the sheet.  
           [0010]    After the bonds in the card modules in the sheet have been welded and tested and any in line programming has been performed, the sheet may be cut into pre-tested and/or pre-programmed smart cards. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a sectional view of a smart card according to an embodiment.  
         [0012]    [0012]FIG. 2A is a plan view of a sheet including a number of card modules according to an embodiment.  
         [0013]    [0013]FIG. 2B is an expanded view of one of the card modules of FIG. 2A.  
         [0014]    [0014]FIG. 3 is a perspective view of an integrated weld/test head according to an embodiment.  
         [0015]    [0015]FIG. 4 is a flowchart describing an integrated weld and test operation according to an embodiment.  
     
    
     DETAILED DESCRIPTION  
       [0016]    [0016]FIG. 1 illustrates a contactless smart card  100  according to an embodiment. The contactless card  100  contains an integrated circuit (IC) chip  102  connected to a wire-wound antenna  104  embedded in a plastic card layer  106 . The antenna  104  may include three or four turns of wire and is generally located around the perimeter of the card. The card may conform to International Standard Organization (ISO) 14443 or 15693, an international standard for remote coupling contactless cards. ISO specifies physical, mechanical, and electrical features of the card and the communication protocols between the card and the reader, without restricting the architecture of the IC chip in the card or the application for the card. A popular architecture for such contactless smart cards is the Mifare architecture and related protocols developed by Philips Semiconductor.  
         [0017]    Reader peripherals and reader/writer (R/W) units read contactless smart cards through low-wattage radio frequencies, generally between 10 MHz to 15 MHz. The readers produce a low-level magnetic field by means of a transmitting antenna, usually in the form of a coil. The magnetic field serves as a carrier of power from the reader to the contactless smart card, which accesses this field through the embedded antenna  104 . The reader recovers the electromagnetic signal from the passive smart card and converts the signal back into an electrical form. Once the reader has checked for errors and validated the data received from the smart card, the data is decoded and restructured for transmission in the format required by the host computer.  
         [0018]    A batch of contactless smart cards may be manufactured simultaneously from a single sheet  200  of plastic, e.g., Polyvinyl Chloride (PVC) or Acrylonitrile Butadiene Styrene (ABS), as shown in FIGS. 2A and 2B. The plastic sheet  200  forms the substrate of the smart card modules  202  that are subsequently cut from the sheet  200 . Cavities are punched in the sheet in locations corresponding to the IC modules for each card in the sheet. The IC modules  204  are then placed in the cavities and secured in place with an adhesive.  
         [0019]    After the sheet has been populated with IC modules, the card antennas  204  are installed. The card antennas  204  may be round conductor wires that are embedded into the sheet  200  around what will be the perimeters  206  of the cut cards. A robotic arm that includes an ultrasonic head, a wire feed system, and cutter may be used to liquefy the plastic in the sheet and embed the wire antennas in the different card locations. Alternatively, the antennas may be bonded or deposited on the sheet in the respective card modules  202 .  
         [0020]    Each IC module  204  may include two contact tabs  208  for interconnection with the two ends  210  of the associated wound wire antenna  204  of the card module. The ends  210  of the wire antenna may be bonded to the contact tabs  208  using thermo-compression welding techniques. Since the wire antenna is used to supply power to the IC module and to enable the IC module to communicate with the card reader, it is critical that a good bond is formed between the wire antenna and the IC module.  
         [0021]    In an embodiment, the bonds between the antenna ends  210  and the IC module  204  are tested during fabrication of the card modules  202  in the sheet  200  (i.e., tested “in line”) by testing the operation of the IC module  204  via the wire antenna  205  following the interconnect welding operation. As shown in FIG. 3, the bonding apparatus  300  includes a robotic welding system with a robot hand  302  that integrates a weld head  304  and a R/W unit  306 . The weld head  304  includes a weld tip  310  for producing the thermo-compression bond between the wire antenna ends  210  and the contact tabs  208  on the IC module  204 . The R/W unit  306  generates low-wattage radio frequencies (e.g., between 10 MHz to 15 MHz) for providing power to and communicating with the IC modules  204  in the sheet  200  via the associated wire antennas  205  to which the IC modules  204  are connected.  
         [0022]    [0022]FIG. 4 is a flowchart illustrating an integrated weld and test operation  400  to an embodiment. The flow of the operation  400  is exemplary, and blocks in the flowchart may be skipped or performed in different order and still achieve desirable results.  
         [0023]    The robot arm and/or sheet are moved to align the weld tip  310  with the interconnect site on an IC module  204  in a selected card module  202  (block  402 ). The heated weld tip  310  is pressed against the interconnect site to form the thermo-compression bond (block  404 ). After both interconnects are made between the wire ends  210  and contact tabs  208  of the IC module, the R/W unit  306  is activated (block  406 ). The robot arm may move the R/W unit  306  to a desirable range and orientation for communicating with the IC module  204 , e.g., about 4 cm. The R/W unit  306  then tests the operation of the selected IC module (block  408 ).  
         [0024]    The R/W unit  306  may perform one or more of various tests on the IC module. These tests may include, for example, a wake-up call, serial number check, full memory read, and full function test. The R/W unit  306  may also write data to the chip and then read back and check the written data from the chip memory. If any of the tests fail (block  410 ), the card may be stamped or otherwise marked for rework (block  412 ). After the weld and test operations have been performed on all of the card modules  202  in the sheet  200 , the marked cards modules with defective interconnects may be reworked in a subsequent fabrication operation ( 414 ).  
         [0025]    The IC modules  204  in the individual smart card modules  202  may also be programmed in line by the R/W unit  306  (block  420 ), before the cards are separated from the sheet. The programming may include initialization, in which all of the IC modules  204  are loaded with data that is the same for the batch of smart cards in the sheet  200 . The programming may also include personalization, in which an individual IC module  204  is loaded with data specific to an individual cardholder.  
         [0026]    When the interconnects in all of the card modules  202  on the sheet  200  are satisfactory and any desired in line programming of the IC modules  204  is complete, the sheet  200  may be passed on for lamination. Once laminated, the sheet  200  may be cut into the individual smart cards (block  430 ).  
         [0027]    The operation  400  may be implemented in hardware or software, or a combination of both (e.g., programmable logic arrays). Unless otherwise specified, the algorithms included as part of the operation are not inherently related to any particular computer or other apparatus. In particular, various general purpose machines may be used with programs written in accordance with the teachings herein, or it may be more convenient to construct more specialized apparatus to perform the required method steps. However, preferably, the invention is implemented in one or more computer programs executing on programmable systems each comprising at least one processor, at least one data storage system (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. Program code is applied to input data to perform the functions described herein and generate output information. The output information is applied to one or more output devices, in known fashion.  
         [0028]    Each such program may be implemented in any desired computer language (including machine, assembly, high level procedural, or object oriented programming languages) to communicate with a computer system. In any case, the language may be a compiled or interpreted language.  
         [0029]    Each such computer program is preferably stored on a storage media or device (e.g., ROM, CD-ROM, or magnetic or optical media) readable by a general or special purpose programmable computer, for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. The system may also be considered to be implemented as a computer-readable storage medium, configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform the functions described herein.  
         [0030]    A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.