BACKGROUND OF THE INVENTION

[0002] Smart cards are used as bankcards, ID cards, telephone cards and the like. They are based upon the use of an electromagnetic coupling (either by direct physical contact or by electromagnetic waves) between a smart card's electronic components and a card reader, pickup head or other appropriate electronic signal receiving device such as those employed in an ATM. Because these cards are so widely used to effect very valuable and/or otherwise important transactions, they are the frequent subject of fraudulent activities. These fraudulent activities often involve physically tampering with a smart card's electronic components. For example, their computer chips or other electronic components are removed from a valid smart card and physically transferred to a fraudulent card in order to gain money, unauthorized access, unauthorized information, etc.

[0003] Smart cards are usually made by assembling several layers of plastic sheets in a sandwich array. In the case of so-called “contact” type smart cards at least one face of the smart card has an opening in which an electronic signal sensing component such as a strip-like sensor, computer chip, module or “pickup head” reside(s). The electronic signal sensing component comes into direct physical contact with an electrically cooperating component of a machine (e.g., an ATM machine, credit card transaction machine, a personal identity verification machine, telephone, etc.) in which the contact type smart card is employed. Many contact type smart cards have all of their electrical components (e.g., their electronic signal sensing device and their computer chip assembled) in a unified module that is glued in an open cavity in a face of the card. By way of distinction, so-called “contactless” smart cards communicate with the machines in which they are employed by means of a radio wave-receiving antenna that is embedded in the interior of the contactless smart card. Hence, there is no physical contact between the card's electronic signal sensing component(s) and the user machine's signal sensing component. Some smart cards operate in hybrid, contact/contactless, modes of operation.

[0004] Applicant's invention may be used with any of these three types of smart card; but for reasons hereinafter more fully explained, it is more particularly concerned with “contact” type smart cards and/or the methods employed to manufacture them. The methods by which prior art smart cards have been manufactured have varied considerably. For example, U.S. Pat. No. 5,272,374 discloses an integrated chip-employing smart card comprising a card board having a first and a second major surface and a semiconductor module having an electrode terminal face. The semiconductor module is mounted in the card board such that the electrode terminal face is left exposed in the first major surface of the card board.

[0005] U.S. Pat. No. 5,311,396 teaches a portable and connectable chip-based smart card system having one or more chips integrated into a package. The electronic component is mounted on the upper surface of metal contacts. A lower surface has metal contacts that constitute a connector of the system. Each of the metal contacts of the upper face is connected to, and faces, a metal contact of the lower surface, and vice versa. In a second embodiment of this invention, the electronic component is surface mounted on an upper surface of the metal contacts in a manner such that the lower surface of these contacts forms the connector.

[0006] U.S. Pat. No. 5,486,687 teaches a memory card having several integrated circuits for personal computers. These memory cards serve as a large capacity mass memory for replacing floppy disks and other exchangeable magnetic supports. They are provided with a plug-in connector at the end of the card and can be inserted in the reader in a prescribed manner, e.g., in accordance with PCMCIA standards. According to one aspect of this invention, a flush contact chip card memory is formed by such a plug-in card. To this end, the card has a supplementary connector with flush contacts on its principal face. The resulting reader is transportable. Its application software can be stored in the card and can be installed in any random microcomputer equipped with a PCMCIA reader.

[0007] All of these prior art methods for making contact smart cards are to some degree concerned with properly positioning and fixing the electronic signal sensing component module or assembly inside the smart card in such a way that they present a flat surface on or substantially flush with the card's face surface (or its obverse surface). Unfortunately, this proximity of the signal sensing component to the face surface (or its obverse) of contact smart cards presents an opportunity for tampering with, and fraudulent use of, such cards.

SUMMARY OF THE INVENTION

[0008] Applicant's smart cards (e.g., credit cards, ATM cards, personal identity cards, access control cards, telephone cards, etc.) and methods for making them are primarily based upon the use of certain hereinafter more fully described physical elements and manufacturing procedures. Applicant's tamper-preventing construction for contact type smart cards is achieved by coating the rear side of the smart card's contact device (e.g., its signal sensor, pickup head, computer chip) with a primer/adhesive that has the ability to form a strong bond with a thermosetting polymeric material that is injected into a void space that eventually becomes the core or center layer of the smart card. This construction method is based upon applicant's finding that the bonding action between a primer/adhesive and the thermosetting polymeric material that forms the core of the card is much stronger than the bonding action between the rear surface of an electrical signal sensing component and a thermosetting polymeric material.

[0009] The tamper-preventing action provided by applicant's placement of a primer/adhesive on the rear side (i.e., the thermosetting polymer contacting-side) of the card's contact device can be replaced by or further enhanced by placement of certain, hereinafter more fully described, “anchor hooks” on the electrical sensing component in a manner such that said hooks are immersed in the incoming, liquid, thermosetting polymer. Thereafter, these “anchor hooks” become very strongly embedded in the thermosetting polymeric material when it cures. Indeed, the use of such anchor hooks can, in its own right, achieve the tamper preventing action provided by applicant's primer/adhesive-thermosetting material bond. In some of the more preferred embodiments of this invention the primer/adhesive and the anchor hooks will be used together to achieve the tamper-preventing action.

[0010] The primer/adhesives used in the hereindescribed processes are so-called solvent based, primer/adhesives. They usually employ methyl ethyl ketone as a solvent for an adhesive, polymeric material. 3M Adhesive Systems Industrial Tape and Specialties Division, 3M Center, Building 220-7E-01, St. Paul, Minn. makes several such primer/adhesives. Their 4475® Primer/adhesive is, however, particularly preferred for the practice of this invention. In actual manufacturing practice, these solvent based, primer/adhesives may be at least partially cured by exposure to an “artificial” energy source (i.e., an energy source other than ambient heat and/or light of the manufacturing plant). This exposure speeds up the curing process. These artificial energy sources may be further characterized by their ability to produce electromagnetic waves of a given wave length. Some primer/adhesives, for example, can be more quickly cured by exposure to energy sources giving off electromagnetic waves having wave lengths ranging from about 200 to about 400 nanometers (nm). Such primer/adhesives are sometimes referred to as being “UV curable”. Electrically powered UV and/or microwave producing devices known to those skilled in this art may be employed as sources of such 200-400 nm wave forms. Use of devices that emit 260-270 nm wave forms is even more preferred when using certain UV curable primer/adhesives. Regardless of the type of solvent based, primer/adhesive being used, however, applicant's primer/adhesive “curing” step will most preferably, at least partially, take place in a period of time ranging from about 0.1 to about 10 seconds. Partial curing times of less than 3 seconds are even more preferred in high speed manufacturing processes.

[0011] These primer/adhesives should, most preferably, be employed in the form of at least one small layer, coating, mound, dollop, or hemisphere that is placed on an inside surface of the card's electronic signal sensing device that is exposed on an outside surface of a “contact” type card. In the case where the electronic signal sensing device is part of a module (e.g., one comprised of a signal sensor, a board, a chip, a potting device, etc.) the primer/adhesive is preferably placed on the bottommost element so that the primer/adhesive will come into intimate contact with the thermosetting material which, upon curing, become the center or core layer of the card. Such layer, mound, etc. of the primer/adhesive is preferably applied to the electronic signal sensing component, or the undermost component (e.g., the computer chip or porting device) of the module before being placed in an opening or holding hollow in the smart card's top (or bottom) layer. Again, this exposure of the signal sensing device allows it to come into physical contact with a signal reading device in a card-reading machine such as an ATM.

[0012] The beneficial effects of applicant's manufacturing procedures can be further enhanced by use of (1) certain hereinafter more fully described “cold,” “low pressure,” forming procedures, (2) certain physical placements of other electronic components (e.g., chips other than those in the module) within these smart cards, (3) certain thermoset flow gate geometries and (4) certain receptacles in applicant's molds for receiving thermoset material that may be injected in excess of the amount needed to form the core regions of applicant's smart cards. Aside from their tamper-preventing features, the smart cards made using the hereindescribed elements and manufacturing methods also are characterized by their high quality external surfaces. The term “high quality” in the context of this patent disclosure should be taken to imply substantially flat external surfaces (i.e., card faces having no waves, bends, wrinkles or pock marks).

[0013] Applicant's contact type, smart cards are generally comprised of a top layer having an inside surface and an outside surface, a bottom layer having an inside surface and an outside surface and a center or core layer that is sandwiched between the top and bottom layers. Either the top layer or the bottom layer (or both layers) of a contact type smart card made according to the methods of this patent disclosure may have an opening in which an electrical signal sensing device is affixed. Such devices are usually associated with other electronic components such as computer chips, boards, pods, etc. Hence, the resulting devices are frequently referred to as “modules.” One of the most common devices of this kind is a contact which (via a board) is combined with a chip to form a signal sensing/processing module.

[0014] In other cases, however, some of the additional electronic components (e.g., computer chips, capacitors, etc.) of applicant's contact type smart cards may be completely embedded in the thermosetting polymeric material that constitutes the card's center or core layer. Hence, these completely embedded electronic components form no part of the external surface of applicant's finished smart cards. Such cards are sometimes referred as hybrid or “combi” smart cards. Again, in the case of contact type cards, the card's electrical signal sensor device (its pickup head, contact surface, etc.) are placed in contact with a reading machine through an opening in a face (top or bottom) of the contact type smart card. Thus, electrical signal-carrying contact by the reading machine using the contact card (e.g., with an ATM) is made with the card via this exposed electrical contact in the face side (or obverse side) of the card.

[0015] In all cases, however, all three of these layers are unified into a smart card body by a bonding action between the thermosetting polymeric material used to create the core layer of such cards and those material(s) such as PVC, out of which the top and bottom layers are made. In some of the more preferred embodiments of applicant's invention, this bonding action may be augmented through use of various hereinafter more fully described treatments of the inside surfaces of the top and/or of the bottom layer of applicant's smart cards.

[0016] Before delving any further into the more specific details of applicant's methods for making the hereindescribed tamper-preventing smart cards, it should be noted that, for the purposes of this patent disclosure, the terms “upper” and “lower,” or “top” and “bottom,” layer(s) should be regarded as being relative. That is to say that they are implied by the relative positions of the mold shells that are employed to manufacture these cards. Hence, these terms should not imply any absolute position or orientation of the card itself.

[0017] Be this top/bottom nomenclature as it may, the hereindescribed methods for making tamper-preventing smart cards in general, and tamper-preventing contact type smart cards in particular, will employ reaction injection molding machines (which are often individually referred to as “RIM”). These machines are associated with a top mold shell and a bottom mold shell that, most preferably, are capable of performing certain hereinafter more fully described cold, low pressure, forming operations on at least one of the sheets of polymeric material (e.g., PVC) that make up the two major external surface layers of applicant's smart cards. Such top and bottom mold shells cooperate in ways that are well known to those skilled in the polymeric material molding arts. For use in applicant's particular processes, however, at least one of the RIM's mold shells, e.g., the top mold shell, will have at least one cavity for partially defining the thickness of, and general peripheral extent of, a precursor smart card body that is to be formed, and most preferably cold, low pressure formed, between the two mold shells.

[0018] It might also be noted here that applicant's use of the term “precursor smart card body” (which will include bodies of “excess” polymeric material) is to distinguish those roughly defined card bodies that are formed by such mold devices from those “finished” smart cards that are produced by removing the excess polymeric materials (e.g., by trimming them off of the precursor card body) and by cutting the precursor card bodies to certain prescribed sizes. For wide commercial use, all smart cards also must be made to very precise, standardized dimensions. For example, ISO Standard 7810 requires that contactless smart cards have a nominal length of 85.6 mm, a nominal width of 53.98 mm and a nominal thickness of 0.76 mm. Such cutting to prescribed sizes also may remove the excess material in one cutting/trimming operation. It also will be well appreciated by those skilled in this art that the molding devices used to make such cards in commercial production operations will most preferably have mold shells having multiple cavities (e.g., 2, 4, 6, 8, etc.) for making several such cards simultaneously.

[0019] Those skilled in this art also will appreciate that applicant's use of terms like “polymeric,” “plastic,” “thermoplastic” and “thermosetting” each refer to a potentially wide variety of polymeric materials. Be that as it may, the polymeric materials employed by applicant will generally fall into one of two subcategories—thermoplastic materials, or thermosetting materials. Thermoplastic materials are characterized by their possession of long molecules (either linear or branched) that have side chains or groups that are not attached to other polymer molecules. Consequently, thermoplastic materials can be repeatedly softened and hardened by heating and cooling so they can be formed, and then cooled to form a final hardened shape. Generally speaking, no appreciable chemical changes take place during such heat driven, forming operations. Conversely, thermosetting materials (such as their resins), have chemically reactive portions that form chemical cross-linkages between their long molecules during their polymerization. In other words, these linear polymer chains become bonded together to form stereo chemical structures. Therefore, once such thermosetting resins are hardened, the resulting material cannot be softened by heating without degrading at least some of the chemical cross linking molecular groups.

[0020] Either form of polymeric material (thermoplastic or thermosetting) may be used for the top layer and/or the bottom layer of applicant's smart cards. Hence, applicant's use of the general term “polymeric” with respect to the materials out of which applicant's top and bottom layers can be made should be taken to include thermosetting materials as well as thermoplastic materials. Thermosetting polymers are, however, highly preferred for creating the center or core layer of applicant's smart cards. There are several reasons for this preference. For example, thermosetting polymers generally bond better with the materials (e.g., PVC) from which the top and bottom layers are preferably made. Thermosetting polymers also can be commercially obtained in relatively inexpensive, easy to use, liquid monomer-polymer mixtures, or partially polymerized molding compounds, that are particularly well suited for use in applicant's high speed, cold, low pressure forming operations.

[0021] Some representative polymeric materials (thermoplastic or thermosetting) that can be used for making applicant's top and bottom layers will include polyvinyl chloride, polyvinyl dichloride, polyvinyl acetate, polyethylene, polyethylene-terephthalate, polyurethane, acrylonitrile butadiene styrene, vinyl acetate copolymer, polyesters, polyethylene, epoxy and silicones. Such top and bottom layers also may be made from other polymeric materials such as polycarbonate, cellulose acetate and cellulose acetate butyrate-containing materials. Of all the polymeric materials from which applicant's top and bottom layers could be made, however, polyvinyl chloride (“PVC”) is especially preferred because of the clear to opaque visual qualities of this material and its ability to receive printing and its relatively lower cost.

[0022] The most preferred thermosetting materials for applicant's injection purposes are polyurethane, epoxy and unsaturated polyester polymeric materials. By way of some more specific examples, polyurethanes made by condensation reactions of isocyanate and a polyol derived from propylene oxide or trichlorobutylene oxide are especially preferred. Of the various polyesters that can be used in applicant's processes, those that can be further characterized as being “ethylenic unsaturated” are particularly preferred because of their ability to be cross linked through their double bonds with compatible monomers (also containing ethylene unsaturation) and with the materials out of which applicant's top and bottom layers are made. The more preferred epoxy materials for use in the practice of this invention will be those made from epichlorohydrin and bisphenol A, or epichlorohydrin, and an aliphatic polyol (such as glycerol). They are particularly preferred because of their ability to bond with some of the more preferred materials (e.g., PVC) out of which applicant's top and bottom layers are made. These three general kinds of thermosetting material, (polyurethane, epoxy and unsaturated polyester), also are preferred because they do not tend to chemically react with applicant's more preferred glues (e.g., various cyanoacrylate-based glues), to form unsightly “artifacts” in the core regions of applicant's card bodies.

[0023] Next, it should be noted that applicant's use of expressions such as “cold, low pressure forming conditions” generally should be taken to mean forming conditions wherein the temperature of the injected polymeric liquid or semi-liquid material is less than the heat distortion temperature of the plastic sheet material being cold formed (e.g., the top layer of applicant's smart cards), and pressures less than about 500 psi. In some of the more preferred embodiments of the hereindescribed processes, the cold forming temperatures used in applicant's processes will be at least 100° F. less than the heat distortion temperature of the plastic sheet material being molded. By way of a more specific example, the heat distortion temperature of many polyvinyl chloride materials is about 230° F. Hence, the temperatures used to cold form such PVC sheets in applicant's process preferably will be no more than about (230° F.-100° F.). Temperatures of about 130° F. are particularly preferred for such materials.

[0024] Applicant's more preferred cold, low pressure forming procedures will involve injection of thermosetting polymeric materials whose temperatures range from about 56° F. to about 160° F., under pressures that preferably range from about atmospheric pressure to about 500 psi. More preferably, the temperatures of the thermosetting polymers being injected into the center or core region of applicant's cards will be between about 65° F. and about 130° F. under injection pressures that preferably range from about 80 to 120 psi. In some of the most preferred embodiments of this invention the liquid or semi-liquid thermosetting polymeric material will be injected into any given card forming cavity under these preferred temperature and pressure conditions at flow rates ranging from about 0.1 to about 50 grams/second/card-forming cavity. Flow rates of 1.5 to 1.7 grams/seconds/card-forming cavity are even more preferred. Those skilled in this art also will appreciate the applicant's low temperature and pressure conditions contrast rather sharply with the much higher temperatures (e.g., 200° F. to 1000° F.) and pressures (e.g., from 500 to 20,000 psi) that are often used in many prior art, high speed, smart card injection molding manufacturing operations.

[0025] It also should be noted that applicant's use of such relatively cold, low pressure, forming conditions may require that any given gate (i.e., the passageway that connects a runner with each individual card-forming cavity) be larger than those gates used in prior art, hot, high pressure operations. Applicant's gates are preferably relatively larger than prior art gates so that they are able to quickly pass the thermoset material being injected under applicant's cold, low pressure forming conditions wherein such thermoset materials are more viscous. Similarly, the runner (i.e., the main thermoset material supply passageway in the mold system that feeds from the source of the thermoset material to each individual gate), will normally be in a multi-gate or manifold array, and, hence, should be capable of simultaneously supplying the number of gates/card forming cavities (e.g., 4 to 8 cavities) in the manifold system at the relatively cold temperature (e.g., 56° F. to 160° F.) and relatively low pressure (e.g., atmospheric pressure to 500 psi) conditions used in applicant's process.

[0026] It also might be noted at this point that the flow rates for the polymeric thermoset material under applicant's low temperature and pressure conditions nonetheless, should be such that they are able to completely fill a given card-forming cavity in less than or about 10 seconds per card-forming cavity (and more preferably in less than about 3 seconds). Card-forming cavity fill times of less than 1 second are even more preferred where they can be achieved. In view of these cold-forming conditions, certain preferred embodiments of applicant's smart card making processes will employ gates having a width which is a major fraction of the length of a leading edge of the card to be formed (that is, a card edge which is connected to a gate). Applicant prefers that the width of a given gate be from about 20 percent to about 200 percent of the width of the leading edge (or edges—multiple gates can be used to fill the same card-forming cavity), i.e., the “gated” edge(s), of the smart card being formed.

[0027] Applicant also prefers to employ gates that are tapered down from a relatively wide inflow area to a relatively narrow core region that ends at or near the leading edge(s) of the card body being formed. Most preferably, these gates will narrow down from a relatively wide diametered (e.g., from about 5 to about 10 mm) injection port that is in fluid connection with a thermosetting material-supplying runner, to a relatively thin diameter (e.g., 0.10 mm) gate/card edge where the gate feeds the thermosetting material into the void space which ultimately becomes the center or core of applicant's finished card. By way of further example, applicant has found that gates that taper from an initial diameter of about 7.0 millimeters down to a minimum diameter of about 0.13 mm will produce especially good results under applicant's preferred cold, low pressure injection conditions.

[0028] Another optional feature that can be used to advantage along with applicant's glues and gluing procedures is the use of mold shells that have one or more receptacles for receiving “excess” polymeric material that may be purposely injected into the void space between applicant's top and bottom layers in order to expunge any air and/or other gases (e.g., those gases formed by the exothermic chemical reactions that occur when the ingredients used to formulate most polymeric thermoset materials are mixed together) from said void space. These thermoset ingredients are preferably mixed just prior to (e.g., about 30 seconds before) their injection into the void space.

[0029] Still other optional procedures that may be used to enhance the results of using applicant's manufacturing methods may include the use of: (1) treatments that encourage and/or augment the bonding action between the inside surfaces of the top and bottom layers and the injected thermosetting material, (2) films that display alphanumeric/graphic information that is visible at the card's major surface(s), (3) opacity promoting (or preventing) films or layers, (4) use of top layers or bottom layers that are at least partially pre-molded by a preceding molding operation (e.g., a preceding, prior art type, “hot” molding operation or a preceding “cold” molding operation such as those described in this patent disclosure and (5) the use of opacity promoting pigment(s) in the thermoset material. It might also be noted here that the outside surfaces of the smart cards resulting from applicant's manufacturing processes may be thereafter embossed or printed upon in order to display alphanumeric/graphic information.

[0030] Applicant's methods for making the smart cards of this patent disclosure also may, as an optional feature, involve the use of at least one gas venting procedure and/or at least one excess polymeric material receiving receptacle. More preferably, there will be at least one such receptacle per card-forming cavity. The presence of such gas venting and/or excess material receiving receptacles will allow gases (e.g., air, and the gaseous reaction products associated with those usually exothermic chemical reactions of the polymeric material forming ingredients) and/or relatively small amounts of the incoming thermoset polymeric material itself to escape from each void space during applicant's forming operations, e.g., cold, low pressure forming operations, and be received in such receptacles and/or be totally flushed out of the mold system. These gas venting procedures and excess material receptacles generally serve to prevent imperfections that may otherwise be created by entrapping gases in the void space during the injection of the polymeric material.

[0031] Thus, this aspect of applicant's invention involves injecting a flowable liquid or semi-liquid moldable polymeric material into a void space between the top and bottom layers of applicant's smart card in a process wherein the top and bottom molds are respectively abutted against the top and bottom layers of the smart card at a mold parting line perimeter or lip region at pressures that are sufficient to (a) completely fill the void space with a liquid or semi-liquid thermosetting polymeric material under the conditions (e.g., cold forming conditions) used in the hereindescribed processes, (b) immerse the primer/adhesive on the underside of the electrical signal sensor, module, etc., (c) immerse any anchor hooks associated with the electrical signal sensor or module, (d) drive minor amounts of the polymeric material out of the card forming cavities and into the excess material receptacle and/or (e) drive the gases in the void space to the excess material receptacle and/or drive such gases completely out of the mold system (e.g., drive such gases out of the mold at the parting line regions where the top and bottom mold shells come together). Thus, the mold lip pressures used in applicant's procedures should be sufficient to hold the pressures at which the thermoplastic material is injected in order to completely fill the void space between the top and bottom (e.g., between about ambient pressure and 200 psi), but still permit small amounts of the thermoset material and any gases to be flushed or squirted out of the mold system at its parting line. In other words, in these preferred embodiments, applicant's “excess” material receptacles need not, and preferably will not, receive all of the excess material injected into the void space. Excess thermoset material and/or gases also may be—and preferably are— expunged from the entire mold system at the parting line where the top mold lip and the bottom mold lip abut against each other or abut against the top layer and the bottom layer. In effect, the incoming liquid or semi-liquid thermoset polymeric material completely fills the void space, immerses any primer adhesives, electronic component(s), anchor hooks, etc. contained therein and force any air present in the void space between the top and bottom layers (as well as any gases created by the chemical reaction of the starting ingredients of the polymeric material) out of the void space—and, in some preferred cases, completely out of the mold system. All such actions serve to eliminate any surface imperfections such as surface “pock marks” and/or encapsulated bubbles that might otherwise form if such gases were entrapped in the thermoset polymeric material when it solidifies to form the core region of applicant's cards.

[0032] Finally it also should be noted that the top and/or bottom layers used in applicant's processes may be at least partially molded into cavity-containing forms before they are placed in the mold system used to make the smart cards of this patent disclosure. Hence, the “cold, low pressure” molding operations called for in this patent disclosure may be only a part of the total molding to which these layer or sheet materials are subjected. Thus, for example the cold, low pressure molding procedures of this patent disclosure may provide only a partial amount of the total molding experienced by a molded top layer of applicant's smart card. In the more preferred embodiments of this invention, however, the top layer will experience a major portion, e.g., at least 50 percent, and more preferably all of the total molding it experiences (as defined by the change in the volume of the cavity created by the molding operation) by the cold, low pressure molding operations that are preferred for the hereindescribed molding operations.