Patent Description:
Devices incorporating wireless communication approaches including RFID technology are widely used for a variety of different applications, including inventory control, tracking, guard, and security systems. Such systems are well known in the retail industry, including in connection with clothing inventory control and security from theft and other losses.

RFID devices may have a variety of integrated components, such as an RFID chip containing data like an identification code for the type of product and/or product component, allowing for immediate electronic identification and tracking of the exact piece of goods associated with a unique identification code. Other components include at least one antenna electrically connected to the RFID chip, which is responsible for transmitting signals to and/or receiving signals from another RFID device, for example, an RFID reader system.

In one example, an RFID reader is associated with a point-of-sale location or check-out counter of a retail facility and detects the chip in a tag associated with a piece of goods, which can include the stock keeping unit (SKU) and register price of that item, as well as other specific identification indicia. In another example, an RFID-readable tag is attached to a piece of merchandise in a retail facility, which tags are scanned using an RFID reader to keep proper count of the product inventory and/or to be used as a security measure functioning as a so-called guard tag.

Typical RFID devices currently in the marketplace are susceptible to damage and reduction or elimination of expected operability upon exposure to the conditions of industrial processing of clothing, components or other items or products, particularly those made of fabric material. Such susceptibility can be experienced before, during and/or after manufacturing and processing and subsequent warehousing, merchandising, use and handling by consumers.

One conventional approach to producing RFID devices is commonly referred to as a "flip chip" or direct chip attachment approach. According to such an approach, an RFID chip is pushed into the surface of an antenna formed of a suitable conductive material such as aluminium or copper foil. The RFID chip is oriented with its conductive connections facing toward the foil, and secured using an adhesive. Typically, the adhesive is a form of an epoxy with particles such as plastic beads plated with gold incorporated into it. Such adhesive is commonly referred to as "anisotropic conductive paste. " The adhesive is, in one embodiment, non-conductive in its state before application, but when the RFID chip is pushed down so its conductive connection bumps are in proximity to or touch the foil, a conductive connection is made, which can be assisted by the particles becoming trapped in the interface.

Once the RFID chip is in place with the adhesive between it and the foil, the adhesive needs to be cured. Typically, this is achieved by applying pressure and heat using two metal blocks, one under the antenna and one above the RFID chip. These metal blocks are commonly referred to as "thermodes. " Process conditions vary depending on the size of the RFID chip and nature of the substrate; however, for a <NUM><NUM> RFID chip, a force of <NUM> N applied using a <NUM>° C. top thermode (i.e., the thermode positioned closest to the RFID chip) and a <NUM>° C. bottom thermode (i.e., the thermode positioned closest to the antenna) for one to ten seconds is typically suitable for curing the adhesive and completing the joint.

<CIT> discloses a method for producing a device having a transponder antenna connected to contact pads. An antenna with terminal connections is provided in contact with a substrate. The contact pads are placed on the substrate and connected to the terminal sections of the antenna. The connection is produced by means of a soldering by introducing energy between the pads and the terminal sections. The pads are placed such as to provide a surface facing an antenna terminal connection section. The section is arranged on the substrate and the soldering energy is directly applied to the pads. The invention also relates to the device obtained.

<CIT> discloses a system which has a stamping device for stamping out RFID chip modules from a carrier strip, and a stamping punch provided above a stamping opening. A support receives a substrate and is provided below the stamping opening in an accurate positioning manner. The punch is moved up against the substrate, and a suction device holds the modules on the punch. A heating device melts solder present on the modules so as to establish a conductive connection between an electrical connection of the modules and a conductor of the substrate. The substrate is made of paper and plastic material.

Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate manner.

<FIG> illustrates the assembly of an RFID device using one approach according to the present disclosure. The RFID device may be provided according to conventional design, with an RFID chip <NUM>, an associated antenna <NUM>, and an adhesive <NUM>. The RFID chip <NUM> is oriented with its conductive connections <NUM> facing toward the antenna <NUM>, for a "flip chip" or direct chip attachment approach. As for the antenna <NUM>, it is mounted to or otherwise associated with a fabric substrate <NUM>, such as a patch, an article of clothing, or a tag or label of an article of clothing. The antenna <NUM> may be an antenna of any shape contemplated by the art. In one embodiment, the antenna is a dipole.

<FIG> illustrates a pair of similarly configured thermodes <NUM> and <NUM>, with a top thermode <NUM> positioned closer to the RFID chip <NUM> and a bottom thermode <NUM> positioned closer to the antenna <NUM>, but spaced from the antenna <NUM> by the substrate <NUM>, which as discussed herein is fabric. It is important to note that the present invention is not limited to a fabric substrate, but may be any other type of flexible substrate known in the art. In the embodiment of <FIG>, both thermodes <NUM> and <NUM> are configured as pin thermodes, which each have a tip <NUM> with a smaller cross-sectional area (i.e., the surface facing the other thermode and the components of the RFID device in the orientation of <FIG>) than a conventional flat thermode. For example, a conventional flat thermode may have a cross-sectional area on the order of cross-sectional area of conventional thermode of approximately <NUM><NUM> (or in a range between <NUM><NUM> and <NUM><NUM>), whereas a pin thermode according to the present disclosure may have a tip <NUM> with a cross-sectional area on the order of a cross-sectional area of approximately tip <NUM><NUM> (or in the range of approximately <NUM><NUM> to <NUM><NUM> depending on the size of the RFID chip). In one embodiment, a pin thermode may have a cross-sectional area that is less than a cross-sectional area of the associated RFID chip or, at most, substantially equal to the cross-sectional area of the associated RFID chip to ensure that pressure and heat are applied to the necessary portions of the adhesive. However, it is also within the scope of the present disclosure for the cross-sectional area of a pin thermode to be larger than the cross-sectional area of the associated RFID chip, though preferably no more than nominally greater.

While the top thermode <NUM> may be provided according to conventional design, the illustrated pin configuration is particularly advantageous for the bottom thermode <NUM>. As described above, a conventional thermode will compress a fabric substrate and heat the fabric over a large area, whereas the tip <NUM> of a bottom pin thermode <NUM> is shaped so as to instead penetrate into the fabric substrate <NUM> to move into contact with or at least into the vicinity of the antenna <NUM>. If the bottom thermode <NUM> is provided with a heating element <NUM> associated with the tip <NUM> and/or a body <NUM> of the bottom thermode <NUM> (as in the embodiment of <FIG>, in which the top thermode <NUM> also includes a heating element <NUM>), then heat applied by the bottom thermode <NUM> to the fabric substrate <NUM> will be reduced to a much smaller area (i.e., the immediate region surrounding the portion of the bottom thermode <NUM> penetrating the fabric substrate <NUM>). Thus, if the bottom thermode <NUM> has a substantially circular or circular cross-sectional shape, then heat would be applied only to a small cylindrical region of the fabric substrate <NUM>, rather than over a much larger area, which greater reduces the damage done to the fabric substrate <NUM> in assembling the RFID device.

If the bottom thermode <NUM> is provided with a heating element <NUM>, then it may be advantageous for it to apply less heat to the RFID device than the top thermode <NUM> to further reduce the amount of damage to the fabric substrate <NUM>. For example, in one embodiment, the top thermode <NUM> may be configured to be heated to a temperature of <NUM>° C. , while all or a portion of the tip <NUM> of the bottom thermode <NUM> may be configured to be heated to a lower temperature. In one embodiment, the tip <NUM> (or a portion thereof) of the bottom thermode <NUM> may be configured to be heated to <NUM>° C. , as in a conventional "flip chip" approach. In another embodiment, the tip <NUM> (or a portion thereof) of the bottom thermode <NUM> is heated to some lower temperature, which may be dependent upon a critical temperature of the associated fabric substrate <NUM> where the visual finish is effected or distortion is caused locally. For example, if the fabric substrate is comprised of a polyester, it may have a critical temperature of approximately between <NUM>° C. and <NUM>° C. , depending on composition, the lower temperature being in the glass transition region were the material becomes soft and can easily distort under pressure, and the higher value related to melting. It will be appreciated that localized damage to the look and feel of a fabric is important to avoid for clothing in which case the tip <NUM> (or a portion thereof) of the bottom thermode <NUM> may be heated to a temperature less than a critical temperature of exemplary fabric material to minimize damage to the fabric substrate <NUM>, for example a spot or blemish. In yet another embodiment, the tip <NUM> (or a portion thereof) of the bottom thermode <NUM> may be heated to a first temperature as the tip <NUM> is penetrating the fabric substrate <NUM> and then heated to a higher second temperature once it has been moved into its final position for curing the adhesive <NUM>.

In yet another embodiment, which is illustrated in <FIG>, the bottom thermode <NUM> is configured as in <FIG>, but omits a heating element, such that the unheated bottom thermode <NUM> acts as an anvil for the RFID chip <NUM> to be pushed against as the adhesive <NUM> is cured by conduction from the top thermode <NUM>. Alternatively, the same effect may be achieved using the bottom thermode <NUM> of <FIG> without operating its heating element <NUM>. By foregoing the application of heat by the bottom thermode <NUM> and instead applying all heat using the top thermode <NUM>, even less damage is done to the fabric substrate <NUM> when curing the adhesive <NUM>.

A comparison of <FIG> illustrates different possible final positions for the bottom thermode <NUM>, <NUM> for curing the adhesive <NUM>. In the embodiment of <FIG> (in which the bottom thermode <NUM> is heated), the tip <NUM> of the bottom thermode <NUM> is moved into contact with the antenna <NUM>. This may be advantageous when the tip <NUM> of the bottom thermode <NUM> is heated to improve the application of heat from the tip <NUM> to the adhesive <NUM>. In contrast, in the embodiment of <FIG> (in which the bottom thermode <NUM> is not heated), the tip <NUM> is moved into the vicinity of the antenna <NUM>, without contacting the antenna <NUM>. As the bottom thermode <NUM> is not applying heat to the adhesive <NUM>, it is not as important for the tip <NUM> to be brought into contact with the antenna <NUM>. Additionally, moving the tip <NUM> into the vicinity of the antenna <NUM> without actually contacting the antenna <NUM> may further reduce the damage done to the fabric substrate <NUM>, as it does not penetrate completely through the fabric substrate <NUM>. However, while <FIG> illustrates a heated bottom thermode <NUM> being moved into contact with the associated antenna <NUM> and <FIG> illustrates an unheated bottom thermode <NUM> being moved only into the vicinity of the associated antenna <NUM>, it should be understood that it is within the scope of the present disclosure for a heated bottom thermode <NUM> to be moved only into the vicinity of the associated antenna <NUM> (rather than contacting it) and for an unheated bottom thermode <NUM> to be moved into contact with the associated antenna <NUM>.

<FIG> shows an alternative configuration for a pin thermode <NUM>. In the embodiment of <FIG>, the pin thermode <NUM> includes a cap or tip <NUM> and an associated body <NUM>, with the cap or tip <NUM> oriented to be closer to the associated RFID device than the body <NUM>. The pin thermode <NUM> further includes a heating element <NUM> associated with the tip <NUM> and extending at least partially through the body <NUM>. In the illustrated embodiment, the heating element <NUM> is coaxial with the body <NUM>, but it is within the scope of the present disclosure for the heating element <NUM> to be non-coaxially positioned within the body <NUM>.

The heating element <NUM> may be variously configured without departing from the scope of the present disclosure, but in exemplary embodiments is configured as either a conductive path for heat or an electrical path for a heater associated with the tip <NUM>. Regardless of its exact configuration, the heating element <NUM> is configured to increase the temperature of the tip <NUM> of the pin thermode <NUM>, as described above with respect to the embodiment of <FIG>. While the heating element <NUM> increases the temperature of the tip <NUM>, the body <NUM> is configured such that its outer surface is not heated by the heating element <NUM> or is at least not heated to the same temperature as the tip <NUM>. In embodiments in which heat is passed through the body <NUM> (i.e., when the heating element <NUM> comprises a conductive path for heat), the body <NUM> may be made of a low thermal conductivity material, such as, but not limited to PTFE or a foamed PTFE, to limit the change in temperature at the outer surface of the body <NUM> so that less heat is applied to a fabric substrate it has penetrated. In one embodiment, a material with a low friction surface is utilized as it will slide through the fabric with less force and potential to cause damage.

<FIG> show another alternative embodiment of a pin thermode <NUM> according to an aspect of the present disclosure. In the embodiment of <FIG>, the pin thermode <NUM> includes a tip <NUM> and a body <NUM>, as in other embodiments. The pin thermode <NUM> further includes an actuator <NUM>, which is operable to move the tip <NUM> (or at least a portion thereof) between a first configuration (<FIG>) and a second configuration (<FIG>) in which the tip <NUM> has a different cross-sectional area. The first configuration is intended for easy penetration of a fabric substrate, while the second configuration is intended for increasing the area over which the tip <NUM> contacts or otherwise applies force to an RFID device during curing of its adhesive.

The particular configuration of the tip <NUM> may vary, which may also affect the particular configuration of the associated actuator <NUM>. In one embodiment, the tip <NUM> is formed of a deformable or flexible material (e.g., an elastomeric material) secured to a distal end <NUM> of the body <NUM>. In such an embodiment, the actuator <NUM> may be configured as an elongated rod with an enlarged end <NUM>, which is moved proximally to compress the tip <NUM> against the distal end <NUM> of the body <NUM>, causing the tip <NUM> to expand outwardly for an enlarged cross-sectional area. In another embodiment, the tip <NUM> is formed of a plurality of rigid or semi-rigid members configured as petals pivotally or otherwise movably connected to the distal end <NUM> of the body <NUM>. In such an embodiment, the actuator <NUM> may be moved proximally to deploy the individual members or may be manipulated in some other manner (e.g., by being rotated about its central axis) to deploy the individual members to the expanded configuration of <FIG>. Other configurations of the tip <NUM> may also be employed without departing from the scope of the present disclosure, with the optimal configuration depending on any of a number of factors, such as the thickness and material composition of the associated fabric substrate, the cross-sectional area of the associated RFID, and whether the tip <NUM> is to be heated.

<FIG> show another alternative embodiment of a pin thermode <NUM> according to an aspect of the present disclosure. In the embodiment of <FIG>, the pin thermode <NUM> includes a body <NUM> and an associated tip <NUM>, with the tip <NUM> being comprised of a plurality of projections <NUM> (which may be heated or unheated) that separately penetrate an associated fabric substrate. In the illustrated embodiment, the projections <NUM> are substantially identical (to better ensure a uniform application of pressure and/or heat to the RFID device) and extend in parallel (to better ensure penetration through the fabric substrate), but it is within the scope of the present disclosure for at least two of the projections <NUM> to be differently configured and/or for at least two of the projections <NUM> to be non-parallel. It may be advantageous for the projections <NUM> to be sufficiently elongated so as to be capable of penetrating entirely through the associate fabric substrate without the body <NUM> of the pin thermode <NUM> also penetrating the fabric substrate in order to minimize any damage caused to the fabric substrate. However, it is also within the scope of the present disclosure for both the projections <NUM> and a portion of the body <NUM> to penetrate the fabric substrate.

<FIG> illustrates the positions of the projections <NUM> with respect to an associated RFID chip <NUM> and antenna <NUM>, which may correspond to the positions of the conductive connections of the RFID chip <NUM>, such that each projection <NUM> applies pressure to one of the conductive connections. However, it should be understood that the positions of the projections with respect to the conductive connections of an associated RFID chip may vary without departing from the scope of the present disclosure, provided that the selected points at which the projections apply pressure and/or heat to the RFID device is sufficient to form an acceptable bond between the RFID chip and the antenna.

<FIG> shows the assembly of an RFID device using another embodiment of a pin thermode <NUM> according to an aspect of the present disclosure. In the embodiment of <FIG>, the pin thermode <NUM> (which may be heated or unheated) includes a tip <NUM> and an associated body <NUM>. The body <NUM> defines a lumen <NUM>, with at least one aperture <NUM> in fluid communication with the lumen <NUM> being defined in the tip <NUM> and/or the body <NUM>. In one embodiment, a plurality of apertures <NUM> are uniformly positioned around the perimeter of the body <NUM> and/or tip <NUM>, but it is also within the scope of the present disclosure for there to be only one aperture <NUM> or for a plurality of apertures <NUM> to be arranged in a non-uniform pattern.

The pin thermode <NUM> further includes a liquid source from which a liquid may be advanced into and through the lumen <NUM> to the aperture or apertures <NUM>. From the aperture or apertures <NUM>, the liquid is advanced out of the pin thermode <NUM> and into the region surrounding the pin thermode <NUM> (e.g., into a gap defined in the antenna <NUM> or into the fabric substrate <NUM>). The nature of the liquid may vary, which may affect the optimal position of the aperture or apertures <NUM>. For example, the liquid may be an adhesive that is the same as or similar to the adhesive <NUM> positioned between the RFID chip <NUM> and the antenna <NUM>. In this case, it may be advantageous for at least one aperture <NUM> to be defined in the tip <NUM> so as to apply the adhesive to the RFID device. In another embodiment, the liquid may be an adhesive or varnish or flexible material, such as silicone rubber, which prevents moisture ingress. In this case, it may be advantageous for at least one aperture <NUM> to be defined in the body <NUM>, such that a portion of the liquid may be applied to the fabric substrate <NUM> to strengthen and seal the region of the fabric substrate <NUM> penetrated by the pin thermode <NUM>.

In one embodiment, the bottom pin is unheated and used as an anvil and the top pin is also unheated and used as an anvil to apply pressure, but has an optical path such as a fibre down through the centre to pass light, in particular infra-red, where wavelengths between approximately <NUM> and <NUM> are strongly adsorbed, that, once the chip is under pressure, applied infra-red light causes the chip to heat itself and cure the adhesive. Alternatively the bottom pin, top pin or both are made of an optically transparent material such as a glass.

In a further embodiment of the present invention, the adhesive to bond the chip cures when ultra violet light is applied via an optical path is incorporated into the bottom pin thermode.

In a further embodiment, the bottom pin thermode may transfer a catalyst, a curing agent and/or an accelerator either applied to the tip of the thermode or passed through a channel, into the adhesive, causing rapid curing, which may be exothermic to also heat the chip and adhesive to complete the bond. Curing agents can be latent, in that they are mixed with the adhesive, and activated, where a curing agent can be added as a two-part system. A range of chemical types can be used as curing agents, for example amines, anhydrides, phenol and thiols, and accelerators/catalysts added to latent curing mixtures, such as tertiary amines and alcohols. As the curing process for the epoxy adhesive can be highly exothermic, the pin thermodes may be of a high thermal conductivity and, depending on the amount of heat generated, cooled, to limit the peak temperature of the joint and chip to prevent damage to the substrate.

In a further embodiment the heat needed to cure the adhesive is provided by passing ultrasonic energy into the chip and hence the adhesive and antenna when they are in contact, where the mechanical energy is converted into thermal energy curing the adhesive and completing the joint between antenna and chip.

Claim 1:
A pin thermode (<NUM>) for connecting an RFID chip to an antenna mounted to a fabric substrate, the pin thermode comprising:
a body (<NUM>);
a tip (<NUM>) mounted to the body and configured to penetrate the fabric substrate so as to be moved into contact with or into the vicinity of the antenna; and
a heating element (<NUM>) integrated into the tip and extending at least partially through the body.