The present invention relates to radio frequency identification (RFID) antennas, and more particularly to application of RFID antennas to packaging.
Integrated circuits (ICs) are the basic building blocks that are used to create electronic devices. Continuous improvements in IC process and design technologies have led to smaller, more complex, and more reliable electronic devices at a lower cost per function. As performance has increased and size and cost have decreased, the use of ICs has expanded significantly.
One particular type of IC that would benefit from inexpensive mass production involves the use of radio frequency identification (RFID) technology. RFID technology incorporates the use of electromagnetic or electrostatic radio frequency (RF) coupling. Traditional forms of identification such as barcodes, cards, badges, tags, and labels have been widely used to identify items such as access passes, parcels, luggage, tickets, and currencies. However, these forms of identification may not protect items from theft, misplacement, or counterfeit, nor do they allow “touch-free” tracking.
More secure identification forms such as RFID technology offer a feasible and valuable alternative to traditional identification and tracking. RFID does not require physical contact and is not dependent on line-of-sight for identification. RFID technology is widely used today at lower frequencies, such as 13.56 MHz, in security access and animal identification applications. Higher-frequency RFID systems ranging between 850 MHz and 2.5 GHz have recently gained acceptance and are being used in applications such as vehicular tracking and toll collecting, and in business logistics such as manufacturing and distribution.
Traditionally, antennae for RFID tags are designed primarily to function as collectors of RF energy to promote tag function. In some applications, a printing process is used to print conductive traces on a substrate to form a functional electronic structure such as an RFID antenna. The RFID antenna absorbs, couples with, and/or reflects radio frequency signals from a transmitter and provides a signal and power to an attached integrated circuit.
The radiation, or gain pattern, of the antenna impacts the performance of the antenna. RFID tags with traditional antennae are applied inside a package or product, applied underneath a self adhesive label containing graphics, and/or located on top of the package or product. The RFID tags are typically applied to a single surface of a multi-surface package. The antenna structure is two-dimensional and is inherently limited in the directionality of the radiation pattern. In other words, the two-dimensional antenna structure has a void in one dimension. As a result, the antenna device is sensitive to the orientation with the reader antenna. In other words, the orientation of the antenna is limited to the position of the package in relation to the reader antenna. In addition to orientation sensitivity, materials within the package, such as metals and/or liquids, may further interfere with the operation of the antenna.
An RFID system comprises a packaging substrate that has a first surface and at least one second surface. An antenna is formed on the packaging substrate and includes a first conductive trace and at least one second conductive trace, wherein at least one of the conductive traces is formed on the first surface and the at least one second surface. An integrated circuit is connected across the first conductive trace and the at least one second conductive trace on the first surface. The packaging substrate has an unfolded state wherein the first surface and the at least one second surface are substantially coplanar. The packaging substrate has a folded state wherein the first surface and the at least one second surface are not coplanar.
In another aspect of the invention, a method of printing is disclosed for printing an RFID antenna operable to function in three dimensions comprises forming an antenna that includes a first conductive trace and at least one second conductive trace on an unfolded packaging substrate having a first surface and at least one second surface. An integrated circuit is connected across the first conductive trace and the at least one second conductive trace. The unfolded packaging substrate is formed into a package wherein the first surface and the at least one second surface are not coplanar. The integrated circuit and portions of the first conductive trace and the at least one second conductive trace are formed on the first surface and a portion of at least one of the first and/or second conductive traces is formed on the at least one second surface.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.
Referring now to
The RFID system 10 is typically applied to a single surface 30 of a package 32 as shown in
The present invention integrates a three-dimensional antenna structure with product packaging, resulting in substantial improvements to orientation sensitivity, environmental robustness, and potential antenna design innovation. The antenna 14 is printed directly to a package substrate 40 prior to folding the package substrate 40 into its final form as shown in
After the antenna 14 is printed on the package substrate 40, the package substrate 40 is folded into a package 56 as shown in
Additionally, ultra-high frequency (UHF) antennas generally function at ½ or ¼ of the RF wavelength used to communicate with or power the RFID tag due to size limitations. Although full-wave antennae provide higher gain, the size constraints related to printing conventional antennae on a single side of a package limit the practicality of full-wave antennae. Three-dimensional antennae as described herein are able to cover larger areas, providing full or, in certain applications, double wavelength antenna capabilities.
Further embodiments of antennae 14 printed on two or more sides 42 of package substrates 40 are shown in
These antennas can be manufactured using printing processes, such as, but not limited to: gravure, offset gravure, flexography, offset lithography, letterpress, ink jet, flatbed screen, and/or rotary screen printing. Furthermore, the antenna can be patterned using etching, stamping, or electrochemical deposition (such as electrolysis or electroplating) of metals.
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the current invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.
This patent application claims priority from U.S. Provisional Patent Application No. 60/717,155, filed Sep. 15, 2005, and entitled “RFID ANTENNA ON MULTIPLE SIDES OF 3-D PACKAGING”.
Number | Date | Country | |
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60717155 | Sep 2005 | US |