MXPA00003396A - High temperature rfid tag - Google Patents

Abstract

A high temperature RFID tag (10,20) is described which has a survival temperature in the range of approximately -40°C to 300°C and an operating temperature of approximately -20°C to 200°C. The RFID tag comprises a housing (21) comprising a first thermally resistant material and having a base (24) and a top (22), and a circuit board substrate (26) which includes an IC circuit (28) and is disposed in a tag chamber (36), the substrate comprising a second thermally resistant material which is encapsulated in the housing. The thermally resistant materials exhibit a deflection temperature in a range of 287°C to 320°C.

Description

HIGH TEMPERATURE RADIO FREQUENCY IDENTIFICATION LABEL (RFID) FIELD OF THE INVENTION - ~ _ The present invention relates in general to radio frequency identification (RFID) devices, and more particularly to a high temperature RFID tag. BACKGROUND OF THE INVENTION RFID systems are well known in the art. These systems include relatively large packets containing a set of battery-driven transmit and receive circuits, such as the identification system disclosed in the U.S. Patent. No. 4,274,083, for passive systems in which the transceiver receives its power from the base station or interrogator, such as the identification system disclosed in the U.S. Patent. No. 4,654,658. A typical RFID system is made up of reusable labels fixed or embedded in product carriers, antennas that interrogate the labels by means of a radio frequency (RF) link and a controller. The host system (or computer) interconnects with the controller and directs the interrogation of the labels. RFID tags provide effective means of identifying, monitoring and controlling materials in a closed loop process. At the factory, labels are used as the transport mechanism between the "islands of automation", providing a record of each process that can be influenced immediately or transferred later for analysis. The labels can be fed by means of an internal battery (for example, an "active" label) or by an inductive coupling (for example, a "passive" label). Passive tags do not need maintenance and virtually have unlimited life. Either way, the life span of an active label is limited by the battery's lifetime, although some labels offer replaceable batteries. RFID tags are packaged in a variety of ways and are subject to a multitude of means. Labels are usually encapsulated for durability against bumps, fluids, dust or dirt. Although these labels are immune to almost all environmental factors, they can, in many cases, be adversely affected by high temperature environments. It is, therefore, an object of the present invention to provide an RFID tag that has the ability to operate over a wide range of temperatures. It is another object of the invention to provide an RFID tag that is capable of operating in harsh and high temperature factory environments. SUMMARY OF THE INVENTION The high temperature RFID tag of the present invention has a substantially increased survival temperature in the range from -40 ° C to 300 ° C.

The label also has a unique operating temperature in the range of -18 ° C to 135 ° C. In accordance with the objects and advantages of the present invention, the high temperature RFID tag comprises: - A housing having a base and an upper part, the base and the upper part forming a chamber therein, the housing comprising a first thermally resistant material; and a printed circuit board substrate placed inside the chamber, the substrate includes an integrated circuit, the substrate comprises a second thermally resistant material; the housing and the printed circuit board have a varying survival temperature of about -40 ° C to 300 ° C. BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the following, more particular description of the preferred embodiments of the invention become evident, as illustrated in the accompanying drawings, and in which, like the characters mentioned , generally refer to the same parts or elements in all views, and in which: FIGURE 1 is a schematic illustration of a typical RFID system; FIGURE 2 is a perspective view of a high temperature RFID tag according to the invention; and FIGURE 3 is an exploded perspective view of the high temperature RFID tag shown in FIGURE 2. DETAILED DESCRIPTION OF THE INVENTION The high temperature RFID tag of the present invention substantially reduces or eliminates the disadvantages and shortcomings associated with the RFID tags of the prior art. According to the invention, a thermally resistant housing (e.g., high temperature) having a base and an upper part, and therein is provided a printed circuit board substrate having an integrated circuit (IC), to achieve the Unique survival temperatures and high temperature performance capabilities of the label. The term "operating temperature", as used herein, means the temperature (and / or variation thereof) at which the label can perform the intended functions.The intended functions include reading, writing and filling functions. term "survival temperature" means the temperature (and / or variation thereof) at which the label can be exposed without adversely affecting the performance characteristics of the label when returning to an operating temperature. 1, a simple read / write RFID system is shown. The system normally comprises one or more tags (or transponders) 10, which contain some data in memory, at least one antenna 12 for communicating with the tags 10, and a controller 14 for handling the communication interface. The guest system 16 interconnects with the controller 14 and directs the interrogation of the labels 10 placed or embedded in the carriers of the product 11 and any subsequent action by parallel, serial or bus communications 18. Referring now to FIGURE 2, it is shown ^ a perspective view of a preferred embodiment of the high temperature RFID tag 20 of the present invention. In the annotated embodiment, the tag 20 comprises a passive read / write tag. Either way, as will be appreciated by someone _ who has common skill in the art, the concepts of the illustrated embodiment can be incorporated into the active manufacturing systems. As illustrated in FIGURE 2, the label 20 preferably has a substantially cylindrical shape, with a variation diameter of approximately .25in. -a 5.0in., preferably l.Oin. approximately. In this way, the label 20 is capable of being added or embedded in various surface configurations and in limited surface areas. In further conceived embodiments of the invention, not shown, the tag has a substantially square shape. According to the present embodiment, the dimension of the surface of the label is preferably in the variation of 1 in_. to 3 in. (for example, 1 in. X I in., 2 in. X 2 in., 3 in. X 3 in.). As will be appreciated by one of ordinary skill in the art, the high temperature label of the present invention may comprise several forms. The labels may also include several conventional joining means.

According to the invention, the housing of the label 21 preferably includes a housing base 24 and an upper part 22 (see Figure 3). In further conceived embodiments of the invention, not shown, the housing 21 may also comprise a one-piece molded unit. As illustrated in FIGURE 3, the base 24 comprises a substantially cylindrical lower portion 25 with a circumferential wall 28 positioned on the outer edge, defining a label chamber 30 therein. The wall 28 preferably includes a bushing seat 29 which is adapted to place the housing bushing 22 in one location. The base 24 includes a plurality of inwardly projecting suspension pins 32, positioned on the inner surface of the part. bottom of the base 25. The pins 32 are adapted to support the printed circuit board substrate 26 when placed on the base 24. As illustrated in FIGURES 2 and 3, the upper part of the housing 22 has a "cylindrical" shape corresponding, substantially similar The bushing 22 is provided with a lower gear portion 27, which is adapted to slidely engage the inner surface of the bushing seat 29. A key feature of the present invention is the unique high temperature resistance of the housing 21. According to the invention, the housing 21 comprises a material of high thermal resistance, such as Teflon® ou n Ryton®PPS compound, which can be exposed to high temperatures without materially affecting the properties of the material and / or its characteristics. In a preferred embodiment, the housing comprises the Ryton®PPS compound, R-4 02XT. The thermally resistant materials exhibit a deflection temperature in a variation of 287 ° C to -320 ° C. In the label chamber 30, the printed circuit board substrate 26 is placed. The substrate includes an IC circuit 28 preferably placed on a surface thereof. As stated, the base 24 is provided with suspension pins 32 for positioning the printed circuit board 26 in the base 24. As illustrated in FIGURE 3, the printed circuit board 26 similarly has the substantially cylindrical shape and is adapted to be placed within the label chamber 30. According to the invention, the IC circuit 28 comprises copper and other similar material and is plated to the printed circuit board 26 by conventional means. Circuit IC 28 is punch-connected to the printed circuit board 26 by gold solder and is encapsulated using a high temperature epoxy, such as Eccobond® "104." The annotated materials exhibit excellent performance characteristics. over a wide temperature variation and, therefore, protect the circuit 28 at elevated temperatures In accordance with the invention, the printed circuit board 26 Similarly, it is a high thermal resistance material, such as a preconditioned polymer or a ceramic compound. In a preferred embodiment, the printed circuit board 26 comprises a preconditioned polymide having a Tg of 300 ° C. Referring to FIGURE 2, the upper part of the housing 22 is molded oppositely to the base of the housing 24, encapsulating the printed circuit board 26 therein. According to the invention, the upper part 22 is injection molded to the base 24 to provide an effective encapsulation. As will be appreciated by one of ordinary skill in the art, various encapsulation methods may be employed within the scope of the invention, such as the one-piece molded housing, which is discussed above. The successor in title has found that the high-temperature RFID tag of the present invention has a survival temperature variation of about 40 ° C to 300 ° F and exhibits superior performance characteristics over the operating temperature variation of about -18 °. C at 135 ° C., the labels can be used in various environments and / or high temperature industrial operations, such as painting and engine manufacturing operations, which have not been possible with prior art labels. While the preferred embodiments and their technical advantages have been described above in detail and illustrated in the drawings, the present invention is not limited to this, but only to the extent and spirit of the appended claims.

Claims (16)

1. R E I V I N D I C A "C I O N S 1. A high temperature RFID tag, comprising: a housing having a base and upper part, the base and the upper part forming a chamber therein, the housing comprises a first thermally resistant material; and a printed circuit board substrate within the chamber, the substrate includes an integrated circuit, the substrate comprises a second thermally resistant material; the housing and the substrate as a whole have a survival temperature varying from about 220 ° C to 300 ° C.
2. 2. The RFID tag of Claim 1, wherein the tag has an operating temperature in the range of -18 ° C to 135 ° C.
3. 3. The RFID tag of Claim 1, wherein the printed circuit board is substrate encapsulated in the housing. _
4. 4. The RFID tag of Claim 3; wherein the high temperature epoxy is used to encapsulate the printed circuit board substrate.
5. 5. The RFID tag of Claim 1, wherein the first thermally resistant material consists of TefIon®.
6. 6. The RFID tag of Claim 1, wherein the first thermally resistant material consists of the Ryton®PPS compound.
7. The RFID tag of Claim 1, wherein the second thermally resistant material consists of a polymide.
8. 8. The RFID tag of Claim 7, wherein the polymide is preconditioned.
9. 9. The RFID tag of Claim 1, wherein the second thermally resistant material comprises a ceramic composite.
10. 10. The RFID tag of Claim 1, wherein the housing has a substantially cylindrical shape.
11. 11. The RFID tag of Claim i; wherein the housing has a substantially square shape.
12. 12. An RFID tag, comprising: a housing and substrate assembly, the housing having a base and an upper part, the base and the upper part forming a chamber therein, the housing comprising a first thermally resistant material, the The substrate is placed inside the housing chamber and includes an integrated circuit, the substrate comprising a second thermally resistant material, the assembly of the housing and the substrate have a "survival temperature varying from about 220 ° C to 300 ° C and a variation of operating temperature of about 18 ° C to 135 ° C, the housing and substrate assembly capable of being exposed to cyclic changes in temperature up to and between operating temperature and survival temperature without substantially affecting the functions of the
13. 13. The RFID tag of Claim 12, wherein the substrate is encapsulated in the housing with a high temperature epoxy.
14. 14. The RFID tag of Claim 12, wherein the first thermally resistant material comprises a Ryton®PPS compound.
15. 15. The RFID tag of Claim 12, wherein the second thermally resistant material comprises a preconditioned polymer.
16. 16. The RFID tag of Claim 12, wherein the second thermally resistant material comprises a ceramic composite.