RFID interposer with impedance matching
An RFID interposer has conductive material that includes an impedance matching structure. The impedance matching structure aids in matching impedance between a chip that is to be mounted to the interposer, and an antenna that the interposer is to be coupled to. The impedance matching structures may allow different chips, with slightly different electrical characteristics, to be impedance matched to the same antenna configuration, using the same type of interposer. The impedance matching structure may have any of a variety of configurations in the electrically conductive material of the interposer. The structure may be parts of the chip mounting bond pads, may be part of the conductive electrical connection between the chip bond pads and antenna bond pads, may be part of connections between the chip bond pads and the antenna bond pads, and/or may be only indirectly electrically coupled to the antenna bond pads (such as by capacitive coupling).
1. A radio frequency identification device (RFID) interposer comprising:
a dielectric substrate;
electrically conductive material on a major surface of the substrate;
wherein the electrically conductive material includes an impedance matching structure;
chip bond pads for receiving and electrically coupling one or more chips to the electrically conductive material and antenna bond pads for electrically coupling the electrically conductive material to an antenna;
and wherein the impedance matching structure includes a shunt electrically coupling the antenna bond pads together.
2. The RFID interposer of claim 1 , wherein the impedance matching structure includes one or more series inductors electrically coupling the chip bond pads to the antenna bond pads.
3. The RFID interposer of claim 1 , wherein the shunt provides a conductive pathway between the antenna bond pads.
4. The RFID interposer of claim 1 , wherein the shunt includes a capacitor/inductor that is indirectly capacitively electrically coupled to at least one of the antenna pads, without a direct electrical connection.
5. The RFID interposer of claim 1 , wherein the impedance matching structures includes the chip bond pads having a configuration to electrically interact differently with internal mechanical structures of different chips to be coupled to the chip bond pads.
6. The RFID interposer of claim 1 ,
wherein the chip bond pads allow coupling of the chip in more than one location; and
wherein the impedance matching structure has electrical characteristics that change depending upon where the chip is coupled to the chip bond pads.
7. The RFID interposer of claim 6 , wherein the chip bond pads allow coupling of the chip in multiple discrete locations.
8. The RFID interposer of claim 6 , wherein the chip bond pads allow coupling allow a continuous range of chip mounting locations of the chip.
9. The RFID interposer of claim 1 , wherein the impedance matching structure is a tunable impedance matching structure with tunable electrical characteristics.
10. The RFID interposer of claim 9 , wherein the tunable impedance matching structure is configured to be tuned by physically altering one or more portions of the interposer.
11. The RFID interposer of claim 1 , in combination with a chip and an antenna, each coupled to the interposer to form an RFID device.
12. The combination of claim 11 , wherein the antenna includes an antenna impedance matching structure.
13. A method of making an RFID device, the method comprising:
patterning an electrically conductive material having an impedance matching structure with an inductor shunt;
coupling an RFID chip having chip bond pads for receiving and electrically coupling the RFID chip to an RFID interposer with the impedance matching structure, and
coupling the RFID interposer to an antenna.
14. The method of claim 13 , wherein the coupling the chip to the interposer includes having the impedance matching structure compensate for electrical characteristic differences between different types of chips and electrical characteristic differences of the interposer and the different types of chips.
15. A radio frequency identification (RFID) device comprising:
a first substrate having a first face and a second face;
an antenna on one of the faces;
a second substrate attached to the first substrate;
chip bond pads for receiving and electrically coupling one or more chips to the second substrate;
an impedance matching structure on the second substrate;
wherein the impedance matching structure is electrically coupled to the antenna and has electrical characteristics that change depending upon where the chip is coupled to the chip bond pads.
16. An RFID device comprising:
a package having an antenna on a surface of the package; and
an interposer that includes:
a substrate;
an electrically conductive material on a major surface of the substrate, the electrically conductive material including an impedance matching structure that includes a shunt;
chip bond pads for receiving and electrically coupling one or more chips to the substrate;
antenna bond pads for electrically coupling the electrically conductive material to an antenna; and
wherein the impedance matching structure is coupled to the antenna.