FORM-2
THE PATENTS ACT. 1970 (39 of 1970)
COMPLETE SPECIFICATION (Section 10, rule 13)
"A Method of Manufacturing RFID Label Antenna using Dual
Technology"
M-Tech Innovations Ltd
with our principle place of business at Mahavir Chambers, 12 Premanand Society, Balajinagar, Pune-Satara Road, Pune 411043, Maharashtra, India.
an Indian Company registered under the provisions of the Companies Act, 1956.
The following specification particularly describes the nature of the invention and the manner in which it is to be performed: -
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FIELD OF INVENTION:
The present invention relates to a design of RFID label antennas using Dual Technology.
More particularly the present invention seeks to provide RFID label antennas by Dual technology process which would have more flexibility in the label design, reduce material wastage & make the RFID label more cost effective.
Still particularly, this invention relates to a design of RFID label antennas with no open circuits in the antenna and with the contact resistance of the conductive traces Etched as the RFID label antenna maintained in significant range to give better tag performance.
BACKGROUND OF THE INVENTION:
This method of manufacturing RFID label antennas has changed a great deal since the early days of manufacturing RFID labels. Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to automatically identify people or objects. Radio Frequency IDentification (RFID) is a method of storing and remotely retrieving data using devices called RFID tags or transponders. RFID tags consist of two essential components - a chip and an antenna. An RFID tag is a small object that can be attached to or incorporated into a product, animal, or person. RFID tags contain antennas to enable them to receive and respond to radio-frequency queries from an RFID
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transceiver. Passive tags require no internal power source, whereas active tags require a power source.
The technology used in RFID has been around since the early 1960's. Conventionally, RFID tags can be either active or passive. Passive RFID tags have no internal power supply. The minute electrical current induced in the antenna by the incoming radio frequency signal provides just enough power for the tag to transmit a response. Due to limited power and cost, the response of a passive RFID tag is brief— typically just an ID number. Lack of an onboard power supply means that the device can be quite small. Passive tags have practical read distances ranging from about 10 mm up to about 6 metres.
Active RFID tags, on the other hand, have an internal power source, and may have longer range and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. Many active tags have practical ranges of tens of metres, and a battery life of up to 10 years. Because passive tags are cheaper to manufacture and have no battery, the majority of RFID tags in existence are of the passive variety.
The conventional method of coil winding process of manufacturing the RFID label antennas (which is a part of the tag as explained above) is done by laying a suitable coil in the specified format to make a RFID label antenna. The gap between two tracks of the antenna need to be uniform throughout and the same is difficult to maintain consistently.
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Many researchers and technicians have experimented with alternate RFID label antenna manufacturing method. One such alternate method is the etching process the copper material is etched from the copper sheet and only the copper material required for laying the label antenna is kept on the substrate. In this process there is a heavy loss of the material since the unwanted material needs to be etched out which is of no use after etching.
Up to now, RFID technology has been too expensive and too limited to be practical for many commercial applications. But if tags can be made cheaply enough, they can solve many of the problems associated with bar codes. Radio waves travel through most non-metallic materials, so they can be embedded in packaging or encased in protective plastic for weather-proofing and greater durability. And tags have microchips that can store a unique serial number for every product manufactured around the world.
PRIOR ART:
A U.S. Patent No. 6,951,596 claims, "A method of forming an RFID article, the method comprising the steps of: providing an RFID webstock of polymeric material having a plurality of recesses, each of the recesses containing an RFID chip; providing a second web having antennas as spaced thereon; dividing the RFID webstock into a plurality of sections, each of the sections including one or more of the RFID chips and a portion of the polymeric material; indexing the pitch of the RFID sections from high density on said RFID webstock, to a relatively low density on an RFID inlay stock; and
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attaching the sections to the antennas in an automatic continuous process, so that each of the RFID chips is adjacent to one of the antennas to form the RFID inlay stock.
A U.S. Patent No. 6,451,154 claims, "A method of making RFID labels, comprising: (a) providing a plurality of RFID inlets, each including a chip, on a first web; (b) covering the RFID inlets with a second web to provide a composite web; (c) providing pressure sensitive adhesive on a portion of one of the webs that will be an exterior portion of a label once ultimately formed; (d) at least one of verifying the functionality of, or programming, the chips prior to formation of the composite web; and (e) acting on the composite web so as to provide the composite web into labels having a top face, and a bottom face with pressure sensitive adhesive, wherein (b) is practiced by laminating the first and second webs by passing them between laminating rolls without harming the inlets, wherein (b) is practiced without harming the chips by providing a recess in at least one of the laminating rolls in alignment with the inlets.
A U.S. Patent No. 7,014,729 claims, "A method of making RFID labels, comprising: (a) providing a plurality of RFID inlets, each including a chip, on a first web; (b) covering the RFID inlets with a second web, to form a composite web; (c) laminating a third web onto the composite web by passing the webs between laminating rolls to sandwich the inlets between the second and third webs without harming the inlets, by providing a recess in at least one of the laminating rolls in alignment with the inlets; (d) providing pressure sensitive adhesive on a portion of one of the webs that will be an
exterior portion of a label once ultimately formed; and (e) acting on the composite web so
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as to form the composite web into labels having a top face, and a bottom face with pressure sensitive adhesive.
A U.S. Patent No. 7,045,186 claims, "An RFID label made according to a method comprising: (a) providing a plurality of RFID inlets, each including a chip, on a first web; (b) covering the RFID inlets with a second web; (c) laminating a third web onto the second web by passing the webs between laminating rolls to sandwich the inlets between the second and third webs without harming the inlets, to provide a composite web; (d) providing pressure sensitive adhesive on a portion of one of the webs that will be an exterior portion of a label once ultimately formed; and (e) acting on the composite web so as to provide the composite web into labels having a top face, and a bottom face with pressure sensitive adhesive.
A U.S. Patent No. 6,940,408 claims, "A radio frequency identification (RFID) inlay comprising: an inlay substrate; an antenna on the inlay substrate; a strap, wherein the strap includes: an RFID chip having contacts thereupon; and strap leads operatively coupled to the contacts of the chip; a nonconductive adhesive attaching the strap to the inlay substrate; and a conductive connection operatively coupling the strap leads and the antenna; wherein the conductive connection includes conductive bumps attached to the strap.
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A U.S. Patent No. 6,853,087 claims, "An RFID device comprising: a first electrical component having a first electrically conductive contact; a second electrical component having a second electrically conductive contact; wherein the first and second electrically conductive contacts are in alignment with one another at least one electrically conductive hard particle attached without an adhesive to at least one of the first and second electrically conductive contacts, wherein the at least one electrically conductive hard particle has a hardness at least as great as that of at least one of the first and second electrically conductive contacts; a non-conductive adhesive disposed between the first and second electrically conductive contacts; wherein the first and second electrically conductive contacts are held together by the non-conductive adhesive once the adhesive cures; wherein a permanent electrical connection is formed between the first and second electrically conductive contacts; and wherein a permanent physical attachment is formed between the first electrical component and the second electrical component".
These systems and methods of manufacturing RFID Label antennas are complex and are lacking in the development of high quality RFID Label antenna. Most of the above apparatus, systems and methods of manufacturing RFID Label antennas have concentrated only in the area of printer technology but not on screen printing thereby effectively hiking the price of such RFID label antennas.
This process of manufacturing RFID label antennas using dual Technology is done by Silk screen printing method. Printing technology is used for manufacturing the
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RFID label antenna ahead of other techniques like Etching or coil winding. The
manufacturing process is carried out at & sponsored by M-Tech Innovations Ltd.
Ideally, RFID label antenna should not have problems of maintaining consistency in coil laying or maintaining uniform gap between two tracks of the antenna or instances of heavy loss of the material since the unwanted material while etching.
In recent years, considerable attention has been directed towards developing such RFID label which would be efficient, inexpensive to manufacture and overcomes all the technical difficulties. The conventional methods of manufacturing RFID labels did try to overcome drawbacks to a certain extent but did not complete satisfy the current standards and expectations.
The objective of the present invention is to provide for a RFID label which has consistency in coil laying.
Another objective of the present invention is to provide for a RFID label which maintaining uniform gap between two tracks of the antenna.
Another objective of the present invention is to provide for a RFID label which has consistency in coil laying.
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Another objective of the present invention is to provide for a RFID label which would avoid or overcome instances of heavy loss of the material since the unwanted material while etching.
DESCRIPTION OF PRESENT INVENTION:
Radio Frequency Identification (RFID) labels are used for the applications like Library management, Access control systems, Inventory Control, Jewelry Management systems etc., RFID label consists of an antenna and a chip where the antenna design varies as per the size and application requirements. RFID Labels fall into two broad categories: passive and active. Passive labels are the most simple and consist of the components mentioned above. They obtain power from the radio frequency field of the reader, and therefore don't require an integrated power source. This makes them the most inexpensive tag. Active tags use an on-board power source to achieve either greater range or the ability to record data from a sensor. These tags are usually more complex and therefore cost more.
The antenna of RFID label can be manufactured using the following techniques:-
a) Etching
b) Coil winding
c) Printing
RFID labels comprise two essential components: a silicon chip and an antenna. The chip receives and transmits data, such as a product identification number, via the
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antenna. The data on the chips can be accessed by a radio frequency signal created by a "reader", an electronic module connected to its own antenna and a computer network. The reader sends a specific signal to RFID tags in the immediate area. These tags then respond with an answer, again, such as their unique identification number, which the reader processes and conveys to a computer network.
The major drawbacks while manufacturing the RFID label antenna by Coil winding & Etching process are:-
a) Coil winding process:-
In the coil winding process is done by laying a suitable coil in the specified format to make a RFID label antenna. The limitation of coil winding process is that it is not feasible to use for the UHF RFID labels where the area of antenna is much higher and the consistency in coil laying cannot be maintained. The gap between two tracks of the antenna need to be uniform throughout and the same is difficult to maintain consistently.
b) Etching process:-
In the etching process the copper material is etched from the copper sheet and only the copper material required for laying the label antenna is kept on the substrate. In this process there is a heavy loss of the material since the unwanted material needs to be etched out which is of no use after etching.
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BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS:
In the present invention, the RFID label antenna is manufactured by Dual Technology consisting of first Etching process and then two layer by printing process using modern screens of aluminum frames with a polyester fabric (screen cloth) stretched across them.
Screen printing is basically a printing process that involves covering the surface to be printed with a material like synthetic fiber or polyester or nylon into which opening have been cut. Because silk was the earliest material stretched across a frame to create a screen, the process became known as Silk Screen Printing. This term is still used today despite the fact that most screens are made of synthetic fibers which are more durable and not as subject to change.
Screen printing is the most versatile color medium. Any conceivable color can be screen printed. Screen printing inks are available to create finishes which range from matted to high gloss; and only with screen printing can ink be laid down so transparently it is almost invisible, or so thick that it appears to be a block print. Screen printing is unparalleled in color and texture versatility. This means that it can be used to print on many different types of surfaces and not confined to paper. Screen printing inks have been designed to be applied to almost any surface: glass, fabric, wood, metal, plastic and many more.
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The entire manufacturing processes of the RFID label by the Dual Technology consist of two process of Etching and Screen making.
The Etching process is divided into 2 parts:
I. Artwork preparation;
II. Filming;
III. Etching by using Copper;
The entire manufacturing by printing process is divided into 4 parts:
I. Artwork preparation;
II. Screen making;
III. Printing;
IV. Testing and
V. Chip bonding.
I. Artwork preparation:
The graphics to be printed on the base substrate is prepared on the computer to the desired dimensional specification. In this case the RFID label antenna is designed so as to go ahead for the printing purpose.
II. Screen making:
a) Screen
The screens used in this type of printing are commonly made of aluminum or wood frame in the shape of a square or rectangle. It is covered on one side with a
tightly stretched and tightly woven mesh fabric. This mesh consists of many different
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thread counts that range anywhere from 100 to 400 threads per inch. For printing of RFID label antenna a screen of 90T to 120T is recommended. (90T means 90
Threads in one centimeter) The screen must then be coated with a light sensitive emulsion that will accept the artwork image. The screen cloth (polyester fabric) is stretched with automated stretching equipment to achieve accurate tensions, fabric orientation and levels. The coarse density of the screen is important in evaluating the life and/or the number of impressions suited to the printing project. The Screen cloth Fabric (Screen cloth) is stretched over the screen frame
b) Expose
In order to expose a screen, the artwork must be printed onto a clear or translucent film. The artwork is then put onto an exposure system. This is a large machine with a glass top and a light source at the bottom. The light is activated and shines upward toward the glass. The artwork is placed on the glass and the screen is placed on top of the artwork. The light is then turned on for a controlled amount of time and the screen is exposed.
c) Washout
After the screen is exposed, it is then washed out with high-pressure water. The areas of the artwork that were not exposed to the light wash out with water. It is these areas that the ink will pass through and onto the garment. After, the screen has dried; it is then taped around the edges to prevent ink from leaking onto the printing substrate.
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d) Squeegee
Squeegee is the tool which applies the ink. The type of squeegee for printing such RFID label antenna is a Soft squeegee for uniform deposition of the ink on the base substrate and to prevent the screen from damaging since the conductive ink used contains almost 61% of pure Silver. The squeegee is the tool which applies the ink. It pulls the ink across the screen and forces it through the open stencil areas on to the paper or other material being printed. The ink on the screen is checked to ascertain the quantity which should be optimum. The ink is pulled back across the screen with a firm, steady stroke using the squeegee. This movement of the squeegee enables the ink to pass through the stencil and prints the image on the material under the stencil.
III. Printing:
a) Setting
After the screen is prepared for ink, it is then loaded into the printer. It is aligned and adjusted for height. It is then ready to print. The ink is poured on the screen and squeegee is used to apply the ink on the base substrate. Since this method of manufacturing RFID label antenna is by printing method, it inevitably calls for applying ink to the screen. The ink is spread evenly along one side of the stencil (on the top, bottom, right or left side of the image).
b) Loading the screen
After the screen is clamped, the ink is placed in the screen. Along with the ink, a squeegee is placed in the screen to press the ink onto the base material to be printed.
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c) Printing
With the material to be printed in place, the screen is then lowered onto the
base material. The squeegee is then drug across the screen to distribute the ink. The squeegee is then pulled across the screen while applying pressure to push the ink
through the screen and onto the base substrate. The pressure and angle the position the squeegee can be varied to adjust for better printing. The Printing conditions for manufacturing the RFID label antenna is of a room temperature around 25 deg. Celsius to 30 deg. Celsius. It is pertinent to note that the printing premise or printing room should be dust and pollutant free and clean.
d) Curing
After the image is printed, the base material is carefully removed from the board and placed into the box oven for curing. If the ink isn't cured to the right temperature, the ink may crack or come off the base material. This is a critical part of printed to ensure the customer a long lasting product
IV. Testing:
The printed RFID label antenna is tested for the open circuit and contact resistance. There should not be any open or short circuit in the printed antenna and the closed loop contact resistance should not be more than 22 ohms to 25 ohms. Once the testing is done the RFID label is given for chip bonding.
a) Track continuity:
i
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The continuity of the conductive tracks printed is important to ensure if there
are no open circuits in the antenna. If there are any open circuits observed then the contact resistance will be very high and subsequently will reduce the tag
performance.
b) Contact resistance:
The contact resistance of the conductive traces printed as the RFID tag antenna should be between 22 to 25 ohms to ensure good performance of the RFID Tag. The contact resistance can be measured using multimeter.
V. Chip bonding:-
The chip an integrated circuit is one of the components that for a RFID label or tag. The chip is bonded to the RFID label antenna at designated locations. The chip is bonded to the RFID label antenna pads using the silver conductive epoxy.
A final product in the form of RFID Label antenna from the abovementioned dual technology of first Etching and then screen printing is thus obtained.
The advantages of using dual Technology (Etching & Printing) for laying the RFID label antenna are:
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1. Etching has more advantage for design of small tag like 9x70mm. As well with
Etching technology, the cost of the inks used for printing only one layer is much lower.
2. Since high speed printing processes are both fast and additive, applying a conductive ink antenna is significantly cheaper and faster than other alternatives.
3. By Etching process, very fine track laying is possible with appropriate gap between the tracks.
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We Claim:
1. A method for manufacturing RFID label antenna using dual technology comprising the
steps of:
a. Etching
b. Screen printing
2. The method recited in claim 1, wherein the said Etching process consists of:
a. Artwork preparation using computer;
b. Filming;
c. Etching by using Copper
3. The method recited in claim 1 wherein the said screen printing process consist of:
a. exposing the screen by using an appropriate exposure system
b. washing the exposed screen with high-pressure water.
c. drying the screen after such wash out.
d. pouring the ink on the screen.
e. using Soft squeegee for printing RFID label antennas.
f. maintaining a room temperature around 25 deg. Celsius to 30 deg. Celsius for
manufacturing the RFID label antenna.
g. using the Silver Conductive Paste for printing the RFID label antennas,
h. maintaining the continuity of the conductive tracks printed
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i. maintaining the conductive traces printed as the RFID label antenna between 22 to 25 ohms
4. The method recited in claim 1 & 3 wherein the said screens has 90 to 120 threads per centimeter.
5. The method recited in claim 1, 3 & 4, wherein the said screens is wherein the said screens are replaced by steel screen mesh for fine printing.
6. The method recited in claim 1, wherein the said screens is coated with a light sensitive emulsion.
7. The method recited in claim 1, wherein the artwork to be exposed is placed on the glass and the screen is placed on top of the artwork.
8. The system recited in claim 3, wherein the said washout cleans the areas of the artwork that were not exposed to the light.
9. The method recited in claim 3, wherein the said ink contains 61% of pure Silver and is checked to ascertain the quantity which should be optimum.
10. The method recited in claim 3, wherein the said Soft squeegee pulls the ink across the
screen and maintains uniform deposition of the ink.
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Dated this 19th December, 2006

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ABSTRACT
A method for manufacturing RFID label antenna by dual technology comprising the steps of Etching and Screen Printing where the Etching comprises the steps of Artwork preparation using computer, filming and Etching by using Copper and the Screen printing comprises the steps of exposing the screen by using an appropriate
exposure system, washing the exposed screen with high-pressure water, drying the screen after such wash out, pouring the ink on the screen, using Soft squeegee for printing RFID
label antennas, maintaining a room temperature around 25 deg. Celsius to 30 deg. Celsius for manufacturing the RFID label antenna, using the Silver Conductive Paste for printing the RFID label antennas, maintaining the continuity of the conductive tracks printed and maintaining the conductive traces printed as the RFID label antenna between 22 to 25 ohms and at the end of these two processes of etching and screen printing, a RFID label antenna by dual technology is procured.