U.S. patent application number 11/079143 was filed with the patent office on 2006-09-14 for radio frequency identification (rfid) tag lamination process.
This patent application is currently assigned to RCD Technology Corp.. Invention is credited to Robert R. Oberle.
Application Number | 20060205113 11/079143 |
Document ID | / |
Family ID | 36971527 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060205113 |
Kind Code |
A1 |
Oberle; Robert R. |
September 14, 2006 |
Radio frequency identification (RFID) tag lamination process
Abstract
A method of constructing an RFID unit can include using a
protective layer to hold an integrated circuit chip module to a
substrate layer with an antenna unit while a conductive adhesive
has not yet fully set.
Inventors: |
Oberle; Robert R.;
(Macungie, PA) |
Correspondence
Address: |
FLIESLER MEYER, LLP
FOUR EMBARCADERO CENTER
SUITE 400
SAN FRANCISCO
CA
94111
US
|
Assignee: |
RCD Technology Corp.
Bethlehem
PA
|
Family ID: |
36971527 |
Appl. No.: |
11/079143 |
Filed: |
March 14, 2005 |
Current U.S.
Class: |
438/107 ;
257/E21.516; 257/E23.064; 257/E23.13 |
Current CPC
Class: |
H01L 2924/014 20130101;
H05K 3/3485 20200801; H01L 2924/07811 20130101; H01L 23/3164
20130101; H05K 3/321 20130101; H01L 2924/0102 20130101; H05K 3/284
20130101; H05K 2201/10628 20130101; H05K 3/3421 20130101; G06K
19/07749 20130101; H01L 2924/01082 20130101; H01L 23/49855
20130101; Y02P 80/30 20151101; H05K 2203/1311 20130101; H01L
2924/14 20130101; H01L 2924/07811 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
438/107 |
International
Class: |
H01L 21/50 20060101
H01L021/50 |
Claims
1. A method of constructing an RFID unit comprising: attaching an
integrated circuit chip to a substrate with an antenna unit using
an adhesive; and laminating a protective layer over at least part
of the integrated circuit chip while the adhesive has not yet fully
set.
2. The method of claim 1, wherein the integrated circuit chip is
part of a chip module.
3. The method of claim 2, wherein the chip module includes a lead
frame.
4. The method of claim 2, wherein attaching step comprises using
the adhesive to connect a connection element of the module to the
substrate.
5. The method of claim 1, wherein any dwell time between the
attaching and laminating steps is less than less than minute.
6. The method of claim 1, wherein the attachment step is done at a
rate of one attachment per second or greater.
7. The method of claim 1, wherein the adhesive takes over a day to
fully set.
8. The method of claim 1, wherein the adhesive is an electrically
conductive adhesive.
9. The method of claim 8, wherein the conductive adhesive is solder
paste.
10. The method of claim 1, wherein the integrated circuit chip is
attached to the protective layer before the attaching step.
11. The method of claim 1, wherein the protective layer is stretchy
to conform to IC chip.
12. An apparatus to construct an RFID unit comprising: a unit to
attach an integrated circuit chip to a substrate with an antenna
unit using an adhesive; and a unit to laminate a protective layer
over at least part of the integrated circuit chip while the
adhesive has not yet fully set.
13. The apparatus of claim 12, wherein the integrated circuit chip
is part of a chip module.
14. The apparatus of claim 12, wherein the laminating unit connects
a strip of the protective layer to a strip of the substrate.
15. The apparatus of claim 12, wherein the laminating unit uses hot
rollers.
16. The apparatus of claim 12, wherein the attaching unit operates
at a rate of one attachment per second or greater.
17. The apparatus of claim 12, wherein the integrated circuit chip
is attached to the protective layer before the attaching unit.
18. A method of constructing an flexible circuit comprising:
attaching an integrated circuit chip to a substrate with an circuit
traces using an adhesive; and; laminating a protective layer over
at least part of the integrated circuit chip while the adhesive has
not yet fully set.
Description
BACKGROUND OF INVENTION
[0001] Radio Frequency Identification (RFID) tags are typically
small objects that can be attached to or incorporated into a
product. RFID tags contain antenna to enable them to receive and
respond to radio-frequency queries from an RFID tranciever. The
RFID tags are used in a host of industries for purposes such as
inventory control, security, personal identification and the
like.
[0002] The RFID tags can be passive or active. Active devices have
their own power supply. Passive devices rely on energization from
the RFID tranciever. Passive and active RFID tags can use
integrated circuit chips to modulate the identification
response.
[0003] The construction of RFID units can consist of the attachment
of a chip module to a substrate with an antenna unit. The chip
module is typically attached to the substrate with an electrically
conductive adhesive and then the combined unit can be further
processed after the adhesive sets.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a cross sectional view of an RFID unit of one
embodiment.
[0005] FIG. 2 is a top view of an RFID unit of one embodiment.
[0006] FIG. 3 is a diagram of an apparatus to construct an RFID
unit of one embodiment.
DETAILED DESCRIPTION
[0007] One embodiment of the present invention comprises a method
of constructing an RFID unit. The method comprises attaching an
integrated circuit chip to a substrate with an antenna unit using
an adhesive; and laminating a protective layer over at least a
portion of the integrated circuit chip while the adhesive has not
yet fully set.
[0008] FIG. 1 illustrates a cross section diagram of an RFID unit
100 of one embodiment. In this embodiment, the integrated circuit
102 is part of a module 104 which also includes lead frame elements
106 and 108. Other connection elements other than a lead frame
could be used in the module 104. The module 104 is adhesively
connected to substrate 110 including antenna elements 112 and 114
using a conductive adhesive 116. The conductive adhesive 116 can be
a conventional isotropic conductive adhesive, and anisotropic
conductive adhesive or even solder such as solder paste.
[0009] FIG. 2 illustrates a top view where module 202 with IC 204
and lead frame 206 and 208 are connected using the conductive
adhesive to the antenna unit 210 to form the RFID unit 200.
[0010] Looking again at FIG. 1, the protective layer 120 can be
laminated over the module 104 including the integrated circuit 102.
The protective layer 120 can hold the module 102 in place while the
conductive adhesive 116 sets.
[0011] The laminating protective layer can be made of many type of
materials including thermoplastic material, thermoset material,
polyester, polystyrene, polypropylene, polyethylene. The protective
layer may have an adhesive layer. In one embodiment, the protective
layer is relatively stretchy and will conform the shape of the
module or integrated circuit chip. In one embodiment, since the
lamination is done before the adhesive is fully set, there does not
have to be any dwell time between attaching and laminating steps.
In one embodiment, the dwell time can be reduced below a minute.
The attachment step can be done at a high rate due to the lack of
requirement for the conductive adhesive to fully set. In one
embodiment, the attachment is done at a rate of one attachment per
second or greater. The conductive adhesive can be of such that it
takes a long time to fully set since the protective layer holds the
module in place. Thus, the conductive adhesive can take over a day
to fully set, which can greatly increase the pot time of the
adhesive in the apparatus to produce the RFID units.
[0012] The protective layer can have a radiation or heat curable
adhesive. In one embodiment, the protective layer has an ultra
violet (UV) curable adhesive that can be cured in a later step.
[0013] FIG. 3 illustrates an apparatus of one embodiment. In this
embodiment, the laminating protective layer is held in a strip on
roll 302. If the protective layer has a liner it can be removed
onto roll 304. A roll 305 containing a strip with chip modules can
feed to device 307 which can attached the chip module up side down
on the protective layer 308. The antenna material can be a strip on
roll 310. The conductive adhesive can be provided by an adhesive
dispenser 314 to dispense upon module, such as on the leadframe of
the module. An attachment unit 316 attaches the protective layer
308 with modules to the antenna material strip 309. Dancers 320 and
321 can be used to register the substrate strip having antenna
units with the modules on the protective layer 308. A lamination
unit 322 can later be used to laminate the protective layer over
the integrated circuit chip module. The finished material can be
rolled up into a roll 324 which can be held for later processing.
The later processing can include cure step which can be done at a
separate location from the apparatus 300. The laminating unit 322
can use hot rollers. The attaching unit 316 can operate at a rate
greater than one attachment per second or greater.
[0014] In the example of FIG. 3, the integrated circuit chip (as
part of the chip module) is attached to the protective layer before
the attaching unit. This need not be the case, but it can allow the
chips to be spaced on a strip such that the chips will register in
position with the substrate strip having the antenna unit. In an
alternate embodiment, the integrated circuit chip, as part of the
chip module, is attached to the substrate with antenna first
followed by the lamination of the protective layer.
[0015] One embodiment of the present invention is a method of
constructing an RFID unit comprising using a conductive adhesive to
attach an integrated circuit chip module to a substrate with an
antenna unit; and laminating a protective layer over at least a
part of the integrated circuit chip module while the conductive
adhesive has not yet fully set.
[0016] One embodiment of the present invention is a method of
constructing an RFID unit comprising placing a integrated circuit
chip module on a protective layer, wherein the protective layer
includes an adhesive to hold the integrated circuit module; placing
a conductive adhesive on at least portions of the integrated
circuit chip module; and attaching the integrated circuit chip
module to a substrate with an antenna unit.
[0017] One embodiment of the present invention is an RFID unit
comprising a substrate with an antenna unit; an integrated circuit
chip to the substrate with an antenna unit using an adhesive; and a
protective layer laminated over at least a part of the integrated
circuit chip while the adhesive has not yet fully set.
[0018] The chip module can be a single chip attached to a lead
frame or suitable substrate with appropriate electrical connections
for attachment to the antenna-examples of chip modules are offered
by Philips Electronics, Netherlands (FCP package) and Alien
Technologies of Morgan Hill Calif. (Alien Strap) The lead frame can
terminates in two pads, which are intended to attach to the RFID
circuit by a conductive adhesive. Chip modules can be utilized in
order to alleviate the difficulties that normally arise when
placing a small integrated circuits (typical integrated circuits
are <1 mm square, and the areal density of integrated circuits
are typically very low, <0.25 units/square inch). In traditional
application, the mounting of small integrated circuits without a
leadframe leads to low process throughput owing to the time delay
inherent in locating and placing such a small integrated
circuit.
[0019] The disadvantages of previous processes relate to process
throughput and reliability. Application of non-conductive epoxy
under the integrated circuit and conductive epoxy to the outer
leads results in a mechanically and electrically reliable assembly,
however the dwell time for the circuit, i.e. that time that the
circuit must be immobilized while the adhesives cure is typically
several minutes. This may be decreased by using faster curing epoxy
resins however the inherent chemical instability of so-called snap
cure resins makes handling difficult and leads to excessive yield
loss or high material wastage. Anisotropic adhesives, either tapes
or pastes offer increased throughput with respect to epoxy
adhesives however the dwell time per attachment is typically
several seconds and during the dwell time the module must be held
immobile on the substrate using considerable pressure to effect a
reliable electrical connection. The use of a laminated protective
layer can produce a throughput in excess of one attachment per
second that insures mechanical stability of the device. The
equipment can be relatively simple to maintain a very low cost of
ownership of the overall process. This can be as low as $0.01 or
less per attachment when considering the overall cost of materials
and equipment amortization.
[0020] In one embodiment, a traditional conductive adhesive can be
placed over the terminals of the circuit to which the module is to
be attached or placed on the terminals of the module prior to
assembly.
[0021] The module can be placed on the substrate with contact of
the terminals of the module on the appropriate terminal of the
circuit. Alternatively, the module may be temporarily attached to a
tape which is subsequently laminated to the circuit.
[0022] A protective layer can be laminated over the module of a
tape which holds the module in place while the adhesive is cured
(partially or fully). The tape may held in place by a variety of
adhesives including an adhesive selected from any of a number of
adhesive types; hot melt, pressure sensitive, UV cure, thermoset
etc. This laminate may cover the module fully or partially or it
may be advantageous to use a segmented or multiple adhesives for
specific uses.
[0023] A curing step can be done to set, such as cure, the
conductive adhesive. This step may be of a type that initiates cure
of the adhesive which proceeds after the circuit has been removed
from the immediate vicinity of the attachment and/or curing
station.
[0024] The protective layer can form a protective cover for the
module, particularly if the laminate conforms closely to the shape
of the module after lamination. There is no requirement for dwell
time in the placement equipment. This means that parts with a
partially cured adhesive can be safely rolled up and stored while
the curing process takes place. This has the dual benefit of
increasing process throughput and reducing material waste costs.
Tape lamination equipment presently available can be modified to
suit this application. The throughput of exiting equipment is
sufficient to meet the imperative of a low cost high throughput
process for placement and attachment of the module.
[0025] In alternate embodiments, a curable adhesive can be placed
over the module contemporaneously with the conductive adhesive; an
anisotropic adhesive can be used rather than traditional conductive
adhesive; and/or an anisotropic adhesive can be used in place of
both the traditional conductive adhesive and a laminating
adhesive.
[0026] An alternate embodiment is a method for constructing a
flexible circuit comprising attaching an integrated circuit chip to
a substrate with an circuit traces using an adhesive; and
laminating a protective layer over at least part of the integrated
circuit chip while the adhesive has not yet fully set.
[0027] The foregoing description of preferred embodiments of the
present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Many
embodiments were chosen and described in order to best explain the
principles of the invention and its practical application, thereby
enabling others skilled in the art to understand the invention for
various embodiments and with various modifications that are suited
to the particular use contemplated. It is intended that the scope
of the invention be defined by the claims and their
equivalents.
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