U.S. patent application number 12/901590 was filed with the patent office on 2011-10-13 for forming channels for an antenna wire of a transponder.
This patent application is currently assigned to Feinics AmaTech Teoranta. Invention is credited to David Finn.
Application Number | 20110247197 12/901590 |
Document ID | / |
Family ID | 43383657 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110247197 |
Kind Code |
A1 |
Finn; David |
October 13, 2011 |
FORMING CHANNELS FOR AN ANTENNA WIRE OF A TRANSPONDER
Abstract
Channels may be formed in the inlay substrate of a transponder,
such as by laser ablation, and the antenna wire may subsequently be
laid in the channels. Laying the wire in a channel ensures that it
substantially fully embedded in the substrate, thereby eliminating
a need for pressing the wire into the substrate. The channels may
be tapered, or profiled, to enhance adhesion of a self-bonding
wire. A recess for the chip module can also be formed using laser
ablation, and insulation may be removed from end portions of the
antenna wire using laser ablation. Laser ablation may also be used
to create various mechanical and security features.
Inventors: |
Finn; David; (Tourmakeady,
IE) |
Assignee: |
Feinics AmaTech Teoranta
|
Family ID: |
43383657 |
Appl. No.: |
12/901590 |
Filed: |
October 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12877085 |
Sep 7, 2010 |
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12901590 |
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12545825 |
Aug 22, 2009 |
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12877085 |
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12045043 |
Mar 10, 2008 |
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12545825 |
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61367466 |
Jul 26, 2010 |
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61361895 |
Jul 6, 2010 |
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61318334 |
Mar 28, 2010 |
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61315036 |
Mar 18, 2010 |
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61259224 |
Nov 9, 2009 |
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61235012 |
Aug 19, 2009 |
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61230710 |
Aug 2, 2009 |
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61020141 |
Jan 9, 2008 |
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Current U.S.
Class: |
29/600 |
Current CPC
Class: |
H01L 2224/78301
20130101; H01L 2224/78301 20130101; G06K 19/07749 20130101; H01Q
1/2225 20130101; Y10T 29/49016 20150115; G06K 19/07798 20130101;
G06K 19/0775 20130101; H01L 2924/00014 20130101 |
Class at
Publication: |
29/600 |
International
Class: |
H01P 11/00 20060101
H01P011/00 |
Claims
1. A method of mounting an antenna wire to a surface of a substrate
for a transponder chip comprising: forming a channel in the surface
of the substrate for accepting the antenna wire; laying a
self-bonding antenna wire into the channel; and while laying the
antenna wire into the channel, performing one or more of thermally
or electrically warming the wire, or activating an adhesive layer
of the wire by chemically.
2. The method of claim 1, wherein: the channel is formed by laser
ablation of the substrate material.
3. The method of claim 2, wherein: the substrate is frozen during
performing laser ablation.
4. The method of claim 2, wherein: the substrate comprises a
polymer material.
5. The method of claim 2, wherein: the substrate comprises a porous
material.
6. The method of claim 2, wherein: the substrate comprises a
non-porous material.
7. The method of claim 2, wherein: the substrate comprises
Teslin.TM..
8. The method of claim 2, wherein: the channel is formed with a
single pass of a laser.
9. The method of claim 2, wherein: the channel is formed with
multiple passes with a laser.
10. The method of claim 1, wherein the channel is U-shaped.
11. The method of claim 1, wherein: the channel is formed by a
mechanical tool, or by a hot mold process.
12. The method of claim 1, wherein: the channel has a depth which
is less than a diameter of the wire, and as the wire is laid down
into the channel, it is pressed further into the substrate.
13. The method of claim 1, wherein: the channels are formed by
removing material from the substrate.
14. The method of claim 1, further comprising: forming a recess to
receive a chip module in the substrate.
15. The method of claim 14, wherein: the recess is formed by laser
ablation of substrate material.
16. The method of claim 14, wherein: the recess is a stepped
recess.
17. The method of claim 14, wherein: the channel extends from an
edge of the recess.
18. A method of forming an inlay substrate, comprising: thinning an
edge region of an inlay substrate using laser ablation.
19. The method of claim 18, further comprising: forming studs for
inserting into holes of a separate element in the thinned edge
region.
20. The method of claim 18, further comprising: forming holes for
receiving studs of a separate element in the thinned edge region.
Description
TECHNICAL FIELD
[0001] The invention relates to "inlay substrates" used in the
production of "inlays" for "security documents" such as electronic
passports, electronic ID cards and smart cards and, more
particularly, to how an antenna wire may be mounted to the inlay
substrate (and subsequently connected to an RFID (radio frequency
identification) chip or chip module disposed on the inlay
substrate).
BACKGROUND
[0002] Transponders are electronic devices incorporated into secure
documents such as "smart cards" and "electronic passports" using
RFID (radio frequency identification) technology.
[0003] The transponder (or inlay, or chip card) itself generally
comprises (includes): [0004] a substrate (or inlay substrate) which
may comprise a sheet of a synthetic material; [0005] a chip (or
chip module, or chip unit) installed on the substrate (or in a
recess in the surface of the substrate) and having terminals (or
contact surfaces, or pads); and [0006] an antenna wire (or
conductor) mounted on the substrate, formed with "turns" as a flat
coil and connected (bonded) by its ends or end portions to the
terminals of the chip module. (In some of the drawings presented
herein, only one end or end portion of the antenna wire may be
shown, for illustrative clarity, particularly in the
cross-sectional views.)
[0007] The inlay substrate may comprise one or more layers of PVC,
Polycarbonate (PC), polyethylene (PE), PET (doped PE), PETE
(derivative of PE), TYVEK, Teslin.TM., Paper or Cotton/Noil, and
the like. For example, a single layer of uncoated Teslin.TM., with
a thickness of 356 microns. In the main hereinafter, inlay
substrates comprising Teslin.TM. or polycarbonate (PC) will be
described.
[0008] Teslin.TM. is a synthetic printing media, manufactured by
PPG Industries. Teslin.TM. is a waterproof synthetic material that
works well with an Inkjet printer, Laser printer, or Thermal
printer. Teslin.TM. is also single-layer, uncoated film, and
extremely strong. In fact, the strength of the lamination peel of a
Teslin.TM. sheet is 2-4 times stronger than other coated synthetic
and coated papers. Teslin.TM. comes in the sizes of 7 mil to 18
mil, though only sizes 10 mil and 14 mil are sized at 8.5'' by
11'', for printing with most consumer printers. Also available are
perforated versions of Teslin, specifically, 2up, 6up, and 8up.
Teslin.TM. is a microporous polymer. Polycarbonate (PC) is
typically used for national ID cards, and also as the material in
certain passports (such as for the Datapage, in contrast to the
e-Cover).
[0009] The inlay substrate may have an area designated as a
"transponder site" whereat the chip module will be installed. (A
recess in the inlay substrate may constitute the transponder site.)
The transponder site may itself have two areas designated as
"terminals areas" corresponding in position to the two terminals of
the chip module which will be installed at the transponder site.
(The transponder site and terminal areas are generally geometric
abstractions, the chip module and terminals are physical elements.)
Hence, it should be understood that, where applicable, the terms
(and reference numerals for) "transponder site" and "chip module"
may be used interchangeably, and that the terms "terminal areas"
and "terminals" may similarly be used interchangeably.
[0010] In the main hereinafter, RFID chips incorporated into chip
modules will be described. The chip module may be a leadframe-type
chip module comprising an RFID chip encapsulated by a mold mass and
supported by and connected to a leadframe having two terminal
areas. [0011] the mold mass may be approximately 240 .mu.m thick
and 5 mm wide [0012] the leadframe may be approximately 80 .mu.m
thick and 8 mm wide.
[0013] The chip module may be disposed in a recess extending into
the surface of the substrate measuring for example 5.5 mm
wide.times.8.5 mm high (generally the recess is only slightly
larger than the chip module to allow some clearance during
installation, while maintaining good registration).
[0014] The recess for receiving the chip module extends into the
inlay substrate from a "top" surface thereof, and may be a "window"
type recess extending completely through the inlay substrate to a
"bottom" surface thereof, or the recess may be a "pocket" type
recess extending only partially through the inlay substrate towards
the bottom surface thereof.
[0015] The recess may have a "straight" profile--in other words,
substantially constant cross-dimension through (or into) the inlay
substrate. Or, the recess may have a "stepped" profile, including a
larger cross-dimension at the top surface of the substrate than at
(or towards) the bottom surface of the inlay substrate. The recess
is generally sized and shaped to accommodate the size and shape of
the chip module being disposed therein. The term "cavity" may be
used interchangeably with "recess". A stepped recess profile is
commonly used to accommodate a leadframe module, since the
leadframe is typically wider (8-10 mm) than the mold mass (4-6 mm)
of the chip module.
[0016] The antenna wire can be self-bonding copper wire or
partially coated self-bonding copper wire, enamel copper wire or
partially coated enamel wire, silver coated copper wire,
un-insulated wire, aluminum wire, doped copper wire or litz
wire.
[0017] The conventional method of mounting the wire is using a
sonotrode tool which vibrates, feeds the wire out of a capillary,
and embeds it into the surface of the substrate. Examples of
embedding a wire in a substrate, in the form of a flat coil, and an
ultrasonic tool for performing the embedding (and a discussion of
bonding), may be found in U.S. Pat. No. 6,698,089 (refer, for
example, to FIGS. 1, 2, 4, 5, 12 and 13 of the patent). See also
FIGS. 1 and 2 of U.S. Pat. No. 6,233,818. Both of these patents are
incorporated by reference herein. It is also known that a coated,
self-bonding wire will stick to a synthetic (e.g., plastic)
substrate because when vibrated sufficiently to soften (make
sticky) the coating and the substrate.
[0018] The conventional method for connecting the ends or end
portions of the antenna wire to the terminals (or "terminal areas")
of the chip module is by means of thermo compression (TC) bonding.
This method makes use of heat by passing pulses of electric current
through a thermode and simultaneously applying pressure to cause a
diffusion process between the wire and the leadframe of the chip
module.
[0019] FIGS. 1A and 1B illustrate an example of a prior art
technique, such as is disclosed in U.S. Pat. No. 6,233,818 for
mounting an antenna wire to an inlay substrate and connecting the
antenna wire to a chip module installed in a recess in the inlay
substrate.
[0020] An inlay sheet 100 is a large inlay substrate which may have
a plurality of transponder areas (or sites) 102, a one of which is
shown in some detail. Typically, several transponders (or
transponder sites) are fabricated on a single inlay sheet.
[0021] A recess 106 is formed in the inlay substrate 102 for
receiving a leadframe type chip module 108, positioned as shown,
with the mold mass 112 situated below the leadframe 114. The
leadframe 114 of the chip module 108 has two terminal areas 108a
and 108b. An antenna wire 110 having two ends (or end portions)
110a and 110b is mounted on the substrate and connected to the
terminal areas 108a and 108b of the chip module 108.
[0022] The wire may is mounted to the substrate using an ultrasonic
embedding tool such as a sonotrode having a capillary 116. Mounting
the antenna wire may proceed as follows: [0023] using the
sonotrode, embed the wire a short distance, between the points "a"
and "b" near a first terminal of the chip module. (embedding is
indicated by the symbols "x") [0024] stop embedding (raise the
sonotrode), and pass over the first terminal of the chip module,
between the points "b" and "c". [0025] lower the sonotrode and
resume embedding at the point "c", and form the turns of the
antenna between the points "c" and "d" (embedding is indicated by
the symbols "x") [0026] there may be for example 4 or 5 turns, and
the overall length of the antenna wire may be 104 cm [0027] notice
that in forming the turns of the antenna, the wire may need to
cross over itself, thus requiring an insulated wire. However, in
some cases, the antenna wire does not need to cross over itself.
See, for example, FIG. 4 of U.S. Pat. No. 6,698,089. [0028] after
approaching near the second terminal of the chip module, stop
embedding and pass over the second terminal of the chip module,
between the points "d" and "e". [0029] resume embedding a short
distance on the opposite side of the chip module, between the
points "e" and "f".
[0030] The embedding process may be discontinuous, at several
points, rather than continuous.
[0031] In a next stage of the process, the "connection" portions of
the wire passing over the terminal areas are interconnected to the
terminal areas of the RFID chip, typically by means of thermo
compression bonding. A thermode 118 for performing bonding is
illustrated. It is known to remove insulation from the connection
portions of the antenna wire to improve bonding.
[0032] In the case of Teslin (synthetic paper), a normal insulated
wire would not properly embed into the material, it would detach.
Therefore, it is known to use self-bonding wire which attaches to
the material with a slight penetration of the wire in the
material.
[0033] A self-bonding (or self-adhering) wire may comprise [0034] a
metallic core (typically, but not necessarily round in
cross-section) comprising copper, aluminum, doped copper, gold, or
Litz wire, and may have a diameter of 0.010-0.50 mm [0035] a first
coating or "base coat" comprising modified polyurethane, and having
a thickness of only a few microns [0036] a second coating
comprising polyvinylbutyral or polyamide, and having a thickness of
only a few microns.
[0037] The transponder thus formed on the inlay substrate may be
incorporated, for example, in an electronic passport cover. The
material for the cover layer of the passport may be a cloth
product, with chemistry in the coatings and a leather-like
appearance to the cloth, such as by Holliston Inc. (905 Holliston
Mills Road, Church Hill, Tenn. 37642; www.holliston.com)
[0038] FIG. 1C shows a passport cover having a cover layer and an
inlay substrate. The cover layer is laminated (joined) to the inlay
substrate using a polyurethane hot melt adhesive, such as
approximately 50-80 .mu.m thick. Prior to the adhesive process, the
inlay substrate may be pre-pressed to ensure that the antenna wire
does not protrude over (extend above) the surface of the Teslin.TM.
substrate, in other words, to ensure that the antenna wire is fully
embedded in the inlay substrate.
SUMMARY
[0039] According to the invention, generally, channels may be
formed in the inlay substrate of a transponder, such as by laser
ablation, and the antenna wire may subsequently be laid in the
channels. Laying the wire in a channel ensures that it
substantially fully embedded in the substrate, thereby eliminating
a need for pressing the wire into the substrate. The channels may
be tapered, or profiled, to enhance adhesion of a self-bonding
wire. A recess for the chip module can also be formed using laser
ablation, and insulation may be removed from end portions of the
antenna wire using laser ablation. Laser ablation may also be used
to create various mechanical and security features.
[0040] More specifically, laser ablation may be used to ablate
material from an inlay substrate of a secure document, such as for
[0041] (i) creating a recess (cavity or pocket) to accommodate a
chip or chip module and/or [0042] (ii) forming grooves or trenches
in the substrate or film to accept a wire conductor which may serve
as the antenna of a transponder incorporated into the secure
document [0043] (iii) forming mechanical (such as stress relief)
and security (anti-tampering) features
[0044] Laser ablation causes the removal of material from a
substrate. More generally, many of the features described herein
can be achieved via photochemical and photothermal response of the
substrate material to laser irradiation. In other words, material
of the substrate could be photochemically and photothermally
activated material at the time of laying the wire down.
[0045] According to an embodiment of the invention, a method of
mounting an antenna wire to a surface of a substrate for a
transponder chip comprises: forming a channel in the surface of the
substrate for accepting the antenna wire; laying a self-bonding
antenna wire into the channel; and while laying the antenna wire
into the channel, performing one or more of thermally or
electrically warming the wire, or activating an adhesive layer of
the wire by chemically. The channel may be formed by laser ablation
of the substrate material. The substrate may be frozen during
performing laser ablation. The substrate may comprise polymer
material, or a porous material or a non-porous material or
Teslin.TM.. The channel may be formed with a single or with
multiple passes of the laer. The channel may be U-shaped. The
channel may be formed by a mechanical tool, or by a hot mold
process. The channel may have as a depth which is less than a
diameter of the wire, and as the wire is laid down into the
channel, it is pressed further into the substrate. The channel may
be formed by removing material from the substrate. A recess for
receiving a chip module in the substrate may be formed in
conjunction with laser ablation of the channels, and the recess may
be a stepped recess. The channel (or channels) may extend from an
edge of the recess.
[0046] According to an embodiment of the invention, an edge region
of the inlay substrate may be thinned using laser ablation. Studs
may be formed in the thinned region for inserting into holes of a
separate element in the thinned edge region. Holes may be formed in
the thinned region for receiving studs of a separate element in the
thinned edge region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Reference will be made in detail to embodiments of the
disclosure, examples of which may be illustrated in the
accompanying drawing figures (FIGs). The figures are intended to be
illustrative, not limiting. Although the invention is generally
described in the context of these embodiments, it should be
understood that it is not intended to limit the invention to these
particular embodiments.
[0048] Certain elements in selected ones of the figures may be
illustrated not-to-scale, for illustrative clarity. The
cross-sectional views, if any, presented herein may be in the form
of "slices", or "near-sighted" cross-sectional views, omitting
certain background lines which would otherwise be visible in a true
cross-sectional view, for illustrative clarity. In some cases,
hidden lines may be drawn as dashed lines (this is conventional),
but in other cases they may be drawn as solid lines.
[0049] If shading or cross-hatching is used, it is intended to be
of use in distinguishing one element from another (such as a
cross-hatched element from a neighboring un-shaded element). It
should be understood that it is not intended to limit the
disclosure due to shading or cross-hatching in the drawing
figures.
[0050] Elements of the figures may (or may not) be numbered as
follows. The most significant digits (hundreds) of the reference
number correspond to the figure number. For example, elements of
FIG. 1 are typically numbered in the range of 100-199, and elements
of FIG. 2 are typically numbered in the range of 200-299. Similar
elements throughout the figures may be referred to by similar
reference numerals. For example, the element 199 in FIG. 1 may be
similar (and possibly identical) to the element 299 in FIG. 2.
Throughout the figures, each of a plurality of elements 199 may be
referred to individually as 199a, 199b, 199c, etc. Such
relationships, if any, between similar elements in the same or
different figures will become apparent throughout the
specification, including, if applicable, in the claims and
abstract.
[0051] FIG. 1A is a top view of a transponder site (one of many on
an inlay sheet), according to the prior art.
[0052] FIG. 1B is a side, cross-sectional view, partially exploded,
of a wire being mounted to an inlay substrate and bonded to the
terminals of a transponder chip, according to the prior art.
[0053] FIG. 1C is a perspective view of a secure document which is
an electronic passport cover, according to the prior art.
[0054] FIG. 1D is a cross-sectional view of the secure document of
FIG. 1C, according to the prior art.
[0055] FIG. 2A is a cross-sectional view illustrating a technique
for creating channels for mounting an antenna wire in an inlay
substrate, according to an embodiment of the invention.
[0056] FIG. 2B is a cross-sectional view illustrating a technique
for creating channels for mounting an antenna wire in an inlay
substrate, according to an embodiment of the invention.
[0057] FIG. 2C is a cross-sectional view illustrating a technique
for creating channels for mounting an antenna wire in an inlay
substrate, according to an embodiment of the invention.
[0058] FIG. 2D is a perspective view illustrating a technique for
creating channels for mounting an antenna wire in an inlay
substrate, according to an embodiment of the invention.
[0059] FIG. 2E is a cross-sectional view illustrating mounting an
antenna wire in a channel, according to an embodiment of the
invention.
[0060] FIG. 3A is a perspective view illustrating a technique for
forming a recess in an inlay substrate using laser ablation,
according to an embodiment of the invention.
[0061] FIG. 3B is a cross-sectional view illustrating a technique
for forming a recess in an inlay substrate using laser ablation,
according to an embodiment of the invention.
[0062] FIG. 3C is a cross-sectional view illustrating a technique
for forming a recess in an inlay substrate using laser ablation,
according to an embodiment of the invention.
[0063] FIG. 3D is a cross-sectional view illustrating a technique
for forming a recess in an inlay substrate using laser ablation,
according to an embodiment of the invention.
[0064] FIG. 4 is a perspective view illustrating a technique for
forming channels for mounting an antenna wire in an inlay
substrate, according to an embodiment of the invention.
[0065] FIG. 5 is a cross-sectional view of a technique for forming
channels for mounting an antenna wire in an inlay substrate,
according to an embodiment of the invention.
[0066] FIG. 6A is a cross-sectional view of a technique for
mounting and connecting an antenna wire to a chip module of a
transponder, according to an embodiment of the invention.
[0067] FIG. 6B is a cross-sectional view of a technique for
mounting and connecting an antenna wire to a chip module of a
transponder, according to an embodiment of the invention.
[0068] FIG. 6C is a cross-sectional view of a technique for
mounting and connecting an antenna wire to a chip module of a
transponder, according to an embodiment of the invention.
[0069] FIG. 7A is a perspective view of a technique for mounting
and connecting an antenna wire to a chip module of a transponder,
according to an embodiment of the invention.
[0070] FIG. 7B is a cross-sectional view taken on a line 7B-7B
through FIG. 7A.
[0071] FIG. 7C is a top view of a further step in the technique of
FIG. 7A.
[0072] FIG. 8 is a perspective view of forming trenches around a
recess in a substrate, according to an embodiment of the
invention.
[0073] FIG. 9A is a top view, and FIGS. 9B and 9C are
cross-sectional views of a technique for forming a protected area
around a chip module in an inlay substrate, according to an
embodiment of the invention.
[0074] FIG. 10A is a perspective view, and FIG. 10B is a
cross-sectional view of a technique for "pinning" a chip module in
a recess in an inlay substrate, according to an embodiment of the
invention.
[0075] FIG. 11A is a perspective view, and FIG. 11B is a
cross-sectional view of a technique for retaining a chip module in
a recess in an inlay substrate, according to an embodiment of the
invention.
[0076] FIG. 12A is a cross-sectional view of a technique for
modifying an edge portion (region) of an inlay substrate to mate
with an other element such as a flap, according to an embodiment of
the invention.
[0077] FIGS. 12B and 12C are partial perspective views of
alternatives to the technique shown in FIG. 12A, according to
embodiments of the invention.
DETAILED DISCLOSURE
[0078] Various "embodiments" of the invention (or inventions) will
be discussed. An embodiment is an example or implementation of one
or more aspects of the invention(s). Although various features of
the invention(s) may be described in the context of a single
embodiment, the features may also be provided separately or in any
suitable combination. Conversely, although the invention(s) may be
described herein in the context of separate embodiments for
clarity, the invention(s) may also be implemented in a single
embodiment.
[0079] The relationship(s) between different elements in the
figures may be referred to by how they appear and are placed in the
drawings, such as "top", "bottom", "left", "right", "above",
"below", and the like. It should be understood that the phraseology
and terminology employed herein is not to be construed as limiting,
and is for descriptive purposes only.
[0080] The invention relates generally to inlays and techniques for
making the inlays, including technical features and security
features. As used herein, an "inlay" may be a single- or
multi-layer substrate containing HF (high frequency) and/or UHF
(ultra-high frequency) radio frequency identification (RFID,
transponder) chips and/or modules. These inlays may be used in
secure documents, such as, but not limited to, electronic passports
(ePassports) and electronic ID (eID) cards.
[0081] In some of the figures presented herein, only one end or end
portion of the antenna wire and a corresponding single one of the
two terminals of the chip module may be shown as described, as
exemplary of how both ends or end portions of the antenna wire may
be mounted to the inlay substrate and connected by a connection
portion of the antenna wire to the terminals of the chip module,
unless as otherwise may be noted. A connection portion of the wire
may be an end or end portion of the wire.
[0082] In some of the techniques for mounting and connecting an
antenna wire presented herein, mainly the mounting of the antenna
wire is described in detail. Typically, the connecting of the
antenna wire will occur subsequent to mounting, using a
conventional thermode-type tool in a conventional manner, and may
only be briefly discussed and/or shown.
[0083] In the main, examples of electronic passport covers with
inlay substrates having leadframe modules may be used to illustrate
the embodiments. It should be understood that various embodiments
of the invention(s) may also be applicable to other secure
documents containing electronics (such as RFID and antenna), such
as electronic ID cards. Secure documents may also be referred to as
"electronic documents". In the main hereinafter, secure documents
which are passport inlays, typically cold laminated (with
adhesive), are discussed.
[0084] The following embodiments and aspects thereof may be
described and illustrated in conjunction with systems, tools and
methods which are meant to be exemplary and illustrative, not
limiting in scope. Specific configurations and details may be set
forth in order to provide an understanding of the invention.
However, it should be apparent to one skilled in the art that the
invention(s) may be practiced without some of the specific details
being presented herein. Furthermore, well-known features may be
omitted or simplified in order not to obscure the descriptions of
the invention(s).
Forming Channels or Grooves to Accept the Antenna Wire
[0085] The conventional technique (such as in U.S. Pat. No.
6,233,818) for mounting the antenna wire is by ultrasonically
embedding (countersinking) it into the surface of the inlay
substrate. Ideally, the antenna wire is fully embedded so that it
is flush or below the top surface of the inlay substrate. However,
with ultrasonic embedding, the wire may become only partially
embedded, such as approximately half its diameter. In other words,
a 100 .mu.m diameter wire may be embedded 50 .mu.m (half its
diameter) into the inlay substrate, and may protrude approximately
50 .mu.m (half its diameter) from the surface of the inlay
substrate. And, in the case of adhesively sticking, a 100 .mu.m
diameter wire may be substantially not embedded at all into the
inlay substrate, and may protrude approximately 100 .mu.m (its
entire diameter) from the surface of the inlay substrate.
[0086] For applications such as driver's license or passports, it
is generally not desirable that the wire extend (protrude) above
the surface of the inlay substrate. As discussed hereinabove, the
chip module may be recessed so as to be substantially contained
within the inlay substrate (or sheet), without sticking out and
creating a bump.
[0087] According to an embodiment of the invention, the antenna
wire may be mounted so as to be substantially entirely disposed
(embedded) within the surface of the inlay substrate, without
protruding therefrom. In other words, the wire will be
substantially entirely recessed below the surface of the inlay
substrate.
[0088] Generally, this may be accomplished by creating a "groove"
(or "channel", or "trench") in the surface of the inlay substrate
to accept the antenna wire. Then, the antenna wire may then be laid
(inlaid, pressed, sunk) into the groove.
[0089] In general, the groove may be formed either by removing
material from the substrate (by analogy, digging a trench with a
shovel, and tossing the dirt aside), or displacing material of the
substrate (by analogy, hoeing a trench to push aside dirt). Some
exemplary techniques for removing or displacing material will be
described below. A mechanical tool, such as a wire bonder, may be
used to form and press the wire into the groove.
[0090] The depth of the groove should be at least a substantial
portion of the diameter of the wire, such as at least 50% of the
diameter of the wire, including at least 60%, at least 70%, at
least 80% and at least 90%, and the groove may be at least as deep
as the wire diameter, such as at least 100%, at least 105%, at
least 110%. In some cases, described below, the groove may be a
"deep trench" which is much greater than the diameter of the wire,
for routing the wire from one level, such as just within the
surface of the substrate) to another level, such as deep within the
substrate, such as for facilitating connecting the wire to contact
areas or pads of a module which are disposed below the surface of
the substrate (see, for example, FIGS. 2B and 2D where the wire
ends are bonded to a bottom surface of the leadframe, rather than
to the top surface thereof).
[0091] For example, for mounting a 60 .mu.m diameter wire, a groove
which is approximately 60 .mu.m deep may be formed into the surface
of the inlay substrate. As discussed below, in conjunction with
mechanically embedding the antenna wire in the groove, heat may be
applied to allow further embedding. Therefore, for example, a 60
.mu.m wire could be pressed, with heat, into a 40 .mu.m deep
groove, and become substantially entirely embedded within the
surface of the substrate, without protruding therefrom.
[0092] The groove may be less deep than the diameter of the wire
and, as the wire is laid down into the groove, it may be pressed
further into the substrate. Or, after the entire antenna wire is
laid down, the inlay substrate may be placed in a press which may
further sink the antenna wire into the inlay substrate. The process
may be performed in a warm environment to soften the substrate. The
wire may be warmed as it is being laid down (scribed, sunk) into
the trench (groove) to facilitate its entry into the trench.
[0093] The width of the groove may be approximately equal to the
diameter of the wire. For example, for a wire having a diameter of
60-80 .mu.m, a laser beam having a diameter of 0.1 mm (100 .mu.m)
would create a groove sufficiently wide (100 .mu.m) to receive the
wire. The groove may be narrower than the diameter of the wire,
such as approximately 95% of the diameter of the wire, to
facilitate an "interference" fit, securely holding the wire in
position for subsequent handling. In general, a groove which is
significantly wider than the diameter of the wire would not be
preferred, since it would tend not to retain the wire (such as by
interference fit), without more (such as an adhesive).
[0094] The groove may be slightly narrower than the diameter of the
wire, and as the wire is being laid down, the material of the inlay
substrate may resiliently retract (e.g., elastic deformation) to
receive the wire, holding it in place. Generally, the wire
typically has a circular cross-section (but may have other
cross-sections, such as a ribbon wire), and the groove may have a
substantially rectangular cross-section. For example, a 60 .mu.m
wide groove may receive and retain in place an 80 .mu.m diameter
wire. The wire may be warmed as it is being laid down (scribed,
sunk) into the groove to facilitate its entry into the groove.
[0095] The groove may simply be a channel extending along the
surface of the inlay substrate, formed by a mechanical tool
(ultrasonic stamp or scribe), or by a hot mold process.
Alternatively, the groove may be formed by laser ablation, in a
manner similar to how recesses are made.
[0096] Generally, the groove facilitates holding the wire in place.
For example, a 100 micron diameter wire can be inserted (with some
pressure) into a narrower, such as 95 micron wide channel (the
depth of the channel should be at least half the diameter of the
wire, so that the wire can be embedded "over center"), and will
stay in place. It is beneficial that this can be done without
requiring an ultrasonic embedding tool. As mentioned above,
mounting a wire to the inlay substrate is typically done by
ultrasonically embedding the wire into the inlay substrate, or
ultrasonically causing a self-bonding wire to adhere to the inlay
substrate. The "channeling technique" disclosed herein can proceed
faster than the ultrasonic techniques, and sheets can be prepared
with wire channels, off-line, then the wire can be installed in a
simple embedding machine which does not need ultrasonics.
[0097] According to an embodiment of the invention, channels (or
grooves, or trenches) are formed in the substrate for receiving the
antenna wire, and the antenna wire is installed (laid) into the
channel, which has several advantages, such as eliminating the need
for the pressing operation associated with ultrasonic embedding of
the antenna wire. Various techniques for forming the channels will
briefly be described.
[0098] FIG. 2A (illustrates a technique 200a using a laser 250 to
form a groove (channel, trench) 252a in a surface of an inlay
substrate 202. This is an example of removing material to form the
groove. The laser 250 is shown moving from left-to-right in the
figure. Laser ablation of material to form channels (grooves,
trenches) will be described in greater detail hereinbelow.
[0099] A wire 210 is shown being laid down into the groove 252a,
from left-to-right, and may be urged into the groove 252a by a
simple pressing tool (or wheel) 254. The wire 210 may be laid into
the groove 252a during formation of the groove (channel), by
following after the laser a distance "u".
[0100] Although only one straight groove is shown, a 2-dimensional
(x-y) groove pattern may thus be formed in the top surface of the
inlay substrate, extending from (originating and terminating at) a
recess in the inlay substrate, for accepting an antenna wire having
a number of turns or coils. As mentioned above, insulated wire is
relevant where the wire needs to cross over itself, such as in FIG.
1A. Methods of forming a single groove with multiple passes of the
laser, and forming grooves with tapered (profiled) sidewalls are
described below.
[0101] The wire may be a self-bonding (coated, self-adhering wire).
In conjunction (such as simultaneous) with laying the wire in the
groove (channel), the wire 210 may be warmed thermally (such as
with heat), chemically activated (such as with alcohol), or warmed
electrically (such as by passing a current through the wire. The
pressing tool 254 itself may be heated. Or, a separate heating
element 256 may be provided, such as a nozzle directing hot air
onto the wire either immediately before (to the right of) or after
(to the left of, as shown) the pressing tool 254. The heating
element 256 may be a laser operating in a range to heat the wire
sufficiently to activate the adhesive coating.
[0102] FIG. 2B illustrates a technique 200b using a mechanical tool
260b to form a groove 252b in a surface of an inlay substrate 202.
This is an example of removing material to form the groove. The
tool may be a milling tool, such as a conventional or climb milling
tool available from IBAG Switzerland AG, described hereinabove.
Reducing the temperature of the material being milled, as discussed
above, may be employed.
[0103] Alternatively, the tool 250b may be similar to a "gouge"
used to carve patterns in wood. (Gouge--Carving tool with a curved
cutting edge.) A gouging tool 250b is shown moving from
left-to-right in the figure. In this figure, the wire (202) and the
pressing tool (254) are omitted, for illustrative clarity. The
"debris" from gouging (or milling) is also omitted, for
illustrative clarity.
[0104] In either of using laser ablation or a mechanical tool to
form the channels, the process is one of removing material, and may
be performed at reduced temperature, such as by chilling (freezing)
the inlay substrate (polymer) with a stream of cold gas, such as
freeze gas (or spray) at approximately -50.degree. C. (resulting in
the substrate being chilled to approximately -20.degree. C.). A
suitable freeze spray is Kontakt Chemi 75 (CRC Industries).
[0105] FIG. 2C illustrates a technique 1200c using an ultrasonic
stamp tool 250c form a groove 252c in a surface of an inlay
substrate 202. This is an example of displacing material, with
pressure, to form the groove. The tool may be a thin rectangular
block, or a small diameter cylinder, mounted to an ultrasonic
converter (not shown). The tool 250c is shown moving from
left-to-right in the figure. In this figure, the wire (202) and the
pressing tool (254) are omitted, for illustrative clarity. A
similar tool could be used to push the wire further into the
substrate, once it has already been (partially) embedded
therein.
[0106] FIG. 2D illustrates a technique 200d forming a groove 252d
in the surface of an inlay substrate 202 by using heat and molding.
Essentially, a die tool 250d having a raised pattern 251
corresponding to the desired pattern for the groove(s) is pressed
(arrow) down against the surface of the inlay substrate 202, and
heat may be applied, to transfer the pattern to (mold the pattern
into) the inlay substrate. This technique can also be considered to
be "displacing".
[0107] Regarding techniques for displacing material to form a
channel for the antenna wire, it could be said that in
straightforward embedding (ultrasonic, sonotrode), the wire
displaces substrate material as it is embedded into the surface of
the substrate. It should be understood that the displacing
techniques described herein are performed with a tool separate and
distinct from the wire, and prior to the wire being embedded in the
surface of the substrate.
[0108] It should be understood that the channels for antenna wire
being discussed herein are "pre-formed" (prior to
mounting/embedding the antenna wire therein) in a desired pattern
for the antenna. An inlay substrate may be prepared with such
pre-formed channels for later embedding of antenna wire.
[0109] The channel to accept a wire does not have to be laser
ablated, it can be formed through direct etching (lithographic
process), x-ray (using a mask), chemically, mechanically or
thermally (electromagnetic radiation). Or it could be a transfer
process using an additional layer of material, such as adhesive, in
which channels are formed prior to the additional layer of material
being placed on the inlay substrate or after it is placed on the
substrate.
[0110] FIG. 2E shows embedding a wire in the channel. This can be
done during channel formation, such as indicated in FIG. 2A, with
the wire following close behind the laser, or the wire can be
installed in a separate step after the entire channel is formed. In
this example, a groove 252e (compare any of grooves 262a, 262b,
262c, 262d) is formed in the substrate 202, and a wire 210
installed (inserted, mounted, laid into) in the groove using any
suitable mechanical tool 254.
[0111] The wire conductor used to countersink in the laser ablated
(or otherwise formed) trench or channel in the substrate may be a
self-bonding wire with a coating of polyurethane adhesive as an
outer layer and an insulated layer as the inner core surrounding
the metal wire such as copper. During the countersinking process of
placing the wire conductor into the trench or channel, a laser may
be used to soften or melt (or activate) the outer layer of the wire
in order to bond the self-bonding wire to the walls of the trench
or channel.
[0112] It should be understood that when a wire is installed into a
pre-formed groove, this is different than ultrasonic embedding of a
wire into a non-grooved surface of a substrate, such as is
disclosed in U.S. Pat. No. 6,698,089 (or U.S. Pat. No. 6,233,818).
The tool 254 for installing the wire into the groove 252e may or
may not be ultrasonic.
[0113] After installing, the wire may protrude slightly above the
top surface of the substrate 202. If sufficient pressure, heat
and/or ultrasonic are used during installing the wire and/or the
groove is sufficiently deep, the wire may be fully embedded, flush
with the top surface of the substrate.
[0114] It should be understood that the channel to accept the wire
does not have to be laser-ablated, rather it can be formed using
other techniques such as gouging, ultrasonic stamp and heat mold,
as described above, as well as by using [0115] direct etching
(lithographic process), [0116] x-ray (using a mask), [0117]
chemically, [0118] mechanically or thermally.
[0119] It is within the scope of the invention that channels for
accepting antenna wire may be formed in a layer or film of material
which is separate from the substrate, such as [0120] forming
channels in a layer of adhesive on the surface of the substrate, or
[0121] forming channels in a film of material, then applying the
film to the substrate
Laser Ablation of Polymers
[0122] Laser ablation may be used to remove material from a
substrate or film, typically of a synthetic material, typically of
an inlay substrate of a secure document, such as for
(i) creating a recess (cavity, pocket) to accommodate a chip or
chip module and/or (ii) forming channels (or grooves or trenches or
notches) in the substrate (or layer or film) to accept a wire
conductor which may serve as the antenna of a transponder
incorporated into the secure document
[0123] The controlled removal of substrate material by intense
light is called laser ablation, derived from the Latin word
ablatum, or sometimes also referred to as Ablative Photo
Decomposition (APD). The material removal occurs only if a certain
threshold in light intensity is exceeded.
[0124] Laser ablation is the process of removing material from a
solid (or occasionally liquid) surface by irradiating it with a
laser beam. At low laser flux, the material is heated by the
absorbed laser energy and evaporates or sublimates. At high laser
flux, the material is typically converted to a plasma. Usually,
laser ablation refers to removing material with a pulsed laser, but
it is possible to ablate material with a continuous wave laser beam
if the laser intensity is high enough.
[0125] The depth over which the laser energy is absorbed, and thus
the amount of material removed by a single laser pulse, depends on
the material's optical properties and the laser wavelength. Laser
pulses can vary over a very wide range of duration (milliseconds to
femtoseconds) and fluxes, and can be precisely controlled. This
makes laser ablation very valuable for both research and industrial
applications.
[0126] The simplest application of laser ablation is to remove
material from a solid surface in a controlled fashion. Laser
machining and particularly laser drilling are examples; pulsed
lasers can drill extremely small, deep holes through very hard
materials. Very short laser pulses remove material so quickly that
the surrounding material absorbs very little heat, so laser
drilling can be done on delicate or heat-sensitive materials.
[0127] A typical laser for ablating synthetic material such as
Teslin.TM. or polycarbonate is an ultra violet diode pump laser
operating at the wavelength of 355 nm.
[0128] Laser ablation may be used for the machining of cavities in
commercial polymers (ultra high molecular weight polyethylene and
polycarbonate) to accept an electronic component such as a
microchip (or chip module). Heretofore, UV laser ablation of
commercial polymers in industrial applications have had limited
commercial success because of high ablation thresholds, low
ablation rates resulting in low production throughput and
re-deposition of debris.
[0129] Laser ablation of polymers can be performed under
atmospheric conditions and at room temperature, making it a very
attractive alternative to traditional micromachining of 3
dimensional structures using high speed mechanical milling.
[0130] Thermoplastic polymers (compound with a molecular structure)
have a low thermal conductivity and extremely high UV absorption
and so direct bond breaking without heat is possible using lasers
emitting in the UV range 157-355 nm. This process is called cold
ablation and for the ablation of most polymers, nanosecond UV
lasers are well suited.
[0131] The nature of the interaction mechanisms between the laser
beam and the polymer substrate depend on the parameters of the
laser light energy and on the physical (microstructure) and
chemical properties (the arrangement of atoms or molecules within a
polymer) of the substrate.
[0132] The successive phases in the irradiation of a polymer
substrate with intense nanosecond UV-pulses can be described
roughly in the following diagrams:
[0133] A laser beam may be focused on a substrate to cause
ablation. Ablation may be broken down into the following three
phases [0134] (a) interaction of the laser beam with the target
substrate with UV light absorption and generation of electronic
excitation [0135] (b) high pressure generated by bond breakage of
the target substrate. [0136] (c) removal or sputtering of the
ablated material from the target substrate.
[0137] The first phase of the laser ablation process begins with
the absorption of photons at UV wavelengths in the substrate and
this leads to electronic and vibrational excitation of the
molecules.
[0138] In a second phase, the electronic excitation relaxes and a
conversion decomposition mechanism takes place via heat generation
(photothermal activation), photochemical and photomechanical
reaction. This mechanism induces bond breaking, evaporation and
desorption. However, the exact pathways leading to decomposition
are unclear and controversial. See Bauerle, D. (2000). Laser
Processing and Chemistry, third ed. Advanced Texts in Physics.
Berlin, Heidelberg, New York: Springer-Verlag, incorporated by
reference herein.
[0139] In a third phase, mainly gaseous components (a multiple of
the original solid) will be forcefully ejected from the surface at
high pressure, causing the removal of material. The components
travel with speed and are preceded by a shockwave front due to
compression of the ambient atmosphere.
[0140] The ejected plume consists of vapor, driving gas and
particles of which some will be re-deposited as debris around the
ablation crater. (The word crater is used in laser science to
describe the process of ablation (explosive), the resulting area is
a recess when machined properly at the right wavelength, pulse
duration and fluence. A crater may be a recess, or a channel, or
any feature formed by laser ablation.)
[0141] The deposition of debris can be minimized by directing a
medium such as He or H2 to the ablation area at low pressure. These
gases allow the plume to expand much faster preventing less
particle formation and re-deposition.
[0142] Apart from the substrate material, the most important laser
parameters affecting the ablation mechanism are: [0143] Wavelength
(.lamda.) of the laser emission and the ability of the polymer
substrate to absorb that wavelength [0144] Pulse energy (E) [0145]
Intensity or irradiation fluence (.PHI.) of the laser beam delivery
[0146] Pulse duration (t) [0147] Frequency of the pulses (usually
referred to as the repetition rate) (Q) [0148] Angle of incidence
[0149] Beam shape and quality [0150] Dwell time (irradiation time
at a particular spot)
[0151] But, these parameters are further influenced by other
factors such as multiphoton absorption, thermal diffusion,
scattering due to surface roughness, and various hydro dynamical
processes.
[0152] It is a general object of the invention to structure polymer
materials for hosting RFID chips (or chip modules) in manufacturing
an intermediate product known as an inlay used by secure printers
in the production of electronic passports and national identity
cards. In particular, to machine a microporous polymer substrate
(such as Teslin) with a target ablation rate of up to approximately
5 mm.sup.3/second, creating a stepped recess or a pocket-type
recess which extends only partially through a substrate. This
recess or pocket is prepared to accept a leadframe RFID chip module
such as an MOB 6 from the semiconductor company NXP. (The polymer
material may also be non-porous.)
[0153] According to an aspect of the invention, faster ablation may
be achieved by amalgamating several techniques to create a hybrid
ablation process.
[0154] In the main hereinafter, forming channels in polymer
substrates using laser ablation will be discussed.
[0155] A suitable tool for performing the laser ablation techniques
described herein is the TruMicro Serie 5000 laser by TRUMPF Laser
GmbH+co. KG (Schramberg Germany).
[0156] An advantage of the techniques disclosed herein for forming
a channel (or channels) for the wire include that there is
substantially no displacement of substrate material (of course,
with an "interference fit", some displacement of the substrate
material is desirable, as the walls of the groove may expand
resiliently when inserting the wire.) Also, un-insulated wire may
be used, which has the advantage that insulation need not be
removed from connection portions of the wire prior to bonding to
the terminals of the chip module.
[0157] To assist the ablation process of the polymer in creating
craters, trenches or channels, the ablation zone of the substrate
material can be heated or frozen (e.g. using freeze gas) prior to
the material being removed. Alternatively, the material can be
treated with carbon by passing the polymer through a laser printer
to induce (lay down a specific pattern or broader blanket of) black
toner into the area to be machined. Alternatively, black ink can be
applied to the substrate material prior to ablation. Carbon may
have the beneficial effect of lowering the ablation threshold and
increasing the absorption of the laser energy at the ablation zone.
Reference is made to U.S. Pat. No. 4,693,778, incorporated by
reference herein.
Forming Recesses by Laser Ablation
[0158] FIGS. 3A-3D illustrate various techniques for using a laser
to ablate material in a controlled manner from a substrate such as
an inlay substrate to form a recess extending into a surface of the
inlay substrate.
[0159] FIG. 3A shows forming a recess (opening, window) in a single
layer of material, such as a layer of Teslin.TM. for an inlay
substrate, using laser ablation. This single layer of material may
also be representative of each of the two layers in a multi-layer
inlay substrate such as are shown in FIGS. 2A and 2B. (See also
FIG. 8 of "S16") As described therein [0160] FIG. 8 ("S16")
illustrates an exemplary process 800 of forming a recess 806 in a
substrate 802, using a laser 860. The substrate 802 may be a single
layer of Teslin (for example), having a thickness "t" of 355 .mu.m
in the z-direction, and measuring 183 mm.times.405 mm (3up format)
in the x- and y-directions. A typical size for the recess 806, to
accommodate a chip with lead frame, may be approximately 5
mm.times.8 mm, by 260 .mu.m deep. [0161] The laser 860 emits a beam
(dashed line), targeted at the substrate 802, to ablate material
from the substrate 802 to form the recess 806. The beam may have a
diameter of approximately 0.1 mm. The beam may be scanned back and
forth, traversing in one direction entirely across the recess area,
turning around, and traversing back across the recess area, like
plowing a field. Many passes may be required to carve out the
entire area of the recess, given that the beam diameter is
typically much (such as 10-100 times) smaller than the length or
width of the recess. As is known, the beam may be scanned, in any
suitable manner, such as with mirrors. Also, the intensity of the
beam may be controlled or modulated to control the penetration into
the substrate. For example, a pulse-width modulated beam may be
used. The laser may be a UV laser (355 nm) with a power ranging
from 20 to 70 watts. [0162] The process of using a laser in this
manner, rather than (for example) a conventional rotating milling
tool, may be referred to as "laser milling" The technique described
herein may be particularly beneficial for applications where it is
desired to form a "pocket" type recess which intentionally does not
extend all the way through the substrate or sheet (in other words,
the recess or pocket extends only partially through the substrate).
Mechanical milling can be difficult. On the other hand, laser
milling can be very effective for Teslin and polycarbonate
substrates. For PVC, laser milling is less effective.
[0163] FIG. 3A illustrates an exemplary process 300 of forming a
recess 306 in an inlay substrate 302, using a laser 360. The inlay
substrate 302 may be a single layer of Teslin (for example), having
a thickness "t" of 355 .mu.m. A typical size (width dimensions) for
the recess 306, to accommodate a chip module (such as 210) with a
lead frame (such as 218), may be approximately 5 mm.times.8 mm. The
recess 306 may extend completely through the inlay substrate 302,
resulting in a window-type recess. The recess 306 may extend only
partially, such as 260 .mu.m through the inlay substrate 302,
resulting in a pocket-type recess.
[0164] The laser 360 emits a beam (dashed line), targeted at the
substrate 302, to ablate material from the substrate 302 to form
the recess 306. The beam may have a diameter of approximately 0.1
mm. The beam may be scanned back and forth, traversing in one
direction entirely across the recess area, turning around, and
traversing back across the recess area, like plowing a field. Many
passes may be required to carve out the entire area of the recess,
given that the beam diameter is typically much (such as 10-100
times) smaller than the length or width of the recess. As is known,
the beam may be scanned, in any suitable manner, such as with
mirrors. Also, the intensity of the beam may be controlled or
modulated to control the penetration into the substrate. For
example, a pulse-width modulated beam may be used. The laser may be
a UV laser (355 nm) with a power ranging from 20 to 70 watts.
[0165] The process of using a laser in this manner, rather than
(for example) a conventional rotating milling tool, may be referred
to as "laser milling". The technique described herein may be
particularly beneficial for applications where it is desired to
form a "pocket" type recess which intentionally does not extend all
the way through the substrate or sheet (in other words, the recess
or pocket extends only partially through the substrate). Mechanical
milling can be difficult. On the other hand, laser milling can be
very effective for Teslin and polycarbonate substrates. For PVC,
laser milling is less effective.
[0166] The recess (opening) 306 formed in the inlay substrate 302
of FIG. 3A extends completely through the inlay substrate 302. The
substrate 302 may be a one layer of a multi-layer substrate.
[0167] FIG. 3B shows forming a stepped window-type recess 306b in a
single layer of material, such a layer of Teslin.TM. for an inlay
substrate 302b, using laser ablation. This may be a two-step
process comprising: [0168] first laser milling a central area (such
as between "b" and "c") to a first partially through the substrate,
[0169] then continuing laser milling the entire area (such as
between "a" and "c") to create a recess extending partially through
the substrate in a peripheral area, and to extend the recess in the
central area completely through the substrate.
[0170] Alternatively: [0171] first laser milling the entire area
(between "a" and "d") to a first depth (d1) [0172] then laser
milling only the central area (between "b" and "c") to a second
depth (d2).
[0173] FIG. 3C shows forming a stepped pocket-type recess 306c in a
single layer of material, such a layer of Teslin.TM. for an inlay
substrate 302c, using laser ablation. This may be a two-step
process comprising: [0174] first laser milling a central area (such
as between "b" and "c") to a depth partially through the substrate,
[0175] then continuing laser milling the entire area (such as
between "a" and "d") to create a recess extending partially through
the substrate in a peripheral area, and to extend the recess in the
central area deeper into (but not completely through) the
substrate.
[0176] Alternatively: [0177] first laser milling the entire area
(between "a" and "d") to a first depth (d1) [0178] then laser
milling the central area (between "b" and "c") to a second depth
(d2).
[0179] FIG. 3D shows that a two-step pocket type recess 306d can be
formed in a single layer of material, such a layer of Teslin.TM.
for an inlay substrate 302c, using laser ablation. This may be a
three-step process comprising: [0180] first laser milling a central
area (such as between "c" and "d") to a depth partially through the
substrate, [0181] next laser milling a middle area (such as between
"b" and "e") to a depth partially through the substrate, which will
increase the depth in the central area, [0182] then continuing
laser milling the entire area (such as between "a" and "f") to
create a recess extending partially through the substrate in a
peripheral area, and to extend the recess in the middle and central
area deeper into (but not completely through) the substrate.
[0183] Alternatively: [0184] first laser milling the entire area
(between "a" and "f") to a first depth (d1) [0185] then laser
milling the middle area (between "b" and "e") to a second depth
(d2) [0186] then laser milling the central area (between "c" and
"d") to a third depth (d3).
[0187] For example, the resulting depths may be: [0188] in the
peripheral area ("a"-"b", "e"-"f"), approximately 0.056 mm [0189]
in the middle area ("b"-"c", "d"-"e"), approximately 0.116 mm
[0190] in the central area ("c"-"d"), approximately 0.306 mm [0191]
remaining thickness at the bottom of the central area,
approximately 0.050 mm [0192] (total thickness of the substrate,
0.306+0.050=0.356)
Accommodating Crossing Wires
[0193] In some cases, depending on the pattern of the antenna, it
may be necessary for the antenna wire to cross itself. For example,
see compare FIG. 4 of U.S. Pat. No. 6,088,230 and FIG. 5 of U.S.
Pat. No. 6,233,818. FIG. 1A also shows an antenna pattern which has
a crossover. Typically, a short circuit is avoided because the wire
is insulated (and the sonotrode may be switched off in the vicinity
of the crossover).
[0194] The use of channels can be advantageous for mounting an
antenna wire in a pattern that requires the antenna wire to cross
over itself, without shorting. For example: [0195] a first portion
of the antenna wire may be "fully" embedded in a channel, without
protruding above the surface of the substrate. The channel may be
made deeper than the wire at the point where crossover will occur
to ensure that the antenna wire is indeed fully embedded. [0196]
Then, a second portion of the antenna wire which crosses over the
first portion may be laid on the surface of the substrate.
[0197] Alternatively, [0198] a first portion of the antenna wire is
fully embedded in a channel (or portion of the overall channel)
which is very deep where the second portion will be crossing over
[0199] the second portion of the antenna wire is embedded in a
channel (or portion of the overall channel) which is "normal" depth
for accepting a wire conductor [0200] The depth of the first
channel portion is sufficient that the second portion of the wire
crossing over the first portion of the antenna wire does not short
thereto.
[0201] FIG. 4 illustrates the latter variation where there is a
shallow channel 452a crossing over a deep channel 452b. The
channels 452a and 452b may be portions of a single overall channel
in the substrate 402.
[0202] A first portion 410a of the antenna wire 410 is disposed in
the deep portion 452b of the channel, and is shown in dashed lines.
A second portion 410b of the antenna wire is disposed in the
shallow portion 452a of the channel. In this manner, the second
portion of the antenna wire may pass over the first portion of the
antenna wire without contacting it. Some exemplary dimensions are:
[0203] the wire may have a diameter of 80 .mu.m [0204] the
channel(s) may have a width of 100 .mu.m [0205] the shallow channel
may have a depth of 100 .mu.m [0206] the deep channel may have a
depth of 200 .mu.m [0207] the substrate may have a thickness of 350
.mu.m
[0208] Generally, insulated and/or self-sticking (self-bonding)
wire would be used. But using these techniques, un-insulated (bare)
wire may also be used, again avoiding the necessity of removing
insulation from connection portions of the wire.
[0209] Once the channel is created, the wire conductor (which may
be a self-bonding wire) can be installed into the channel and
simultaneously thermally or chemically activated (with laser, hot
air, with alcohol), so that the adhesive layer of the self-bonding
wire sticks to the walls of the channel.
Forming the Channels and Laying the Wire(s) into the Channel(s)
[0210] Techniques for forming channels in the inlay substrate and
subsequently (including during forming the channels) laying (or
routing) the wire in the channels have been described hereinabove.
The inlay substrate may, for example, be a synthetic material such
as Teslin.TM. or PC (polycarbonate).
[0211] In U.S. Pat. No. 6,233,818 the wire is embedded on (or in)
the surface of the inlay substrate using ultrasonic energy (and a
sonotrode). This can be problematic when using materials such as
Teslin.TM. for the inlay substrate. Filler material in the
Teslin.TM. inhibits the wire from embedding well. In such cases,
the wire can only be embedded onto (and only slightly into) the
surface of the substrate. A wire which is not fully embedded in the
substrate results in an uneven topology, and with a thin cover
material the antenna will be evident. Hence, in a subsequent step
the wire is pressed with a laminator (heat and pressure) further
into the surface of the substrate. This lamination step may also
adversely affect the chip module. This issue of "hiding" the wire
may be more problematic on passports where the cover material is
relative soft and thin, in contrast with smart cards where there
may be several layers of harder and thicker cover material.
[0212] According to an embodiment or aspect of the invention, it
may be simpler and more efficient to lay the wire in pre-formed
channels. The term "inlaying" may be used to describe this process,
to distinguish it from any ultrasonic form of embedding. Other
suitable terms may be "scribing", "inserting", "laying", "putting",
"routing", and the like (as well as grammatical variations
thereof). Generally, if ultrasonics are not required to mount the
antenna wire to the inlay substrate, a sonotrode is not
required.
[0213] The channel for receiving an antenna wire may be
substantially the same width and depth as the diameter (for a
non-round wire, a relevant width dimension) of the antenna wire,
typically in the range of 30-112 .mu.m. The channel may be slightly
narrower than the wire, to receive the wire with an interference
fit. The channel may be wider than the antenna wire.
[0214] The channel for receiving an antenna wire may be at least as
deep as the diameter (for a non-round wire, a relevant depth
dimension) of the wire, so that the wire is completely submerged in
the channel. The channel may be shallower than the diameter of the
wire, and a protruding wire may be left to protrude, or
subsequently pressed into the substrate so as to be completely
submerged. The channel may be deeper than the antenna wire to
ensure that the antenna wire becomes completely submerged in the
channel.
[0215] The channel may be formed using laser scanning ablation.
Scanning means that the laser beam traverses the inlay substrate in
at least one direction. For example, after making one pass (or
row), the laser may be moved to the side for a subsequent pass in
the same or opposite direction. (An analogy may be beam scanning in
a Cathode Ray Tube television). Various parameters of the laser may
be altered or adjusted for (or even during) each pass including
wavelength, fluence, repetition rate, pulse width, beam shape,
angle of incidence and dwell time.
[0216] If the diameter of the laser beam is sufficiently wide
(corresponding with the desired width of the channel), and has
sufficient fluence (to penetrate to the desired depth of the
channel), the channel may be formed with one pass of the laser. To
enhance the quality of the structures in a channel, it is
advantageous to use an ultrafast laser (in the picosecond range)
using a low fluence above the threshold fluence and removing
material layer by layer (several passes). At high fluence, there is
a trade-off in material removal and the quality of etching.
[0217] Or, multiple passes of the laser can be scanned across the
length of the channel to increase the width and/or depth of the
channel, each pass of the laser ablating the channel to an
increased depth, in an iterative manner. For example, several
passes of the laser may be used to form a channel having an overall
depth of 80 .mu.m by ablating a 30 .mu.m wide, 5-10 .mu.m deep
amount of material with each pass. For example, to form a channel
having a width of approximately 100 .mu.m (such as 97 .mu.m) and an
overall depth of 80 .mu.m, multiple passes of a laser having a beam
width of 30 .mu.m may be used. In one pass, the 30 .mu.m diameter
beam may ablate approximately a 70 .mu.m wide area, to an average
depth of approximately 5 .mu.m. In subsequent passes, the beam may
be overlapped with a previously ablated area, such as with a 50%
overlap. In three or four passes, the 100 .mu.m wide channel may be
ablated.
[0218] Generally, the laser beam may be directed to the surface of
a substrate via a galvanometer. The laser beam ablates the material
line for line with an overlap of about 50-60% to get the best
surface finish.
[0219] The width of the laser beam (hence, the resulting width of
ablation) may be modified optically (beam shaping--such as with
lenses, using a mask or changing the beam shape) to have a narrower
laser beam width. The penetration of the laser beam (hence, the
resulting depth of ablation) may be modified by changing the
fluence and or repetition rate of the laser.
[0220] The channel may be formed with many (several) passes of the
laser, each pass forming a portion of the overall channel. For
example, a first pass of the laser may form a first portion of the
channel having a width of approximately 100 .mu.m (such as 97
.mu.m) and a depth of 5 .mu.m (dependent on the laser pulse energy
and repetition rate). A second and several subsequent aligned
passes of the laser may extend the previously formed portion(s) of
the channel deeper, maintaining the same 97 .mu.m width, until an
intermediate channel depth of 45 or 50 .mu.m is achieved--half of
the desired overall depth of the channel. Then, maintaining
alignment, in subsequent several passes the width of the laser beam
may be lessened with each pass, resulting in a bottom portion
(half) of the channel tapering down. In this manner, a channel can
be created which has a profile (cross-section) similar to that of
the wire. This may increase the opportunity for the antenna wire to
stick to the walls of the channel
Some Advantages of Forming Channels
[0221] Antenna wire does not embed well (using a sonotrode)
directly into Teslin.TM.. Therefore, to produce a transponder site,
first an antenna channel is created in the Teslin.TM. with the
appropriate number of turns and having a deeper indent in the
material at the position where the outer wire of the antenna
crosses the antenna wires to reach the chip module for
interconnection.
[0222] Once a channel is created, the wire conductor (a self
bonding wire) can be installed into the channel and simultaneously
thermally activated, so that the adhesive layer of the self bonding
wire sticks to the walls of the channel.
[0223] In the case of Teslin.TM., a normal insulated wire would not
properly embed into the material, it would detach. Therefore,
self-bonding wire is used, and attaches to the material with a
slight penetration of the wire in the material. In the prior art,
to sink the wire into the material, it is necessary that we
pre-press the antenna with chip connected using a hot lamination
press. With pre-formed channels for accepting the wire, such as
using laser ablation, it is not necessary to perform this task.
Profiled/Tapered Channels
[0224] FIG. 5 illustrates an example of forming (multiple pass
channels). A first path "P1" is shown over a central portion of the
channel. A second path "P2" is shown over a left portion of the
channel. A third path "P3" is shown over a right portion of the
channel. The order of these paths can be different.
[0225] Notice that the channel in the figure is "stepped". This
represents making several passes with the laser, at a few (such as
three) widthwise positions (paths P1,P2,P3). Each pass of the laser
may only remove 5 .mu.m of material, in which case 20 passes would
be needed to achieve a depth of 100 .mu.m at any given
position.
[0226] The channel can be rectangular (straight sidewalls). The
channel can be tapered, or U-shaped. In FIG. 5, the top half (such
as upper 50 .mu.m) of the channel has straight sidewalls, and the
lower half (such as bottom 50 .mu.m) of the channel decreases in
width as the depth increases, thereby the sidewalls are tapered,
and approximate the semicircular profile of the bottom half of the
antenna wire (shown in dashed lines). This increases the contact
area between the sidewalls of the channel and the antenna wire,
which will enhance adhesion of a self-bonding wire in the
channel.
[0227] Alternatively, masks may be used to block portions of the
laser bean and effect a similar stepwise decrease in width
accompanying increase in depth.
[0228] Some exemplary operating conditions for the laser may be:
[0229] operating the laser at a pulse repetition rate of 30-40 kHz
(one pulse every approximately 30 microseconds) [0230] the duration
of each pulse may be approximately 30 picoseconds
[0231] This low duty cycle (relatively short pulse in a relatively
long interval) is advantageous for "cold ablation", where the
material is not significantly heated.
[0232] The polymer substrate may be porous, facilitating the laser
ablation, and the ablation may be performed in an inert atmosphere.
Debris can be removed through a suction system.
[0233] The antenna wire may be bare (non-insulated wire). The
antenna wire may be insulated wire, typically having a copper core
coated with a layer of modified polyurethane (an insulating
material). The antenna wire may be self-sticking wire, typically
having a coating (layer) of polyvinylbutyral. The antenna wire may
be insulated and self-sticking, having a coating of polyurethane
covered by a coating of polyvinylbutyral. Typical dimensions for a
round, insulated, self-sticking wire may be: [0234] Diameter of
copper core: 80 .mu.m [0235] Thickness of insulating layer of
polyurethane: 4 .mu.m [0236] Thickness of the self-sticking layer
of polyvinylbutyral: 4.5 .mu.m
[0237] Materials other than copper may be used for the wire.
Elektrisola (product name: Polysol 155) has been mentioned above.
See
http://www.elektrisola.com/self-bonding-wire/common-self-bonding-wire-typ-
es/iecjis.html
[0238] The pattern (turns) of the antenna wire may involve the wire
crossing over itself, in which case an insulated wire would
typically be used. Using channels, such as shown in FIG. 15, the
wire may be bare wire, since one the upper channel is sufficiently
higher than the lower channel that the wire in the upper channel
(shallow portion of the channel) is physically separated from the
wire in the lower channel (deep portion of the channel). (If the
two bare portions of the antenna wire pass over each other, without
touching, there is no subsequent "shorting".) A dab of glue or
other electrically insulating material may be disposed on the wire
at the crossover between the two portions of wire (such as atop the
lower portion). An analogy may be a bridge roadway (analogous to a
portion of the wire in an upper portion of the channel) passing
over a highway roadway (analogous to a portion of the wire in the
lower portion of the channel.
[0239] Self-sticking antenna wire may be attached to the walls
(sides and/or bottom) of the channel by means of heat (such as
hot-air, ultrasonics, UV or IR light) during the process of routing
the wire into the channel
[0240] Heat may be applied to ensure that the antenna wire stays in
the channel, at least temporarily, such as until a cover layer is
applied and adhered onto the substrate. Lamination of the cover
layer onto the substrate will result in the antenna wire will be
"trapped" in the channel. The cover layer may be laminated to the
inlay substrate carrying the chip module and antenna wire using a
hot melt adhesive, such as reactive polyurethane. With a channel
having a depth slightly less than the diameter of the wire, the
wire will project slightly from the substrate, and a more robust
adhering of the wire to the cover layer may be achieved, providing
a security feature" that the antenna will be dislodged during
de-lamination (presumably for illegal purposes) of the cover layer
from the substrate.
[0241] The channel for accepting the antenna wire may advertently
be made wider (such as 110 .mu.m wide rather than 100 .mu.m wide)
at selected areas along the length of the channel so that the
antenna wire does not attach well at these wider sections. For
example, there may be a series of wider portions, each 1 mm in
length, disposed every 5 mm along the length of the channel, at
least in a portion of the channel if not along the entire channel.
A result of this is that the antenna wire may not stick well in
these wider areas, and if an attempt is made to separate the cover
layer from the inlay substrate, the antenna wire may tear out of
the channel. This may be considered to be a "security feature".
Compare FIG. 9A wherein the inlay substrate is perforated to ensure
its self-destruction if tampered with.
Connecting the Wire to the Chip Module
[0242] Any suitable technique may be used for connecting the
antenna wire to the chip module, including some of the techniques
of the prior art. As this disclosure is directed mainly to the
mounting aspect (getting the wire into the substrate), only a few
examples will be presented herein directed to the connecting
aspect.
[0243] In the aforementioned U.S. Pat. No. 6,088,230, mounting and
connecting the antenna wire may be performed as follows: [0244]
starting by bonding a first end of the antenna wire to a first one
of two chip terminals, [0245] then embedding the wire in the
substrate to form the turns of the antenna, [0246] then returning
to the chip module and bonding a second end of the antenna wire to
the second terminal of the chip module
[0247] As mentioned above, this process required a "dual purpose"
bonding/embedding tool.
[0248] According to an embodiment of the invention, mounting and
connecting the antenna wire may be performed as follows: [0249]
starting by bonding a first end of the antenna wire to a first one
of two chip terminals, [0250] then routing the wire into pre-formed
channels in the substrate to form the turns of the antenna, [0251]
then returning to the chip module and bonding a second end of the
antenna wire to the second terminal of the chip module
[0252] This would avoid the need for a complicated "dual purpose"
bonding/embedding tool.
[0253] FIG. 6A shows a chip module having two terminals disposed in
a recess in a substrate. This recess is shown as extending
completely through the substrate, hence an underlying support layer
is included. A channel for accepting a wire is shown extending from
the right (as viewed) side of the recess. The channel may be formed
by laser ablation. The recess may also be formed by laser
ablation.
[0254] A short length of "residual" wire is shown extending from a
wire feed mechanism, such as the capillary of a sonotrode. An
exemplary mounting operation may proceed as follows: [0255] with a
residual first end portion of the wire extending from the capillary
positioned directly over the chip terminal, the capillary is
lowered to begin laying the wire in the channel. [0256] the turns
of the antenna are formed, following the pattern of the channel
[0257] the capillary returns to the chip module and positions a
second end portion of the wire directly over the second terminal of
the chip module. (omitted, for illustrative clarity) [0258] then,
in a connecting phase, a thermode is brought down onto the end
portions of the wire to bond them to the terminals of the chip
module. (See FIG. 1A)
[0259] FIG. 6B shows that a suction system may be employed to
create an airflow maintaining the "floating" end portions of the
wires above the corresponding terminals of the chip module, for
bonding thereto.
[0260] FIG. 6C shows a chip module 608 disposed in a recess 606 in
a substrate 602. The chip module has two terminals 608a and 608b. A
channel 652 is formed in the surface of the substrate. An antenna
610 may be mounted in the channel and connected to the chip module,
as follows: [0261] a dab (or spot) of glue 620 is disposed on the
chip module 608, such as on the mold mass, between the terminals.
One relatively large spot of glue may be disposed approximately in
the middle of the chip module 608, and extending beyond the side
edges of the chip module, and slightly onto the inlay substrate 602
[0262] stick a first end of the antenna wire 610 into the dab of
glue 620. This can be done with the wire placing tool, while
applying heat. The dashes "-" indicate that the antenna wire is
stuck (not embedded, not bonded) in the dab of glue. [0263] using
the wire guide tool, draw (guide) the antenna wire 610 over the
first terminal 608a of the chip module 608. This results in a first
end portion 610a of the antenna wire 610 being disposed over the
first terminal 608a of the chip module 608. [0264] then guide the
antenna wire 610 away from the chip module 608 onto the inlay
substrate 602, laying the wire in the channel 652 and forming the
turns of the antenna, commending at the point "c" [0265] return to
the chip module, and with the wire guide tool, draw (guide) the
antenna wire 610 over the second terminal 608b of the chip module
608. This results in a second end portion 1010b of the antenna wire
1010 being disposed over the second terminal 1008a of the chip
module 1008 [0266] cut the antenna wire 610. Optionally, prior to
cutting the wire, stick the second end of the wire into the dab of
glue. [0267] In a second (connecting) phase, connect (bond) the end
portions of the wire to the terminals.
[0268] FIGS. 7A-7C illustrate another technique 700 for mounting
and connecting an antenna wire. A stepped recess 706 for a chip
module 708 is formed in a substrate 702 and has an upper portion
706a and a lower portion 706b. The recess 706 may be formed by
laser ablation. In conjunction with forming the recess 706, a
channel (752) for accepting the antenna wire (710) is formed.
[0269] A first portion 752a of the channel (752) extends into the
surface of the substrate 702, and continues (as an "extension"
752a' of the portion 752a) into the surface of the lower portion
706b of the recess 706. A second portion 752b of the channel (752)
extends into the surface of the substrate 702, and continues (as an
"extension" 752b' of the portion 752b) into the surface of the
lower portion 706b of the recess 706.
[0270] When the wire (710) is laid into the channel (752), a first
end portion 710a of the wire is laid into the extension 752a' of
the first portion 752a of the channel, and a second end portion
710b of the wire is laid into the extension 752b' of the second
752b of the channel. (The wire is omitted from the view of FIG. 7B,
for illustrative clarity.)
[0271] The channel and recess may be formed sequentially. For
example, first form the channel for accepting the antenna wire in
the surface of the substrate, then after laying down the wire in
the antenna channel (104 cm), the stepped recess is created in the
polymer substrate to accept the chip module. During forming the
recess, the end portions of the wire are "in the way" and the self
bonding layer and insulation layer will be removed from the wire at
the positions where the end portions of the antenna wire will
exposed to the terminal areas of the chip module. Then the chip
module may be installed in the recess and connected with the end
portions of the antenna wire.
[0272] Alternatively, as illustrated, the channels and recess are
fully formed before the antenna wire is laid into the channels.
[0273] Another alternative may be to connect the end portions of
the antenna wire to the terminal areas of the chip module prior to
installing the chip module into the recess. (The chip module would
be supported immediately above the recess during connecting the
wire to the terminals and laying the wire into the antenna
channel.)
[0274] FIG. 7C shows that after the wire is laid into the channel,
the chip module 708 may be installed into the recess 706, with the
mold mass down. The orientation with mold mass down is similar to
FIG. 1D, but in FIG. 7C the end portions of the wire to be
connected to the leadframe are on the mold mass (down) side of the
leadframe.
[0275] The wire may be self-bonding wire. In the process of forming
the recess and channel, and laying the wire, additionally
insulation (the self bonding layer and insulation layer) may be
removed from the top (exposed) surface of the end portions of the
wire to facilitate connecting to terminal areas of the
leadframe.
[0276] Two terminal areas 708a and 708b are illustrated. These are
essentially portions of the leadframe. A hole 709a is created
through the terminal area 708a to expose a portion of the
underlying end portion 710a of the wire. A hole 709b is created
through the terminal area 708b to expose a portion of the
underlying end portion 710b of the wire. The end portions 710a and
710b may be connected in any suitable manner to the corresponding
terminal areas 708a and 708b of the leadframe (of the chip module
708). For example, by soldering. Or, a beam from a laser 760 can be
directed through the holes 709a and 709b in the respective terminal
areas 708a and 708b to effect the connection (laser welding) of end
portions 710a and 710b to terminal areas 708a and 708b.
[0277] The holes 709a and may be micro holes which are percussion
drilled into the metal leadframe of the chip module at each
terminal area. This allows for the welding, soldering or crimping
of the leadframe terminals to the respective end portions of the
antenna wire. For the interconnection per welding, the laser beam
is directed into the hole, causing the copper wire to reach its
melting point in a matter of nanoseconds (ns), picoseconds (ps) or
femtoseconds (fs). The chip module with the micro holes may be
placed over the wires for interconnection.
[0278] Some exemplary dimensions are: [0279] overall thickness "a"
of the substrate 702, approximately 356 .mu.m [0280] depth of an
upper portion 752a of the channel 752 extending into the top
surface of the substrate 702, approximately 100 .mu.m [0281] depth
"b" of an upper portion 706a of the recess 706 which accepts the
leadframe, approximately 80-100 .mu.m [0282] depth "c" of portion
752b of the channel 752 in the bottom of the upper portion 706a of
the recess 706, approximately 100 .mu.m to accommodate a wire have
a diameter of approximately 80 .mu.m [0283] depth "d" of a lower
portion 706b of the recess 706 which accommodates the mold mass of
the chip module, approximately 180 .mu.m (from the bottom of the
upper portion 706a) [0284] a remaining thickness "e" of the
substrate 702 under the lower portion 706b of the recess,
approximately 100 .mu.m. [0285] the total thickness "a" equals the
depth "b" of the upper portion 706a plus the depth "d" of the lower
portion 706b plus the thickness "e" of the remaining portion 702b
of the substrate under the lower portion 706b.
[0286] Notice in FIG. 1D that the end portions of the wire are
connected on an opposite side of leadframe than the mold mass. And,
in FIG. 7C, the end portions of the wire are connected on the same
side of leadframe as the mold mass
[0287] The channels and recess in the substrate may be ablated with
a nanosecond (ns), picosecond (ps) or femtosecond (fs) laser
operating at UV (ultraviolet), VIS (visible) or IR (infrared). The
substrate may be a polymer, such as porous (Teslin.TM.) or
non-porous (polycarbonate) or can be doped to facilitate the laser
ablation process. The ablation can take place in an inert
atmosphere and the polymer can be heated or chilled prior to laser
treatment. Laser ablation is particularly good with a porous
polymer, as its porosity facilitates the ablation process.
[0288] It should be understood that some of the techniques
described hereinabove for forming channels and routing the antenna
wire into the channel may be performed in a layer (or film) of
adhesive on an inlay substrate rather than in the substrate
itself.
Some Additional Features which May be Formed Using Laser
Ablation
[0289] In addition to forming recesses and/or channels for
accepting wire, other mechanical and security features may be
incorporated into the inlay, using laser ablation.
Trenches for De-Stressing the Substrate Layer During Hot
Lamination
[0290] FIG. 8 illustrates a recess formed in an inlay substrate.
The inlay substrate may be for a national ID card, and may comprise
Teslin.TM. or polycarbonate (PC). The recess may, for example, be 5
mm.times.8 mm. The chip module may be an epoxy-glass module, and is
omitted, for illustrative clarity.
[0291] Trenches (grooves, channels, slots, perforations, small
recesses) may be formed near (adjacent, next to) the recess, such
as within a few millimeters thereof. The trenches may be short line
segments, such as 0.5 mm wide by 2 mm long, and arranged in a
pattern radiating from the periphery of the recess. The trenches
may be oriented differently than shown. The trenches may extend to
near the perimeter of the recess, or may extend completely to the
recess. Both variations of trenches are shown in FIG. 8.
[0292] The trenches extend at least partially through the inlay
substrate (from the front surface thereof towards the back surface
thereof), and may provide stress relief to de-stress the inlay
substrate layer during hot lamination of the cover layer to the
inlay substrate. For example, for an 80 .mu.m thick inlay
substrate, the "stress-relief" trenches may extend only
approximately 40 .mu.m through the substrate.
[0293] The trenches may allow for flexure of the inlay substrate,
such as during hot lamination, without buckling, which otherwise
may result in a bumpy or dented front surface of the substrate.
[0294] The stress-relief trenches constitute what may be referred
to as a "mechanical feature" of an inlay substrate.
Perforations to Prevent De-Peeling (or Delamination)
[0295] FIGS. 9A,B,C illustrate a "protected area" around a chip
module connected to an antenna in an inlay substrate. The inlay
substrate (e-cover inlay) may be for an electronic passport, and
may comprise Teslin.TM.. The inlay substrate is adhesively attached
to a passport cover material.
[0296] At the protected area, a recess may for example, be
rectangular to accommodate the chip module connection areas on a
leadframe or printed circuit board, having a recess depth of
approximately 60 microns in the Teslin.TM. layer. The chip module
may be an epoxy-glass module.
[0297] Perforations (trenches, grooves, channels, slots, small
recesses) may be formed around the protected area, such as within a
few millimeters thereof. The perforations may be short line
segments, such as 0.5 mm wide by 0.5 mm long, and arranged in any
suitable pattern at least partially encircling the protected area.
Alternatively, the perforations may be in a line (or lines) passing
across the protected area. The perforations can be other than
straight line segments, such as "s" shaped, and may overlap and/or
intersect each other.
[0298] The perforations may extend fully through the inlay
substrate (from the front surface thereof towards the back surface
thereof).
[0299] If an attempt is made to peel the inlay substrate from the
cover material, the perforations may encourage (cause) the inlay
substrate to tear. The perforations represent points (or areas) of
weakness, making the inlay substrate frangible (capable of being
easily broken).
[0300] The perforations constitute what may be referred to as a
"security feature" of an inlay substrate.
[0301] At the protected area, the chip module is connected to the
antenna and if any attempt is made to peel the inlay substrate from
the cover material, the wire interconnections to the chip module
are destroyed, resulting in permanent damage to the chip
module.
[0302] FIG. 9C illustrates (generally) initiating peeling the cover
material layer from the inlay substrate, and consequent destruction
of the inlay substrate which is facilitated by the
perforations.
[0303] As best viewed in FIG. 9A, both ends of the antenna wire may
approach the chip module from the same side of the recess. (Of
course, in the case of a round recess, from the same
direction.)
Notches for Holding the Chip Module in Position
[0304] FIGS. 10A and B illustrates a recess formed in an inlay
substrate. The inlay substrate may be for a national ID card, and
may comprise Teslin.TM. or polycarbonate (PC).
[0305] The recess may, for example, be 5 mm.times.8 mm. The chip
module may be an epoxy-glass module, and is omitted, for
illustrative clarity.
[0306] Notches may be formed in a manner similar to other laser
ablated features (such as the aforementioned trenches, grooves,
channels, slots, perforations, small recesses). The notches may
extend from one or more side edges of the recess to external the
recess. The notches may semicircular, or triangular (for example),
having a cross-dimension (base, height, diameter) of approximately
1 mm.
[0307] The notches may extend at least partially through the inlay
substrate (from the front surface thereof towards the back surface
thereof). For example, for an 80 .mu.m thick inlay substrate having
a 60 .mu.m deep pocket-type recess, the notches may extend as deep
as the recess.
[0308] Pins, such as wedge-shaped pins, may be inserted into the
notches which will decrease the cross-dimension of the recess,
thereby holding the chip module in place, such as for further
handling (applying adhesive and cover layer).
[0309] The pins would have a cross-dimension (diameter) slightly
greater than the cross-dimension of the notch, so that when a pin
is inserted into the notch, the inlay substrate material between
the notch and the recess deflects towards the chip module, holding
(pinching) it in place,
[0310] The notches (and pins) may eliminate the need for gluing the
chip module in place and allowing for easy handling of the inlay
substrate during wire embedding and interconnection processes.
[0311] The notches constitute what may be referred to as a
"mechanical feature" of an inlay substrate.
Slots for Holding the Chip Module in Position
[0312] FIG. 11A,B illustrates a recess formed in an inlay
substrate. The inlay substrate may be for a national ID card, and
may comprise Teslin.TM. or polycarbonate (PC).
[0313] The recess may, for example, be 5 mm.times.8 mm. The chip
module may be an epoxy-glass module, and is omitted, for
illustrative clarity.
[0314] Slots may be formed in a manner similar to other laser
ablated features (such as the aforementioned notches, trenches,
grooves, channels, perforations, small recesses). The slots may be
disposed outside of the recess, but near to the recess. The slots
may be rectangular, measuring 5-8 mm.times.1 mm.
[0315] The notches may extend at least partially through the inlay
substrate (from the front surface thereof towards the back surface
thereof). For example, for an 80 .mu.m thick inlay substrate having
a 60 .mu.m deep pocket-type recess, the slots may extend as deep as
the recess.
[0316] In a manner similar to the notches/pins described above
(FIG. 13), the slots may eliminate the need for gluing the chip
module in place, especially when moving inlay substrates with a
format of transponder sites from one production process to the
next. Further, using glue to adhesively attach a chip module to an
inlay substrate has the disadvantage that the surface finish of the
inlay substrate after lamination highlights the position of the
chip module in an electronic passport or national identity card
which is a security risk.
[0317] Optionally, pins, such as wedge-shaped pins, may be inserted
into the slots which will decrease the cross-dimension of the
recess, thereby holding the chip module in place, such as for
further handling (applying adhesive and cover layer).
[0318] The pins would have a cross-dimension (diameter) slightly
greater than the cross-dimension of the slots, so that when a pin
is inserted into the slots, the inlay substrate material between
the slots and the recess deflects towards the chip module, holding
(pinching) it in place,
[0319] The slots constitute what may be referred to as a
"mechanical feature" of an inlay substrate.
Some Additional Mechanical and Security Features
[0320] A hologram may be created using the laser on the underside
of the inlay substrate, such as opposite the chip module. This
would create a visible "security feature".
[0321] Some inlay substrates comprise polycarbonate, and tend to
develop micro cracks in the area of the chip module (around the
recess). To reduce the formation of (prevent) micro cracks
developing in polycarbonate (PC), at the position of the chip
module (around the edge of the recess), the material of the
substrate can be laser treated, a form of annealing it at the
threshold fluence (just below ablating, with incubation
effect).
[0322] FIG. 12A shows a chip module 1208 installed in a recess 1206
of an inlay substrate 1202. A side extension, or edge region 1230
of the substrate may be thinned by laser ablation such as to a
fraction of the substrate's original thickness, such as to
approximately 50% of the original thickness. A laser 1250 is shown
ablating from the top (as viewed) surface of the substrate, but it
will be understood that the ablating could occur from the bottom
surface of the substrate 1202, or from both the top and bottom
surfaces of the substrate 1202. By thinning the substrate at an
edge region, an "overlap joint" may be made with another element,
such as a flap of plastic material 1270 (shown in dashed lines).
Reference is made to U.S. Pat. No. 6,213,702, incorporated by
reference herein.
[0323] FIG. 12B shows that laser ablation may be used to create
"studs" 1232 along the edge region 1230 of the substrate 1202 for
inserting into holes of a separate element (not shown, such as a
plastic flap).
[0324] FIG. 12C shows that laser ablation may be used to create
holes 1234 along the edge region 1230 of the substrate 1202 for
receiving mating studs of a separate element (not shown, such as a
plastic flap).
[0325] Generally, laser ablation may be used to thin an entire
region of the substrate, and to form 3-dimensional features such as
studs in a thinned region of the substrate, or to form holes in a
thinned region of the substrate. Each of these would constitute a
"mechanical feature" of an inlay substrate which may be used to
create an interlocking clamp between a flap and a data page inlay
using laser ablated studs and recesses.
[0326] While the invention has been described with respect to a
limited number of embodiments, these should not be construed as
limitations on the scope of the invention, but rather as examples
of some of the embodiments. Those skilled in the art may envision
other possible variations, modifications, and implementations that
are also within the scope of the invention, based on the
disclosure(s) set forth herein.
* * * * *
References