U.S. patent application number 11/061857 was filed with the patent office on 2005-09-15 for equipment and methods for producing continuous metallized thermoformable emi shielding material.
This patent application is currently assigned to Wavezero, Inc.. Invention is credited to Arnold, Rocky R., Zarganis, John C..
Application Number | 20050202723 11/061857 |
Document ID | / |
Family ID | 32030649 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050202723 |
Kind Code |
A1 |
Arnold, Rocky R. ; et
al. |
September 15, 2005 |
Equipment and methods for producing continuous metallized
thermoformable EMI shielding material
Abstract
The present invention provides in-line equipment and methods for
manufacturing an EMI/RFI shield that is integrated formed in a
formable sheet. The EMI/RFI shield may comprise a shaped thermoform
shell that has one or more conductive layers applied to one or more
surfaces. The EMI/RFI shield may be integrally formed with the
formable sheet via attachment tabs that are positioned along one or
more edges of the EMI/RFI shield.
Inventors: |
Arnold, Rocky R.; (San
Carlos, CA) ; Zarganis, John C.; (Redwood City,
CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Wavezero, Inc.
Sunnyvale
CA
Shielding for Electronics, Inc.
Sunnyvale
CA
|
Family ID: |
32030649 |
Appl. No.: |
11/061857 |
Filed: |
February 17, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11061857 |
Feb 17, 2005 |
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10664838 |
Sep 17, 2003 |
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6909615 |
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60411104 |
Sep 17, 2002 |
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Current U.S.
Class: |
439/607.17 |
Current CPC
Class: |
H05K 9/0084 20130101;
H05K 9/0088 20130101; H05K 9/003 20130101 |
Class at
Publication: |
439/609 |
International
Class: |
H01R 013/648 |
Claims
What is claimed is:
1. An EMI/RFI shield integrally formed in a thermoformable sheet,
wherein portions of the thermoformable sheet are removed around a
periphery of the EMI/RFI shield, wherein the portions of the
thermoformable sheet that are not removed integrally connect the
EMI/RFI shield to a remainder of the thermoformable sheet.
2. The EMI/RFI shield of claim 1 wherein the EMI/RFI shield
comprises at least one layer of a conductive material.
3. The EMI/RFI shield of claim 2 wherein the EMI/RFI shield is
multi-compartmentalized.
4. The EMI/RFI shield of claim 2 wherein the EMI/RFI shield defines
a single compartment.
5. The EMI/RFI shield of claim 2 wherein the layer of conductive
material comprises at least one layer of tin, aluminum, copper, and
nickel.
6. The EMI/RFI shield of claim 5 wherein the conductive material
comprises a vacuum metallized first layer of tin and an
electroplated second layer of tin.
7. The EMI/RFI shield of claim 1 wherein the formable polymer sheet
comprises a recycled, conductively coated polymer EMI/RFI shield
that has been mechanically disintegrated and then recombined back
into the formable polymer sheet.
8. The EMI/RFI shield of claim 7 where the mechanically
disintegrated EMI/RFI shields comprise a metallized film comprising
one of a painted film, a vacuum metallized film, and an electroless
plated film.
9. The EMI/RFI shield of 1 wherein the EMI/RFI shield comprises a
top surface, a plurality of sidewalls extending at an angle from
the top surface and a flange around a periphery of the side walls,
wherein the flange and the top surface define substantially
parallel planes.
10. A reel of material for in-line processing equipment, the reel
comprising: a sheet of material; a spool that receives the sheet of
material; and a plurality of EMI/RFI shields attached to the sheet
of material that is rolled on the spool.
11. The reel of material of claim 10 wherein the EMI/RFI shields
are integrally attached to the sheet of material.
12. The reel of material of claim 11 wherein the EMI/RFI shields
are attached to the sheet of material with tabs of material.
13. The reel of material of claim 10 wherein the EMI/RFI shields
comprise at least one layer of conductive material.
14. The reel of material of claim 10 wherein the EMI/RFI shields
and sheet of material comprise recycled material.
15. An EMI/RFI shield integrally attached to a formable polymer
sheet formed by a method comprising: shaping the formable polymer
sheet to create at least one EMI/RFI shield; applying a conductive
layer to the formable polymer sheet; and removing a portion of the
material around a periphery of the conductive EMI/RFI shield so as
to leave the EMI/RFI shield integrally attached to a remainder of
the formable polymer sheet.
16. The EMI/RFI shield of claim 15 wherein the shaping is carried
out before the applying the conductive layer.
17. The EMI/RFI shield of claim 15 wherein the shaping is carried
out after applying the conductive layer.
18. The EMI/RFI shield of claim 15 further comprising applying a
gasket to the EMI/RFI shield.
19. The EMI/RFI shield of claim 15 comprising forming the polymer
sheet from recycled material that comprises conductive
material.
20. The EMI/RFI shield of claim 15 wherein removing a portion
comprises leaving tabs of material that integrally connect the
EMI/RFI shield to the formable polymer sheet.
21. The EMI/RFI shield of claim 5 wherein the conductive material
comprises a vacuum metallized first layer of tin and an
electroplated second layer of nickel.
22. The reel of material of claim 12 wherein the tabs of material
are perforated.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of patent
application Ser. No. 10/664,838 filed Sep. 17, 2003, which claims
benefit to provisional patent application Ser. No. 60/411,104,
filed on Sep. 17, 2002, entitled "Equipment for Producing
Continuous Metalized Thermoformable EMI shielding Material for Tape
& Reel Applications," the complete disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to methods and
devices for in-line processing of a substrate. More specifically,
the present invention relates to in-line methods of producing a
metallized, shaped product on a sheet, for use in tape and reel
applications.
[0003] Production of thermoformed pieces (e.g., small boxes to hold
screws, packaging for consumer products, etc.) often relies upon
the use of "in-line" processing equipment. In a typical
application, a roll of polymer based material (such as PVC,
polyester, etc.) is removed from a spool that has a standard width,
generally between 10" and 42" and the sheet is pulled into a series
of connected, but independent, equipment or stations that modify
the polymer sheet sequentially to form the final piece.
[0004] Specifically, after the material is unspooled and heated to
the required processing temperature, the material is thermoformed
or otherwise shaped. If thermoformed, the polymer based material is
heated (or cooled) to a target processing temperature (usually
between 250.degree. F. and 375.degree. F., depending upon the
polymer and subsequent processing steps). The polymer based
material may then enter a processing station in which hard (e.g.,
aluminum, steel or ceramic) tooling may be used to shape the
polymer-based material. Heat, in addition to vacuum, pressure, or
mechanical molding, may be used to achieve the desired shape of the
product. The metal or ceramic tooling often involves both dies and
molds to achieve the required shape and mechanical details. This
processing involves high pressures but is rapidly accomplished,
e.g., a matter of seconds. In a subsequent step, the polymer based
material may be pulled through to another station that cuts the
final part away from the remaining material of the sheet.
[0005] While conventional methods of shaping and processing
polymer-based sheets have been effective, there remains a need for
methods and equipment that produce thermoformed products in a cost
and time effective in-line process. In particular, there remains a
need to produce metallized thermoformed products in an in-line
process.
BRIEF SUMMARY OF THE INVENTION
[0006] The present invention provides in-line processing equipment
and methods for in-line processing of a substrate. The present
invention also provides novel stations for in-line plastic
processing equipment and products (such as an EMI/RFI shield) that
are integrally attached to a sheet.
[0007] The in-line equipment of the present invention may include
some combinations of stations to heat, shape (e.g., thermoform),
apply one or more conductive or nonconductive layers, apply
conductive or non-conductive gasketing material, and/or die cut.
Advantageously, it would then be possible to accept at one end of
the in-line equipment, a rolled flat polymer-based sheet (e.g.,
polycarbonate, ABS, PVC, PBT etc.) and conduct a continuous chain
of operations (e.g., in-line) that result in the efficient
production of a complete product that is integrally assembled into
a "tape" structure that is ready for final assembly using standard
robotic component placement equipment or manual processing
methods.
[0008] By connecting all of these processes into an in-line
process, the present invention provides an economical manufacturing
process, in the sense that, at one end, raw material (e.g., a
formable sheet) is input into the equipment and at the output, a
final product, such as an EMI/RFI shield is created. This in-line
processing lowers the overall cost of production of the EMI shield
and is suitable for global manufacturing operations as practiced by
participants in the electronics manufacturing sector (EMS).
[0009] In one aspect, the present invention provides an EMI/RFI
shield integrally formed in a formable sheet, such as a
thermoformable sheet. Portions of the thermoformable sheet are
removed around a periphery of the EMI/RFI shield. The portions of
the thermoformable sheet that are not removed are used to
integrally connect the EMI/RFI shield to a remainder of the
thermoformable sheet. The EMI/RFI shield that is integral with the
sheet may be manufactured by any of the methods and in-line
equipment described herein.
[0010] The EMI/RFI shield may comprise at least one layer of a
conductive material, such as tin, aluminum, copper, and nickel. The
EMI/RFI shield may have a plurality of conductive layers of the
same or different materials. For example, the EMI/RFI shield may
have a vacuum metallized first layer of nickel and a electroplated
second layer of tin or nickel.
[0011] The thermoformable sheet used to form the EMI/RFI shield may
be made from a virgin polymer (such as polypropylene,
polycarbonate, ABS, PVC, PBT, or the like) or it may be composed of
a recycled, conductively coated polymer EMI/RFI shield that has
been mechanically disintegrated and then recombined back into the
formable polymer sheet. The recycled EMI/RFI shield may have been
metallized with a painted film, a vacuum metallized film, an
electroless plated film, or the like.
[0012] The EMI/RFI shield may be a single compartment shield or it
may be multi-compartmentalized. In one embodiment, the EMI/RFI
shield defines a top surface, a plurality of sidewalls extending at
an angle from the top surface and a flange around a periphery of
the side walls that extend at an angel from the side walls.
Typically, the flange and the top surface define substantially
parallel planes.
[0013] In a further aspect, the present invention provides a reel
of material for in-line processing equipment. The reel comprises a
spool that receives a sheet of material. A plurality of EMI/RFI
shields are attached to the sheet of material that is rolled on the
spool. The EMI/RFI shields may be integrally attached to the sheet
of material with tabs of material. Typically, the EMI/RFI shields
have at least one conductive layer applied thereon. The
thermoformable sheet used to form the EMI/RFI shield may be made
from a virgin polymer (such as polypropylene, polycarbonate, ABS,
PVC, PBT, or the like) or it may be composed of a recycled,
conductively coated polymer EMI/RFI shield that has been
mechanically disintegrated and then recombined back into the
formable polymer sheet. The recycled EMI/RFI shield may have been
metallized with a painted film, a vacuum metallized film, an
electroless plated film, or the like.
[0014] In another aspect, the present invention provides in-line
processing equipment for continuously processing a formable sheet.
In one embodiment, the processing equipment comprises at least one
metallization station that metallizes at least one surface of the
formable sheet. One or more shaping stations, such as a
thermoforming station, are positioned before or after the
metallization station in the line to shape the formable sheet into
a shaped product. At least one cutting station is configured to
partially remove material around at least a periphery of the
shaped, metallized product so that the product remains on the
sheet. A transportation assembly moves the formable sheet between
stations.
[0015] The in-line processing equipment may optionally include a
gasketing station that applies a gasket to the shaped, metallized
product. The gasket is typically in the form of an electrically
conductive or electrically insulative adhesive. The gasketing
station may comprises a screen printing assembly to deliver the
pattern of adhesive to one or more surfaces of the product.
Optionally, the adhesive gasket may be in the form of a
prefabricated gasket that is in a predetermined shape that matches
certain features of the shaped product. The adhesive may include a
removable protective liner on an inner and/or outer surface of the
adhesive.
[0016] The cutting station may comprise one or more platens or
rotating cutting members that cut the sheet at selected locations
around the product so as to remove only a portion of the material
around the periphery of the shaped, metallized product. The cutting
station may be configured to leave tabs of material along one or
more edges of the shaped product so that the product remains intact
on the original sheet. Consequently, the entire sheet (with the
attached products) may be moved (either in-line or transported as a
rolled up sheet on a spool) to a final processing station, where
the product may be removed from the sheet and placed on the final
assembly (e.g., PCB or electronic device, such as a cellular
telephone).
[0017] The metallization station may take on a variety of forms.
For example, the metallization station may apply a metal or other
conductive layer via painting, ion deposition, sputtering,
electroplating, vacuum metallization, ink printing (with a
conductive ink), arc plasma, or other conventional metallization
methods. Moreover, instead of a metal layer, the metallization
station may actually deposit a non-conductive or non-metal layer
that comprises conductive material, such as conductive fibers,
conductive particles, or the like.
[0018] In some embodiments, the in-line equipment may comprise a
plurality of metallization stations that deposit a plurality of
different metal layers. For example, a first metallization station
may deposit a first metal layer (e.g., a vacuum deposited layer of
metal, such as nickel) over at least one surface of the sheet. A
second metallization station may deposit a second metal layer over
the first metal layer (e.g., electroplate a layer of metal, such as
tin or nickel over the aluminum first layer). As can be
appreciated, the first metal layer and second metal layer may
directly contact each other, or an intermediate conductive or
non-conductive may be disposed between the first and second metal
layers.
[0019] In one embodiment, the metallization station comprises a
chamber with a top and bottom section. The top and bottom sections
are moveable between an open position which allows a finite length
of sheet to enter the chamber, and a closed position in which the
top and bottom sections or ports of the sections contact the sheet
to create a pneumatic seal around the finite length of sheet. The
chamber may include a metallization source for depositing a metal
material onto the portion of the sheet in the metallization
chamber. The chamber may be configured to evacuate the chamber of
air to a vacuum level sufficient for thermally evaporating metal
onto the finite length of sheet in the chamber. Typically, the
evacuation time will have a comparable cycle time (typically
between approximately 3 seconds and approximately 5 minutes) to the
shaping and cutting stations so as to maintain a consistent feed of
the sheet through the in-line processing equipment. The
metallization station may optionally be configured to rotate and/or
flex the finite length of sheet inside the chamber during
metallization to ensure all surfaces of the sheet and/or product
are substantially evenly metallized.
[0020] The metallization station may comprise an assembly that
automatically replenishes the metal evaporated during
metallization. The metal is typically supplied on a continuous fed
spool or as small pieces of metal that are inserted into heating
filaments within the chamber.
[0021] The in-line processing equipment may include a reel station
that reels the sheet comprising the shaped, metallized product onto
a reel or spool. The reel may then be transported (with the shaped,
metallized products still attached) to a remote site or to another
in-line processing station on-site, where the shaped, metallized
products may be unrolled and assembled onto a final product or
electronic device.
[0022] The shaped, metallized products may be an EMI/RFI shields
(e.g., single chamber shield or multi-compartmentalized shields)
that are transported to a final manufacturing station and the tabs
of material may be cut to remove the EMI/RFI shield from the sheet
and placed manually or robotically onto a printed circuit board of
an electronic device, such as a cellular phone.
[0023] The final products may be further be processed at the
cutting station (or at a second cutting station in the in-line
processing equipment) so as to remove material from desired
locations in the shaped, metallized product or from the sheet prior
to processing, so as to allow ventilation through the final
product. Alternatively, the material may be removed from the
product so as to allow items, such as flexible circuitry, cables,
connectors, heat sinks or tools, to have clearance to pass through
the product.
[0024] The in-line equipment may further comprise a second cutting
station that removes the shaped, metallized product from the sheet.
Typically, the second cutting station will be present in equipment
which manufacture and place the product onto its final product in a
single in-line process. In such embodiments, the in-line equipment
may also include a station that places the product on the final
product. For example, if the product is an EMI/RFI shield, the
station may move the shield from the sheet (e.g., cut the tabs of
material) and robotically or manually allow the shield to be placed
over an EMI/RFI source on a printed circuit board (PCB) of an
electronic device.
[0025] It should be appreciated that the stations may be positioned
in different areas of the in-line processing equipment. For
example, it may be desirable to shape the sheet prior to
metallization and cutting. In other embodiments, it may be
desirable to metallize the sheet prior to shaping and cutting the
sheet. In yet further embodiments, it may be desirable to shape and
cut the sheet prior to metallization. Any desired configuration
between the stations or even multiple stations of the same type may
be used.
[0026] The sheet for use in the in-line equipment may be a
pre-manufactured, polymer based material, such as polypropylene,
polycarbonate, ABS, PVC, PBT, or the like, that is rolled out of a
reel and fed into the stations in an in-line process. The flat
polymer-based sheet is either metallized or may contain metallized
inclusions and characteristics. For example, such sheets include
substrates that have been impregnated with metals or conductive
materials either by straight inclusion of the particles during the
sheet fabrication, or by regrinding and recycling previously
metallized substrates and re-extruding the regrind into new
thermoformable sheets that contain metallized particles.
[0027] Instead of unspooling a pre-manufactured roll of material,
in some embodiments, the in-line equipment may include a forming
station, such as an in-line extruder, that forms the polymer sheet.
The sheet may be formed from virgin polymer material or used
material, including material that may already contain metallized
particles or layers (such as carbon, ferrites, metallized glass
fibers, metallized fibers, nano-particles, or even surface
metallizations of product earlier manufactured by one of several
processes including vacuum metallization, electroplating conductive
painting or the like).
[0028] Optionally, the in-line equipment may include a graphics
station that prepares a surface of the formable sheet by applying
text or graphics. The graphics station may apply the text or
graphics via silk-screening, printing, laser printing, decal with
adhesive backings, or the like. The graphics station may apply the
text or graphics in its final form or in a form that achieves its
final desired appearance when the text or graphics are distorted
during shaping. The text or graphics may be placed on top of the
conductive layer or applied such that the text or graphics are
visible through the conductive layer.
[0029] In one specific configuration, the present invention
provides an in-line processing system that comprises a shaping
station that shapes a product shape into the formable sheet, a
metallization station that applies a conductive layer onto at least
one surface of the sheet, and a transportation assembly that is
used to transport the sheet (and product) between the stations.
[0030] In yet another specific configuration, the present invention
provides an in-line processing system that comprises a shaping
station that shapes the formable sheet, a gasketing station that
applies a gasket to the shaped product on the sheet, and a
transportation assembly that moves the formable sheet (and product)
between the stations.
[0031] In a further configuration, the present invention provides
an in-line processing system that comprises a shaping station that
shapes the formable sheet, a cutting station that removes only a
portion of material around a periphery of a product on the sheet so
as to leave the product integrally attached with the sheet, and a
transportation assembly that moves the formable sheet (and product)
between the stations.
[0032] In another aspect, the present invention provides continuous
in-line methods of processing a formable sheet. In one embodiment,
the method comprises applying at least one conductive layer to at
least one surface of the formable sheet. The formable sheet is
shaped (e.g., thermoformed) into a desired product. At least a
portion of the material around a periphery of the product so is
removed so as to leave the product on the sheet. Removing only a
portion of the material around a periphery of the product allows
the product to remain attached to the sheet while providing for
easier removal of the product from the sheet at a subsequent
processing station. Optionally, the sheet may thereafter be wound
onto a reel.
[0033] The metallization may occur before shaping of the sheet, or
the metallization may occur after the shaping of the sheet. The
cutting may occur after shaping and before applying of the
conductive layer. Alternatively, the cutting may be carried out
after shaping and after applying of the conductive layer. As can be
appreciated, any sequence of applying the conductive layer,
shaping, and cutting may be used in the methods and equipment of
the present invention.
[0034] A gasket may be applied onto at least one surface of the
product. The gasket may be an electrically conductive or
electrically insulative adhesive. The adhesive may be prefabricated
into a desired shape and may have a protective liner on its outer
surface.
[0035] The formable sheet may be manufactured by extruding a
material substrate. The material substrate may be a virgin or used
polymer based material. The polymer based material may include a
conductive layer or conductive particles (such as carbon, ferrites,
metallized glass fibers, metallized fibers and/or nano-particles,
or even surface metallization of product earlier manufactured by
one of several processes including vacuum metallization,
electroplating conductive painting or the like) such that
conductive particles will be dispersed in at least a portion of the
resultant formable sheet.
[0036] Optionally, a surface of the formable sheet may be prepared
by applying text or graphics to at least one surface of the sheet.
The text or graphics may be applied via silk-screening, printing,
laser printing, as a decal with adhesive backings, or the like. The
text or graphics may be applied in its final form or in a form that
achieves it final desired appearance when the text or graphics are
distorted during shaping. The text or graphics may be placed on top
of the metal conductive layer or applied such that the text or
graphics are visible through the conductive layer.
[0037] In addition to removing material around the periphery of the
product, material may be removed from the product at desired
locations to provide ventilation or to provide clearance for other
items to extend through the final product.
[0038] These and other aspects of the invention will become more
apparent from the following detailed description of the invention
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a top view of a thermoformed EMI/RFI shield.
[0040] FIG. 1A is a cross-sectional view of the EMI/RFI shield of
FIG. 1 along line A-A.
[0041] FIG. 2 is a cross-sectional view of an alternative EMI/RFI
shield that has a lip.
[0042] FIG. 3 is a top view of a plurality of a single compartment
EMI/RFI shields on a tape sheet.
[0043] FIG. 4 is a top view of a plurality of
multi-compartmentalized and single compartment EMI/RFI shields on a
tape sheet.
[0044] FIG. 5 is a top view of an EMI/RFI shield integrally
attached to a sheet with tabs of material.
[0045] FIG. 5A is a top view of another EMI/RFI shield integrally
attached to the sheet with tabs of material.
[0046] FIG. 5B is a perspective view of the EMI/RFI shield of FIG.
5A.
[0047] FIG. 5C illustrates an adhesive having removable liners that
may be applied with a gasketing station of the present
invention.
[0048] FIG. 5D schematically illustrates a spool comprising a sheet
of material with the EMI/RFI shields attached thereto.
[0049] FIG. 6 is a schematic illustration of one method of the
present invention.
[0050] FIG. 7 is a schematic illustration of an alternative method
of the present invention.
[0051] FIG. 8 schematically illustrates one example of a forming
station that has a first and second extruder.
[0052] FIG. 9 schematically illustrates one example of a
metallization station.
DETAILED DESCRIPTION OF THE INVENTION
[0053] While the remainder of the discussion focuses on EMI/RFI
shields and in-line processing of the EMI/RFI shield, it should be
appreciated that the equipment, methods, and products of the
present invention are not limited to EMI/RFI shields. For example,
the present invention is equally applicable to ornamental
metallized polymer products, food packaging, utensils, decorative
display pieces or the like.
[0054] FIGS. 1 and 1A illustrate one embodiment of a shaped,
metallized product that is encompassed by the present invention.
The illustrated product is in the form of an EMI/RFI shield 10 for
an electronic device, such as a cellular telephone. The EMI shield
10 is typically comprised of a shell 12 coated with at least one
substantially even layer of a conductive material 14. In the
illustrated embodiment, conductive layer 14 is along an inner
surface of shell 12 but the conductive layer 14 may be on an outer
surface of shell 12 or on at least a portion of both the inner and
outer surface of shell 12.
[0055] The illustrated example of shell 12 in FIGS. 1 and 1A is a
thermoform single compartment "can" that comprises an upper surface
16 and a plurality of sidewalls 18, 18', 18', 18'" that extend at
an angle of approximately 90 degrees from upper surface 16 to
define a chamber 20. It should be appreciated however, that the
angle between the upper surface and sidewalls may vary depending on
the use of the EMI/RFI shield. In use, a bottom edge of conductive
layer 14 along sidewalls 18, 18', 18', 18'" may be grounded so as
to create a grounded shield for an EMI source (not shown). To
improve grounding, an optional gasket 22 may be coupled to the
bottom edge of the sidewalls 18, 18',18", 18'" and conductive layer
14.
[0056] As can be appreciated, the illustrated EMI/RFI shield 10 of
FIGS. 1 and 1A are merely examples, and the EMI/RFI shield may take
on a variety of different shapes and may be composed of a variety
of materials. For example, FIG. 2 illustrates an EMI/RFI shield 10
that has a flange or lip 24 formed around the periphery of the
bottom edge of sidewalls 18, 18', 18", 18'" that extends at an
angle from the sidewalls so as to provide an enlarged surface area
for contacting another body, such as a ground trace on a printed
circuit board (not shown). Lip 24 is typically at an angle of
approximately 90 degrees from the sidewalls so that the upper
surface 16 and lip 24 are in substantially parallel planes, but the
angle may be at a larger or smaller angle, depending on the
particular application of the EMI/RFI shield. If desired, an
electrically conductive or electrically insulative gasket 22 may be
attached to an upper or lower surface of lip 24.
[0057] While not illustrated, EMI/RFI shield 10 may be dome shaped,
or may have multiple chambers 20. A more complete description of
some examples of EMI/RFI shields that may be manufactured with the
methods of the present invention are described in commonly owned
U.S. Pat. No. 5,811,050, U.S. patent Ser. No. 09/788,263, filed
Feb. 16, 2001, and U.S. patent Ser. No. 09/684,188, filed Oct. 10,
2000, the complete disclosures of which are incorporated herein by
reference.
[0058] Referring now to FIGS. 3 and 4, the present invention
further provides an EMI/RFI shield 10 that is coupled to a tape or
sheet 30. Sheet 30 may include openings 32 that are sized and
spaced to interact with a transportation assembly (not shown) so as
to allow sheet 30 to be moved through an in-line processing system.
EMI/RFI shield 10 may be coupled to sheet 30 via an adhesive, but
EMI/RFI shield 10 is preferably formed from the same material as
sheet 30 and integrally attached to sheet 30.
[0059] As shown in FIG. 3, the sheet may be sized so as to allow
only a single EMI/RFI shield 10 to be formed along the width W of
the sheet. As shown in FIG. 4, however, sheet 30 may take on a
larger width W such that a plurality of EMI/RFI shields 10 may be
formed along width W of the sheet 30. EMI/RFI shields 10 formed
along the width W of sheet 30 may have a single compartment,
multiple compartments, and/or may have different sizes and shapes
from other shields on sheet 30. For example, as shown in FIG. 4,
the collection of different sized EMI/RFI shields in each section
34 of the sheet may be a complete set of EMI/RFI shields for a
single printed circuit board or electronic device.
[0060] FIG. 5 is an enlarged top view of one EMI/RFI shield 10 in
sheet 30 that illustrates one example of an integral connection
between EMI/RFI shield 10 and the sheet 30. The cutting station may
remove a portion of material around the periphery such that
openings 40 are spaced around the edge of the EMI/RFI shield. 10.
Each individual EMI/RFI shield 10 may be held onto sheet 30 with
small tabs of material 42 along one or more edges or corners of the
EMI/RFI shield 10.
[0061] FIGS. 5A and 5B illustrate another embodiment of EMI/RFI
shield 10 integrated into sheet 30. In the illustrated embodiments,
the sheet has a width W that allows two shields to be positioned
across width W. A cutting station may remove a portion of the
material around the periphery such that openings 40 are spaced
around tabs of material 42 that are positioned along the at least
two sides of the EMI/RFI shield 10. In the illustrated embodiment,
the tabs of material 42 are positioned along opposite sides or
edges of the EMI/RFI shield 10.
[0062] The small tabs or pieces of material 42, are of a size and
shape that are sufficient to substantially hold the EMI/RFI shield
10 in place within sheet 30. The shapes of the tabs 42 are
typically kept simple and generally are square or rectangular in
nature. The width of the tabs would most likely be kept under 1
inch and most likely less than one half of an inch so that the tabs
42 could easily be manually clipped by an operator with a small
pair of cutters or scissors. Of course the tabs could be cut
automatically, further down the line of the processing equipment
with second cutting station, if desired.
[0063] The preferred number of tabs 42 per EMI/RFI shield 10
generally depends on the size of the part being manufactured.
Consequently, a long part would have more tabs than a shorter part.
The number of tabs should be sufficient to support the weight of
the shield during the various stages of transportation along the
in-line equipment so that the shield does not rotate or flex
drastically away from the horizontal plane of the web or sheet
during processing or transportation.
[0064] Some alternative features that may be incorporated into the
tab 42 design is perforations (not shown). In such cases, the tab
42 may be perforated along the edge of the tab that connects to the
flange 24 or edge of the shield 10 to the sheet 30. The
perforations would still allow enough of a mechanical connection to
support the weight of the EMI/RFI shield 10 but perforated enough
to easily separate the shield 10 from the sheet 30 by tearing the
perforated connection by hand, if necessary.
[0065] As can be appreciated, instead of integrally attaching
(e.g., forming the EMI/RFI shield from the sheet 30 and keeping the
EMI/RFI shield attached to the sheet 30 via integral tabs of
material 42) the shield 10 may be cut away from the sheet 30 and
using an adhesive, the shield 10 may be attached to the sheet. In
such embodiments, as shown in FIGS. 2 and 5C, a bottom of the
shield (e.g., bottom of flange 24 area (FIG. 2) that would contact
a PCB) may be covered with a sheet of double sided adhesive 39. An
adhesive 49 would adhere to the bottom of the plastic sheet 30 and
have a release liner 45 on the opposite/outside surface to protect
the adhesive 49, and the liner 45 would be removed prior to placing
the EMI/RFI shield onto the PCB or other area of the electronic
device. The cutting tools may be configured so that the product
could be cut all the way through the plastic sheet but would leave
the adhesive liner 45 intact so that the adhesive 49 would span
both the sheet and the part 10, holding them intact until a
secondary cutting phase fully removes the part from the sheet.
[0066] FIG. 5D illustrates a reel or spool 51 that is configured to
receive sheet 30 and the integrally attached EMI/RFI shields 10.
Spool may be transported from one processing station to another
processing station wherein the spool 51, EMI/RFI shields 10, and
sheet 30 may feed into the in-line equipment to remove the EMI/RFI
shields 10 from sheet 30 and place it onto a printed circuit board
or electronic device.
[0067] FIGS. 6 and 7 schematically illustrate two exemplary in-line
equipment and methods that are encompassed by the present
invention. While the in-line equipment and methods described herein
are preferably carried out using a transportation assembly (not
shown) to move the sheet between a plurality of individual
processing stations in a continuous, in-line processing system, it
should be appreciated that the steps described herein do not have
to be performed continuously and the steps may be carried out
non-continuously. For example, if desired, after the sheet is
processed at one or more processing stations, the sheet may be
rolled up onto a reel or spool 51 (FIG. 5D) and moved to a
station(s) in a different processing system.
[0068] Referring now to FIG. 6, at a first station 41 a sheet
material is provided. In one embodiment, a material, typically in
the form of "pellets" or recovered virgin or used material,
including material that may already contain metallized particles or
layers (such as carbon, ferrites, metallized glass fibers,
metallized fibers and nano-particles), may be reground and extruded
into a film sheet of a desired size and width. In other
embodiments, a pre-manufactured extruded sheet may be unspooled and
fed into the in-line equipment.
[0069] The material used in the formable sheet may be PVC, ABS,
polyester, polypropylene, polycarbonate, PBT (Polybutylene
Terephthalate) or any other formable polymer-based material. The
extruded, formable sheet 30 (FIGS. 3 and 4) typically has a width
between approximately 1 inch and approximately 8 inches, but it may
be larger, such as up to approximately 30 inches or approximately
35 inches. Sheet 30 may have a thickness between approximately
0.005" inches and approximately 0.040" inches, but may be larger or
smaller as desired. As can be appreciated, the present invention
may use any sheet of any width and thickness, and the present
invention should not be limited to the recited widths and
thicknesses.
[0070] Thereafter, the continuous sheet 30 may be directed to a
shaping station 44 with a transportation assembly where the sheet
is shaped to form a desired shape for the product, such as shell 12
(FIGS. 1 and 2). Optionally, the shaping station may have a
pre-heat stage (not shown) so as to bring the continuous sheet 30
up to a predetermined or recommended processing temperature
suitable for forming the plastic sheet 30. Typically, the product
is formed by thermoforming, but it may also be formed by pressure
forming, or the like. As is known in the art, the thermoforming
process generally provides a flat plastic sheet that is heated to a
processing temperature and brought into contact with a forming
mold. The air is subsequently evacuated from underneath the vacuum
mold which forces the sheet against the mold by vacuum pressure
from below and atmospheric pressure from above. Because the sheet
is softened enough it will conform to the dimensions of the
mold.
[0071] Once thermoformed (or otherwise shaped), the sheet and
shaped product are optionally moved onto a cutting station 46,
where the sheet and product may be subjected to a first die cut
operation where the major elements of the product are partially
separated from the remaining sheet material (scrim). For example, a
number of small "tabs" of material may be left between the sheet 30
and the shell 12 which act to keep the shell 12 attached to the
sheet material 30.
[0072] After the product is die cut, the shaped product (which is
still attached to the sheet 30) is moved to a metallization station
47 where a conductive layer is applied to the shaped product. The
conductive layer may be applied through any one of numerous
methods, including but not limited to, vacuum metallization,
printing with conductive ink, electroplating, electroless plating,
conductive painting, or the like. Vacuum metallization is one
preferred method due to uniformity of deposition along the edges
and surfaces of the sheet. The conductive layer may comprise
aluminum, nickel, tin, copper, silver, zinc, or any other
conductive material, including conductive paint, electroplated tin,
zinc or the like.
[0073] While not explicitly illustrated, the metallization station
47 may include a plurality of individual metallization stations for
applying one or more conductive layers onto one or more surfaces of
the sheet. For example, a first metallization station may apply a
first conductive layer, such as nickel. Thereafter, the metallized
sheet may be moved to a second metallization station where a second
conductive layer, such as tin or nickel, is added. As can be
appreciated, additional conductive or non-conductive layers may be
disposed between the first and second conductive layers, if
desired.
[0074] The first and second metallization stations may or may not
utilize the same type of deposition assemblies. For example, the
first metallization station may use vacuum deposition, while the
second metallization station may use electroplating. As can be
appreciated, any number of metallization stations and any
combination of metallization technologies may be used in the
metallization stations of the present invention.
[0075] After metallization, the metallized, shaped shell may
optionally be moved to a gasketing station 48 where an electrically
conductive or electrically insulated adhesive can be added to the
metallized, shaped product in selected areas to create a
ready-to-assemble product, such as an EMI/RFI shield 10. The
equipment used to apply the gasket can take several forms. For
example, one gasket material type used is the double sided
(conductive or non-conductive) tape adhesive 43 illustrated in FIG.
5C. The types of adhesives would generally have the adhesive
material 49 sandwiched between two different release liners 45 and
be applied in a similar style to laminating where one of the
release liners would be removed exposing the adhesive 49. The
adhesive 49 could then be unspooled from a roll and applied to the
plastic sheet 30 as the sheet is being transferred from station to
station. The remaining release liner would remain intact to protect
the adhesive 49 until it is removed, most likely during final
assembly.
[0076] In most cases, the width of the adhesive 49 would only be
wide enough to completely cover the width of the part or parts in
the sheet to reduce the amount of waste generated, but if desired
the adhesive could have a width that is substantially equal to the
width of the sheet. In other cases, it may be desirable to have the
adhesive 49 precut to a specific shape so that the adhesive will
align with the different edges or flanges of the shield that will
be making contact with the PCB, such as in the case of a
compartmentalized shield. The adhesive could still be applied in a
laminating style in this case, however, adhesive would only be
applied to select areas of the plastic and not across the width of
the part.
[0077] Alternatively, gasketing station 48 may dispense a liquid
conductive or non-conductive adhesive. Dispensable adhesives are
generally contained in a syringe type applicator and droplets or
continuous beads of adhesive are able to be placed either manually
or robotically in select locations of the sheet. The syringes are
typically pneumatically controlled so that a consistent sized
droplet or bead is place every time. Most adhesives of this type
require some length of cure time either at ambient or elevated
temperatures. These types of adhesives are generally less expensive
because there is very little waste, if any.
[0078] After the optional gasketing station, the sheet 30 with the
attached products may be wound-up on spool or reel at a spooling
station 50 for shipment to a manufacturer for final assembly. Once
unspooled, automated machines may remove the remove the metallized,
shaped product after the final die cut and apply the products onto
its final form. For EMI/RFI shields, the EMI/RFI shield may be
removed from the sheet and placed onto a printed circuit board
(PCB) in an appropriate location.
[0079] After the spooling station 50 or instead of going to the
spooling station, the sheet may be moved to a second cutting
station 52 where the cutting station may remove the products from
the sheet (e.g., cut through tabs 42) and apply the shaped,
metallized product in its appropriate location, such as a printed
circuit board of an electronic device.
[0080] FIG. 7 illustrates an alternative configuration for the
in-line equipment and associated methods. In the alternative
configuration, instead of first thermoforming (or otherwise
shaping) the sheet, one or more conductive layers may first be
applied to the sheet at a metallization station 47. Thereafter, the
metallized sheet may be moved to a shaping station 44 wherein the
product shape is formed in the metallized sheet. The metallized,
shaped product may then be moved to the cutting station 46 where a
portion of the material around a periphery of the metallized,
shaped product is removed, such that the shaped, metallized product
is still retained on the sheet. Finally, the sheet and metallized,
shaped product may be moved to a cutting station 52 to remove the
product from the sheet or the sheet may be moved to a spooling
station 50 where the sheet and metallized, shaped product is wound
up on a spool.
[0081] Similar to the embodiment of FIG. 6, a gasket may optionally
be applied to the metallized, shaped product at a gasketing station
48. Thereafter, the sheet and metallized, shaped product (with
gasket) may be moved to a spooling station 50, where the sheet and
metallized, shaped product is wound up on a spool. Alternatively,
the sheet 30 may be moved to a second cutting station 52 to remove
the EMI/RFI shields 10 from the sheet.
[0082] As can be appreciated, the methods and in-line equipment of
FIGS. 6 and 7 are merely examples and various modifications can be
made without departing from the essence of the present invention.
For example, other processing stations may be interspersed between
the recited stations. Other stations include, but are not limited
to, printing or decoration stations for applying information or
logos, ultrasonic welding stations for inserting threaded features
for receiving screws or for inserting grommet features to be used
as grounding eyelets where screws, rivets, or the like can be
inserted to make an electrical connection between the shield and
the PCB or chassis the shield is being inserted into or attached.
Moreover, other configurations of the stations may be used. For
example, in further embodiments, it may be desirable to shape the
sheet, apply the one or more conductive layers to the sheet, and
thereafter remove a portion of material around the periphery of the
shaped, metallized product. In yet other embodiments, it may be
desirable to not remove material from around the periphery of the
EMI/RFI shield, and only remove material from around the EMI/RFI
shield at the final step before placing the EMI/RFI shield.
EXAMPLES OF PROCESSING STATIONS
[0083] FIGS. 8 to 9 schematically illustrate some examples of some
processing stations that may be used with the present invention. It
should be appreciated that the following description are merely
examples, and various other conventional and proprietary technology
may be used without departing from the scope of the present
invention.
[0084] FIG. 8 illustrates an exemplary extruder station that may be
used to extrude a material substrate into the sheet 30. A first
extruder 60 has the ability to accept nominal room temperature
material and then heat the material to the point of melting before
injecting the material onto a platen for spreading into the film
sheet. In the present invention, the width of the platen (that
determines the width of the formed sheet) is typically on the order
of approximately 1 inch to approximately 8 inches, but may be
larger or smaller if desired. Extruder 60 would be capable of
accepting material that contained previously metallized film. This
would allow for recycling of EMI shield products previously used in
an electronic product.
[0085] As shown in FIG. 8, the station may include a second,
stacked extruder 62 that would allow for two film substrates to be
produced in an adjacent (e.g., vertical) conjunction with each
other. The first and second extruders 60, 62 would create sheets
30, 30' separate from each other until after a metallization layer
is applied to one or both interior or exterior surfaces of the
sheet. The sheets may then be brought together to form a layered
EMI shield product. For example, with a first and second film 30,
30', flexible circuitry could be inserted and encapsulated into a
single integrated part, using an insertion station (not shown).
[0086] FIG. 9 illustrates one example of a metallization station
that applies a metal layer onto at least one surface of the sheet
and/or shaped product in a moveable vacuum chamber. As noted above,
however, metallization can take place by several methods and the
present invention is not limited to vacuum metallization. Vacuum
metallization equipment would comprise a small vacuum chamber 70
that would contain various internal chambers so a metal material
could be accepted, metallized, and discharged via one end. The
construction of the vacuum chamber is typically such as to allow
the continuous processing of the sheet 30 and/or EMI/RFI shield
product 10. The vacuum chamber 70 could be located on the same
plane as the other in-line processing stations, or it could be
placed on another plane, if desired. Such a chamber, include ports
72, 74 for entry and exit of the sheet 30 into the vacuum chamber
70. The ports are designed to open and close so as to create a
pneumatic seal (sufficient for creating a vacuum). In a typical
application, tungsten (or similar material) filaments 76 with an
embedded cane material 78 (such as aluminum) would be inserted into
the vacuum chamber 70. One vacuum port 80 could support each single
chamber and multiple ports could be used to insert new
filaments/canes for the metallization process. Additional ports 82,
84 could be used to insert gases (like Nitrogen) in order to
perform a "glow discharge" process step just prior to
metallization. Typically metallization station will use a smaller
pressure containment vessel that could be evacuated to low
pressures (.about.10.sup.-6 torr.) in a very short period of time
(<3 sec.)
[0087] While particular forms of the invention have been
illustrated and described, it will be apparent that various
modifications can be made without departing from the spirit and
scope of the invention.
* * * * *