U.S. patent application number 10/863716 was filed with the patent office on 2004-11-25 for multi-layered structures and methods for manufacturing the multi-layered structures.
This patent application is currently assigned to Wavezero, Inc.. Invention is credited to Arnold, Rocky R., Toyama, Steve, Zarganis, John.
Application Number | 20040234752 10/863716 |
Document ID | / |
Family ID | 22876542 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040234752 |
Kind Code |
A1 |
Arnold, Rocky R. ; et
al. |
November 25, 2004 |
Multi-layered structures and methods for manufacturing the
multi-layered structures
Abstract
Multi-layered molds and methods for manufacturing multi-layered
molds. A metallized layer can be deposited on at least one side of
a substrate. The substrate can be shaped and then the metal layer
can be deposited onto the shaped substrate. Optionally, an
injection molded resin can be deposited onto the substrate and/or
metal layer.
Inventors: |
Arnold, Rocky R.; (San
Carlos, CA) ; Zarganis, John; (Redwood, CA) ;
Toyama, Steve; (Livermore, 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: |
22876542 |
Appl. No.: |
10/863716 |
Filed: |
June 7, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10863716 |
Jun 7, 2004 |
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09947229 |
Sep 4, 2001 |
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6768654 |
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60233259 |
Sep 18, 2000 |
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Current U.S.
Class: |
428/336 ;
428/457; 428/458 |
Current CPC
Class: |
H05K 3/341 20130101;
H05K 9/003 20130101; Y10T 428/31681 20150401; Y10T 428/265
20150115; B29C 45/14811 20130101; Y10T 428/24479 20150115; H05K
5/0243 20130101; H05K 9/0084 20130101; B29K 2995/0011 20130101;
B29L 2009/008 20130101; Y10T 428/24802 20150115; B29K 2995/002
20130101; H05K 9/0088 20130101; Y10T 428/31678 20150401 |
Class at
Publication: |
428/336 ;
428/457; 428/458 |
International
Class: |
B32B 015/04 |
Claims
What is claimed is:
1. A method of forming a multi-layered laminate for use in an
in-mold process, the method comprising: shaping the substrate into
a desired shape; applying a decorative feature to at least one
surface of a substrate; and depositing a metal layer onto at least
one surface of the decorated and shaped substrate.
2. The method of claim 1 wherein the metal layer has a sufficient
thickness to shield electromagnetic interference.
3. The method of claim 1 wherein the metal layer has a thickness
between approximately 1 micron and 50 microns.
4. The method of claim 1 wherein shaping comprises thermoforming
the substrate.
5. The method of claim 1 wherein applying comprises using printable
masks, silk screening, heat transfer molding, sublimation
ink-transfer, or pad printing.
6. The method of claim 1 further comprising injection molding a
resin onto at least one of the decorative feature, metal layer, and
substrate.
7. The method of claim 1 wherein shaping comprises placing the
substrate over a vacuum mold.
8. The method of claim 1 wherein applying is carried out after
shaping.
9. The method of claim 1 wherein applying is carried out before
shaping.
10. The method of claim 1 wherein applying comprises decorating
both a first surface and a second surface of the substrate.
11. The method of claim 1 wherein applying comprises decorating
only a first surface of the substrate.
12. The method of claim 1 wherein depositing comprises vacuum
metallizing the metal layer onto the substrate.
13. The method of claim 11 wherein depositing comprises painting,
sputtering, electroplating, deposition coating, electroless
plating, laminated conductive layers the metal layer onto the
substrate.
14. The method of claim 1 wherein the metal layer provides a
reflective surface.
15. A method of forming a multi-layered structure, the method
comprising: placing a pre-shaped metallized insert into an
injection molding chamber; and injection molding a resin on the
metallized insert.
16. The method of claim 15 wherein the metallized substrate
comprises a film and at least one metal layer, wherein the at least
one metal layer is sufficient to block electromagnetic
interference.
17. The method of claim 15 wherein the metallized substrate
comprises a film and at least one metal layer, wherein the at least
one metal layer with a thickness between approximately 1 micron and
50 microns.
18. The method of claim 15 wherein providing comprises: shaping the
substrate; and depositing a metal layer onto at least one surface
of the shaped substrate to form the metallized substrate.
19. The method of claim 18 wherein depositing comprises vacuum
metallizing the metal layer onto the shaped substrate.
20. The method of claim 18 wherein depositing comprises painting
the metal layer onto the shaped substrate.
21. The method of claim 18 comprising applying at least one layer
of decoration onto the substrate prior to shaping of the
substrate.
22. The method of claim 15 wherein the metallized substrate further
comprises at least one layer of decoration.
23. The method of claim 15 wherein the metallized substrate
comprises a film and a metal layer, wherein injection molding
comprises bonding the resin to the metal layer.
24. The method of claim 23 comprising depositing an undercoat over
the metal layer prior to bonding the resin to the metal layer.
25. The method of claim 15 wherein the metallized substrate
comprises a film and a metal layer, wherein injection molding
comprises bonding the resin with the film.
26. The method of claim 25 comprising depositing a topcoat over the
metal layer.
27. The method of claim 26 wherein the topcoat comprises
urethane.
28. The method of claim 15 wherein the metallized substrate
comprises a shaped thermoform and a metal layer.
29. The method of claim 15 wherein the resin is clear or black.
30. The method of claim 15 wherein the metallized substrate creates
a reflective surface.
31. The method of claim 15 wherein the metallized substrate is
colored.
32. The method of claim 15 wherein the metallized substrate
comprises a non-conductive film and a conductive metal layer.
33. A method of forming a multi-layered structure, the method
comprising: shaping a substrate into a desired shape; depositing a
metal layer onto at least one surface of the shaped substrate.
placing a metallized substrate into an injection molding chamber;
and injection molding a resin on the metallized substrate.
34. The method of claim 33 wherein shaping comprises thermoforming
the substrate.
35. The method of claim 33 wherein depositing comprises vacuum
metallizing the metal layer onto the shaped substrate.
36. The method of claim 33 wherein injection molding comprises
bonding the resin to the metal layer.
37. The method of claim 33 wherein injection molding comprises
bonding the resin to the shaped substrate.
38. The method of claim 33 further comprising applying a decorative
feature to at least one of the substrate and metal layer.
39. The method of claim 33 comprising applying one of an undercoat
and an overcoat to the metal layer.
40. A method of forming a multi-layered structure, the method
comprising: applying a decorative layer to at least one side of a
substrate; shaping the decorated substrate into a desired shape;
depositing a metal layer onto at least one surface of the decorated
and shaped substrate. placing a metallized substrate into an
injection molding chamber; and injection molding a resin on the
metallized substrate.
41. A multi-layered insert for an in-mold manufacturing process,
the insert comprising: a shaped substrate comprising a decorative
feature along at least one surface; and a metallized layer disposed
over at least one of the substrate surface and the decorative
feature.
42. The insert of claim 41 wherein the substrate comprises a
thermoform.
43. The insert of claim 41 wherein the metallized layer comprises a
vacuum metallized layer.
44. The insert of claim 41 wherein the metallized layer is bonded
to the substrate after shaping of the substrate.
45. The insert of claim 41 wherein the metallized layer has a
thickness that is sufficient to block electromagnetic
interference.
46. The insert of claim 41 wherein the metallized layer has a
thickness between approximately 1 micron and 50 microns.
47. The insert of claim 41 wherein the substrate comprises a first
surface and a second surface, wherein the metallized layer is
disposed on both the first surface and the second surface.
48. The insert of claim 41 wherein the decorative feature is
disposed only on a first surface and the metallized layer is
disposed on a second surface.
49. The insert of claim 48 wherein a second metallized layer is
disposed on the decorative feature.
50. The insert of claim 41 wherein the metallized layer provides a
reflective surface.
51. A multi-layered laminate comprising: a pre-shaped film; a metal
layer coupled to the pre-shaped film, the metal layer having a
thickness sufficient to shield electromagnetic interference; and an
injection molded plastic structure coupled to at least one of the
pre-shaped film and metal layer.
52. The mold of claim 51 comprising at least one decoration layer
coupled to at least one of the pre-shaped film and the metal
layer.
53. The mold of claim 51 wherein the pre-shaped film comprises a
first surface and a second surface, wherein the metal layer is
coupled to the first surface, wherein the laminate further
comprises a second metal layer coupled to the second surface of the
pre-shaped film.
54. The mold of claim 51 wherein the metal layer has a thickness
between approximately 1 microns and 50 microns.
55. The mold of claim 51 wherein the injection molded plastic is
directly coupled to the metal layer.
56. The mold of claim 51 wherein the injection molded plastic is
coupled to the metal layer with an undercoat.
57. The mold of claim 51 wherein the injection molded plastic is
coupled to the pre-shaped film.
58. The mold of claim 51 wherein the pre-shaped film comprises a
thermoform.
59. A shielded plastic housing for an electronic component, the
housing comprising: an injection molded layer; a thermoform layer
comprising a metal layer that has a thickness sufficient to block
transmission of electromagnetic interference, wherein one of the
metal layer and thermoform layer is coupled to the injection molded
layer; and a decorative layer coupled to one of the injection
molded layer, the thermoform layer and the metal layer.
60. The housing of claim 59 wherein the metal layer is viewable
through the injection molded layer.
61. The housing of claim 59 wherein the metal layer provides a
reflective surface.
62. An electronic device comprising: a plastic housing comprising:
an injection molded layer; a thermoform layer comprising a metal
layer that has a thickness sufficient to block transmission of
electromagnetic interference, wherein one of the metal layer and
thermoform layer is coupled to the injection molded layer; and a
printed circuit board disposed within the plastic housing.
63. The device of claim 62 wherein the metal layer has a grounding
element to establish an electrical contact to a ground on the
printed circuit board.
64. The device of claim 62 wherein the plastic housing comprises a
decorative layer coupled to at least one of the injection molded
layer, thermoform and metal layer.
65. The device of claim 62 wherein the injection molded layer is
clear or colored and the metal layer is viewable through the
injection molded layer.
66. The device of claim 65 wherein the metal layer provides a
reflective surface.
67. The device of claim 62 wherein the injection molded layer is
substantially clear, wherein the device further comprises a
decorative feature that is viewable through the injection molded
layer.
68. A method of shielding an electronic component of a printed
circuit board, the method comprising: providing a printed circuit
board having an electronic component and a ground trace; placing an
electronic housing around the electronic component; conforming a
polymer insert comprising a metal shielding layer to the electronic
housing; and grounding the metal shielding layer of the polymer
insert with the ground trace on the printed circuit board.
69. The method of claim 68 wherein the housing comprises ribs,
wherein grounding comprises contacting a portion of the metal layer
of the polymer insert ribs that conforms with the ribs with the
ground trace on the printed circuit board.
70. The method of claim 68 wherein providing comprises vacuum
metallizing the metal shielding layer onto a polymer insert.
71. The method of claim 68 wherein grounding comprises depositing a
conductive adhesive or solder between the metal layer and ground
trace.
72. The method of claim 68 wherein grounding comprises laser
heating or ultrasonic welding the metal layer to the ground
trace.
73. A method of shielding an electronic component of a printed
circuit board, the method comprising: providing a printed circuit
board having an electronic component and a ground trace; placing a
housing comprising a metal shielding layer around the electronic
component; and creating a via through a portion of the housing;
positioning the via over the ground trace; and depositing at least
one of a conductive adhesive and a solder in the via to
conductively ground the metal layer in the housing to the ground
trace.
74. The method of claim 73 wherein the housing is an outer housing
of an electronic device.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application claims benefit to U.S. Provisional
Patent Application Ser. No. 60/233,259, filed Sep. 18, 2000, the
complete disclosure of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to multi-layered
structures or laminates and methods for manufacturing the
multi-layered structures. In particular, the present invention
relates to multi-layered structures having a shielding layer for
blocking transmission of electromagnetic interference.
[0003] All electronic products emit electromagnetic radiation,
generally in the range of 50 MHz to 1 GHz, but not limited to this
range, especially considering the recent advances in high-speed
microprocessor design and the rapidly increasing capabilities of
high-speed networking and switching. The problem of emittance of
electromagnetic radiation is not new to designers of electronic
equipment; indeed, significant efforts are taken to reduce
electromagnetic interference, electrostatic discharge,
radiofrequency interference (hereinafter referred to collectively
as "EMI") and virtually every county has a regulating agency (FCC
in the U.S., for instance) that restricts the marketing and sale of
electronic equipment that do not pass stringent requirements for
EMI, whether radiation or intercepted (also called susceptibility)
by an electronic device.
[0004] Present day solutions for EMI shielding generally include
the use of conductively painted plastic housings, conductive
gaskets, and metal cans that are affixed to the printed circuit
board by soldering or similar methods, some of which are
semi-permanent. In virtually all cases, however, the existing
solutions are expensive and add to the cost of providing electronic
equipment such as cell phones, personal digital assistants, laptop
computers, set-top boxes, cable modems, networking equipment
including switches, bridges, and cross-connects.
[0005] In an effort to bring costs down while increasing shielding,
various technologies for the metallization of polymer substrates
has been developed. For example, U.S. Pat. No. 5,028,490 to
Koskenmaki describes layering a polymer substrate with aluminum
fibers and sintered to form a flat material with a metal coating
that is intended to provide effective EMI control (also called
electromagnetic control or EMC). In actual use, however, the
material has been shown to be expensive, difficult to use, and
subject to inferior performance due to cracking of the metallized
layer. Unfortunately, the metal-layered material has not been able
to withstand a thermoformed process due to the typical tight radius
used in the thermoforming molds.
[0006] U.S. Pat. No. 5,811,050 to Gabower, the complete disclosure
of which is incorporated herein by reference, has provided an
alternative approach wherein the thermoformable substrate (any
number of polymers) is first formed and then metallized. This
approach offers the advantage of eliminating the stresses to
metallized layer created during molding. The product has been shown
to be highly effective and relatively low-cost.
[0007] Plastic housings, because they are not conductive, provide
no shielding of electromagnetic radiation. Attempts to provide
plastic with a conductive feature include intrinsically conductive
plastics and plastics loaded with conductive fillers (carbon or
nickel flakes, for instance). Generally, these plastics are
prohibitively expensive, or at least not economically feasible
given alternative technologies (cans, gaskets, and conductive
painting). Additionally, the level of shielding effectiveness is
also small, typically less than 40 dB, whereas the demands of many
computing devices, both mobile and fixed, require shielding
effectiveness greater than 40 dB.
[0008] Historically, metals have been used for housings of fixed
location equipment and electronic devices. Fixed electronics, such
as personal computers, printers, fax machines, etc. are typically
contained in metal housings or, if plastic housings are used, the
printed circuit boards (PCBs) are shielded in some manner (cans,
for instance on selected high-emission components and traces).
Mobile devices often used plastic housings and some combination of
conductive gaskets, metal cans, and conductive painting of the
housing to achieve the desired shielding effectiveness. As the
frequency of emissions increases as a result of smaller components,
circuits, and the closer locating of analog/digital circuits, the
need for shielding increases and the need for greater shielding
effectiveness also increases. The drive to create smaller, lighter
mobile products also creates a need for lighter and thinner
shielding solutions.
[0009] Recently, the use of in-mold and insert-mold plastic molding
processes have become of great interest to the electronics
packaging industry. With in-mold processes, a relatively thin
material is drawn into or placed into a plastic injection mold and
used as a "dam" or backstop for the injection plastic material that
typically becomes the structural housing. Such processes provide
some interesting design features for a variety of products.
[0010] While the in-mold processes have been effective in creating
decorative housings, the current in-mold processes, however, do
nothing to solve the difficult issue of EMI shielding.
BRIEF SUMMARY OF THE INVENTION
[0011] The present-invention provides multi-layered inserts,
laminates, housings, and electronic devices that have a metal layer
that provides improved decorative features and/or EMI
shielding.
[0012] In exemplary uses, the multi-layered structures of the
present invention can be used to create housings and electronic
devices that have an EMI shield integrated with the housing. The
housings of the present invention can provide shielding of greater
than 40 dB for radiation in the range of 50 MHz to 1 GHz, or more.
In addition to providing EMI shielding, the metal layers of the
present invention can also provide a decorative layer, such as a
"metallic look" or a reflective surface. The integrated
plastic/shielding housing can be used for both fixed and mobile
electronic products.
[0013] In general, the electronic devices of the present invention
include a housing having film layer, at least one metal layer
having a thickness that is sufficient to block the transmission of
EMI, and a resin layer. The electronic devices typically include a
printed circuit board disposed within the shielded housing in which
the EMI shield layer is grounded.
[0014] The film layers incorporated into the structures of the
present invention will typically be shaped to a desired form prior
to the deposition of the resin onto the film. In exemplary
embodiments, the film layer is a thermoform that is shaped using
conventional thermoforming techniques (e.g., vacuum, pressure, or
mechanical forces). It should be appreciated however, that the film
layer can be shaped using any conventional or proprietary
methods.
[0015] The metal layers of the present invention are also typically
attached to the film layer after shaping of the film layer. If the
metal layer is applied prior to shaping of the film layer, the
shaping process (e.g., thermoforming) tends to stretch out and
weaken portions of the metal layer. Such stretching and thinning
has been found to weaken and sometimes destroy the EMI capabilities
of the metal layer. The EMI shields Of the present invention will
generally have a substantially even thickness that is sufficient to
block the passage of EMI. Typically, the metal layer will have a
thickness between approximately 1 microns and 50 microns. In such
embodiments, the metal layer will typically be grounded so as to
create a Faraday cage.
[0016] Typically, the metal film layer is deposited onto the film
layer using vacuum metallization. Vacuum metallization is one
preferred method because of the substantially even layer of metal
that can be applied to the shaped film to create the EMI shield. It
should be appreciated however, that other methods of depositing the
metal layer to the substrate can be used without departing from the
scope of the present invention. For example, instead of vacuum
metallization, other methods such as a depositing a random mat or
fiber weave, sputtering, painting, electroplating, deposition
coating, electroless plating, laminated conductive layers, or the
like, can be used to deposit the metal layer onto the multi-layered
laminate.
[0017] It should be appreciated that, in addition to EMI shielding,
the metal layers of the present invention can be also used for
decorative purposes or reflective purposes. Such metal layers are
typically composed of materials such as aluminum and its alloys,
copper and its alloys, tin and its alloys, silver and its alloys,
nickel and its alloys, or the like. Additionally, instead of a
single layer, it is possible to apply two or more layers using the
same or different materials. For example, in some embodiments it
may be possible to apply a nickel layer and a tin layer over the
polymer film layer. In one preferred embodiment, an aluminum metal
layer created by vacuum metallization has a luster and reflective
properties similar to that of chrome. Such a metal layer is
beneficial, particularly when the metal layer is used as a
reflector.
[0018] Depending on the combination of materials and the sequence
of deposition, the multi-layered structure may need a protective
undercoat to improve adhesion between layers or an overcoat to
protect the top layer of the laminate. Thus, as used herein,
"coupling two layers" or "attaching two layers" are meant to
encompass both directly and indirectly (e.g., another layer in
between the two layers) bonding the two layers together.
[0019] The present further includes shielded/decorated inserts for
an in-mold and insert-mold processes. Multi-layered inserts of the
present invention for the in-mold manufacturing process includes a
shaped substrate (such as a thermoform) having a decorative feature
disposed along at least one surface. A metallized layer can be
disposed over at least one of the substrate and decorative
feature.
[0020] Methods of in-mold and insert mold shielding of the present
invention include forming a multi-layered laminate for use in an
in-mold process. A decorative feature can be applied to at least
one surface of a substrate. The decorated substrate is then shaped
into a desired shape. A metal layer is then deposited onto at least
one surface of the decorated and shaped substrate.
[0021] After the multi-layered insert is manufactured (either
locally or remotely), the shaped metallized substrate can be
manually or robotically placed into an injection molding chamber
and an injection molding resin can be deposited on the metallized
substrate. The resulting multi-layered laminate from the in mold
process provides a pre-shaped film having a metal layer coupled
thereto, and an injection molded plastic structured coupled to
either the film or the metal layer.
[0022] In exemplary embodiments, the metal layer coupled to the
substrate has a thickness that is sufficient to act as an EMI
shield. Thus, if the shaped substrate is formed into a housing for
an electronic device, the electronic device will have a conformal
EMI shield integrated into its housing. Optionally, the
multi-layered structure can include a second metal layer. The
second metal layer can be decorative in nature or for aesthetic
purposes.
[0023] One or both of the first and second metal layer can be used
to create a bright, reflective, and shiny surface to provide a
design element. With the second metal layer containing a decorative
image on a first side of the substrate and EMI shielding on a
second side of the substrate, a highly effective and aesthetically
designed electronics product can be produced.
[0024] In another aspect, the present invention provides structures
and methods for grounding a metallized layer, such as a shielded
electronic housing with a ground trace of a printed circuit board.
In exemplary embodiments, the grounding methods comprises placing a
solder paste over ribbed portions of the electronic housing to
mechanically and conductively contact the ground traces on the
printed circuit board. In another exemplary embodiment, the present
invention creates a via or perforation in the electronic shield and
deposit a conductive adhesive or molten solder to create a
mechanical and conductive bond between the metal layer on the
shield and the ground trace. Other methods include soldering,
ultrasonic welding, conductive adhesives, laser melting, and the
like.
[0025] A further understanding of the nature and advantages of the
invention will become apparent by reference to the remaining
portions of the specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1 to 10 are simplified cross sectional views of a
multi-layered structure incorporating the present invention;
[0027] FIG. 11 illustrates an exemplary electronic housing
incorporating the present invention;
[0028] FIG. 12 illustrates a simplified light housing incorporating
the present invention;
[0029] FIGS. 13 to 15 illustrates an exemplary method of shaping
and metallizing a film;
[0030] FIGS. 16 to 18 illustrate an exemplary method of injection
molding the shaped, metallized film of FIG. 13;
[0031] FIGS. 19A and 19B illustrate a thin electronic package
disposed within the multi-layered structure of the present
invention; and
[0032] FIGS. 20 to 22 illustrates various methods of grounding an
electronic housing with a ground trace of the printed circuit
board.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The methods and devices of the present invention provide
improved multi-layered structures that provide improved decorative
features and/or an EMI shield. The multi-layered structures or
laminates of the present invention provide a laminate having a film
layer, a metal layer, and a resin layer to create the multi-layered
laminate. In exemplary embodiments, the structures and methods of
the present invention can be used to create a conformal EMI shield
that can fit integrally with a shaped outer housing of an
electronic device.
[0034] The multi-layered structures or laminates of the present
invention can take a variety of forms. Generally, the multi-layered
laminate includes a film, a metal layer, and a resin layer. It
should be appreciated that for ease of reference, the multi-layered
structures of the present invention are shown as being planar for
illustration purposes only. The multi-layered structures of the
present invention can take any variety of symmetrical or
non-symmetrical three-dimensional forms to create housings for a
variety of electronics, reflectors, microwave components, wireless
product, personal computers, external CD-ROM drives, or the like.
For example, the multi-layered laminate can be designed to fit the
form factor of fixed personal computers or printers in which the
housing would be on the order of several feet in any direction.
Alternatively, the multi-layered laminate could be designed to fit
a form factor for mobile products in which case the housing would
be on the order of several inches in any direction.
[0035] FIGS. 1 and 2 illustrate a portion of exemplary
multi-layered structures 10 of the present invention. Multi-layered
structure 10 includes a metal layer 12 disposed on a film 14 (to
create a metallized film 15) and a resin 16 coupled to either the
film 14 or metal layer 12. As illustrated in FIG. 1, film 14 can be
disposed between resin 16 and metal layer 12. Alternatively, as
shown in FIG. 2, the metal layer 12 can be disposed between film 14
and resin 16.
[0036] In other embodiments, as shown in FIG. 3, multi-layered
structure 10 can include metal layers 12, 12' along both surfaces
of film 14. The two metal layers have been found to improve
shielding efficiency, and increase available conductive surface
area to be used for grounding connection points.
[0037] If metal layer 12 is exposed, as shown in FIG. 3, it may be
desirable to place an elastomer topcoat layer 18, such as a
urethane, or the like, over at least a portion of metal layer 12 so
as to protect metal layer 12. If metal layer 12 is an EMI shield,
topcoat layer 18 can help maintain the metal layer's electrical
conductivity while preventing scratches, electrical breaks, and the
like. If metal layer 12 is a decorative or reflective layer,
topcoat layer 18 can maintain the metal layer's luster and/or
prevent metal layer from wearing out.
[0038] Alternatively, as shown in FIG. 4, if metal layer 12 is
sandwiched between film 14 and resin 16, to protect metal layer 12
during manufacturing, an elastomer undercoat, a micro-cellular
foams, or the like, can be used to create a barrier between the
molten resin during the injection molding process.
[0039] In the embodiment of FIG. 5 an undercoat 19 can be applied
between the metal layer 12 and resin 16 so as to protect metal
layer 12 during the heat generated during the injection molded
process. The undercoat can improve the bonding characteristics
between resin layer 16 and metal layer 12.
[0040] Metal layer 12 of the present invention can serve a variety
of purposes. In the embodiments illustrated in FIGS. 1 to 5, metal
layer 12 can either be a decorative layer, an functional, or both.
If the metal layer is functional, such as acting as an
electromagnetic interference, electrostatic discharge,
radiofrequency interference, and/or increases the available
conductive surface are to be used for grounding connection points.
If metal layer 12 is an EMI shield, the metal layer will generally
have a thickness between approximately 1 micron and 50 microns, so
as to be able to provide shielding effectiveness greater than
approximately 40 dB and to block the passage of electromagnetic
radiation between the range of 50 MHz to 1 GHz, or more.
[0041] In embodiments where metal layer 12 is used purely for
decorative purposes, metal layer need not be conductive and metal
layer 12 can have a smaller thickness, than the above cited ranges.
Moreover, the decorative layer will oftentimes be applied only to a
portion of film 14. Optionally, metal layer 12 can be colored so as
to provide a better decorative effect.
[0042] In exemplary embodiments, metal layer 12 can be deposited
onto film layer 14 such that the metal layer acts as a decorative,
reflective surface. In such cases, the multi-layered structure 10
can be used as reflectors for automotive vehicles (e.g., cars,
planes, etc), as an external housing for electronic equipment,
badges, nameplates, or the like. One advantage of such a
configuration is that the metal layer can be viewed through a
protective layer, such as clear or colored resin 16 or overcoat 18.
Unlike conventional printing methods, which often place the
decorative features on an external, exposed surface, by placing the
metal layer behind a protective layer, the luster and decorative
features of the metal layer can be maintained for a longer period
of time. Additionally, if metal layer 14 is formed in the shape of
letters (such as a warning or instructions), the decorative
features can be protected from delamination, abrasion, and wear,
and a user will be prevented from rubbing such letters off.
[0043] Metal layer 12 can be deposited into multi-layered mold
through a variety of methods. In exemplary methods, the metal layer
12 can be vacuum metallized onto film 12. Vacuum metallization has
been found to provide a smoother, mirror like finish that can
create a reflective surface. For example, Applicants have found
that vacuum metallized aluminum provides a surface finish similar
to that of chrome. A more complete description of vacuum
metallization of a thermoform can be found in commonly owned U.S.
Pat. No. 5,811,050 to Gabower, the complete disclosure of which is
incorporated herein by reference.
[0044] Film layers 14 of the present invention can also take a
variety of forms. Exemplary material include, but are not limited
to, a thermoplastic resin such as polyvinyl chloride, an acrylic
resin, polystyrene, acrylic, acrylonitrile butadiene styrene,
cellulose acetate, cellulose propionate, cellulose acetate
butyrate, high density polyethylene, nylon, polycarbonate,
polypropylene, ABS resin, intrinsic conductive polymers (ICP), or
the like.
[0045] As is known in the art, resin 16 is typically applied to the
metallized film 15 through an injection molding process. As will be
described in more detail below, metallized film 15 will typically
be shaped prior to the injection molding. Resin layer 16 can
include various types of resin, depending on the application, final
product, and the like. Some examples of suitable resins include,
but is not limited to, polycarbonate, polycarbonate and ABS blends,
PETG, PBT, PC/PETG blends, intrinsic conductive polymers (ICP), and
the like.
[0046] Some additional combinations for multi-layered structures 10
of the present invention are illustrated in FIGS. 6 to 10.
Multi-layered structure can include one or more decorative layers
20 in addition to a shielding layer 22. Shielding layer will
generally have the same characteristics as metal layer 12 described
above. Decorative layer 20, however, can include any of a variety
of conventional or proprietary decorative layers. Decorative layer
can include an aesthetic layer of non-conductive paint, a colored
or transparent film, or other non-functional layers. Such
decorative layers can be deposited via pad printing, screen
printing, heat transfer molding, sublimation ink-transfer,
printable masks, or the like.
[0047] As illustrated in FIG. 6, in some embodiments, both a first
surface and a second surface of film can be decorated with a
decorative layer 20, 20'. A metal, shielding layer 22 can be
coupled to at least one of the decorative layers (in this
embodiment 20') to provide shielding to any electronic components
disposed within or behind multi-layered structure 10.
[0048] As shown in FIGS. 7 to 10, film layer 14 can have a
decorative layer 20 disposed along only one surface. In such
embodiments, the metal layer 22 can be coupled to the film layer 14
directly (FIGS. 7 and 10) or indirectly (FIGS. 8 and 9).
[0049] In FIG. 8, film layer 14 can be clear and would be the
outside surface of the end product allowing the decoration layer to
be visible through clear film layer 14. Alternatively, resin layer
16 can be along the outside surface of the housing and can be
clear, thus allowing visibility through layer 16. In regards to
FIG. 9, layers 14, 16 can be clear and/or layer 22 does not cover
the decoration.
[0050] In each of the embodiments, depending on its specific use,
resin layer 16 can either be along an outer surface or inner
surface of the final product. For example, in FIG. 2, a clear or
colored resin 16 can be on an outer surface of an electronics
housing, such that metal layer 12 can be viewed through the resin
layer. Alternatively, FIG. 4 illustrates an embodiment in which
overcoat 18 can be positioned along an outer surface of the final
product so as to protect metal layer 12 from the environment. It
should be appreciated however, that the flexibility provided by the
concepts of the present invention allow the combination of FIG. 4
to be switched such that resin layer 16 is along the outer surface
of the final product, and overcoat layer 18 can be an insulating
layer to provide protection from incidental contact of any enclosed
electronics with the conductive portions of the shield.
[0051] Exemplary uses of the multi-layered structures 10 of the
present invention include forming an electronic device 24, such as
a cellular phone housing, personal digital assistant (PDA), laptop
computers, video game consoles, or other devices which use a
plastic housing. As shown in FIG. 11, housing 25 of electronic
device 24 will typically include any of the above combinations of
resin layer 16, metal shielding layer 22, and decorative layer 20.
In such embodiments, in order to ground the metal shielding layer
and to create a Faraday cage, the metal shielding layer can use a
grounding element 26, such as a conductive tab, conductive
adhesive, threaded metal screws for housing, gaskets, or the like,
to ground the metal shielding layer to a ground trace of a printed
circuit board 28. Electronic devices 24 having an integrated
plastic/shielding structure that provides the required shielding
and mechanical protection of enclosed electronics can be produced
at a lower cost, are lighter weight, and can have a more compact
design than would otherwise be achieved with alternative
solutions.
[0052] In other exemplary uses, as shown in FIG. 12, the present
invention can be used to create improved reflective surfaces, such
as a lamp housing, vehicle reflectors or head lights, flashlights,
or the like. In such embodiments, the resin 16 and metallized film
15 can be formed to create a lamp housing 30 so as to reflect and
focus light that is emitted from a light source 32.
[0053] FIGS. 13 to 18 illustrate a simplified method of
manufacturing the multi-layered structure of the present invention.
As shown in FIG. 13, flat film 34, such as a thermoform film, can
be positioned over a male or female vacuum mold 36 and the film can
be formed using a variety of conventional thermoforming methods,
including vacuum forming, pressure forming, and/or plug assist
(FIG. 14).
[0054] In some methods, the flat film 34 can be pre-decorated on at
least one side, as shown by reference numerals 35,35'. As can be
appreciated, the decorative feature will be modified to account for
the known deformation that will take place during shaping. Some
exemplary decorating methods are printable masks, screen printing,
hot stamping, painting, silkscreening, pad printing, or the
like.
[0055] In other embodiments, it may be possible to decorate the
film after shaping flat film 34. For example, for complicated
designs it may be more cost effective to post form the complicated
decorations that may be distorted during forming.
[0056] Optionally, after the film has been formed into its desired
shape, if the film has not already been pre-decorated, one or both
sides of film 34 can be decorated with a metal or non-metal
decorative feature 35, 35' to create the decorated and shaped
insert 38 (FIG. 15). If desired, the shaped and decorated insert 38
can be metallized with a metal layer 40 (FIG. 16). As noted above,
if metal layer 40 is an EMI shield, it is preferable to deposit the
EMI shield 40 after film 38 has been shaped. By depositing the
metal layer 40 on the pre-shaped film 38, the continuity and
shielding effectiveness of the metal layer 40 can be maintained so
as to provide effective EMI shielding.
[0057] While it is possible to metallize the film prior to shaping,
Applicants have found that the metal layer tends to thin or crack
at the curves and sharp bends during the shaping process. Such
thinning and cracking reduces the shielding effectiveness of metal
layer 40.
[0058] In exemplary embodiments, metal layer 40 and decorating
layer can be deposited through a vacuum metallization process. The
vacuum metallization process has been shown to produce a
substantially even layer, and thus a substantially even EMI shield.
It should be appreciated however, that other methods of depositing
the metal layer can be used. For example, other methods of
depositing the metal layer 40 onto film 34 include painting,
sputtering, electroplating, deposition coating, electroless
plating, laminated conductive layers, or the like. For example,
while it is possible to paint a conductive layer onto film 34,
conventional conductive paints and inks only provide a shielding
effectiveness of less than approximately 45 dB. Moreover, such
paints and inks require the use of silver as part of the basic
material, and such silver paints are not environmentally sound
since the deposition process creates extensive organic volatile
emissions. Recycling of such painted structures is further
problematic because of state and federal regulations against the
dumping of silver based paints. For these reasons, vacuum
metallization of an aluminum (or other environmentally safe
material) is preferred over painting with conductive paints and
inks.
[0059] As shown in FIG. 17, the pre-shaped and metallized insert 42
is manually or robotically placed in an injection molding cavity
44. As is know in the art, the injection mold typically includes an
injection mold cavity 44 and core 46. The injection mold core 46
typically includes a runner/gate in which the molten plastic is
injected into the cavity. The molten plastic resin 43 is delivered
into the injection mold cavity 44 so as to contact the metallized
insert 42. In the illustrated embodiment of FIG. 18, the molten
resin 43 directly contacts the metal layer 40. In other
embodiments, however, the molten resin can contact an undercoat
(FIG. 5) or the film layer (FIG. 1). The exact layering
combinations of each of the particular layer will depend on the
specific end-use of the multi-layered structure, the materials used
for each layer, the properties of the materials used in each layer
(e.g., heat resistance, cost, chemical resistance,
impact-resistance requirements, aesthetics, and the like.
[0060] Referring again to FIG. 11, the present invention provides
improved shielded electronic housings for both wireless and fixed
electronic devices. As shown in FIGS. 19A and 19B, it may be
possible to add a small, thin electronics package 48 to the layer
combinations. The thin electronics packages could be used for
antennas, sensors, lights, MEMS (micro electromechanical systems)
or the like. The electronics can, but is not limited to, being
placed between the film layer (decorated or not decorated) and the
metal shielding layer. Such a combination would allow the
electronics packaged to be shielded from the internal noise from
the electronics contained within the housing.
[0061] In order for the electronic devices and electronic housings
of the present invention to be shielded, the metallized layer in
the multi-layered substrate must be grounded, typically to the PCB
ground traces disposed within the housing. FIGS. 20 to 21
illustrate two exemplary methods of grounding the metallized layer
of the housing to the PCB. As shown in FIG. 20, in some embodiments
of the present invention, a formed and metallized polymer insert 50
(such as a metallized polycarbonate layer) can be shaped to
correspond with the shape of the outer housing 52. Thus, the outer
housing can be retrofitted with a metallized substrate 50 to shield
the electronic components disposed within the electronic enclosure.
As illustrated in FIG. 20, oftentimes, the electronics enclosure 52
can include support ribs 54 that can contact the grounding traces
56 of a printed circuit board 58. To ground the metallized
substrate 50 to the ground traces of the printed circuit board, a
solder paste 60 can be deposited onto the metallized substrate 50
over the ground traces 56 and soldered or heat reflow soldered to
the printed circuit board.
[0062] FIGS. 21A and 21B shows a formed shield 62 that is coupled
to a printed circuit board 58. As shown, the formed shield includes
a metal layer 64 sandwiched between two shaped polymer inserts 66,
68. As noted above, metal layer 64 is typically vacuum metallized
onto one of the polymer inserts. However, it should be appreciated
that one or more layers can be applied using any of the variety of
methods described above. In order for the sandwiched metal layer 64
to be grounded to the ground trace 56, a via 70 can be formed
through shield 62. The via 70 can then be filled with a molten
solder or conductive adhesive 72 to create a conductive path
between ground trace 56 and metal layer 64. Advantageously, the
molten solder will have a tendency to be pulled in between the two
polymer layers along the metal fibers or metal layer so as to
provide a stronger ground connection to the metal layer. Once the
adhesive or solder has solidified, the solder can act as a rivet to
both mechanically and conductively attach the shield to the printed
circuit board. It should be appreciated however, that while the
method illustrated in FIG. 21 shows a metal layer disposed between
two polymer layers, the bonding method may work equally well with a
shield having an exposed metal layer.
[0063] In addition to the methods illustrated in FIGS. 20, 21A and
21B, other methods can be used to conductively and mechanically
attach the shield to the ground trace. For example, a solder,
pressure activated adhesive, conductive adhesives or the like can
be used to bond the metal layer to the ground traces. Additionally,
laser heat, an ultrasonic weld, or the like can be used to melt or
soften the portion of the metal layer disposed over the ground
trace.
[0064] Finally, as shown in FIG. 22, during manufacturing of the
printed circuit board, a well or indentation 76 can be created in
the printed circuit board 58 in the locations of the grounding
traces 56. These wells 76 can be adapted to receive a matching
contour of the ribs 54 of the shield or housing. Advantageously,
the wells 76 can increase the contact surface are between the
shield and the ground traces and can provide a recess for the
solder or conductive adhesive to pool during application.
[0065] While the above is a complete description of the preferred
embodiments of the inventions, various alternatives, modifications,
and equivalents may be used. For example, other combinations or the
number of decorative layers, film layers, EMI shielding layers,
resin layers, undercoats, overcoats, and can be used without
departing from the scope of the present invention. Moreover, in
addition to electronic housings and reflectors, the present
invention can be used to provide unique decorative appearances
particularly when used with clear or colored plastics. Although the
foregoing has been described in detail for purposes of clarity of
understanding, it will be obvious that certain modifications may be
practiced within the scope of the appended claims.
* * * * *