USOO7358447B2
`
`(12) United States Patent
`GabOWer
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,358.447 B2
`Apr. 15, 2008
`
`(54) ELECTROMAGNETIC INTERFERENCE
`SHIELDS FOR ELECTRONIC DEVICES
`
`4,489,116 A 12/1984 Flood
`4,542,076 A
`9, 1985 Bednarz et al.
`
`WI S
`M
`: John F. Gab
`(75) I
`nventor: John F. Gabower, Mauston, WI (US)
`(73) Assignee: WaveZero, Inc., Sunnyvale, CA (US)
`
`(*) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 278 days.
`(21) Appl. No.: 10/659,838
`
`(22) Filed:
`65
`(65)
`
`Sep. 10, 2003
`Prior Publication D
`rior Publication Data
`US 2004/OO48077 A1
`Mar. 11, 2004
`O
`O
`Related U.S. Application Data
`(60) Continuation of application No. 09/732,235, filed on
`Dec. 7, 2000, now Pat. No. 6,624,353, which is a
`continuation of application No. 08/958,595, filed on
`Oct. 29, 1997, now Pat. No. 6,570,085, which is a
`division of application No. 08/463,297, filed on Jun.
`5, 1995, now Pat. No. 5,811,050, which is a continu-
`ation-in-part of application No. 08/254.250, filed on
`Jun. 6, 1994, now abandoned.
`
`(51) Int. Cl.
`H05K 9/00
`(2006.01)
`(52) U.S. Cl. ....................................... 17437s. 174,300
`(58) Field of Classification Search .............. 174/35 R,
`174/35 MS, 378,390; 361/816, 818
`See application file for complete search history.
`References Cited
`
`(56)
`
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`Primary Examiner Hungy. Ng
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`and Crew LLP
`
`(57)
`
`ABSTRACT
`
`An EMI shield for personal computers, cellular telephones,
`and other electronic devices is constructed from thermo
`formable polymeric material which is then metallized on all
`Surfaces by vacuum metallization techniques to provide an
`inexpensive, lightweight, yet effective EMI shield.
`
`12 Claims, 5 Drawing Sheets
`
`
`
`27
`
`29
`
`
`
`S
`
`a Q
`
`Momentum Dynamics Corporation
`Exhibit 1012
`Page 001
`
`

`

`US 7,358.447 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
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`Gabower
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`5,225,629
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`5,243,126
`5,250,342
`5,270,488
`5,285,619
`5,286,528
`5,355,016
`5,373,102
`5,394,304
`5,395,659
`5,405,000
`5,436,803
`5.438,482
`5,468,910
`5,519,168
`5,524,697
`5,538,576
`5,550,713
`5,557,064
`5,559,676
`5,559,677
`5,566,055
`5,597,979
`5,598,034
`5,639,989
`5,704,117
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`5,811,050
`5,822,690
`5,825,634
`5,837,086
`5,864,088
`5,872,332
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`5,969,418
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`6,096.413
`6,097,613
`6,110,563
`6,121,545
`6,127,038
`6, 140,575
`6,147,879
`
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`
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`
`174,35MS
`
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`
`OTHER PUBLICATIONS
`BMI, Inc., Product Announcement, “Modular Shielding System.”
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`(1994).
`Gabower, John H. (Jack), “Thermoformed Vacuum Metallized
`Inserts For EMI Shielding of Electronic Devices.” Consumer Elec
`tronics Show, Flamingo Hilton and Tower, Las Vegas, Nevada.
`Gabower, Jack (Hohn H.), “Thermoformed Vacuum Metallized
`Inserts for Emi Shielding.” Item 1995—The International Journal of
`EMC, Robar Industries, Inc., (1995) pp. 120, 122, 127.
`General Electric Co., “Silver-Coated VALOX FR-1 Film Provides
`Shielding For Circuit Breakers.” GE Films in Action, (Jun. 1994).
`General Electric Plastics Co., “Methods of Controlling EMI.”
`EMI/RFI Shielding Guide.
`E. Grerg, F. Jones and A. Horton, “Machinery's Handbook.” Indus
`trial Press, New York, NY (1976) pp. 2299-2301.
`Gwinner, Dieter, "Vacuum Evaporated Aluminum for Selective
`Shielding of Plastic Housings.” ITEM 1993 The International Jr.nl
`of EMC (1993).
`Hasler, Walter, “Electroplating and Vacuum Metalizing.” Technical
`Report, Balzers Akiengesellschaft, Lichtenstein, published in
`Galvanotechnic, 2 (1984).
`Hollard, L., “Vacuum Deposition of Thin Films.” Degassing of
`Plastic Material/Plasticizers, Chapman & Hall Ltd., London (1996)
`pp. 46-47, 52-53.
`Kimmel & Gerke, "Chapter 7: Shielding of EMI Control . . . and
`how to do it right.” EDN, Jan. 2, 1994 Supplement.
`LaBounty, T., Aluminum Evaporation (Time-Temp.) “How Do
`Others Metallize?,” Midwest Technical Service, Tips (1980) p. 19.
`Leonard, “What's hot and what's not in EMI shielding of plastics.”
`Plastics Design Forum, (Mar/Apr. 1993).
`Maissel, Leon I. and Reinhard Glang, “Handbook of Thin-Film
`Technology,” McGraw-Hill (1970) pp. 1-7, 8:1-26, et seq; 1-38, 39.
`Midwest Tungsten Service, Tips Vacuum Metallizing Electrical
`Problems (1986).
`Minnesota Mining & Mfg. Co., "6100 Thermoformable EMI
`Shidlding Material.” (1994).
`Mooney, “Trent to Lower Cost Resins Will Accelerate.” Plastics
`World. (Apr. 1995).
`Orion Industries Incorporated, “Orion R. Designs Economical EMI
`Shielding Box Without Cutting Corners,” product brochure.
`Placon Corp., Madison, Wisconsin Sales Brochure.
`Rigney, D., "Vacum Coating.” pp. 387-388, 390-410.
`Consise Encyclopedia of Polymer Science & Engineering, John
`Wiley & Sons, 1990 ISBN 0-471-5.1253-2, pp. 446-447, 744-746,
`1192-1195.
`“EMI Protection in Consumer Portable Products.” Electronic Pack
`aging and Production (Mar. 1994).
`“Style CBS Circuit Board Component Shielding Design Guide 4.'
`product brochure, Leader Tech, Tampa, Florida.
`Ultrasonic Welders Advanced Claimshell-Sealing Process, Packag
`ing (Oct. 1994).
`Vacuum Platers, Inc., “VAEMAT High performance Vacuum
`Evaporated Film Coatings.” Product Data Sheet.
`Vacuum Platers, Inc., Advertising Folder.
`Silver Shielding for the Highest Performance, Swift Textile Metal
`izing Corporation, ITEM (1995) pp. 11, 15, 109, 112, 113, 115, 116,
`212, 213, 267, 269.
`* cited by examiner
`
`Momentum Dynamics Corporation
`Exhibit 1012
`Page 002
`
`

`

`U.S. Patent
`
`Apr. 15, 2008
`
`Sheet 1 of 5
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`US 7,358.447 B2
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`
`
`Momentum Dynamics Corporation
`Exhibit 1012
`Page 003
`
`

`

`U.S. Patent
`
`Apr. 15, 2008
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`Sheet 2 of 5
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`US 7,358.447 B2
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`62
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`Z?
`
`ØZZZZZZZZZZZZZZZZ
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`Momentum Dynamics Corporation
`Exhibit 1012
`Page 004
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`

`

`U.S. Patent
`
`Apr. 15, 2008
`
`Sheet 3 of 5
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`US 7,358.447 B2
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`
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`
`
`FIGURE 4
`
`Momentum Dynamics Corporation
`Exhibit 1012
`Page 005
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`

`

`U.S. Patent
`
`Apr. 15, 2008
`
`Sheet 4 of 5
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`US 7,358.447 B2
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`30
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`FIGURE 6
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`
`
`FIGURE 7
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`Momentum Dynamics Corporation
`Exhibit 1012
`Page 006
`
`

`

`U.S. Patent
`
`Apr. 15, 2008
`
`Sheet S of 5
`
`US 7,358.447 B2
`
`100
`
`75
`
`50
`
`Q
`
`Surface to Substrate
`Centerline
`
`N S
`Š
`
`Y
`Y Y
`NWorking Range N
`
`2
`8
`
`q) 9
`d
`:
`8. 2
`
`E
`6
`
`25 N
`N N
`
`
`
`30 45 60
`O
`6O 45 30
`Angle of incidence 6 to coated surface. degrees
`
`F.G. 8
`
`injection
`Molded
`Part
`
`Thermoform
`Part
`
`5
`
`CD
`3 4
`
`C
`
`3
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`8
`g 2
`
`c
`Z
`
`Šs SS ŠN
`
`
`
`1
`18 in.
`16
`14,
`2
`10
`8
`6
`4
`2
`40 45 Crm.
`35
`30
`25
`2O
`15
`10
`5
`Relative distance h filament to surface Coated
`
`FG. 9
`
`Momentum Dynamics Corporation
`Exhibit 1012
`Page 007
`
`

`

`1.
`ELECTROMAGNETIC INTERFERENCE
`SHIELDS FOR ELECTRONIC DEVICES
`
`US 7,358,447 B2
`
`2
`Each of the current shielding methods have shortcomings.
`The major disadvantages of plating are its high cost, com
`plex process cycles, and its application is limited to only
`certain polymer resins. Metal-filled resins for injection
`molding Suffer from poor conductivity compared to metals.
`The conductive polymer resin is very expensive and com
`plex shape molding is difficult from flow and uniformity
`perspectives.
`Three general types of conductive metal-bearing paints
`are in general use. Silver paints have the bast electrical
`properties but, they are extremely expensive. Nickel paints
`are used for relatively low attenuation applications and are
`limited by high resistance and poor stability. Passivated
`copper paints have moderate cost and lower resistivity, but
`also lack stability. All paint applications have difficulties
`with coating uniformly, blow back in tight areas and recesses
`depending on part complexity, and application problems
`which can lead to flaking. Paints also fail ESD testing over
`1OKVA
`EMI shielding through the use of metal cases for the
`personal computer or other electronic device may not always
`be desired because of concerns about weight and aesthetics,
`with weight being a serious concern for laptop computers or
`portable and handheld devices of any types. The use of a
`metal shroud to line a plastic case improves over the metal
`case in aesthetic and design concerns for the outside of the
`housing but results in an increased assembly step and little
`weight minimization. Metal also lacks the ability to be
`formed into complex shapes often taking up unnecessary
`room adjacent to the circuitry and assembled electrical
`components.
`The use of coated plastic housings for electronic devices,
`including microcomputer and cellular telephones, may not
`provide a Suitable solution when one considers that personal
`computers currently offered may operate at clock speeds of
`100 MHz, which gives rise to opportunities for EMI genera
`tion not previously confronted in the personal computer
`industry. Further, the ever increasing clock speeds of the
`personal computers being offered makes effective shielding
`more and more challenging since any breach in the shield
`which has one dimension in excess of 0.23 inch may allow
`substantial EMI leakage, causing the unit to fail United
`States Federal Communication Commission standards.
`The use of metallic coatings on plastic housings presents
`certain manufacturing and service concerns. A slipped tool
`used during assembly or a repair can cause a scratch in the
`metal coating of Sufficient size to cause a slot antenna,
`thereby making the case totally useless, and thereby leading
`to a costly item being discarded with little feasibility for
`Successful recycling.
`The seams of a metal plated plastic housing will act like
`slot antennae unless the housing sections are conductively
`joined by the use of overlapping joints, conductive gaskets,
`or conductive tape. When the housing must be opened for a
`repair or retrofit, it can be understood that some of the
`conductive interconnection may be degraded by the activity
`of disassembly.
`Further background on prior art methods and character
`istics of shielding methods may be examined in EMI/RFI
`Shielding Guide” published by the GE Plastics Division of
`the General Electric Company, and in “the Designer's Guide
`to Electromagnetic Compatibility” by Gerke & Kimmel,
`Supplement to EDN Magazine, Volume 39, No. 2, (Jan. 20.
`1994) to both of which the reader is directed.
`
`This application is a continuation of U.S. Ser. No. 09/732,
`235, filed on Dec. 7, 2000, which is a continuation of U.S.
`patent application Ser. No. 08/958,595, filed Oct. 29, 1997,
`which is a divisional of U.S. patent application Ser. No.
`08/463,297, filed Jun. 5, 1995, (now U.S. Pat. No. 5,811,
`050) which is a continuation-in-part of U.S. patent applica
`tion Ser. No. 08/254.250, filed Jun. 6, 1994, the complete
`disclosures of which are incorporated herein by reference.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`15
`
`This invention pertains to shielding apparatus for con
`taining high frequency electromagnetic radiation within a
`personal computer, cellular telephone, or other electronic
`instrument.
`Electromagnetic compatibility (EMC) is a broad term
`used to describe electromagnetic interference (EMI), radio
`frequency interference (RFI) and electrostatic discharge
`(ESD), and the above terms are often used interchangeably.
`The fact that electronic devices are both sources and
`receptors of EMI creates a two-fold problem. Since electro
`magnetic radiation penetrating the device may cause elec
`tronic failure, manufacturers need to protect the operational
`integrity of their products. Secondly, manufacturers must
`comply with the regulations aimed at reducing electromag
`netic radiation emitted into the atmosphere. Proper design is
`necessary to prevent the device's function from being dis
`rupted by emissions from external Sources and to minimize
`its systems emissions.
`Today, plastics are replacing metals as the material for
`electronic enclosures since plastics offer increased design
`flexibility and productivity with decreased cost. The switch
`from metal to plastics as a housing material for electronic
`equipment has contributed to concern over EMI shielding.
`Plastics are insulators, so EMI waves pass freely through
`unshielded plastic without Substantial impedance or resis
`tance. Additionally, ever increasing device miniaturization
`and the increase in clock speeds of microprocessors used in
`computing devices makes it more difficult to handle the EMI
`pollution these faster computers generate. So a variety of
`technologies using metal/polymer combinations and com
`45
`posites are being used as a shielding material in electronic
`devices.
`Current methods for shielding of electromagnetic inter
`ference (EMI) include the use of metal housings, metal filled
`polymer housings, metal liners for housings, and conductive
`coatings for the interior of rigid polymer or composite
`housings.
`Metal coatings for rigid plastic housings are applied
`through use of conductive paints or through application of
`metal platings applied by chemical plating (electroless plat
`ing), by electroplating, or through vacuum metallization. In
`addition, metal foils with adhesive backings may be applied
`to the inside of plastic cases for electronic instruments to
`achieve shielding requirements. Zinc Arc spray techniques
`are also available to apply a metal coating to a plastic
`housing.
`Another shielding material is provided through the use of
`metal fibers sintered onto a polymeric Substrate as is taught
`in U.S. Pat. No. 5,226,210, and commercially produced as
`#M 610D Thermoformable EMI-shielding material by the
`Minnesota Mining and Manufacturing Company of St. Paul,
`Minn.
`
`25
`
`30
`
`35
`
`40
`
`50
`
`55
`
`60
`
`65
`
`Momentum Dynamics Corporation
`Exhibit 1012
`Page 008
`
`

`

`3
`SUMMARY OF THE INVENTION
`
`US 7,358,447 B2
`
`4
`thermal evaporation, cathode sputtering, ion plating, elec
`tron beam, cathodic-arc, or vacuum thermal spray.
`Because a thermoformed enclosure is used, the shield is
`of reduced weight and if damage occurs to the thermo
`formed shield during manufacturing or repair of the elec
`tronic device, a less costly replacement item is needed.
`The use of interlockable enclosure bodies which may snap
`together or otherwise be mechanically held in assembled
`state, permits the walls of the shield to be in conductive
`contact and reduces or eliminates the need for conductive
`tape or conductive gaskets while providing an effective EMI
`shield. Further securing means may be employed, Such as by
`use of conductive adhesive, laser welding, or heat sealing.
`It is accordingly an object of the invention to provide an
`EMI shield which may be thermoformed into a desired
`shape with metallization applied on all surfaces of the shield.
`It is another object of the invention to provide an EMI
`shield which provides an easy-to-manufacture shield with
`excellent attenuation of the strength of electric or magnetic
`fields.
`Another object of the invention is to provide an inexpen
`sive EMI shield that will not be totally degraded by a scratch
`on one surface of the shield.
`Another object of the invention is to provide an EMI
`shield which is light weight.
`Another object of the invention is to provide an EMI
`shield which may be nested for shipment.
`Another object of the invention is to provide an EMI
`shield with Superior conductive wall coupling structure.
`Another object of the invention is to provide an EMI
`shield which will not need application of conductive tape or
`gaskets to provide adequate shielding.
`Another object of the invention is to provide an EMI
`shield which increases resistance of the shielded compo
`nents to corrosive atmospheric conditions.
`These and other objects of the invention will become
`understood from a review of the detailed description of the
`invention which follows.
`
`DESCRIPTION OF THE DRAWING FIGURES
`
`FIG. 1 is an exploded perspective view of a laptop
`personal computer having the shield invention installed
`therein.
`FIG. 2 is an enlarged view of a typical cross section of a
`sidewall of the preferred embodiment shield invention.
`FIG. 3 is a schematic view of the typical apparatus used
`for applying metal deposition to the polymer thermoforms of
`the preferred embodiment.
`FIG. 4 is a plan view of the preferred embodiment of the
`invention in its unfolded arrangement.
`FIG. 5 is an enlarged perspective view of the intercon
`necting edges of the preferred embodiment shield invention.
`FIG. 6 is an enlarged cross section of the engagement
`between a cover member and a base member of an alternate
`embodiment of the shield invention.
`FIG. 7 is an enlarged cross section of a second alternate
`embodiment of the shield invention showing the cover
`thereof in phantom in an open position.
`FIG. 8 is a graph of relative coating thickness as a
`function of vapor stream incident angle; and
`FIG. 9 is a comparison of work range injection molded vs.
`thermoformed parts distance from part to vapor source.
`
`This invention pertains to EMI shielding for personal
`computers, cellular telephones and other electronic devices
`which are subject to Part 15 of the FCC Rules. A thermo
`formable polymeric sheet is formed into an enclosure sized
`and shaped to enclose an EMI emitting Subsystem or com
`ponent. The thermoformed polymeric enclosure is then
`metallized on all or selected Surfaces by vacuum metallizing
`techniques where the thermoformed enclosure is placed in a
`vacuum chamber, treated with an ionized gas, and then
`metallized by the use of aluminum or other metal being
`vaporized by use, for example, of a current-passing tungsten
`filament, or other vaporization techniques. The enclosure is
`rotated within the chamber to allow metallization of all
`desired surfaces. Masking may be employed when certain
`regions or surfaces are preferred not to be metallized. The
`enclosure is thereby provided with walls having a polymeric
`Substrate provided on desired Surfaces with a vacuum met
`allized layer. The vacuum metallized layers are of sufficient
`thickness to make the surfaces of the enclosure electrically
`conductive. The enclosure is formed in the shape and size
`necessary to house and shield the EMI emitter; for example
`in the case of a personal computer, the enclosure may serve
`as a thin-walled case within the rigid outer housing of the
`computer. Alternatively, the enclosure may be formed to fit
`as an insert within a device's housing as a Substitute for a
`metal insert shield, or the enclosure may be shaped and sized
`to contain only certain components which are emitters of, or
`susceptible to, EMI. Gangs of metallized enclosures may be
`devised with electrical isolation as desired provided by gaps
`in the metallization layers. Different electronic devices will
`require varying degrees of attenuation or shielding effec
`tiveness. The enclosure may be coated on all Surfaces or
`selectively coated for certain applications.
`Thermoformed shapes have previously been vacuum met
`allized with thin-film coatings (350 to 1000 angstroms or
`0.035 to 0.10 microns) but only for their reflective metallic
`appearance. Conventional thin-film vacuum metallizing is
`not adequate to dissipate EMI. Existing equipment for
`metallizing thermoformed shapes for ornamental reflective
`appearance purposes is not suitable for application of rela
`tively thick thin film as is required to provide suitable
`surface impedance to allow effective EMI dissipation.
`Many polymeric materials are thermoformable. Formabil
`ity, thickness, melt strength, shrinkage, flame retardency,
`and other properties are factors determined by the end user
`of the finished product. Extruded roll or sheet materials
`suitable for thermo forming include Acrylonitrile-Butenate
`Styrene (ABS), polystyrenes, cellulose polymers, vinyl
`chloride polymers, polyamides, polycarbonates, polysul
`fones, and olefin polymers such as polyethylene, polypro
`pylene, polyethylene terephthalate glycol (PTG) and methyl
`methacrylate-acrylonitrile (co-polymers).
`Use of these polymers with additional fillers such as
`carbon black, graphite, and metal fibers, add to the shielding
`effectiveness for absorbing more of the lower electro-mag
`netic wave lengths.
`The polymeric enclosures are not metallically coated until
`after the thermoforming process. Because the forming pro
`cess stretches or draws the material into corners and
`recesses, it would also draw or thin the metallic coating
`making its uniformity vary in different areas on the formed
`shape if coatings were applied prior to forming.
`After forming, metallic coatings may be applied to the
`shapes by a variety of vacuum deposition techniques such as
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`Momentum Dynamics Corporation
`Exhibit 1012
`Page 009
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`US 7,358,447 B2
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`5
`DETAILED DESCRIPTION OF THE
`INVENTION
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`overlap, EMI shielding is made substantially thorough as the
`touching engagement of overlapping second section 20 on
`first section 18 provides electrical conductivity between the
`sections. Conductive adhesive or conductive tape may be
`added to the seam formed between first section 18 and
`second section 20 to ensure sufficient EMI shielding in the
`seam region. Hinge region 22 provides a conductive path
`between first section 18 and second section 20. To aid in
`reducing gaps in EMI shielding effect, conductive adhesive
`36 may be applied to flanges 38 and 40 of blank 30, which
`will come into abutment when enclosure bodies 18 and 20
`are folded about hinge 22 for edgewise engagement.
`FIG. 5 illustrates further the novel mechanical locking
`means of the preferred embodiment EMI shield 2. Boss 39
`is formed upon flange 40 of first section 18 and is engage
`able with recess 41 formed in flange 38 to provide additional
`retention forces when first section 18 and second section 20
`are engaged.
`FIG. 3 discloses apparatus for vacuum deposition of
`metallic coating on thermoformed blank 30 which is placed
`on carrier 62 in evacuable chamber 60. Chamber 60 is
`evacuated and a gas, including a gas from the group includ
`ing Argon, Nitrogen, Oxygen, CF and SF, is passed into
`chamber 60, excited by an electric charge, and the resulting
`ionized gas serves to modify the surfaces of blank 30.
`Chamber 60 is again evacuated and carrier 62 is caused to
`revolve around tungsten filament 64 which is energized
`electrically to provide energy to vaporize metal 66, the
`molecules of which travel from filament 64 and are depos
`ited on blank 30. Blanks 30 may alternatively be retained to
`planetary mount 68 which rotates about itself as it revolves
`about filament 64 in the direction of arrows. Control 67 is
`associated with chamber 60 to cause evacuation of the
`chamber, introduction of gas for Surface modification of the
`blank, and energization of the filament.
`FIG. 6 illustrates another embodiment of the shield inven
`tion wherein a thermoformed case 130 is formed of formable
`sheet polymer. Lid 132 is likewise thermoformed of sheet
`polymer into a complementary shape. Lid 132 is provided
`with spring element 134 about its periphery, spring element
`134 being formed upon lid 132 and being urged into
`touching engagement with inner surface 138 of case 130.
`After case 130 and lid 132 are suitably thermoformed, they
`are passed through a vapor metal deposition operation where
`a metal film is deposited on selected Surfaces, including all
`surfaces thereof if desired. In the embodiment of FIG. 6,
`metal film of thickness between 1.0 and 50.0 microns is
`deposited upon outer surface 140 of lid 132 and a similar
`metal layer is vapor deposited upon outer Surface 142 of case
`130 and upon inner surface 138 of case 130. Inner floor
`surface 144 of case 130 is polymeric, having been masked
`to prevent deposit of metallization thereon. In this embodi
`ment, conductivity of surface 144 has been avoided in order
`to prevent interference with Surface circuitry of a component
`carrying board which may be installed within the shield of
`FIG. 6.
`FIG. 7 discloses another alternative embodiment of the
`shield invention wherein shield body 102 comprises a ther
`moformed polymer base 104 with a hinged cover member
`106. Shield body 102 is provided with projections 108 upon
`the upper area of first sidewall 110. Cover 106 is fixed by
`hinge 122 to case 104 and is provided with indents 112
`which are formed in the outer leg 114 of U-shaped recess
`116. Recess 116 extends around the periphery of cover 106
`and is provided to permit touching engagement of outer leg
`
`Referring to the drawing figures and in particular to FIG.
`1, the invention 2 is shown in place as a component of a
`laptop personal computer 4. Bottom case 6 of computer 4 is
`provided with power supply module 7 stationed therein.
`Invention 2 encloses the mother board of the computer 2,
`including the central processing unit, memory storage chips,
`input-output circuit components and the like (not shown).
`Top case 8 overlies invention 2 when invention 2 is placed
`within bottom case 6 of computer 4. Top case 8 includes
`keyboard 10 and visual display 12 which are interconnected
`to associated circuitry housed in invention 2 by leads 14.
`Power supply 7 and input/output ports 9 are electrically
`connected to associated circuitry housed in invention 2 by
`cables 16.
`FIG. 2 discloses a cross section of a wall of invention 2,
`showing a polymeric Substrate 25 having conductive met
`allization layers 27 and 29 applied thereto by vacuum metal
`deposition techniques. Each of layers 27 and 29 are a
`relatively thick, thin film of metal, preferably of aluminum,
`copper, or silver. In the preferred embodiment, aluminum is
`used, and is applied to the polymeric substrate 25 after the
`polymeric substrate has been thermoformed into a desired
`25
`enclosure shape and then its Surface is modified by bom
`bardment by an ionized gas in an evacuated chamber or by
`other means Suitable to increase Surface tension of the
`substrate 25. The substrate 25 is then placed in an evacuated
`chamber where a metal is vaporized and deposited on the
`substrate 25 on the surfaces thereof, through rotation of the
`substrate 25 about itself and about the metal vapor source.
`Substrate 25 has been earlier formed into a desired shield
`shape before application of the metallization layers 27 and
`29 in order to achieve a uniform thickness of metallization
`over the surfaces of substrate 25. By thermoforming sub
`strate 25 before subjecting it to the metallization step,
`problems with thinning of the metallization layers 27 and 29
`at corners, bends and the like, which might occur if the
`substrate were formed after metallization is applied, are
`avoided. If desired, certain regions of substrate 25 may be
`masked to prevent deposit of metal film on those regions.
`By applying a relative thick film (between 1.0 and 50
`microns thick), which has a surface impedance of less than
`one ohm per square per inch, a suitably conductive layer of
`45
`metallization is achieved which provides a low surface
`impedance and hence effective EMI attenuation. The appli
`cation of metallization layers 27 and 29 to opposing sides of
`substrate 25 increases the EMI attenuation achieved.
`FIG. 4 discloses the preferred embodiment of the inven
`tion 2 in its unfolded state. Polymeric sheet material is
`thermoformed into a desired shield blank 30 by conventional
`methods. Blank 30 comprises first section 18 and second
`section 20 interconnected by hinge region 22, all of which
`are formed from continuous polymeric sheet of generally
`uniform thickness. By use of thermoformable material, it
`can be understood that light weight is realized and that
`unassembled shield blanks 30 may be nested for shipment.
`From FIGS. 4 and 5. it can be seen that the edges 24 of
`first section 18 of blank 30 are formed to fit in complemen
`tary engagement with the edges 26 of second section 20 of
`blank 30. In particular, edges 24 of first section 18 are
`provided with shoulder recesses 19 wherein ridges 21 of
`second section 20 are receivable, such that the periphery 34
`of second section 20 is overlapped by the periphery 32 of
`first section 18 when first section 18 and second section 20
`are folded about hinge region 22 into engagement. By this
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`Momentum Dynamics Corporation
`Exhibit 1012
`Page 010
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`7
`114 with the sidewalls of base 104. At region 124, for
`example, conductive surface contact is provided between
`base 104 and cover 106.
`Shield 102 is first thermoformed into the desired shape
`from sheet polymer material and then a metallic layer is
`vapor deposited on all or selected surfaces of shield 102. The
`metallic layer is suitably thick to provide excellent surface
`conductivity thereby providing excellent EMI attenuation.
`It can be further understood that thermoformed shapes
`such as enclosure bodies 18 and 20 of FIG. 4 may be ganged
`together by interconnected webs, such as hinge 22 of FIG.
`4, wherein a metal deposition layer is applied to the outer
`surfaces of shapes 18 and 20 respectively while no metal
`lization is applied to hinge 22, such result being effected by
`application of masking to hinge 22 before it is passed into
`the evacuated chamber where metal is to be vapor deposited
`thereon. The resulting gang of metallized shapes may then
`be used to provide EMI shielding to dis