(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2004/0001299 A1
`(43) Pub. Date:
`Jan. 1, 2004
`Van Haaster et al.
`
`US 2004.0001299A1
`
`(54)
`
`EMI SHIELD INCLUDING A LOSSY
`MEDIUM
`
`(75)
`
`Inventors: Philip van Haaster, Corona, CA (US);
`Edward Nakauchi, Westminste, CA
`(US); Richard Norman Johnson,
`Encinitas, CA (US)
`
`Correspondence Address:
`TESTA, HURWITZ & THIBEAULT, LLP
`HIGH STREET TOWER
`125 HIGH STREET
`BOSTON, MA 02110 (US)
`
`(73)
`
`Assignee: LAIRD TECHNOLOGIES,
`DELAWARE WATER GAP, PA
`
`INC.,
`
`(21)
`(22)
`
`Appl. No.:
`
`10/319,797
`
`Filed:
`
`Dec. 13, 2002
`
`Related U.S. Application Data
`(60) Provisional application No. 60/340,343, filed on Dec.
`14, 2001.
`
`Publication Classification
`
`(51) Int. Cl. ................................................... HO2H 9/06
`(52) U.S. Cl. .............................................................. 361/118
`(57)
`ABSTRACT
`LOSSy materials can be used to SuppreSS EMI transmission.
`Disclosed are methods for applying lossy materials to EMI
`shielded enclosures to improve EMI shielding effectiveness
`and the EMI shielded enclosures so produced. In some
`embodiments, the EMI shielded enclosure includes a
`printed-circuit board mountable device. In one embodiment,
`lossy material can be applied to the interior of an EMI
`Shielded enclosure using an adhesive. In another embodi
`ment, lossy materials can be applied to the exterior of the
`EMI enclosure to suppress EMI incident upon the EMI
`Shielded enclosure, thereby reducing the Susceptibility of
`electronics contained within the EMI shielded enclosure. In
`yet another embodiment, lossy materials can be applied to
`both the interior and exterior of the EMI enclosure.
`
`
`
`100
`
`EMENCLOSURE
`
`102
`
`104
`
`104
`
`400
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 001
`
`

`

`Patent Application Publication
`
`Jan. 1, 2004 Sheet 1 of 13
`
`US 2004/0001299 A1
`
`
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 002
`
`

`

`Jan. 1, 2004 Sheet 2 of 13
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`Exhibit 1008
`Page 003
`
`

`

`Patent Application Publication
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 004
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 004
`
`

`

`Patent Application Publication
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 005
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 005
`
`

`

`Patent Application Publication
`
`Jan. 1, 2004 Sheet 5 of 13
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`Page 006
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`Patent Application Publication
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`Jan. 1, 2004
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`Patent Application Publication
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`Jan. 1, 2004 Sheet 9 of 13
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`Exhibit 1008
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`Patent Application Publication
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`Exhibit 1008
`Page 011
`
`

`

`Patent Application Publication
`
`Jan. 1, 2004 Sheet 11 of 13 US 2004/0001299 A1
`
`STEP 500
`
`STEP 510
`
`PROVIDE EM SHIELD
`
`PROVIDE ABSORBING MATERAL
`
`STEP 520
`
`SECURE THE ABSORBING MATERIAL TO EM
`SHIELD
`
`STEP 525
`
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`SECURE ABSORBINGEM SHIELD
`TO CIRCUIT BOARD
`
`FIG. 8
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 012
`
`

`

`Patent Application Publication
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`Jan. 1, 2004 Sheet 12 of 13
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`Page 013
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`

`

`Patent Application Publication
`
`Jan. 1, 2004 Sheet 13 of 13
`
`US 2004/0001299 A1
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 014
`
`

`

`US 2004/0001299 A1
`
`Jan. 1, 2004
`
`EMI SHIELD INCLUDING A LOSSY MEDIUM
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`0001. This application claims the benefit of and priority
`to U.S. Provisional Application Serial No. 60/340,343, filed
`on Dec. 14, 2001, the disclosure of which is incorporated
`herein by reference in its entirety.
`
`FIELD OF THE INVENTION
`0002 The present invention relates to generally to elec
`tronic component packaging and, more specifically, to elec
`tronic component packages that are shielded to protect
`against electromagnetic interference (EMI).
`
`BACKGROUND OF THE INVENTION
`0003. As used herein, the term EMI should be considered
`to refer generally to both electromagnetic interference and
`radio frequency interference (RFI) emissions, and the term
`“electromagnetic' should be considered to refer generally to
`electromagnetic and radio frequency.
`0004. During normal operation, electronic equipment
`typically generates undesirable electromagnetic energy that
`can interfere with the operation of proximately located
`electronic equipment due to EMI transmission by radiation
`and conduction. The electromagnetic energy can be of a
`wide range of wavelengths and frequencies. To minimize the
`problems associated with EMI, Sources of undesirable elec
`tromagnetic energy may be shielded and electrically
`grounded. Alternatively, or additionally, Susceptors of EMI
`may be similarly shielded and electrically grounded. Shield
`ing is designed to prevent both ingreSS and egreSS of
`electromagnetic energy relative to a housing or other enclo
`Sure in which the electronic equipment is disposed. Since
`Such enclosures often include gaps or Seams between adja
`cent acceSS panels and around doors, effective Shielding is
`difficult to attain, because the gaps in the enclosure permit
`transference of EMI therethrough. Further, in the case of
`electrically conductive metal enclosures, these gaps can
`inhibit the beneficial Faraday Cage Effect by forming dis
`continuities in the conductivity of the enclosure which
`compromise the efficiency of the ground conduction path
`through the enclosure. Moreover, by presenting an electrical
`conductivity level at the gaps that is Significantly different
`from that of the enclosure generally, the gaps can act as Slot
`antennae, resulting in the enclosure itself becoming a Sec
`ondary source of EMI.
`0005 Shields are generally constructed to reduce EMI at
`a particular wavelength, or range of wavelengths. EMI
`Shields are typically constructed of a highly-conductive
`material operating to reflect the radiation component of the
`EMI and to drain to electrical ground the conducted com
`ponent of the EMI. For example, EMI shields are typically
`constructed of a metal, Such as copper, aluminum, gold, tin,
`Steel, and StainleSS Steel, sheet metal and nickel. EMI Shields
`may also be constructed of combinations of different metals,
`Such as nickel-coated copper, and combinations of a con
`ductive material with an electrical insulator, Such as metal
`plated plastic. In the abstract, an ideal EMI shield would
`consist of a completely enclosed housing constructed of an
`infinitely-conductive material without any apertures, Seams,
`gaps, or vents. Practical applications, however, result in an
`
`enclosure constructed of a finitely-conducting material and
`having Some apertures. Generally, reducing the largest
`dimension (not merely the total area) of any aperture, as well
`as reducing the total number of apertures, tends to increase
`the EMI protection or shielding effectiveness of the enclo
`Sure. Apertures may be intentional, Such as those accom
`modating air flow for cooling, or unintentional, Such as those
`incident to a method of construction (e.g., seams). Special
`methods of manufacture may be employed to improve
`Shielding effectiveness by welding or Soldering Seams, or by
`milling a cavity. The shielding effectiveness of an EMI
`enclosure having an aperture is a function of the wavelength
`of the EMI. Generally, the shielding effectiveness is
`improved when the largest dimension of the aperture is Small
`compared to the wavelength (i.e., less than one-half the
`wavelength). As the frequencies of operation increase, how
`ever, the associated wavelengths of induced EMI decrease,
`leading to a reduction in Shielding effectiveness for any
`non-ideal EMI enclosure.
`0006 EMI shielded enclosures are typically constructed
`of conductive materials that induce resonances of the elec
`tromagnetic energy within the cavity. For example, reflec
`tions of the electromagnetic field at the boundaries of the
`cavity can create Standing waves within the cavity under
`certain conditions. Such resonances tend to increase the
`peak amplitudes of the electromagnetic energy through
`additive effects of the multiple reflections. These resonance
`effects, by increasing the peak energy levels within the
`enclosure, can reduce the apparent shielding effectiveness at
`the resonant frequencies because the same enclosure is
`Shielding a larger Source of EMI-the resonant peak elec
`tromagnetic energy.
`0007 EMI protection is particularly important in small,
`densely packaged, Sensitive electronic applications operat
`ing at high frequencies. In one application, a communica
`tions transceiver, Such as a Gigabit Interface Converter
`(GBIC), converts electrical currents into optical signals
`Suitable for transmission over a fiber-optic cable and optical
`Signals into electrical currents. GBICS are typically
`employed in fiber-optic telecommunications and networking
`Systems as an interface for high-Speed networking. AS the
`name Suggests, the data rates of transmission are greater than
`one gigabit-per-Second (Gbps). In Some applications GBIC
`modules are installed within an EMI enclosure. One par
`ticular form factor for an EMI cage 50, or housing, shown
`in FIGS. 1A and 1B is described in a Multi-source Agree
`ment (MSA) prepared by Several cooperating members
`within the related industry. As shown in FIG. 1, one end 55
`of the housing 50 is opened to accommodate the insertion
`and extraction of a GBIC transceiver (i.e., a transceiver
`having a form factor compliant with the Small-Form-Factor
`Pluggable specifications described in the “Cooperation
`Agreement for Small Form-Factor Pluggable Transceivers,”
`dated Sep. 14, 2000, the contents of which are herein
`incorporated by reference in their entirety). The MSA
`recommended EMI cage 50 offers a design level of shielding
`effectiveness for GBIC operations at 1 Gbps; however, as
`operating frequencies increase, the Shielding effectiveness of
`the recommended EMI cage, without modification, will be
`inadequate. For example, emerging applications using the
`optical carrier protocols described in the Synchronous Opti
`cal Network (SONET) standards can operate above 1 Gbps
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 015
`
`

`

`US 2004/0001299 A1
`
`Jan. 1, 2004
`
`(e.g., the OC-48 protocol Supporting data rates of up to 2.5
`Gbps and OC-192 protocol supporting data rates of up to 10
`Gbps).
`0008. There exist certain methods for providing EMI
`Shielding to electronic components. For example, U.S. Pat.
`No. 5,639,989 issued to Higgins, III, the disclosure of which
`is herein incorporated by reference in its entirety. Higgins
`discloses the use of a housing wherein all interior Surfaces
`are conformally coated with a first EMI material consisting
`of a polymer containing filler particles. The method dis
`closed in Higgins applies the first EMI material as a con
`formal coating. The disclosed method also indicates that
`selection of different materials for filler particles results in
`the attenuation of electromagnetic energy within Specified
`frequency ranges.
`
`SUMMARY OF INVENTION
`0009. In general, the present invention relates to an EMI
`Shield, Such as a highly-conductive metal enclosure or cage,
`that incorporates an electrically absorbing or lossy material
`to absorb a portion of the EMI, thereby enhancing the
`performance of the EMI shield over a range of operational
`frequencies. The absorbing material may remove a portion
`of the EMI from the environment by the process of ohmic
`loss-dissipating a portion of the EMI in the form of thermal
`heating. The absorbing material, when placed within a
`conductive cavity may also alter the resonant characteristics
`of the cavity to reduce resonant "peaks” of the electromag
`netic fields within the cavity, and/or to translate in frequency,
`a resonant peak or cutoff.
`0010. In one aspect, the invention relates to a shielding
`System for providing shielding from high-frequency, elec
`tromagnetic interference. The shielding System includes an
`electrically-conductive shield adapted for covering at least a
`portion of a device. The Shielding System also includes an
`electromagnetic absorbing material disposed on a first side
`of the electrically-conductive shield. The combined electri
`cally-conductive Shield and electromagnetic absorbing
`material attenuate a transfer of electromagnetic energy with
`respect to the Shielded device.
`0011. In one embodiment, the shielding system includes
`an enclosure defining a cavity Suitable for housing a device,
`Such as a board mounted device. In another embodiment, the
`housing is adapted for enclosing the device on Substantially
`all sides. In yet another embodiment, the electromagnetic
`absorbing material is applied to at least a portion of an
`interior Surface.
`0012. In one embodiment, the housing is adapted for
`attachment to a circuit board. In another embodiment, the
`housing includes at least one portion being removably
`attached. In another embodiment, the electrically-conduc
`tive shield is adapted for housing at least one of a fiber optic
`transmitter and a fiber optic receiver. In another embodi
`ment, the electrically-conductive shield is adapted for hous
`ing a gigabit interface converter (GBIC). In yet another
`embodiment, the electrically-conductive shield includes a
`form factor Substantially compliant with a Small-form-fac
`tor-pluggable Standard.
`0013 In one embodiment, the electrically-conductive
`Shield is Selected from the group consisting of aluminum,
`copper, nickel, tin, Silver, gold, beryllium, phosphor bronze,
`
`Steel, Stainless Steel, and combinations thereof. In another
`embodiment, the electrically-conductive shield includes
`sheet metal.
`0014.
`In one embodiment, the energy absorptive material
`is Selected from the group consisting of electrically conduc
`tive material, carbonyl iron powder, Sendust, ferrite, iron
`Silicide, magnetic alloys, magnetic flakes, and combinations
`thereof. In another embodiment, the energy absorptive mate
`rial includes electrically absorbing particles Suspended in a
`matrix. In another embodiment, the energy absorptive mate
`rial is Selected from the group consisting of electrically
`conductive material, carbon, carbonyl iron powder, Sendust,
`ferrites, iron Silicide, magnetic alloys, magnetic flakes, Steel
`wool, carbon-impregnated rubber, ferrite in a plastic
`Stranded carrier, metal foils, metal clad materials including
`iron, nickel, and iron/nickel compositions, paste composites
`Selected from the group consisting of iron, nickel, copper
`with epoxy, lacquer binders, and combinations thereof, and
`combinations thereof. In yet another embodiment, energy
`absorptive material is attached using a pressure Sensitive
`adhesive.
`0015. In another aspect, the invention relates to a process
`for attenuating a transfer of high-frequency electromagnetic
`energy with respect to a device. The proceSS includes the
`Steps of reflecting electromagnetic energy at an electrically
`conductive shield adapted for covering at least a portion of
`a device, altering an electromagnetic resonance associated
`with the electrically-conductive Shield, and absorbing a
`portion of electromagnetic energy proximate to the electri
`cally-conductive shield. The shield thereby reduces a trans
`fer of electromagnetic energy with respect to the device. In
`one embodiment, the Step of altering the electromagnetic
`resonance includes reducing a peak amplitude of the elec
`tromagnetic resonance.
`0016. In another aspect, the invention relates to a process
`for attenuating a transfer of high-frequency electromagnetic
`energy with respect to a device. The proceSS includes the
`Steps of providing an electrically-conductive Shield adapted
`for covering at least a portion of a device, and providing an
`electromagnetic absorbing material adapted for absorbing at
`least a portion of electromagnetic energy within a predeter
`mined range of wavelengths. The proceSS also includes the
`Steps of treating at least a portion of the electrically-con
`ductive shield with electromagnetic absorbing material and
`placing the treated electrically-conductive shield in the
`immediate vicinity of the device. The electrically-conduc
`tive shield reduces a transfer of electromagnetic energy with
`respect to the device.
`0017. In one embodiment, the step of treating includes
`applying the electromagnetic absorbing material to a first
`side of the electrically-conductive shield. In another
`embodiment, the Step of treating is Selected from the group
`including painting, dipping, Spraying, Vapor depositing, Silk
`Screening, mechanically fastening, chemically bonding, and
`combinations thereof. In another embodiment, the Step of
`treating includes at least one of molding, forming, and
`forming in place the electromagnetic absorbing material
`onto the electrically-conductive Shield.
`0018. In one embodiment, the step of providing an elec
`tromagnetic absorbing material includes forming a sheet of
`absorbing material having a predetermined thickness, and
`adapting the sheet of absorbing material for application to a
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 016
`
`

`

`US 2004/0001299 A1
`
`Jan. 1, 2004
`
`first side of the electrically conductive shield. In another
`embodiment, the adapting Step includes applying a chemical
`fastener to at least one side of the Sheet of absorbing
`material. In yet another embodiment, the adapting Step
`includes applying a preSSure Sensitive adhesive to at least
`one side of the sheet of absorbing material.
`0019. In yet another aspect, the invention relates to a
`Shield for attenuating a transfer of high-frequency electro
`magnetic energy with respect to a device, the shield includ
`ing means for reflecting electromagnetic energy adapted for
`covering at least a portion of the device, means for altering
`an electromagnetic resonance response associated with the
`means for reflecting electromagnetic energy, and means for
`absorbing a portion of electromagnetic energy proximate to
`the means for reflecting electromagnetic energy. The Shield
`thereby reduces a transfer of electromagnetic energy with
`respect to the device. In one embodiment, the means for
`reflecting electromagnetic energy includes an electrically
`conductive shield. In another embodiment, the means for
`altering an electromagnetic resonance includes an electro
`magnetic absorbing material.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0020. The invention is pointed out with particularity in
`the appended claims. The advantages of the invention may
`be better understood by referring to the following descrip
`tion, taken in conjunction with the accompanying drawings,
`in which:
`0021
`FIG. 1A is a schematic drawings depicting exter
`nal orthogonal views of a top, Side, and end of an electri
`cally-conducting EMI cage for a device;
`0022 FIG. 1B is a schematic drawing depicting an
`external view of a bottom of the electrically-conducting EMI
`cage of FIG. 1A;
`0023 FIG. 2A is a schematic drawing of one embodi
`ment of the invention, in which a lossy material is applied
`to an inside of a portion of an EMI enclosure;
`0024 FIG. 2B is a schematic drawing of an alternative
`embodiment of the invention, in which a lossy material is
`applied to an outside of a portion of an EMI enclosure;
`0.025
`FIG. 2C is a schematic drawing of another alter
`native embodiment of the invention, in which a lossy
`material is applied to both the inside and the outside of a
`portion of an EMI enclosure;
`0.026
`FIG. 3 is a more detailed drawing depicting the
`embodiment of the invention shown in FIG. 2A,
`0.027
`FIG. 4A is a schematic drawing of another alter
`native embodiment of the invention, in which a lossy
`material is applied to the outside portion of an EMI enclo
`Sure,
`0028 FIG. 4B is a schematic drawing of yet another
`alternative embodiment of the invention, in which a lossy
`material is applied to the inside portion of an EMI enclosure;
`0029 FIG. 4C is a schematic drawing of still another
`alternative embodiment of the invention, in which a lossy
`material is applied to both the inside and the outside of an
`EMI enclosure;
`
`0030 FIG. 5 is a schematic drawing of an embodiment
`of the invention, in which a lossy material is applied directly
`to an electronic component;
`0031
`FIG. 6 is a schematic drawing depicting one
`embodiment of the invention, in which a lossy material is
`applied to a first side of an EMI enclosure;
`0032 FIG. 7 is a graph representing test results compar
`ing the radiated emissions performance of one embodiment
`of the invention to a prior art shield.
`0033 FIG. 8 is a flow diagram depicting the steps of the
`embodiment of the invention shown in FIG. 2A,
`0034 FIG. 9A is a schematic drawing of a circuit board
`mountable embodiment of the invention;
`0035 FIG.9B is a schematic drawing of a tape and reel
`packaging configuration of the embodiment illustrated in
`FIG. 9A;
`0036 FIGS. 10A and 10B are schematic drawings of a
`two-piece circuit board mountable embodiment of the inven
`tion; and
`0037 FIGS. 10C and 10D are schematic drawing of a
`tape and reel packaging configuration of the embodiment
`illustrated in FIGS. 10A and 10B, respectively.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`0038 Lossy materials can be used to suppress EMI
`transmissions, for example, by converting the electromag
`netic energy into another form of energy, Such as thermal
`energy. The electromagnetic fields can induce electrical
`currents to flow within the lossy material having a finite
`electrical conductivity, resulting in ohmic losses. In one
`embodiment, the lossy material can be composed of ferrite
`like material mixed in an elastomer, Such as a resin binder.
`In other embodiments, the lossy material can be composed
`of a lossy filler material, Such as carbon powder mixed in an
`open-celled reticulated foam. The lossy materials can be
`configured in sheet form or in a liquid form for coating a
`Substrate. Some examples of lossy materials are electrically
`conductive material, carbon, iron, carbonyl iron powder,
`Sendust, ferrites, iron Silicide, magnetic alloys, magnetic
`flakes, steel wool, and combinations thereof. Other
`examples of lossy materials include carbon-impregnated
`rubber, ferrite in a plastic Stranded carrier, metal foils, metal
`clad materials including iron, nickel, and iron/nickel com
`positions, paste composites Selected from the group consist
`ing of iron, nickel, copper with epoxy, lacquer binders, and
`combinations thereof, and in combination with the previous
`exemplary lossy materials. Other materials used to achieve
`electromagnetic effects include alumina (Al2O), Sapphire,
`Silica (SiO2), titanium oxide (TiO), and combinations
`thereof.
`0039. In some embodiments, the lossy material can be
`combined with other materials to achieve a desired effect.
`For example, the lossy material can be combined with a fire
`retardant to meet Stringent flammability Standards. One Such
`flammability standard is the UL94VO vertical flame test,
`described in detail in Underwriter Laboratories Standard 94,
`entitled “Tests for Flammability of Plastic Materials for
`Parts in Devices and Appliances,” 5" Edition, 1996, the
`disclosure of which is incorporated herein by reference in its
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 017
`
`

`

`US 2004/0001299 A1
`
`Jan. 1, 2004
`
`entirety. In one embodiment, flame retardant additive is
`prepared in a particulate form and combined with a lossy
`material, Such as carbonyl iron powder whereby each addi
`tive is Suspended in a matrix, Such as an elastomer, or resin
`binder.
`0040 Various U.S. patents describe lossy materials and
`their uses. See, for example, U.S. Pat. No. 4,408,255 issued
`to Adkins, U.S. Pat. No. 5,689,275 issued to Moore et al.,
`U.S. Pat. No. 5,617,095 issued to Kim et al., and U.S. Pat.
`No. 5,428,506 issued to Brown et al., the disclosures of
`which are herein incorporated by reference in their entirety.
`Co-pending United States provisional patent application
`serial No. 60/419,873, filed on Oct. 21, 2002, the disclosure
`of which is incorporated herein by reference in its entirety,
`also describes lossy materials. Some manufactures of lossy
`materials are R&F Products of San Marcos, Calif.; ARC
`Technical Resources, Inc. of San Jose, Calif.; Tokin
`America, Inc. of Union City, Calif.; Intermark-USA, Inc. of
`Long Island City, N.Y.; TDK of Mount Prospect, Ill., Emer
`Son & Cuming Composite Materials, Inc., of Canton, Mass.;
`Cuming Corp. Microwave Products, of Avon, Mass.; and
`Capcon of Inwood, N.Y.
`0041 According to the present invention, EMI shielding
`can be added to newly fabricated or existing packages, or
`housings, for electronic components by applying a first,
`high-frequency, absorbing EMI material to a Second, reflect
`ing EMI material. The high frequency absorbing material
`includes a lossy material. In Some embodiments that lossy
`material is broadband in nature, absorbing EMI energy over
`a broad range of frequencies. The reflecting EMI material
`can be any of the EMI Shielding materials, Such as metals,
`including sheet metals currently used by those skilled in the
`art.
`0042. In one embodiment, the lossy material can be
`fabricated in a sheet and applied to at least a portion of a
`conductive EMI shield, Such as a metallic EMI shield.
`Alternatively, the lossy material can be applied as a sheet, or
`coating, during the course of manufacture. The lossy mate
`rials can be added to the interior, the exterior, or both the
`interior and exterior Surfaces of the EMI shield.
`0043 FIG. 2A shows one embodiment of an EMI shield
`configured as an EMI enclosure 99 including an absorbing
`material 102 applied to a reflecting material 100. In this
`embodiment, the absorbing, or lossy, material 102 is applied
`to at least a portion of the reflecting material 100 using an
`adhesive 104. The adhesive can be a curable adhesive, Such
`as an epoxy, or a non-curable adhesive, Such as a pressure
`Sensitive adhesive. The adhesive can be a conductive adhe
`Sive or a non-conducting adhesive.
`0044) The EMI enclosure 99 can include a highly-con
`ductive reflecting material 100, Such as aluminum, copper,
`nickel, tin, Silver, gold, beryllium, Steel, Stainless Steel, sheet
`metal, including compounds or combinations of different
`conducting materials, Such as nickel plated copper, phosphor
`bronze, tin plated steel, etc. The EMI enclosure 99 can also
`include an insulative material, Such as a plastic Suitably
`coated with an electrically conducting, or metallic layer
`Such metal-coated plastic applications are common in the
`packaging of Small, light-weight electronic devices.
`0045. The EMI enclosure 99 can be a substantially closed
`container, Such as a box, or a partially-open container, Such
`
`as a box or a cage having fewer than Six Sides. For example,
`the EMI enclosure 99 may include only five sides for
`applications in which the EMI enclosure 99 is installed onto
`another Surface, Such as a circuit board, Substrate, or con
`ductive enclosure. In Some applications, the EMI enclosure
`99 can be a plane, Such as a plate adapted for fastening to an
`electronic device. The EMI enclosure 99 can also include
`one or more apertures 106. The apertures, for example, can
`be useful for providing interconnections to any electronic
`components and/or devices disposed therein. Additionally,
`apertures can be useful for cooling, or even for cost and/or
`weight Savings for those applications in which a closed
`Surface is unnecessary.
`0046) The lossy material 102 can be selectively applied to
`the entire internal and/or external Surfaces of the EMI
`enclosure 99. Alternatively, the lossy material 102 can be
`Selectively applied to a portion of the internal and/or exter
`nal Surfaces. For example, in applications in which the
`electromagnetic energy has a preferred polarization, or in
`applications in which only a portion of the EMI enclosure 99
`is exposed to the EMI energy, the lossy material 102 can be
`applied in a limited manner, covering the most-Vulnerable
`(i