Abstract:
An apparatus for electromagnetic compatibility (EMC) shielding, the apparatus comprising a first EMC shield with a plurality of substantially parallel interconnected finger elements spaced apart from one another. A second EMC shield with a plurality of substantially parallel interconnected finger elements spaced apart from one another. The first EMC shield coupled to the second EMC shield, wherein at least one finger element of the plurality of finger elements of the first EMC shield is situated between at least two finger elements of the plurality of finger elements of the second EMC shield and in parallel with the at least two finger elements such that a space is formed between the at least one finger element and at least one of the at least two finger elements.

Description:
FIELD OF THE INVENTION 
       [0001]    This disclosure relates generally to electromagnetic compatibility shielding, and in particular, to decreasing the effects of electromagnetic interference on electronic components. 
       BACKGROUND 
       [0002]    For purposes of this disclosure, the term electromagnetic interference (EMI) is understood to refer to electromagnetic emission and radiation that includes both electromagnetic interference and radio-frequency interference (RFI). The term electromagnetic compatibility (EMC) is understood to refer to the ability to combat EMI through the shielding of electronic components which may be affected by EMI. 
         [0003]    Certain electronic parts, located primarily on circuits, radiate electromagnetic waves, which can cause noise (i.e., unwanted signals) to appear in other electronic components existing within a certain proximity of the radiating electronic parts. Accordingly, it is common to provide shielding and/or grounding for electronic components that use circuitry that emits electromagnetic radiation or for electronic components that are susceptible to electromagnetic radiation. Such shielding may be grounded to allow the electromagnetic radiation to be dissipated without disrupting the operation of the electronic components. 
         [0004]    One method for providing this shielding has been through a stamped metal shield having individual “fingers,” or elongated metal strips, typically made of a stainless steel. Such an EMC shield is also know as a “fingerstock” and is typically placed over an electronic component to reflect or contain EMI emissions. These fingers are formed around the electronic component to reduce undesirable EMI emission and/or effects of electromagnetic radiation. The spacing of each finger depends on the frequencies of the EMI waves. Typically, the higher the frequency that the EMC shield is designed to protect the electronic component from, the smaller the spacing between the fingers. Reducing the space between the fingers may also reduce the amount of unwanted emissions that may pass through the EMC shield from the components. 
         [0005]    To reduce the spacing between the fingers, a stamping tool used to manufacture the EMC shield has to be made smaller in order to achieve the smaller gap. As a result, life expectancy of the stamping tool decreases as the gap between the fingers of the EMC shield is made smaller. 
       SUMMARY 
       [0006]    One embodiment of the present invention provides an apparatus for electromagnetic compatibility (EMC) shielding comprising a first EMC shield with a plurality of substantially parallel interconnected finger elements spaced apart from one another. A second EMC shield with a plurality of substantially parallel interconnected finger elements spaced apart from one another. The first EMC shield coupled to the second EMC shield, wherein at least one finger element of the plurality of finger elements of the first EMC shield is situated between at least two finger elements of the plurality of finger elements of the second EMC shield and in parallel with the at least two finger elements such that a space is formed between the at least one finger element and at least one of the at least two finger elements. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0007]    The following detailed description, given by way of example and not intended to limit the disclosure solely thereto, will best be appreciated in conjunction with the accompanying drawings, in which: 
           [0008]      FIG. 1  depicts an isometric view of a multi-layered EMC shield in accordance with an embodiment of the present invention. 
           [0009]      FIG. 2  depicts an enlarged view of the isometric perspective of the multi-layered EMC shield of  FIG. 1 . 
           [0010]      FIG. 3  depicts a forward perspective of the multi-layered EMC shield of  FIG. 1 . 
           [0011]      FIG. 4  depicts an enlarged view of a side perspective of the multi-layered EMC shield of  FIG. 1 . 
           [0012]      FIG. 5  depicts an enlarged view of a top perspective of the multi-layered EMC shield of  FIG. 1 . 
           [0013]      FIG. 6  is a flowchart depicting the manufacturing steps of the multi-layered EMC shield of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Detailed embodiments of the present invention are disclosed herein with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely illustrative of potential embodiments of the invention and may take various forms. In addition, each of the examples given in connection with the various embodiments is also intended to be illustrative, and not restrictive. This description is intended to be interpreted merely as a representative basis for teaching one skilled in the art to variously employ the various aspects of the present disclosure. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments. 
         [0015]    In general, an electromagnetic compliant (EMC) shield may include one or more sides, each comprising a plurality of finger elements. The finger elements are separated sections, or tabs, of a shielding material that interconnect at one end and are free at another. These sections are arranged to reduce undesirable EMI emission and/or the effects of electromagnetic radiation. The EMC shield may be positioned on a mounting surface such that the finger elements on each of the one or more sides surround internal components and/or circuitry. The EMC shield may also be in electrical contact with the mounting surface. 
         [0016]    An exemplary embodiment of the present invention provides a multi-layered EMC shield, which is comprised of two or more EMC shields as described above, that interconnect. The orientation of the finger elements of the two or more EMC shields is such that, when the EMC shields are combined in a stacked formation, the finger elements point in the same direction and finger elements of one EMC shield are positioned in between finger elements of another EMC shield. In a preferred embodiment, the finger elements of the two or more EMC shields do not overlap. 
         [0017]      FIG. 1  depicts an isometric view of a multi-layered EMC shield  100  in accordance with an embodiment of the present invention. 
         [0018]    In an exemplary embodiment, multi-layered EMC shield  100  is comprised of two EMC shields (i.e., EMC top shield  102  and EMC bottom shield  104 ). Multi-layered EMC shields are not limited to only two EMC shields but can be comprised of two or more EMC shields. Multi-layered EMC shield  100  is preferably composed of a metal capable of reflecting electromagnetic interference (EMI) waves. In the preferred embodiment, EMC top shield  102  and EMC bottom shield  104  are mounted together in a manner so that apertures located on the top of multi-layered EMC shield  100  are aligned. The aligned apertures provide cooling to components that multi-layered EMC shield  100  is situated over. The size of the apertures can be based on the alignment of EMC top shield  102  with EMC bottom shield  104  and/or the size and shape of stamped apertures on the surface of the EMC top shield  102  and EMC bottom shield  104 . 
         [0019]    Top finger elements  106  are part of EMC top shield  102  and bottom finger elements  108  are part of EMC bottom shield  104 . When EMC top shield  102  is aligned with EMC bottom shield  104 , top finger elements  106  and bottom finger elements  108  align in an alternating matter. For example, in this embodiment no two finger elements situated next to each other are similar. When top finger elements  106  are aligned with bottom finger elements  108 , spacing  110  exists between every finger element. The size and positioning of the finger elements can be varied to adjust spacing  110  depending on the frequency of the electromagnetic interference (EMI) waves multi-layered EMC shield  100  is configured to protect against. A lower frequency EMI wave would require spacing  110  to be smaller. However, though a larger spacing  110  would protect only against higher frequency EMI waves, a larger spacing  110  would provide more cooling due to increased air flow. 
         [0020]      FIG. 2  depicts an enlarged view of the isometric perspective of the multi-layered EMC shield  100 .  FIG. 2  illustrates how every finger element of either top finger elements  106  or bottom finger elements  108  are respectively connected. Connecting every finger element in top finger element  106  and every finger element in bottom finger element  108  provides rigidity for the multi-layered EMC shield  100  thus providing a uniform spacing  110  between each finger element of the alternating top finger elements  106  and bottom finger element  108 . 
         [0021]      FIG. 3  depicts a forward perspective of multi-layered EMC shield  100 . As shown, EMC top shield  102  is coupled to EMC bottom shield  104  with top finger elements  106  aligning with bottom finger elements  108 . Top finger elements  106  and bottom finger elements  108  curve generally downward from where EMC top shield  102  is coupled to EMC bottom shield  104  to define a u-shaped top hook portion  302  and bottom hook portion  304  respectively. U-shaped top hook portion  302  and bottom hook portion  304  lead into top spring arm portion  306  and bottom spring arm portion  308  respectively. Due to the shape of top spring arm portion  306  and bottom spring arm portion  308 , both spring arms have the ability to be compressed in a spring like manner and to be attached to a designated mounting area. Upon attachment to the designated mounting area, top finger elements  106  and bottom finger elements  108  will be restrained or compressed such that a downward force is applied by top spring arm portion  306  and bottom spring arm portion  308  onto the mounting surface. This downward force will secure the multi-layered EMC shield  100  to the designated mounting surface. 
         [0022]    In one embodiment, a gasket may exist between multi-layered EMC shield  100  and a designated mounting surface to further provide a seal where EMI waves can not pass through. 
         [0023]      FIG. 4  depicts an enlarged view of a side perspective of multi-layered EMC shield  100 . As previously mentioned in the discussion of  FIG. 1 , top finger elements  106  and bottom finger elements  108  align in an alternating matter. 
         [0024]      FIG. 5  depicts an enlarged view of a top perspective of multi-layered EMC shield  100 . As previously mentioned in the discussion of the  FIG. 1 , the alignment of the apertures when EMC top shield  102  is mounted on EMC bottom shield  104  is dependent on the necessary ventilation for cooling of the components located beneath the multi-layered EMC shield  100 . 
         [0025]      FIG. 6  is a flowchart depicting the manufacturing steps of the multi-layered EMC shield  100 . As previously mentioned in the discussion of  FIG. 1 , multi-layered EMC shield  100  is comprised of EMC top shield  102  and EMC bottom shield  104 . 
         [0026]    An exemplary process for creating multi-layered EMC shield  100  initializes by constructing EMC top shield  102  (step  602 ). EMC top shield  102  may be constructed using a mold template to stamp a piece of metal into the shape of EMC top shield  102 . Stamping the piece of metal into the shape of EMC shield  102  will provide the clearly defined top finger elements  106 . Upon the completion of constructing EMC top shield  102 , the process calls for constructing EMC bottom shield  104  (step  604 ). Similar to the construction of EMC top shield  102 , a mold template may be used to stamp a piece of metal into the shape of EMC bottom shield  104  with clearly defined bottom finger elements  108 . Upon completion of construction of EMC top shield  102  and EMC bottom shield  104 , the process calls for coupling EMC top shield  102  to EMC bottom shield  104  (step  606 ). The process couples EMC top shield  102  to EMC bottom shield  104  such that top finger elements  106  do not overlap bottom finger elements  108 . Coupling EMC top shield  102  to EMC bottom shield  104  allows the tool used for stamping to be larger with a higher tolerance since spacing between each finger element of top finger elements  106  and the bottom finger elements  108 , is greater. The small spacing between each finger element, which could previously be achieved using a smaller, lower tolerance stamping tool, can now be achieved by coupling EMC top shield  102  to EMC bottom shield  104 . 
         [0027]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting to the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
         [0028]    Having described preferred embodiments of a multi-layered EMC shield (which are intended to be illustrative and not limiting), it is noted that modifications and variations may be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims.