PATENT DOCUMENT

Publication Number: US-8769811-B2
Application Number: US-61137609-A
Country: US
Kind Code: B2

Title: Method of shielding an electronic component from electromagnetic interference (EMI)

Abstract:
An electronic circuit component is provided with shielding for electromagnetic interference (“EMI”) by covering at least part of the component with a layer of electrical insulation that conforms to the shape of the surface to which the insulation is applied. At least part of the surface of the insulation is then covered by a layer of EMI shielding that conforms to the shape of the surface of the insulation to which the shielding is applied.

Claims:
The invention claimed is: 
     
       1. A method of shielding an electronic circuit component from an electromagnetic interference, the method comprising:
 applying a layer of electrical insulation to at least part of a surface of the electronic circuit component, the layer of electrical insulation conforming to the surface to which it is applied; 
 applying a layer of electromagnetic shielding to at least part of a surface of the layer of electrical insulation, the layer of electromagnetic shielding conforming to the surface to which it is applied, wherein the applying the layer of electrical insulation comprises:
 placing the component in a mold, the mold having an area that fits an end portion of a contact lead of the electronic circuit component so that the end portion of the contact lead is not overlapped by the layer of electrical insulation; and 
 injecting the layer of electrical insulation into the mold. 
 
 
     
     
       2. The method defined in  claim 1 , wherein the applying the layer of electrical insulation comprises:
 applying the electrical insulation in a fluid form to the at least part of the surface of the electronic circuit component; and 
 converting the electrical insulation to non-fluid form after it has conformed to the surface to which it is applied. 
 
     
     
       3. The method defined in  claim 1 , wherein the applying the layer of electromagnetic shielding comprises:
 applying the layer of electromagnetic shielding in a fluid form to the at least part of the surface of the insulation; and 
 converting the layer of electromagnetic shielding to non-fluid form after it has conformed to the surface to which it is applied. 
 
     
     
       4. The method defined in  claim 1 , wherein the applying the layer of electromagnetic shielding comprises:
 removing the electronic circuit component with the layer of electrical insulation as a subassembly from the mold; 
 placing the subassembly in a second mold; and 
 injecting the layer of electromagnetic shielding into the second mold. 
 
     
     
       5. The method defined in  claim 1 , wherein the applying the layer of electromagnetic shielding comprises:
 placing the electronic circuit component, to which the electrical insulation has been applied, in a mold; and 
 injecting the layer of electromagnetic shielding into the mold. 
 
     
     
       6. The method defined in  claim 1 , further comprising:
 prior to the applying the layer of electrical insulation, mounting the elctronic cirucit component on a supporting structure. 
 
     
     
       7. The method defined in  claim 6 , wherein the supporting structure comprises a printed circuit board. 
     
     
       8. A method of shielding an electronic circuit component from electromagnetic interference, the method comprising:
 applying a layer of electrical insulation to at least part of a surface of the electronic circuit component, the layer of electrical insulation conforming to the surface to which it is applied; 
 applying a layer of electromagnetic shielding to at least part of a surface of the layer of electrical insulation, the layer of electromagnetic shielding conforming to the surface to which it is applied; and 
 mounting the electronic circuit component with the layer of electrical insulation and the layer of electromagnetic shielding on a supporting structure, wherein the applying the layer of electrical insulation further comprises:
 placing the electronic circuit component in a mold, the mold having an area that fits an end portion of a contact lead of the electronic circuit component so that the end portion of the contact lead is not overlapped by the layer of electrical insulation; and 
 injecting the layer of electrical insulation into the mold. 
 
 
     
     
       9. The method defined in  claim 8 , wherein the supporting structure comprises a printed circuit board. 
     
     
       10. The method defined in  claim 8 , wherein the applying the layer of electromagnetic shielding comprises:
 removing the electronic circuit component and a printed subassembly from the mold; 
 placing the printed subassembly in a second mold; and 
 injecting the layer of electromagnetic shielding into the second mold. 
 
     
     
       11. The method defined in  claim 8 , wherein the applying the layer of electromagnetic shielding comprises:
 placing the component and the printed circuit board, to which the electrical insulation has been applied, in a mold; and 
 injecting the layer of electromagnetic shielding into the mold. 
 
     
     
       12. The method defined in  claim 6 , wherein the supporting structure includes a ground contact, wherein the applying the layer of electrical insulation leaves the ground contact uncovered by the electrical insulation, and wherein the applying the layer of electromagnetic shielding causes the electromagnetic shielding to reach the ground contact. 
     
     
       13. The method defined in  claim 8 , wherein the supporting structure includes a ground contact, and wherein the mounting comprises:
 electrically connecting the electromagnetic shielding to the ground contact. 
 
     
     
       14. The method defined in  claim 13 , wherein the applying the layer of electromagnetic shielding comprises:
 giving the electromagnetic shielding a projection that can be used to reach the ground contact. 
 
     
     
       15. The method defined in  claim 6 , wherein the applying the layer of electrical insulation further comprises filling a spacing between the electronic circuit component and an adjacent electronic circuit component on the support structure with the layer of electrical insulation. 
     
     
       16. The method defined in  claim 1 , wherein the applying the layer of electrical insulation comprises contacting a solder area with the layer of electrical insulation, the solder area coupling the electronic circuit component to a supporting structure. 
     
     
       17. The method defined in  claim 1 , wherein the applying the layer of electromagnetic shielding comprises forming a layer of electromagnetic shielding extension overlapping a solder area, the solder area coupling the electronic circuit component to a supporting structure. 
     
     
       18. The method defined in  claim 1 , wherein the applying the layer of electrical insulation comprises forming an insulation portion overlapping an inner portion of an electrical lead coupled to the electronic circuit component. 
     
     
       19. The method defined in  claim 8 , further comprising:
 mounting a second electronic circuit component on the supporting structure adjacent to the electronic circuit component, wherein 
 the applying the layer of electrical insulation further comprises filling a spacing between the electronic circuit component and the second electronic circuit component.

Description:
This application claims the benefit of U.S. provisional patent application 61/072,640, filed Mar. 31, 2008, which is hereby incorporated by reference herein. This is a division of application Ser. No. 12/214,682, filed Jun. 19, 2008, now U.S. Pat. No. 7,633,015 which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to electronic circuitry, and more particularly to shielding that may be used around such circuitry to reduce electro-magnetic radiation from or to such circuitry (so-called electromagnetic interference or EMI). 
     A traditional way to reduce EMI for electronic circuitry is to place electrically conducting (typically metal) shielding around the circuitry, which shielding is connected to electrical ground (i.e., a source of electrical ground potential or voltage). For example, several electronic circuit components that have been mounted on a printed circuit board (“PCB”) may be placed under a metal cover or inside a metal container (“can”). A layer of electrical insulation may be included between the circuit components and this metal shielding to ensure that the shielding cannot cause any short circuits in the electronic circuitry by making electrical contact with that circuitry. 
     A possible problem with the foregoing approach is that the metal shielding is typically fabricated in advance with a predetermined size and shape, which size and shape the shielding retains after the shielding has been combined with the electronic circuitry to be shielded. This means that because of manufacturing tolerances for (1) the electronic circuitry, (2) the shielding, and (3) any insulation used between the circuitry and the shielding, the shielding must be made significantly larger than the theoretical minimum size the shielding could have. Such results are inconsistent with the need to make many types of electronic devices as small as possible. 
     SUMMARY OF THE INVENTION 
     In accordance with certain possible aspects of this invention, an electronic component may be shielded by at least partly covering it with a layer of electrical insulation that conforms to the shape of the surface of the electronic component to which the insulation is applied. The electrical insulation is then at least partly covered by a layer of EMI shielding that conforms to the shape of the surface of the insulation to which the EMI shielding is applied. 
     Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified plan view of some illustrative prior art electronic circuitry. 
         FIG. 2  is a simplified elevational view (partly in section along a line like  2 - 2  in  FIG. 1 ) of circuitry like that shown in  FIG. 1  with other conventional elements added. 
         FIG. 3  is a simplified elevational view taken along a line like  3 - 3  in  FIG. 1 , but with some possible additional features shown. 
         FIG. 4  is similar to  FIG. 3 , but shows a later stage in processing what is shown in  FIG. 3 . 
         FIG. 5  is again similar to  FIG. 4 , but shows a still later stage in processing what is shown in  FIG. 4 . 
         FIG. 6  is a simplified elevational view taken along the line  6 - 6  in  FIG. 5 . 
         FIG. 7  is a simplified elevational view, partly in section, of an illustrative embodiment of apparatus in accordance with the present invention. 
         FIG. 8  is a simplified plan view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 9  is a simplified sectional view taken along the line  9 - 9  in  FIG. 8 . 
         FIG. 10  is a view similar to  FIG. 9  showing an illustrative embodiment of a later stage in use of the apparatus of  FIGS. 8 and 9  in accordance with the invention. 
         FIG. 11  is a simplified plan view showing an illustrative embodiment of an intermediate stage in use of the apparatus of  FIGS. 8 and 9  in accordance with the invention. 
         FIG. 12  is a view similar to  FIG. 8  for another illustrative embodiment in accordance with the invention. 
         FIG. 13  is a simplified sectional view taken along the line  13 - 13  in  FIG. 12 . 
         FIG. 14  is a simplified elevational view, partly in section, of an illustrative embodiment of apparatus inside processing apparatus in accordance with the invention. 
         FIG. 15  is a simplified sectional view taken along the line  15 - 15  in  FIG. 14 . (Sectional portions of  FIG. 14  are taken along the line  14 - 14  in  FIG. 15 .) 
         FIG. 16  is similar to  FIG. 15  for later stage apparatus inside later stage processing apparatus in accordance with the invention. 
         FIG. 17  is generally similar to  FIG. 15 , but for other illustrative apparatus and processing apparatus in accordance with the invention. 
         FIG. 18  is generally similar to  FIG. 16 , but for later stage apparatus and processing apparatus that may follow what is shown in  FIG. 17  in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative prior art electronic circuitry  10  is shown in  FIG. 1  by way of additional background. Circuitry  10  includes a sheet  20  of printed circuit board (“PCB”) material on which several electronic circuit components  30   a - d  are mounted. (As used herein, the term PCB includes all forms of this general type of element, such as flexible printed circuit, “flex”, or “FPC” material.) Each of components  30  is shown as having two electrically conductive leads  32  extending from it. This is only an example, and a component can have any number of such leads. Moreover, these leads can have any of a variety of shapes, as well as any of a variety of locations relative to the remainder of the associated component  30 . In the particular example shown in  FIG. 1 , leads  32  are shown as being intended for soldering to the upper surface of PCB  20  (e.g., to solder paste areas on that surface (see also later-described  FIG. 3 )).  FIG. 1  also shows electrical ground contacts  40  on the upper surface of PCB  20 .  FIG. 1  shows circuitry  10  before any solder or any EMI shielding structure has been added to it. 
       FIG. 2  shows a structure like that shown in  FIG. 1  from a line approximately like that indicated at  2 - 2  in  FIG. 1 . However,  FIG. 2  shows the structure after addition of EMI shielding  50  of a prior art kind.  FIG. 2  shows this shielding  50  and some associated electrical insulation  60  in section (taken along a line like  2 - 2  in  FIG. 1 ), but  FIG. 2  is otherwise primarily an elevational view. 
       FIG. 2  shows the placement of a metal cover  50  over components  30  and a portion of PCB  20 . To ensure that metal cover  50  cannot cause a short circuit in the circuitry that it covers, a layer of electrical insulation  60  is provided between cover  50  and the underlying circuitry  30 , etc. Cover  50  is electrically connected to ground contacts  40  on PCB  20 . For example, cover  50  may be soldered to these ground contacts. Accordingly, cover  50  provides EMI shielding for the electronic circuit components  30  under or inside that cover. 
       FIG. 3  shows a structure like that shown in  FIG. 1 , but from another direction (i.e., along the line  3 - 3  in  FIG. 1 ).  FIG. 3  shows a typical electronic circuit component  30  on solder paste regions  34  prior to soldering of component  30  to PCB  20  (i.e., prior to so-called reflow).  FIG. 3  shows additional ground contacts  40  beyond paste regions  34 . 
       FIG. 4  shows the  FIG. 3  structure again, but after reflow. As shown in  FIG. 4 , solder areas  36  now exist at the location of each solder paste region  34  in  FIG. 3 . Like  FIG. 1 ,  FIGS. 3 and 4  show the structure before any EMI shielding structure has been added. 
       FIG. 5  shows the  FIG. 4  structure after addition of conventional insulation  60  and EMI shielding  50  of the type shown in  FIG. 2 .  FIG. 6  shows how the lower edge of EMI shielding  50  may be scalloped or crenellated so that it can contact a plurality of spaced ground contacts  40 , while jumping over other circuitry (e.g., electrical circuit traces on PCB  20 ) between those contacts  40 . 
     Note that in the prior art construction that is illustrated by  FIGS. 2 and 5 , EMI shielding  50  has a predetermined size and shape that is basically independent of the size and shape of the circuit components  30  covered by that shielding. Moreover, shielding  50  holds that predetermined size and shape after it has been applied over components  30  and their ancillary electrical features like  32  and  36 . Note also that shielding  50  is typically manufactured separately from the elements over which it is applied, and then this prefabricated shielding structure is added over the underlying electrical circuitry. 
     Because of tolerances required in manufacturing components  30  and related features  32  and  36 , as well as tolerances required in separately manufacturing shielding  50  (and possibly also insulation  60 ), shielding  50  must be made so that (at a minimum) its interior is larger than (at a maximum) the exterior of the underlying circuitry. This typically means that shielding  50  effectively increases the size of the finished structure by a significant amount (as compared to the size of the underlying circuitry (e.g.,  30 ,  32 , and  36 )). This may be undesirable in contexts in which an objective is to keep electronic circuit structures as small as possible. 
       FIG. 7  shows an illustrative embodiment of how electronic circuitry components  30 , mounted on a PCB  20  as shown in FIGS. like  1 ,  3 , and  4 , may be shielded more compactly than in prior art such as  FIGS. 2 ,  5 , and  6 . In particular,  FIG. 7  shows a starting structure like that shown in  FIG. 4 . Then a layer of conforming electrical insulation  160  is applied over the  FIG. 4  structure except for ground contacts  40 . Thereafter, a layer of conforming, electrically conducting, EMI shielding  150  is applied over insulation  160  so that the EMI shielding reaches and makes contact with ground contacts  40 . 
     The term “conforming” as used herein with reference to insulation  160  and EMI shielding  150  means that each of these layers follows, contacts, and preferably also adheres to the surface to which it is applied. For example, insulation  160  lays down on and intimately and extensively contacts the surface(s) of elements  30 ,  36 , etc., to which it is applied. Insulation  160  also preferably adheres to those surfaces. Insulation  160  is preferably applied with enough thickness to ensure good electrical insulation to elements  30 ,  36 , etc., but also preferably not with greatly more thickness than is sufficient for that purpose. Insulation  160  can be applied in a liquid or at least a flowable fluid state. For example, insulation  160  can be an epoxy resin (e.g., a potting compound) or a polymer (e.g., silicone rubber) that is brushed on over elements  30 ,  36 , etc., or otherwise flowed on over those elements while in a liquid or at least flowable state. After insulation  160  has been applied, it is converted to a non-fluid, non-flowable state. For example, resin or polymer insulation  160  may be cured (e.g., by time, temperature, and/or a chemical atmosphere) to render it non-fluid and therefore non-flowable. Such curing may make insulating layer  160  hard, or it may still remain somewhat flexible. 
     As another example of how conforming insulation  160  may be applied, shrink-wrap type materials and procedures may be used for that purpose. Thus, for example, a sheet of shrink-wrappable insulating material may be placed over elements  30 ,  36 , etc. Then that material may be subjected to the conditions that cause it to shrink-wrap down into much more complete, conforming contact with the surfaces of the elements  30 ,  36 , etc., over which it has been placed. For example, these conditions may be heat, a chemical environment, or anything else that activates the shrink-wrap properties of material  160 . This causes insulation  160  to become conforming with (and also preferably to adhere to) the surfaces of elements  30 ,  36 , etc., that it has been placed over. Such activation of the shrink-wrap properties of material  160  is a form of curing of that material, and it is embraced within the term curing (or the like) as that term is used herein. 
     After application of insulating layer  160  has been completed, EMI shielding layer  150  is applied over the insulation in a generally similar way. Thus shielding layer  150  is again a layer that conforms to the surfaces to which it is applied (in this case the exposed surface of insulation  160 , ground contacts  40 , etc.). Shielding layer  150  is again applied with sufficient thickness to enable it to perform its EMI shielding function, but preferably not with greatly more thickness than that. As a conforming layer, shielding layer  150  again follows and contacts (and also preferably adheres to) the surfaces to which it is applied. Application techniques like those described above for layer  160  may be used again for layer  150  (employing, of course, an electrically conducting material rather than an electrically insulating material). Thus, for example, an epoxy or polymer material that is loaded with metal particles may be deposited on the surfaces below in a liquid or at least a flowable fluid state. This may be done by brushing or otherwise flowing this material ( 150 ) on over the surfaces below. Then material  150  is converted to a non-fluid, non-flowable state. For example, the material of layer  150  may be cured (which may leave it hard or still flexible to some degree) as described above for layer  160 . As another example, material  150  may be a shrink-wrappable sheet material. Such a sheet is placed over the surfaces to be shielded, and then the shrink-wrap properties of the material may be activated to cause it to conform to (i.e., to contact, follow, and preferably adhere to) all portions of the surfaces to which it has been applied. 
       FIG. 7  of course shows the conforming nature of each of layers  160  and  150  in the finished structure  10 . Thus insulating layer  160  follows, contacts, and preferably adheres to all portions of the surfaces below it (e.g., the upper surfaces of elements  30 ,  36 , etc.). Similarly, EMI shielding layer  150  follows, contacts, and preferably adheres to all portions of the surfaces below it (e.g., the upper surfaces of elements  160 ,  40 , etc.). Especially of note is the fact that layer  150  makes good electrical contact with ground contacts  40  and provides an electrically continuous, electrically conductive cover over all elements below it. Layer  150  therefore provides EMI shielding for the circuitry covered by it. 
     Because elements  160  and  150  conform to the size and shape of the elements  30 ,  36 , etc., that they cover, the resulting product (e.g., as in  FIG. 7 ) can be smaller than prior art structures like  FIGS. 2 and 5 . The final product can have nearly the same size and shape as the underlying electronic circuitry, increased only by the thickness of layers  160  and  150 . 
       FIGS. 8-10  illustrate an alternative embodiment of the invention in which one or more electronic circuit components are pre-shielded using the invention prior to being mounted on a substrate such as a PCB. Thus  FIGS. 8 and 9  show elements  30   a - d  assembled side-by-side, and covered with conforming insulation  160  and conforming EMI shielding  150  before being mounted on a PCB.  FIG. 10  then shows the assembly  200  of  FIGS. 8 and 9  (which assembly  200  may be referred to as a pre-shielded custom component pack) mounted on PCB  20 . These FIGS. will now be described in more detail. 
     In  FIGS. 8 and 9 , four electronic circuit components  30   a - d  (which can be like the similarly numbered elements in  FIG. 1 ) are assembled side-by-side, with their leads  32  projecting from opposite sides of the assembly. A layer of conforming insulation  160  is then applied over the above-mentioned assembly (except for the outer-most portions of leads  32  and the underside of the assembly). Note that insulation  160  preferably does cover the inner-most portion of leads  32  as at  162  (but, again, not any portion of the lower surface of those leads). After insulation  160  has been applied (and cured, if necessary), a layer of conforming EMI shielding  150  is applied over most of insulation  160 . Note that the insulation  162  on the inner portions of leads  32  prevents shielding  150  from making electrical contact with leads  32 . Note also that shielding  150  is caused or allowed to form outward extensions  152  that can be used to reach ground contacts when assembly  200  is later mounted on a substructure such as a PCB. After shielding  150  has been applied, it is cured if necessary. Assembly  200  is now complete and ready for mounting on a substructure such as a PCB at any time. Such mounting is illustrated by  FIG. 10 , which will now be described. 
       FIG. 10  shows assembly  200  from  FIGS. 8 and 9  mounted on PCB  20 . A solder paste area  34  is disposed on PCB  20  where each contact  32  will come down on the PCB. Solder  36  is then applied to permanently electrically and mechanically connect the exposed outer end portion of each lead  32  to electrical circuitry on the PCB. The same is done to connect each of shielding tabs  152  to a ground contact on the PCB. See also  FIG. 11 , which shows a plan view of what is shown in  FIG. 10  prior to the addition of solder  36 . Thus  FIG. 11  shows that there is a solder paste area  34  under each of leads  32 , and also under each of EMI shielding extensions  152 . Solder  36  (e.g., as in  FIG. 10 ) is added over each of these solder paste areas  34  to connect the associated feature  32  or  152  of assembly  200  to circuitry on PCB  20 . 
       FIGS. 12 and 13  show an alternative embodiment in which there is some spacing between electronic circuit components  30   a - d  in pre-shielded custom component pack  200 ′. In this embodiment the spacing between components  30  is filled by conforming insulation material  160 . In all other respects assembly  200 ′ may be similar to assembly  200 . 
     Any of the materials mentioned earlier for insulation  160  can be used again for the insulation  160  in embodiments like those illustrated by  FIGS. 8-13 . Also, the above-described techniques for applying (and, if necessary, curing) insulation  160  can be used again for the insulation  160  in embodiments like those illustrated by  FIGS. 8-13 . The same is true for EMI shielding  150  in embodiments like  FIGS. 8-13  (i.e., any of the earlier-described EMI shielding  150  materials, application techniques, and/or curing techniques (if necessary) can be used again for the EMI shielding  150  in embodiments like  FIGS. 8-13 ). 
     Alternative techniques for applying conforming insulation  160  and/or conforming EMI shielding  150  are illustrated by  FIG. 14  and several subsequent FIGS. These alternative techniques involve molding insulation  160  and/or shielding  150  around the structure(s) to be insulated and/or shielded.  FIGS. 14 and 15  begin the illustration of these techniques by showing an example of molding insulation  160  for a structure otherwise similar to what is shown in  FIGS. 8 and 9 . Thus in  FIGS. 14 and 15  elements  30   a - d  and  32  are repeated from  FIGS. 8 and 9 . 
       FIGS. 14 and 15  show elements  30 / 32  placed inside a two-part mold structure  300   a - b , which may be part of an injection molding machine. In particular, elements  30   a - d  and  32  rest on lower mold part  300   a , which contacts and covers the undersides of those elements. Upper mold part  300   b  is then placed over elements  30   a - b ,  32 , and  300   a . Upper mold part  300   b  peripherally sealingly contacts lower mold part  300   a , except where one or more openings like  302  may be left for injection of insulation  160  into the mold and/or for venting gas from the mold cavity. Upper mold part  300   b  leaves a space (cavity)  304  between its inner surface and all surfaces of assembly  30 / 32  that are to be coated with insulation  160 . Note that upper mold part  300   b  does not leave such space around the outer-most end portions of leads  32 . Thus in areas like  306 , upper mold part  300   b  fits closely around the outer end portions of leads  32 . However, space  304  does extend to around the inner portions of leads  32  as shown, for example, at  308 . 
     When elements  30 / 32  are positioned in mold  300   a - b  as shown in  FIGS. 14 and 15 , insulation material  160  in a flowable fluid condition is injected (under pressure) into the space  304 / 308  around those elements as indicated by the arrow  310  in  FIG. 14 . This causes insulation  160  to completely fill space  304 / 308  and conform to (and preferably also adhere to) all surfaces of elements  30 / 32  that were previously exposed to space  304 / 308 . 
     After insulation  160  has cured sufficiently (assuming that such curing is required), mold  300   a - b  can be opened (by separating parts  300   a  and  300   b  from one another), and subassembly  30 / 32 / 160  can be removed. Conforming EMI shielding  150  can now be added to this subassembly using any of the techniques described earlier, or alternatively using a further molding step as illustrated by  FIG. 16 , as will now be described. 
     As shown in  FIG. 16 , the subassembly of elements  30 / 32 / 160  that comes out of molding process  300   a - b  is placed in two-part mold  320   a - b , which can be part of another injection molding machine. In particular, subassembly  30 / 32 / 160  is placed on lower mold part  320   a , which again is shaped to cover the undersides of elements  30  and  32 . Upper mold part  320   b  fits down over subassembly  30 / 32 / 160  and seals to lower mold part  320   a  all around subassembly  30 / 32 / 160 , except for where apertures may be left for such purposes as injecting EMI shielding material  150  into the mold or allowing venting from the mold. The inner surface of upper mold part  320   b  leaves a space (cavity)  324  between that surface and any part of subassembly  30 / 32 / 160  that it is desired to cover with shielding  150 . The inner surface of upper mold part  320   b  may also leave a similar space between that surface and lower part  320   a  where it is desired for shielding  150  to also form projections  152  for connection to ground contacts on another structure like PCB  20 . 
     Note that upper mold part  320   b  is shaped (e.g., at  326 ) to fit snugly around outer portions of the insulation  162  that covers the inner portions of leads  32 . This keeps the shielding material  150  that is injected into cavity  324  from making contact with any of leads  32 . 
     When subassembly  30 / 32 / 160  is in mold  320   a - b  as shown in  FIG. 16 , EMI shielding material  150  in a flowable fluid state is injected (under pressure) into the space  324  that is left in the mold around selected parts of subassembly  30 / 32 / 160  as shown in  FIG. 16  and described above. This causes shielding material  150  to fill space  324 , whereby it conforms to (and preferably also adheres to) the portions of subassembly  30 / 32 / 160  that it is desired to shield. After shielding material  150  has cured sufficiently (assuming that such curing is necessary), the two parts of mold  320   a - b  can be separated, and finished assembly  30 / 32 / 160 / 150  can be removed. It will be appreciated that this assembly can look very much like assembly  200  in  FIGS. 8 and 9 , and that it can be used in the same way that assembly  200  can be used. 
     The molding alternatives illustrated by  FIGS. 14-16  can be used for either insulation  160 , or for shielding  150 , or for both insulation  160  and shielding  150 . Molding may allow (or at least facilitate) the use of different materials for insulation  160  and/or shielding  150  than would otherwise be possible (or at least easy) to use. For example, molding may allow the use of molten metal (e.g., molten silver) for shielding  150 . As another example, molding may allow the use of certain plastics or rubbers for insulation  160  that it would otherwise be difficult or impossible to use. Molding may allow (or at least facilitate) more precise control of where insulation  160  and/or shielding  150  is deposited on underlying structures. For example, precise shaping of the insulation  162  around certain portions of leads  32  may be facilitated by molding insulation  160 . Similarly, ensuring that shielding  150  does not extend beyond the outer ends of insulation portions  162  may be facilitated by molding shielding  150 . Molding may also help to ensure that the molded layer or layers  160  and/or  150  have the desired thickness at all locations on the underlying structure(s). Molding does not alter the fact that the molded layer or layers  160  and/or  150  are “conforming” as that term is defined above. 
       FIG. 17  illustrates the point that molding techniques like those described above can also be applied to circuit components that have already been mounted on a substructure such as a PCB.  FIG. 17  therefore shows a subassembly like that shown in  FIG. 7  (but without insulation  160  or shielding  150 ). This subassembly is placed in a two-part mold  340   a - b  that is shaped for application of insulating material  160  to desired parts of the subassembly. The resulting further subassembly (now with insulation  160 ) can then be placed in further molding apparatus  360   a - b  as shown in  FIG. 18  for application of shielding material  150  to that further subassembly. The resulting final assembly will be similar to what is shown in  FIG. 7 , except that layers  150  and  160  will have been applied by molding rather than by other means. 
     Briefly recapitulating and in some respects extending some of the foregoing, electronic components on printed circuit boards may produce electromagnetic interference (“EMI”) that can affect the performance of nearby electronic systems. This “noise” can affect not just products outside the mechanical envelope, but systems inside the product as well. To assist in blocking the noise emitted by a component, such components are often covered by a thin-walled metal can. This can is then soldered to the printed circuit board and connected to ground planes within the board. 
     The above-mentioned cans can be large and bulky compared to the components they cover. These cans can also require insulation layers and large flat areas to which to attach. What is needed is a method for producing smaller EMI-blocking features to allow space inside an enclosure to be better utilized. The present invention addresses such a need. 
     For example, a circuit board that has completed SMT (wherein electronic components are soldered to the board) can be placed in a custom mold (e.g.,  340   a - b ) into which insulating potting material  160  or the like is injected to produce a thin covering of electrical insulation over the board and the components to be shielded. Once cooled or otherwise cured (if necessary), the board is removed from this first mold and placed in a second mold (e.g.,  360   a - b ) into which silver or other appropriate metal or material is injected to produce a thin, electrically conducting coating over the potting or other insulating material. In a final (optional) stage, the part may be painted with a spray coating. 
     If desired, the final stage mentioned immediately above may be omitted and the metal or other EMI shielding layer may be molded with additional mechanical features for such purposes as to provide rigidity, electrical contact, heat transfer, etc. As another possible alternative, the immediately above-mentioned final stage can use a third mold to inject plastic over the EMI shielding. This plastic can have additional features molded in to serve other mechanical needs. 
     It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the number, shapes, sizes, etc., of the components  30  to which the invention is applied can be different from what is shown in the drawings herein, which are intended to be only generally illustrative of what can be done.

Metadata:
Filing Date: 20091103
Publication Date: 20140708
Grant Date: 20140708
Priority Date: 20080331
Inventors: WURZEL JOSH
GETTEMY SHAWN ROBERT
AL-DAHLE AHMAD
VIERI CARLIN JAMES
YAO WEI
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K3/284", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49144", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/09872", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/0024", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/10689", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/552", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49128", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10689", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/0024", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49117", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49128", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49144", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49146", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T156/1052", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/4913", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T156/1052", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/09872", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/4913", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49117", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/552", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K9/0084", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 41116904