WO2014145594A1 - Canaux formés fournissant un blindage électromagnétique dans des enveloppes électroniques - Google Patents

Canaux formés fournissant un blindage électromagnétique dans des enveloppes électroniques Download PDF

Info

Publication number
WO2014145594A1
WO2014145594A1 PCT/US2014/030388 US2014030388W WO2014145594A1 WO 2014145594 A1 WO2014145594 A1 WO 2014145594A1 US 2014030388 W US2014030388 W US 2014030388W WO 2014145594 A1 WO2014145594 A1 WO 2014145594A1
Authority
WO
WIPO (PCT)
Prior art keywords
semi
box
elliptic
enclosure
cylinder
Prior art date
Application number
PCT/US2014/030388
Other languages
English (en)
Inventor
Paul Douglas Cochrane
Original Assignee
Stealthdrive, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stealthdrive, Inc. filed Critical Stealthdrive, Inc.
Priority to US14/899,227 priority Critical patent/US20160174420A1/en
Publication of WO2014145594A1 publication Critical patent/WO2014145594A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0007—Casings
    • H05K9/0009—Casings with provisions to reduce EMI leakage through the joining parts

Definitions

  • shielding always adds cost and weight, so it is always best to use the other techniques described in this series to improve EMC and reduce the need for shielding. Even when it is hoped to avoid shielding altogether, it is best to allow for Murphy's Law and design from the very conception so that shielding can be added later if necessary. A degree of shielding can also be achieved by keeping all conductors and components very close to a solid metal sheet. Ground-planed PCBs populated entirely by low-profile surface mounted devices are therefore are recommended for their EMC advantages.
  • a useful degree of shielding can be achieved in electronic assemblies firstly, by keeping their internal electronic units and cables very close to an earthed metal surface at all times, and secondly, by bonding their earths directly to the metal surface instead of (or as well as) using a safety star earthing system based on green/yellow wires.
  • This technique usually uses zinc-plated mounting plates or chassis, and can help avoid the need for high values of enclosure SE.
  • a shield puts an impedance discontinuity in the path of a propagating radiated electromagnetic wave, reflecting it and/or absorbing it. This is conceptually very similar to the way in which filters work-they put an impedance discontinuity in the path of an unwanted conducted signal.
  • [8.]lt is generally best to allow a large distance between the circuits that are shielded and the walls of their shield.
  • the emitted fields outside of the shield, and the fields that the devices are subjected to, will generally be more "diluted" the larger the shielded volume.
  • Electromagnetic fields consist of E and M fields in a given ratio (giving a wave impedance E/M of 377 in air). Electric fields are easily stopped by thin metal foils since the mechanism for electric field shielding is one of charge re-distribution at a conductive boundary; therefore, almost anything with a high conductivity (low resistance) will present suitably low impedance. At high frequencies, considerable displacement currents can result from the rapid rate of charge re-distribution, but even thin aluminium can manage this well. However, magnetic fields are much more difficult to stop. They need to generate eddy currents inside the shield material to create magnetic fields that oppose the impinging field. Thin aluminium is not going to be very suitable for this purpose, and the depth of current penetration required for a given SE depends on the frequency of the field. The SE also depends on the characteristics of the metal used for the shield which is known as the "skin effect".
  • An actual SE in practice will depend on internal resonances between the walls of the enclosure itself, the proximity of components and conductors to apertures (keep noisy cables such as ribbon cables carrying digital busses well away from shield apertures and joints) and the impedances of the fixings used to assemble the parts of the enclosure, etc.
  • an SE will vary strongly with the method and quality of assembly, materials, and internal PCBs and cables, it is always best to allow an SE ' safety margin ' of 20 dB. It may also be advantageous to at least include design-in features that will allow improvement of the SE by at least 20 dB if there are problems with the final design's verification/qualification testing.
  • All metals shield materials with relative permeability greater than 1 can saturate in intense magnetic fields, and then don't work well as shields and often heat up.
  • a steel or Mumetal shield box over a mains transformer to reduce its hum fields can saturate and fail to achieve the desired effect. Often, this is all that is necessary to make the box larger so it does not experience such intense local fields.
  • Another shielding technique for low frequency shielding is active cancellation, and at least two companies have developed this technique specifically for stabilizing the images of CRT VDUs in environments polluted by high levels of power frequency magnetic fields.
  • FIG. 1 D shows that if we extend the distance that a wave leaking through an aperture has to travel between surrounding metal walls before it reaches freedom, we can achieve respectable SEs even though the apertures may be large enough to put a fist through.
  • This very powerful technique is called "waveguide below cut-off".
  • Honeycomb metal constructions are really a number of waveguides below cut-off stacked side-by-side, and are often used as ventilation grilles for shielded rooms, similar to high-SE enclosures.
  • a waveguide allows all its impinging fields to pass through when its internal diagonal (g) is half a wavelength.
  • a waveguide does not leak like an ordinary aperture (as shown by FIG. 1 A) and can provide a great deal of shielding: for f ⁇ 0.5f.sub. cutoff SE is approximately 27 d/g where d is the distance through the waveguide the wave has to travel before it is free.
  • FIG. 1A shows examples of the SE achieved by six different sizes of waveguides below cut-off. Smaller diameter (g) results in a higher cut-off frequency, with a 50 mm (2 inch) diameter achieving full attenuation by 1 GHz. Increased depth (d) results in increased SE, with very high values being readily achieved.
  • Waveguides below cut-off do not have to be made out of tubes, and can be realized using simple sheet metalwork which folds the depth (d) so as not to increase the size of the product by much. As a technique, it is only limited by the imagination, but it must be taken into consideration early in a project as it is usually difficult to retro-fit to a failing product .not intended for use. Conductors should never be passed through waveguides below cut-off, as this compromises their effectiveness. Waveguides below cut-off can be usefully applied to plastic shafts (e.g. control knobs) so that they do not compromise the SE where they exit an enclosure. The alternative is to use metal shafts with a circular conductive gasket and suffer the resulting friction and wear. Waveguides below cut-off can avoid the need for continuous strips of gasket, and/or for multiple fixings, and thus save material costs and assembly times.
  • Gaskets are used to prevent leaky apertures at joints, seams, doors and removable panels.
  • gasket design is not too difficult, but doors, hatches, covers, and other removable panels create many problems for gaskets, as they must meet a number of conflicting mechanical and electrical requirements, not to mention chemical requirements (to prevent corrosion). Shielding gaskets are sometimes required to be environmental seals as well, adding to the compromise.
  • FIG. 1 B shows a typical gasket design for the door of an industrial cabinet, using a conductive rubber or silicone compound to provide an environmental seal as well as an EMC shield. Spring fingers are often used in such applications as well.
  • Conductively wrapped polymers polymer foam or tube with a conductive outer coating can be very soft and flexible, with a low compression set. Some only need low levels of contact pressure. However, they may not make the best environmental seals and their conductive layer may be vulnerable to wear.
  • Metal meshes random or knitted are generally very stiff but match the impedance of metal enclosures better and so have better SEs than the above types. They have poor environmental sealing performance, but some are now supplied bonded to an environmental seal, so that two types of gaskets may be applied in one operation.
  • Spring fingers are usually made of beryllium copper or stainless steel and can be very compliant. Their greatest use is on modules (and doors) which must be easy to manually extract (open), easy to insert (close), and which have a high level of use. Their wiping contact action helps to achieve a good bond, and their impedance match to metal enclosures is good, but when they don't apply high pressures, maintenance may be required (possibly a smear of petroleum jelly every few years). Spring fingers are also more vulnerable to accidental damage, such as getting caught in a coat sleeve and bending or snapping off. The dimensions of spring fingers and the gaps between them causes inductance, so for high frequencies or critical use a double row may be required, such as can be seen on the doors of most EMC test chambers.
  • FIG. 1 C shows a large aperture in the wall of the shielded enclosure, using an internal "dirty box” to control the field leakage through the aperture.
  • the joint between the dirty box and the inside of the enclosure wall must be treated the same as any other joint in the shield.
  • the mesh size must be small enough not to reduce the enclosure's SE too much.
  • mesh size will be considerably smaller than one aperture on its own would need to be for the same SE.
  • this crude "6 dB per doubling" formula can lead to over-engineering, but no simple rule of thumb exists for this situation.
  • Honeycomb metal ventilation shields consisting of many long narrow hexagonal tubes bonded side-by-side have been used for this purpose for many years. It is believed that at least one manufacturer of highly shielded 19" rack cabinets claims to use waveguide below cut-off shielding for the top and bottom ventilation apertures that use ordinary sheet metalwork techniques.
  • Volume-conductive plastics or resins generally use distributed conductive particles or threads in an insulating binder which provides mechanical strength. Sometimes these suffer from forming a "skin" of the basic plastic or resin, making it difficult to achieve good RF bonds without helicoil inserts or similar means. These insulating skins make it difficult to prevent long apertures which are created at the joints, and also make it difficult to provide good bonds to the bodies of connectors, glands, and filters. Problems with the consistency of mixing conductive particles and polymers can make enclosures weak in some areas and lacking in shielding in others.
  • I EC1000-5-6 (95/210789 DC from BSI) for best practices in industrial cabinet shielding (and filtering).
  • BS IEC 61000-5-2:1998 for best practices in cabling (and earthing).
  • the PCB track equivalent of a shielded cable is a track run between two ground planes, often called a "stripline.”
  • guard tracks are run on both sides of this "shielded track” on the same copper layer.
  • These guard tracks have very frequently via holes bonding them to the top and bottom ground planes.
  • the number of via holes per inch is the limiting factor here, as the gaps between them act as shield apertures (the guard tracks have too much inductance on their own to provide a good SE at high- frequencies).
  • the dielectric constant of the PCB material is roughly four times that of air, when FIGS. 1 A-1 E are used to determine via spacing, their frequency axes should be divided by two (the square root of the PCB's dielectric constant).
  • a microstrip When a microstrip enters a shielded PCB box, it will suffer an impedance discontinuity due to the wall of the box. If the wavelength of the highest frequency component of the signals in the microstrip is greater than 100 times the thickness of the box wall (or the width of box mounting flange), the discontinuity may be too brief to register. But where this is not the case, some degradation in performance may occur and such signals are best routed using striplines.
  • Multipurpose padding also means the invention not restricted to proprietary filters and be created to best suit the requirements of the circuit (and the product as a whole) at the lowest cost.
  • Shielding is the use of conductive materials to reduce EMI by reflection or absorption. Shielding electronic products successfully from EMI is a complex problem with three essential ingredients: a source of interference, a receptor of interference, and a path connecting the source to the receptor. If any of these three ingredients is missing, there is no interference problem. Interference takes many forms such as distortion on a television, disrupted/lost data on a computer, or "crackling" on a radio broadcast. The same equipment may be a source of interference in one situation and a receptor in another.
  • .lamda./50 0.003 meters or 3.0 mm minimum @ 2 GHz.
  • the present invention removes the need for the single most expensive and least reliable aspect of the electro-mechanical packaging, which is the EMI gasket.
  • the solution(s) provided by the present invention will eliminate the need for gaskets in a great number of applications, as well as "spoons" and other similarly troublesome structures in the PC Chassis and other electronics enclosures.
  • the present invention provides a configuration of placing two and three dimensional formations into and across the seams of a four-by-two or four-by-one-by-one six sided enclosure, in which the 2D and 3D shapes, which are easily formed in conductive metal (or conductive polymers) allow for improved EMI shielding, but also decrease assembly and manufacturing costs (especially in preferred embodiments).
  • a lid-and-box enclosure each with an EMI attenuation trough.
  • These EMI attenuation troughs are generally of a male semi cylinder inside a female semi cylinder running the length (or a significant length of the enclosure).
  • These merged structures provide both necessary conductance and capacitance for effective EMI attenuation.
  • FIGS. 1A-1 E illustrate various electromagnetic interference shielding principles
  • FIG. 2A illustrates a sample pattern in an enclosure as may be implemented in the invention that embodies the principle of "effective length
  • FIG. 2B illustrates a side of a computer enclosure in another embodiment of the invention, or three cuts in the "four-cut” or TORTURED PATH.TM. solution;
  • FIG. 3 illustrates a two-dimensional embodiment
  • FIG. 4 illustrates a simple electronics enclosure for a three-dimensional EMI shielding solution using partial spheres or "scallops"
  • FIG. 5A illustrates a 2-d/3-d hybrid of the invention
  • FIG. 5C illustrates a feature of a 2d/3d embodiment, using semi-cylinder-in-semi-cylinder formation from an angled view;
  • FIG. 5D illustrates the semi-cylinder-in-semi cylinder feature from a side view;
  • Fig. 6A is a main embodiment of the box and cover using attenuation troughs
  • Fig. 6B is a view of the box and cover
  • Fig. 6C is detail of a section of the box
  • Fig. 7A is a first illustration of the main embodiment
  • Fig. 7B is a second view of the main embodiment
  • Fig. 7C is a third view of the main embodiment
  • Fig. 8A is a schematic detail of the attenuation trough features of the invention before merging box and cover;
  • Fig. 8B is a schematic detail of the attenuation trough features when box and cover are merged;
  • Fig. 9A is a first alternate configuration of the box and cover with a continuous attenuation trough on each side;
  • Fig. 9B is a second alternate configuration with a continuous attenuation trough behind the attachments
  • Fig. 9C is a third alternate configuration of the box and cover with continuous troughs straddling the attachments;
  • Fig. 9D is a fourth alternate configuration of the box and cover with both continuous and intermittent attenuation troughs
  • Fig. 9E is a fifth alternate configuration of the box and cover with a "picture frame" continuous attenuation trough;
  • Fig. 10 is a configuration of multiple attenuation troughs as they would be placed in parallel.
  • Fig. 1 1 illustrates a variation of the attenuation troughs in which they have embedded or multiple troughs.
  • TORTURED PATHTM EMI solution is shown for enclosures that are generally in the shape of boxes and other types of cabinets for computers and other electronic components that require EMI/EMC shielding.
  • a principal wall of an enclosure is shown which is the wall of a shielded enclosure made of a conductive material, with the greater sizes of apertures causing a greater amount leakage of the electromagnetic fields.
  • the improvement reduces the size of apertures by strategically cutting, forming, molding, extruding, stamping and forming any manufacturing method which utilizes an electromagnetically conductive material in basically any application.
  • the present invention provides a less expensive EMI shielding solution than the way the current technology is implemented. This can be accomplished in various embodiments of the invention implemented "two" dimensions (namely two-dimensional considerations since nothing literally takes place in only two dimension) with sheet metal or flat extruded cut or stamped materials. The material could be cast, again, with a thin sheet metal-assuming that the structures cast, cut, or extruded are thin relative to the overall dimensions, considering that the so-called two-dimensional considerations have finite thickness.
  • a goal of this particular embodiment of the invention is to create small apertures. More particularly, the goal of this embodiment is to create apertures that are not only small but force the electromagnetic noise to change directions or to go through apertures that are small and make the path difficult for the EMI to find its way out (thus, the "tortured path.") This, of course, reciprocally applies to the susceptibility of the electronics inside the enclosure to electromagnetic interference from the outside as well.
  • EMI electromagnetic inference generally refers to what is projected outwards to the world and how it might interfere with other devices.
  • the expression "EMI” also includes shielding from any devices that are external to the user and that are radiating electromagnetic fields which will cause interference on the product and this is where the user would be susceptible to EMI.
  • the preferred and conceptually most effective tortured path for the EMI is a sinusoidal saw-tooth square wave, as shown in FIG. 2B, but also may be any kind of irregular shape, whether the pattern is periodic, periodic and changing, or constantly changing in shape.
  • the invention requires that the pattern not allow for the maximum aperture size to be sufficient for the electromagnetic waves to traverse through the material, whether it is inward or outward. This principle of the invention is shown in FIG. 2A as "effective length matters.”
  • the present invention there is no requirement for physical contact, therefore there are no tolerance issues, deforming issues, no degradation over time and no environmental impact. There are no loose structures added.
  • the invention provides an extremely cost effective EMI shielding solution because there are no added parts, no fasteners and no welds. Free-plated material may be used everywhere which are formed in the case of sheet metal, stamp and form and/or a few rivets which do not depend on contact which have no degradation over time and no environmental impact.
  • the first model of tortured path as shown in "effective length” a model is shown where the LSTD is the old standard length of a slot. If it was a straight slot, that gap would be, as shown, compared to length of the tortured path, which is the longest straight line distance that the electromagnetic interference can see through the sinusoid. The length standard and the strength slot would be somewhere in the order of eight to 10 times the length of the tortured path. And all that has been done is a stamp and then a subsequent form or stamp, which is brings the male and female image of these two slots together.
  • FIG. 2B illustrates an alternate and illustrative embodiment of the invention, known by the trade name of The TORTURED PATH.TM. EMI solution.
  • Three cuts are shown in various shapes in the illustration, and four are used in a first type of the alternate embodiment.
  • the cuts may all be of one type of cut, in appropriate patterns, such as sinusoidal, square wave, and certain Brownian-motion type cuts.
  • FIG. 2B shows a couple examples of the different types of shapes.
  • a triangular saw tooth-type cut configuration is shown. Again, the wave(s) are not able to seen by the peaks so it will look for the straightest line it can find. So it's just "tortured” in that it cannot see around the corners.
  • the square wave is then seen and then a very odd bent paperclip-looking shape wave, a cut is seen. Any cut imaginable can be used. The goal is to try to reduce the effective length of any slot that can be used as antenna by the electromagnetic interference.
  • This can be used around I/O devices.
  • This can be used in sheet metal.
  • This can be used in extruded, molded or casted cuts in any shape. It may be used in sort of a modular into a chassis or around the back phalange of a model. It may be used around the input/output devices, in any manufacturing method or in any electromagnetically conducted materials for which EMI needs to be contained.
  • the TORTURED PATH.TM. solution reduces the effective length by strategic cuts, shapes or molds or extruded shapes and, in addition, goes three-dimensional through drawing and overlapping, again, torturing the path. Even bringing together a wave-guided effect,
  • the TORTURED PATH.TM. is the essence of the invention and it can efficiently be implemented in the present invention with complementary forming techniques or molding techniques that don't require additional costs.
  • FIG. 3 is a top view of a pure two-dimensional embodiment, a three-sided and three-sided bar where the one three-sided fitting is down over the other and it comes straight down from the top. Then, the EMI/EMC is just deflected in front and back in order to overcome any interference between the sign waves. So it is possible to bring the two U-sections together, having The TORTURED PATH.TM. seam running along six different edges to bring the two three-sided boxes or sections together. In the configurations shown in FIG.
  • the ' nose ' or the front faceplate goes over all four sides and can be tapped and can control the entire assembly
  • the EMI can be contained and basically element fasteners eliminate welds and gaskets at a very low cost and additionally provide thermal enhancement. So it would therefore be additionally cost reductive and, thermally enhanced because of the ability to now open up more apertures and would be environmentally friendly, without any addition there.
  • One hundred percent of this is assemble-able and 100% reliable with no degradation over time. It could be quarter turn, but in this case, a simple captive-spring loaded screw that can be taken into a pem-nut on the back of a phalange is pivoted off of the side wall. One of those is at the front and both ends of the chassis where there may a split shear on the one side and just the positive locking on the other.
  • 3. times.1 .times.1.times.1 are all assembly configurations contemplated by the invention. (A 3. times, component is shown in US Application Publication 2006-96773 (assigned to the present application) and can be used in 3.times.3, 3.times.2.times.1 ,
  • FIG. 3 shows an exploded view, respectively of the same front corner of the 171/2 inch (in a preferred embodiment, but dimensions are dependent on end-use) 1 -RU box and it shows how the tongue tabs UTBs and LTBs would over-lock and interlock with one another. In this way, the tabs bring the entire assembly together, which is sort of a tongue and groove style. An excellent assembly for minimizing fasteners would help to align the chassis and could bring some electrical contacts together, although it is not dependent on this alignment for an appropriate EMI level. Also, here it uses captive fasteners, both in the screw or the retaining screw.
  • illustrate that the two-dimensional solutions provided in the computer enclosure applications of the present invention can be implemented with ease in all major manufacturing methods including: stamped, laser cut, cast, extruded, molded, etc. In each manufacturing method, almost all of the benefits of each (detailed above) will apply. Because there is a "gap" between mating components, the tolerances in the fabrication process are as “liberal” as possible. The liberal tolerances further accentuate reliability and ensure the highest possible yield of parts off the manufacturing line, so that generally, there are no fit issues. Further, the "one-hit" TORTURED PATH.TM. solution can improve packaging flexibility and thermal performance as well.
  • the inventive solution may be used not only for chassis fabrication, but also for modules, FRUs, connectors and other I/O components that require EMC protection/shielding.
  • the inventive solution to cut shapes to provide great open areas for airflow, does not adversely impact the EMI performance and leads to the conclusion that manufacturing cost remains low, while thermal performance remains high.
  • a preferred two-dimensional embodiment has a diameter of 0.18 and 0.24 inches.
  • the diameter is 0.18" and the values are at 0.24".
  • the dimensions are details that must be optimized depending on end-use which is not something that is required for implementation of the present invention.
  • the rule of thumb is between a three millimeter and seven millimeter gap.
  • 0.18 and 0.24 it is about six millimeters.
  • forty-two thousandths is a standard gage for a "z-axis" dimension.
  • such a dimension is not relevant to the spirit of the present invention, rather a random choice and one that is used frequently by skilled artisans for purposes of convenience and economy.
  • the end-user can just take the box, expand and grow it and then has all of their seams and everything done. All they have to do is set it up correctly. In other embodiments, there does not need to be a "tortured path" in the front. It moves all around to the sides, so one has this box that can be expanded or grown in any sigma or any RU or any depth, for a 171/2 or 24 inch rack, for example. The box is expanded and the performance increases. All pre-plated, no screws, no assembly, a few rivets and its done. It's 100 percent reliable with zero assembly defects.
  • FIG. 4 refers to a sample three-dimensional EMI-shielding solution for an electronics enclosure in a basic embodiment, (such as referred to as the "three- dimensional tortured path solution") with the "shell” or “scallop” embodiment of the invention.
  • the three-dimensional patterns are formed or otherwise configured such that they are generally going the inside periphery of the edges, and the two parts FSE and FL come together and the "sinusoids" meet. All that is necessary for the implementation of the three-dimensional implementation of the invention is to "cut” or stamp the edge of the metal and make the same cut and they come together with a "30 gap” or something similar.
  • the advantages of the primary embodiment of the invention include, inter alia, the fact that there does not need to be any contact and therefore no degradation over time.
  • the parts FSE and FL don't have to make physical contact. Further advantages include that there are no tolerances to consider and there is nothing to deform.
  • the basic three-dimensional embodiment takes advantage of the manufacturing ease of using a two-part enclosure including a five-sided enclosure FSE with an interior volume IN for housing electronics and a flange FL, which fits into the five-sided enclosure upon completion.
  • a box or the flange could be molded or cast, and thus "three-dimensional tortured path" or a TORTURE CHAMBER. TM. is illustrated.
  • the electromagnetic interference cannot get in or out of the electronic enclosure.
  • there is a (periodic) quarter sphere with a half cylinder-type shape IP although, as can be appreciated by those skilled in the art, many other types of shapes would be sufficient for providing the necessary shielding, and some are briefly discussed below.
  • the female three dimensional shapes FP in the "lid" or flange FL or mate with the male protrusions IP along the perimeter of the lid at the lid-to-box interface OE which is generally the XY plane formed at the seam of the junction between the lid and the box (not shown), labeled as plane XY(#A).
  • plane XY(#A) the shielding is provided well inside the allowable for the frequency that are generally desired for shielding.
  • the three-dimensional EMI-shielding solution includes an interior pattern IP of three-dimensional shapes which are stamped, cut, molded, extruded or otherwise configured into the five-sided enclosure FSE around the perimeter of the top or open edge OE.
  • the interior pattern IP as being semi-spherical and "male” or protruding into the interior volume IN, however, in other embodiments the shapes could be reversed or "female” without necessarily departing from the spirit of the invention.
  • the flange FL also includes a pattern that is "complementary" to each other such that the box and the phalange will seamlessly fit as well as provide sufficient EMI shielding. Further discussion regarding three-dimensional EMI shielding solutions is provided in PCT Application Publication WO/06-26758 (Oct. 1 , 2006), assigned to the present applicant, and which is incorporated by reference for all purposes.
  • FIG. 5A-B a first "hybrid" embodiment of the electronics enclosure is shown, in which both two-dimensional and three-dimensional features provide EMI benefits.
  • a simple overlap lid with a stepped-in base is seen, including the features that include the "dome” and the “dimple” which are used to provide the electromagnetic interference shielding.
  • S-D is the dimple;
  • C-C is the dome that fits over it.
  • the gap would be a nominal perhaps 10 thousandths, whatever is appropriate for assembly, and that gap will dictate what the volumetric space that the wave would have to negotiate, and it would be reflected and absorbed as it traversed (traverses) between the cylinder structures and the dome structures, the dimple.
  • structure SE-1 just reflects the top surface of the lid.
  • Structure AC are the stepped-in bend corners of the base where it steps into accept the lid over top of it.
  • the structure (configuration) referenced S2 reflects the side wall of the base.
  • the structure referenced SF is, again, the bend channel as it bends in to allow the lid to come over the base. The waves are forced to negotiate between the side wall and the fringed-over section of the lid.
  • FIGS. 5C-5D once again illustrate the assembly feature of the sprung section with the cylinder-in-cylinder part of the alternate embodiment using the 2D/3D combination of features.
  • CL1 and CL2 contact lines
  • the "line contacts" shown in reference structures CL1/CL2 make physical grounding, and such as overlap for an assembly feature, the overlap for the wave guide, and then incidental contact along the lines into the page at CL1/CL2 for providing further EMI shielding.
  • a main embodiment of the of the lid and box embodiment is illustrated as a low-cost electronics enclosure providing improved shielding.
  • the invention is designed primarily to reduce or completely eliminate the use of gaskets in such enclosures, while still providing adequate EMI shielding.
  • the invention takes advantage of the Applicant's "semi-cylinder in semi-cylinder" shielding features, in which mating semi-cylindrical channels ("attenuation troughs") are formed into both a box BX and a lid FL, such that the semi-cylindrical channels provide both capacitance and conductive contact (and other electrical and mechanical advantages) when they are "mated.”
  • the troughs will also be referred to as "semi-cylinders," although the actual shapes may be more like semi-elliptical cylinders or cylindroids. This description is made without departing from the scope of the invention.
  • FIG. 6A a sample illustration of a main embodiment is shown.
  • the main embodiment includes a box portion BX and a cover portion FL, which are designed to fit together as an enclosure for electronics.
  • the box portion BX which, like the top or lid portion FL is made out of a conductive material, usually mild steel in a preferred embodiment (but which may include other materials which will be discussed below), includes a lip L, which is formed in the box BX to extend inward from the top seam TS, which generally extends around the periphery of the top seam towards the interior of the box.
  • a conductive material usually mild steel in a preferred embodiment (but which may include other materials which will be discussed below)
  • a lip L which is formed in the box BX to extend inward from the top seam TS, which generally extends around the periphery of the top seam towards the interior of the box.
  • a series of semi-cylindrical shapes TR shown as female (elliptical) cylinders in the embodiment.
  • the semi-cylindrical shapes TR are formed around the periphery of the lip L, and in the illustration include 4 "equal" semi-cylinders along the length Lgth of the box, and 2 "equal" semi-cylinders along the width of the box.
  • the semi-cylinders TR are separated by fastener threads SB.
  • the corresponding cover FL structure has 4 "male” semi-cylinders configured TM into the length of flange, and 2 "male” semi-cylinders that are formed into the width.
  • FIG. 6B shows an "assembled" enclosure ENC, in which the semi-cylinder structures from the flange FL have fit into the semi-cylinder structures on the lip of the box to create EMI shielding or attenuating "cylinder-in-cylinder” structures TA(x)/TA(y) across the seam.
  • the cylinder-in-cylinder structures TX(x)/TA(y) create both conductive electrical contact and capacitance along the entire length of the structure. The detail of these structures is discussed below.
  • the cylinder-in-cylinder structure at least partially crosses the "plane" of the seam where the box intersects the flange of the top xy seam. However, it is not required to do so to take advantage of the theory behind these embodiments.
  • the enclosure has two sets of ventilation structures VS1 and VS2 on the two sides yz1 and yz2 of the box.
  • These ventilation structures VS1 and VS2 are generally known in the art.
  • FIGS. 6A and 6B are shown and have been configured due to manufacturing and machining standards, as well as convenience for the end users, and considers the tolerances for the material, especially for the lip structure L and the fastening system of the box. For example, there are 16 fastener threads on the lip L structure.
  • the lip L includes the semi-cylinder structures TA1 ...TAx in the center in the illustrative embodiment.
  • Figs 9a-1 1 there are different configurations that may be more appropriate for different end uses.
  • complex needs for additional EMI shielding may require additional or alternate semi-cylindrical attenuation structures, as are illustrated and discussed subsequently.
  • FIGS. 7A-C illustrate detail of the semi-cylinder-in-semi-cylinder, or attenuation troughs of the main embodiment of the invention.
  • the semi-cylinder-in-semi-cylinder attenuation structures both provide capacitance and conductance which in turn provides EMI attenuation and shielding.
  • the troughs are formed such that there is a high degree of electrical contact between the bottom of the top trough and the top of the bottom trough, usually in a "line" as provided by design, but at least in multiple points of contact as provided in practice over the life of product.
  • FIG. 7A illustrates a first detail of the semi-cylinder-in-semi-cylinder system, as illustrated in FIGS. 6A-B.
  • the lower conductive sheet is formed with a first semi-cylinder or set of semi-cylinders AC1 ...ACx.
  • AC1 ...ACx In some embodiments, as those shown in FIGS. 6A and 6B there will be multiple intermittent semi-cylindrical channels. In other words, as those shown in FIGS. 6A and 6B there will be multiple intermittent semi-cylindrical channels. In other
  • each semi-cylinder trough AC1 ...ACx is terminated with a "quarter-sphere" shape rounding off the semi-cylinder trough.
  • the shape will generally be "less” than a quarter sphere, but is not limited to this.
  • the EMI shielding advantages of a having a partial sphere incorporated into a electronics enclosure are discussed in US Patents 7,342, 184, issued March 1 1 , 2008 to the Applicant, and 7,995,355, issued August 9, 201 1 to the Applicant, and both of which are incorporated by reference.
  • the semi-cylinder troughs formed into the top conductive sheet are slightly different in shape per the "common surface” than the bottom semi-cylinder troughs in a preferred embodiment.
  • the advantage of this is threefold. (1 ) If the top semi-cylinder is slightly shorter in length that the bottom semi-cylinder, the semi-cylinder structures will not be inclined to "stick;” (2) the wear will be less over the lifetime of the product and the semi-cylinder troughs will maintain enough points of contact to be effective; and (3) there will be a greater tolerance from deformation due to torque from the attachment screws over time.
  • the top and bottom semi-cylinders form an attenuation trough
  • FIGS. 8A and B illustrate the fundamental shaping of the EMI-attenuation system in the main embodiment.
  • FIG. 8A illustrates the primary embodiment as shown and implemented in FIGS. 6A-7C.
  • FIG. 8A shows the two conductive sheets S1 and S2 each with a side view of an attenuation trough AT1 and AT2.
  • Each attenuation trough has dimensions d1/d2 (depth), w1/w2 (width), IA1/IA2 (initial angle from lip), TA1/TA2 (final angle from lip) and t1/t2 (thickness of material). It is anticipated that the three- dimensional aspect of the attenuation troughs AT1/AT2 will be roughly and elliptic cylinder, but the dimensions of each will vary slightly to optimize the invention.
  • the thickness of the material t1/t2 must be taken into account when design the dimensions of the attenuations troughs, but other factors must be taken into account.
  • FIGS. 9A-E illustrate sample alternate configurations of the cylinder-in-cylinder structural placement on the box and flange embodiment.
  • FIG. 9A illustrates an assembled box in an alternate embodiment.
  • the semi-cylinder structures are a single continuous structure (as opposed to the "intermittent structure” shown in FIGS. 6A and 6B).
  • the semi-cylinder "troughs" are placed further into the lip structure L' so that the attachment structures do not interrupt the effect of cylinder-in- cylinder attenuation.
  • placing additional stresses on the lip structure L' is only practical insofar as the additional shielding is needed.
  • FIG. 9B illustrates another alternate configuration of the invention in which the semi-cylindrical channels are continuous along all the sides and placed in front of the attachment structures AS.
  • FIG. 9C illustrates another alternate embodiment, in which there are two rows of cylinder-in-cylinder structures one continuous cylinder-in-cylinder structure formed into the rear of the lip "behind” the intermittent cylinder-in-cylinder structure which straddle the attachment structures AS.
  • FIG. 9D illustrates yet another alternate embodiment in which there are both a set of intermittent semi cylinder-in-semi cylinder structures straddle the attachment structures in the front part of the lip structure L, and a continuous cylinder-in-cylinder attenuation structure is "behind" the front row.
  • Fig. 9E illustrates yet another alternate embodiment in which there is a continuous attenuation trough around the perimeter of the enclosure.
  • the continuous attenuation trough(s) AT” will likely provide for more complex manufacturing process, but also provide superior EMI attenuation as there are fewer “gaps.”
  • This "picture frame" embodiment would be more suitable for certain end-use applications.
  • FIGS. 9A-E simply illustrate samples of how the attenuation features of the electronic enclosure may operate under differing configurations.
  • the exemplars shown are meant to be illustrative and are certainly not limited to the examples show.
  • FIG. 10 an alternate embodiment is shown as the trough-in- trough attenuations structures are shown in a parallel (or series) configuration in which the two semi-cylinder-in-semi-cylinder sets have different properties.
  • Bottom sheet S1 is formed with two semi-cylinders AC1 (f) and AC1 (r) which have two different widths WC1 (f) and WC1 (r), thus providing for various advantages in which additional EMI attenuation may be provided by changing the parameters which were discussed in Figs 8a-b above.
  • FIG. 1 1 a second alternate configuration of the attenuation troughs is shown.
  • the attenuation troughs A1/A2 of the two conductive sheets S1/S2 are also formed with secondary shapes that provide additional optional conductive contact points between the sheets.

Abstract

L'invention concerne une enveloppe électronique qui comprend un couvercle et un boîtier constitué d'un matériau conducteur, de préférence de l'acier doux. Un blindage contre les interférences électromagnétiques amélioré est obtenu par formation de goulottes d'atténuation de forme semi-cylindrique dans le couvercle et le boîtier autour de la périphérie de l'enveloppe. Une des goulottes (la femelle) est formée de façon à présenter une taille légèrement inférieure à celle de l'autre goulotte (mâle) afin d'établir un contact en ligne ou plusieurs points de contact le long des surfaces adjacentes des formes. Le contact en ligne et/ou les multiples points de contact entre les goulottes assurent à la fois la conductance et la capacité.
PCT/US2014/030388 2013-03-15 2014-03-17 Canaux formés fournissant un blindage électromagnétique dans des enveloppes électroniques WO2014145594A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14/899,227 US20160174420A1 (en) 2013-03-15 2014-03-17 Formed channels providing electromagnetic shielding in electronics

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201361790068P 2013-03-15 2013-03-15
US61/790,068 2013-03-15
US201314104055A 2013-12-12 2013-12-12
US14/104,055 2013-12-12

Publications (1)

Publication Number Publication Date
WO2014145594A1 true WO2014145594A1 (fr) 2014-09-18

Family

ID=51538037

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2014/030388 WO2014145594A1 (fr) 2013-03-15 2014-03-17 Canaux formés fournissant un blindage électromagnétique dans des enveloppes électroniques

Country Status (1)

Country Link
WO (1) WO2014145594A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017001888A1 (fr) 2015-06-29 2017-01-05 Bosch Car Multimedia Portugal, S.A. Boîtier polymère conducteur pour composant électronique
WO2023126667A1 (fr) 2021-12-29 2023-07-06 Bosch Car Multimedia Portugal S.A Protection, enceinte et leur procédé de fabrication, pour blindage électromagnétique

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4831498A (en) * 1987-07-23 1989-05-16 Uniden Corporation Shield structure for circuit on circuit board
US5557063A (en) * 1994-01-03 1996-09-17 Lucent Technologies Inc. Electronic component enclosure for RF shielding
US5777854A (en) * 1995-05-19 1998-07-07 Ast Research, Inc. Integrate flexible contacts grounding system for a computer system chassis
US6373692B1 (en) * 2000-09-22 2002-04-16 Mace Tech Corp. Screwless computer case mounting arrangement
US20060096773A1 (en) * 2004-11-09 2006-05-11 Cochrance Paul D Reduced cost and gasketting "one-hit" and other manufacturing EMI-shielding solutions for computer enclosures

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4831498A (en) * 1987-07-23 1989-05-16 Uniden Corporation Shield structure for circuit on circuit board
US5557063A (en) * 1994-01-03 1996-09-17 Lucent Technologies Inc. Electronic component enclosure for RF shielding
US5777854A (en) * 1995-05-19 1998-07-07 Ast Research, Inc. Integrate flexible contacts grounding system for a computer system chassis
US6373692B1 (en) * 2000-09-22 2002-04-16 Mace Tech Corp. Screwless computer case mounting arrangement
US20060096773A1 (en) * 2004-11-09 2006-05-11 Cochrance Paul D Reduced cost and gasketting "one-hit" and other manufacturing EMI-shielding solutions for computer enclosures

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017001888A1 (fr) 2015-06-29 2017-01-05 Bosch Car Multimedia Portugal, S.A. Boîtier polymère conducteur pour composant électronique
WO2023126667A1 (fr) 2021-12-29 2023-07-06 Bosch Car Multimedia Portugal S.A Protection, enceinte et leur procédé de fabrication, pour blindage électromagnétique

Similar Documents

Publication Publication Date Title
US7995355B2 (en) Three-dimensional configurations providing electromagnetic interference shielding for electronics enclosures
US8399780B2 (en) EMI-shielding solutions for computer enclosures using combinations of two and three-dimensional shapes formed in sheet metal
US7342184B2 (en) Three-dimensional configurations providing electromagnetic interference shielding for electronics enclosures
US7511230B2 (en) Reduced cost and gasketting “one-hit” and other manufacturing EMI-shielding solutions for computer enclosures
US9345183B2 (en) EMI-shielding solutions for electronics enclosures using opposing three-dimensional shapes and channels formed in sheet metal
US20160174420A1 (en) Formed channels providing electromagnetic shielding in electronics
US20120285738A1 (en) Shielding Polymers Formed into Lattices Providing EMI Protection for Electronics Enclosures
EP2410831A2 (fr) Formes tridimensionnelles avec plusieurs géométries paramétriques et surfaces formées dans les enceintes électroniques pour fournir un blindage contre les interférences électromagnétiques
US7199310B2 (en) Electromagnetic interference shielding structures for computer hard-drive enclosures
US7064265B2 (en) Reduced-gasket EMI-shielding solutions for hard disk drives and other computer components
US8541696B2 (en) EMI-shielding solutions for computer enclosures using combinations of two and three-dimensional shapes formed in sheet metal
CN104053347B (zh) 包括具有拉制的闩锁特征部的框架的电磁干扰屏蔽设备
US20070297160A1 (en) Configurations for EMI Shielding Enclosures
KR100779924B1 (ko) 정보 기술 장치용 인클로저
US20080006444A1 (en) Method for Providing Electromagnetic Interference Shielding in Electronics Enclosures by Forming Tubular Patterns in Conductive Polymer
EP2356896B1 (fr) Configuration de blindage électromagnétique
TWI526151B (zh) 電磁干擾屏蔽配置
US6963495B1 (en) EMI shielded chassis for electrical circuitry
WO2014145594A1 (fr) Canaux formés fournissant un blindage électromagnétique dans des enveloppes électroniques
CN100544570C (zh) 电子设备与采用带有配合锯齿状物的基本共面部分的外壳
CN102065673A (zh) 为电子设备外壳提供电磁干扰屏蔽的三维结构
CN217606505U (zh) 显示模组及led显示屏

Legal Events

Date Code Title Description
NENP Non-entry into the national phase

Ref country code: DE

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 14762326

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 14899227

Country of ref document: US

122 Ep: pct application non-entry in european phase

Ref document number: 14762326

Country of ref document: EP

Kind code of ref document: A1

122 Ep: pct application non-entry in european phase

Ref document number: 14762326

Country of ref document: EP

Kind code of ref document: A1

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC (EPO FORM 1205A DATED 11/03/2016)

122 Ep: pct application non-entry in european phase

Ref document number: 14762326

Country of ref document: EP

Kind code of ref document: A1