CN102065673A - Three-dimensional configuration providing electromagnetic interference shielding for electronics enclosure - Google Patents

Abstract

The invention provides a three-dimensional configuration providing electromagnetic interference shielding for an electronics enclosure. The configuration of the electronics enclosure comprises a computer chassis, in which three-dimensional shapes that may be in the form of a partial or quarter-sphere or cube or other periodic 'patterns' may be stamped, molded, cut or extruded into a lid and a five-sided 'box' to provide improved EMI shielding, such that the need for gaskets is reduced or eliminated.

Description

The three-dimensional structure of electromagnetic interference shield is provided for electronic equipment casing

The application be the applying date on January 10th, 2006, application number for 200680007823.0, name is called the dividing an application of invention that the three-dimensional structure of electromagnetic interference shield is provided for electronic equipment casing.

The priority document reference

The application requires on November 10th, 2005 to submit to, title is the U.S. Patent Application Serial Number No.11/270 of " three-dimensional structure (THREE-DIMENSIONAL CONFIGURATIONS PROVIDING ELECTROMAGNETIC INTERFERENCE SHIELDING FOR ELECTRONICS ENCLOSURES) of electromagnetic interference shield is provided for electronic equipment casing ", 827 priority, this application is the part continuation application, and require on March 15th, 2005 to submit, by Borrow. Douglas. Kao Kelanni (Paul Douglas Cochrane) invention, title is the U. S. application sequence number No.11/080 of " reducing the electromagnetic shielding solution (Reduced cost and gasketting " one-hit " and other manufacturing EMI-shielding solutions for computer enclosures) that cost and liner and other making are used for counter body ", 385 35 USC §, 120 specified priority power.The application also requires the Borrow that submitted on January 10th, 2005. and the title of Douglas. Kao Kelanni is the U.S. Provisional Application sequence number No.60/642 of " being used to make the linerless electromagnetic shielding solution (Gasketless " one-hit " electromagnetic interference (EMC) shielding solutions for the manufacture of computers chassis and other electronic component containers) of computer cabinet and other electron component housing ", the priority of 694 35 USC § 119 (e).For each purpose, all above referenced patent applications all are merged in by reference.

Technical field

The present invention relates to provide the three-dimensional structure of electromagnetic interference shield for electronic equipment casing.

Background technology

Following background technology part partly extracts that from Australia. English. and base is thought. Armstrong (Eur Ing Keith Armstrong), thorough beautiful. " EMC the 4th partly shielding effect designing technique (Design Techniques for EMC-Part 4 Shielding) " of Kerafyrm (Cherry Clough) consultant, EMC-UK alliance.

The volume shielding is commonly referred to " Faradic electricity cage (Faraday Cage) " fully, is acceptable so a kind of impression although this can provide the cylinder (as Mr.'s faraday master) that is covered with the hole, yet is not so usually.Have the cost grade for shielding, this makes considers as early as possible that in design process shielding is commercial extremely important.Shielding can be installed around following components and parts: each IC-cost is 25P for example; Area of isolation-the cost of PCB circuit is ￡ 1 for example; Whole PCB-cost is ￡ 10 for example; Sub-component and module-cost be ￡ 15 for example; Entire product-cost is ￡ 100 for example; Assembly (for example Industry Control and instrument console)-cost is ￡ 1,000 for example; Room-cost is ￡ 10,000 for example; And building-cost ￡ 100,000 for example.

Shielding always can increase cost and weight, therefore always wishes preferably to use other technology of describing in these are a series of to improve EMC, and reduces the needs to shielding.Even when wishing to avoid shielding fully, preferably consider murphy's rule (Murphy Law) and according to real conceptual design, so that can add shielding afterwards if desired.Also can all very reach degree of screening by making all conductors and assembly near the solid metal sheet.Therefore, fully paste the ground plane PCB that set of devices is dressed up by low contoured surface, because of its in the recommended use of the advantage aspect the EMC.

At first keep near the grounded metal surface by internal electron unit and the cable that makes electronic equipment assembly always, secondly by their earth terminal is direct-connected to the metal surface, rather than (perhaps and) utilize the safe star grounding system based on green/yellow lead, can obtain effective degree of screening in electronic equipment assembly.This technology adopts zinc-plated mounting plate or cabinet, and helps avoid the needs to high price shell SE.

How to have worked and write many textbooks, therefore no longer repeated them here at radome.But, the notion of some summaries is helpful.Radome is provided with the impedance discontinuity point on the path of electromagnetic wave propagation, reflection and/or the absorption of radiation.This is in the conceptive working method that is very similar to filter---and they are provided with the impedance discontinuity point on unnecessary conducted signal path.Impedance ratio is big more, and SE is big more.

Under 0.5 millimeter or bigger thickness condition, most of normal metal of making all provides above good SE of 1 megahertz and the above good SE of 100 megahertzes.The problem major part of this metallic shield is to be lower than 1 megahertz and the hole causes by thin material, frequency.

Usually the distance between the circuit that preferably makes conductively-closed and the wall of its radome greatly.The volume of conductively-closed is big more, and the formed field of the launching site in the radome outside and device just will become and get over " thin ".

When shell has wall parallel to each other, just may set up standing wave with resonance frequency, therefore may cause the SE problem.Erose shell or have curved surface or the shell of non-parallel walls helps avoid resonance.When relative shielding wall is parallel, wish to avoid taking place because the resonance of the same frequency that width, height or length cause.Therefore,, can use the square-section, rather than the square-section, and preferably avoid size each other in simple multiple for fear of cubical shell.For example, if length is 1.5 times of width, second resonance of width will take place jointly with the 3rd resonance of length so.The preferred size of using the irrational number ratio, for example those sizes that provide by fibonacci series.

Field source is from two aspects: electricity (E) and magnetic (M).Electromagnetic field is formed (wave impedance E/M is 377 in the supposition air) by E field and the M field of giving certainty ratio.Electric field is easy to be stopped by thin metal forming, because electric field shielding mechanism is to carry out redistributing of electric charge at the conducting border place; Therefore, anything that almost has a high conductivity (low resistance) all shows suitable Low ESR.Although the two-forty that electric charge is redistributed under high-frequency can cause producing a large amount of displacement current, even if thin aluminium also can easily be tackled this situation.But, magnetic field may more difficultly stop.They need create the magnetic field opposite with incident magnetic field in the inner vortex flow that produces of shielding material.Thin aluminium is not to be well suited for this purpose, and the required electric current length of penetration of given SE depends on the frequency in magnetic field.SE also depends on the characteristic of the metal that is used to shield, and this is called " kelvin effect ".

The skin depth that is called the shielding material of " kelvin effect " makes the electric current that is caused by rebound magnetic field approximately reduce by 9 decibels.Therefore, thickness is that the material of 3 skin depths has at opposition side and reduced about 27 decibels electric current, and has about 27 decibels SE of M field.

Kelvin effect is even more important at low frequency usually, formed field excellent magnetic and have the wave impedance lower than 377 Ω more likely under such frequency.Most of textbook has all provided the formula of skin depth; But, this formula need be known the conductivity and the relative permeability of shielding material.

The conductivity of copper and aluminium surpasses 5 times of steel, therefore be good at very much stopping electric field, but their relative permeability is 1 (equaling air).Typical mild steel has under low frequency and is approximately 300 relative permeability, when frequency increases to when surpassing 100 KHz, drops to 1.The higher magnetic permcability of mild steel reduces its skin depth, and making has better Rational Thickness than aluminium when being used to shield low frequency.The steel of different brackets (particularly stainless steel) has different conductivity and magnetic permeability, and their skin depth also has remarkable difference as a result.The good material that is used to shield should have high conductivity and high magnetic permeability and enough thickness, with the skin depth amount that need to obtain under the low-limit frequency of being concerned about.Mild steel plate with 1 millimeters thick of pure zinc (for example 10 microns or more) is suitable for many application scenarios.

100 decibels or more SE result when being easy to obtain frequency and surpassing 30 megahertzes with the metallic article of ordinary construction.But, this adopts the shielding volume that does not have joint or slit of complete closed, so make quite difficulty of product assembling, unless you are ready to it is carried out complete weld seam, and does not also have external cable, antenna or transducer (rather than abnormal products).In the practice, no matter whether make shielding and reduce emission or improve vulnerability to jamming, most of shielding properties is all limited by hole wherein.

Consider that the hole has hinted " slot antenna " of hole as half-wave resonance as the hole in other best shielding.This makes us to make prediction about maximal pore size to given SE: for single hole, SE=20log (Ω/2d), wherein Ω be the wavelength under the frequency of heart that closes, d is the full-size in hole.In fact, this supposition can not be always correct, but it is a Simple Design instrument that becomes good framework.Might improve this formula according to the technology of using on the specific product and construction method and practical experience.

The resonance frequency of slot antenna is by its longest dimension---diagonal is managed.Even this makes Kong Duokuan or the how narrow difference of the sight line of passing the hole that whether exists very little.

The thickness of hole and lacquer or oxide-film forms by overlapped metal plates uniformly, and just radiation under their resonance frequency (leakage) is passed as their wide enough fingers.One of most important EMC problem is to make the internal frequency of product remain on inside, so they can not pollute outside radio spectrum.

(wherein γ is the light velocity to the half-wave resonance of slot antenna (with the above-mentioned rule of thumb: SE=20log (2d) expression): 3.10 to utilize relational expression γ=f λ ⁸Meter per second, f are the frequencies of representing with hertz, and λ is the wavelength of representing with rice).It is half-wave resonance that our discovery will be located about 350 megahertzes along the gap of the 430 narrow millimeters long of the leading edge extension of the front panel of 19 inches carrier unit.Under this frequency, our example 19 " front panel no longer provides more shielding, and it removed also there is not what difference fully.

20 decibels SE under 1 Gigahertz need be not more than about 16 millimeters hole.For 40 decibels, may only be 1.6 millimeters, need liner to come closed hole and/or needs to use waveguide under the cutting technique of describing later.In the practice, actual SE depends on the degree of closeness (make such as flat cable the noise cable that carries number bus away from shield opening and joint) in internal resonance, assembly and conductor between the wall of shell itself and hole, and the impedance that is connected that is used for the parts of package shell etc.

Anywhere may, all expect be necessary or inevitably porous dehiscence become a plurality of littler holes.Inevitably slotted hole (lid, door etc.) may need the liner or the spring clip (or keeping shielding successional other means) that conduct electricity.Therefore the SE (roughly) of a plurality of little same holes close to each other is proportional to its quantity (SE=20logn, wherein n is a hole count), and two holes will be worsened 6 decibels, and four will worsen 12 decibels, and eight will worsen 18 decibels or the like.But, perhaps when the hole keeps clear of (comparing with wavelength) each other,, broken in the stage because eliminating the general 6 decibels of rules of this every even numbers of effect when the wavelength under closing frequency of heart begins whole dimension with array of orifices when suitable.

Be set to the SE that obtains is respectively worsened, but the half-wavelength under 100 megahertzes is 1.5 meters.Under so low frequency, less than with regard to this typical products, the increase of hole count often makes the SE of shell worsen with regard to those.

The hole is not only as slot antenna.In shielding, flow and be forced to electric current, make its emission magnetic field around the hole turning path.Stride across the voltage official post hole emission electric field in hole.The author has seen by the diameter of microcontroller from the little radome that is installed on the PCB and has been not more than 4 millimeters hole (being intended to be used to embed the erection column of plastics) with the level of signifiance of 130 megahertzes emission.

The unique actual wise mode of finding the SE of any complicated shell with hole be utilize the three dimensional field solver to structure and any PCB and conductor (particularly those may near any holes) carry out modeling.The software kit that can realize this function all has friendly user interface now, and may operate in desktop PC.Perhaps, the user also can find technical ability university or the design consulting firm that has necessary software and drive it.

Owing to SE along with assembly method and quality, material and inner PCB and cable differ widely, but preferably keep 20 decibels SE " secure border " always.If final design verification/quality test existing problems comprises that so at least it also is favourable allowing to utilize at least 20 decibels of design features that improve SE.

50 hertz frequency is problematic, and wishes to have the SE under this frequency of common metal of any Rational Thickness.Special material such as magnetic conductive metal and radiometal has very high relative permeability, usually in 10,000 scopes.Their skin depth is correspondingly very little, and is just effective but they only reach tens KHz.It is very favorable noting not knocking the thing of being made by these materials, because this will destroy their magnetic permeability, so they have to be thrown away or annealing again under atmosphere of hydrogen.These unusual materials are used for quite similar passage, so that magnetic field is turned to away from shielded zone.These are different with the employed notion of common radome.

All metal shield materials that have greater than 1 relative permeability can both be saturated in high-intensity magnetic field, therefore can not work well as radome, and be heated usually.The steel or the magnetic conductive metal shielding box that reduce the power transformer of hum field can be saturated, and can not obtain desired effect.Usually, make that case is bigger to be necessary, therefore do not need to experience the local field of this intensity.Another shield technology that is used for low frequency shielding is initiatively to eliminate, and at least two companies have developed this technology, specifically is used at the image of being stablized CRT VDU by the environment of the supply frequency magnetic pollution of high level.

If Fig. 1 D illustrate we prolong the ripple that leaks by the hole before unfettered must arround the distance of advancing between the metallic walls, even the hole can be passed through to a fist greatly so, we also can obtain considerable SE.This very effective technology becomes " waveguide under the cutting ".The honeycomb metal structure is actually the waveguide under a plurality of cuttings stacked side by side, through being commonly used for the ventilating window of shielded enclosure, is similar to high SE shell.As any hole, when its inner opposite angle (g) when being half-wavelength, waveguide makes all incident magnetic fields pass through.Therefore, our cutting frequency of waveguide is given by the following formula: f _Cutoff=150,000/g (when g was unit with the millimeter, answer was to be unit with the megahertz).Under this cutting frequency, waveguide can be as not leaking (shown in Figure 1A) the plain bore, and more shielding can be provided: for f＜0.5f _Cutoff, SE is approximately equal to 27d/g, and wherein d advanced by the distance of waveguide before the ripple freedom.

Figure 1A illustrates by the SE example that waveguide obtained under the cutting of 6 different sizes.Littler diameter (g) causes higher cutting frequency, and the diameter of 50 millimeters (2 inches) obtains the full attenuation of 1 Gigahertz.In fact the SE of the increase that the degree of depth (d) that increases causes obtains very large value.

Waveguide under the cutting is unnecessary is made by pipe, but can utilize simple sheet metal goods to realize, wherein metallic article folds proper depth (d) thereby the size of product can not increased too much.As a kind of technology, not the restriction that only is subjected to imagination, but must be early stage with regard to consideration in project, because the failure product that does not use conductor is improved common being difficult to, wherein conductor can not pass the waveguide under the cutting, because this is trading off to their effects.The cutting under waveguide be highly suitable for plastic shaft (for example, control handle) so that they not entail dangers to they withdraw from the SE of shell.Replacement scheme is to use the metal shaft with annular conductive gasket, and stands final friction and wear.Cutting waveguide down can be avoided divesting continuously and/or to the needs of various fixed part, and so save material cost and installation time liner.

Liner is used to avoid the hole at joint, seam, door and removable panel place to leak.Assembling for simple and easy coupling, cushion designs is not too difficult, but door, opening, lid and other removable panel have caused many problems to liner, because they must satisfy machinery and demand electricity of a plurality of contradictions, more need not put forward chemical need (to avoid corrosion).Shielding gasket also needs environmental sealing sometimes, adds intermediate.

Figure 1B illustrates the typical cushion designs of the door that is used for industrial cupboard, and it utilizes conductive rubber or silicon resin compound, so that environmental sealing and EMC to be provided shielding.Spring clip also is used for this class usually and uses.

It should be noted that the green/yellow line that is used for door or panel safety ground can be not favourable to the EMC of hundreds of KHz.Do not use long line if use short wide earth strip, this may prolong several megahertzes.

Having can be for selecting for use from the magnanimity kind liner of how tame manufacturer, and wherein some manufacturer also provides the personalized customization service.This observed result has disclosed the neither one liner and has been fit to use on a large scale.Consideration when design or selection liner comprises: (1) mechanical flexibility; (2) compressive deformation; (3) impedance of wide range of frequencies; (4) corrosion opposing (the electric EMF of low stream about compounding ingredient is applicable to desired environment); (5) keep out the desired harsh ability of normal use; (6) shape of installation surface and preparation; (7) consolidation is easy; And the needs of (8) environmental sealing and smoke and fire.

Shielding gasket has 4 kinds of main types: the polymer of conducting polymer, conductive package, wire netting and spring clip.(1) conducting polymer (insulating polymer that wherein has metallic, double as is an environmental sealing, and has low compression deformation, but needs significant contact to press, this makes their be difficult to just be used in the door of manually opening without lever is auxiliary.(2) (foam of polymers or pipe with external conductive coating are very soft and tough, have low compressive deformation for the polymer of conductive package.Some only need low-level contact to press.But, they can not make environmental sealing best, and their conductive layer may easier wearing and tearing.(3) wire netting (arbitrarily or braiding) is stone usually, but therefore the impedance of but mating metal shell better has better SE than above type.They have relatively poor environmental sealing performance, but some are provided to bonding environmental sealing at present, make two types liner can be used in a kind of operation.(4) spring clip (" finger storage ") is made by beallon or stainless steel usually, and can be very flexible.The use of their maximums is must manually extracting (opening), the easy module of inserting (closing) and having high-grade use (and door) easily.Their demagnetization contact action helps to obtain good binding, and the impedance matching of they and metal shell is fine, but when they are not used in high pressure, needs to safeguard (may just use the vaseline spot every several years).The also easier accidental damage that is subjected to of spring clip for example twists in the overcoat sleeve and crooked or fracture.Therefore the size in spring clip and the gap between them causes induction, for high frequency or crucial the use, may need doublely, for example can find out from the breadboard door of most of EMC.

Need product is carried out suitable mechanical pretreatment, liner can be installed simply and effectively.Absorption from the teeth outwards and squeeze liner between matching block simply, may not can work best---their assembling screw is twisted tightly more, thereby make great efforts the compressing liner and make it to have good sealing, the gap between the fixture may be bent manyly more so, opens leakage-gap more.Shown in Figure 1B, this is the insufficient rigidity because of matching block, if the groove that does not have liner to clamp-on just is difficult to make matching block enough hard.Groove also helps correct location, and keeps liner in assembling process.

The liner contact zone needn't apply (unless it has electrically-conducting paint), and material therefor, their preparation and plating must think over the galvanic corrosion point.All liner details and measurement result must be reflected on the manuscript, and must assessment to change that they proposed influence to shielding and EMC.When application job was transferred to different suppliers, it was very common making liner useless, because mask information can not be set on the figure.Because to the change degree of the super scope spraying of the liner installation region that do not covered, employed change also may have ill-effect (when different coating workmans applies) in coating process.

Fig. 1 C is illustrated in the macropore in the wall of screening can, utilizes inner " dirty case " to control by the field in hole and leaks.Joint between dirty case and the enclosure must with the same processing of any other joint in the radome.

Can obtain the window of multiple shielding based on following two major techniques: the thin metal film on the plastic sheet and the wire netting of embedding.(1) thin metal film on the plastic sheet, normally tin indium oxide (ITO).At film thickness is more than 8 microns and 8 microns the time, and light worsens and begins to become unacceptable, and for battery powered product, the back light of increase may too be difficult to burden.The thickness of these films may be not enough to provide the good SE below 100 megahertzes.(2) wire netting of Qian Ruing is made by the dusting cover of the copper cash of blackening usually.Worsen for the light identical with metal film, these provide higher SE, if but mesh size is improper, and they may be subjected to More's interference of display pixel so.A kind of knack is the diagonal orientation mesh.

Honeycomb metal display screen also can obtain very high shielding properties.They are the waveguide under a large amount of cuttings, and are stacked side by side, and major part is used in safety or the Military Application.The extremely narrow visual angle of waveguide mean the operator the head avoid any other people to steal a glance at their display screen.

The size of screening must be little of the SE of shell not being reduced too much.The SE (roughly) of a large amount of little same holes close to each other and their quantity n proportional (SE=20logn), therefore two holes will make SE worsen 6 decibels, and 4 will make SE worsen 12 decibels, and 8 will make SE worsen 18 decibels, and the like.For a large amount of apertures of typical air grating window, mesh size is significantly less than a needed hole for same SE.With regard to the size of ventilation hole surpassed quarter-wave upper frequency, the formula of " 6 decibels of every multiples " that this is rough is through engineering approaches too, but for this situation, did not have simple rule or empirical equation.

Waveguide under the cutting allows to have the upper air current rate of the SE of higher value.Honeycomb metal ventilation radome (the hexagon pipe by many long and narrow combinations is side by side formed) used many years for this purpose.Can believe high shielding 19 " at least one manufacturer of cupboard frame requires to shield for the ventilation hole up and down that uses common metal goods technology uses cutting waveguide down.

The shielding that designs for ventilation hole may be very complicated and since need that scavenging air brings be deposited on dust on the radome.The design of careful air filter can be so that the ventilation radome be soldered or otherwise for good and all be fixed on the position.

For good sensation and outward appearance, use plastic casing usually, but plastic casing is difficult to shielding.The inside of using the electric conducting material the metallic in binding agent (electrically-conducting paint) or using actual metal (plating) applied plastic shell, be harsh technically, if and in harness hope, in the Mould design process, should be noted that details so.

When finding to be necessary to shield, can notice that usually the design of plastic casing does not allow to obtain required SE by applying its inner surface.Weakness is the seam between the plastic components usually; They can not guarantee the sealing coupling usually, and are not easy sealed usually.Often need expensive new die, the income of market introducing simultaneously and new product produces and begins delay.

For new product, no matter when need plastic casing, at the beginning of design, just consider that obtaining necessary SE is fatal economically.

Coating or plating must not be very thick on plastics, and therefore the quantity of the skin depth that is obtained may be very little.Some utilize the gentle coating of nickel and other metal to develop into the quite high magnetic permeability that adopts nickel, to reduce skin depth and to obtain better SE.

Coating and other practical problem of electroplating comprise is bonded on the plastic them in the whole use of product in desired environment.The professional knowledge that does not have material and technology is so done not too easily.Electrically-conducting paint that product inside comes off or electrodeposited coating will cause a lot of harm to EMC---and may make the conductor short circuit, cause operation unreliable and have a risk of fire and electric shock.Coating and electroplating plastic must be by having the expert of protracted experience to finish in this professional domain.

The specific question of coating or electroplating plastic is a voltage isolation.For second series products (double insulation), add conductive layer to plastic casing inside and can reduce electric leakage and clearance distance, and relax Electrical Safety.And, for the product of any plastic casing, add conductive layer to the inner surface of housing and can promote to carry out individual Electrostatic Discharge by seam and joint, may use the neurological susceptibility problem of ESD has been replaced the radiated interference problem.For business reason, finally may need any possibility of shielding if exist, it is extremely important to begin just careful design plastic casing from the initial design process so.

Some companies are by using thin and low-cost metallic shield that do not have attraction on printed circuit board (PCB) or around the assembly, come wisely (expection pun) to pack, thereby make and for their beautiful plastic casing, there is no need to bear dual shielding task.This can save great amount of cost and save a large amount of troubles, but must just consider at the beginning of project, otherwise does not have unnecessary space (the perhaps space of type of error) to assemble the metallic article of this class inside.

The plastics of conduction in enormous quantities or resin use conducting particles or the line that disperses usually in the insulating adhesive of mechanical strength is provided.Sometimes this can form basic plastics or resin " collection skin ", makes not insert helical coil or the good RF combination of the very difficult acquisition of similar tool.These insulation collection skins make and are difficult to holes of avoiding the joint to produce, also make to be difficult to provide and the combining of the main body of connector, sealed tube and filter.The conforming problem of hybrid conductive particle and polymer makes at some regional shells very poor, and lacks shielding in other zone.

Based on the material of carbon fibre (conducts electricity) itself and the polymer of self-conductive, begin to be easy to obtain, but they do not have the high conductivity of metal, therefore the SE that can not provide for given thickness.Silk screen and connector (or sealed tube) and their 360 ° of bondings that all pass the shielded type cable of screening can are parts of the same important any " faraday cylinder " with outer cover metal goods itself.Be used for non-shielding external cable filtering whole assembly and to install also be very important for the SE that obtains.IEC 1000-5-6 (95/210789 DC from BSI) draft referring to the best practice that is used for industrial cupboard shielding (and filtering).BS IEC 61000-5-2:1998 referring to the best practice that is used for cable (and ground connection).

Thereby what turn back to us shields cost-effective original scheme with low as far as possible assembling horizontal application, and we should consider the problem with the shielding of PCB level.Desirable PCB cascade screen is to come the closed metal box with connector that shields and the conventional filter that is installed on its wall generally speaking, and in fact, this only is the miniature version of aforesaid product cascade screen shell.The result is commonly referred to the module that high SE can be provided, and is generally used for RF and microwave regime.。

The PCB shielding of lower cost is possible, although the module that their SE does not design usually is so good.It always depends on the ground plane of the PCB that is used for providing radome one side, makes the case of simple five sides to be assemblied on the PCB as any other assembly.With the case of these five sides with the means of spot welds in a plurality of surrounding environment on ground plane, create around " faraday cylinder " in the desired zone of circuit.The case of the installation PCB shielding of five sides of various standards is easy to obtain usually, and specializes in the design of adopting customization in the company of this precision metallic goods usually.Case utilizes the lid of snap-on, when opening with convenient lid, can easily adjust, visit test point or replace chip.This movably lid cooperates with the spring clip of environment usually, can obtain good SE when being closed on the appropriate location when them.

The weakness of this screen method is the variation in visibly different hole, and the hole is as follows: by the hole of causing, gap between the ground plane of welding; Any hole in the ground plane (for example clearance around path and the through hole); And any other hole (for example ventilating, be connected to the path of adjustable component, display etc.) in the case of five sides.To the components side ground plane, can be that cost is eliminated one group of hole with the edge seal welding of the case of five sides with manual operation consuming time.

For least cost, we wish that signal that we are all and energy all offer the shielding area as the PCB of track, avoid lead and cable.This means that we need use the PCB that is equivalent to shielded connector that dividing plate is installed and the filter that dividing plate is installed.

The PCB track that is equivalent to shielded type cable is the track of advancing between two ground planes, is commonly referred to " strip line ".Sometimes, the protection orbital motion is on the both sides of this " shielding track " of same copper layer.These protection tracks have very many through holes, and they are connected to ground plane up and down.Here, the quantity of per inch through hole is limiting factor, and this is because the gap between them is as shield opening (protection track itself has too many self-induction, thereby provides good SE with high frequency).When Figure 1A-1E is used for determining by the interval, because the dielectric constant of PCB material roughly is four times of air, so their frequency axis should be divided by 2 (square roots of PCB dielectric constant).Some designers can for the protection track not take a lot of trouble, but only use through hole " together with " track in question.For fear of resonance, what the through hole around the desired space of randomly changing was capable is a good idea at interval.

Enter the circuit region place that is sealed by shielded cask at strip line, their ground plane up and down (and any protection track) is connected the welding point of shielded cask in the both sides near strip line.

Only having single ground plane and opposite side is exposed to airborne track, is exactly so-called " microwave transmission band " structure.When the microwave transmission band entered in the PCB case of conductively-closed, its impedance that will become owing to the wall of case was discontinuous.If the thickness of the wavelength ratio tank wall of the highest frequency component of signal in the microwave transmission band (or case is installed width of cover plate) is big 100 times, discontinuity may be lacked very much and can't record so.But if not this situation, some deterioration of performance may take place so, so sort signal utilizes preferably strip line to send.

The track of all conductively-closeds is owing to the PCB zone through conductively-closed, so must be filtered.By might utilizing PCB shielding rather than this filtering to obtain remarkable improvement, but this is difficult to prediction.Therefore, filtering should always be put into plan (at least for prototype, and only just removing) from the PCB Butut after EMC tests successfully.

Best filter is a punch, but to avoid the cloth line style be favourable in order to save cost.Leaded PCB mount type is obtainable, and can be welded on the PCB in common mode.Then, leaded PCB seat when follow-up phase is installed, is welded to the wall of shielding box at it with hand.Be welded to potential ground plane by the central contact with filter, can assemble quickly, this makes that the welding point between shielded box and the same ground plane is very approaching in its both sides.Back one structure also is fit to the break-through filter of mounted on surface, and this can further reduce assembly cost.

But, the break-through filter, even surface installing type, also still than simple ferrite bean or capacitor costliness many.In order in exploitation EMC test, to find the most worthwhile filter of cost, also minimum latency and avoid the PCB Butut repeatedly simultaneously, can adopt following any filter construction easily to create many purposes pad pattern: (1) zero ohm link (does not have filter, when EMC tests new design, usually as starting point); (2) resistor of connecting or ferrite bean with signal; (3) be connected to the capacitor of ground plane; (4) choke of general mode; (5) resistor/ferrite/capacitor bank (three-way pipe, LC etc., more detailed) referring to this a series of part 3; (6) break-through capacitor (being center pin ground connection, is not real break-through); And (7) break-through filter (three-way pipe, LC etc., center pin ground connection is not real break-through).Many purposes pad also means and the invention is not restricted to proprietary filter, but can be created with minimum cost, preferably to satisfy circuit (with as a whole product) demand.

In seeking the EMI/EMC solution, existing technology is clumsy and trouble.For example, prior art is used spoon (they are some small embossments that have indenture at extension), and so they are just got together and towards rightabout.One is transformed into another, and they just match and must do the physics contact like this.These structural bendings, and when one in them planar crooked and they when no longer contacting, they will lose their conductivity.So prior art will begin to leak EMI.Their tolerance is poor, and very expensive.In addition, the existing manufacturing technology that is designed to address these problems need form shell, engages or other scheme of forbidding so that it must have tongue-and-groove.

Summary of the invention

The present invention has eliminated the demand to the one side (being EMI gasket) the most expensive in the electromechanics encapsulation, that reliability is the poorest.During solution provided by the invention will be eliminated and widely apply, in " spoon " shape thing and the PC case in other similar trouble structure to the demand of liner.The invention provides a kind of structure and manufacture method of hard-drive covering system, wherein, comprise that the polymer of electromagnetic interference shield (EMI shielding) is configured, so that can reduce or eliminate shielding gasket fully.To by Premier

One side of the disc driver fixture of making or many sides or another EMI shielded polymer material cut according to pattern, and sufficient EMI shielding is provided, and have the effect that does not need shielding gasket.In replaceable structure of the present invention, computer casing has had cheap shielding solution.

Description of drawings

Figure 1A-1E illustrates various existing electromagnetic interference shield principles;

Fig. 2 illustrates the sample mode of the shell that the present invention can realize, wherein the present invention specifically implements the principle of " effective length " in the two-dimentional EMI shielding solution;

Fig. 3 is illustrated in a side of the counter body in the another embodiment of the present invention, perhaps three cuttings or the TORTURED PATH in " four cuttings " ^TMSolution;

Fig. 4 A illustrates the two-dimentional specific implementation of the counter body of overlooking;

Fig. 4 B is the Closed Graph of the 2-D EMI shielding principle in the counter body;

Fig. 4 C is the end view of two-dimentional EMI screening can;

Fig. 4 D is the front view of two-dimentional EMI screening can;

Fig. 5 A illustrates the first embodiment of the present invention that realizes 3D shape;

Fig. 5 B illustrates the first embodiment of the present invention of seeing from different perspectives;

Fig. 6 illustrates the plane of the body of facing five formula casees in the first embodiment of the invention;

Fig. 7 illustrates the plane of the body on the cover plate that is stamped into first embodiment of the invention;

Fig. 8 A illustrates the sample details of " recessed " partial sphere;

Fig. 8 B illustrates the close-up view of " protruding " partial sphere;

Fig. 9 A illustrates the EMI shielding principle in the example 3D shape of shell of the present invention;

Fig. 9 B illustrates the EMI shielding principle in the shell of assembling;

Figure 10 illustrates provides EMI the of the present invention further operation of shielding;

Figure 11 A is illustrated in the inside of three-dimensional embodiment of the present invention in the box assembly;

Figure 11 B illustrates the vertical view of the present invention in the cap assemblies;

Figure 11 C illustrates the end view of the box assembly among first embodiment;

Figure 12 illustrates the alternative embodiment of the present invention that utilizes single cubic body;

Figure 13 illustrates the double cubic body in another alternative embodiment; And

Figure 14 illustrates the mixed structure that uses the two and three dimensions shielding construction.

Embodiment

Utilization " shell " of the present invention or " scallop " embodiment shown in Fig. 5 A and Fig. 5 B, can form or dispose in addition three dimensional type, make them extend along the inner periphery at edge usually, and two parts FSE and FL gather together, and satisfy " sine curve ".Implementing that three dimensional realization of the present invention is necessary is the edge of " cutting " or stamped metal, and does identical cutting, and they and gather together with " 30 gap " or other similar thing.The advantage of basic embodiment of the present invention especially comprises this fact: the therefore deterioration (referring to Fig. 9 B) in time not without any need for the contact.FSE contacts with the unnecessary physics that carries out of FL part.Further advantage comprises does not consider tolerance, does not have distortion yet.

Refer again to Fig. 5 A, first embodiment of the three-dimensional EMI shielding solution that is used for electronic equipment casing is shown with the side angle view.First embodiment has the advantage easy to manufacture of utilizing two parts formula shell, and this shell comprises five formula shell FSE and the cover plate FL with inner space IN of being used to hold electronic equipment, in case finish, cover plate FL will be installed on five formula shells.

Refer again to Fig. 5 A-5B, Fig. 5 B illustrates the vertical view (embodiment of part three of the present invention will at the following brief discussion that carries out) of the three-dimensional case among the embodiment of part two of three-dimensional solution.In this certain embodiments, therefore case or cover plate are illustrated " three-dimensional bending path " or TORTURE CHAMBER by mold pressing or casting together ^TMGenerally speaking, electromagnetic interference can not enter electronic equipment casing or can therefrom not spill yet.In the preferred embodiment shown in Fig. 5 A and Fig. 5 B, there are (periodically) 1/4th spheroid IP with semicircle column type shape, although as the skilled personnel to understand, the body of many other types also enough provides necessary shielding, and some will carry out brief discussion hereinafter.In diagram, periphery and convex projection IP's concavity said three-dimensional body FP among " lid " or the cover plate FL along lid closely cooperates at OE place, the interface of lid and case, the interface OE of lid and case is exactly the formed XY of the seam plane of the junction between lid and the case (not shown) usually, is marked as plane X Y (#A).

Although between case FSE and lid/cover plate FL, suitable space can be arranged, also provide shielding in inside, be used to allow usually in order to shield required frequency.

Shown in Fig. 5 A and Fig. 5 B, three-dimensional EMI shielding solution comprises the inner IP of said three-dimensional body, wherein, these said three-dimensional body can be drawing, cutting forming, die forming, extrusion molding or otherwise be configured to around the top side of OE or five formula shell FSE of the periphery of open side.Fig. 5 A and Fig. 5 B are depicted as inner IP hemisphere and " protrusion " or project into inner space IN, but, in other embodiments, described body can be the unnecessary upset that deviates from spirit of the present invention or " concavity ".Fig. 5 A and Fig. 5 B illustrate the type that cover plate FL also comprises each other " supporting ", so that case and cover plate can seamlessly cooperate, and provide sufficient EMI shielding.

The half-wave resonance of the slot antenna of representing with above-mentioned empirical method is to utilize the relational expression SE=20log (basis of solid line (and empirical method of Fig. 1 E) among Fig. 1 D of λ/2d).Therefore, the deterioration relevant with porous type provided by the following relationship formula: SE reduction=10log (N), wherein the # hole in the N=type.Utilize relational expression f λ=c, wherein c is the light velocity 3 * 10^8 meter per second, and frequency is a unit with the hertz, and λ is to be the wavelength of unit with rice, f=wave frequency wherein, λ=wavelength, the c=light velocity.

Shielding promptly uses electric conducting material to reduce EMI by reflection or absorption.It is the challenge with following three Fundamentals that electronic product is successfully shielded with EMI: interference source, disturb recipient and be connected the source and the path of recipient.If lack any one of this three factors, all do not have interference problem.Recombinant Interferon adopts many forms, the interruption/lost data of the distortion on the TV, computer for example, or " crackle " in the radio broadcasting.Same equipment may be interference source in one case, may be recipient in another case.

Current, FCC adjusts the EMI emission between 30 megahertzes and 2 Gigahertzs, but does not indicate the anti-interference to external disturbance.Along with device frequency increases (it is common that the application of 10 Gigahertzs is becoming), their wavelength reduces pro rata, this means that EMI can send/enter very little path (for example, under the frequency of 1 Gigahertz, path must be less than 1/2 inch) from very little path.Therefore the trend to higher frequency helps to drive the needs that more EMI are shielded.As the reference point, computer processor is operated with the frequency that surpasses 250 megahertzes, and the portable phone of some renewals is operated in 900 megahertzes.

Traditionally, metal (conduction itself) has been the selection material of EMI shielding.Because many benefits of plastics in recent years, replace metal to have huge trend with plastic resin (having conductive coating or fiber).Even plastics itself are transparent to electromagnetic radiation, but the improvement of coating and fiber has allowed the design engineer to consider the advantage of plastics.

As concrete example, consider that FCC adjusts with the frequency of shielding up to 2 Gigahertzs, the typical maximum clock speed in many controllers of enterprise network is 400 megahertzes.If you think that 2 Gigahertz values are as the peak frequency of being concerned about, so at 400 megahertzes, the user will shield up to and comprise the 5th harmonic wave of 400 megahertz signals, i.e. 400 megahertzes * 5=2 Gigahertz (shielding the 5th harmonic wave of the maximum clock speed of 400 megahertzes).

In order to determine the wavelength at 2 Gigahertz places, utilize equation c, more than: f λ=c, λ=c/f, λ=(3 * 108)/(2 * 109 λ=0.15 meter (at 2 Gigahertz places).Term A﹠amp; B be concerned about about to the longest may slit length definite λ/2=0.075 rice or 75 millimeters.Therefore recommendation remains on about λ/20 to the scope of λ/50 with the hole, and for 2 Gigahertzs, the hole should remain in the following scope: under 2 Gigahertzs, and maximum λ/20=0.075 rice or 75 millimeters; Under 2 Gigahertzs, minimum value λ/50=0.003 rice or 3.0 millimeters.

Can see from above-mentioned equation, shield effectiveness for 1 hole of maximum length " X ": at 3 millimeters places, SE=20log (λ/2d) (do not have minimum value, the smaller the better, this equation is as the actual value of encapsulation)---〉locate SE=20log (0.15/ (2 * 0.003))=20log (25)=28 decibel at 7.5 millimeters '---SE=20log (0.15/ (2 * 0.0075))=20log (10)=20 decibel.

Therefore, in standard application, a plurality of holes are arranged, for example preferred 0.060 " thick steel plate SE reduction=10log (N), have the hole type and SE reduction=10log (the N)=10log (100)=20 that comprise 100 holes.Under the situation in 7.5 millimeters holes, the result is that shielding will arrive zero, and under the situation in 3 millimeters holes, the result is that shielding is reduced to 8 decibels.

This promptly is the place that EMI restriction character occurs, and does not allow electromagnetic interference go out and obtain influencing each other between the cooling air to become more remarkable.One of principle that the present invention adopts is illustrated by Figure 1A.

Recommending maximum package application to be provided on the shell level provides～15 decibels shielding.Can clearly see not having technical improvement to be difficult to realize from above-mentioned information.Should notice that above-mentioned deterioration even not will consider the loss of sealing place of actual use liner.This only is the borehole that is used for air flows.

The two-dimentional solution that is used for EMI shielding is depicted as and is used for shell, and this shell has usually and is used for the shape that computer and other need the cupboard of the case of electronic equipment assembly of EMI/EMC shielding and other type.Referring to Figure 1A, the main wall of shell is shown, it is the wall of the conductively-closed shell made by electric conducting material, and the size in hole is big more, and the leakage rate of electromagnetic field is big more.At trade name " TORTURED PATH ^TM" in the known embodiment of the invention, by strategically cut, shaping, mold pressing, extruding, punching press and be formed on and adopt any manufacture method of electromagnetism conductive material to reduce the size in hole in basic any application.

The invention provides the EMI shielding solution more cheap than the mode of implementing current techniques.This can finish with the of the present invention various embodiment that realize two dimensions (owing to only can not take place along bidimensional is any, bidimensional is considered) with the material of sheet metal or smooth extruding cutting or punching press.Material can be cast once more with thin sheet metal---and very thin the whole relatively dimension of structure that supposition is cast, cuts or pushes, consider that so-called bidimensional considers to have limited thickness.Along with manufacture process turns to mould pressing process or casting technique, will create even more three dimensional type, or form the metal that exceeds the 2D plane, and use dry technology to create overlapping and further " crooked route ".Therefore, the purpose of this specific embodiment of the present invention is to create aperture.Particularly, the purpose of this embodiment is to create not only little and force electromagnetic noise to change the hole of direction, perhaps passes aperture and make path be difficult to find an exit (therefore, " crooked route ") for EMI.Certainly, this has also influenced electronic equipment in the shell conversely to the susceptibility of the electromagnetic interference that comes from the outside.EMI is that electromagnetic interference refers to what thing is outside to penetrate also how to disturb miscellaneous equipment.But, for purposes of this disclosure, term " EMI " comprises any equipment of shielding user outside and radiation field, and wherein electromagnetic field disturbs product, and this also is the place that the user is subjected to EMI.

Waveguide is discussed in above Figure 1A-1E, and wherein the degree of depth in the degree of depth of raceway groove or hole makes for given hole dimension, and electromagnetic wave comes out very difficult.TORTURED PATH ^TMInvention realizes that with mold pressing or forging type to create the three-dimensional passageway that does not allow EMI to overflow or enter shell, this can comprise waveguiding effect.But, for EMI, be sinusoidal sawtooth square wave preferably with the most effective conceptive crooked route, as shown in Figure 2, and can be the irregular type of any kind of, as shown in Figure 3, no matter type is being the cycle, that the cycle changes in shape or is often changing.But, the present invention needs type not allow the enough electromagnetic waves of maximal pore size to cross material, no matter is inwardly or outwards.Rule one of of the present invention is illustrated among Fig. 2, as " effective length problem ".

Prior art diagram Figure 1B shows the cover plate that uses as the groove with liner.Groove is arranged in the end of case or shell, is filled with liner then---and ring liner is very common means in this case.Then, use lid, force gasket deformation, it will partly adapt to raceway groove then, thereby form sealing.If consider this " crooked route " notion, as discussed below the shown in the present of three-dimensional example be shown, can partly or wholly be shaped and avoid liner by mold pressing, casting or machining, in formed shape, coupling bottom, top.But, matcher generally includes not only the simple waveguiding effect shown in the prior art.

Feature that the present invention uses so-called " crooked route " as one man or is individually created the shape that the structure that is combined together by the improvement metal reduces hole dimension, and particularly those provide the structure of desired EMI/EMC shielding.In a preferred embodiment, shown in Fig. 5 A-14 that discusses below, specific structure is used sinusoidal three-dimensional scallop, and the three-dimensional scallop of this sine elder generation is along the bidimensional shaping and then be configured as normal surface.This normal surface has body widely, and this body forces EMI to rotate through the hole that narrows down because of shaping.Therefore, because around the material of pedestal, (must be the electromagnetism conductive material) because if be not that the words EMI/EMC of this material can not shield effect.Conductive material is used for this structure means that ripple attempts to pass the hole, this hole is too little and can not send or receive the ripple of given frequency for ripple.Change the shape of cutting, might do so once more, with waveguide, consistent, so that the metal that you can have interlocking or have seam as the sealing or the punching press of tongue-and-groove.But be not only to have the seam interlocking, this " crooked route " type is created, and they are fitted to each other, and the convex member is relative mirror image with the concavity member with a gap simultaneously.This does not need the present invention to have close tolerance, because the gap can be less relatively than admissible hole dimension, but relatively large than admissible tolerance.Because this feature of the present invention has 100% reliability in the assembling.

In addition, utilize specific embodiment of the present invention, 100% reliability on the performance is possible, because medium is difficult for compression in time or worsens.In addition, as the liner that may be torn or prune, there is not the liner of possibility plastic deformation without any material yet.For example, beryllium copper may plastic deformation.In addition, no matter any metal gasket, finger piece liner or finger piece support may be in the transportation or be in other situation because unsuitable design or unsuitable processing deform.On the contrary, by creating cutting or, just can not deforming by the two dimension or the three-dimensional cutting of control EMI as the mode of control hole size.Further, in the present invention, do not need the physics contact, therefore do not have tolerance issues, problem on deformation, can not worsen in time, do not have environmental impact yet.Can not make the loosely organized of interpolation.Because the parts that do not have to add, do not have fastener and weld seam, so the invention provides extremely effectively EMI shielding scheme of cost.Can use the material of any plating Anywhere, its sheet metal, punching press and shaping with and/or the situation of some rivets under form, and sheet metal, punching press and shaping with and/or some rivets do not rely on the contact that can not worsen in time and can not produce environmental impact.

Prior art panel cabinet among Fig. 1 C is depicted as by case or by the front and can be suitable for specific embodiment of the present invention.Utilize the preferred embodiments of the present invention of crooked route, generally can for example create the measuring instrument of installing on the panel effectively, as shown in the figure.With the rear side of the cover plate of cabinet pairing, by on the plate of cover plate back, adding TORTURE PATH ^TMShape can make the present invention be suitable for implementing the present invention.Under the situation of sheet metal, another piece sheet metal can be used in the back of washing away cover plate that the front is 90 degree rectangular shapes, and this also makes type suitable aesthetically or satisfactory.After this, cutting material, sine, sawtooth, square wave will be fit to the hole that coupling has suitable tolerance shape once more, and this tolerance is nearly 20/1000ths to 30 inches that meet in the gap of this type.Then, the reverse side of type will around and only overlap another top in the same plane.Existing only is the gap of selecting what type, reduces the effective length around the border all along, and comprises EMI, and enough shieldings are provided.

Referring now to Fig. 1 E,, the graph of a relation between frequency and the gap size is shown.Along with the increase of the frequency of electromagnetic noise, in order to have adequate shielding, admissible hole dimension reduces.Significantly, along with frequency increases, be necessary to make the gap more and more littler.In this manner, if use crooked route, sine curve for example, wavelength can shorten so, and amplitude can reduce, to create for the suitable gap of given frequency.It can be done well, because it is positioned under the admissible half-wavelength that is generally used for shielding scope.For example, distance surpasses to the given frequency in the scope of λ of 20 wavelength 50, removes with 20-50 in that scope.As an example, FCC adjusts up to 2 Gigahertzs, and in that scope, its λ equals 3 microns, and distance equals 0.15 meter 150 microns in other words conj.or perhaps.Removing with 50, is 3 microns, is 7.5 microns and remove with 20.Even under the situation of your bent sheet metal or other abnormal shape, still use 30,000 at an easy rate ^ThAll crooked tolerances are managed in the gap, and this gives the reliability of assembling basic 100%, but are 30,000 ^ThWidth.In addition, if this situation is compared with 3/4ths microns, make to have three times or four times of these sizes, it still remains in 3 microns the scope with that size of four times so.This gap does not allow the adjacent peak or the paddy of visible ripple, therefore effective wavelength may be the distance of traversing substantially, the distance of traversing is not fully from the crest to the crest, but midway from the crest to the centre again to trough, the downward transformation of in ripple from the crest to the trough certain, and still remain within 3 microns the demand.

Very Duan wavelength or very little hole dimension are allowed to by this way, but need be except punching press and form anything.Under the situation of mold pressing, might be tightr.In sheet metal, may be narrower than 30,000.This is very a large amount of, and makes assembling very perfect.It might be reduced to 10/1000ths or 15, and this is no problem.If all cuttings all are held so that they are invisible, its keeps true so, and if it uncertain be the convex and the female member of inaccuracy coupling, as long as they remain in that gap, it can be irregular a little so.For example, crest can be a little near trough, but it can not cause interference, and it in addition may cause the intermediate contact that improves conductivity.

Fig. 1 E relates to the relation between shield effectiveness and the frequency.If you see 10 microns gap, for example, it is illustrated in the about 20 decibels of shieldings that have 10 microns gaps under 1 Gigahertz is possible.For most of electromagnetism encapsulation, under the situation of sheet metal shell, sheet metal shell is difficult to screening can above 20 decibels.In one example, 10 microns seam will provide 20 decibels of shieldings under 1 Gigahertz.In this case, marking wave is easy to the gap is limited in half this size Anywhere.Under the situation of half that size, at 1 Gigahertz, based on this chart, it might be up to 35 decibels, and this obviously surpasses the shielding of any normal cabinet.Certainly, now this based on a hole.Therefore, have necessary usefulness 10 multiplication benefits and reduce it, wherein N be porose quantity.But it adopts 100 holes, and---10 multiplication benefit---makes in the shielding and reduces by 20 decibels.Therefore for 5 microns seams, we are easy to provide, and 1 Gigahertz may approximately be 30 decibels of shieldings.Therefore, even have 100, also still has 10 decibels shielding; The shell that many existence are arranged, they can not surpass 10 decibels shielding.Certainly, in user's Desktop PC, usually more expectation do not lie in cabinet.Therefore, the present invention also proposes a solution, do not have liner, do not have screw, do not have fastener, and have only some rivets, and the performance that passs does not in time worsen substantially, and do not have compressive deformation, has only a gap.

Referring now to Fig. 2,, shown in " effective length ", first model of the EMI shielding principle in the two dimensional application of the present invention, showing LSTD is the old full-length of slit.If it is straight slit, so as shown in the figure, slit will be compared with the length that EMI shields the path, and EMI shielding path is that electromagnetic interference can be seen through the longest sinusoidal air line distance.Length standard and intensity slit may shield the sequence arrangement of the length in paths with 8 to 10 times of EMI.Fig. 3 A illustrates several examples of dissimilar types.You can see triangle sawtooth pattern cutting structure.And, do not allow wave energy to see, so it will seek the most straight line that it can find by crest.Therefore, it is just crooked, far away from being that it can not see the corner.Then, you can see square wave, and after this, you can see ripple, the cutting trace of the clip shape of extremely odd bending.You also can use any cutting that you can imagine.What you attempted to do is exactly to reduce the effective length that can be used as any slit of antenna by electromagnetic interference.Therefore, this can center on the use of IO (sounding like) equipment.This can be used in the sheet metal.This can be used in the extruding cutting trace of Any shape, cutting trace mold pressing, casting, no matter whether it be used for cabinet around the back shroud of model with certain standard package, and no matter whether it comprise the electromagnetism conductive material of EMI around input-output apparatus, any needs with any manufacture method.Cutting profile or mold pressing or the extrusion pressing type of crooked path EMI by tactic reduces effective length, and by extracting and overlapping crooked route enters three-dimensional.But in set waveguide effect, crooked path also is the essence of this notion, and it can be easily introduced into, and does not increase cost or improves complementary forming technique or the mould pressing technology of making complexity to stand.

Fig. 3 A illustrates two-dimentional EMI shielding embodiment of the present invention.Three of various types shown in the diagram are cut traces, and 4 are used as in the alternative embodiment of the first kind.But, the cutting trace can all be one type a cutting trace, and according to suitable type, for example sine wave, square wave and certain so-called Brownian movement type cut trace.Two dimension EMI shielding scheme provides a kind of potential complete EMI shielding scheme with interchangeable embodiment, as long as 4 lines are placed with any serpentine locomotion of avoiding the sinusoidal wave WP of propagation.Fig. 3 A illustrates some examples of dissimilar types.Triangle sawtooth pattern cutting structure is depicted as TST.And can not see crest, so it can seek the most straight line that it can find.Therefore, it is only in corner bent around that it can not be seen.See square wave SW then, after this ripple MWC cutting trace of the clip shape of very strange distortion also is shown.The cutting trace that it should be understood that other type also can use.Purpose is to attempt to reduce the effective length that can be used as any slit of antenna by electromagnetic interference.Therefore, these cutting traces can use around I/O equipment.This can be used in the sheet metal and be used in Any shape extruding, mold pressing, the casting the cutting trace in.The present invention can use, so that it is used for cabinet with standard package, or around the back shroud of model.It can use around input-output apparatus, comprises the electromagnetism conductive material of EMI with any manufacture method or any needs.TORTURED PATH ^TMScheme reduces effective length by cutting, shape or mold pressing or the extrusion shapes of tactic, in addition, enters three-dimensional by extraction and overlapping crooked route.Even with waveguiding effect, TORTURED PATH ^TMBe the essence of this notion, and it can easily be realized with the complementary forming technique or the mould pressing technology that do not need to increase extra cost in the present invention.

How effectively and make and how variously use this principle is shown, Fig. 3 B illustrates replaceable cutting counter body side can have any amount of Non-periodic Type NPP along the seam of shell ENC, to create improved EMI shielding.

Realizing that " effective length " principle to make two-dimentional EMI shielding scheme, is mold pressing, is follow-up shaping or mold pressing then, and it makes convex and these two slits of concavity image together.This realizes with little width and big width that replacedly therefore, littler convex member is installed in bigger concavity component inside back and forth), no matter they are the interrupted types in sawtooth waveforms, square wave, sine wave or these or other type.As shown in the figure, might be not become local worthwhile ground in fact and to reduce that effective length effectively.

Fig. 4 A-4D illustrates the embodiment of two-dimentional EMI shielding scheme, as U.S. Patent Publication No.2005-205209 (U. S. application sequence number No.11/012,896) and U. S. application sequence number No.11/080,385 are quoted from, for all purposes, these two applications are incorporated in this by reference.Fig. 4 A is the top angle view of first example or embodiment, and three sides and one three side fastener ride over three side posts on another downwards, and it from last directly downwards.Then, EMI/EMC is only in the front and back deflection, to overcome the interference between the marking wave.Therefore, might make two U parts together, make TORTURED PATH ^TMSeam is advanced along 6 different edges, so that two three side casees or part are together.

Fig. 4 A and Fig. 4 B illustrate the embodiment that two dimension of the present invention " general " " is once hit " scheme, are used for PC shell and other " case ", and they provide many advantages in the manufacturing process for current method.

Other embodiments of the invention can comprise product purpose, assembling and other manufacturing consideration, for example use " three and three " structure (not shown).The 4 side assemblies of the model #3 of the preferred embodiments of the present invention can be used in " 4 * 1 * 1 " or " 4 * 2 ".4 side assemblies still also can comprise other scheme that Fig. 3 discusses by in the sinusoidal pattern manufacturing of each edge.In two-dimentional EMI shielding embodiment, cover plate all from the top down, up to the side and the back side.Therefore, when uncap, just can expose fully without any the case inside of disturbing, view is not from the top down covered by any material.Therefore, can reach case fully.In addition, as four sides and the both sides of top, also can do like this as a whole front part.Except the assembling of three parts, in two parts assembling, also can do like this.Under the situation of " 5 * 1 type " embodiment, this structure is very simple.This embodiment implements in 3 * 3 passage casees of two parts assembling.

At most of embodiment that two-dimentional EMI SHIELDING CALCULATION machine shell of the present invention is used, the present invention needs simple punching press or the cutting in the sheet metal (specific embodiment), and the manufacturing that is shaped.The present invention is inexpensive than " spoon ", and does not need the physics contact, and therefore bigger reliability is provided.

Refer again to Fig. 4 A, show the model of the preferred embodiment of counter body structure.The cabinet that the RU17.5 inch is wide, about 11.5 inches dark, this has represented the structure of the type species that is used for 19. inches stands of standard, admissible 17.5 inches wide and RU height.TORTURED PATH ^TMSeam is advanced along the side.This is a front isometric view, watches the right hand corner of front in the prospect.Seam will be along the top of the top of two sides, back, near behind two of corner vertically the corner advance downwards, but at rear side.All 4 sides all center on panel, but basic neither one illustrates forward part.Therefore,, do not have the hole to be positioned at the front,, and have only some things open to discussion although these may only improve aesthetic feeling on certain point from aesthetic.

This class hole can ergonomics ground, aesthetic the use, perhaps they can be used to the sign of the company of cutting, if do suitable.They can be used to realize TORTURED PATH ^TMShape passes air in the mode that helps to control EMI.Therefore, the particular shell shown in Fig. 4 A and Fig. 4 B exists at the bottom of 4 side groups, and in the flat type structure, it can be the case of 4 sides.It will make TORTURED PATH ^TMShape is around the periphery of all 4 sides.In the back and can be loaded onto between the two side portions of cover plate, can turn up and with the side rear board of packing into.Being fastened in each only needs a rivet, and selectively needs a rivet in each of corner in the back.So process will be punching press, shaping, and two rivets are used for total assembling, do not have liner, do not have weld seam, do not have screw, and all these can both be finished in pre-plated material.

Fig. 4 A also illustrates the preferred embodiment with the independent lid that can lift down, and this embodiment utilizes TORTURED PATH ^TMAssembling conversion back and both sides.These specific structures make and are easy to add joint, so that the top is fixed to substrate, perhaps can use the countersinking screw, avoid " interruption " problem from electromagnetic point, and this also can increase electromagnetism advantage of the present invention.This is opposite with the modular housing situation with straight slit, in slit, is necessary can allow the identical distance in hole to have screw with maximum.Utilize this structure of the present invention, distance can increase TORTURED PATH ^TMEMI/EMC shields scheme, and also can be used for structural intergrity, and/or only is used for shell, to keep shell.

In the structure shown in Fig. 4 A and Fig. 4 B, front end or front panel change all 4 sides, and can be beaten and control it.In this manner, might in fact lid be put down, be put in the structure, in fact it hooked rotation with certain tongue-and-groove hook.It might be reduced, and the strictness of mooring all and front panel assembling.Basically, next can be punching press, shaping, friction fit, and next only be that lid is in place.Side and substrate can be stayed by the nose cone system.In this manner, whole assembling all together.Though this process can not provide the integrality of all structures that all product purposes all need, in many cases, it is suitable really.The many structures that can finish it are arranged.EMI can be comprised, and the primary element securing member eliminates weld seam with low-down cost and accent is complete, and enhancing heat is provided extraly.Therefore, opening the more ability of porous owing to have now, thus can reduce cost in addition, and strengthen heat, and environmental friendliness, without any interpolation.This 100% can assemble and 100% reliable, can not worsen in time simultaneously.Simple mooring is arranged.This can be 1/4th time limits, but in this case, simple mooring---can be used for the screw that spring is housed of the photoelectromagnetic nut of cover plate back, pivot around sidewall.These one of at the front and the two ends of cabinet, on a side of cabinet, separately prune, and just be locked on another.

Aesthetic, needs cut trace along the type of seam TPS in front.Can see from above, when it during along the advancing up and down of forward edge, end view is shown.This diagram proof has the turn Fastener of the captive fastener that is used for install bin.It can be positive 1/4th circle locks, and wherein blade is in the back of cover plate.Under the situation that does not deviate from the spirit and scope of the present invention, simple screw or any way of suitable locking device can use.Enclosure system can extend from very simple cost assembling means the most to one's profit, high reliability is provided simultaneously, and need not assembles or weld with regard to the energy minimization assembly cost in fact.This can finish with any material with any manufacture method---any electromagnetism conductive material and any manufacture method.In casting, mold pressing etc., only by mold pressing or casting just might realize the three-dimensional bending path simply.In extruding, TORTURED PATH ^TMBe cut into the shape of pushing and being used for air flows and EMI container.

Fig. 4 C is the end view that is used for the two-dimentional EMI shielding scheme of counter body.And, from the top, have only a line to pass shown top face, its just with the bottom on identical.A line is arranged in the side, also in front, the 1-U that advances up and down dimension, both in front also in the back, this was all that can see from the side.Along the top edge of side, and in the side of top edge, two seams as seen, near the corner of the back of two edges.The big view such as grade of rear corners also is shown in Fig. 4 B, and TORTURED PATH ^TMThe edge is along top and side, and down to the rear corners of the substrate of visible cabinet, that corner is reduced in the two edges of lid then.

If carefully checked this corner.The projection that formation is arranged at the closure place that preceding right corner falls, these projections on a face, become waist and rise and the another side back wall around.In this case, there is one from being positioned at the lid formation of sidewall.Sidewall is in the back of leading flank, and leading flank is positioned at the back of lid, has formed " three parts converges " or locking corner.These three are together, but their stack ups and one be positioned at another below, so they are not interlocked with not using any securing member, this has further reduced manufacturing cost.In each case, utilize around the slit length of these joints (perhaps whether it is around the cover plate that is used for mounting screw), length is maintained at the allowed length of frequency whatsoever to 2 Gigahertz EMI shielding or selection control.Hole on the top can provide extra flexibility just, is used for this embodiment of the present invention, and allows rivet to be used to connect lid and substrate.In not having the structure of removable lid, can use the countersinking screw.In this case, remove and take away lid, take away the front, take away lid and can reach the inside of case.Shown in this rule, of the present invention no matter have specific attraction to be characterised in that be what feature is in an embodiment of the present invention around TORTURED PATH ^TMScheme can realize: the EMI that keeps minimum aperture length and control necessity in view of the above as follows.

Diagram illustrates 17.5 inches respectively (in a preferred embodiment, have only dimension to depend on that product uses) the same preceding corner of 1-RU case, and it illustrate otch joint UTB and LTB how each other eyelet no matter be the thing of any tongue-and-groove type with interlocking and how to make so that whole assembled is in the same place.Because outstanding being assembled with that minimizes fastener helps aim at cabinet, and makes electric contact together, be not used for it of EMI although do not depend on.And it uses the mooring fastener herein, both at screwed or hold-down screw, and has photoelectromagnetic nut PN, and this is installed on the back of supporting cover plate MP.In case this illustrates punching press and is shaped, feature is exactly very simply and with low-down cost to be provided.This is that suitable effective and efficient manner is used for making, assembles and keep EMI, and it is low cost, high-performance and outstanding solution.

Fig. 4 A-4D illustrates the scheme that is provided in the counter body application of the present invention and can easily realize with all main manufacture methods, comprise: punching press, laser cutting, casting, extruding, mold pressing etc., in each manufacture method, almost each (above detailed description) is beneficial to and can uses.Further, because there be " gap " between matching component, the tolerance in the manufacture process is " freedom " as much as possible.The further emphasized reliability of tolerance freely, and guaranteed so that generally speaking, do not have matching problem away from the highest possible output of the part of making line.Further, " once hit " two-dimensional schemes and can improve encapsulation flexibility and hot property.For example, this creationary scheme not only can be used for the cabinet manufacturing, also is used for module, FRU, connector and other needs the I/O parts of EMC protection/shielding.This creationary scheme cutting profile, to be provided for the big open area of air flows, this scheme can influence the EMI performance sharply, and can obtain the low cost of manufacture high conclusion of hot property simultaneously.

From improved EMI shielding (leaking and protection) angle, if cut with maximal efficiency in the hole, do not have the EMI of antenna to need radiation so, heat scatter (wish not can with the EMI performance be cost).This notion can be extended to industrial design, begin to adopt these cutting traces then, and make them become the part of industrial design.Heat is similar to improving, and reduces cost with respect to liner, screw, welding etc. and be 100% reliable.Can never worsen reliability in time.When these two things put together, there is air gap.The liner that does not have compressive deformation.Beryllium copper is distortion or crooked not.The fibre gasket that separates does not separate with foam.They are pruned, and they separate, and they utilize adhesive or similar thing to bond together.When they were pruned, they may be failed.Along with the time is provided with compression, therefore, they will be along with the performance loss of time.Beryllium copper is illegal in Europe.Its bending and spoon bending, and they depend on the physics contact.Yet this does not rely on the physics contact.In the useful life of entire product, it is all 100% reliable.In addition, if gap size is provided with well, promptly gap size is the twice of the sum of geometric tolerances, will be combined together in turn so, and the assembling of can not failing is provided, and does not assemble defective in fact.This is designed to zero assembling defective.Always assemblnig, and be 100% reliability.

The twice physical dimension is the normal sum of geometric tolerances.If the gap of twice is arranged,, 100% safe clearance is arranged all so for any assembly error.In this embodiment, unlimited safety and unlimited reliable in assembling.There is not assembly error.Two-dimentional embodiment of the present invention provides the scheme that does not have waste or failure in the assembling.Panel can bonding or explosion in face of the user.Can get rid of the inspection behavior, and therefore cause reducing cost.Because to environment zero influence, so environmental friendliness.Can use all pre-plated materials, this is very important.Can use pure pre-plating, and no longer be concerned about what electroplated the back.Retention problems and environmental problem that all are relevant with cost all are eliminated.For all plating, must take all sheet metals.Be necessary to transport a part and electroplate, obtain all plating and packaged, therefore can not abrade.But, in this case, this can finish with 100% pre-plated material.This is the process of unique transportation and assembling.

Two-dimentional embodiment of the present invention makes the simple and cost reduction of assembly technology manufacturing, because the welding that there is no need or any follow-up operation.When welding is process a part of, also must be that electroplate the back, because can not welding pre-the plating.To destroy plating.Otherwise, if welding is arranged, be that electroplate the back then, so whole thing must concrete plan.Problem is that if if the planning that has the back to electroplate has any ruffle, the result is detained so, and delay has been arranged, and just has oxidation source.Therefore, if plated material is detained, it just will be arranged in the gap so, and perhaps it can not enter.It or be detained, perhaps can not permeate, and if enough safe oxidations are arranged, corrosion is so just arranged.In this embodiment, all these is eliminated.

Referring now to Fig. 5 A-13,, " 3-D case " or three-dimensional EMI shielding scheme are shown realize.The preferred embodiment of three dimensional realization of the present invention as mentioned above.

Fig. 6 and Fig. 7 illustrate five the formula casees of creative shell in a preferred embodiment and the different views of lid respectively.Referring now to Fig. 6,, helps to consider some other planes that form by three dimensional type in lid and case.For example, other " XY " plane is arranged, its bottom that is marked with " plane X Y (#2) " by the male member spheroid among the case FSE forms, and the top of male member spheroid is marked with " plane X Y (#3) ".For the purpose of considering the needed EMI shielding of electronic equipment casing, in view of each seam, also can consider other plane, for example be formed on the YZ and the XZ plane of the infall of case FSE and cover plate/lid FL.YZ plane from the seam of each joint of case FSE and lid FL forms comprises plane YZ (#A) and YZ (#A) ' respectively.The plane that also exists inside from the three dimensional type IP middle part of shell (near) to form, this can be the inner plane of convex XZ#3 and near the part of inwall, i.e. XZ#2.XZ is similar on 26S Proteasome Structure and Function with the YZ plane, forms because they all are width and length by shell.For the diagram purpose, describe the plane, and the plane is not considered as limiting the scope of the invention or may the using of various embodiment.

Table 6: the plane that forms by the three dimensional type in five formula shells

Referring to Fig. 7, the plane that is formed by " concavity " scallop or part spheroid is shown.For the purpose that electromagnetic interference shield is provided, Fig. 7 illustrates lid and three correlation planes and the front view on " the sub-plane " that become by concavity scallop or 1/4th spherical.In a word, in five formula shells, there is little gap on these planes with the relative part with convex three dimensional type.But, in certain embodiments, the XY#A plane should be very consistent with the XY#S plane.In alternative embodiment (below in Figure 10, discuss), can the adjusting play, heat being provided or making advantage, but may jeopardize some EMI shieldings.The terminal use of alternative embodiment can have specific trading off at " gap " for different electronic equipment casings.

Table 7: the plane that forms by the three dimensional type in the lid

The plane	Describe
		XY#S	By the plane that the seam at the junction point of lid and five formula shells forms, the top of parallel cover plate
XY#
	4	The plane that forms by " bottom " of concavity scallop, and parallel XY#S
XY#
	5	The plane that forms by " top " of concavity scallop, and parallel XY#S

XZ#S	The plane that forms by the width of cover plate, and perpendicular to lid surface
		XZ#
4	The plane that forms by the innermost point of concavity scallop, and parallel XZ#S plane
		XY#
5	The plane that forms by the outermost point of concavity scallop, and parallel XZ#S plane
		YZ#S	The plane that forms by the length of cover plate, and perpendicular to lid surface
YZ#
	4	The plane that forms by the innermost point of concavity scallop, and parallel YZ#S plane
YZ#
	5	The plane that forms by the outermost point of concavity scallop, and parallel YZ#S plane

Referring to Fig. 8 A, the details of " concavity " three-dimensional structure in the cover plate is shown.Fig. 8 B illustrates the details of " convex " three-dimensional structure in five formula casees.As indicated above, " gap " or " coupling " between the spatial mode of projection and the recessed spatial mode can be different between specific embodiment of the present invention according to end user's needs.

Referring to Fig. 9 A and Fig. 9 B, illustrate and " crooked chamber " to be used to provide carrying out the operation of electromagnetic interference shield inside and outside the shell.Mold pressing that these are interesting or cast moulding do not allow ripple to propagate usually, and continuous reflection also finally is absorbed, because it attempts to pass the plane (referring to above plane #A) of interface or seam.Because the gap between each in these all is not enough to form the antenna on the case outside, perhaps by this gap, electromagnetic interference is absorbed basically fully.In this certain illustrative, shown in Fig. 9 B, lid has cover plate, and therefore the waveguiding effect from cover plate is arranged.In a word, there is very short hole waveguiding effect is provided for " crooked chamber " hole itself.By shortening hole dimension and creating crooked chamber, waveguide and waveguide cover plate are worked together.As shown in the figure, EMI do not have liner around the lid, do not have emission the cabinet of securing member come down to cannot.Lid only by nail (or other fixing means) in some suitable positions, no matter need what or replacedly, pin in other position.Preferred embodiment is very simple, does not have securing member and good EMI protection container in fact.

The function diagram of the EMI protection that is provided by specific embodiment of the present invention also is provided Figure 10.Electromagnetic interference EMI PROP propagates along all directions from the electronic equipment (not shown).Gap between case and the lid GAP is width g, and can be different with each embodiment.Selectively, gap adjusting structure GTA can be used for improving ventilation by increasing gap g.So certain embodiments can be different, enough be used for different terminals and use.As seen, the plane that forms by actual seam XY#1 be " on " plane, wherein the structure formation of concavity/convex interface is positioned at XY#S+ (this rises and falls) between XY#2 (4) and XY# (3).In other embodiment (not shown), the plane that is formed by seam can be passed by concavity/convex interface and form the plane, and this depends on terminal use's complexity and needs.

Figure 11 A-11C be respectively among the basic embodiment five formula shell FSE and from the angle, the detailed view of the inner IP of top and side angle.

It should be appreciated by those skilled in the art, can use other three dimensional type, single cube structure for example shown in Figure 12, or double cube structure shown in Figure 13 do not limit the scope of the invention or possible embodiment.Specific three dimensional type provides EMI shielding advantage, and this must weigh with the manufacturing advantage that is provided by other type.So 1/4 spheroid shown in Fig. 5-7 will provide one type advantage, and for example Figure 12 and three-dimensional cubic build shown in Figure 13 will provide and simplify the advantage of making.

Figure 14 illustrates " mixing " of the present invention embodiment has merged the two and three dimensions feature, so that combination or be provided for the electromagnetic interference shield of electronic equipment casing individually.

Claims (10)

1. shell that is used for computer or other electronic equipment comprises:

The electromagnetic interference shield of making by electric conducting material (EMI), wherein said shell has six faces that adopt electric conducting material, have at least two faces to be configured as in wherein said or cutting forming for having three-dimensional widely multiaspect wave attenuation part, described three-dimensional widely multiaspect wave attenuation partly covers at least a portion width of place face and propagates to obstruct the EMI ripple, thereby partly provides sufficient shielding by described wave attenuation.

2. shell as claimed in claim 1, wherein said volume wave attenuation part edge is away from the direction projection of the inner space of described shell.

3. shell as claimed in claim 1, wherein said volume wave attenuation part edge is recessed towards the direction of the inner space of described shell.

4. shell as claimed in claim 1, wherein said volume wave attenuation partly are drawing, die forming, that be shaped, extrusion molding or cast form.

5. shell as claimed in claim 1, wherein said volume wave attenuation part is extended along the edge of the upper surface of described shell.

6. shell as claimed in claim 1, wherein said volume wave attenuation partly comprises a plurality of lug bosses, described a plurality of lug bosses separate the frequency range that needs shielding to weaken with suitable distance.

7. shell as claimed in claim 6, wherein said lug boss comprises the part of spheroid.

8. shell as claimed in claim 6, wherein said lug boss comprises cylindrical part.

9. shell as claimed in claim 1, wherein said electric conducting material is a conducting polymer.

10. one kind provides abundant EMI/EMC the counter body of shielding, comprise a plurality of at least, described a plurality of at least face is configuration like this: then form normal surface again by being shaped along bidimensional earlier, form sinusoidal multiaspect said three-dimensional body, make described normal surface have body widely, this body forces described EMI to rotate through the hole that narrows down because of shaping, and wherein said material around cabinet is made by the electromagnetism conductive material.

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