IL260607A - Enclosure for protecting its contents from electromagnetic waves - Google Patents

Description

1 Enclosure for protecting its contents from electromagnetic waves Field of the invention The present invention belongs to the field of enclosures/packing means/housings intended for shielding electric or electronic equipment from electromagnetic radiation which may be called EMI/RFI.

Background of the invention Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical/electronic circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data. Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares, and auroras (Northern/Southern Lights). EMI frequently affects AM radios. It can also affect mobile phones, FM radios, and televisions, as well as observations for radio astronomy.

Presently, EMI/RFI protection is usually reached by manufacturing a box being solid, machined, welded or casted. Alternatively, the box may be assembled from machined/casted panels attached to one another with bolts and using EMI/RFI gasket/s between them.

A solid box provides a good EMI/RFI and water protection if needed, but it is expensive especially when the enclosure's size becomes considerable.

US2015042218 (A1) describes a housing for electronic devices. The housing is assembled from several components. The components form a continuous closed section gasket channel there between. A suitable fluid is injected into said channel to form a gasket between the components.2 Though a box assembled from panels is usually cheaper to manufacture then the solid box, it demands a gasket which is usually a weak link of the design (due to possible water leakage). This technology is also heavy, since the use of bolts requires quite thick panels for tapping the bolts.

Another approach to solving the discussed problem is using expensive electrically conductive adhesives for EMI shielding enclosures.

For example, US5763824 (A) describes a Faraday cage; CN107018647 (A) discloses a multilayer cabinet, while both of the references require an electrically conductive adhesive for EMI/RFI protection.

Object and summary of the invention The main object of the invention is to propose an improved, new EMI shielding housing, which would be less complex and less expensive than those known from the prior art.

The additional object of the invention is to make the proposed housing waterproof.

Yet an additional object is to provide a method for manufacturing of the inventive housing.

According to one aspect of the invention, the above object may be achieved by providing a housing/enclosure for shielding its contents from electromagnetic waves, the housing being assembled from conductive panels attached to one another using non-conductive adhesive, in the housing, L-shaped contact surfaces are formed wherever the conductive panels are attached to one another, thereby creating overlapping, L-shaped conductive seams secured by the non-conductive adhesive.

The L-shaped contact surface should be understood as a generally L-shaped one, i.e. formed by two angularly spaced planes which create there-between an angle.

Typically, the angle is close to 90O, but may differ from 90O.3 The Inventors have arrived to a conclusion that any of the proposed L-shaped conductive seams, created between a pair of panels, is capable of creating an obstacle to electromagnetic waves in two perpendicular surfaces and therefore is able to block propagation of electromagnetic waves almost in any direction in case such waves enter a gap between the pair of panels.

Since the proposed housing is supposed to have two or more such L-shaped conductive seams which will definitely block the electromagnetic waves in additional directions, the housing will be thus protected from electromagnetic waves having any direction.

The above definition of the housing covers a number of options to create the L-shaped seams, some of them will be briefly mentioned as a, b, c and then described below in more detail as PPES, PPLS, PBLS and PBRS. a) L-shaped seam may be created if one or more of the panels are L-shaped themselves. b) L-shaped seam may be created by connecting the panels by a bonding element. c) Yet another option does not require that a panel and/or a bonding element have an L-shaped profile. An L-shaped contact surface (and seam) may be created at the place of contact of two panels, where edge of one of the panels is inserted in a groove made in the other panel so that two perpendicular or close to perpendicular contact surfaces are created between the two panels.

For options a) and/or c) the panels may be preliminarily designed so as to fit to one another by forming the desired L-shaped contact surface there-between. That may be reached: - by manufacturing one or more of the panels so as to have an integral L- shaped extension at one or more of its edges, and/or - by manufacturing one or more of the panels with suitable grooves at their edges. 304 The proposed housing may be pre-assembled using a number of auxiliary bolts/fasteners or using an auxiliary frame/box/envelope which would support the housing from inside and/or outside. The housing may then be "glued" by the non- conductive adhesive along the L-shaped seams between the panels.

For option b), the housing may comprise one or more conductive bonding elements.

For example, the bonding element may have a generally L-shaped profile.

In that case, the housing may be assembled with the pre-assembling step, and/or as described below.

The housing may be assembled from the conductive panels attached to one another using said one or more conductive bonding elements and the non-conductive adhesive, wherein said conductive panels and/or said one or more conductive bonding elements are configured so as to form said L-shaped contact surfaces wherever attached to one another, thereby creating said overlapping, L- shaped conductive seams secured by the non-conductive adhesive.

The bonding elements may have various shapes. In one example (as mentioned above), the bonding element may have a generally L-shaped cross-section to form the L-shaped contact surface with the conductive panels.

In another embodiment, the bonding element may serve as a rim forming the L- shaped contact surface when being inserted in a suitable depression formed in two or more conductive panels to be joined.

In one specific embodiment, the housing is designed for EMI/RFI shielding.

Dimensions of the L-shaped seams may be selected so as to provide mechanical rigidity of the housing by the minimal area of said L-shaped contact surfaces.

However, the above-mentioned housing may be configured so that the dimensions of the L-shaped contact surface (for example, the minimal overlap of each half of the L- shape) are selected based on the wavelength of one or more of the electromagnetic waves to be blocked by the housing.5 The proposed housing may have various shapes. Typically, it is a rectangular box made from rectangular conductive panels, so it may have mutually perpendicular L- shaped overlapping conductive seams.

In the proposed housing, the L-shaped contact surfaces may form one or more kinds of the overlapping conductive seams: Panel to panel, Edge seam (PPES), wherein two edges of two conductive panels to be joined meet to make a corner so that the edge of one panel enters into a suitable depression provided along the edge of another panel. In such a seam, two mutually perpendicular surfaces of one panel come into contact with suitable surfaces of the depression provided in the other panel, thereby forming there-between the L- shaped contact surface and the PPSS; Panel to panel, L seam (PPLS), wherein at least one of two conductive panels to be joined is provided with an L-shaped extension at its edge, and wherein said two conductive panels meet to make a corner wherein the L-shaped extension of one panel comes into contact either with an edge or with the L-shaped extension of the other panel, thereby forming there-between the L-shaped contact surface and the PPLS; Panel to Bonding element, L seam (PBLS) wherein two edges of two respective conductive panels to be joined meet to make a corner, and wherein said corner comes into contact with a bonding element having a generally L-shaped cross­ section and placed along said edges, thereby forming the L-shaped contact surface and the PBLS between said two conductive panels and said bonding element; Panel to Bonding element, Rim seam (PBRS) wherein two edges of two respective conductive panels meet to make a corner and wherein said two conductive panels are assembled to one another by a rim-like bonding element entering into a suitable depression provided along other edges of said panels, being perpendicular to the corner, thereby forming between the panels and the rim-like element the L-shaped contact surface and the PBRS.

As understood from the above, the housing may be assembled without conductive bonding elements. However and quite preferably, the housing may be assembled by using one or more conductive bonding elements for forming better overlapped seams.6 The EMI shielding housing may be made water safe by using the non-conductive adhesive being waterproof.

The proposed housing may be essentially lighter and less expensive than regular EMI shielding ones, in case the panels (and preferably the bonding elements too) are made from a machined metal or from metal sheets.

It should be noted that the panels may be thinner than those used in conventional techniques, the panels just have to be capable of providing sufficient rigidity of the housing.

Therefore, the panels may be selected among available conductive panels, as thin as possible to ensure rigidity of the housing. If necessary, the rigidity and the minimal thickness may be calculated based on the required volume of the housing, but will not be discussed in the present description.

As mentioned above, the bonding element may be made, for example, in the form of a profile having a generally L-shaped cross-section. It may be made of metal sheet and be attachable to at least one of the conductive panels by said non-conductive adhesive.

If the housing has a circular or the like base, the profile of the bonding element may be curved. In one specific example, the profile may be a linear L-shaped profile.

The own contact surface of such an L-shaped bonding element may be at its "outer" corner (which may be defined as formed by two surface portions creating the angle around 270O there-between). However, the own contact surface of the L-shaped bonding element may be its "inner" corner formed by two surface portions which form the angle around 90O there-between. In any case, the L-shaped bonding element forms the L-shaped contact surface with the panels to be joint.

Alternatively, at least one of the conductive panels may have an L-shaped edge (or have an integral L-shaped edge extension).

Further, at least one of said L-shaped contact surfaces may be provided with an engraved pattern (comprising one or more grooves having an arbitrary configuration),7 so as to improve adhesion of the panels and/or bonding elements to be connected when a layer of said adhesive is placed on said L-shaped contact surfaces.

The adhesive may be preliminarily spread on the contact surface of the bonding element and/or on the contact surface of the panel of interest.

Indeed, when the L-shaped contact surfaces to be joined are provided with the adhesive and being pressed against one another, the adhesive will be accommodated mainly in the grooves of the engraving, though leaving some remainders of the adhesive around them. Those grooves will ensure hermetic interconnection of the contact surfaces. In case the adhesive is waterproof, the housing becomes waterproof too.

It goes without saying that the engraved pattern may be provided on the conductive panels and/or on the one or more bonding elements.

For better results, the engraved pattern may be provided at each member ( panel- panel, panel-bonding element) forming a specific L-shaped contact surface, thereby ensuring interconnection between the parts to be bonded to one another, when a layer of the non-conductive adhesive is placed there-between.

As mentioned above, the housing may have any geometrical shape, for example a prismatic shape or a cylindrical shape.

The housing may be open at one of its bases.

The conductive panels of the housing may include a bottom panel and at least one side panel connectable to the bottom panel.

The housing may be provided with a lid (for example, a conductive lid) securable to the housing in any manner which will not be discussed in details in this description.

In a first specific case, the lid may be shaped so as to have L-shaped margins overlapping side panel(s) of the housing.

In a second specific case, the lid may be shaped so as to have a rim-like portion entering edges of side panel(s) of the housing.8 In one embodiment, the lid may be securable to the housing using said ( or slightly modified) non-conductive adhesive and thus playing part of an additional bonding element.

Thus, the "first case" lid may be connectable to the housing as the bonding element having the L-shaped cross-section.

The "second case" lid may be connectable to the housing as a rim-like bonding element.

In another case, the lid may be securable to the housing using a separate bonding element (similar to said one or more bonding elements) and using the non-conductive adhesive.

The slightly modified adhesive used for the lid may be an adhesive having its melting temperature lower than the non-conductive adhesive used for other seams. For example, the lid adhesive may melt at of about 70OC which is much lower temperature than say 130OC at which main seams of the housing would melt. In such a case, the lid would be easily removable from the housing by heating it till said lower melting temperature.

According to a second aspect of the invention, there is provided a method for manufacturing of a housing capable of shielding its contents from electromagnetic waves, for example from EMI/RFI.

The method may comprise: providing conductive panels (for example manufactured by machining, or made from a sheet metal) suitable for assembling by forming L-shaped contact surfaces at least there-between, assembling the housing from the conductive panels using a non-conductive adhesive for securing said L-shaped contact surfaces, thereby creating overlapping, L-shaped conductive seams secured by the non-conductive adhesive. 309 The method may further comprise steps of: providing one or more conductive bonding elements (for example having an L-like cross-section), wherein said conductive panels and/or said one or more conductive bonding elements are configured so as to form the L-shaped contact surfaces wherever attached to one another; assembling the housing by securing said conductive panels to one another, using said one or more conductive bonding elements and the non-conductive adhesive preliminarily placed at said L-shaped contact surfaces.

As mentioned, the method may comprise a preliminary step of pre-assembling the housing, using a number of auxiliary fasteners or an auxiliary frame. The housing may then be "glued" by the non-conductive adhesive along the overlapping L-shaped conductive seams formed between the panels.

In case of pre-assembling the housing with bolts/fasteners, then method may comprise a final step of sealing the orifices left by the removed/ non-removed bolts, for example by using a conductive adhesive.

If the method comprises placing the panels into the frame (a model box) to pre­ assemble them there-inside, the frame may be further fit closer to the assembled housing by rubber inserts, Velcro fasteners or the like.

It should be noted that no injection of the adhesive is required in the proposed method. The adhesive may be freely spread in advance on the L-shaped contact surface/s (of specific conductive panels and/or specific conductive bonding elements).

The method may comprise a preliminary step of providing an engraved pattern on at least one said L-shaped contact surfaces.

For example, at least one bonding element may be provided with a first engraved pattern (comprising one or more grooves) on its contact surface, so as to be connectable to said one or more panels when a layer of said adhesive is placed between the bonding element and said one or more panels.10 Alternatively or in addition, at least one conductive panel may be provided with a second engraved pattern on its contact surface.

The method may further comprise providing the box with a removable lid adapted to be adhered to the housing by an adhesive having its melting temperature lower than said adhesive used for other seams of the housing.

Such a lid may be then removed, if needed, by heating the box to the temperature of melting the seam of the lead. Other seams will still remain untouched i.e., the housing will preserve its protective properties.

To the best of the Applicant’s knowledge, nobody in the prior art succeeded to resolve the task of creating a cheap and light EMI shielding housing in the manner proposed on the present patent application.

The invention will be further described in detail as the description progresses.

Brief description of the drawings The invention will be further described and illustrated with the aid of the following non-limiting drawings in which: Fig. 1 illustrates a perspective view of one embodiment of the proposed bonded protective box (housing, enclosure).

Fig. 2 illustrates an exploded view of the box shown in Fig. 1.

Fig. 3 illustrates a cross-sectional view of one embodiment of the proposed overlapping conductive L-shaped seam, formed using a conductive bonding element attached to conductive panels of the proposed box.

Fig. 4 illustrates a cross-sectional view of a slightly different seam formed by a conductive bonding element attached to slightly modified conductive panels of the proposed box, where one of the panels has an engraved pattern on its contact surface.

Detailed description of specific embodiments11 Fig. 1 shows an exemplary embodiment 10 of the bonded EMI/RFI protected box (without a lid).

The box 10 is assembled from conductive side panels 12 and a conductive bottom panel 14 (not seen in this figure), using conductive L-shaped bonding elements 16 ( one of them, is seen in this picture) which form L-shaped contact surfaces between those elements 16 and the panels 12. The type of a conductive overlapping seam formed by the bonding elements 16 with the panels 12 is PBLS ( Panel-Bonding element L Seam). The upper frame/rim 18 may be understood as a conductive rim­ like bonding element. The type of seam formed by this rim with the panels is PBRS (Panel-Bonding element Rim Seam) Vertical seams between side walls of the box 10 are created between the panels 12 themselves without any bonding elements. Such seams are also overlapping conductive seams formed by L-shaped contact surfaces which will be discussed with reference to Fig. 2.

Fig. 2 is an exploded view of the box shown in Fig. 1.

The four side panels 12 include: - two panels 12A, each provided with the bonding L-shaped element 16 at its lower part, for example adhered to 12A by a non-conductive adhesive, and - two panels 12B, each having the perimeter being thinner than the main thickness of the panel, so as to engage edges of the neighboring panels 12A and 14 in their suitable depressions, when assembling the box ( the PPES, i.e., Panel-Panel Edge Seam is used here).

For assembling the box 10, the bottom panel 14 may be placed under the bonding element 16, as further shown in Fig. 3 (i.e., by using the contact surface at the "outer" corner of the element 16). It should be noted, however, that the bottom panel may be placed above the element 16, if suitably designed to support the bottom panel 14. In both cases, the PBLS seam will be used.

Alternatively, each of the panels 12A may be manufactured as an integral generally L- shaped panel (or a panel having an L-shaped edge extension) and may thus serve for making L-shaped contact surfaces with other panels. (The PPLS seam will be used in such cases.)12 As mentioned above, there may be an alternative option to assemble the box 10 by inserting the bottom panel 14 into the "inner" corner of the L-shaped element 16. If the panel 12A is integral with the L-shaped element 16, it will support the bottom plate 14 from beneath (by using the seam PPLS).

The rim-like bonding element 18 is shown separately in Fig. 2.

Fig. 3 shows a cross section of one optional joint (seam) for assembling the proposed EMI shielding enclosure. This seam is a so-called PBLS one (Panel-Bonding element L- Seam), which is the most illustrative example of overlapping L-shaped conductive seams which are used in this invention.

In the cross-section, the conductive side panel is 12A, the bottom panel is 14, and the conductive bonding element 16 having a generally L-shaped cross-section is adhered to the panel 12A and 14, using the contact surfaces on the "outer" corner of the bonding element 16. It should be noted that the bonding element 16 and the panels 12A and 14 form overlaps 21 by their contact surfaces (when connected to one another). These overlaps 21 form the overlapping L-shaped conductive seam that ensures the EMI-shielding properties of the enclosure. Owing to the reliable conductive overlaps, the adhesive may be non-conductive since it is not critical for overlapping conductive seams, including such as the joint between panels 12A and 14. Other joints of the box may have smaller dimensions, but are still constitute the proposed overlapping, conductive L-shaped seams.

For all such seams, dimensions of the overlapping L-shaped contact surface may be optimized so as to provide rigidity of the housing. Moreover, the minimal contact surface (for example, the minimal overlap of each half of the L-shape) may be selected according to the wavelength/s of the electromagnetic radiation which is to be blocked by the protective housing.

In all such seams a non-conductive adhesive is used to provide the mechanical connection and, optionally, water/air proof insulation.

Fig. 4 shows a cross-section of a slightly different option to connect panels of the proposed box to one another.13 The bottom panel 14 is attached to a side panel 12C using a conductive bonding element 16A (similar to 16).

The panel 12C, at its contact surface, is provided with an engraved pattern comprising two grooves 22. When adhesive 20 is spread over the contact surfaces of panel 12C and/or over the bonding element 16A, the adhesive will be accumulated in the grooves when the parts are pressed against one another. The adhesive 20 in the grooves 22 will then provide a securing and insulating layer between the panel 12C and the bonding element 16A. The other portion of the contact surface of the element 16A may be attached to the panel 14 by adhering but without providing any grooves.

It should be noted that the engraving pattern may be provided not only on the side wall. Alternatively or in addition, it may be made on the contact surface of the bonding element 16 (16A).

In other words, a) the adhesive may be placed on at least a portion of the L-shaped contact surface, b) the proposed engraving may be made in one or both of the bonded parts. The provided engraved grooves may be filled with the spread adhesive. Unlike many known methods, the proposed adhesive application is simple since it does not require injection of adhesive into specific channels. The engraving itself may be done by a laser cutting machine which makes the process simple and cheap.

Since the adhesive is not injected in the proposed method, the engraving can be done in different ways and in various complex shapes (which cannot be done with the injection process since there the adhesive needs to flow inside a specific channel).

Various complex shapes/patterns may be used in order to improve quality of the obtained seams.

The Inventors have presented the improved enclosure which is preferably assembled from panels which can be manufactured by machining or from metal sheets (which are cheap technologies).

The assembling of the complete box is done by bonding the panels together.

The bonding is done by a cheap non-conductive adhesive. The EMI/RFI protection at the attachment lines is ensured by overlap of metal parts in the L-shaped conductive seams, without the use of any gasket.14 The water protection may be reached by the same adhesive, since the non-conductive adhesive is usually waterproof.

The application is not restricted to any specific kind of adhesive, the adhesive can be chosen according to the environmental conditions required.

A small quantity of auxiliary fasteners or an auxiliary frame may be used in order to locate the parts on the assembly and for ensuring the adhesive dry time.

It should be appreciated that while the invention has been described with reference to specific examples and drawings, other embodiments and versions of the housing and the method may be proposed which should be considered part of the invention whenever defined by the claims which follow. 260607/2

Claims (14)

Claims:

1. A housing for shielding its contents from electromagnetic waves, the housing 5 being assembled from conductive panels attached to one another using non- conductive adhesive, in the housing, L-shaped contact surfaces are formed wherever the conductive panels are attached to one another, thus creating overlapping, L-shaped conductive seams secured by the non-conductive adhesive; 10 wherein the housing comprises one or more conductive bonding elements; and wherein the one or more of the conductive bonding elements have a generally L- shaped cross-section to form the L-shaped contact surface with one or more of the conductive panels, which serve as a rim forming the L-shaped contact surface when being inserted in a suitable depression formed in two or more conductive panels to be 15 joined..

2. The housing according to Claim 1, wherein the conductive panels are designed so as to fit to one another by forming said L-shaped contact surfaces there-between. 20

3. The housing according to Claim 2, wherein one or more of said conductive panels are manufactured with suitable grooves at their edges, and/or by manufacturing one or more of said panels to have an integral L-shaped extension at one or more of its edges. 25

4. The housing according to any one of the preceding claims, assembled from the conductive panels attached to one another using said one or more conductive bonding elements and the non-conductive adhesive, wherein said conductive panels and/or said one or more conductive bonding elements are configured so as to form said L-shaped contact surfaces wherever attached to one another, thereby creating said 30 overlapping, L-shaped conductive seams secured by the non-conductive adhesive. 260607/2 16

5. The housing according to any one of the preceding claims, designed for EMI/RFI shielding.

6 The housing according to any one of the preceding claims, wherein 5 dimensions of said one or more L-shaped contact surfaces are selected based on the wavelength of one or more of the electromagnetic waves to be blocked by the housing.

7. The housing according to any one of the preceding claims, wherein said 10 non-conductive adhesive is waterproof.

8. The housing according to any one of the preceding claims, wherein said panels are made from a machined metal or from metal sheets. 15

9. The housing according to any one of the preceding claims, wherein at least one of said L-shaped contact surfaces is provided with an engraved pattern to improve adhesion of the panels to be connected.

10. The housing according to any one of the preceding claims, comprising a lid 20 serving as an additional conductive bonding element.

11. The housing according to any one of the preceding claims, wherein the lid is secured to the housing using another adhesive having its melting temperature lower than the adhesive used for other seams of the housing. 25

12. A method for manufacturing a housing according to any one of the preceding claims, the method comprises: providing conductive panels suitable for assembling the housing by forming L-shaped contact surfaces there-between, 30 assembling the housing from the conductive panels using a non-conductive adhesive for said L-shaped contact surfaces, thereby creating overlapping, L-shaped conductive seams secured by the non-conductive adhesive; further comprising: 260607/2 17 providing one or more conductive bonding elements, wherein said conductive panels and/or said one or more conductive bonding elements are configured so as to form the L-shaped contact surfaces wherever attached to one another; 5 assembling the housing by securing said conductive panels to one another, using said one or more conductive bonding elements and the non-conductive adhesive preliminarily placed at said L-shaped contact surfaces; and wherein it further comprising a preliminary step of providing an engraved pattern on at least one said L- shaped contact surfaces. 10

13. The method according to Claim 12, comprising a preliminary step of pre- assembling the housing, using a number of auxiliary bolts/fasteners or an auxiliary frame. 15

14. The method according to Claim 12 or 13, further comprising providing the box with a removable lid adapted to be adhered to the housing by an adhesive having its melting temperature lower than said adhesive used for other seams of the housing.