WO2000048440A1

WO2000048440A1 - Arrangements for electromagnetic shielding of components and circuits

Info

Publication number: WO2000048440A1
Application number: PCT/SE2000/000069
Authority: WO
Inventors: Ödgärd ANDERSSON
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1999-02-09
Filing date: 2000-01-14
Publication date: 2000-08-17
Also published as: JP2002537639A; DE10084045T1; SE515448C2; SE9900429L; SE9900429D0; AU2836000A

Abstract

The present invention relates to electromagnetic shielding of components and circuits arranged on a printed wiring board within a housing of an electric apparatus. A housing for an insert card (200) comprises a first and a second rectangular housing part (203, 204) with a number of resilient spaced-apart tongues (214-217) formed as part of the respective first and second housing part. The resilient spaced-apart tongues (214-217) abut corresponding ground-conductors (222a-b) at least partly enclosing components to be electromagnetic shielded on the printed wiring board (205). This forms EM-shielded zones inside the insert card (200).

Description

ARRANGEMENTS FOR ELECTROMAGNETIC SHIELDING OF COMPONENTS AND CIRCUITS

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of electromagnetic shielding and, in particular, to arrangements for electromagnetic shielding of components within a housing of an electric apparatus.

DESCRIPTION OF RELATED ART

An electric apparatus can as an example comprise a housing in which an electric device with components is arranged. It is common that one or more of these components, e.g. digital circuits, coils, antennas and transformers, in the electric apparatus, radiates EMI (Electro Magnetic Interference) and/or RFI (Radio Frequency Interference) . The EMI and RFI influence the performance of both adjacent components in the electric apparatus itself and other electric apparatuses situated near by.

A known solution to this problem is to arrange some kind of electromagnetic shielding (EM-shielding) in the electric apparatus. The EM-shielding reduces the EMI /RFI that is radiating from the electric apparatus and/or shields the apparatus from EMI/RFI that is radiating from other apparatuses .

The space inside a housing of an electric apparatus is often limited. Sometimes very limited such as in insert cards (also called plug-in cards, PCMCIA cards, PC cards or Compact Flash cards) where the height of the components is limited by the insert cards standards, e.g. PCMCIA or JEIDA. Another example of an electric apparatus where the height of the components is limited is a power supply with a metal housing, e.g. a power supply module for mounting on a printed wiring board. This reduces the number of possible shielding devices that can be used as EM-shielding in e.g. an insert card.

Insert cards are commonly used in portable PCs, electronic notebooks, mobile phones, FAX modems, LAN cards etc. An insert card can as an example comprise a radio unit, an IC memory, a radio modem or data processing equipment. Generally insert cards are removably interconnected to the electric equipment with which they are used so as to be inserted when needed and extracted when not needed.

A known solution for EM-shielding in insert cards is to use different types of shielding gaskets, e.g. polymers mixed with conductive particles or metal strips with small lugs (often called "Sticky Fingers") . Gaskets intended for EM- shielding are usually expensive to purchase and to assemble in the insert cards. The gaskets also tend to bow the covers of the insert cards, since they need compression to work.

Another known solution is to use shield cans (metallic hoods) that encapsulate the component and carry the electromagnetic interference to ground. These shield cans restrict the component height.

Yet another known solution is to use conductive adhesives in combination with shielding gaskets or conductive frames which are expensive and complicated to assemble.

The US patent 5 726867 describes a card holder for computers and related equipment comprising a top cover and a bottom member. End edges of the top cover have respective hooks for co-operation with further recesses on the edges of the bottom member so that the top member is easily snapped over the bottom member and fully encloses the card for substantially complete EMI shielding.

The US patent 5774344 describes a RFI/EMI shield for a circuit card in the form of a box enclosure with a top and a bottom casing. The top casing has solid flanged side walls surrounding the card. The bottom casing has a flange formed by flat, plate-like fingers that are in contact with and are mating in full length with the entire periphery of the side walls of the top casing.

As will be seen herein, each of the arrangements disclosed in these patents is of different types and design than the arrangements of the present invention.

SUMMARY

The present invention meets some problems related to electromagnetic shielding (EM-shielding) of components within a housing of an electric apparatus.

One problem is to provide EM-shielding between different zones within an electric apparatus .

Another problem is to provide low-cost and easy to assemble EM-shielding in an electric apparatus .

A further problem occurs when the EM-shielding in an electric apparatus limits the component height.

In light of the foregoing, a primary object of the present invention is to make it possible to divide the interior of the electric apparatus into different EM-shielding zones.

Other objects of the present invention are to provide EM- shielding that is cheap and easy to manufacture and makes the assembly and disassembly of the electric apparatus fast and easy.

Yet another object of the present invention is to provide EM-shielding without affecting the component height in the electric apparatus .

In a housing according to the present invention, accommodating an electric device, a number of spaced-apart tongues are arranged to create an electrical contact with one or several conductive elements at predetermined positions on the electric device. These conductive elements delimit certain areas with components which are EM-shielded by the spaced-apart tongues.

According to one embodiment of the invention the housing comprises a first and a second part. Resilient spaced-apart tongues are integrated in the first and second part and are arranged to abut against a number of electrical conductors embracing a number of components on the electric device in the housing. The electrical conductors are also connected to a ground plane in the electric device.

The inventive arrangement is therewith characterised according to claim 1.

An advantage with the present invention is that it is possible to arrange EM-shielding between different zones within the electric apparatus in an easy and flexible way.

Another advantage with the present invention is that the EM- shielding is integrated in the housing, i.e. no extra shielding devices have to be bought and assembled in the apparatus .

Yet another advantage is that the EM-shielding makes the housing in which the EM-shielding is arranged very easy to assemble and disassemble.

Still another advantage is that the EM-shielding can be made in the same processing step as when the housing is made, i.e. the EM-shielding does not introduce any extra manufacturing steps.

Another advantage is that the EM-shielding does not affect the component height in the electric apparatus. A further advantage is that the arrangement used for EM- shielding can be used to position an electric device in a predetermined position inside the electric apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a perspective view of an insert card.

Figure 2 illustrates an exploded view of a first insert card according to the present invention.

Figure 3a illustrates a view of a first housing part according to the present invention.

Figure 3b illustrates a view of a cut-out section from figure 3a.

Figure 3c illustrates a cross sectional view of a resilient tongue according to the present invention.

Figure 4 illustrates an exploded view of a second insert card according to the present invention.

Figure 5 illustrates an exploded view of a third insert card according to the present invention.

Figure 6 illustrates cross sectional views of different resilient tongues according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention relates to EM-shielding of components within a housing, i.e. a casing or a cover, of an electric apparatus, e.g. an insert card or a power supply.

EMC (Electromagnetic compatibility) is the combination of two properties of electric apparatuses: emission and susceptibility. Emission refers to the unwanted electromagnetic energy an electric apparatus generates and emits. It is often referred to as RFI (Radio Frequency Interference) or EMI (Electromagnetic Interference) . Susceptibility refers to the level of immunity of an electric apparatus operating in an environment of EMI (both conducted and radiated) and power-line transients. Combining these two properties give the apparatus EMC, i.e. how it affects other electrical equipment in its vicinity and how sensitive it is to interference from the environment.

A number of sources can cause EMI, e.g. atmospherically discharges, electromagnetic processes in machines and plants, energy supplies, high-speed integrated circuits and various transmitters like mobile/cellular phones.

Electric components, circuits and apparatuses may e.g. be made electromagnetically compatible by: reducing the interfering signal source level, reducing the receptor susceptibility, or increase the attenuation of the path or paths over which the interference is transmitted from source to receptor.

An electromagnetic shield (EM-shielding) can be described as a device that comprises a conductive or ferromagnetic material which reflects, absorbs or carries electromagnetic interference (EMI/RFI) to ground.

Figure 1 illustrates an insert card 100 with a connector 101 arranged in a housing 102 that encloses the interior of the insert card 100. A label 103 is attached on the housing 102. The insert card can as an example comprise a transceiver, an IC memory, a radio modem or data processing equipment. The insert card 100 is an example of an electric apparatus comprising a housing in which an electric device with components is arranged. A power supply module (not illustrated in any figures) can be designed in a similar way as the insert card 100 with a housing that encloses an electric device, in this case e.g. DC/DC or AC/DC converters.

Figure 2 is an exploded view illustrating a first insert card 200 according to a first embodiment of the present invention. The insert card 200 includes two labels 201, 202 respectively, a first and a second rectangular housing part 203, 204 respectively and a rectangular printed wiring board 205 with components. The first and second housing parts 203, 204 respectively, preferably consisting of plates, are made of metal, e.g. steel or aluminium, and form two halves of a housing. Each one of the housing parts 203, 204 respectively shows two parallel longitudinal narrow sides 206-209 respectively, an inner surface 210, 211 respectively facing towards the interior of the insert card and an outer surface 212, 213 respectively facing outwards. The narrow side 207 and the inner surface 210 of the first housing part 203 and the outer surface 213 of the second housing part 204 are hidden in figure 2.

The first housing part 203 has a first and a second parallel row of resilient spaced-apart tongues 214, 215 respectively which forms a group of tongues. The second housing part 204 has a third and a fourth parallel row of resilient spaced- apart tongues 216, 217 respectively which also forms a group of tongues. The resilient spaced-apart tongues are formed as part of the respective first and second housing part. A detailed description of these spaced-apart tongues is made in connection with figures 3a-c below. The labels 201 and 202 are adhered on the outer surface 212, 213 respectively of the first and second housing parts. The labels are used for product marking and to cover a number of openings in each housing part. A description of these openings is made in connection with figure 3c below.

The rectangular printed wiring board 205 is arranged between the first and second housing part 203, 204 respectively. The rectangular printed wiring board 205 comprises a first side 218 facing the first housing part 203, a second side 219 (hidden in figure 2) facing the second housing part 204, a connector 220, a number of components on the first and second side 218,219 respectively and at least one ground plane. For simplicity the components and ground plane are omitted in the figure. The connector 220 is attached at one of two parallel short sides of the rectangular printed wiring board 205. The connector 220 is used for connecting the insert card 200 to the electric equipment into which it is inserted. The printed wiring board 205 with components and the connector 220 is also referred to as the electric device.

The first side 218 of the printed wiring board 205 comprise two transverse electrical conductors 222a and 222b (also referred to herein as ground-conductors 222a and 222b) arranged from one longitudinal side to the other of the printed wiring board 205 and in parallel to the short

(transverse) sides of the printed wiring board 205. This means that the first side 218 of the printed wiring board

205 is divided into three board-sections 221a-c by the ground-conductors 222a and 222b. The second side 219 of the printed wiring board 205 is also divided into three board-sections 225a-c by two transverse electrical conductors 223a and 223b (also referred to herein as ground-conductors 223a and 223b) as on the first side 218. The three board-sections 225a-c and the ground- conductors 223a-b on the second side 219 of the printed wiring board 205 are hidden in figure 2. The ground- conductors 222a-b, 223a-b, respectively are connected with the ground plane in the printed wiring board. The ground- conductors are made of copper but can as an alternative be made of tin, gold or any another electrical conductive material suitable for printed wiring boards .

Figure 3a illustrates the first housing part 203 with the first and second rows of resilient spaced-apart tongues 214, 215 respectively. The spaced-apart tongues are each partially stamped-out of the housing part 203 to form a number of outstretched and resilient parts of the housing. This means that the spaced-apart tongues are a homogeneous part of the housing. The first and second rows of spaced- apart tongues 214, 215 respectively are arranged across the inner surface 210 of the first housing part 203 perpendicular to the respective longitudinal narrow sides 206 and 207. The first and second row of spaced-apart tongues 214, 215 respectively are arranged in such a way that the tip of the spaced-apart tongues in each row abut the corresponding ground-conductors 222a-222b on the first side of the printed wiring board 205 when the first insert card 200 is assembled.

Figure 3b illustrates a cut-out section C from figure 3a of the first housing part 203 with two resilient spaced-apart tongues 301, 302 respectively from the first row 214 of tongues. The side-to-side spacing d between the spaced-apart tongues 301 and 302 can as an example be λχ/10 as in this embodiment, where λ_x is the wavelength of the electromagnetic interfering signals that the EM-shielding is designed for. The side-to-side spacing d of XN10 is the same between all the spaced-apart tongues in the first and second row of tongues 214, 215 respectively.

Figure 3c illustrates a cross sectional view taken along line A-A of figure 3b of the resilient tongue 302. The resilient tongue 302 consists of a narrow and flat outstretched arm 303 extending from the inner surface 210 of the housing part 203 towards the interior of the insert card 200. The top of each arm is slanted to form a flat tip 304 in parallel with the inner surface 210 of the housing part 203. The flat tip 304 is arranged to make good electrical contact with the electrical conductor 222a on the printed wiring board 205. There is an opening 305 under the resilient tongue 302 that is created when the resilient tongue is stamped out from the housing part. The size of the opening 305 and the tongue 302 are determined in a known way from λi . The arm 303 forms a first angle 306 of e.g. 45 degrees against an imaginary surface over the opening 305. The first angle 306 is determined dependent on the distance between the housing parts and the printed wiring board when the insert card is assembled and also dependent on the desired size of the opening 305. If the first angle 306 is to big the tongues will be bent when the insert card is assembled and if the first angle 306 is to small no contact against the printed wiring board will be achieved.

The description of the resilient spaced-apart tongues in the first housing part 203 according to figure 3a-c applies equally to the resilient spaced-apart tongues in the second housing part 204. The third and fourth rows of spaced-apart tongues 216, 217 respectively are arranged across the inner surface 211 of the second housing part 204 perpendicular to the respective narrow sides 208 and 209 of the second housing part 204. The third and fourth row of spaced-apart tongues 216, 217 respectively are arranged in such a way that the tip of the spaced-apart tongues in each row abut the corresponding ground-conductor 223a, 223b respectively when the first insert card 200 is assembled.

The ground-conductors 222a-b and 223a-b on the printed wiring board and the housing parts with the corresponding rows of spaced-apart tongues 214-217 respectively creates three EM-shielded zones inside the insert card 200. Figure 6 illustrates two other examples of resilient tongues 601, 602 respectively that can be used as an alternative to the resilient tongue 302 in the first embodiment illustrated in figure 3c.

Figure 4 is an exploded view illustrating a second insert card 400 according to a second embodiment of the present invention. The second insert card 400 has two labels 401, 402 respectively, a first and a second rectangular housing part 403, 404 respectively and a rectangular printed wiring board 405. The first and second housing parts 403, 404 respectively, preferably consisting of plates, are made of metal, e.g. steel or aluminium, and form two halves of a housing. Each one of the first and the second housing part shows two longitudinal narrow sides 406-409 respectively, an inner surface 410, 411 respectively facing towards the interior of the insert card 400 and an outer surface 412, 413 respectively facing outwards. The narrow side 407 and the inner surface 410 of the first housing part 403 and the outer surface 413 of the second housing part 404 are hidden in figure 4.

The first housing part 403 has a first rectangle of spaced- apart tongues 424. The second housing part 404 has a second and a third rectangle of spaced-apart tongues 416, 417 respectively. The resilient spaced-apart tongues are of the same design as in the first embodiment according to figure 3a-c. The three rectangles of spaced-apart tongues 416, 417 and 424 forms three groups of tongues.

The labels 401 and 402 are adhered on the outer surface 412, 413 respectively of the first and second housing parts. The labels are used for product marking and to cover openings in each housing part as in the first embodiment according to figure 2. The rectangular printed wiring board 405 arranged between the first and second housing part 403, 404 respectively comprises a first side 418 facing the first housing part 403, a second side 419 (hidden in figure 4) facing the second housing part 404, a connector 420, a number of components on the first and second side 418, 419 respectively and at least one ground plane. For simplicity the components and ground plane are omitted in the figure. The connector 420 is attached at one of the two parallel short sides of the printed wiring board 405. The printed wiring board 405 with components and the connector 420 is also referred to as the electric device.

The first side 418 of the printed wiring board 405 has a rectangle of electrical conductors 423 (also referred to herein as ground-conductors 423) which delimits a first board-section 421a.

The second side 419 of the printed wiring board 405 is divided into two board-sections 425a-b by two rectangles of electrical conductors 426a-b respectively (also referred to herein as ground-conductors 426a-b) . The two board-sections 425a-b and the two rectangles of conductors 426a-b on the second side 419 of the printed wiring board 405 are hidden in figure 4. The electrical conductors 423 and 426a-b respectively are connected with the ground plane in the printed wiring board 405 and are made of copper but can as an alternative be made of tin, gold or any another electrical conductive material suitable for printed wiring boards .

The rectangle of spaced-apart tongues 424 in the first housing part is arranged in such a way that the tip of the tongues in the rectangle 424 abut the rectangle of ground- conductors 423 on the first side of the printed wiring board when the second insert card 400 is assembled. The two rectangles of spaced-apart tongues 416, 417 respectively in the second housing part 404 are arranged so that the tip of the tongues in each rectangle abut the corresponding rectangle of ground-conductors 426a-b respectively on the second side of the printed wiring board 405 when the second insert card 400 is assembled.

The ground-conductors 423, 426a-b respectively on the printed wiring board 405 and the housing parts 403, 404 respectively with the rectangles of spaced-apart tongues 416, 417 and 424 respectively creates four EM-shielded zones inside the insert card 400.

Figure 5 is an exploded view illustrating a third insert card 500 according to a third embodiment of the present invention. The third insert card 500 includes two labels 501, 502 respectively, a first and a second rectangular housing part 503, 504 respectively and a rectangular printed wiring board 505. Each one of the first and the second housing part, preferably consisting of plates, shows an inner surface 510, 511 respectively facing towards the interior of the insert card 500 and an outer surface 512, 513 respectively facing outwards. The inner surface 510 of the first housing part 503 and the outer surface 513 of the second housing part 504 are hidden in figure 5. The third insert card 500 also includes a fixating frame 506 arranged between the first housing part 503 and the circuit board 505.

The first housing part 503 has a first and a second row of spaced-apart tongues 514, 515 respectively which forms a group of tongues. The resilient spaced-apart tongues on the first housing part 503 are of the same design as in the first embodiment according to figure 3a-c.

The labels 501 and 502 are adhered on the outer surfaces as in the first and second insert card according to figure 2 and 4. The fixating frame 506 is made of aluminium but can as an alternative be made of another conductive material as magnesium, zinc or plastic coated with a conductive material. The fixating frame 506 is formed as a first rectangular part 507 with one short side missing and a first and a second transverse part 508, 509 respectively extending from one longitudinal side to the other parallel to the remaining short side of the rectangle 507. The design of the fixating frame 506 varies dependent on the size and number of board sections arranged on the printed wiring board 505. The fixating frame 506 can have a recess (not illustrated) to guide the printed wiring board 505 when it is assembled.

The rectangular printed wiring board 505 arranged between the first and second housing part 503, 504 respectively comprises a first side 518 facing the first housing part 503, a second side 519 (hidden in figure 4) facing the second housing part 504, a connector 520, a number of components on the first side 518 and at least one ground plane. For simplicity the components and ground plane are omitted in the figure. The printed wiring board 505 with components and the connector 520 is also referred to as the electric device.

The first side 518 of the printed wiring board 505 comprises a pattern of narrow electrical conductors (also referred to herein as ground-conductors) which includes a rectangular frame 517 with two cross-connected conductors 522a and 522b. The rectangular frame 517 is arranged along the outer edge of the first side 518 of the printed wiring board 505. The two cross-connected conductors 522a, 522b respectively are arranged from one longitudinal side to the other and in parallel to the short sides of the rectangular frame 517. This means that the first side 518 of the printed wiring board 505 is divided into three board-sections 521a- c by the ground-conductors 517, 522a and 522b. The ground- conductors 522a-b and 517 respectively are connected with the ground plane in the printed wiring board 505 and are made of copper.

The fixating frame 506 is arranged in such a way that the frame abuts the corresponding ground-conductor 517, 522a and 522b respectively on the first side of the printed wiring board 505 when the third insert card 500 is assembled. The first and second transverse part 508, 509 respectively of the fixating frame 506 abut the corresponding ground- conductor 522a, 522b respectively and the first rectangular part 507 abut the rectangular ground-conductor 517 when the third insert card 500 is assembled.

The first and second row of spaced-apart tongues 514, 515 respectively in the first housing part 503 are arranged in such a way that the tip of the spaced-apart tongues in each row abut the corresponding transverse part 508, 509 respectively of the fixating frame 506 when the third insert card 500 is assembled.

The fixating frame 506 abuts both the corresponding ground- conductors 522a, 522b and the first and second row of spaced-apart tongues 514, 515.

The ground-conductors 517, 522a-b respectively on the printed wiring board 505, the frame 506 and the first housing part 503 with the rows of spaced-apart tongues 515 and 516 respectively creates three EM-shielded zones on the first side 518 of the printed wiring board 505 inside the insert card 500. The printed wiring board 505, the frame 506 and the housing creates one EM-shielded zone on the second side 519 of the printed wiring board 505 inside the insert card.

In a fourth insert card, not illustrated in any figures, according to a fourth embodiment of the present invention two fixating frames are used. Resilient tongues on a first housing part abut a first fixating frame which abut a first side of a printed wiring board. Resilient tongues on a second housing part abut a second fixating frame which abut a second side of the printed wiring board. Hence, the printed wiring board is fastened and fixated by the two fixating frames arranged between the housing parts .

The resilient spaced-apart tongues in the first and second insert card 200, 400 respectively constitutes an effective EM-shielding arrangement by connecting the ground plane in the respective printed wiring board via the corresponding ground-conductors to the first and second housing part of each insert card. The resilient spaced-apart tongues in the third and fourth insert card constitutes an effective EM- shielding arrangement by connecting the ground plane in the respective printed wiring board via the corresponding ground-conductors and one or two fixating frames to the first and second housing part of each insert card. These EM- shielding arrangements form grounded enclosures (EM-shielded zones) in the insert cards that completely or partly enclose (embrace) components within one or more board-sections on the respective printed wiring board. Both the ground- conductors and the fixating frames are examples of conductive elements on the printed wiring board.

The resilient tongues are partly pushed against the respective housing part (so that the first angle 306 decreases) when the housing is assembled around the printed wiring board of the insert card. This means that the spaced- apart tongues will exert a pressure against the printed wiring board which ensures a galvanic contact between the spaced-apart tongues and the ground-conductors and/or fixating frames against which they abut.

The surface of the ground-conductors and/or of the tongues can be surface treated, e.g. by applying Ni, Sn or Cr, to optimised the electrical contact between the tip of the tongues and the ground-conductors . The side-to-side spacing between the spaced-apart tongues in a group surrounding a certain board-section (or EM-shielded zone) of the printed wiring board is dependent on the frequency that particular board section is designed for. This means that the side-to-side spacing may differ between different groupings of the spaced-apart tongues in the same insert card. The side-to-side spacing d between the spaced- apart tongues can as an example be λι/10 in a first group of tongues and λ₂/10 in a second group of tongues, where λ. and λ₂ correspond to the wave-length of a first and a second electromagnetic interfering signal.

The resilient spaced-apart tongues in a group of tongues with two rows, e.g. 214 and 215, does not necessarily have to be arranged so that the tongues are "pointing" at each other as illustrated in figure 2 to 5. The tongues at both rows of tongues in a group can be "pointing" in the same direction. The resilient spaced-apart tongues in a group of tongues forming a rectangle, e.g. 417 and 424, does not necessarily have to be arranged so that the tongues are "pointing" to the centre of the rectangle as illustrated in figure 4. The tongues in a rectangle can be "pointing" in the opposite direction. A group of tongues and the corresponding board-section with ground-conductors according to the present invention can be arranged in a number of different forms e.g. as rows, rectangles, squares or circles .

The resilient tongues can also be used to position the printed wiring board inside the housing of the insert card 200, 400 and 500 in a predetermined position. This means that the resilient tongues can replace frames, screws, rivets, gaskets or similar fastening means which is used to position the circuit board in the insert card 200, 400 and 500.

The printed wiring boards in the insert cards of this invention may comprise components on both sides, on one of these sides and/or inside the printed wiring board in an intermediate layer.

The labels 201, 202, 401, 402 and 501 which are adhered on the outer surface of the housing parts in figure 2,4 and 5 to cover the openings can as an example be made of metal, e.g. copper or aluminium, with a conductive adhesive attached on one side. Such labels can preferably be used if the openings under the spaced-apart tongues are bigger than λi/10 for those frequencies that the EM-shielding is designed to shield from.

Locking means is arranged on/in the insert cards 200, 400 and 500 to keep the first and second housing parts together. For simplicity the locking means are omitted in the figures. This type of locking means is well known in the art e.g. snap-locking, gluing or welding.

The resilient tongues are stamped and formed in the same procedure as the housing parts. This means that no extra processing step is needed to manufacture the resilient spaced-apart tongues in the housing parts.

The housing of the insert cards 200, 400 and 500 have been described to include two housing parts but the housing may also be designed as one single housing, that e.g. is folded around the electric device, or be designed to include more than two housing parts.

It should be understood that the insert cards 200, 400 and 500 can comprise other components or electrical conductors for the performance of the insert card than those described. These components and conductors are for simplicity omitted in the figures and the corresponding text.

The inventive arrangement with the resilient tongues can be used in a number of different boxes, covers, housings or similar which encloses electric devices to be EM-shielded. These boxes, covers, housings or similar can be made by any material suitable for EM-shielding e.g. steel, aluminium or metalized plastic.

Claims

1. A housing with electromagnetic shielding accommodating an electric device in which electronic components are mounted in certain areas, c h a r a c t e r i s e d in that said housing has a number of spaced-apart tongues (214-217,301-302,416-417, 424,514- 515,601-602), which are arranged to create electrical contact with at least one position determined conductive element (222a-b, 223a-b, 423, 425a-b, 517 , 522a-b, 506) provided on said electric device, where said position determined conductive element at least partly embrace at least one of said areas so as to shield said components in said area.

2. The housing as claimed in claim 1, wherein said spaced- apart tongues (214-217,301-302,416-417, 424,514-515,601-602 are resilient.

3. The housing as claimed in claim 1 or 2, wherein said spaced-apart tongues (214-217,301-302,416-417,424,514- 515,601-602) are formed as a part of said housing (203-204, 403-404,503-504) .

4. The housing as claimed in any one of claims 1-3, wherein said spaced-apart tongues (214-217,301-302416-417,424,514- 515,601-602) are arranged in at least one group in said housing .

5. The housing as claimed in any one of claims 1-4, wherein said conductive element (222a-b, 223a-b, 423, 425a-b, 517 , 522a- b,506) and said spaced-apart tongues are delimiting at least one EM-shielded zone in said housing.

6. The housing as claimed in any one of claims 1-5, wherein said electrical device includes at least one printed wiring board (205,405,505) on which said conductive element (222a- b, 223a-b, 423, 425a-b, 517, 522a-b, 506) and said components are arranged.

7. The housing as claimed in any one of claims 1-6, wherein said conductive element (222a-b, 223a-b, 423, 425a-b, 517 , 522a- b) is an electrical conductor (222a-b, 223a-b, 423, 425a- b,517,522a-b) .

8. The housing as claimed in any one of claims 1-7, wherein said housing includes at least one housing part (203-204, 403-404,503-504) .

9. The housing as claimed in any one of claims 1-7, wherein said housing includes a first and a second housing part

(203-204, 403-404,503-504), where at least one of said housing parts has said spaced-apart tongues (214-217,301- 302,416-417,424,514-515,601-602) .

10. The housing as claimed in any one of claims 6-9, wherein a first number of said spaced-apart tongues (514,515) abuts at least one frame (506) arranged on said printed wiring board (205,405,505) in said housing.

11. The housing as claimed in any one of claims 1-10, wherein said spaced-apart tongues (214-217,301-302,416- 417,424,514-515,601-602) have been stamped out from said housing.

12. The housing as claimed in any one of claims 1-11, wherein a second number of spaced-apart tongues are arranged to position said electric device in said housing in a predetermined position.

13. The housing as claimed in any one of claims 1-12, c h a r a c t e r i s e d in that said housing accommodating said electric device is an insert card.

14. The housing as claimed in any one of claims 1-12, c h a r a c t e r i s e d in that said housing accommodating said electric device is a power supply.