The present invention relates generally to structures for preventing or shielding electromagnetic interference (“EMI”) emissions from connector assemblies. In particular, the invention relates to shielded electrical connectors and shielding assemblies for connectors for high-speed signal transfer.
Connector assemblies may be used in or between electronic devices for transmitting signals between two cables or between a cable and the printed circuit board of an electronic device. It is common practice to make such interconnections with connector assemblies comprising one connector configured to fit at least partially with another connector, or counterpart connector.
It is well known that signals to be transmitted by such connector assemblies may cause EMI emissions. This is particularly the case for high speed and/or frequency signals, such as about 1 gigabit per second and higher, and the effect tends to get worse for increasing signal frequencies. Such EMI radiations may cause electromagnetic disturbance to other neighbouring connector assemblies and/or electrical or electronic devices. Vice versa, electromagnetic radiations emitted by the connector environment may disturb signals transmitted by connectors.
Effective EMI shielding of a connector assembly is usually achieved in electrically connecting conductive shielding arrangements on both connecting parts of the connector assembly with at most small holes, smaller than the shortest wavelength from which shielding is desired. Thus, for effective shielding of a connector assembly at high frequencies one should provide such a connector assembly with at most very small holes in and between the connecting parts.
Resilient gaskets and/or contact springs are used for providing such an electrical connection between the conductive shielding arrangements.
Contact springs provide a certain tolerance for true positioning of the connector and the counterpart connector to be mated, in particular for board-to-board connector assemblies.
In an aspect of the invention, a shielding assembly according to claim 1 is provided. In the first position (when the connector is not mated with the counterpart connector), the second portion is arranged at a first separation (distance) from the shield wall and in the second position (when the connector is mated with the counterpart connector), the second portion is arranged at a second separation (distance) from the shield wall, wherein the second separation is larger than the first separation. In other words, the second portion or the spring element is moved away from the shield wall when the connector and its counterpart are mated. Of course, since the spring element may be linked at one side to the shielding assembly, the second portion and the shield wall be spread out only on one side (the opposite side to the one linked or attached to the shielding assembly).
According to the invention, the spring elements comprise a first portion for making an electrical contact with the shielding arrangement of the counterpart and a second portion which is at least partially located outside the gap between the connector and its counterpart (or the shielding arrangement of the counterpart). Consequently, in the mated situation the spring elements of the shielding assembly provide electrical contact between the shield member of the assembly and the counterpart connector, preferably with a shielding arrangement of the counterpart connector. The spring elements may comprise a conductive portion or be conductive as a whole, e.g. by being metallic. Such electric contact provides an EMI shielding effect to the connector assembly. In the shielding assembly according to the invention, the second portion is arranged further away from the shield wall in the mated situation than in the unmated situation. This prevents the spring element from becoming trapped against the shield wall upon mating the connector and the counterconnector, which could result in plastic deformation of (the second portion of) the spring element. The spring element, and therewith the shielding arrangement, is therefore relative safe from damage.
Thus, in the shielding assembly according to the invention, the size, strength and/or resiliency of the spring element of the shielding assembly need not be dimensioned for withstanding plastic deformation. The spring element therefore may be formed for accepting relatively large amounts of elastic deformation and for having a relatively low spring constant.
The former aspect provides a relatively large tolerance for true positioning of the connector and the counterpart connector of the connector assembly with respect to each other. The latter aspect facilitates mating the connector and the counterpart connector by providing a relatively low insertion resistance, hence reducing the required insertion force.
It is generally desired that a plurality of adjacent spring elements are provided for reasons of increasing effective EMI shielding by reducing apertures in the shielding. For facilitating designing and manufacturing of the shielding assembly and thus of at least the connector of the connector assembly the plural spring elements are substantially identical.
The assembly of claim 2 allows a relatively large freedom of movement for the second section of the spring element, in particular if the contact portion and the portion of the first section are arranged on opposite sides of the shield wall. The second section is advantageously arranged such that its displacement upon mating is also unobstructed by the counterpart connector. Such a configuration also allows limiting the opening in the shield wall to the extent which is necessary for the passage and/or movement of the first section, for a better EMI shielding. A configuration with the second section also moving through the shield wall (for instance if the shielding member is attached inside the shielding assembly, falls in the scope of the invention even if not the most preferred.
In the assembly of claim 3 the displacement of at least the third portion of the spring element is limited. This may protect the spring element against excessive deformation. The third portion may make electrical contact with the shield member. This aspect is discussed in more detail below.
The assembly of claim 4 allows shortening the electrical path between the shielding arrangement of the connector and the counterpart connector, to the distance between the fulcrum and the contact point between the spring element and the counterpart connector. Such a feature also allows combining a relatively low spring force and/or large deformation range for the second portion of the spring element with a relatively large contact force for the contact portion against the counterpart connector by using a lever-effect between on the second portion of the spring element. An increased contact force reduces contact resistance of the electrical contact and may improve scraping off a dust-, debris- and/or oxide layer which may be present on the counterpart connector, thus improving the electrical contact.
Advantageously, the third portion is free from contact with the shield wall in the first position (unmated situation), whereas the third portion comes at least in mechanical contact with the shield wall during mating the connector and the counterpart connector, remaining in mechanical contact with the shield wall in the second position (mated situation). This provides a relatively low contact force for at least a first amount of displacement of the third portion, and thus a relatively low insertion force, during the initial stage of mating the connector assembly. During the later stage of mating and in the mated situation the lever-effect is employed.
In the assembly of claim 5, the spring element is configured for concentrating deformation of the spring element in the second portion, which is provided with space for such deformation. This assists preventing the spring element from being plastically deformed. This also allows optimising the different portions for their different functions within the spring element.
In the assembly of claim 6, the elastic deformation of the spring is in plural directions, such that deformation stresses are distributed instead of being localised. Thus, a spring element is provided which may have a large mechanical strength against deformation various directions, and which may have at the same time a relatively low spring constant.
Further, in this assembly, the desired maximum deformation of the spring element may be confined in a particular volume, rather than in a single direction. Thus, particular combinations of spring force, true positioning tolerance and available space in different directions for (the shielding assembly of) the connector may be met more easily.
Due to the spring element extending at least partially inside or trough the slot(s), the shield wall extends at least partially around the spring element in the assembly of claim 7. Thus one or more edges of the shield wall allow protecting the spring element against excessive deflection in a direction towards that edge/those edges. Further, apertures in the shield are reduced and thus EMI shielding efficiency of the assembly is improved.
One or more spring elements may be arranged at least partially within a slot.
The assembly of claim 8 allows reducing the height of (the shield wall of) the connector while still providing the benefits of having slots, which provide edges substantially in three directions.
The assembly of claim 9 allows substantially decoupling the spring function and the electrical connection function of the spring element. In case the spring element is insulating, e.g. being made of a plastic, the at least one conducting path may be the first electrical connection path.
The at least one electrical connection path may be an additional connection path. Providing the spring element with a plurality of connection paths may reduce the electrical resistance of the shielding assembly. This improves the shielding effect of the shielding assembly.
The path length of the shortest connection path is a decisive factor for the inductance of the shielding assembly. Generally, the shorter the path is, the lower will be the inductance.
The assembly of claim 10 thus provides a spring element which allows a relatively long spring—generally allowing a large deflection—, a relatively low resistance and a relatively shorter electrical connection path—generally allowing shielding a high frequency—.
The electrical connection path may be established by a conductive element, such as a wire, in-between the first portion and the shield member. A simpler solution is provided by an assembly in which the one or more spring elements of the shielding assembly are formed such that at least in the mated situation of the connector and the counterpart connector the second contact point of those spring elements provides a direct contact, both mechanical and electrical contact, with the shield wall, such as discussed above with respect to claims 3 and/or 4.
The assembly of claim 11 provides a substantially modular shield assembly, and therewith a substantially modular connector. This allows optimising properties such as material properties of at least the shield member and the spring member relatively independent from each other. E.g., the spring member may be manufactured from thin elastic sheet material such as phosphor bronze, whereas the shield member may be manufactured from a different, substantially more rigid material, e.g. a material suitable for deep drawing.
Another aspect of the invention is a shielding assembly according to claim 12.
Such a shielding assembly allows a relatively large amount of deformation of the spring elements upon mating, while still providing a relatively short electrical connection path. Thus, the shielding assembly combines a relatively large tolerance for true positioning of the connector and the counterpart connector with a relatively low inductance and therewith EMI-shielding for high frequencies.
Another aspect of the invention is a shielding assembly according to claim 13.
The shielding assembly provides a relatively large amount of deflection of the spring elements and a short electrical connection path for EMI shielding of the connection between the connector and the counterpart connector at relatively high frequencies. The spring element is protected against excessive deformation, which may lead to plastic deformation instead of elastic deformation. The connector assembly may be formed relatively low, saving valuable mounting volume.
A connector assembly may be provided as a whole or by providing the connector and the counterpart connector individually. Consequently, another aspect of the invention is the connector defined in claim 13.
The connector of the connector assembly may be manufactured substantially modular, hence another aspect of the invention is the shielding assembly defined in claim 14.
The invention will be explained in more detail hereafter with reference to the drawings, which serve for illustration purposes only.
In the drawings,
In the Figures, identical objects and elements are indicated with identical reference signs.
The shielding assembly 2 comprises a shield member 3 having a shield wall 4. The shielding assembly 2 further comprises a spring member 5 comprising a plurality of spring elements 6 which are joined by a carrier strip 7.
The shield member 3 of the embodiment of
The shield member 3 of the embodiment of
The spring member 5 of both embodiments of
The shield wall 4 of the shield member 3 comprises a plurality of slots 8. The slots 8 are open at the mating side of the shield member 3, giving the shield wall 4 a substantially castellated shape with relatively high portions in between adjacent slots 8. The rear side of the shield wall 4 may comprise means for mounting to a further object, e.g. the flange 4A shown in
The spring elements 6 of the spring member 5 are configured for making electrical contact between the shield wall 4 and the counterpart connector in the mated situation of the connector and the counterpart connector. Each spring element 6 comprises a first portion or contact portion 9 configured for making electrical contact with the counterpart connector. Each spring element 6 further comprises second portion or spring portion 10 for providing a spring force to the contact portion 9. In the embodiments shown each spring element 6 is provided with tongues or protrusions 11 extending on either side from the spring element 6 near the contact portion 9.
As shown in
The protrusions 11 extend substantially parallel to the shield wall 4 and perpendicular to the mating direction M. As shown in
For providing a suitable EMI shielding function the shield member 3 should comprise an electrically conducting material. Suitable materials comprise e.g. metals and conducting plastic materials. Similarly, the spring element 6 should comprise a conductive material at least for the contact portion 9. Preferably the entire spring member 5 is conductive. For instance it is a metal piece. The shield member 3 and the spring member 5 are preferably electrically interconnected and they may be mechanically attached together as shown in
The spring member 5 may also comprise means for mounting the spring member 5 to a further object, such as a printed circuit board. E.g., the carrier strip 7 of the spring member 5 may comprise one or more mounting tails adapted to be connected to a receiving portion of a printed circuit board. The mounting tails extend from the carrier strip 7 in opposite direction to the spring element 6.
In the unmated situation of the connector 1 and the counterpart connector 100, the spring elements 6 are arranged substantially as depicted in
Upon mating the connector and the counterpart connector, see
The deflection of the spring element 6 brings the edges 11A of the protrusions 11 into contact with the shield wall 4. This provides a fulcrum F for a rotation of the spring element 6 with respect to the shield wall 4, as indicated by the black dot and the black arrows in
The contact between (the edges 11A of) the protrusions 11 and the shield wall 4 establishes an electrical contact between the shield member 3 and the spring element 6 in case both are conducting. Thus an electrical connection path between the contact portion 9 and the shield member 3 is established via the protrusions 11 which is relatively short and thus advantageously results in a relatively low inductance of the path.
In the shown embodiments the electrical contact between the contact portion 9 and the shield member 3 via the protrusions 11 is a second electrical connection path in addition to a first connection path between the contact portion and the shield member 3 via the spring portion 10 and the carrier strip 7 of the spring member 6. It will be appreciated that the second electrical connection path via the protrusions 11 is significantly shorter than the first one via the spring portion 10. Thus, the inductance and resistance of the electrical connection between the contact portion 9 and the shield member 3 are reduced, improving the shielding characteristics of the shielding assembly.
In case the slots 8 are not open on the mating side, i.e. the slots 8 are holes through the shield wall 4, the tip 11B of the spring member 6 may act in the same manner as set out for the edges 11A.
Referring now in more detail to
The longitudinal ends of the strip are provided with a locking tab 13 and a matching recess 14, respectively, forming closing features 13, 14 for maintaining the bent shape of the shield member 3. The locking tab 13 is asymmetric, having a pointed side 13A directed towards the future mating direction M of the shield member 3 and a substantially straight side 13B which is substantially parallel to the (future) rear side of the shield member 3. The recess 14 is shaped accordingly. The asymmetric closure means 13, 14 assist maintaining the rear side of the shield member 3 substantially planar.
A substantially planar rear side is particularly important in case the shielding assembly 1 is mounted on a board connector, since in that case the shield member 3 may be fixed to the board substantially only by soldering it. A non-coplanar shielding member may cause one or more weak spots in the soldering contact which may lead to EMI leakage. When mechanical stress concentrates at such a weak spot it may also lead to a partial or complete failure or breaking off of the assembly. To provide mechanical stability and to ensure and maintain a substantially planar rear side, the shield member 3 may be made with a relatively thick and robust material.
Similarly, the rear side of the flange 4A of the shield member 3 of
The spring member 5 may also be manufactured by cutting or stamping from a sheet material (
Like
Whereas the embodiment of
Upon mating the connector 1 and the counterpart connector 100, the spring element 6 will deflect outward. If the edges 11A of the protrusions 11 come into contact the shield wall 4, a fulcrum F is formed and the spring element 6 will deform as indicated in
Should the tip 11B come into contact with the spring portion 10, the effective spring action is divided asymmetrically over the portions 10A and 10B. Thus, the spring constant of the spring element 6 is significantly increased, increasing the contact pressure and decreasing the contact resistance of the contact portion 9 to the counterpart connector 100.
As indicated with the bold black arrow in
In order to reduce the spring force of the spring portion 10 and/or to localize regions of the spring element 6 in which deformation should be confined, the spring portion 10 may be suitably made longer and/or made thinner in one or more dimensions relative to the contact portion 9 and/or adjacent portions. E.g., in
Another option is the embodiment of
Thus, by interchanging the spring member 5 of the embodiment of
A spring member comprising spring elements according to
Alternatively, the spring portion 10 may comprise further portions extending in different directions, e.g. with several zigzagging portions. This further increases the mechanical length, allowing further reducing spring force and distributing deformation both in deflection and torsion. Electrical contact between the protrusions 11 or the tip 11B of the spring element 6 and the shield wall 4 still provides a low inductance to the shielding arrangement.
The invention is not restricted to the above described embodiments which can be varied in a number of ways within the scope of the claims. For instance, the spring elements may be provided separately, instead of joined on a carrier strip.
The shape of the shield member may be different.
One or more contact portions may be provided with bumps, ridges etc. for increasing local contact pressure and thus reducing electrical contact resistance.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB2008/055366 | 10/22/2008 | WO | 00 | 6/28/2011 |