Self-securing RF screened housing

Details Self-securing RF screened housing Self-securing RF screened housing

1998-02-03

2001-10-02

Gaffin, Jeffrey (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S816000, C361S818000, C361S736000, C361S759000, C174S034000, C206S719000

Reexamination Certificate

active

06297967

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a self-securing RF screened housing for screening against electromagnetic radiation.
In the case of screening devices, a problem which arises frequently is to produce between a printed circuit board and a screened housing connected to it a contact which is sufficient for RF screening. This is particularly problematic if a unit in which the RF screening device is used is subject to vibration, which may be the case, for example, when used in a vehicle. For this reason, a conductive foam (or adhesive) is generally used in order to ensure a reliable contact between the printed circuit board and the screening device. The use of such an additional aid is, however, on the one hand very expensive and, on the other hand, a further process step is required during assembly, as a result of which the production and assembly time is unnecessarily extended.
Furthermore, dismantling of such RF screening devices for repair work is complex, since the conductive foam or adhesive as a rule has to be removed first and must then be replaced by new foam or adhesive.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided self-securing RF screened housing having a screening plate and having at least two mutually opposite side walls, which project from said screening plate and are designed to engage behind rims of a printed circuit board, which is fitted with the RF screened housing, and having elastic means which can be pressed against at least one of the main surfaces of the printed circuit board in order to clamp the latter at the rims to the side walls. The invention provides an RF screened housing which enables reliable and RF-proof electrical contact with a printed circuit board in a relatively simple manner, to be precise even when subject to relatively long-lasting and severe vibration stresses.
If the RF screened housing, which may be completely composed of electrically conductive material or, for example, of plastic with an electrically conductive coating, is placed onto the printed circuit board, its side walls come into contact with electrically conductive regions on the printed circuit board. As a result of the contact pressure produced by the elastic means, a reliable screen is obtained in this case, since said means always ensure the electrical contact, even when subject to relatively severe mechanical stresses.
The elastic means may likewise expediently be electrically conductive, so that it is possible to produce an even better electrical contact between the RF screened housing and the printed circuit board. When the RF screened housing is placed onto the printed circuit board, the elastic means then press against the conductive coating, which is applied on the surface of the printed circuit board, and thus further improve the screening reliability.
According to an advantageous development of the invention, the side walls have openings, which are located at a distance from one another in the longitudinal direction of said side walls, for holding tabs which project at the sides from the printed circuit board.
When the RF screened housing is placed onto the printed circuit board, the side walls, which project from the screening plate, initially bend outwards, before then springing back again into their original position allowing the tabs, which are fitted on the printed circuit board at a distance corresponding to that between the openings and the side walls, to snap into these openings.
The electrically conductive inner edges of the openings are in this case electrically conductively connected to the rest of the RF screened housing, so that, when the RF screened housing is coupled to the printed circuit board, a good electrical contact is produced between at least one electrically conductive inner edge of each opening and an electrical coating which is formed on the printed circuit board. The last-mentioned electrical coating may also be present on both sides of the printed circuit board and of the tabs.
The RF screened housing is effectively protected against sliding off as a result of the fact that the tabs, which are fitted on the printed circuit board at the sides, snap into the openings in the side walls.
According to another advantageous development of the invention, the elastic means, which are designed as lugs, project into each of the openings, it being possible for the lugs to be, for example, integrally connected to the side wall, for example at the lower inner edge, which is parallel to the screening plate, of the openings. In consequence, a reliable electrical contact is produced between the RF screened housing and the printed circuit board, since the conductive coating on the upper surfaces of the tabs which are fitted to the printed circuit board is now pressed by the elastic lugs against the upper inner edges, which are parallel to the screening plate, of the openings. Alternatively, an electrical contact can be made via the lugs, which press against electrically conductive regions on the side of the printed circuit board facing them.
It would furthermore be conceivable for the elastic means, which are designed as lugs, to be connected to the side wall on any other inner edges of the openings, the tabs always being pressed against those inner edges of the openings which are opposite the lugs.
Alternatively, a plurality of elastic means, which are designed as lugs, can also project into the openings in the side walls, this still further improving the coupling of the printed circuit board to the RF screened housing.
According to an advantageous development of the invention, the screening plate, the elastic means which are designed as lugs, and the side walls may be formed from a single metal sheet, which has a positive effect on the production costs and the production time.
In a further refinement of the invention, the elastic means, which are designed as lugs, are bent outwards relative to the side wall, which makes it easier to fit the RF screened housing onto the printed circuit board, since the side walls can then spring back over the tabs better.
The elastic means, which are designed as lugs, may, however, themselves also be bent inwards or run in a straight line parallel to the side wall.
According to yet another development of the invention, the side walls are bent outwards in the region of their free rim in order thus to make it easier to fit the RF screened housing onto the printed circuit board without there being any risk of the electrically conductive coating, which is present on the tabs, being scratched during the fitting operation.
According to another highly advantageous development of the invention, the mutually opposite side walls have wall regions which are at a distance from one another in the longitudinal direction of the printed circuit board and run inwards, for engaging behind the rims of said printed circuit board. These wall regions which run inwards may be formed by pressing in the side walls in place.
Alternatively, the wall regions which run inwards may, however, also be formed by cutting and bending the side walls in places.
When the RF screened housing is fitted onto the printed circuit board, the side walls in turn bend outwards in order then to spring back in essence to their original position once the wall regions which run inwards have passed the rim of the printed circuit board. The advantage of this development is that the printed circuit board does not need to be additionally processed, since there is no need for any tabs, which project from the printed circuit board at the sides, or similar structures on the printed circuit board and, nevertheless, a good electrically conductive contact is produced between the RF screened housing and the printed circuit board as a result of the effect of the elastic means, which press the printed circuit board against the wall regions which run inwards. In this case the elastic means press the printed circuit board away from the screening plate and against the wall region which run inwards. Since the wall regions which run inwa

Affiliated with

Also associated with

Rating

Self-securing RF screened housing does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Self-securing RF screened housing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-securing RF screened housing will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2560403