The following description relates to shielding and in particular to radio frequency and electromagnetic interference shields.
Many electronic devices such as telephones, computers, personal digital assistants, televisions and the like have components that emit electromagnetic radiation. This radiation can interfere with the operation of other electronic components within the device or other equipment closely located. Shielding is often used to minimize the electromagnetic radiation. Various types of shielding are employed and have size, shape and attachment drawbacks.
Often shielding for circuit boards leave gaps between the board and the shield and leakage can occur. Also shield covers that are secured to the circuit board using ground clips or other common attachment devices often become unfastened or loose due to vibration or handling. Sometimes the shield covers even become detached from the clips. The resulting gaps can lead to electromagnetic interference problems. In instances where a shield is soldered to the circuit board and if the electronics on the board need tuning or reworking the shield is difficult to remove and replace.
Therefore, a need exists for improved radio frequency shield covers.
A shield cover is provided. The shield cover includes a top surface, four side walls, each side wall extending substantially perpendicular from an edge of the top surface, and one or more first securing tabs extending from at least one of the side walls. Each of the one or more first securing tabs includes a leg and a foot, the foot including a tapered edge. Each of the one or more first securing tabs, when engaged, is adapted to draw the shield cover toward a top surface of an associated circuit board and reduce gaps created between the cover and the circuit board. The circuit board includes one or more slots through the circuit board to receive the one or more securing tabs. The one or more first securing tabs are engaged by twisting the leg of the securing tab such that the tapered portion of the foot contacts a bottom surface of the circuit board and resultantly pulls the shield cover toward the top surface of the circuit board.
The details of one or more embodiments of the claimed invention are set forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description, the drawings, and the claims.
Like reference numbers and designations in the various drawings indicate like elements.
Embodiments of the present invention provide systems and methods of radio frequency shield covers.
In one embodiment, shield cover 100 includes one or more dividers 107 and a plurality of slots 109 adapted to receive or secure dividers 107. Dividers 107 partition shield cover 100 into a plurality of smaller shields used to shield selected areas of a circuit board. In one embodiment, dividers 107 are secured to shield cover 100 by spot welding, soldering, tack welding, rivets or another suitable attachment device.
In one embodiment, side wall 110 aligns substantially flush with an outer edge of circuit board 130 and tab 125 grasps bottom of edge 133 via an outer edge or perimeter of circuit board 130. In another embodiment, circuit board 130 includes a slot 150 in circuit board 130 and tab 125 extends through slot 150 and grasps the bottom edge 133 of circuit board 130 via slot 150.
In one embodiment, shield cover 100 includes one or more of tabs 125 along side walls 110 for securing shield cover 100 to circuit board 130. In another embodiment, shield cover 100 includes one or more dividers 107 each having one or more tabs 125 extending from dividers 107 securing shield cover 100 to circuit board 130.
In operation shield cover 100 is sized for a specific application and fits onto circuit board 130 and is secured via one or more tabs 125 located along side walls 110 and/or dividers 107. In one embodiment, tabs 125 located along side walls 110 are stamped or punched from the same piece of material that cover 100 is made from. In another embodiment, tabs 125 located on dividers 107 is stamped or punched from the same piece of material that dividers 107 are made from. In one embodiment, shield cover 100 including any tabs 125 are stamped from beryllium copper, sheet brass, nickel silver, thin mild steel or the like. In another embodiment, shield cover 100 including any tabs 125 is made of a material providing EMI shielding and is suitably ductile to allow tabs 125 to be twisted up to 105 degrees without breaking off.
Circuit board 230 is shown with a plurality of ground etches 275 and associated gaskets 279. In one embodiment, gaskets 279 are EMI gaskets e.g. metallized nylon over foam EMI gaskets or the like. Gaskets 270 are adapted to secure to circuit board 230 and cover ground etches 275. As illustrated, gaskets 279 correspond to the outline of side walls 210 and dividers 207 so that when cover 200 is secured to circuit board 230 side walls 210 and dividers 207 align with gaskets 279. It is understood that although multiple gaskets 279 are shown to correspond with multiple dividers 207, any combination of dividers 207 and gaskets 279 may be employed as required by the specific application. Gaskets 279 aid in reducing the gap between side walls 210, and dividers 207 and circuit board 230. Tabs 225 pull shield cover 200 down to engage with and compress gaskets 279.
In one embodiment, tabs 225 located along side walls 210 are stamped or punched from the same piece of material that cover 200 is made from. In another embodiment, tabs 225, located on dividers 207, are stamped or punched from the same piece of material that dividers 207 are made from. In one embodiment, shield cover 200 including any tabs 225 are stamped from beryllium copper, sheet brass, nickel silver, thin mild steel or the like. In another embodiment, shield cover 200 including any tabs 225 is made of a material providing EMI shielding and is suitably ductile to allow tabs 225 to be twisted up to 105 degrees without breaking off.
In one embodiment, gaskets 379a and 379b are EMI gaskets e.g. metallized nylon over foam EMI gaskets or the like.
Shield covers 100 and 200 as discussed above are secured to associated circuit boards using one or more tabs 125 and 225, respectively and reduce any gap produced between the cover and circuit board. As a result, electromagnetic radiation is reduced.
A number of embodiments of the invention defined by the following claims have been described. Nevertheless, it will be understood that various modifications to the described embodiments may be made without departing from the spirit and scope of the claimed invention. Accordingly, other embodiments are within the scope of the following claims.