EMI shielding

board levelcagecan

PCB shielding cans, also known as board level shields or PCB EMI shields, are used for isolating circuits by creating a Faraday cage directly on the board that encloses the circuit to be shielded. There are many different types of board level shields but they can be thought of in two broad categories: one-piece and two-piece board level EMI shields. The term PCB shielding can typically refers to a one-piece shield that is soldered directly to the PCB. The typical one-piece board level shield consists of a stamped metal can (usually a rectangle) that is soldered directly to ground pads or through grounding vias on the PCB. There is a very wide range in the degree of soldering points between the shield and the ground plane of the PCB. For example, in the most extreme case, the shield can be continuously soldered around the perimeter of the can where it mates to the board. This essentially provides a complete Faraday cage and provides among the highest level of shielding effectiveness. Other methods include solder pads every 2-4mm around the perimeter and pins that are soldered on the back side of the board as these pins protrude through vias or through holes. The advantages of one-piece board level shields is that they can provide a high level of shielding effectiveness and they can be among the lowest cost solutions. Typical Shortcomings of One-Piece PCB Shielding Cans The disadvantages can be numerous. If the shield can is installed during the reflow process, you lose the ability to inspect and/or rework the board after reflow.