What is Board Level Shielding? What is a Two-piece and One-piece solution - When should you use one over the other?
Editorial Team - EMC Directory
Board-level shielding (BLS) refers to the use of metal cages or enclosures on printed circuit board (PCB) to protect sensitive electronic components from electromagnetic interference (EMI) and radio frequency interference (RFI) and reduce crosstalk issues in the PCB. The metal enclosure acts as a Faraday cage, blocking electromagnetic radiation signals from entering or exiting the shielded area of the PCB. This protects the critical circuits and components within the enclosure from external EMI/RFI disturbances and also protects other circuits and components near the shielded enclosure and nearby electronic devices from internally generated EMI/RFI by the enclosed components and circuits.
Figure: Board-level shielding and one-piece, two-piece shield design shown
The metal enclosures providing board-level shielding are made of conductive materials such as aluminum, stainless steel, nickel-silver, cold-rolled steel, beryllium copper, and phosphor bronze. These metallic cages are available in one-piece, two-piece, multi-cavity designs and custom configurations to offer BLS. They come in a variety of material options, shield sizes, surface mounting, and through-hole mount configurations, with customization options available. Board level shielding or PCB level shielding, is an EMI shielding technique that significantly contributes to improving the EMC performance of the electronic device.Various configurations of board-level shield designs:
One-piece shield design:
In a one-piece shield solution, a single continuous piece of metal is used to cover the components and circuits needing protection. For a surface mount shield, the metal cage is attached or soldered to the PCB using alignment pins. In the case of a through-hole shield, it is attached to the PCB using mounting pins. It is a simple & economical shielding solution. This shield solution is also available in a multi-plane cover design.
Figure: One-piece shield design configurations
Pros of one-piece shield solution:Cons of one-piece shield design:
Use case: The one-piece shield design is used where access to covered components for repair is not necessary.
Two-piece shield design:
The two-piece shield solution consists of a metal frame that is soldered/attached to the PCB and a removable metal cover (or lid) that fits onto the frame. This shielding solution is available in the following configurations:
Figure: Two-piece shield design configurations
Pros of two-piece shield solution:Cons of two-piece shield solution:
Use cases: Two-piece shields are ideal for applications where frequent access to the shielded components is required, such as during prototyping, testing, and field repairs.
Multicav shield design: The multi-cavity shield design is a compartmentalized shield that combines multiple shields into one cover. It saves board space, reduces shield weight, and lowers overall costs. This shielding solution typically features a two-piece design with inner walls (frames) strategically placed and covered by a single removable metal cover.
Figure: Multi-cavity design
Peel shield design:The Peel shield design features an easy-to-remove or peelable top section for accessing components and circuits. The top section can be removed by hand with minimal force using a hook scriber or tweezers, eliminating the need for labor-intensive desoldering. This approach prevents damage to the board and components, thereby reducing the risk of increased scrap. After repair, the shield's top can be resealed using a replacement cover. The Peel shield is more economical and ideal for situations where infrequent access to shielded components is required.
Figure: Peel shield design
Key features of board-level shielding solutions:Applications: Board level shielding is used to suppress EMI/RFI board level in various electronics applications, including mobile phones & tablets, 2-in-1 notebooks, medical devices, routers, wireless meters, game consoles, point of sale (POS) equipment, wireless speakers, wearables & IoT, drones, servers, and more.
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