For most RF (Radio Frequency) devices, the PCB needs a shielding frame or shielding can to reduce the effects of EMI (Electromagnetic Interference). A common design uses a shielding frame that is soldered to the PCB, along with a separate shielding can that fits over the frame to enclose and isolate the RF circuitry.
This means that two sets of stamping tools are typically required before implementing this solution, which adds to the initial tooling cost. In addition, the shielding frame must be mounted to the PCB using the SMT machines and process. This requires tight flatness control to ensure reliable solder joints. Most shielding frame designs require a maximum flatness of around 0.12 mm, while some even require flatness below 0.10 mm.
This can be challenging because typical stencil thicknesses are only around 0.10–0.127 mm or thinner. Maintaining such tight flatness requirements makes the shielding frame more difficult and expensive to manufacture.
