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.

Actually, there is another option: a SHIELDING CLIP can be used instead of a traditional shielding frame but still need shielding can. This approach can reduce cost and simplify the assembly process. I have compared the shielding frame and shielding clip in terms of cost and maintenance in the table below.

	Shielding Frame	Shielding Clip
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Component cost	Punch tooling one time charge about USD3,000~USD4,000 Unit cost about USD0.25~USD0.45	One clip: USD0.014 Assume one shielding can need 4~8 pcs then its unit cost is about USD0.056~0.112.
SMT constraint and cost	Poor coplanarity for Shielding frame slow the SMT efficiency. Lower AOI coverage yield. Must be the final step to mount on the board. 4.Need to make tape-on-reel tooling.	No coplanarity issue. No effect for AOI. Be able to handle by speed pick and place machine.
SMT constraint and cost	The cross rib on the frame will interfere with component while repair. Most of the time need to cut off the rib or damage the frame for repair.	Easy to repair.
Maintenance cost	The test point can’t locate under the cross rib or frame edge.	Easy to place the test point.
Test	Shielding-can is easily to place upon the frame without special training.	Need special training for the operator to install shielding-can into it.
Assembly	Shielding-can is easily to place upon the frame without special training.	Need special training for the operator to install shielding-can into it.

Although shielding clips offer several advantages and potential cost savings, there is still one major concern that needs to be considered. A small gap may remain between the shielding can and the PCB. The RF engineer should verify whether this gap has any impact on the shielding effectiveness or RF performance.

I also listed some of the technical data provided by the shielding clip supplier below

• What is the clip retention force? How can we calculate whether the clips can prevent the shielding can from coming off during impact or drop testing? According to the supplier, each clip provides approximately 1 kgf of retention force to hold the shielding can in place. We therefore need to consider the weight of the shielding can and the acceleration or impact force generated during the drop test. For most shielding cans, four clips should be sufficient, with one clip positioned near each corner.
• What is the mounting force that each clip can withstand on the PCB? According to the supplier, each clip can withstand at least 5 kgf of push force. This should be sufficient for most consumer electronics applications.
• How far apart should the clips be placed? According to the supplier, one clip every 25 mm should be sufficient.
• What stencil thickness should be used? According to the supplier, a stencil thickness of 0.10–0.12 mm is recommended. A thicker stencil will deposit more solder paste, which can increase the height of the solder joint and result in a larger gap between the shielding can and the PCB.

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