PCB Shielding case Design Guide
In the design of RF hardware, electromagnetic interference needs to be considered, and the design of the shielding case is essential. Today's article the Shenzhen PCB manufacturer - SysPCB will introduces the design specifications of shielding case and the types.
Some notes about the design of the shield case are as follows:
1. The material of the shield case can be zinc-tin-nickel-alloy or copper-nickel-zinc alloy (good performance and easy processing) or stainless steel (only shield cover). The material of the shielding frame is zinc-tin-nickel-alloy or copper-nickel-zinc alloy to ensure good welding performance. Material thickness is generally between 0.1-0.2mm, 0.2mm is more commonly used.
2. Shielding case pad width is between 0.7-1mm.
3. Design of heat dissipation holes: When considering heat dissipation, heat dissipation holes need to be added. The hole diameter is generally between 1-1.5mm, and the hole spacing is about 5mm.
4. When considering batch soldering, it is necessary to reserve a vacuum washing area in the middle of the shield case (guaranteed to be a flat surface and no holes), generally the diameter of this area is not less than 5mm.
5. The component’s pad should be at least 0.3mm away from the edge of the shielding case pad.
6. When soldering, consider the solder height of 0.1mm, and at least 0.2mm above the top of the shielding case.
7. 2-1-2-1mm mode design: Soldering of the shielding case as far as possible not whole soldering, so it will cause tin stacking. Generally 2-1-2-1mm mode is adopted, with 2mm contact and 1mm suspension for easy tin climbing, which can ensure the adhesion strength of the shielding case.
8. If the shielding case is of symmetrical shape, you need to add positioning holes or regular triangle lines.
Regarding the soldering form of the shielding case, there are currently three main types as follows:
Single piece soldering
The single piece is directly soldered to the circuit board, and the single piece is easy to process and the cost is low. The biggest disadvantage is that once soldering is not easy to remove, it makes maintenance and debugging more difficult.
Two pieces of detachable soldering type
The two-piece type is composed of a frame and a cover. The frame is generally made of copper-nickel-zinc alloy for easy soldering, and the cover is generally made of stainless steel, which is cheaper.
The advantage of the two-piece type is that it is convenient for maintenance and inspection. The disadvantage is that it needs to open the mold twice and the cost is higher.
Shielding case clip + single shielding case
Now the shielding case clip is used instead of the frame, which can save the mold opening cost of the frame. The shielding case clip is fastened by the buckle. At least 4 pieces are required, which can be implemented flexibly. The disadvantage of this solution is that the clamping force of the buckle needs to be studied, and it is not suitable for use in scenarios with high vibration intensity.
Conclusion: According to the characteristics of the above schemes, a suitable design scheme needs to be selected in combination with actual application scenarios.