EC6011 Electromagnetic Interference and Compatibility

1. EC6011 Electromagnetic Interference and
Compatibility

2. PCB level Shielding

4. Why Shielding ?
• Immunity
• Achieve EMC environment
• Miniaturization
• Avoid the unwanted EM signals

5. What is PCB level Shielding?
• Used to a metallic plate or non - metallic
sheets, and to provide the EMC for PCB.
• Improve the efficiency
• Costly maintenance

6. Types of material
• Stainless steel
• Cu
• Tin
• Brass or beryllium copper
• Multiple Tin
• Multiple spring fingers
• Metal plate

7. Consideration to PCB Shielding
• Circuit design
• Grounding
• Partition
• Isolation
• Material selection(E or H field)
• Thickness, character
• filtering

8. Types of PCB
• Plane (single) – converter , relay circuits
• Multi-layer – PC mother board,
-- PGA IC’s board (switches, R, M)

9. Light weight PCB
• Less weight
• Sensitive circuits (Aircraft, satellite, smart phones)
• Difficult to design
• But, provide good Shielding

10. Conductive coating
• Poly carbonate (125 micro meter)
• Ni (50 nano meter)
• Tin (5 micro meter)

11. Magnetron sputtering
(thin film deposition manufacturing process)
• Is the technique to achieve conductive coating
• Vacuum deposition
• Metal, non metal
• Like, Electro plating

12. Why Ni choose?
• Non- Oxidation material
• Not react with Tin
• Good Adhesion (bonding)
• 200 ‘C temperature
• Avoid device RE also
• 60-80 dB
• 30 MHz – 2 GHz

13. Mold in Place (MIP)
• Combination of (Gasket + Multi compartment material)
• Small
• Gasket : Electrically conductive Elastomer
• Multi compartment material : metal + plastic + polymer
• Act as a sandwiched b/w PCB & Housing
• Technique behind, compression, injection
• Advantages: soldering, testing, calibration, repair all are
possible
• Ex: cell phone & LCD monitors

14. Board level Shielding
• Shield + thermal cooling
• Heat sink
• Heat pipe
• Spring fingers

15. Disadvantages of PCB
• Cost
• Weight