Automotive Electromagnetic Compatibility (EMC) – Using Conductive Paints to Protect Against EMI/RFI

Modern automotive design relies heavily on integrated computer systems to control key functions that improve performance, reliability, safety, and passenger convenience. Trends have pivoted away from power performance towards energy efficiency, forcing manufacturers to redesign control systems that places electrical components closer together. These changes increase the likelihood of electromagnetic interference (EMI) between systems, disrupting proper function through crosstalk. This situation makes automotive electromagnetic compatibility (EMC) problems a real concern for design engineers.

Although circuit design engineers try to minimize EMI by reducing frequency, current, and loop area, these methods are not always sufficient to bring circuitry into compliance. As a result, shielding is often required to preserve performance and safety.

EMI Shielding (Board-Level and Package-Level)

Electromagnetic interference (EMI) occurs when high frequency signals travelling short distances disrupt the proper function of either neighboring circuits or components within the same circuit. These are often referred to as board-level or package-level electromagnetic interference. Traditional mitigation strategies included using decoupling capacitors and metal stamping. But these solutions were both expensive and cumbersome. Board and package level paints present a practical solution for reducing EMI as they are light weight, cost-effective, and easy to apply in tight spaces.

RFI Shielding

Radio frequency interference (RFI) is interference caused by low frequency signals that travel longer distances to disrupt other devices – for example, a cell phone generating radio frequency signals that interfere with a neighboring device, such as a vehicle’s infotainment system. RFI protection is therefore paramount to safeguarding vehicle control systems. The classic solution was to place the PCB in an aluminum housing sealed with an electrically conductive gasket material; however, due to cost and weight constraints, this strategy was replaced with using plastic enclosures coated with RFI shielding paints. Here, the inner walls of the enclosure are coated with an RFI shielding coating, which not only protects the enclosed PCB from incoming RFI signals but also shields neighboring devices by containing radio frequency signals generated from the PCB within the enclosure.

Customized Solutions for the Automotive Industry

Choosing the right conductive coating is about balancing constraints with requirements. The substrate dictates which binder system is situable – for example, acrylic for plastics, epoxy for metal and concrete, or water-based urethane, for drywall while attaining the required shielding performance depends on which conductive filler is used. MG Chemicals has engineered an extensive portfolio of materials applicable to a wide range of automotive parts and systems including

Customized Solutions for the Automotive Industry
  1. Power train management
  2. Control Area Networks (CAN)
  3. Advanced Driver Assisted Systems (ADAS) including lane departure warning systems, adaptive cruise control, collision warning avoidance,
  4. Airbag deployment
  5. Active braking systems
  6. Integrated infotainment systems
  7. Tire pressure monitors
  8. Ignition systems
  9. Various LED component systems such as power supplies and control boards.

Electric vehicles (EVs) have an even higher demand for EMI shielding materials compared to conventional automobiles. In EV battery packs, conductive paints reduce electrical resistance between active materials and the aluminum foil along the wall of battery cells, which improves charging and discharging performance.

Our conductive paints also enhance EMC compatibility of electric motors and onboard chargers by shielding plastic enclosures and PCB components at the module level.

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