Conductive Silicone Rubber in Engine Control Units (ECUs)

Core Properties of Conductive Silicone Rubber

• Excellent conductivity: The volume resistivity can usually be as low as 10⁻³~10⁰Ω・cm, which can meet the basic requirements of electromagnetic shielding and conductive connection;
• Wide temperature range stability: It can maintain elasticity and conductivity in the range of -60℃~200℃ (some special models can reach above 250℃), easily coping with extreme temperature fluctuations of -40℃~150℃ in the engine compartment;
• Excellent elasticity and sealing performance: The Shore hardness is mostly between 30~70A, and the compression set rate is less than 20% (under the condition of 150℃×70h), which can closely fit irregular surfaces to achieve reliable sealing;
• Resistance to environmental erosion: Insensitive to oil, coolant, ozone, and humidity, and can resist chemical corrosion in the engine compartment for a long time;
• Shock absorption and buffering capacity: The dynamic elastic modulus is adapted to the high-frequency vibrations (10~2000Hz) during vehicle driving, which can effectively absorb impact energy.

Challenges in the Working Environment of ECUs

• Electromagnetic interference (EMI): The engine ignition system, motors, sensors, etc. will generate a lot of electromagnetic radiation. If ECUs are interfered, it may lead to signal distortion, control logic disorder, and even engine failure;
• Environmental sealing requirements: The intrusion of dust, water vapor, and oil will cause short circuits or corrosion of the internal circuits of the ECU, affecting its service life;
• Mechanical stress impact: Vibrations during vehicle driving (especially during idling and sudden acceleration) may cause loosening of solder joints of internal components and poor contact of connectors.

Key Applications of Conductive Silicone Rubber in ECUs

1. Electromagnetic Shielding Seals

• During installation, the sealing ring is in close contact with the metal shell under the action of compression force, forming a continuous conductive path, reflecting or absorbing external electromagnetic radiation. The shielding effectiveness can reach 60~100dB (100MHz~10GHz frequency band), far exceeding the EMC standard requirements of the automotive electronics industry;
• For shell joints with complex shapes (such as ECU shells with cooling fins), the flexibility of conductive silicone rubber can adapt to irregular surfaces, avoiding shielding loopholes.

2. Flexible Conductive Connection Components

• Conductive gaskets: Placed between the PCB board and the metal shell, they not only realize module grounding but also offset the dimensional differences caused by temperature changes through elastic buffering, reducing contact resistance fluctuations (usually controllable within 50mΩ);
• Connector conductive contacts: Replace traditional metal shrapnel to form flexible conductive contacts between the sensor plug and the ECU interface, reducing the risk of poor contact caused by vibration, especially suitable for key signal transmission such as crankshaft position sensors and oxygen sensors.

3. Integrated Heat Dissipation and Shock Absorption Components

• Heat conduction: The thermal conductivity can reach 1~3W/(m・K), transferring the heat of power devices on the PCB board to the metal heat dissipation shell;
• Vibration isolation: Attenuate vibration energy through its own elasticity, avoiding fatigue damage of devices caused by hard connections.

Application Advantages and Future Trends

• Integrated design: Reduce the number of parts (such as combining seals and shields into one), reduce assembly complexity, and improve production efficiency;
• Lightweight advantage: The density is only 1/5~1/3 of that of metal, which helps reduce vehicle weight and save energy;
• Cost controllability: By adjusting the type of conductive fillers (such as replacing precious metals with carbon-based ones), the material cost can be reduced while meeting performance requirements.