Designing today’s automotive power sub-systems is an enormously complex business. What makes it complex? Modern cars, whether powered by engines or motors, have more and varied power requirements than ever before, with as many as 100 programmable Electronic Control Units (ECUs) helping to run everything from the engine and power train to infotainment, communications, and safety and driver-assistance systems. The complexity is only increasing as car technology rapidly advances toward more sophisticated driver-assistance systems and self-driving cars.
So it’s not surprising that the automotive sector has overtaken computers and communications as the fastest-growing market for power electronic systems. As in-vehicle power electronics grow more complex and control more of a car’s functions, several design factors become even more critical:
- Ruggedness and reliability: Components must withstand the rigors of everyday use and the extremes of temperatures and humidity.
- Longevity: Consumers expect their vehicles to function longer — ten years or more — than other electronic devices such as mobile phones.
- Interference: Electronic components and systems in the vehicle must coexist with each other without causing interference.
To ensure components don’t fail once they’re embedded in electronics systems, the automotive industry has developed strict quality standards for component manufacturing and testing. Only parts that meet these standards can be qualified for automotive use.
Key Automotive Qualification Standards
- AEC-Q100 Qualification - AEC-Q100 is a failure mechanism based stress test qualification for packaged integrated circuits. The Automotive Electronics Council (AEC) is based in the United States and was originally established by three major automotive manufacturers for the purpose of establishing common part-qualification and quality-system standards. AEC-Q100 is an industry standard specification that outlines the recommended new product and major change qualification requirements and procedures for packaged integrated circuits.
- IEC60664-1 - The dimensioning of clearances aims to choose an air distance able to withstand the maximum peak voltage across the air gap between two parts at different voltages. According to Paschen’s law, the behavior of air to withstand a maximum voltage value is in relationship with air pressure. Essential for high altitude applications are effects linked to dimensional parameters like clearances and creepage distances due to reduced air pressure with increasing altitude. The electrical field stress through solid insulation under dedicated environmental parameters is depending on the device construction and is validated by test procedures according to the applicable product standards for application altitudes of 2000 m only. Above 2000 m the stated parameters Ue, Ui, Uimp and Ie for the devices have to be re-evaluated. The correction factor for operation at altitudes above 5000 m and below 6000 m, for example, is 1.48.
- VDE0884-10 - This standard concerns the maximum transient voltages, which a device can withstand without a breakdown in isolation under various test conditions. VIOTM, for example, is defined by IEC 60747-5-5 and VDE 0884-10 as the peak transient voltage that the isolator can handle without breaking down. This standard is based on a partial discharge test rather than voltage breakdown, and on the isolation withstands voltage.
- CTI 600 Mold Material - The Comparative Tracking Index or CTI is used to measure the electrical breakdown (tracking) properties of an insulating material. Tracking is an electrical breakdown on the surface of an insulating material wherein an initial exposure to heat chars the material, and the char is more conductive than the original insulator, producing more current flow, more heat, and eventually complete failure. The minimum required creepage distances over an insulating material between electrically conducting parts in apparatus, especially between parts with a high voltage and parts that can be touched by human users, is dependent on the insulator's CTI value.
For more information, see the Automotive Applications page.