Generally speaking, the basic structure of an automobile hasn’t changed for decades: four wheels, engine, radio, doors, hood, etc. But, what has changed considerably are automotive electronics. Since the 1970s, electronics have gone from about 5% of the bill of materials (BOM) to over 35% when electric vehicles and hybrids are factored into the equation.
The inclusion of more automotive electronics should be good news for the electronics industry, but the unique use environments of vehicles present reliability issues that traditional board design and testing don’t take into consideration – and failures result.
Let’s take a look at how and why automotive electronics require consideration beyond conventional means in order to optimize board and component reliability.
The Four Categories of Automotive Electronics
The four-decade, +/-30% spike in automotive electronics has necessitated specific categorization:
- Functional electronics (critical to vehicle operation): anti-lock braking systems (ABS), automatic transmission control, starters, fuel injection, headlights, electromechanical parking brakes
- Regulatory compliance electronics (mandated by NHTSA or DOT): airbags, emission controls, backup camera, collision detection radar
- Differentiating electronics (unique, customer-oriented technologies): infotainment, adaptive cruise control, Wi-Fi connectivity and advanced driver assistance systems (ADAS)
- Growth opportunities (for vehicles in general): collision detection, in-dash displays, heads-up displays (HUD), enhanced infotainment systems, vehicle-to-vehicle communication (V2V) and improved Wi-Fi
Not so neatly categorized is the advent of autonomous vehicles. They offer great potential for improvements to vehicular traffic – increase in highway capacity and traffic flow, faster response times, less fuel consumption and less pollution. Automakers are working hard to make sure these vehicles operate safely in both everyday traffic and harsh off-road environments along with overcoming some skeptical consumer perceptions.
Testing for Failure
The typical computer environment in which boards are designed and tested offers:
- Immobility/limited vibration
- Little to no mechanical shock
- Low humidity/controlled temperatures of office environments
- Predictable duty cycles
While those dynamics are ideal for, say, household electronics, the stressors to which automotive electronics are exposed change the game completely:
- Harsh mobile environments
- Large temperature swings
- Sustained periods of vibration and, in the case of accidents, sudden shock
Couple this with ever-shrinking feature sizes – environment and movement sensors, on-board computer systems and networks, and vehicle control actuators – suddenly, best performance predictability is on a sliding scale over one, five or even 10 years of driving, and degradation takes its toll.
Semiconductors and Board Level Reliability
The small scale of automotive electronics makes regulating the electric field of fundamental semiconductors precarious, and often causes unwanted effects that have a minimal amount to do with wear. When semiconductors degrade and their performance lags, it can generally be traced back to transients and thermal extremes associated with automotive environments:
- High temperatures accelerate dielectric breakdown and bias temperature instability
- Cold temperatures accelerate hot carrier effects
While DfR Solutions has developed innovative methodologies to assess semiconductor mechanisms for sub-0.5 micron technologies, high-speed integrated circuits and PCB over-constraint in automotive applications still warrant the need for advancements in circuit boards, including:
- Structure-based electronics
- Low- and high-temperature substrates
- Flexible electronics
Design for Reliability Best Practices
The challenges presented by automotive electronics are real, but they aren’t insurmountable when design for reliability best practices are applied early in the lifecycle – before the board is even built – using Sherlock Automated Design Analysis™ software. Sherlock helps rigorously qualify products against automotive stressors, including thermal, shock, vibration and higher density board challenges. The result? Reliable products. Less time spent on product qualification. Reduced test cycles and related costs.
As in other industries, rapid advancement in automotive electronics is and will continue to be inevitable. Contact us to find out what Sherlock can do to help you keep pace! Also, learn about Sherlock and the semiconductor wearout module in our webinar, Assure Reliable Performance of Semiconductors in Aerospace and other High Performance Industries.