Material Gains
Will Self-Driving Vehicles Sharpen Our Focus on Reliability?
The nature of ADAS could revive CAF fears.

In a previous column, I enthused about the prospects for 5G to transform lives for the better, supporting new services that take advantage of ultra-reliable low-latency communication (URLLC) and capacity for massive machine-type communications, or mMTC. One place the impact of 5G will be felt is on the road, where machines will assume the entire decision-making from humans.

Leveraging 5G’s guaranteed latency below 1ms for effective real-time performance, the prospects for mission-critical V2X vehicle-to-everything communication can become real. Vehicle-to-infrastructure interactions with smart signs should result in smoother, safer journeys, and vehicle-to-vehicle connections that share information about presence and position should avert huge numbers of “sorry, I didn’t see you” accidents. Of course, it will take time for smart infrastructure to evolve and for V2X-equipped cars to enter the market. But it’s quite clear, even now, that cars are destined no longer to be islands. Ultimately, it’s a matter of when, not if, our road journeys come to be handled by fully self-driving vehicles.

There are still many technical hurdles to overcome, as well as legal issues, not to mention cultural obstacles. On the other hand, we can gain tremendous benefits by separating the privilege of personal mobility from the burden of car ownership. Cost-effective services delivered on a pay-per-use basis can extend access to groups excluded by current models based on vehicle ownership, such as those on low incomes or allowing the elderly to lead independent and active lifestyles into later stages of life than ever before. As we age, I suspect that more of us will tune into the benefits of being able to summon a self-driving vehicle whenever we need, be it to get somewhere or just for a change of scenery.

Parking is another problem that will become much easier to deal with. Self-driving cars will move from one job to the next, no stopping or waiting. Towns will no longer need to devote precious real estate to vast parking areas or commit resources to collecting payments and monitoring proper usage. Homeowners could utilize driveway and garage space for other purposes. W e can all enjoy the prospect of residential streets no longer lined by parked cars.

This all has implications for the self-driving vehicles themselves. They obviously need to become far more intelligent, and nonstop motion will place a much greater load on components and systems than most conventional privately-owned vehicles would experience, resulting in faster wear-out and shorter lifetime.

We will also need to consider how to maintain them during their operational life. These “servers on wheels” will quickly become outdated, embodying standards that will become eclipsed and obsolete in a short timeframe after manufacture. Ensuring compatibility between infrastructure upgrades and multiple generations of vehicles could be a challenge. Together, compatibility issues and high duty cycles may require important on-board electronic equipment – particularly modules associated with machine vision and off-vehicle communications – to be renewed and upgraded at specific intervals, much like consumable items such as tires or engine drivebelts are today. On the other hand, cars may simply become consumables to be discarded in favor of a new and more up-to-date model, just as we now move easily from one mobile phone to the next at the end of each contract.

Either way, the primary onboard systems and safety systems must operate continuously and must be 100% reliable. Reliability is a multifaceted issue in such a complex interconnected environment comprising vehicles’ on-board systems, cellular networks, data-center servers, and more. On-board the vehicle, high operating temperatures, frequent temperature cycling, shock and vibration, and electromigration are all issues that challenge reliability. As these systems become increasingly mission-critical, electronic manufacturers and materials suppliers need to understand the various deterioration mechanisms and effective techniques for dealing with them.

At the substrate level, where I feel most qualified to comment, conductive anodic filament (CAF) formation is a key factor in the degradation of the PCBs that provide the underpinnings for every vehicle’s on-board systems. The ingredients for CAF include the presence of charge carriers, voltage bias and moisture; a recipe we can guarantee in any automotive operating environment. Initially aided by degradation of the dielectric over time, due to the presence of impurities in the material, electrochemical action drives ion migration that eventually causes short circuits, leading to electrical failure.

Mitigating the risk of CAF requires controls at all stages of manufacture. Ventec has developed optimized treating processes to ensure complete wetting of the glass fabric with the resin to ensure an optimum chemical bond. Current research is targeting CAF-formation resistance of low-loss materials for automotive use at high data rates. Industry bodies are also active; the High-Density Packaging User Group (HDPUG) is moving to increase industry understanding of the issue and suggest processes and practices to mitigate the risks.

Material suppliers should support initiatives such as these and take part in industry testing programs, compare products with those of peers, and work with OEMs to develop effective countermeasures and position new products properly in the market.

Alun Morgan
Alun Morgan

is technology ambassador at Ventec International Group (ventec-group.com); alun.morgan@ventec-europe.com.