“As the new generation of passenger cars increasingly rely on millimeter-wave radar technology to improve the safety of drivers and passengers, the margin of error left for these advanced safety systems becomes smaller and smaller. However, as the core of the active safety system, the millimeter-wave radar microcontroller (MCU) serves increasingly complex subsystems and applications, and often has to work under harsh environmental conditions, which further reduces the errors of millimeter-wave radar electronics. The tolerance is compressed to the limit.
As the new generation of passenger cars increasingly rely on millimeter-wave radar technology to improve the safety of drivers and passengers, the margin of error left for these advanced safety systems becomes smaller and smaller. However, as the core of the active safety system, the millimeter-wave radar microcontroller (MCU) serves increasingly complex subsystems and applications, and often has to work under harsh environmental conditions, which further reduces the errors of millimeter-wave radar electronics. The tolerance is compressed to the limit.
For example, in the hot summer, when the car is idling, the temperature of the radar MCU responsible for controlling the automatic emergency braking (AEB) system will gradually rise-when the car accelerates, the cooling structure on the board will dissipate heat, and at the same time AEB There must not be any delay in the function. The system must be up and running immediately and respond in real time to constantly changing and challenging driving conditions. Even leaving aside the safety hazards caused by lagging response or system failure, when the radar system fails, at least heavy vehicle maintenance is required, which will have a negative impact on customer satisfaction.
To avoid such problems, the MCU itself, the MCU manufacturing process, and the target subsystem containing the MCU must have the highest possible quality. Next, this article will describe several factors that affect the quality of millimeter-wave radar MCUs, as well as improvement opportunities adopted by industry leaders such as NXP.
Understand customer use cases
As the “brain” of active safety systems, millimeter-wave radar MCUs need to consistently provide accurate data under any circumstances. At the level of Electronic components, NXP has demonstrated how intermittent system failures can be effectively mitigated inside the MCU: redundant cores and memory storage libraries can ensure the greatest degree of data integrity. The calculations performed on one core will be verified by other cores, and the decision tree will arbitrate accordingly. A similar redundancy mechanism is usually built in the subsystem where the MCU is located to help identify and eliminate errors on multiple layers to prevent the errors from spreading to other on-board systems.
The key element to achieve this result is that we have to understand customer use cases in a very in-depth and detailed manner, infer and reconstruct the parameters of customer test cases and software functions, and finally verify the MCU to ensure that it can play a role in these precise use cases. The more we know about customer use cases, the more effective we can build verification and test suites to fully test our systems under various working conditions. What is the customer’s startup sequence? What is the utilization rate of each core? What instructions do they run? The understanding of these issues will help to fully test the MCU, analyze the result data and feed the data back to your own development workflow to ensure the continuous upgrade of next-generation products.
Supplier management and collaboration quality improvement
In terms of managing chip manufacturing partners, ensuring and improving the quality of MCUs, NXP firmly believes in this principle: “Trust is necessary, but verification is also necessary.” NXP itself has rich experience in fab operations and can select Supplier with the most stringent process discipline level. The accumulation of technology over the years also gives us the ability to guide suppliers to complete any necessary process improvements.
This requires suppliers to maintain close collaboration and communication from the senior management to the engineering department, and understand that NXP will be deeply involved in the testing, verification and technical characterization phases, and we will be involved at any time when necessary. Before starting the production process, we will test products on the production line of the target fab, define the differences, customize the process as needed, and strive to do the necessary work to achieve excellent process consistency, thereby minimizing the impact Factors of MCU quality.
Communication and transparency
When a supplier has a quality problem that needs to be resolved as quickly as possible in a comprehensive and transparent manner, NXP’s own manufacturing expertise will also come in handy. We maintain close cooperation with suppliers, take quick action, identify problems as soon as they occur, quickly control them, and conduct necessary root cause analysis. When a problem occurs, NXP has a complete process: close the corresponding production line, and limit the problem to the smallest subset of materials as much as possible.
It is also important that NXP will promptly and proactively inform customers of these manufacturing issues. When a quality defect is detected, we do not consider the “acceptable threshold” and do not accept the convention that the product can fail several times, but directly light up the red light. Our purpose in doing this is to communicate and fix the problem as early as possible to avoid the affected device from affecting the end customer. In this regard, we use a very detailed and comprehensive traceability system that allows us to track the entire process of each MCU from production to delivery.
Continuously improve quality
Quality performance is usually measured in parts per million (PPM), that is, the number of defective devices in one million devices. This is the consensus of the industry. Of course, the ultimate goal is to reduce the defect rate per million to zero, but mass production is difficult to achieve.
NXP promotes a continuous quality improvement culture in all internal and external factories. This reflects our determination to meet and exceed customer quality expectations. As we often say, excellent quality is a journey, not an end. During this journey, we can proudly say that since the beginning of ADAS mass production in 2013, our PPM indicators have been optimized by more than 60%. This is the progress that NXP is constantly pursuing.