Authored By:
Lenora Clark
MacDermid Alpha Automotive, Waterbury, CT, USA
Paul Salerno
MacDermid Alpha, South Plainfield, NJ, USA
Senthil Kanagavel
MacDermid Alpha, Suwanee, GA, USA
Summary
Radio Detection and Ranging (radar) sensors require specialized materials and specific tolerances in order to optimize their function. However, although not new to many markets, such as the military and telecommunications, some of these materials and design sets are novel to the automotive industry. Their use is growing rapidly with the increase in autonomous driving and safety systems. Nonetheless, the specific design and fabrication bring challenges to the automotive supply chain.
As the automotive industry takes steps toward fully autonomous vehicles, there is a respective progression of increased safety systems in vehicles. The increase in quantity and function brings significant change to the electrical content and its level of sophistication. Historically, automotive circuit board assemblies were not considered complicated as they did not require fine features or advanced components. Now these aspects are a necessity as many systems require high density interconnect (HDI) designs with advanced packaging to support the processing and function of the safety systems. The processing speeds involved in making safety critical decisions effect design, fabrication, and reliability of the components delivered into the automotive supply chain.
Degrees of autonomy are described in levels from 0 to 5, with 5 being fully autonomous. Today, most cars function on a level of 1-2 with rapid growth in level 3 devices that provide the user conditional automation. This paper will discuss the current areas of growth that support level 3 autonomy, with a focus specifically on radar modules that bring perspectives of distance and speed to surrounding objects. The various systems used to support the automation of driving are housed under the phrase Advanced Driver Assistance Systems or ADAS.
Advanced safety systems require the car to react in response to external changes surrounding the vehicle. This takes the decision-making process away from the driver, and therefore, reliability is of greater importance than ever. This paper will investigate the chemical process changes needed to improve reliability, specific for radar module builds. It will discuss how radar designs challenge Printed Circuit Board (PCB) fabrication, what reliability requirements are needed, and review certain improvement options necessary to create a reliable system, including packaging considerations.
Conclusions
Significant advances are happening in the automotive space to deliver greater safety to passengers and pedestrians around the vehicle. These enhanced safety requirements utilize specialized technologies with enhanced requirements to achieve success. AS this research demonstrates it is imperative that the proper surface finish be chosen for high frequency applications. Enhanced solder alloys such as Innolot are a requirement to withstand the aggressive thermal cycle conditions required for advanced safety. Innolot in this testing shows a dramatic increase in thermal cycle resistance with superior shear strength. Lastly, the hybrid silver sintering adhesive will also extend product life by improving the thermal transfer away from the die.
Each of these materials provides improvements over the incumbent but could realize even greater improvement when used together in one design. It is critical to test individual material changes as well as those combined in the final design build for a complete understanding of end use life and performance.
Initially Published in the SMTA Proceedings
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