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Sony publishes an interview with its automotive image sensor designers explaining why the company is still having difficulties on this market. Few quotes:Automotive settings present harsh conditions to overcome, such as high temperature, humidity, and vibration, while high quality must be ensured. This meant that the design, manufacturing, and quality assurance divisions had their own unique challenges to address and conquer.
J.Azami: In the beginning, the project started to develop automotive image sensors modelled on security image sensors. The basic idea was that the security sensors had the attributes that were useful for automotive sensors, such as extensive durability and the ability to capture images in dark places. However, once the business became established, we found out that the automotive image sensors had a whole set of different requirements. Those days, I would visit customers overseas and come back feeling deflated at their feedback, time and again.
Y. Sakano: I have always been interested in HDR, and Azami-san’s invitation was all welcome. But there was a problem. Image sensors for automotive cameras require very high quality standards, and initial defect rate had to be extremely low. Normally, other image sensors are improved iteratively through a course of repeated production cycles. Whereas, automotive image sensors must be manufactured by mature processes, and this was an unwritten rule.
M. Nishizuka: The standards like IATF 16949 and ISO 26262 are clear enough themselves, but it was very difficult to adapt our work processes to them. To probe and understand each standard was difficult in itself, but it was even more challenging to align our project members to this understanding. It was necessary that every member understood and implemented the ways of doing things that were unfamiliar to us.
T. Shimozono: The requirements set out in those standards like IATF 16949 and ISO 26262 were very specific, different from ones we normally handled. We needed to find out the ways to apply them in manufacturing in practice. Another particularity of automotive applications is that so many customer inspections were involved. How we interpreted the standards often turned out to be unsatisfactory to our customers, who gave us feedback with their specific requests, as well. It was such hard work to meet all these requirements and requests.
M. Nishizuka: The dashboard can heat up over 100°C in summer time. So, the sensor must be able to withstand these temperatures. Secondly, driving on a road causes vibration. It takes extremely high levels of engineering to make precision devices that withstand vibration and operate without making errors.
Also, as Sakano-san mentioned it earlier, there is the zero-defects expectation, that is, to minimize the initial defect. The request was below 1 ppm, which means fewer than one defective unit in every one million produced. In order to meet the requirements of both high performance and reliability, we had to set up the product evaluation environment as strict as never before.
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