Why are automotive chips still rare?

By now, almost everyone knows that the automotive industry is still short of semiconductor chips, although the situation seems to be improving. While it’s pretty much a given that electric vehicles use more semiconductors, why do gasoline-powered internal combustion engine (ICE) vehicles use so many chips? And do these chips have any attributes that make it harder to increase crafting capacity when they’re scarce? This is what this article will attempt to explain.

Why are so many semiconductor chips used in cars?

The New York Times
NYT
said a modern vehicle can use up to 3,000 semiconductor chips, while another source said over 1,000. I’m sure it depends on what you count, but as recently as in the 1960s, electronics in vehicles were pretty much limited to the car radio. How did a product that was almost entirely mechanical not so long ago end up with so many chips? The answer has several components and reflects the general increase in the use of chips in a wide range of consumer and industrial products: performance, cost and the migration of functionality from hardware to software.

For automobiles, the huge push to improve fuel economy after the 1973 oil crisis led to the rapid increase in the use of electronics in engine controls. While electronic ignitions had begun to appear in the late 1960s, the use of microcontroller chips for engine controls demonstrated what was possible with a digital approach. By using sensors to monitor things like temperature, crankshaft position, mass airflow, throttle position, and exhaust oxygen concentration, automakers have been able to improve significantly improve the fuel economy and emissions profiles of their vehicles. Controller chips performed on-the-fly calculations to optimize engine performance that were impossible to do with sensors and mechanical linkages.

This highlights one of the main drivers for the growth in the use of semiconductor chips: the implementation of many functions using software that might have been difficult (if not impossible) to achieve with material alone. Calculating the optimum flow rate to feed the fuel injectors can involve solving complex equations in real time or looking up numbers in tables. This is easily (and cheaply) done with computer chips and some software. This is also how we achieved more sophisticated automatic transmissions, using software to implement sophisticated control schemes like downshifting. A controller chip attached to the speed sensors sends signals to solid-state power switches that control the transmission solenoids. This highlights the role of power semiconductors, devices that switch power under digital control, which are widely used in a vehicle. If you also count these devices as “chips” (as the New York Times probably did), the number of solid-state devices in a vehicle increases dramatically.

Automotive-grade semiconductor chips and the associated switches and devices they control are more reliable than their mechanical counterparts. I remember when I was much younger, a friend showed me the sequential turn signals in the trunk of their 1968 Mercury Cougar. The red turn signals were apparently connected to a small motorized rotary switch that “looked like a washing machine “. Once the contacts were worn or corroded, this thing was a mess. The use of solid-state switches and a simple timer circuit made these mechanisms much more reliable.

Another example – several years ago I rented a Volkswagen Beetle, and when I jumped in the car and closed the door, the driver’s side window rolled down a bit just as the door was about to close, then it came back up. This evened out the pressure inside the cabin, so your ears wouldn’t pop. This kind of functionality would have been really hard to do purely mechanically, but with a microchip it was probably only a few lines of code. A vehicle’s body electronics – power windows, door locks, exterior mirrors are usually connected to a body control module (BCM) chip. The BCM also communicates with other electronic units throughout the car – things like the instrument cluster and many sensors. And of course, infotainment systems use a lot of chips.

One more thing about implementing things in software rather than hardware: you can modify the product after you ship it. We see this all the time in our computer and phone software – it seems like every ten Zoom meetings I get a new software update. But the material? Tesla showed the power of “over-the-air updates,” which change car functionality. I remember GE Aviation also did a software patch to temporarily fix a high altitude icing issue on their GEnx turbofans used on Boeing
BA
787 and 747-8. With software? Wow, that was impressive!

What’s unique about automotive chip design and manufacturing?

Automotive chips have several remarkable characteristics. The first is that they have to operate for a long time over wide temperature extremes while being subjected to a lot of shock and vibration. Automakers expect a 15-year lifespan and tolerate a zero part-per-billion failure rate during that time. They also want spare parts to be available for 30 years. Most consumer electronics (like your phone) have failure rates measured in parts per million and would be considered obsolete after five years. If your PC encounters an error, restart and relaunch it. If your motor controller suddenly fails you don’t pull over to the side of the road and start again (although I’ve heard of something like this happening with a vehicle’s infotainment system electric). The Automotive Electronics Council (established by the Detroit Big Three) maintains a range of qualification standards for chips. For operating temperature, it defines the operating ranges of grades 0, 1, 2 and 3, with grade 1 covering -40 ºC to +125 ºC and grade 2 covering -40 ºC to +105 ºC. By the way, this has an upper limit above the temperature of boiling water. This is a considerably tougher range than most consumer chips will ever see. Chips need to be reliable, so they need to be designed and tested to last long enough under extreme conditions.

The second requirement is that they must be designed with security in mind. Much of this is covered by ISO 26262 – Functional Safety Standards, which covers a range of things from how they are designed to how failures are handled.

Finally, chip manufacturing processes in semiconductor fabs must be “qualified,” which typically takes six months. Plants also need to make changes to their process design kits for high-temperature device designs, thicker interconnects, and other items that improve reliability. After that, the chips must be thoroughly tested before they can be incorporated into vehicles. This means accelerated life testing at high temperatures and harsh conditions to simulate many years of service. Mainstream automakers have taken up to 3-5 years to design, test and validate new chips.

I pointed out earlier that many automotive microcontrollers use 90nm technology and adding capacity has been difficult. Shortages over the past two years have prompted some automotive chip vendors to migrate to 65/55nm nodes, and some have even moved to 40nm. But DigiTimes says it will take up to five years for new chips built with 40nm processes to clear validation processes and be installed in new vehicles, meaning existing technology will be used for some time. Again. And that’s why the shortage of autochips speaks longer than most to subside.

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