With the acceleration of vehicle electronics, car-grade chips have become an important part of automotive electronic technology. Automotive-grade chips play important roles in driving safety and vehicle control in the automotive field, so their reliability requirements are very high. In order to ensure that automotive-grade chips can withstand the test of various harsh environments, reliability environmental tests must be conducted. Reliability environment testing is to test the chip in a certain harsh environment to ensure its working ability and long-term stability in this environment. The simulated environment test chamber(reliability environmental test chamber)is one of the important equipment for reliability environmental testing. The test chamber can simulate various harsh environments during vehicle driving, such as high temperature, low temperature, high humidity, low humidity, vibration and other conditions, and test the reliability of car-grade chips through strict testing methods. Through reliability environmental testing, vehicle-grade chips can be comprehensively tested and evaluated to ensure their reliability and stability.
Automotive electronic products are generally more expensive. One of the main reasons is the use of automotive-grade electronic components. But what kind of electronic components are automotive-grade devices? Let's first take a look at the differences between the application of electronic components in automobiles and the application of general consumer electronics.
Environmental requirements
Temperature: Automotive electronics has relatively wide requirements for the working temperature of components. There are different requirements according to different installation locations, but they are generally higher than the requirements for civilian products (it is said that AEC Q100 has deleted the 0℃-70℃ in the H version. Temperature requirements, because no automotive product can have such low requirements).
Example:
Around the engine: -40℃-150℃;
Passenger cabin: -40℃-85℃;
Civilian products: 0℃-70℃.
Other environmental requirements: humidity, mold, dust, water, EMC and harmful gas erosion, etc. are often higher than the requirements of consumer electronics products.
vibration, shock
When a car works in a moving environment, many products will encounter more vibration and impact. This requirement may be much higher than that of products placed at home.
reliability
In order to illustrate the reliability requirements of cars, let me explain it in another way:
1. Design life: The design life of general automobiles is about 15 years and 200,000 kilometers, which is much longer than the life requirements of consumer electronics products.
2. Under the same reliability requirements, the more components and links the system consists of, the higher the reliability requirements for the components. At present, the degree of electronics in cars is very high. From the powertrain to the braking system, a large number of electronic devices are installed, and each device is composed of many electronic components. If we simply regard them as a series relationship, then to ensure that the entire vehicle reaches considerable reliability, the requirements for each part of the system are very high. This is why the requirements for automotive parts are often expressed in terms of PPM (millions). one part) to describe.
Consistency requirements
Nowadays, cars have entered a stage of mass production. Hundreds of thousands of a car can be produced in a year, so the requirements for product quality consistency are very high. This was quite challenging for semiconductor materials in the early years.
After all, the consistency of diffusion and other processes in the production of semiconductors is difficult to control. The performance of the produced products is easy to be discrete. In the early days, it could only be accomplished by aging and screening. Now, with the continuous improvement of processes, the consistency has been greatly improved. Consistency of quality is also the biggest difference between many local suppliers and internationally renowned suppliers. For complex automotive products, it is absolutely unacceptable for components with poor consistency to cause safety hazards in the entire vehicle.
Let's look at some other requirements:
Manufacturing process
Although automobile parts are constantly developing toward miniaturization and lightweight, compared with consumer products, the requirements for manufacturing processes of automobile products can be relaxed in terms of volume and power consumption. Generally, larger packages are used to ensure that Have sufficient mechanical strength and comply with the manufacturing processes of major automotive suppliers.
Product Lifecycle
Although the prices of automobile products have been continuously reduced in recent years, automobiles are still a durable and large-ticket commodity, and the supply of after-sales parts must be maintained for a long time. At the same time, developing an automobile part requires a lot of verification work, and the verification work caused by replacing components is also huge. Therefore, vehicle manufacturing companies and parts suppliers also need to maintain stable supply for a long time.
standard
From this point of view, it is indeed complicated to meet the requirements of automotive products, and the above requirements are for automotive parts (for electronic components, it is a system). How to convert the requirements into electronic components becomes very difficult. To solve this problem, Naturally, some standards have emerged, and the more recognized ones are the AEC standards:
AEC Q100 Requirements for Active Device Components
AEC Q200 requirements for passive (Possive Device) components
Of course, I guess many people will also say that there are many corporate standards for OEMs. But I also want to share my understanding on this point. The OEM I worked for before does have relevant general reliability requirements standards, but it assesses a complete automotive component (a system composed of electronic components), rather than directly targeting the electronic components that make up these components. (resistors, capacitors, transistors, chips, etc.). Although its requirements can be used as a reference for the selection of lower-level components, it is still very inappropriate for electronic component testing.
Verification of vehicle regulations
In my previous job, it was inevitable that I would use some electronic components that did not have AEC Q100/200 certification. Many car factory personnel would like to conduct some reliability verification to verify whether it meets the vehicle regulations.
My personal opinion is that this method is not very effective, because these tests are only necessary but not sufficient tests. It can only be used to deny the availability of the device, not to confirm that it can be used.
The reason is simple: the sample size is too small and the items tested are not sufficient. For components manufactured in large quantities such as semiconductors, it is very unreliable to test a small number of samples to determine their reliability. Here we can also take a look at the main certification test items conducted by AEC Q100, that is You can see the difference.
Which standard is more demanding?
Car regulations or industrial regulations, which one has higher requirements? It is generally believed that the standard order of high and low is military industry > automobile > industry > consumer electronics. But personally I cannot fully accept this order. Industry is a very broad area, and the environments and reliability requirements encountered are also very different. It is conceivable that the reliability requirements of a large industrial equipment will never be lower than those of a car. (For example, key equipment of a large power plant), and at the same time, the harshness of the environment may far exceed the requirements of automobiles. It cannot simply be said that the industrial regulatory requirements are lower than those of automobiles.
Disadvantages of using car-spec parts
No choice can have only advantages and no disadvantages. What are the disadvantages of using car-standard electronic components?
First of all, it is expensive, with high system requirements, high development and verification costs, and low output, which makes the cost much higher than that of consumer electronics. The relatively high threshold also results in a larger sales premium.
The second disadvantage is that selection is difficult. Anyone who plays electronics knows that today, electronic components are quite abundant. There are many solutions for products with the same function, and the complexity may vary greatly. However, sometimes in order to meet the requirements of car regulations, some highly integrated products have to be given up. plan.
Another obvious disadvantage is that some products are technologically backward, and a large amount of verification work affects the speed of new products to market. At the same time, the general launch strategy of chip manufacturers is to wait until the consumer electronics market matures before applying the product to the market. to the car market. For example, in 2013, a product developed by the editor used the ARM Cortex A9 processor. At that time, it was basically the best product in the automotive market, but the ARM Cortex A57 processor was not uncommon in the consumer market.
What are the risks of using non-vehicle-standard electronic components in the car?
This issue is really complex and needs to be judged from many aspects:
1. Although it has not obtained relevant certification, the performance and reliability of the product actually meet the requirements, and it has also been verified by a large number of applications. If this is the case the risk is relatively small.
2. This is a very important point, which is the relationship between components and systems. The performance and reliability of the system are composed of next-level electronic components, so under the same design, products using non-vehicle-standard components will definitely be worse. However, good design can reduce the performance requirements of components. If the protection measures are well designed and the component failure has a slight impact on the system, it is possible to use non-car-standard components to make better products.
Due to the limitations of current technology and processes, not every electronic component that needs to be used in cars can meet the so-called vehicle regulations. But in order to realize certain functions on the car, these components must be used. This situation can be divided into two categories:
a. This function has high safety requirements and deviations cannot be accepted.
Example: E-CALL function for emergency calls. To ensure this function, a backup battery needs to be installed on the device. This function is related to life safety, and according to some companies' ASILI (ISO26262) rating, it is required to reach level B.
And we know that it is very difficult for batteries to maintain high performance at -40 degrees. Therefore, some companies' solution is to wrap a heating resistance wire on the battery and heat it at low temperatures to ensure performance. At this time, it is not qualified by the standards of a single component, but as a parts assembly, it can meet the standard requirements of the car manufacturer. . This also shows the relationship between the OEM's corporate standards and component standards.
b. This function generally does not involve safety, so you can consider accepting deviations
Such as the LCD screen of the entertainment system. Possible display of reduced response and optical performance at low temperatures. But this situation will be accepted by some engineering staff.
3. Some "bold" and careless people have certain ideas, such as reducing costs or obtaining better performance, and only want to verify their performance and accuracy through a small number of samples in a short period of time. Reliability, in this case I can only say that everything in the future will depend on character, no one knows what will happen.