Discussion on testing challenges of automotive electronics

As a test engineer, we have to deal with complex tests before the assembly of the Electronic Control Unit (ECU). In this essay, I will try to make you more aware of the various applications and testing strategies. I hope to help you sort out the ideas so that you can ask system integrators and/or ATE suppliers more accurately and help you make the right choice.

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product development

Of course, all newly designed products are validated and tested before they are released. HILs (Hardware In the Loop) are increasingly important in laboratory testing strategies. In general, this is mainly used to test the response of the ECU in the event of an external fault, including: loss of signal, short circuit to ground or Vbat, or erroneous data. In the ATE industry, the fault insertion switching system is usually selected to implement this test. Several companies offer the hardware devices that I have mentioned above for fault generation/injection. Because the safety of ECUs in automobiles is critical, such high-level tests are equally important.

Process test

In the process of assembly and quality testing, the automotive industry appears to be somewhat conservative in the introduction of new technologies. According to INEMI's report, the automotive industry lags behind other industries in introducing small-size packages of PCBs. The main influencing factor is the use environment - temperature range -40 ~ +250 degrees Celsius (exhaust gas sensor operating temperature up to 580 degrees Celsius), multi-G vibration requires structural design standards far higher than the general industry, such as home computers. The original device density is also much lower than other consumer products. In addition, in the future, most of the clocks on the car will not exceed 150MHz, and the test points are still mechanically and electrically accessible. This information indicates that ICT testing (In-circuit testing) will still occupy an important position on the assembly line in the next few years.

For the sake of quality and reliability, AXI (Automatic X-Ray Inspection) is also highly valued as part of the testing strategy. Because the BGA package has a large number of device pins, it is important to verify that all pins are soldered firmly, especially for those safety-related ECUs such as ABS anti-lock systems, airbag controllers, active safety systems and lines. Transmission control (X by Wire) and so on. Because the car's steering and braking (coming soon) are fully electronically controlled, these tests will be critical in the near future.

Because optical inspection does not see the underlying portion of the BGA chip, and in fact not all I/O have terminals, AXI is increasingly important in testing strategies. Despite the economic downturn in 2008 and 2009, the number of newly purchased cars in the world is still as high as 50 million.

Current AXI systems have very low detection speeds (3D X-ray inspection is about 0.6 square inches per second and 2D X-ray inspection is about 6 square inches per second). If the detection speed is increased, the ATE manufacturer will also increase the analysis speed of the equipment accordingly, and the resulting cost increase is also an important consideration in the cost-sensitive automotive industry. In many cases, it is possible to perform partial X-ray inspection of the ECU and AOI or ICT detection for other parts to ensure the efficiency of the production line.

Various types of needs

The complexity of EOL determines the difficulty of testing, because the task here is to simulate the real working environment, so completing these complex tests requires a well-planned plan. There are some requirements for ECUs to consider in functional test systems. include:

Power requirements: The electronic control unit determines when to drive electromechanical devices such as motors and coils. According to the current 12V standard for automotive power buses, this means that large currents can occur – up to 100A for electric power steering! Variable valve actuators on V8 engines require up to 2400W of peak power! Equivalent to a current peak of up to 200A at 12V! So proper switching specifications and cooling capacity are important.

Hybrid cars: Power system cigarettes can be as high as 300V, but most peripherals—such as lights, entertainment, and in-vehicle equipment—run at very low voltages. So there is usually a voltage conversion in this type of design. And because the voltage of 300 VDC is dangerous, isolation tests must be considered in the test plan to ensure safety.

Serial communication: The automotive industry has embraced the concept of networking, or in their own terms, "multiple connections" - in accordance with the connection structure of the various ECUs in the car. Multi-channel technology has been used to display diagnostics, security and performance information, and is now also used for entertainment and navigation. However, the fact that too many protocols are actually used is a problem.

Some organizations such as AUTOSAR (Automotive Open System Architecture) are looking for ways to simplify ECU development and interconnect communication, but it takes time to implement. So now whether you are buying or building a test system, you have to deal with a variety of different protocols.

RF applications: AM/FM broadcasting in automotive ECU testing, RF and microwave testing has been applied more widely. The Bluetooth interface interconnected with mobile phones has been widely used in low-cost cars. IEEE has reported the use of BAP (Bluetooth Access Points) to establish a conceptual design of a micro network. The goal of this design is to avoid conflicts in device identification. Finally, there is interactive cruise control that uses the radar band (40 GHz) to maintain a safe distance.

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