Compare electrostatic discharge standards for automotive electronic components

Electrostatic discharge standards

According to different countries or regions, the certification standards for automotive electronic components may vary, including national standards, international standards, or automotive enterprise standards. In order to better meet the requirements of automotive component products in various regions, we will compare and analyze different electrostatic discharge standards.

Electrostatic discharge standards mainly consist of international standards, IEC61000-4-2, ISO 10605, and various automotive enterprise standards.

Table 1 Electrostatic Discharge Test Standards

Note: From the table, it can be seen that international standards have always been followed by enterprises or laboratories, and have been modified based on them. Volkswagen and Chrysler have referred to ISO10605 and IEC61000-4-2 standards.

Principles of Electrostatic Discharge

Static electricity cannot be transferred between two objects due to friction. These accumulated charges generate static electricity. Electrostatic discharge can interfere with electronic components through conduction and radiation. PCB interference affects system operation. Electrostatic discharge is basically divided into two models. Electrostatic electricity caused by electrification of various electronic equipment; 2. Static electricity caused by human body charges. Basic standards for automotive components, product standards, and automotive enterprise standards are mainly based on human body models to simulate electrostatic discharge. The following diagram is a schematic diagram of a human body model, where the resistance represents the resistance of the human body and the capacitance C represents the capacitance of the human body.

Test method and test layout

Test environment requirements

Table 2 Environmental Requirements

Note: According to the electrostatic discharge principle, static electricity has a great relationship with the environment. Generally, the lower the temperature and humidity, the easier it is to generate static electricity. From the table above, it can be seen that various automotive companies are close to product standards and stricter than basic standards. Chrysler and BMW standards do not have clear temperature and humidity requirements, but according to the principle of standard traceability, it is necessary to trace back to the superior, subject to the requirements of ISO10605.

2. Requirements for output characteristics of electrostatic generators

The ISO 10605:2008 standard specifies the contact discharge current waveform, giving the upper and lower edges of the calibration waveform and the current peak value, as well as the current values at calibration t1 and t2 (different RC combinations have different t1 and t2), as shown in Table 3.

Table 3 Current characteristics of contact discharge mode

In the figure: X time, ns; Y current, A

1：330pF/330Ω

2: 150pF/330 Ω Figure 1 Discharge Waveforms of 150pF/330 Ω and 330pF/330 Ω at 5kV Voltage

In the figure: X time, ns; Y current, A

1：330pF/2000Ω

2: 150pF/2000 Ω Figure 2 Discharge Waveforms of 150pF/2000 Ω and 330pF/2000 Ω at 5kV Voltage

Table 4 Comparison of discharge network parameters

Note: The 2k Ω resistance test represents a direct discharge through the skin of the human body. The test using a 330 Ω resistor represents the discharge of electricity from the human body through metal components such as tools, keys, and rings. The test using a 330 Ω resistor is more rigorous than the test using a 2K Ω resistor. Under the same resistance, the larger the capacitance, the more rigorous the test.

3. Test method

According to ISO 10605:2008, there are two types of discharge: contact discharge and air discharge. Contact discharge is preferred during testing. For places where the gap and discharge head cannot be contacted, the standard for selecting air discharge for each automotive enterprise is also equivalent to this standard.

According to IEC6100-4-2, discharge includes contact discharge, air discharge, and indirect discharge, as well as automotive companies that reference this standard, such as Volkswagen and Chrysler.

4. Test layout

Combining the ISO 10605:2008 standard and the enterprise standard, its standards include electronic component testing and the sensitivity classification testing of electronic components specified in packaging processing. Some car manufacturers require vehicle electrostatic discharge testing. Here, we mainly analyze and compare electronic components.

4.1. Electronic components (charged state)

According to the standard layout requirements of ISO 10605:2008, the horizontal coupling plate is connected to the ground reference plane through two 470k Ω resistors (shown in Figure 3, 13). The negative electrode of the battery is connected to the horizontal coupling plate, with the measured object placed on the horizontal coupling plate (50 ± 5) mm, and the edge away from the horizontal coupling plate (HCP) is 0.1m.

Figure 3. Configuration for conducting electrostatic discharge tests on live components

Note: In the figure, 1 test equipment 2 electrostatic discharge generator 3 electrostatic discharge generator 4 non-conductive table 5 horizontal coupling plate (HCP) 6 ground point 7 ground wire connection 8 test equipment 9 external equipment 10 battery 11 insulation support (if necessary) 12 insulation block 13470k Ω resistance 14 reference plane (GRP, selection) 15 horizontal coupling plate (HCP) ground.

Note: The standards of automobile manufacturers refer to ISO10605 and IEC61000-4-2 standards, but some manufacturers will make minor adjustments according to their own requirements, such as grounding resistance, because the discharge will also be required to be 1M Ω according to the grounding resistance, Citroen, and Ford standards. Chrysler standards do not require testing the charging mode.

4.2. Electronic components (non charged)

The ISO10605:2008 standard requires that the minimum distance between the electrostatic discharge test surface and other conductive structures (such as the conductive surface of the shielding chamber) be 0.1m. During the discharge test, the object under test is placed on a 50mm insulating pad, and the discharge return cable of the generator should be at least 0.2m away from the equipment under test. High resistance (1m Ω) can eliminate static charge accumulation, as shown in Figure 4.

Figure 4 Configuration for conducting electrostatic discharge tests on components without electrification

Note: In the figure, 1 equipment under test 2 electrostatic discharge generator 3 electrostatic discharge generator 4 non-conductive table 5 horizontal coupling plate (HCP) 6 ground point 7 ground wire connection 8 electrostatic elimination pad.

Note: The standards of automotive manufacturers mainly refer to the test layout of non live parts in ISO 10605, but Volkswagen and Chrysler directly refer to the test layout and test methods in IEC61000-4-2. During the mode discharge process, the sensitivity classification test for electronic components specified for packaging and handling is mainly based on a human model. Therefore, public reference to the IEC61000-4-2 standard is more in line with the on-site situation. From Table 4, it can be seen that the discharge energy of the discharge network 150pf/330 Ω is higher than 150pf/2000 Ω. However, the Chrysler standard also requires field coupling testing.

5. Test level

Contact discharge 2kV~15kV refers to the requirements of Appendix C of ISO10605. Air discharge 2kV~25kV. IEC61000-4-2 requires contact discharge of 2kV~8kV, air discharge of 2kV~15kV, and specifies the opening level. Automotive enterprise standards are tested based on this standard, but the maximum is 25KV.

6. Test criteria

Appendix C of the ISO10605 standard specifies four fault judgment criteria, requiring that the tested object be evaluated after each test level is completed. The automotive enterprise standard will provide corresponding judgment levels based on the test level.