Detail of GB/T 37977.46-2024

Introduction of GB/T 37977.46-2024

GB/T 37977.46-2024 Electrostatics - Part 4-6: Standard test methods for specific applications - Wrist straps 1 Scope This document serves as the standard test method section for specific applications in the GB/T 37977 series, providing electrical and mechanical test methods and performance limit for evaluation, acceptance and periodic verification testing of wrist straps. Note: All dimensions are nominal except where indicated. This document is intended for testing wrist straps and wrist strap systems used for the grounding of personnel engaged in working with ESD sensitive assemblies and devices. It does not address constant monitoring systems. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3 Terms and definitions 3.1 wrist strap assembled device consisting of a band and ground cord that is designed to provide electrical connection from a person’s skin to ground 3.2 wrist strap system wrist strap when properly worn by a person, where the electrical path includes the person, the band and the ground cord 3.3 band portion of the wrist strap worn on the wrist Note: The band maintains electrical contact with a person’s skin. 3.4 ground cord portion of the wrist strap that provides flexibility of movement while completing the electrical circuit between the band and ground 3.5 evaluation testing testing of a wrist strap to determine its electrical and mechanical performance abilities Note: Data are in the form of values from laboratory testing. 3.6 acceptance testing incoming tests to confirm proper marking and electrical functionality Note: Data are in the form of visual inspection records and values or pass/fail notation. 3.7 periodic verification testing end-use testing to confirm electrical functionality Note: Data are in the form of pass/fail notation or resistance values. 3.8 current-limiting resistance resistance value incorporated in series with the wrist strap’s electrical path to ground Note: This resistance limits electrical current that could pass through the ground cord in the event of inadvertent user contact with an electrical potential. 3.9 resistance range user-specified upper and lower resistance values which define the user-acceptable resistance values of a wrist strap or wrist strap system 3.10 strain relief construction feature designed to protect the connections and cord from premature failure 3.11 breakaway force force required to disconnect the ground cord from the band 4 Testing levels and performance limits This standard specifies different types of testing for wrist straps. Tables 1, 2 and 3 detail the three types of testing with the associated limits and subclause references to test methods. The methods provide appropriate tests for the different levels of wrist strap examination. Evaluation tests are laboratory tests for measuring the performance of a wrist strap or for the comparison of wrist straps. Acceptance tests provide methods for incoming goods inspection. Finally, the periodic verification or functional test is a simple check of electrical continuity. This test shall be used on a regular, user defined basis, to ensure that the wrist strap is electrically functional. Testing shall be carried out under ambient laboratory conditions. The temperature and humidity at the time of testing shall be recorded and reported in the test report. In the case of any dispute regarding test values, conditioning and testing shall be done at (23 ± 2) °C and (1 2 ± 3) % RH. Note: Testing has shown that environmental conditions do not significantly affect test results.

Contents of GB/T 37977.46-2024