Are you familiar with the testing functions of various human-to-ground testers?
In daily electronics production, I often hear reports of high static voltage levels among employees. I'm unsure of the cause. How can I eliminate static electricity from the human body? ANSI/ESD S20.20 stipulates that when people wear anti-static shoes while walking on the floor, the resistance of the stem and floor system should be less than 1-109Ω, and the charged voltage should be less than 100V peak. Personnel handling SSDs must use an anti-static wrist strap. When using a wrist strap, the theoretical contact between the wrist strap and the user's wrist, as well as the grounding wire, should be good, with a wire resistance of 0.8*106Ω; when worn, the grounding resistance should be less than 3.5*107Ω. When using a wrist strap, ensure a secure ground connection and low contact resistance. The diameter of the wrist strap's grounding metal core should be greater than 1.5 mm², and the elastic band must contain conductive wire.
Proper human static protection requires rigorous technical inspection. Currently, the most common method used by customers is to install a comprehensive human static detector at the workshop entrance with an access control system. Only when ESD protection meets standards will the guardrail open the door for employees to enter the workshop. How do I choose a human grounding tester suitable for workshop use?
Human Grounding Tester Functional Introduction
I. What is the Function of a Human Grounding Tester?
Human grounding testers on the market have many names, such as human grounding testers or wristband/anti-static shoe testers, but they actually refer to the same instrument. This type of instrument is installed at the entrance to the ESD protection area (workshop entrance) to check whether the resistance of employees wearing anti-static wristbands and work shoes is within the qualified range. Only qualified employees can enter the ESD protection area (EPA).
II. What is the difference between a human grounding tester and a real-time grounding monitor?
Human grounding testers are primarily installed at each doorway to restrict access to qualified employees. They are often used in conjunction with access control. Real-time grounding monitors are installed at fixed workstations to monitor the grounding status of people, desks, and equipment in real time.
Mobile personnel cannot use real-time grounding monitors, and mobile personnel are grounded through anti-static shoes, so they can only be detected by human grounding testers.
III. What is the difference between a human grounding tester and a wristband tester?
A wrist strap tester measures the resistance of the wrist strap itself, while a human body grounding tester measures the resistance of the human body to the ground through the wrist strap. Therefore, a human body grounding tester measures the resistance of the wrist strap (the combined resistance of the human body and the wrist strap).
Four: What are the precautions for using a human body grounding tester?
Please note the following to avoid damage to the instrument and confusion:
1) The tester itself must be reliably grounded: Static electricity generated by the human body can enter the instrument's internal circuit boards through the fingers. If the tester is not grounded or the grounding is inadequate, the internal chips may be damaged.
2) Keep the test button dry and free of contaminants, otherwise there is a risk of short circuiting.
3) The resistance of anti-static shoes may vary depending on weather temperature/humidity or pollution levels, sometimes passing and sometimes failing. This is not a problem with the tester, but rather the resistance of the anti-static shoes themselves.
Five: How to calibrate a human body grounding tester?
Once the tester is installed, it is difficult to remove it, so sending it to a third party for calibration is not very convenient. It is recommended to purchase an original standard resistance box and calibrate it to see if it meets the requirements before using a qualified standard resistance box.
The human body grounding tester can be calibrated at the actual location, which is a simple and effective method.