How to Choose Anti-Static Shoes?
Research on anti-static shoes has shown that the level of static charge generated by a worker's body depends on the materials of both the anti-static shoes and the flooring. Therefore, systematically measuring ESD in real-world environments, from the anti-static shoes worn by workers to the anti-static flooring, provides highly meaningful and practical data.
Currently, a common problem in the anti-static shoe industry is that anti-static shoes cannot consistently meet the 100V HBM reference voltage. This is because most anti-static shoes in the electronics industry use unstable additives, resulting in electrical properties that degrade over time, leading to inconsistent performance.
To overcome this issue and reduce the voltage on the human body, one approach is to improve the electrical properties of the shoes, making them more conductive. However, this must be limited to a certain resistance range to meet safety regulations of relevant agencies.
It is also important to remember that the resistance from the human body to the ground should not be less than 1*10e5 ohms, as stated in the S20.20TR manual, to protect the body from any harm and avoid potential electrical safety risks.
Some ESD practitioners misunderstand that as long as the resistance from the body to the ground is less than 3.5*10e5 ohms, the body voltage will not exceed 100V HBM in an ESD-controlled workplace. If these misconceptions are not corrected, they create a high-risk environment when handling and protecting highly ESD-sensitive equipment found in many microchip manufacturing industries.
It is important for users of ESD shoes to understand that it is the body voltage, not the body-to-ground resistance, that can damage microchips.
Therefore, ideally, a shoe or footwear system would not only keep the body voltage below 100V HBM but also achieve an appropriate body-to-ground resistance that meets safety requirements.
However, most users are unaware of a simple solution that can achieve a body voltage below 100V HBM in all standing production environments without the use of a wrist strap.
A simple and feasible typical solution on the market is to use anti-static shoelaces. Anti-static shoes consist of a U-shaped bracket, the tail of which can be arbitrarily fixed on the surface of the insole inside the shoe. There is an elastic rubber band wrapped around the upper and sole of the shoe. The shoes can be standard ESD or non-standard ESD.