Electrostatic electricity can be a significant cause of problems in a cleanroom if you are not thinking through how your cleanroom is set up and used. This problem is a sudden discharge of electricity between two metal objects that if not controlled can cause damage to components of products or components of electronic tools you may be using.
The most common type of Electrostatic discharge comes from static electricity. This can be a build up on the cleanroom garment of an employee that ends up discharging when they touch an electronic tool or hold a metal object close to components of a product. These discharges can be in the thousands of volts of electricity (depending upon your relative humidity). It only takes a small charge of 30+ volts to destroy some electronic components.
Another type of Electrostatic discharge can be from a build up of electrical energy in a non grounded object. Sometimes electronic devices or metal items that deal with friction or electricity can build up an extra charge that can discharge when in close proximity to another metal or electronic item.
The key to this problem is to control and manage the movement of this charge. When will it build up? How do we limit it? How do we discharge it in a safe manner?
There are a few ways to handle Electrostatic Discharge inside your cleanroom:
Anti-static: This method consists of using special clothing, curtains, gloves, towelettes, etc. that are used to eliminate or control the static electricity. These are not resistive to static electricity but help to prevent the build up of the charge.
Conductive: The purpose of these items is to allow the flow of Electrostatic charge in a safe manner to prevent damage to sensitive items. Conductive materials can be shoe covers, chairs, gloves and even some types of tape.
Dissipative: This type of material or times has the purpose of collecting any Electrostatic charge and conducting it out in a safe manner to prevent the damage to sensitive materials. Sometimes this can be an object that e employees are supposed to touch before they start work or before they enter the cleanroom. Ionizers for the cleanroom air circulation can also be used to help in dissipating Electrostatic charge on surfaces. Floors and walls in Cleanrooms sometimes can be built to limit the creation of static charge as well as help dissipate it away in a safe manner.
Humidity: Maintaining proper humidity levels can reduce the electrostatic discharge in the cleanroom, depending upon design, geographic area and process specifications your indoor relative humidity could vary. A properly designed cleanroom will take these factors in to consideration to help you maintain control.
Making sure your Cleanroom is designed properly from the beginning is very important to making sure you do not end up with a problem later.