Company Name: Hangzhou Qiaohui Color Steel Co., Ltd. <br> Contact: Mr. Du <br> Contact: 15068169318
Address: No. 18 Dongjiamen, Sandun Town, Xihu District, Hangzhou
Generation and hazard analysis of static electricity in clean room
Static electricity is the product of electrons moving (including polarization and conduction) inside or between materials. Two different materials are in contact with each other, and the distance between them is less than a certain distance, such as 10-25 cm. At this time, due to the tunneling effect, the electrons in the two materials pass through the interface and exchange with each other. When the exchange reaches equilibrium, a potential difference occurs between the materials, and equal amounts of positive and negative charges appear on both sides of the interface. If you connect the two substances that are separated after being separated, the two substances will carry equal amounts of positive and negative charges, respectively. This is the basic principle of generating static electricity.
There are three main methods of generating static electricity: frictional charging, conductive charging and induction charging.
Friction charging: Because objects of different materials will separate after contact, and due to the different ability of atomic nuclei to confine electrons, when two different materials are in contact or friction, the peripheral electrons will rotate to move to the side with greater restraint capacity, making a material belt Positively charged, another material is negatively charged.
Conductive charging: Because a conductor can move electrons freely on its surface. When in contact with a charged body, the electrons will be transferred from the charge, which will lead to a charge balance between the two, thereby forming an electrostatic phenomenon.
Inductive charging: refers to the induction of adjacent electric fields. For conductors, electrons move freely on the surface of a conductive material. If a conductor is placed in another electrostatic field, the same charges repel each other. The opposite charges attract each other and positive and negative ions will be transferred. The imbalance of positive and negative charges caused by electrostatic field induction causes the conductor to be charged.
From the basic principles and methods of generating static electricity, it can be seen that in the entire manufacturing process of general electronic products, many processes may generate static electricity. Electronics Manufacturing I
Static electricity is generated by people, work surfaces, components, and packaging. As long as there is static electricity, there will be an ESD (electrostatic discharge) process, which mainly occurs during the discharge process.
The noise caused by the induced and discharged current flowing to the circuit will cause the reference ground potential such as product ground and signal ground potential to move and fluctuate, thereby causing interference to the normal operation of the circuit.
Dust-free workshop engineering: the generation and hazard of static electricity in clean rooms. Static electricity hazards are different from lightning protection or electromagnetic interference:
The human body is unaware of electrostatic discharge, but components are damaged unknowingly.
Potential and cumulative:-After some components have been damaged by electrostatic discharge, only some performance parameters have been reduced, but they have not yet failed. It may cause failure under continuous use, so static electricity may damage equipment.
Randomness: At any stage, step or location of contact with a charged human body (or object) during processing, manufacturing, use or maintenance, it may cause electrostatic discharge damage to electronic components. It has strong randomness.
Complexity: Some electrostatic damages are also difficult to distinguish from damage caused by other causes, leading people to mistake electrostatic damages for other faults and make wrong judgments.
ESD protection is a comprehensive system project. In principle, ESD protection should be carried out from two aspects: controlling the generation of static electricity and controlling the dissipation of static electricity.
The selection of materials in the process flow and the control of static dissipation are mainly to safely discharge and neutralize static electricity.