During the SMT processing process, electrostatic discharge can cause damage or failure to electronic components. With the increase in IC integration and the gradual shrinkage of components, the impact of static electricity has become more serious.
According to statistics, static electricity accounts for 8% to 33% of the factors that lead to the failure of electronic products, and the annual loss of electronic products caused by static electricity reaches billions of dollars.
Il est donc très important de mettre en œuvre des mesures de protection électrostatique dans la production SMT. Cet article explique en détail comment prendre des mesures de protection électrostatique, depuis la production d'électricité statique jusqu'à la protection des composants et des scènes.
How is static electricity generated?
Electrostatic discharge, abbreviated as ESD, is a physical phenomenon that refers to the charge transfer caused by objects with different electrostatic potentials approaching each other or directly contacting each other. During charge transfer, there is a flow of charge, delivering enough electricity to offset the voltage.
Static electricity has a great impact on electronic components and electronic circuit boards. For example, electrostatic breakdown may occur, causing component damage or failure, thereby affecting electronic products.
Common principles of static electricity generation
01 Frictional electrification
When two different materials rub together, one of the materials becomes charged, creating static electricity.
02 Induction electrification
Under the action of the electrostatic field, the object undergoes a redistribution of charge. For example, when a charged object approaches an uncharged object, a potential difference will be formed between the two. This potential difference will cause the charge to move on the uncharged object, thereby generating a static charge on the uncharged object.
03 Capacitive charging
When a charged object that already has a certain charge approaches or separates from another object, the capacitance of the system changes, and the electrostatic potential on the charged object will change, forming static electricity.
Anti-static for electronic components
Electronic components that are sensitive to static electricity generally have anti-static signs. Pay special attention to anti-static issues when encountering components with these signs during the production process.
Semiconductor integrated circuits take protective measures against anti-static failure in design, and can provide electrostatic discharge design protection below 2000V for sensitive components. At the same time, protective resistors and embedded diodes can also be added through circuit peripheral design to make them have more powerful antistatic ability.
Common scenarios of static electricity damage
01 Place components
When components are placed on the chipboard, due to the presence of electrostatic fields, the components may slip or deform from the placement position, causing defects or failures.
02 Electrostatic charge accumulation
Due to the metal shell and grounding device of SMT equipment, electrostatic charges will accumulate. If the electrostatic charges are not released in time, damage to the components will occur.
03 Contamination damage
Static charges can absorb dust, oil and other impurities, causing surface contamination of components or circuit boards, thus affecting their normal operation.
04 adsorption damage
During handling, storage, or assembly, static charges can attach to components or other parts, causing them to malfunction or be damaged.
Basic principles of electrostatic protection
Electrostatic protection principles
1. Use or install static-sensitive components in static-safe areas.
2. Use static-shielding containers to transport and store static-sensitive components or circuit boards.
3. Regularly check whether the installed electrostatic protection system is operating normally.
4. Ensure that suppliers understand and comply with the above three principles.
Static electricity protection steps
1. Avoid placing static-sensitive components and circuit boards together with plastic products or tools.
2. Make sure that the work area floor and table mat have sufficient conductivity. It is best to use conductive rubber table tops or use conductive tape to stick to the four sides of the table.
3. Always check whether the grounding system is in good condition, and the ground cable must be correctly connected to the busbar.
4. When using electronic tools or instruments, make sure that the tools or instruments used meet the requirements for electrostatic protection.
5. Limit the use of packaging materials such as plastic bags and foam boxes. If they must be used, make sure that the packaging materials have undergone conductive treatment or are made of metal materials.
6. Wear anti-static clothing and shoes, use anti-static tools and gloves, and anti-static bracelets.
7. Hire professionals who have been trained in electrostatic protection to ensure that anti-static measures are implemented correctly.
8. Conduct regular electrostatic protection inspections and tests to ensure the effectiveness of anti-static measures.
9. Employees and guests who are not wearing bracelets are prohibited from approaching the electrostatic protection workstation. Once violations are discovered, they should be stopped immediately and reported to superiors.
10. If there are problems or defects in the electrostatic protection system, you should immediately report it to the superior leader or the person in charge of electrostatic protection, and take timely measures to improve and deal with it to ensure the effectiveness of the electrostatic protection system.
FAQ - à propos du PCB
La décharge électrostatique, abrégée en ESD, est un phénomène physique qui fait référence au transfert de charge causé par des objets ayant des potentiels électrostatiques différents qui s'approchent les uns des autres ou qui entrent directement en contact les uns avec les autres. Pendant le transfert de charge, il y a un flux de charge qui fournit suffisamment d'électricité pour compenser la tension.
- Électrification frictionnelle
- Électrification par induction
- Chargement capacitif
- Place components
- Electrostatic charge accumulation
- Contamination damage
- Adsorption damage