Understanding electrostatic discharge
As winter comes to a close, your jacket may give you an electrostatic shock. You may get one from touching a metallic doorknob after crossing a carpeted room or from shaking someone’s hand. Although static electricity is ever present people rarely notice it.
What causes electrostatic discharge?
Why is everyone shocked at some point? ESDs (electrostatic discharges) happen because of a buildup in static charge caused by friction. When certain surfaces move against each other, electrons rub off one surface and accumulate on the other, causing a difference in potential electrostatic energy to build up between the two.
The accumulated voltage may reach a point where it is powerful enough to jump very quickly to another surface holding a different level of static charge. This jump or discharge causes the feeling of pain when your skin is one of the surfaces.
These electric shocks can be very unpleasant but are usually harmless. But if this happens to electronic components or devices, harm can occur.
As smaller electronic devices such as NEMS (nano electromechanical systems) and MEMS (micro electromechanical systems) take off, it becomes increasingly important to understand and control electrostatic phenomena. Because of their size, these tiny electronic components can become permanently damaged even by very low electrostatic discharges.
Electrostatic discharge, new and old
Static electricity has been a serious industrial problem for centuries. As early as the 1400s, European and Caribbean forts were using static control procedures and devices to prevent electrostatic discharge ignition of black powder stores. By the 1860s, paper mills in the USA (United States of America) employed basic grounding, flame ionization techniques, and steam drums to dissipate static electricity from the paper web as it went through the drying process.
Today, as devices have become faster and smaller, their sensitivity to ESD has increased. Because electrical and electronic products contain many components, manufacturers want to be assured that the electronic components used in their products are of the required quality.
Protection from ESD by IEC...
This is why it is essential for industry to put in place protection programmes against ESD. IEC is the world reference for ESD standards. This is where the IEC, through its standardization and CA (Conformity Assessment) activities, plays a major role. IEC 61340-5-1, Electrostatics – Protection of electronic devices from electrostatic phenomena – General requirements, is the most recent International Standard on developing ESD control programmes.
IECQ, the IEC Quality Assessment System for Electronic Components, offers assessment and Process Approval Certification as a means of providing independent verification of compliance to IEC 61340-5-1 for facilities handling unprotected ESD sensitive devices.
As semiconductor devices continue to become more sensitive to ESDs it is important that companies handling these devices develop, implement and maintain effective ESD control programmes in their facilities.
The IECQ ESD Approved Process Certification Scheme is also designed to work with a company’s existing quality management system. Companies with electrostatic discharge requirements may instill confidence; however, experience has shown that an approach on the management and control of ESD is necessary.
IECQ is a worldwide approval and certification system that covers the supply, assembly, associated materials and processes of a large variety of electronic components that are used in millions of devices and systems.
IECQ operates five certification schemes: HSPM (Hazardous Substances Process Management), ECMP (Electronic Component Management Plan), AP (Approved Process), AC (Approved Component), and ITL (Independent Testing Laboratory).
The IECQ Certification System provides manufacturers with independent verification that IEC International Standards and other specifications were met by suppliers who hold certification.