Wednesday, December 29, 2010
【 Weak current College 】 electrostatic discharge (ESD) control of the five principles 】
Although the technical, technological and material in this period evolve, effective electrostatic discharge (ESD, electrostatic discharge) control program design and implementation is still based on the following four concepts:
· The electrostatic protection design within the components and products
· Eliminate anti-static materials and processes
· To disperse or and electrostatic discharge
· Provide on the physical protection of electrostatic discharge
Nevertheless, we often encounter problems, we should consider adding a fifth concept: to test your process and the environment. Our first concept is that design your components, products, and the Assembly, make it more reasonable to avoid electrostatic discharge (ESD). If possible, the use of electrostatic sensitive components, or on your use of the electrostatic discharge-sensitive (ESDS, ESD-sensitive) components provide the appropriate input protection. There is conflicting, advanced production technology means more compact and more complex geometry, usually more sensitive to ESD. However, in the product design to establish more ESD control, then the problem will occur.
Obviously, the product design is not a complete answer. You can avoid ESD components and products, but you can reduce or eliminate the generation and electrostatic discharge. First of all we must work environment as much as possible to reduce or eliminate many static processes or materials, such as ordinary plastic. Because ESD will not occur in the same electric potential or zero potential of material, so the work environment of processes or materials should be kept in the same static potential. Typically, these conductive or disperse materials should electrical connections to the same public places, such as electrical ground. In addition, to provide ground wire to the electrostatic hand ring belt, floor or table surface, safely reduce discharge and accumulation.
Because all generate static electricity cannot be completelyeliminated, so our third principle is that safely dispersed or those to happen in and electrostatic discharge. Proper grounding and electrical conductivity or disperse materials play a major role. For example, static electricity into the working environment for workers through static electricity hand ring or wear ESD control work shoes ESD floor mat stepping to eliminate them. Electrostatic discharge to the ground, rather than on the sensitive element discharge.
For some objects, such as ordinary plastic and other insulator, grounding cannot eliminate anti-static discharge. Typically, use of ions and the insulation on PD. Ion process produces the anionic, attracted to discharge a surface, thus effectively and electrostatic discharge.
The fourth principle is to prevent the occurrence of electrostatic discharge contacts to sensitive components and Assembly. One approach is to assemble the components and provide proper grounding or streaming, making any discharge of separated from the product. The second method is that in the appropriate packaging materials, packaging and transport of sensitive components. These materials can be effectively shielding products, reduce static electricity off in any of the products move from static electricity.
Finally, don't ask whether a process can produce ESD hazard, then guess the answer, you can test it. For example, using the field strength meter (fieldmeter) detect if possible harms of ESD electrostatic field exists. Measurement is the most secure method. You confirm and quantify those genuinely in need of electrostatic protection area, allowing you to concentrate on those areas of most concern. In addition, you can verify that those will not produce the harm of ESD, save you the cost of unnecessary protection.
These five principles become effective electrostatic control program. They help in the selection of appropriate materials and procedures for effective control of ESD. In most cases, effective program will involve all these concepts. In the development of control procedures, confirm that the sensitive element, sensitive level, and who has ESD hazard. And then see which concepts will protect these components. Finally, the selection and implementation can complete the tasks of the program and materials.