Electrostatic hazards and antistatic packaging (below)

3 anti-static packaging principle

Static electricity is a common physical phenomenon. The generation of static electricity is not terrible. It is the accumulation and discharge of static electricity that causes damage to optoelectronic products, ammunition, and pyrotechnics. Knowing this, it is not difficult to prevent static electricity. Simply put, if you can create a condition that does not accumulate static electricity, you can avoid the harm of static electricity.

The generation of static electricity mainly comes from two aspects. One is the friction between objects (especially insulators), and the other is the induction of external electric fields or electromagnetic fields. In general, the higher the object conductivity (the lower the resistivity), the less likely it is to generate and accumulate static electricity. Because of the high conductivity of the object, once the electronic loss due to friction and other external effects, there will soon be other parts of the electron to fill the gap, that is, the transfer of charge, so that the object appears to be electrically neutral. Conversely, if the object has a very low electrical conductivity (high resistivity, such as an insulator), when friction causes some part of the electron to lose electrons, it will not be possible to generate charge transfer in a short period of time, so that part of the object will have a positive charge. The accumulation of (losing electrons), the other part of the accumulation of negative charge (acquisition of electrons). Since charge accumulation occurs only on the surface of an object, the surface conductivity of the object (usually expressed in terms of surface resistivity) becomes an important physical parameter for studying the generation and accumulation of static electricity.

A lot of research and practice shows that from the perspective of packaging, the surface resistivity of the material and the degree of electrostatic protection have the relationship of Figure 1.

In addition to the need to understand the relationship between surface resistivity and degree of protection of the above materials, effective electrostatic protection must also be familiar with the electrostatic susceptibility of the product itself, the flow of the product, and the environment through which the product may be stored.

The static sensitivity of the product itself determines which type of antistatic material is appropriate. For example, for products that are less sensitive to static electricity (insensitive), packaging materials with a surface resistivity of 109 to 2012 Ω are preferred. Because this type of material is not easy to generate static due to friction and vibration, it has anti-static function, low cost, and easy access to materials. General natural paper, cotton and other natural fiber products that have this function. If the product is sensitive to static electrodes, such as field-effect transistors, large-scale integrated electronic components, electric initiators, electric ignition devices, etc., the surface resistivity must be less than 109Ω.

An understanding of the product's distribution environment helps us understand the potential for static electricity. As we all know, the degree of electrostatic accumulation has a great relationship with the relative humidity of the environment. Relative humidity is low (the more dry the air), the easier it is to accumulate static electricity; the higher the relative humidity (air humidity), the less likely the static electricity will accumulate. This is because the water molecules in the air are polar molecules, and the presence of a large number of water molecules can take away part of the charge, especially when the air is in circulation. Knowing the product flow and storage environment can predict the magnitude of the electrostatic hazard. For example, in the winter in the north, dry deserts, between product packaging materials and materials, between products and packaging, in the transport of vibration friction may generate a high electrostatic voltage, posing a serious threat and harm to the product. In this case, special attention must be paid to electrostatic protection.

4 Development of domestic anti-static packaging technology

Foreign industrial countries have fully realized the electrostatic hazards in the 1960s and have successively formulated a large number of anti-static packaging standards. Anti-static packaging materials also developed rapidly, effectively controlling the harm of static electricity. In the industry, the quality and reliability of electronic products have been continuously improved, the service life of electronic devices has increased, and the number of explosive flammable and explosive products on the military has greatly decreased.

In recent years, China has also learned about the harm of static electricity. During the production process, electrostatic protection has been widely noticed.

However, we must not see that no matter whether electronic products or military products are sensitive products such as explosives, pyrotechnics, and ammunition that are sensitive to static electrodes, there has been no explicit mention of antistatic problems in packaging, let alone formulating corresponding technical standards. Here are a few reasons why we should explore.

One is the lack of sufficient understanding of the hazards of static electricity. Some electronic component manufacturers compete for semi-finished products with common plastic boxes that do not have anti-static capabilities at all. The explosives production plant also uses general plastic bags as inner packaging bags of nitro cotton. The analysis of the causes of certain explosion accidents has never been analyzed from the perspective of electrostatic hazards. The second is the lack of in-depth research on anti-static packaging technology. So far we still do not know exactly what the static susceptibility of certain products (especially electric pyrotechnics) is. The research of anti-static packaging materials is also lack of systemic, and the available packaging materials are very limited.

Since 1986, there has been a shortage of anti-static packaging materials in China. 59 carried out research in this area. So far, a series of antistatic packaging materials have been initially formed. This mainly includes anti-static packaging plastic film, buffer foam, injection molding and extrusion molding anti-static plastic. The electrical and mechanical properties of these materials can meet the needs of electrostatic protection of different products, and some products have reached the level of foreign 80s. Initially met the current domestic market demand.

We believe that with the deepening of awareness of electrostatic hazards in people, in the electronics industry and the military industry, anti-static packaging technology will surely develop rapidly.

5 Conclusions and recommendations

The accumulation and discharge of static electricity has caused huge losses to the microelectronics industry and the military industry. The harm of static electricity is not terrible. It is terrible that people lack understanding of it. With the development of science and technology, the harm of static electricity will surely cause more and more departments to attach great importance to it. Anti-static packaging technology will also be rapidly developed.

In order to minimize the harm of static electricity, it is necessary to take decisive measures to enforce anti-static technology. Hereby suggest:

(1) Strengthen the promotion of electrostatic hazards. Strengthen the anti-static awareness of all types of personnel in the electrostatic sensitive product industry.

(2) Military product research and production departments work together to further understand the electrostatic susceptibility of some common pharmaceuticals from the combination of theory and practice, and lay a theoretical foundation for antistatic packaging.

(3) Conduct a comprehensive investigation of explosives, pyrotechnics, and ammunition (including fuzes, flammable cartridges, etc.) in the military industry to ascertain the magnitude of static electricity in product turnover and storage under various environmental conditions. Provide basic data for anti-static packaging.

(4) For electrostatic sensitive products from the production process to the factory, strict control of all aspects of electrostatic protection. In response to the weak link of the factory packaging, we must quickly grasp the legislative work of anti-static packaging.

Source: Southwest Institute of Technology Engineering