An antistatic bag is a bag used for storing electronic components, which are prone to damage caused by electrostatic discharge (ESD).
Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter.
Electrostatic discharge (ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. A buildup of static electricity can be caused by tribocharging or by electrostatic induction. The ESD occurs when differently-charged objects are brought close together or when the dielectric between them breaks down, often creating a visible spark.
These bags are usually plastic polyethylene terephthalate (PET) and have a distinctive color (silvery for metallised film, pink or black for polyethylene). The polyethylene variant may also take the form of foam or bubble wrap, either as sheets or bags. Multiple layers of protection are often used to protect from both mechanical damage and electrostatic damage. A protected device can be packaged inside a metalized PET film bag, inside a pink polyethylene bubble-wrap bag, which is finally packed inside a rigid black polyethylene box lined with pink poly foam. It is important that the bags only be opened at static-free workstations.
Polyethylene terephthalate, commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, thermoforming for manufacturing, and in combination with glass fibre for engineering resins.
Metallised films are polymer films coated with a thin layer of metal, usually aluminium. They offer the glossy metallic appearance of an aluminium foil at a reduced weight and cost. Metallised films are widely used for decorative purposes and food packaging, and also for specialty applications including insulation and electronics. Its burning caused the crash of Swissair Flight 111 in 1998 that killed 229 people.
Bubble wrap is a pliable transparent plastic material used for packing fragile items. Regularly spaced, protruding air-filled hemispheres (bubbles) provide cushioning for fragile items.
Dissipative antistatic bags, as the name suggests, are made of standard polyethylene with a static dissipative coating or layer on the plastic. This prevents buildup of a static charge on the surface of the bag, as it dissipates the charge to ground (i.e., whatever other surface it is touching).This bridge to ground is achieved with the inclusion of a tallow amine on the bags surface which attracts moisture that can conduct the charge to another surface, or to the atmosphere itself. In this sense, this type is truly 'antistatic' in that it hinders the formation of static charges. It, however, is not resistant to electrostatic discharge; if something else with a charge touches the bag (such as a person's hand), its charge would easily transfer through the bag and its contents. These bags are usually pink or red in color because of the dissipative chemical layer. Black bags also exist, wherein the polyethylene is manufactured containing trace amounts of carbon, forming a partial shield, though not a complete one.
Polyethoxylated tallow amine refers to a range of non-ionic surfactants derived from animal fats (tallow). They are used primarily as emulsifiers and wetting agents for agrochemical formulations, such as pesticides and herbicides.
Conductive antistatic bags are manufactured with a layer of conductive metal, often aluminum,and a dielectric layer of plastic covered in a static dissipative coating. This forms both a shield and a non-conductive barrier, shielding the contents from static charge via the Faraday cage effect. These bags are preferred for more sensitive parts, but they also see use in environments where sparks would be hazardous, such as oxygen-rich areas in aircraft and hospitals. Metalized bags are more fragile than their nonmetal counterparts, however, as any puncture compromises the integrity of the shield. In addition, they have a limited shelf life, as the metal substrate can deteriorate over time. These bags are often gray or silver owing to the metal layer, while still being transparent to some degree.
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor but only slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive charges are displaced in the direction of the field and negative charges shift in the opposite direction. This creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axes align to the field.
A Faraday cage or Faraday shield is an enclosure used to block electromagnetic fields. A Faraday shield may be formed by a continuous covering of conductive material, or in the case of a Faraday cage, by a mesh of such materials. Faraday cages are named after the English scientist Michael Faraday, who invented them in 1836.
Foam also exists in both pink (dissipative) and black (conductive) varieties, used for storing individual leaded components by piercing the leads into the foam.
Through-hole technology, refers to the mounting scheme used for electronic components that involves the use of leads on the components that are inserted into holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side either by manual assembly or by the use of automated insertion mount machines.
An antistatic device is any device that reduces, dampens, or otherwise inhibits electrostatic discharge; the buildup or discharge of static electricity, which can damage electrical components such as computer hard drives, and even ignite flammable liquids and gases.
An antistatic agent is a compound used for treatment of materials or their surfaces in order to reduce or eliminate buildup of static electricity. Static charge may be generated by the triboelectric effect or by a non-contact process using a high voltage power source. Static charge may be introduced on a surface as part of an in-mold label printing process.
Electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF shielding.
The triboelectric effect is a type of contact electrification on which certain materials become electrically charged after they are separated from a different material with which they were in contact. Rubbing the two materials each with the other increases the contact between their surfaces, and hence the triboelectric effect. Rubbing glass with fur for example, or a plastic comb through the hair, can build up triboelectricity. Most everyday static electricity is triboelectric. The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, and other properties.
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy.
Conductive polymers or, more precisely, intrinsically conducting polymers (ICPs) are organic polymers that conduct electricity. Such compounds may have metallic conductivity or can be semiconductors. The biggest advantage of conductive polymers is their processability, mainly by dispersion. Conductive polymers are generally not thermoplastics, i.e., they are not thermoformable. But, like insulating polymers, they are organic materials. They can offer high electrical conductivity but do not show similar mechanical properties to other commercially available polymers. The electrical properties can be fine-tuned using the methods of organic synthesis and by advanced dispersion techniques.
Static cling is the tendency for light objects to stick (cling) to other objects owing to static electricity. It is common in clothing, but occurs with other items, such as the tendency of dust to be attracted to, and stick to, plastic items.
Corona treatment is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface. The corona plasma is generated by the application of high voltage to an electrode that has a sharp tip. The plasma forms at the tip. A linear array of electrodes is often used to create a curtain of corona plasma. Materials such as plastics, cloth, or paper may be passed through the corona plasma curtain in order to change the surface energy of the material. All materials have an inherent surface energy. Surface treatment systems are available for virtually any surface format including dimensional objects, sheets and roll goods that are handled in a web format. Corona treatment is a widely used surface treatment method in the plastic film, extrusion, and converting industries.
Body capacitance is the physical property of the human body that has it act as a capacitor. Like any other electrically-conductive object, a human body can store electric charge if insulated. The actual amount of capacitance varies with the surroundings; it would be low when standing on top of a pole with nothing nearby, but high when leaning against an insulated, but grounded large metal surface, such as a household refrigerator, or a metal wall in a factory.
An electrostatic-sensitive device is any component which can be damaged by common static charges which build up on people, tools, and other non-conductors or semiconductors. ESD commonly also stands for electrostatic discharge.
Electronic packaging is the design and production of enclosures for electronic devices ranging from individual semiconductor devices up to complete systems such as a mainframe computer. Packaging of an electronic system must consider protection from mechanical damage, cooling, radio frequency noise emission and electrostatic discharge. Product safety standards may dictate particular features of a consumer product, for example, external case temperature or grounding of exposed metal parts. Prototypes and industrial equipment made in small quantities may use standardized commercially available enclosures such as card cages or prefabricated boxes. Mass-market consumer devices may have highly specialized packaging to increase consumer appeal. Electronic packaging is a major discipline within the field of mechanical engineering.
A flexible intermediate bulk container (FIBC), bulk bag, or big bag, is an industrial container made of flexible fabric that is designed for storing and transporting dry, flowable products, such as sand, fertilizer, and granules of plastic.
Electrostatic coating is a manufacturing process that employs charged particles to more efficiently paint a workpiece. Paint, in the form of either powdered particles or atomized liquid, is initially projected towards a conductive workpiece using normal spraying methods, and is then accelerated toward the work piece by a powerful electrostatic charge.
Velostat is a packaging material made of a polymeric foil (polyolefins) impregnated with carbon black to make it electrically conductive. It is used for the protection of items or devices that are susceptible to damage from electrostatic discharge. It was developed by Custom Materials, now part of 3M. Velostat is now a U.S. registered trademark (4,964,564) of Desco Industries Inc. Desco Industries purchased the assets of the 3M Static Control business on January 2, 2015.
Electronic components have a wide range of failure modes. These can be classified in various ways, such as by time or cause. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
Faraday's ice pail experiment is a simple electrostatics experiment performed in 1843 by British scientist Michael Faraday that demonstrates the effect of electrostatic induction on a conducting container. For a container, Faraday used a metal pail made to hold ice, which gave the experiment its name. The experiment shows that an electric charge enclosed inside a conducting shell induces an equal charge on the shell, and that in an electrically conducting body, the charge resides entirely on the surface. It also demonstrates the principles behind electromagnetic shielding such as employed in the Faraday cage. The ice pail experiment was the first precise quantitative experiment on electrostatic charge. It is still used today in lecture demonstrations and physics laboratory courses to teach the principles of electrostatics.
Electrostatic discharge materials are plastics that reduce static electricity to protect electrostatic-sensitive devices (ESD) or contain flammable liquids or gases.
|This electronics-related article is a stub. You can help Wikipedia by expanding it.|