Electrostatic protection material
Electrostatic protective materials or antistatic materials play an important role in electrostatic protection and control engineering. Electrostatic protective products made of antistatic materials such as containers, garments, conveyor belts, etc. are essential in the manufacturing process.
1 Basic concepts related to electrostatic protection materials
Here are some basic material-related concepts used in ESD protection and control technology.
Resistance and Resistivity: These are two key concepts in electrostatic control technology that are often confused and used not only to represent materials, but also to describe test methods for evaluating materials.
Volume resistivity: refers to the ratio of the DC voltage drop across a unit thickness to the current passing through a unit area. The bulk resistivity is one of the basic parameters of a material and its electrical conductivity is expressed in ohms/cm.
Surface resistivity: This parameter is used for a film material of a certain thickness, which is defined as the ratio of the DC voltage drop per unit length on the surface to the current flowing through the unit width. It refers to the resistance between the two opposite sides of the square, as long as the area is much larger than the film thickness, the resistance is independent of the size of the square. The unit of surface resistivity is ohms.
Resistance: On the other hand, the resistance of a material of different shapes (area and length) and resistivity to current, which also indicates the circuit connectivity between the surface or surface of the material and the discharge capacity of the object, in ohms. .
Surface Resistance: According to EOS/ESD S11.11 "Measurement of Surface Resistance of Electrostatic Discharge Planar Materials", surface resistance is the ratio of the DC voltage between two points on a material's surface to the current passed, expressed in ohms. The surface resistance value is independent of the structure of the material.
Body resistance: According to the definition in ESD DS11.12 "Measurement of bulk resistance of electrostatic discharge plane material", body resistance refers to the ratio of DC voltage to current passing between the two ends of the material, and its unit is also ohm.
Insulating material: generally refers to a material having a surface resistivity of 1×10 12 ohms or a bulk resistivity of 1×10 11 Ω/cm or more. There is substantially no current flowing on the surface or inside of the insulating material, and its resistance is large and it is difficult to ground. The static charge in this material will remain on it for a long time.
Conductive material: generally refers to a material having a surface resistivity of less than 1 x 105 ohms or a bulk resistivity of less than 1 x 104 ohms/cm. This material has a low electrical resistance, and electrons flow very easily on its surface and inside, flowing to any other conductor or earth that is in contact.
Dissipative material: generally refers to a material having a surface resistivity greater than or equal to 1 x 105 and less than 1 x 1012 ohms, or a bulk resistivity greater than or equal to 1 x 104 and less than 1 x 1011 ohm/cm.
Shielding material: Generally, the material with a surface resistivity of less than 1×10 10 ohms per millimeter thickness or a body resistivity of less than 1.0×103 ohms/cm is used. The Faraday protective cover made of this material can prevent electrostatic sensitive devices from being electrostatically charged. Impact.
Antistatic property: Generally refers to the property of the material to suppress friction and electrification. The antistatic properties of materials are not necessarily related to their electrical resistance or electrical resistivity. For example, some antistatic materials have high electrical resistance and are high-insulation type, but the power is very small, and static friction does not occur due to repeated friction.
Understanding and properly using these basic concepts in electrostatic control can make the term more accurate, which helps to effectively implement ESD control.