The type, selection and installation of conductive rubber

Conductive rubber

Conductive rubber is to uniformly distribute conductive particles such as glass silver-plated, aluminum silver-plated and silver in silicone rubber, and make the conductive particles contact by pressure to achieve good electrical conductivity. It has good electromagnetic sealing and water-vapor sealing ability, and can provide good electrical conductivity under certain pressure,
It is widely used in electronic equipment with airtightness and electromagnetic shielding such as aerospace, aviation, ships and weapons.

Types of Conductive Rubber

Different metal particles filled in conductive rubber have different properties and applicable occasions. Molded glass silver-plated conductive rubber is suitable for a wide range of EMI applications and provides reliable low-cost shielding; sterling silver conductive rubber is available in a variety of durometers and compositions to resist mildew and is suitable for low to medium voltage applications; silver-plated copper Conductive rubber has the maximum conductivity and the best shielding effect; nickel-silver-plated conductive rubber has corrosion resistance and can provide relatively high shielding effect; aluminum-silver-plated conductive rubber has low cost, has the highest conductivity, the least galvanic corrosion, and the weight comparison Lightweight, provides excellent moisture seal for chassis joints and gaps; graphite nickel-plated conductive rubber has high conductivity and is used in applications requiring broadband shielding and environmental sealing.

The commonly used cross-sectional shapes of conductive rubber are: rectangle, tube, circle and hollow D shape, etc., and can also be processed into special shapes according to needs. The rectangular rubber has a large contact area with the structural member, and the same compression amount requires the largest pressure; the tubular and hollow D-shaped rubber requires the least pressure for the same compression amount.

Selection and Installation of Conductive Rubber

When designing, it is necessary to select conductive rubber with different fillers according to the base material of the structure, so that the contact surface between the conductive rubber and the device can be electrochemically compatible. If the size allows, try to use a thicker pad, which allows the structural parts to have larger machining errors. Due to the addition of metal particles to silicone rubber, the physical properties of conductive rubber such as hardness, elastic modulus and strength are different from ordinary silicone rubber. Therefore, it is necessary to select the appropriate compression amount according to the requirements of the corresponding manual and the actual situation of the equipment.

Pay attention to the following when installing conductive rubber:

① The conductive rubber should be installed in a position that is not easy to be damaged, and the metal surface must be clean and conductive during installation;

② Try to use the groove installation method, which is convenient for fixing the conductive rubber and controlling the amount of compression; the width of the groove should be sufficient to ensure that the side of the conductive rubber can be freely stretched when compressed;

③ The rigidity of the structural parts should be sufficient, and the structural parts should not be significantly deformed by the elastic force of the conductive rubber after tightening, which will affect the sealing and shielding performance;

④ Select the appropriate screw diameter and spacing, so that the structural parts have enough pressure to ensure that the conductive rubber can reach the expected deformation, and the appropriate screw spacing can also prevent the structural parts from being significantly deformed;

⑤ When the conductive rubber is installed in the groove, it is generally pasted and fixed with conductive glue. The disadvantages are: increased cost, uneven application of conductive glue will lead to different heights of rubber pads, affecting sealing, and aging of conductive glue will reduce shielding effectiveness. It is recommended to drop a small drop of non-conductive glue on the place where the screw hole passes through. The place where the glue is not conductive, but it can still play a conductive role through the contact between the screw and the conductive rubber and structural parts.