Conductive rubber is used to connect glassplate with silver, aluminum silver plating, silver and other conductive particlesuniform distributionIn silicone rubber, conductive particles are contacted by pressure to achieve good conductivity.It is applied in both military and commercial fields.Its main function is to seal andelectromagnetic shielding 。The products can be molded or extruded, and there are options for chip or other punching shapes.Shielding performance up to 120 dB (10 GHz).It is divided into CONSIL-NC (graphite nickel plated silicone rubber) CONSIL-V (silver filled silicone rubber extrusion gasket) CONSIL-A (aluminum silver plated silicone rubber) CONSIL-N (nickel silver plated silicone rubber) CONSIL-C (copper silver plated silicone rubber) SC-CONSIL (graphite silicone rubber CONSIL-R (pure silver silicone rubber) CONSIL-II (silver filled silicone rubber molded gasket), etc.[1]
1. When the conductive particles filled in the conductive rubber are filled with a certain volume fraction, they contact each other to form an electronic continuous state. When the external electromagnetic field reaches the outside of the conductive rubber, strong electromagnetic waves hit the conductive particlesfree electronOn the other hand, free electrons move freely. During their movement, free electrons form electromagnetic fields that are opposite to the external electromagnetic fields. The internal and external electromagnetic fields cancel each other to weaken electromagnetic interference waves;
2. Another principle isEnergy conversion，conservation of energyThe electromagnetic wave hits the free electron. During the movement of the free electron, the conductive particles have certain resistance and generate heat, that is, electromagnetic interference wave——free electronKinetic energy - thermal energy to weaken electromagnetic interference waves.[1]
According to the relationship between current, voltage and resistanceVoltage dropThere is always a certain current flow, but the current is too small for people to feel.Conductive rubberVolume resistanceCompared with metal, it is still large. According to the relationship between volume resistance and distance, the longer the distance, the greater the resistance.On medical electrodes, conductive rubber has been widely used. At this time, the conductive rubber electrode is thin, generally below 1mm, and the electrode only contacts on the upper and lower sides, that is, the distance is only 1mm. At this time, the conductive rubber is fully energized.[1]
Conductive rubber
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Structural design
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Conductive rubber must be subject to a certain compression force in order to conduct electricity well, so the structural design must ensure appropriate pressure without overpressure.The optimum height compression of plate is 7~15%;The best height compression of solid circle and D-shape is 12~30%;The optimal height compression of tubular and P-shaped is 20~60%[1]。
purpose
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Conductive rubber has good electromagnetic sealing and water vapor sealing capabilities, and can provide good conductivity under certain pressure (suppression frequency reaches 40GHz).[1]
Conductive rubber meets the US military standard MIL-G-83528 and is widely used in electronics, telecommunications, power, military industry, aviation, aerospace, ships and other fields.Conductive rubber is mainly made of high-performance silicone rubber as the base material, with special fillers (such as copper silver plating, aluminum silver plating, glass silver plating, graphite nickel plating particles, etc.) and additives, and through strictly controlled processes,Volume resistivityIt can reach 0.004 Ω cm with good stability.[1]
application
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Conductive rubber usually refers toVolume resistanceWithin 10 to 9 ohm centimeters, since rubber is an excellent insulator, the volume resistance is more than 10 for about 14 times.Conductive rubber is divided into anti-static conductive rubber, and the volume resistance is between the 5th power of 10 and the 9th power of 10,Conductive carbon blackThe volume resistance of filled conductive rubber can usually be kept at several thousand Ohms, or even as low as one or two hundred Ohms. It is very difficult to keep the volume resistance below 50 Ohms.When the volume resistance is less than 10 ohm cm, the conductive rubber haselectromagnetic shielding Function.What follows is that the volume resistance is less than 10 ohm cm, which is mainly used in electromagnetic shielding occasions, as well as electronic and microwave waveguide systems such as chassis, cabinets, shelters, connector pads, etc.[1]
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In our daily life, we can cut off a small piece of conductive rubber to repair the position of the electrical contact like the remote control. For the iron sheet like the battery electrode of the remote control, it is easy to be corroded. If we replace the electrode with a conductive rubber sheet, it will not rust, it can be waterproof, and it is convenient to change three times. It is a good choice.But only withConductive carbon blackFilled conductive rubber,Volume resistanceIt can be used in daily life in the range of several hundred ohm centimeters.[1]
Whether the electromagnetic shielding effectiveness and volume resistance must be in direct proportion, that is, the better the conductivityShielding effectivenessThe higher, according to foreign scholars' research, there are three ways to weaken interference waves: shielding, absorbing and filtering.Conductive rubber, due to its conductive particles, can generate a magnetic field opposite to the outside during the movement of electrons, playing a shielding role.But the principle of wave absorption is similar to that of shieldingMicroparticle。When the filled conductive particles reach the nanometer level, not only the particle size is nm, but also theSpecific surface area，Voids, like thisNanoparticlesWill have betterNano effect, nano effect can have wave absorption effect.It is conductive rubber filled with conductive particles, which can shield and absorb waves.Volume resistanceIt may only reflect the size of the shielding from one side, but it is impossible to measure the size of the absorbing capacity.andConductive carbon blackAlthough the volume resistance of filled conductive rubber is large, it can absorb waves due to its nano diameter and nano effect.So we will also see carbon black filled rubberSealing stripThe magnetic field intensity of the microwave oven is particularly high, up to more than 14G, and the rubber filled with carbon black can better weaken the magnetic field wave.[1]
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Nickel coated copper powder
Nickel coated copper powder isConductive silicone rubberThe most ideal conductive filler, excellent conductivity and electromagnetic wave shielding performance, has good oxidation resistance when conductive rubber is formed at high temperature, and has strong corrosion resistance in various environments（Salt spray test）And have a fairly long service life, and ensure 100% of the qualified products.Cost comparisonplate with silverProducts such as silver platingGlass bead, silver platedAluminium powderSilver plated copper powder and pure silver powder have strong cost advantages.The rise of silver price will not lead to the instability of supply price.Nickel coated copper powder has comparable price stability.It is the main filling powder of the last conductive silicone rubber.The main representative models of the market are: Tengfei Metal Technology W-5 nickel coated copper powder.Due to its mature technology and good coating, it can be filled and used in various rubbers. From a technical point of view, a good nickel coated copper powder has quite a number of technical difficulties in production technology, and the poor coating can not meet the requirements of shielding performance.Choose goodNickel coated copper powderIt is the key to product quality.[2]
aluminumplate with silverConductive rubber: It has excellent shielding performance and smoke resistance;
Copper silver plated conductive rubber: the bestConductivity；
Silver plated glass conductive rubber: the bestcost performance；
Sterling silver conductive rubber: It has good mildew resistance.[2]
FIP conductive rubber
FIP (Form In Place) conductive rubber is a new type of high-performance rubber for electromagnetic sealing gasket with small sizeElectromagnetic shielding composite, onelectromagnetic shielding In the material industry, it is usually called dispensing conductive rubber.This material is specially designed toFluid state, made of one or two component silicone rubber and metal based conductive filler uniformly mixed[3]。
FIP，Also known as dispensing forming, on-site forming, in-situ forming, in-situ forming, surface dispensing and surfaceGutta percha, refers to the forming method of conductive rubber.[3]
When in use, the uncured conductive rubber in fluid state is applied to the designated position on the flange surface from the needle point after applying air pressure through the computer operated numerical control machine tool.The pointed rubber material does not flow or deform. It can be formed in situ at room temperature when contacting the moisture in the air. After curing, it forms a permanent bond with the substrate.[3]
The main function of FIP conductive rubber is to provide low impedance and flexible connection between conductive surfaces, and to provide environmental sealing, which is directly used for the parts to be shielded.Because of its good thixotropy and adhesiveness, it can be easily and directly applied to the flange surface made of a variety of metallized plastics and metal materials.[3]
