The contacts of RJ45 connectors are the core components to ensure the resistance and reliability in using. And the contact resistance is mainly affected by the contact material, the impact of vertical pressure, surface morphology, application voltage and current, and other factors.
1) contact material
The electrical connector of different material and technical conditions for the production of the same specifications mating contacts, contact resistance provides a different assessment indicator. Rapid separation of electrical connectors totals resistance to environmental norms GJB101-86 predetermined diameter of 1mm contact mating contact resistance of copper alloy ≤5mΩ, ferroalloy ≤15mΩ.
2) The surface pressure perpendicular to the contact surface
Perpendicular to the surface of the pressure contact means in contact with each other and perpendicular to the surface of the contact surface of the force. With vertical pressure increases, the number of contact points and the micro area is also increasing, while the contact point of transition from micro elastic deformation to plastic deformation. Resistance decreases due to the concentration, leaving the contact resistance is reduced.
The contact pressure is primarily dependent on the geometry and material properties of the contact member.
3) surface morphology
Including the design of the shape of the surface morphology and the state of the environment, the more loose surface membrane contacting surface may be due to dust, rosin, oil and other mechanical attachment in the contact surface formed by deposition, this layer of film because the table easily fitted with a particulate matter hidden in microscopic pits at the contact surface, the contact area is reduced, the contact resistance increases, and highly volatile. Second, the membrane fouling due to physical adsorption and chemical adsorption formed on the metal surface is mainly chemisorption, which is accompanied by physical adsorption after electron mobility generated. Therefore, some of the high-reliability requirements of the product, such as aerospace electrical connector assembly must be clean environmental conditions and improve the cleaning process necessary structural sealing measures, the use of units must have good storage and use of operating environmental conditions.
When using the voltage reaches a certain threshold, the film will contact the breakdown, leaving the contact resistance decreased rapidly. However, due to the thermal effect accelerates the chemical reaction layer near the area of the film has some repair. So resistance is nonlinear. In the vicinity of the threshold voltage, the voltage drop will be small fluctuations in the current may cause twenty times or several times range. The contact resistance change dramatically, not to understand this error occurs when testing and useful contacts.