What Are The Factors That Affect The Contact Resistance Of RJ45 Interface Pins

RJ45 connector, which is a common network cable connector, 8 contacts of which are composed of PIN pins. Generally, there are 4 factors that affect the pin contact resistance: vertical pressure, contact material, operating voltage, and surface morphology. The following are detailed analysis.

1. Vertical pressure

Vertical pressure refers to the force generated by the surfaces in contact with each other and perpendicular to the surfaces of the contact pieces. With the increase of vertical pressure, the number and area of contact micro-points also gradually increased, and the contact micro-points transitioned from elastic deformation to plastic deformation. Since the concentrated resistance gradually decreases, and the contact resistance decreases, the vertical pressure of the contact depends mainly on the geometry and material properties of the contact.

2. Contact material

Because the technical conditions of electrical connectors stipulate different contact resistance assessment indicators for contacts of the same specification made of different materials. The general specification GJB101-86 for quick-release environmental-resistant electrical connectors stipulates that the contact resistance of mating contacts with a diameter of 1mm is ≤15mΩ for iron alloys and ≤5mΩ for copper alloys.

3. Use voltage

The use of voltage means that when a certain threshold is reached, the film of the contact piece will be broken down, and the contact resistance will drop rapidly. However, because the thermal effect accelerates the chemical reaction in the vicinity of the film layer, it has a certain repair effect on the film layer, so the resistance value is nonlinear. Near the threshold voltage, the small fluctuation of the voltage drop will cause the current to be 20 times or tens of times. range changes.

4. Surface morphology

Surface morphology mainly refers to the shape of the design and the state of the environment.

Design shape: The fouling film formed by physical adsorption and chemical adsorption is mainly chemical adsorption on the metal surface, which is generated with electron migration after physical adsorption. Therefore, for some products with high reliability requirements, such as aerospace electrical connectors, they must have clean assembly and production environmental conditions, perfect cleaning processes and necessary structural sealing measures, and the user unit must have good storage and operating environmental conditions. .

Environmental state: some contact parts may be formed by mechanical adhesion and deposition of dust, rosin, oil, etc. on the surface of the contact surface. At the pit, the contact area is reduced, the contact resistance is increased, and it is more unstable.