The metal conductor inside the terminal is the core part of the terminal, which transmits the voltage, current or signal on the external wire or cable to the corresponding contact of its matching connector. Therefore, the contact must have excellent structure, stable and reliable contact retention and good conductivity. Due to unreasonable structural design, wrong material selection, unstable mold, out-of-tolerance machining size, rough surface, unreasonable surface treatment processes such as heat treatment and electroplating, improper assembly, bad storage and use environment, improper operation and use, etc., poor contact between contact parts and mating parts will be caused.
2. Poor insulation
The function of the insulator is to keep the contacts in the correct position, and to insulate the contacts from each other and from the housing. Therefore, insulating parts must have excellent electrical properties, mechanical properties and processability. Especially with the wide use of high-density and miniaturized terminals, the effective wall thickness of insulators is getting thinner and thinner. This puts forward stricter requirements for insulating materials, injection mold accuracy and molding process. Due to the pollution of metal residues, surface dust, flux, etc. on the surface or inside of insulators, organic matter precipitation and the fusion of harmful gas adsorption film and surface water film form ion conduction channels, moisture absorption, moldy growth, aging of insulation materials and other reasons, it will cause short circuit, leakage, breakdown, low insulation resistance and other bad insulation phenomena.
3. Poor fixation
Insulators not only play the role of insulation, but also provide accurate centering protection for protruding contacts, and also have the functions of installation, positioning, locking and fixing on equipment. Poor fixity, light will affect contact reliability and instantaneous power failure, and heavy will lead to product disintegration. Disassembly refers to the abnormal separation between plug and socket, pin and jack due to the unreliable structure of terminal in the plugging state, which will lead to the serious consequences of power transmission and signal control interruption of control system. Due to unreliable design, wrong material selection, improper selection of molding process, poor quality of heat treatment, mold, assembly and welding, and inadequate assembly, poor fixation will be caused.
In addition, poor appearance caused by peeling, corrosion, bumping, plastic shell flash, cracking, rough processing and deformation of contact pieces, poor interchangeability caused by out-of-tolerance of positioning and locking fit dimensions, poor consistency of processing quality and excessive total separation force are also common and frequently-occurring diseases. Generally, these faults can be found and eliminated in time during inspection and use.