From the perspective of use, the function that the terminal should achieve is that the contact part must be conducted and the contact is reliable. Insulated parts that should not be conducted must be insulated reliably. There are three common fatal failure forms of terminals:

1. The problem of poor contact

The metal conductor inside the terminal is the core part of the terminal, which transmits the voltage, current or signal from the external wire or cable to the contact corresponding to the connector. Therefore, the contact must have excellent structure, stable and reliable contact retention and good electrical conductivity. Due to the unreasonable structure design of the contact, the wrong material selection, the mold is unstable, the processing size is out of tolerance, the surface is rough, the surface treatment process such as heat treatment electroplating is unreasonable, improper assembly, poor storage and use environment and improper operation and use will cause poor contact at the contact part and matching part of the contact.

2. The problem of poor insulation

The function of the insulator is to keep the contacts in the correct position and arrangement, and to insulate the contacts from the contact to the housing. Therefore, the insulation must have excellent electrical properties, mechanical properties and process molding performance. Especially with the widespread use of high-density, miniaturized terminals, the effective wall thickness of the insulator is getting thinner and thinner. This puts forward more stringent requirements for insulation materials, injection mold accuracy and molding process. Due to the existence of excess metal on the surface or inside the insulator, surface dust, flux and other pollution and moisture, organic material precipitates and harmful gas adsorption film and surface water film fusion to form ionic conductive channels, moisture absorption, mold growth, aging of insulating materials and other reasons, will cause short circuit, leakage, breakdown, low insulation resistance and other insulation defects.

3. The problem of poor fixation

The insulator not only plays an insulating role, but also provides precise centering and protection for the extended contact. At the same time, it also has the functions of installation and positioning, locking and fixing on the equipment. Poor fixation, light impact on contact and reliability, resulting in instant power failure, serious is the disintegration of products. Disintegration refers to the abnormal separation between the plug and the socket, and between the pin and the socket due to the unreliable structure of the wire terminal in the plugged state due to the material, design, process and other reasons, which will cause the power transmission of the control system And the serious consequences of signal control interruption. Due to unreliable design, wrong material selection, improper selection of molding process, poor quality of heat treatment, mold, assembly, welding and other processes, and improper assembly will cause poor fixation.

In addition, poor appearance caused by coating peeling, corrosion, bruising, plastic shell flash, cracking, rough contact processing, deformation and other reasons, poor exchange caused by positioning and locking fit size, poor processing quality consistency, excessive total separation force and other reasons are also common and frequently-occurring diseases. These kinds of faults can generally be found and eliminated in time during inspection and use.