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Share the experience of | common faults of terminals and what are the solutions?

  • DATE:2018/4/16 14:58:55

Share the experience of | common faults of terminals and what are the solutions?


The plastic insulating materials and conductive parts of terminals are directly related to the quality of terminals, which determine the insulation and electrical conductivity of terminals, respectively. Failure of any terminal will result in failure of the whole system. The painful lessons at home and abroad are very profound.
Prevention is the purpose, and analysis is the basis. In a sense, preventive failure is more important than failure analysis. It has more practical significance for ensuring the quality and reliability of the terminals.
From the perspective of usage, the connection terminal should achieve the following functions: the contact part must be connected and the contact must be reliable. Where the insulation part should not be connected, the insulation must be reliable.

One
There are three fatal failure modes of terminals:
One
Poor contact


The metal conductor inside the terminal is the core part of the terminal, which transfers the voltage, current, or signal from the external wires or cables to the contacts corresponding to the connectors that they match. Therefore, contacts must have excellent structure, stable and reliable contact force and good electrical conductivity. Due to unreasonable structure design of contact parts, improper selection of material, unstable mold, super poor processing size, rough surface, heat treatment electroplating, improper surface treatment technology, improper assembly, bad storage and use environment and improper operation, will cause contact defects in contact parts and fit parts of contact parts.


Two
Poor insulation
The function of insulators is to keep the contacts in the correct position, and to insulate the contacts between the contacts and the contacts, the contacts and the shells. Therefore, insulation parts must have excellent electrical properties, mechanical properties and process molding performance. Especially with the extensive use of high-density and miniaturized terminal blocks, the effective wall thickness of insulators is getting thinner and thinner. This puts forward stricter requirements for insulation materials, injection mold accuracy and molding process. Due to the presence of multiple metal residues in the insulator surface or inside, surface dust, flux and other pollution are damp, the precipitation of organic materials and the adsorption film of harmful gas and surface water film form the ionic conductive channel, which can cause short circuit, leakage, breakdown and low insulation resistance. Bad luck.
Three
Poor fixation
Insulators not only play an insulating role, but also provide accurate pair neutralization for extended contacts, but also have the function of installing and locking in the equipment. Poor fixation, light impact and reliable contact cause instant power failure, and the most serious is product disintegration. Disintegration refers to the abnormal separation of the plug and socket between the plug and socket caused by the unreliability of the structure caused by the material, design, technology and other reasons, which will result in the serious consequences of the power transmission and signal control interruption of the control system. Due to unreliable design, wrong selection of material, improper selection of molding process, poor quality of heat treatment, die, assembly and welding, and so on.


In addition, due to the skin, corrosion, bruising, plastic shell flying edge, rupture, contact parts processing rough, deformation and other causes of the appearance of bad appearance, due to positioning locking with the size of super poor, poor quality of processing, excessive total separation force and other causes of poor interchangeability, is also a common disease, frequently occurring disease. These faults can be found out in time in the process of inspection and use.

Reliability screening test for prevention of failure:
In order to ensure the quality and reliability of terminal terminals and prevent the occurrence of these fatal faults, it is suggested that according to the technical conditions of the product, the corresponding screening technical requirements are studied and formulated, and the reliability test of prevention failure is carried out below.

1. prevention of poor contact
1) conduction detection
At present, there is no such item in the product acceptance test of the general wiring terminal manufacturer, and generally needs conduction test after installing the machine. Therefore, it is suggested that manufacturers should increase 100% of point-to-point detection for some key products.
2) transient detection
Some wiring terminals are used in dynamic vibration environment. It is proved by experiment whether the static contact resistance is qualified or not, and the contact reliability in dynamic environment can not be guaranteed. Because often contact resistance connectors in the vibration, impact and other simulated environmental tests still appear instantaneous power failure phenomenon, so some of the high reliability terminals, the best can be 100% of its dynamic vibration test to assess the contact reliability.
3) single hole separation force detection
The single hole separation force refers to the separation force from the static state to the moving contact, which is used to characterize the contact between the pin and the socket. The experiment shows that if the separation force of single hole is too small, it will cause signal transient when subjected to vibration and impact load. It is effective to measure contact reliability by measuring single hole separation force than measuring contact resistance. It is found that the contact resistance is often qualified by checking the hole with a single hole separation force. Therefore, in addition to developing a new generation of flexible intercalation contact and stable contact parts, the production plant should not use the multi point test of the automatic pulling force test machine for the key model, so that 100% of the point by point single hole separation force check for the finished product should be carried out to prevent the signal transient caused by the relaxation of the individual Jack.

2. prevention of poor insulation
1) inspection of insulating materials
The quality of raw materials has great influence on insulation performance of insulators. Therefore, the selection of raw material manufacturers is particularly important. We should not simply reduce costs and lose material quality. We should choose reputable factories.


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