Reliability screening test for terminal block failure prevention

In order to ensure the quality and reliability of the terminals and prevent the occurrence of fatal faults, it is recommended to study and formulate the corresponding screening technical requirements according to the technical conditions of the products, and carry out the following reliability tests for preventing failures.

1. Prevent contact failure

1) Conduction detection

At present, the general terminal manufacturer's product acceptance test does not have this item, and the user generally needs to conduct conduction test after installation. Therefore, it is recommended that manufacturers should increase the point-by-point conduction test by 100% for some key models.

2) Instantaneous detection

Some terminals are used in a dynamic vibration environment. The experiment proves that it is only qualified to check whether the static contact resistance is qualified, and it cannot guarantee the reliable contact in the dynamic environment. Because the connector with good contact resistance often exhibits instantaneous power failure during vibration, shock and other simulated environmental tests, it is better to test the dynamic vibration test of some high reliability terminals. Contact reliability.

3) Single hole separation force detection

The single-hole separation force refers to the separation force in which the contact member in the engaged state changes from static to moving, and is used to characterize that the pin and the socket are in contact. Experiments show that the single-hole separation force is too small, which may cause signal transients when subjected to vibration and shock loads. It is effective to check the contact reliability by measuring the single hole separation force to measure the contact resistance. Check that the single hole separation force is too poor, the measured contact resistance is still qualified. To this end, in addition to the development of a new generation of flexible plug contacts with stable and reliable contact parts, the production plant should not use the automatic insertion force tester for multi-point measurement of key models, and 100% point-by-point processing for finished products. Hole separation force check to prevent signal breakage caused by individual jack relaxation.

2. Prevent insulation failure

1) Insulation inspection

The quality of raw materials has a great influence on the insulation properties of insulators. Therefore, the choice of raw material manufacturers is particularly important, and it is impossible to reduce the cost and lose the material quality. You should choose the reputable material of the big factory, and carefully check the inspection lot number, material proof and other important information for each batch of materials, and make traceable information on the use of materials.

2) Insulation insulation resistance inspection

At present, some of the production plant processes are required to be assembled into finished products and then tested for electrical properties. As a result, the insulation of the insulator itself is unqualified, and only the entire batch of finished products is scrapped. A reasonable process should be 100% process screening in the state of the insulator parts to ensure electrical performance.

3. Prevention of poor fixation

1) Interchangeability check

Interchangeability checks are a dynamic check. It requires that the same series of plugs and sockets can be mated to each other, and it is found that there is no difference in the size of the insulators, contacts, etc., the missing parts or the assembly is not in place, etc., which cannot be inserted, positioned and locked. Even under the action of the rotating force, it causes disintegration. Another function of the interchangeability check is to find out whether there are metal surpluses that affect the insulation performance through plugging and unplugging, such as threads and bayonet. Therefore, for some important applications, the terminal should be 100% checked to avoid such major fatal failures.

2) Torque resistance check

Torque resistance inspection is a very effective inspection method to assess the reliability of the terminal structure. Such as the US military standard MIL-L-39012 standard. According to the standard, each batch should be sampled for torque resistance inspection, and problems should be discovered in time.

3) General measurement of crimped wires

In the electrical installation, it is often found that the individual core crimping wires are not in place, or cannot be locked after being sent to the position, and the contact is unreliable. The reason for the analysis is that there are burrs or dirt stuck in the screw holes of the individual mounting holes. In particular, the use of the factory has been installed in the last mounting holes of a plug socket, and it is found that after the ill, the other crimped wires of the other holes have to be unloaded one by one, and the plug is replaced again. In addition, due to the improper matching of the wire diameter and the crimping aperture, or due to the operation of the crimping process, the crimping end is not secure. To this end, the manufacturer must pass all the mounting holes of the sample of the plug (seat) of the delivery before the finished product leaves the factory, that is, use the loading and unloading tool to send the wire crimped with the pin or jack to the position, check whether Locked. According to the technical requirements of the product, the pull-out force of the crimping wires is checked one by one.

Without reliable terminals, there is no reliable system engineering. Failure and reliability are two aspects of a contradiction that are corresponding and interconnected. Through the reliability screening of terminal blocks, various failure modes and failure mechanisms are found, which can lead to a lot of lessons and eliminate various hidden dangers, and provide scientific basis for improving design, process, inspection and use. It is also important to revise and formulate technical conditions of terminal blocks. in accordance with. Finding measures to prevent failure and achieving a transition from failure to reliability is the ultimate goal of failure analysis.