When we buy food will check the production date and shelf life on the packaging, the same, terminal block connectors also have a certain period of safe use. Terminal products stored in certain environmental conditions for a period of time, the material may change, the product performance will also decline, a long time to set aside, the reliability of the product will not be guaranteed. Today we will talk about the terminal connector “shelf life”.
Terminal “shelf life” refers to from the production and inspection of qualified to install the machine before storage time in certain environmental conditions, and the effective storage period of the terminal is the terminal in the storage period of the quality and reliability in the installation of the machine can meet the equipment requirements of the period, the basic validity period is not considered the terminal quality level of effective storage period.
A, the factors affecting the terminal storage period.
The effective storage period of the terminal length and the following three factors related to.
1. the quality of the terminal, is to ensure that the terminal in the effective storage period of quality and reliability will not significantly degrade the basic conditions;.
2. terminal storage environmental conditions.
3. Terminal storage after the qualification criteria.
In most of the total specifications and detailed specifications of terminal blocks are specified in the storage environment of terminal blocks.
Such as SJ331 provides the semiconductor integrated circuit storage environmental conditions: -10 ℃ ~ +40 ℃, RH ≤ 80%; U.S. military standard for semiconductor integrated circuit storage environment temperature range of -65 ℃ ~ +150 ℃. GB4798.1 provides for the storage of precision instruments, terminals warehouse environmental level for the highest level, environmental conditions: 20 ℃ ~ 25 ℃; RH for 20% ~ 70%; air pressure of 70kPa ~ 106kPa. QJ2222A provides a general Storage environment and special storage environment two types of conditions.
Second, the effective storage period of terminal blocks
The terminal is composed of two major parts of different materials: plastic insulation parts, different plating hardware. Plastic and metal storage period is not the same, a complete product storage period should be the fastest aging parts shall prevail. Usually, the life of the insulating parts have 3 years, but due to the different storage environments, vary greatly.
U.S. military standards in the early provisions of the “backlog” more than 12 months of semiconductor discrete devices need to be re-inspected upon delivery, which can be considered the effective storage period of semiconductor discrete devices is 12 months. After the release of the version provides more than 24 months of semiconductor discrete devices, delivery need to re-inspection; after the release of the new version provides a “backlog” of more than 36 months of semiconductor discrete devices, delivery need to re-inspection.
Third, the terminal block overdue re-inspection
More than 3 years of inventory terminals, before installation should be re-tested. Review test includes: electrical characteristics test, visual inspection of appearance and destructive physical analysis (DPA). Use 3 ~ 10 times magnification or microscope for the appearance of the terminal block inspection. Terminal break or shell off for fatal defects; terminal rust or surface damage for serious defects; surface coating off, blistering or sign blurred but does not affect the use of light defects. These three defects of the terminal block for unqualified. Electrical characteristics test, the electrical characteristics of the terminals have been tested in the warehouse, should be tested in accordance with the method of the same parameters of the test. For the electrical characteristics of the terminal not tested at the time of storage, according to the corresponding detailed specifications of the terminal or product manual test function and main parameters.
In short, the terminal “shelf life” is very long, but the effective storage period is not long, in the temperature, humidity control is good, life up to 3 years, if the environment is bad, the terminal life of only one and a half years or even shorter, acid and alkaline environment on the terminal damage is very big, so we should regularly product testing, found aging phenomenon immediately replace the terminal connector.