What is the purpose of component screening? What are the screening methods?

Date：2021-08-02 17:00:00Views：1528

Components shall be screened according to relevant screening technical conditions and can be used only after passing the screening. In order to prevent false welding caused by oxidation at the welding end after screening of chip components, it is forbidden to screen chip components without weldability treatment conditions at the welding end. Components are the basis of the whole machine. The inherent reliability of electronic components depends on the reliability design of the product. In the manufacturing process, it may form time or stress-related failure in use due to its inherent defects or improper control of manufacturing process. In order to ensure the reliability of the whole batch of components, we should try to eliminate the components with early failure as much as possible before the electronic components are installed on the whole machine and equipment. Therefore, we should screen the components.

The inherent reliability of electronic components depends on the reliability design of products. In the manufacturing process of products, due to human factors or fluctuations in raw materials, process conditions and equipment conditions, the final finished products cannot all achieve the expected inherent reliability. In each batch of finished products, there are always some potential defects and weaknesses in some products. These potential defects and weaknesses show early failure under certain stress conditions. The average life of components with early failure is much shorter than that of normal products. Therefore, the screening of components is very important and necessary.

According to the screening experience at home and abroad, the total service failure rate of components can be reduced by 1-2 orders of magnitude through effective screening. Therefore, screening is an important means to ensure reliability, whether military products or civil products. For military products, screening is more important. According to national requirements, each component in each batch of military products should be tested through screening test to find and eliminate defects and hidden dangers in manufacturing, technology and materials, so as to ensure the reliability of components.

Screening method of components:

Under the condition that the surface assembled components meet the above screening principles, they can be screened in one of the following ways according to the actual situation.

Component level screening: refers to the 100% component level screening conducted by the user.

Entrusted screening: entrust the original manufacturer of surface assembled components or the unit that meets the product screening and testing conditions and obtains the consent of the product user to screen according to the product use conditions.

Sampling screening: the user shall conduct sampling screening according to the product use conditions, and the proportion of sampling screening shall be 5% ~ 10% of the assembly quantity

Board level screening: the user shall conduct board level screening after the printed circuit board assembly inspection is qualified according to the product service conditions.

Necessity of component screening:

Two schemes for prioritizing test screening

Scheme 1: put the failure mode screening that does not produce chain initiation effect in the front, and put the failure mode screening that can produce chain initiation effect with other failure modes in the back.

Scheme 2: put the screening of failure modes that can produce chain initiation effect with other failure modes in the front, and the screening of failure modes that do not produce chain initiation effect in the back.

If scheme 1 is selected, it will be found that the screening of failure modes that can produce chain triggering effect with other failure modes is put behind. If the failure mode itself is not triggered, but other related failure modes are triggered first, because the detection of such failure modes has been done earlier, Therefore, it is impossible to accurately locate and eliminate such defective components. Option 2 can effectively avoid the above problems and make the screening process more high-quality, economic and efficient.

The above is "what is the purpose of component screening? What are the screening methods?" If you have any requirements related to component inspection and testing, please call Chuangxin testing, and we will serve you wholeheartedly!