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Electronic components (hereinafter referred to as components) is an important part of electronic products and the most basic unit of electronic products. The reliability of components is directly related to the reliability of the whole system. Therefore, the reliability of components is one of the important links to ensure the reliability of products in the process of model development. at the same time, it is also of great significance to speed up the progress of model development, ensure development quality, save development funds, and reduce comprehensive support costs and life cycle costs.
 
Secondary screening of components.
 
The screening of components can be divided into two categories: "primary screening" and "secondary screening". The screening of components according to the product specifications (general specifications, detailed specifications) of components before delivery to users is called "one-time screening". The re-screening carried out by the user according to the use requirements after the purchase is called "secondary screening".
 
At present, the production level of domestic components is more or less different from the requirements of developed products, and the screening items and stress requirements carried out by manufacturers may not necessarily meet the needs of product development.

There are not many real "military standard" products in imported components, and most of them are medium-and low-grade products, among which there may be many fake and shoddy products.
 
However, the developed products are often highly targeted, and the components with a certain failure mode must be strictly eliminated, otherwise the product can not be guaranteed to work reliably. All these require us to ensure the quality of components through secondary screening. The secondary screening of components is one of the important measures in the quality control of components, which is of great significance to ensure the reliability of products.
 
Several problems that should be paid attention to in the secondary screening:
 
1.100% secondary screening should be carried out for the components used in the model development, so that the components with a certain failure mode can be eliminated to the maximum extent.

2. Selective screening is carried out according to the use of the product. For example, the assessment of the ability to resist photo exposure is a special case. Aerospace electronic equipment must be considered, while ground electronic equipment can basically not be considered.
 
3. Other control methods should be adopted to ensure the quality of the components which can not be screened due to the problem of means. For example, some experiments have been carried out on the circuits used or entrusted to other units to carry out tests, and so on.

4. Considering the limitation of secondary screening, its batch allowable failure percentage (PDA) must be strictly controlled.
General items for secondary screening:

Temperature cycle: check for structural defects.
Constant temperature acceleration: check inner lead.
Particle collision noise detection: check for impurities.
Electric aging: check for early failure.
High and low temperature test: check parameter drift.
Initial and final test at room temperature: check whether the product is qualified or not.
Leak detection: check for air leakage.
Visual inspection of appearance.

Destructive physical Analysis of components (DPA).

Destructive physical analysis ((DPA)) technology is developed to meet the needs of engineering and to ensure the high reliability of components. It can reflect some defects that can not be found in the process of secondary screening of components.
A large number of data statistics show that the proportion of nonconforming items that can be eliminated through screening, such as external visual inspection, PIND and leak detection, is 36.9%, while the proportion of defects that cannot be eliminated by screening into internal visual inspection, shear force, bonding force, etc., reaches 63.1%, which shows the large number of defects that cannot be put forward by screening.

Develop the general principles of DPA:

1. The components selected by important models or general models of important electronic products should be used as DPA;.
2. The grade of the device is lower than that of the components required by the model.
3. Failed to retrograde the selected components according to the requirements of the model;
4. The same batch of components that have broken down in the test;
5. For the components beyond the storage period, it is necessary to reasonably select the items and select the DPA laboratory certified by the relevant departments when doing the DPA test.

Storage and storage of components.

The storage and storage of components must comply with the prescribed storage conditions, especially for electronic components such as moistureproof, anticorrosive, anti-aging, anti-static and other electronic components. Different varieties and batches should be classified in the warehouse, marked clearly, arranged orderly, safe and safe, reasonable, neat, and recorded in temperature and humidity. And carry out regular quality inspection of the electronic components with regular testing requirements in the process of storage, and find that the unqualified products are isolated from the warehouse in time and recorded.

Electrical installation and debugging of components.

When the inherent reliability and operational reliability of the components are at a certain value, the reliability of the Denso process determines the reliability of electronic products. Therefore, we must pay attention to the electrical reliability of electronic components in order to ensure the reliability of electronic components.

The components enter the production workshop and carry out electrical assembly welding according to the drawings and process requirements. The welding time, welding temperature and anti-static requirements of various components should be clearly given in the electrical assembly process.

If the welding time of a CMOS integrated circuit is less than 4s and the welding temperature is less than 240C, it should be welded in the electrostatic protection area. For some integrated circuits, it is convenient to replace or not suitable for direct welding, the integrated circuit sockets should be welded first, and the welding height should be specified if there is a requirement for heat dissipation.

The Denso workers in the production workshop should be trained to complete the outstanding matters in the sampling inspection of components, such as whether the components are mixed, whether the identification is correct, whether the welding pins or pins are deformed, whether the appearance is damaged, etc.

Before power-on debugging the printed board, mainly check the direction of the components, and whether the PCB welding has short circuit, virtual welding and so on. Whether the debugging process is live or not, special attention should be paid to electrostatic protection and debugging tools. Whether the debugging tools meet the requirements of anti-static directly affects the smooth electrostatic discharge path of electrostatic sensitive devices in the debugging process. Debugging and replacing components or finding problems should be recorded in detail and notify the designer to find out the cause.

For example: the potentiometer with a deviation of less than 10% is used, the critical batch quality is 461 Ω, and the scheduled function is found to be difficult to adjust. The designer analyzes the circuit according to the debugging record, and the specific parameters of which components are not suitable will be replaced to improve the reliability of the components.

Failure analysis of components.
 
Failure analysis is an important way to find and solve problems. When component failures are found in the process of product testing and system joint adjustment, for components with typical failures or batch quality problems, the component quality control department should organize relevant technicians and quality control personnel to carry out failure analysis, clarify the failure mechanism and find out the cause of failure.
 
Critical and important component failures, components with unknown causes of repeated failures, and components with unknown or low quality grades should be taken as the focus and can be carried out by professional failure analysis laboratories. Through trial marketing analysis, the design can be improved, the management of key processes can be strengthened, and the reliability of products can be continuously improved.
 
At the same time, it also improves the business and technical level of designers, manufacturers and related personnel. If it is confirmed to be a batch quality problem after failure analysis, notification and warning should be issued at least within the scope of this development model, so as to avoid the recurrence of similar situations.
 
Establishment of component quality database
 
The establishment of the component quality database can comprehensively reflect the quality state of the components, from which we can see the production level and process level of the manufacturers, and provide the corresponding quality data for the selected components in the model development. to provide a basis for some decisions.
Accordingly, we can also adjust the suppliers, selectively entrust specific manufactu
rers to carry out the development of new components and put forward suggestions for subsidizing technical transformation, so as to further ensure the quality and reliability of the components. The model development unit should establish the information storage database from the whole process of component selection, ordering, production supervision and acceptance, secondary screening, DPA, storage and failure analysis, and establish an information base that can retrieve the information of components, including installed components and failed components.
The database should be established by the quality inspection department, cooperate with the purchasing, testing and development departments, and provide the corresponding data. The quality department uses the computer to count and analyze the database, and then feedback the results to the purchasing, testing and development departments, so as to adjust the purchase, test and adoption of components to improve the reliability of components.

In order to improve the reliability of electronic components, we must do a good job in the design and selection, inspection, testing, screening, storage and electrical equipment of electronic components, which will provide a solid foundation for improving the reliability of electronic products. According to the above discussion and the experience of some models, it can be seen that:
The main contents are as follows: 1. Compiling the optimal catalogue of model components is the cornerstone of the work of components, which must be paid full attention to.

2. Secondary screening must be carried out for installed components, and 100% of the key models are required for secondary screening.
3. Failure analysis and DPA are important means to find quality problems of components. In the long run, they greatly reduce the life cycle cost of equipment.