The filtering of components is divided into two types: "first filtering" and "secondary screening". Before the delivery of the component, the filter of the product specifications (general specifications, detailed specifications) of the component before delivery is called "one screening". After the purchase, the use party is called "secondary screening" according to the requirements of the use requirements.
At present, the production level of domestic meta -devices is more or less different from the requirements of the development of products. The screening project and stress requirements of the screening of the manufacturer may not necessarily meet the needs of product development.
There are not many real "military standards" products in imported components, most of which are still low -end products, and there may be many counterfeit products.
The development of products is often very targeted, and components that exist in some failure models must be strictly removed, otherwise they cannot guarantee that the product is reliable to work. These all 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 the reliability guarantee of the product.
Several issues that should be paid attention to when second screening:
1. 100%secondary screening should be implemented for the components used in the development of the model, so as to maximize the elimination of components with a certain failure mode.
2. Selective screening for the purpose of the product. For example: the assessment of anti -amplitude ability is a special case. It must be considered for the Aerospace Electronics equipment, and the ground electronic equipment is basically not considered.
3. For components that cannot be screened due to means, other control methods must be taken to ensure its quality. For example, some tests were performed on the circuit used or tried to entrust other units.
4. Considering the limitations of secondary screening, it is necessary to strictly control its batch percentage percentage (PDA).
Universal project for secondary screening:
Temperature cycle: Check the structural defect
Constant temperature acceleration: check the internal lead
Granules collision noise detection: Check whether there are impurities
Electric Refining: Check the early failure of the inspection
High and low temperature test: check parameter drift
Junior temperature and final test: Check whether the product is qualified
Discovery: Check the leakage or not
Visual inspection
Dead physical analysis of components (DPA)
Dead physical analysis (DPA) technology is the need for engineering and develops to ensure the high reliability requirements of components. It can reflect some defects that cannot be found during the second screening of the component.
In a large amount of data statistics, it shows that the proportion of unqualified unqualified items such as external visits, PIND and leakage can be screened at 36.9%. The equal proportion reaches 63.1%.
General principles of DPA:
1. The components selected for important models or general models need to be used as DPA;
2. The level of the device is lower than the component of the model requirements;
3. Components that fail to retrieve the screening according to the model requirements;
4. The same batch of device in the experiment;
5. Equipment that exceeds the storage period, you must choose the project reasonably when doing DPA tests, and select the DPA laboratory certified by relevant departments.
Storage and storage of components
The storage and storage of components must meet the storage and storage conditions of its storage. In particular, electronic components such as moisture -proof, anti -corrosion, anti -aging, anti -static and other electronic components should be properly kept. The secondary classification is stored, and the warehouse should be significantly marked, orderly, safe and stable, reasonable storage, cleanliness, clean and humidity. And the electronic components with regular testing requirements during the inventory process were tested on a regular basis. It was found that unqualified products were isolated from the warehouse in time and recorded in the case.
Electricity and debugging of components
When the inherent reliability and reliability of the meta -device are a certain value, the reliability of the electricity process determines the reliability of electronic products. Therefore, we must pay attention to the reliability of electronic components to ensure the reliability of electronic components.
The component enters the production workshop, and the electricity is welded according to the drawings and process requirements. Electric installation process should be clearly given to the welding time of various components, welding temperature, and components on anti -static.
For example, the welding time of a CMOS integrated circuit is less than 4S and the welding temperature is less than 240 ° C. Welded in the electrostatic protection area. For some integrated circuits in order to replace convenience or should not be directly welded directly, the welding integrated circuit socket should be clearly clear. If there are heat dissipation requirements, the welding height should be clearly defined.
Electric workers in the production workshop should be trained and can complete the incidents of the component's random inspection. For example, whether the component is mixed, the logo is correct, whether the welding foot or pins are deformed, and whether the appearance is damaged.
Before power -on debugging the printing board, the direction of the component is mainly checked, and there are short circuits and virtual welding welding of the printed board welding. Whether the debugging process comes with power, pay special attention to electrostatic protection and debugging tools. Whether the debugging tool meets the anti -static requirements, directly affects the smooth electricity discharge pathway during the debugging process. Debugging the replacement device or finding problems, there should be detailed records, and notify the designer to find the reason.
For example: the use of a potentiometer with a deviation of 500Ω less than 10%, the critical critical quality of the batch quality is 461Ω, which is qualified. The predetermined function is difficult to adjust the power of the power. The designer analyzes the circuit according to the debugging record. Replace it to improve the reliability of components.
Effective analysis of components
Failure analysis is an important way to find problems and solve problems. When the product test, system joint adjustment, etc., when the component is found to be invalid, for a component of typical failure or batch quality problems, the component quality control department shall organize relevant technical personnel to organize relevant technical personnel Together with the quality control personnel, the failure analysis, clarify the failure mechanism, and find out the cause of the failure;
Key, important components failure, repeated components that are unknown for repeated causes and unknown reasons, and components with unknown or low quality grades should be used as a focus, which can be carried out by a professional failure analysis laboratory. Through trial sales analysis, design can be improved, the management of key procedures can be strengthened, and the reliability of the product can be continuously improved;
At the same time, the business technology level of design, manufacturing and related personnel has also been improved. If the failure analysis is confirmed to be a batch properties, it shall be issued notified and warning within the scope of this development model to avoid re -occurrence of similar situations.
Establish component quality database
Establishing component quality databases can comprehensively reflect the quality status of the components. From this we can see that the manufacturer's production level and process level are available. The selected components selected by model development can provide corresponding quality data and provide a basis for some decisions.
Based on this, the supplier can also be adjusted, and it is optional to entrust specific manufacturers to carry out new components to develop and put forward suggestions for funding for technical reform to further ensure the quality and reliability of components. The model development unit shall establish information from the selection, ordering, producer acceptance, secondary screening, DPA, storage and failure analysis of component devices. Information library.
The database should be established by the quality inspection department, cooperation such as procurement, testing and development, and providing corresponding data. The quality department uses a computer to statistics and analysis of the database, and then feeds the results to the procurement, testing and research departments. Based on this, the procurement, test, and adoption of components are adjusted to improve the reliability of components.
In order to improve the reliability of electronic components, it is necessary to do a good job of designing, testing, testing, screening, storage and storage, and electricity in the design, selecting, testing, screening, storing storage, and electricity of the meta -device; it will provide a solid foundation for improving the reliability of electronic products.
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