How to control the reliability of electronic components during the manufacturing process

Electronic components (hereinafter referred to as components) are 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 entire system.

Therefore, the reliability of components is one of the important links to ensure product reliability during the model development process. It is also important for accelerating model development progress, ensuring development quality, saving development costs, reducing comprehensive support costs and life cycle costs. .

Secondary screening of components

The screening of components is divided into two categories: “one-time screening” and “secondary screening”. The screening of components in accordance with the product specifications (general specifications, detailed specifications) of the components before delivery to the user is referred to as "one-time screening." The re-screening by the user after the purchase according to the usage requirements is called "secondary screening".

At present, the production level of domestic components is generally more or less different than the requirements for the use of developed products. The screening project and stress requirements of the manufacturer may not meet the needs of product development.

There are not many genuine “military” products in imported components, most of them are medium and low-end products, and there may be many counterfeit and shoddy products.

The products developed are often highly targeted, and components that have a certain failure mode must be strictly excluded. Otherwise, the products cannot be reliably operated. 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 the reliability assurance of products.

Several issues to be aware of during secondary screening:

1. The components used in the model development should be subjected to 100% secondary screening, so as to minimize the presence of components with certain failure modes.

2. Selective screening for the use of the product. For example, the assessment of resistance to radiation is a special case. For aerospace electronic equipment, it must be considered, and ground electronic equipment can basically be ignored.

3. For components that cannot be screened due to instrumental problems, other control methods must be adopted to ensure their quality. For example, some tests are performed on the circuit used or other units are commissioned for testing.

4. Considering the limitations of secondary screening, its batch allowable failure percentage (PDA) must be strictly controlled.

General project for secondary screening:

Temperature cycling: checking structural defects

Constant temperature acceleration: check the inner lead

Particle collision noise detection: check for impurities

Electric aging: checking early failure

High and low temperature test: check parameter drift

Normal temperature initial test and final test: check whether the product is qualified

Leak detection: check for leaks or not

Visual inspection

Destructive physical analysis of components (DPA)

Destructive physical analysis (DPA) technology is developed to meet the engineering needs and to ensure the high reliability requirements of components. It can reflect some defects that are impossible to find in the secondary screening process of components.

A large number of data statistics show that the proportion of non-conforming products that can be eliminated through screening, such as external visual inspection, PIND and leak detection, is 36.9%, and the defects that cannot be removed by screening are entered into internal visual inspection, shear force and bonding force. The proportion reached 63.1%, which shows that the number that could not be submitted through screening can be seen.

Carry out the general principles of DPA:

1. The components selected for important electronic products of important models or general models shall be DPA;

2. The level of the device is lower than the components required by the model;

3. Failure to retrograde the components that can be screened according to the model requirements;

4. The same batch of components that have failed during the test;

5. For components exceeding the storage period, it is necessary to select the project reasonably and select the DPA laboratory to be certified by the relevant department when doing DPA test.

Storage and storage of components

The storage and storage of components must meet the storage and storage conditions specified by them. In particular, electronic components that require moisture, corrosion, anti-aging, anti-static, etc. should be properly kept. The storage of components should be stored in different types and batches. Sub-category storage, the warehouse should be marked, orderly, safe and secure, reasonable storage, clean warehouse, temperature and humidity records. During the inventory release process, the electronic components with regular testing requirements were subjected to regular quality inspection, and the non-conforming products were found to be isolated and released in time and recorded.

Electrical installation and commissioning of components

When the inherent reliability and reliability of the components are constant, the reliability of the electrical assembly process determines the reliability of the electronic product. Therefore, we must pay attention to the electrical reliability of electronic components to ensure the reliability of the use of electronic components.

The components enter the production workshop and are electrically assembled according to the drawings and process requirements. The electrical assembly process shall clearly indicate the soldering time of various components, the soldering temperature and the antistatic requirements of the components.

If the welding time of a CMOS integrated circuit is less than 4s and the soldering temperature is less than 240 °C, it should be soldered in the static protection zone. For some integrated circuits, it is convenient to replace or not to be directly soldered. It is necessary to first solder the integrated circuit socket first. If there is heat dissipation requirement, the welding height should be specified.

The electrician in the production workshop should be trained to complete the unfinished matters in the sampling of the components, such as whether the components are mixed, whether the marking is correct, whether the soldering pins or pins are deformed, and whether the appearance is damaged or not.

Before commissioning the printed circuit board, check the component direction and the short circuit or solder joint of the printed circuit board. If the debugging process is live, pay special attention to the static protection and debugging tools. Whether the debugging tool meets the anti-static requirements directly affects the smoothness of the electrostatic discharge path of the electrostatic sensitive device during the debugging process. Debugging replacement components or finding problems should be documented in detail and notified to the designer to find the cause.

For example: use a potentiometer with a 500Ω deviation of no more than 10%, the batch quality is critically 461Ω, and the qualification is judged. The electrical installation debugging finds that the predetermined function is difficult to adjust. The designer analyzes the circuit according to the debugging record, and the specific component parameters are not suitable. Replace it to improve the reliability of the components.

Component failure analysis

Failure analysis is an important way to find problems and solve problems. When components are found to be ineffective in product testing, system debugging, etc., for components with typical failure or batch quality problems, the component quality control department should organize relevant technical personnel. Perform failure analysis together with quality control personnel to clarify the failure mechanism and identify the cause of failure;

Key and important component failures, repeated failures of unexplained components, and selected components of unknown or low quality grades should be the focus of a professional failure analysis laboratory. Through trial sales 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 technical level of design, manufacturing and related personnel. If the batch quality problem is confirmed after the failure analysis, at least the notification and warning should be issued within the scope of the developed model to avoid the recurrence of similar situations.

Establish component quality database

The establishment of the component quality database can comprehensively reflect the quality status of the components. From this, we can see the manufacturer's production level and process level, and provide the corresponding quality data for the selected components of the model development, which will provide a basis for some decisions.

According to this, it is also possible to adjust the supplier, selectively commission a specific manufacturer to carry out the development of new components and propose financial support, thus further ensuring the quality and reliability of the components. The model development unit shall establish information storage information library from the selection, ordering, supervision and acceptance, secondary screening, DPA, storage and failure analysis of components, and establish information to retrieve components including installed components and failed components. Information library.

The database should be established by the quality inspection department, and the procurement, testing and development departments should cooperate and provide corresponding data. The quality department uses the computer to perform statistics and analysis on the database, and then feeds the results back to the procurement, testing and development departments, and adjusts the procurement, testing and adoption of components to improve the reliability of components.

In order to improve the reliability of the use of electronic components, it is necessary to do the design selection, inspection, testing, screening, storage and storage, and electrical installation of components; it will provide a solid foundation for improving the reliability of electronic products. According to the above discussion and the experience of some models developed:

1. The catalogue of selected components and components is the cornerstone for the work of components, and must be given full attention.

2. The secondary screening is required for the installed components, and the key model requires 100% for secondary screening.

3. Failure analysis and DPA are important means to find component quality problems. In the long run, they greatly reduce the life cycle cost of equipment.