What are the stages of product failure? IC chip third-party detection mechanism

Date：2022-04-21 14:06:13Views：973

Failure analysis is a new developing subject, which has been popularized from military industry to ordinary enterprises in recent years. It is generally based on the failure mode and phenomenon, through analysis and verification, simulate and reproduce the failure phenomenon, find out the cause of failure, and dig out the failure mechanism. It has strong practical significance in improving product quality, technology development and improvement, product repair and arbitration of failure accidents. The methods are divided into destructive analysis, nondestructive analysis, physical analysis, chemical analysis and so on. The reason for the high early failure rate is that there are unqualified parts in the product; The reason for the high late failure rate is that the product components enter the failure period after long-term use. The running in of mechanical products and the aging screening of electronic components are the measures to ensure reliability according to this failure law.

1. Identify failure issues

In order to improve the efficiency of failure analysis, it is best to locate the problem to the specific network as much as possible before submitting the analysis application. In the process of fault location, try to avoid damaging the fault phenomenon and maintain the original morphology. Generally, it is not allowed to re weld the fault part. Carefully use heating, pressurization, power on impact and other means, otherwise it will affect the subsequent failure analysis.

2. Background information investigation of failed samples

This part of work is a key part of failure analysis. The information investigation should be detailed and comprehensive, obtain first-hand information as much as possible, and conduct appropriate verification with the production personnel when necessary to ensure the reliability of the information. It mainly includes the following contents: the failure stage of the failed sample: SMT stage, testing stage, assembly stage, etc; The specific test stations of the failed samples are as follows, which can be appropriately deleted according to the actual situation of the failed samples:

1. Batch information of single board invalidation: barcode information, production batch and delivery contract number;

2. Failure rate, including historical failure rate, recent failure rate (or batch failure rate);

3. PCB related information (surface treatment, manufacturer, batch, etc.);

4. Relevant device information (tag number, device code, model, manufacturer and batch, packaging form, electrode composition at welding end, coating composition, etc.), and the service failure rate of the device on other products or veneers;

5. Failure of similar products (with similar characteristics: the same production, testing and operation environment, similar board complexity);

6. Experience before failure;

7. Processing route, heating process, repair and maintenance times of failed veneers;

8. Transportation and storage environment, process and relevant information of veneer;

9. Operation environment of veneer, such as temperature, humidity, dust, salt fog, climate, vibration, routine operation, etc., as well as the surrounding environment of the station and important pollution sources;

10. Functional test results;

3. Fault recurrence and fault location

For the fault phenomenon described by the applicant, use multimeter and other tools to reproduce the fault as much as possible. Be moderately skeptical about the positioning results of production line personnel. For fault location, the method of appearance observation shall be preferred, and then electrical measurement shall be carried out. During fault recurrence and location, try not to take the fault location as a direct measurement point to avoid applying excessive mechanical and electrical stress to the fault location. If the appearance may be damaged during fault recurrence and location, appearance observation and photography shall be carried out first.

4. Nondestructive analysis

1. Appearance analysis

Visually or with the help of magnifying glass, metallographic microscope, stereo microscope and other tools, observe the appearance characteristics of the failed sample, including but not limited to the size of the single board, deformation, characteristics of relevant components or structural parts, fault distribution, color change of fault location, impurity residue, fracture characteristics, appearance of solder joints, etc. Tip: appearance inspection is very important for failure analysis. The observation should be careful and comprehensive, and it is not easy to let go of any doubts.

2.X-ray

It is mainly aimed at the samples whose failure position cannot be directly observed. It is used for the obvious abnormalities of metal materials, silicon wafer and ceramic body. It has good analysis ability for the tin connection, less tin, cold welding, cavity, abnormal shape of solder ball of BGA, thin coating on the hole wall of PCB, hole break, wire break and short circuit. Tip: Although X-ray has limited ability to pick up BGA open welding caused by common reasons, as a routine inspection method, X-ray may provide useful information and cannot be easily abandoned.

3.C-SAM

It mainly analyzes internal defects such as material delamination and cavity, which are commonly used in popcorn failure of moisture sensitive devices, delamination of ceramic components and PCB, etc.

4.3d measuring instrument

It is used to measure coplanarity and precision size. It is often used to obtain the warpage information of PCB or components and the size information of shell.

Note: in the process of damage analysis, pay attention to keep the picture evidence. Even if no abnormality is observed at that time, keep the complete picture for re-examination in the later analysis.

5. Assumptions about possible causes of failure

Analyze the collected data, conduct reasonable logical reasoning in combination with the results of nondestructive analysis, and preliminarily determine the possible failure mechanism and cause. When reasoning, we should have a broad mind. We can make bold assumptions according to the existing evidence, and do not let go of all possibilities. Then we can analyze which evidence supports the hypothesis and which are contrary. In order to support the hypothesis, we need to obtain what evidence, and distinguish the primary and secondary possible failure mechanisms and causes.

6. Analysis and verification

This part is an important part of failure analysis, which is often the place with the largest workload. This process carries out targeted analysis and verification according to the hypothetical failure mechanism. Destructive analysis means are often used to carry out component analysis and micro analysis as needed. The general principles are:

Multiple suspicious factors can be analyzed in parallel. If not, analyze the main factors of key suspicion first, and then the secondary factors.

Try to keep the information of failed samples intact. If the primary factor is not easy to verify, and the original failure sample information may be destroyed in the verification process, while the secondary factor is easy to verify and will not destroy the original failure sample information, the secondary factor can be verified first, and then the primary factor can be verified. The analysis and verification methods generally include the following contents:

Dyeing pull-out: it is a test method to quickly determine the failure position (for cases where the failure position cannot be observed directly). Generally, fracture morphology analysis and composition analysis can be carried out after pulling out.

Slice analysis: it is one of the most commonly used microscopic analysis methods. A lot of failure information is obtained, including coating structure, section position, solder joint shape, metallographic structure and its micro characteristics.

High magnification microscopic analysis and composition analysis.

Bold assumptions and careful verification should be made during analysis and verification. The verification process must be cautious and the evidence is conclusive.

7. Give the failure reason and failure mechanism

According to the information obtained from non-destructive analysis and destructive analysis, conduct comprehensive analysis to obtain the failure mechanism, clarify the failure cause according to the failure mechanism, and confirm that the problem is caused by materials, design, manufacturing or environment.

8. Reproduction test

The purpose is to verify the accuracy of the failure analysis conclusion, which can be omitted according to the specific situation.

9. Improvement measures

1. Specific improvement measures are given according to the failure mechanism and failure causes.

2. The improvement measures should be specific and operable;

3. For production problems, it is suggested to give temporary solutions and fundamental solutions (short-term and long-term);

10. Follow up

Track the product situation after the implementation of improvement measures and verify the correctness of the analysis conclusion. Generally, it can be set as half a year.

I believe that by reading the above content, we can have a deeper understanding of failure analysis. Failure analysis is of great significance to the production and use of products. Failure may occur at all stages of the product life cycle, involving product R & D and design, incoming material inspection, processing and assembly, test and screening, client use and other links. By analyzing the samples of process waste products, early failure, test failure, pilot failure and on-site failure, confirm the failure mode, analyze the failure mechanism and clarify the failure cause, Finally, preventive countermeasures are given to reduce or avoid the recurrence of failure.