What are the manifestations of automobile parts failure? Component failure detection center

Date：2022-06-02 15:53:45Views：994

Electronic components are the basic elements of electronic circuits. Electronic components must be connected with each other to form an electronic circuit with specific functions. Wires, harnesses, fuses, connectors, various switches and relays are all basic components of automobile circuits, and they are also basic components of automobile circuits. Failure analysis of automobile parts is to study the causes, characteristics and laws of automobile parts losing their specified functions; The failure analysis and prevention techniques are studied to analyze the causes of component failure; The improvement and preventive measures are put forward to improve the reliability and service life of the automobile.

Main failure modes of automotive electronic components

1. Element breakdown

Breakdown includes over-voltage breakdown or over-current, thermal breakdown caused by overheating, etc; Sometimes the breakdown is in the form of short circuit and sometimes in the form of open circuit; The over-voltage and over-current breakdown caused by circuit fault is often unrecoverable.

2. Component aging or performance degradation

This includes many aspects, such as the capacity of the capacitor decreases, the insulation resistance decreases, the leakage of the transistor increases, the resistance value of the resistance changes, the resistance value of the adjustable resistance cannot change continuously, the relay contact is ablated, etc; Components such as relays often fail to adjust the initial operating current due to insulation aging, coil burnout, inter turn short circuit, contact jitter.

3. Line fault

Such faults include poor insulation, short circuit, bypass, etc. caused by loose wiring, poor contact, humidity, corrosion, etc; Such faults are generally independent of components.

Damage causes of automobile electronic components

1. Power supply problem

The operation of the automobile circuit board requires a suitable voltage range. When the voltage exceeds or falls below the voltage, the circuit is in an unstable working state, especially when the voltage is over-voltage, the circuit is more likely to be damaged. For example, the aluminum electrolytic capacitor with a rated 22uf/63v may explode instantly at a high voltage of 300V. Power supply is the most important problem. Some circuit boards do not add any protection at the power supply end for cost reasons, which is very easy to burn the circuit board and its connected front and rear circuits.

2. Load problem

The load corresponding to the "source" is the load. The load carrying capacity is an important indicator of the circuit performance in the circuit. After the circuit board is designed and debugged, its load carrying capacity has been fixed in a reasonable range. The circuit is easy to be damaged under no-load and overload operation. For example, the common short circuit is equivalent to overload.

3. Component problems

Electronic components have a failure rate and service life. Generally, one failure is allowed for every 100000 components. In this way, the failure efficiency of a circuit board with hundreds of components may reach one thousandth or even one percent. Moreover, the change of power supply and load also has a great impact on the service life of components. Long-term abnormal use intensifies the aging of components and shortens the service life, which is very easy to cause circuit board failure and burn out in serious cases.

In addition to the above three general reasons, long-term abnormal use is also easy to cause circuit board burnout. Such abnormal use can be in abnormal physical environment (temperature, humidity, etc.), abnormal electromagnetic environment (near large radiation electrical appliances), etc.

Common failure detection and analysis technology of automobile parts

1. Metallographic examination technology

Metallographic analysis technology is the most important method in failure analysis, which is mainly divided into the following aspects:

Macrostructure defect evaluation

Forging flow line inspection

Analysis Sample

Whether the microstructure meets the standard / expected requirements

Rating of non-metallic inclusions

Determination of grain size

Decarburization layer detection

Carburized layer detection

Judge crack type

Determine crack growth mode

2. Non destructive testing

The traditional radiographic testing (RT), radiographic digital imaging testing (DR) and computer tomography (CT) technology are used for nondestructive testing. Under the condition of no damage to the tested object, the internal structure, composition, material and defect of the tested object are clearly, accurately and visually displayed in the form of plane superimposed projection or two-dimensional sectional image. The application of radiographic testing technology in defect characterization mainly includes the following five aspects:

(1) Identification of defects

(2) Defect size measurement

(3) 3D reconstruction and defect extraction (3D reconstruction of internal defects of materials to characterize the shape and distribution of defects)

(4) Internal structure analysis without disassembly

(5) Assembly analysis without disassembly

3. Chemical composition analysis

The chemical composition analysis of materials is mainly used to check whether the design and material selection are improper, and whether there is a problem that the inferior is superior or the false is confused with the true.

4. Mechanical properties

Why do I have to do mechanical property test?

According to the purpose, requirements and possibility of failure analysis, the hardness, tensile at room temperature, impact, bending, flattening, fatigue and mechanical properties at high temperature shall be measured (without damaging the main failure characteristics);

Evaluate whether the process and material of the failed parts meet the requirements;

The critical value of material resistance to deformation or fracture is obtained.

Common reasons for unqualified mechanical properties:

Improper heat treatment process;

Improper sampling position or sampling method;

Serious material segregation.

5. Fracture analysis technique

Through fracture morphology analysis, some basic problems of fracture can be studied, such as fracture cause, fracture property, fracture mode, fracture mechanism, fracture toughness, stress state of fracture process and crack growth rate. Therefore, fracture analysis has become an important means for failure analysis of metal components.

The above contents are related to the failure analysis of auto parts compiled by the core detection team. I hope they can help you. Chuangxin testing is a professional testing organization for electronic components. At present, it mainly provides testing services for integrated circuits such as capacitors, resistors, connectors, MCU, CPLD, FPGA, DSP, etc. Specialized in functional testing of electronic components, incoming appearance testing of electronic components, anatomical testing of electronic components, acetone testing, X-ray scanning testing of electronic components, and RoHS component analysis testing. Welcome to call, we will serve you wholeheartedly!