Those who drive know that where is the best driving skill? No highway, only downtown and poor road conditions can improve the level. The development of society is a process of finding problems to solve problems. It is not terrible to see problems, but the frequent occurrence of the same type of problems is very terrible.
Failure Analysis Basic Concept
Definition: The diagnostic process for failed electronic components.
1. Failure analysis often requires electrical measurements and advanced physical, metallurgical, and chemical analysis methods.
2. The purpose of failure analysis is to determine the failure mode and failure mechanism, and to propose corrective measures to prevent the repetition of the failure mode and failure mechanism.
3, failure mode refers to the observed failure phenomena, failure modes, such as open circuit, short circuit, parameter drift, functional failure and so on.
4. The failure mechanism refers to the physical and chemical process of failure, such as fatigue, corrosion and overstress.
Failure Analysis General Procedures
1, collect field data
2, the electrical test and determine the failure mode
3, non-destructive inspection
4, open the package
5. Mirror examination
6, power and failure location
7. Physical and chemical analysis of the failure site to determine the failure mechanism.
8. Comprehensive analysis, determine the cause of failure, and propose corrective measures.
1. Collect site data:
2, the electrical test and determine the failure mode
Electrical test failure can be divided into connectivity failure, electrical parameter failure and function failure.
Connectivity failures include open circuits, short circuits, and changes in resistance. This type of failure is easily tested, and field failures are mostly caused by electrostatic discharge (ESD) and electrical stress (EOS).
Failure of electrical parameters requires more complex measurements. The main manifestations are parameter values ​​that are outside the specified range (exceeding tolerances) and parameter instability.
To confirm the failure of the function, input a known excitation signal to the component and measure the output result. If the measured output state is the same as the expected state, the component function is normal, otherwise it is a failure, and the functional test is mainly used in the integrated circuit.
The three failures have a certain correlation, that is, one failure may cause other types of failures. The root cause of functional failure and electrical parameter failure can often be attributed to connectivity failures. In the absence of complex functional test equipment and test procedures, it is possible to perform electrical measurements using simple connectivity tests and parametric test methods. Combined with the application of physical failure analysis techniques, satisfactory failure analysis results can still be obtained.
3, non-destructive inspection
X-Ray inspection is to use X-ray see-through components (multi-directions and angles are optional) to detect the encapsulation of components without damaging the chip, such as abnormality of air bubbles, bonding wires, grain size, and bracket orientation. Wait.
Applicable scenarios: Check whether the bonding is abnormal, the package has no defects, confirm the grain size and layout
Advantages: short duration, intuitive and easy analysis
Disadvantages: Limited access to information
limitation:
1, the same batch of devices, different encapsulation production line device internal shape is slightly different;
2. It is difficult to check the damage or defect of the internal circuit. It must be obtained through functional tests and other tests.
case analysis:
X-Ray Inspection - Bubble, Bonding Line
X-Ray authenticity identification - empty package bomb (can be seen in the figure, there is no grain)
"Specious"
This is the real thing
X-Ray used for analysis of origin (the same brand with the same model in the following figure)
X-Ray for Failure Analysis (PCB Inspection, Analysis)
(The following dense dot is the BGA's tin bead. As we can see in the figure below, this chip is actually a BGA secondary package)
4, open the package
There are two mechanical methods and chemical methods for unsealing. According to the packaging materials, the types of microelectronic devices include glass packages (diodes), metal shell packages, ceramic packages, and plastic packages. ??
Mechanical opening
Chemical Kaifeng
5, microscopic image technology
Optical Microscope Analysis Technology
Secondary electron image technology of scanning electron microscope
Voltage effect failure location technology
6, the main failure mechanism of semiconductor analysis
Electrical stress (EOD) damage
Electrostatic discharge (ESD) damage
Packaging failure
Wire bonding failure
Bad chip bonding
Metal semiconductor contact degradation
Sodium ion contamination failure
Oxide pinhole failure
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