Failure analysis of electronic components in component testing

Date：2022-08-25 15:51:14Views：801

With the increasing demand for the quality and reliability of electronic products, the reliability of electronic components continues to attract people's attention. How to improve the reliability has become a hot issue in the manufacturing of electronic components. In order to help you understand deeply, this paper will summarize the relevant knowledge of electronic device failure analysis. If you are interested in what this article is about to cover, read on.

The purpose of reliability work is not only to understand and evaluate the reliability level of electronic components, but also to improve and improve the reliability of electronic components. Therefore, after the failed devices are obtained from the use site or reliability test, it is necessary to conduct various tests and Analysis on them, find and determine the causes of failure, feed back the analysis results to the design, manufacturing, management and other relevant departments, and take targeted and effective corrective measures to improve and improve the reliability of the devices. This kind of test analysis, the process of finding the failure cause or mechanism, is called failure analysis.

Failure analysis is the process of diagnosing the failure mechanism and cause of electronic components, which is the only way to improve the reliability of electronic components. Components from design to production to application may fail, so failure analysis runs through the entire life cycle of electronic components. Therefore, it is necessary to find out the cause of failure, determine the failure mode, and propose corrective measures to prevent the same failure mode and failure mechanism from recurring on each component and improve the reliability of the component.

In summary, the significance of failure analysis is as follows:

1. The theory and idea of improving design, process or application can be obtained through failure analysis.

2. By understanding the physical phenomena causing failure, the formula of predicting reliability model is obtained.

3. It provides theoretical basis and practical analysis means for reliability test conditions.

4. When dealing with the problems of components and parts encountered in the project, provide decision-making basis for whether to use the whole batch.

5. Through the implementation of corrective measures of failure analysis, the yield and reliability can be improved, and the failure during system test and operation can be reduced, and obvious economic benefits can be obtained.

Classification of failures

In actual use, the failure can be classified as required. According to the failure mode, it can be divided into open circuit, short circuit, no function, characteristic degradation (degradation) and retest qualified; According to the failure causes, it can be divided into misuse failure, essential failure, early failure, accidental failure, loss failure and natural failure; According to the degree of failure, it can be divided into complete failure and partial (local) failure; According to the combination of failure time characteristics and time characteristics, it can be divided into sudden failure, gradual failure, gap failure, stable failure, sudden failure, degradation failure and recoverable failure; According to the severity of failure consequences, it can be divided into fatal failure, serious failure and mild failure; According to the relevance and independence of failure, it can be divided into related failure, non related failure, independent failure and dependent failure; According to the failure occasion, it can be divided into test failure and on-site failure (on-site failure can be further divided into commissioning failure and operation failure); According to the external performance of failure, it can be divided into obvious failure and hidden failure.

failure mechanism

The failure of electronic components mainly occurs in the process of product manufacturing, testing, transportation, storage and use, and is closely related to raw materials, design, manufacturing and use. There are many kinds of electronic components, and the corresponding failure modes and mechanisms are also many. The failure mechanism is the essential reason for device failure, which explains how the device fails, that is, the physical and chemical process that causes device failure. However, the opposite is a series of macroscopic performance and property changes that it will show sooner or later, such as fatigue, corrosion and overstress.

The main failure mechanisms of electronic components include:

(1) Over stress (EOS): refers to that the current, voltage stress or power of the component exceeds its allowable maximum range.

(2) Electrostatic damage (ESD): during the processing, assembly, storage and transportation of electronic devices, they may come into contact with containers, test equipment and operators with static electricity, and the static electricity will be discharged to the ground through the device pins, resulting in damage or failure of the devices.

(3) Latch up: the MOS circuit presents a low resistance state due to the presence of parasitic pnpn transistors. This low resistance state will still exist after the trigger condition is removed or terminated

(4) Electromigration (EM): when the device is working, there is a certain current in the metal interconnection line, and the metal ions will produce mass transport along the conductor. As a result, voids or whiskers will appear in some parts of the conductor.

(5) Hot carrier effect (HC): hot carriers refer to carriers whose energy is several KT higher than Fermi level. These carriers are not in thermal equilibrium with the lattice. When their energy reaches or exceeds the Si-SiO2 interface potential barrier (3.2eV for electron injection and 4.5ev for hole injection), they will be injected into the oxide layer, resulting in the interface state, oxide layer traps or trapped by traps, causing the oxide layer charge to increase or fluctuate unsteadily. This is the hot carrier effect.

(6) Gate oxygen breakdown: in MOS devices and circuits, defects in the gate oxide layer will lead to gate oxygen leakage, and when the leakage increases to a certain extent, it constitutes breakdown.

(7) Time dependent dielectric breakdown (TDDB): the applied electric field is lower than the intrinsic breakdown strength of gate oxygen, but the breakdown phenomenon still occurs after a certain time. This is because defects are generated and accumulated in the oxide layer during the stress application.

(8) Due to the different chemical potentials between gold and aluminum, a variety of intermetallic compounds, such as purple spots and white spots, will be produced after long-term use or high-temperature storage above 200 ℃. The aluminum layer becomes thin, the contact resistance increases, and finally an open circuit is caused. At a high temperature of 300 ℃, there will also be voids, i.e. Kirkendall effect, which is the rapid diffusion of gold into aluminum at high temperature and the formation of compounds, and the annular space around the bonding point. The aluminum film is partially or completely separated to form a high resistance or an open circuit.

(9) "Popcorn effect": the water vapor in the plastic packaging material of the plastic packaging components expands under high temperature, causing delamination effect between the plastic packaging material and the metal frame and the chip, breaking the bonding wire, thus causing open circuit failure.

Failure analysis technology

Failure analysis technology is the means and method used in failure analysis theory, which mainly includes six aspects: failure location technology; Sample preparation technology; Microanalysis technology; Stress verification technology; Electronic analysis technology; Composition analysis technology.

1. Failure location technology

The main purpose of the failure location technology is to determine the failure location of the detection target. With the complexity of modern integrated circuits and electronic components, the failure location technology is particularly important. There are many methods for failure location technology, among which X-ray and Sam can be used for non-destructive testing without opening. X-ray can be used to observe the internal structure of components and multilayer printed circuit boards, open or short circuit of internal leads, bonding defects, solder joint defects, packaging cracks, cavities, bridges, monuments and device missing. Sam can observe internal cracks, delamination defects, cavities, bubbles, voids, etc. If X-ray and Sam cannot detect the failure part, the components need to be unpacked, and then other methods can be used to locate the failure, such as microscopic inspection.

2. Sample preparation technology

To solve most of the failure analysis, anatomical analysis technology is required, i.e. cross-sectional analysis of the sample, which does not damage the observation and test parts. The sample preparation steps generally include opening the package, removing the passivation layer, and removing the interlayer medium for the multilayer structure chip. Mechanical or chemical methods can be used to open the package. The passivation layer can be removed by chemical etching or plasma etching (such as ICP, RIE), or fib.

3. Microanalysis Technology

The analysis of failure causes, the determination of failure mechanism and the failure location mentioned above all need to use microscopic analysis technology. Various microscopes are generally used for microscopic analysis, and they have their own advantages and disadvantages, such as stereoscopic microscope with large depth of view and strong stereoscopic imaging sense; Metallographic microscope with good plane imaging effect and prominent color; SEM with high magnification (up to several hundred thousand times); The sample preparation requires a high tem for observing the lattice structure; Infrared microscope with low imaging accuracy but easy operation; For the optical radiation microscope with high imaging accuracy, the equipment and method shall be selected according to the actual situation.

4. Stress verification technology

There are differences in the reliability of electronic components in different environments, such as the stress generated under different humidity and temperature, the electrical stress generated under different current and voltage, etc., which will lead to changes in the performance of electronic components or failure. Therefore, various environmental parameters can be simulated to verify the reliability of components under various stresses.

5. Electronic analysis technology

There are many methods of failure analysis using electronic, such as EBT, EPMA, SEM, TEM, AES, etc.

6. Composition analysis technology

It is necessary to determine the composition and composition of a part of the components, that is, the composition analysis technology is required to determine whether there is pollution or whether the composition is correct, which affects the performance of the components. Common equipment includes EDS, EDAX, AES, Sims, etc.

The above is related to the failure analysis of electronic devices compiled by the Chuangxin testing team. I hope it will be helpful to you. Our company has professional engineers and industry elite teams, and has three standardized laboratories with an area of more than 1800 square meters. It can undertake various test projects such as electronic component testing and verification, IC authenticity identification, product design and material selection, failure analysis, functional testing, factory incoming material inspection and tape weaving.