Familiar skills of failure analysis and detection of electronic products

Date：2021-09-09 13:26:00Views：1135

Before failure analysis, it is necessary to narrow the scope of suspicion according to the failed products and their failure background, preliminarily judge the possible failure phenomena of products, select appropriate analysis technology and equipment, follow the principle of simplicity before complexity, from outside to inside, from face to point, from non-destructive to destructive, clarify the analysis sequence and formulate targeted analysis scheme, Reduce the cost of failure analysis, speed up the progress of failure analysis and improve the success rate of failure analysis. Prepare corresponding treatment measures for various possible causes. It is best to create fishbone diagrams of faults and failure causes to help analyze. The scheme formulated at the beginning of failure analysis should not be invariable. With the development of analysis work, the failure analysis scheme should be corrected in time according to the newly discovered phenomena and analysis results. The following mainly talks about the common failure analysis skills of electronic products.

Common techniques for failure analysis of electronic products:

1. X-ray nondestructive testing can be used for testing

*Various defects in IC packaging, such as layer peeling, burst, cavity and wire integrity

*Possible defects in PCB manufacturing process, such as poor alignment or bridging

*Defects of open circuit, short circuit or abnormal connection

*Solder ball integrity in packaging

2. Sat ultrasonic flaw detector / scanning ultrasonic microscope

It can carry out non-destructive detection on the internal structure of IC package, and effectively detect various damages caused by water, gas or heat, such as:

Wafer surface delamination

Cracks in solder balls, wafers or filler

Pores inside the packaging material

Various holes, such as holes at wafer joint surface, tin ball, glue filling, etc

3. SEM scanning electron microscope / EDX energy dispersive X-ray apparatus

It can be used for material structure analysis / defect observation, element composition, conventional micro area analysis, and accurate measurement of component size

4. Three common leakage current path analysis methods:Emmi low light level microscope / OBIRCH laser beam induced impedance change test / LC liquid crystal hot spot detection

Emmi LLM is used to detect abnormalities caused by ESD, latch up, I / O leakage, junction defect, hot electrons, oxide current leakage, etc.

OBIRCH is often used for high and low impedance analysis and line leakage path analysis Using OBIRCH method, defects in the circuit can be located effectively, such as holes in lines and holes under through holes. High resistance area at the bottom of through hole, etc; It can also effectively detect short circuit or leakage, which is a powerful supplement to luminescence microscopy.

LC can detect the specific location of chip failure caused by ESD and EOS stress damage.

5. Probe station / probe test probe test can be used to directly observe the internal signal of IC

6. ESD / latch up ESD / latch up utility test

7. FIB circuit modification

FIB focused ion beam can directly cut, connect or jumper metal wires Compared with the re flow verification, the first use of FIB tool to verify the modification of circuit design has very obvious advantages in terms of timeliness and cost.

In summary, according to the observed failure morphology, position in the chip, chemical composition, physical structure and characteristics, combined with the device failure background, failure mode, material, design layout, manufacturing process and failure analysis experience, judge the possible causes of failure. According to the probability of each possible cause, analyze and confirm one by one, and determine the root cause of the problem on the basis of certain data, technology and test. Finally, the model causing the failure phenomenon is deduced, and the corresponding mechanism of the failure mode is put forward.