Complete Collection of PCB Failure Analysis Technologies

　　1. Appearance inspection

　　Appearance inspection is the visual inspection or use of some simple instruments, such as stereomicroscope, metallographic microscope, or even magnifying glass, to examine the appearance of a PCB, find the location of failure and related physical evidence. Its main function is to locate the failure and preliminarily determine the failure mode of the PCB. The appearance inspection mainly checks the contamination, corrosion, location of bursting boards, circuit wiring, and regularity of failure of PCBs. If it is a batch or individual, whether it is always concentrated in a certain area, etc. In addition, many PCBs fail only after being assembled into PCBA, and it is necessary to carefully examine the characteristics of the failure area to determine whether it is caused by the influence of the assembly process and the materials used in the process.

　　2. X-ray fluoroscopy examination

　　For certain areas that cannot be visually inspected, as well as internal defects such as through-holes in PCBs, X-ray fluoroscopy systems can only be used for inspection. The X-ray perspective system utilizes the different principles of moisture absorption or transmittance of X-rays based on different material thicknesses or densities for imaging. This technology is more commonly used to detect internal defects in PCBA solder joints, internal defects in through-holes, and location of defective solder joints in high-density packaged BGA or CSP devices. At present, the resolution of industrial X-ray fluoroscopy equipment can reach below one micrometer, and it is transitioning from two-dimensional to three-dimensional imaging equipment. There are even five dimensional (5D) devices used for packaging inspection. However, this 5D X-ray fluoroscopy system is very valuable and has little practical application in the industry.

　　3. Slice analysis

　　Slicing analysis is the process of obtaining the cross-sectional structure of a PCB through a series of methods and steps such as sampling, embedding, slicing, polishing, corrosion, and observation. Through slice analysis, rich information on the microstructure reflecting the quality of PCBs (through holes, coatings, etc.) can be obtained, providing a good basis for the next step of quality improvement. However, this method is destructive, and once sliced, the sample is inevitably destroyed; At the same time, this method requires high sample preparation requirements and a longer sample preparation time, requiring well-trained technical personnel to complete. A detailed slicing operation process is required, which can refer to the process specified in IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.