Research on the Application of Microscopic Analysis Technology in PCB Inspection and Failure Analysis

With the development of PCB to high density and high reliability, the traditional microsection and scanning electron microscopy (SEM) observation methods are difficult to meet the current microscopic analysis needs, so FIB-SEM, EBSD, TEM and other microscopic analysis technologies in the quality inspection and failure analysis of PCB products have begun to be widely used. This paper briefly introduces the principles of FIB-SEM, EBSD, TEM and typical applications in the PCB field, and combines specific PCB product failure examples to conduct technical research on the practical application of microscopic analysis methods in HDI board blind hole bottom separation and FPC conductor fracture, pointing out the advantages and shortcomings of various analysis techniques, and has reference significance for PCB failure analysis, quality inspection and production process control.

I. Introduction

Printed circuit board (PCB), as the core basic component of the secondary packaging of various electronic products, is the basis for realizing the electrical interconnection between various components. The development of PCB is gradually moving towards high density and high reliability, and the industry pays attention to the macro performance of PCB while also paying attention to the exploration of its microscopic mechanism, such as the interface interconnection of various materials, the relationship between crystal structure and performance, and the defect analysis of micro-nano scale to ensure the reliability of products. Copper is the main conductor of PCB board, mainly including rigid board/flexible board basic copper foil, electroplated copper, electroless copper layer and sputtered copper layer, etc., the performance and interface bonding strength of each layer have a significant impact on PCB reliability. The metal copper layer belongs to the polycrystalline material, and its microscopic grain size and morphology are closely related to the performance of the copper layer, which directly affects the mechanical and physical properties of the copper layer. At present, the microscopic detection and analysis methods of PCB in the industry are mainly microsection and SEM, but their observation of crystal structure and micro-nano size is insufficient. In view of the market’s requirements for PCB product quality and reliability testing gradually tend to be precise and microscopic, this paper briefly introduces the equipment of commonly used microscopic analysis methods such as FIB-SEM, EBSD, TEM, etc., and provides reference for industry peers by conducting technical research on the application of practical cases of failure analysis of HDI board blind hole bottom separation and FPC conductor fracture.