Method for analyzing quality of thin surface layer of PCB

A method for analyzing quality of a thin surface layer of a PCB, comprising steps in sequence:

• S1) taking a sample:
• wherein a region to be tested is taken from the PCB as the sample by a tool, wherein the region to be tested is close to an edge of the PCB;
• S2) performing gold spraying treatment:
• wherein conductive treatment is performed on a surface of the sample by spraying gold;
• S3) fixing and transferring the sample:
• wherein the sample to be tested is firmly fixed on a metal sample platform, with conductivity between the surface of the sample and the metal sample platform, then the sample platform with the sample is mounted on an inclined surface of a test platform, with the region to be tested facing the highest position of the test platform;
• S4) depositing a first protective layer by an electron beam:
• wherein a first protective layer is deposited by the electron beam;
• S5) depositing a second protective layer by a focused ion beam:
• wherein after depositing by the electron beam is completed, imaging is performed by the focused ion beam to determine position of the first protective layer, and then a second protective layer is deposited on the first protective layer by the focused ion beam;
• S6) forming an observation surface,
• wherein after the second protective layer is deposited, an angle of inclination of the test platform is adjusted to make a surface of the sample perpendicular to the ion beam direction of the focused ion beam, and the surface of the sample is perpendicularly cut by the focused ion beam to form a V-shaped opening inner the surface of the sample, a surface of the opening substantially perpendicular to the surface of the sample is taken as the observation surface;
• and
• S7) performing observation with a scanning electron microscope:
• wherein the angle of inclination of the sample is adjusted to substantially form a 7-degree angle between the surface of the sample and the direction of the electron beam of the scanning electron microscope, then observation to the observation surface is performed by the scanning electron microscope.