X-ray inspection for PCB defects

Common types and manifestations of PCB defects：
Appearance defects: including PCB surface scratches, pits, bulges, cracks, pinholes, solder mask peeling, air bubbles,
copper exposure, sagging, pad oxidation, deformation, lack of materials, misprinted characters, missed printing, blur,
poor adhesion, hole offset, blockage, inconsistent hole diameter, etc. Such defects directly affect the assembly suit-
ability and appearance compliance of the PCB.

Electrical performance defects:
Mainly manifested as line open circuit (poor conduction), short circuit (abnormal connection between lines), low insul-
ation resistance, substandard voltage resistance, etc., which will cause the PCB to be unable to achieve normal electri-
cal functions, and even cause equipment failure or safety hazards.

Structural defects:
such as PCB surface warpage exceeding the standard, interlayer separation (stratification), bubbles inside the substrate,
etc., which affect the mechanical strength of the PCB and the assembly accuracy of components. Long-term use is prone to
problems such as unstable signal transmission.

Main detection methods for PCB defects

Automated Optical Inspection (AOI): Based on machine vision technology, it scans the PCB surface at high speed and automa-
tically identifies appearance defects (such as scratches, exposed copper, abnormal characters) through image comparison.
It has high detection efficiency and good repeatability, and is suitable for preliminary screening of batch PCBs.

X-ray inspection (X-Ray):
Using X-ray to penetrate the internal structure of PCB, clearly showing the welding status of solder joints (such as BGA,
CSP packaged devices), and checking for internal defects such as virtual soldering, solder connection, and solder voids,
it is the core means of detecting hidden defects in PCB.