SEM, Scanning Electron Microscope
Interactions of the electron beam with atoms at various depths within the sample, various signals will be generated include secondary electrons (SE), backscattered electrons (BSE), X-rays, etc. The detector collects these secondary signals and then construct an image of the surface characteristics of the sample.
The characteristic X-rays generated during the observation process can be used to determine element composition with EDS(Energy-dispersive X-ray spectroscopy).
Therefore, SEM can observe the appearance, size of the sample and determine the composition of materials.
The sample could be observed with multiple illumination systems and the magnification is from 50x to 2500x. It can also zoom in and out through the optical lens to capture the sample surface. In addition, digital microscope can synthesis image for samples with height differences.
Therefore, this equipment is suitable for parts IC packaging inspection (appearance, defects, discoloration), PCB board appearance or surface finishes defect observation and PCBA solder joint and defect observation (solder ball, bridging, dewetting).
High-energy electrons are released from the filament to excite the target material to generate X-ray for sample penetration. Due to the different density of each structure in the sample, there will be a black and white grayscale difference in the X-ray penetration image, this indicates the location and type of defects in the sample. X-ray inspection is a non-destructive analysis, hence further tests can be performed with the same sample.
X-ray inspection can be applied to:
- Internal defects of IC packaging parts
- Soldering condition of the assembled electronic circuit board
- Porosity proportion in the solder joint
- Filling condition of the porous material
Dye and Pry Test
Solder joints on the circuit board are infiltrated with special ink, so that the fine defects of the solder joints are dyed, and the solder joints and PCB will be seperated to expose the dyed area to observe the size and morphology of the defects.
Therefore, this test can observe solder joint defects of PCBA and confirm the sealing condition of filling materials and sealing materials.
Cross Section Test
The abnormal part will be sampled sealed the part with resin. After epoxy curing, the sample will be grinded and polished to the desired position, and then observe with digital microscope or SEM.