Imaging Method
Automated acoustic and optical inspection systems translate a probe along a defined grid to map surface and subsurface features. In planar raster scanning, the measurement head moves in a series of closely spaced parallel lines across the horizontal plane of the sample. This technique generates a continuous two dimensional image of internal interfaces by collecting data at regular spatial intervals.
It is widely employed in acoustic microscopy to evaluate the integrity of ball grid array joints.
Defect Detection
Discontinuity analysis relies on the reflection and transmission of signals at material boundaries. When the scanner encounters a void or a delamination, the amplitude of the reflected wave shifts sharply from the baseline. These signal shifts are converted into contrast maps that highlight internal structural anomalies.
Resolution Boundary
Achieving high spatial resolution requires balancing the scanning velocity with the step size of the mechanical gantry. Smaller step sizes yield denser data arrays that can resolve sub-micron cracks, but this adjustment increases the total acquisition time. The process is optimized by using high frequency transducers that focus the energy on the critical solder layer of the assembly.
This precise focus ensures that thin delamination defects are captured before the board proceeds to final system assembly.
