Pulse Acquisition
Reflected ultrasonic waves generated by a high-frequency transducer provide the raw signal data used to construct non-destructive cross-sectional images of packaged electronic components. Pulse-echo acoustic imaging uses a single transducer to both generate the acoustic pulse and receive the reflected echoes from internal material boundaries. This scanning method allows inspection without requiring access to both sides of the sample.
Defect Extraction
Timing and amplitude variations of the returned pulses reveal the presence of internal cracks, voids, and delamination within the component package. The instrument measures the flight time to determine the depth of each boundary and uses the amplitude to determine the interface quality. This scanning reveals cracks and voids that are invisible to both visual inspection and standard X-ray systems.
Frequency Range
Transducers optimized for electronic inspection operate at frequencies ranging from fifteen to over two hundred and thirty megahertz to balance resolution against penetration depth. High-frequency transducers offer excellent spatial resolution for detecting fine cracks but have limited penetration in thick or highly attenuating materials. Selecting the appropriate frequency ensures that the inspection system resolves the target features while penetrating to the necessary depth within the package.
This selection process is critical when inspecting stacked die packages where the transducer must resolve sub-micron air gaps on multiple layers without losing too much signal energy to the intervening silicon and mold compound.
