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Acoustic
Microscopy is a non-destructive screening technique
offering unique insight on the integrity of package
and device construction. Its advantages include the
detection of void formations, delaminations, cracks
and fractures as well as other hidden internal defects
within inherently susceptible materials and device types.
Various device types like SOIC’s, BGA’s, CSP’s,
encapsulating materials, PCB’s, molding compounds, flex circuits, and other products
may be analyzed. Testing performed to IPC/JEDEC J-STD-035,
Acoustic Microscopy for Nonhermetic Encapsulated Electronic
Components, or client requirements.
A
high frequency ultrasound transducer emits sound waves
that can be received back (echo) or transmitted through
a material. The acoustic signature or waveform may then
be interpreted to determine variations of acoustic impedance
within a sample. The difference in acoustic impedance
may indicate a change in material densities or separation
at an interface. The transducer may also be mechanically
scanned across the sample in a raster pattern emitting
and receiving the ultrasound signal to generate an image
(pulse-echo). An immersion fluid medium, typically DI
water, is used to acoustically couple the sample while
performing the analysis.
Measurement
Modes:
A-Scan:
The A-Scan mode is used to characterize a single point
of interest in a specimen. It is also used as a convenient
method of focusing the microscope.
B-Scan:
The B-Scan mode generates a top-down or X-Z axis crosssectional
image of the sample. Tilted artifacts or features and
non-planar fracture propagations can be identified.
C-Scan:
The C-Scan mode or pulse-echo provides a planar view
image at a specific depth. Illustrations of delaminations
and void formation can be generated.
Through-Scan:
Through-Scan transmission mode generates images based
on variations in acoustic impedance. This mode is often
necessary to verify defects observed during C-Scan
mode analysis.
Applications:
° Ceramic Capacitor Defects
° Plastic Package Defects
° Die Attach Defects
° Pharmaceutical and Medical Package Defects
° Flip Chips
° Chip Scale Packages (CSP)
° Ball Grid Arrays (BGA)
° Metal Ball Grid Arrays (MBGA)
° Plastic Encapsulated IC’s
° Hybrids
° Multi-Chip Modules (MCM)
° Bonded Wafers
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