Epoxy Strain Transfer Efficiency Loss under Cyclic Thermal Loading
Cyclic thermal loading degrades epoxy shear modulus, causing strain transfer loss that demands strict bondline guard-banding in technical files.
Acoustic Micro-Tomography
Mapping Logic
Ultrasonic imaging systems provide three dimensional visualizations of internal material density variations. High frequency sound waves are used in acoustic micro tomography to map the interior of electronic packages without destructive cross sectioning. These waves reflect off interfaces between dissimilar materials, such as the boundary between a die and a molding compound.
Signal processing algorithms then reconstruct these reflections into a stack of virtual slices. This non destructive method identifies buried defects like voids or cracks that optical inspection cannot reach.
Detection Capability
The system uses a focused transducer to scan the surface while submerged in a coupling fluid. Because acoustic micro tomography relies on mechanical impedance differences, it excels at finding air gaps. An air gap reflects nearly 100 percent of the acoustic energy back to the sensor.
This makes the technique a standard for identifying delamination in surface mount components.
Defect Categorization
Reflected signals are analyzed for phase inversion and amplitude to distinguish between a secure bond and a physical separation. In a secure bond, the signal passes through or returns with a specific phase, whereas a separation flips the phase of the wave. Modern systems integrate automated software to flag these anomalies based on pre set thresholds for reflection intensity.
High resolution sensors allow for the detection of features as small as several microns in width. The resulting data set provides a complete internal map of the assembly.