Non-destructive techniques have the advantage of providing data without physical alteration of the electronic device. The five major techniques used are X-ray, scanning acoustic microscopy (SAM), superconducting quantum interference device (SQUID), time domain reflectometry (TDR), and thermal imaging.
The X-ray tool analyzes density differences among the materials in electronic devices. It is used mostly during package analysis where C4 bumps and metal traces, such as wires, show a high contrast to all other materials.
Scanning acoustic microscopy (SAM)
Scanning acoustic microscopy is used to measure the acoustic impedance of electronic devices. Reflections and transmissions of pulsing sound waves show the acoustic density differences between materials.
Superconducting quantum interference device (SQUID)
The superconducting quantum interference device is a very sensitive magnetic sensor that measures electromagnetic fields caused by current flow. It is mostly used to detect resistive and solid shorts on a macroscopic scale.
Time domain reflectometry
Time domain reflectometry is a method used to measure the electrical impedance of metal traces. A short, high-frequency pulse is generated and transmitted from the pad, pin, or ball through the metal traces of the package and into the die. Any impedance changes will cause reflections that are characteristic for the impedance change. During functional analysis, the location information of the impedance change can be used to isolate the origin of opens or shorts.
During thermal imaging, the electromagnetic emissions in the near-infrared range are collected and processed to produce a thermal emission map of the device. Through comparison with reference parts, hot spots can be identified that relate, for example, to mismatches in thermal conductivity.