Invention Description
The reliability of microelectronic packaging is increasingly challenged by the phenomenon of electromigration in lead-free solder joints, where high current densities cause material transport and eventual failure. Traditional characterization methods, such as optical and scanning electron microscopy, are restricted to two-dimensional surface observations that fail to capture the complex, internal three-dimensional evolution of damage, such as the formation of non-planar voids. As solder volumes continue to scale down to the micro-scale, understanding these internal structural changes becomes critical for predicting device longevity. There has been a significant technical gap in the ability to track these failure mechanisms in situ under real-world conditions, creating a pressing need for a methodology that can bridge the divide between superficial surface data and the true internal state of the material during active testing.
Researchers at Arizona State University have developed a novel custom-engineered fixture for x-ray microtomography systems and electron scanning microscopes that measures the effects of electromigration as it is happening. The fixture allows for the mounting of wire-like or fiber-like specimens of a high aspect ratio and down to 100 micrometers in diameter under mechanical constraint. It is specifically designed to perform accelerated electromigration testing on high-aspect-ratio specimens where the region of interest is a solder volume connecting copper wire substrates. It provides a wide range of characterization probes access to the region of interest, and can be equipped with a side-mounted resistive ceramic heater for studying electromigration damage at elevated temperatures. Additionally, ASU researchers have developed supporting projection processing algorithms and numerical models to reduce noise in reconstructed data and aid scan parameter optimization.
This novel fixture facilitates an unrivaled ability to explore failed solder specimens, and offers key insight to the behavior of materials undergoing electromigration.
Potential Applications
- Semiconductor industry research and quality assurance
- Development and testing of lead-free solder materials
- Failure analysis and reliability testing of microelectronic interconnects
- Academic and industrial materials science research
Benefits and Advantages
- Enables simultaneous accelerated electromigration testing and high-resolution imaging
- Minimizes thermal expansion to maintain structural integrity during testing
- Can be equipped with a ceramic heater for studying electromigration effects at elevated temperatures
- Enables in situ access to a material’s region of interest during x-ray microtomography and electron microscopy
- Includes software support for reducing image noise and optimizing scan parameters
- Works with a wide range of characterization probes
- Handles specimens of a high aspect ratio down to 100 micrometers in diameter
For more information about this opportunity, please see