Printed Circuit Assembly Strain Limits during Bed of Nails Testing
Bed-of-nails test fixtures demand empirical strain gauge verification to ensure dynamic microstrain levels stay below component limits and prevent latent pad cratering.
Scanning Electron Microscopy Solder
Atomic Resolution
Electron beam bombardment of a connection point creates high-magnification images that detail the chemical morphology of the alloy. Utilizing scanning electron microscopy solder evaluations allows for the detection of elemental migration and the identification of microscopic non-conductive inclusions. This technique reaches resolutions far beyond the limits of visible light devices.
Composition Mapping
Backscattered electrons provide information about the variations in atomic weight within the cross-sectioned joint. When performing scanning electron microscopy solder analysis, engineers look for the needle-like silver-tin structures that characterize aged or heat-stressed solder masses. These features appear with high contrast, allowing for the measurement of the intermetallic growth rate at the pad interface.
This imaging is coupled with Energy Dispersive Spectroscopy to identify contaminants like oxygen, nickel, or leftover flux residues that weaken the bond. The high depth of field provided by the electron source makes it possible to view the three-dimensional structure of a fracture surface. Understanding the crystal orientation inside the joint helps predict how well it will withstand repeated thermal expansion in the field.
Topological Depth
Visual scans of fracture paths indicate if the failure occurred within the bulk solder or along the brittle nickel boundary. Detailed results define whether the manufacturing process was under control.