Strains Within a 300µm Diameter Ball Solder in BGA

The VIC-3D Stereo Microscope system enables local analysis within very small elements. One industry that benefits from this small-field imaging is microelectronics. Small electronics, like ball grid arrays (BGA) seen here, are too far small for traditional DIC to provide enough resolution to obtain local strain distribution within the actual ball solder. Here, we are able to leverage the optics of the VIC-3D Stereo Microscope system to zoom in on a single ball solder within the BGA. The chip assembly is cut in half so that the cross-section can be imaged in order to reveal the strains within the individual elements (the ball solder and the two boards that it interfaces with). The specimen is loaded in shear tension, and the stereo microscope obtains images within a 1mm field of view (FOV), in order to investigate the strains within the small region in order to reveal the local strain distribution within the different components. The strain distribution within the 300 µm diameter solder along with the chipboard and motherboard that it interfaces with are all revealed with the VIC-3D Stereo Microscope system.

Image 1: Measurement setup: Stereo Microscope mounted on x-y-z-microtable (backside) and tensile machine (right)

Image 2: Principal strain of a solder ball d=300 µm under shearing load (horizontal)