ZEISS Axio Imager.M2m Optical Microscopy
A ZEISS Axio Imager.M2m optical microscope equipped with an Axiocam 503 color microscope camera Figure 3.7. The ZEISS Axio Imager.M2m optical microscope operates using an LED to illuminate the specimens, equipped with 5 objective magnifications (50, 100, 200, 500, and 1000x). Axiocam 503 color has a 3-megapixel color camera with a 2/3” sensor and an image diagonal of 11mm. The highest resolution is 4.54 µm pixel size. It features a dynamic range of 1:2,500 for precise reproduction and can take live images of up to 38 images per second at full resolution. The fracture surface was again inspected using the same optical microscope.
Hitachi S-2460N SEM
Figure 3.10 depicts the SEM used to examine the specimen microstructure and fracture surfaces.A
beam of electrons is used to scan the specimen, images are created with higher resolution and depth of focus. In addition, depending on the information desired, three different technologies are integrated in the SEM system: secondary electrons detection (SE), backscattered electrons (BSE), and characteristic X ray (EDS). All these techniques carry out signals treated from the interaction of the electrons with the surface of the sample. First, secondary electron detection (SE) is the most common imaging mode, It provides information about the surface morphology and surface topography. Low-energy (<50 eV) is collected resulting from conduction or valence bands of the specimen atoms by inelastic scattering interactions with beam electrons [55].
]In addition, backscattered electron detection (BSE) mode collects higher energy electrons coming from deeper layers of the specimen. The BSE technique is used to determine the contrast between area with different compositions( based on the atomic number and phase differences). Image from BSE mode is brighter than SE mode since the heavy elements from BSE are brighter. Third,
The X-ray (Energy-dispersive X-ray spectroscopy, EDS) was used to address the map of different compositions and also characterize the elements by sorting them based on the constituent percentages for a specific area of the sample. Every element has its own atomic structure, by interacting with X-ray excitation, a set of peaks on its electromagnetic emission spectrum (element signature) is displayed. Image processing techniques based on the depth of the signal are described in the figure 3.11.
IMC Thickness Analysis
The thickness of the IMC layer is measured for each combination to study the role of its thick- ness on the component reliability. In order to measure the thickness of the IMC layer, the picture is captured using the ZEISS microscope as shown in Figure 4.19.
The area and the length of the layer is obtained using the image processing tools in ZEN core software by ZEISS. The average thickness is calculated by dividing the area by the IMC length, as shown in the picture below.
