Looking at Device Internal Structure by a Cross sectioning of EEE Parts
- Posted by Francisco Javier Aparicio Rebollo
- On November 27, 2020
- 0
The cross-sectioning process provides access to the device internal structure, its materials and design. Such components as diodes and capacitors and silicon dice are often subjected to cross-sectioning to detect the defects which could not be found using other testing techniques.
Cross-sectioning generally involves three discrete steps: mounting the sample in a block of epoxy resin to form the specimen, grinding or cutting the specimen and finally polishing the surface so exposed. The main purposes of these steps are exposed hereafter.
Mounting:
- To hold the sample and their internal elements together during the sectioning process.
- To provide a means of holding the sample during grinding and polishing operations.
- To provide a convenient means of positioning the sample on the microscope stage for examination.
The purpose of grinding is to quickly reach the broad region of interest. This enables the exact area of interest to be reached by subsequent slower polishing techniques in a reasonable period of time. Grinding is carried out by using silicon carbide paper disks mounted on horizontal rotary grinding wheels. A continuous flow of water is used for cooling and cleaning the wheels.
FIGURE: Cross-sectioned wired connector
The purpose of polishing before the cross sectioning is to eliminate surface scratches produced during grinding while maintaining sectioned sample features essentially unchanged so that a true view of these features is adequately available for visual inspection.
FIGURE: PCB cross-section with soldered ceramic capacitors
After fine polishing, the samples are examined microscopically using a compound microscope with vertical illumination to locate, identify and characterize defects which constitute reject criteria.
A key element in the performance of cross-section is the ability of the inspector to detect and identify problems and non-conformances of the products. Extensive experience in the technologies examined, knowledge about acceptance criteria and cumulated know-how are a prerequisite for proper test execution.
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Since 2007 Dr. Aparicio has developed a productive research career within the field of Materials Science including post-doctoral stays at the University of Trento, the University of Mons, and the Spanish National Research Council (CSIC). His researches have been published in more than 30 articles in reputed international research journals and conferences (> 70) including more than 10 invited talks and lectures.
Within the frame of the program “Torres Quevedo” for the Knowledge Transfer and the incorporation of research talent into the industry, in 2019 he joined Alter Technology as Senior Materials Science Test Engineer. In 2019 he was appointed to lead the Scanning Acoustic Microscopy Service. Within this framework, he currently collaborates in different ESA projects (JUICE and PLATO).”
Actually, he is not in our company anymore, but still as an external collaborator in our blog.
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