High-Density 3D Packaging Sidewall Interconnection Technology for CCD Micro-Camera Visual Inspection System

The authors have developed 3D packaging sidewall interconnection technology, which enables a higher packaging density in the 3D stack direction, in order to realize a CCD micro-camera visual inspection system integrated on the front of an experimental wireless micromachine for a visual inspection robot moving by itself in pipes of diameter 10 mm ϕ in an electric power generation plant. This technology was achieved by exposing the high-aspect-ratio circuit wiring layers at the edge of a stack-unit substrate as sidewall footprint. The sidewall footprint has a high aspect ratio, which is a superior shape for the electrode terminals, by designing the Cu-filled stacked vias to be laid out directly on the core substrate in a build-up multilayer wiring substrate. With regard to the alignment between the stack-unit substrates that determines the relative precision of the sidewall footprint, the process of dividing into the individual 3D packaging modules after multiple-unit layout stack-unit substrate lamination was used to improve the precision of sidewall footprint. By using this packaging technology, a prototype 3D packaging module consisting of a CCD video signal transmission circuit and a CCD control signal circuit in a CCD micro-camera visual inspection system obtained an excellent CCD output signal and confirmed the effectiveness of the technology for high-density packaging in a microspace. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(8): 67–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10063