High density interconnect (HDI) advances in substrate technology have allowed considerable improvements in processing more complex, compact devices. Chip Scale Packaging (CSP) and multi-chip modules (MCM) have continued to decrease in size and increase in functionality, moving closer to be more like flip chip technology. Improvements in wafer structuring allow for tremendous possibilities for device functionality; however a limit does exists on what traditional substrate fabrication methods will allow. A push in developing through silicon vias (TSVs) and use of alternative materials, other than organic or flex, are needed to enable new packaging technology developments. As needed, an alternative substrate has been developed that uses Silicon-based technology, photo-defined vias and the capability of semiconductor level routing density. It also includes the possibility to open cavities in the substrate to embed integrated die. This technology has opened up many possibilities for fabricating Ultra high density substrates from a US-based supplier that enables the use of integrated die, surface mount processing and fine pitch, multi-die placements.
The following paper details the processing and reliability capabilities of this substrate technology. A comprehensive characterization study was conducted to evaluate the processing of units containing ultra-small SMT devices, intermixed with fine pitch, flip chip die. The units were also processed with traditional BGA balling, making them compatible with level 2, PCB level processes. Data will be shown with the results of the assembly analysis and subsequent reliability assessment of these units, showing a robust performance with thermal shock, uHAST and MSL level testing. A full analysis of the substrates structure will also be shown. The paper will show this technology's possibilities as a next generation substrate alternative.
Demonstration of fine pitch FCOB (Flip Chip on Board) assembly based on solder bumps at Fermilab