Answer: In the 1990s, an innovative team of engineers and scientists at GE created multi chip modules packages using blind vias and build up circuit technologies to interconnect them. Others have followed that lead including Intel with its BBUL microprocessor chip and universities and technical institutes in Europe. Researchers in Japan have also been working on buried active device assembly. In every know case, the developers are working with bare IC die and not tested and burned in IC packages. The problem with bare die is twofold: 1) The entire assembly must be completed and burned in before the yield of the die is known and this has hampered broader scale use 2) Bare die are nonstandard in terms of both size and pin out making design a challenge as a library of registered components is virtually impossible to obtain. Another difference is that almost all modules created in this fashion were designed to be assembled to printed circuit boards and most often with solder. In short, known prior efforts have been primarily on building micro electronics using microvias in an IC fab-like environment and the improved technology will be focused on assembly macro electronics and interconnection macrovias produced in printed circuit shop environments with no solder in the final assembly.
The new concepts also differ from known prior work in that it proposes have components back to back with through connections where required to make side to side connections and the stacking and lateral interconnection of assemblies. There are a number of other innovations and improvements in the works as well to advance the concept.
To reiterate and summarize, a key difference between earlier and presently developing concepts and the processes in development is that robust, tested and burned in IC packages will be used in place of delicate and bare silicon chip of uncertain quality. In recent years embedded passive and embedded active (i.e., IC chip) modules and PCBs have been described but these modules and PCBs are so far as is known still being designed to be soldered to a next level assembly. The technology presently in development proposes the complete elimination of solder and all of the associated problems it brings with it. This is an important distinction in the evolutionary development of improved electronics over time where each succeeding generation builds on the foundations of earlier work. To paraphrase Isaac Newton: “If Verdant has been able to see a bit further than others, it is because we have benefited from standing on the shoulders of giants.”