Design and evaluation of an epoxy three-dimensional multichip module

A low-cost, three-dimensional multichip module (MCM) technology provides greatly improved system density and reduced mass over planar packaging technologies. The technology offers a high degree of testability that negates the need for known good die (KGD) procurement. Testing is achieved with very low cost overheads and with no increase in the volume of the module. The technology allows complete, heterogeneous systems to be packaged and interconnected in a single, ultra-dense module. The electrical characteristics of the technology are comparable to standard chip packages. However, the parasitics due to package-to-package interconnects are eliminated. This removes the dominant cause of parasitics, dramatically improving the electrical characteristics. A programmable integrated camera and image processing system has been developed which incorporates a grayscale camera, analog-to-digital conversion, four programmable processors and memory. Utilizing the three-dimensional multichip module technology, the system, which consists of nine chips and 36 discrete components, has an overall volume of 4.77 ml. This is approximately six times more dense than an advanced PCB implementation. The system forms the first stage in the design and manufacture of a portable video communications device. For such applications, low system volume and mass are key attributes. The system demonstrates the potential of the packaging technique for the integration of complete mixed signal systems incorporating sensors and processing. Further developments to the technology will provide increased module density, improved routing capacity, and electrical performance.