Foreword

The developments over the past 8–10 years reflected in this document have resulted in a variety of new materials, structures, and interconnect methodologies. This ‘‘smorgasbord'' of MCM technology is shown in Figure F–1. The selection of the elements that make up a structure to meet the systems level needs initially appears to be a difficult problem in the current environment. However, the choices available should be viewed as part of the beauty of this technology.

Initially, system requirements should be developed on a hierarchal basis. A simple high-level breakdown of a system is shown in Figure F–2. System requirements for cost, reliability and performance must be clearly understood in the context of the application and system environment. In this way, requirements are logically developed and an understanding of their interrelationships can be inferred or modeled.

The complexity of an MCM structure demands the development of requirements for the structure from system level considerations. The next step is to work with system partitioning concepts that make sense in terms of system cost and performance. For example, the designer should question whether it makes sense to use single chip packaging, manufacture a single module an a 10.2 cm [4 in] substrate, or four modules on a 5.1 cm [2 in] substrate. Perhaps the answer is the latter when cost is compared to performance requirements for the system. This process of system partitioning may require an iteration or two following the initial technology selection in order to develop accurate costs as the process of developing a module-based system progresses.

Following the development of system requirements and partitioning, a specific module can be synthesized which meets the systems needs through a balancing of module attributes related to cost, performance, and reliability. At this point, IPC-MC-790 can become a useful tool in understanding the various module options and the relationship of these attributes to a potential structure. this is done through the use of comparisons of interconnect and substrate properties, manufacturing costs and other criteria for MCM-L, MCM-D, and MCM-C as defined in section 1 of the document. Table F–1 shows these various module attributes and their relative weights for these general categories.

The selection of a general category is initially made through comparing system requirements to module attributes. This should be done in a quantitative fashion