Ultra-fine feature printed circuits and multi-chip modules

Abstract As semiconductor devices evolve, so do the packages that house them and the printed circuit boards (PCBs) that support and interconnect them to form systems. The higher numbers of connections per device are squeezed into smaller pitches, both on the package and in the PCB, to fit into the available space and to improve electrical performance. Ultimately, individual packages are not required for each device. This paper describes substrates available from GEC-Marconi suitable for carrying and interconnecting packaged or unpackaged devices, or a combination of them, manufactured using techniques and materials familiar to the PCB industry. Multi-chip modules using lamination techniques to make the substrates (MCM-Ls) are a natural extension of printed circuit technology to meet the ever increasing demands of system integration and density. As with other forms of multi-chip module (MCM), the interconnection density is so high that most circuits need very few signal layers — often only two. The substrate can also incorporate layers to control thermal expansion and extract heat. MCM-L substrates are extraordinarily versatile; they can accommodate packaged ICs (for example, fine-pitch surface mount technology), unpackaged ICs, other MCMs, and odd-form components. These ultra-fine feature substrates can provide solutions for a wide range of sizes, complexities, performance and market sectors at competitive prices.