ULTRA-FINE FEATURE PRINTED-CIRCUITS AND MULTICHIP MODULES

As semiconductor devices evolve, so do the packages that house them an d the printed circuit boards (PCBs) that support and interconnect them to form systems. The higher numbers of connections per device are squ eezed into smaller pitches, both on the package and in the PCB, to fit into the available space and to improve electrical performance. Ultim ately, individual packages are not required for each device. This pape r describes substrates available from GEC-Marconi Research Centre suit able 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 tech niques to make the substrates (MCM-Ls) are a natural extension of prin ted circuit technology to meet the ever increasing demands of system i ntegration 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 substrate s are extraordinarily versatile; they can accommodate packaged ICs (fo r example, fine-pitch surface mount technology), unpackaged ICs, other MCMs, and odd-form components. These ultra-fine feature substrates ca n provide solutions for a wide range of sizes, complexities, performan ce and market sectors at competitive prices.