Three methods of interconnecting circuitry in multilayer printed circuit boards are the
CLEARANCE-HOLE, the PLATED-THROUGH-HOLE, and LAYER BUILD-UP.
MODULAR ASSEMBLIES were devised to achieve high circuit density.
Modular assemblies have progressed from CORDWOOD MODULES through
MICROMODULES. Micromodules consist of film components and discrete components to integrated
and hybrid circuitry.
ENVIRONMENTAL FACTORS to be considered are temperature, humidity, shock, vibration, and