1-41
Figure 1-43C.—Evolution of modular assemblies. INTEGRATED-CIRCUIT.
Cordwood Modules.
The cordwood assembly, shown in view (A) of figure 1-43, was designed and fabricated in various
forms and sizes, depending on user requirements. This design was used to reduce the physical size and
increase the component density and complexity of circuits through the use of discrete devices. However,
the use of the technique was somewhat limited by the size of available discrete components used.
Micromodules
The next generation assembly was the micromodule. Designers tried to achieve maximum density in
this design by using discrete components, thick- and thin-film technologies, and the insulator substrate
principle. The method used in this construction technique allowed for the efficient use of space and also
provided the mechanical strength necessary to withstand shock and vibration.
Semiconductor technology was then improved further with the introduction of the integrated circuit.
The flat-pack IC form, shown in view (C), emphasizes the density and complexity that exists with this
technique. This technology provides the means of reducing the size of circuits. It also allows the reduction
of the size of systems through the advent of the lsi circuits that are now available and vlsi circuits that are
being developed by various IC manufacturers.
Continuation of this trend toward microminiaturization will result in system forms that will require
maintenance personnel to be specially trained in maintenance techniques to perform testing, fault
isolation, and repair of systems containing complex miniature and microminiature circuits.
Q43. What are the three most common methods of interconnections?
Q44. Name the three methods of interconnecting components in multilayer printed circuit boards.
Q45. What is one of the major disadvantages of multilayer printed circuit boards?
Q46. What was the earliest form of micromodule?
