Micromodule

(in electronics), a miniature module densely packed with electronic components. Micromodules are used as functional subassemblies mainly in small, highly reliable electronic apparatus for aircraft, rockets, and spacecraft. A distinction is made among stacked, flat, wafer, and cylindrical micromodules.

Stacked micromodules are composed of microcomponents (resistors, capacitors, semiconductor diodes, transistors, and so on) fabricated in the form of thin plates 9.6 X 9.6 mm in size that are assembled into stacks 5–25 mm high and then embedded in a polymeric sealing compound. Flat micromodules are composed of microcomponents mounted on the surface of a printed-circuit board; the board with the microcomponents is inserted in a metal casing and sealed. In wafer micromodules, cylindrical microcomponents 0.5–6.0 mm in diameter and about 2 mm thick are inserted in holes in a printed-circuit board. Cylindrical micromodules are composed of microcomponents of identical diameter (8–10 mm). Compared to modules, the micromodules have a high packing factor (five to 30 microcomponents per cu cm) and are more reliable by an order of magnitude.