An area study is an important step in circuit board design; it is during this
step that it is determined whether the necessary design components will fit on
the board. Area studies can be done either electronically (using board layout
software) or by hand.
When doing an area study it is necessary to consider not only the size of
the component packaging, but also the clearance requirements of various components.
For instance, the pads of a given part might extend beyond what appears to be the
part outline. It is crucial that every dimension of the component
be accurately represented whether the area study is done with software or on paper.
A preliminary area study might not need to take into account which components
would be best placed in close proximity to which other components. Such a preliminary
study might consist of merely placing all the part geometries on the board anywhere
they will fit, and seeing how much room is left within the space constraints of the board.
If there seems to be a reasonable amount of space left after the preliminary area study,
a more involved study can be done -- one in which good electronic design rules and practices
are taken into consideration. For example, certain signals might require the shortest possible
trace between source and destination, so as to avoid noise pickup, etc. Parts also might
need to be rotated to a specific orientation either to eliminate trace crossover or simply
enable more small parts to be placed next to a larger associated part.
If the parts do not fit on the board, there are two options: obtain smaller parts or
increase the overall board area. In most cases, it is preferred that smaller parts be
located, because the overall trend in technology these days is for everything to get smaller.
A larger board outline could result in numerous complications, such as a board that does not
fit into a chassis or rack that has already been decided upon. Getting all necessary
parts to fit into a predefined outline is considered a valuable engineering skill.