Hole and PAD on printed circuit board need to array according to standard system, it is more important in multilayer printed circuit board design, because during the process of manufacturing, each layer need to align with other layers. As seen from standard system as picture below, it use 2 mutual related graphics, one is standard or one reference line, as well as standard symbol, all the components array should base upon these symbols. Below factors should be taken into consideration:
1> Fix 0/0 fiducial location, ensure all or most part of printed circuit board could be covered within the area of cartesian coordinate.
2> Fix most of components space and locations, and install the original diagram network. Specify all components which are not suitable for identify in the graphic.
3> Refers to the manufacturing and assembling aspects, we have to consider the locations requirement of holes. If size and density of printed circuit board prohibit add internal hole, then designer has to integrate panel board with external hole and view it as part of design.