What is the usual sequence of components placed on printed circuit board?

Components are placed on the printed circuit board and structure are closely cooperate with the fixed position of the components, such as a power socket, lights, switches, connectors and so on, these devices in place after the LOCK it with the software LOCK function, make it move later will not be false; Special components and large components of the line, such as heating elements, transformers, IC, etc. Place small devices. Components from the plate on the edge of the distance: possible all the components are placed in the plate edge of less than or greater than the thickness at least 3 mm, this is because when mass production assembly line plug-in and wave soldering, to provide for the use of guide groove, and at the same time in order to prevent the defect caused by edge contour machining parts, if there is excessive components on printed circuit board, forced to beyond 3 mm, can add a 3 mm at the edge of the plate and auxiliary, auxiliary edge V trough, with the hand break off when in production.