Prototyping SMT Stencils for µBGA and similar smaller size components requires Fine Line Stencil technology. The whole affair of developing Prototype SMT Stencils is an expensive and meticulous job but nevertheless in big demand by mass PCB assemblers.
A PCB (printed circuit board) would not invite a second glance from us but if we only come to know behind the various technologies involved in making them, we would probably say a silent thanks to the inventors of Gerber file format and software developers of CAD and CAM.
In addition, another recent technological advancement used in creating SMT Stencil is laser. To produce prototype Stencil for soldering minute semi conductors and chips, laser is employed to cut the base stencil material for surface mounting.
I gathered this much information for the benefit of a young electronics engineer who wishes to start his PCB assembling unit in a small scale.