PCB Assembly refers to the attaching of electronic components to a printed journeying board. PCBs are used to mechanically enter and support 
electronic components using semiconductive pathways, traces or tracks which are etched from copper sheets laminated onto a non-conductive substrate.Once the PCB is completed then electronic components can be attached to produce a printed journeying assembly. The leads of the components are inserted through holes in the PCB, and in opencast mount construction, the electronic components are settled on lands or pads on the outmost surfaces of the printed journeying board. The component leads in both types of this construction are then mechanically immobile to the PCB with soft metal molten solder.
There are all kinds of various techniques for attaching components to printed journeying boards, and most very high intensity production is generally produced by machine placement and bulk wave soldering or reflow ovens.
Sometimes very skilled technicians are employed to solder very diminutive parts by assistance low a microscope. This is achieved by using tweezers and a very fine soldering tip. Some parts much as ball grid array packages are impossible to solder by hand.Very often, opencast mount and through the mess construction staleness be combined on a azygos printed journeying board, as some of the required electronic components are only available in opencast mount packages, patch others are only available in through mess packages.