2.10 Hot air leveling of PCB Circuit Board
During this stage of the fabrication process, the panels are dipped in solder bath, so that all PTHs and solder points are covered with tin-lead plating. These panels are passed through a conveyor, while hot air is blown from one side of the panel, so that all the tin-lead covered holes are cleared.
2.11 PCB Circuit Board Trimming
During this stage of the process, the panels are cut to the required size of individual PCB. Printed circuit boards contain holes which are plated through and some which are not to have any plating in them at all. Since the electro-less copper process will deposit copper inside drilled holes, a second drilling step is needed. These holes are mainly used for mounting the components and ﬁxing the connectors etc.
2.12 PCB Circuit Board Legend printing
The legend or nomenclature, is screen-printed onto PCBs to identify the components, for assembling and testing purposes. This screen-printing operation is performed using legend print ﬁlm supplied by the customer. Since legend is permanent, once it is dried, legend-printed panels must also be checked for legibility and completeness of the printed image.
2.13 PCB Circuit Board Inspection
Inspection is done at various stages of the fabrication process. If the panel is accepted at that stage, it is passed on to the next stage. Otherwise it goes back to rework, to the same stage of operation. In some cases, when the panel is beyond rework, it is rejected.