In the application of surface-mount procedures, the manufacturer mounts all components on the
surface of the printed circuit board (PCB). These parts can be mounted on the top (component)
side, the bottom (solder) side, or both. Typically, manual placement is used for prototype or
low-volume runs. Robotic placement is used for medium or high-volume runs. The surface-mount
process is accomplished in three stages:
Stage 1: Solder Paste Application via Screen Printing
In the application of surface-mount procedures, components are mounted on the surface of the
printed circuit board (PCB). These parts can be mounted on the top (component) side, the bottom
(solder) side, or both.
Stage 2: Placement of Components
Typically, manual placement is used for prototype or low-volume runs. Robotic placement is used
for medium or high-volume runs
Stage 3: Oven Reflow of Solder Paste & Components to the PCB
The reflow process commences with the printed circuit assembly (PCA) travelling along the
conveyor (In line systems) passing through a preheat zone which elevates the PCB and
component leads to a temperature just below the transition from solid to liquid. The assembly then
moves into the reflow zone in which the formation of the solder joint occurs. After only a few
seconds the PCA moves into the cooling zone and the solder changes state again back into a
solid form. If the correct profile has been set and there are no solderability problems, the correct
amount of paste was applied, the components on the assembly will now be fully soldered to the
PCB.
