There are several different techniques used to assemble PCBs and Surface Mount Technology is considered the most preferred of them all. But what is Surface Mount Technology and why is it an ideal option for your PCB?
Surface Mount Technology or SMT, as the name suggests is the mounting technique through which electrical components are directly mounted on the surface of the PCB. The conventional mounting technologies inserted the electrical components in a PCB through holes which would consume much space on a PCB. Whereas the SMT enables mounting on the surface itself giving way to optimal usage of the PCB space and reduction of wastage; allowing compact size PCBs. In addition to that, it also reduced the manufacturing cost and increased the scope of manufacturing automation.
Advantages
- Components per unit area: Usage of limited space leaves room for additional components, therefore resulting in higher component density. Also, components can be placed on both sides of the PCB.
- Component Connections: As the technique doesn’t involve holes which block the routing space in the inner and the backside layers, many more connections per component can be adjusted.
- Scope for Correction: Minor errors in component placement are fixed automatically during the soldering process as the molten solder pulls components into alignment with solder pads. The same isn’t possible in a conventional through hole mechanism as once the leads are drawn through the holes, the components are fully aligned and cannot move laterally out of alignment.
- Under Stress Performance: Due to lower mass and lesser cantilevering, the SMT designed PCBs have shown better mechanical performance under stress situations like in case of a shock or vibrations.
- EMC Performance: The smaller radiation loop and lesser lead inductance results in lower radiated emissions, therefore better EMC Performance.
- Efficient Solution: In comparison to a through hole mechanism, the SMT proves more efficient in terms of costing and time consumption. It is an automated process so is a simpler and faster technique.
Disadvantages
The SMT might prove effective in many terms but it has its own set of disadvantages. With the smaller sizes and lead spacings of the SMT devised PCBs, manual prototype assembly or component-level repair can be a costly affair requiring skilled operators and more expensive tools. Also, this puts the reliability of solder joints to question. The compact size leaves no space for markings, due to which the marked ID codes or the component values need to be more cryptic and smaller that are impossible to read normally and require magnification.
The SMT might have its own set of disadvantages but overall, the introduction of this technology has revolutionised the PCB designing process, giving way to building highly complex electronic circuits with compact assemblies and good repeatability due to the higher level of automation at a lesser cost.
