Introduction on SMD or SMT | What is surface mounted devices or technology | Advantages of SMD or SMT | Disadvantages of SMD or SMT |
Basic introduction of SMD: Surface Mounted Devices.
Surface mount technology is a method for constructing electronic circuit in which the components which will surface mount components mounted directly into the surface of printed circuit boards (PCBs). Electronic devices made so it called surface mount devices (SMDs).
In the industry, SMT has largely replaced the through whole technology in which components are fitted with wire leads into holes in the circuit board. SMT components are smaller than through whole components because it has smaller leads or no leads.
SMT components are mechanically that will redesign to have small metal tabs or end caps or terminations on the body of the component, which will directly solder to the surface body of the PCB.
Surface mount components are smaller in size and they will place on both sides of a board and thus allows higher circuit densities. SMDs are lightweight, hence provides a high degree of automation, reducing labor costs, and increase production rates.
SMDs have same electrical function as that of through whole components with better electrical performance. SMT and SMD components on circuit board are as shown in figure.
Advantages of SMDs:
- Reduced size and weight for SMDs.
- Components place on the side of the circuit board.
- It has low resistance.
- Similar automated assembly.
- Small errors during placements will correct automatically.
- SMDs provide better mechanical performances under shake and vibration conditions.
- Effect of unwanted RF signal is less than in SMT parts.
- Faster assembly.
- Fewer hoes need to be drilled.
- Smaller production and storage area.
Disadvantages of SMDs:
- The manufacturing process for an SMT much more sophisticated than the whole board, then it raises the initial cost and time of setting up for production.
- Manual assembly or component level repair is more difficult than machine assembly.
- SMDs cannot use with breadboards for testing purposes. It requires custom PCB for testing also and that type of PCBs are expensive.
- Due to high packaging density thermal problem arises.
- As all SMD components not labeled with a clear text thus difficult to distinguish different SMD components. SMD layout design is too complex than the normal PCB layout.
- High accuracy in PCB artwork and fabrication must require to design a complex circuits.