The Difference Between Through Hole And Surface Mounted Technology

As the structure of semi conductors became more complex over time, the packaging technology required significant changes in order to offer added utilities and functionalities. To complement the complexity some new forms of packaging for semiconductor integrated circuits were developed, that were classified based on their mounting style.

Major Types of Mounting in Semiconductors

Through Hole Mounting: This mounting technique involves different components which have lead wires that are led to the board through holes, hence the name. In this method, leads 
rely on holes in a multilayer PCB. The leads are then finally soldered to offer permanent mounting. The technology finds usage in

• DIP aka Dual Inline Packaging

• Pin Grid Array Package

Surface Mounting: This is a relatively new mounting method worked out seeing a

tremendous increase in the number of pins in Integrated Circuits. As demand for smaller weight and size of packaged weight increased, there was felt a need for a new, improved technology that came to be known as surface mount technology (SMT). In this leads are soldered on PCB surface directly rather than using hole mounting. The technology is used in

• Flatpack Packages

• Chip Carrier Packages

The Differences Between Through Hole and Surface Mounted technology

There are some points that make SMT different from Through Hole, which have been briefly summarized below

• SMT has helped significantly in solving the space problems that were commonly noticed with the Through Hole mounting.

• The pin count has increased greatly in SMT when compared to its older counterparts.

• In SMT, the components are leadless and are directly mounted to the board surface. In Through Hole the components have lead wires that are taken to the wiring boards via holes.

• The Pads on the surface in SMT are not used for connection of layers on the printed wiring boards.

• The components in the Though Hole Technology are larger which leads to lower component density per unit area. The packing density that can be achieved with SMT is very high as this allows mounting component on both sides, when needed.

• SMT has made possible applications that seemed impossible with through hole.

• SMT is suitable for high volume production that gives access to lowered cost of unit assemblies which is not possible with through hole technology.

• With SMT acquiring higher circuit speed is easier due to the reduced size. SMT fulfils one of the prime marketing requirements while assisting in making high performance circuits in a very small size.

• SMT has a disadvantage as the capital investment involved in its machinery and production is higher.

• Designing, production, skill and technology required in implementing SMT is very advanced when compared to through hole technology.

When comparing both, SMT surpasses Through Hole in advantages, which clearly define and justify the majority (90%) use of this technology in board assemblies. Through Hole however is anticipated to remain in use in testing and prototype applications that may need manual adjustments and replacements.Its complete disappearance from the scene seems to be ruled out.