The conventional form of fitting components on the circuit board has completely changed in this modern era. The through-hole method has been revolutionized by the modern method called surface mount technology.
Surface mount devices or SMD’s made through SMT process comprise different types of components which are very small in size, have short pins, leads, flat contacts and BGA’s. Following is the categorization of SMD devices:
Passive SMD: This comprise of various resistors or capacitors which are of different package sizes like: 1812, 1206, 0805, 0603, 0402, and 0201. These sizes are based on the dimensions of hundreds of an inch. Depending on the size levels of resistors and capacitors they are also differentiated on the basis of the use of application.
Transistors and diodes: Mostly these are contained in small packages which are connected via leads on the board. Usually, three leads are used for this purpose and are bended in such a way so that they can easily touch the board for its proper functioning.
Integrated circuits: Depending on the interconnectivity, package sizes would vary because simple chips for an example would require 14 to 16 pins, whereas other chips or processors would require more than 200 pins.
