Types of PCB pads

Square pads - large and small components on printed circuit boards, and used when printed conductors are simple. This type of pad is easy to implement when manufacturing a PCB by hand. 

Round pads - widely used in single and double-sided printed circuit boards with regularly arranged components. If the density of the board allows, the pad can be larger and will not fall off during soldering. 

Island-shaped pad - the connection between the pad and the pad is integrated. Often used in vertical irregular arrangement installation. Such pads are often used in tape recorders.

Teardrop Pads - Used when the traces on the pad are thinner to prevent pad blister, peeling, and pad disconnection. Such pads are commonly used in high frequency circuits. 

Polygon Pads - Used to distinguish between pads with different outer diameters and different apertures for easy processing and assembly.
 
Elliptical Pads - These pads have sufficient area to enhance stripping resistance and are commonly used in dual in-line devices.
 
Open-type pad - In order to ensure that the pad holes for manual repair welding are not sealed by solder after wave soldering.