What are the design standards for pad shape and size in PCB design?

The pad is the basic unit of PCB surface mount assembly. On the printed circuit board, the electrical connections of all components are carried out through pads. So, what are the design standards for pad shape and size in PCB design? 1. The shape of the pad: The pad can be divided into 7 categories. According to the shape, the distinction is as follows: 1. Square pad-the printed circuit board components are large and few, and the printed wire is more used when the printed wire is simple. 2. Circular pads-widely used in single and double-sided printed boards with regularly arranged components. 3. Island-shaped pad-the connection between the pad and the pad is integrated, and it is often used in vertical irregular arrangement. 4. Teardrop pads-often used when the connected traces are thinner, and are often used in high-frequency circuits. 5. Polygonal pads-used to distinguish pads with close outer diameters but different apertures for easy processing and assembly. 6. Oval pad-This pad has enough area to enhance the anti-stripping ability, and is often used in dual in-line devices. 7. Open-shaped pads-in order to ensure that after wave soldering, the pad holes that are manually repaired are not sealed by solder. 2. Design standard of pad shape and size 1. The minimum single side of all pads is not less than 0.25mm, and the maximum diameter of the entire pad is not more than 3 times the component aperture. 2. Try to ensure that the distance between the edges of the two pads is greater than 0.4mm. 3. In the case of dense wiring, it is recommended to use oval and oblong pads. 4. For plug-in components, in order to avoid the phenomenon of copper foil breaking during welding, the single-sided connecting plate should be completely covered with copper foil, and the minimum requirement for double-sided panels should be filled with teardrops. 5. All machine insert parts need to be designed as drip pads along the direction of the bent leg to ensure that the solder joints at the bent leg are full. 6. The pads on the large-area copper skin should be chrysanthemum-shaped pads, not to be soldered. The above is about the relevant requirements of the pad shape and size design standard in PCB design, I hope it will be helpful to you.