Design standards for the shape and size of PCB pads
1. Call PCB standard package library
2. The minimum single side of the pad is not less than 0.25mm, and the diameter of the entire pad is not greater than 3 times the aperture of the component
3. Try to ensure that the distance between the edges of the two pads is greater than 0.4mm
4. Pads with a hole diameter exceeding 1.2mm or a pad diameter exceeding 3.0mm should be designed as diamond-shaped or plum-shaped pads
5. In the case of dense wiring, it is recommended to use oval and oblong connection pads. The diameter or minimum width of the single-sided pad is 1.6mm; the double-sided weak current line pad only needs to add 0.5mm to the hole diameter, and the pad is too large to cause unnecessary continuous welding

PCB pad via hole size standard
The inner hole of the pad is generally not less than 0.6mm, because the hole smaller than 0.6mm is not easy to process when punching. Usually, the diameter of the metal pin plus 0.2mm is used as the diameter of the inner hole of the pad, such as the diameter of the metal pin of the resistor. When it is 0.5mm, the diameter of the inner hole of the pad corresponds to 0.7mm, and the diameter of the pad depends on the diameter of the inner hole.

Reliability Design Points of PCB Pads
1. Symmetry, in order to ensure the balance of the surface tension of molten solder, the pads at both ends must be symmetrical
2. Pad spacing, if the spacing of the pads is too large or too small, it will cause welding defects, so ensure that the spacing between the component terminals or pins and the pads is appropriate
3. The remaining size of the pad, the remaining size after the component end or pin overlaps with the pad must ensure that the solder joint can form a meniscus
4. The width of the pad should be basically the same as the width of the component end or pin