How Many Types of Pads Have You Seen in PCB Design?

June 20, 2025

In PCB design, the pad is a very important concept, and PCB engineers must be no stranger to it. However, although familiar, many engineers have only a superficial understanding of solder pads.

Pad, the basic constituent unit of surface mount assembly, is used to form the land pattern of the circuit board, that is, various combinations of pads designed for special component types.

A pad is a partially conductive pattern used for electrical connection, device fixation, or both.

Types of PCB Pads

I. Common Solder Pads

1.Square solder pads - They are often used when the components on the printed circuit board are large but few, and the printed wires are simple. When making PCBS by hand, it is easy to achieve by using this kind of pad.

2.Circular pads - widely used in single-sided and double-sided printed circuit boards where components are regularly arranged. If the density of the plate permits, the pads can be larger so that they won't fall off during welding.

3. Island-shaped pads - The wires connecting the pads are integrated into one. It is often used in vertical irregular arrangement installations.

4. Polygonal pads - Used to distinguish pads with similar outer diameters but different hole diameters, facilitating processing and assembly.

5. Elliptical pads - These pads have sufficient area to enhance anti-peeling ability and are often used in dual-in-line devices.

6. Open-shaped pads - Commonly used to ensure that the holes of the hand-soldered pads are not sealed by solder after wave soldering.

II. Special Solder Pads

1. Plum blossom solder pad

The plum blossom pad is usually used at the position where large vias are grounded. There are several reasons for this design:
1) The fixed hole needs to be metallized and connected to GND. If the fixed hole is fully metallized, it is easy to block the hole during reflow soldering.
2) The use of internal metal screw holes may cause the grounding to be in an poor state due to installation or multiple disassembly and assembly reasons. By using plum blossom hole pads, good grounding can be guaranteed regardless of how the stress changes.

2. Cross-shaped solder pads

Cross-shaped pads are also known as hot pads, hot air pads, etc. Its function is to reduce the heat dissipation of the solder pads outward during soldering, so as to prevent false soldering or PCB peeling caused by excessive heat dissipation.
1) When your pad is the ground wire. The cross pattern can reduce the area of the ground wire connection, slow down the heat dissipation speed and facilitate welding.
2) When your PCB requires machine surface mount and is a reflow soldering machine, cross-shaped solder pads can prevent the PCB from peeling off (as more heat is needed to melt the solder paste).

3. Teardrop solder pad

It is often used when the trace of the pad connection is relatively thin to prevent the pad from peeling and the trace from disconnecting from the pad. This kind of pad is commonly used in high-frequency circuits.

The design standards of pads in PCB design

I. Design Standards for the Shape and Size of PCB Pads:

1.Call the PCB standard package library.
2. The minimum diameter of each side of the pad shall not be less than 0.25mm, and the maximum diameter of the entire pad shall not exceed three times the hole diameter 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 rhombic or plum blossom-shaped pads.
5. In cases where the wiring is relatively dense, it is recommended to use oval and long oval connection panels. The diameter or minimum width of the single-sided pad is 1.6mm. For the weak current circuit pads of double-sided boards, only the hole diameter plus 0.5mm is needed. Pads that are too large may cause unnecessary continuous soldering.

II. Standards for PCB Pad Vias Size:

The inner hole of the solder pad is generally no less than 0.6mm, as holes smaller than 0.6mm are difficult to process during mold opening and punching. Usually, the inner hole diameter of the solder pad is calculated by adding 0.2mm to the diameter of the metal pins. For example, when the diameter of the metal pins of a resistor is 0.5mm, the corresponding inner hole diameter of the solder pad is 0.7mm. The diameter of the solder pad depends on the inner hole diameter.

III. Key Points for Reliability Design of PCB Pads

1.Symmetry: To ensure the balance of the surface tension of the molten solder, the pads at both ends must be symmetrical.
2. Pad spacing: If the pad spacing is too large or too small, it will cause soldering defects. Therefore, it is necessary to ensure that the distance between the component ends or pins and the pads is appropriate.
3. The remaining dimensions of the solder pads: The remaining dimensions after the ends or pins of the components overlap with the solder pads must ensure that the solder joints can form a menscar-shaped surface.
4. The width of the solder pads should be basically consistent with the width of the component ends or pins.