Shape and classification of pcb pads
In PCB design, pads are a vital component used to achieve electrical connections between components and circuit boards. Depending on the application requirements, welding process and component type, the design of pads will also vary. In this article, we will introduce the shape and classification of pcba pads in detail, so that everyone can be more familiar with the knowledge of pcb pads.
In PCB design, pads are a vital component used to achieve electrical connections between components and circuit boards. Depending on the application requirements, welding process and component type, the design of pads will also vary. In this article, we will introduce the shape and classification of pcba pads in detail, so that everyone can be more familiar with the knowledge of pcb pads.
1. Round pads: Round pads are the most common basic shape. They are suitable for most welding needs, especially for SMD (surface mount devices) that need to be soldered by wave soldering or reflow soldering. Round pads can provide good soldering wettability and strength.
2. Square pads: Square pads have advantages over round pads in certain specific applications, such as when higher soldering strength or larger soldering area is required. They are usually used for connection points that are subject to greater mechanical stress.
3. Oval pads: Oval pads are usually used in situations where the soldering direction needs to be controlled, such as in certain high-density wiring areas on PCBs, where oval pads can help guide the solder to flow in a specific direction.
4. Special-shaped pads: In addition to standard round, square and oval pads, there are also some special-shaped pads, such as heart-shaped, star-shaped, D-shaped, etc. These special-shaped pads are mainly used for special soldering needs or specific design requirements.
Classification of pcb pads
1. Through-hole pads: Through-hole pads are suitable for pin soldering of plug-in components. They usually correspond to through-holes on the circuit board, allowing component pins to pass through the PCB and solder from the other side.
2. Surface mount pads: Surface mount pads are designed for SMD. These pads are located on the surface of the PCB and do not require through-holes. Components are fixed to the PCB through soldering processes such as reflow soldering or wave soldering.
3. Microvia pads: Microvia pads are commonly used in high-density interconnect (HDI) PCBs to achieve tiny through-hole connections between multi-layer boards. The size of these pads is very small and is suitable for high-precision and high-reliability electronic applications.
4. Solder mask defined pads: Solder mask defined pads are a type of pad defined on the solder mask layer, in which the solder mask layer forms a small gap around the pad to help control the flow of solder during soldering.
5. Non-Solder Mask Defined Pad: Non-Solder Mask Defined Pad has no solder mask gap restrictions, and solder can flow freely on the pad surface. This type of pad may be used in certain specific applications or special process requirements.
classification of pcb pads
2. The spacing between the edges of the two pads should be greater than 0.4mm as much as possible.
3. In the case of dense wiring, elliptical and oblong connection pads are recommended. The diameter or minimum width of the single-sided pad is 1.6mm; the weak current line pad of the double-sided board only needs the hole diameter plus 0.5mm. If the pad is too large, it is easy to cause unnecessary soldering. Pads with an aperture of more than 1.2mm or a pad diameter of more than 3.0mm should be designed as diamond or plum blossom pads.
4. For plug-in components, in order to avoid copper foil breakage during welding, the connection pads on one side should be completely covered with copper foil; and the minimum requirement for double-sided boards should be teardrops.
5. All machine-inserted parts should be designed as drip pads along the bend direction to ensure that the solder joints at the bend are full.
6. Pads on large areas of copper foil should use daisy-shaped pads to avoid cold soldering. If there are large areas of ground and power lines on the PCB (area exceeding 500 square millimeters), windows should be opened locally or designed as grid filling.