The circuit board is an essential accessory in all electronic equipment or electronic products. All components need to be attached to the board and electrically connected through the pads on the PCB board in order to operate. The solder pad is the most important basic unit in PCB circuit board design. According to different components and soldering process, the pad in the printed circuit board can be divided into two types of non-perforated pads and perforated pads. Non-perforated pads are mainly used for surface mount component soldering, and perforated pads are mainly used for pin-type component soldering.
Rectangular pad has square and rectangular two categories. Square pad is mainly used to identify the printed circuit board for the installation of components on the first pin; rectangular pad is mainly used as the surface mount components pin pad. Pad size and the corresponding component pin size, this pad is mostly used for some simple circuits, such as some small production or handmade printed circuit board.
In the PCB proofing, round pad is the most commonly used a pad. For over-hole pads, the main size of the circular pad is the size of the hole and pad size, pad size is generally twice the size of the hole. Non-over-hole type circular pads are mainly used as test pads, positioning pads and reference pads, etc. The main size is the pad size. Mostly used for double-sided printed circuit board circuit and the arrangement of more regular circuit, such as integrated circuit pin pads, etc.
In the PCB design, the designer can be based on the specific requirements of the design, the use of some special shape of the pad, including oval, tear Li new, island-shaped, etc.. Such pads are mostly used in irregular arrangements, more applications in home appliances, such as televisions, radios, video disc players, etc.. Shaped pads can make the components more densely fixed, therefore reducing the length of the printed wire and the number of strips. This pad has a larger copper foil area, which enhances the pad's resistance to peeling strength.
Octagonal pad in the PCB proofing application less, it is mainly to meet the printed circuit board wiring and soldering performance of the pad and other requirements set.
The choice of pad shape with the shape of the components, size, layout, heat and force direction and other factors, the designer needs to be selected based on comprehensive consideration. In the process of achieving automatic welding production is most suitable for laser soldering machine for welding is a round pad and rectangular pad, at the same time, these two pads are also the most common design of PCB circuit boards.