How to choose the size of the circuit board pad size [circuit board design]
Update date：2012-8-12
Previous customers to let us help design a headset products, with plug-in plug-diameter 0.5MM, but the board, leaving only 1.2MM length, we tell customers this from the painting can not pad is too small to draw not come up. This problem is not only the customer exists, in fact, a lot of people just entering the electronics industry do not know how to design the circuit board above the pad pore size, do not know how to choose.
In fact, the design of plug-in component pads, big and small pad size should be appropriate. Too much pad and solder spread area, consisting of the solder joint is not plump, while the tension is too small of a smaller pad copper foil appearance, solder consisting of the solder joint is not infiltration.
Wiring minimum distance does not violate the design of electrical spacing, the design of the pad should be large in order to ensure the sufficient width of the ring. Generally pad the hole than the component lead diameter slightly larger, the design is too large, easily formed in the welding Weld. Pad diameter D is generally not less than (d 1.2) mm, where d is the pad within the aperture, the minimum value of the pad can take (d 1.0) mm for some density PCB. The shape of the pad is usually set to round, DIP package IC pad is the best runway shape, so in a limited space to increase the area of the pad, IC welding. The connection of the wiring and the pad should be a smooth transition, that is, when the width of the wiring to enter the circle pad than the diameter of the circular pad hours, should be used to complement teardrop design. During the design process, we need to pay attention to the size of the pore diameter d, the pad is different, we should consider: Depending on the size of the lead diameter of the actual components such as component holes, mounting holes and slots. The pad pitch should also consider the installation of the actual components such as resistors, diodes, and tubular capacitors and other components of the "vertical" and "horizontal" two kinds of installation, the pitch of two ways different. In addition, the pad pitch design should also consider the minimum clearance requirements between the components, especially the gap between the specific components from the pitch between the pads to ensure. In addition, the frequency PCB, but also to minimize the number of vias, which can reduce the distributed capacitance, but also increase the mechanical strength of the PCB. In short, the high-frequency PCB design, the pad and its shape, pore size and spacing of design should not only consider its particularity, but also to meet the requirements of the production process. Standardized design can reduce product costs, but also to ensure product quality while increasing production efficiency.
In fact, the size of the pad design and some of the considerations in the PCB design, we usually continue to accumulate during the design process, continuous learning and summed up. We are usually in the process of designing learning and summarize the faster way to improve our level of circuit board design.
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