In the manufacturing of printed circuit boards (PCBs), it is common to encounter solder bridging issues, where unexpected solder connections occur between adjacent pads. This is mainly due to improper pad setup, and if not addressed promptly, it can lead to circuit shorts, affecting normal functionality. So how do you choose pads? Perhaps you can take a look at the following three types of pads!
1. Add Tail PadsTail pads refer to the addition of an extended line at the edge of the pad, giving the pad a “tail” shape. This design can guide the solder to flow along a specific path during the soldering process, reducing the likelihood of solder flowing to adjacent pads. At the same time, the design of tail pads must also consider factors such as length, width, and position to ensure they can effectively guide the solder flow and avoid interference with other components.
This design is suitable for DIP, SIP, ZIP, and other series of packaged components.
Design Requirements:
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If the package pin spacing is less than 0.2mm, tail pads must be added;
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If the package is parallel to the PCBA direction, tail pads should be added at the end pins;
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If the package is perpendicular to the PCBA direction, add a tail pad for every other pin.
2. Add Solder Absorption PadsSolder absorption pads refer to the addition of a small pad between adjacent pads to absorb excess solder. When solder flows towards adjacent pads during the soldering process, this extra pad will preferentially absorb the solder, preventing solder from bridging between adjacent pads. The challenge of this design lies in precisely controlling the size and position of the solder absorption pad to ensure it can effectively absorb solder without affecting the overall layout and functionality of the PCB. This design is suitable for DIP, SIP, ZIP, and other series of packaged components. Design requirements:
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If the pad pin spacing is less than 1.27mm, a solder absorption pad must be equipped;
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The size of the solder absorption pad must be larger than that of the original pad;
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The solder absorption pad must be outside the component’s outer frame silk screen;
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The solder absorption pad must be on the same network as its adjacent pads or floating, with no conflicts.
3. Extend Pin PadsExtended pin pads refer to increasing the contact area between the pad and the pin to reduce the risk of solder bridging. This design allows solder to distribute better between the pad and the pin during the soldering process, reducing the likelihood of it flowing to adjacent pads. It is important to ensure that the extended part of the pad does not interfere with other pads or components during the design process, and also to consider the soldering process to avoid making the pins too long, which can lead to soldering difficulties. This design is suitable for QFP series packaged components. Design requirements:
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The width of the pad must match the component pin;
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The length of the pad should be 1-1.5 times that of the component pin.
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