Electronic Design - What are the design standards for pad shape and size in PCB design?

What are the design standards for pad shape and size in PCB design?

The pad is the basic unit of PCB surface mount assembly. On the printed circuit board, the electrical connections of all components are carried out through pads. So, what are the design standards for pad shape and size in PCB design?

Land shape and size design standard

1. The shape of the pad:

Pads can be divided into 7 categories, which are distinguished by shape as follows:

1. Square pads-more used when the printed circuit board components are large and few, and the printed wires are simple.

2. Circular pads-widely used in single and double-sided printed boards with regularly arranged components.

3. Island-shaped pad-the connection between the pad and the pad is integrated, and it is often used in vertical irregular arrangement.

4. Teardrop pad-often used when the connected traces are thinner, and are often used in high-frequency circuits.

5. Polygonal pads-used to distinguish pads with close outer diameters but different apertures, which is convenient for processing and assembly.

6. Oval pad-This pad has enough area to enhance the anti-stripping ability, and is often used in dual in-line devices.

7. Open-shaped pad-to ensure that after wave soldering, the pad hole for manual repair is not sealed by solder.

2. Design standards for pad shape and size

1. The minimum single side of all pads is not less than 0.25mm, and the maximum diameter of the entire pad is not more than 3 times the component aperture.

2. Try to ensure that the distance between the edges of the two pads is greater than 0.4mm.

3. In the case of dense wiring, it is recommended to use oval and oblong pads.

4. For plug-in components, in order to avoid copper foil breakage during soldering, the single-sided connection plate should be completely covered with copper foil, and the minimum requirement for double-sided panels should be filled with teardrops.

5. All machine insert parts need to be designed as drip pads along the bent leg direction to ensure full solder joints at the bent leg.

6. The pads on the large-area copper skin should be chrysanthemum-shaped pads, not to be soldered.

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