What issues should be paid attention to in PCB 護墊？

Pad is a kind of hole, pad design should pay attention to the following matters.

1. Diameter and inner hole size of pad: 焊盤內孔一般不小於0.6mm，因為小於0.6mm的孔不易加工。 通常採用金屬引腳直徑加0.2mm作為焊盤內孔直徑。 如果電阻的金屬引腳直徑為0.5mm，則焊盤內孔直徑為0.7mm，焊盤直徑取決於內孔直徑。 Hole diameter/pad diameter is usually: 0.4/1.5; 0.5 / 1.5;0.6 / 2; 0.8 / 2.5; 1.0 / 3.0; 1.2 / 3.5; 1.6/4. When the diameter of the pad is 1.5 mm, in order to increase the stripping strength of the pad, the length of not less than 1.5 mm, the width of 1.5 mm long circular pad can be used, this kind of pad is most common in the pin pad of integrated circuit. For the diameter of pads beyond the scope of the above table, the following formula can be used to select: hole with diameter less than 0.4mm: D/ D = 1.5-3; Holes with diameters greater than 2rran: D/ D =1.5-2 (where: D is the diameter of pads and D is the diameter of inner holes)

2. The distance between the edge of the inner hole of the pad and the edge of the printed board should be greater than 1 mm, so as to avoid the defect of the pad during processing.

3. When the wire connected with the pad is relatively thin, the connection between the pad and the wire is designed into a droplet shape, which is not easy to peel the pad, and the wire and the pad is not easy to disconnect.

4. Adjacent pads to avoid into an acute Angle or large area of copper foil. An acute Angle will cause wave soldering difficulties, and there is a danger of bridging, large area of copper foil due to excessive heat dissipation will lead to difficult welding.