| 摘要 |
A printed circuit board includes a layer. A layer of copper is covered on a surface of the layer. A through hole extends through the printed circuit board. A thermal engraving is defined in the surface of the layer, surrounding the through hole and without being covered by the layer of copper. The thermal engraving includes a first opening and a second opening. The first opening of the thermal engraving faces an output terminal of the power supply, and is non-contiguous with the second opening. |
