What are the requirements for the spacing of wires on printed circuit boards? The editor believes that the spacing between adjacent wires must meet electrical safety requirements, and in order to facilitate operation and production, the spacing should also be as wide as possible. The minimum spacing should be at least suitable for withstanding the voltage. This voltage generally includes operating voltage, additional fluctuating voltage, and peak voltage caused by other reasons. If the relevant technical conditions allow for a certain degree of metal residue between wires, their spacing will decrease. Therefore, designers should take this factor into consideration when considering voltage. When the wiring density is low, the spacing between signal lines can be appropriately increased. For signal lines with significant differences in high and low levels, the spacing should be as short and increased as possible.
The minimum width of printed circuit board wires is mainly determined by the adhesion strength between the wires and the insulating substrate, as well as the current value flowing through them. When the thickness of the copper foil is 0.05mm and the width is 1-1.5mm. With a current of 2A, the temperature will not exceed 3 ℃, and a wire width of 1.5mm can meet the requirements. For integrated circuits, especially digital circuits, a wire width of 0.02-0.3mm is usually chosen. Of course, as long as allowed, use wide lines as much as possible. Especially for power and ground wires, the minimum spacing between wires is mainly determined by the worst-case insulation resistance and breakdown voltage between wires. For integrated circuits, especially digital circuits, as long as the process allows, the spacing between wires can be reduced to 5-8mm.
However, for high currents, if the current load is calculated at 20A/square millimeter, when the thickness of the copper foil is 0.5MM (usually this much), the current load with a line width of 1MM (about 40MIL) is 1A. Therefore, a line width of 1-2.54MM (40-100MIL) can meet the general application requirements. For the ground wire and power supply on high-power equipment boards, the line width can be appropriately increased according to the power size. For low-power digital circuits, in order to improve wiring density, a minimum line width of 0.254-1.27mm (10-15MIL) can be met.
On a printed circuit board, there are both high voltage and low voltage circuits. The components of the high voltage circuit and the low voltage part need to be separated and placed separately. The isolation distance is related to the withstand voltage. Usually, the distance on the board is 20mm at 2000V, and it needs to be increased proportionally above this. For example, if a withstand voltage test of 3000V is required, the distance between the high and low voltage lines should be at least 35mm. In many cases, to avoid creepage, slots are also made between the high and low voltage on the printed circuit board. The circuit boards we make also have high and low voltage circuits, with a circuit spacing of 10mm between them.