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| Some experience about the width and the copper vias. |
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We generally have a sense when drawing PCB, which high current will need thick lines (eg 50mil, or even more), low current signal can be thin (eg 10mil). For some electromechanical control systems, sometimes traces of instantaneous current can reach more than 100A, so relatively thin line will cause the problem.
A basic rule of thumb is: 10A / square mm, that is, the current cross-sectional area of 1 square mm traces safely through current value is 10A. If the width is too small, then, when a large current through the wire will be burned down. Of course, the current energy burn traces should follow the formula: Q = I * I * t, for example, for a 10A current alignment, the sudden appearance of a 100A current glitch, the time of duration is us level, the 30mil wire it can afford to live. (At this time will arise another problem ?? stray inductance of the wire, the glitch counter electromotive force will produce a strong role in the inductor, which may damage other devices. Finer longer stray wire the larger the inductance, so in fact the length of the wire is also integrated to be considered)
Generally PCB drawing software tend to several options of the components pins for via copper pads: rectangular spokes, the spokes 45 degree angle, straight shop. What is the difference? Novices often do not care about, pick one of appearance on the list. Actually not. There are two main considerations: First, it can not heat so fast, the second will consider the over-current capability.
Using straight paved the way that the pad over-current ability is very strong, the high-power loop device pin must be used in this way. While its thermal performance is also very strong, although the work is good for heat dissipation device, this is a challenge to the circuit board welding personnel, because fast cooling pads are not easy to hang tin, often you need to use a larger wattage soldering iron and higher soldering temperature, reducing production efficiency. Cartesian angle and 45 spokes spokes will reduce pin contacted area with the copper foil, heat slowly, it is much easier to weld together. So Choose connection via pads copper will according to applications, over-current capability and cooling capacity are considered together, a low-power signal line do not use straight paved, but for a large current through the pads have to be straight paved. As for the right angle or a 45 degree angle will see the beauty.
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