PCB circuit board - 8mil vias can carry too much current

To answer the question "How much current can an 8mil via carry?", we first need to understand what knowledge the question mainly applies to. The answer is circuit boards. So, let's get back to the question itself. What is "8mil"? It refers to the diameter of the via (through hole), expressed as 8 thousandths of an inch. Mil is also called milli-inch, which is a unit of length. 1mil is equal to 0.0254 mm, so 8mil is equal to 0.2032 mm.

"Via" refers to a common hole drilled at the intersection of the wires that need to be connected on each layer in double-sided and multi-layer boards to connect the printed wires between layers.

Then a question arises, is an 8mil via diameter considered large? It can be considered a smaller size in the electronics manufacturing industry. Typically, the diameter of a via can range from tens of microns to several millimeters, depending on the specific application and design requirements. An 8mil via diameter is relatively small and is commonly found in the manufacture of precision electronic devices or high-density circuit boards. However, whether it is considered large or small also needs to consider the specific application context and design requirements. For some applications, an 8mil via may be considered a larger size; while for other applications, it may be considered a smaller size. So it depends on the situation.

So how much current can an 8mil via carry? Generally speaking, an 8mil (0.008 inch) via can carry a relatively small current in a standard PCB design. The specific current carrying capacity depends on the via design, material, environment and other factors, so it is difficult to give an exact value. Generally speaking, 0.1 is the safest current. The current size is not only related to the trace width, but also to the copper thickness and temperature. If you want to consider actual use, you need to consider many aspects. A through hole with an 8mil diameter, a hole wall copper thickness of 25um, and a temperature rise of 25 degrees can carry a maximum current of 1.

The flow capacity of a via is determined by the hole diameter. To calculate the flow capacity of a via, you need to know the inner wall thickness of the via, which is generally at least 15um-17um. If you know the inner wall thickness, you can calculate the corresponding line width and know the flow capacity.