We can see that the middle and high-end data lines usually consist of several parts: plastic shell - woven mesh - aluminum foil - copper core. The innermost conductor core (copper core) wrapped by colored insulators is used to transmit data signals and current, and the outer shell is used to protect the wires; what is the role of the intermediate woven mesh and aluminum foil layer?
An important role of the data line is to transmit data signals. However, there may be various messy interference information around us when we use it. We think about it. If these interfering signals enter the inner conductor of the data line and are superimposed on the originally transmitted signal, is it possible to interfere or change the original transmitted signal, causing useful signal loss or problem?
These woven mesh and aluminum foil layers protect and shield the information we want to transmit. Of course, not all data lines have two layers of shielding, some have multiple shielding layers, some have only one layer, or even none. Shielding is the separation of metal between two spatial regions to control the induction and radiation of electric, magnetic and electromagnetic waves from one region to another. Specifically, the shield core is used to surround the conductor cores to prevent them from being affected by external electromagnetic fields/interference signals, and also to prevent the interference electromagnetic fields/signals from spreading out in the lines.
The shielding layer of the data line is mainly made of non-magnetic materials such as copper and aluminum, and is generally a braided copper mesh (aluminum-magnesium woven mesh) or a copper poise (aluminum poise, etc.), and their thickness is very thin, which is much smaller than the metal material used. The depth of the skin. It should be noted that one end of it must be connected to the signal ground of the circuit, because the effect of the shielding layer is mainly not caused by the reflection and absorption of the electric field and the magnetic field by the metal body itself, but is caused by the grounding of the shielding layer and grounding. Different forms will directly affect the shielding effect.
The production process of ordinary shielded wire is as follows:
Stranded copper - extruded (inner core) - winding (internal core) - aluminum bale - braided (or entangled) - extruded (outside) - roll package
In the electronic connection line, we often use letters to identify the materials used to introduce them, such as:
AL stands for aluminum, such as: 4C+AL, which means a 4-core wire with aluminum.
AB stands for weaving, such as: 4C+80/0.10AB, which means 4-core braided wire. The weaving specification is 80 pieces of copper wire with 0.10mm outer diameter.
S stands for winding, such as: 4C+60/0.10S, which means 4C winding wire, and the winding specification is 60 copper wires with an outer diameter of 0.10mm.