FAQ

Magnetic beads are composed of wires passing through ferrite, with very low DC resistance and impedance at low frequencies, and have almost no effect on DC signals. At high frequencies (above tens of megahertz), the impedance of magnetic beads is relatively high, and high-frequency electromagnetic fields generate eddy currents on ferrite materials, converting high-frequency interference signals into heat and dissipating them. Magnetic beads are commonly used for power filtering and high-frequency signal circuit filtering in high-frequency circuit modules to suppress EMI interference.

Inductance is composed of a coil and a magnetic core, with a small DC resistance and a large inductance. Inductance is commonly used for filtering in mid to low frequency circuits, focusing on suppressing conductive interference. Its application frequency is below tens of megahertz.

1. Abnormal mechanical stress/external force can cause cracks or damage to the body, resulting in an open circuit of the internal electrode.
2. Overcurrent causes cracks or damage to the body, resulting in melting and short circuiting of the internal electrodes.
3. Poor soldering: oxidation and rusting of the end electrode, uneven or too thin electroplating thickness of the end electrode, asymmetrical dimensions on both sides of the end electrode, and other defects such as standing a monument.
4. The product itself is of poor quality, resulting in insufficient high temperature resistance of the parts.

 The full name of magnetic beads is ferrite magnetic bead filter, which is an anti-interference component used to filter out high-frequency noise and consume it in the form of heat. When choosing magnetic beads, two aspects should be considered: one is the situation of noise interference in the circuit, and the other is the magnitude of the current that needs to be passed through. Choose a model with a higher impedance at the center frequency of the noise, but it is not necessarily better to have a higher impedance because the higher the impedance, the higher the DC resistance and the greater the attenuation of the useful signal; Then look at the current, and if used in the power cord section, choose a model with a higher rated current.

The principle of magnetic beads is basically similar to that of inductors. When using inductors, we hope that their losses are as small as possible. In magnetic beads, we need to use their losses to eliminate high-frequency components that we do not need. When current flows through a wire, a circular magnetic field is generated around the wire. A magnetic ring with a relatively high magnetic permeability is placed on the wire, and there will be a relatively large circular magnetic field inside the magnetic ring. If the current is changing, then the magnetic field is also changing. According to the law of electromagnetic induction, a changing magnetic field generates an electric field, which is a circular electric field. If the resistivity of the magnetic ring is not infinite at this point, the circular electric field will generate a circular current, which generates heat. This loss is called eddy current loss. The patch type magnetic beads commonly used in our practice also suffer from eddy current losses.