Chipinductors are also known as power inductors, high current inductors and surface-mount high power inductors.It has the characteristics of miniaturization, high quality, high energy storage and low resistance.
The inductance in general electronic circuit is hollow coil, or coil with magnetic core, which can only pass through a small current and bear a lower voltage.And the power inductor also has hollow coil, also has the magnetic core, the main characteristic is to use the thick wire winding system, can withstand tens of ampere, hundreds, thousands, even tens of thousands of ampere.
The power patch inductance is divided into two kinds: with and without magnetic cover, mainly composed of magnetic core and copper wire.In the circuit mainly play the role of filtering and oscillation.
Inductance classification of SMD
There are four main types of chip inductors, namely wound inductors, laminated inductors, braided inductors and thin-film chip inductors.
Commonly used is winding type and laminated type of two types.The former is the product of miniaturization of traditional wound inductors.The latter is made by multilayer printing technology and lamination production process, and the volume is smaller than the winding chip inductor, which is the key product in the field of inductor components.
It is characterized by wide range of inductance (mH ~ H), high precision of inductance, small loss (i.e., large Q), large permissible current, strong inheritance of manufacturing technology, simple, low cost;
But the downside is that further miniaturization is limited.Ceramic core inductors can maintain a stable inductance and a fairly high Q value at such a high frequency, thus occupying a place in the high-frequency circuit.
It has good magnetic shielding, high sintering density and good mechanical strength.The disadvantages are low qualification rate, high cost, small inductance and low Q value.
Compared with wound chip inductors, it has many advantages: small size, conducive to the miniaturization of the circuit, magnetic circuit closed, will not interfere with the surrounding components, will not be adjacent to the interference of components, is conducive to high-density installation of components;Integrated structure, high reliability;Heat resistance, good weldability;Neat shape, suitable for automatic surface installation production.
Thin film chip
It has the characteristics of high Q, high precision, high stability and small volume in microwave frequency band.Its internal electrodes are concentrated on the same layer, and the magnetic field distribution is concentrated, which can ensure that the device parameters change little after installation, and it presents good frequency characteristics above 100MHz.
The weaving type
The characteristic is that the unit volume inductance at 1MHz is larger, smaller and easier to install on the substrate than other chip inductors.A miniature magnetic element used for power processing.
SMD inductance is an electromagnetic induction element made of insulated wire.Belongs to the common inductance element.
The role of chip inductor: through dc resistance ac this is simply said to isolate the ac signal, filter or form a resonant circuit with capacitors, resistors, etc.
The role of tuning and frequency selective inductance: inductance coil and capacitor in parallel can form LC tuning circuit.
SMD inductance in the circuit any current, will generate a magnetic field, the magnetic flux of the magnetic field on the circuit.
When the current of SMT inductor changes, the dc voltage potential generated in SMT inductor will prevent the current from changing.
When the current passing through the inductor coil increases, the self-induced electromotive force generated by the inductor coil decreases as the current passing through the inductor coil decreases. The self-induced electromotive force is in the same direction as the current, preventing the current from decreasing and releasing the stored energy to compensate for the decreased current.
The opposite direction prevents the current from increasing, and converts some of the electrical energy into magnetic field energy, which is stored in the inductance.Therefore, after inductance filtering, not only the pulsation of load current and voltage decreases, the waveform becomes smooth, but also the conduction Angle of rectifier diode increases.
Shielding SMD inductance and general SMD inductance function is different, the general SMD inductance in the circuit is not shielded, used in the circuit inductance can not play the desired effect, shielding SMD inductance can shield the current instability in some circuits, play a good blocking role.
Shielding inductive complete metal shield will positively charged conductor surrounded by at the inner side of the shield will be induced with a charged conductor equal amounts of negative charge, outer appearance and charged conductor of the same amount of positive charge, if the metal shield grounding, the outside of the positive charge will flow into the earth, the lateral electric field will not exist, which are positively charged conductor of the electric field shielding in the metal mask.
Shielding inductance also plays a coupling role in the circuit. In order to reduce the coupling interference voltage of alternating electric field to sensitive circuit, the inductance can set a metal shield with good conductivity between the interference source and the sensitive circuit and ground the metal shield.
The coupling interference voltage of alternating electric field to sensitive circuit depends on the product of alternating electric field voltage, coupling capacitance and metal shield grounding resistance.As long as the metal shield is well grounded, the coupling interference voltage of the alternating electric field to the sensitive circuit can be reduced.
The main factor of electric field shielding is reflection, so the thickness of shielding body should not be too large, and the main factor is structural strength.
You May Like
Post time: Aug-24-2019