The inductor includes a core, a floor plate, a first protection layer, and a second protection layer. The core includes a first flange, a second flange, and a middle section, where the middle section is sandwiched between the first and second flange, the middle section is wound around by a coil, the first and second flanges respectively have a side upon which at least an electrode is configured, and the coil is connected to the electrodes. The floor plate is adhered to other sides of the first and second flanges. The first protection layer completely covers the floor plate, and partially covers the first and second flanges, and the middle section. The electrodes on the first and second flanges are exposed outside the first protection layer. The second protection layer completely covers the coil around the middle section.

BACKGROUND OF THE INVENTION

(a) Technical Field of the Invention

The present invention is generally related to inductors, and more particular to an improved structure of inductors.

(b) Description of the Prior Art

Generally, an inductor, after wire winding, is coated and sealed by an adhesive applied from a dispenser. The adhesive is usually an ultraviolet (UV) curable resin, which is a resin blended with some light sensitive material (photosensitizer/photoinitiator) that would be quickly solidified after being exposed to UV light.

As shown inFIGS.1and2, an inductor includes a core100configured with electrodes110, a coil120, and a protection layer200made of UV curable resin wrapping and protecting the core100. The inductor is fixed on a circuit board through surface mount technology (SMT).

Usually, the protection layer200is formed by placing the core100in a tank and injecting UV curable resin into the tank by a dispenser. As the electrodes110have to be exposed outside the protection layer200for connection to the circuit board, the coil120is partially covered by the protection layer200, as shown inFIG.1. As such, the coil120may be damaged when the inductor is fixed to the circuit board. In addition, solder beads may spatter on the coil120as the inductor goes through reflow, causing the coil120to be short-circuited.

SUMMARY OF THE INVENTION

The present invention teaches an inductor, which includes a core, a floor plate, a first protection layer, and a second protection layer. The core includes a first flange, a second flange, and a middle section, where the middle section is sandwiched between the first flange and the second flange, the middle section is wound around by a coil, the first flange has a first side upon which at least an electrode is configured, the second flange has a second side upon which at least an electrode is configured, and the coil is connected to the electrodes. The floor plate is adhered to other sides of the first and second flanges. The first protection layer completely covers the floor plate, and partially covers the first flange, the second flange, and the middle section. The at least an electrode on the first side and the at least an electrode on the second side are exposed outside the first protection layer. The second protection layer completely covers the coil around the middle section.

The first protection layer has a vertical coverage of the first flange, the second flange, and the middle section up to the first side the first flange and the second side of the second flange but not over the electrodes thereupon.

In an embodiment, the first protection layer is made of ultraviolet (UV) curable resin or insulative resin.

In an embodiment, the first protection layer is made of a mixture of UV curable resin and magnetic powders.

In an embodiment, the second protection layer is made of UV curable resin or insulative resin.

In an embodiment, the second protection layer is made of a mixture of UV curable resin and magnetic powders.

The inductor has the following advantages. Firstly, the coil is fully protected by being completely covered by the second protection layer so that the coil does not suffer external impact when the inductor is installed on a circuit board, and the coil is prevented from being short-circuited by solder beads splattered during reflow. Secondly, the electrodes on the first flange and the second flange are kept exposed outside the first protection layer so that they may be conveniently connected to the circuit board.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIGS.3and4, an inductor according to an embodiment of the present invention includes a core1, a floor plate2, a first protection layer3, and a second protection layer4.

The core1includes a first flange11, a second flange12, and a middle section13. The middle section13is sandwiched between the first flange11and the second flange12to form an I-like shape. The middle section13is wound around by a coil131. Each of the first flange11and the second flange12has a side upon which electrodes are configured. The coil131's two ends are respectively connected to the electrodes. The electrodes are made of highly conductive material such as silver. More specifically, the first flange11has a first side111and the second flange12has a second side121. The first side111is configured with a first electrode112and a second electrode113. The second side121is configured with a third electrode122and a fourth electrode123. The coil131includes a number of windings. The windings of the coil131are respectively connected to the first electrode112, the second electrode113, the third electrode122, and the fourth electrode123.

The first flange11has another side opposite to the first side111with no electrode. The second flange12also has another side opposite to the second side121with no electrode. The floor plate2is adhered to the first flange11's another side and to the second flange12's another side by UV curable resin. The floor plate2, by providing a flat and planar surface to the core1, facilitates the adhesion of the inductor to the circuit board in a surface-mount device (SMD) process.

The first protection layer3completely covers the floor plate2, and partially covers the first flange11, the second flange12, and the middle section13. The electrodes are exposed outside the first protection layer3. The first protection layer3may be made of UV curable resin, insulative resin, or a mixture of UV curable resin and magnetic powders. The insulative resin may be epoxy resin or polyimide resin. More specifically, the first protection layer3has a vertical coverage range including the first flange11, the second flange12, and the middle section13, up to the first side111of the first flange11and the second side121of the second flange12by not over the first electrode112, the second electrode113, the third electrode122, and the fourth electrode123thereupon, so that subsequently the electrodes are available for connection to the circuit board.

The second protection layer4completely covers the coil131around the middle section13. The second protection layer4may be made of UV curable resin, insulative resin, or a mixture of UV curable resin and magnetic powders. The insulative resin may be epoxy resin or polyimide resin.

To form the inductor, the core1and the floor plate2are stacked in a tank into which

UV curable resin (or insulative resin or a mixture of UV curable resin and magnetic powders) is injected in a first injection through a dispenser to form the first protection layer3. The protection layer3partially covers the first flange11, the second flange12, and the middle section13(including the coil131around the middle section13). As the coil131is exposed, UV curable resin is injected again in a second injection into the tank to form the second protection layer4that completely covers the middle section13and the coil131.

The inductor as described has the following advantages. Firstly, the coil131is fully protected by being completely covered by the second protection layer4so that the coil131does not suffer external impact when the inductor is installed on a circuit board, and the coil131is prevented from being short-circuited by solder beads splattered during reflow. Secondly, the electrodes on the first flange11and the second flange12are kept exposed outside the first protection layer3so that they may be conveniently connected to the circuit board.