A high-insulation multilayer planar transformer (1) includes a pair of iron cores (20) and a circuit board integration (10a). The circuit board integration (10a) is stacked between the iron cores (20) and has a through hole (100a). The circuit board integration (10a) includes a first to a third insulating layers (11a, 12a, 14a) and a first to a second coil windings (13a, 15a). The first and third insulating layers (11a, 14a) include at least two insulating plates (111a, 141a) stacked with each other respectively. The second insulating layer (12a) includes at least one insulating plate (121a). The coil winding (13a, 15a) is disposed between the adjacent insulating layers and surrounds the through hole (100a) planarly. Therefore, the reinforced insulation requirement of safety regulations may be achieved.

An inductor component comprising a spiral wiring wound on a plane; first and second magnetic layers located at positions sandwiching the spiral wiring from both sides in a normal direction relative to the plane of the wound spiral wiring; a vertical wiring extending from the spiral wiring in the normal direction to penetrate at least the inside of the first magnetic layer; and an external terminal disposed on at least a surface of the first magnetic layer to cover an end surface of the vertical wiring. The first magnetic layer is larger than the second magnetic layer in terms of the area of the external terminal viewed in the normal direction, and when A is the thickness of the first magnetic layer and B is the thickness of the second magnetic layer, A/((A+B)/2) is from 0.6 to 1.6.

An on-chip inductor structure includes first and second winding portions symmetrically arranged in an insulating layer by a symmetrical axis. Each of the first and second winding portions includes first and second semi-circular conductive lines concentrically arranged from the inside to the outside. First and second input/output conductive portions are disposed in the insulating layer along the extending direction of the symmetrical axis, to respectively and electrically couple the first ends of the outermost semi-circular conductive lines. A conductive branch structure is disposed in the insulating layer along the symmetrical axis and between the first and second input/output conductive portions, and electrically coupled to first ends of the innermost semi-circular conductive lines. The conductive branch structure has a grounded first end and a second end is electrically coupled to a circuit and is opposite the first end of the conductive branch structure.

A manufacturing method of transformer circuit board includes following steps: plate stamping, forming a plurality of metal plates with a stamping mold; primary layering, layering the metal plates that are in alignment with each other between two outer insulation layers, with an inner insulation layer disposed between the two metal plates; primary pressing, hot pressing the metal plates to fix the metal plates between the two outer insulation layers; secondary layering, layering another metal plate on the outer side of the two outer insulation layers, respectively, corresponding to the positions of the previously layered metal plates; secondary pressing, hot pressing the metal plates on the outer side of the outer insulation layers, and printing to form a solder mask layer on the outer insulation layers. Finally, cutting to form a transformer circuit board with low leakage inductance and high EMI shield.

A coating layer is used to encapsulate winding turns of an insulated conductive wire of a coil that is encapsulated by a magnetic material containing magnetic particles so as to prevent the magnetic particles from damaging the insulated insulating layer of the insulated conductive wire of the coil when the magnetic material is pressed to form a magnetic body, thereby avoiding unwanted short circuits that are caused by the magnetic particles and damaged portions of the insulated conductive wire.

In the coil component, the maximum reference surface height of the entire wall of the outermost wall and the innermost wall is the same as the reference surface height of the winding part of the coil, that is, equal to or less than the reference surface height of the winding part of the coil. In addition, in both the outermost wall and the innermost wall, the reference surface height of the second side surface is lower than the reference surface height of the winding part of the coil. In this case, in the vicinity of the upper surface of the outermost wall and the innermost wall, the magnetic flux toward the main surface side of the substrate is suppressed from being blocked by the outermost wall and the innermost wall, and the magnetic flux circulation is improved. Thus, the coil characteristics of the coil component are improved.

A balanced-to-unbalanced (balun) transformer includes a primary inductor coupled to an unbalanced terminal and a secondary inductor coupled to a balanced terminal. The primary inductor is configured on a second layer and a third layer of a four-layer symmetrical stack-up. The secondary inductor is configured on a first layer and a fourth layer of the four-layer symmetrical stack-up. The primary inductor includes a first primary winding disposed on the second layer and a second primary winding disposed on the third layer. The secondary inductor includes a first secondary winding disposed on the first layer and a second secondary winding disposed on the fourth layer.

A transformer element includes: a primary coil including a plurality of primary partial coils having a central axis located on one straight line in an in-plane direction of an insulating film; and a secondary coil including a plurality of secondary partial coils arranged within the insulating film and having a central axis located on the one straight line. One or more of the primary partial coils are each interposed between a pair of the secondary partial coils, or one or more of the secondary partial coils are each interposed between a pair of the primary partial coils in plan view.

A coil component includes: a support substrate; first and second coil portions disposed on the support substrate to be spaced apart from each other; a body surrounding the support substrate and the first and second coil portions; and a plurality of external electrodes disposed on a surface of the body, wherein each of the first and second coil portions includes a coil pattern and a lead pattern connected to the coil pattern and exposed from the surface of the body, and a width of an exposed portion of the lead pattern exposed from the surface of the body is greater than a width of each of the coil pattern and the plurality of external electrodes.

A coil component includes a body, a support portion disposed in the body, a coil portion disposed on a first surface of the support portion, a lead portion disposed on a second surface of the support portion facing the first surface of the support portion and connected to the coil portion, and a via penetrating through the support portion to connect an inner end portion of the coil portion and an inner end portion of the lead portion to each other, wherein the coil portion includes a first conductive layer embedded in the support portion and having a first surface exposed to or facing the first surface of the support portion, a second conductive layer disposed on the first surface of the first conductive layer, and a third conductive layer disposed on the second conductive layer and protruding from the first surface of the support portion.