JPH0746659B2 - Chip inductor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip inductor used in electronic devices such as television receivers and video tape recorders, and communication devices.

2. Description of the Related Art Electronic devices represented by television receivers and video tape recorders have made great progress in performance and packaging in recent years. Among them, in terms of mounting, a large amount of chip parts are adopted to realize high-density mounting, and for example, a liquid crystal television that fits in a pocket and a video camera that integrates a camera and a video device have been commercialized. In terms of performance, the circuits have been digitized, and compact disc players,
Digital televisions have been commercialized.

Against this background, chip components have been required to have higher performance, one step further, from the stage of simply eliminating lead wires from conventional leaded components to achieve chip formation.

In the case of fixed inductors (hereafter called chip inductors) that are made into chips, it is traditionally several MHz from the audio frequency band.
However, it is required to operate in the tens to hundreds of MHz band, and the tolerance is ± 20% to ± 10% in the past. 5
% Tolerances are being requested.

However, the chip inductor used in the frequency band of several tens of MHz or more has a small inductance value of several μH to several nH, and it is very difficult to realize a tolerance of ± 5%.

FIG. 3 and FIG. 4 show an example of a conventional chip inductor.

In FIG. 3, 10 is a ceramic substrate made of alumina or the like, and electrodes 11a and 11b are provided on both ends thereof. 12 is a ceramic bobbin such as alumina, around which copper wire is
13 is wound to form a coil element 14. Coil element 14
Is fixed on the main surface of the ceramic substrate 10 with an adhesive or the like,
Extra lines at both ends are electrodes provided at both ends of the ceramic substrate 10.
11a and 11b are electrically connected to each other.

In the structure of the conventional example shown in FIG. 4, a groove 15 is provided in the central portion of the bottom surface, and a ceramic substrate 17 which also functions as a bobbin is provided with electrodes 16a and 16b on the bottom surface excluding the groove 15.
A copper wire 18 is wound around the center of the copper wire 17, and both ends of the copper wire 18 are electrically connected to the electrodes 16a and 16b.

Problems to be Solved by the Invention In such a conventional chip inductor, since the number of windings of the copper wire is about 10 times in order to obtain an inductance value of about 1 μH or on the order of nH, even if the same winding is used, It has a drawback that the inductance value greatly varies depending on (interval between copper wires, etc.). Further, since the copper wire is exposed, there is a drawback that automatic mounting by a mounting machine cannot be performed.

Means for Solving the Problems In order to eliminate the drawbacks of the conventional chip inductor, the chip inductor of the present invention is provided with grooves at regular intervals on the main surface of a quadrangular prismatic or plate-shaped core having electrodes on the end faces. , A copper wire is embedded in the groove and wound, both ends of the winding are electrically connected to the electrodes of the core, and a heat resistant resin is embedded in the groove containing the copper wire. The surface is almost smooth.

Action The action of the present invention by the above means is that the core is provided with grooves at regular intervals, and the copper wires are embedded in the grooves and wound to keep the intervals of the copper wires always constant and at the same time Prevents the suction nozzle of the mounting machine from directly contacting the copper wire during mounting.

In addition, heat-resistant resin is embedded in the groove after winding to smooth the main surface to prevent air leakage from the suction nozzle of the mounting machine, and also to prevent copper from heat during soldering (reflow and dip). The line can be protected.

Examples The present invention will be described in detail below based on examples.

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view of this embodiment taken along the line AA 'in FIG. In both figures, 1 is a quadrangular prismatic or plate-shaped core, and alumina was used in this embodiment, but this is a material with little loss in a high frequency region and heat resistance (at least it can withstand heat during soldering). .) Is acceptable. 2a and 2b are electrodes, which are formed by baking Ag-Pd. Three
Is a heat resistant resin, and for example, an epoxy resin can be used. 4 is a copper wire, and a urethane coated copper wire was used.

In the present embodiment having the above-described configuration, the core 1 has a square shape as shown in the drawing, and is a so-called square type chip inductor. In the core 1, grooves 5 having a quadrangular cross section are formed in a spiral shape at regular intervals on the main surface, that is, the upper and lower surfaces and side surfaces, and copper wires 4 are embedded in the grooves 5.

In the present embodiment, the grooves 5 are provided on the entire upper and lower surfaces and the main surfaces of the side surfaces. However, when the mounting method only by reflow is adopted, the grooves are provided only on the upper and lower surfaces or only on the upper surface, and the other main surface portions are not provided. The copper wire is still practical enough to be exposed.

Further, in the present embodiment, Ag-Pd alloy is used for the electrodes 2a and 2b, but when the core 1 is made of heat-resistant plastic or the like that cannot withstand the baking temperature of Ag-Pd (around 1000 ° C). For the electrodes 2a and 2b, it is necessary to prevent an excessive temperature load from being applied to the core 1 by, for example, electroless plating or attaching a metal plate.

EFFECTS OF THE INVENTION As described above, according to the present invention, by providing a groove on the main surface of the core, and embedding a copper wire in the groove and winding the same, the interval between the copper wires can be kept constant. The variation in the inductance value due to the number of turns becomes extremely small, and even when a tolerance of about ± 5% or higher is required, the production can be performed with good yield.

Further, as described above, by embedding a copper wire in the groove, further embedding a heat resistant resin in the groove, and smoothing the resin surface, automatic mounting by a mount machine is possible,
In addition, it has the advantage that the copper wire can be protected during soldering, which is of great industrial value.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the chip inductor of the present invention, FIG. 2 is a sectional view of this embodiment, and FIGS. 3 and 4 are perspective views of a conventional example. 1 ... Core, 2a, 2b ... Electrode, 3 ... Heat resistant resin, 4 ...
… Copper wire, 5… Groove.

Claims (1)

[Claims] 1. A quadrangular prismatic or plate-shaped core having electrodes on its end faces is provided with grooves at regular intervals on the main surface, copper wires are embedded in the grooves and wound, and both ends of this winding are A chip inductor in which a heat-resistant resin is electrically connected to the electrodes of the core and a heat-resistant resin is embedded in the groove containing a copper wire so that the main surface is substantially smooth.