JPH0227530Y2 - - Google Patents

Description

[Detailed description of the invention] Field of the invention In this invention, a pair of external extraction electrodes are formed on the outward main surface of one flange of the core, and each of these external extraction electrodes extends to each side of the flange. The present invention relates to a chip coil formed by using a chip coil, and particularly relates to an improvement to prevent a decrease in Q.

Description of prior art Figures 1 to 3 and Figures 4 to 6
The figure shows only the core of a conventional chip coil that is of interest to this invention, and two representative examples are shown.

As shown in these figures, in both examples the core comprises a winding core 1 holding a coil winding (not shown), and at each end of this winding core 1:
First and second flanges 2, 3 are formed, respectively. In these examples, the first flange 2
is larger than the second flange 3. Each of the flanges 2 and 3 has a rectangular shape. Therefore, for example, the first flange 2 is formed with a pair of planar side surfaces 4 that sandwich the winding core 1 and face each other. . A pair of external extraction electrodes 5 are formed on the outwardly facing main surface of the first flange 2 . Although not shown in these external extraction electrodes 5,
Lead wires forming each end of the coil winding are electrically connected.

Focusing on the formation state of the external extraction electrodes 5 as described above, each external extraction electrode 5 is connected to the first flange 2.
It can be seen that it extends to each side 4 of , forming a side extension 6 there. This side extension 6 is
In the example shown in FIGS. 1 to 3, it is formed only in the center of the side surface 4, and in the example shown in FIGS. 4 to 6, it is formed over almost the entire surface of the side surface 4. The side extension 6 is necessary to increase the adhesion strength of the external lead electrode 5 to the wiring pattern when mounting the chip coil on a printed circuit board, etc., and to check the state of solder adhesion when the chip coil is mounted. In fact, it is proving effective.

However, the formation of the side extensions 6 on the side surfaces 4 as described above has the disadvantage that eddy currents are induced due to changes in magnetic flux, and as a result, the Q of the coil is significantly impaired. In particular, this effect is even greater when the side surface 4 has a wide width a (Fig. 3).
The formation of the side extension portion 6 as shown in FIGS. 4 to 6 has a problem in that it cannot be applied to such a wide width a. On the other hand, in order to increase the adhesion strength of the external extraction electrode 5, it is necessary to increase the area of the side surface extension part 6, and from this point of view, the formation mode as shown in FIGS. However, there were cases in which the performance could not be fully satisfied. For example, in the case of solder immersion or jet soldering, the external lead electrode 5 could fall off or be worn out.

Purpose of the invention Therefore, the object of this invention is to provide a shape of a chip coil, particularly the side extension of the external extraction electrode, which satisfies the fixing strength of the external extraction electrode without causing Q deterioration.

Structure of the invention In this invention, the side extension of the external extraction electrode is
They are formed on the planar side surfaces of the flange that face each other with the winding core in between, and are characterized in that they are formed on at least a portion of each side surface excluding the central portion.

Effects of the invention According to this invention, a decrease in Q is advantageously prevented. The reason can be considered as follows. That is, it is known that the closer the magnetic flux is to the winding core, the more the magnetic flux crosses the winding core. This phenomenon,
If applied to a planar side surface, the magnetic flux will cross this planar side surface more near the center. Therefore, if the side extension of the external extraction electrode is formed in a part other than the center of the side as in this invention, this side extension will be located at a position where there is less magnetic flux. Got tired,
This is because the generation of eddy currents can be further suppressed. The adhesion strength of the externally drawn electrode can only be increased by the presence of the side extension, so no matter where the side extension is located, it has no effect in terms of the function of increasing the adhesion strength. No difference.

DESCRIPTION OF EMBODIMENTS Figures 7 to 9 show a first embodiment of this invention, Figures 10 to 12 show a second embodiment of this invention, and Figures 13 to 15 show a second embodiment of this invention. These figures are for explaining each of the third embodiments, and in all of them, only the core made of ferrite or the like of the chip coil is shown. Figures 16 and 17
The figure shows a completed chip coil based on the third example shown in FIGS. 13 to 15. In addition, in these FIGS. 7 to 17, parts corresponding to those shown in FIGS. 1 to 6 described above are given the same reference numerals, and redundant explanation will be omitted.

First, before explaining the features of this invention, the explanation of the chip coil as a finished product will be supplemented with reference to FIGS. 16 and 17.

FIG. 16 shows a coil winding 7, and each of the lead wires 8 serving as each end of the coil winding 7 is drawn out to the outer main surface of the first flange 2, and is drawn out here. , each is electrically connected to the external lead electrode 5 by solder or the like.

Next, the side extension portion 6, which is a feature of this invention, will be explained based on each embodiment.

In the first embodiment shown in FIGS. 7 to 9,
The side extension 6 is completely separated into two parts at the side 4, and each side extension 6 is located on the outside of the side 4.

In the second embodiment shown in FIGS. 10 to 12, the side surface extension 6 is formed to be slightly continuous near the lower edge of the side surface 4, including the central portion, but the main portion thereof is It is missing in the center of the side surface 4 and is separated on both sides of the side surface 4.

In the third embodiment shown in FIGS. 13 to 15, the basic formation state of the side extension 6 is the same as in the second embodiment, but the outline of the side extension 6 is rounded. has been completed.

Incidentally, the side surface extension portion 6 as described above may be made of a metal piece or may be formed by printing.

FIG. 18 is a graph comparing the Q of the chip coil of this invention and the fixing strength of the external lead electrode with that of the conventional chip coil. In Fig. 18, the vertical axis represents Q and electrode adhesion strength (unit:
kgf). Three types of shapes of the side extension portion 6 are schematically shown along the horizontal axis in FIG. 18. A corresponds to the conventional example shown in FIGS. 4 to 6, and B corresponds to the conventional example shown in FIGS. This corresponds to the conventional example shown in FIGS. 1 to 3, and C corresponds to the first embodiment of this invention shown in FIGS. 7 to 9. As is clear from Fig. 18, the Q of the chip coil is
It can be seen that the bonding strength of C is improved in the order of A, B, and C, and that C has almost the same value as A.

FIGS. 19 and 20 are bottom views of the core of still another embodiment of this invention, respectively. These Examples are significant in that they clarify that the planar shape of the first flange in the chip coil to which this invention is applied is not limited to a completely rectangular shape. That is, in any embodiment, the first
The flange 2 satisfies the condition that a pair of planar side surfaces 4 that sandwich the winding core 1 and face each other are formed, and other shapes are arbitrary. The side surface extension 6, which is a characteristic feature of this invention, is formed on this side surface 4.

Note that in FIGS. 19 and 20, the winding core 1 is shown as having a circular cross section. In this way, the shape of the winding core 1 may be rectangular or circular as shown in the other drawings, or may be any other shape. In addition, the external extraction electrode 5
Of course, the shape of is also arbitrary.

Incidentally, in the illustrated embodiment, the side surface extension portions of the external extraction electrodes 5 are located on both sides of the side surface 4, but they may be located on only one side. For example, if the explanation is based on the first embodiment shown in FIGS. 7 to 9, two
One of the two side extensions 6 may be omitted. The formation state of such side extension portion 6 is as follows.
It is only necessary to select it according to the adhesion strength required of the external extraction electrode 5.

[Brief explanation of the drawing]

1 to 3 show a first conventional example,
FIG. 1 is a perspective view of the core, FIG. 2 is a bottom view of the same, and FIG. 3 is a side view of the same. 4 to 6 show a second conventional example, and are a perspective view, a bottom view, and a side view of the core, respectively. 7 to 9 show a first embodiment of this invention, and are a perspective view, a bottom view, and a partial side view of the core, respectively. 10th
Figures 1 to 12 show a second embodiment of the invention, and are a perspective view, a bottom view, and a partial side view of the core, respectively. Figures 13 to 15 show a third embodiment of this invention, and are respectively a perspective view of the core and a perspective view of the core.
They are a bottom view and a partial side view. Figure 16 shows the 13th
16 is a perspective view of a chip coil completed using the core of FIGS. 15 to 15. FIG. FIG. 17 is a bottom view of the chip coil shown in FIG. 16. FIG. 18 is a graph showing the Q and external lead electrode fixing strength of the chip coil C of this invention in comparison with conventional examples (A, B). FIGS. 19 and 20 are bottom views of still other embodiments of this invention, respectively. In the figure, 1 is the winding core, 2 is the first flange,
3 is a second flange, 4 is a side surface, 5 is an external extraction electrode, 6 is a side extension, 7 is a coil winding, and 8 is a leader wire.

Claims (1)

[Claims for Utility Model Registration] First and second flanges are formed at each end of a winding core that holds a coil winding, respectively, to constitute a core, and a main surface facing outside of the first flange comprises a core. is formed with a pair of external lead-out electrodes, each lead-out electrode is electrically connected to a lead-out wire serving as each end of the coil winding, and the first flange is provided with a lead wire that serves as the end of the coil winding. In the chip coil, a pair of planar side surfaces facing each other are formed, and each of the external extraction electrodes extends to each of the side surfaces to form a side surface extension part thereon. A chip coil, characterized in that the side surface extension portion is formed on at least a portion of each side surface excluding the central portion.