JPH0416405Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a unit coil laminate consisting of a plurality of unit coils each having a predetermined coil pattern formed on both sides of an insulating base. be.

[Prior Art] In a coil formed by printing technology, a spiral coil pattern is formed on both sides of an insulating base, and the inner peripheral ends of both coil patterns are connected to each other to form a unit coil. A unit coil laminate is constructed by stacking a plurality of coils and connecting them in parallel.

This unit coil laminate is compact and can be particularly reduced in height, making it suitable as a coil for electronic components.

Examples of conventional unit coil stacks are shown in FIGS. 5 through 8. This conventional unit coil stack has four unit coils each having a four-turn coil pattern stacked on top of each other to increase the number of parallel circuits to four.
That is. In order to make it easier to understand, Figure 5 shows only the coil pattern portions (the insulating base and the insulating sheet are omitted) for two of the four circuits, with the distance between the coil patterns being separated from the actual distance. In the figure, vertical broken lines indicate electrical connections between coil patterns.

FIG. 6 is a side view of the outer circumferential outlet portion of FIG. 5, and FIG. 7 is a sectional view taken along the line B-B' of FIG.
The parts omitted from the display in FIG. 5 are shown without being omitted in these figures.

In these figures, 1a to 1d are first to fourth unit coils, respectively, and these unit coils have four-turn spiral coil patterns 3a1, _3a2 to _3d1 , on both sides of insulating bases 2a to 2d, _respectively . 3 Consists of _d2 . The inner circumferential ends of the coil patterns on both sides of each unit coil are electrically connected to each other by a connecting conductor (for example, a through-hole conductor) provided through the insulating base.

The unit coils 1a to 1d are laminated with insulating sheets 4 interposed between them, and insulating plates 5 are arranged at both ends of these laminated bodies. The outer peripheral side outlet portions A ₁ , B ₁ , C ₁ and D ₁ of the coil patterns on the front side of the first to fourth unit coils are connected to each other by the conductor 6A, and Outer peripheral side outlet portions A ₂ , B ₂ , C ₂ and D ₂ of the coil pattern are connected to each other by a conductor 6B, and unit coils 1a to 1d are connected in parallel.

In this type of coil, the coil pattern is formed from a very thin conductor. This is not only because of the manufacturing reason that thinner coil patterns are easier to manufacture when many are connected in parallel, but also because
This is because thinning the coil pattern suppresses eddy currents in the conductive portion and improves high frequency characteristics.

This type of coil has distributed capacitance (hereinafter referred to as distributed capacitance) in addition to inductance, which is used for its original purpose. It is generally desirable for this distributed capacitance to be small; if it is large, the charging current flowing through the distributed capacitance will increase and the original functions of the inductive reactance element and the coil will be impaired.

FIG. 8 shows an equivalent circuit of the above-mentioned unit coil stack, where L ₁ indicates the inductance of each coil pattern, and C ₁ indicates the distributed capacitance of each unit coil. In addition, C ₂ is the distributed capacitance that occurs when unit coils are stacked, and this distributed capacitance is
_C2 does not exist when the unit coil is alone.

[Problem to be solved by the invention] In the above unit coil stack, the charging current flowing through the distributed capacitance is proportional to the product of the interelectrode voltage and the distributed capacitance size and frequency, so the charging current is reduced. To achieve this, the higher the power supply frequency, the smaller the distributed capacitance must be.

On the other hand, distributed capacitance is inversely proportional to the distance between the electrodes. In the unit coil, as shown in Figure 8, there is a distributed capacitance between the coil patterns on both sides of the insulation base.
C ₁ exists, but when unit coils are stacked,
A new distributed capacitance _C2 is generated between the coil patterns of adjacent unit coils. Therefore, when a unit coil laminate is constructed by stacking a plurality of unit coils, the distributed capacitance increases, the charging current increases, and the high frequency characteristics deteriorate. In order to alleviate this inconvenience, it is necessary to reduce the distributed capacitance _C2 by thickening the insulating sheet interposed between the unit coils.

Insulating sheet 4 interposed between unit coils
is the insulating base 2 to which the coil pattern is connected.
Unlike the coils a, 2b, . . . , it is only necessary to have a thickness sufficient to withstand the potential difference in the coil pattern between the unit coils, and the thickness required for this purpose is extremely thin. However, if the insulating sheet is made thicker than the required thickness for voltage resistance in order to suppress the charging current, the thickness of the unit coil laminate will increase, which cancels out the advantages of the unit coil laminate and also increases production costs. .

An object of the present invention is to provide a unit coil laminate that improves high frequency characteristics by reducing the charging current flowing through the distributed capacitance between the unit coils without increasing the thickness of the insulating sheet.

[Means for Solving the Problem] In the present invention, adjacent coil patterns of a plurality of stacked unit coils are made symmetrical with respect to an insulating sheet interposed between them, and a potential difference is created between opposing portions of both coil patterns. Connect the unit coils so that this will not occur.

Therefore, the outer circumferential outlet of the front side coil pattern of the odd-numbered unit coil and the outer circumferential side outlet of the back side coil pattern of the even-numbered unit coil are connected to each other when counted from either end in the stacking direction of the laminate. Then, the outer circumferential outlet portions on the back side of the odd-numbered unit coils and the outer circumferential side outlet portions on the front side of the even-numbered unit coils are connected to each other.

[Operation of the invention] When adjacent coil patterns are made to have a symmetrical shape with respect to the insulating sheet as described above, between points of the adjacent coil patterns that face each other across the insulating sheet (points located at symmetrical positions with respect to the insulating sheet) The potential difference becomes zero. Geometrically, distributed capacitance exists between adjacent unit coils in the equivalent circuit of the present invention, but since the potential difference between each symmetrical point of adjacent coil patterns is zero, the distributed capacitance between the unit coils No charging current flows. Therefore, it is as if distributed capacitance between unit coils does not exist electrically.

For simplicity, we ignore the distributed capacitance between the unit coil stack and the outside (for example, the ground), and let C ₁ be the distributed capacitance between the coil patterns on both sides of the unit coil, and the adjacent coil patterns of the stacked unit coil. If the distributed capacitance between the two is C ₂ , each frequency of the power supply is ω, the power supply voltage is V, and the number of stacked unit coils is n, then the charging current I ₁ that flows in the stack of the present invention and the charging current that flows in the conventional stack The charging current I ₂ is:

I ₁ = jnωC ₁ V I ₂ = jnωC ₁ V + j (n-1) ωC ₂ V From these, the charging current ratio I ₁ /I ₂ is calculated as follows: I ₁ /I ₂ = (nC ₁ ) / {nC ₁ + (n-1)C ₂ }.

Assuming that C ₁ =C ₂ and n is large, the charging current according to the present invention will be about half that of the conventional method.

In addition, since the potential difference between the symmetrical points of adjacent coil patterns is zero, there is no need to consider the thickness in terms of withstand voltage when setting the thickness of the insulating sheet, and it is simply due to the eddy current between the two coil patterns. The thickness of the insulating sheet may be determined in consideration of the insulation performance required to prevent the circulation of the insulating sheet.

Therefore, in the present invention, the thickness of the insulating sheet can be made thinner than the conventional one, not only from the viewpoint of current suppression due to distributed capacitance, but also from the viewpoint of withstand voltage conditions.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 to 4 show an embodiment of the present invention, in which the number of turns of the unit coil is 4, and the number of unit coils is 4.

In FIG. 1, the distance between the coil patterns is shown to be greater than the actual distance, and only the coil pattern portions are shown for two of the four circuits. In FIG. 1, vertical broken lines indicate connections between coil patterns.

Figure 2 is a side view of Figure 1 looking at the outlet on the outer peripheral side;
Figure 3 is a sectional view taken along line A-A' in Figure 1.
Portions omitted in the figures are shown without being omitted in these figures.

FIG. 4 shows an equivalent circuit of an embodiment of the present invention.

In these figures, parts equivalent to those of the conventional example shown in FIGS. 5 to 8 are given the same reference numerals, and 1a to 1d are first to fourth unit coils, respectively. These unit coils each have a four-turn spiral coil pattern 3 _a1 on both sides of the insulating bases 2 a to 2 d.
3 _a2 to 3 _d1 and 3 _d2 are formed of copper foil, and the inner peripheral ends of the coil patterns on both sides of each unit coil are electrically connected to each other through the insulating base. There is. The coil pattern of this unit coil is formed by etching a copper-clad laminate, or bonding spirally formed copper foil to both sides of an insulating substrate. Connections between the inner edges of the coil patterns on both sides of the insulating base can be made through through holes using conductive paint, or by penetrating the board and providing a connecting conductor and soldering both ends to the coil pattern. This can be done by

The unit coils 1a to 1d are laminated with insulating sheets 4 interposed between them, and insulating plates 5 are arranged at both ends of these laminated bodies. The insulating base 2, the insulating sheet 4, and the insulating plate 5 are made of an insulating material such as polyester film.

In this invention, as seen in Figure 1,
Laminated unit coils 1a, 1b, ...adjacent coil patterns _3a2 and _3b1 , _3b2 and _3c1
and 3 _c2 and 3 _d1 have symmetrical shapes with respect to the insulating sheet 4 interposed between them. The connection between unit coils, that is, the connection at the outer circumferential outlet of the coil pattern, is performed using a known method such as soldering the connecting conductor. The outer peripheral side outlet of the front side coil pattern of the odd-numbered unit coil and the outer peripheral side outlet of the rear side coil pattern of the even-numbered unit coil are connected to each other,
The outer circumferential outlet of the coil pattern on the back side of the odd-numbered unit coil and the outer circumferential outlet of the coil pattern on the front side of the even-numbered unit coil are connected to each other.

In this embodiment, the first and third unit coils 1a and 1c from the top in FIGS.
The outer circumferential outlet portions A ₁ and _C 1 of the coil patterns 3 _a1 and 3 _c1 on the front side and the outer circumferential outlet portion B of the coil patterns 3 _b2 and 3 _d2 on the back side of the second and fourth unit coils 1 b and 1 d. ₂ and D ₂ are connected conductor 6A
A terminal is drawn out from the connecting conductor. Also, the first and third unit coils 1a
Outer exits A ₂ and C 2 of coil patterns 3 _a2 and 3 _c2 on the back side of _1c and outer exits of coil patterns 3 _b1 and 3 _d1 on the front side of the second and fourth unit coils 1b and 1d Portions B ₁ and D ₁ are connected by a connecting conductor 6B, and a terminal is drawn out from the connecting conductor.

FIG. 4 shows an equivalent circuit of the unit coil stack of this embodiment. In the figure, the vertical positional relationship of the coil patterns is the same as in Figures 2 and 3, where L ₁ is the inductance of each coil pattern, C ₁ is the distributed capacitance between the front and back coil patterns of each unit coil, and C _{Let 2} ' be the distributed capacitance between the coil patterns of adjacent unit coils. In FIG. 4, terminals T ₁ and T ₂ are terminals drawn out from connection conductors 6A and 6B, respectively.

When adjacent coil patterns are made to have symmetrical shapes with respect to the insulating sheet as described above, the potential difference between points of the adjacent coil patterns that face each other across the insulating sheet 4 (points located at symmetrical positions with respect to the insulating sheet 4) is Becomes zero. In the equivalent circuit of the present invention shown in Fig. 4, it is assumed that distributed capacitance C ₂ ' exists between adjacent unit coils, but since the potential difference between each symmetrical point of adjacent coil patterns is zero, No charging current flows through.
Therefore, it is as if the distributed capacitance C ₂ ' between the unit coils does not exist electrically.

As described above, according to the present invention, distributed capacitance between unit coils can be electrically eliminated, so that high frequency characteristics can be improved. In addition, the thickness of the insulating sheet can be determined by taking into consideration the insulation performance necessary to prevent eddy current from circulating between the coil patterns, so the thickness can be made sufficiently thin, and the unit coil It is possible to take advantage of the advantages of a laminate.

In the above example, the number of unit coils is 4, but in general, when n unit coils are stacked, the coil pattern of each unit coil is formed in the same way, and the n unit coils are connected in the same way. By connecting the outer circumference side lead portions of the coil patterns, it is possible to obtain a unit coil laminate of the present invention in which n coils are connected in parallel.

[Effects of the invention] As described above, according to the invention, since the charging current is prevented from flowing through the distributed capacitance between the unit coils, the charging current of the unit coil stack can be reduced and the high frequency characteristics can be improved. There are advantages that can be achieved. Furthermore, since it is not necessary to increase the thickness of the insulating sheet interposed between the unit coils in order to reduce the distributed capacitance between the unit coils, the insulating sheet can be made thinner to reduce the thickness direction dimension of the unit coil stack. The effect that can be obtained is obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the arrangement and connection of the coil patterns in the embodiment of the present invention, FIG. 2 is a side view of the embodiment of FIG.
The figure is a sectional view taken along the line A-A' in Figure 1, Figure 4 is an equivalent circuit of an embodiment of the present invention, and Figure 5 is a perspective view showing the arrangement and connection of coil patterns in a conventional unit coil stack. , FIG. 6 is a side view of the unit coil laminate shown in FIG. 5, looking at the outer outlet part, FIG. 7 is a sectional view taken along line B-B' in FIG. 5, and FIG. 8 is a conventional unit coil laminate. This is the equivalent circuit of 1a to 1d...unit coil, 2a to 2d...
...Insulation base, 3 _a1 , 3 _a2 to 3 _d1 , 3 _d2 ... Coil pattern, 4 ... Insulation sheet, 5 ... Insulation plate,
6... Connection conductor.

Claims (1)

[Claims for Utility Model Registration] A plurality of unit coils are provided in which coil patterns are formed on both sides of an insulating base and the inner peripheral ends of the coil patterns are connected to each other, and the plurality of unit coils are connected through an insulating sheet. In a unit coil laminate in which the plurality of unit coils are stacked together and connected in parallel to each other, adjacent coil patterns of the plurality of stacked unit coils are shaped symmetrically with respect to the intervening insulating sheet, and odd-numbered Connect the outer circumferential side outlet of the coil pattern on the front side of the unit coil and the outer circumferential side outlet of the coil pattern on the back side of the even numbered unit coil, and connect the outer circumferential side outlet of the back side of the odd numbered unit coil and the even numbered 1. A unit coil laminate, characterized in that outer circumferential outlet portions on the front side of the second unit coil are connected to each other.