JPH03126204A - High frequency coil - Google Patents

Abstract

PURPOSE:To suppress an increase in an effective resistance upon increase in a frequency and to increase a large current capacity by sequentially laminating substantially ringlike conductive films and insulating films in multiple layers, and connecting the conductive film ends in parallel. CONSTITUTION:For example, substantially rectangular copper foils 1a, 1b, 1c,..., and low dielectric constant insulating films 2a, 2b, 2c, ... are prepared. The foils 1a, 1b, 1c,... and the films 2a, 2b, 2c, ... are sequentially laminated, and integrated through adhesive or the like. The right and left ends of the foils 1a, 1b, 1c,... protrude from the right and left ends of the films 2a, 2b, 2c,.... Then, coils 7a, 7b are punched from the laminated multilayer board 9. The coils 7a, 7b are formed of substantially C-shaped rings 4a, 4b, legs 5a, 5b connected to the rings 4a, 4b, and terminals 6a, 6b made only of copper foils of the legs 5a, 5b, and the terminals 6a, 6b are integrally connected by soldering or the like. In this case, the substantially OMEGA-shaped coils 7a, 7b composed of the foils 1a, 1b, 1c are connected in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high frequency coil suitable for use in a transformer for a switching regulator.

[Summary of the invention]

The present invention relates to a high-frequency coil suitable for use in a transformer for a switching regulator.The present invention relates to a high-frequency coil suitable for use in a transformer for a switching regulator. This suppresses the increase in effective resistance that accompanies the increase in current capacity, and simultaneously achieves a large current capacity.

Conventional technology] Traditionally, many of the transformers for switching regulators are relatively low voltage, high current types, and in order to handle high frequencies, the number of turns of the coil wound around the core etc. is several hundred to several tens of turns. There are many things. In particular, in the secondary winding, the number of turns is set based on the lowest regulation, contrary to the primary winding.
If it is about A, the wire diameter of the coil is about 2.3 mm. That is, when a round steel single wire is used as a coil wound around the core and the wire diameter is increased in order to increase the current capacity, the skin effect becomes impossible to ignore as the frequency band used increases. The skin effect is a phenomenon in which as the frequency increases, the current flowing through the coil conductor gathers at the surface and becomes difficult to flow through the center.The magnitude of the skin effect is given by the following equation.

ω・μ・k・・・・・・(1) ω is the angular frequency (ω-2πf, f: frequency) μ is the magnetic permeability of the conductor and the electrical conductivity of the conductor, where μ is determined by the material etc. If ω is approximately constant, it can be considered that the skin effect depends only on ω.

Due to such skin effect, current flows only on the surface of the conductor at high frequencies, so the resistance of the coil, ie, copper loss, increases. Therefore, in the past, thick winding wires were used to reduce copper loss, or, for higher frequencies (high power such as VHF), pipe-shaped conductors with silver plating on the surface or conductors made of thin stranded wires were used. I was using it.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 60-39743, a coil pattern is sequentially formed in one direction on a thin flexible printed board, and a pair of the flexible printed boards are overlapped to form a cylindrical shape. Coils and the like are also known.

It can be expressed as δ=(ω・μ・k)−* (2). For example, the frequency f=IM of ω=2πf
When the skin depth δ of the Hz copper wire is 66 μm, current no longer flows inside the wire and the effective resistance increases. That is, as the frequency f increases, copper loss increases, and there is a problem in that it is difficult to simultaneously handle a large current capacity and a high frequency (for example, MHz band), as in the case of the secondary winding of a switching regulator.

The present invention was made in order to solve the above-mentioned problems, and its purpose is to suppress the increase in effective resistance that accompanies higher frequencies and to obtain a high-frequency coil that can increase the current capacity. be.

[Problem to be solved by the invention]

When a skin effect with the magnitude of equation (1) above occurs in a conductor that forms a coil, the depth δ at which the current concentrates on the surface of the conductor is a quantity that represents the magnitude of the skin effect. Examples of the high-frequency coil of the present invention are shown in FIGS. 1A and 1B.

As shown in C, approximately ring-shaped (4a) (4b) conductive films (la) (lb) (lc) and insulating films (2a)
) (2b) (2c) (2d) are sequentially stacked in multiple layers to form terminals (6) of ring-shaped conductive films (4a) (4b).
a) This is made by connecting the parts in (6b) in parallel.

[Effect]

The high-frequency coil of the present invention is made by alternately laminating conductive films and insulating films with a thickness of about the skin depth δ due to the skin effect, forming a ring-shaped one-turn coil, and connecting the terminals in parallel, making it suitable for high frequencies. It is possible to suppress the influence of the accompanying skin effect and achieve low loss in the high frequency range and large current capacity.

〔Example〕

An embodiment of the high frequency coil of the present invention will be described below with reference to FIGS. 1 and 2.

FIGS. 1A, B, and C are explanatory diagrams for explaining the process of forming a high-frequency coil according to the present invention. First, as shown in Figure 1, for example, approximately rectangular copper foil (LA) (LB) (IC)...
...and low conductivity insulating films (2a) (2b) (2c
)... Prepare. Copper foil (la) (ib) (l
c) has a thickness of approximately the skin effect depth δ of δ−(ω·μ·k)−y shown in the second equation. For example, circumference aL] c f
is 60 μm at Iz and 20 μm at 5 MHz.
It is about m. Insulating film (2a) (2b) (2C)...
For example, copper foil (LA) (LB) (LC)...
...The left and right ends are smaller. Laminate such copper foils (la) (lb) (lc) ... and insulating films (2a) (2b) (2c) = = in sequence as shown in Figure 1, and apply adhesive etc. When integrated through the insulating films (2a), (2b), (2c), the left and right ends of the copper foils (la), (lb, and lc) protrude from the left and right ends of the insulating films (2a), (2b), (2c), and so on. Next, as shown in the plan view of Fig. 1C, coils (7a) (7b
) is punched out, the coil (7a) (7'b) is a substantially C-shaped ring! (4a) (4b) and this ring part (4a)
Legs (5a) (5b) communicating with (4b) and terminals (6a) made of only copper foil of these legs (5a) (5b)
(6b) and this terminal (6a) (6b)
are connected together with solder, etc. In this case each copper foil (la)
Approximately Ω-shaped coil (7a) composed of (To) (IC)
(7b) are connected in parallel. In order to use the thus punched coil (7a) as the secondary winding of a transformer for a switching regulator, for example, the groove (10a) of the lower E-shaped core (8a) must be cut out as shown in the second prisoner. (1
C-shaped ring part (4a) of the coil (7a) on the bottom of the coil (7a)
Eddy current loss due to leakage magnetic flux (11) can also be suppressed by sinking the coil (7a) sufficiently deeply to avoid leakage magnetic flux (11) that is incident perpendicularly to the surface of this coil (7a) (see assembled cross section in Figure 2B). I can do it. Next, the upper E-type core is placed on the lower E-type core and integrated, and the -order winding etc. are wound to form a transformer for a switching regulator.

According to the high-frequency coil of this example configured on this cliff, the increase in effective resistance (copper loss) of the coil due to higher frequencies is reduced,
Since it can handle large current capacity, it is possible to obtain a highly efficient transformer even with high frequency and large current capacity, such as the secondary winding of a transformer for a switching regulator.

In the above embodiment, the coils (7a) and (7b) each having one turn were explained, but a method for forming a high frequency coil having multiple turns will be explained with reference to FIGS. 3 and 4. Figure 3A.

B and C are pattern explanatory diagrams for explaining a method of forming, for example, a two-turn high-frequency coil.

In order to obtain such a pattern, copper foil (la) (lb) (lc)...
and the insulating films (2a), (2b), (2c), etc. are laminated to form an integrated multilayer board (9), and the third
First to third coils (12a), (12b), and (12C) having patterns as shown in Figures A, B, and C are punched out.

As shown in FIG. 3A, the first coil (12a) has a substantially C-shaped ring part (14a) and this link part (14a
) one leg (13a) communicating with the - end of the
A terminal (15a) consisting only of copper foil is formed at the end of this leg (13a), and a plurality of copper foils are soldered and connected in parallel.
It also includes a ring portion (14a) and an intermediate terminal portion (16a) formed at the other end. The second coil (12b) has intermediate terminals I (16b) (
16c) is formed, and a third coil (12c) is formed.
As shown in Fig. 3C, there is a semicircular half ring part (14c).
, one leg (13b) communicating with one end of this half ring part (14c), and this leg (13b)
There is a terminal (15b) consisting of only copper foil formed on the end of the ring, and a plurality of copper foils are soldered and connected in parallel, and a half ring 8 (14c).
id). Multilayer board like this (9)
The first to third coils (12a) punched from (
12b) (12C) is the ring part (14a) (1
4b) and the center of the half ring part (14C)○6,02
and 0. They are stacked as shown in Figure 4 with . and the intermediate terminal portion (16a) of the first coil (12a).
) and the intermediate terminal part (1) of the second coil (12b)
6c) Each copper foil (la
) (lb)... are connected in parallel to each other. Similarly, the second coil (12b) and the third coil (12c
) The intermediate terminal portions (16b) and (16d) of each copper foil (l
a) (lb)... are integrated so that they are connected in parallel with each other. In the above example, the terminals (15a) and (15b) were made of copper foil only, but as shown in Figure 4, this part is also laminated with an insulating film and copper foil alternately, and through holes are drilled in each part. The copper foils (la) and (lb) may be connected in parallel. In addition, in Figure 4 (17a)
(17b) (17c) Fill the through holes with solder and connect the intermediate terminal parts (16a) and (16c) (16e).
(16d) and the terminal (15a) or (15b) copper foil (la) (lb)... are shown integrated.

A high frequency coil with multiple turns of three or more turns can be easily obtained by the same method as described above.

By using this example as a secondary coil of a transformer for a switching regulator, a highly efficient transformer can be obtained.

In addition, although the above-mentioned example was explained as a high frequency coil of a transformer for a switching regulator, its use is not limited to a transformer for a switching regulator, and can be used for various high frequency coils. Also, multilayer board (9
) is not limited to the laminate of copper foil (1a) (lb) (lc) and insulating film (2a) (2b) (2c) (2d). It is obvious that various modifications can be made without departing from the spirit of the present invention, such as the use of laminated coil portions.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a high-frequency coil that suppresses the influence of the skin effect, has low loss in the high-frequency range, and has a large current capacity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the formation process of the high-frequency coil of the present invention, FIG. 2 is an assembly state diagram of the high-frequency coil, FIG. 3 is a coil pattern diagram showing another embodiment of the high-frequency coil of the present invention, and FIG.
The figure is an assembled side cross-sectional view showing an embodiment of the high-frequency coil pond of the present invention. (la) (lb) (lc) is copper foil, (2a) (2
b) (2c) (2d) f'! Insulating film, (4a)
(4b) is the ring part, (7a) (7b) is the coil, (
9) is a multilayer board, and (8a) and (8b) are E-type cores. Agent Hidemori Matsukuma 91-layer board Honbunmei's high side carp 1 gun A'ball 8 theory Tsukikuni 1st figure 20 - $, fixed June's high frequency coil Shino Aoi] Standing person floor stage 2nd map of the month of the month of high school and high school! ! n tiger or example carp I turn B turn the market of the present invention against carp

Claims (1)

[Claims] A high-frequency coil characterized in that a substantially ring-shaped conductive film and an insulating film are successively laminated in multiple layers, and terminals of the ring-shaped conductive films are connected in parallel.