JP2016146423A - High frequency choke coil and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a high frequency choke coil having wide band characteristics, easy to be manufactured and mounted.SOLUTION: The high frequency choke coil includes: a substrate 21; a coil body 25 formed with a pattern of a plurality of rounds in a spiral shape with a conductor on one surface side 21a of the substrate 21; and resistor 30, 40 formed with such a pattern as to connect conductors of different rounds of the coil body 25, for suppressing resonance caused by inter-wiring capacitance and floating capacitance between the conductors. Furthermore, a leg part 22 for substrate installation is projected on a lower surface side 21b of the substrate 21 to reduce the floating capacitance between the coil body 25 and an installation surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for realizing a high-frequency choke coil (hereinafter referred to as RFC) that has wide-band characteristics and is easy to manufacture and mount.

  The RFC has a characteristic of allowing direct current to pass and exhibiting high impedance with respect to alternating current (high frequency) having a high frequency, and is mainly used in a power supply circuit such as a high frequency amplifier or a driver, a bias supply circuit, or the like.

  In order to obtain a flat characteristic over a wide band with an RFC for separating AC and DC as described above, it is necessary to suppress resonance within the use band. A conical structure is known in which an absorber is used as a core material and a conducting wire is wound around the outer periphery of the core (for example, Patent Document 1).

Japanese Patent Application No. 2004-266047

  However, it is difficult to manufacture an RFC having a conical structure in which a conducting wire is wound around a core as described above, because it is necessary to wrap the conducting wire densely without gaps, and when the tip of the conducting wire is connected to another circuit, solder is required. Wiring is performed using a material or an adhesive, but it is necessary to remove the insulation coating in advance, and mounting work including fixing of parts is very troublesome.

  An object of the present invention is to solve this problem and to provide an RFC having a wide band characteristic and easy to manufacture and mount.

In order to achieve the above object, a high frequency choke coil according to claim 1 of the present invention comprises:
A substrate (21);
A coil body (25) in which a plurality of circumferential patterns are spirally formed with a conductor on one surface side of the substrate;
Resistors (30, 40, 30a to 30c, 40a to 40c, which are patterned so as to connect conductors of different circumferences of the coil body, and suppress resonance caused by line capacitance between the conductors and stray capacitance, 50, 60).

A high-frequency choke coil according to claim 2 of the present invention is the high-frequency choke coil according to claim 1,
A substrate installation leg portion (22) is projected from the surface opposite to the one surface side of the substrate.

A method for manufacturing a high-frequency choke coil according to claim 3 of the present invention includes:
Patterning a resistor on one side of the substrate;
A coil main body in which a conductor is formed in a spiral pattern on one surface side of the substrate, and the conductors of different circumferences of the coil main body are connected by the resistor.

  As described above, the high-frequency choke coil of the present invention is formed by connecting the conductors of different circumferences of the coil body in which the conductor is spirally formed on one surface side of the substrate with a resistor, and the line capacitance between the conductors, Resonance due to stray capacitance is suppressed, so it can be easily manufactured only by thin film pattern processing on the substrate, and both ends of the coil body patterned on the substrate and other circuits are connected by wire bonding. And can be implemented very easily.

  In addition, because the board installation legs protrude from the opposite side of the board, an air layer is formed between the opposite side of the board and the installation surface, and the stray capacitance between the coil body and the installation surface Can be reduced, and resonance within the use band due to stray capacitance can be more effectively prevented.

The figure which shows the structure of embodiment of this invention RFC equivalent circuit including resistors The figure which shows the characteristic of RFC of embodiment and RFC of conventional structure The figure which shows the characteristic when there is no resistor in RFC of embodiment The figure which shows the characteristic at the time of providing the resistor also inside by RFC of embodiment The figure for demonstrating the manufacturing method of RFC of embodiment. Diagram showing a configuration with a reduced number of resistors Diagram showing a configuration with an increased number of resistors The figure which shows the example which provided the resistor in the unit of two conductors

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the structure of an RFC 20 to which the present invention is applied.

  This RFC 20 is for realizing a stable high-frequency blocking characteristic from several tens of MHz to about 60 GHz, and as shown in the plan view of FIG. 1A, a substrate having a predetermined thickness and a substantially square outer shape. 21, a coil body 25 that is spirally formed with a conductor at the center of the upper surface side 21 a of the substrate 21, and a resistor 30 that is patterned so as to connect between conductors of different circumferences of the coil body 25, 40.

  The substrate 21 is an insulator and is made of a material having a low dielectric loss tangent (loss) and a low relative dielectric constant (close to 3), such as quartz glass or Teflon (registered trademark), and has a side of about 0.8 mm and a thickness of 0. The leg portion 22 for installing the substrate protrudes at the same height as the thickness of the substrate 21 at the four corners of the lower surface side 21b as shown in the front view of FIG. It is installed.

  Thus, since the board installation leg portion 22 is provided on the lower surface side 21b of the substrate 21, an air layer is formed between the lower surface side 21b of the substrate 21 and the installation surface, and the coil body 25 and the installation surface are installed. The stray capacitance between the surfaces can be reduced, and resonance within the use band due to the stray capacitance can be more effectively prevented. Here, the leg portion 22 is formed of the same material as that of the substrate 21, but may be formed of another material having a small dielectric loss tangent (loss) and a low relative dielectric constant. The position of the leg 22 is preferably provided at a position that avoids the central portion of the substrate where the magnetic flux of the coil body 25 is concentrated, and ideally is provided at a position that does not overlap the coil body 25 so as not to increase the stray capacitance. It is best if you can.

  The conductor of the coil body 25 is made of, for example, gold (Au), silver (Ag), copper (Cu) or the like, and has a predetermined width (for example, 25 μm) and a predetermined gap (for example, 15 μm). A predetermined spiral (for example, 8 laps) is formed in a square spiral shape from the outer edge to the outer edge, and the innermost and outermost ends have a width and a length to facilitate connection by wire bonding. Widely formed terminal portions 25a and 25b are provided.

The upper surface 21 a of the substrate 21 is provided with resistors 30 and 40 patterned along a line extending from the center of the coil body 25 to one side of the substrate 21 and perpendicular to the opposite side. The resistors 30 and 40 are made of, for example, tantalum nitride (Ta ₂ N), nickel chrome (NiCr), silicon oxide (SiO ₂ ), etc., and have a predetermined width (for example, 15 μm) and a predetermined thickness (for example, 0.01 μm). The pattern is formed to connect the conductors of different circumferences of the coil body 25, and here, the four adjacent conductors outside the coil body 25 are connected by a predetermined resistance (several hundreds Ω). . By connecting the conductors of the coil body 25 with this relatively low resistance, resonance due to the inductance of the conductor and the capacitance between the lines and stray capacitance can be suppressed, and a wideband characteristic can be obtained as an RFC.

  FIG. 2 shows the circuit of the RFC 20 equivalently, and it can be said that a plurality of taps are provided on the coil body 25, and the resistances R1, R2, and R3 of the resistors 30 and 40 are connected therebetween. The resistance component is intensively connected to a portion where the conductor length per circuit is longer than the short portion. This is because the line-to-line capacitance and stray capacitance are reduced in the part where the conductor length per circuit is short, and the resonance frequency thereby exceeds the use band, and the influence can be ignored, but in the part where the conductor length per circuit is long. This is to prevent line capacitance and stray capacitance from increasing, and the resulting resonance frequency from entering the use band and causing a non-negligible effect.

FIG. 3 shows the characteristics of the RFC having the conventional structure and the RFC 20 having the above structure. This characteristic is the result of measuring the loss (S ₂₁ ) between the input and output of the transmission line when the RFC to be measured is connected in parallel between the main line conductor and the ground conductor of a 50Ω transmission line (for example, a microstrip line). It is.

  The size of the RFC of the conventional structure is a coated copper wire with a thickness of about 0.05 mm, wound 10 times around the core with close winding, with the thin diameter about 0.2 mm and the thick diameter about 1 mm. The coil height is 0.5 mm.

In addition, the RFC 20 having the above structure has a substrate 21 made of a quartz glass material having an outer shape (width × length) of 0.8 × 0.75 mm and a thickness of 0.2 mm, and the coil body 25 is made of a conductive material gold (Au), The conductor width is 25 μm, the gap between conductors is 15 μm, the number of turns is 8 turns, the resistors 30 and 40 are made of tantalum nitride (Ta ₂ N), the width is 15 μm, the thickness is 0.01 μm, and the four conductors of the coil body 25 It has a total length of 145 μm, with a width of 25 μm × 4 and a gap of 15 μm × 3 between the four conductors, and each of the conductors for the four outer circumferences of the coil body 25 is connected with a resistance of about 200Ω. . The resistance values per unit length of the resistors 30 and 40 are uniform over the entire length, but the resistance value of the portion of the coil body 25 that overlaps the conductor becomes a low resistance close to 0Ω by the conductor, Only between the conductors will have a resistance value of 200Ω.

  As shown in FIG. 3, both the characteristic G of the RFC 20 of the embodiment and the characteristic F of the RFC of the conventional structure are in the range of −3 dB from the lower limit frequency of 40 MHz to 60 GHz, and almost the same characteristics are obtained. Therefore, the RFC 20 of the embodiment can be easily manufactured only by patterning the conductors of the coil body 25 and the resistors 30 and 40 on the substrate 21 as compared with the RFC of the conventional structure that can obtain an equivalent frequency characteristic. Since it can be simply mounted simply by wire bonding to both ends of the coil body 25, it is much easier to use.

  FIG. 4 shows the characteristic G of the RFC 20 of the embodiment and the characteristic G ′ when the resistors 30 and 40 are omitted. When the resistors 30 and 40 are not provided, the line capacitance and the stray capacitance between the conductors are shown. It can be seen that a large number of deep dip points due to resonance appear to be caused by the above, and that a broadband characteristic such as the characteristic G cannot be obtained.

  FIG. 5 shows changes in the characteristics of the RFC 20 when the circumferential position of the coil body 25 connected by the resistors is changed (the lengths of the resistors 30 and 40 are changed). A characteristic Ga in which the two conductors are connected by the resistors 30, 40, a characteristic Gb in which the five outer conductors are connected by the resistors 30, 40, and the four outer conductors are connected by the resistors 30, 40 in the same manner as described above. The characteristic Gc, the characteristic Gc in which the three outer conductors are connected by the resistors 30 and 40, and the characteristic G ′ without the resistors 30 and 40 are shown.

  As is clear from this figure, in the state where the outer four conductors of the coil body 25 are connected by resistors, there is a significant characteristic difference depending on whether the inner conductors are connected by resistors. In addition, it can be seen that the resonance suppression action by the resistor is dominant in the connection between the outer conductors. In addition, in the characteristic Gc in which only the outer three conductors are connected by the resistor, a shallow dip point appears. Therefore, in the case of RFC20 having the above-described dimensions and material, the outer three or more conductors are connected by the resistor. It is presumed that one having the outer four conductors connected by resistors is the best in practice.

Next, a method for manufacturing the RFC 20 having the above structure will be briefly described with reference to FIG.
First, as shown in FIG. 6A, a substrate 21 made of a quartz glass material having a predetermined thickness is prepared. As shown in FIG. 6B, the materials of the resistors 30 and 40 are formed on the substrate upper surface 21a. A tantalum nitride (Ta ₂ N) layer 100 is formed to a thickness of 0.01 μm. In FIG. 6, the thicknesses of the resistors 30 and 40, the coil body 25, and the material thereof are exaggerated.

Next, unnecessary tantalum nitride (Ta ₂ N) layers are removed by masking the portions to be the resistors 30 and 40, and the resistors 30 and 40 are made to have a width of 15 μm, as shown in FIG. A pattern is formed with a length of 145 μm (25 × 4 + 15 × 3).

  Subsequently, as shown in FIG. 6D, a gold (Au) layer 101 which is a material of the coil body 25 is formed with a thickness of 8 μm.

  Finally, the spiral portion that becomes the coil body 25 is masked to remove unnecessary gold (Au) layers, and four locations including both ends of the resistors 30 and 40 as shown in FIG. The coil body 25 is patterned in a state where the four outer conductors intersect each other. In practice, a large number of RFCs 20 are manufactured at a time by forming a plurality of pairs of resistor and coil body patterns on a large substrate and then cutting the substrate. In addition, about the leg part 22, it forms by the method of adhere | attaching the thing manufactured with the board | substrate 21 with another member on the lower surface side of the board | substrate 21, and the lower surface side of the board | substrate 21 leaving the four corners. Can do.

  The above-described dimensions, such as the material, shape, width, and thickness of the substrate 21, the coil body 25, and the resistors 30, 40, of the RFC 20 are merely examples and do not limit the present invention. Combinations may be used, and dimensional changes such as width and thickness are arbitrary.

  Moreover, in the said embodiment, although 2 sets of resistors 30 and 40 were used, for example, when the inductance of the coil main body 25 is small (when the number of turns is small), as shown in FIG. Resonance can also be suppressed by connecting the conductors with one set of resistors 30. Conversely, when the inductance is large (when the number of turns is large), four sets of five outer conductors are connected as shown in FIG. It is also possible to suppress resonance by connecting the resistors 30, 40, 50, 60 (which may be three sets).

  Further, in the above embodiment, the conductors are connected by the single resistors 30 and 40 that linearly intersect the four adjacent conductors of the coil body 25. However, the arrangement of the resistors that connect the conductors is arranged. For example, as shown in FIG. 9, the resistors 30 a to 30 c and 40 a to 40 c may be connected using two adjacent conductors as a connection unit. Further, the resistor does not necessarily have to connect between adjacent conductors, and may be connected in a jumping manner so as to straddle the conductors.

  Moreover, in the said embodiment, although the coil main body was formed in the square spiral shape, you may form in polygonal spirals, such as circular, a hexagon, and an octagon.

  20 ... RFC (High Frequency Choke Coil), 21 ... Substrate, 22 ... Leg, 25 ... Coil body, 25a, 25b ... Terminal, 30, 40, 30a-30c, 40a-40c, 50, 60 …… Resistor

JP 2004-266047 A

In order to achieve the above object, a high frequency choke coil according to claim 1 of the present invention comprises:
A substrate (21) made of an insulator;
A coil body (25) in which a plurality of circumferential patterns are spirally formed with a conductor on one surface side of the substrate;
On one side of the substrate, wire bonding terminal portions (25a, 25b) patterned on the innermost end and the outermost end of the coil body;
A resistor that is patterned on one surface side of the substrate so that conductors of different circumferences of the coil body are equivalently connected by a resistance component, and suppresses resonance caused by line capacitance between the conductors and stray capacitance. (30, 40, 30a-30c, 40a-40c, 50, 60).
The high frequency choke coil according to claim 2 of the present invention is the high frequency choke coil according to claim 1,
The resistor is characterized in that the conductors of different circumferences are equivalently connected with a resistance component of several hundred Ω.

A high-frequency choke coil according to claim 3 of the present invention is the high-frequency choke coil according to claim 1 or 2 ,
A substrate installation leg portion (22) is projected from the surface opposite to the one surface side of the substrate.

A method for manufacturing a high-frequency choke coil according to claim 4 of the present invention includes:
Patterning resistors (30, 40, 30a to 30c, 40a to 40c, 50, 60) on one side of the substrate (21) made of an insulator;
A coil body (25) in which conductors are formed in a spiral pattern on one surface of the substrate , and wire bonding terminal portions (25a, 25b) patterned on the innermost and outermost ends of the coil body. And a step of equivalently connecting the conductors of different circumferences of the coil main body with a resistance component by the resistor .

Claims (3)

A substrate (21);
A coil body (25) in which a plurality of circumferential patterns are spirally formed with a conductor on one surface side of the substrate;
Resistors (30, 40, 30a to 30c, 40a to 40c, which are patterned so as to connect conductors of different circumferences of the coil body, and suppress resonance caused by line capacitance between the conductors and stray capacitance, 50, 60).   The high frequency choke coil according to claim 1, wherein a leg portion (22) for installing a substrate is projected from a surface opposite to the one surface side of the substrate. Patterning a resistor on one side of the substrate;
A high frequency choke comprising: a coil body in which a conductor is formed in a spiral pattern on one surface side of the substrate; and a conductor between different circumferences of the coil body is connected by the resistor. Coil manufacturing method.

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