JP7832040B2 - Coil components, circuit boards, electronic devices, and methods for manufacturing coil components - Google Patents

Description

This invention relates to coil components, circuit boards, electronic devices, and methods for manufacturing coil components.

Conventionally, a coil component is known that comprises a magnetic substrate made of a magnetic material, an external electrode provided on the surface of the magnetic substrate, and a coil conductor that spirally orbits around a coil axis within the magnetic substrate.
An example of a coil component is an inductor. An inductor is a passive component used in electronic circuits. For example, inductors are used to remove noise in power lines and signal lines.

One example of an inductor is the multilayer inductor. In a multilayer inductor, for example, a conductor pattern is formed by screen printing on a perforated magnetic sheet, and these sheets are sequentially stacked to form a coil by connecting the conductor patterns in series. In a multilayer inductor, it is necessary to efficiently form the coil conductors so that the desired characteristics as an inductor are obtained. In addition, in a multilayer inductor, the conductor pattern must be arranged so as not to deform under the pressure during molding.
For example, Patent Document 1 proposes a technique for reducing the DC resistance of a coil by configuring the coil in a double helix shape by connecting a coil conductor and a via-hole conductor.

Japanese Patent Publication No. 2011-187535

In multilayer inductors, the number of turns of the coil conductor to obtain the required inductance and DC resistance, as well as the position of the lead wires connecting the coil conductor to the external electrodes, are predetermined. Furthermore, conductor patterns with less than one turn per layer when viewed from the stacking direction (e.g., 1/2 turn, 3/4 turn, 5/6 turn, etc.) are used, and multilayer inductors perform better when the number of turns per layer is greater.
When the number of turns of a coil within a single layer exceeds one full turn when viewed from the stacking direction, that is, when the conductor is wound around the coil more than one full turn to form a planar spiral coil, it becomes necessary to solve the problem of short circuits between overlapping conductors within the same layer. Furthermore, the area of the core surrounded by the coil conductors, as viewed from the stacking direction, decreases, making it difficult to obtain the required inductance value. For this reason, the number of turns of a coil within a single layer is usually set to less than one full turn.

In multilayer inductors, if the maximum winding length of the conductor pattern—the manufacturing limit for the amount of windings viewed from the stacking direction within a single layer—is used, the amount of windings in the conductor pattern may fall below the maximum winding length in one of the stacked sheets. When this occurs, the areas with and without the conductor pattern are not evenly distributed. This difference in shrinkage between the conductor and magnetic material during molding causes coil deformation, resulting in a deterioration of characteristics and quality.

Therefore, conventionally, a winding amount less than the maximum winding amount was used as the winding amount of the conductor pattern within a single layer, as viewed from the stacking direction.
At this time, there are two methods: first, the small winding amount is set each time according to the desired number of turns so that there are no fractional turns, and the amount of winding is adjusted to be equal in each layer; and second, one type of winding amount is determined, and when there is a fractional turn compared to the desired number of turns, the conductor pattern on the lead side is adjusted.

However, in both cases, the length of the pattern gaps within the coil circumference, which do not contribute much to the inductance, becomes longer than in the case of the maximum number of turns, resulting in a decrease in inductance. When a smaller number of turns is used compared to when the maximum number of turns is used, the design may have more layers, and since the height of the coil components is limited, it becomes necessary to reduce the thickness of each layer, which degrades the insulation performance.
Furthermore, in the former case, a conductor pattern with a different winding amount for each layer is required for each coil component with multiple inductance values, which complicates the manufacturing process.

Furthermore, in the latter case, the presence of conductor patterns in the fractional portion means that the conductor and magnetic material are not evenly distributed. This difference in shrinkage between the conductor and magnetic material during molding can lead to short-circuit defects due to contact between the conductor patterns of the upper and lower layers, a decrease in inductance due to coil deformation, and a deterioration in yield when cutting the inductor from the laminated molded body, resulting in a deterioration of characteristics and quality.
To improve the latter, conventional designs have included extending unnecessary conductors (non-conducting conductors) to positions where no current flows, thereby ensuring symmetry in the conductor pattern. However, this approach has the problem that the properties of the magnetic substrate are not efficiently utilized because the number of conductors that do not contribute to the characteristics increases.
Therefore, the present invention aims to improve the characteristics of a coil while preventing deformation of the coil.

To solve the above problems, a coil component according to one aspect of the present invention comprises a spiral conductor, the overlapping conductor patterns of multiple layers stacked in a plurality of layers, such that when viewed from the stacking direction, they form a circular circuit; the multiple layers of conductor patterns are connected in a spiral manner; the multiple layers of conductor patterns include a spiral conductor containing short patterns shorter than the conductor patterns of other layers; a pair of lead wires connected to both ends of the spiral conductor and extending from the circular circuit when viewed from the stacking direction; a magnetic substrate made of multiple layers of magnetic material enclosing the spiral conductor; a pair of external electrodes provided on the outer surface of the magnetic substrate, to which the pair of lead wires are connected; and a parallel pattern provided in the short pattern layer, extending in parallel from one end of the short pattern along the conductor pattern of the adjacent layer, with the extended end connected to the conductor pattern of the adjacent layer.

According to one embodiment of the present invention, the short pattern is located in an intermediate layer among the multiple layers.
Furthermore, according to one aspect of the present invention, the conductor structure, which combines the helical conductor and the parallel pattern, is symmetrical with respect to the reversal of the coil component in the direction in which the pair of lead wires are swapped.
Furthermore, according to one embodiment of the present invention, among the conductor patterns constituting the helical conductor, the conductor patterns other than the short pattern extend to a length that reaches 90% or more of one circumference within the layer.

Furthermore, according to one aspect of the present invention, when viewed from the stacking direction, the winding amount is expressed as a fraction with the length of one turn of the circuit as the denominator and the length of the conductor pattern as the numerator, with the interval along the circuit between the positions of the connection parts of the conductor patterns of each layer projected onto the circuit as the unit, then the winding amount of the conductor patterns other than the short pattern among the conductor patterns constituting the helical conductor is equal to the winding amount of the pattern that combines the short pattern and the parallel pattern.
Furthermore, according to one aspect of the present invention, the conductor patterns constituting the helical conductor are connected to each other by vias of diameter R, and if the length L of the circuit is divided by the largest integer n less than or equal to the quotient obtained by the sum of the width PH of the conductor pattern and the diameter R of the via, then the conductor patterns other than the short pattern are composed of (n-1)/n of the circuit.

Furthermore, according to one embodiment of the present invention, the conductor pattern constituting the helical conductor has a thickness in the stacking direction that is greater than the spacing between them in the stacking direction.
Furthermore, according to one aspect of the present invention, the gaps between the ends to which the conductor pattern extends do not overlap, at least between adjacent layers, when viewed in the stacking direction.

Furthermore, a circuit board according to one aspect of the present invention comprises any of the above-mentioned coil components and a substrate on which the coil components are mounted.
Furthermore, an electronic device according to one aspect of the present invention includes the above-mentioned circuit board.
Furthermore, a method for manufacturing a coil component according to one aspect of the present invention is a manufacturing method for manufacturing the above-mentioned coil component, comprising the steps of laminating a plurality of layers including a conductor pattern constituting the helical conductor and the parallel pattern, and a plurality of layers of magnetic material constituting the magnetic substrate, and pressing the laminated plurality of layers together to form a laminate.

According to this invention, it is possible to improve the characteristics of the coil while preventing deformation of the coil.

This is a perspective view showing a coil component related to one embodiment of the present invention. This is a cross-sectional view of the coil component shown in Figure 1. This is a conceptual diagram showing the helical structure of a conductor. This diagram shows the detailed structure of the conductor in a coil component. This figure shows the via positions corresponding to the maximum winding amount. This is a diagram showing the land shape of the via. This figure shows the conductor structure of the first comparative example of a coil component. This figure shows the conductor structure of the second comparative example of a coil component. This is a schematic perspective illustrating a situation in which pressure imbalances occur. This is a schematic cross-sectional view illustrating a situation where pressure imbalance occurs. This is a schematic perspective view illustrating a situation where pressure is distributed. This is a schematic cross-sectional view showing a situation where pressure is distributed. This figure shows the structure of the conductor in a modified example compared to the second comparative example. This figure shows a comparative example compared to a second embodiment of the present invention. This figure shows a second embodiment of the present invention. This figure shows a third embodiment of the present invention.

The embodiments of the present invention will be described in detail below with reference to the attached drawings. Note that the following embodiments are not limiting to the present invention, and not all combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications and various conditions (operating conditions, operating environment, etc.) of the device to which the present invention is applied.

The technical scope of this invention is defined by the claims and is not limited by the following individual embodiments. The drawings used in the following description may differ in scale and shape from the actual structure for the sake of clarity. Components shown in the previously described drawings may be referenced as appropriate in later descriptions of the drawings.

<Basic structure of coil components>
Figure 1 is a perspective view showing a coil component according to one embodiment of the present invention. Figure 2 is a cross-sectional view of the coil component shown in Figure 1. Figure 2(A) shows a cross-section along the line A-A shown in Figure 1, and Figure 2(B) shows a cross-section along the line B-B shown in Figure 1.
The coil component 1 is mounted on a substrate 2a. The substrate 2a is provided with, for example, two land portions 3. The coil component 1 has a base body 11 and external electrodes 12, and the coil component 1 is mounted on the substrate 2a by soldering each external electrode 12 to the land portion 3. A circuit board 2 according to one embodiment of the present invention comprises the coil component 1 and a substrate 2a on which the coil component 1 is mounted. The circuit board 2 can be provided in various electronic devices. Examples of electronic devices equipped with the circuit board 2 include automotive electrical components, servers, board computers, and various other electronic devices.

The coil component 1 may be an inductor, transformer, filter, reactor, or various other coil components. The coil component 1 may also be a coupled inductor, choke coil, or various other magnetically coupled coil components. The coil component 1 may, for example, be an inductor used in a DC/DC converter. The applications of the coil component 1 are not limited to those explicitly stated herein.

In this specification, unless otherwise understood in context, directions are described using the "L-axis," "W-axis," and "H-axis" directions of Figure 1 as reference points, and are referred to as the "length," "width," and "height" directions, respectively. The "height" direction may also be referred to as the "thickness" direction.

The coil component 1 has a rectangular parallelepiped shape. Specifically, the coil component 1 has a first end face 1a and a second end face 1b at both ends in the length direction, a first main surface 1c (top surface 1c) and a second main surface 1d (bottom surface 1d) at both ends in the height direction, and a front surface 1e and a rear surface 1f at both ends in the width direction.

The first end face 1a, the second end face 1b, the first main face 1c, the second main face 1d, the front face 1e, and the rear face 1f of the coil component 1 may all be flat or curved surfaces. Furthermore, the eight corners and twelve edges of the coil component 1 may be rounded.

In this specification, even if the first end face 1a, the second end face 1b, the first main face 1c, the second main face 1d, the front face 1e, and part of the rear face 1f of the coil component 1 are curved, or if the corners or edges of the coil component 1 are rounded, such a shape may be referred to as a "rectangular parallelepiped shape." In other words, in this specification, "rectangular parallelepiped" or "rectangular parallelepiped shape" does not mean a "rectangular parallelepiped" in a mathematically strict sense.

In one embodiment of the present invention, the coil component 1 has a conductor 14 inside a base body 11, and the base body 11 and the conductor 14 are integrally formed by lamination. Both ends of the conductor 14 are connected to the external electrodes 12. Note that while Figure 2(B) shows a layered structure to illustrate the concept of lamination, in the actual coil component 1, each layer is crimped and integrated, so clear boundaries may not exist.

The substrate 11 is made from a composite magnetic material containing one or more metallic magnetic particles and a binder resin. The substrate 11 may be made by bonding the metallic magnetic particles together through an oxide film on the surface of each particle. As the metallic magnetic particles, Fe or Ni as the main component may be used, such as FeSiCr, FeSiAl, FeSiCrB, Fe-Ni, Fe, etc. Alternatively, combinations of these may be used as the metallic magnetic particles, or the metallic magnetic particles may contain, for example, Si, Bi, etc.

The shape of the metallic magnetic particles is not particularly limited, but they are preferably spherical or nearly spherical, with an average particle diameter of 1 to 20 μm. The metallic magnetic particles may also be insulated.
The binder resin binds multiple metal magnetic particles together. The binder resin is, for example, a thermosetting resin with excellent insulating properties. The material of the substrate 11 is not limited to those explicitly stated herein, and any known material can be used as the substrate material.

The conductor 14 is made of a metallic material with excellent conductivity. As the metallic material for the conductor 14, for example, one or more metals from Cu (copper), Al (aluminum), Ni (nickel), or Ag (silver), or an alloy containing any of these metals, may be used. The conductor 14 may also contain oxides as part of the metallic material.

The external electrode 12, like the conductor 14, is made of a metal material with excellent conductivity. The same metal material used for the conductor 14 may be used for the external electrode 12. The external electrode 12 may have layers of Ni and Sn superimposed on its surface by plating or other means.

In the formation of the coil component 1 by lamination, multiple magnetic sheets 111 made of the composite magnetic material described above are prepared, and a planar conductive pattern 141 for forming the conductor 14 is created on the surface of the magnetic sheets 111, for example by printing. Methods other than printing, such as plating, vapor deposition, or paste transfer, may be used to form the conductive pattern 141.
The thickness of the conductor pattern 141 is preferably greater than the spacing between the conductor patterns 141 (i.e., the thickness of the magnetic sheet 111). This is because a greater thickness of the conductor pattern 141 than the spacing between the layers suppresses the effect of the difference in shrinkage between the conductor and the magnetic material during molding.

Furthermore, holes are made in the magnetic sheet 111 to form vias 142 connecting each conductor pattern 141, and these holes are filled with conductive material. The vias 142 are created, for example, by printing or filling. The printing of the vias 142 may be performed simultaneously with the printing of the conductor patterns 141 or separately. Other methods besides printing, such as plating, vapor deposition, or paste transfer, may also be used to form the vias 142.

Subsequently, the magnetic sheet 111 with the conductor pattern 141 and via 142 is stacked with the magnetic sheet 111 that will form the uppermost and lowermost layers of the substrate 11, and then compressed to obtain a laminate. The resulting laminate is then separated into individual pieces and heat-treated to obtain a substrate 11 containing the conductor 14. In the heat treatment of the laminate, the resin may be removed by thermal decomposition at 600-850°C, and the metallic magnetic particles may be oxidized.

Subsequently, external electrodes 12 are formed so that they are connected to both ends of the conductor 14. The external electrodes 12 can be formed by any method; for example, printing, paste dipping, paste transfer, sputtering, or vapor deposition may be used. The shape of the external electrodes 12 can be any shape.

<Detailed structure of the conductor>
The conductor 14 has a helical structure in which the conductor patterns 141 of each layer are connected in a spiral manner. Among the conductor patterns constituting the helical conductor, there are short patterns that are shorter than the conductor patterns of other layers, and parallel patterns that extend in parallel from one end of the short pattern along the conductor pattern of the adjacent layer, with the extended end connected to the conductor pattern of the adjacent layer.

Figure 3 is a conceptual diagram showing the helical structure of conductor 14 as viewed from the stacking direction. Here, the shape obtained by superimposing the shapes of each conductor pattern from the stacking direction is referred to as the circumferential circuit. Furthermore, the length of the line segment passing through half the width of each conductor pattern from one end to the other is called the conductor pattern length. The length of the line formed by the overlapping of these line segments (i.e., the line that completes one circuit of the circumferential circuit) is referred to as the circumferential circuit length.

The leftmost diagram in Figure 3 shows the circumferential circuit 143 and via positions 144 of the conductor 14. In Figure 3, the connections between the conductor patterns 141 of each layer are made using vias 142. The via positions 144, which are the connection positions, are obtained by projecting the positions of the vias 142 for connecting each layer onto the circumferential circuit 143 as viewed from the stacking direction. Vias are not necessarily used to connect the conductor patterns 141 of each layer. Even in that case, the connection positions projected onto the circumferential circuit 143 are the same as the via positions 144 when vias are used for connection. In the following, the present invention will be explained using the case of via connection, which is a typical example of connection. In cases other than via connection, the present invention will be explained by replacing "via" with "connection part". For example, via 142 and via position 144 can be replaced with connection part 142 and connection part position 144, respectively. In the following explanation of Figures 4, 7, 8, 13, 14, 15, and 16, the leftmost diagram will similarly be used to show the circumferential circuit and via positions of the conductor.
The conductor 14 has a conductor pattern 141 that extends along, for example, an elliptical circumferential circuit 143. Although an elliptical circumferential circuit 143 is illustrated in Figure 3, the shape of the circumferential circuit 143 may be other shapes, such as a rectangle.

Via 142 is provided at one of the via positions 144 set at equal intervals on the circuit 143. In Figure 3, as an example, the via positions 144 are at positions that divide the circuit 143 into eight equal parts, but the via positions 144 may also be at positions that divide the circuit into four, six, or ten equal parts. The interval between via positions (hereinafter referred to as via interval) is not necessarily limited to an even number of equal parts.
If the structure of the coil component is symmetrical, it is desirable that characteristic changes dependent on the mounting direction occur less during the mounting of the coil component. For this reason, it is desirable that the via spacing is at equal intervals, as this improves the symmetry of the coil component structure. Furthermore, it is even more desirable that the via spacing is at an even number of equal intervals, as this further improves the symmetry of the coil component structure.

Each layer of the conductor pattern 141 is formed between via positions 144 connected to the upper layer and via positions 144 connected to the lower layer, and has a shape that is less than one full rotation by the distance between the via positions 144. The uppermost layer of the conductor pattern 141 is formed between a via position 144, one end of which is connected to the conductor pattern 141 of the lower layer, and a via position 144, the other end of which is connected to a lead-out portion 145a connected to the external electrode 12, and has a shape that is less than one full rotation by the distance between the via positions 144. The lowermost layer of the conductor pattern 141 is formed between a via position 144, one end of which is connected to the conductor pattern 141 of the upper layer, and a via position 144, the other end of which is connected to a lead-out portion 146a connected to the external electrode 12, and has a shape that is less than one full rotation by the distance between the via positions 144. For example, in Figure 3, the peripheral circuit 143 is divided into eight equal parts by eight via positions 144, and the pattern includes seven of these via intervals, resulting in a shape approximately 7/8 of the circumference. Since the via positions 144 where vias 142 are formed in the conductor pattern 141 of each layer are offset by one via interval, the overlapping conductor patterns 141, viewed from the stacking direction, are connected in a spiral pattern, as shown by the dashed-dotted arrows.

In the following, the amount of turns in a single layer of conductor pattern 141 that is less than one full turn will be referred to as the "winding amount" of the conductor pattern 141. The winding amount represents the relative length of the conductor pattern 141 to the length of one full turn of the circuit 143. Relative length refers to the number of via spacings included, where one via spacing is defined as 1. In this case, the winding amount is expressed as a fraction with the number of via spacings included in the conductor pattern 141 in the numerator and the number of via spacings included in one full turn of the circuit in the denominator. That is, Figure 3 shows a conductor pattern 141 with a winding amount of 7/8.

Similarly, in this case, the portion of the circuit without a conductor pattern 141 in one layer is called the pattern gap, and the relative length of the pattern gap to the length of one turn of the circuit 143 is hereafter referred to as the "gap amount." The relative length of the "gap amount" is defined as the distance between via positions at both ends of the conductor pattern 141 that are in contact with the portion where the pattern gap is formed. That is, Figure 3 shows a pattern gap with a gap amount of 1/8. Since the circuit always completes one turn, the sum of the "winding amount" and the "gap amount" is always 1 in each layer.

All other conditions being equal, forming the conductor 14 with a conductor pattern 141 that has a larger winding amount is desirable because it improves the inductance and insulation characteristics of the coil component 1. That is, a larger winding amount means a smaller gap, and the magnetic flux leaking from the core surrounded by the coil conductor through the pattern gap is reduced, thus improving the inductance characteristics.

Furthermore, a larger winding capacity allows for a tighter spiral winding of the coil conductor, which in turn allows for a minimum number of layers and maximum spacing between layers, resulting in improved insulation properties. In addition, minimizing the number of layers also has the benefit of reducing labor costs in the production process.
The maximum winding capacity that is the limit for manufacturing will be referred to as the "maximum winding capacity" below. The "maximum winding capacity" is a quantity related to the shape and length of the conductor pattern's peripheral circuitry, as well as the size of the vias, and will be explained in detail later.

Furthermore, the detailed structure of the conductor 14 will be explained using Figure 4. For the sake of explanation, a rectangular circuit as shown in Figure 4 will be used as an example below, but the shape of the circuit is not limited to this.
Figure 4 shows the detailed structure of the conductor 14 of the coil component 1.
Figure 4 shows the conductor patterns 141 of each stacked layer arranged in the order of stacking. For example, the left side of Figure 4 is the top and the right side is the bottom. The coil component 1 has cover layers that do not contain the conductor patterns 141 above and below the layers that contain the conductor patterns 141, but these are omitted in the figure. The same applies to Figures 7, 8, 13, 14, 15, and 16.

Figure 4 shows a rectangular circuit 143, with via positions 144 indicating that the circuit 143 is divided into 12 equal parts. Therefore, the winding amount of the conductor pattern 141 in each layer is 11/12. The circuit 143 may be divided into any number of equal parts. It is preferable that the circuit 143 is divided into the maximum number of parts in the design; in this case, the conductor pattern 141 in each layer will have the maximum winding amount. Here, we will explain assuming that the maximum winding amount in Figure 4 is 11/12. That is, in the example shown in Figure 4, the conductor pattern 141 in each layer has the maximum winding amount.

The uppermost layer of the conductor pattern 141 is an upper lead layer 145, having a lead portion 145a with one end connected to the conductor pattern 141 and the other end connected to the external electrode 12. The lowermost layer of the conductor pattern 141 is a lower lead layer 146, having a lead portion 146a with one end connected to the conductor pattern 141 and the other end connected to the external electrode 12. For the upper lead layer 145 and the lower lead layer 146, the amount of winding is determined by the portion of the conductor pattern 141 excluding the lead portions 145a and 146a.

Between the upper lead layer 145 and the lower lead layer 146, a total of eight circumferential layers 147 are provided, each with the same winding amount of 1 1/12, and where the formation position of the vias 142 is shifted by one interval from the via position 144. The pattern gaps 141c in the conductor pattern 141 of each layer are the same gap amount of 1/12 and are sequentially shifted; therefore, the pattern gaps 141c do not overlap between adjacent layers.

The conductor patterns 141 of the upper lead layer 145 and the eighth perimeter layer 147 are connected in a spiral series via each via 142. Furthermore, the vias 142 of the eighth perimeter layer 147, labeled "H," are connected to the short pattern section 141a of the lower lead layer 146. As a result, a spiral structure is formed, extending from the connection between the lead section 145a of the upper lead layer 145 and the conductor pattern 141 to the connection between the lead section 146a of the lower lead layer 146 and the short pattern section 141a.

Here, the number of turns in the helical structure that satisfies the required inductance characteristics for coil component 1 is assumed to be, for example, 8 turns. Furthermore, to accommodate the arrangement of the lead-out sections 145a and 146a, an additional 1/2 turn is required for the number of turns in the helical structure. In the example in Figure 4, the number of turns in the helical structure is "8 + 4/12" turns.

The lower lead-out layer 146 is provided with an additional pattern section 148 connected to the short pattern section 141a. Since the additional pattern section 148 also extends along the circumferential circuit 143, it extends along the conductor patterns 141 of the other layers. Because one end of the short pattern section 141a is connected to the lead-out section 146a, the additional pattern section 148 extends along the circumferential circuit 143 from the side of the short pattern section 141a opposite to the side connected to the lead-out section 146a. The combined winding amount of the short pattern section 141a and the additional pattern section 148 is "11/12," which is the same as the winding amount of the conductor patterns of the other layers. Furthermore, the gap amount of the combined pattern of the short pattern section 141a and the additional pattern section 148 is the same as the gap amount of the pattern gap 141c in the conductor patterns 141 of each layer, which is 1/12.

One end of the additional pattern section 148 is connected to the short pattern section 141a, and the other end of the additional pattern section 148 is connected to the conductor pattern 141 of the "H" circumferential layer 147 via the additional via 142a. In other words, the additional via 142a is located in the middle of the conductor pattern 141, not at either end, and the additional pattern section 148 is connected in parallel to a portion of the conductor pattern 141 in the "H" circumferential layer 147, specifically to the section 141b of the conductor pattern 141 from the additional via 142a to via 142.

In the conductor structure 14 shown in Figure 4, since the conductor pattern 141 of each layer has the same winding amount, the pressure is distributed evenly during crimping after lamination, suppressing distortion of the helical structure. While it is desirable for the length of the additional pattern section 148 to be such that the conductor pattern 141 of each layer has the same winding amount, it is not limited to this length. Even if the length of the additional pattern section 148 is other, its presence still distributes the pressure during crimping compared to the case where the additional pattern section 148 is absent.

Furthermore, the arrangement of the conductor patterns 141, where the pattern gaps 141c do not overlap at least between adjacent layers, also contributes to pressure distribution during crimping. Moreover, the winding amount per layer being "9/10" or more ensures that the pattern gaps 141c are sufficiently narrow, further contributing to pressure distribution.

In the conductor 14 structure shown in Figure 4, the conductor pattern 141 has its maximum winding length, resulting in a small pattern gap relative to the conductor pattern 141. Therefore, compared to the case where the maximum winding length is not present, the stability against pressure during crimping is higher, and the characteristics of the coil component 1 are improved. Furthermore, because the DC resistance of the conductor 14 is reduced due to the presence of an additional pattern section 148 connected in parallel with a portion of the conductor pattern 141b, the characteristics of the coil component 1 are also improved.

Here, we will explain how to calculate the maximum winding amount.
Figure 5 shows the via positions corresponding to the maximum winding amount, and Figure 6 shows the land shape of the vias. At each via position 144 shown in Figure 5, vias 142 with the land shape shown in Figure 6 are arranged at equal intervals. The number of via positions 144 shown in Figure 5 is an example to illustrate the concept of the maximum winding amount, and the actual number of via positions 144 is not limited to the number shown in Figure 5.
The maximum winding amount A within a single layer can be calculated using the following equations (1), (2), and (3).
A = (n-1)/n (where n is the maximum number of via positions) ... (1)
n = (Circuit length L) ÷ (Pattern gap length m + Via hole diameter R + Margin k)
... (2)
R ≥ 2 × √(Cross-sectional area S of the coil conductor ÷ π) ……(3)

Equation (3) shows that the area of the circular via 142 is equal to or greater than the area S of the cross-section perpendicular to the stretching direction in the conductor pattern 141. This prevents degradation of DC resistance in the via 142 portion. The conductor pattern width PH and conductor pattern thickness are selected so that the cross-sectional area S of the surface perpendicular to the circumferential direction of the coil conductor is an appropriate value.
Margin k is a margin provided in the direction of the circumferential circuit required in the manufacturing process to prevent via holes from being formed beyond the ends of the conductor pattern, and is generally a predetermined value of 30 μm or more. Margin kH is a margin provided in the width direction of the conductor pattern 141 required in the manufacturing process to prevent via holes from being formed beyond the conductor pattern width PH, and is generally a predetermined value of 30 μm or more. By setting margin k and margin kH to be equal, a circular land shape as shown in Figure 6 can be obtained. The land shape can be elliptical, rectangular, or other shapes. The land width RH relative to the conductor pattern width PH is arbitrary, but is usually designed to be equal or larger. Figure 6 is an example where the land width RH is large relative to the conductor pattern width PH.

The circumference length L of the circuit 143 is the length of the line passing through half the width PH of the conductor pattern. In the case where the circuit 143 is an ellipse, it is determined as the circumference of the ellipse passing through half the width PH of the conductor pattern. The minor and major axes of this ellipse are obtained by adding half the width of the circuit 143 to the minor axis ra and major axis rb of the core surrounded by the coil conductors. When the land width RH is equal to the conductor pattern width PH, the minor and major axes of the ellipse representing the circumference length L are obtained by adding half the land width RH to the minor axis ra and major axis rb of the core surrounded by the coil conductors.

The pattern gap length m is the minimum value such that m ≥ R and the via positions 144 are equally spaced. Therefore, the largest integer value less than or equal to the value of n obtained by substituting m = R into equation (2) is the desired value of n. Substituting this value of n into equation (1) allows the maximum winding amount A to be calculated.

To improve the characteristics of coil component 1, it is desirable that the winding amount of the conductor pattern 141 be the maximum winding amount A determined by the above equations (1), (2), and (3). Furthermore, it is desirable that the gap amount be as small as possible, and that the pattern gap length be as short as possible.

The circuit formed by the patterned conductor is usually set to have a large inductance value. Therefore, in a typical coil component where the ratio of the outer dimensions of the coil component is long side:short side = 2:1, the ratio of the long side to the short side of the circuit formed by the conductor pattern contained inside will be greater than 2 when considering the distance from the outer surface of the coil component. If the circuit is rectangular, the long side and short side dimensions are the dimensions of the long side and the short side, respectively. If the circuit is elliptical, the long side and short side dimensions are the dimensions of the major axis and the minor axis, respectively.
As mentioned above, considering the structural symmetry of the coil component, it is desirable that vias be positioned at equal intervals and in an even number.

Therefore, let's consider via positions 144, which are arranged in even numbers and at equal intervals.
If the spacing between the equally spaced via positions 144 is greater than the dimension of the shorter side of the circuit 143, then on the entire shorter side of one of the coil components, there will be a section where neither the vias 142 nor the conductor pattern 141 exist. This is undesirable because it makes the coil more susceptible to deformation due to the difference in contraction between the conductor and the magnetic material.

If the shorter side of the circuit 143 has a spacing equal to one equally spaced via position 144, then two via positions 144 can exist on the shorter side, thereby suppressing coil deformation. Since a greater via spacing can be designed on the longer side of the circuit 143 than on the shorter side, the maximum number n of via positions 144 becomes greater than 6. Therefore, the maximum winding amount A becomes 5/6 or greater.

If the shorter side of the circuit 143 has a spacing equal to two equally spaced via positions 144, then three via positions can exist on the shorter side, which significantly suppresses coil deformation. On the longer side of the circuit 143, more via spacing can be designed than on the shorter side, so the maximum number of via positions n is greater than 8, and the maximum winding amount A is 7/8 or more.
The dimension of the shorter side of the circuit 143 may be greater than or equal to the spacing between three equally spaced via positions 144.

As mentioned above, in a typical coil component 1, the ratio of the length of the longer side to the shorter side of the circumferential circuit 143 formed by the enclosed conductor pattern 141 is greater than 2 when considering the distance from the outer surface of the coil component 1. Therefore, when the shorter side of the circumferential circuit 143 corresponds to one or two equally spaced via positions 144, the maximum number of via positions 144 n is 8 and 10, respectively. That is, the maximum winding amount A is 7/8 and 9/10.

Based on these considerations, a winding ratio of 5/6 or 7/8 is desirable, and a winding ratio of 9/10 or higher is more desirable. In reality, the length of the conductor pattern 141 is longer than the value calculated from the winding ratio because it includes the land patterns of the vias at both ends, not just the distance between via positions. In other words, it is desirable for the conductor pattern 141 to extend to a length of 83.3% or more, 87.5% or more, of the circumference within the layer, and more preferably to a length of 90% or more.

The coil component 1 in one embodiment of the present invention will be described below in comparison with a comparative example. In the following, redundant explanations of components similar to those of the previously described embodiment may be omitted.
Figure 7 shows the structure of the conductor in the first comparative example of the coil component.
The coil component 1001 in the comparative example shown in Figure 7 has an upper lead layer 145 and a lower lead layer 146, and a total of eight circumferential layers 147, similar to the coil component 1 in the embodiment described above.
In the comparative example shown in Figure 7, assuming that the number of turns of the helical structure satisfying the inductance characteristics is, for example, 8 turns, an additional 1/2 turn of the helical structure is required to accommodate the arrangement of the lead-out sections 145a and 146a.

In the comparative example shown in Figure 7, the coil component 1001 uses via positions 144 that divide the peripheral circuit 143 into six equal parts, resulting in a helical structure with "8 + 2/6" (= 50/6) turns. This number of turns is then evenly distributed among the 10 layers, resulting in a turn count of "5/6" per layer.
In the comparative example shown in Figure 7, the amount of winding in each layer is uniform, so the pressure is distributed throughout during crimping after lamination. However, since the amount of winding in one layer is less than "11/12" in the coil component 1 of the embodiment described above, the performance of the coil component 1001 is inferior.

When the number of turns x required for the spiral structure of a coil component is evenly distributed across the number of stacked layers N, the amount of turns B per layer can be calculated as B = x ÷ N. This amount of turns B is, of course, limited to less than or equal to the maximum amount of turns A mentioned above. Furthermore, the constraint that equally spaced via positions 144 are used on the circumferential circuit 143 is also added, and the number of layers N is adjusted to satisfy these constraints. As a result, the amount of turns B is smaller than the maximum amount of turns A, except in exceptional cases, and the structure of the coil component 1 in the above-described embodiment improves the characteristics of the coil component.

Figure 8 shows the structure of the conductor in the second comparative example of the coil component.
The coil component 1002 in the comparative example shown in Figure 8 also has an upper lead layer 145 and a lower lead layer 146, and a total of eight circumferential layers 147, and, similar to the coil component 1 of the embodiment described above, the conductor pattern 141 has the maximum winding amount. However, in the comparative example shown in Figure 8, the lower lead layer 146 has a short pattern portion 141a and a lead portion 146a, and the winding amount of the conductor pattern 141 is less than that of the other layers.
If there is a layer with fewer turns of the conductor pattern 141 than other layers, there is a risk that pressure unevenness will occur during crimping after lamination, causing coil distortion or other problems.

Figures 9 and 10 are schematic diagrams illustrating the conditions under which pressure imbalances occur. Figure 9 shows a perspective view, and Figure 10 shows a cross-sectional view.
When a layer of short pattern portion 141a and a layer of conductor pattern 141 with a large winding amount are laminated and pressure is applied as shown by arrow P in Figure 9, the pressure difference concentrates in region R1 due to the difference in contraction between the conductor and the magnetic material. As a result, the entire laminated structure may tilt diagonally as shown by arrow T in Figure 9, or distortion may occur in the conductor pattern 141 as shown in Figure 10, which can cause deterioration in the performance of the coil component. Furthermore, if deformation occurs in the coil, short-circuit defects and a decrease in inductance may occur due to contact between conductor patterns in adjacent layers, and the yield when cutting the inductor from the laminate may also deteriorate.

Figures 11 and 12 are schematic diagrams illustrating a situation where pressure is distributed. Figure 11 shows a perspective view, and Figure 12 shows a cross-sectional view.
When the additional pattern section 148 is connected to the short pattern section 141a, the winding amount becomes close to the winding amount in the conductor pattern 141 of the other layers. As a result, even when pressure is applied as indicated by arrow P, the pressure is distributed to each layer, and distortion of the laminated structure and the conductor pattern 141 is suppressed.

Figure 13 shows the structure of the conductor in a modified example compared to the second comparative example shown in Figure 8.
In the modified example shown in Figure 13, the lower lead layer 146 includes a short pattern section 141a and a lead section 146a, as well as an additional pattern section 1408. As a result, the amount of winding in the lower lead layer 146 is equivalent to the amount of winding in the conductor patterns 141 of the other layers, and the pressure is distributed throughout during crimping after lamination, suppressing coil distortion caused by crimping after lamination.

However, in the modified example shown in Figure 13, the additional pattern portion 1408 is connected to the short pattern portion 141a at one end, and no current flows through it, so it does not contribute to the characteristics of the coil component 1002. In other words, in the modified example shown in Figure 13, the increase in conductor patterns that do not contribute to the characteristics of the coil component 1002 hinders the efficient use of material, and the characteristics of the coil component 1002 do not improve.
Thus, the coil component 1 of the above-described embodiment is superior when compared to any of the comparative examples.

Next, other embodiments of the present invention will be described.
Figure 14 shows a comparative example to be compared with the second embodiment of the present invention. Figure 15 shows the second embodiment of the present invention.
In the comparative example coil component 1003 in Figure 14, via positions 144 that divide the circumferential circuit 143 into eight equal parts are used, and the total number of turns in the helical structure is "5 + 2/8" (= 42/8). Also, in the comparative example in Figure 14, an upper lead layer 145 with lead portion 145a, a lower lead layer 146 with lead portion 146a, and a total of four circumferential layers 147 are stacked. The "42/8" turns are evenly distributed among the six layers, resulting in a winding amount of "7/8" per layer.

In contrast to this comparative example, the coil component 100 of the second embodiment shown in Figure 15 uses via positions 144 that divide the circumferential circuit 143 into 10 equal parts, resulting in a large winding amount of "9/10" per layer. That is, the conductor pattern 141 extends to a length that reaches more than 90% of one circumference within a single layer. Furthermore, an upper lead layer 145 with lead portions 145a, a lower lead layer 146 with lead portions 146a, and a total of four circumferential layers 147 are stacked.

The lower lead layer 146 is provided with a short pattern section 141a connected to the lead section 146a, and an additional pattern section 148 connected to the short pattern section 141a. The combined winding amount of the short pattern section 141a and the additional pattern section 148 is "9/10". Furthermore, the additional pattern section 148 is connected to the conductor pattern 141 of the adjacent layer via an additional via 142a, and the additional pattern section 148 is connected in parallel to a portion of the conductor pattern 141b.

In the second embodiment as well, the winding amount of the conductor pattern 141 in each stacked layer is the same, and parallel connections of the conductor pattern 141 are formed in some areas, so that coil distortion during crimping is suppressed and the characteristics of the coil component 100 are improved. Thus, the structure of one embodiment of the present invention can be applied even if the total number of windings of the helical structure is different.
In the second embodiment, the gap size of the pattern gap 141c is "1/10", which is sufficiently small. When the pattern gap 141c within one layer is sufficiently small, the proportion occupied by the conductor pattern 141 when stacked increases, and the distortion of the coil when crimped is further suppressed.

Figure 16 shows a third embodiment of the present invention.
In the coil component 200 of the third embodiment shown in Figure 16, via positions 144 that divide the circumferential circuit 143 into 10 equal parts are used, similar to the first embodiment, and the number of turns in the helical structure is "8 + 4/12" turns, with the amount of turns in each layer being "11/12". Also, in the coil component 200 of the third embodiment, similar to the first embodiment, an upper lead layer 145 having a lead portion 145a, a lower lead layer 146 having a lead portion 146a, and a total of 8 circumferential layers 147 are stacked.

In the coil component 200 of the third embodiment, five conductor patterns 141 are connected in series in a spiral manner from the upper lead layer 145, and five conductor patterns 141 are also connected in series in a spiral manner from the lower lead layer 146. The connection between the upper five layers and the lower five layers creates a short pattern section 141a in the circumferential layer 147 located in the middle of the lamination. The portion of the conductor pattern 141 of the circumferential layer 147 excluding the short pattern section 141a becomes an additional pattern section 148. The additional pattern section 148 is connected in parallel to a portion 141b of the conductor pattern 141 of an adjacent layer via an additional via 142a.

Thus, the parallel structure of the additional pattern section 148 may be provided in an intermediate layer of the lamination. Note that the circumferential layer 147, shown in Figure 16, which includes the short pattern section 141a and the additional pattern section 148, and the circumferential layer 147, which includes a section 141b where the additional pattern section 148 is connected in parallel, have symmetrical conductor pattern shapes 141. Therefore, these circumferential layers 147 can be interpreted as having interchangeable roles for the additional pattern section 148 and the parallel-connected section 141b.

In the coil component 200 of the third embodiment, the upper five layers and the lower five layers have a symmetrical structure. Therefore, the conductor 14 does not change in structure when the coil component 200 is reversed by swapping the lead portions 145a of the upper lead layer 145 and 146a of the lower lead layer 146. In other words, the coil component 200 of the third embodiment is highly practical because there is no need to distinguish between upper and lower during mounting, and there is no change in characteristics.

1,100,200 Coil component 2 Circuit board 2a Substrate 3 Land area 11 Base 111 Magnetic sheet 12 External electrode 14 Conductor 141 Conductor pattern 141a Short pattern area 142 Via 142a Additional via 143 Peripheral circuit 144 Via position 145 Upper lead layer 146 Lower lead layer 145a, 146a Lead area 147 Peripheral layer 148 Additional pattern area

Claims (10)

The conductor patterns of the multiple layers stacked in a series are connected in a spiral manner so that the overlapping of the conductor patterns of each layer forms a circular circuit when viewed from the stacking direction, and the conductor patterns of the multiple layers include spiral conductors that are shorter than the conductor patterns of the other layers.
A pair of lead wires are connected to both ends of the aforementioned helical conductor and are drawn out from the circumferential circuit when viewed from the stacking direction,
A magnetic substrate comprising multiple layers of magnetic material, which encloses the helical conductor,
A pair of external electrodes are provided on the outer surface of the magnetic substrate, and each of the pair of lead wires is connected to them,
A parallel pattern is provided on the layer having the short pattern, extending in parallel from one end of the short pattern along the conductor pattern of the adjacent layer, with the extended end connected to the conductor pattern of the adjacent layer;
Equipped with ,
The coil component is characterized in that the conductor patterns constituting the helical conductor are connected to each other by vias of diameter R, and when the length L of the circumferential circuit is used as the largest integer value n less than or equal to the quotient obtained by dividing the length L of the conductor pattern by the sum of the width PH of the conductor pattern and the diameter R of the via, the conductor patterns other than the short pattern are composed of (n-1)/n of the circumferential circuit . The coil component according to claim 1, characterized in that the short pattern is located in an intermediate layer among the multiple layers. The coil component according to claim 1 or 2, characterized in that the conductor structure, combining the helical conductor and the parallel pattern, is symmetrical with respect to the reversal of the coil component in the direction in which the pair of lead wires are swapped. The coil component according to any one of claims 1 to 3, characterized in that, among the conductor patterns constituting the helical conductor, the conductor patterns other than the short pattern extend to a length reaching 90% or more of one circumference within the layer. The coil component according to any one of claims 1 to 4, characterized in that, when the winding amount is expressed as a fraction with the length of one turn of the circuit as the denominator and the length of the conductor pattern as the numerator, using the interval along the circuit between the connection points of the conductor patterns of each layer projected onto the circuit as viewed from the stacking direction, the winding amount of the conductor patterns other than the short pattern that constitute the helical conductor is equal to the winding amount of the pattern that combines the short pattern and the parallel pattern. The coil component according to any one of claims 1 to 5 , characterized in that the conductor pattern constituting the helical conductor has a thickness in the stacking direction that is greater than the spacing between them in the stacking direction. The coil component according to any one of claims 1 to 6 , characterized in that the gaps between the ends of the extended conductor pattern do not overlap in the stacking direction, at least between adjacent layers. A coil component according to any one of claims 1 to 7 ,
A circuit board on which the aforementioned coil component is mounted,
A circuit board characterized by comprising the following features. An electronic device characterized by comprising the circuit board described in claim 8 . A manufacturing method for producing a coil component according to any one of claims 1 to 7 ,
A step of laminating multiple layers including the conductor pattern and the parallel pattern that constitute the helical conductor, and multiple layers of magnetic material that constitute the magnetic substrate,
A process of forming a laminate by pressing together multiple stacked layers,
A method for manufacturing a coil component, characterized by having the following features.