JP2006310705A - Process for manufacturing planar coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for manufacturing a planar coil having aspect ratio of 1 or larger in a stable manner. <P>SOLUTION: The manufacturing process comprises a step for preparing an insulating substrate, having a spiral patterned underlying conductor layer on at least one surface (S01-S07), and a step for forming a coil conductor by immersing the insulating substrate into plating liquid, thereby performing electrolytic plating on the underlying conductor layer (S08). The plating liquid is copper sulfate based plating liquid, containing polymer and brightener, and the concentration of brightener in the plating liquid is managed so as to be in the range of 4-25 ml/l in the forming process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a planar coil.

As a method of manufacturing a planar coil used in a circuit element, a manufacturing method of forming a coil conductor by forming a base conductor layer in a coil shape on at least one surface of an insulating substrate and subjecting the coiled base conductor layer to electrolytic plating (See, for example, Patent Document 1 below).
JP 2004-342645 A

  In the manufacturing method described in Patent Document 1, a plating solution whose main component is copper sulfate, sulfuric acid, or ethylene glycol is used as a plating solution for performing electrolytic plating. This manufacturing method is intended to improve the aspect ratio of the coil conductor (the ratio of the height to the width of the coil conductor). In Patent Document 1, a coil conductor having an aspect ratio of 1 or more is formed. Is described.

  However, when a high aspect ratio coil conductor having an aspect ratio of 1 or more is actually formed, there is a technical problem to be solved that irregularities are generated on the surface of the coil conductor and undulation may occur.

  Therefore, an object of the present invention is to provide a planar coil manufacturing method that can stably manufacture a planar coil having an aspect ratio of 1 or more.

  The method for manufacturing a planar coil according to the present invention includes a preparation step of preparing an insulating substrate having a base conductor layer patterned in a spiral shape on at least one surface, a step of immersing the insulating substrate in a plating solution, Forming a coil conductor by performing electrolytic plating, and the plating solution is a copper sulfate-based plating solution containing a polymer and a brightener. In the forming step, the concentration of the brightener in the plating solution is 4 to 4. It is characterized by being managed so as to be 25 ml / l.

  According to the present invention, since the brightener concentration in the plating solution is managed to be 4 to 25 ml / l in the forming process, the growth rate of the coil conductor in the direction perpendicular to the insulating substrate can be stably increased. The coil conductor can be anisotropically grown.

Moreover, in the manufacturing method of the planar coil which concerns on this invention, it is also preferable that the electric current density of electrolytic plating shall be 10-20 A / dm < ² > in a formation process. Since electrolytic plating is performed with a high current density, the coil conductor can be more anisotropically grown.

  Moreover, in the manufacturing method of the planar coil which concerns on this invention, a polymer is polyethyleneglycol, It is also preferable to manage so that the density | concentration of the polymer in a plating solution may be 1-60 ml / l in a formation process. Since the polymer concentration is controlled to be 1 to 60 ml / l, the coil conductor can be uniformly formed.

  Moreover, in the manufacturing method of the planar coil which concerns on this invention, it is also preferable to manage so that the chlorine concentration in a plating solution may be 30-70 ppm in a formation process. Since the chlorine concentration is controlled to be 30 to 70 ppm, the polymer can function effectively.

  Moreover, in the manufacturing method of the planar coil which concerns on this invention, it is also preferable to manage so that the copper sulfate density | concentration in a plating solution may be 100-200 g / l in a formation process. Since the copper sulfate concentration is controlled to be 100 to 200 g / l, it is possible to suppress the occurrence of waviness in the coil conductor pattern and to suppress the film quality of the coil conductor from becoming coarse.

  Moreover, in the manufacturing method of the planar coil which concerns on this invention, it is also preferable to manage so that a sulfuric acid concentration may be 150-200 ml / l in a formation process. Since the sulfuric acid concentration is controlled to be 150 to 200 ml / l, it is possible to suppress the occurrence of waviness in the coil conductor pattern and to suppress the film quality of the coil conductor from becoming rough.

  In the planar coil manufacturing method according to the present invention, the aspect ratio of the conductor formed in the forming step is 1 or more.

  According to the present invention, since the coil conductor can be stably anisotropically grown in the direction perpendicular to the insulating substrate in the forming step, a planar coil having an aspect ratio of 1 or more can be manufactured stably.

  The teachings of the present invention can be readily understood by considering the following detailed description with reference to the accompanying drawings shown for illustration only. Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  Prior to describing a method for manufacturing a planar coil according to an embodiment of the present invention, a coil element using the planar coil will be described. FIG. 1 is a perspective view of the coil element 1a. The coil element 1a is a surface mount type coil element. The coil element 1a includes a flat core structure 10 and external terminals 20 that are electrically connected to other substrates. The core structure 10 is composed of a bridge-type ferrite core 11 and a protruding ferrite core 12, and the bridge-type ferrite core 11 and the protruding ferrite core 12 are combined to form a flat plate shape as a whole.

  An exploded perspective view of the coil structure 10 is shown in FIG. The bridge-type ferrite core 11 includes a rectangular flat plate portion 111 and leg portions 112 extending perpendicularly to the flat plate portion 111. A pair of leg portions 112 are provided. One leg portion 112 extends from one side of the flat plate portion 111 and the other leg portion 112 extends from the side parallel to the one side in the same direction. Therefore, when the bridge-type ferrite core 11 is arranged so that the leg portion 112 stands on the protruding ferrite core 12, a gap is formed between the flat plate portion 111 of the bridge-type ferrite core 11 and the protruding ferrite core 12. .

  The protruding ferrite core 12 has a rectangular flat plate portion 121 and a protruding portion 122 protruding from the central portion of the flat plate portion 121. The protrusion 122 is a convex portion having a prismatic shape. When the core structure 10 is configured by abutting the distal end surface of the leg portion 112 of the bridge-type ferrite core 11 to the flat plate portion 121 of the protruding ferrite core 12, an outer shell portion that is substantially a closed magnetic path is configured. The protrusion 122 is arranged inside the outer shell. The detailed structure of the bridge type ferrite core 11 and the protruding type ferrite core 12 will be described later as appropriate.

  FIG. 3 shows a perspective view of the state where the external terminal 20 is removed from the state of FIG. As shown in FIG. 3, a coil substrate 30 (planar coil) is placed in a gap between the bridge type ferrite core 11 and the protruding type ferrite core 12 constituting the core structure 10, and is fixed with an adhesive 40. Yes. One end face of the coil substrate 30 is exposed from the end face where the gap portion of the core structure 10 faces. At this one end surface, the insulating substrate 31, the lead-out end electrode 32, and the protective resin layer 33 are exposed. The insulating substrate 31 is a substrate that is a basic part of the coil substrate 30. The lead-out end electrode 32 is electrically connected to a coil conductor, which will be described later, and is a portion that is also electrically connected to the external terminal 20 shown in FIG. The protective resin layer 33 is a resin layer provided to protect the coil substrate 30.

  The coil substrate 30 will be described with reference to FIG. FIG. 4 is a plan view of the coil substrate 30. A hole 35 is formed in the central portion of the coil substrate 30. A coil conductor 34 is formed so as to surround the hole 35. The coil conductor 34 is formed in a spiral shape so as to surround the hole 35 outward from a portion desired for the hole 35. The coil conductors 34 are formed on both surfaces of the coil substrate 30 and are electrically connected to the lead-out end electrodes 32, respectively.

  The lead-out end electrode 32 connected to the coil conductor 34 formed on one surface of the coil substrate 30 and the lead-out end electrode 32 connected to the coil conductor 34 formed on the other surface are respectively Provided on opposite sides of the coil substrate 30. In addition, the coil conductors 34 provided on both surfaces of the coil substrate 30 are electrically connected to each other by front and back contact portions 36 formed at the peripheral edge portion of the hole 35. Therefore, when a voltage is applied between the lead-out end electrode 32 provided on one side of the coil substrate 30 and the lead-out end electrode 32 provided on the other side, it is formed on one surface of the coil substrate 30. A current flows from the coil conductor 34 formed to the coil conductor 34 formed on the other surface.

  The protruding portion 122 of the protruding ferrite core 12 is inserted into the hole 35 of the coil substrate 30. In order to explain this situation, FIG. 5 shows a cross-sectional view in the vicinity of the protrusion 122 of the protrusion-type ferrite core 12 in FIG. As shown in FIG. 5, the protruding portion 122 of the protruding ferrite core 12 is inserted into the hole 35 of the coil substrate 30. The protruding portion 122 of the protruding ferrite core 12 is formed slightly shorter than the leg portion 112 of the bridge type ferrite core 11. Accordingly, a gap is generated between the tip of the protrusion 122 and the bridge-type ferrite core 11, and the minute gap 41 can be formed. The minute gap 41 is provided in order to prevent the bridge-type ferrite core 11 and the protruding ferrite core 12 from being magnetically saturated with a current flowing through the coil conductor 34 of the coil substrate 30. Since the core structure 10 has an ultra-compact shape with one side of several millimeters or less, the dimension of the minute gap 41 (distance between the tip of the protrusion 122 and the bridge-type ferrite core 11) is preferably 0. .1 to 100 μm, more preferably 0.1 to 50 μm.

  Subsequently, a manufacturing method of the coil substrate 30 (planar coil) in the present embodiment will be described with reference to FIGS. FIG. 6 is a diagram showing the procedure of the manufacturing method in the present embodiment. 7 and 8 are views for explaining a method of manufacturing the coil substrate 30, and illustrate a cross section of a portion corresponding to a part of the coil substrate 30. 7 and 8 will be referred to as needed while explaining the procedure of the manufacturing method according to FIG.

  First, the insulating substrate 31 is prepared (see step S01 in FIG. 6 and FIG. 7A). It is assumed that the insulating substrate 31 has a thickness of 60 μm, a glass cloth is impregnated with BT resin, and a hole 35 is already formed (not shown in FIG. 7).

  Subsequently, the underlying conductor layer 60 is simultaneously formed on the front and back surfaces of the insulating substrate 31 by electroless plating (see step S02 in FIG. 6 and FIG. 7B). A photoresist layer 61 is simultaneously electrodeposited on each of the underlying conductor layers 61 formed simultaneously on the front and back surfaces of the insulating substrate 31 (see step S03 in FIG. 6 and FIG. 7C). In the photoresist layer 61 formed on the front and back surfaces, exposure is performed on each side of the front and back surfaces by photolithography along the pattern on which the coil conductor (see FIG. 4) is to be formed, and then development is performed simultaneously on the front and back surfaces. Then, the removal portion 611 is formed (see step S04 in FIG. 6, (D) in FIG. 7).

  Using the photoresist layer 61 thus patterned as a plating mask, a portion corresponding to the removal portion 611 in FIG. 7D is selectively subjected to electrolytic plating to simultaneously coat both the front and back surfaces of the coil conductor plating layer 62. (See step S05 in FIG. 6 and FIG. 8A). After this coil conductor plating layer 62 is formed, the photoresist layer 61 as a plating mask is peeled and removed simultaneously on both the front and back surfaces (see step S06 in FIG. 6 and FIG. 8B).

  From the state shown in FIG. 8B, the base conductor layer 60 other than the portion where the coil conductor plating layer 62 is formed is removed by etching, and the base conductor layer 60a is insulated from the coil conductor plating layer 62. It remains between the substrate 31 (see step S07 in FIG. 6 and (C) in FIG. 8). In this embodiment, the insulating substrate 31 having the base conductor layer 60a patterned as shown in FIG. 8C is formed by performing steps S01 to S07 (preparation step). An insulating substrate that has undergone the above process may be prepared.

  After that, without the selective plating mask, the coil conductor plating layer 62 is further grown and formed by electrodeposition by an electrolytic plating method (step S08 in FIG. 6). Thereby, a sufficiently thick conductor portion as the coil conductor 34 is obtained. The coil conductor 34 can be grown and formed at a high density until the gap between adjacent coil conductors is 15 μm or less. This is because the plating layer is formed in proportion to the amount of electricity in the height direction, whereas the rate at which the plating layer is formed in the width (gap) direction becomes slower as the gap becomes narrower.

Step S08 will be further described. The current density in step S08 is 10 to 20 A / dm ² . This is because the coil conductor plating layer 62 is anisotropically grown in the vertical direction of the insulating substrate 31 by keeping the current density high. The plating solution used in step S08 is a copper sulfate-based plating solution containing a polymer and a brightener. In the present embodiment, leveler and chlorine are further included.

  In step S08, the copper sulfate concentration in the plating solution is managed to be 100 to 200 g / l. Further, the sulfuric acid concentration in the plating solution is managed to be 150 to 200 ml / l. When the copper sulfate concentration is less than 100 g / l, the supply of copper is insufficient, and the coil conductor 34 is swelled. On the other hand, when the copper sulfate concentration exceeds 200 g / l, the supply of copper becomes excessive and the film quality on the surface of the coil conductor 34 becomes rough.

  The polymer is contained in order to suppress copper deposition, and is used to uniformly form the coil conductor 34 by the polarization effect. As the polymer, polyether compounds such as polyethylene glycol, polypropylene glycol, polyethylene oxide, and polyoxyalkylene glycol are used. Among these polymers, it is particularly preferable to use polyethylene glycol. In step S08, the polymer concentration in the plating solution is controlled to be 1 to 60 ml / l.

  Chlorine is contained to make the polymer function. In step S08, the concentration of chlorine in the plating solution is controlled to be 30 to 70 ppm. If the chlorine concentration is below 30 ppm, the polymer cannot function sufficiently and pits are generated. On the other hand, when the chlorine concentration exceeds 70 ppm, the chlorine concentration becomes excessive, the function of the polymer is inhibited, and branch-like abnormal growth occurs.

  The brightener is contained to promote copper deposition, and is used to form the coil conductor 34 sufficiently thick due to the depolarization effect. Brighteners include 3-mercaptopropyl sulfonic acid (or its sodium salt), bis (3-sulfopropyl) disulfide (or its disodium salt, hereinafter collectively referred to as SPS), N, N-dimethyldithiocarbamic acid ( Sulfur compounds such as 3-sulfopropyl) ester (or its sodium salt) are used. In particular, it is preferable to use SPS. In step S08, the concentration of the brightener in the plating solution is controlled to be 4 to 25 ml / l.

  Brightener concentration control is performed by a Hull cell test or a CVS (Cyclic Voltammetric Stripping) method, particularly preferably a CVS method. The principle of the CVS method is as follows. By periodically changing the potential of the electrode immersed in the plating solution, copper is periodically deposited on the surface of the electrode, and the deposited copper is anodically dissolved. Since the amount of electricity obtained from the peak current when the deposited copper is anodicly dissolved corresponds to the mass of the deposited copper, the deposition rate and this amount of electricity are in a proportional relationship. Therefore, by measuring the amount of electricity, the concentration is determined based on the influence of the brightener on the deposition rate.

  When SPS is used as a brightener, a part thereof is reduced and transformed into a thiol compound (hereinafter referred to as MPS). MPS is further strongly reduced and decomposed and desulfurized. SPS is oxidized and decomposed into sulfonic acid and alcohol. Therefore, when the concentration is measured by the CVS method, a concentration obtained by adding SPS and MPS is obtained. In this embodiment, the SPS (including MPS) concentration is managed by the CVS method using “QUALIB QL-5” manufactured by FCI Technology.

  The leveler is contained to suppress copper deposition and smoothes the surface of the coil conductor 34. As the leveler, nitrogen compounds such as phenazine compounds, safranine compounds, polyalkyleneimines, thiourea derivatives, polyacrylic acid amides are used. It is particularly preferable to use a phenazine compound.

  After the formation of the coil conductor plating layer 62 is completed, the coil conductor 33 is formed on both surfaces of the insulating substrate 31, and then a protective resin layer 33 (solder resist) is printed on both surfaces of the insulating substrate 31. The coil substrate 30 is completed by covering and protecting the conductor 34.

  According to the manufacturing method of the coil substrate 30 (planar coil) in this embodiment, since the concentration of the brightener in the plating solution is controlled to be 4 to 25 ml / l in the step S06 which is a formation step, the insulating substrate 31 The growth rate of the coil conductor 34 in the direction perpendicular to the direction can be stably increased, and the coil conductor 34 can be anisotropically grown. Therefore, a planar coil having an aspect ratio (the ratio of the height to the width of the coil conductor) of 1 or more as shown in FIG. 8 can be manufactured stably.

It is a figure which shows the external appearance of the coil element containing the coil board | substrate manufactured by the manufacturing method which is embodiment of this invention. It is a figure which shows the core structure of FIG. It is a figure which shows a mode that the external terminal was taken from the coil element of FIG. It is a top view of the coil board | substrate of FIG. It is sectional drawing in the center vicinity of the coil element of FIG. It is a figure which shows the procedure of the manufacturing method which is embodiment of this invention. It is a figure for demonstrating the manufacturing method which is embodiment of this invention. It is a figure for demonstrating the manufacturing method which is embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a ... Coil element, 10 ... Core structure, 11 ... Bridge type ferrite core, 12 ... Projection type ferrite core, 20 ... External terminal, 30 ... Coil substrate, 31 ... Insulating substrate, 32 ... Derived end electrode, 33 ... Protective resin Layer, 34 ... coil conductor, 36 ... front and back contact part, 40 adhesive.

Claims (7)

A preparation step of preparing an insulating substrate having a base conductor layer patterned in a spiral shape on at least one surface;
Forming a coil conductor by immersing the insulating substrate in a plating solution and subjecting the base conductor layer to electrolytic plating to form a coil conductor,
The plating solution is a copper sulfate-based plating solution containing a polymer and a brightener,
In the forming step, the planar coil manufacturing method is characterized in that the concentration of the brightener in the plating solution is controlled to be 4 to 25 ml / l. ^{2. The} method for manufacturing a planar coil according to claim 1, wherein in the forming step, a current density of the electrolytic plating is 10 to 20 A / dm ² . The polymer is polyethylene glycol;
The method for producing a planar coil according to claim 1 or 2, wherein in the forming step, the concentration of the polymer in the plating solution is controlled to be 1 to 60 ml / l. In the said formation process, it manages so that the chlorine concentration in the said plating solution may be 30-70 ppm, The manufacturing method of the planar coil of any one of Claims 1-3 characterized by the above-mentioned. In the said formation process, it manages so that the copper sulfate density | concentration in the said plating solution may be 100-200 g / l, The manufacturing method of the planar coil of any one of Claims 1-4 characterized by the above-mentioned. In the said formation process, it manages so that the said sulfuric acid concentration may be 150-200 ml / l, The manufacturing method of the planar coil of any one of Claims 1-5 characterized by the above-mentioned. The method for manufacturing a planar coil according to claim 1, wherein an aspect ratio of the conductor formed in the forming step is 1 or more.

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