JP2009267291A - Coil component and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and high-performance coil component that improves the reliability as the coil component, and to provide a method of manufacturing the same. <P>SOLUTION: The coil component includes: a resist layer 108 being an insulating resin composed of a photosensitive resin; and a coil portion built in the resist layer 108. One surface of a coil pattern 102 composed of metal forming the coil portion is covered with a metal layer 110 composed of gold, silver, palladium, platinum, tin or nickel. The thickness of a metal layer 110b provided at the bottom of a via electrode 104 is smaller than that of a metal layer 110 provided over the surface of the coil pattern 102. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coil component widely used in an electronic device such as a mobile phone and a manufacturing method thereof.

  Conventional coil components aimed at miniaturization have been produced by forming a laminated coil by a production method represented by a ceramic green sheet method or a semi-additive method.

FIG. 10 is a perspective view showing the structure of a coil component manufactured by a semi-additive method which is a conventional method. In FIG. 10, reference numeral 202 denotes a substrate, and a wiring 204 is formed on the surface thereof. The wiring 204 is covered with a mold resin 206, and a part of the wiring 204 is connected to an external electrode 208 (for example, , See Patent Document 1).
Japanese Patent Laid-Open No. 9-270355

  However, the conventional coil component has a problem of the bonding strength between the electrode and the mold resin or long-term reliability.

  That is, in the conventional configuration, stress is locally applied due to the difference in thermal shrinkage between the wiring 204 and the mold resin 206 due to heating during solder mounting or the like, and as a result, the reliability is lowered. In addition, a gap is generated between the wiring 204 and the mold resin 206 due to a long-term change over time, which causes quality problems such as deterioration of electrical characteristics or strength.

  The present invention solves the above-described conventional problems. By forming a metal layer having bonding properties and corrosion resistance on one surface of an electrode forming a coil pattern, the reliability as a coil component is improved, and the size is reduced. It is an object of the present invention to provide a high-performance coil component and a manufacturing method thereof.

  In order to solve the conventional problems, the present invention provides a coil component in which an insulating resin made of a photosensitive resin and a coil portion made of a plurality of coil patterns are built in the insulating resin, One side is covered with a metal layer made of gold, silver, palladium, platinum, tin or nickel, and connected to the bottom of the via electrode through this metal layer, and the thickness of the metal layer connected to the via electrode is set to one side of the coil pattern It is set as the structure made thinner than the metal layer formed in this.

  The coil component and the manufacturing method thereof according to the present invention can improve the bondability with the insulating resin and reduce the surface oxidation of the electrode material by covering one surface of the electrode layer forming the coil pattern with the metal layer. In addition, the thickness of the metal layer connected to the via electrode is made thinner than the thickness of the metal layer provided on one surface of the coil pattern, thereby improving the connectivity of the via electrode and further improving the long-term reliability of the coil component and A manufacturing method thereof can be provided.

(Embodiment 1)
Hereinafter, a coil component and a manufacturing method thereof according to Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a coil part of a coil component according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1 for explaining the configuration of the coil part of the coil component.

  In FIG. 1 and FIG. 2, reference numeral 100 denotes a dotted line indicating the external shape of a coil component, which is a chip component. This chip coil is formed so that the coil pattern 102 is in a spiral shape inside an insulating resin obtained by curing a photosensitive resin. 2 shows the structure of a coil component formed by laminating using a plating technique and a photolithography technique.

  The via electrode 104 corresponds to an interlayer connection portion of the plurality of coil patterns 102. The coil pattern 102 formed of a plurality of layers is connected in a spiral shape or a coil shape by the via electrode 104 formed at a predetermined position. ing.

  The coil pattern 102 may have a spiral shape, a meander shape, or the like, and the coil pattern 102 may have any shape. Reference numeral 106 denotes an external electrode which is mounted as a terminal electrode, and a part of the spirally formed coil pattern 102 is connected to a plurality of external electrodes 106.

  As shown in FIG. 2, a base electrode layer 101 is formed below the coil pattern 102. The base electrode layer 101 serves as a power feeding electrode when the coil pattern 102 is formed by electroplating, and a metal such as copper, nickel, chromium, gold, silver, or palladium can be used. And when this ground electrode layer 101 and the coil pattern 102 are comprised by the same electrode material excellent in electroconductivity, such as copper, the coil components excellent in the electrical property are realizable.

  In particular, when a metal material mainly composed of nickel, titanium, or chromium is used as the base electrode layer 101, these metal materials have high bondability with resin and excellent corrosion resistance. It has the advantage of increasing the reliability of the parts. The base electrode layer 101 can be formed by an electroless plating method or a sputtering method. And as thickness of the base electrode layer 101 at this time, the range of 0.01-1 micrometer is preferable. If it is less than 0.01 μm, it becomes unstable as a feeding point, and if it exceeds 1 μm, productivity is lowered.

  Next, the coil pattern 102 can be formed on the base electrode layer 101 by electroplating using copper or the like having excellent conductivity.

  Reference numeral 110 denotes a metal layer, and the metal layer 110 is embedded in the resist layer 108 while being formed on one surface of the coil pattern 102. By forming the metal layer 110, the surface oxidation of the coil pattern 102 can be prevented, and the adhesion strength between the resist layer 108 and the coil pattern 102 can be increased.

  Further, the connectivity with the via electrode 104 can be improved by selecting the metal in consideration of the bonding property with the metal forming the via electrode 104. Furthermore, an excellent effect of improving workability during exposure (including alignment during exposure) can be obtained.

  Therefore, the electrode pattern of the coil portion that contributes to actual electrical characteristics is composed of a laminate of the base electrode layer 101, the coil pattern 102, the via electrode 104, and the metal layer 110, and these laminate patterns are the coil portion. It acts as a conductor.

  Further, when the coil pattern 102 is formed of copper, the surface of copper is often oxidized, and if the via electrode 104 is formed on the oxide film via the base electrode 101, via connection with low connection reliability is achieved. As a result, long-term reliability is lowered. On the other hand, by connecting the surface of the coil pattern 102 with a noble metal, a metal thin film that is harder to oxidize than copper, or a metal thin film that can be easily reduced even when oxidized, connection of via connection is possible. Reliability can be increased.

  Then, in particular, when a gold thin film is formed as the metal layer 110, a copper electrode is formed as the base electrode layer 101, and a copper electrode is formed in the via electrode 104, the interdiffusion is caused by heating to promote copper grain growth, It was also found that a via connection structure with improved connection reliability can be realized.

  Furthermore, by making the thickness of the metal layer 110b corresponding to the area connected to the via electrode 104 smaller than the thickness of the metal layer 110 provided on one surface of the coil pattern 102, the diffusion layer between the via electrode 104 and the metal layer 110b. By forming a thin film, connection conductivity and connection reliability of the via electrode 104 can be further increased.

  Next, reference numeral 108 denotes a resist layer made of a photosensitive resin. This resist layer 108 serves as a mask material for forming the coil pattern 102 and is finally laminated to construct the external shape of the coil component. Yes. Therefore, it is preferable that the material used for the resist layer 108 is a photosensitive material and has excellent insulation and durability. As an organic material suitable for such use, an epoxy resin, a polyimide resin, or a modified resin thereof is preferable.

  By using the coil component having the configuration described above, it is possible to prevent surface oxidation of the coil pattern 102 such as copper having excellent conductivity, to improve the connectivity of the via electrode 104, and between the electrode material and the resin material. Since the improvement in adhesion can be realized, it is possible to provide a coil component manufacturing method that can realize a coil component excellent in electrical characteristics and long-term reliability and can be manufactured in a lump.

  Furthermore, when the insulating resin is permeable, it is possible to easily distinguish the front and back of the coil component.

  Next, the manufacturing method of the coil component in this Embodiment 1 is demonstrated in detail using drawing.

  3 to 9 are cross-sectional views of steps for explaining the method of manufacturing the coil component according to the first embodiment.

  First, as shown in FIG. 3, a substrate 112 is prepared, and a resist layer 108 made of a photosensitive resin is formed on the substrate 112 in a predetermined pattern shape. The base material 112 may be a material that serves as a temporary base such as a silicon substrate, a metal substrate, or a glass substrate. Reference numeral 101 denotes a base electrode layer, which is formed on the entire surface so as to cover the surface of the base material 112 or the resist layer 108.

  As a method for forming the base electrode layer 101, a thin film forming method such as an electroless plating method or a sputtering method can be used.

  In this way, the base electrode layer 101 having excellent adhesion is formed on the surface of the substrate 112 or the resist layer 108. As a material suitable for the base electrode layer 101, a metal such as nickel, titanium, chromium, copper, gold, silver, or palladium can be used, and by utilizing the conductivity of the base electrode layer 101, It can be used as a power supply electrode for electroplating in the next step.

  Further, when a metal having a relatively low resistance value such as silver, copper, or nickel is selected for the base electrode layer 101, it can be used as a part of the conductor of the formed coil pattern 102, and the skin in a high frequency region. Low resistance due to the effect can be realized.

  Further, when a member having high migration resistance such as nickel, titanium or chromium is used, an effect of preventing metal migration can be obtained.

  The thickness of the base electrode layer 101 is preferably 0.01 to 1 μm. When the thickness is less than 0.01 μm, the resistance value of the base electrode layer 101 increases, which may be difficult to use as a power supply electrode layer for electroplating. When the thickness exceeds 1 μm, the productivity of the base electrode layer 101 is lowered, and the base electrode layer 101 may be peeled off from the surface of the base material 112 or the resist layer 108 due to the internal stress.

  Next, as shown in FIG. 4, an electrode layer 116 made of copper or the like was formed on the base electrode layer 101 by electroplating. Here, by using the conductivity of the base electrode layer 101, an electrode layer 116 such as copper having excellent conductivity can be formed at low cost and at high speed using a technique such as electroplating. Note that as the electrode material of the electrode layer 116, silver having excellent conductivity can be used.

  Further, the electrode layer 116 can be formed using an electroless plating method or a sputtering method without forming the base electrode layer 101.

  Thereafter, as shown in FIG. 5, the excess electrode layer 116 and the base electrode layer 101 protruding from the height of the resist layer 108 are removed by a mechanical polishing method such as cutting or grinding or a CMP polishing method (chemical polishing). By removing with high accuracy, the electrode layer 116 is patterned into the coil pattern 102 and embedded in the resist layer 108. For example, the height of the resist layer 108 shown in FIG. 5 may be polished to be thinner than the height of the resist layer 108 in FIG. Thereby, dimensional accuracy can be increased.

  At this time, the surface of the polished base metal material such as copper may be left in the heat generated during polishing or in the atmosphere to form a surface oxide film. This surface oxide film causes a decrease in the adhesion between the insulating resin constituting the resist layer 108 and the coil pattern 102, and reduces the conductivity of the coil pattern 102 as the thickness of the oxide film increases. Therefore, management of the oxidation state of the surface is important.

  Next, a metal layer 110 is formed on the coil pattern 102 as shown in FIG. As the metal layer 110, it is preferable to use a member that selectively chemically reacts with a metal material constituting the coil pattern 102 as described later. This selective chemical reaction method includes a plating method, and particularly has an advantage that patterning is unnecessary if it is a displacement plating method and an electroless plating method. This displacement plating method is a method of forming a metal film on the surface of an object by a displacement reaction, and the electroless plating method is a chemical reaction.

  In addition, although patterning is required, it can be formed using a thin film method.

  In general, copper is optimally used as the metal material used for the coil pattern 102 from the viewpoint of productivity and conductivity, and the performance of the coil component can be enhanced. When copper is used for the coil pattern 102, the metal constituting the metal layer 110 is preferably composed mainly of any one of gold, silver, palladium, platinum, tin, and nickel. As a method for forming the metal layer 110, it is optimal to use a plating method such as a displacement plating method or an electroless plating method. In the case of the displacement plating method, for example, when the substrate 112 on which the coil pattern 102 is formed is immersed in various displacement plating baths in which gold, silver, or platinum is present as an ion or a complex, the exposed surface of the coil pattern 102 is, for example, copper. The metal layer 110 can be formed by substituting a material having a base electrode potential that is lower than the material of the coil pattern 102 formed.

  In the case of electroless plating, a catalyst such as gold, silver, palladium, platinum, tin or nickel can be deposited by selectively applying a catalyst to the exposed surface of the coil pattern 102 as a pretreatment. The metal layer 110 can be formed while utilizing the above.

  By these chemical reactions, the surface oxide film of the coil pattern 102 is removed, and by using the new metal layer 110 as its surface, it becomes possible to prevent the surface oxidation of copper, and the coil having excellent conductivity and adhesion. It is possible to provide a method of manufacturing a coil component that can realize the component and has excellent long-term reliability. Here, if the metal layer 110 exceeds 1 μm, the proportion of the metal layer 110 in the coil portion increases, which may deteriorate the electrical performance of the coil component. Moreover, if it is less than 0.01 micrometer, many pinholes etc. will exist and a bondability will improve, but the improvement of corrosion resistance becomes small. Therefore, the thickness of the metal layer 110 is desirably 0.01 to 1 μm.

  Note that when any one of gold, silver, palladium, platinum, tin, or nickel is used for the metal layer 110 and the surface roughness of the metal material is increased, the resist layer 108 formed over the metal layer 110 Adhesion can be further increased. And as the roughened state, a fine bowl shape of 0.01-1 micrometer or less is desirable. By closely gathering the fine protrusions, the adhesion with the resist layer 108 is further enhanced.

  Thus, by covering the surface of the coil pattern 102 with the base electrode layer 101 and the metal layer 110, the adhesion with the resist layer 108 is improved, and long-term reliability such as mechanical strength or electrical characteristics, etc. Can also be improved.

  Further, the metal layer 110 may be formed on the coil pattern 102 of all layers or only on the necessary coil pattern 102. In addition, when the resist layer 108 having light transmittance is used, the metal layer 110 is also formed on the surface of the coil pattern 102 which is the uppermost layer, so that it is easy to distinguish the upper and lower (or front and back) of the product. Have

  Next, as shown in FIG. 7, a new resist layer 108 is formed, and an opening 128 is formed by using a photolithography technique and an etching technique. At this time, the metal layer 110 exposed to the opening 128 together with the resist layer 108 is partially removed using an etching method or the like so as to be thinner than the thickness of the metal layer 110 provided on one surface of the coil pattern 102. The metal layer 110b is formed. By removing the surface layer by this etching, the oxide film can be removed, thereby improving the connectivity with the base electrode layer 101 and its reliability, and reducing the thickness of the metal layer 110, A decrease in the conductor resistance of the coil portion can be suppressed. As a method for removing the surface of the metal layer 110, for example, the surface of the metal layer 110 can be efficiently removed by reverse sputtering with argon gas or the like in a vacuum. It is preferable to use a metal whose main component is a metal made of gold, silver, palladium, platinum, tin or nickel. It has been found that a highly reliable connection structure can be realized by forming the base electrode layer 101 through these metal layers 110b.

  Furthermore, as shown in FIG. 8, the base electrode layer 101 can be formed on the surface of the resist layer 108 and the exposed surface of the opening 128 of the metal layer 110 by repeating the process of FIG.

  In this way, by forming the base electrode layer 101 also on the inner wall surface of the opening 128, the adhesion between the resist layer 108 forming the opening 128 and the via electrode 104 can be improved. Needless to say, the adhesion strength between the resist layer 108 and the base electrode layer 101 can be increased by selecting a thin film method such as sputtering as a method for forming the base electrode layer 101.

  Further, when the coil pattern 102 is formed by multilayering, the electrode layer 116 protected by the base electrode layer 101 firmly bonded to the resist layer 108 can be formed on the coil pattern 102. Then, by forming the metal layer 110 on the upper surface of the electrode layer 116, the electrode layer 116 is firmly bonded to the resist layer 108.

  Thereafter, by repeating the steps of FIGS. 4 to 6, the via electrode 104 is formed by filling the electrode layer 116 in the opening 128 formed in the resist layer 108 as shown in FIG. 9. The coil pattern 102 and the metal layer 110 can be formed.

  At this time, when the base electrode layer 101 and the via electrode 104 are all made of copper and the metal layer 110b is formed of a material such as gold, via connection formation with excellent conductivity and excellent connection reliability is realized. This is an effective configuration when a small via diameter is required.

  A coil component having a desired inductance value can be produced by repeating these steps up to a predetermined number of times. As an example, the coil component shown in FIG. 1 is a chip coil of 0603 size, the coil part is a 6.5-turn chip coil, and an inductor: 4 to 5 nH, Q; We were able to. It was confirmed that there was little change in DC resistance (RDc) with time in the reliability test of the high temperature and high humidity test (65 ° C., 95%) for this chip coil.

  According to the present invention, various types of electronic devices can be used as highly reliable small-sized coil components with improved adhesion and reliability of via electrodes, and excellent adhesion between the electrode layer forming the laminated coil pattern and the insulating resin. Useful for equipment.

The perspective view of the coil components in Embodiment 1 of this invention Sectional view Sectional drawing for demonstrating the manufacturing method of the coil component Sectional view Sectional view Sectional view Sectional view Sectional view Sectional view A perspective view showing the structure of a conventional coil component

Explanation of symbols

100 dotted line 101 ground electrode layer 102 coil pattern 104 via electrode 106 external electrode 108 resist layer 110 metal layer 110b metal layer 116 electrode layer 112 base material 128 opening

Claims (8)

A coil component including an insulating resin made of a photosensitive resin and a coil portion made of a plurality of coil patterns in the insulating resin, wherein one surface of the coil pattern is made of gold, silver, palladium, platinum, tin or nickel A coil component that is coated with a metal layer and is connected to the bottom of the via electrode through the metal layer, and the thickness of the metal layer connected to the via electrode is thinner than the metal layer formed on one surface of the coil pattern. The coil component according to claim 1, wherein the coil pattern and the via electrode are copper. The coil component according to claim 1, wherein the thickness of the metal layer provided on one surface of the coil pattern is 0.01 to 1 μm. The coil component according to claim 1, wherein a base electrode layer is provided on the other side of the coil pattern on which the metal layer is not formed. The coil component according to claim 4, wherein the base electrode layer is mainly composed of nickel, titanium, or chromium. The coil component according to claim 5, wherein the thickness of the base electrode layer is 0.01 to 1 μm. Forming a groove for forming a coil pattern on one surface of the photosensitive resin, forming a base electrode layer on a bottom surface of the formed groove, and forming an electrode layer on an upper surface of the base electrode layer; After forming the coil pattern by removing unnecessary portions of the electrode layer, forming a metal layer on one surface of the coil pattern, and changing the thickness of the metal layer where the metal layer is connected to the via electrode to another metal A method of manufacturing a coil component, comprising: a step of making the layer thinner than a thickness of the layer; and a step of connecting a via electrode having a base electrode layer formed on the exposed surface of the metal layer and laminating a coil pattern. The method for manufacturing a coil component according to claim 7, wherein a plating method is used as a method of forming the metal layer.

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