JP2009182188A - Chip coil and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip coil having an improved humidity resistance and a high space factor, and a method for manufacturing the same. <P>SOLUTION: The chip coil is composed of an element body made of a cured resin material having a water absorption of 0.8% or less, a coil pattern having a via connection arranged in the element body, and electrodes provided on the surface of the element body. Thereby, the chip coil having an excellent humidity resistance can be obtained while a high space factor of the coil pattern is assured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inductance component used in a small electronic device such as a mobile phone.

The role of electronic components is important for realizing high functionality and miniaturization of electronic devices, and one of these electronic components is an inductance component. In order to realize the downsizing of the inductance component, the element body is composed only of a photosensitive resin, a fine pattern is formed using a photolithography process, the conductor is formed by electrolytic plating, and the conductor is composed of copper. A chip coil has been proposed (see, for example, Patent Document 1).
JP 2003-203813 A

  However, in the conventional configuration, in order to form a coil pattern having a high space factor on the plane around which the spiral coil is wound, the photosensitive resin forming the element body has a resolution, that is, a photolithography process. It is composed of a resin material with excellent fine pattern formation performance that can achieve a high aspect ratio with high accuracy by fine etching, and in this way, in the moisture resistance reliability test, photosensitive resin There is a problem that electrical characteristics such as L value and Q value fluctuate due to hygroscopic expansion.

  An object of the present invention is to solve the above-mentioned conventional problems, and to provide a chip coil having a high space factor coil pattern excellent in moisture resistance reliability and a method for manufacturing the chip coil.

  In order to solve the conventional problems, the present invention provides an element body made of a cured photosensitive resin, a coil pattern made of copper having via electrodes formed inside the element body, and a surface of the element body. The coil is composed of electrodes arranged in the above structure, and the water absorption rate of the cured product of the photosensitive resin is 0.8% or less, and the thickness of the exterior part made of the photosensitive resin of the coil pattern is 20 μm or more. Is.

  The chip coil and the manufacturing method thereof according to the present invention include an element body made of a cured product of a photosensitive resin having a water absorption rate of 0.8% or less, and a plurality of coil patterns having via connections formed inside the element body. With the configuration having the electrodes arranged on the surface of the element body, a highly reliable chip coil can be realized while ensuring a high space factor of the coil pattern.

(Embodiment 1)
Hereinafter, the chip coil and the manufacturing method thereof according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a chip coil according to Embodiment 1 of the present invention.

  In FIG. 1, an element body 1 made of an insulating resin having photosensitivity is formed as a laminated structure in order to form a coil pattern 2. In the coil pattern 2, a spiral planar coil 2 a formed in a predetermined layer and a spiral planar coil 2 b formed in another layer are connected via a via electrode 3. The terminal coil 5 is connected to the planar coil 2a and the planar coil 2b via the extraction electrode 4, thereby forming a chip coil having a chip shape.

  More specifically, the planar coil 2b provided inside a predetermined layer of the element body 1 is spirally wound from one terminal electrode 5 in the inner circumferential direction, and is separated from the innermost circumferential portion of the planar coil 2b. The innermost peripheral part of the planar coil 2 a provided in the layer is connected by a via electrode 3, and the planar coil 2 a is spirally wound in the outer circumferential direction toward the other terminal electrode 5 to constitute a chip coil. In FIG. 1, the two-layer planar coils 2a and 2b are described as an example. However, in order to achieve a desired inductance value, a predetermined number of layers can be determined by designing a predetermined number of layers by simulation in advance. Thus, the planar coils 2a and 2b can be combined.

  Moreover, in order to make a chip coil of a small size such as 1005 size or 0603 size among chip components, it is necessary to increase the number of spirals per layer. On the other hand, if the pattern width of the planar coils 2a and 2b is reduced, the direct current resistance is increased and the electrical characteristics of the chip coil are deteriorated. In consideration of these, it is important to form the planar coils 2a and 2b having a high aspect ratio by reducing the pattern width and increasing the pattern thickness. In order to realize this, for example, it is preferable to form the planar coils 2a and 2b having an inter-pattern distance of 20 μm or less, an aspect ratio of 1.5 or more, and a pattern width of 10 to 30 μm. Further, the height of one via electrode 3 is preferably 5 μm or more and 100 μm or less in order to realize a coil pattern with a high space factor. In particular, when the thickness is less than 5 μm, the insulation is lowered, and when the thickness exceeds 100 μm, the stress increases at the interface between the via electrode 3 and the coil pattern 2 and the probability of occurrence of a defect such as disconnection increases.

  The insulating resin used for the element body 1 is preferably an epoxy resin having a photosensitivity or a polyimide resin. In particular, when the coil pattern 2 having high resolution is formed, an acrylic modified epoxy resin is preferable.

  As a chip coil having such a configuration, a coil pattern 2 having a chip size of 0603 and an L value of 1.8 nH at that time was manufactured, and a chip coil having resins having different water absorption rates was manufactured as a prototype. The water absorption was determined from the weight change around 85 ° C. and 85% RH-120 hours. Further, the element body 1 which is an exterior part covering the coil pattern 2 was formed to have a thickness of about 20 μm.

  The moisture resistance reliability of the chip coil produced as described above was evaluated. The test contents include a high temperature and high humidity load test (temperature: 60 ° C., humidity: 95%, load condition: 0.5 A as a rated current, continuous application, test time: 1000 hours), and high temperature and high humidity test (temperature). 60 ° C., humidity: 95%, no load, test time: 1000 hours), and the results are shown in Table 1. As the determination conditions, it is possible to determine that the change rate of L: within ± 5% and the change rate of Q: within ± 20% are satisfactory from the viewpoint of practicality.

  From the results of (Table 1), it was found that the water absorption is preferably in the range of 0.8% or less. By using the chip coil having such a configuration, high space factor of the coil pattern of the planar coils 2a and 2b can be ensured, and at the same time, the moisture resistance of the entire chip coil can be improved. This is different from the chip coil of the conventional ceramic body, in the present invention, since the body 1 is a resin cured material having photosensitivity, and the entire coil portion has an exterior structure made of the resin cured material. In addition, it is considered that stress is easily applied to the coil portion due to hygroscopic expansion of the cured resin constituting the element body 1, and the characteristic value changes. Therefore, by using a cured product of a photosensitive resin having a water absorption rate of 0.8% or less as the element body 1 in this study, the electrode material having excellent conductivity such as copper is used and the productivity such as the plating method is excellent. It has been found that the chip coil of the structure having the coil pattern 2 formed of the fine pattern can be improved in moisture resistance, and a chip coil capable of reducing stress concentration on the coil pattern 2 due to hygroscopic expansion can be realized.

  Moreover, it can be set as the chip coil which can satisfy moisture resistance by the thickness of the element | base_body which coat | covers the coil pattern 2 being 20 micrometers or more. While it is possible to design the thickness of the element body 1 in consideration of the space factor, it is necessary to increase the thickness of the element body 1 of the exterior portion when it is not necessary to increase the number of layers of the coil pattern 2. The reliability can be further increased.

  As another specific configuration, the main component of the inner layer portion of the element body 1 is an epoxy resin, and an insulating material for the element body 1 used on the upper surface side and the lower surface side of the chip coil is an epoxy resin. By adopting a configuration in which a different kind of material such as an inorganic filler is mixed in the chip coil, it is possible to obtain a chip coil having further excellent moisture resistance and mechanical strength. The upper surface side and the lower surface side are layers on which the coil pattern 2 is not formed, and pattern formation by high-precision photolithography is unnecessary, and thus such a configuration can be obtained.

The inorganic filler used _{therein, Al 2 O 3, SiO 2} , TiO 2, metal oxides such as ZrO ₂ or MgO is preferable.

  Moreover, it is preferable to use an insulating resin having a volume resistance of 10 GΩcm or more of the photosensitive insulating resin constituting the element body 1. By using a photosensitive insulating resin having a volume resistance of 10 GΩcm or more, a chip coil with little characteristic deterioration can be obtained even at high frequencies.

  The cross-section of the planar coils 2a and 2b is not limited to a square shape, but may be an annular shape or the like. However, the square shape can increase the cross-sectional area of the coil, resulting in a reduction in copper loss. can do.

  It is more desirable that the planar coils 2a and 2b have a thickness of 10 μm or more because a large current can be handled.

  Next, the manufacturing method of this chip coil is demonstrated using drawing. 2 to 10 are cross-sectional views for explaining the manufacturing process of the chip coil according to the first embodiment.

  In this chip coil manufacturing method, a plurality of chip coils are formed at a time in a state of being connected to each other on a single wafer substrate such as silicon, and finally a plurality of chip coils are separated and manufactured into individual pieces. Is the method.

  First, as shown in FIG. 2, for example, an aluminum thin film having a thickness of 80 to 100 nm is formed on a substrate 8 made of a silicon wafer having a thickness of 0.2 to 1.0 mm by a plating method, a sputtering method, a vapor deposition method, or the like. 9 is formed. At this time, it is preferable to use either silicon, glass or quartz as the substrate 8. These materials are preferable from the viewpoints of flatness, surface roughness and material availability. In particular, silicon wafers are the optimal material for this purpose.

  The sacrificial layer 9 is preferably a metal material having excellent etching properties, and aluminum is particularly preferable. This is particularly preferable from the viewpoints of adhesion to the substrate 8 and etching properties.

  Next, a photosensitive epoxy resin or the like is formed on the sacrificial layer 9 by using a coating machine such as a spin coater, and then a frame-shaped gap portion 11 is formed by a photolithography method.

  Next, as shown in FIG. 3, the metal layer 12 is formed using a plating method or the like. The metal layer 12 is formed to be thicker than a predetermined thickness, and then flattened by controlling to a predetermined thickness using CMP polishing or the like to at least the upper surface of the insulating resin layer 10 as shown in FIG. A frame-like post portion 13 made of a thin metal material having excellent dimensional accuracy can be formed. A method of manufacturing a chip coil having excellent lamination accuracy and dimensional accuracy by forming a metal layer 12 thicker than a predetermined thickness and then laminating at least the upper surface of the insulating resin layer 10 by polishing. Can be realized.

  Further, the metal layer 12 is formed by an electrolytic plating method, and by using such a method, chip coils having a fine coil pattern 2 can be efficiently produced collectively. Thus, by using the coil pattern 2 as a plating electrode by a plating method, it is possible to obtain a chip coil that is excellent in productivity, can reduce the circuit resistance value of the conductor, and can realize excellent high-frequency characteristics, particularly Q value. be able to.

  Further, when the metal layer 12 is formed by a plating method, it is preferable to use copper from the viewpoint of electrical characteristics and productivity.

  In addition, as a material which forms the coil pattern 2, it is also possible to use silver excellent in conductivity.

  And when using copper as the coil pattern 2, it can be set as the chip coil more excellent in moisture resistance by coat | covering the surface of the coil pattern 2 with the metal excellent in corrosion resistance, such as titanium or chromium. . Therefore, before forming copper by plating, titanium or chromium is formed on the inner wall surface of the gap 11 by sputtering, and after forming copper by plating, the surface layer of copper is again applied to the above method. Then, the surface of the coil pattern 2 can be coated by coating a metal such as titanium or chromium. Thereby, the coil pattern 2 excellent in moisture resistance can be produced.

  Then, after forming the insulating resin layer 10 having the gap portion 11 by using a photolithography method on the insulating resin layer 10 having a predetermined pattern as shown in FIG. 5, the inside of the gap portion 11 is plated. Using a method and CMP polishing, a metal material having excellent conductivity, such as copper, is laminated while forming a predetermined pattern of predetermined spiral planar coils 2a and 2b and a frame-like post portion 13 with high accuracy. By repeating the above, a laminated body in which the coil pattern 2 including the planar coils 2a and 2b is formed inside the frame-shaped post portion 13 can be manufactured.

  The coil pattern 2 has a two-layer laminated structure composed of a planar coil 2a and a planar coil 2b. The coil pattern 2 is determined by an inductance value. The value can be designed.

  Further, the gap portion 11 includes a plurality of frame-like gap portions 11a for forming the frame-like post portion 13, a spiral void portion 11b disposed inside the frame-like gap portion 11a, and a via electrode. This frame-shaped gap 11a functions as a frame-shaped post 13 for separating into individual chip-shaped components in the latter half of the manufacturing process. Thus, they are laminated.

  In addition, the coil pattern 2 including the planar coils 2a and 2b is formed in the spiral gap 11b, the via electrode 14 made of metal is formed in the through hole gap 11c, and the coil pattern 2 and the frame shape are formed. Insulation with the post portion 13 is intended.

  When the two-layer planar coils 2 a and 2 b are formed, the two-layer planar coils 2 a and 2 b are made conductive by the via electrode 14.

  The width of the post portion 13 is preferably 100 μm or less (not including 0).

  Next, an etching process for dividing the element body 1 that has completed the stacking process for forming the chip coil is entered. Therefore, as shown in FIG. 6, a resist pattern 15 for protecting from the etching process is formed by photolithography.

  Thereafter, as shown in FIG. 7, the frame-shaped post portion 13 is removed by melting with an etching agent, and the sacrificial layer 9 formed on the substrate 8 so as to enter from the gap portion 11a formed by etching is removed. It can be separated into individual pieces by removing.

  Next, after removing the resist pattern 15 as shown in FIG. 8, a nickel plated electrode and a Sn plated electrode are laminated and coated on the surfaces of both end faces of the element body 1 so as to be electrically connected to the exposed electrode 14. Thus, the terminal electrode 5 having excellent mountability as shown in FIG. 9 is formed. The terminal electrode 5 has a five-surface electrode structure, but the configuration of the terminal electrode 5 can be changed as necessary.

  The shape of the chip coil produced by this manufacturing method was as follows: length: 1.00 mm × width: 0.50 mm × thickness: 0.30 mm (1005 size), and a chip coil having an inductance value of 8.4 nH could be produced.

  As described above, it is composed of a base body 1 made of a cured resin, a coil pattern 2 having a via connection formed inside the base body 1, and a terminal electrode 4 disposed on the surface of the base body 1. In the chip coil in which the water absorption rate of the cured resin is 0.8% or less, the element body 1 and the coil pattern 2 formed of an insulating resin having at least photosensitivity are laminated a plurality of times by the photolithography method, and the coil pattern 2 Is formed at the inner layer portion of the element body 1 that is an insulating resin, the step of forming the coil pattern with plated copper and the step of dividing the coil pattern into individual pieces by etching, thereby efficiently reducing the moisture resistance and the coil pattern. It is possible to provide a method for manufacturing a chip coil having excellent high space factor.

  Since the chip coil and the manufacturing method thereof according to the present invention have high moisture resistance, they are useful in various electric devices such as mobile phones.

Sectional drawing of the chip coil in Embodiment 1 of this invention Sectional drawing which shows the manufacturing process of the same chip coil Sectional view Sectional view Sectional view Sectional view Sectional view Sectional view Sectional view

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Element body 2 Coil pattern 2a, 2b Planar coil 3 Via electrode 4 Lead electrode 5 Terminal electrode 8 Substrate 9 Sacrificial layer 10 Insulating resin layer 11, 11a, 11b, 11c Air gap part 12 Metal layer 13 Post part 14 Via electrode 15 Resist pattern

Claims (6)

A chip coil comprising an element body made of a cured product of a photosensitive resin, a coil pattern made of copper having a via electrode formed inside the element body, and an electrode disposed on the surface of the element body. A chip coil in which the water absorption rate of a cured resin is 0.8% or less, and the thickness of an element covering the coil pattern is 20 μm or more. The chip coil according to claim 1, wherein a cured product of a photosensitive resin containing an inorganic filler is used for an exterior portion of the element body. The chip coil according to claim 1, wherein the coil pattern and the via electrode are plated films. The chip coil according to claim 1, wherein the coil layer and the surface layer of the via electrode are coated with titanium or chromium. The chip coil according to claim 1, wherein the via electrode has a height of 5 to 100 μm. A chip coil comprising an element body made of a cured product of a photosensitive resin, a coil pattern made of copper having a via electrode formed inside the element body, and an electrode disposed on the surface of the element body. A method of manufacturing a chip coil in which the water absorption of the cured resin is 0.8% or less, and the thickness of the exterior part made of the photosensitive resin of the coil pattern is 20 μm or more,
Forming an insulating resin having photosensitivity by a photolithography method;
Forming a coil pattern on the inner layer portion of the insulating resin by a plating method;
A step of laminating using the photolithography method and the plating method while connecting the coil pattern by via electrodes by laminating the steps;
A manufacturing method of a chip coil including at least a step of dividing into individual pieces.

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