JP6493778B2 - Laminated component and manufacturing method thereof - Google Patents

Description

  The present invention relates to a laminated component in which a coil is formed in a laminated body in which metallic soft magnetic materials are laminated.

  Conventionally, coil parts such as inductors, transformers, and chokes have been used in a wide variety of applications such as home appliances, industrial equipment, and vehicles. The coil component includes a magnetic core and a coil provided on the magnetic core. For such a magnetic core, ferrite having excellent magnetic properties, flexibility in shape, and cost is widely used.

  In recent years, as power supply devices such as electronic devices have been downsized, the demand for coil parts that are small and low in profile and can be used for large currents has become stronger, and the saturation magnetic flux density is higher than that of ferrite. A laminated coil component (hereinafter referred to as a laminated component) using metal soft magnetic powder has been proposed. As the metal soft magnetic powder, for example, soft magnetic powder such as Fe, Fe—Si—Al, Fe—Si—Cr, or Fe—Ni alloy is used.

  In the laminated component of Patent Document 1, such a metal soft magnetic powder is blended and kneaded with borosilicate glass, a resin binder, and a solvent to obtain a magnetic layer layer paste. Furthermore, using Ag powder as the conductor powder, blended and kneaded with a resin binder and a solvent to obtain a conductor layer paste, the magnetic layer layer paste and the conductor layer paste were alternately and repeatedly printed. And laminate. The obtained laminated body is heat-treated at 750 ° C. in the atmosphere to fix the metal soft magnetic powder with a glass component, and to form a laminated part including a coil made of a conductor layer. In Patent Document 2, a magnetic material layer paste is used as a sheet, and a plurality of conductor layer pastes each having a coil pattern formed thereon are laminated, and are pressed to form a laminated body. It is heat-treated at a temperature of 400 ° C. or higher in a non-oxidizing atmosphere. In the obtained laminated component, the metal soft magnetic powder is fixed by a glass component in the same manner as in Patent Document 1. Further, by performing the heat treatment in a non-oxidizing atmosphere, a decrease in the magnetic permeability after the heat treatment is prevented. However, in Patent Document 2, there is no description as to why the effects of heat treatment in a non-oxidizing atmosphere are brought about.

JP-A-9-148118 JP 2007-27354 A

  The metal soft magnetic powder has a high saturation magnetic flux density, but is easily rusted and has a low electrical resistivity. Therefore, in the laminated parts of Patent Documents 1 and 2, the soft magnetic powder particles are covered with a glass component to prevent rust and insulation. However, since the glass component between the metal soft magnetic powders is non-magnetic, it also acts as a magnetic gap and reduces the magnetic permeability, so it is not easy to increase the inductance of the laminated component. Furthermore, the strength of the laminated part is affected by the strength of the glass component between the metal soft magnetic powders, and may be inferior in strength compared to the laminated part using ferrite. In addition, a lot of glass is required to reliably coat the metal soft magnetic powder, and a process of mixing borosilicate glass and the metal soft magnetic powder is required. There is also room for improvement.

  An object of the present invention is to provide a multilayer component that can be obtained by a simple manufacturing method and that can easily obtain a high inductance and a large inductance.

According to a first aspect of the present invention, a coil composed of a coil pattern formed of a paste containing Ag powder is encapsulated in a magnetic material in which Fe-based soft magnetic powder is bonded through an oxide phase in which Al is segregated, and the Fe Soft magnetic powder is a Fe—Al—Cr alloy grain having a median diameter d50 in a cumulative particle size distribution of 20 μm or less that passes through a sieve having a mesh size of 32 μm, and the Fe—Al—Cr alloy grain is Al 2.0 mass% or more and 10.0 mass% or less, Cr is contained 1.0 mass% or more and 9.0 mass% or less, inevitable impurities and other elements are contained in 1.0 mass% or less, and the balance Is Fe and contains more Al than Cr, and the oxide phase is formed by oxidation of the Fe-Al-Cr alloy grains,
The magnetic body is configured by stacking a plurality of magnetic layers, and the coil pattern is stacked through the magnetic layers and connected in the stacking direction .

In the first invention, it is preferable that the paste further contains one or more metals selected from the group consisting of Pd, Ir, Pt, Ru, Rh, Ti, and Co as a shrinkage rate control material .

In the first invention, the paste preferably contains one or more metals selected from Pt, Ru or Rh .

In 1st invention, it has a terminal electrode connected to the said coil on the surface of the said multilayer component covered with the said oxide phase, and glass exists between the surface of the said multilayer component and the said terminal electrode . Is preferred.

In 1st invention, it is preferable to mount an electronic component in the said laminated component and to connect with the said terminal electrode.

According to a second aspect of the present invention, there is provided a step of forming a formed body in which a magnetic layer and a coil pattern are laminated, and the formed body is heat treated at a temperature of 700 to 800 ° C. in an atmosphere in which oxygen is present or in an atmosphere in which water vapor is present. And the manufacturing method of the laminated component characterized by including the process of forming the oxide phase which Al segregated which couple | bonds Fe-type soft-magnetic powder .

  In the laminated component, Fe—Al—Cr alloy particles are used as the Fe-based soft magnetic powder, and an oxide phase formed from the Fe—Al—Cr alloy particles is interposed between the Fe-based soft magnetic powders. Can demonstrate its sexuality. Moreover, the Fe-based soft magnetic powders can be firmly bonded to each other by the oxide phase, and the strength of the laminated component can be increased. Further, since the oxide phase is thin, the density can be increased. As a result, the non-magnetic region in the obtained multilayer component can be reduced to improve the magnetic permeability, and thus the inductance.

  In this manufacturing method, an oxide phase containing Al can be formed between Fe-based soft magnetic powders simply by heat-treating the resulting molded body, and the productivity of laminated parts can be improved. In addition, the formation of a specific oxide phase can efficiently increase the insulation and strength of the laminated component.

It is a perspective view of the lamination component concerning one embodiment of the present invention. It is sectional drawing of the laminated component which concerns on one Embodiment of this invention. It is a disassembled perspective view of the laminated component which concerns on one Embodiment of this invention. It is a perspective view of the laminated component which concerns on other embodiment of this invention. It is sectional drawing of the laminated component which concerns on other embodiment of this invention. It is an equivalent circuit schematic of the laminated component which concerns on other embodiment of this invention. It is a SEM observation figure of the lamination components in an example.

  Hereinafter, a laminated part and a manufacturing method thereof according to an embodiment of the present invention will be specifically described. However, the present invention is not limited to this. Note that in some or all of the drawings, portions that are not necessary for the description are omitted, and there are portions that are illustrated in an enlarged or reduced manner for ease of description.

  FIG. 1 shows the appearance of a multilayer component according to an embodiment of the present invention, FIG. 2 shows a cross section of the multilayer component in FIG. 1, and FIG. 3 shows each layer constituting the multilayer component in FIG.

  The laminated component is composed of 11 layers (S1 to S11), and includes a coil forming region 1 having coil forming layers 1a to 1d made of a magnetic layer 2 on which a coil pattern 3 (3a to 3c) is formed, and a coil forming region 1 And a magnetic body region 5 composed of a magnetic body layer 2 that does not have a coil pattern. In the coil forming area 1, the coil patterns 3 (3a to 3d) of 0.5 to 1 turn are connected through the through holes 6 to form a coil of 6.5 turns. Both ends of the coil are drawn out to the opposite side surfaces of the laminated component, and are connected to terminal electrodes 200a and 200b onto which a conductor layer paste such as Ag is baked.

  The magnetic layer 2 is obtained by kneading an Fe-based soft magnetic powder containing Fe—Al—Cr alloy particles, an organic binder mainly composed of polyvinyl butyral, and a solvent such as ethanol, toluene, xylene in a ball mill. After the viscosity of the prepared slurry is adjusted, it is applied and dried on a carrier film such as a polyester film by a doctor blade method or the like to form a sheet. Fe-based soft magnetic powder is composed only of Fe-Al-Cr alloy particles, and contains other Fe-based soft magnetic particles such as Fe-Si-Al alloy particles and Fe-Si-Cr alloy particles. Also good.

  The form of the Fe-based soft magnetic powder is not particularly limited, but it is preferable to use granular powder represented by atomized powder from the viewpoint of fluidity and the like.

  The composition of the Fe—Al—Cr alloy grains containing Fe, Cr and Al as the three main elements having a high content ratio is not particularly limited as long as it can constitute the magnetic layer. Al and Cr are elements that improve corrosion resistance and the like. In addition, Al contributes particularly to the formation of surface oxides. From this viewpoint, the content of Al in the Fe—Al—Cr alloy grains is preferably 2.0% by mass or more, and more preferably 3.0% by mass or more. On the other hand, since the saturation magnetic flux density decreases when the Al content is excessive, the Al content is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 7.0% by mass or less. It is. Cr is an element that improves the corrosion resistance as described above. From this viewpoint, the content of Cr in the Fe—Al—Cr alloy grains is preferably 1.0% by mass or more, more preferably 2.5% by mass or more. On the other hand, if the amount of Cr is excessive, the saturation magnetic flux density is lowered and the alloy grains are hardened. Therefore, the Cr content is preferably 9.0% by mass or less, more preferably 7.0% by mass or less.

  From the viewpoint of corrosion resistance and the like, the total content of Cr and Al is preferably 6.0% by mass or more. In addition, since Al is significantly concentrated in the surface oxide layer as compared with Cr, it is more preferable to use Fe—Al—Cr alloy grains having a higher Al content than Cr.

  The balance other than Cr and Al is mainly composed of Fe, but may contain other elements as long as the Fe-Al-Cr alloy grains have advantages such as formability. However, since the nonmagnetic element lowers the saturation magnetic flux density and the like, the content of such other elements is preferably 1.0% by mass or less. In addition, since Si used in an Fe—Si alloy or the like is an element that is disadvantageous for improving the strength of the laminated part, in this embodiment, it is unavoidable to enter through a normal manufacturing process of Fe—Al—Cr alloy particles. It may be contained at an impurity level (preferably 0.5% by mass or less). The Fe—Al—Cr alloy grains are more preferably composed of Fe, Cr and Al except for inevitable impurities.

  The average particle diameter of the Fe-based soft magnetic powder (here, the median diameter d50 in the cumulative particle size distribution is used) is not particularly limited, but by reducing the average particle diameter, the strength, core loss, and high frequency characteristics of the laminated parts are reduced. Therefore, for example, in applications where high frequency characteristics are required, an Fe-based soft magnetic powder having an average particle size of 20 μm or less can be suitably used. The median diameter d50 is more preferably 18 μm or less, and still more preferably 16 μm or less. On the other hand, when the average particle size is small, the magnetic permeability is low, so the median diameter d50 is more preferably 5 μm or more. It is more preferable to remove coarse particles from the Fe-based soft magnetic powder using a sieve or the like. In this case, it is preferable to use Fe-based soft magnetic powder that is at least under 32 μm (that is, has passed through a sieve having an opening of 32 μm).

  The coil forming layer 1 is further formed by opening connection through holes in the obtained sheet, printing the coil patterns 3a to 3d with the conductor layer paste, and filling the through holes 6 with the conductor layer paste. Is done. Although not shown, a plurality of coil patterns are usually formed on one surface of the sheet.

  The conductor layer paste includes metal particles, an organic vehicle, and a solvent, and may further include glass powder. It is preferable to use Ag, Cu, an Ag alloy, a Cu alloy or the like as the metal particles. In addition to printing, the coil pattern can be transferred. One or more metals selected from the group consisting of Pd, Ir, Pt, Ru, Rh, Ti, and Co may be added to the conductor layer paste as a shrinkage rate control material. Some of these metals, for example, Pt, Ru, or Rh, function as a catalyst for promoting the oxidation of Fe—Al—Cr alloy grains, and are formed at the interface between the coil pattern and the magnetic layer by a heat treatment described later. The oxide phase formed from the Al—Cr alloy grains can be formed stably, and the insulation between the coil pattern and the magnetic layer can be improved.

  In addition, you may print or apply | coat a magnetic body paste to the area | region except a coil pattern so that it may become substantially the same height as the upper surface of a coil pattern. The magnetic paste preferably contains the same Fe-based soft magnetic powder as the sheet. However, the particle size, the types of subcomponents, the amount added, etc. may be different. The magnetic paste is prepared by blending a Fe soft magnetic powder, a binder such as ethyl cellulose, and a solvent. According to such a configuration, even when the coil pattern is thick, it is possible to reduce the occurrence of stacking misalignment during delamination and delamination after debonding.

  The magnetic body layer 2 (the magnetic body region 5 and the plurality of coil forming layers 1a to 1d) is laminated and thermocompression-bonded to form a molded body so that the coil patterns 3a to 3d are connected through the through holes 6 to form a coil.

  Next, the heat treatment process of the molded body will be described. In order to relieve the stress strain introduced into the Fe-based soft magnetic powder by molding or the like and obtain good magnetic properties, the molded body is subjected to heat treatment. Such heat treatment further forms an oxide phase in which Al is segregated on the surface of the Fe-based soft magnetic powder. This oxide phase is grown by reacting Fe-based soft magnetic powder and oxygen by heat treatment, and is formed by an oxidation reaction exceeding the natural oxidation of Fe-based soft magnetic powder. Such heat treatment can be performed in an atmosphere in which oxygen exists, such as in the air or in a mixed gas of oxygen and an inert gas. Further, the heat treatment can be performed in an atmosphere in which water vapor exists, such as in a mixed gas of water vapor and inert gas. Of these, heat treatment in the air is simple and preferable.

  The heat treatment in this step may be performed at a temperature at which the oxide phase is formed. By such heat treatment, a laminated part having excellent insulation and strength can be obtained. Furthermore, the heat treatment in this step is preferably performed at a temperature at which the Fe-based soft magnetic powder is not significantly sintered. When the Fe-based soft magnetic powder is significantly sintered, a part of the oxide phase in which Al is segregated (the Al ratio is high) is surrounded by the alloy phase and is isolated in an island shape to form a neck. For this reason, the insulating function separating the Fe-based soft magnetic powder is lowered. The specific heat treatment temperature is preferably in the range of 600 to 900 ° C, more preferably in the range of 700 to 800 ° C, and still more preferably in the range of 750 to 800 ° C. The holding time in the above temperature range is appropriately set according to the size of the laminated component, the processing amount, the allowable range of characteristic variation, and the like, and is set to 0.5 to 3 hours, for example.

  Al in the Fe—Al—Cr alloy grains is concentrated in the surface layer, and the ratio of Al in the oxide phase is higher than that in the alloy phase inside the alloy grains, and segregation of Al in the oxide phase occurs. The element distribution can be observed with an SEM image.

  By forming such an oxide phase, the insulation and corrosion resistance of the Fe-based soft magnetic powder can be improved without using borosilicate glass. Moreover, since this oxide phase is formed after forming a molded object, it contributes also to the coupling | bonding of Fe type soft magnetic powder through this oxide phase. The Fe-based soft magnetic powders are bonded to each other through the oxide phase, whereby a high-strength laminated component is obtained. Therefore, the forming method is simplified, and the productivity is improved.

  Since the formed oxide phase is about several tens of nanometers in the grain boundary phase between two grains, the nonmagnetic portion can be reduced and the magnetic permeability can be increased. In addition, it was observed that the oxide phase covered not only the grain boundaries of the Fe-based soft magnetic powder but also the entire surface of the laminated component.

  Usually, the molded body includes a plurality of coils. Therefore, the unit molded body may be cut into necessary units before heat treatment so as to include at least one coil and heat-treated. Alternatively, the molded body may be heat-treated and then cut into a unit molded body.

  The terminal electrode may be formed and baked on the molded body using a conductor layer paste by a conventionally known formation method such as a printing method, a transfer method, or a dip method. As the conductor layer paste, the one used for the coil pattern can be used. The terminal electrode may be formed before or after the heat treatment. If it is before heat treatment, it can be baked in the heat treatment step. It is preferable to form a plating film on the terminal electrode so as to improve solderability. Such laminated parts are used as, for example, chokes, inductors, reactors, transformers, and the like.

  The conductor layer paste preferably contains glass powder. The glass after baking exists at the interface between the terminal electrode and the surface of the laminated component, and the adhesion strength of the terminal electrode to the laminated component can be improved. When Pt, Ru, or Rh is included, the heat treatment causes the surface of the multilayer component to be at the interface with the terminal electrode, rather than the oxide phase formed on the surface of the multilayer component that is not covered by the terminal electrode. A thick oxide phase is formed. The thick oxide layer directly under the terminal electrodes further increases the insulation between the terminal electrodes and improves the adhesion strength of the terminal electrodes.

  In the laminated component of the present embodiment, the case where it is manufactured by the sheet lamination method has been described, but it can be configured even if the printing lamination method is adopted, and is not limited to the above.

FIG. 4 shows the appearance of a laminated part of another embodiment, FIG. 5 shows a cross section thereof, and FIG. 6 shows an equivalent circuit thereof. The laminated component 10 encloses the coil, which is a semiconductor integrated circuit component IC and capacitors Cin, step-down DC-D C converter that implements Cout including a switching element and a control circuit on the surface thereof. Since the configuration of the laminated component 10 is substantially the same as that described above, a duplicate description is omitted.

  A plurality of terminal electrodes 90 are provided on the back surface of the multilayer component 10 and are connected to the semiconductor integrated circuit component IC and the inductor by connection electrodes formed on the side surfaces. The connection electrode may be formed by a through hole in the laminated component. Symbols attached to the terminal electrodes 90 correspond to the terminals of the semiconductor integrated circuit component IC to be connected, the terminal electrode Vcon is an output voltage variable control terminal, the terminal electrode Ven is an output ON / OFF control terminal, and an external terminal Vdd. Is a terminal for ON / OFF control of the switching element, the terminal electrode Vin is connected to the input terminal, and the terminal electrode Vout is connected to the output terminal. The terminal electrode GND is connected to the ground terminal GND. Since an oxide phase with excellent insulation is formed on the surface of the laminated component 10, it is possible to form terminal electrodes and connection electrodes, and it is excellent in strength, so it is suitable for mounting other electronic components. ing.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in this example are not intended to limit the scope of the present invention only to those unless otherwise specified.

  A laminated part was produced as follows. Fe-Al-Cr alloy particles were used as the Fe-based soft magnetic powder. The average particle diameter (median diameter d50) measured with a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.) was 10 μm. The Fe-based soft magnetic powder was a granular atomized powder, and its composition was Fe-5.0% Al-4.0% Cr in mass percentage. The atomized powder was used after removing coarse particles through a sieve of 440 mesh (aperture 32 μm).

  To 100 parts by weight of Fe-based soft magnetic powder, 26 parts of ethanol as a solvent, 7.2 parts of butanol, and 1.6 parts of polyvinyl butyral as a binder are added and mixed, defoamed to adjust the viscosity. A sheet was formed as a slurry for molding.

A coil pattern was formed on the obtained sheet using an Ag conductor layer paste, and the coil pattern was laminated. By a cold isostatic pressing method (CIP), the pressure was 350 kg / cm ² , the temperature was 85 ° C., and the time was 600. The molded body was pressed in seconds. The obtained molded body was cut into a single-piece molded body, and then a conductor layer paste to be a terminal electrode was attached to two opposing surfaces by a dipping method. After drying appropriately, this molded body was heat-treated in the atmosphere at a heat treatment temperature of 750 ° C. for 1 hour to obtain a laminated part. The external dimensions were 2.0 mm in length, 1.2 mm in width, and 1.2 mm in thickness. The inductance was 1 μH at 100 kHz.

  Bending and twisting were applied in a state where the laminated component produced by the above process was mounted on the substrate by soldering. When observed with a stereomicroscope, no cracks or cracks were observed in the magnetic layer or the terminal electrode.

Separately from the laminated parts, an annular sample was prepared using the sheet. The external dimensions after the heat treatment are an outer diameter of φ13.4 mm, an inner diameter of φ7.7 mm, and a height of 4.0 mm. A load was applied in the diameter direction from the outer peripheral side surface of the obtained sample, the maximum load P (N) at the time of fracture was measured, and the crushing strength σr (MPa) was obtained from the following equation.
σr = P (D−d) / (Id ² )
(Here, D: outer diameter of the core (mm), d: thickness of the core (mm), I: height of the core (mm))
As a result, a strength of 100 MPa exceeding the crushing strength of general ferrite was obtained.

Similarly, a disk-shaped sample (outer diameter φ13.5 mm, thickness 4 mm) is prepared using the sheet, and a conductive adhesive is applied to two opposing flat surfaces. After drying and solidification, the object to be measured is prepared. It was set between the electrodes. A resistance value R (Ω) was measured by applying a DC voltage of 50 V using an electrical resistance measuring device (8340A manufactured by ADC Corporation). The area A (m ² ) and the thickness t (m) of the plane of the object to be measured were measured, and the specific resistance ρ (Ωm) was calculated by the following equation. As a result, 1.3 × 10 ⁴ kΩm, which is about the same as that of ferrite. Specific resistance was obtained.
Specific resistance ρ (Ωm) = R × (A / t)

  The laminated part was cut, and the cut surface was observed with a scanning electron microscope (SEM / EDX) (magnification: 2000 times). FIG. 7 is a mapping showing a cross-sectional observation photograph and the distribution of Fe (iron), Al (aluminum), and O (oxygen). The brighter the color, the greater the number of target elements. It can be seen that the surface of the Fe—Al—Cr alloy grains is rich in oxygen and oxides are formed, and that the Fe—Al—Cr alloy grains are bonded to each other through the oxides. Further, Al has a remarkably high concentration of Al on the surface of the Fe—Al—Cr alloy grains. From these, it was confirmed that an oxide phase having a higher Al ratio than the internal alloy phase was formed on the surface of the Fe—Al—Cr alloy grains.

2 Magnetic layer 3, 3a-3c Coil pattern 10 Laminated component 200a, 200b Terminal electrode

Claims (6)

A coil composed of a coil pattern formed of a paste containing Ag powder is included in a magnetic body in which Fe-based soft magnetic powder is bonded through an oxide phase in which Al is segregated,
The Fe-based soft magnetic powder is an Fe—Al—Cr alloy grain that passes through a sieve having an opening of 32 μm and has a median diameter d50 in a cumulative particle size distribution of 20 μm or less,
The Fe—Al—Cr-based alloy grains include Al of 2.0% by mass to 10.0% by mass, Cr content of 1.0% by mass to 9.0% by mass, inevitable impurities and other elements. 1.0% by mass or less, the balance being Fe, the content of Al being greater than Cr,
The oxide phase is formed by oxidation of the Fe-Al-Cr alloy grains,
The magnetic component is formed by stacking a plurality of magnetic layers, and the coil pattern is stacked via the magnetic layers and connected in the stacking direction . The laminated component according to claim 1,
A laminated part, wherein the paste further contains at least one metal selected from the group consisting of Pd, Ir, Pt, Ru, Rh, Ti, and Co as a shrinkage rate control material . The laminated component according to claim 1,
A laminated part comprising one or more metals selected from Pt, Ru or Rh in the paste . A laminated part according to any one of claims 1 to 3,
Having a terminal electrode connected to the coil on the surface of the laminated component covered with the oxide phase;
A laminated part characterized in that glass exists between the surface of the laminated part and the terminal electrode . The laminated component according to claim 4, wherein
An electronic component is placed on the laminated component and connected to the terminal electrode. A method for manufacturing a laminated part according to any one of claims 1 to 5,
A step of forming a molded body in which a magnetic layer and a coil pattern are laminated;
A step of heat-treating the molded body in an atmosphere containing oxygen or an atmosphere containing water vapor at a temperature of 700 to 800 ° C. to form an oxide phase in which Al segregating Fe-based soft magnetic powder is segregated. A method for manufacturing a laminated part, comprising: