JP6748626B2 - Electronic parts - Google Patents

Description

The present invention relates to an electronic component, and more particularly to an electronic component such as a miniaturized inductor which has a magnetic core and can be surface-mounted on a circuit board.

Conventionally, an inductor having a magnetic core is known as a coil for a step-up/down circuit of a power supply in a portable electronic device, a choke coil used in a high frequency circuit, and the like.
As such an inductor, for example, as described in Patent Document 1, a coil conductor is wound around a ferrite core, and both ends of the coil conductor are connected to a pair of terminal electrodes provided on the surface of the ferrite core. The thing of the structure is known. Here, the ferrite core has a so-called drum shape having a winding core and a pair of flanges provided at the upper end and the lower end of the winding core. An inductor having such a structure generally has a feature that it is suitable for high-density mounting and low-profile mounting on a circuit board, because the external dimensions (especially height) can be reduced. There is.

JP, 2011-009644, A

In recent years, as electronic devices have become smaller, thinner, and more sophisticated, there has been a demand for a wire-wound inductor capable of higher density mounting and lower profile mounting while improving inductor characteristics and reliability.
The present invention provides an electronic component which has desired electrical characteristics and high reliability and can be favorably applied to an inductor or the like which can be mounted on a circuit board in a high density and a low profile. With the goal.

The electronic component according to the invention of claim 1 is an electronic component having a porous substrate, wherein the substrate has a layer made of a resin material on a surface layer thereof, and a part of the layer made of the resin material is An electrode material or an electrode containing the electrode material and an electrode bonding material is formed on the surface of the porous base material in which the pores of the porous base material are impregnated and on which the layer made of the resin material is formed. And the porous substrate is composed of particles of a soft magnetic alloy containing no glass, and the void portions are void portions between particles of the porous substrate, and The pore portion is characterized in that it is a pore portion having a water absorption rate or a porosity higher than that of the substrate made of ferrite .

According to a second aspect of the present invention, in the electronic component according to the first aspect, the electrodes are formed by applying a plate-like member made of the electrode material with an adhesive. To do.

According to a third aspect of the present invention, in the electronic component according to the first aspect, the electrode is formed by a metal thin film formed by using the electrode material by a sputtering method or a vapor deposition method. ..

The invention according to claim 4 is the electronic component according to any one of claims 1 to 3 , wherein the electronic component is a group of particles of a soft magnetic alloy containing iron, silicon, and an element that is more easily oxidized than iron. An oxide layer formed by oxidizing the soft magnetic alloy particles is formed on the surface of each soft magnetic alloy particle, and the oxide layer contains an element that is more easily oxidized than iron as compared with the soft magnetic alloy particle. Many are included, and the particles are bonded to each other through the oxide layer.

According to a fifth aspect of the present invention, in the electronic component according to the fourth aspect , the element that is more easily oxidized than iron is chromium, and the soft magnetic alloy contains at least 2 to 15 wt% of chromium. Characterize.

According to the present invention, it is possible to provide an electronic component, which has desired electrical characteristics and high reliability, and which can be favorably applied to an inductor or the like, which enables good high-density mounting and low-profile mounting on a circuit board. Therefore, it is possible to contribute to the improvement of reliability in addition to the reduction in size and thickness and the increase in functionality of the electronic device in which the electronic component is mounted.

It is a flowchart which shows 1st Embodiment of the electrode forming method of the electronic component which concerns on this invention. It is a flowchart which shows 2nd Embodiment of the electrode forming method of the electronic component which concerns on this invention. It is a figure which shows the characteristic regarding the impregnation of the resin solution in the metal powder compact and ferrite which are applied to the base|substrate of the electronic component which concerns on this embodiment. It is a schematic diagram which shows the cross section near the surface in the base|substrate which concerns on this embodiment, and the base|substrate which consists of ferrites. FIG. 3 is an enlarged schematic diagram for explaining a cross section near the surface of the base body according to the present embodiment. 4 is a table showing the measurement results of the bonding strength when the electrode forming method for an electronic component according to the first embodiment is applied. 9 is a table showing measurement results of adhesion strength when the electrode forming method for an electronic component according to the second embodiment is applied. It is a schematic perspective view which shows the 1st structural example (1st application example) of the electronic component which can apply the electrode forming method which concerns on this invention. It is a schematic sectional drawing which shows the internal structure of the electronic component which concerns on a 1st application example. It is a schematic block diagram which shows the 2nd structural example (2nd application example) of the electronic component which can apply the electrode formation method which concerns on this invention. It is a disassembled perspective view of the electronic component which concerns on a 2nd application example.

Hereinafter, an electrode forming method for an electronic component according to the present invention will be described in detail with reference to embodiments.
Here, the method for forming an electrode of an electronic component according to the present invention is a method for preventing permeation by preventing permeation of an electrode material or an electrode bonding material on the surface of a porous substrate having a predetermined water absorption rate or a predetermined porosity. A layer made of a glass material or a resin material was formed by impregnating or coating the material, and a base treatment was performed to fill a part of the layer made of the glass material or the resin material in the pores on the surface of the porous substrate . After that, an electrode is formed.

First, a porous substrate to which the method for forming an electrode of an electronic component according to the present invention is applied will be described.
The electronic component to which the electrode forming method for an electronic component according to the present invention is applied has a porous substrate having a water absorption of about 1.0% or more or a porosity of about 10 to 25%. Specifically, the electronic component substrate is composed of, for example, iron (Fe), silicon (Si), and a group of soft magnetic alloy particles containing an element that is more easily oxidized than iron. On the surface, an oxide layer in which the soft magnetic alloy particles are oxidized is formed, the oxide layer contains more elements that are more easily oxidized than the iron as compared with the soft magnetic alloy particles, and the particles form the oxide layer. It is possible to successfully apply the molded body of metal powder, which is bonded via the metal powder. In this embodiment, chromium (Cr), aluminum (Al), or the like can be applied as the element that is more easily oxidized than iron.

Here, a high saturation magnetic flux density Bs (for example, 1.2 T or more) and a high magnetic permeability μ (for example, 37 or more) can be realized by appropriately adjusting the composition, content, etc. of the soft magnetic alloy particles, and Even at a frequency of 100 kHz or more, it is possible to suppress the occurrence of eddy current loss in the particles. Therefore, the porous substrate having such magnetic characteristics can be favorably applied as a core member of an electronic component such as an inductor.
An embodiment of a method for forming an electrode in an electronic component having such a porous substrate will be described below.

<First Embodiment>
FIG. 1 is a flowchart showing a first embodiment of an electrode forming method for electronic parts according to the present invention.
As shown in FIG. 1, the electrode forming method for an electronic component according to the first embodiment generally includes a glass slurry preparing step S101, a glass coating step S102, a binder removal step S103, a glass baking step S104, and an electrode. Forming step S105.

In the glass slurry preparation step S101, a mixture of a binder resin and a solvent with glass powder (glass frit) in a predetermined ratio is stirred in a ball mill for a predetermined time to generate a glass slurry (slurry glass). Specifically, the glass powder used in the glass slurry preferably has an average particle size of, for example, about 0.1 to 10 μm and a softening point of about 800° C. or lower. As the binder resin, for example, polyvinyl alcohol or its modified product can be favorably applied. The solvent preferably contains water, and may be a mixture of water-soluble alcohols such as ethanol and isopropyl alcohol at a fixed ratio. The solid content of the glass powder and the binder resin in the glass slurry is preferably set to, for example, about 0.1 to 20 wt% with respect to the weight of the glass slurry. The weight of the binder resin with respect to the total weight is preferably set to, for example, about 1 to 20 wt %. The stirring time by the ball mill is set to about 16 hours, for example. The viscosity of the glass slurry thus produced is set to, for example, about 0.001 to 0.01 Pa·s.

In the glass coating step S102, the porous substrate of the electronic component as described above is put into the barrel of the temperature control barrel spray device, and the glass slurry is sprayed onto the substrate while rotating the barrel at a predetermined rotation speed. Form a thin glass coating on the surface of the substrate. Specifically, for example, 10,000 to 20,000 substrates of electronic components are put in the barrel, and 120 cc of glass slurry is sprayed for about 30 to 50 minutes by a spray method. Here, the temperature of the glass slurry at the time of spraying the glass slurry on the substrate is set to, for example, about 40 to 100° C., although it depends on the composition of the solvent.

In the binder removal step S103, the substrate having the glass coating film formed thereon is heat-treated at a predetermined temperature in a firing furnace to remove the resin component contained in the glass coating film (removing the binder). Specifically, the binder removal processing of the base body is, for example, heat treatment at 600° C. for about 120 minutes.

In the glass baking step S104, the debindered substrate is heat-treated at a predetermined temperature in a baking furnace to form a glass film on the surface of the substrate (glass baking treatment). Specifically, in the glass baking process, heat treatment is performed in the air or N 2 gas atmosphere at 700 to 800° C. for about 20 minutes, for example. As a result, the glass film is formed at least in the electrode formation region of the base. That is, as a result, a layer made of a glass material is formed at least in the electrode formation region of the base, and the pores on the surface of the porous base are partially filled with the glass material.

In the electrode forming step S105, an electrode is formed in a predetermined region (electrode forming region) of the glass-baked substrate. Specifically, as the electrode, a fired electrode obtained by applying an electrode paste obtained by adding glass to an electrode material to the above base and firing the electrode paste at a predetermined temperature can be favorably applied. Further, as another form of the electrode, for example, an electrode frame formed by adhering a conductive plate-shaped member (frame) made of an electrode material to the surface of the substrate with an adhesive can be favorably applied. Further, as still another form of the electrode, for example, an electrode film obtained by forming a metal thin film on the surface of the substrate by using an electrode material by a sputtering method, an evaporation method or the like can be favorably applied. Here, in the above-mentioned fired electrode, as an electrode material, for example, silver (Ag), an alloy of silver (Ag) and palladium (Pd), an alloy of silver (Ag) and platinum (Pt), copper (Cu), or the like is used. Can be applied well. Further, in the above-mentioned electrode frame, for example, a phosphor bronze plate or the like can be favorably applied as an electrode material, and, for example, an epoxy resin can be favorably applied as an adhesive for adhering to the base. .. Furthermore, in the above-mentioned electrode film, for example, titanium (Ti), an alloy containing titanium (Ti), or the like can be favorably applied as the electrode material. Further, when the above-mentioned firing electrode or electrode film is applied as an electrode, a metal plating layer may be formed on the surface thereof by electrolytic plating.

In the present embodiment, as a method of coating glass on the base of the electronic component, a method of spraying glass slurry on the base in a rotating barrel to form a glass coating film on the entire surface of the base has been described. The present invention is not limited to this. That is, as a method for forming the glass coating film on the substrate, various methods such as printing, roller, brush coating, vacuum impregnation, and potting can be favorably applied in addition to the above-mentioned spray method. By such a method, the glass coating film can be satisfactorily formed on the entire surface of the substrate or at least on the electrode formation region. That is, by such a method, a layer made of a glass material is formed on the entire surface of the substrate, or at least on the electrode formation region, and a part of the layer made of the glass material is formed on the pores on the surface of the porous substrate. Is filled.

<Second Embodiment>
FIG. 2 is a flowchart showing a second embodiment of the electrode forming method for electronic parts according to the present invention.
As shown in FIG. 2, the electrode forming method for an electronic component according to the second embodiment generally includes a resin solution preparing step S201, a resin impregnating step S202, a drying step S203, a curing step S204, and an electrode forming step. And S205.

In the resin solution preparing step S201, a resin solution containing a resin material in a predetermined ratio is prepared. Here, it is preferable that the resin solution is made of an organic resin material (for example, a silicone resin, an epoxy resin, an acrylic resin, or the like) or an inorganic material to which a solid filler is not added or a solid filler is slightly added. Specifically, for example, a 30 wt% silicone resin diluted with toluene can be favorably applied as a resin solution. A curing agent or the like is appropriately added to such a resin solution.

In the resin impregnation step S202, the base of the porous electronic component is dipped in the resin solution to bring the base into a vacuum state, thereby expelling the air inside the base and impregnating the resin solution (vacuum impregnation). Specifically, the pressure during vacuum impregnation is preferably reduced to, for example, 20 Torr (26 hpa) or less.

In the drying step S203, the substrate is dried to dry the resin solution on the surface and inside. Specifically, the resin solution on the surface of the substrate and the resin solution on the inside are air-dried, for example, by leaving them to stand naturally for about 1 hour.

In the curing step S204, the resin solution with which the substrate is impregnated is cured by heat treating the substrate at a predetermined temperature. Specifically, the substrate is heat-treated at 200° C. for about 1 hour in a humid atmosphere. After the heat treatment, the substrate is left to stand to be naturally cooled for, for example, 30 minutes or more. By the series of these steps (S201, S202, S203, S204), the surface of the electrode formation region of the surface layer of the base body can be in a state where a layer made of a resin material is formed, and the holes inside the electrode formation region of the surface layer of the base body can be formed. The part can be in a state in which a part of the layer made of the resin material is filled.

In the electrode forming step S205, an electrode is formed in a predetermined region (electrode forming region) of the substrate that has been impregnated and cured with the resin solution. Specifically, as the electrode, an electrode frame formed by adhering a conductive plate-shaped member (frame) made of an electrode material to the surface of the base with an adhesive can be favorably applied to the base. it can. Further, as another form of the electrode, for example, an electrode film obtained by forming a metal thin film on the surface of the substrate by using an electrode material by a sputtering method, a vapor deposition method or the like can be preferably applied. Here, in the above-mentioned electrode frame, for example, a phosphor bronze plate or the like can be favorably applied as an electrode material, and an epoxy resin, for example, can be favorably applied as an adhesive for adhering to the substrate. it can. Further, in the above-mentioned electrode film, for example, titanium (Ti) or an alloy containing titanium (Ti) can be favorably applied as the electrode material. Furthermore, when the above-mentioned electrode film is applied as an electrode, a metal plating layer may be formed on the surface by electrolytic plating.

In the present embodiment, as a method of impregnating the resin solution into the substrate of the electronic component, a method of immersing the substrate in the resin solution for vacuum impregnation and impregnating the resin solution over the entire surface of the substrate has been described. It is not limited to this. That is, as a method for impregnating the substrate with the resin solution, various methods such as spraying, printing, roller, brush coating, and potting can be favorably applied. By such a method, the resin solution can be satisfactorily impregnated on the entire surface of the substrate or at least the electrode formation region. That is, by such a method, the surface of the electrode formation region of the surface layer of the substrate can be in a state where a layer made of a resin material is formed, and the void portion inside the electrode formation region of the surface layer of the substrate is made of the layer made of the resin material. It can be partially filled.

Further, although the case where the silicon resin is applied as the resin solution has been described in the present embodiment, the present invention is not limited to this, and, for example, 75 wt% epoxy resin is applied as the resin solution. May be. In this case, the heat treatment in the curing step is set to, for example, 180° C. for about 1 hour.

In addition, in the present invention, as another resin solution, for example, a solvent-free one-component type inorganic pore-sealing agent containing an alkoxysilane compound as a raw material of a silicon resin as a main component (for example, "D&D Co., Ltd." Permeate HS-100" (trade name) can also be applied favorably. This type of inorganic pore-sealing agent comprises an alkoxysilane compound or a partial hydrolysis-condensation product thereof, an inorganic pigment, an inorganic additive, and a curing catalyst.

Then, when such an inorganic pore-sealing agent is used as a resin solution, the method for impregnating a substrate of an electronic component is as follows. First, the inorganic pore-sealing agent and the substrate are defoamed in vacuum for about 5 to 10 minutes. After the treatment, the inorganic pore-sealing agent and the substrate are mixed in a vacuum. Then, the vacuum state is released and the substrate is impregnated with the inorganic pore-sealing agent. After that, the substrate is subjected to liquid removal treatment and left in a moist atmosphere for, for example, 24 hours, whereby the inorganic pore-sealing agent impregnated in the substrate can be cured well.

(Verification of action and effect)
Next, the function and effect of the electrode forming method of the electronic component according to each of the above-described embodiments will be described.

Here, in order to verify the function and effect of the electrode forming method of the electronic component according to the present embodiment, as a comparison target, the base of the electronic component is made of a well-known ferrite, and the base treatment as shown in each of the above-described embodiments is performed. It shows the case where is not applied. Note that electronic components having a base made of ferrite are already commercially available and mounted on various electronic devices such as inductors, and are used in various reliability tests such as adhesion strength. It has been highly evaluated in the market.

FIG. 3 is a diagram showing characteristics regarding impregnation of a resin solution in a molded body of metal powder and ferrite applied to the base body of the electronic component according to the present embodiment. Here, FIG. 3A is a table showing differences in water absorption rate, density (apparent density, true density), and porosity between the base body according to the present embodiment and the base body made of ferrite. FIG. 6B is a diagram showing a difference in water absorption between the base body according to the present embodiment and the base body made of ferrite. Further, FIG. 4 is a schematic diagram showing a cross section near the surface of the base body according to the present embodiment and the base body made of ferrite. FIG. 4A is a schematic diagram showing a cross section near the surface of the substrate according to the present embodiment, and FIG. 4B is a schematic diagram showing a cross section near the surface of the substrate made of ferrite. FIG. 5 is an enlarged schematic diagram for explaining a cross section near the surface of the substrate according to the present embodiment.

As described above, the molded body of metal powder applied to the base body of the electronic component according to the present embodiment is porous, and thus has a dense crystal structure as shown in FIGS. 3(a) and 3(b). It has higher water absorption and porosity than known ferrite. Specifically, in the substrate according to this embodiment, when the substrate having a true density of 7.6 g/cm ³ has an apparent density of 6.2 g/cm ³ , the water absorption rate is 2% and the porosity is 18.4. Shows a high value of %. In contrast, in the substrate made of a ferrite, when true density of the density 5.34 g / cm ³ apparent substrate 5.35 g / cm ^3, water absorption of 0.2%, a porosity of 0.2 %, which is a low value of about 1/10 or less as compared with the substrate according to the present embodiment. This state is shown in FIGS.

That is, as shown in FIG. 4A, the substrate according to the present embodiment has a structure in which an oxide film is formed on the surface of the metal powder and the metal powders are bonded to each other through the oxide film. Therefore, relatively large pores are present between the metal powders from the surface of the substrate to the inside thereof. On the other hand, as shown in FIG. 4(b), the well-known ferrite base body has a dense crystal structure, so that there are almost no holes inside the base body. ..

In each of the above-described embodiments, such a porous substrate is impregnated or coated with glass or resin prior to the electrode forming step, and baked or cured to give a glass to the pores. Alternatively, the resin is permeated and filled to improve the porosity at least on the surface or surface of the substrate.

Next, the bonding strength when the electrode is formed on the porous substrate will be verified.
FIG. 6 is a table showing the measurement results of the bonding strength when the electrode forming method for an electronic component according to the first embodiment is applied, and FIG. 7 is an electrode forming method for an electronic component according to the second embodiment. 7 is a table showing the measurement results of the adhesion strength when the is applied.

First, a method of measuring the adhesion strength will be described.
First, an electrode was formed on the surface of the substrate, and the electrode was soldered onto a mounting land made of a copper foil formed on a glass-epoxy resin substrate, for example, to mount the substrate on the substrate. Here, as a method of mounting the base on the board, after the cream solder was printed on the board, the base was mounted on the mounting land and heated to 245° C. to perform reflow soldering processing for mounting. Then, with respect to the board on which the base is mounted, the base is pressed from the side surface of the base in a direction parallel to the upper surface of the board with a jig of a peel strength tester, and the peel strength is measured. An evaluation was made.

Next, the bonding strength of the base body having the electrodes obtained by applying the electrode forming method according to the first embodiment will be verified with reference to FIG. Here, with respect to the case where the metal powder compact is applied as the porous substrate, the presence or absence of the base treatment and the fixing strength, and the case where the metal powder compact is applied as the substrate and the fixing strength when the ferrite is applied Verified.

As shown in the first embodiment, a metal powder compact is applied as a substrate, glass coating is performed as a base treatment, and an electrode material made of copper (Cu) is subjected to predetermined firing conditions (baking temperature, baking atmosphere; When the baked electrode was formed by baking (see FIG. 6), the fixing strength of the substrate was 291N. On the other hand, a molded body of metal powder is applied as the substrate, and the electrode material made of copper (Cu) is fired under predetermined firing conditions (baking temperature, baking atmosphere; see FIG. 6) without performing the base treatment. The adhesion strength of the substrate when forming the fired electrode was 54N and 95N. That is, it was confirmed that the substrate according to the present embodiment has a bonding strength that is approximately three times or more that of the case where the base treatment is not performed.

Further, when ferrite is applied as a substrate and an electrode material made of silver (Ag) or copper (Cu) is fired under predetermined firing conditions (baking temperature, baking atmosphere; see FIG. 6) to form a baked electrode, The fixing strengths of the substrates were 244N and 336N, respectively. That is, it was confirmed that the base body according to the present embodiment has the same degree of fixing strength as compared with the case where ferrite is applied.

Next, the bonding strength of the substrate having the electrodes obtained by applying the electrode forming method according to the second embodiment will be verified with reference to FIG. 7. Again, regarding the case of applying the metal powder compact as the porous substrate, the presence or absence of the base treatment and the fixing strength, and the case of applying the metal powder compact as the substrate and the fixing strength when applying the ferrite Verified.

As shown in the second embodiment, a molded body of metal powder is applied as a substrate, epoxy resin is impregnated as a base treatment, and a plate member made of phosphor bronze is bonded by using an epoxy resin adhesive. The adhesion strength of the substrate when it was adhered to form an electrode frame was 141N. Similarly, when the base resin is impregnated with silicon resin and the plate-shaped member made of phosphor bronze is adhered using an epoxy resin adhesive to form the electrode frame, the adhesion strength of the base is It was 139N. On the other hand, when an electrode frame is formed by applying a metal powder molded body as a substrate and performing no base treatment and adhering a plate-shaped member made of phosphor bronze with an epoxy resin adhesive. The adhesion strength of the substrate was 69 N. That is, it was confirmed that the base body according to the present embodiment has approximately twice or more the fixing strength as compared with the case where the base treatment is not performed.

Further, when ferrite was applied as the base and a plate-shaped member made of phosphor bronze was adhered using an epoxy resin adhesive to form the electrode frame, the fixing strength of the base was 142N. That is, it was confirmed that the base body according to the present embodiment has the same degree of fixing strength as compared with the case where ferrite is applied.

As described above, according to the electrode forming method of the electronic component according to each of the above-described embodiments, before forming the electrode, the substrate is impregnated with or coated with glass or a resin material, and the base treatment for baking or curing is performed to obtain the glass. Since the resin material permeates and fills the pores of the porous substrate, the porosity of the surface or surface layer of the substrate is improved. As a result, it is possible to prevent the electrode material, the adhesive (electrode bonding material), etc., from penetrating into the base during electrode formation, and to reduce the bonding and adhesion between the base and the electrode. It is possible to realize the same fixing strength as in the case of being applied to, and it is possible to contribute to the improvement of the reliability of the electronic device in which such an electronic component is mounted.

(Application example)
The electrode forming method shown in each of the above-described embodiments can be favorably applied to electronic components such as surface-mounted inductors. Hereinafter, an application example will be briefly described. The configuration shown here is an example to which the present invention is applicable, and the present invention is not limited to this.

FIG. 8 is a schematic perspective view showing a first configuration example (first application example) of an electronic component to which the electrode forming method according to the present invention can be applied. Here, FIG. 8A is a schematic perspective view of the electronic component according to the present application example as viewed from the upper surface side (upper flange portion side), and FIG. 8B illustrates the electronic component according to the present application example. It is a schematic perspective view seen from a bottom surface side (lower flange portion side). FIG. 9 is a schematic cross-sectional view showing the internal structure of the electronic component according to the first application example. Here, FIG. 9 is a view showing a cross section of the electronic component taken along the line AA shown in FIG. 8.

As shown in FIGS. 8 and 9, the electronic component according to the first application example is a wound-type inductor 10 having a drum core structure, and includes a core member 11 and a coil conductor 12 wound around the core member 11. And a pair of terminal electrodes 16A and 16B to which the end portions 13A and 13B of the coil conductor 12 are connected, and an exterior member 18 made of a magnetic powder-containing resin that covers the outer circumference of the coil conductor 12 wound. Have

As shown in FIGS. 8A and 9, the core member 11 includes a column-shaped winding core portion 11a around which the coil conductor 12 is wound, and an upper collar portion 11b provided at the upper end of the winding core portion 11a in the drawing. And a lower collar portion 11c provided at the lower end of the winding core portion 11a in the drawing, and the appearance thereof has a drum shape. Here, the core member 11 corresponds to the base body shown in each of the above-described embodiments, and for example, particles of a soft magnetic alloy containing iron (Fe), silicon (Si), and an element that is more easily oxidized than iron. A porous shaped body composed of groups is applied. In particular, in the wire-wound inductor according to this application example, by using soft magnetic alloy particles containing 2 to 15 wt% of chromium (Cr) as an element that is more easily oxidized than iron, excellent inductor characteristics (inductance -DC superposition characteristic: L-Idc characteristic) can be realized.

In addition, as shown in FIGS. 8B and 9, a pair of terminals is provided on the bottom surface (outer surface) 11B of the lower collar portion 11c of the core member 11 with an extension line of the central axis CL of the winding core portion 11a interposed therebetween. Electrodes 16A and 16B are formed. Here, on the bottom surface 11B, grooves 15A and 15B are formed in regions (electrode formation regions) where the pair of terminal electrodes 16A and 16B are formed, as shown in FIGS. 8B and 9, for example. It may be one.

As the coil conductor 12, as shown in FIG. 9, a coated conductor in which an insulating coating 14 made of polyurethane resin, polyester resin or the like is formed on the outer periphery of a metal wire 13 made of copper (Cu), silver (Ag) or the like is applied. To be done. The coil wire 12 is wound around the columnar winding core portion 11a of the core member 11, and as shown in FIGS. 8B and 9, one and the other end portions 13A and 13B are With the insulating coating 14 removed, the terminal electrodes 16A and 16B are conductively connected by solders 17A and 17B, respectively.

Here, as the coil conductor 12, for example, a covered conductor having a diameter of 0.1 to 0.2 mm is wound around the winding core portion 11 a of the core member 11 3.5 to 15.5 times. The metal wire 13 applied to the coil conductor 12 is not limited to a single wire, and may be two or more wires or a stranded wire. Further, the metal wire 13 of the coil conductor 12 is not limited to one having a circular cross-sectional shape, and for example, a rectangular wire having a rectangular cross-sectional shape, a square wire having a square cross-sectional shape, or the like is used. Can also When the terminal electrodes 16A and 16B are provided inside the grooves 15A and 15B, the diameters of the ends 13A and 13B of the coil conductor 12 are set to be larger than the depths of the grooves 15A and 15B. Is preferred.

Both ends 13A and 13B of the coil conductor 12 are conductively connected to the pair of terminal electrodes 16A and 16B by solders 17A and 17B, respectively, with the insulating coating 14 removed. Here, the terminal electrodes 16A and 16B correspond to the electrodes shown in each of the above-described embodiments, and the electrode forming method shown in each of the above-described embodiments is used for the bottom surface 11B of the porous core member 11 that is the base. Formed. That is, prior to the step of forming the terminal electrodes 16A and 16B, a glass or resin is impregnated or coated, and a base treatment of baking or curing is performed to allow the glass or resin to permeate into the pores of the porous core member 11. And the porosity is improved at least on the surface or the surface layer of the core member 11 in the electrode formation region. Here, the terminal electrodes 16A and 16B are, as described above, a firing electrode obtained by applying an electrode paste to the electrode-shaped back region of the core member 11 and firing at a predetermined temperature, or a conductive plate-like member. It is possible to apply an electrode frame adhered using an adhesive, or an electrode film obtained by forming a thin film of an electrode material by sputtering or vapor deposition.

In addition, when applying a baked electrode of copper (Cu) or silver (Ag) as the terminal electrodes 16A and 16B, or when applying an electrode frame made of pure copper or phosphor bronze, as the core member 11, For example, a metal powder having a particle size of 6 to 23 μm (for example, 4.5Cr3SiFe manufactured by Atomics Co., Ltd.) is molded (for example, 6.0 to 6.6 g/cm ³ →theoretical porosity is 22 to 13%), ground, and baked. As a result, as shown in the above-described verification of the function and effect, high fixing strength between the core member 11 and the terminal electrodes 16A and 16B can be realized.

FIG. 10 is a schematic configuration diagram showing a second configuration example (second application example) of an electronic component to which the electrode forming method according to the present invention can be applied. Here, FIG. 10A is a schematic perspective view of the electronic component according to the first application example, and FIG. 10B is an electronic component taken along the line BB shown in FIG. It is a figure which shows the cross section of. FIG. 11 is an exploded perspective view of an electronic component according to the second application example.

As shown in FIGS. 10 and 11, the electronic component according to the second application example is a laminated inductor 20, and is provided in a rectangular parallelepiped component body 21 and both end portions in the length direction of the component body 21. And a pair of terminal electrodes 24 and 25 that are formed.

As shown in FIGS. 10A and 10B, the component body 21 has a rectangular parallelepiped magnetic body portion 22 and a spiral coil portion 23 covered by the magnetic body portion 22. The one end of the coil portion 23 is connected to the terminal electrode 24, and the other end is connected to the terminal electrode 25.

As shown in FIG. 11, the magnetic body portion 22 has a structure in which, for example, a total of 20 magnetic body layers ML1 to ML6 are laminated and integrated. Here, the magnetic body portion 22 corresponds to the base body shown in each of the above-described embodiments and is composed of a group of particles of a soft magnetic alloy containing iron (Fe), silicon (Si), and chromium (Cr). A porous molded body is applied.

The coil portion 23 is mainly composed of, for example, a silver (Ag) particle group, and as shown in FIG. 11, a plurality of coil segments CS1 to CS5 and relay segments IS1 to IS4 connecting the coil segments CS1 to CS5. And have a coil structure that is integrated in a spiral shape.

Each of the coil segments CS1 to CS4 has a strip shape, and has a predetermined plane pattern as shown in FIG. Further, each of the relay segments IS1 to IS4 has a columnar shape penetrating the magnetic layers ML1 to ML4. Then, as shown in FIGS. 10B and 11, the coil segment CS1 of the uppermost layer is connected to the terminal electrode 24 through the lead-out portion LS1 formed continuously, and the coil segment CS5 of the lowermost layer is connected. Is connected to the terminal electrode 25 via the continuously formed lead-out portion LS2.

The pair of terminal electrodes 24 and 25 are mainly composed of, for example, a silver (Ag) particle group similarly to the coil portion 23, and as shown in FIGS. Is formed on each end face and four side faces near the end face. Here, the terminal electrodes 24 and 25 correspond to the electrodes shown in each of the above-described embodiments, and the electrodes shown in each of the above-described embodiments are provided at both ends in the length direction of the porous component body 21 that is the base. It is formed using the forming method. That is, prior to the step of forming the terminal electrodes 24, 25, glass or resin is impregnated or coated, and a base treatment of baking or curing is performed to allow the glass or resin to permeate into the pores of the porous component body 21. And the porosity is improved at least on the surface or surface of the component body 21 in the electrode formation region.

As described above, according to each of the above-described application examples, in various inductors that can be surface-mounted on a circuit board, a core member or component in which an electrode material, an electrode bonding material, an adhesive, or the like is a base during electrode formation. It is possible to prevent the terminal electrode from penetrating into the main body and deteriorating the bondability and adhesiveness of the terminal electrode. Therefore, a high bonding strength between the base of the inductor and the terminal electrode can be realized, which can contribute to the improvement of the manufacturing yield and the reliability of the electronic device equipped with such an inductor.

In the application example described above, the case where the present invention is applied to the terminal electrode of the inductor has been described, but the present invention is not limited to this. That is, the method for forming an electrode of an electronic component according to the present invention is not limited to other electronic components as long as an electrode is formed on the electronic component having a porous substrate by using an electrode material or an electrode bonding material. Can be applied well.

INDUSTRIAL APPLICABILITY The present invention is suitable for application to electronic components such as miniaturized inductors that can be surface-mounted on a circuit board. In particular, in an electronic component having a porous substrate, electrodes can be formed well on the substrate, which is extremely effective.

DESCRIPTION OF SYMBOLS 10 winding type inductor 11 core member 11a winding core part 11b upper flange part 11c lower flange part 12 coil lead wire 16A, 16B terminal electrode 18 exterior member 20 laminated inductor 21 component body 22 magnetic material part 23 coil part 24, 25 terminal electrode S101 Glass slurry preparation step S102 Glass coating step S103 Binder removal step S104 Glass baking step S105 Electrode formation step S201 Resin solution preparation step S202 Resin impregnation step S203 Drying step S204 Curing step S205 Electrode forming step

Claims (5)

An electronic component having a porous substrate,
The substrate has a layer made of a resin material on its surface layer, and a part of the layer made of the resin material is impregnated in the pores of the porous substrate, and a layer made of the resin material is formed. Forming an electrode material or an electrode containing the electrode material and an electrode bonding material on the surface of the porous substrate, and
The porous substrate is composed of particles of a soft magnetic alloy containing no glass,
The void portion is a void portion between particles of the porous substrate, and
An electronic component, wherein the void portion of the base is a void portion having a water absorption rate or a porosity higher than a water absorption rate or a porosity of a base body made of ferrite. The electronic component according to claim 1, wherein the electrode is formed by subjecting a plate-shaped member made of the electrode material to an attachment process using an adhesive. The electronic component according to claim 1, wherein the electrode is formed by a metal thin film formed by using the electrode material by a sputtering method or a vapor deposition method. The electronic component is composed of a group of particles of a soft magnetic alloy containing iron, silicon, and an element that is more easily oxidized than iron, and is formed by oxidizing the soft magnetic alloy particles on the surface of each soft magnetic alloy particle. An oxidized layer is formed, the oxidized layer contains more elements that are more easily oxidized than iron as compared with the soft magnetic alloy particles, and the particles are bonded to each other through the oxidized layer. The electronic component according to any one of 1 to 3 . The element that is more easily oxidized than iron is chromium,
The electronic component according to claim 4 , wherein the soft magnetic alloy contains at least 2 to 15 wt% of chromium.

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