JP6922044B2 - Electronic components - Google Patents

Description

The present invention relates to electronic components, and more particularly to electronic components such as miniaturized inductors which have a magnetic core and can be surface-mounted on a circuit board.

Conventionally, inductors having a magnetic core are known as coils for buck-boost circuits of power supplies in portable electronic devices, choke coils used in high-frequency circuits, 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 structure is known. Here, the ferrite core has a so-called drum-shaped shape having a winding core portion and a pair of flange portions provided at the upper end and the lower end of the winding core portion. An inductor having such a structure has a feature that it is suitable for high-density mounting or low-profile mounting on a circuit board because the external dimensions (particularly the height dimension) can be reduced in general. There is.

Japanese Unexamined Patent Publication No. 2011-09644

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

The electronic component according to the invention according to claim 1 is an electronic component having a porous substrate, and the substrate has a layer made of a glass material on its surface layer, and a part of the layer made of the glass material is said. The electrode material or the electrode material and the electrode are formed on the glass layer which is impregnated in the pores of the porous substrate and which is the electrode forming region on the surface of the porous substrate on which the layer made of the glass material is formed. The electrode containing the bonding material is formed, and the porous substrate is made of soft magnetic alloy particles, and the pore portion is a pore portion between the particles of the porous substrate. The vacant portion of the substrate is a vacant portion in which the water absorption rate and the porosity exceed the water absorption rate and the porosity of the substrate made of ferrite, and the electrode is the electrode material or the electrode material. It is characterized in that it is formed by firing the electrode bonding material.

According to the second aspect of the present invention, in the electronic component according to the first aspect, the water absorption rate and the porosity of the vacant portion of the substrate exceeding the water absorption rate and the porosity of the substrate made of ferrite have a water absorption rate of 1. It is a molded body of a metal powder having a porosity of 0% or more or a porosity of 10 to 25%.

The invention according to claim 3 is the electronic component according to claims 1 and 2, wherein the electronic component is composed of iron, silicon, and a group of particles of a soft magnetic alloy containing 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 more elements that are more easily oxidized than iron as compared with the soft magnetic alloy particles. The particles are characterized in that they are bonded to each other via the oxide layer.
The invention according to claim 4 states that in the electronic component according to claim 3, 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. It is a feature.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided an electronic component which can be satisfactorily applied such as an inductor capable of good high-density mounting and low-profile mounting on a circuit board while having desired electrical characteristics and high reliability. In addition to making the electronic device on which the electronic component is mounted smaller and thinner and having higher functionality, it is possible to contribute to the improvement of reliability.

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 the 2nd Embodiment of the electrode forming method of the electronic component which concerns on this invention. It is a figure which shows the characteristic about the impregnation of the resin solution in the molded body of the metal powder applied to the substrate of the electronic component which concerns on this embodiment, and ferrite. It is a schematic diagram which shows the cross section in the vicinity of the surface of the substrate which concerns on this embodiment, and the substrate made of ferrite. It is an enlarged schematic diagram for demonstrating the cross section in the vicinity of the surface of the substrate which concerns on this embodiment. It is a table which shows the measurement result of the sticking strength when the electrode forming method of the electronic component which concerns on 1st Embodiment is applied. It is a table which shows the measurement result of the sticking strength when the electrode forming method of the electronic component which concerns on 2nd Embodiment is applied. It is a schematic perspective view which shows the 1st structural example (1st application example) of the electronic component to which the electrode forming method which concerns on this invention can apply. It is schematic cross-sectional view which shows the internal structure of the electronic component which concerns on 1st application example. It is a schematic block diagram which shows the 2nd structural example (2nd application example) of the electronic component to which the electrode forming method which concerns on this invention can apply. It is an exploded perspective view of the electronic component which concerns on the 2nd application example.

Hereinafter, the electrode forming method of the electronic component according to the present invention will be described in detail by showing embodiments.
Here, the method for forming an electrode of an electronic component according to the present invention is a permeation prevention method for 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 the pores on the surface of the porous substrate with a part of the layer made of the glass material or the resin material. Later, it is characterized by forming an electrode.

First, a porous substrate to which the electrode forming method for electronic components according to the present invention is applied will be described.
The electronic component to which the electrode forming method for the electronic component according to the present invention is applied has a porous substrate having a water absorption rate of about 1.0% or more or a porosity of about 10 to 25%. Specifically, the substrate of the electronic component 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, and each soft magnetic alloy particle is composed of. An oxide layer obtained by oxidizing the soft magnetic alloy particles is formed on the surface, and the oxide layer contains more elements that are more easily oxidized than iron as compared with the soft magnetic alloy particles, and the particles form the oxide layer. A molded metal powder molded body bonded via the metal powder can be satisfactorily applied. In this embodiment, chromium (Cr), aluminum (Al), or the like can be applied as an element that is more easily oxidized than iron.

Here, by appropriately adjusting the composition and content of the soft magnetic alloy particles, it is possible to realize 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). Even at a frequency of 100 kHz or higher, it is possible to suppress the occurrence of eddy current loss in the particles. Therefore, a porous substrate having such magnetic characteristics can be satisfactorily 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 is shown below.

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

In the glass slurry preparation step S101, a glass powder (glass frit) mixed with a binder resin and a solvent at a predetermined ratio is stirred with a ball mill for a predetermined time to generate a glass slurry (slurry-like 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 less. Further, as the binder resin, for example, polyvinyl alcohol or a modified product thereof can be satisfactorily applied. Further, the solvent preferably contains water, and may be a mixture of water-soluble alcohol such as ethanol and isopropyl alcohol at a constant ratio. The solid content of the glass powder and the binder resin in the glass slurry is preferably set to about 0.1 to 20 wt% with respect to the weight of the glass slurry, for example, and further, the glass powder and the binder resin. 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, for example, about 16 hours. 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 sprayer, and the glass slurry is sprayed on the substrate while rotating the barrel at a predetermined rotation speed. A thin glass coating is formed on the surface of the substrate. Specifically, for example, 1000 to 20000 electronic component substrates are put into the barrel, and 120 cc of glass slurry is sprayed by a spray method for about 30 to 50 minutes. Here, the temperature of the glass slurry when the glass slurry is sprayed onto 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 resin component contained in the glass coating film is removed (binder removal treatment) by heat-treating the substrate on which the glass coating film is formed at a predetermined temperature in the firing furnace. Specifically, in the binder removal treatment of the substrate, for example, heat treatment is performed at 600 ° C. for about 120 minutes.

In the glass baking step S104, a glass film is formed on the surface of the substrate (glass baking treatment) by heat-treating the debinder-treated substrate at a predetermined temperature in the firing furnace. Specifically, the glass baking process is performed by heat treatment in the atmosphere or N2 gas atmosphere at, for example, 700 to 800 ° C. for about 20 minutes. As a result, a glass film is formed at least in the electrode forming region of the substrate. That is, as a result, a layer made of a glass material is formed at least in the electrode forming region of the substrate, and a part of the layer made of the glass material is filled in the pores on the surface of the porous substrate.

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, for example, an electrode paste obtained by adding glass to an electrode material to the substrate and firing at a predetermined temperature can be satisfactorily 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 a substrate using an adhesive can be satisfactorily 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 a substrate by using a sputtering method, a vapor deposition method, or the like for an electrode material can be satisfactorily applied. Here, in the above-mentioned fired electrode, as the electrode material, for example, silver (Ag), an alloy of silver (Ag) and palladium (Pd), an alloy of silver (Ag) and platinum (Pt), copper (Cu) and the like are used. It can be applied well. Further, in the above-mentioned electrode frame, for example, a phosphor bronze plate or the like can be satisfactorily applied as an electrode material, and for example, an epoxy resin can be satisfactorily applied as an adhesive for adhering to a substrate. .. Further, in the above-mentioned electrode film, for example, titanium (Ti), an alloy containing titanium (Ti), or the like can be satisfactorily applied as the electrode material. Further, when the above-mentioned fired electrode or electrode film is applied as the electrode, a metal plating layer may be formed on the surface thereof by electrolytic plating.

In the present embodiment, as a method of glass coating the substrate of an electronic component, a method of spraying a glass slurry on the substrate in a rotating barrel to form a glass coating film on the entire surface of the substrate has been described. The present invention is not limited to this. That is, as a method for forming a glass coating film on a substrate, various methods such as printing, rollers, brush coating, vacuum impregnation, and potting can be satisfactorily applied in addition to the spray method as described above. Then, 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 forming region. That is, by such a method, a layer made of glass material is formed on the entire surface of the substrate, or at least on the electrode forming region, and a part of the layer made of 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 components according to the present invention.
As shown in FIG. 2, the method for forming electrodes of electronic components according to the second embodiment is roughly a resin solution preparation step S201, a resin impregnation step S202, a drying step S203, a curing step S204, and an electrode forming step. It has S205 and.

In the resin solution preparation step S201, a resin solution containing a resin material having a predetermined ratio is prepared. Here, the resin solution is preferably made of an organic resin material (for example, silicon resin, epoxy resin, acrylic resin, etc.) or an inorganic material to which no solid filler is added or to which a small amount of solid filler is added. Specifically, for example, a 30 wt% silicon resin diluted with toluene can be satisfactorily 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 substrate of the porous electronic component is immersed in the resin solution and the substrate is put into a vacuum state to expel the air inside the substrate and impregnate the resin solution (vacuum impregnation). Specifically, the pressure at the time of 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 and inside of the substrate is air-dried by allowing it to stand naturally for, for example, about 1 hour.

In the curing step S204, the substrate is heat-treated at a predetermined temperature to cure the resin solution impregnated in the substrate. Specifically, the substrate is heat-treated in a humid atmosphere at, for example, at 200 ° C. for about 1 hour. After the heat treatment, the substrate is left to cool naturally for, for example, 30 minutes or more. By a series of these steps (S201, S202, S203, S204), the surface of the electrode forming region on the surface layer of the substrate can be made into a state in which a layer made of a resin material is formed, and holes inside the electrode forming region on the surface layer of the substrate are formed. The portion can be in a state where 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 impregnated with the resin solution and cured. Specifically, as the electrode, an electrode frame formed by adhering a conductive plate-shaped member (frame) made of, for example, an electrode material to the surface of the substrate using an adhesive can be satisfactorily applied to the substrate. can. Further, as another form of the electrode, for example, an electrode film obtained by forming a metal thin film on the surface of a substrate by using a sputtering method, a vapor deposition method, or the like for an electrode material can be satisfactorily applied. Here, in the above-mentioned electrode frame, for example, a phosphor bronze plate or the like can be satisfactorily applied as the electrode material, and for example, an epoxy resin can be satisfactorily applied as the adhesive for adhering to the substrate. can. Further, in the above-mentioned electrode film, for example, titanium (Ti), an alloy containing titanium (Ti), or the like can be satisfactorily applied as the electrode material. Further, when the above-mentioned electrode film is applied as the electrode, a metal plating layer may be formed on the surface thereof by electrolytic plating.

In the present embodiment, as a method of impregnating the substrate of an electronic component with a resin solution, a method of immersing the substrate in a resin solution to vacuum impregnate the substrate and impregnating the entire surface of the substrate with the resin solution 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, rollers, brush coating, and potting can be satisfactorily applied. Then, by such a method, the resin solution can be satisfactorily impregnated on the entire surface of the substrate, or at least the electrode forming region. That is, by such a method, the surface of the electrode forming 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 pore portion inside the electrode forming region of the surface layer of the substrate is a layer made of the resin material. It can be partially filled.

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

Further, in the present invention, as yet another resin solution, for example, a solvent-free one-component inorganic pore-forming 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 satisfactorily. This type of inorganic pore-forming agent comprises an alkoxysilane compound or a partially hydrolyzed condensate thereof, an inorganic pigment, an inorganic additive, and a curing catalyst.

When such an inorganic pore-forming agent is used as a resin solution, the method of impregnating the substrate of an electronic component is as follows: First, the inorganic pore-forming agent and the substrate are defoamed in a vacuum for about 5 to 10 minutes. After the treatment, the inorganic pore-forming agent and the substrate are mixed in vacuum. Next, the vacuum state is released and the substrate is impregnated with the inorganic pore-sealing agent. After that, the substrate is deliquesed and left in a humid atmosphere for, for example, 24 hours, so that the inorganic pore-forming agent impregnated in the substrate can be satisfactorily cured.

(Verification of action and effect)
Next, the action and effect in 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 action and effect in the electrode forming method of the electronic component according to the present embodiment, as a comparison target, the substrate 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. Indicates the case where is not applied. Electronic components having a substrate made of ferrite are those that are already commercially available and mounted on various electronic devices, such as inductors, and have been subjected to various reliability tests such as adhesion strength. It has received high praise from the market.

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

As described above, since the metal powder molded body applied to the substrate of the electronic component according to the present embodiment is porous, it has a dense crystal structure as shown in FIGS. 3 (a) and 3 (b). Compared to well-known ferrite, it has a high water absorption rate and porosity. Specifically, in the substrate according to the present 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. It 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. 4 and 5.

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 via the oxide film. Therefore, relatively large pores exist between the metal powders from the surface of the substrate to the inside. On the other hand, as shown in FIG. 4B, the well-known ferrite substrate has a dense crystal structure, so that there are almost no pores inside the substrate. ..

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 is subjected to a baking treatment or a curing treatment to form glass in the pores. Alternatively, the resin permeates and fills, and at least the porosity on the surface or surface layer of the substrate is improved.

Next, the adhesion strength when the electrode is formed on the porous substrate will be verified.
FIG. 6 is a table showing the measurement results of the fixing strength when the method for forming electrodes of electronic components according to the first embodiment is applied, and FIG. 7 is a table showing the measurement results of the fixing strength when the method for forming electrodes of electronic components according to the second embodiment is applied. It is a table which shows the measurement result of the sticking strength when is applied.

First, a method for measuring the adhesion strength will be described.
First, an electrode was formed on the surface of the substrate, and the substrate was mounted on the substrate by solder-bonding the electrode onto a mounting land made of copper foil formed on, for example, a glass-epoxy resin substrate. Here, as a method of mounting the substrate on the substrate, after printing cream solder on the substrate, the substrate was mounted on the mounting land, heated to 245 ° C., and reflow soldered for mounting. Then, the substrate is pressed with the jig of the peel strength tester in a direction parallel to the upper surface of the substrate from the side surface of the substrate with respect to the substrate on which the substrate is mounted, the peel strength is measured, and this is used as the fixing strength. Evaluation was performed.

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

As shown in the first embodiment, a metal powder molded body 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, firing atmosphere; When the firing electrode was formed by firing in FIG. 6), the adhesion strength of the substrate was 291N. On the other hand, a metal powder molded body is applied as a substrate, and an electrode material made of copper (Cu) is fired under predetermined firing conditions (baking temperature, firing atmosphere; see FIG. 6) without performing a base treatment. When the fired electrode was formed, the adhesion strength of the substrate was 54N and 95N. That is, it was confirmed that the substrate according to the present embodiment has about three times or more the fixing strength as compared with 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, firing atmosphere; see FIG. 6) to form a firing electrode. The fixing strength of the substrate was 244N and 336N, respectively. That is, it was confirmed that the substrate according to the present embodiment has the same degree of fixing strength as that in the case where ferrite is applied.

Next, the adhesion 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 where the metal powder molded body is applied as the porous substrate, the presence or absence of the base treatment and the fixing strength, and the fixing strength when the metal powder molded body is applied as the substrate and when ferrite is applied. Verified.

As shown in the second embodiment, a metal powder molded body is applied as a substrate, an epoxy resin is impregnated as a base treatment, and a plate-shaped member made of phosphor bronze is coated with an epoxy resin adhesive. When bonded to form an electrode frame, the adhesion strength of the substrate was 141N. Similarly, when an electrode frame is formed by impregnating a plate-shaped member made of phosphor bronze with an epoxy resin adhesive as a base treatment, the adhesion strength of the substrate is It was 139N. On the other hand, when a metal powder molded body is applied as a substrate and a plate-shaped member made of phosphor bronze is adhered using an epoxy resin adhesive to form an electrode frame without performing a base treatment. The adhesion strength of the substrate was 69N. That is, it was confirmed that the substrate according to the present embodiment has approximately twice or more the fixing strength as compared with the case where the surface treatment is not performed.

Further, when ferrite was applied as the substrate and a plate-shaped member made of phosphor bronze was adhered using an epoxy resin adhesive to form an electrode frame, the adhesion strength of the substrate was 142 N. That is, it was confirmed that the substrate according to the present embodiment has the same degree of fixing strength as that in 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, the substrate is impregnated or coated with a glass or resin material and subjected to a base treatment of baking or curing before forming the electrode. And the resin material permeates and fills the pores of the porous substrate, so that the porosity of the surface or surface layer of the substrate is improved. As a result, it is possible to prevent the electrode material, adhesive (electrode bonding material), and the like from permeating into the substrate during electrode formation, and to prevent the substrate from deteriorating the bondability and adhesion between the substrate and the electrode. It is possible to realize the same adhesive strength as when applied to, and it is possible to contribute to the improvement of the reliability of the electronic device equipped with such an electronic component.

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

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 collar side), and FIG. 8B is a schematic perspective view of the electronic component according to the present application example. It is a schematic perspective view seen from the bottom surface side (lower collar 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 diagram showing a cross section of the electronic component along the line AA shown in FIG.

As shown in FIGS. 8 and 9, the electronic component according to the first application example is a winding inductor 10 having a drum core structure, and is a core member 11 and a coil conductor 12 wound around the core member 11. , A pair of terminal electrodes 16A and 16B to which the ends 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 periphery of the wound coil conductor 12. Have.

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

Further, as shown in FIGS. 8B and 9, a pair of terminals are placed 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 the region where the pair of terminal electrodes 16A and 16B are formed (electrode forming region), for example, as shown in FIGS. 8B and 9. It may be a thing.

As shown in FIG. 9, the coil conductor 12 is 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. Will be done. Then, the coil conductor 12 is wound around the columnar 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 formed. With the insulating coating 14 removed, the terminal electrodes 16A and 16B are electrically connected to the terminal electrodes 16A and 16B by solders 17A and 17B, respectively.

Here, in the coil conductor 12, for example, a coated conductor having a diameter of 0.1 to 0.2 mm is wound around the core portion 11a 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 conducting wire 12 is not limited to one having a circular cross-sectional shape, and for example, a flat wire having a rectangular cross-sectional shape, a square wire having a square cross-sectional shape, or the like may be used. You 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 depth of the grooves 15A and 15B. It is preferable to have.

Both ends 13A and 13B of the coil conducting wire 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 the above-described embodiments, and the electrode forming method shown in each of the above-described embodiments is used on the bottom surface 11B of the porous core member 11 which is the substrate. Is formed. That is, prior to the forming steps of the terminal electrodes 16A and 16B, the glass or resin permeates the pores of the porous core member 11 by performing a base treatment of impregnating or coating the glass or resin and baking or curing the glass or resin. At least on the surface or surface layer of the core member 11 in the electrode forming region, the porosity is improved. Here, as described above, the terminal electrodes 16A and 16B are a fired electrode obtained by applying an electrode paste to the electrode-shaped spine region of the core member 11 and firing at a predetermined temperature, or a conductive plate-shaped member. An electrode frame to be bonded using an adhesive and an electrode film obtained by forming a thin film of an electrode material by sputtering or vapor deposition can be applied.

When a fired electrode of copper (Cu) or silver (Ag) is applied as the terminal electrodes 16A and 16B, or when an electrode frame made of pure copper or phosphor bronze is applied, the core member 11 is used. 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 22 to 13%), ground, and baked. As a result, as shown in the above-mentioned verification of the action and effect, it is possible to realize a high adhesion strength between the core member 11 and the terminal electrodes 16A and 16B.

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 along the line BB shown in FIG. 10A. It is a figure which shows the cross section of. FIG. 11 is an exploded perspective view of the 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, which is provided at a rectangular parallelepiped component body 21 and both ends of the component body 21 in the length direction. It has a pair of terminal electrodes 24, 25 and the like.

As shown in FIGS. 10A and 10B, the component main body 21 has a rectangular parallelepiped-shaped magnetic material portion 22 and a spiral coil portion 23 covered with the magnetic material portion 22. 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 material portion 22 has a structure in which, for example, a total of 20 magnetic material layers ML1 to ML6 are laminated and integrated. Here, the magnetic material portion 22 corresponds to the substrate shown in each of the above-described embodiments, and is composed of a particle group of a soft magnetic alloy containing iron (Fe), silicon (Si), and chromium (Cr). A porous molded body is applied.

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

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

Similar to the coil portion 23, the pair of terminal electrodes 24 and 25 are mainly composed of, for example, a silver (Ag) particle group, and as shown in FIGS. 10A and 10B, the length direction of the component body 21 It is formed on each end face of the above and four side surfaces in the vicinity of the end face. Here, the terminal electrodes 24 and 25 correspond to the electrodes shown in the above-described embodiments, and the electrodes shown in the above-described embodiments are attached to both ends of the porous component body 21 which is the substrate in the length direction. It is formed using a forming method. That is, prior to the forming steps of the terminal electrodes 24 and 25, the glass or resin permeates the pores of the porous component body 21 by performing a base treatment of impregnating or coating the glass or resin and baking or curing the glass or resin. At least on the surface or surface layer of the component body 21 in the electrode forming region, the porosity is improved.

As described above, according to the above-mentioned application examples, in various inductors that can be surface-mounted on a circuit board, core members and components in which an electrode material, an electrode bonding material, an adhesive, or the like is a substrate at the time of electrode formation. It is possible to prevent the terminal electrodes from penetrating into the main body and deteriorating the bondability and adhesion of the terminal electrodes. Therefore, since it is possible to realize a high adhesion strength between the inductor substrate and the terminal electrode, it is possible to contribute to the improvement of the manufacturing yield and reliability of the electronic device equipped with such an inductor.

In the above-mentioned application example, 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 may be any other electronic component as long as the electrode is formed on the electronic component having a porous substrate by using an electrode material or an electrode bonding material. It can be applied well.

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, an electrode can be satisfactorily formed on the substrate, which is extremely effective.

10 Winding type inductor 11 Core member 11a Winding core part 11b Upper collar part 11c Lower collar part 12 Coil conductor 16A, 16B Terminal electrode 18 Exterior member 20 Laminated inductor 21 Part body 22 Magnetic material part 23 Coil part 24, 25 Terminal electrode S101 Glass slurry preparation process S102 Glass coating process S103 Binder removal process S104 Glass baking process S105 Electrode forming process S201 Resin solution preparation process S202 Resin impregnation process S203 Drying process S204 Curing process S205 Electrode forming process

Claims (4)

An electronic component with a porous substrate
The substrate has a layer made of a glass material on its surface layer, a part of the layer made of the glass material is impregnated in a pore portion of the porous substrate, and a layer made of the glass material is formed. An electrode material or an electrode containing the electrode material and an electrode bonding material is formed in a glass layer serving as an electrode forming region on the surface of the porous substrate.
The porous substrate is composed of soft magnetic alloy particles.
The pores are pores between the particles of the porous substrate, and
The porosity of the substrate is a porosity whose water absorption rate and porosity exceed the water absorption rate and porosity of the substrate made of ferrite.
The electrode is an electronic component characterized in that it is formed by firing the electrode material or the electrode material and the electrode bonding material. The pores of the substrate whose water absorption rate and porosity exceed the water absorption rate and porosity of the substrate made of ferrite are metal powders having a water absorption rate of 1.0% or more or a porosity of 10 to 25%. The electronic component according to claim 1, wherein the electronic component is a molded body of the above. The electronic component is composed of iron, silicon, and a group of soft magnetic alloy particles containing 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. The oxide layer is formed, and the oxide 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 via the oxide layer. The electronic component according to 1 or 2. The element that is more easily oxidized than iron is chromium.
The electronic component according to claim 3, wherein the soft magnetic alloy contains at least 2 to 15 wt% of chromium.

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