JP4858568B2 - Manufacturing method of electronic parts - Google Patents

Description

  The present invention relates to a method for manufacturing an electronic component such as a coil component. More specifically, the present invention relates to an electronic component that can prevent chipping of a glass coating and the like and effectively prevent the surface of the component body from being exposed. It relates to a manufacturing method.

  With the miniaturization of coil components, the use of Mn—Zn cores from conventional Ni—Zn cores has been studied in order to obtain necessary characteristics. However, since the Mn—Zn core is conductive, an electrode cannot be provided directly on the surface of the core, and thus an insulating film needs to be provided on the surface of the core. Examples of the insulating film include glass and resin.

  In Patent Document 1, it is proposed to form a glass coating film on the surface of the core by a barrel coating method. However, it is said that the barrel coating method can form a uniform glass coating film, but the products may come into contact with each other and collide with each other, so that the glass coating film may be chipped. If the product is produced with the glass coating film missing, problems such as short circuit failure may occur. Therefore, there is a demand for a method for reliably suppressing chipping of the glass coating film.

  In addition, in order to increase the environmental resistance and insulation of electronic parts such as ferrite cores and varistors that are not conductive, a glass cured film formed by heat-treating a glass coating film as a protective film on the surface is used. There is a need for a method of forming a glass coating that can form and cover the entire surface of a component without causing chipping or the like.

JP 2001-237135 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a method for manufacturing an electronic component that can prevent chipping of a glass coating and the like, and can effectively prevent the surface of a component body from being exposed. It is to be.

In order to achieve the above object, a method for manufacturing an electronic component according to the present invention includes:
A step of applying a glass slurry containing glass powder, a binder and a solvent to the surface of the component body to form a glass coating film,
A step of curing the glass coating film,
When forming the glass coating film, a difference in coating film strength is provided in the film thickness direction of the glass coating film, and the strength of the glass coating film is closer to the surface than near the component main body in the stage before the curing treatment. The glass coating film is formed so as to be low.

  In the method for manufacturing an electronic component according to the present invention, the glass coating film (before the curing treatment) is formed so that the strength of the glass coating film is lower on the surface side than near the component main body. Therefore, when the glass coating film is formed, even if the products come into contact with each other and collide with each other, the surface of the glass coating film may become a sacrificial film and may be chipped, but the glass coating film near the component body remains. It will be. That is, in the method according to the present invention, even if the surface of the glass coating film is missing, the glass coating film near the component main body remains, and the surface of the component main body is hardly exposed. In addition, if the glass coating near the component body remains, the surrounding glass coating is softened due to the heat generated by the glass coating curing process, and the thin film is repaired. Thus, a glass cured film having a uniform film thickness can be obtained.

  The means for providing the coating film strength difference is not particularly limited, but preferably, when the glass coating film is formed, the glass contained in the glass slurry in the initial stage of coating and forming the glass coating film on the component main body. Compared with the concentration of the binder with respect to the powder, the concentration of the binder with respect to the glass powder contained in the glass slurry is set low at the end of coating and forming the glass coating, and the coating is applied in the film thickness direction of the glass coating. A film strength difference is provided. In this case, the binder concentration on the surface of the glass coating film becomes low, and after the curing treatment by firing the glass coating film, the glass cured film obtained from the glass coating film having a low binder concentration has a binder concentration. It is not brittle and has higher mechanical strength than a cured glass film obtained from a high glass coating film. In the present specification, unless otherwise specified, the binder resin concentration (binder concentration or binder resin content) is a concentration with respect to the glass powder. For example, the binder resin content of 10% means that the glass powder is 100 g and the binder resin is 10 g.

  Alternatively, when forming the glass coating film, compared to the binder contained in the glass slurry at an early stage of coating and forming the glass coating film on the component main body, the final stage of coating and forming the glass coating film You may provide a coating-film intensity | strength difference in the film thickness direction of the said glass coating film by changing the kind of the said binder contained in a glass slurry.

  Alternatively, when the glass coating film is formed, the glass coating film is applied and formed in comparison with the particle size of the glass powder contained in the glass slurry in the initial stage of applying and forming the glass coating film on the component body. The film strength difference may be provided in the film thickness direction of the glass coating film by reducing the particle size of the glass powder contained in the glass slurry at the final stage.

  Alternatively, when forming the glass coating film, compared to the glass powder contained in the glass slurry at the initial stage of coating and forming the glass coating film on the component body, at the final stage of coating and forming the glass coating film You may provide a coating-film intensity | strength difference in the film thickness direction of the said glass coating film by changing the kind of the said glass powder contained in the said glass slurry.

  Preferably, when forming the glass coating film, the type of the glass slurry is suddenly changed in the middle from the initial stage to the final stage of applying and forming the glass coating film on the component main body. By doing in this way, the coating strength changes rapidly, and the effect as a sacrificial film on the surface of the glass coating is improved.

  Preferably, the strength ratio by a scratch test showing the difference in coating strength is at least twice. By setting to 2 times or more, the effect as a sacrificial film in the surface of a glass coating film improves.

  The component main body is accommodated in a movable barrel, and the glass coating film is formed by spraying the glass slurry on the component main body in the barrel. By using the so-called spray barrel method, a uniform glass coating can be formed on a large amount of component bodies at once. That is, mass production becomes possible.

FIG. 1 is a schematic cross-sectional view of a barrel device used in a method for manufacturing an electronic component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a drum core processed by the barrel apparatus shown in FIG. FIG. 3 is a schematic cross-sectional view in which a first glass coating film is formed on the surface of the drum core shown in FIG. FIG. 4 is a cross-sectional view of a drum core in which a second glass coating film is formed on the surface of the first glass coating film. FIG. 5 is a cross-sectional view of the drum core after winding the coil. FIG. 6 is a graph showing the relationship between the coating film strength ratio and the substrate visible defect occurrence rate in the drum core according to the example of the present invention.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
First embodiment As shown in Fig. 1, a barrel apparatus 1 used in a method for manufacturing a coil component according to an embodiment of the present invention has a cylindrical or prismatic cylinder casing 1a, and is hollow. The barrel container 2 is accommodated in the interior of the casing so as to be rotatable around the axis in the direction of arrow A (or the opposite direction).

  In the casing 1a, an inlet pipe 3 and an outlet pipe 4 are formed on opposite sides of the casing 1a with the barrel container 2 interposed therebetween. From the inlet pipe 3, the drying gas can enter the casing 1 a and the outlet pipe 4 can discharge the air inside the casing.

  A spray nozzle 5 is disposed along the axial direction at the axial center position in the barrel container 2, and the slurry 6 is directed from the nozzle 5 toward a large number of core components 10 stored in the barrel container 2. Can be sprayed. Since the barrel container 2 rotates in the direction of arrow A, the core components 10 stored in the barrel container 2 are gathered in the rotational direction A side rather than directly below the barrel container 2 in the vertical direction, Stirring by rotation of 2.

  The nozzle 5 is capable of spraying the slurry 6 toward a set of core components 10 that are gathered biased toward the rotation direction A side rather than directly below the vertical direction of the barrel container 2. Note that the direction in which the slurry is sprayed from the nozzle 5 may be freely changed. A discharge pipe (not shown) is connected to the casing 1a located below the barrel container 2, so that excess slurry 6 can be discharged.

  The wall of the barrel container 2 is formed with a large number of holes communicating with the outside and the inside, and the slurry 6 stored below the casing 1a also enters the inside of the barrel container 2 and the slurry 7 The core component 10 can be immersed in Further, since the wall of the barrel container 2 is formed with a large number of holes communicating with the outside and the inside, the inside of the casing 1a is connected from the inlet pipe 3 formed in the casing 1a to the outlet pipe 4. The flowing drying gas is also circulated inside the barrel container 2.

  Next, a method for manufacturing a coil component using the barrel apparatus shown in FIG. 1 will be described. First, the core component 10 shown in FIG. 2 is prepared. The core component 10 of this embodiment is composed of a soft magnetic metal such as Mn—Zn ferrite and permalloy, and a conductive magnetic material such as metal dust, and has a drum core shape.

  The core component 10 includes a cylindrical or prismatic core portion 12 and a pair of flange portions 14 integrally formed on both sides along the axial direction of the core portion 12. The outer diameter of the flange portion 14 is larger than the outer diameter of the core portion 12, and a concave portion 16 surrounded by the flange portion 14 is formed on the outer periphery of the core portion 12. Thus, as shown in FIG. 5, the coil 30 is wound.

  In this embodiment, the outer diameter of the core part 12 is 0.6 to 1.2 mm, the axial width W of the core part 12 is 0.3 to 1.0 mm, and the outer diameter of the collar part 14 is 2.0 to 3.0 mm, the thickness of the flange portion 14 is 0.2 to 0.3 mm, and the depth D from the outer peripheral surface of the flange portion 14 to the outer peripheral surface of the core portion 12 is 0.5. -1.0 mm. And in this embodiment, D / W is 1 or more, Preferably it is 1.0-1.5. In addition, the shape of the collar part 14 may be a square, an octagon, or the like in addition to a circle.

  A large number of such core components 10 are accommodated in the barrel container 2 shown in FIG. 1, and only the slurry 6 is sprayed from the nozzle 5 first. At that time, the barrel container 2 is rotated, and the slurry 6 is sprayed from the nozzle 5 while stirring the core component 10.

  The slurry 6 includes glass powder, a binder resin, and a solvent. In this embodiment, the content of the binder resin with respect to the glass powder in the slurry 6 varies between the initial stage and the final stage, and is preferably 10 to 40% by weight, more preferably 15 to 25% by weight at the initial stage.

  Further, the content of the binder resin with respect to the glass powder in the slurry 6 is preferably 2 to 10% by weight, more preferably 3 to 8% by weight at the end of the coating step. This is because if the content of the binder resin is too small, the strength of the glass coating film is lowered, and if it is too high, the strength of the cured glass film after firing is lowered. The binder resin contained in the slurry 6 is preferably polyvinyl alcohol (PVA) or a modified product thereof.

  The method for switching the binder resin content relative to the glass powder contained in the slurry 6 is not particularly limited, but two or more types of slurry 6 having different binder resin contents are prepared, and the slurry is applied during spray coating. What is necessary is just to change 6 types. Alternatively, the glass powder may be gradually added to the slurry in order to gradually reduce the content of the binder resin with respect to the glass powder contained in the slurry 6.

  FIG. 3 shows a state in which the first glass coating film 6a formed at the initial stage of application is formed by the slurry 6 containing a relatively large amount of the binder resin with respect to the glass powder, and FIG. 4 shows the first glass coating film. The state by which the 2nd glass coating film 6b formed with the slurry 6 in which the quantity of binder resin with respect to glass powder is contained relatively little on the surface of 6a was formed is shown.

  The timing for switching the content of the binder resin with respect to the glass powder contained in the slurry 6 is determined by, for example, the film thickness t1 of the first glass coating film 6a and the film thickness t2 of the second glass coating film 6b. For example, when the total film thickness of the glass coating film 20 composed of the first glass coating film 6a and the second glass coating film 6b is t3, t1 / t3 is 1/8 to 1/2, and t2 / t3 is 1. The content of the binder resin in the slurry is switched so as to be / 2 to 7/8. The reason why t2 is larger than t1 is preferred because film thickness t2 having a small binder resin content provides better binder removal treatment and higher strength of the cured glass film after firing. The total film thickness t3 of the glass coating film 20 is preferably 2 to 30 μm. If it is too thin, the effect as a glass coating film is small, and if it is too thick, the stress becomes strong and the coating film may peel off and it is not economical.

  The softening temperature of the glass powder is preferably 800 ° C. or lower. The average particle diameter (median diameter) of the glass powder is not particularly limited, but is preferably 0.1 μm or more and 10 μm or less. Examples of the glass powder include amorphous glass powders such as lead borosilicate glass, bismuth borosilicate glass, zinc borosilicate glass, and crystallized glass powder among silica glasses.

  The solvent preferably contains water. The solvent may be 100% water, but when the contact angle between the surface of the glass powder and water is large, water-soluble alcohol such as ethanol, isopropyl alcohol (IPA), IBA (isobutyl alcohol), etc. is mixed in a certain ratio. Therefore, it is preferable to suppress aggregation and sedimentation of the glass powder.

  The softening point of the glass powder is preferably 300 ° C or higher and 800 ° C or lower. Thus, by using glass powder having a softening point of 800 ° C. or less, it becomes possible to narrow or eliminate the temperature range from the thermal decomposition temperature of the binder resin to the softening point of the glass. Therefore, it is preferable because the shape of the glass powder layer can be maintained while the temperature is raised to the softening point of the glass in the firing step. The reason why it is defined as 300 ° C. or higher is that the softening point of many glass powders is 300 ° C. or higher.

  While rotating the barrel container 2 shown in FIG. 1 and stirring the components 10 in the container 2, the slurry 6 is sprayed from the nozzles 5 to the components 10. The slurry 6 sprayed on the parts 10 covers the surface of each part 10, and excess slurry 6 is discharged through a pipe (not shown). Although the processing time which rotates the barrel container 2 and sprays the slurry 6 from the nozzle 5 to the components 10 is not specifically limited, For example, it is about 30 to 180 minutes.

  The temperature of the slurry 6 at the time of spraying is preferably 40 ° C. or more and 100 ° C. or less although it depends on the composition of the solvent. When using a solvent having a low boiling point, it is preferable to lower the temperature within the above temperature range.

  When the amount of the part 10 to be processed is small, a ball having a specific gravity and volume close to that of the part 10 may be thrown into the barrel container 2 as a medium to keep the amount of the medium and the part 10 constant.

  The glass coating film is simultaneously dried while spraying the slurry 6. A drying gas is poured into the casing 1 a from the inlet pipe 3 and discharged from the outlet pipe 4. As shown in FIG. 4, the glass coating film 20 which consists of the 1st glass coating film 6a and the 2nd glass coating film 6b which were apply | coated to the surface of the component 10 is dried. The drying gas used for the drying process is, for example, air having a temperature of 50 to 100 ° C. You may perform a drying process after completion | finish of spraying for 5 to 30 minutes, for example.

  The peripheral speed Vs1 when discharging the slurry 6 from the nozzle 5 is preferably 0.01 m / sec or more and 0.1 m / sec or less, preferably 0.01 m / sec or more and 0.08 m / sec or less, more preferably. It is 0.01 m / sec or more and 0.06 m / sec or less.

  As shown in FIG. 4, the glass coating film 20 which consists of the 1st glass coating film 6a and the 2nd glass coating film 6b is formed in the surface of the components 10 after a drying process. The ratio of the coating strength by the scratch test of the first glass coating film 6a to the second glass coating film 6b after the drying treatment is twice or more. By setting to 2 times or more, the effect (after-mentioned) as a sacrificial film in the 2nd glass coating film 6b improves.

  In the scratch test, a knife edge (design knife / Kokuyo HA-F30 spare blade) connected to a load cell is pressed against each glass coating film 6a, 6b formed on the surface of the core part for the test while vertically pressing the core. The scratch test is performed, and the force until the glass coating film is peeled off and the surface of the core part is exposed is measured by a load cell. For example, when the binder resin content is 5% by weight, the coating film strength is about 7N, whereas when the binder resin content is 25% by weight and 30% by weight, about 22N. become.

  After the drying process, the component 10 is taken out from the barrel container 2 and fired (cured). The firing conditions are determined according to the softening point of the glass powder contained in the glass coating film 20, and the glass coating film 20 is preferably fired at a temperature equal to or higher than the softening temperature of the glass powder. Specifically, the firing temperature is preferably 600 to 800 ° C., and the firing time is 5 to 30 minutes. After the glass coating film 20 is fired, it becomes a glass cured film 20 ′ (see FIG. 5). The thickness of the glass cured film 20 ′ is preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less after firing. is there. You may perform a binder removal process before baking.

  After that, as shown in FIG. 5, a pair of terminal electrodes 32 made of silver, titanium, nickel, chromium, copper, or the like is printed, transferred, or immersed on the end face of one of the flanges 14 in each core component 10. It is formed by sputtering, plating or the like. The terminal electrode 32 is insulated for the glass cured film 20 ′ even if the core component 10 is conductive.

  Thereafter, the wire 30 is wound around the core portion 12, and both ends of the wire are respectively connected to the terminal electrode 32 by thermocompression bonding, welding using an ultrasonic wave or a laser, a soldering method, and the like, thereby completing the coil component. . In FIG. 5, for ease of explanation, the first glass cured film 6 a ′ obtained by curing the first glass coating film 6 a and the second glass obtained by curing the second glass coating film 6 b. Although the cured film 6b ′ is drawn separately, after firing, the first glass cured film 6a ′ and the second glass cured film 6b ′ are integrated so as not to be distinguished. However, depending on firing conditions, bubbles generated during the binder removal process remain in the glass cured film, and the first glass cured film 6a ′ and the second glass cured film 6b ′ may be distinguished depending on the number and size of the bubbles. There are cases where it is turned on.

  In the method for manufacturing a coil component according to the present embodiment, the slurry 6 is sprayed onto the plurality of components 10 while moving the plurality of components 10 inside the barrel container 2 to form the glass coating film 20 on the surface of the components 10. Therefore, the glass coating film 20 can be formed almost uniformly on the surface of a large number of components 10 at a time. That is, mass production becomes possible.

  And in the manufacturing method of the coil components which concern on this embodiment, it is glass with the 2nd glass coating film 6b located in the surface of the glass coating film 20 rather than the 1st glass coating film 6a which has covered the core component 10 directly. The glass coating film 20 is formed so that the strength of the coating film 20 is low. Therefore, when the glass coating film 20 is formed, the second glass coating film b located on the surface of the glass coating film 20 becomes a sacrificial film and may be chipped even if the products contact and collide with each other. However, the first glass coating film 6a directly covering the core component 10 remains. Since the 1st glass coating film 6a contains many binder resin, it is excellent also in adhesiveness with the core component 10. FIG.

  That is, in the method according to the present embodiment, even if the second glass coating film 6b is missing, the first glass coating film 6a remains and the surface of the core component 10 is rarely exposed. Moreover, if the 1st glass coating film 6a remains, the surrounding 2nd glass coating film 2 will soften by the heat | fever by the hardening process of the glass coating film 20, and the thin part is repaired, and it is comparatively A cured glass film 20 ′ having a uniform film thickness (after baking treatment) is obtained.

  Moreover, in this embodiment, the binder density | concentration in the surface of the glass coating film 20 becomes low. Since the second glass coating film 6b having a low binder concentration is easily removed, the first glass cured film 6a obtained from the first glass coating film 6a having a high binder concentration after the glass coating film 20 is baked and cured. Compared to ', the second glass cured film 6b' obtained from the second glass coating film 6b having a low binder concentration is not brittle and has high mechanical strength. For example, in the first cured film 6a ′ obtained from the first glass coating film having a binder resin content of 30% by weight, the coating film strength by baking after baking is 10 N, whereas the binder resin content is In the second glass cured film 6b ′ obtained from the 5% by weight second glass coating film, the coating film strength by the scratch test after firing is as high as 35N.

Furthermore, in this embodiment, when forming the glass coating film 20, the kind of glass slurry is suddenly changed in the middle from the initial stage which apply | coats and forms the glass coating film 20 to the core component 10 to the last stage. By doing in this way, the change of the coating-film intensity | strength of the film thickness direction in the glass coating film 20 becomes rapid, and the effect as a sacrificial film in the 2nd glass coating film 6b improves.
Second embodiment

  In this embodiment, in order to provide a coating film strength difference between the first glass coating film 6a and the second glass coating film 6b of the glass coating film 20 shown in FIG. Since it is the same as that of 1st Embodiment except changing it in the middle of spray application, and there exists the same effect, the overlapping description is abbreviate | omitted.

  In this embodiment, for example, the molecular weight of the binder resin contained in the second glass coating film 6b is made smaller than that of the binder resin contained in the first glass coating film 6a. In general, when the molecular weight of the binder resin is large, the strength of the coating film by the slurry containing the binder resin is increased. However, if the molecular weight is too high, slurrying becomes difficult and spray coating tends to be difficult.

Therefore, the following combinations are preferable. That is, the binder resin contained in the first glass coating film is a polyvinyl alcohol (PVA) resin, and the binder resin contained in the second glass coating film is an ethyl cellulose resin or an acrylic resin.
Third embodiment

  In this embodiment, in order to provide a coating film strength difference between the first glass coating film 6 a and the second glass coating film 6 b of the glass coating film 20 shown in FIG. 4, the particle size of the glass particles contained in the slurry 6. Is the same as that of the first embodiment except that it is changed in the middle of spray application, and the same operational effects can be obtained, so that redundant description is omitted.

In this embodiment, for example, by reducing the particle size of the glass particles contained in the second glass coating film 6b as compared with the particle size of the glass particles contained in the first glass coating film 6a, A strength difference is produced in the film thickness direction, and the coating strength of the inner surface can be increased with respect to the outer surface of the glass coating 20. For example, the particle diameter of the glass particles contained in the first glass coating film 6a is 0.8 to 1.2 μm, and the particle diameter of the glass particles contained in the second glass coating film 6b is 0.3 to 0.7 μm. Is preferred.
Fourth embodiment

  In this embodiment, in order to provide a coating film strength difference between the first glass coating film 6a and the second glass coating film 6b of the glass coating film 20 shown in FIG. Since it is the same as that of the first embodiment except that it is changed in the middle of spray application, and exhibits the same function and effect, overlapping description is omitted.

  In this embodiment, for example, the glass coating film is selected by selecting the glass particles contained in the second glass coating film 6b having a lower strength than the glass particles contained in the first glass coating film 6a. Thus, a strength difference can be produced in the film thickness direction of 20, and the coating strength of the inner surface can be increased relative to the outer surface of the glass coating 20.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, in the above-described embodiment, the drying process is performed while spraying the first glass coating film 6a or the second glass coating film 6b. However, after the first glass coating film 6a is formed, the drying process is performed, and then Alternatively, the second glass coating film 6b may be formed and dried. Or you may perform a drying process, after forming the 1st glass coating film 6a and the 2nd glass coating film 6b continuously by spray application. Moreover, you may form other glass coating films or coating films other than glass between the 1st glass coating film 6a and the 2nd glass coating film 6b, and on the surface of the 2nd glass coating film 6b. Other glass coating films may be formed. Furthermore, in the above-described embodiment, the boundary between the first glass coating film 6a and the second glass coating film 6b is clear before firing, but it is not always necessary to be clear. When the amount of the binder resin with respect to the glass powder in the slurry gradually changes, the boundary between the first glass coating film 6a and the second glass coating film 6b is not necessarily clear.

  Further, the component body processed by the method of the present invention is not limited to the core component 10 of the coil component, but may be a core of an inductive device such as a transformer. The material of the core is not particularly limited, and may be made of, for example, ferrite, alumina, iron, or the like. Furthermore, the parts processed by the method of the present invention may be ceramic multilayer chip parts such as varistors, thermistors, capacitors and coils, Nd-Fe based metal magnets, and the like.

  In the present invention, the solvent in the slurry for forming the second glass coating film 6b does not include water, and water-insoluble ethyl cellulose or the like may be used as the binder resin. Thereby, it is possible to prevent the water-soluble binder resin (PVA) of the first glass coating film 6a from eluting into the second glass coating film 6b.

  Furthermore, in the above-described embodiment, the glass cured film 20 ′ is used as an insulating film, but it can be used for other purposes, for example, as a buffer film. By attaching the buffer film, when the component 10 is hard, wear of a tool that handles the component 10 can be reduced. Further, the glass cured film 20 ′ may be used as a film for protecting the component 10.

Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.
Example 1

  A barrel apparatus 1 having an outer diameter of 200 mm of the barrel container 2 shown in FIG. 1 was prepared, and a glass coating film was formed on the core component 10 shown in FIG. The core component 10 was made of Mn—Zn ferrite, and the diameter of the flange 14 was 3 mm, the thickness of the jaw 14 was 0.25 mm, the dimension D was 0.8 mm, and the dimension W was 0.6 mm.

  First, glass powder having a softening point of 645 ° C. and an average particle diameter of 0.5 μm was prepared, and the glass powder and polyvinyl alcohol resin were mixed at a predetermined weight ratio. Furthermore, the obtained solid component (a mixture of glass powder and polyvinyl alcohol) and a solvent were mixed at a predetermined weight ratio, and stirred by a ball mill for 16 hours to prepare a first slurry. As the solvent, a mixture of water and ethanol at 8: 2 was used. The ratio of the glass powder to the whole slurry in the first slurry was 5% by weight. The content of the binder resin in the first slurry was 20% by weight with respect to the glass powder.

  Further, a glass powder having a softening point of 645 ° C. and an average particle diameter of 0.5 μm was prepared, and the glass powder and the polyvinyl alcohol resin were mixed at a predetermined weight ratio. Further, the obtained solid component (a mixture of glass powder and polyvinyl alcohol) and a solvent were mixed at a predetermined weight ratio, and stirred for 16 hours with a ball mill to prepare a second slurry. As the solvent, a mixture of water and ethanol at 8: 2 was used. The ratio of the glass powder to the whole slurry in the second slurry was 5% by weight. The content of the binder resin in the second slurry was 5% by weight with respect to the glass powder.

  Next, 900 g of the component 10 is put into the barrel container 2 of the barrel apparatus 1 shown in FIG. 1, and the surface of the component 10 is first subjected to spraying using the first slurry described above, and the film thickness t1 is 10 μm. 1 glass coating film 6a was formed. Then, the 2nd glass coating film 6b whose film thickness t2 is 10 micrometers was formed by the spray process using a 2nd slurry. The total film thickness t3 of the glass coating film 20 was 20 μm. The rotation speed of the barrel container 2 was 5 rpm (circumferential speed 0.05 m / s), and the slurry discharge amount and coating time were appropriately adjusted. Simultaneously with the spray treatment, drying treatment was performed at a hot air temperature of 70 ° C.

Thereafter, the part 10 was taken out from the barrel container 2, and the obtained part 10 was fired at 680 ° C. for 1 hour. About 1000 parts 10, the number of parts 10 having a defect (substrate visible defect) in which the surface of the core part 10 in the glass coating film 20 was visually observed was examined. The occurrence rate of the parts 10 with the substrate visible defect was 0.0%. In addition, the ratio of the coating strength (before firing) of the first glass coating film to the second glass coating film by the scratch test was 2.9 times and more than twice.
Comparative Example 1

  Except that the first glass coating film having the total film thickness t3 = 20 μm was formed on the surface of the core component 10 by using only the first slurry without using the second slurry, The core component 10 was produced, and the occurrence rate of the substrate visible defect was examined. The occurrence rate of the parts 10 with the substrate visible defect was 3.0%.

Moreover, when the coating strength of the 1st glass coating film by a scratch test was investigated in the state before baking, it was 22N. Moreover, after baking, when the coating strength of the 1st glass cured film by the scratch test was investigated, it was 25N.
Comparative Example 2

  In the same manner as in Example 1 except that the second glass coating film having a total film thickness t3 = 20 μm was formed on the surface of the core component 10 by using only the second slurry without using the first slurry. The core component 10 was produced, and the occurrence rate of the substrate visible defect was examined. The occurrence rate of the parts 10 with the substrate visible defect was 32.1%.

Moreover, when the coating strength of the 1st glass coating film by a scratch test was investigated in the state before baking, it was 7.5N. Moreover, after baking, when the coating strength of the 1st glass cured film by the scratch test was investigated, it was 35N.
From Comparative Example 1 and Comparative Example 2, it was found that the higher the strength of the glass coating film before firing, the lower the incidence of substrate-visible defects. However, even in Comparative Example 1 having a high coating film strength, the substrate-visible defect could not be 0.0% as in Example 1. By reducing the coating strength on the surface side, the glass coating on the surface side worked as a sacrificial film, and the surface visible defects could be remarkably reduced.
Moreover, after baking, the film strength of the 1st glass coating film obtained from the 2nd slurry with a low binder density | concentration was able to be made higher than the 2nd glass cured film obtained from a 1st slurry.
Example 2

A plurality of core components 10 are formed in the same manner as in Example 1 except that the content of the binder resin in the first slurry is 20% by weight and the content of the binder resin in the second slurry is 8% by weight. Fabricated and examined the incidence of substrate-visible defects. The occurrence rate of the parts 10 with the substrate visible defect was 0.0%. Moreover, the ratio of the coating strength (before firing) of the first glass coating film to the second glass coating film by the scratch test was 2.2 times and more than twice.
Example 3

A plurality of core components 10 are formed in the same manner as in Example 1 except that the content of the binder resin in the first slurry is 20% by weight and the content of the binder resin in the second slurry is 10% by weight. Fabricated and examined the incidence of substrate-visible defects. The occurrence rate of the parts 10 with the substrate visible defect was 0.1%. Moreover, the ratio of the coating strength (before firing) of the first glass coating film to the second glass coating film by the scratch test was 1.8 times, which was smaller than twice.
Example 4
A plurality of core components 10 are formed in the same manner as in Example 1 except that the content of the binder resin in the first slurry is 20% by weight and the content of the binder resin in the second slurry is 12% by weight. Fabricated and examined the incidence of substrate-visible defects. The occurrence rate of the parts 10 with the substrate visible defect was 0.8%. Moreover, the ratio of the coating strength (before firing) of the first glass coating film to the second glass coating film by the scratch test was 1.5 times.
Example 5
A plurality of core components 10 are formed in the same manner as in Example 1 except that the content of the binder resin in the first slurry is 20% by weight and the content of the binder resin in the second slurry is 15% by weight. Fabricated and examined the incidence of substrate-visible defects. The occurrence rate of the parts 10 with the substrate visible defect was 2.2%. Further, the ratio of the coating strength (before firing) of the first glass coating film to the second glass coating film by the scratch test was 1.2 times.
As shown in FIG. 6, from Examples 2 to 5, if the coating strength ratio is 1.5 times or more, the occurrence rate of the substrate visible defects can be suppressed to 1.0% or less, which is 2 times. If it is more than it, it was further more preferable and it has confirmed that it was 0.0%.
Comparative Example 3

A plurality of core components 10 are formed in the same manner as in Example 1 except that the content of the binder resin in the first slurry is 5% by weight and the content of the binder resin in the second slurry is 20% by weight. Fabricated and examined the incidence of substrate-visible defects. The occurrence rate of the parts 10 with the substrate visible defect was 30.2%. Further, the ratio of the coating strength of the first glass coating film to the second glass coating film by the scratch test (before firing) was 0.3 times and smaller than 1.
Example 6

  The type of the binder contained in the slurry 6 is changed during the spray coating, the particle size of the glass particles contained in the slurry 6 is changed during the spray coating, or the glass particles contained in the slurry 6 Even when the type of was changed during spray application, the same results as in Examples 1 to 5 could be confirmed.

DESCRIPTION OF SYMBOLS 1 ... Barrel apparatus 1a ... Casing 2 ... Barrel container 3 ... Inlet pipe 4 ... Outlet pipe 5 ... Spray nozzle 6 ... Slurry 6a ... 1st glass coating film 6a '... 1st glass cured film 6b ... 2nd glass coating film 6b' ... 2nd glass cured film 10 ... Core component 12 ... Core part 14 ... Gutter part 16 ... Concave part 20 ... Glass coating film

Claims (7)

A step of applying a glass slurry containing glass powder, a binder and a solvent to the surface of the component body to form a glass coating film,
A step of curing the glass coating film,
When forming the glass coating film, a difference in coating film strength is provided in the film thickness direction of the glass coating film, and the strength of the glass coating film is closer to the surface than near the component main body in the stage before the curing treatment. The glass coating is formed so that the
When forming the glass coating film, the glass coating film is applied and formed in comparison with the concentration of the binder with respect to the glass powder contained in the glass slurry in the initial stage of coating and forming the glass coating film on the component main body. A method for producing an electronic component, characterized in that at the end of the step, the binder concentration relative to the glass powder contained in the glass slurry is set low, and a coating strength difference is provided in the film thickness direction of the glass coating . When forming the glass coating film, compared with the binder contained in the glass slurry at the initial stage of coating and forming the glass coating film on the component main body, the glass slurry at the final stage of coating and forming the glass coating film wherein by changing the kind of the binder, a method of manufacturing an electronic component according to claim 1, characterized in that providing a film strength difference in the thickness direction of the glass coating contained. When forming the glass coating film, compared to the particle size of the glass powder contained in the glass slurry at the initial stage of coating and forming the glass coating film on the component body, the final stage of coating and forming the glass coating film the particle size of the glass powder contained in the glass slurry by the smaller, the electronic component according to claim 1 or 2, characterized by providing a film strength difference in the thickness direction of the glass coating film Production method. When the glass coating film is formed, the glass is coated at the final stage of coating and forming the glass coating film compared to the glass powder contained in the glass slurry at the initial stage of coating and forming the glass coating film on the component body. The manufacturing of the electronic component according to any one of claims 1 to 3 , wherein a coating film strength difference is provided in a film thickness direction of the glass coating film by changing a type of the glass powder contained in the slurry. Method. In forming the glass coating, on the way from the initial period to the final period of applying forming the glass coating to the component body, suddenly, to any one of claims 1 to 4, changing the type of the glass slurry The manufacturing method of the electronic component of description. Method of manufacturing an electronic component according to any of the coating strength difference claims 1-5 intensity ratio is more than twice that shown. The component body is accommodated in a movable within the barrel, by spraying the glass slurry to the component body in the barrel, the electronic component according to any one of claims 1 to 6 forming the glass coating Manufacturing method.

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