JP2958805B2 - Electronic components for surface mounting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a surface mounting electronic component provided in an electronic circuit of the present invention, and more particularly, to a laminated transformer and an in-phase type used in a high-frequency circuit and provided for surface mounting. The present invention relates to a surface mounting component such as an inductor.

[Prior Art] Conventionally, electronic parts for surface mounting such as multilayer transformers and in-phase inductors have been used in electronic circuits. This surface mount electronic component is composed of ferrite magnetic fine powder and an organic binder as a magnetic layer so that at least two linear or meandering conductors are exposed at the ends in a ferrite magnetic layer. A ferrite paste containing an organic solvent as a dispersion medium as a main material and a conductive paste containing a metal fine powder and an organic binder as a main material and a dispersion medium of an organic solvent as a conductor are formed into printed films, respectively. It is dried every time, laminated in a superimposed manner, and integrally sintered by a hot isostatic press or the like to obtain a sintered body. A film-shaped electrode terminal is provided on the end face of the sintered body to form an electronic component for surface mounting. In the conventional electronic components for surface mounting such as a laminated transformer and an in-phase type inductor formed as described above, the ferrite paste or the conductive paste is coated with a specular gloss (an incident angle of 60 ° −a reflection angle of 60 °) when the film is dried. ) Is 30% or less.

[Problems to be Solved by the Invention] However, in order to further improve the performance and reliability of the surface mount electronic component, the configuration of the conventional surface mount electronic component described above requires the paste dispersibility, the laminate, and the like. It has been found that there are various drawbacks in terms of the filling property of the powder and the density of the sintered body.

In other words, in order to achieve higher performance and higher reliability of electronic components for surface mounting, the paste dispersibility is improved, the filling rate of the laminate is increased, and the density of the sintered body is made as close as possible to the theoretical density. Although it is necessary to use the ferrite paste described above, the dispersibility of the ferrite paste is such that the specular gloss (incident angle 60 ° -reflection angle 60 °) of the surface of the ferrite paste during drying is 30% or less. Since it does not have this, the packing ratio of the laminate is low and the sintered density is about 90% of the theoretical density.
Even if the molding density was increased by means such as hot isostatic pressing in a subsequent process, open pores after firing could not be avoided. That is, when used as a surface-mounting electronic component in a severe environment such as high temperature and high humidity, a short circuit occurs between the conductor portions due to intrusion of moisture or the like, and the conductor portion is damaged by migration or corrosion. Alternatively, the insulation between the conductor phases deteriorates, and in the worst case, the wire may be disconnected or short-circuited, so that the reliability or the function as a surface mounting electronic component is lost.

In addition, in the conventional laminate, since the dispersibility at the time of the paste is insufficient, uniform filling of particles cannot be obtained, and even if densification is performed at a predetermined sintering temperature, uniform grain growth cannot be obtained. Grain growth itself tends to be insufficient.

Further, in the conductor using the conductive paste, there is a drawback that, similarly to the ferrite paste, the filling is insufficient and the DC resistance after sintering is higher than the theoretical value.

Therefore, a technical problem of the present invention is to eliminate the drawbacks of the conventional technology and to provide a surface mount electronic component such as a multilayer transformer and an in-phase inductor having high performance and high reliability even in a severe environment. is there.

[Means for Solving the Problems] According to the present invention, a surface-mounted electronic component in which a plurality of linear conductors is sandwiched between magnetic layers and at least one end of each conductor is exposed to the end face of the magnetic layer Wherein the magnetic layer is formed from a ferrite paste having a specular gloss of at least 40% on the surface when the film is dried, thereby obtaining an electronic component for surface mounting.

That is, in the present invention, by using the ferrite paste, the surface roughness formed by film formation and drying is reduced, and a highly filled laminate is formed. By performing densification while avoiding the open pores, which are points, it is possible to sufficiently secure 95% or more of the theoretical density.

Furthermore, according to the present invention, in the electronic component for surface mounting, the conductor portion has a high dispersion in which the mirror gloss (incident angle 60 ° -reflection angle 60 °) of the surface is 40% or more when the film is dried. An electronic component for surface mounting characterized by being formed from a conductive paste is obtained.

That is, in the present invention, by using the above-mentioned highly dispersed conductive paste, the filling rate of the conductor portion is improved, and the DC resistance value after sintering is smaller than that obtained by molding using the conventional conductive paste. The film thickness can be reduced by about 10% to 30%, and the surface roughness at the time of film formation can be considerably reduced, so that highly accurate film formation can be performed.

As described above, according to the present invention, even when the surface-mounting electronic component is used under severe conditions, the penetration of moisture or the like is sufficiently prevented, and the short-circuiting or migration or corrosion between the conductors causes It is possible to manufacture laminated surface mount electronic components with sufficiently improved characteristics, while fully preventing damage to the conductors, deterioration of insulation between conductor phases, disconnection, and short circuits. The present invention constitutes a surface-mounting electronic component which is sufficiently prevented and has improved industrial economy.

Hereinafter, embodiments of the electronic component for surface mounting according to the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an example of a configuration of a laminated transformer as a surface-mounting electronic component according to an embodiment of the present invention.
The figure is a cross-sectional view of the laminated transformer shown in FIG. 1, which is not connected for simplicity, but is made up of one component, and the conductors 12 and 13 are partially emphasized.

FIG. 3 is a perspective view showing a laminated body of the laminated transformer of FIG. 1, and FIG. 4 is an exploded view of the laminated body of FIG.

In FIG. 1, the laminated transformer according to the embodiment of the present invention has an electrode film on both end surfaces of a magnetic layer 11 formed of a high filling and high density ferrite paste.
It is baked as B ・ 32B.

Referring to FIG. 2, a laminated transformer according to an embodiment of the present invention includes a conductor layer formed of a conductive paste in a magnetic layer 11 formed of a highly filled and high density ferrite paste.
12 and 13 are provided.

With reference to FIG. 3 and FIG. 4, a method of manufacturing the laminated transformer according to the embodiment of the present invention will be described.

The conductor paste forming the conductor 13 is printed on a magnetic sheet 21 made of a highly filled, high density ferrite paste forming the magnetic layer 11 and then dried, and the high filling, high density ferrite paste is printed thereon. Film is dried and magnetic sheet
22, and the conductor 13 was further printed thereon and dried.
The upper part is covered with the same magnetic sheet 21 as the lower part, or a magnetic paste is printed, formed into a film, and dried to obtain a laminate 10 as shown in FIG.

When the laminate 10 is integrally sintered by a hot isostatic press or the like, a sintered body having the same shape as the laminate 10 is obtained. A first end is connected to the end face of the obtained sintered body so as to be connected to the end of the exposed electrode 12/13.
When the external electrodes 31A, 31B, 32A, 32B as shown in the figure are respectively baked, the electronic component 1 for surface mounting is obtained.

FIG. 5 shows a method for measuring the specular gloss of the paste constituting the magnetism and the conductor when the film is dried. As shown in FIG. 5, the specular glossiness is obtained by measuring the intensity of the reflection angle at a position where the incident angle is 60 ° −the reflection angle 60 ° with respect to the sample.

In the embodiment of the present invention, the magnetic layer 11 is made of a highly-filled and high-density magnetic layer 11 by using a highly dispersible ferrite paste having a surface gloss of 40% or more when the film is dried.
Are formed. This highly dispersible ferrite paste reduces the roughness of the molded surface by film formation and drying, forms a highly filled laminate, and densifies by subsequent sintering to achieve a theoretical density of 95%. % Can be sufficiently secured, and even when used in a harsh environment, the penetration of moisture or the like is sufficiently prevented, and the conductor is damaged due to a short circuit or migration or corrosion between the conductors, and the reliability as a device is increased. Can be sufficiently prevented.

In addition, the specular gloss of the surface (incident angle 60 °-reflected angle 60 °)
Is less than 40%, the surface roughness of the molded surface is reduced by film formation and drying, and the non-uniformity is based on the aggregation of primary particles in the paste and the uneven dispersion of the binder. Since coating and molding can be avoided and a high-filled and high-density laminate can be formed, open pores are sufficiently eliminated, and the distance between the conductors can be made extremely narrow as compared with the conventional one. Can be considerably improved as compared with the conventional one. In addition, since it is applied with uniform and high packing density, grain growth by sintering is uniform and promoted,
The sintering can be performed at a temperature of at least 10 to 50 ° C. lower than a predetermined sintering temperature, and industrial economics can be improved.

On the other hand, in the present invention, the conductive paste for forming the conductor portions 12 and 13 has a surface mirror gloss (incidence angle) when the film is dried.
Molded using a polymer conductive paste with a reflection angle of 60 °-60 °) of 40% or more, which reduces the DC resistance after sintering by about 10% to 30% compared to conventional products. Was completed.
Also, the surface roughness of the conductive paste during film formation is considerable,
Since it can be reduced, highly accurate film formation can be performed.

Therefore, it is possible to form a film with sufficiently high accuracy even on the complicated and fine conductor portions 12 and 13 as shown in the exploded view of FIG. 4, and it is possible to considerably reduce the surface roughness at the time of film formation. A film could be formed.

In the multilayer transformer according to the embodiment of the present invention, the specular glossiness (incident angle 60 ° −reflection angle)
A highly dispersed ferrite paste or conductive paste in which 60%) indicates 40% or more can be obtained by using a high-speed dispersing machine such as a homogenizer or a roll dispersing machine such as a three-roll mill as a general manufacturing method, as in the case of the ferrite paste. It can be easily manufactured using.

In addition, when the film is dried, the specular gloss of the surface (incident angle of 60
A highly dispersed ferrite paste or conductive paste having a {-reflection angle of 60%) of 40% or more is a high-rotation type dispersing machine such as a homogenizer or three rolls as a general manufacturing method, like the ferrite paste. Instead of using a roll dispersing machine, an example of a manufacturing method is to use a ferrite magnetic powder and an organic binder as main raw materials and an organic solvent as a dispersion medium such as a kneader or a planetary mixer. Pre-kneading using a stirrer with low rotation and large shear stress, and then using a stirrer with high rotation such as a bead mill and filling the container with beads with a diameter of about 0.1 to 3 mm to 60 to 90 vol%. It is manufactured by dispersing.

In the embodiment of the present invention, the method of forming a film using the ferrite paste or the conductive paste is not limited to a printing method, but may be a coating method, a doctor blade method, an extrusion molding method, an injection molding method, or any other manufacturing method. Does not change the effect of the present invention at all. Further, in the embodiment of the present invention, only the laminated transformer has been described as the surface mount electronic component. However, it is needless to say that the in-phase type inductor can be manufactured by the same manufacturing method.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a surface mounting electronic component having high performance and high reliability even in a severe environment.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a basic configuration of a multilayer transformer as an electronic component for surface mounting according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the multilayer transformer of FIG. 1, and FIG. FIG. 4 is a perspective view showing a laminated body of the laminated transformer shown in FIG. 4, FIG. 4 is an exploded view of the laminated body of FIG. 3, and FIG. FIG. In the figure, 1 ... Surface mount electronic component, 10 ... Laminated body, 11 ... Magnetic layer, 31A / 32A / 31B / 32B ... External electrode, 12/13 ... Conductor, 21/22 ... Magnetic Sheet.

Claims (2)

(57) [Claims] A plurality of linear conductor portions sandwiched between magnetic layers;
In a surface-mount electronic component in which at least one end of each conductor portion is exposed to an end face of the magnetic layer, the magnetic layer is formed from a ferrite paste having a surface glossiness of at least 40% when a film is dried. Electronic components for surface mounting. 2. The electronic component for surface mounting according to claim 1, wherein the conductor has a mirror gloss (incident angle of 60 ° −reflection angle of 60 °) of 40% or more when the film is dried. An electronic component for surface mounting, which is formed from a highly dispersed conductive paste.