JP2979065B2 - Electronic components for surface mounting - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mounting electronic component used for an electronic circuit, and more particularly, to a laminated transformer and an in-phase type used for a high-frequency circuit and used for image mounting. The present invention relates to electronic components for surface mounting such as inductors.

[Prior Art] Conventionally, a surface mount electronic component 70 as shown in a perspective view of FIG. 7 has been used. FIG. 8 shows a sectional view of FIG. In FIG. 8, the surface-mounting electronic component 70 is formed such that at least two linear or meandering conductors 12 and 13 are formed in the ferrite magnetic layer 14 with the ends exposed. A ferrite paste containing a ferrite magnetic fine powder and an organic binder as the main raw materials and an organic solvent as a dispersion medium, and a conductor 82 and 83 containing a metal fine powder and an organic binder as the main raw materials and an organic solvent as a dispersion medium. Each of the conductive pastes is formed into a printed film, dried each time it is printed, laminated by superposition, molded into a laminate 90 shown in FIG. 9, and then integrally sintered by a hot isostatic press or the like. , And a sintered body having the same shape as the laminated body 90. As shown in FIG. 7, a conductor 82 having the film-shaped electrode terminals 71A, 71B, 72A, 72B exposed on the end face of the sintered body.
And 83 are provided so as to cover the surface mount electronic component 70. The conventional surface-mounted electronic components 70 such as the laminated transformer and the in-phase inductor formed as described above have a specular gloss (incident angle 60 ° -reflection angle 60 °) of 30% when the ferrite paste is formed and dried. A dispersant having the following degree was used.

In the case where a surface-mounted electronic component is formed of a highly filled and high-density magnetic layer, the ferrite paste has a specular gloss (incident angle of 60 ° −reflection angle) on its surface when the film is dried.
60%) generally represents more than 40% of the total. Further, the conductive paste has a dispersive property such that the specular gloss (incident angle 60 ° -reflection angle 60 °) of the surface during film formation drying is 30% or less, and generally constitutes the whole. It was used a lot.

[Problems to be Solved by the Invention] However, in order to further improve the performance and reliability of the surface-mounted electronic component, the above-described configuration of the conventional surface-mounted electronic component requires the dispersibility of the paste and the laminate. 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-mounted electronic component in a harsh environment such as high temperature and high humidity, a short circuit occurs between the conductors 82 and 83 due to intrusion of moisture or the like, or the conductor In the worst case, the wires 82 and 83 may be damaged or the insulation between the conductors 82 and 83 may deteriorate. In the worst case, the wires may be disconnected or short-circuited. Was.

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

When the entire magnetic layer 14 is composed of a highly filled and high density magnetic layer, the surface of the ferrite paste has a specular gloss (incident angle 60 ° −reflection angle 60 °) of 40 when the film is dried.
% Or more, the sheet method, which is a general manufacturing method, is taken as an example, but cracks are generated during sheet forming, and the flexibility of the sheet itself is lost. From the viewpoint of cost, the ferrite paste uses a high-dispersion ferrite paste of 40% or more as a whole when the film has a specular gloss (incident angle 60 ° -reflection angle 60 °) of 30% or less when the film is dried. Doing so has the disadvantage of being industrially disadvantageous. Furthermore, in the conductors 82 and 83 using the conductive paste, as in the case of the ferrite paste forming the magnetic layer, the filling is insufficient and the DC resistance after sintering shows a value higher than the theoretical value. was there.

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 at least the magnetic layer between the plurality of conductors of the magnetic layer is formed of a ferrite paste having a surface glossiness of at least 40% when the film is dried. Parts are obtained.

According to the present invention, in the electronic component for surface mounting,
The conductor portion is formed of a highly dispersed conductive paste having a surface glossiness (incidence angle 60 ° -reflection angle 60 °) of 40% or more when the film is dried. Electronic components are obtained.

That is, in the present invention, as the conductive paste, the specular gloss (incident angle 60 ° −reflection angle 60
The use of a dispersive conductive paste whose i) is 40% or more improves the filling rate of the conductor, and the DC resistance after sintering is 1% lower than that of the conductive paste.
Since it can be reduced by about 0 to 30% and the surface roughness at the time of film formation can be considerably reduced, highly accurate film formation can be performed. Further, the magnetic layer between the conductors or the magnetic layer in which the conductors are embedded is a highly dispersed ferrite exhibiting a specular gloss (incident angle 60 ° -reflection angle 60 °) of 40% or more when the film is dried. By using the paste, the surface is made of a highly filled and high-density magnetic layer, and further, around the conductor or the highly filled and high-density magnetic layer around which the conductor is buried, a mirror gloss of the surface when the film is dried Degrees (incident angle
60 °-reflection angle 60 °) is composed of a normal magnetic layer formed using a ferrite paste that shows 30% or less. Therefore, even when used in a harsh environment such as intense high temperature and high humidity, the conductor portion While sufficiently preventing the phenomenon of damage to conductors, deterioration of insulation between conductor layers, disconnection or short-circuit due to short-circuiting, migration or corrosion between conductors, the characteristics are sufficiently improved and the number of processes and cost are extremely low. This makes it possible to form a laminated transformer that is advantageous to the conventional technology, and to sufficiently prevent the drawbacks of the prior art, thereby constituting an electronic component for surface mounting with 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 sectional view showing a basic configuration of a laminated transformer as a surface mount electronic component according to a first embodiment of the present invention. For the sake of simplicity, it is not a connected shape, but one component, and the conductors 82 and 83 are partly highlighted.

Referring to FIG. 1, a laminated transformer according to a first embodiment of the present invention has a conductive paste of conductors 82 and 83 and a magnetic layer between the conductors 82 and 83 formed of a high filling and high density ferrite paste. Other than that, it is formed by the same method as the conventional example. That is, a conductor paste forming the conductor portion 13 is printed and formed on a magnetic sheet forming the magnetic layer 14 and dried, and a high filling and high density ferrite paste is printed thereon, formed and dried. Further, the conductor portion 13 is printed and formed into a film and dried, and the conductive portion 13 is covered with a magnetic sheet, or a magnetic paste is printed and formed into a film and dried, and the obtained laminate 10 is subjected to hot isostatic pressing or the like. The sintered body is integrally sintered. The resulting sintered body has the same appearance as the laminate 90 shown in FIG. 9, and its cross section is the same as that of the laminate 10 shown in FIG.

When external electrodes are provided on both end surfaces of the sintered body, a surface mounting electronic component having the same appearance as that of the conventional example shown in FIG. 7 can be obtained.

FIG. 5 shows a method for measuring the specular gloss of the paste constituting the magnetic layer and the conductor when the film is dried.

As shown in FIG. 5, the specular glossiness is obtained by measuring the intensity of the reflected light at a position where the incident angle is 60 ° −the reflection angle 60 ° with respect to the sample.

In the first embodiment of the present invention, a highly-filled and high-density magnetic layer 15 is formed by using a highly dispersible ferrite paste having a surface specular gloss of 40% or more when the film is dried. In addition, the conductor layer 82 and the magnetic layer around the conductor section 83 have a specular glossiness on the surface (incident angle 60 ° -reflection angle 60 °).
Is composed of a magnetic layer 14 formed by using a ferrite paste showing 30% or less.

Therefore, even when used in a harsh environment, the penetration of moisture and the like is sufficiently prevented, and the conductors 82 and 83 are damaged or the conductors 82 and 83 are damaged by a short circuit or migration or corrosion between the conductors 82 and 83. While fully preventing the phenomenon of insulation deterioration, disconnection, or short-circuit, it also prevents defects such as cracks occurring during sheet formation and operability due to the lack of flexibility of the sheet itself. It is possible to form a laminated transformer which is very advantageous in terms of number and cost.

FIG. 2 shows a second embodiment of the present invention, and the basic configuration is the same as that of the multilayer transformer according to the first embodiment of FIG. FIG. 6 is an exploded perspective view of the laminated transformer of FIG.

As shown in FIG. 6, a magnetic sheet 21 for forming a magnetic layer
A meandering conductor 83 is superimposed and printed thereon, and then a high-fill / high-density magnetic layer 24 is superimposed and printed thereon.
Is superimposed and printed, and finally the same magnetic sheet 21 as the magnetic layer 21 is printed.
To form a laminated body, and after integrally sintering the laminated body using a hot isostatic press or the like, an external electrode is applied to the end to form a laminate.

In the second embodiment, the conductive paste for forming the conductor portions 12 and 13 has a surface mirror glossiness (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. 6, and it is possible to considerably reduce the surface roughness at the time of film formation. A film could be formed.

FIG. 3 is a sectional view showing a laminated transformer as a surface mounting electronic component according to a third embodiment of the present invention, which is formed in the same manner as in the first and second embodiments. Conductor part 12
The magnetic layer between the 13 and around the conductors 12 and 13 has a specular gloss (incidence angle 60 °-reflection angle 60)
The high-density magnetic layer 34 is formed by embedding a pair of conductors 12 and 13 by using a high-dispersion ferrite paste whose i) shows 40% or more. further,
When the magnetic layer around the highly filled and high-density magnetic layer 34 is deposited and dried, the mirror gloss of the surface (incident angle 60 ° -reflection angle 60 °) is reduced.
It is formed using a ferrite paste showing 30% or less.

Even if the magnetic layer 31 is used in a harsh environment such as severe high temperature and high humidity, the conductors 12 and 13 may be damaged or the conductors 12 and 13 may be damaged due to a short circuit or migration or corrosion between the conductors 12 and 13. It is possible to form a surface-mounting electronic component that has sufficiently improved characteristics and is very advantageous in terms of the number of steps and cost, while sufficiently preventing the phenomenon of insulation deterioration between phases, disconnection or short circuit.

FIG. 4 shows an electronic component for surface mounting according to a fourth embodiment of the present invention. The basic configuration is a laminated transformer similar to that of the third embodiment. That is, as shown in FIG. 4, the high-fill / high-density magnetic layer 44 is printed on the entire surface of the magnetic layer 41 so that the high-fill / high-density magnetic layer 44 sandwiches the conductors 12 and 13 and dried. Are formed by sandwiching the conductors 12 and 13 and sintering the same during the process of repeating the above, and applying external electrodes to the end surfaces.

In the case of the laminated transformer shown in FIG. 4, the specular glossiness of the surface of the laminated transformer during drying (incident angle 60 ° -reflection angle 60 °)
High-dispersion ferrite paste or conductive paste, which shows 40% or more,
It can be easily produced using a high-rotation disperser such as a homogenizer or a roll disperser such as a three-roll as a general production method.

In addition, when the film is dried, the specular gloss of the surface (incident angle of 60
High-dispersion 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 a three-roll disperser as a general production method, like the ferrite paste described above. Instead of using a roll-type dispersing machine such as the one described above, an example of the manufacturing method is a kneader or a planetary mixer using ferrite magnetic powder and an organic binder as main raw materials and an organic solvent as a dispersion medium. Pre-kneading using a stirrer with low rotation and large shear stress, etc., and then using a stirrer with high rotation such as a bead mill and filling the container with beads with diameter of about 0.1 to 3 mm to 60 to 90 vol%. It is manufactured by performing high dispersion.

In the first to fourth embodiments of the present invention, the method of forming a film using the ferrite paste or the conductive paste may be a coating method, a doctor blade method, an extrusion molding method, an injection molding method or the like in addition to the printing method. It should be added that the effect of the present invention does not change at all regardless of the manufacturing method. In the first to fourth embodiments of the present invention, a multilayer transformer has been described as an electronic component for surface mounting. However, an in-phase inductor can be manufactured by a similar 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 cross-sectional view showing an example of a basic configuration of a laminated transformer as a surface mount electronic component according to a first embodiment of the present invention.
FIG. 3 is a sectional view showing a surface mounting electronic component according to a second embodiment of the present invention, FIG. 3 is a sectional view showing a surface mounting electronic component according to a third embodiment of the present invention, and FIG. FIG. 5 is a cross-sectional view showing a surface mounting electronic component according to a fourth embodiment of the present invention, FIG. 5 is a diagram showing a method for measuring specular gloss, and FIG. 6 is an exploded perspective view of the surface mounting electronic component of FIG. FIG. 7 is a perspective view showing a conventional surface-mounting electronic component, FIG. 8 is a cross-sectional view of the conventional surface-mounting electronic component, and FIG. 9 is a diagram showing a laminate of the surface-mounting electronic component in FIG. It is a perspective view which shows a structure. In the figure, 10, 20, 30, 40, 90 …… Laminated body, 11, 21, 31, 41…
… Magnetic layer, 15, 24, 34, 44 …… Highly filled, high density magnetic layer, 70
...... Surface mount electronic components, 71A / 71B / 72A / 72B ... Electrode terminals.

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 is exposed to an end face of the magnetic layer, at least a magnetic layer between the plurality of conductors among the magnetic layers has a specular gloss of a surface when a film is dried. Is formed from a ferrite paste showing at least 40%. 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.