The present invention relates to an electronic component and a manufacturing method thereof and, more particularly, to an electronic component having a magnetic resin layer embedded with a passive element part and a manufacturing method therefor.
A general electronic component often has a structure in which a passive element part is formed on the surface of a base and covered with an insulating material. As described in JP 2011-14747 A, some electronic components requiring high magnetic characteristics, such as coil components, use a magnetic material such as ferrite as the base and a magnetic resin as the insulating material for covering the passive element part. With this configuration, a closed magnetic path is formed by the base and magnetic resin layer, thereby making it possible to obtain high magnetic characteristics.
However, the magnetic resin includes a magnetic filler such as metal magnetic particles, so that it is larger in surface roughness and thus lower in smoothness than a general insulating resin. Thus, in an electronic component of the type described in JP 2011-14747 A in which the magnetic resin layer and the mounting substrate face each other, flow of underfill for filling a gap between the mounting substrate and the electronic component may be blocked.
It is therefore an object of the present invention to provide an electronic component having a magnetic resin layer embedded with a passive element part and in which underfill easily flows. Another object of the present invention is to provide a manufacturing method of such an electronic component.
An electronic component according to the present invention includes: a base; a passive element part formed on the main surface of the base; a magnetic resin layer formed on the main surface of the base so as to embed the passive element part therein and having a surface extending parallel to the main surface of the base; an insulating coat layer formed on a first area of the surface of the magnetic resin layer and having higher smoothness than the surface of the magnetic resin layer; and a terminal electrode formed on a second area of the surface of the magnetic resin layer and connected to the passive element part.
According to the present invention, the insulating coat layer having high smoothness is formed on the surface of the magnetic resin layer, so that when underfill is supplied to a gap between the mounting substrate and the electronic component which has been mounted on the mounting substrate such that the magnetic resin layer faces the mounting substrate, the underfill can be made to easily flow in the gap. In addition, the terminal electrode is formed on the surface of the magnetic resin layer having large surface roughness, so that adhesion of the terminal electrode is enhanced by anchor effect.
In the present invention, the insulating coat layer may contain insulating resin. This allows an insulating coat layer having high smoothness to be formed by a low-cost process such as a screen printing method. In this case, the insulating coat layer may further contain inorganic filler. This can reduce the thermal expansion coefficient of the insulating coat layer.
In the present invention, the magnetic resin layer may contain metal magnetic particles. This can significantly enhance the permeability of the magnetic resin layer.
In the present invention, the surface of the magnetic resin layer may not be exposed, that is, may be completely covered with the terminal electrode and the insulating coat. With this configuration, the entire surface of the magnetic resin layer having low smoothness is covered, thus making it possible to enhance the flowability of underfill.
In the present invention, the magnetic resin layer may further have a first side surface perpendicular to the main surface of the base, and the terminal electrode may be continuously formed on the surface and the first side surface of the magnetic resin layer. With this configuration, a solder fillet is formed when the electronic component is mounted on the substrate by soldering, thus making it possible to enhance mounting reliability. In this case, the magnetic resin layer may further have a second side surface perpendicular to both the main surface of the base and the first side surface, and the second side surface of the magnetic resin layer may be completely exposed without being covered with the terminal electrode. With this configuration, a process for manufacturing the electronic component can be simplified, thus making it possible to reduce the manufacturing cost.
In the present invention, the terminal electrode may include first and second terminal electrodes, the passive element part may include a coil pattern, and one and the other ends of the coil pattern may be connected respectively to the first and second terminal electrodes. This allows a coil component as an inductance element to be provided. In this case, the terminal electrode may further include a third terminal electrode formed in a third area of the surface of the magnetic resin layer. This can enhance mounting strength and heat radiation performance.
In the present invention, the film thickness of the terminal electrode and that of the insulating coat layer may differ from each other. That is, the film thickness of the terminal electrode and that of the insulating coat layer need not coincide with each other, but they may be individually designed according to required characteristics.
An electronic component manufacturing method according to the present invention includes the steps of: forming a passive element part on the main surface of a base; forming a magnetic resin layer on the main surface of the base so as to embed the passive element part therein; forming an insulating coat layer having higher smoothness than the surface of the magnetic resin layer in a first area of the surface of the magnetic resin layer that is parallel to the main surface of the base; and selectively forming a terminal electrode connected to the passive element part in a second area which is a part of the surface of the magnetic resin layer that is not covered with the insulating coat layer by electroless plating.
According to the present invention, an electronic component in which underfill easily flows can be provided. Further, since the terminal electrode is formed by the electroless plating using the insulating coat layer as a mask, a process of manufacturing the electronic component can be simplified.
In the present invention, a step of polishing the surface of the magnetic resin layer may be performed before the step of forming the terminal electrode. With this process, a magnetic material such as metal magnetic particles is exposed to the surface of the magnetic resin layer, thereby facilitating the formation of the terminal electrode by the electroless plating. In this case, a step of forming a groove in the magnetic resin layer to expose a part of the side surface of the magnetic resin layer and a part of the passive element part may be performed before the step of forming the terminal electrode. Further, in the step of forming the terminal electrode, the terminal electrode may be formed also on the side surface of the magnetic resin layer. This allows the terminal electrode to be formed on the surface and side surface of the magnetic resin layer simultaneously.
As described above, according to the present invention, there can be provided an electronic component in which underfill easily flows and a manufacturing method therefor.
The above and other objects, features and advantages of this invention will become more apparent by reference to the following detailed description of the invention taken in conjunction with the accompanying drawings, wherein:
Preferred embodiments of the present invention will now be explained in detail with reference to the drawings.
The electronic component 100 according to the present embodiment is a two-terminal type coil component and includes a base 11, a coil pattern C as a passive element part formed on a main surface 11a of the base 11, a magnetic resin layer 12 covering the coil pattern C through an insulating resin 20, terminal electrodes 31 and 32 connected respectively to one end C1 and the other end C2 of the coil pattern C, and an insulating coat layer 40 formed on a surface 12a of the magnetic resin layer 12.
The base 11 has a plate-like body having the xy plane as the main surface 11a and serves as a support body for forming the coil pattern C. The material of the base 11 is not particularly limited, but when the coil pattern C serves as the passive element part as in the present embodiment, the base 11 is preferably a magnetic material such as magnetic resin or ferrite. Although not particularly limited, in the present embodiment, the height of the base 11 in the z-direction is lower than the height of the magnetic resin layer 12 in the z-direction. This is because the back surface of the base 11 is subjected to polishing in a manufacturing process to be described later.
The coil pattern C is made of a good conductor such as copper (Cu) and has eight-turn configuration which is obtained by overlapping two four-turn planar spiral patterns in the z-direction. The one end C1 of the coil pattern C is exposed from a side surface 12b of the magnetic resin layer 12 and connected to the terminal electrode 31. Likewise, the other end C2 of the coil pattern C is exposed from the side surface 12b of the magnetic resin layer 12 and connected to the terminal electrode 32. As a result, the electronic component 100 according to the present embodiment can be used as a two-terminal type coil component having the two terminal electrodes 31 and 32.
The magnetic resin layer 12 is formed on the main surface 11a so as to embed the coil pattern C therein through the insulating resin 20. The magnetic resin layer 12 is made of a composite material obtained by mixing an insulating resin material and a magnetic material such as metal magnetic particles and has comparatively high permeability unlike a general insulating resin. On the other hand, in order to enhance permeability, it is necessary to add a magnetic material having a comparatively large particle diameter, with the result that the surface roughness tends to become larger than that of a general insulating resin. As illustrated in
The magnetic resin layer 12 has a surface 12a having the xy plane, a side surface 12b having the yz plane, and a side surface 12c having the xz plane. The surface 12a of the magnetic resin layer 12 has a first area 12a1 positioned at substantially the center in the x-direction and a second area 12a2 positioned on both sides of the first area 12a1 in the x-direction. The insulating coat layer 40 is formed on the first area 12a1, and terminal electrodes 31 and 32 are formed on the second area 12a2. In the present embodiment, the surface 12a of the magnetic resin layer 12 is completely covered with the insulating coat layer 40 and terminal electrodes 31 and 32, and thus the surface 12a of the magnetic resin layer 12 is not exposed outside. Although a film thickness T1 of the insulating coat layer 40 and a film thickness T2 of the terminal electrodes 31 and 32 are substantially equal to each other in
The terminal electrode 31 or 32 is formed on the side surface 12b of the magnetic resin layer 12. The terminal electrodes 31 and 32 each have an L-shape continuously formed on the surface 12a and side surface 12b of the magnetic resin layer 12. In
The side surface 12c of the magnetic resin layer 12 is not covered with the insulating coat layer 40 and terminal electrodes 31 and 32 and is thus completely exposed.
The insulating coat layer 40 is made of a material having higher smoothness than the surface 12a of the magnetic resin layer 12 and plays a role of enhancing flowability of underfill after mounting. The smoothness can be defined by surface roughness. That is, the surface roughness of the insulating coat layer 40 is smaller than the surface roughness of the surface 12a of the magnetic resin layer 12.
The material of the insulating coat layer 40 is not particularly limited as far as it has higher smoothness than the surface 12a of the magnetic resin layer 12 and may be an insulating resin or an inorganic material. Considering the manufacturing cost, it is preferable to use a resin material as the material of the insulating coat layer 40, and an inorganic filler such as silica may be added so as to reduce the thermal expansion coefficient. When the inorganic filler is added, it is preferable to use an inorganic filler having a small particle diameter so as not make the surface roughness of the insulating coat layer 40 exceed the surface roughness of the surface 12a of the magnetic resin layer 12. For example, when an inorganic filler having a particle diameter of about 5 μm to 10 μm is added to the insulating coat layer 40, it is possible to ensure sufficiently higher smoothness than the magnetic resin layer 12 containing metal magnetic particles.
As described above, the electronic component 100 according to the present embodiment has the insulating coat layer 40 having high smoothness on the surface thereof facing the substrate at mounting, so that the flowability of underfill is not blocked by the magnetic resin layer 12 having large surface roughness. In addition, the terminal electrodes 31 and 32 are directly formed on the surface 12a of the magnetic resin layer 12 having the large surface roughness, so that it is possible to enhance adhesion of the terminal electrodes 31 and 32 by anchor effect.
The following describes a manufacturing method for the electronic component 100 according to the present embodiment.
First, as illustrated in
Then, as illustrated in
Then, as illustrated in
Then, as illustrated in
Then, as illustrated in
Then, as illustrated in
Thus, according to the manufacturing method for the electronic component 100 according to the present embodiment, the terminal electrodes 31 and 32 are formed by the electroless plating using the insulating coat layer 40 as the mask, so that it is possible to simultaneously form the terminal electrodes 31 and 32 each on the surface 12a and side surface 12b of the magnetic resin layer 12 in one process. That is, the insulating coat layer 40 plays two roles of serving as the mask for electroless plating during the manufacturing process and enhancing the flowability of underfill after completion of the electronic component 100.
As illustrated in
In the electronic component 200 according to the second embodiment, the terminal electrodes 31 and 32 are formed not only on the xy plane and yz plane, but also on the inner walls of the arc-like corners of the magnetic resin layer 12, so that solder fillet spreads wider than in the first embodiment. This can further enhance mounting strength onto the substrate.
A manufacturing method for the electronic component 200 according to the second embodiment is as follows. After the processes described using
It is apparent that the present invention is not limited to the above embodiments, but may be modified and changed without departing from the scope and spirit of the invention.
For example, in the above embodiments, the coil pattern C serving as the passive element part has an eight-turn spiral pattern; however, the spiral pattern shape of the passive element part is not limited to this.
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