The present disclosure relates to a module with a coil core embedded in an insulating layer, and a method for manufacturing the module.
Some modules designed for high frequency signals have, as a component to prevent noise, a toroidal coil mounted on a wiring board. For example, as illustrated in
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-278841 (see paragraphs 0010 to 0014,
The core formed by the magnetic core 102 and the coil electrode is physically large relative to other electronic components mounted on the upper face of the wiring board 101. The upper face of the wiring board 101 thus needs to be provided with a large area for mounting the coil. This requirement places a limit to the miniaturization of the module 100 through reduction of the area of the principal face of the wiring board 101. Although miniaturization of the module 100 would be achieved by building the coil into the wiring board 101, if the wiring board 101 is made of resin, it is possible that the heat generated from the coil builds up within the resin, leading to the degradation of the coil characteristics.
The present disclosure has been made in view of the above-mentioned problems, and accordingly it is an object of the disclosure to achieve miniaturization of a module by building a coil into the module, while also achieving the improved dissipation of the heat generated from the coil.
To achieve the above object, a module according to the present disclosure includes an insulating layer, a ring-shaped coil core embedded in the insulating layer, a coil electrode disposed in the insulating layer so as to wind around the coil core, and a heat-dissipating member disposed outside the coil core within the insulating layer.
Building the coil core into the insulating layer as described above eliminates the need to provide the principal face of the insulating layer with a large mounting area for mounting a coil formed by the coil core and the coil electrode. This allows the area of the principal face of the insulating layer to be reduced to achieve miniaturization of the module.
Further, for example, if the heat-dissipating member is made of metal, the metal has a thermal conductivity higher than that of a material such as ceramic or resin commonly used to form the insulating layer, and thus the presence of the heat-dissipating member made of metal and disposed outside the coil core within the insulating layer improves the dissipation of the heat generated from the coil.
If the heat-dissipating member is made of metal, contact of the heat-dissipating member with the coil electrode may lead to the degradation of the coil characteristics. Even if the heat-dissipating member and the coil electrode do not contact each other, when the two components are located in close proximity to each other, this may cause an eddy current to be generated in that location, leading to the degradation of the coil characteristics. Accordingly, if an insulator with a thermal conductivity higher than that of the insulating layer is used to form the heat-dissipating member, this makes it possible to prevent the degradation of the coil characteristics even when the heat-dissipating member and the coil electrode are placed in contact with or in close proximity to each other.
Disposing the heat-dissipating member made of metal outside the coil core has the following effect. For example, if stress is exerted on the coil core from outside the module, such as when the module is dropped, the heat-dissipating member also acts as a component that mitigates this stress, thus preventing the breakage of the coil core due to external stress.
The heat-dissipating member may be further disposed inside the coil core within the insulating layer. This configuration allows the heat generated from the coil to be dissipated by the heat-dissipating members disposed both outside and inside the coil core, thus further improving the heat dissipation characteristics of the module.
The coil electrode may include a plurality of outer metal pins disposed so as to cross the circumferential direction of the coil core, the outer metal pins being arranged along the outer circumferential face of the coil core, a plurality of inner metal pins disposed so as to cross the circumferential direction of the coil core, the inner metal pins being arranged along the inner circumferential face of the coil core such that the inner metal pins form a plurality of pairs with the corresponding ones of the outer metal pins, a plurality of first connecting members that each connect one end face of one of the outer metal pins with one end face of one of the inner metal pins that forms a pair with the outer metal pin, and a plurality of second connecting members that each connect another end face of one of the outer metal pins, with another end face of one of the inner metal pins located adjacent to and on a predetermined side of one of the inner metal pins that forms a pair with the outer metal pin.
The outer metal pins and the inner metal pins have a low resistivity in comparison to conductors formed by providing through-holes in the insulating layer, such as via conductors and through-hole conductors. Consequently, when each conductor connecting a predetermined one of the first connecting members with the corresponding second connecting member is formed by the outer metal pin or the inner metal pin, the overall resistance of the coil electrode can be reduced, thus improving the characteristics of the coil included in the module.
Use of conductors formed by providing through-holes in the insulating layer, such as via conductors and through-hole conductors, places a limit to the narrowing of the pitch between adjacent conductors. By contrast, use of the outer metal pins and the inner metal pins, which are formed without providing such through-holes, facilitates the narrowing of the pitch between adjacent metal pins. The pitch between adjacent metal pins can be thus easily narrowed to increase the number of turns in the coil electrode. This makes it possible to provide a module with a high-inductance coil embedded in the module, within the limited space in the interior of the insulating layer.
The outer metal pins, the inner metal pins, and the heat-dissipating member may be each made of the same metal. This allows the outer metal pins, the inner metal pins, and the heat-dissipating member to be formed simultaneously.
The outer metal pins, the inner metal pins, and the heat-dissipating member may be each made of different metals. This configuration allows, for example, the heat-dissipating member to be made of a metal with superior heat dissipation characteristics, while allowing the outer metal pins and the inner metal pins to be each made of a metal that is highly rigid and not prone to breakage.
A method for manufacturing a module according to the present disclosure includes the steps of preparing a metal plate, the metal plate being stuck on one principal face of a support having a flat shape, etching the metal plate to simultaneously form a plurality of outer metal pins disposed upright on one principal face of the support and arranged in a ring shape, a plurality of inner metal pins located inside the outer metal pins with a placement space for placing a coil core being interposed between the inner metal pins and the outer metal pins, the inner metal pins being disposed upright on the one principal face of the support and arranged in a ring shape to form a plurality of pairs with corresponding ones of the outer metal pins, and a metal body serving as a heat-dissipating member, the metal body being disposed in, out of an area located outside the outer metal pins and an area located inside the inner metal pins, at least the area located outside the outer metal pins, placing the coil core in the placement space, forming an insulating layer that seals the one principal face of the support, the coil core, the outer metal pins, the inner metal pins, and the metal body, performing polishing or grinding to remove the support, and expose both end faces of the outer metal pins and both end faces of the inner metal pins from the insulating layer, and forming a plurality of first connecting members that each connect one end face of one of the outer metal pins with one end face of one of the inner metal pins that forms a pair with the outer metal pin, and a plurality of second connecting members that each connect another end face of one of the outer metal pins with another end face of one of the inner metal pins located adjacent to and on a predetermined side of one of the inner metal pins that forms a pair with the outer metal pin.
In this case, etching, which is a common technique, can be used to form the following components disposed within the insulating layer: the outer metal pins and the inner metal pins, and the metal body serving as a heat-dissipating member that is located in, out of an area outside the outer metal pins and an area inside the inner metal pins, at least the area outside the outer metal pins. This allows for easy manufacture of a module that is capable of being miniaturized by building a coil core into the module, while achieving the improved dissipation of the heat generated from the coil.
Further, the outer metal pins, the inner metal pins, and the metal body that serves as a heat-dissipating member can be formed simultaneously by etching, thus enabling the inexpensive manufacture of a module that is compact with superior heat dissipation characteristics.
According to the present disclosure, the magnetic core is embedded in the insulating layer, thus eliminating the need to provide the principal face of the insulating layer with a large mounting area for mounting a coil formed by the coil core and the coil electrode. This allows the area of the principal face of the insulating layer to be reduced to achieve miniaturization of the module. Further, for example, if the heat-dissipating member is made of metal, the metal has a thermal conductivity higher than that of a material such as ceramic or resin commonly used to form the insulating layer, and thus the presence of the heat-dissipating member made of metal and disposed outside the coil core within the insulating layer improves dissipation of the heat generated from the coil.
A module 1 according to an embodiment of the present disclosure will be described with reference to
As illustrated in
The insulating layer 2 is made of, for example, thermosetting resin such as epoxy resin. The insulating layer 2 is formed so as to cover the magnetic core 3, the metal bodies 5a and 5b, and outer metal pins 6 and inner metal pins 7 that will be described later.
The magnetic core 3 is a so-called toroidal core formed in a ring shape. The magnetic core 3 is made of, for example, a magnetic material commonly used for a coil core, such as ferrite.
The coil electrode 4 is spirally wound around the ring-shaped magnetic core 3. The coil electrode 4 includes a plurality of outer metal pins 6 disposed on the outer circumferential side of the magnetic core 3, a plurality of inner metal pins 7 disposed on the inner circumferential side of the magnetic core 3, a plurality of upper wiring electrodes 8 (corresponding to “first connecting members” according to the present disclosure) disposed on one principal face (upper face) of the insulating layer 2, and a plurality of lower wiring electrodes 9 (corresponding to “second connecting members” according to the present disclosure) disposed on the other principal face (lower face) of the insulating layer 2.
As illustrated in
The inner metal pins 7 are disposed so as to form a plurality of pairs with the corresponding outer metal pins 6. As illustrated in
A covering resin layer 10 is stacked on each principal face of the insulating layer 2 so as to cover the upper wiring electrodes 8 and the lower wiring electrodes 9. The covering resin layer 10 is made of, for example, the same resin as the resin used to form the insulating layer 2, such as thermosetting resin. Alternatively, instead of the covering resin layer 10, a wiring board with a ground electrode may be used to connect the ground electrode with the heat-dissipating metal bodies 5a and 5b. This configuration further improves the dissipation of heat by the metal bodies 5a and 5b.
The heat-dissipating metal bodies 5a and 5b are each made of a metal such as Cu or Al, and disposed within the insulating layer 2. Specifically, as illustrated in
Instead of the metal bodies 5a and 5b, for example, an insulator with a thermal conductivity higher than that of the insulating layer 2, such as aluminum nitride or silicon nitride, may be used to form the heat-dissipating member.
(Method for Manufacturing Module 1)
Next, a method for manufacturing the module 1 will be described with reference to
First, a metal plate 12 made of Cu with a predetermined thickness is prepared as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Lastly, as illustrated in
In the above-mentioned embodiment, the magnetic core 3 is thus embedded in the insulating layer 2. This eliminates the need to provide the principal face of the insulating layer 2 with a large mounting area for mounting a coil formed by the magnetic core 3 and the coil electrode 4. This allows the area of the principal face of the insulating layer 2 to be reduced to achieve miniaturization of the module 1.
The metal forming the heat-dissipating metal bodies 5a and 5b has a thermal conductivity higher than that of the resin forming the insulating layer 2. Consequently, the presence of the heat-dissipating metal body 5a disposed outside the magnetic core 3 within the insulating layer 2 improves dissipation of the heat generated from the coil. Since the heat-dissipating metal body 5b is also disposed inside the magnetic core 3 within the insulating layer 2, dissipation of the heat generated from the coil is further improved.
Disposing the metal body 5a outside the magnetic core 3 has the following effect. For example, if stress is exerted on the magnetic core 3 from outside the module 1, such as when the module 1 is dropped, the metal body 5a also acts as a component that mitigates this stress, thus preventing breakage of the magnetic core 3 due to external stress.
If the heat-dissipating member is made of metal (the metal body 5a or 5b), contact of the metal body 5a or 5b with the coil electrode 4 may lead to the degradation of the coil characteristics. Even if the metal body 5a or 5b and the coil electrode 4 do not contact with each other, when the two components are located in close proximity to each other, this may cause an eddy current to be generated in that location, leading to the degradation of the coil characteristics. Accordingly, if an insulator such as aluminum nitride or silicon nitride instead of the metal body 5a or 5b is used to form the heat-dissipating member, this makes it possible to prevent the degradation of the coil characteristics even when the heat-dissipating member and the coil electrode 4 are placed in contact with or in close proximity to each other.
The outer metal pins 6 and the inner metal pins 7 have a low resistivity in comparison to conductors formed by providing through-holes in the insulating layer 2, such as via conductors and through-hole conductors. Consequently, when each conductor connecting a predetermined one of the upper wiring electrodes 8 with the corresponding lower wiring electrode 9 is formed by the outer metal pin 6 or the inner metal pin 7, the overall resistance of the coil electrode 4 can be reduced, thus improving the characteristics of the coil included in the module 1.
Use of conductors formed by providing through-holes in the insulating layer 2, such as via conductors and through-hole conductors, places a limit to the narrowing of the pitch between adjacent conductors. By contrast, use of the outer metal pins 6 and the inner metal pins 7, which are formed without providing such through-holes, facilitates the narrowing of the pitch between the metal pins 6 and 7 that are adjacent to each other. The pitch between the adjacent metal pins 6 and 7 can be thus easily narrowed to increase the number of turns in the coil electrode 4. This makes it possible to provide the module 1 with a high-inductance coil embedded in the module 1, within the limited space in the interior of the insulating layer 2.
Forming each of the metal pins 6 and 7 and the heat-dissipating metal bodies 5a and 5b by the same metal allows the metal pins 6 and 7 and the metal bodies 5a and 5b to be formed simultaneously.
With the method for manufacturing the module 1 according to this embodiment, etching, which is a common technique, can be used to form the following components disposed within the insulating layer 2: the metal pins 6 and 7, the heat-dissipating metal body 5a disposed outside the outer metal pins 6, and the heat-dissipating metal body 5b disposed inside the inner metal pins 7. This allows for easy manufacture of the module 1 that is capable of being miniaturized by building the magnetic core 3 into the module 1, while achieving the improved dissipation of the heat generated from the coil.
Further, the outer metal pins 6, the inner metal pins 7, and the heat-dissipating metal bodies 5a and 5b can be formed simultaneously by etching, thus enabling the inexpensive manufacture of the module 1 that is compact with superior heat dissipation characteristics.
The present disclosure is not limited to each embodiment mentioned above but may be modified in various forms other than those mentioned above, without departing from the scope of the disclosure. For example, although the above-mentioned embodiment is directed to a method for manufacturing the module 1 in which each of the metal pins 6 and 7 and the heat-dissipating metal bodies 5a and 5b are made of the same metal, if each of the metal pins 6 and 7 and the metal bodies 5a and 5b are to be made of different metals, the manufacturing method may be modified such that, during the etching of the metal plate 12 described above with reference to
The coil to be embedded in the module 1 may not necessarily be a toroidal coil.
The present disclosure can be applied to various modules with a coil core embedded in the insulating layer.
1 module
2 insulating layer
3 magnetic core (coil core)
4 coil electrode
5
a,
5
b metal body (heat-dissipating member)
6 outer metal pin
7 inner metal pin
8 upper wiring electrode (first connecting member)
9 lower wiring electrode (second connecting member)
Number | Date | Country | Kind |
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2014-054855 | Mar 2014 | JP | national |
This is a continuation of International Application No. PCT/JP2015/055642 filed on Feb. 26, 2015 which claims priority from Japanese Patent Application No. 2014-054855 filed on Mar. 18, 2014. The contents of these applications are incorporated herein by reference in their entireties.
Number | Date | Country | |
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Parent | PCT/JP2015/055642 | Feb 2015 | US |
Child | 15267729 | US |