TWI540601B - Low configuration high power inductors - Google Patents

Description

Low profile high power inductor

The present invention relates to a low profile high power inductor, and more particularly to a low profile high power inductor utilizing a ferromagnetic colloidal protective layer as an electromagnetic core.

An inductor is a kind of electronic component that is wound by an insulated wire to form a self-inductive quantity. The inductor is widely used in electronic circuits, for example, in an electronic circuit of oscillation, tuning, coupling, filtering, delay, and deflection. . When manufacturing, the coil is usually wound on a core to form a conductor loop. When current flows through the coil, according to Faraday's law of electromagnetic induction, the conductor will generate an electromotive force to "react" the change, that is, electromagnetic induction. When the current passes through a 1 Henry inductance element at a rate of change of 1 ampere/second, it induces an induced electromotive force of 1 volt, and the electromagnetic induction L is calculated as ,among them

L = inductance unit Henry (H);

μ ₀ = permeability of free space = 4π × 10 ^-7 H / m;

μ _r = relative magnetic permeability of the core material;

N = number of turns of the coil;

A = cross-sectional area of the coil around the square meter (m ² ); and

l = coil winding length in meters (m).

From the formula, the influence of the number of turns and the cross-sectional area of the wound coil on the size of the inductor can be known. In order to provide sufficient inductance value, the coil used often takes a lot of space, so the inductor often has a large volume, which imposes a considerable burden on the circuit design in the plane or height direction of the circuit board, so that the thin and light design is hindered.

The way in which such electronic components were mounted to the circuit board was mainly by soldering the pins, and even to reduce the height of the components on the circuit board, holes were drilled in the circuit board to accommodate the body portion of the inductor, regardless of the plug-in or the cutting feet. The inductor body is placed in the pre-drilled hole, and most of it needs to be supplemented by manual work, which is not only complicated and time-consuming, but also the circuit board area is limited by such components, and it is not easy to be miniaturized, and cannot be applied in small electronic products. In order to solve these problems, the current mainstream electronic components, on the one hand, the volume is minimized, and mainly installed with the surface mount technology (SMT, surface mount technology) to the circuit board, so that the wiring density on the circuit board is increased, and the occupied area is reduced. It also reduces the delay time of electronic components, and the circuit responds faster and improves overall performance.

1 is a common surface mount chip inductor mainly comprising a magnetic core 11, a coil 12, an electrode 13 and a housing 15, wherein the coil 12 is wound around the magnetic core 11, and the two ends of the coil 12 are respectively guided. It is connected to the electrode 13 and is packaged in a shape of a wafer by a case 15 for surface mounting to a mounting surface of the substrate 14. In the manufacturing process, the coil 12 is first wound around the magnetic core 11, and then connected to the electrode 13 by wire bonding, and finally packaged. However, on the one hand, the magnetic core 11 must occupy a considerable height, which will increase the thickness of the inductor wafer. When the wafer inductor is soldered to the circuit board, the overall circuit board cannot be thinned; on the other hand, between the coil and the electrode The contact structure is relatively fragile. Once the extrusion is slightly pushed and offset during the encapsulation process, the contact position may be poorly contacted, resulting in deterioration of product performance and cost. In particular, the process is mainly mechanical operation and manufacturing precision. Poor, product prices and quality can not be easily upgraded.

Another common surface mount inductor is shown in FIG. 2, wherein the coil 22 is wound in a spiral single layer from the center point, but on the one hand, the metal wire portion is very large in size, which does not conform to the miniaturization trend; In the production process, the two ends of the coil 22 are first welded to a strip having two electrodes, and the strip and the coil are integrally sealed into the metal shell 26, and finally the material is cut. The connection between the strip and the electrodes forms an individual inductor, and finally is mounted on the substrate 25. The operation process is complicated, and the accuracy of many links is not high, and the product yield and precision are thus limited.

Therefore, how to make the surface-mounted chip inductor thinner, to reduce the space occupied by the circuit layout, and to improve the manufacturing yield and precision of the thinned inductor, even the mass production of the batch, so that the output efficiency is greatly increased, It is an important thinking direction to enhance the competitiveness of the product market.

It is an object of the present invention to provide a low profile high power inductor that substantially reduces the thickness of the wafer inductor.

Another object of the present invention is to provide a high precision low profile high power inductor.

It is yet another object of the present invention to provide a low profile high power inductor that can be batch manufactured to increase output efficiency.

Still another object of the present invention is to provide a low profile high power inductor which is a simple structure with a ferromagnetic colloid instead of a magnetic core.

A low profile high power inductor according to the present invention includes: a substrate having an insulating surface on at least one side surface; at least one nautilus coil formed on the at least one insulating surface; and a set of guiding the at least An electrode at both ends of a parrot screw; and a ferromagnetic colloid protective layer enclosing the at least one nautilus coil.

The low-profile high-power inductor disclosed in the present invention is formed by forming a nautilus coil on a substrate by, for example, sputtering, thickening, and forming a ferromagnetic colloid protective layer by a colloidal package of a ferromagnetic material. The ferromagnetic colloid protective layer can replace the magnetic core required for conventional inductors. On the one hand, the height of the chip inductor is greatly reduced, the volume is greatly reduced, and the product precision is extremely high, which fully conforms to the trend of light and thin electronic products; In particular, the structure is relatively simple, batch production, output efficiency and yield can be improved, achieving all of the above objectives in one fell swoop.

The foregoing and other objects, features, and advantages of the invention are set forth in the <RTIgt;

A first preferred embodiment of the low profile high power inductor of the present invention, as shown in FIG. 3, is a substrate 30 made of, for example, an insulating alumina material, which is pre-cut by a laser processing process, for example, by a laser processing. The example is illustrated as a scored frangible portion 310, thereby forming a plurality of substrates 31 joined to each other, and since the alumina has an insulating property, other circuit structures can be provided on the surface thereof. As shown in FIG. 4 and FIG. 5, on the insulating surface of the substrate 31, a copper layer 3310 having a thickness of about several micrometers is first sputtered, and then a photoresist film 361 is coated on the copper layer 3310, and a predetermined pattern is applied. The photomask 40 is overlaid on the photoresist film 361 for exposure, so that the exposed portion of the photoresist film 361 is cured.

Wherein, the predetermined pattern has a plurality of spiral shapes, each spiral corresponds to the one substrate 31, and the uncured photoresist film 361 is washed away by developing (TMAH; Tetra methyl ammonium hydroxide), as shown in FIG. 6. As shown, the remaining photoresist film 361 is spirally distributed over the copper layer 3310. Next, the exposed copper layer 3310 is etched, and the cured photoresist film 361 is removed, thereby forming a spiral copper layer 3310 as shown in FIG. 7. Since the thickness is only a few micrometers, as shown in FIG. It is shown that the spiral copper layer 3310 is plated to be thickened so that each of the substrates 31 is formed with a nautilus coil 32 as shown in FIG.

Thereafter, the most central and outermost ends of the parrot screw 32 are respectively drilled by laser to form two through holes 330, 340 formed through the substrate 31 as shown in FIG. 10, and on each of the substrates 31. The opposite side, corresponding to the perforations 330, 340, forms two conductive electrodes 331, 341 as shown in FIG. 11, respectively. Therefore, when the perforations 330 and 340 are filled with, for example, conductive silver paste, the two ends of the parrot screw 32 above the substrate 31 can be respectively connected to the two guiding electrodes 331 and 341 located under the respective substrates 31 to For future surface mounting for welding purposes.

At this time, as shown in FIG. 12, a colloid mixed with a ferromagnetic material is applied over each of the substrates 31, and on the one hand, the gap of the nautilus-like coil 32 is filled, and at the same time, each of the parrot-like coils 32 is coated, and the colloid is solidified. Thereafter, a ferromagnetic colloid protective layer 38 is formed. The ferromagnetic colloid protective layer 38 is used to protect the nautilus coil 32 from moisture or oxidation, and because of the ferromagnetic substance therein, the magnetoresistance can be reduced, and the magnetic flux generated by the coil conduction can be smoothly performed in the ferromagnetic colloid protective layer 38. Traveling in, providing a good magnetic circuit, thereby replacing the magnetic core required by conventional inductors. Finally, each of the substrates 31 is separated by, for example, a tapping method using the fragile portion 310 formed at the time of pre-cutting to form an individual wafer inductor as shown in FIG.

Since the manufacturing process utilizes a semiconductor process, the precision is calculated in micrometers, which is far superior to the current common chip inductors, and the electrical properties of the fabricated inductors are thus accurate. In addition, the whole structure is simple, such as substrate, coil, protective layer, etc., and the manufacturing process is quite convenient. Compared with the conventional technology, coils are formed one by one, and the inductors in this case are manufactured in batches using, for example, sputtering and plating. The technology produces hundreds or even thousands of components at a time, and the output efficiency and yield are relatively high; and the overall height of the inductor can be less than 1 mm, which greatly saves the occupied circuit space.

Of course, as can be easily understood by those skilled in the art, in the above embodiments, the selection of the substrate, whether the pre-cutting is required, the electrode guiding forming manner, and the like can be implemented in other manners, and the substrate of the second preferred embodiment of the present invention. It is exemplified as a sintered ceramic substrate, and for the sake of convenience, although there is no fragile partial partition on the entire substrate, in this example, the portion where the individual inductor is formed in the future is referred to as an individual substrate. 31' and separated by dashed lines as shown in Figures 14 and 15. In this example, the entire substrate is embedded in a green state before the sintering, and a conductor post 320' penetrating the upper and lower surfaces of the substrate 31' is embedded in the center of each of the substrates 31'. Therefore, each of the sintered substrates 31 is embedded. The center is respectively formed with a through hole 311' penetrating through the substrate 31', and a conductor post 320' buried in the through hole 311'. In addition, the upper and lower insulating surfaces of the respective substrates 31' are respectively formed with a surrounding side wall 36' by the sintered ceramics, so that a cylindrical recessed receiving portion 360 is formed at the upper and lower surfaces of each of the substrates 31'. '.

Next, in the same manner, in each of the substrates 31' and the accommodating portion 360' of the lower double-layer insulating surface, a nautilus coil 32' as shown in FIGS. 16 and 17 is formed, respectively, and each of the surrounding side walls 36 is formed. The top surfaces of the 'each form two lead electrodes 331', 341'. Since the upper and lower ends of the two nautilus coils 32' are centrally connected via the conductor post 320', and the circuits therein are bypassed in the same clockwise or counterclockwise direction, the upper and lower coils are formed. The magnetic forces add to each other. Subsequently, the outermost end of the upper coil is wire-bonded to the conductive electrode 331' on the upper surrounding side wall 36'; the outermost end of the lower coil is wire-bonded to the conductive electrode 341' on the lower surrounding side wall 36'.

Referring to FIG. 18 together, at this time, a colloid of ferromagnetic material is poured into the accommodating portion 360', and the nautilus coil 32' on the upper and lower sides is completely covered therein; and the surrounding side wall 36' is The conductive electrodes 331', 341' are exposed to the colloid of the ferromagnetic material, and the ferromagnetic colloid protective layer 38' is formed after the colloid of the ferromagnetic material is solidified. Subsequently, the preheating resin is pressurized into the accommodating space until the surrounding side wall 36' is filled. After the resin is hardened, the housing corresponding to each of the substrates 31' is formed, and the conductive electrodes 331', 341' on the upper and lower sides are formed. Still exposed.

Next, for example, cutting with a diamond knife, the substrate 31' is separated from the substrate 31' in a strip shape, and the side edges on which the conductive electrodes 331', 341' are formed are exposed, and as shown in FIG. After the substrate 31' is stacked, a side conductive layer is sputtered on the side of each substrate 31' by, for example, sputtering, so that the upper and lower conductive electrodes 331', 341' can be extended to the side. Next, the entire plurality of components are separated one by one, and then the barrel plating operation is performed to thicken the side electrodes, and the guiding electrodes 331' and 341' above the substrate 31' are properly guided to the lower guiding respectively. Electrodes 331', 341'. Therefore, the upper and lower sides of the element form a symmetrical structure, which can be soldered either above or below, thereby completing the low profile high power inductor of this example as shown in FIG.

Further, if the nautilus coils on the upper and lower sides are not connected to each other in the previous embodiment, and the magnetic lines formed by one of the ones are induced to the other, a micro-transformer can be constructed, so referring to FIG. 21 As shown in the third preferred embodiment of the present invention, in this example, the substrate 31" also has a core 320" extending through the upper and lower sides, and on the opposite sides of the substrate 31", two nautilus coils are also formed. 32", and respectively form a surrounding side wall 36", since in this example, the upper and lower two nautilus coils 32" are wound with different numbers of turns, and the central end of each parrot screw 32" The portion does not contact the core 320", but connects the most central and outermost ends of the upper nautilus coil 32" to the guiding electrodes 331", 341" of the upper surrounding side wall 36", respectively, and the lower parrot The most central and outermost ends of the spiral coil 32" are respectively guided to the conductive electrodes 331", 341" of the lower surrounding side wall 36".

Finally, as shown in FIG. 22, ferromagnetic colloids are respectively filled in the upper and lower accommodating portions to form a ferromagnetic colloid protective layer 38", and separation of the respective elements is performed, and side electrodes are formed, so that the upper conductive electrodes are formed. As shown in Figures 23 and 24, it is guided to the bottom surface for soldering in future surface mounting. Thus, the wafer transformer of this example can be constructed by the inductor elements on both sides of the substrate.

Since the low-profile high-power inductor of the present invention has a thinned structure, when the surface is mounted on the circuit board, the space occupied by the circuit layout can be reduced, and the manufacturing process is quite precise, so that the inductance value ( L) Accurate, especially the wafer inductor of the present invention has a simple structure, a large number of components can be manufactured in a single manufacturing process, and is not limited to individual windings of the prior art, so that the operation procedure is simplified, the product yield and the output efficiency are improved, and the above is achieved. Every purpose.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications according to the scope of the present invention and the description of the invention are still It is within the scope of the patent of the present invention.

11. . . Magnetic core

12, 22. . . Coil

13. . . electrode

14, 25, 31, 31', 31"... substrate

15. . . case

26. . . Metal housing

30. . . Substrate

310. . . Vulnerable department

3310. . . Copper layer

361. . . Photoresist film

40. . . Mask

32, 32', 32"... Nautilus coil

330, 340. . . perforation

331, 341, 331', 341', 331", 341". . . Lead electrode

38, 38', 38"... Ferromagnetic colloidal protective layer

320’. . . Conductor column

311’. . . perforation

36', 36"... around the side wall

360’. . . Housing

320"...iron core

Figure 1 is a conventional surface mount chip inductor;

2 is a conventional surface mount wafer inductor having a spiral single layer wound coil;

3 is a schematic view showing the substrate of the first preferred embodiment of the low-profile high-power inductor of the present invention pre-cut to form a plurality of substrates connected to each other;

4 is a side view of the substrate of FIG. 3 with a copper layer sputtered, a photoresist film coated on the copper layer, and a photomask having a predetermined pattern covering the photoresist film;

Figure 5 is a plan view of the substrate of Figure 4;

6 is a side view of the remaining photoresist film of FIG. 4 spirally distributed over the substrate and the copper layer;

Figure 7 is a side view of the copper layer of Figure 6 distributed on the substrate in a spiral shape;

Figure 8 is a side elevational view of the spiral copper layer of Figure 7 electroplated to form a nautilus coil;

Figure 9 is a plan view showing the base of Figure 8 formed with a nautilus coil;

Figure 10 is a side view of the substrate of Figure 8 with two holes formed by laser drilling through the substrate;

Figure 11 is a side view of the perforation of Figure 10 filled with conductive silver glue, so that the two ends of the parrot screw are respectively guided to the underlying electrodes of the substrate;

12 is a side view of the nautilus coil of FIG. 11 filled with a gap and a coating filled with a ferromagnetic material, and formed into a ferromagnetic colloid protective layer after the colloid is solidified;

Figure 13 is a side elevational view of the wafer inductor of the present embodiment formed after the substrate of Figure 12 is diced and separated;

14 is a second preferred embodiment of the low-profile high-power inductor of the present invention, in which a conductor post is embedded in the substrate on the upper and lower surfaces of the substrate, and the upper and lower insulating surfaces of each substrate are respectively formed by sintered ceramics. a side view surrounding the side wall;

Figure 15 is a plan view of the substrate of Figure 14;

Figure 16 is a side view of the upper and lower surrounding side walls of Figure 14 respectively forming two nautilus coils, and forming two guiding electrodes on the top surfaces of the surrounding side walls;

Figure 17 is a plan view of the substrate of Figure 16;

Figure 18 is a side view of the ferromagnetic colloid of the ferromagnetic material after the colloid of the ferromagnetic material is solidified;

19 is a side view of the substrate of FIG. 18 after being stacked in a strip, and simultaneously sputtering a side conductive layer on each substrate side by, for example, sputtering;

Figure 20 is a side view showing the wafer inductor of this example formed after the substrate of Figure 19 is diced and separated;

21 is a side view of a nautilus-like coil in which two different coil turns are formed in the lower two surrounding sidewalls according to a third preferred embodiment of the low-profile high-power inductor of the present invention;

Figure 22 is a side view of the colloid of ferromagnetic material filled in the surrounding side wall of Figure 21, and a side view of the ferromagnetic colloid protective layer formed after the colloid of the ferromagnetic material is solidified;

Figure 23 is a side elevational view showing the side electrodes of the substrate of Figure 22, respectively;

Figure 24 is a bottom plan view of the substrate of Figure 23;

Designated components represent no number

31'‧‧‧Substrate

32’‧‧‧ Nautilus coil

36’‧‧‧ Surrounding the side wall

38'‧‧‧ Ferromagnetic colloidal protective layer

331', 341'‧‧‧ lead electrode

360’‧‧‧ 容

Claims (4)

A low profile high power inductor comprising: a substrate having an insulating surface on at least one side surface; at least one nautilus coil formed on the at least one insulating surface; and a set of at least one nautilus coil An electrode at both ends; a ferromagnetic colloid protective layer enclosing the at least one nautilus coil; and a surrounding sidewall formed on an outer edge of the corresponding substrate and forming a receiving portion with the substrate, and the ferromagnetic colloid The protective layer is filled in the receiving portion. The low profile high power inductor of claim 1, wherein the substrate has two insulating surfaces on opposite sides, and the aforementioned nautilus coils are respectively formed on the two insulating surfaces, and the ferromagnetic colloid protective layer The aforementioned parrot screw is closed. The low-profile high-power inductor of claim 2, wherein a perforation is formed in the substrate, and a guiding electrode for guiding the two parrot-shaped coils is formed in the through hole. The low profile high power inductor of claim 1, wherein the receiving portion is a cylindrical recess.