Thin film type inductor

A thin film type inductor includes: a body including a support member including a through hole, upper and lower coils disposed on upper and lower surfaces of the support member, respectively, and a via penetrating through the support member while connecting the upper and lower coils to each other; and external electrodes disposed on an external surface of the body. A coil pattern directly connected to the via may include an inclined surface.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims the benefit of priority to Korean Patent Application No. 10-2017-0134150 filed on Oct. 16, 2017 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a thin film type inductor, and more particularly, to a thin film type power inductor advantageous for high inductance and miniaturization.

BACKGROUND

In accordance with the development of information technology (IT), apparatuses have been rapidly miniaturized and thinned. Therefore, market demand for small, thin devices has increased.

Korean Patent Laid-Open Publication No. 10-1999-0066108 provides a power inductor including a substrate having a via hole and coils disposed on opposite surfaces of the substrate and electrically connected to each other by the via hole of the substrate, in accordance with such a technical trend to provide an inductor including coils having uniform and high aspect ratios.

Further, in a design of the power inductor, generally, upper and lower coils are connected to each other by filling a via hole. Here, a line width of a via hole pad portion may be designed to be wider than that of other coil patterns. Therefore, a plating layer in the vicinity of the pad portion may grow rapidly, as compared to other coil patterns, and when an additional planarization process is not subsequently performed, it may be difficult to provide a plating pattern having a desired thickness without a plating deviation.

SUMMARY

An aspect of the present disclosure may provide a thin film type inductor in which a plating deviation is decreased by controlling line widths of upper and lower coil patterns directly connected to a via hole not to excessively grow as compared to a line width of other coil patterns.

According to an aspect of the present disclosure, a thin film type inductor may include: a body including an internal coil including a plurality of coil patterns, a support member supporting the internal coil, and a magnetic material encapsulating the internal coil and the support member, the body having upper and lower surfaces facing each other in a thickness (T) direction, first and second end surfaces in a length (L) direction, and first and second side surfaces in a width (W) direction; and external electrodes disposed on an external surface of the body and electrically connected to the internal coil. The internal coil may include an upper coil and a lower coil disposed on upper and lower surfaces of the support member, respectively, in the thickness direction. The upper and lower coils may be connected to each other by a via penetrating through the support member. A plurality of first coil patterns forming the upper coil and a plurality of second coil patterns forming the lower coil may include an upper connection pattern and a lower connection pattern, respectively, which are directly connected to the via. At least one of an upper portion of the upper connection pattern and an upper portion of the lower connection pattern may include an inclined surface.

According to another aspect of the present disclosure, a thin film type inductor may include: a body including an internal coil including a plurality of coil patterns, a support member supporting the internal coil, and a magnetic material encapsulating the internal coil and the support member, the body having upper and lower surfaces facing each other in a thickness (T) direction, first and second end surfaces in a length (L) direction, and first and second side surfaces in a width (W) direction; and external electrodes disposed on an external surface of the body and electrically connected to the internal coil. The internal coil may include an upper coil and a lower coil disposed on upper and lower surfaces of the support member, respectively, in the thickness direction. The upper and lower coils may be connected to each other by a via penetrating through the support member. A plurality of first coil patterns forming the upper coil and a plurality of second coil patterns forming the lower coil may include an upper connection pattern and a lower connection pattern, respectively, which are directly connected to the via. Each of the upper and lower connection patterns may include an upper region and a lower region, the upper region located at a farther side from the support member, the lower region located at a nearer side to the support member and directly connected to the via. A cross section of the lower region of at least one of the upper and lower connection patterns in a width-thickness (W-T) direction may have a rectangular shape, and a cross section of the upper region of at least one of the upper and lower connection patterns in the width-thickness (W-T) direction may have a trapezoidal shape, which has a decreasing width in the width direction from the nearer side to the farther side of the support member.

DETAILED DESCRIPTION

Hereinafter, a thin film type inductor according to an exemplary embodiment in the present disclosure will be described, but is not necessarily limited thereto.

FIG. 1is a schematic perspective view of a thin film type inductor100according to an exemplary embodiment in the present disclosure, andFIG. 2is a schematic plan view of an internal coil ofFIG. 1.

Referring toFIGS. 1 and 2, the thin film type inductor100may include a body1and external electrodes21and22disposed on an external surface of the body.

Next, the body1may form an exterior of the thin film type inductor, have upper and lower surfaces opposing each other in a thickness (T) direction, first and second end surfaces opposing each other in a length (L) direction, and first and second side surfaces opposing each other in a width (W) direction, and be substantially hexahedron. However, an external shape of the body is not limited.

The body1may contain a magnetic material11having magnetic properties. Here, as the magnetic material11, any material may be used as long as it has magnetic properties. For example, the magnetic material11may be ferrite or a material in which metal magnetic particles are filled in a resin, wherein the metal magnetic particle may contain one or more selected from the group consisting of iron (Fe), silicon (Si), chromium (Cr), aluminum (Al), and nickel (Ni).

The magnetic material11may serve as an encapsulant encapsulating a support member12to be described below and an internal coil13supported by the support member12.

The first and second external electrodes21and22may be connected to lead portions of the internal coil13exposed to the first and second end surfaces of the body opposing each other in the length direction, respectively. The first and second external electrodes may be formed to be extended to the upper and lower surfaces and the first and second side surfaces of the body adjacent to the first and second end surfaces of the body as well as the first and second end surfaces thereof to thereby entirely have an alphabet C shape, but are not limited thereto. That is, the first and second external electrodes may also be formed of L-shaped electrodes or bottom-surface electrodes.

Referring toFIGS. 1 and 2, a region A including a coil pattern in the vicinity of a via connecting upper and lower coils131and132of the internal coil13to each other is illustrated. The region A illustrates that the thin film type inductor100according to the present disclosure includes a coil pattern having a substantially uniform line width as compared to a thin film type inductor according to the related art. Since the line width of the coil pattern in the region A is substantially the same as that of other coil patterns, it may be appreciated that a plating deviation between the coil patterns is not large. This may be appreciated from the fact that generally, in a case of designing a coil pattern to have a wide line width at a specific point, at the time of plating the coil pattern, since a plating growth rate at the specific point is faster than a plating growth rate at other points, over-plating of the coil pattern occurs at the specific point. When the over-plating occurs at the specific point as described above, only in a case of adjusting the thickness of the coil pattern to be uniform using a separate method such as a polishing method, or the like, the coil pattern having a uniform thickness may be obtained. Meanwhile, as illustrated in the region A ofFIGS. 1 and 2, since the line width of the coil pattern in the vicinity of the via is substantially the same as that of other points, a filling rate of the magnetic material11filled in a through hole H may be increased.

Next, a specific shape of a plurality of coil patterns including the region A ofFIGS. 1 and 2will be described in more detail with reference toFIG. 3.

FIG. 3is a schematic cross-sectional view taken along line I-I′ ofFIG. 1. Referring toFIG. 3, the internal coil13may include the upper coil131supported on an upper surface of the support member and the lower coil supported on a lower surface of the support member based on the support member12. Meanwhile, since a detailed description of the upper coil131may be applied to the lower coil132as it is, hereinafter, for convenience of explanation, a separate description of the lower coil132will be omitted.

A through hole H and a via hole spaced apart from the through hole H by a predetermined distance may be included in the support member12. As described above, the magnetic material11may be filled in the through hole H, and the via hole may be filled with a conductive material to form a via15. Here, the via15may serve to connect the upper and lower coils131and132to each other.

The via15may be directly connected to an upper connection pattern131camong the plurality of coil patterns of the upper coil131and directly connected to a lower connection pattern132camong the plurality of coil patterns of the lower coil. In this case, a connection structure between the via15and the upper connection pattern131cand between the via15and the lower connection pattern132cmay be suitably selected by those skilled in the art in consideration of process conditions and desired characteristics. For example, the via15may be formed so that a side surface of the via hole is enclosed by a seed pattern and a portion of the via15penetrating through the via hole is formed integrally with the upper and lower connection patterns131c,132cwithout a boundary line therebetween, but is not limited thereto.

The upper connection pattern131cdirectly connected to the via15may include lower and upper regions1311cand1312c. Although the upper and lower regions1311cand1312care formed integrally with each other without a boundary line therebetween, for convenience of explanation, these regions are illustrated as configurations distinguished from each other. A cross section of the lower region1311cof the upper connection pattern131cin a width-thickness (W-T) direction may have a rectangular shape. Since an insulating part14insulating the plurality of coil patterns from each other serves as a guide of the upper connection pattern131c, the cross section described above may be obtained. Since the insulating part14is prepared before a plating process for the internal coil13is performed, the internal coil13may grow only in a space in an opening portion prepared in the insulating part14. As a result, the lower region1311cof the upper connection pattern131cmay grow so as to have a rectangular cross section.

Next, a cross section of the upper region1312cof the upper connection pattern131cin the width-thickness (W-T) direction may have a trapezoidal shape. One surface of the upper region1312cmay be an inclined surface, which inclines toward a center of a core of the internal coil13, and a method of forming the inclined surface is not limited, but for example, the inclined surface may be formed by performing exposure and development at least two times. As a specific example, after laminating an insulating sheet on the support member, performing primary exposure, and subsequently performing secondary exposure, development may be performed. At the time of performing the primary exposure, exposure may be performed at an exposure amount of 1000 mJ/cm2to 3000 mJ/cm2, and the secondary exposure may be additionally performed only on a region in which the inclined surface will be formed. In this case, it is suitable that an exposure amount of the secondary exposure is selected in a range of 2.5% to 15% of the exposure amount of the primary exposure, and may be preferably about 50 mJ/cm2to 400 mJ/cm2. The inclined surface may be substantially formed by additionally performing the secondary exposure. An inclined angle of the inclined surface or a maximum width of the inclined surface may be suitably determined by those skilled in the art.

A width W1of an edge of the upper connection pattern131ccoming into contact with the support member12may be wider than a width W2of an upper surface of the upper connection pattern131cin parallel with the support member12. A width W3of an edge of the lower connection pattern132ccoming into contact with the support member12may be wider than a width W4of an upper surface of the lower connection pattern132cin parallel with the support member12.

A width W1of an edge of the upper connection pattern131ccoming into contact with the support member12may be substantially equal to a maximum width of a coil pattern closest to the upper connection pattern131camong the plurality of coil patterns forming the upper coil131. A width W3of an edge of the lower connection pattern132ccoming into contact with the support member12is substantially equal to a maximum width of a coil pattern closest to the lower connection pattern132camong the plurality of coil patterns forming the lower coil132. When the cross section of the upper region1312cof the upper connection pattern131cin the width-thickness (W-T) direction has the trapezoidal shape, an innermost insulating part141adisposed to be adjacent to the center of a magnetic core of the internal coil13while coming into contact with the inclined surface of the upper region1312cof the upper connection pattern131cmay also have an inclined surface corresponding to the inclined surface of the upper region1312c. The innermost insulating part141amay be composed of a basic insulating part1412aand a remaining insulating part1411aincluding the inclined surface. The remaining insulating part1411amay be formed by secondary exposure. The remaining insulating part1411amay serve to prevent over-plating of the upper connection pattern, and since the remaining insulating part1411aserves as a guide for plating growth, the remaining insulating part1411amay serve to control the over-growth of the upper connection pattern131cin the width or thickness direction. As a result, the upper connection pattern131cmay not have an over-plating growth defect in the upper region1312cthereof while having the lower region1311cwide enough to prevent an open failure of the via15from occurring.

The insulating part14may further include insulating parts141b1,141b2,142b3,142b4, and142b5serving as growth guides of the coil pattern in addition to the innermost insulating part141adisposed in an innermost portion of the insulating part14. The insulating parts141b1,141b2,142b3,142b4, and142b5may be formed simultaneously with forming the basic insulating part1412aof the innermost insulating part141a. A coil pattern having a high aspect ratio may be stably formed by the insulating parts141b1,141b2,142b3,142b4, and142b5. Cross sections of the insulating parts141b1,141b2,142b3,142b4, and142b5in the W-T direction may have a rectangular shape, but a design for the cross-sectional shape thereof may be suitably changed into a suitable shape by those skilled in the art at the time of exposure.

In addition, an additional insulating part16may be further disposed on the insulating part14. The additional insulating part16may be a configuration for insulation between the upper surface of the coil pattern and the magnetic material11, but may be simultaneously disposed on the insulating part14, such that a double insulation effect may be implemented. A method of forming the additional insulating part16is not limited. For example, the additional insulating part may be formed by laminating an insulating sheet. There is no need to use a photosensitive insulating material as a material of the additional insulating part16, but any material may be used as long as it has insulation properties. On the contrary, since the insulating part14needs to be subjected to exposure and development, it is advantageous to form the insulating part14using the photosensitive insulating material.

FIG. 4is a schematic cross-sectional view of a modified example of the thin film type inductor ofFIG. 3. A thin film type inductor200ofFIG. 4is substantially equal to the thin film type inductor100ofFIG. 3except that a shape of an additional insulating part16′ is different. For convenience of explanation, a description of components overlapping those of the thin film type inductor ofFIG. 3will be omitted, and the overlapping components will be denoted by the same reference numerals.

Referring toFIG. 4, the additional insulating part16′ of the thin film type inductor200may be formed only on upper surfaces of respective coil patterns. The additional insulating part16′ may be formed only on the upper surfaces of the coil patterns but is not formed on an upper or side surface of an insulating part14, such that there is no double insulation effect, but a thickness of the insulating layer may be entirely decreased. A spare space in which a magnetic material11may be filled may be further secured corresponding to a decrease in thickness of the insulating layer as compared to an inductor having the same size. As a result, permeability of the thin film type inductor may be improved. Here, the additional insulating part16′ has a uniform thickness, and the thickness of the additional insulating part16′ may be preferably 1 μm or more to 10 μm or less. When the thickness of the additional insulating part16′ is thinner than 1 μm, it may be difficult to secure insulation reliability between the coil pattern and the magnetic material11, and when the thickness of the additional insulating part16′ is thicker than 10 μm, the space in which the magnetic material11may be filled may be insufficient. A method of forming the additional insulating part16′ is not limited, but in order to insulate only the upper surfaces of the coil patterns, for example, a method of forming an oxide layer may be applied.

Since the additional insulating part16′ insulates only the upper surfaces of the coil patterns, an upper surface of the insulating part14may come in direct contact with the magnetic material11.

Next,FIG. 5is a schematic cross-sectional view of a modified example of the thin film type inductor ofFIG. 3. A thin film type inductor300ofFIG. 5is substantially equal to the thin film type inductor100ofFIG. 3except that an insulation structure including an insulating part and an additional insulating part is different. For convenience of explanation, a description of components overlapping those of the thin film type inductor100ofFIG. 3will be omitted, and the overlapping components will be denoted by the same reference numerals.

Referring toFIG. 5, an insulator17may be disposed along surfaces of coil patterns. The insulator17may insulate the coil patterns and a magnetic material11from each other while insulating a plurality of coil patterns from each other. A method of forming the insulator17is not limited, but for example, the insulator17may be formed by depositing a parylene resin, or the like, on the surface of the coil pattern using a chemical vapor deposition method. A thickness of the insulator17may be uniformly formed. Here, the term “uniform thickness” means that a width of the insulator insulating between the coil patterns and a thickness of the insulator insulating the upper surfaces of the coil pattern are substantially equal to each other.

A method of forming the insulator17is not particularly limited, but in the thin film type inductor100ofFIG. 3, the insulating part disposed before forming the coil patterns by plating is removed after the coil pattern is formed by the plating and subsequently, the insulator17may be formed using a chemical vapor deposition method.

Since the insulator17insulates the coil patterns at a relative thin thickness along the surfaces of the coil patterns, a space in which the magnetic material11may be filled may be relatively sufficiently secured. Particularly, since the magnetic material11as well as the insulator17may be disposed on inclined surfaces of upper regions1312cof upper and lower connection patterns131c,132c, respectively, a filling rate of the magnetic material in the vicinity of the center of the core may be increased. Further, in the vicinity of the center of the core, a case in which a flow of a magnetic flux is not smooth due to an increase in magnetic flux density may frequently occur, but the flow of the magnetic flux may be controlled to be optimized along the inclined surfaces of the upper and lower connection patterns131c,132c.

With the above-mentioned thin film type inductor, particularly, a plating deviation of coil patterns may be decreased in a power inductor field requiring an ultra small size and high inductance, and the flow of the magnetic flux in the vicinity of the center of the core and the filling rate may be improved. Since there is no need to add a new process line at the time of deriving the structure of the thin film type inductor, it may be easy to change a design. Requirements for a limit size for preventing the open failure of the via or facility restrictions may be satisfied, and at the same time, a deviation between the coil pattern and the connection pattern connected to the via may be significantly decreased.

As set forth above, according to exemplary embodiments in the present disclosure, the thin film type inductor capable of increasing the filling rate of the magnetic material in the center of the core of the coil and decreasing the plating deviation between the coil patterns by decreasing the size of the coil pattern connected to the via may be provided.