Magnetic core inductor chip and method of making the same

A magnetic core inductor chip includes a core and a coil. The core is in the form of a single piece of a magnetic material. The coil is deposited on and surrounds the core and has structural characteristics indicative of the coil being formed on the core by deposition techniques. Methods for making the magnetic core inductor chip are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 104120531, filed on Jun. 25, 2015.

FIELD

The disclosure relates to an inductor chip and a method of making the same, more particularly to a magnetic core inductor chip with a core made from a magnetic material and a coil deposited on the core.

BACKGROUND

There are three types of inductors namely thin film type inductors, multilayered type inductors, and wire wound type inductors, which are commercially available.

TW patent NO. 1430300 discloses a multilayered type inductor which includes a plurality of insulator layers, and a plurality of patterned metal layers. The insulating layers and the patterned metal layers cooperatively define a core and a coil of the multilayered type inductor.

A method of making the multilayered type inductor includes steps of: plating the patterned metal layers on the corresponding insulating layers; forming holes in each of the insulating layers; and filling a conducting material into the holes such that the patterned metal layers are electro-connected to one another through the conducting material.

The aforesaid method is relatively complicated. In order to simplify the structure of the multilayered type inductor and the method of making the same, TW patent application publication No. 201440090 A discloses a magnetic multilayered type inductor (seeFIG. 1) and a method of making the same.

The method of making the multilayered type inductor includes the steps of: laminating a first circuit plate110, a second circuit plate120, a third circuit plate130and a fourth circuit plate140(seeFIG. 2A); attaching an assembly of a supporting film150and a bonding pad circuit160to the first circuit plate110(seeFIG. 2B); transferring the bonding pad circuit160from the supporting film150to the first circuit plate110(seeFIG. 2C); removing the supporting film150from the bonding pad circuit160(seeFIG. 2D); sintering the first, second, third and fourth circuit plates110,120,130,140and the bonding pad circuit160so as to form a multilayered substrate100(seeFIG. 2E); and scribing the multilayered substrate100using a scriber170(seeFIG. 2F), such that the multilayered substrate100can be broken into a plurality of multilayered type inductors10(seeFIG. 1).

Referring toFIG. 1, each of the first, second, third and fourth circuit plates110,120,130,140includes a respective one of non-magnetic bodies111,121,131,141and a respective one of first, second, third and fourth circuit patterns112,122,132,142. Formation of the first, second, third and fourth circuit plates110,120,130,140requires numerous steps (a total of at least 13 steps), including punching each non-magnetic body111,121,131,141to form the holes, filling the conductive paste in the holes, forming the first, second, third and fourth circuit patterns112,122,132,142and sintering, before laminating the first, second, third and fourth circuit plates110,120,130,140.

The magnetic multilayered inductor thus formed has undesired non-ohmic contact and Joule-heating, which may be induced at the interfaces between every two adjacent ones of the first, second, third and fourth circuit patterns112,122,132,142.

SUMMARY

Therefore, an object of the disclosure is to provide a magnetic core inductor chip that can alleviate at least one of the drawbacks of the prior art.

According to the disclosure, the magnetic core inductor chip includes a core and a coil.

The core is in the form of a single piece of a magnetic material.

The coil is deposited on and surrounds the core and has structural characteristics indicative of the first coil being formed on the core by deposition techniques.

Another object of the disclosure is to provide methods of making a magnetic core inductor chip that can overcome at least one of the aforesaid drawbacks of the prior art.

According to the disclosure, a method of making a magnetic core inductor chip includes:

forming at least one first patterned photoresist layer on a magnetic wafer such that the magnetic wafer has an etched portion exposed from the first patterned photoresist layer, the first patterned photoresist layer having a peripheral end part and at least one passive-component-defining unit, the passive-component-defining unit having a connecting part connected to the peripheral end part, a plurality of breaking-line-defining protrusions protruding from the connecting part, and a plurality of chip-defining parts;

etching the etched portion to pattern the magnetic wafer so as to form a magnetic patterned wafer; and

removing the first patterned photoresist layer from the magnetic patterned wafer, such that the magnetic patterned wafer has a peripheral end portion and at least one passive-component unit that includes a connecting portion, a breaking line, and a plurality of spaced apart chip bodies, the connecting portion being connected to the peripheral end portion, the breaking line having a plurality of connecting tabs that are spaced apart from one another, each of the connecting tabs being disposed between and interconnecting the connecting portion and a respective one of the chip bodies;

forming a seed layer on each of the chip bodies of the magnetic patterned wafer, such that the seed layer is disposed on and around each of the chip bodies;

forming a second patterned photoresist layer on the seed layer on each of the chip bodies, such that the seed layer has a exposed region that is exposed from the second patterned photoresist layer, and a covered region that is covered with the seed layer;

depositing a metal layer on the exposed region of the seed layer so as to form a coil on and around each of the chip bodies of the magnetic patterned wafer through deposition techniques;

removing the covered region of the seed layer from the magnetic patterned wafer; and

breaking the magnetic patterned wafer along the breaking line so as to form a plurality of magnetic core inductor chips.

According to the disclosure, another method of making a magnetic core inductor chip includes:

providing a punching die having a plurality of die holes that are arranged in an array;

punching a magnetic wafer using the punching die so as to form a magnetic patterned wafer that has a peripheral end portion and at least one core chip unit, the core chip unit including a connecting portion, a breaking line, and a plurality of spaced apart chip bodies, the connecting portion being connected to the peripheral end portion and being spaced apart from the chip bodies by a tab-accommodating space along a direction, the breaking line having a plurality of connecting tabs that are spaced apart from one another and that are disposed in the tab-accommodating space, each of the connecting tabs interconnecting the connecting portion and a respective one of the chip bodies;

forming a seed layer on each of the chip bodies of the magnetic patterned wafer, such that the seed layer is disposed on and around each of the chip bodies;

forming a patterned photoresist layer on the seed layer on each of the chip bodies, such that the seed layer has a exposed region that is exposed from the patterned photoresist layer, and a covered region that is covered with the patterned photoresist layer;

depositing a metal layer on the exposed region of the seed layer so as to form a coil on and around each of the chip bodies of the magnetic patterned wafer through deposition techniques;

removing the covered region of the seed layer from the magnetic patterned wafer; and

breaking the magnetic patterned wafer along the breaking line so as to form a plurality of magnetic core inductor chips.

DETAILED DESCRIPTION

Referring toFIG. 3, a first embodiment of a magnetic core inductor chip according to the disclosure includes a core2and a first coil3.

The core2is in the form of a single piece of a magnetic material.

The first coil3is deposited on and surrounds an outer surface of the core2, and has structural characteristics indicative of the first coil3being formed on the core2by deposition techniques.

The core2further has top and bottom surfaces21,22, and two opposite side surfaces23extending from the top surface21to the bottom surface22. The first coil3surrounds the top and bottom and side surfaces21,22,23of the core2.

The magnetic material is selected from the group consisting of a magnetic metal material and a magnetic ceramic material. The magnetic metal material is selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The magnetic ceramic material is, e.g., magnetite (Fe3O4) with an inverse spinel structure. Since the core2is a single piece, it has an excellent mechanical strength, and does not induce the non-ohmic contact as encountered in the prior art.

It should be noted that, in this embodiment, the core2may have a size ranging from 0.2 mm×0.1 mm×0.1 mm to 0.6 mm×0.3 mm×0.3 mm. In certain embodiments, the core2may have a size ranging from 0.2 mm×0.1 mm×0.1 mm to 0.4 mm×0.2 mm×0.2 mm.

In certain embodiments, the first coil3includes a first seed layer (not shown) deposited on the core2, and a first metal layer (not shown) that is deposited on the first seed layer through deposition techniques, e.g., plating techniques.

Referring toFIG. 4, a second embodiment of the magnetic core inductor chip according to the disclosure differs from the first embodiment in that the core2of the second embodiment further includes a plurality of spaced apart notches24that are indented inwardly from the side surfaces23. The first coil3extends into and through the notches24.

Referring toFIG. 5, a third embodiment of the magnetic core inductor chip according to the disclosure differs from the first embodiment in that the core2of the third embodiment further includes a plurality of spaced apart holes25that extend through the top surface21and the bottom surface22and that are disposed between the side surfaces23. The first coil3extends into and through the holes25.

Referring toFIGS. 6 and 7, a fourth embodiment of the magnetic core inductor chip according to the disclosure differs from the first embodiment in that the fourth embodiment further includes an insulator layer5and a second coil4. The insulator layer5is disposed on and encloses the first coil3and the core2, and the second coil4is disposed on and surrounds the insulator layer5at a position corresponding to the position of the first coil3.

In certain embodiments, the second coil4includes a second seed layer (not shown) deposited on the insulator layer5, and a second metal layer (not shown) that is deposited on the second seed layer through deposition techniques, e.g., plating techniques.

It is noted that the production of the magnetic core inductor chip of the disclosure may use MEMS manufacturing techniques.

The following description illustrates a method of making the magnetic core inductor chip of the first embodiment of the disclosure, and should not be construed as limiting the scope of the disclosure. The method includes the steps of S1to S8.

In step S1(seeFIGS. 8,9 and 10), at least one first patterned photoresist layers71is formed on a magnetic wafer60, such that the magnetic wafer60has an etched portion600exposed from the first patterned photoresist layer71. The first patterned photoresist layer71has a peripheral end part711and at least one passive-component-defining unit712, the passive-component-defining unit712having a connecting part7121connected to the peripheral end part711, a plurality of breaking-line-defining protrusions7122protruding from the connecting part7121, and a plurality of chip-defining parts7123.

As shown inFIG. 9, each of the breaking-line-defining protrusions7122are aligned with a respective one of the chip-defining parts7123in a first direction (X) and having a width (D3) smaller than that (D5) of the respective one of the chip-defining parts7123in a second direction (Y) that is perpendicular to the first direction (X).

In the method of making the first embodiment, two first patterned photoresist layers71are respectively formed on top and bottom surfaces603,604of the wafer60, and the first patterned photoresist layers71formed on the top and bottom surfaces are symmetrical to each other (seeFIG. 10).

It should be noted that each of the breaking-line-defining protrusions7122may be connected to or spaced apart from a respective one of the chip-defining parts7123.

As shown inFIGS. 9 and 10, in this embodiment, each of the breaking-line-defining protrusions7122is spaced apart from a respective one of the chip-defining parts7123. As such, the etched portion600of the magnetic wafer60is designed to have a plurality of to-be-fully-etched regions601and a plurality of to-be-partially-etched regions602. Each of the breaking-line-defining protrusions7122is spaced apart from a respective one of the chip-defining parts7123by a gap713. The gaps713which are defined by the breaking-line-defining protrusions7122and the chip-defining parts7123are respectively aligned with the to-be-partially-etched regions602so as to expose the to-be-partially-etched regions602therefrom. Since the to-be-partially-etched regions602have a width (D2) in the first direction (X) significantly less than that (D1) of the to-be-fully-etched regions601in the second direction (Y), the to-be-partially-etched regions602have an etching rate lower than that of the to-be-fully-etched regions601.

As mentioned above, the first patterned photoresist layers71formed on the top and bottom surfaces603,604are symmetrical to each other, so that the to-be-partially-etched regions602and the to-be-fully-etched regions601of the top surface603are symmetrical to the to-be-partially-etched regions602and the to-be-fully-etched regions601of the bottom surface604.

As shown inFIG. 11, in step S2, the etched portion600is etched by chemical etching or sandblasting so as to pattern the magnetic wafer60. In detail, the to-be-partially-etched regions602and the to-be-fully-etched regions601of the top and bottom surfaces603,604of the magnetic wafer60are simultaneously etched, such that the magnetic wafer60is patterned so as to form a magnetic patterned wafer61.

In step S3(seeFIGS. 12 and 13), the first patterned photoresist layer71is removed from the magnetic patterned wafer61. The magnetic patterned wafer61has a peripheral end portion610and at least one passive-component unit611that includes a connecting portion6111, a breaking line6112, and a plurality of spaced apart chip bodies2. The connecting portion6111is connected to the peripheral end portion610. The breaking line6112has a plurality of connecting tabs6114that are spaced apart from one another. Each of the connecting tabs6114is disposed between and interconnects the connecting portion6111and a respective one of the chip bodies2.

It is noted that each of the chip bodies is to serve as the core2(seeFIG. 3) of the magnetic core inductor chip according to the present disclosure.

The shape of the connecting tabs6114thus formed can be controlled based on actual requirements by varying the shape of the breaking-line-defining protrusions7122. In one embodiment, referring back toFIGS. 11 and 12, each of the breaking-line-defining protrusions7122is disposed between the respective one of the chip-defining parts7123and the connecting part7121, and is reduced in width (D3) from the respective connecting part7121toward the corresponding one of the chip-defining parts7123, so that each of the connecting tabs6114thus formed is correspondingly reduced in width (D4) from the connecting portion6111toward the respective one of the chip bodies2.

In step S4(seeFIG. 14), a first seed layer31is formed on each of the chip bodies2of the magnetic patterned wafer61, such that the first seed layer31is disposed on and around each of the chip bodies2.

In step S5(seeFIG. 15), a second patterned photoresist layer73is formed on the first seed layer31, such that the first seed layer31has a first exposed region311that is exposed from the second patterned photoresist layer73, and a first covered region312that is covered with the second patterned photoresist layer73.

In step S6(seeFIGS. 15 and 16), a first metal layer32is deposited on the first exposed region311of the first seed layer31so as to form a first coil3on and around each of the chip bodies2of the magnetic patterned wafer61through deposition techniques.

The first seed layer31may be made from a catalytically active material (e.g., a catalytically active metal) or a conductive material. When the first seed layer31is made from the catalytically active material, the first metal layer32is formed through chemical plating (or electroless plating) techniques. When the first seed layer31is made from the conductive material, the first metal layer32is formed through electro-plating techniques. The catalytically active material is selected from the group consisting of Pt, Pd, Au and Ag. The conductive material is selected from the group consisting of Cr, Ni, Ti, W and Mo.

In step S7(seeFIG. 17), the first covered region312of the first seed layer31(seeFIG. 15) is removed from the magnetic patterned wafer61.

It should be noted that the second patterned photoresist layer73(seeFIG. 15) is also removed after the deposition of the first metal layer.

In step S8(seeFIG. 18), the patterned wafer61is broken along the breaking line6112by applying an external force thereto so as to form a plurality of magnetic core inductor chips20. Alternatively, the magnetic patterned wafer61may be broken along the breaking line6112using a scriber (not shown) or using etching techniques.

In certain embodiments, when the magnetic wafer60is made from a metal, an insulator film (not shown) is needed to be formed on each of the chip bodies2before the deposition of the first seed layer31thereon so as to prevent short-circuit between each of the chip bodies2and the first coil3.

Referring toFIG. 19, the method of making the magnetic core inductor chip of the second embodiment (seeFIG. 4) differs from the method of making the first embodiment in that the former further includes forming a plurality of notch-defining grooves7125that are intended inwardly from side faces7124of each chip-defining part7123, so that after step S2, each of the chip bodies2of the magnetic patterned wafer61is formed with a plurality of notches24and that the first coil3is formed to extend into and through the notches24(seeFIG. 4).

Referring toFIG. 20, the method of making the magnetic core inductor chip of the third embodiment (seeFIG. 5) differs from the method of making the first embodiment in that the former further includes forming a plurality of hole-defining through-holes7126extending through top face7127and bottom face (not shown), and disposed between side faces7124of each of the chip-defining parts7123, so that after step S2, each of the chip bodies2of the magnetic patterned wafer61is formed with a plurality of spaced apart holes25extending through top and bottom surfaces21,22of the core2and disposed between the side surfaces23of the core2, and that the first coil3is formed to extend into and through the holes25(seeFIG. 5).

Referring toFIGS. 21 to 24, the method of making the magnetic core inductor chip of the fourth embodiment differs from the method of making the first embodiment in that the former further includes: forming an insulator layer5on the first coil3and on each of the chip bodies2; forming a second seed layer41on the insulator layer5; forming a third patterned photoresist layer74on the second seed layer41, such that the second seed layer41has a second exposed region411that is exposed from the third patterned photoresist layer74, and a second covered region412that is covered with the third patterned photoresist layer74; depositing a second metal layer42on the second exposed region411of the second seed layer41so as to form a second coil4(seeFIG. 6) on the insulator layer5through deposition techniques (e.g., plating techniques); and removing the third patterned photoresist layer74and the second covered region412of the second seed layer41from the insulator layer5.

The second seed layer41may be made from a catalytically active material or a conductive material. When the second seed layer41is made from the made from the catalytically active material, the second metal layer42is formed through chemical plating (or electroless plating) techniques. When the second seed layer41is made from the conductive material, the second metal layer42is formed through electro-plating techniques. The catalytically active material is selected from the group consisting of Pt, Pd, Au and Ag. The conductive material is selected from the group consisting of Cr, Ni, Ti, W and Mo.

Another method of making the magnetic core inductor chip of the first embodiment of the disclosure is illustrated in the following. The method includes the steps of s1to s7.

In step s1(seeFIG. 25), a punching die8having a plurality of die holes81that are arranged in an array is provided.

In step s2(seeFIGS. 26 and 27), a magnetic wafer60is punched using the punching die8so as to form a magnetic patterned wafer61that has a peripheral end portion (not shown) and at least one passive-component unit611, the passive-component unit611including a connecting portion6111, a breaking line6112, and a plurality of spaced apart chip bodies2. The connecting portion6111is connected to the peripheral end portion (not shown), and is spaced apart from the chip bodies2by a tab-accommodating space (not shown) along a first direction (X). Similar to the structure shown inFIG. 13, the breaking line6112has a plurality of connecting tabs6114that are spaced apart from one another and that are disposed in the tab-accommodating space (not shown). Each of the connecting tabs6114interconnects the connecting part6111and a respective one of the chip bodies2.

In step s3(seeFIG. 28), a first seed layer31is formed on each of the chip bodies2of the magnetic patterned wafer61, such that the first seed layer31is disposed on and around each of the chip bodies2.

In step s4(seeFIG. 29), a second patterned photoresist layer73is formed on the first seed layer31, such that the first seed layer31has a first exposed region311that is exposed from the second patterned photoresist layer73, and a first covered region312that is covered with the second patterned photoresist layer73.

In step s5(seeFIG. 30), a first metal layer32is deposited on the first exposed region311of the first seed layer31so as to form a first coil3on and around each of the chip bodies2of the magnetic patterned wafer61through plating techniques.

In step s6(seeFIG. 31), the second patterned photoresist layer73and the first covered region312of the first seed layer31is removed from the magnetic patterned wafer61.

In step s7(seeFIG. 32), the magnetic patterned wafer61is broken along the breaking line6112so as to form a plurality of magnetic core inductor chips20.

The magnetic wafer60may be made from a magnetic metal material or a magnetic ceramic green. When the magnetic wafer60is made from the magnetic ceramic green, the method further comprises sintering the chip bodies2after the chip bodies2are separated from the connecting portion6111.

In summary, the methods of the present disclosure may be advantageous over the prior art in reducing the steps of making the magnetic core inductor chip.

Furthermore, the core2of the magnetic core inductor chip of the present disclosure is in the form of a single piece. As such, the core2of the magnetic core inductor chip of the present disclosure has a higher mechanical strength than that of the conventional multilayered type inductor.