COMPOSITE WIRE, METHOD FOR PREPARING SAME, AND METHOD FOR PREPARING POWER INDUCTOR

Abstract

A composite wire includes a metal inner core, an easily-passivated metal layer wrapping a surface of the metal inner core, and a self-adhesive resin layer wrapping a surface of the easily-passivated metal layer. An insulation layer of the composite wire is a metal passivation layer that is formed by the easily-passivated metal layer obtained after sintering treatment and oxidation. The preparation method is used for manufacturing the composite wire. The method for preparing a power inductor is used for preparing a new type of power inductor including the composite wire. The composite wire is high-temperature resistant and is easily wound. During winding, the easily-passivated metal layer is unlikely to fall off, thereby ensuring that the insulation layer formed by passivation of the easily-passivated metal layer has desirable weather resistance and voltage resistance.

Claims

1. A composite wire, comprising a metal inner core, an easily-passivated metal layer wrapping a surface of the metal inner core, and a self-adhesive resin layer wrapping a surface of the easily-passivated metal layer, wherein the easily-passivated metal layer has the following feature: after being sintered, the easily-passivated metal layer could be oxidized to form a metal passivation layer to serve as an insulation layer.

2. The composite wire according to claim 1, wherein the metal inner core is a nickel-plated copper wire which is formed by plating nickel on a surface of a copper wire by electroplating or electroless plating, and a nickel-plated layer has a thickness of 1/10 to 3/10 of a diameter of the copper wire.

3. The composite wire according to claim 2, wherein the easily-passivated metal layer is aluminum or chromium, is plated on a surface of the nickel-plated copper wire by electroplating or PVD, and has a thickness of 1/10 to 3/10 of the diameter of the copper wire; and after being sintered at a temperature of 600 C. to 900 C., the easily-passivated metal layer is oxidized on the surface of the nickel-plated copper wire to form the metal passivation layer.

4. The composite wire according to claim 1, wherein the self-adhesive resin layer is nylon and is formed on the surface of the easily-passivated metal layer by performing coating and drying for multiple times.

5. A method for preparing the composite wire according to claim 1, comprising the following steps S1 to S3: S1: providing a metal inner core to serve as a conductor of the composite wire; S2: plating an easily-passivated metal layer on a surface of the metal inner core and controlling the thickness of the easily-passivated metal layer to be within a predetermined range; and S3: coating a self-adhesive resin layer on a surface of the easily-passivated metal layer; wherein, the easily-passivated metal layer formed in the step S2 has the following feature: after being sintered, the easily-passivated metal layer could be oxidized to form a metal passivation layer to serve as an insulation layer.

6. The method for preparing the composite wire according to claim 5, wherein the metal inner core is a nickel-plated copper wire which is formed by plating nickel on a surface of a copper wire by electroplating or electroless plating, and a nickel-plated layer has a thickness of 1/10 to 3/10 of a diameter of the copper wire.

7. The method for preparing the composite wire according to claim 6, wherein the easily-passivated metal layer is aluminum or chromium, is plated on a surface of the nickel-plated copper wire by electroplating or PVD, and has a thickness of 1/10 to 3/10 of the diameter of the copper wire; and after the easily-passivated metal layer is sintered at a temperature of 600 C. to 900 C., the easily-passivated metal layer forms the metal passivation layer on the surface of the nickel-plated copper wire.

8. The method for preparing the composite wire according to claim 5, wherein the step S3 specifically comprises: evenly applying a self-adhesive resin paint on the surface of the easily-passivated metal layer by felt dip-coating, with a thickness of 1 m to 2 m for each application, and repeating the application and drying operations at a temperature of 80 C. to 150 C. multiple times, so as to form the self-adhesive resin layer.

9. A method for preparing a power inductor, comprising the following steps A to E: A: preparing the composite wire according to claim 1, comprising the following steps S1 to S3: S1, providing a metal inner core to serve as a conductor of the composite wire; S2, plating an easily-passivated metal layer on a surface of the metal inner core and controlling the thickness of the easily-passivated metal layer to be within a predetermined range; wherein, the easily-passivated metal layer has the following feature: after being sintered, the easily-passivated metal layer could be oxidized to form a metal passivation layer to serve as an insulation layer; S3, coating a self-adhesive resin layer on a surface of the easily-passivated metal layer; B: winding the composite wire prepared in the step A, according to a predetermined shape and a predetermined coil quantity, so as to form coils; C: placing the coils into a mold cavity, adding metal soft magnetic powder to the mold cavity, and pressing the metal soft magnetic powder and the coils to form a base comprising the coils; D: performing sintering treatment on the base at a temperature of 600 C. to 900 C., wherein during the sintering treatment, an outermost self-adhesive resin layer on the composite wire is carbonized and oxidized to form a gas to be discharged, and at the same time, the easily-passivated metal layer is oxidized to form the metal passivation layer; and E: plating two terminal electrodes on two ends of the base processed in the step D, wherein the two terminal electrodes are respectively connected to two end portions of the coils, so as to form the power inductor.

10. The method for preparing a power inductor according to claim 9, wherein when the composite wire is prepared in the step A, the metal inner core used is a silver wire, an aluminum wire, or a nickel-plated copper wire, the easily-passivated metal layer is aluminum or chromium, and after the sintering treatment is performed on the easily-passivated metal layer in the step D, an aluminum oxide layer or a chromic oxide layer is correspondingly generated to wrap the surface of the metal inner core.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a schematic structural diagram of a composite wire comprising an easily-passivated metal layer according to the present application; and

[0032] FIG. 2 is a schematic structural diagram of a power inductor using the composite wire in the present application.

DETAILED DESCRIPTION

[0033] The following further describes the present application with reference to the accompanying drawings and preferred implementations.

[0034] An embodiment of the present application provides a composite wire comprising an easily-passivated metal layer. The composite wire comprises a metal inner core, an easily-passivated metal layer wrapping a surface of the metal inner core, and a self-adhesive resin layer wrapping a surface of the easily-passivated metal layer. An insulation layer of the composite wire is a metal passivation layer that is formed by the easily-passivated metal layer after sintering treatment and oxidation.

[0035] The metal inner core of the composite wire may be, for example, a silver wire, an aluminum wire, or a nickel-plated copper wire, and the nickel-plated copper wire is preferably used because the nickel-plated copper wire has better high-temperature resistance and conductive performance is less affected by a high temperature. When the nickel-plated copper wire is used as the metal inner core in the composite wire, for an internal structure of the composite wire, reference may be made to FIG. 1. It is sequentially a copper wire 10, a nickel layer 20, an easily-passivated metal layer 30, and a self-adhesive resin layer 40 from the inside to the outside of the structure. The nickel-plated copper wire is formed by plating the nickel layer 20 on a surface of the copper wire 10 by electroplating or electroless plating, and the plated nickel layer 20 preferably has a thickness of 1/10 to 3/10 of a diameter of the copper wire 10.

[0036] In a preferred embodiment, a material of the easily-passivated metal layer 30 is aluminum or chromium, and the easily-passivated metal layer is plated on the surface of the metal inner core by electroplating or PVD. Referring to FIG. 1, when the metal inner core is the nickel-plated copper wire, the easily-passivated metal layer 30 is formed on a surface of the nickel layer 20, and has a thickness of 1/10 to 3/10 of the diameter of the copper wire 10. After being sintered at a temperature of 600 C. to 900 C., the easily-passivated metal layer 30 could be oxidized on the surface of the metal inner core, for example, the nickel-plated copper wire, to form a metal passivation layer. The metal passivation layer is an oxide of easily-passivated metal, for example, an aluminum oxide or a chromic oxide. When the easily-passivated metal is chromium, a main component of the metal passivation layer is Cr.sub.2O.sub.3. The metal passivation layer formed after the sintering treatment by the easily-passivated metal layer 30 is the insulation layer of the composite wire.

[0037] Another embodiment of the present application provides a method for preparing the foregoing composite wire. The method comprises the following steps S1 to S3:

[0038] S1: Provide a metal inner core to serve as a conductor of the composite wire. As described above, the metal inner core may mainly be a silver wire, an aluminum wire, or a nickel-plated copper wire that has a more stable resistance at a high temperature, and may alternatively be another common conductor.

[0039] S2: Plate an easily-passivated metal layer on a surface of the metal inner core and control the thickness of the easily-passivated metal layer to be within a predetermined range. For example, when the metal inner core is a nickel-plated copper wire, the easily-passivated metal layer has a thickness of 1/10 to 3/10 of a diameter of the copper wire.

[0040] S3: Coat a self-adhesive resin layer on a surface of the easily-passivated metal layer. The self-adhesive resin layer may be, for example, nylon, and is formed on the surface of the easily-passivated metal layer by performing coating and drying for multiple times. For example, a specific operation comprises: evenly applying a self-adhesive resin paint on the surface of the easily-passivated metal layer by felt dip-coating, with a thickness 1 m to 2 m for each application, and repeating the application and drying operations at a temperature of 80 C. to 150 C. multiple times to form the self-adhesive resin layer.

[0041] A specific embodiment of the present application provides a new type of power inductor. In the power inductor, the foregoing composite wire is used as coils. As shown in FIG. 2, the power inductor comprises: a base 100, coils 200 inside the base, and terminal electrodes 301 and 302 respectively connected to two ends of the coils. A method for preparing the power inductor is specifically as follows:

[0042] Step A: Preparing the composite wire according to the method for preparing the composite wire disclosed in the foregoing embodiment;

[0043] Step B: winding the composite wire prepared in the step A to form the coils of the power inductor, according to a predetermined shape and a predetermined coil quantity;

[0044] Step C: placing the coils into a mold cavity, adding metal soft magnetic powder to the mold cavity, and pressing the metal soft magnetic powder and the coils to form a base comprising the coils;

[0045] Step D: performing sintering treatment on the base at a temperature of 600 C. to 900 C., where during the sintering treatment, an outermost self-adhesive resin layer on the composite wire is carbonized and oxidized to form a gas to be discharged, and at the same time, the easily-passivated metal layer is oxidized to form the metal passivation layer; and

[0046] Step E: plating two terminal electrodes on two ends of the base processed in step D, where the two terminal electrodes are respectively connected to two end portions of the coils, so as to form the power inductor.

[0047] After step D is completed, if a coil protrudes from an outer surface of two ends of the base, grinding and polishing are performed, and terminal electrodes are plated subsequently.

[0048] The foregoing content is merely detailed descriptions made on the present application by using specific preferred embodiments, and it should not be understood that specific embodiments of the present application are limited to these descriptions. A person skilled in the art may further make several equivalent replacements or obvious variations without departing from the idea of the present application to achieve the same performance or purposes, and such replacements and variations shall fall within the protection scope of the present application.

[0049] Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.