JPH11283857A - Manufacture of coil part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the manufacturing method of a coil part, by which defective soldering caused by the bonding part for an insulating covered conductor and an external connecting electrode can be prevented, the conductor is embedded in the connecting electrode and the connection to the outside can be stably and securely made. SOLUTION: This manufacturing method of a coil part comprises the processes. In the low-pressure compressing process, an insulating covered conductor 3 is compressed with respect to an electrode 4 at the temperature higher than the melting temperature of in insulating film 3b of the insulating covered conductor 3 with the relatively low pressure, when the insulating covered conductor is connected to the electrode of a coil part. In the high-pressure compressing part, a compression with relatively high pressure is performed for the insulating covered conductor 3, so that a conductor 3a is flattened for the electrode 4 and the conductor 3a is embedded in the electrode 4 following the low-pressure compressing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a coil component used for forming, for example, an inductance component, and more particularly, to a method in which a winding composed of an insulated conductor is formed on a core. The present invention relates to a method for manufacturing a coil component having an improved method of joining to an electrode.

[0002]

2. Description of the Related Art Conventionally, coil components have been used in various electronic circuits to generate various inductance components. As this type of coil component, there is known a coil component in which an insulated conductor is wound around a core made of magnetic or insulating ceramics or plastic to form a winding portion. Here, electrodes are formed on the outer surface of the core on both sides of the winding portion, and both ends of the insulated conductor are connected to these electrodes, respectively.

[0003] By the way, the above-mentioned insulated wire is usually C
It has a structure in which an insulating coating made of polyesterimide or the like is formed on the outer surface of a conductive wire made of a metal such as u. Also, the bonding of the insulating-coated conductor to the electrode has conventionally been performed by a pulse heating method. this,
This will be described with reference to FIG.

[0006] FIG. 6 is a sectional view showing a portion where an electrode 52 is formed on the upper surface of a core 51 of a coil component. First, the end of the insulated conductor 53 is placed on the electrode 52. Note that, in the insulation-coated conductor 53, an insulation coating 53b is formed around the conductor 53a.

Next, the pressure tip 56 heated to about 500 ° C. is lowered, and the insulation-coated lead wire 53 is pressed against the electrode 52. By this pressurization, the conducting wire 53a is flattened, and the conducting wire 53a and the electrode 52 are thermally pressed to complete the joining.

In the above joining method, the electrode 52 is made of Ag, C
When made of a high melting point metal such as u or Ni, the insulating coating 53b is melted at a temperature equal to or lower than the melting point of these electrode materials, so that the conducting wire 53a and the electrode 52 are directly joined. In addition, the conducting wire 53a is flattened by pressurization.

[0007]

However, the electrode 5
Even if the conducting wire 53a is flattened on the surface 2, a step occurs between the conducting wire 53a and the surface of the electrode 52. Therefore, the electrode 5
For example, when the surface side of No. 2 is a mounting surface for mounting a coil component on a printed circuit board, stability in mounting the coil component may be impaired, or the reliability of bonding by soldering may be low.

Further, in the electrode 52 of the coil component, an electrode layer formed by plating a low melting point metal such as Sn or solder is often formed on the surface in order to enhance solderability at the time of mounting. For example, as shown in FIG.
As the electrode 52, a base layer 52a formed by applying and baking an Ag paste on the surface of the core 51 is formed, and an N surface for preventing solder erosion is formed on the outer surface thereof.
A structure in which an i-plated layer 52b is formed and an electrode layer 52c made of a low melting point metal for improving solderability on the outermost surface is conventionally known.

In this case, since the pressure tip 54 is heated to about 500 ° C., the pressure tip 54 heats the electrode layer 52c to a temperature equal to or higher than the melting point of the low melting point metal. In addition, during joining, a sufficient pressure is applied to the rolling of the conductive wire 53a. Therefore, the insulating coating 53
b and the electrode layer 52c made of a low melting point metal provided on the surface are melted and liquefied, and the conductive wire 53a
Is rolled and flattened.

As a result, at the time of pressurization by the pressurizing tip 54, the liquefied low-melting metal is pushed to the side of the conductive wire 53a by the liquefied insulating coating 53b. Accordingly, when the melted insulating coating 53b is attached to the pressing tip 54 after displacing the low melting point metal material and is removed together with the pressing tip 54, the portion where the Ni plating layer 52b is exposed on the side of the conductive wire 53a. A sometimes occurred. Ni plating layer 5
When the coil component is mounted on the printed circuit board by soldering when the 2b is exposed, the Ni plating layer 52b
Has low solder wettability, which causes a mounting defect.

Alternatively, even when the Ni plating layer 52b is not exposed at the portion indicated by the arrow A, the molten insulating coating 53b pushes out the low-melting metal material and then presses the pressing tip 54b. And when removed together with the pressure tip 54, a crater-like depression 52d remains in the surface of the electrode 52 where the insulating coating 53b was present around the conducting wire 53a, thereby deteriorating the solderability. Sometimes I did.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, to prevent poor soldering due to a joint between an insulated conductor and an electrode for external connection, and to prevent the conductor from being used for connection. It is an object of the present invention to provide a method for manufacturing a coil component which is embedded in the electrode and can stably and reliably connect to the outside.

[0013]

According to the first aspect of the present invention, there is provided a core made of an insulating material, an insulated wire wound around the core, and an electrode formed on an outer surface of the core. A method for manufacturing a coil component in which an end of the insulated conductor is joined to the electrode, wherein the joining of the insulated conductor to the electrode is performed at a temperature not lower than a temperature at which the insulating coating of the insulated conductor is melted. And a low-pressure pressurizing step of pressing the insulating coated conductive wire against the electrode at a relatively low pressure, and, following the low-pressure pressing step, the conductive wire is buried so as to flatten the conductive wire, and the electrode. And a high-pressure pressurizing step of pressing the conductive wire against the electrode at a relatively high pressure.

According to the second aspect of the present invention, the temperature in the high-pressure pressing step is equal to or lower than the melting point of the electrode surface.
The temperature is higher than the freezing point. In the present invention, the high-pressure pressing step may be performed at a lower temperature than the low-pressure pressing step, or may be performed at a higher temperature.

Preferably, in the present invention, the electrodes of the coil component are formed on a base layer formed by applying and baking a conductive paste such as Ag, and on the surface of the base layer. A metal material having excellent solderability, for example, a solder erosion prevention layer made of Ni, and a metal material formed on the outer surface of the solder erosion prevention layer and having excellent solderability, such as Sn or solder. A soldering layer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing non-limiting embodiments of the present invention with reference to the drawings.

FIGS. 1A to 1D are cross-sectional views for explaining a method of manufacturing a coil component according to an embodiment of the present invention, and FIG. 2 is a sectional view obtained by the embodiment of the present invention. FIG. 5 is a perspective view for explaining a coil component to be used.

First, the structure of the chip coil component shown in FIG. 2 will be described. The chip-type coil component 1 has a core 2 made of an insulating material such as a dielectric material, a magnetic material, an insulating ceramic or plastics. The core 2 has a winding part 2a around which the insulated conductor 3 is wound, and electrode forming parts 2b and 2c thicker than the winding part 2a on both sides of the winding part 2a. In the winding part 2a, the insulated conductor 3 is wound. Also, the electrode forming part 2
On the upper surfaces of b and 2c, first and second electrodes 4 and 5 are formed for connection to the outside when used.

In the method of manufacturing a coil component according to the present embodiment, the above-described chip type coil component 1 is manufactured. The method is characterized by a step of joining the insulated conductor 3 to the first and second electrodes 4 and 5. The other steps can be performed according to a conventionally known method for manufacturing a coil component. That is, a step of winding the insulating coated conductor wire 3 around the outer surface of the core 2 to form a winding portion, and the electrode forming portions 2b and 2c of the core 2
The step of forming the electrodes 4 and 5 on the upper surface of the substrate can be performed according to a conventionally known method.

The feature of the method of manufacturing the chip-type coil component of this embodiment resides in the step of joining the end portions of the insulated wire 3 to the first and second electrodes 4 and 5, which is called the first electrode. An example in which the end of the insulated conductor 3 is joined to the upper surface 4 will be described.

First, as shown in FIG. 1 (a), an insulating-coated conductor 3 is arranged on a first electrode 4. First electrode 4
Are formed on the upper surface of the electrode forming portion 2b of the core 2 of the coil component. Further, the first electrode 4 includes a base layer 4a, N
It has a structure in which an i-plated layer 4b and a Sn-plated layer 4c are stacked. The base layer 4a is formed, for example, by applying and baking an Ag-containing conductive paste. However, the base layer 4a may be formed by other methods such as vapor deposition, plating, and sputtering.

On the base layer 4a, a Ni plating layer 4b is formed as a solder erosion preventing layer in order to prevent solder erosion. Note that Cu or Fe may be used instead of Ni.

On the outer surface of the Ni plating layer 4b, an Sn plating layer 4c is formed as an easily solderable layer in order to enhance solderability at the time of mounting. Instead of Sn, a plating layer may be formed of another material having excellent solderability, such as solder, to form a solderable layer.

In this embodiment, the insulated conductor 3 has a conductor 3a made of Cu and an insulation cover 3b formed to cover the outer peripheral surface of the conductor 3a. The insulating coating 3b is
It is composed of polyesterimide or the like. The temperature at which the insulating coating 3b made of polyesterimide is melted is 330 ° C. or higher.

When joining the insulated conductor 3 to the first electrode 4, the insulated conductor 3 is first placed on the first electrode 4 and the pressure tip 6 is lowered. Pressure tip 6
Is heated to a temperature equal to or higher than the temperature at which the insulating coating 3b of the insulating coating conductor is melted, and in this embodiment, equal to or higher than 500 ° C. Further, the pressure tip 6 is lowered so as to press the insulated wire 3 against the first electrode 4 at a relatively low pressure. The value of the pressure at the time of pressurization cannot be uniquely determined because it differs depending on the diameter and material of the insulated wire 3. For example, when the wire is made of Cu and has a wire diameter of 40 μm, about 30 to 30 μm is required. This is performed at a pressure of about 50 gF. Thus, the low-pressure pressurizing step of the present invention is performed.

In the low-pressure pressing step, since the pressing tip 6 is heated to a temperature higher than the temperature at which the insulating coating is melted, the insulating coating 3b is melted. Accordingly, as shown in FIG. 1B, the melted insulating coating 3b moves to both sides of the conducting wire 3a on the first electrode 4, and the lower surface of the conducting wire 3a is moved to the outermost side of the first electrode 4. It is in direct contact with the Sn plating layer 4c.

As shown in FIG. 1B,
In the low-pressure pressing step, since the pressure applied by the pressing tip 6 is low, the conductive wire 3a is hardly deformed. That is, the low-pressure pressurizing step is performed at such a pressure that the flattening of the conductive wire 3a hardly occurs.

In the low-pressure pressing step, the Sn plating layer 4
3C is not directly in contact with the pressure tip 6 and is applied in a relatively short time as shown in FIG. 3 because the applied pressure is small, so that the insulating coating 3b melts, but the Sn plating layer 4c hardly melts. In other words, the above pressure and pressurizing time are selected so that the insulating coating 3b is melted but the Sn plating layer 4c is not melted.

Next, following the low pressure pressurizing step, a high pressure pressurizing step of pressurizing at a relatively high pressure is performed. That is,
A high-pressure pressing step is performed so that the conductive wire 3a is flattened with respect to the first electrode 4 so that the conductive wire 3a is flattened and the conductive wire 3a is buried with respect to the first electrode 4. This is shown in FIG.
This will be described with reference to (c) and (d).

As shown in FIG. 1C, in the high-pressure pressing step, a further downward load is applied to the pressing tip 6 to
a is flattened. That is, the pressure applied by the pressure tip 6 in the high-pressure pressing step is set so that the conductive wire 3a is flattened and the conductive wire 3a is embedded in the first electrode 4. Therefore, the conducting wire 3a is flattened by the high-pressure pressing step, and as shown in FIG.
It is embedded in the first electrode 4.

The temperature in the high-pressure pressing step is preferably lower than the melting point of the first and second electrode surface portions, that is, lower than the melting point of the Sn plating layer 4c and higher than the freezing point. In the example, the temperature is 230 ° C. By setting the temperature in the high-pressure pressing step in this manner, the Sn plating layer 4c of the first electrode 4 can be softened, whereby the conductive wire 3a can be reliably embedded in the first electrode 4. it can.

It should be noted that the temperature in the high-pressure pressing step was changed to Sn
When the temperature is higher than the melting point of the plating layer 4c, the Sn plating layer 4c is melted in the high-pressure pressing step, the molten Sn is pushed away by the insulating coating 3b, and the Ni plating layer 4b is finally exposed. In some cases, a dent may occur after the insulating coating 3b is removed.

The magnitude of the pressure applied in the high-pressure pressurizing step also differs depending on the material and wire diameter of the conductive wire 3a, and therefore cannot be uniquely determined.
Is used, and when the wire diameter is 40 μm, about 300 g
It may be about F.

Next, by pulling up the pressure tip 6, the insulating coating 3b is removed while adhering to the bottom surface 6a of the pressure tip 6. As is clear from FIG. 1D, after the insulating coating 3b is removed, no depression remains on the surface of the first electrode 4, and the surface of the electrode 4 is flattened.

FIG. 3 shows temperature and pressure profiles in the low-pressure pressing step and the high-pressure pressing step. That is, as is clear from FIG. 3, it is necessary to carry out the high-pressure pressing step subsequent to the low-pressure pressing step. Even if they are joined, the surface of the electrode 4 is flattened.

Therefore, according to the manufacturing method of the present embodiment, the conductor 3a of the insulated conductor 3 is flattened and the first electrode 4
Since the surface of the first electrode 4 is buried in the inside, the surface of the first electrode 4 is flattened, so that the reliability of bonding by solder or the like when the coil portion is mounted on the printed circuit board can be improved. In addition, since the Sn plating layer 4c is reliably exposed around the conductor 3a, the solderability is excellent.

The high-pressure pressing step may be performed at a lower temperature than the low-pressure pressing step as in the above-described embodiment, but may be performed at a higher temperature than the low-pressure pressing step. . For example, when the insulating coating 3b is made of a urethane resin, the melting temperature of the urethane resin is 28
The temperature is about 0 ° C., and the urethane-based resin dissolves quickly, but since the heating is performed for a short time, the Sn plating layer does not soften. Therefore, in the low-pressure pressing step, by melting the insulating coating made of the urethane-based resin and in the high-pressure pressing step, the Sn plating layer is softened at a higher temperature, so that the conductive wire is formed in the same manner as in the above embodiment. It can be reliably embedded in the Sn plating layer of the electrode.

In the above embodiment, the first and second electrodes are formed on the base layer 4a made of the Ag conductive paste by Ni plating.
Although it has a structure in which the plating layer 4b and the Sn plating layer 4c are stacked, in the present invention, the first and second electrodes may be constituted by a single layer.

That is, the first and second electrodes are formed from a single metal material, and the above-described low-pressure pressing step and high-pressure pressing step are performed to join the insulated conductor to the first and second electrodes. May be. In this case, in the first low-pressure pressing step, as in the case of the above embodiment, the conductor is not so flattened, the insulating coating is melted and pushed to the side of the conductor. Then, as shown in FIG. 5, in the high-pressure pressing step, a relatively high pressure is applied by the pressing tip 6 so that the conductive wire 3a is embedded in the first electrode 24. The temperature in the high-pressure pressing step is such that the first electrode 24 made of a single material is softened so that the conductive wire 3a is embedded.
That is, the temperature is higher than the freezing point and lower than the melting point.

Also in this case, the insulating coating 3b is melted in the first low-pressure pressing step, moved to the side of the conductive wire 3a, and is placed on the bottom surface 6a of the pressing tip 6 after the next high-pressure pressing step. Attached and removed. Therefore, as shown on the right side in FIG. 5, after the high-pressure application step, the conducting wire 3a is joined to the first electrode 4, and the surface of this joint is flattened.

In the above-described embodiment, the coil component has a structure in which a pair of electrodes are formed at both ends of the core around which the insulated wire 3 is wound, to which the ends of the insulated wire 3 are joined. However, in the coil component manufactured according to the present invention, the electrode to which the insulated wire is joined is
The number of electrodes that may be formed only on one end side of the core 2 and to which the end of the insulated conductor is joined is not particularly limited.

Further, in the above-described embodiment, the temperature in the low pressure pressing step was selected so that the insulating coating 3b was melted but the Sn plating layer 4c, ie, the low melting point metal layer was hardly melted. The temperature in the step may be set at a temperature at which the low melting point metal layer is melted. That is, even if the low-melting metal layer is once melted in the low-pressure pressing step, the low-melting metal layer may be cooled so as to be in a softened state at or above its freezing point in the subsequent steps. 3a can be embedded in the electrode in the same manner as in the above embodiment. This cooling may be performed in the high-pressure pressurizing step, or may be performed as described above prior to the high-pressure pressurizing step.

The conductor 3a of the insulation-coated conductor 3 is
It can be configured using an appropriate metal material other than Cu, for example, Ag, Ni, or the like. Also, the insulating material constituting the insulating coating 3b is not limited to polyesterimide or urethane-based resin, but may be constituted by using another appropriate synthetic resin.

[0044]

According to the method for manufacturing a coil component according to the first aspect of the present invention, in the low-pressure pressurizing step, the pressure of the insulating-coated conductive wire with respect to the electrode is higher than the temperature at which the insulating coating is melted and relatively low. , Whereby the insulating coating is melted and moved to the side of the conductor. Next, in the high-pressure pressurizing step, a larger pressure is further applied to the conductor, and the conductor is flattened and embedded in the electrode. Therefore, the surface of the portion where the insulated conductor is joined to the electrode is flattened, and the insulated conductor is securely contacted with the electrode. Therefore, the reliability of the electrical connection can be improved, and the reliability of the joint by soldering when mounting on a printed circuit board or the like can be improved.

According to the second aspect of the present invention, the temperature in the high-pressure pressing step is lower than the melting point of the electrode surface portion and higher than the freezing point. Then, the conductive wire of the insulating coated conductive wire is securely embedded in the electrode.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views illustrating a step of joining an insulating-coated conductor to a first electrode in one embodiment of the present invention.

FIG. 2 is a perspective view showing a coil component obtained in one embodiment of the present invention.

FIG. 3 is a view showing a pressure and temperature profile in the embodiment shown in FIG. 1;

FIG. 4 is a schematic perspective view for explaining a joining device used in the embodiment shown in FIG. 1;

FIG. 5 is a cross-sectional view for explaining a high-pressure application step in another embodiment of the present invention.

FIG. 6 is a cross-sectional view for explaining a step of joining an insulated conductor to an electrode in a conventional method of manufacturing a coil component.

FIG. 7 is a cross-sectional view for explaining a problem in a case where an insulated conductor is joined to an electrode having an electrode layer made of a low melting point metal in a conventional method for manufacturing a coil component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coil component 2 ... Core 3 ... Insulated covering wire 3a ... Conducting wire 3b ... Insulating coating 4 ... First electrode 4a ... Base layer 4b ... Ni plating layer 4c ... Sn plating layer 5 ... Second electrode 6 ... Pressure chip

[Procedure amendment]

[Submission date] April 2, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

2. The method for manufacturing a coil component according to claim 1, wherein the high-pressure pressing step is performed at a lower temperature than the low-pressure pressing step.

3. The method for manufacturing a coil component according to claim 2 , wherein the high-pressure pressing step is performed at a higher temperature than the low-pressure pressing step.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

[0013]

According to the first aspect of the present invention, there is provided a core made of an insulating material, an insulated wire wound around the core, and an electrode formed on an outer surface of the core. A method for manufacturing a coil component in which an end of the insulated conductor is joined to the electrode, wherein the joining of the insulated conductor to the electrode is performed at a temperature not lower than a temperature at which the insulating coating of the insulated conductor is melted. And a low-pressure pressurizing step of pressing the insulating coated conductive wire against the electrode at a relatively low pressure, and, following the low-pressure pressing step, the conductive wire is buried so as to flatten the conductive wire, and the electrode. Like the electrode surface
And a high-pressure pressurizing step of pressing the conductor against the electrode at a relatively high pressure at a temperature equal to or lower than the melting point and equal to or higher than the freezing point .

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

[0014] Also, in the present invention, a high pressure pressing step may be performed in may be performed at a temperature lower than the low pressure process, or a high temperature.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0045

[Correction method] Change

[Correction contents]

Further , in the present invention, the temperature in the high-pressure pressing step is lower than the melting point of the electrode surface portion and higher than the freezing point. The conductor of the covered conductor is securely embedded in the electrode.

Claims (4)

[Claims] 1. A core comprising an insulating material, an insulated conductor wound around the core, and an electrode formed on an outer surface of the core, wherein an end of the insulated conductor is connected to the electrode. A method for manufacturing a joined coil component, comprising: joining an insulated conductor to the electrode at a temperature equal to or higher than a temperature at which the coating of the insulated conductor is melted, and applying a relatively low pressure to the electrode. A low-pressure pressing step of pressurizing and, following the low-pressure pressing step, so as to flatten the conductive wire,
And a high-pressure pressurizing step of pressing the conductive wire against the electrode at a relatively high pressure so as to be embedded in the electrode. 2. The method for manufacturing a coil component according to claim 1, wherein the temperature in the high-pressure pressurizing step is lower than the melting point of the electrode surface portion and higher than the freezing point. 3. The method for manufacturing a coil component according to claim 1, wherein the high-pressure pressing step is performed at a lower temperature than the low-pressure pressing step. 4. The method for manufacturing a coil component according to claim 1, wherein the high-pressure pressing step is performed at a higher temperature than the low-pressure pressing step.