JPH08330154A - Chip type coil and its manufacture - Google Patents

Abstract

PURPOSE: To reduce the cost by a structure wherein the terminal electrode includes a low temperature baking metal layer. CONSTITUTION: An electric insulation layer 8 is formed on a ceramic substrate 2 while covering a coil conductor 3 and a jump conductor 6. A pair of terminal electrodes 9, 10 are formed at the opposite ends of the substrate 2. The terminal electrode 9 comprises a low temperature baking metal layer 12, and a barrier metal film 13 formed on the surface. The baking metal layer 12 is formed by baking a low temperature baking metal paste applied to the end part of the substrate 2. Silver or copper powder is admixed, as a conductive material, with the metal paste. The barrier metal film 13 is formed by wet plating, e.g. electroplating or electroless plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip coil and a method for manufacturing the same, and more particularly to improvements in the structure of a terminal electrode and a method for forming the same.

[0002]

2. Description of the Related Art FIG. 1 is a partially cutaway perspective view of a chip coil 1 which is of interest to the present invention. Such a chip type coil 1 is, for example, several hundred M
It is used in a high frequency band of Hz or more and has an inductance value of several hundreds nH or less.

Referring to FIG. 1, a chip type coil 1 includes an electrically insulating substrate 2. A coil conductor 3 extending in a spiral shape is formed on the substrate 2. The one end 4 of the coil conductor 3 extends to the edge of the substrate 2. A jump conductor 6 is connected to the other end portion 5 of the coil conductor 3, and the jump conductor 6 is formed on an electrically insulating patch 7 that covers a part of the coil conductor 3 and at the other end edge of the substrate 2. Extend to.

An electric insulation layer 8 is formed on the substrate 2 so as to cover the coil conductor 3 and the jump conductor 6. Then, a pair of terminal electrodes 9 and 10 are formed on both ends of the substrate 2. The one end 4 of the coil conductor 3 is
It is electrically connected to one terminal electrode 9, and the other end 5 is also electrically connected to the other terminal electrode 10 via the jump conductor 6.

Conventionally, the terminal electrodes 9 and 10 have been formed by dry plating such as sputtering or vacuum evaporation. This is because a resin such as polyimide was used as the material of the electrically insulating patch 7 and the electrically insulating layer 8, so that the terminal electrodes 9 and 10 were made of a conventional high temperature baking (700 to 1000 ° C.) type silver paste. The reason is that when attempting to form it by baking such a metal paste, the resin used as the material of the insulating patch 7 and the insulating layer 8 cannot withstand the temperature during baking. Therefore, it is necessary to form the terminal electrodes 9 and 10 by dry plating.

[0006]

However, when the terminal electrodes 9 and 10 are to be formed by dry plating, the labor cost associated with putting the chips in and out of the mask for limiting the places to be dry-plated and the mask The cost required for manufacturing, the facility cost due to the use of an expensive dry plating apparatus, and the like are high, which causes the high cost of the chip coil 1.

Further, when the chip is subjected to dry plating through the mask, especially at the end face portion of the substrate 2, since the plating film is only formed by the wraparound of metal atoms, if the substrate 2 becomes thicker. Indeed, it becomes more difficult to form the plating film relatively thick in this portion. As a result, for example, when the underlayer of the terminal electrodes 9 and 10 is made of a nickel-chromium alloy and the surface layer is also made of silver, the nickel-chromium alloy of the underlayer may be exposed and the terminal electrodes 9 and 10 may be exposed. The solderability or solder heat resistance may deteriorate.

Further, the boundary line between the patterns of the terminal electrodes 9 and 10 given by the mask may be blurred. In this case, the resulting inductance value of the chip coil 1 deviates from a desired value.
Therefore, an object of the present invention is to provide a chip type coil and a method for manufacturing the same, which can solve various problems encountered when the above-mentioned terminal electrode is formed by dry plating.

[0009]

According to the present invention, there is provided an electrically insulating substrate, a pair of terminal electrodes formed at both ends of the substrate, and an end portion formed on the substrate and at each end of the terminal electrode. Is provided with a coil conductor electrically connected to each other, and an electrical insulating layer formed on the substrate so as to cover the coil conductor, and is directed to a chip-type coil. To solve the problem, the terminal electrode is characterized by including a layer made of a low temperature baking type baking metal.

The baked metal preferably contains silver. Further, copper may be used instead of silver. The terminal electrode may further include a barrier metal film formed by wet plating on the surface of the layer made of the baked metal. The barrier metal film may be formed by either electroplating or electroless plating. Further, the barrier metal film may be formed, for example, with a base of nickel and a surface of tin, a base of nickel and a surface of solder, and a base of copper and a surface of tin. it can.

The substrate is preferably made of ceramic or may contain resin. The coil conductor may be a processed metal film formed by wet plating, or may be a processed metal film formed by dry plating.

The electric insulation layer is preferably made of a resin such as an epoxy resin or a polyimide resin.
The present invention is also directed to the above-described method for manufacturing the chip coil. In the method for manufacturing a chip-type coil according to the present invention, a mother substrate for preparing a plurality of substrates for a plurality of chip-type coils by dividing them along a plurality of first and second dividing lines that are orthogonal to each other is prepared. And a step of forming the coil conductor and the electrical insulating layer on the mother substrate, and then dividing the mother substrate along the first dividing line, thereby forming the pair of terminal electrodes. A step of obtaining a stick-shaped structure in which end portions to be formed are arranged along both edges extending in the longitudinal direction, and a low temperature baking type is applied to both edges extending in the longitudinal direction of the stick-shaped structure. The step of applying the metal paste, the step of baking the metal paste to form the terminal electrode, and thereafter dividing the stick-shaped structure along the second dividing line. It is characterized by comprising the step of obtaining the individual chip-type coil.

The low temperature baking type metal paste contains, for example, a silver or copper powder as a conductive material and a phenol resin or an epoxy resin as a fixing material, and is baked at a temperature of about 200.degree. It is possible.

[0014]

According to the present invention, since the layer made of the baked metal provided in the terminal electrode can be baked at a relatively low temperature of about 200 ° C., other elements provided in the chip coil have high heat resistance. You don't have to. for that reason,
Conventionally, because of the heat resistance problem described above, it was necessary to form the terminal electrodes by dry plating, which causes a high cost, but according to the present invention, the need to use such dry plating can be avoided.

[0015]

Therefore, according to the present invention, the terminal electrode can be formed at low cost, and the cost of the chip type coil can be reduced. Further, according to the present invention, unlike the case of dry plating, the thickness (t dimension) of the chip type coil is not restricted and the boundary line is not obscured. It can be appropriate.

When silver or copper is used as the baking metal, it is possible to ensure high conductivity at a relatively low cost in the terminal electrode. If the terminal electrode is further provided with a barrier metal layer, it is possible to easily provide the terminal electrode with good solderability and solder heat resistance by the barrier metal layer.

When the substrate is made of ceramic, the coil conductor is formed by a method of exposing to a relatively high temperature such as sputtering, without the trouble of considering the heat resistance of the substrate being encountered. The steps can be carried out. The ceramic used for the substrate preferably has a low dielectric constant (ε is 10 or less).

The significance of the present invention is particularly enhanced when the substrate is a resin-containing substrate such as a glass / epoxy substrate or a polyimide substrate. That is, in the present invention, since the baking metal provided in the terminal electrode can be baked at a low temperature, the substrate does not need to have high heat resistance, and the resin can be used for the substrate without any problem. Further, the resin can provide the substrate at a lower cost than the ceramic.

When the coil conductor is formed by wet plating, the cost can be reduced in terms of equipment cost, material cost, labor cost, etc., as compared with the case where it is formed by dry plating such as sputtering. When the electric insulation layer is made of an epoxy resin, the electric insulation layer can be formed at a lower cost than when it is made of ceramic.
In particular, when an epoxy resin is used, the electric insulation layer can be easily formed in a desired pattern by printing such as screen printing.

As described above, when the terminal conductor is provided with the low temperature baking type baking metal while the coil conductor is formed by the wet plating and the electric insulating layer is made of resin, the chip type coil according to the present invention is obtained. All manufacturing steps can be performed at a temperature of about 200 ° C. Therefore, high heat resistance is not required for each element provided in the chip-type coil, the range of material selection for each element is widened, and various methods can be developed for forming each element.

Further, according to the method of manufacturing the chip type coil according to the present invention, since the terminal electrode is formed, the mother substrate is first formed using the low temperature baking type metal paste.
At the stage of the stick-shaped structure which is divided only along the dividing line, the metal paste is applied to both edges extending in the longitudinal direction and baked, and then the stick-shaped structure is divided into the second division. Since the electrodes are divided along the line, the terminal electrodes can be efficiently formed with simple and inexpensive equipment, and as a result, the cost of the chip type coil can be reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The chip type coil 1 shown in FIG. 1 also corresponds to a chip type coil according to an embodiment of the present invention. As described above, the chip coil 1 includes the electrically insulating substrate 2. A coil conductor 3 extending in a spiral shape is formed on the substrate 2. The one end 4 of the coil conductor 3 extends to the edge of the substrate 2. A jump conductor 6 is connected to the other end 5 of the coil conductor 3, and the jump conductor 6
Is formed on the electrically insulating patch 7 that covers a part of the coil conductor 3 and extends to the other edge of the substrate 2.

An electric insulating layer 8 is formed on the substrate 2 so as to cover the coil conductor 3 and the jump conductor 6. Then, a pair of terminal electrodes 9 and 10 are formed on both ends of the substrate 2. The one end 4 of the coil conductor 3 is
It is electrically connected to one terminal electrode 9, and the other end 5 is also electrically connected to the other terminal electrode 10 via the jump conductor 6.

The chip type coil 1 is manufactured, for example, as follows. FIG. 2 is a plan view showing some typical steps included in the method for manufacturing the chip coil 1. First, the substrate 2 is prepared as shown in FIG. The substrate 2 is made of, for example, alumina, a ceramic having a low dielectric constant (ε is 10 or less), or glass, or a substrate containing a resin such as a glass / epoxy substrate or a polyimide substrate. May be.

Next, as also shown in FIG. 2A, a conductor film 11 made of a metal of good conductivity such as silver, gold or copper is formed on the substrate 2. Conductor film 11
For the formation of, for example, dry plating such as sputtering, or wet plating such as electroplating or electroless plating is applied. Substrate 2 is preferably composed of a ceramic because it is exposed to relatively high temperatures when dry plating is applied. When wet plating is applied, the substrate 2 can be composed of any of the materials described above.

Next, as shown in FIG. 2B, the conductor film 1
1 is patterned to form a spiral coil conductor 3. As a patterning method, for example, by applying a resist on the conductor film 11 in the same pattern as the coil conductor 3 by screen printing, drying, and removing the excess conductor film 11 by wet etching, the resist is peeled off. The method of obtaining the coil conductor 3 having a desired pattern can be applied. Instead of this, a photoresist is used.
A photolithography technique may be applied in which it is applied on the substrate 1, exposed based on the pattern of the coil conductor 3, developed, and then patterned by etching. In the latter case, the coil conductor 3 can be easily thinned (for example, the line and space is 20 to 30 μm).

The coil conductor 3 having a desired pattern may be formed on the substrate 2 from the beginning by printing, for example. Further, the coil conductor 3 having a desired pattern may be formed on the substrate 2 by using a transfer technique. Next, as shown in FIG. 2C, the electrically insulating patch 7 is formed so as to cover a part of the coil conductor 3. The insulating patch 7 is formed, for example, by applying an epoxy resin in a desired pattern by screen printing and baking. A polyimide resin may be used instead of the epoxy resin.

Next, as shown in FIG. 2 (4), the jump conductor 6 is formed on the insulating patch 7. The jump conductor 6 can be formed by using the same material and method as those for forming the coil conductor 3 described above. That is, first, a conductor film is formed by wet plating or dry plating, and then patterned by etching using a resist to obtain a jump conductor 6 having a desired pattern.
When the jump conductor 6 is formed, the above-described formation of the coil conductor 3 is usually repeated, so that the thickness of the coil conductor 3 is increased at a substantial portion thereof.

Next, as shown in FIG. 2 (5), the electric insulating layer 8 is formed so as to cover the coil conductor 3 and the jump conductor 6.
Are formed on the substrate 2. The insulating layer 8 is formed by applying an epoxy resin onto the substrate 2 by screen printing,
It is formed by baking. A polyimide resin may be used instead of the epoxy resin. Also,
Instead of such a resin, the insulating layer 8 may be formed by applying a ceramic paste onto the substrate 2 and baking it.

Next, as shown in FIG. 2 (6), the terminal electrodes 9 and 10 are formed on both ends of the substrate 2, and the desired chip type coil 1 is obtained. These terminal electrodes 9 and 10
The method of forming the above will be described with reference to the one terminal electrode 9 shown in FIG. Referring to FIG. 3, the terminal electrode 9 includes a layer 12 made of low temperature baking type baking metal and a barrier metal film 13 formed on the surface thereof.

The baked metal layer 12 is formed by applying a low temperature baking type metal paste to the end portion of the substrate 2 and baking it, and can be baked at a relatively low temperature of 200 to 300 ° C. As the conductive material, that is, the metal material contained in the metal paste, for example, silver powder or copper powder is used, and as the fixing material, for example, phenol resin, epoxy resin, or the like is used, and by kneading these, It is a metal paste. In addition,
As the fixing material, any resin may be used as long as it is not melted by the molten solder or adversely affected.

The barrier metal film 13 is formed by wet plating such as electroplating or electroless plating, and has good solderability and / or solder heat resistance for the terminal electrode 9 as required. Formed to give.
Although not shown in FIG. 3, the barrier metal film 13 is formed with, for example, two layers, and the base is nickel and the surface is tin, the base is nickel and the surface is solder, and the base is copper. The surface can be tin.

Referring again to FIG. 2, in (1) to (5) thereof, it is indicated by broken lines that the substrate 2 is provided by a mother substrate obtained by dividing these plural ones. Normally, in manufacturing a chip-type coil on a factory scale, a large number of chip-type coils are efficiently manufactured. Therefore, the steps shown in FIGS. 2 (1) to (5) are performed while maintaining the state of the mother substrate. , The mother structure is divided by, for example, chocolate break or dicing so as to obtain chips for the individual chip type coils 1 when the step (5) is completed in parallel with respect to the plurality of substrates 2. To be done.

The efficient manufacturing method of the chip type coil 1 as described above is more preferably carried out as shown in FIG. FIG. 4 (1) shows a mother structure 14 including a mother substrate at a stage where the process shown in FIG. 2 (5) has been completed. This mother structure 14 is
It is divided along a plurality of first dividing lines 15 to form a stick-shaped structure 16 as shown in FIG. 4 (2). In this stick-shaped structure 16, the ends of the substrate 2 on which the pair of terminal electrodes 9 and 10 are to be formed are arranged along both edges 17 and 18 extending in the longitudinal direction.

This stick-shaped structure 16 is then
As shown in FIG. 4C, in that state, the metal paste is subjected to a low temperature baking type metal paste application step, and the metal paste is applied to both edge portions 17 and 18 extending in the longitudinal direction and baked. To form the terminal electrodes 9 and 10. Next, the stick-shaped structure 16 is divided along a plurality of second dividing lines 19 which are orthogonal to the above-mentioned first dividing line 15, and as shown in FIG. It is assumed to be 1.

When the barrier metal film 13 is formed on the surface of the terminal electrodes 9 and 10, it may be formed after the individual chip-type coils 1 are formed, or the stick-shaped structure may be formed. The formation may be performed at the stage of the object 16. Although the present invention has been described above with reference to the preferred embodiments, various other modifications are possible within the scope of the present invention.

For example, in the illustrated embodiment, the chip coil 1 is one in which one end 5 of the coil conductor 3 is electrically connected to the associated terminal electrode 10 via the jump conductor 6. However, the present invention can also be applied to a chip-type coil that does not include such a jump conductor and has a coil conductor simply formed on the substrate in a planar manner.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a chip coil 1 according to an embodiment of the present invention.

2A to 2C are plan views sequentially showing representative steps included in the method for manufacturing the chip coil 1 shown in FIG.

FIG. 3 is a terminal electrode 9 of the chip coil 1 shown in FIG.
It is sectional drawing which expands and shows the edge part in which was formed.

4 is a plan view sequentially showing steps included in a preferred method for forming the terminal electrodes 9 and 10 shown in FIG. 1. FIG.

[Explanation of symbols]

 1 Chip type coil 2 Substrate 3 Coil conductor 4, 5 Coil conductor end 6 Jump conductor 7 Electrical insulation patch 8 Electrical insulation layer 9, 10 Terminal electrode 12 Baking metal layer 13 Barrier metal film 14 Mother structure 15 First division Line 16 Stick-like structure 17,18 Edge of stick-like structure 19 Second dividing line

Claims (8)

[Claims] 1. An electrically insulating substrate, a pair of terminal electrodes formed at both ends of the substrate, and terminal ends formed on the substrate and electrically connected to the terminal electrodes, respectively. In a chip-type coil comprising a coil conductor and an electric insulating layer formed on the substrate so as to cover the coil conductor, the terminal electrode includes a layer made of a low temperature baking type baking metal. A chip coil. 2. The baked metal contains silver or copper,
The chip-type coil according to claim 1. 3. The chip coil according to claim 1, wherein the terminal electrode further comprises a barrier metal film formed by wet plating on the surface of the layer made of the baked metal. 4. The chip-type coil according to claim 1, wherein the substrate is made of ceramic. 5. The chip-type coil according to claim 1, wherein the substrate contains a resin. 6. The chip type coil according to claim 1, wherein the coil conductor is formed by wet plating. 7. The chip coil according to claim 1, wherein the electrical insulation layer is made of resin. 8. An electrically insulating substrate, a pair of terminal electrodes formed on both ends of the substrate, and an end formed on the substrate and electrically connected to the terminal electrodes. A method for manufacturing a chip coil, comprising: a coil conductor; and an electrical insulating layer formed on the substrate so as to cover the coil conductor, wherein the plurality of substrates for the plurality of chip coils are orthogonal to each other. A mother substrate for taking out by dividing along each of the plurality of first and second dividing lines is prepared, the coil conductor and the electrical insulating layer are formed on the mother substrate, and then the mother substrate is divided into By dividing along one division line, a stick-like structure is obtained in which the end portions where the pair of terminal electrodes are to be formed are arranged along both edge portions extending in the longitudinal direction, and the stick-like structure is obtained. of A low temperature baking type metal paste is applied to both edges of the structure extending in the longitudinal direction, the metal paste is baked to form the terminal electrode, and then the stick-like structure is formed on the second dividing line. A method for manufacturing a chip-type coil, characterized by comprising the steps of dividing along each side to obtain individual chip-type coils.