KR0167392B1 - A film-type inductor and method for preparing the same - Google Patents

Abstract

The thin film inductor of the present invention is characterized by forming a leader line for connecting one end of a spiral pattern at the center to an external electrode when forming a spiral pattern conductor pattern layer. It is located on the same plane and the manufacturing method is difficult and there is a limit to the use of high frequency due to the capacitance. However, in the present invention, the manufacturing process is simple and the conductor pattern_insulation_drawing is performed by forming the lead wire through the substrate to form the lower surface of the substrate. The capacitance from the line can be ignored, which increases the frequency usage limit of the inductor.

Description

Thin film inductor and manufacturing method thereof

1 (a) is a plan view of a conventional thin film inductor in which the basic shape of the coil is spiral.

FIG. 1 (b) is sectional drawing of the center part of FIG. 1 (a).

2 is a perspective view of a thin film inductor manufactured according to the present invention.

3 is a process chart for manufacturing a thin film inductor according to the present invention of FIG.

* Explanation of symbols for main parts of the drawings

20: thin film type inductor 21,31: insulated substrate

22,33: conductor layer 24: insulating film

22a: end of spiral connection 22b: spiral connection

23a, 23b, 34, 34 ', 38, 38': external electrode 25, 37: connecting lead (leader line)

26: distal end of the connecting electrode 32: the upper surface

35: connection hole 36: lower surface

The present invention relates to a thin film inductor and a method of manufacturing the same. In particular, by forming a lead line for connecting one end of the conductor pattern with the external electrode on the surface opposite to the surface on which the conductor pattern is formed, the thin film type inductor which is easy to use at high frequency with a simple manufacturing process and high reliability, and its manufacturing method It is about.

1 (a) and 1 (b) show a conventional high frequency thin film inductor, where FIG. 1 (a) is a plan view and FIG. 1 (b) is a portion where the connection line of FIG. 1 (a) is located. It shows the shape of the cut section.

In FIG. 1, the high frequency thin film inductor 20 includes an insulating substrate 21 and a conductor layer 22 formed on the insulating engine 21. The conductor layer 22 includes external electrodes 22a and 23b and a spiral connection 22b at the center of the substrate.

One end portion 22a of the spiral connection portion is connected to the external electrode 23a, and the spiral connection portion 22b is connected to the tip portion 26 of the connection connection. The conductor layer 22 is protected by the insulating film 24, one end of the tip portion 26 of the connecting electrode formed by the insulating film 24 is connected to the spiral connecting portion 22b and the other end The part is connected to the external electrode 23b.

As shown in FIG. 1A, in order to connect the spiral connecting portion 22b to the external electrode 23b, the insulating film 24 should be made as described above to prevent a short circuit.

The conventional high frequency thin film inductor 20 having the structure as described above is manufactured by the following process.

That is, a metal thin film is coated on the insulating substrate 21 by sputtering or vapor deposition, and then the metal thin film is photoetched to form the conductor layer 22 and the external electrodes 23a and 23b. An insulating film 24 of polyimide is coated on the insulating substrate 21 including the conductor layer 22 and the external electrodes 23a and 23b formed in a spiral shape.

The central portion of the insulating film 24 is perforated for connection between the spiral connection portion 22b and the tip portion 26 of the connection lead 25, and both ends are removed for the external electrodes 23a and 23b. . A metal thin film is coated on the insulating film 24 and then photoetched to form the connecting lead 25 and the tip portion 26.

The above technique is not only complicated in the process of coating and etching the insulating layer after pattern formation of the conductor layer, but also the capacitance between the spiral-shaped conductor pattern and the connecting conductor across it as shown in FIG. 1 (a). This effect is increased, resulting in a lower resonance frequency. That is, the limit to the use of high frequency appears. In order to prevent the above increase of capacitance, it is necessary to seek a method of narrowing the width of the conductor pattern or keeping the distance between the conductor pattern and the connecting wire, but narrowing the width and increasing the thickness are designed vertically during metal etching. It is difficult to form, and the high step causes the deterioration of the reliability of the connection part. In addition, even if the above-described method is used, the process becomes complicated on the same plane and there is a limit in reducing the capacitance.

Therefore, the present invention eliminates the process of coating and etching the insulating layer in the thin film inductor and draws the connecting lead (lead line) to the back of the substrate without the conductor pattern layer, thereby simplifying the manufacturing process and increasing reliability. And its production method.

Hereinafter, the present invention will be described in detail.

The thin inductor of the present invention is a thin film inductor used at high frequency by forming a conductor pattern on an insulating substrate, and one terminal of the conductor pattern layer formed in a spiral shape on one surface of the insulating substrate is connected to an external electrode on the same surface. The other terminal of the conductor pattern layer is connected to the external electrode by a lead wire formed on the opposite surface of the insulating substrate through a connection hole passing through the insulating substrate in the middle portion of the insulating substrate.

The thin film type inductor according to the present invention can be used at high frequency by minimizing the capacitance of the inductor generated in the conductor_insulation layer_lead line.

In addition, a method of manufacturing a thin film inductor of the present invention includes the steps of forming a connection hole penetrating from one side of the insulating substrate to the opposite side in the center portion; Forming external electrodes on edges of both surfaces of the insulating substrate, respectively; And forming a lead wire and a spiral pattern conductor pattern connecting the connection hole and the external electrode to opposite surfaces of the insulating substrate, respectively.

When described in more detail based on the accompanying drawings of the present invention as follows.

The high frequency thin film inductor of the present invention eliminates the process of coating and etching the insulating layer during the manufacturing process and forms a connecting lead (leader line) on the opposite side of the plate where the conductor pattern layer is formed, thereby simplifying the manufacturing process and providing high reliability. Has characteristics.

In the high frequency thin film inductor according to the present invention, as illustrated in FIG. 2, one terminal of the conductive pattern layer 33 formed in the spiral shape on the upper surface 32 of the ceramic insulating substrate 31 has an outer surface on the same surface. The other terminal of the conductive pattern layer 33 is connected to the electrode 34 and is insulated through a connection hole 35 passing through the ceramic insulating substrate 31 at the center of the ceramic insulating substrate 31. It is connected to the external electrode 38 by a leader line 37 formed on the lower surface 36 of the substrate.

The high frequency thin film inductor as described above may be manufactured by the following method. First, as illustrated in FIG. 3 (a), a connection hole 35 having a predetermined size or more is formed in the middle pressure portion of the ceramic insulating substrate 31, or the connection hole 35 is arbitrarily made. A ceramic insulating substrate 31 is used.

The connection hole 35 should be made at least wider than the width of the conductor pattern layer 33 formed later. When the size of the connection hole 35 is smaller than the width of the conductor pattern layer 33, the reliability of the connection is reduced, and the DC resistance of the inductance element is increased, resulting in thermal noise.

Next, as shown in FIG. 3 (b), external electrodes 34 and 34 'are formed on both ends of the ceramic insulating substrate 31, respectively. The external electrodes 34 and 34 'may be formed by etching by dry coating such as puttering, vacuum deposition, or ion plating, or by using plating. However, in order to simultaneously form the external electrodes 34 and 34 ′ and the connection hole 35, a screen printing method using a mask may be more effective. The material used at this time is copper, silver, nickel, chromium, gold aluminum. Titanium or composite materials including them may be selected and used.

When the external electrodes 34 and 34 'are formed on the upper surface of the ceramic insulating substrate 31 (the surface with the conductive pattern layer 33) and the processing of the connection hole 35 is completed, the ceramic insulating substrate 31 is finished. (31) is reversed to form external electrodes (38, 38 ') on the lower surface (36) shown below as shown in FIG. 3 (c), respectively, and a connection hole (35) and the external electrodes (38,38'). ), The leader line 37 is formed.

The material of the leader line 37 and the external electrodes 38 and 38 'formed on the lower surface of the ceramic insulating substrate 31 and the method of forming the same use the same materials and methods as those of the upper surface. Again, screen printing is more effective, and the connection hole 35 is formed when the external electrodes 38 and 38 'are formed on the lower surface for the effective filling of the connection hole 35 penetrating the ceramic insulating substrate 31. ) Has the advantage of increasing the reliability of the current flow without the need for special process insertion. In addition, when the lead wire 37 is also wider than the conductor pattern layer 330, which is to be formed later, the resistance decreases, thereby obtaining an excellent inductor.

On the other hand, the conductor pattern layer 33 requires two terminal electrodes, that is, a portion connected to the external electrode 34 on the upper surface of the ceramic insulating substrate 31 as shown in FIG. When the conductor is wound into the center of the substrate 31, it is for connecting it to the external electrode. That is, in the third (d) it refers to the connection hole 35 and the current passes through the substrate to reach the connection hole 35 of the lower surface and flows along the leader line 37, and finally another external electrode. It is to be connected to the external circuit through (38).

Advantages of the thin film inductor according to the present invention are as follows. In the manufacture of connecting holes, it is possible to process them together with external electrodes to make them all at once, and connecting the connecting holes with external electrodes is processed at the bottom of the substrate through the substrate, so that the insulating layer between the conductor pattern layer and the lead wire connecting to the external electrodes later This is not necessary. If the insulation layer is to be manufactured separately, the process is complicated and costs are increased because the insulation film must be coated as well as a method such as photoetching. In addition, due to the inevitable step (height difference) between the leader line and the conductor pattern, the connection portion becomes thin, resulting in an increase in resistance and inferior connection reliability. Therefore, the present invention not only simplifies the process due to the absence of an insulating layer, but also does not cause a height difference between the connection hole and the conductor pattern layer, thereby increasing the reliability of the device and eliminating problems such as thermal noise.

In addition, determining the resonant frequency of the thin film inductor (ie, determining the limit of the use frequency) is based on the capacitance composed of the conductor_insulation layer_conductor. Occurs between patterns and between patterns and leader lines. The influence of the capacitance caused by the double pattern and the lead line and the insulating layer between them is quite large, and the above effects limit the frequency of use of the inductor. However, in the present invention, since the leader line is manufactured on the opposite side of the conductor pattern on the back surface of the substrate without using the insulating layer, the capacitance from the pattern_insulation layer_leader line structure can be ignored. Therefore, the resonant frequency is increased to become a thin film type inductor with a high use frequency.

EXAMPLE

After making a slurry of 96% of alumina P ceramic raw material and solvent such as alcohol, plasticizer and binder, make ceramic green sheet by tape casting method and decide the part where device is to be created. Make a hole. The green sheet was heat-treated at 1500 ° C. for 2 hours at an elevated temperature rate of 10 ° C./min in an oxide furnace to prepare a ceramic substrate. A conductor paste composed mainly of copper (Cu) powder was printed on the ceramic substrate to form external electrodes and connecting holes on the substrate top and dried. It was confirmed that the connection hole was also well filled with the conductor paste. On the lower surface of the dried specimen, the external electrode and the leader line were printed with a conductor paste and dried using the same method as the upper surface. The dried specimens were heat-treated at 900 ° C. and nitrogen atmosphere.

Next, in order to form a conductor pattern, in order to form a conductor pattern layer, a thickness of 1 μm is formed by using a photoetching method of forming a copper layer on the upper surface by sputtering and coating and etching a positive light resistor thereon. A micrometer conductor pattern was obtained. Then, in order to increase the inductance value of the device, a thick pattern having a thickness of 20 μm was obtained by electroplating using the conductor pattern layer as an electrode. These devices were protected by coating with epoxy resin.

The inductance value was 3 nH at 500 MHz when the total device size was 2.0 mm × 1.25 mm and the surface mounting component size was 60 µm, the width of the conductor pattern was 60 µm, and the thickness of the conductor was 20 µm. The frequency limit was over 3GHZ.

Claims (3)

In the thin film type inductor used by forming a conductor pattern layer 33 on the insulating substrate 31 at a high frequency, one terminal of the conductor pattern layer 33 formed in a spiral shape on one surface of the insulating substrate 31 is formed on the same surface. The other terminal of the conductive pattern layer 33 is connected to an external electrode 34 and is connected to the insulating substrate through a connection hole 35 passing through the insulating substrate 31 at the center of the insulating substrate 31. Thin film inductor for high frequency, characterized in that connected to the external electrode 38 by the lead line 37 formed on the opposite side of the (31). Forming a connection hole at a central portion thereof, penetrating from one side of the insulating substrate to the other side thereof; Forming external electrodes on both side edges of the insulating substrate; And forming a leader line and a spiral pattern conductor pattern layer connecting the connection hole and the external electrode to opposite surfaces of the insulating substrate, respectively. The method of claim 2, wherein the external electrode is simultaneously manufactured with a connection hole, and the conductor pattern layer is selected from copper, silver, nickel, chromium, gold, titanium, aluminum, or a composite material including the same. .