JP4904825B2 - Manufacturing method of chip resistor - Google Patents

Description

The present invention relates to a method of manufacturing a chip resistor, and more particularly to a method of manufacturing a chip resistor having a low resistance value and a good TCR.

  Hereinafter, a conventional chip resistor will be described with reference to the drawings.

  FIG. 13 is a cross-sectional view of a conventional chip resistor, and the manufacturing method thereof will be described below based on FIG.

  First, the back electrode 2 and the top electrode 3 are formed by screen printing on both ends of the lower surface of the substrate 1 made of insulating alumina or the like and both ends of the upper surface of the substrate 1 and fired with a profile having a peak temperature of 850 ° C. Thus, the back electrode 2 and the top electrode 3 are made stable.

  Next, the resistor 4 is formed by a screen printing method so that both ends are electrically connected to the upper surface electrode 3, and the resistor 4 is made a stable film by firing with a profile having a peak temperature of 850 ° C.

  Next, a protective film 5 made of resin is formed so as to cover all of the resistor 4 and a part of the upper surface electrode 3, and both ends of the substrate 1 are electrically connected to the back surface electrode 2 and the upper surface electrode 3. An end face electrode 6 is formed on the surface.

  Finally, a conventional chip resistor has been manufactured by forming a nickel plating layer 7a and a solder plating layer 7b on the surfaces of the back electrode 2, the top electrode 3, and the end electrode 6 using a barrel plating method.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2000-106302 A

  In the conventional chip resistor described above, even if a material such as a silver palladium alloy having a low TCR of several tens ppm / ° C. is used for the resistor 4, the material used for forming the upper surface electrode 3 is mainly composed of silver. Therefore, when the electrode paste is fired at a peak temperature of 850 ° C., the TCR is several thousand ppm / ° C., which is higher than that of the resistor 4, and in the vicinity of the portion where the upper electrode 3 and the resistor 4 overlap. Since mutual diffusion occurs, and the diffusion causes the influence of the upper electrode 3 having a high TCR on the resistor 4 having a low TCR, it is difficult to obtain a stable resistor having a low TCR.

  On the other hand, in Patent Document 1, a resistor is sandwiched between an upper layer and a lower layer of a first surface electrode layer mainly composed of silver, and a copper plating film having a thickness of 30 μm or more is formed on the first surface electrode layer. However, since the copper plating film is not in direct contact with the resistor, the technology that makes it possible to secure low resistance and good TCR is disclosed. In the portion where the first surface electrode layer and the resistor overlap, diffusion occurs and the TCR is adversely affected. Moreover, since the manufacturing process is complicated, it is advantageous in terms of cost.

The present invention solves the above-described conventional problems, and an object of the present invention is to provide a method for manufacturing a chip resistor having a low resistance value and a good TCR.

  In order to achieve the above object, the present invention has the following configuration.

According to the first aspect of the present invention, there is provided a resistor provided from one end portion to the other end portion of the upper surface of the piece-like substrate, and both end faces of the piece-like substrate. In a method for manufacturing a chip resistor, comprising: a pair of end face electrodes; a protective film that covers a part of the resistor; and a pair of plating layers that electrically connect the resistor and the pair of end face electrodes. Forming a plurality of resistors on the upper surface of the substrate, trimming the resistor with a trimming meter positioned on the resistor, and trimming metering position on the resistor as an end. A step of covering a part of the resistor with a protective film, a step of dividing the sheet-like substrate into a strip-like substrate after the step of covering with the protective film, and an electrical connection between the resistor and the end surface of the strip-like substrate. forming an end surface electrode connected to the end Barrel plating so as to cover the surface of the resistor and the end face electrode after the step of forming the electrode, dividing the strip-shaped substrate to obtain a piece-like substrate, and the step of obtaining the piece-like substrate Forming a plating layer by a method, and not having a step of forming an upper surface electrode on the resistor . According to this manufacturing method, the step of forming the plating layer so as to be electrically connected to the resistor and the end surface electrode provided on the end surface of the strip-shaped substrate is provided, and the upper surface electrode that requires firing at a high temperature is provided. Since it is not provided, the influence of mutual diffusion between the upper electrode having a high TCR and the resistor having a low TCR is eliminated, and thereby a chip resistor having a low resistance value and a good TCR can be obtained. It is. Furthermore, since the trimming meter reading position when trimming the resistor is made substantially the same position as the end of the protective film, according to this manufacturing method, the resistance value after trimming is almost the same as the resistance value of the finished chip resistor product. Therefore, the chip resistor having high resistance value accuracy can be obtained.

As described above, the manufacturing method of the chip resistor according to the present invention does not include the upper surface electrode that needs to be fired at a high temperature, so there is no influence of mutual diffusion between the upper surface electrode having a high TCR and the resistor having a low TCR, As a result, a chip resistor having a low resistance value and a good TCR can be obtained, and further, the resistance value after trimming becomes substantially the same as the resistance value of the finished chip resistor. This has the effect of obtaining a highly accurate chip resistor.

( Reference Example 1)
Hereinafter, prior to the description of the embodiments of the present invention will be described with the reference example 1.

FIG. 1 is a sectional view of a chip resistor in Reference Example 1 , and FIGS. 2A to 2D and FIGS. 3A to 3G are manufacturing process diagrams showing a manufacturing method of the chip resistor.

  Below, the manufacturing method is demonstrated based on the manufacturing-process figure shown to Fig.2 (a)-(d) and Fig.3 (a)-(g).

  First, as shown in FIG. 2A, an insulating sheet-like substrate 11 made of porcelain such as alumina is prepared. Then, an electrode paste mainly composed of silver is screen-printed on the back surface of the sheet-like substrate 11 and fired with a firing profile having a peak temperature of 850 ° C., thereby straddling a plurality of pairs of back-side electrodes 12 across the primary division grooves 11a. As shown in FIG. The back electrode 12 is not necessarily formed. And when this back surface electrode 12 is not formed, the end surface electrode 18 mentioned later goes around the back surface of the board | substrate 11, and bears the role of the back surface electrode 12. FIG.

  Next, as shown in FIG. 2 (b), a plurality of resistors 13 are formed on the upper surface of the sheet-like substrate 11 by using a material having a low specific resistance and a low TCR, such as a silver-palladium alloy, and the like. The resistor 11 is formed from one end to the other end of the substrate 11 so as to straddle a plurality of resistors 13 in parallel.

  Next, as shown in FIG. 2 (c), a pre-coated glass (not shown) is formed by screen printing so as to cover a part of the upper surface of the resistor 13, if necessary, and fired at a peak temperature of 600 ° C. After the pre-coated glass is made into a stable film by firing with a profile, a plating resist 14 made of a material excellent in acid resistance and heat resistance such as a synthetic resin is arranged in a grid pattern, and a part of the resistor 13 is plated resist 14 In this case, if the plating resist 14 is formed also on the primary division groove 11a and the plating layer is not formed on the primary division groove 11a, the plating layer is cut at the time of the primary division. Since the generation of burrs is eliminated, manufacturing is facilitated.

  Next, as shown in FIG. 2D, an electrode 15 made of a metal material having a low resistance value such as silver is formed by plating on the portion of the resistor 13 that is not covered with the plating resist 14 by electroplating. To do. In this case, when the thickness of the electrode 15 formed by plating is 30 μm or more, the connection reliability is improved and the TCR is improved.

  Next, as shown in FIG. 3A, after the substrate 11 is washed, the plating resist 14 is removed using a release agent.

  Next, as shown in FIG. 3B, in order to adjust the resistance values of the plurality of resistors 13 to a constant value, resistance is applied from above the resistor 13 or pre-coated glass (not shown) by a laser trimming method. Trimming is performed on the body 13 to form a trimming groove 16.

  In FIG. 2C, the plating resist 14 is formed. However, the step of forming the plating resist 14 is omitted, and the resistor 13 is directly covered with precoat glass (not shown). And this precoat glass (not shown) may be used as the plating resist 14. In this case, since pre-coated glass (not shown) is a material excellent in acid resistance and heat resistance, it has the same action as the plating resist 14. From this state, the electrode 15 constituted by plating is formed on the resistor 13 other than the portion covered with the precoat glass (not shown) by using an electroplating method. Thereafter, the substrate 11 is washed, and then the trimming groove 16 is formed on the precoat glass (not shown). Thus, if the precoat glass (not shown) is used as the plating resist 14, Since the step of stripping the plating resist 14 can be omitted, the manufacturing process is simplified, which is advantageous in terms of cost.

  Next, as shown in FIG. 3C, a protective film 17 mainly composed of an epoxy resin is formed by a screen printing method so as to cover the plurality of resistors 13 and the precoat glass (not shown). By curing with a curing profile having a peak temperature of 200 ° C., the protective film 17 is made stable.

  Next, as shown in FIG. 3D, a strip-shaped substrate 11c is obtained by dividing the sheet-like substrate 11 along the primary dividing grooves 11a.

  Next, as shown in FIG. 3 (e), the end face electrode 18 is electrically conductive so as to electrically connect the electrode 15 formed by plating and the back face electrode 12 (not shown) to the end face of the strip-shaped substrate 11c. It is formed by applying a functional paste or thin film sputtering. In addition, when the back surface electrode 12 is not formed here, the end surface electrode 18 goes around to the back surface of the strip-shaped board | substrate 11c, and bears the role of the back surface electrode 12. FIG.

  Next, as shown in FIG. 3F, the strip-shaped substrate 11c is divided along the secondary dividing grooves 11b to obtain the individual substrate 11d.

Finally, as shown in FIG. 3 (g), the end face of the individual substrate 11d is covered with the electrode 15, the end face electrode 18 and the back face electrode 12 (not shown) formed by plating, that is, The plating layer 19 is formed by barrel plating so as to be electrically connected to these, and the chip resistor in Reference Example 1 is obtained. As shown in FIG. 1, the plating layer 19 is constituted by a two-layer structure of a first plating layer 19a usually made of nickel and a second plating layer 19b made of solder or tin.

The chip resistor in the reference example 1 is provided at both end portions of the upper surface of the resistor 13 as shown in FIG. 1 and a pair of electrodes 15 formed by plating and provided at both end surfaces of the substrate 11. A chip having a better TCR than the conventional resistor as shown in FIG. 9 because the pair of plating layers 19 are electrically connected to the end face electrode 18 and no upper surface electrode that requires firing at a high temperature is provided. A resistor is obtained.

In the reference example 1 described above , the resistor 13 is formed on the upper surface of the substrate 11. However, the present invention is not limited to this configuration. For example, the resistor 13 is formed on the back surface of the substrate 11. In this case, or when the resistors 13 are formed on both the upper surface and the back surface of the substrate 11 as shown in FIG. 10, the same effects as those of the reference example 1 can be obtained.

( Reference Example 2 )
Hereinafter, Reference Example 2 will be described.

4 is a cross-sectional view of the chip resistor in Reference Example 2, and FIGS. 5A to 5F and FIGS. 6A to 6F are manufacturing process diagrams showing a manufacturing method of the chip resistor.

  Below, the manufacturing method is demonstrated based on the manufacturing-process figure shown to Fig.5 (a)-(f) and Fig.6 (a)-(f).

  First, as shown in FIG. 5A, an insulating sheet-like substrate 21 made of porcelain such as alumina is prepared. Then, an electrode paste mainly composed of silver is screen-printed on the back surface of the sheet-like substrate 21 and fired with a firing profile having a peak temperature of 850 ° C., thereby straddling a plurality of pairs of back-side electrodes 22 across the primary division grooves 21a. As shown in FIG. The back electrode 22 is not necessarily formed. And when this back surface electrode 22 is not formed, the end surface electrode 28 mentioned later goes around the back surface of the board | substrate 21, and bears the role of the back surface electrode 22. FIG.

  Next, as shown in FIG. 5B, an electrode paste mainly composed of silver is screen-printed on the upper surface of the sheet-like substrate 21 and fired with a firing profile having a peak temperature of 850 ° C. The upper electrodes 20 are arranged in a grid pattern so as to straddle the primary dividing grooves 21a.

  Next, as shown in FIG. 5C, the upper surface electrode 20 is bridged on the upper surface of the sheet-like substrate 21 using a material having a low specific resistance and TCR made of silver palladium alloy or the like. A plurality of resistors 23 are formed. Here, the order of the steps from FIG. 5A to FIG. 5C, that is, the order of forming the back electrode 22, the top electrode 20, and the resistor 23 is not limited to the above order, and the top electrode The firing of 20 and the back electrode 22 may be performed separately or simultaneously.

  Next, as shown in FIG. 5 (d), a precoat glass (not shown) is formed by a screen printing method so as to cover a part of the upper surface of the resistor 23 as necessary, and fired at a peak temperature of 600 ° C. After baking the profile to make the pre-coated glass a stable film, plating resists 24 made of a material having excellent acid resistance and heat resistance such as synthetic resin are arranged in a grid pattern, and a part of the resistor 23 is plated resist 24. In this case, the plating resist 24 is formed so as not to cover at least the exposed portion of the upper surface electrode 20 and the overlapping portion of the upper surface electrode 20 and the resistor 23. In this case, if the plating resist 24 is also formed on the primary dividing groove 21a and the electrode 25 constituted by plating is not formed on the primary dividing groove 21a, the primary dividing groove 21a Since the generation of burrs due to the cutting of the electrode 25 is eliminated, the manufacture is facilitated.

  Next, as shown in FIG. 5E, an electrode 25 made of a metal material having a low resistance value such as silver is formed on a portion of the upper surface electrode 20 and the resistor 23 that is not covered with the plating resist 24 by electroplating. Is formed by plating. In this case, when the thickness of the electrode 25 formed by plating is 30 μm or more, the connection reliability is improved and the TCR is improved.

  Next, as shown in FIG. 5F, after the substrate 21 is washed, the plating resist 24 is removed using a release agent.

  Next, as shown in FIG. 6A, in order to adjust the resistance value of the plurality of resistors 23 to a constant value, resistance is applied from above the resistor 23 or pre-coated glass (not shown) by a laser trimming method. Trimming is performed on the body 23 to form a trimming groove 26.

  In FIG. 5D, the plating resist 24 is formed. However, the step of forming the plating resist 24 is omitted, and the resistor 23 is directly covered with precoat glass (not shown). The pre-coated glass (not shown) may be used as the plating resist 24. In this case, pre-coated glass (not shown) is a material excellent in acid resistance and heat resistance, and thus has the same action as the plating resist 24. From this state, the electrode 25 constituted by plating is formed on the resistor 23 other than the portion covered with the pre-coated glass (not shown) by using an electroplating method. Thereafter, the substrate 21 is washed, and then the trimming groove 26 can be formed on the precoat glass (not shown). In this way, the precoat glass (not shown) is applied to the plating resist 24. If this is used, the step of removing the plating resist 24 can be omitted, which simplifies the manufacturing process and is advantageous in terms of cost.

  Next, as shown in FIG. 6B, a protective film 27 mainly composed of an epoxy resin is formed by a screen printing method so as to cover the plurality of resistors 23 and the precoat glass (not shown). The protective film 27 is made stable by curing with a curing profile having a peak temperature of 200 ° C.

  Next, as shown in FIG. 6C, the strip-shaped substrate 21c is obtained by dividing the sheet-like substrate 21 along the primary dividing grooves 21a.

  Next, as shown in FIG. 6 (d), the end face electrode 28 is made conductive so as to electrically connect the electrode 25 formed by plating and the back face electrode 22 (not shown) to the end face of the strip-shaped substrate 21c. It is formed by paste application or thin film sputtering. In addition, when the back surface electrode 22 is not formed here, the end surface electrode 28 goes around to the back surface of the strip-shaped board | substrate 21c, and bears the role of the back surface electrode 22. FIG.

  Next, as shown in FIG. 6E, the strip-shaped substrate 21c is divided along the secondary dividing grooves 21b to obtain the individual substrate 21d.

Finally, as shown in FIG. 6 (f), the end face of the individual substrate 21d is covered with the electrode 25, the end face electrode 28 and the back face electrode 22 (not shown) formed by plating, that is, The plating layer 29 is formed by barrel plating so as to be electrically connected to these, and the chip resistor in Reference Example 2 is obtained. As shown in FIG. 4, the plating layer 29 has a two-layer structure of a first plating layer 29 a made of nickel and a second plating layer 29 b made of solder or tin.

As shown in FIG. 4, the chip resistor in the reference example 2 includes a pair of electrodes 25 formed by plating on the side closer to the center of the substrate 21 than the overlapping portion 23 a of the pair of upper surface electrodes 20 and the resistors 23. Therefore, the current flows so as to avoid the overlapping portion 23a between the upper surface electrode 20 and the resistor 23, that is, due to the mutual diffusion between the upper electrode 20 having a high TCR and the resistor 23 having a low TCR. Therefore, a chip resistor having a better TCR than the conventional resistor can be obtained as shown in FIG.

In the reference example 2 described above, the case where the resistor 23 is formed on the upper surface of the substrate 21 has been described. However, the present invention is not limited to this configuration. For example, the resistor 23 is formed on the back surface of the substrate 21. In this case, or when the resistors 23 are formed on both the upper surface and the back surface of the substrate 21 as shown in FIG. 11, the same effects as those of the reference example 2 can be obtained.

( One embodiment )
Hereinafter, the present invention will be described using an embodiment .

FIG. 7 is a cross-sectional view of a chip resistor according to an embodiment of the present invention, and FIGS. 8A to 8H are manufacturing process diagrams showing a manufacturing method of the chip resistor.

  Below, the manufacturing method is demonstrated based on the manufacturing-process figure shown to Fig.8 (a)-(h).

  First, as shown in FIG. 8A, an insulating sheet-like substrate 31 made of porcelain such as alumina is prepared. Then, an electrode paste mainly composed of silver is screen-printed on the back surface of the sheet-like substrate 31 and fired with a firing profile having a peak temperature of 850 ° C., thereby straddling a plurality of pairs of back electrodes 32 across the primary division grooves 31a. As shown in FIG. The back electrode 32 is not necessarily formed. And when this back electrode 32 is not formed, the end surface electrode 38 mentioned later goes around the back surface of the board | substrate 31, and bears the role of the back electrode 32. FIG.

  Next, as shown in FIG. 8B, a plurality of resistors 33 are formed on the upper surface of the sheet-like substrate 31 by using a material having a low specific resistance and a low TCR, such as a silver-palladium alloy. A plurality are formed so as to cross. Here, the order of the steps of FIG. 8A and FIG. 8B, that is, the order of forming the back electrode 32 and the resistor 33 is not limited to the above order, and the resistor 33 is formed first. The back electrode 32 may be formed later.

  Next, as shown in FIG. 8C, the precoat glass 34 is formed by a screen printing method so as to cover a part of the resistor 33, and is fired with a firing profile having a peak temperature of 600 ° C. In order to adjust the resistance value of the plurality of resistors 33 to a constant value, the resistor 33 is trimmed from above the precoat glass 34 by a laser trimming method to form a trimming groove 36. To do. At this time, by setting the trimming meter reading position 35 when trimming the resistor 33 to substantially the same position as an end portion of a protective film 37 described later, the resistance value after trimming is substantially the same as the resistance value of the finished chip resistor. Therefore, the resistance value accuracy is improved and the product yield is improved.

  Next, as shown in FIG. 8D, a protective film 37 mainly composed of an epoxy resin is formed by a screen printing method so as to cover the plurality of resistors 33 and the precoat glass 34, and a peak temperature of 200 ° C. The protective film 37 is made a stable film by curing with the curing profile of

  Next, as shown in FIG. 8E, a strip-shaped substrate 31c is obtained by dividing the sheet-like substrate 31 along the primary dividing grooves 31a.

  Next, as shown in FIG. 8 (f), the end face electrode 38 is applied with a conductive paste or a thin film so as to electrically connect the resistor 33 and the back face electrode 32 (not shown) to the end face of the strip-shaped substrate 31c. It is formed by sputtering. Note that, when the back electrode 32 is not formed here, the end surface electrode 38 wraps around the back surface of the strip-shaped substrate 31 c and plays the role of the back electrode 32.

  Next, as shown in FIG. 8G, the strip-shaped substrate 31c is divided along the secondary dividing grooves 31b to obtain the piece-shaped substrate 31d.

Finally, as shown in FIG. 8H, the end surfaces of the individual substrate 31d are covered with the surfaces of the resistor 33, the end surface electrode 38, and the back surface electrode 32 (not shown), that is, electrically The plated layer 39 is formed by barrel plating so as to be connected to the chip resistor, and the chip resistor in one embodiment of the present invention is obtained. As shown in FIG. 7, the plating layer 39 has a two-layer structure of a first plating layer 39a usually made of nickel and a second plating layer 39b made of solder or tin.

As shown in FIG. 7, the chip resistor according to the embodiment of the present invention described above is provided between the resistor 33 provided from one end of the upper surface of the substrate 31 to the other end and both end surfaces of the substrate 31. Since a pair of plating layers 39 are electrically connected to a pair of provided end surface electrodes 38 and a top surface electrode that requires firing at a high temperature is not provided, a top electrode having a high TCR and a resistor having a low TCR are provided. The influence of interdiffusion is eliminated, and as a result, a chip resistor having a better TCR than the conventional resistor can be obtained as shown in FIG.

In the embodiment of the present invention described above, the resistor 33 is formed on the upper surface of the substrate 31. However, the present invention is not limited to this configuration. For example, the resistor 33 is formed on the back surface of the substrate 31. Even when the resistor 33 is formed on both the upper surface and the back surface of the substrate 31 as shown in FIG. 12, the same effect as that of the embodiment of the present invention can be obtained.

In Reference Examples 1 and 2 and one embodiment, the plating layers 19, 29, 39 are made of the first plating layers 19 a, 29 a, 39 a made of nickel and the second plating layers 19 b, 29 b made of solder or tin. , 39b has been described as having a two-layer structure, but may be configured with a three-layer structure in which a copper plating layer is formed in front of the first plating layers 19a, 29a, 39a made of nickel. Since the resistance value of the electrode portion of the chip resistor can be reduced, the TCR of the chip resistor can be further improved.

The manufacturing method of the chip resistor according to the present invention reduces the influence of the conventional interdiffusion between the upper surface electrode and the resistor by forming the electrode located on the upper surface of the resistor by plating without firing at a high temperature. Thus, a chip resistor having a low TCR is obtained, and it is useful when applied to a low-resistance type chip resistor that requires particularly high reliability.

Cross-sectional view of the chip resistor in Reference Example 1 (A)-(d) Manufacturing process figure which shows the manufacturing method of the chip resistor (A)-(g) Manufacturing process figure which shows the manufacturing method of the chip resistor Cross-sectional view of the chip resistor in Reference Example 2 (A)-(f) Manufacturing process figure which shows the manufacturing method of the chip resistor (A)-(f) Manufacturing process figure which shows the manufacturing method of the chip resistor Sectional drawing of the chip resistor in one embodiment of this invention (A)-(h) Manufacturing process figure which shows the manufacturing method of the chip resistor The figure which shows TCR of the chip resistor in the conventional chip resistor, the reference examples 1 and 2, and one embodiment of this invention Sectional drawing of the chip resistor which shows the other example of the reference example 1 Sectional drawing of the chip resistor which shows the other example of the reference example 2 Sectional drawing of the chip resistor which shows the other example of one embodiment of this invention Cross-sectional view of a conventional chip resistor

11, 21, 31 Substrate 11a, 21a, 31a Primary division groove 11b, 21b, 31b Secondary division groove 11c, 21c, 31c Strip substrate 11d, 21d, 31d Single piece substrate 13, 23, 33 Resistor 14, 24 Plating resist 15, 25 Electrode 16, 26, 36 Trimming groove 17, 27, 37 Protective film 18, 28, 38 End face electrode 19, 29, 39 Plating layer 19a, 29a, 39a First plating layer 19b, 29b, 39b First 2 plating layer 20 upper surface electrode 34 pre-coated glass 35 trimming meter reading position

Claims (1)

A resistor provided from one end to the other end of the upper surface of the individual substrate, a pair of end surface electrodes provided on both end surfaces of the individual substrate, and a part of the resistor Forming a plurality of resistors on an upper surface of a sheet-like substrate in a manufacturing method of a chip resistor including a protective film covering the substrate and a pair of plating layers that electrically connect the resistor and the pair of end surface electrodes A step of performing trimming on the resistor by positioning a trimming meter on the resistor, and a step of covering a part of the resistor with a protective film so that the trimming metering position in the resistor is an end. And a step of dividing the sheet-like substrate into strip-shaped substrates after the step of covering with the protective film, a step of forming an end face electrode electrically connected to the resistor on the end face of the strip-shaped substrate, After the step of forming the end face electrode, the short Obtaining a piece-like substrate by dividing the Jo substrate, forming a plating layer by barrel plating method so as to cover the surface of the resistor and the end face electrode after the step of obtaining the pieces shaped substrate A chip resistor manufacturing method that does not include a step of forming an upper surface electrode on the resistor.

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