JP2015153944A - Resistor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistor capable of improving humidity resistance and a manufacturing method thereof.SOLUTION: A carbon coating 3 is formed on an insulator 2 having insulation properties and a silicon-based inorganic skeleton 4b in which a glass powder 4a is dispersed is formed on the carbon coating 3, thereby providing a protective film 4. A pair of cap electrodes are mounted via the carbon coating 3, the protective film 4 and the carbon coating 3 are then cut by a rubber cutter, a trimming line 8 is formed that pierces the protective film 4 and a resistance film 3, and a resistance value is adjusted. Glass 4c resulting from melting the glass powder 4a is deposited to cross sections 3a of the carbon coating 3 that is cut when forming the trimming line 8, thereby protecting the cross sections 3a.

Description

  The present invention relates to a resistor used in, for example, an electronic component, and more particularly to a resistor in which a protective film having a silicon-based inorganic skeleton is provided on a resistor film and a method for manufacturing the resistor.

  In general, a resistor made of a carbon film is formed on a cylindrical substrate, and a flame retardant paint (smokeless paint) is applied on the resistor to prevent smoke generation during use. The vessel is known. This type of flame retardant carbon film resistor needs to use a flame retardant paint mainly composed of a silicon-based skeleton resin that is more permeable to moisture than epoxy, in addition to a carbon film that is susceptible to gas and moisture. There is. For this reason, there is a problem of “electric corrosion” in which electrolysis occurs when a voltage is applied in the presence of moisture due to energization over a long period of time, and the resistance value changes.

  Usually, this type of carbon film resistor uses an epoxy resin excellent in moisture permeability resistance in order to prevent intrusion of moisture from the viewpoint of preventing the “electric corrosion”. However, in order to make the resistor flame-retardant, from the point of preventing carbonization and smoke generation at high temperature, a material having as little carbon component as possible is used, and an epoxy resin excellent in moisture permeability cannot be used. It is necessary to use a silica film as the main component.

  The silica film generally has a porous structure and is a film in which a plurality of holes are formed. Therefore, although measures are taken to reduce moisture permeability by mixing many fillers, moisture cannot be completely blocked. For this reason, it can be a silica film combined with other resin materials such as silicone, but the silicone resin itself has a relatively high moisture permeability, and the organic components in the side chain increase, so flame retardant (no smoke) It will reduce the sex.

  As this type of carbon film resistor, for example, as described in Patent Document 1, from the viewpoint of improving moisture resistance stability, a high insulation property is provided between a resistance film such as carbon and a moisture-proof coating film covering the surface. It is disclosed to form a silicone resin layer with little moisture absorption and little change in insulation resistance value due to moisture absorption. For example, as disclosed in Patent Document 2, it is disclosed that a carbon inorganic protective film is formed on a carbon film by top coating with silicon nitride.

Japanese Utility Model Publication No. 38-23638 Japanese Patent Laid-Open No. 54-11497

  In the resistor described in Patent Document 1, since the silicone resin layer actually has moisture permeability, it is necessary to increase the thickness of the silicone resin layer to reduce moisture permeability. In particular, in this patent document 1, there is no description regarding the flame-retardant resin exterior.

  In the carbon film resistor described in Patent Document 2, it is necessary to adjust the resistance value after forming the protective film in order to obtain a resistor having a high resistance value. Trimming to cut a spiral. As a result, the trimmed portion (cutting portion) is exposed because the protective film is cut together with the resistor and the moisture resistance is lowered.

  In this type of carbon film resistor, a carbon protective film is formed on the insulating porcelain by a method such as pyrolysis of a carbon material, but since carbon is easily affected by gas and moisture, the protective film The formation of is an issue. As this protective film, moisture can be completely blocked by using a resin such as olefin or a resin excellent in gas barrier property. However, a resin excellent in gas barrier property generally has thermoplasticity, so that heat generated during energization is generated. There is a risk of melting. Furthermore, since the protective film carbonizes due to heat generation and loses its function as a protective film (protective function), there is a risk of smoking and burning with the carbonization of the protective film. Not suitable for incombustible coating. Even if it is a thermoplastic resin, a resin having a large carbon component is not suitable because it may carbonize, emit smoke, and burn.

  On the other hand, if the protective film of the glass film is used, moisture can be completely blocked and combustion during energization can be eliminated. However, when the glass used as the protective film is melted, a high temperature is required, which is a metal. The thermal expansion coefficient does not match that of the cap electrode, and the protective film cracks. Moreover, in order to cover all the through holes that can be formed in the protective film, it is necessary to heat the glass to at least the region exceeding the pour point of the glass, and the resistance value adjusted by trimming changes due to the heating of the glass. There is a risk.

  Furthermore, although it is desirable to coat the manufactured resistors one by one with a protective film, it is desirable that the number of man-hours required for manufacturing is small in order to reduce the manufacturing cost. For this reason, also in the formation process of this kind of protective film, it is desirable to be able to process from a dipping process to a drying process by batch processing. In the dipping process, the product is immersed in a resin having a low viscosity.

  In order to improve the characteristics, it is desirable to form the protective film by applying a thick film. However, when the protective film is formed by dipping, if the thick film is formed using a high viscosity liquid, the manufactured resistor They may adhere to each other, there may be a place where a protective film cannot be formed, or the thickness of the protective film may not be stable, and it is not easy to form an appropriate protective film. In particular, since the thickness of the protective film is limited to dipping, it is necessary to increase the moisture resistance of the protective film while limiting the film thickness to about 3 μm to 5 μm, for example.

  The present invention has been made from the above-described prior art, and an object thereof is to provide a resistor capable of improving moisture resistance and a method for manufacturing the resistor.

  In order to achieve this object, a method of manufacturing a resistor according to the present invention includes a resistance film forming step of forming a resistance film on an insulating main body, and a silicon system in which glass is dispersed on the resistance film. A protective film forming step of forming an inorganic skeleton to form a protective film; an electrode forming step of providing a pair of electrodes via the resistive film; and cutting the protective film and the resistive film to form the protective film and the resistive film. And a resistance value adjusting step for forming a groove portion penetrating therethrough.

  In the present invention configured as described above, in the state where a silicon-based inorganic skeleton in which glass is dispersed is formed on a resistance film to form a protection film, the protection film and the resistance film are cut to form the protection film and the resistance film. By forming the groove portion penetrating through the side surface portion of the resistance film in which the groove portion is formed is protected with glass, so that the moisture resistance of the resistance film can be improved.

  Moreover, the present invention is characterized in that, in the above invention, the resistance value adjusting step attaches the glass to each side surface of the groove when the protective film and the resistance film are cut.

  In the present invention configured as described above, glass adheres to each side surface portion of the groove portion by cutting the protective film and the resistance film. Therefore, since the side part of the cut resistance film is protected by glass, the moisture resistance of the resistance film can be improved.

  Further, the present invention is the above invention, wherein in the protective film forming step, the protective film is heated by heating at a temperature of less than 250 ° C. in a state where the silicon-based inorganic skeleton in which the glass is dispersed is attached on the resistance film. It is characterized by that.

  The present invention configured as described above is a protective film that can be generated during heating by heating at a temperature of less than 250 ° C. to form a protective film with a silicon-based inorganic skeleton in which glass is dispersed on the resistance film. Generation of cracks can be suppressed.

  Moreover, the present invention is the above invention, wherein in the resistance value adjusting step, the protective film and the resistive film are cut with a cutter, and the glass is cut when the protective film is cut with the cutter in the resistance value adjusting step. It is characterized by melting.

  In the present invention configured as described above, the glass melts when the protective film and the resistance film are cut with a cutter to form the groove, so that the side surface of the cut resistance film is more reliably protected with glass, The moisture resistance of the resistance film can be improved.

  Moreover, the present invention is characterized in that, in the above invention, the glass is dispersed in a silicon-based inorganic skeleton in a powder state.

  Since the present invention configured as described above can uniformly disperse the glass in the protective film, when the protective film and the resistance film are cut to form the groove part, the glass is more reliably applied to each side part of the groove part. Can be attached. Therefore, the side part of the cut resistance film can be more reliably protected with glass, and the moisture resistance of the resistance film can be improved more appropriately.

  The resistor according to the present invention includes an insulating main body, a resistance film formed on the main body, a protective film formed on the resistance film and having a silicon-based inorganic skeleton, and the resistance film. And a pair of electrodes provided, and glass is dispersed in the silicon-based inorganic skeleton of the protective film.

  In the present invention configured as described above, in a state where a protective film having a silicon-based inorganic skeleton in which glass is dispersed is formed on the resistance film, the resistance value is adjusted by cutting the protective film and the resistance film, Since the side part of the cut protective film is covered and protected by glass, the moisture resistance of the resistive film can be improved.

  Further, in the present invention according to the above invention, the protective film and the resistance film are provided with a groove portion penetrating the protective film and the resistance film, and the glass is attached to each side surface portion of the groove portion. It is a feature.

  In the present invention configured as described above, since glass is attached to each side surface of the groove portion that penetrates the protective film and the resistance film, the side surface portion of the resistance film can be protected with glass, and the moisture resistance of the resistance film is reduced. Can be improved.

  The present invention cuts the protective film and the resistive film in a state where the protective film having a silicon-based inorganic skeleton in which glass is dispersed is formed on the resistive film, so that the side surface portion of the cut protective film is made of glass. Since it is covered and protected, the moisture resistance of the resistance film can be improved. Problems, configurations, and effects other than those described above will be clarified from the following description of the embodiments.

It is a front view of the resistor concerning one embodiment of the present invention. It is a cross-sectional view of a part of the resistor. It is longitudinal direction sectional drawing of the said resistor. It is process drawing which shows the manufacturing method of the said resistor, (a) is a main body, (b) is a resistance film formation process, (c) is a protective film formation process, (d) is a resin film formation process, (e) is an electrode. (F) is a resistance value adjusting step, (g) is a lead wire welding step, (h) is an overcoat forming step, and (i) is a color code applying step. It is an electron micrograph which shows the surface of the protective film of the resistor which concerns on Example 1 of this invention. It is explanatory drawing which shows the outline | summary of the electrolytic corrosion acceleration test of the protective film of the resistor which concerns on Example 2 of this invention. 4 is an electron micrograph showing the surface of a protective film of a resistor according to Comparative Example 1. It is a graph which shows the resistance value change after the electrolytic corrosion acceleration test of the protective film of the resistor which concerns on the said Example 2 and Comparative Examples 1 thru | or 3.

(Constitution)
A resistor 1 according to an embodiment of the present invention is, for example, a cylindrical flame retardant carbon film resistor used for electronic components and the like, as shown in FIGS. 2 and 3. The insulator 2 is provided as a main body. The insulator 2 is an insulated porcelain made of an insulating material such as alumina. The surface of the insulator 2 is coated with, for example, carbon to form a carbon film 3 as a resistance film. The carbon film 3 is a carbon resistor film, and is provided on the insulator 2 by, for example, a thermal decomposition method. The surface of the carbon film 3 is covered with a protective film 4.

  The protective film 4 is formed by dipping (immersing) the insulator 2 on which the carbon film 3 is formed in the silicon-based inorganic skeleton 4b solution in which the glass powder 4a is dispersed and then drying, for example, baking at 150 ° C. This is a glass composite protective film as a silicon-based inorganic film. As the glass powder 4a, a low softening point glass having a melting point equal to or lower than the melting point that melts when the trimming line 8 described later is formed, for example, 500 ° C. to 600 ° C. is used. Moreover, the glass powder 4a should just be an outer diameter dimension of the grade which can be disperse | distributed to the silicon-type inorganic frame | skeleton 4b, and 1 micrometer-10 micrometers are preferable by the median value. For example, silica or silicone is used as the silicon-based inorganic skeleton 4b. Note that the surface of the protective film 4 can be covered with the resin film 5 from the viewpoint of improving workability. The resin film 5 improves slipperiness when fitting cap electrodes 6a and 6b, which will be described later, and prevents rubbing when using a parts feeder (not shown). Although the resin film 5 is a resin component and its nonflammability is slightly lowered, there is no problem even if it is used as long as it has a thickness of about 1 μm.

  Cap electrodes 6a and 6b serving as a pair of electrodes are fitted and attached to both ends of the insulator 2 on which the resin film 5 is provided. The cap electrodes 6a and 6b are formed in a substantially cylindrical shape with a bottom made of a conductive metal such as stainless steel, and are attached by press-fitting the cap electrodes 6a and 6b to the end portions in the axial direction of the insulator 2. . As shown in FIG. 1, a lead wire 7 is welded to each cap electrode 6a, 6b by thermocompression bonding or the like. Each lead wire 7 is fixed to the center portion of the end face of the cap electrodes 6 a and 6 b and extends concentrically with the insulator 2.

  As shown in FIG. 2, the protective film 4 and the carbon film 3 between the cap electrodes 6 a and 6 b are provided with trimming lines 8 penetrating the protective film 4 and the carbon film 3. The trimming line 8 is a cut part as a groove part for adjusting the resistance value of the carbon film 3, and is formed in a spiral shape in the circumferential direction of the protective film 4 and the carbon film 3. The trimming line 8 is formed from the protective film 4 and the carbon film 3 to the surface portion of the insulator 2. Glass 4c in which the glass powder dispersed in the protective film 4 is melted adheres to the cut surface portions 3a which are the side surfaces of the carbon film 3 and the protective film 4 cut by the trimming line 8, and this glass 4c. Covered with That is, the cut surface portions 3a are secured to moisture by the glass 4c.

  The protective film 4 including the trimming line 8 and the surfaces of the cap electrodes 6 a and 6 b are covered with an external protective layer 9. The external protective layer 9 is an overcoat layer formed by applying a nonflammable exterior paint to the insulator 2 to which the cap electrodes 6a and 6b and the lead wires 7 are attached and the trimming line 8 is formed, followed by drying and curing. It is. That is, the external protective layer 9 covers the end portions of the lead wires 7 welded to the cap electrodes 6a and 6b in addition to the surface of the protective film 4 including the trimming line 8 and the cap electrodes 6a and 6b. On the surface of the external protective layer 9, a color code 10 indicating the resistance value of the carbon film 3 between the cap electrodes 6a and 6b is displayed.

(Production method)
Next, a method for manufacturing the resistor 1 according to the first embodiment will be described with reference to FIG. Here, FIG. 4 is a process diagram showing a method of manufacturing the resistor 1, wherein (a) is an insulator 2, (b) is a resistance film forming process, (c) is a protective film forming process, and (d) is a resin film. (E) is an electrode forming step, (f) is a resistance value adjusting step, (g) is a lead wire welding step, (h) is an overcoat forming step, and (i) is a color code applying step.

  First, a carbon film is formed on the surface of the insulator 2 shown in FIG. 4A by a thermal decomposition method to form a carbon film 3 (resistance film forming step: FIG. 4B).

  Next, the insulator 2 coated with the carbon film 3 is dipped into a silicon-based inorganic skeleton 4b solution in which the glass powder 4a is dispersed and then dried, and then baked at, for example, 150 ° C. to form the protective film 4. (Protective film forming step: FIG. 4C).

  When forming the resin film 5 for improving workability, the insulator 2 on which the protective film 4 is formed is dipped in the resin solution constituting the resin film 5 and then dried, and then baked at, for example, 125 ° C. Then, the resin film 5 is formed (resin film forming step: FIG. 4D).

  Further, the cap electrodes 6a and 6b are press-fitted and fixed to both ends of the insulator 2 on which the protective film 4 is formed, for example. At this time, when the cap electrodes 6a and 6b are press-fitted, the protective film 4 formed on the insulator 2 is scraped, but the carbon film 3 having hardness cannot be scraped. Therefore, as shown in FIG. 6a and 6b come into contact with the carbon coating 3 and become electrically conductive (electrode formation step: FIG. 4 (e)).

  Thereafter, while measuring the resistance value between the cap electrodes 6a and 6b, the insulator 2 to which the cap electrodes 6a and 6b are attached is rotated in the circumferential direction, and the width dimension of, for example, about 70 μm to 100 μm is formed on the protective film 4. The protective film 4 and the carbon film 3 are moved until the resistance value between the cap electrodes 6a and 6b reaches a predetermined value while gradually moving in the axial direction while pressing a rubber cutter (not shown) having The trimming line 8 is spirally formed (resistance value adjusting step: FIG. 4F).

  Next, the lead wire 7 is welded to the end of each cap electrode 6a, 6b by thermocompression bonding or the like (lead wire welding process: FIG. 4G).

  Further, an external protective layer 9 is formed on the protective film 4 including the trimming line 8 between the lead wires 7 and the cap electrodes 6a and 6b by supporting each end of the lead wire 7 and rolling on a predetermined roller. The solution to be applied is applied and overcoated (roller coated), and then dried to form the outer protective layer 9 (overcoat forming step: FIG. 4 (h)).

  Further, a color code 10 indicating the resistance value between the lead wires 7 is displayed on the surface of the external protective layer 9 (color code applying step: FIG. 4 (i)).

(Function and effect)
As described above, according to the resistor 1 according to the above-described embodiment, the protective film 4 is formed by dispersing the glass powder 4a melted when the trimming line 8 is formed by the rubber cutter in the silicon-based inorganic skeleton 4b. For this reason, when the trimming line 8 is formed on the protective film 4 and the carbon film 3 with the protective film 4 formed on the carbon film 3, the glass powder 4a in the protective film 4 is melted. As a result, the glass powder 4a is adhered to each cut surface portion 3a of the carbon film 3 cut by the trimming line 8 as glass 4c in a melted state, and the cut surface portions 3a are protected by the glass 4c. The moisture resistance of the film 3 can be improved.

  In particular, the glass powder 4 b having a small particle diameter is dispersed in the silicon-based inorganic skeleton 4 b constituting the protective film 4, whereby the glass powder 4 b can be uniformly dispersed in the protective film 4. Therefore, when the protective film 4 and the carbon film 3 are cut to form the trimming line 8, the glass 4 c can be more reliably attached to each cut surface portion 3 a of the carbon film 3. Therefore, the portion where the protective film 4 is removed when the trimming line is formed, that is, each cut surface portion 3a of the carbon film 3 can be protected by the glass 4c in which the glass powder 4a in the protective film 4 is melted. The moisture resistance of can be improved more appropriately.

  Further, as a result of the experiment, after applying the silicon-based inorganic skeleton 4b in which the glass powder 4a is dispersed on the carbon film 3, the protective film 4 is formed by heating at a temperature of less than 250 ° C. The occurrence of cracks in the protective film 4 to be obtained can be suppressed.

  In the resistor 1 according to the above embodiment, the resin film 5 is formed on the protective film 4 when improving workability. However, since the resin film 5 is a resin component, the resin film 5 has nonflammability characteristics. Since it has a slightly degrading characteristic, it does not have to be formed on the protective film 4.

  Moreover, as glass powder disperse | distributed to the protective film of the resistor 1 which concerns on the said one embodiment, besides SNG-26A / F014 (Nippon Electric Glass Co., Ltd. product: center diameter 2.58 micrometer) mentioned later, GA-59 ( Nippon Electric Glass Co., Ltd .: softening point 645 ° C.), BF0901 (Nippon Electric Glass Co., Ltd .: softening point 528 ° C.), ASF1109 (Asahi Glass Co., Ltd .: center diameter 2.8 μm, softening point 537 ° C.), ASF 1898 (Asahi Glass) Low softening point glass such as manufactured by Co., Ltd .: center diameter 1.1 μm, softening point 527 ° C., ASF1100 (Asahi Glass Co., Ltd .: center diameter 5.2 μm, softening point 510 ° C.) can also be used.

  Next, Examples 1 and 2 and Comparative Examples 1 to 3 of the resistor 1 according to the present invention will be described.

<Example 1> (Processing liquid)
15 g of tetraalkoxysilane, 60 g of phenyltrialkoxysilane, 200 g of IPA (isopropyl alcohol), 20 g of distilled water, and 0.4 g of nitric acid (69% to 70%) are mixed and subjected to hydrolysis and polycondensation to obtain a siloxane oligomer mixed solution Create Next, 1 g of polyalkylsiloxane (manufactured by YR-3340 Momentive Performance Materials Japan Godo Kaisha) is put into this mixed solution, and stirred until the siloxane in this mixed solution is completely dissolved. Thereafter, 6.6 g of low softening point glass (SNG-26A / F014 [central diameter 2.58 μm] manufactured by Nippon Electric Glass Co., Ltd.) was added, and the mixture was stirred and dispersed for 5 minutes to obtain Treatment Solution 1.

  1 g of polyalkylsiloxane (YR-3340 Momentive Performance Materials Japan GK) was added to the siloxane oligomer mixed solution, and the mixture was stirred for 5 minutes to obtain Treatment Solution 2.

  Further, 15 g of tetraalkoxysilane, 60 g of phenyltrialkoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), 1 g of aluminum tri-sec-butoxide, 200 g of IPA, 20 g of distilled water, and 0.4 g of nitric acid (69% to 70%) are mixed. Hydrolysis and condensation polymerization are performed to prepare a siloxane oligomer mixed solution. Then, 1 g of polyalkylsiloxane (manufactured by YR-3340 Momentive Performance Materials Japan Godo Kaisha) is put into this mixed solution, and stirred until the siloxane in this mixed solution is completely dissolved. did.

(Curing temperature)
A carbon film forming body in which a resistor (resistance value after forming a cap electrode is 398Ω to 501Ω) formed with a carbon film 3 on an insulator 2 is dipped in a phenol resin and then dried in an air atmosphere at 100 ° C. The carbon film formed body is immersed in the treatment liquid 1 and then dried while being swung. Thereafter, the heating temperature in the atmosphere was changed to 150 ° C., 200 ° C., 250 ° C., 300 ° C., 400 ° C., and 450 ° C. to form the protective film 4 on the carbon film forming body.

  Regarding the appearance of these protective films 4, the surface of the silicon-based inorganic skeleton 4b portion, which is a semi-transparent inorganic film portion in the protective film 4, was confirmed with an electron microscope. As shown in FIG. In the case of temperature, the protective film 4 was not cracked. On the other hand, in the case of a heating temperature of 300 ° C. or higher, a remarkable crack C was confirmed in the protective film 4.

  As described above, by forming the protective film 4 heated at a temperature lower than 250 ° C., it is possible to suppress the occurrence of cracks that may occur during the heat treatment. That is, if the heating temperature at the time of forming the protective film is set to a high temperature of 300 ° C. or higher, cracks are generated in the protective film 4, and water penetrates from the generated cracks to cause galvanic corrosion. Therefore, when forming the protective film, it is necessary to cure by heating at a temperature as low as possible, preferably less than 250 ° C., to suppress the generation of cracks.

<Example 2> (silica + silicone + glass powder)
A resistor having a carbon film 3 formed on the insulator 2 (the resistance value after forming the cap electrode is 398Ω to 501Ω) is prepared, and the carbon film formed body is immersed in the treatment liquid 1 and then rocked. dry. Thereafter, heat treatment was performed in an air atmosphere at 150 ° C., and a protective film 4 having a thickness of 3 μm to 5 μm was formed on the carbon film 3.

  When the appearance of the protective film 4 was confirmed with an electron microscope, glass powder particles (glass powder 4a) could be confirmed on the translucent inorganic film in the protective film 4. Further, after cap electrodes 6a and 6b are attached to both ends of the carbon film forming body on which protective film 4 is formed, trimming is performed with a rubber cutter so that the resistance value between cap electrodes 6a and 6b is 100 kΩ. Then, after the trimming line 8 was formed, the following electrolytic corrosion acceleration test was performed.

(Electrolytic corrosion acceleration test)
As shown in FIG. 6, the resistor 1 without the external protective layer 9 is submerged in the pure water W, and 0.1 W according to the resistance value of each resistor 1 so that the heat generated by the resistor 1 is constant. The electric power (approx. 100V in DC) was applied, and the resistance value after energization for 1, 2, 3, 5, and 8 minutes was measured. The resistance value was measured after being pulled up from the pure water W and allowed to cool at room temperature for 5 minutes. As a result, as shown in FIG. 8, the change in resistance value after application for 5 minutes was 8%, and the change in resistance value after application for 8 minutes was about 10%.

<Comparative Example 1> (Silica + Silicone film)
The carbon film forming body prepared in Example 2 was dipped in the treatment liquid 2 and then dried, and heat treatment was performed in an air atmosphere at 150 ° C. to form the protective film 4 shown in FIG. Thereafter, after the cap electrodes 6a and 6b are attached, the trimming ryan 8 is formed by trimming with a rubber cutter so that the resistance value between the cap electrodes 6a and 6b is 100 kΩ, and then the same as in the second embodiment. An electroerosion acceleration test was conducted. As a result, as shown in FIG. 8, the change in resistance value after application for 5 minutes was 15%, and the change in resistance value after application for 8 minutes was more than 19%.

<Comparative Example 2> (Silica + Silicone + Alumina)
The carbon film forming body prepared in Example 1 was dipped in the treatment liquid 3 and then dried, and heat treatment was performed in an air atmosphere at 150 ° C. to form a protective film. Thereafter, similarly to the comparative example 1, after the trimming line 8 was formed so that the resistance value between the cap electrodes 6a and 6b was 100 kΩ, the electrolytic corrosion acceleration test similar to the above-described example 2 was performed.

  As a result, as shown in FIG. 8, the change in resistance value after application for 5 minutes was 11%, and the change in resistance value after application for 8 minutes was about 20%. As described above, by containing alumina in the protective film 4, the alumina component permeates into the carbon film 3, so that although the protective film 4 has low immersion moisture, the electric corrosion from the trimming line 8 cannot be suppressed. Therefore, the resistance value change is large.

<Comparative Example 3> (No protective film)
After the cap electrodes 6a and 6b are attached to both ends of the carbon film formed body produced in Example 1, the trimming line is trimmed with a rubber cutter so that the resistance value between the cap electrodes 6a and 6b is 100 kΩ. After forming 8, the same electrolytic corrosion acceleration test as in Example 2 was performed. As a result, as shown in FIG. 8, the change in resistance value after application for 5 minutes was 38%, and the change in resistance value after application for 8 minutes was more than 80%.

<Result>
By the above, by setting it as the protective film 4 (silica + silicone + glass powder) which concerns on the said Example 2, the said comparative example 1 (silica + silicone + alumina), the comparative example 2 (silica + silicone + alumina), and a comparative example Compared with the case of 3 (no protective film), the resistance value change is small as a result of the electrolytic corrosion acceleration test. Therefore, by forming the protective film 4 in which the glass powder 4a is dispersed in the silicon-based inorganic skeleton 4b composed of silica and silicone, it is possible to more appropriately suppress the occurrence of electrolytic corrosion and to further improve the moisture resistance. It turned out that it can improve appropriately.

  Furthermore, although it is desirable to form the protective film 4 thinly on the carbon film 3, if the protective film 4 is extremely thin, cracks are generated at the time of formation, and the function as the protective film 4 cannot be achieved. On the other hand, by appropriately adjusting the viscosity of the treatment liquid containing alumina having excellent moisture permeability, the protective film 4 having a thickness of about 3 μm to 5 μm is obtained by immersing the carbon film forming body in this treatment liquid. Can be formed. However, the protective film 4 with few cracks can be formed by including the glass powder 4a whose thermal expansion is close to that of the silica-based inorganic film as a filler in the protective film 4 as compared with other inorganic materials.

1 resistor 2 insulator (body)
3 Carbon film (resistive film)
3a Cut surface part 4 Protective film 4a Glass powder (glass)
4b Silicon-based inorganic skeleton 4c Glass 5 Resin film 6a, 6b Cap electrode (electrode)
7 Lead wire 8 Trimming line (groove)
9 External protective layer 10 Color code C Crack W Pure water

Claims (7)

A resistive film forming step of forming a resistive film on the insulating main body;
A protective film forming step of forming a silicon-based inorganic skeleton in which glass is dispersed on the resistance film to form a protective film;
An electrode forming step of providing a pair of electrodes via the resistive film;
A resistance value adjusting step of cutting the protective film and the resistance film to form a groove portion penetrating the protective film and the resistance film;
A method of manufacturing a resistor, comprising: In the manufacturing method of the resistor of Claim 1,
In the resistance value adjusting step, the glass is attached to each side surface portion of the groove portion when the protective film and the resistance film are cut. In the manufacturing method of the resistor of Claim 1 or 2,
The protective film forming step includes heating the silicon-based inorganic skeleton in which the glass is dispersed on the resistance film at a temperature of less than 250 ° C. to form the protective film. Manufacturing method. In the manufacturing method of the resistor in any one of Claim 1 thru | or 3,
In the resistance value adjusting step, the protective film and the resistance film are cut with a cutter,
The method of manufacturing a resistor, wherein the glass is melted when the protective film is cut by the cutter in the resistance value adjusting step. In the manufacturing method of the resistor in any one of Claims 1 thru | or 4,
The method for producing a resistor, wherein the glass is dispersed in a silicon-based inorganic skeleton in a powder state. An insulating body;
A resistive film formed on the body;
A protective film formed on the resistance film and having a silicon-based inorganic skeleton;
A pair of electrodes provided via the resistance film,
A resistor in which glass is dispersed in the silicon-based inorganic skeleton of the protective film. The resistor of claim 6, wherein
The protective film and the resistance film are provided with a groove that penetrates the protective film and the resistance film.
The resistor is characterized in that the glass is attached to each side surface of the groove.