WO2021145269A1 - Electroconductive paste, electrode and chip resistor - Google Patents

Electroconductive paste, electrode and chip resistor Download PDF

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Publication number
WO2021145269A1
WO2021145269A1 PCT/JP2021/000345 JP2021000345W WO2021145269A1 WO 2021145269 A1 WO2021145269 A1 WO 2021145269A1 JP 2021000345 W JP2021000345 W JP 2021000345W WO 2021145269 A1 WO2021145269 A1 WO 2021145269A1
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Prior art keywords
electrode
conductive paste
weight
glass frit
alloy particles
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PCT/JP2021/000345
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French (fr)
Japanese (ja)
Inventor
喜昭 吉井
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ナミックス株式会社
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Priority to CN202180009442.0A priority Critical patent/CN114930467A/en
Priority to KR1020227026685A priority patent/KR20220123286A/en
Priority to JP2021571163A priority patent/JPWO2021145269A1/ja
Publication of WO2021145269A1 publication Critical patent/WO2021145269A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material

Definitions

  • the present invention relates to, for example, a conductive paste used for forming electrodes of electronic components.
  • the present invention also relates to an electrode formed by using the conductive paste and a chip resistor having the electrode.
  • FIG. 1 shows an example of the cross-sectional structure of the chip resistor 100.
  • the chip resistor 100 has a rectangular alumina substrate 102, and a resistor 104 and a take-out electrode 106 for extracting electricity from the resistor 104 are formed on the upper surface of the alumina substrate 102. Further, on the lower surface of the alumina substrate 102, a lower surface electrode 108 for mounting the chip resistor 100 on the substrate is formed. Further, a connection electrode 110 for connecting the take-out electrode 106 and the lower surface electrode 108 is formed on the end surface of the alumina substrate 102.
  • the take-out electrode 106 and the lower surface electrode 108 are formed by applying a conductive paste to the upper surface and the lower surface of the alumina substrate 102 by printing and then firing them.
  • a nickel plating film 112 and a tin plating film 114 are generally formed on the take-out electrode 106, the bottom electrode 108, and the connection electrode 110.
  • the take-out electrode 106 and the bottom electrode 108 have different required characteristics, they are generally formed by using different conductive pastes. For example, a conductive paste having good matching with the resistor 104 is used for forming the take-out electrode 106. Further, when the resistance value of the resistor 104 is low, the resistance value of the take-out electrode 106 is also required to be low. Therefore, a conductive paste capable of forming a low resistance electrode is used for forming the take-out electrode 106.
  • Fossil fuels are being burned in automobiles and thermal power plants, and a large amount of sulfur oxides are emitted into the atmosphere. Further, in sewage treatment plants and waste treatment plants, sulfur is reduced by anaerobic bacteria to generate hydrogen sulfide. Therefore, sulfur-containing components such as sulfur oxides and hydrogen sulfide are present in the atmosphere.
  • the sulfur component in the atmosphere reaches the surface of silver, the sulfur component adheres to the surface of silver and reacts with silver to become silver sulfide.
  • an electrode made of silver as a main material such as an electrode of a chip resistor
  • the same reaction occurs, so that the silver inside the electrode may become silver sulfide. If silver sulfide is generated inside the electrode, the electrode may be broken. Therefore, a device such as a chip resistor having an electrode made of silver may malfunction. Such a phenomenon is called disconnection due to sulfurization.
  • an electrode with high sulfurization resistance is required for the silver-based electrode used in devices such as chip resistors.
  • an object of the present invention is to provide a conductive paste having high sulfurization resistance, low resistance, and capable of forming an electrode at a relatively low cost.
  • the present invention has the following configuration.
  • (Structure 1) Configuration 1 of the present invention comprises (A) alloy particles containing Ag and Sn, and (B) Glass frit and (C) Containing with a thermoplastic resin, (A) A conductive paste in which the weight ratio of Sn in the alloy particles is less than 10% by weight.
  • (Structure 2) Configuration 2 of the present invention is the conductive paste of Configuration 1 in which the weight ratio of Ag in the alloy particles (A) is 50% by weight or more.
  • Configuration 3 of the present invention is the conductive paste of configuration 1 or 2, wherein the content of the glass frit (B) is 2 to 20 parts by weight with respect to 100 parts by weight of the alloy particles (A).
  • Constituent 4 of the present invention is the conductive paste according to any one of Constituents 1 to 3, further comprising (D) silica filler.
  • the glass frit (B) contains SiO 2 and TiO 2.
  • Configuration 6 of the present invention is an electrode obtained by firing any of the conductive pastes of configurations 1 to 5.
  • Configuration 7 of the present invention is a chip resistor having the electrode according to configuration 6.
  • FIG. 1 It is a schematic diagram which shows an example of the cross-sectional structure of a chip resistor.
  • the conductive paste of this embodiment contains (A) alloy particles, (B) glass frit, and (C) thermoplastic resin.
  • the conductive paste of the present embodiment can be preferably used to form an electrode of a device such as a chip resistor having an electrode made of silver as a material.
  • the conductive paste of the present embodiment contains (A) alloy particles.
  • the alloy particles (A) contain silver (Ag) and tin (Sn). Since the alloy particles (A) contain Sn, the sulfide of Ag can be suppressed. Therefore, by using the conductive paste of the present embodiment, it is possible to form an electrode having high sulfurization resistance.
  • the alloy particles (A) can contain metals other than Ag and Sn. However, in order to surely obtain an electrode having low electric resistance and high sulfurization resistance, it is preferable that the alloy particles (A) consist only of Ag and Sn.
  • alloy particles consist only of Ag and Sn means that metal other than Ag and Sn is intentionally not mixed as (A) metal particles, and it is unavoidable. It does not exclude the inclusion of metals other than Ag and Sn that are mixed with the target.
  • the alloy particles (A) can contain metals such as Zn, In, Al and Si as metals other than Ag and Sn as long as the effects of the present embodiment are not impaired.
  • the weight ratio of Sn in the alloy particles (A) is preferably less than 10% by weight. More specifically, the weight ratio of Sn in the alloy particles (A) is preferably 1% by weight or more and less than 10% by weight, and more preferably 1.5% by weight or more and 9% by weight or less. It is more preferably 4% by weight or more and 8% by weight or less, and particularly preferably 4% by weight or more and 8% by weight or less. If the weight ratio of Sn is too large, the electrical resistance as an electrode may become too high. Further, when the weight ratio of Sn is small, the improvement in sulfurization resistance may be small. In particular, when the weight ratio of Sn is less than 2% by weight, the sulfurization resistance may be easily deteriorated.
  • the weight ratio of Ag in the alloy particles (A) is preferably 50% by weight or more, more preferably 70% by weight or more, and more than 90% by weight. More preferred.
  • the electrical resistance of Ag is low compared to other metals. Therefore, when the weight ratio of Ag is in a predetermined range, an electrode having a relatively low electric resistance can be obtained.
  • the shape of the alloy particles (A) is not particularly limited, and for example, spherical, granular, flake-like and / or scaly alloy particles can be used.
  • the average particle size of the alloy particles (A) is preferably 0.1 ⁇ m to 10 ⁇ m, more preferably 0.1 ⁇ m to 7 ⁇ m, and most preferably 1 ⁇ m to 5 ⁇ m.
  • the average particle size referred to here means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
  • the method for producing the alloy particles (A) is not particularly limited, and can be produced by, for example, a reduction method, a pulverization method, an electrolytic method, an atomizing method, a heat treatment method, or a combination thereof.
  • the flake-shaped alloy particles can be produced, for example, by crushing spherical or granular alloy particles with a ball mill or the like.
  • the conductive paste of the present embodiment includes (B) glass frit.
  • the glass frit (B) preferably contains SiO 2 and TiO 2.
  • the adhesion strength of the electrode obtained by firing the conductive paste to the substrate is improved.
  • the glass frit is not particularly limited, but a glass frit having a softening point of 300 ° C. or higher, more preferably a softening point of 400 to 900 ° C., and further preferably a softening point of 500 to 800 ° C. can be used.
  • the softening point of the glass frit can be measured using a thermogravimetric measuring device (for example, TG-DTA2000SA manufactured by BRUKER AXS).
  • glass frit examples include glass frit such as titanium borosilicate type (TiO 2 type) and barium borosilicate type.
  • glass frit examples include bismuth borosilicate, alkali metal borosilicate, alkaline earth metal borosilicate, zinc borosilicate, lead borosilicate, lead borate, lead silicate, and bismus borate.
  • glass frit such as system and zinc borate type. These glass frit can also be used by mixing two or more kinds.
  • the glass frit is preferably lead-free from the viewpoint of environmental consideration.
  • the glass frit preferably contains at least one selected from the group consisting of ZnO, BaO, Na 2 O, Ca O and Al 2 O 3.
  • the glass frit more preferably contains ZnO, BaO, Na 2 O and Al 2 O 3.
  • the average particle size of the glass frit is preferably 0.1 to 20 ⁇ m, more preferably 0.2 to 10 ⁇ m, and most preferably 0.5 to 5 ⁇ m.
  • the average particle size referred to here means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
  • the content of (B) glass frit is preferably 1 to 20 parts by weight, preferably 1.5 to 15 parts by weight, based on 100 parts by weight of the alloy particles (A). More preferably, it is more preferably 2 to 10 parts by weight.
  • the content of the glass frit is less than this range, the adhesion of the electrode obtained by firing the conductive paste to the substrate is lowered.
  • the content of the glass frit is higher than this range, the resistance value of the electrode obtained by firing the conductive paste becomes high.
  • the content of the glass frit is relatively small, an electrode having low resistance can be obtained. Further, when the content of the glass frit is relatively large, an electrode having excellent chemical resistance can be obtained.
  • Chemical resistance is a characteristic required because a plating pretreatment is required when a plating film is formed on the surface of the electrode.
  • the pre-plating treatment is performed for the purpose of removing contaminants from the surface of the electrode, activating the surface of the electrode, and making the surface of the electrode a clean state suitable for plating.
  • Pollutants to be removed can be broadly divided into organic and inorganic.
  • the pretreatment step is not a single step of removing all contaminants. For example, organic substances are removed in a process using an alkaline cleaning agent. Inorganic substances are removed in a process using an acid-based cleaning agent. Therefore, the electrodes are required to have high chemical resistance.
  • the glass frit softens as the temperature rises, and silver sintering progresses. If the glass frit content is high, the glass component may be extruded onto the surface of the sintered body. In that case, the surface of the sintered body may be covered with a glass component.
  • the sintered body By forming a nickel plating film on the surface of the sintered body, not only can the diffusion of tin from the tin plating film to the electrodes be suppressed, but also when the surface of the sintered body is covered with a glass component, the sintered body It is possible to improve the conductivity. Since the alloy particles (A) of the present embodiment are alloy particles containing Ag and Sn, their sinterability is lower than that of Ag particles.
  • Thermoplastic Resin contains (C) a thermoplastic resin.
  • Thermoplastic resin connects silver powders together in a conductive paste.
  • thermoplastic resin one that is burnt down during firing of the conductive paste can be used.
  • thermoplastic resin for example, cellulose-based resins such as ethyl cellulose and nitrocellulose, acrylic resins, alkyd resins, saturated polyester resins, butyral resins, polyvinyl alcohol, hydroxypropyl cellulose and the like can be used. These resins can be used alone or in admixture of two or more.
  • the content of the (C) thermoplastic resin is preferably 0.5 to 40 parts by weight, more preferably 1 to 35 parts by weight, based on 100 parts by weight of the alloy particles (A).
  • the content of the thermoplastic resin in the conductive paste is within the above range, the coating property of the conductive paste on the substrate and the paste leveling property are improved, and the printed shape is excellent.
  • the content of the thermoplastic resin exceeds the above range, the amount of the thermoplastic resin contained in the conductive paste is too large. Therefore, the electrodes may not be formed with high accuracy.
  • the conductive paste of the present embodiment preferably further contains (D) silica filler.
  • silica filler (D) for example, spherical silica (SiO 2 ) particles commercially available as a semiconductor encapsulating material can be used.
  • the shape of the silica filler may be a shape other than a spherical shape.
  • the method for producing the silica filler is not particularly limited, and a silica filler produced by a known method such as a thermal spraying method can be used.
  • the average particle size of the silica filler is preferably 20 nm or more and 5 ⁇ m or less, and more preferably 1 ⁇ m or more and 3 ⁇ m or less.
  • the average particle size referred to here means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
  • the glass frit contains SiO 2 and TiO 2
  • the chemical resistance of the obtained electrode is improved.
  • the amount of silica filler is too large, the resistance value of the obtained electrode becomes high, and it becomes difficult to obtain a low resistance electrode.
  • the (D) silica filler has the same function as the (B) glass frit. Therefore, the ratio of the weight B of SiO 2 contained in (B) the glass frit and the weight D of SiO 2 contained in (D) the silica filler is within the range of the ratio as described above, so that the resistance is appropriate. Chemical properties can be obtained, and an electrode having low resistance can be obtained.
  • the conductive paste of the present embodiment may contain (E) a solvent.
  • the solvent include alcohols such as methanol, ethanol and isopropyl alcohol (IPA), organic acids such as ethylene acetate, aromatic hydrocarbons such as toluene and xylene, and N-methyl-2-pyrrolidone (NMP).
  • the content of the solvent is not particularly limited.
  • the content of the solvent is preferably 1 to 100 parts by weight, more preferably 5 to 60 parts by weight, based on 100 parts by weight of the alloy particles (A).
  • the viscosity of the conductive paste of the present embodiment is preferably 50 to 700 Pa ⁇ s (shear velocity: 4.0 sec -1 ), more preferably 100 to 300 Pa ⁇ s (shear velocity: 4.0 sec -1 ).
  • the viscosity of the conductive paste can be measured by using an HB type viscometer SC4-14 spindle (manufactured by Brookfield).
  • the conductive paste of the present embodiment may contain other additives such as a dispersant, a rheology adjuster, and a pigment.
  • the conductive paste of the present embodiment can be produced by mixing each of the above components using, for example, a Raikai machine, a pot mill, a three-roll mill, a rotary mixer, and / or a twin-screw mixer. ..
  • This embodiment is an electrode obtained by firing the conductive paste of the above-mentioned embodiment.
  • This embodiment is an electrode formed from the above-mentioned conductive paste of this embodiment as a material.
  • the electrode of the present embodiment can be obtained by applying a conductive paste to a substrate and firing it. Therefore, the electrode of the present embodiment can contain alloy particles containing (A') Ag and Sn, and a (B') glass component made of glass frit as a material.
  • the (A') alloy particles are in a sintered state.
  • the weight ratio of Sn in the (A') alloy particles of the electrode of the present embodiment is less than 10% by weight. Since the (C) thermoplastic resin and (E) solvent contained in the conductive paste are vaporized or burned during firing, the electrodes are substantially free of (C) thermoplastic resin and (E) solvent. ..
  • the electrode of this embodiment can further contain (D') silica filler in addition to (A') alloy particles and (B') glass component. Further, in the electrode of the present embodiment, the weight ratio of Ag in the (A') alloy particles, the content of the (B') glass component and the composition of the (B') glass component are contained in the conductive paste as the material. It corresponds to the weight ratio and composition of (A) alloy particles and (B) glass frit.
  • the sheet resistance of the thin film used as the electrode of the present embodiment varies depending on the film thickness, but can be approximately 10 m ⁇ / ⁇ (10 m ⁇ / square) or 10 m ⁇ / ⁇ or less. Therefore, it can be preferably used for forming an electrode that is required to have a low resistance.
  • the conductive paste is applied onto the substrate.
  • the coating method is arbitrary, and for example, it can be coated using a known method such as dispense, jet dispense, stencil printing, screen printing, pin transfer, or stamping.
  • the conductive paste applied on the substrate is fired at 500 to 900 ° C., more preferably 600 to 900 ° C., and even more preferably 700 to 900 ° C.
  • the solvent component contained in the conductive paste evaporates at 300 ° C. or lower, and the resin component is burnt at 400 ° C. to 600 ° C. to form a fired body of the conductive paste.
  • the electrode thus obtained has high chemical resistance and excellent adhesion to the substrate.
  • This embodiment is a chip resistor having the above-mentioned electrodes.
  • the conductive paste of this embodiment can be used for forming circuits of devices such as electronic components, forming electrodes, and joining devices such as electronic components to a substrate. Further, the conductive paste of the present embodiment can be preferably used for forming an electrode of a chip resistor.
  • FIG. 1 shows an example of the cross-sectional structure of the chip resistor 100 of the present embodiment.
  • the chip resistor 100 can have a rectangular alumina substrate 102, a resistor 104 arranged on the surface of the alumina substrate 102, and a take-out electrode 106.
  • the extraction electrode 106 is an electrode for extracting electricity from the resistor 104.
  • a lower surface electrode 108 for mounting the chip resistor 100 on the substrate can be arranged on the lower surface of the alumina substrate 102.
  • a connection electrode 110 for connecting the take-out electrode 106 and the bottom electrode 108 can be arranged on the end surface of the alumina substrate 102.
  • the conductive paste of the present embodiment can be used to form at least one of a take-out electrode 106, a bottom electrode 108, and a connection electrode 110.
  • the take-out electrode 106 is preferably formed using the conductive paste of the present embodiment.
  • the nickel plating film 112 and the tin plating film 114 can be arranged on the upper surfaces of the take-out electrode 106, the lower surface electrode 108, and the connection electrode 110 (the surface opposite to the alumina substrate 102).
  • the conductive paste of the present embodiment it is possible to form an electrode having high sulfurization resistance, low resistance, and relatively low cost, so that a chip resistor in which a highly reliable electrode is formed is formed.
  • An electronic device such as a vessel can be obtained.
  • the average particle size means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
  • Metal particles A4 Ag particles, average particle size (D50) 2.5 ⁇ m
  • Thermoplastic resin Thermoplastic resin C1 Ethyl cellulose resin (STD-200, manufactured by Dow Chemical Co., Ltd.)
  • Thermoplastic resin C2 Ethyl cellulose resin (STD-4, manufactured by Dow Chemical Co., Ltd.)
  • (D) Silica filler The following silica filler was used as the (D) silica filler. Spherical silica (SiO 2 ) powder, average particle size (D50) 2 ⁇ m
  • a test piece was prepared by the following procedure. First, a conductive paste was applied by screen printing on an alumina substrate of 20 mm ⁇ 20 mm ⁇ 1 mm (t). As a result, 20 patterns having a square pad shape with a side of 1.5 mm were formed on the alumina substrate. A stainless steel 250 mesh mask was used to form the pattern. Next, the conductive paste was dried at 150 ° C. for 10 minutes using a hot air dryer. After the conductive paste was dried, the conductive paste was fired using a firing furnace. The firing temperature is 850 ° C. for 10 minutes, and the total firing time is 60 minutes.
  • the sheet resistance R 0 was measured by the 4-terminal method using a tester.
  • a sulfurization resistance test in a high sulfur environment was performed according to ASTM B809-95 (60 ° C., 1000 hours). That is, 200 g of a 0.5 wt% potassium nitrate aqueous solution is placed in the bottom of the desiccator, 50 g of sulfur powder and a test piece are placed on a perforated plate, the desiccator is covered, and the mixture is stored at 60 ° C. for 1000 hours. The accelerated test of sulfide of the electrode was performed.
  • FIG. 2 shows an SEM photograph of a cross section of a test piece prepared under the same conditions as in Example 4 in which the rate of change in sheet resistance was relatively small, taken with a scanning electron microscope (SEM) at a magnification of 1500 times.
  • FIG. 3 shows an SEM photograph of a cross section of a test piece prepared under the same conditions as in Comparative Example 3 (which was an insulator) having a large rate of change in sheet resistance, taken by SEM at a magnification of 1500 times.
  • the test piece was stored in a sulfur atmosphere (60 ° C.) for 1000 hours, and then SEM observed.
  • the electrode patterns obtained by firing the conductive pastes of Examples 1 to 10 had a rate of change in sheet resistance of 11% or less, which was relatively low.
  • the rate of change in sheet resistance is 95% or more, or the sheet resistance after storage in the sulfide acceleration test is high. It was too much to measure.
  • a silver sulfide film is deposited on the surface of the electrode, but sulfur does not penetrate into the inside of the electrode. Therefore, no cracks or the like were observed inside the electrode. That is, in the example shown in FIG. 2, it is clear that the formation of the silver sulfide 20 has almost no effect on the fired body 10.

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Abstract

The present invention provides an electroconductive paste which is capable of forming a relatively low-cost electrode that has high sulfurization resistance, while having a low resistance.　An electroconductive paste which contains (A) alloy particles containing Ag and Sn, (B) a glass frit and (C) a thermoplastic resin, wherein the weight ratio of Sn in the alloy particles (A) is less than 10% by weight.

Description

導電性ペースト、電極及びチップ抵抗器Conductive paste, electrodes and chip resistors
　本発明は、例えば電子部品の電極の形成に用いられる導電性ペーストに関する。また、本発明は、その導電性ペーストを用いて形成された電極、及びその電極を有するチップ抵抗器に関する。 The present invention relates to, for example, a conductive paste used for forming electrodes of electronic components. The present invention also relates to an electrode formed by using the conductive paste and a chip resistor having the electrode.
　電子部品の１つであるチップ抵抗器の電極の形成には、銀粉を含む導電性ペーストが用いられる。図１に、チップ抵抗器１００の断面構造の一例を示す。チップ抵抗器１００は、矩形のアルミナ基板１０２を有しており、アルミナ基板１０２の上面には、抵抗体１０４と、抵抗体１０４から電気を取り出すための取り出し電極１０６が形成されている。また、アルミナ基板１０２の下面には、チップ抵抗器１００を基板へ実装するための下面電極１０８が形成されている。更に、アルミナ基板１０２の端面には、取り出し電極１０６と下面電極１０８とを接続するための接続電極１１０が形成されている。取り出し電極１０６及び下面電極１０８は、アルミナ基板１０２の上面及び下面に導電性ペーストを印刷によって塗布した後に焼成することでそれぞれ形成される。取り出し電極１０６、下面電極１０８、及び接続電極１１０の上には、ニッケルめっき膜１１２及びスズめっき膜１１４が形成されることが一般的である。 A conductive paste containing silver powder is used to form the electrodes of a chip resistor, which is one of the electronic components. FIG. 1 shows an example of the cross-sectional structure of the chip resistor 100. The chip resistor 100 has a rectangular alumina substrate 102, and a resistor 104 and a take-out electrode 106 for extracting electricity from the resistor 104 are formed on the upper surface of the alumina substrate 102. Further, on the lower surface of the alumina substrate 102, a lower surface electrode 108 for mounting the chip resistor 100 on the substrate is formed. Further, a connection electrode 110 for connecting the take-out electrode 106 and the lower surface electrode 108 is formed on the end surface of the alumina substrate 102. The take-out electrode 106 and the lower surface electrode 108 are formed by applying a conductive paste to the upper surface and the lower surface of the alumina substrate 102 by printing and then firing them. A nickel plating film 112 and a tin plating film 114 are generally formed on the take-out electrode 106, the bottom electrode 108, and the connection electrode 110.
　取り出し電極１０６及び下面電極１０８は、それぞれ要求される特性が異なるため、異なる導電性ペーストを用いて形成されることが一般的である。例えば、取り出し電極１０６の形成には、抵抗体１０４とのマッチング性の良い導電性ペーストが用いられる。また、抵抗体１０４の抵抗値が低い場合、取り出し電極１０６の抵抗値も低いことが要求される。そのため、取り出し電極１０６の形成には、低抵抗の電極を形成することのできる導電性ペーストが用いられる。 Since the take-out electrode 106 and the bottom electrode 108 have different required characteristics, they are generally formed by using different conductive pastes. For example, a conductive paste having good matching with the resistor 104 is used for forming the take-out electrode 106. Further, when the resistance value of the resistor 104 is low, the resistance value of the take-out electrode 106 is also required to be low. Therefore, a conductive paste capable of forming a low resistance electrode is used for forming the take-out electrode 106.
　従来、電極の形成に用いられる導電性ペーストとして、特許文献１及び２に開示された銀粉及びガラスフリットを含有する導電性ペーストが知られている。 Conventionally, as a conductive paste used for forming an electrode, a conductive paste containing silver powder and glass frit disclosed in Patent Documents 1 and 2 is known.
特開平７－１０５７２３号公報Japanese Unexamined Patent Publication No. 7-105723 特表２０１６－５３８７０８号公報Special Table 2016-538708 Gazette
　自動車及び火力発電所などにおいて、化石燃料が燃焼されおり、大気中に硫黄酸化物が大量に排出されている。また、また、下水処理場、及びごみ処理場などにおいても、硫黄が嫌気性細菌によって還元されて硫化水素が発生している。そのため、大気中には、硫黄酸化物及び硫化水素など、硫黄を含む成分が存在している。 Fossil fuels are being burned in automobiles and thermal power plants, and a large amount of sulfur oxides are emitted into the atmosphere. Further, in sewage treatment plants and waste treatment plants, sulfur is reduced by anaerobic bacteria to generate hydrogen sulfide. Therefore, sulfur-containing components such as sulfur oxides and hydrogen sulfide are present in the atmosphere.
　大気中の硫黄を含む成分が銀の表面に達すると、銀の表面に硫黄成分が付着し、銀と反応して硫化銀になる。例えば、チップ抵抗器の電極などの銀を主材料とした電極においても、同様の反応が起こるため、電極内部の銀が硫化銀になることがある。電極内部に硫化銀が発生すると、電極に断線が生じる場合がある。そのため、銀を材料とした電極を有するチップ抵抗器などのデバイスでは、動作不良が生じることがある。このような現象を、硫化による断線という。 When the sulfur-containing component in the atmosphere reaches the surface of silver, the sulfur component adheres to the surface of silver and reacts with silver to become silver sulfide. For example, in an electrode made of silver as a main material, such as an electrode of a chip resistor, the same reaction occurs, so that the silver inside the electrode may become silver sulfide. If silver sulfide is generated inside the electrode, the electrode may be broken. Therefore, a device such as a chip resistor having an electrode made of silver may malfunction. Such a phenomenon is called disconnection due to sulfurization.
　硫化による断線を抑制するために、チップ抵抗器などのデバイスに用いられる銀を主材料とする電極には、耐硫化性の高い電極が必要である。 In order to suppress disconnection due to sulfurization, an electrode with high sulfurization resistance is required for the silver-based electrode used in devices such as chip resistors.
　硫化による断線を抑制するために、電極を形成するための導電性ペーストの導電性粒子としてパラジウム単体、あるいはパラジウムを所定量（例えば２０重量％程度）添加することが提案されている。しかしながら、パラジウムの価格は高いため、パラジウム単体あるいはパラジウムの添加により、導電性ペーストのコストが上昇する、という問題がある。 In order to suppress disconnection due to sulfide, it has been proposed to add palladium alone or palladium in a predetermined amount (for example, about 20% by weight) as the conductive particles of the conductive paste for forming the electrode. However, since the price of palladium is high, there is a problem that the cost of the conductive paste increases due to the addition of palladium alone or palladium.
　そこで、本発明は、高い耐硫化性を有し、かつ低抵抗で、比較的低コストの電極を形成することのできる導電性ペーストを提供することを目的とする。 Therefore, an object of the present invention is to provide a conductive paste having high sulfurization resistance, low resistance, and capable of forming an electrode at a relatively low cost.
　上記課題を解決するため、本発明は以下の構成を有する。 In order to solve the above problems, the present invention has the following configuration.
（構成１）
　本発明の構成１は、（Ａ）Ａｇ及びＳｎを含む合金粒子と、
　（Ｂ）ガラスフリットと、
　（Ｃ）熱可塑性樹脂と、を含有し、
　（Ａ）合金粒子におけるＳｎの重量割合が、１０重量％未満である、導電性ペーストである。 (Structure 1)
Configuration 1 of the present invention comprises (A) alloy particles containing Ag and Sn, and
(B) Glass frit and
(C) Containing with a thermoplastic resin,
(A) A conductive paste in which the weight ratio of Sn in the alloy particles is less than 10% by weight.
（構成２）
　本発明の構成２は、（Ａ）合金粒子におけるＡｇの重量割合が、５０重量％以上である、構成１の導電性ペーストである。 (Structure 2)
Configuration 2 of the present invention is the conductive paste of Configuration 1 in which the weight ratio of Ag in the alloy particles (A) is 50% by weight or more.
（構成３）
　本発明の構成３は、前記（Ｂ）ガラスフリットの含有量は、前記（Ａ）合金粒子１００重量部に対して２～２０重量部である、構成１又は２の導電性ペーストである。 (Structure 3)
Configuration 3 of the present invention is the conductive paste of configuration 1 or 2, wherein the content of the glass frit (B) is 2 to 20 parts by weight with respect to 100 parts by weight of the alloy particles (A).
（構成４）
　本発明の構成４は、（Ｄ）シリカフィラーを更に含む、構成１～３のいずれかの導電性ペーストである。 (Structure 4)
Constituent 4 of the present invention is the conductive paste according to any one of Constituents 1 to 3, further comprising (D) silica filler.
（構成５）
　本発明の構成５は、前記（Ｂ）ガラスフリットは、ＳｉＯ２とＴｉＯ２を含み、
　前記（Ｂ）ガラスフリットに含まれるＳｉＯ２の重量Ｂと、前記（Ｄ）シリカフィラーに含まれるＳｉＯ２の重量Ｄとの比率が、重量Ｂ：重量Ｄ＝１：０．２５～１：９．８である、構成４に記載の導電性ペーストである。 (Structure 5)
In the configuration 5 of the present invention, the glass frit (B) contains SiO 2 and TiO 2.
The ratio of the weight B of SiO 2 contained in the (B) glass frit to the weight D of SiO 2 contained in the (D) silica filler is weight B: weight D = 1: 0.25 to 1: 9. It is the conductive paste according to composition 4, which is 8.8.
（構成６）
　本発明の構成６は、構成１～５のいずれかの導電性ペーストを焼成して得られる電極である。 (Structure 6)
Configuration 6 of the present invention is an electrode obtained by firing any of the conductive pastes of configurations 1 to 5.
（構成７）
　本発明の構成７は、構成６に記載の電極を有するチップ抵抗器である。 (Structure 7)
Configuration 7 of the present invention is a chip resistor having the electrode according to configuration 6.
　本発明によれば、高い耐硫化性を有し、かつ低抵抗で、比較的低コストの電極を形成することのできる導電性ペーストを提供することができる。 According to the present invention, it is possible to provide a conductive paste having high sulfurization resistance, low resistance, and capable of forming an electrode at a relatively low cost.
チップ抵抗器の断面構造の一例を示す模式図である。It is a schematic diagram which shows an example of the cross-sectional structure of a chip resistor. 実施例４と同様の条件で作製した試験片（導電性ペーストの焼成体）を、硫黄を含む気体雰囲気中で保管した後の、焼成体の表面付近の断面のＳＥＭ写真（倍率１５００倍）である。A SEM photograph (magnification of 1500 times) of a cross section near the surface of the fired body after storing the test piece (fired body of the conductive paste) prepared under the same conditions as in Example 4 in a gas atmosphere containing sulfur. be. 比較例３と同様の条件で作製した試験片（導電性ペーストの焼成体）を、硫黄を含む気体雰囲気中で保管した後の、焼成体の表面付近の断面のＳＥＭ写真（倍率１５００倍）である。A SEM photograph (magnification of 1500 times) of a cross section near the surface of the fired body after storing the test piece (fired body of the conductive paste) prepared under the same conditions as in Comparative Example 3 in a gas atmosphere containing sulfur. be.
　以下、本発明の実施形態について、具体的に説明する。なお、以下の実施形態は、本発明を具体化する際の形態であって、本発明をその範囲内に限定するものではない。 Hereinafter, embodiments of the present invention will be specifically described. It should be noted that the following embodiments are embodiments for embodying the present invention, and do not limit the present invention to the scope thereof.
　本実施形態の導電性ペーストは、（Ａ）合金粒子と、（Ｂ）ガラスフリットと、（Ｃ）熱可塑性樹脂とを含む。本実施形態の導電性ペーストは、銀を材料とした電極を有するチップ抵抗器などのデバイスの電極を形成するために好ましく用いることができる。 The conductive paste of this embodiment contains (A) alloy particles, (B) glass frit, and (C) thermoplastic resin. The conductive paste of the present embodiment can be preferably used to form an electrode of a device such as a chip resistor having an electrode made of silver as a material.
　以下、本実施形態の導電性ペーストに含まれる成分について、説明する。 Hereinafter, the components contained in the conductive paste of the present embodiment will be described.
（Ａ）合金粒子
　本実施形態の導電性ペーストは、（Ａ）合金粒子を含む。（Ａ）合金粒子は、銀（Ａｇ）及びスズ（Ｓｎ）を含む。（Ａ）合金粒子がＳｎを含むことにより、Ａｇの硫化を抑制することができる。そのため、本実施形態の導電性ペーストを用いることにより、高い耐硫化性を有する電極を形成することができる。 (A) Alloy particles The conductive paste of the present embodiment contains (A) alloy particles. The alloy particles (A) contain silver (Ag) and tin (Sn). Since the alloy particles (A) contain Sn, the sulfide of Ag can be suppressed. Therefore, by using the conductive paste of the present embodiment, it is possible to form an electrode having high sulfurization resistance.
　なお、（Ａ）合金粒子は、Ａｇ及びＳｎ以外の金属を含むことができる。但し、低い電気抵抗であり、かつ高い耐硫化性を有する電極を確実に得るためには、（Ａ）合金粒子は、Ａｇ及びＳｎのみからなることが好ましい。なお、本明細書において、「（Ａ）合金粒子は、Ａｇ及びＳｎのみからなる」とは、（Ａ）金属粒子として、意図的にＡｇ及びＳｎ以外の金属を配合しないことを意味し、不可避的に混入するＡｇ及びＳｎ以外の金属が含有することまでも排除するものではない。 The alloy particles (A) can contain metals other than Ag and Sn. However, in order to surely obtain an electrode having low electric resistance and high sulfurization resistance, it is preferable that the alloy particles (A) consist only of Ag and Sn. In addition, in this specification, "(A) alloy particles consist only of Ag and Sn" means that metal other than Ag and Sn is intentionally not mixed as (A) metal particles, and it is unavoidable. It does not exclude the inclusion of metals other than Ag and Sn that are mixed with the target.
　（Ａ）合金粒子は、本実施形態の効果を損ねない範囲で、Ａｇ及びＳｎ以外の金属として、Ｚｎ、Ｉｎ、Ａｌ及びＳｉなどの金属を含むことができる。 The alloy particles (A) can contain metals such as Zn, In, Al and Si as metals other than Ag and Sn as long as the effects of the present embodiment are not impaired.
　本実施形態の導電性ペーストにおいて、（Ａ）合金粒子におけるＳｎの重量割合は、１０重量％未満であることが好ましい。より具体的には、（Ａ）合金粒子におけるＳｎの重量割合は、１重量％以上１０重量％未満であることが好ましく、１．５重量％以上９重量％以下であることがより好ましく、２重量％以上８重量％以下であることが更に好ましく、４重量％以上８重量％以下であることが特に好ましい。Ｓｎの重量割合が多すぎる場合には、電極としての電気抵抗が高くなりすぎることがある。また、Ｓｎの重量割合が少ない場合には、耐硫化性の向上が少なくなる場合がある。特に、Ｓｎの重量割合が２重量％未満の場合には、耐硫化性が悪化しやすくなる場合がある。 In the conductive paste of the present embodiment, the weight ratio of Sn in the alloy particles (A) is preferably less than 10% by weight. More specifically, the weight ratio of Sn in the alloy particles (A) is preferably 1% by weight or more and less than 10% by weight, and more preferably 1.5% by weight or more and 9% by weight or less. It is more preferably 4% by weight or more and 8% by weight or less, and particularly preferably 4% by weight or more and 8% by weight or less. If the weight ratio of Sn is too large, the electrical resistance as an electrode may become too high. Further, when the weight ratio of Sn is small, the improvement in sulfurization resistance may be small. In particular, when the weight ratio of Sn is less than 2% by weight, the sulfurization resistance may be easily deteriorated.
　本実施形態の導電性ペーストは、（Ａ）合金粒子におけるＡｇの重量割合が、５０重量％以上であることが好ましく、７０重量％以上であることがより好ましく、９０重量％超であることが更に好ましい。Ａｇの電気抵抗は、他の金属と比較して低い。そのため、Ａｇの重量割合が、所定の範囲であることにより、比較的低い電気抵抗の電極を得ることができる。 In the conductive paste of the present embodiment, the weight ratio of Ag in the alloy particles (A) is preferably 50% by weight or more, more preferably 70% by weight or more, and more than 90% by weight. More preferred. The electrical resistance of Ag is low compared to other metals. Therefore, when the weight ratio of Ag is in a predetermined range, an electrode having a relatively low electric resistance can be obtained.
　（Ａ）合金粒子の形状は、特に限定されず、例えば、球状、粒状、フレーク状及び／又は鱗片状の合金粒子を用いることが可能である。 The shape of the alloy particles (A) is not particularly limited, and for example, spherical, granular, flake-like and / or scaly alloy particles can be used.
　（Ａ）合金粒子の平均粒径は、０．１μｍ～１０μｍが好ましく、より好ましくは０．１μｍ～７μｍであり、最も好ましくは１μｍ～５μｍである。ここでいう平均粒径は、レーザー回折散乱式粒度分布測定法により得られる体積基準メジアン径（Ｄ５０）を意味する。 The average particle size of the alloy particles (A) is preferably 0.1 μm to 10 μm, more preferably 0.1 μm to 7 μm, and most preferably 1 μm to 5 μm. The average particle size referred to here means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
　（Ａ）合金粒子の製造方法は、特に限定されず、例えば、還元法、粉砕法、電解法、アトマイズ法、熱処理法、又はそれらの組合せによって製造することができる。フレーク状の合金粒子は、例えば、球状又は粒状の合金粒子をボールミル等によって押し潰すことによって製造することができる。 The method for producing the alloy particles (A) is not particularly limited, and can be produced by, for example, a reduction method, a pulverization method, an electrolytic method, an atomizing method, a heat treatment method, or a combination thereof. The flake-shaped alloy particles can be produced, for example, by crushing spherical or granular alloy particles with a ball mill or the like.
（Ｂ）ガラスフリット
　本実施形態の導電性ペーストは、（Ｂ）ガラスフリットを含む。 (B) Glass frit The conductive paste of the present embodiment includes (B) glass frit.
　（Ｂ）ガラスフリットは、ＳｉＯ２及びＴｉＯ２を含むことが好ましい。導電性ペーストが（Ｂ）ガラスフリットを含有することによって、導電性ペーストを焼成して得られる電極の基板への密着強度が向上する。ガラスフリットは、特に限定されるものではないが、好ましくは軟化点３００℃以上、より好ましくは軟化点４００～９００℃、更に好ましくは軟化点５００～８００℃のガラスフリットを用いることができる。ガラスフリットの軟化点は、熱重量測定装置（例えば、ＢＲＵＫＥＲ ＡＸＳ社製、ＴＧ－ＤＴＡ２０００ＳＡ）を用いて測定することができる。 The glass frit (B) preferably contains SiO 2 and TiO 2. When the conductive paste contains (B) glass frit, the adhesion strength of the electrode obtained by firing the conductive paste to the substrate is improved. The glass frit is not particularly limited, but a glass frit having a softening point of 300 ° C. or higher, more preferably a softening point of 400 to 900 ° C., and further preferably a softening point of 500 to 800 ° C. can be used. The softening point of the glass frit can be measured using a thermogravimetric measuring device (for example, TG-DTA2000SA manufactured by BRUKER AXS).
　（Ｂ）ガラスフリットの例として、ホウケイ酸チタン系（ＴｉＯ２系）、及びホウケイ酸バリウム系等のガラスフリットを挙げることができる。また、ガラスフリットの例として、ホウケイ酸ビスマス系、ホウケイ酸アルカリ金属系、ホウケイ酸アルカリ土類金属系、ホウケイ酸亜鉛系、ホウケイ酸鉛系、ホウ酸鉛系、ケイ酸鉛系、ホウ酸ビスマス系、及びホウ酸亜鉛系等のガラスフリットを挙げることができる。これらのガラスフリットは、２種以上を混合して用いることもできる。ガラスフリットは、環境への配慮の点から鉛フリーであることが好ましい。 (B) Examples of the glass frit include glass frit such as titanium borosilicate type (TiO 2 type) and barium borosilicate type. Examples of glass frit include bismuth borosilicate, alkali metal borosilicate, alkaline earth metal borosilicate, zinc borosilicate, lead borosilicate, lead borate, lead silicate, and bismus borate. Examples include glass frit such as system and zinc borate type. These glass frit can also be used by mixing two or more kinds. The glass frit is preferably lead-free from the viewpoint of environmental consideration.
　ガラスフリットは、ＺｎＯ、ＢａＯ、Ｎａ２Ｏ、ＣａＯ及びＡｌ２Ｏ３からなる群から選択される少なくとも１つを含むことが好ましい。ガラスフリットは、ＺｎＯ、ＢａＯ、Ｎａ２Ｏ及びＡｌ２Ｏ３を含むことがより好ましい。 The glass frit preferably contains at least one selected from the group consisting of ZnO, BaO, Na 2 O, Ca O and Al 2 O 3. The glass frit more preferably contains ZnO, BaO, Na 2 O and Al 2 O 3.
　ガラスフリットの平均粒径は、好ましくは０．１～２０μｍ、より好ましくは０．２～１０μｍ、最も好ましくは０．５～５μｍである。ここでいう平均粒径は、レーザー回折散乱式粒度分布測定法により得られる体積基準メジアン径（Ｄ５０）のことを意味する。 The average particle size of the glass frit is preferably 0.1 to 20 μm, more preferably 0.2 to 10 μm, and most preferably 0.5 to 5 μm. The average particle size referred to here means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
　本実施形態の導電性ペーストにおいて、（Ｂ）ガラスフリットの含有量は、（Ａ）合金粒子１００重量部に対して１～２０重量部であることが好ましく、１．５～１５重量部であることがより好ましく、２～１０重量部であることが更に好ましい。ガラスフリットの含有量がこの範囲よりも少ない場合、導電性ペーストを焼成して得られる電極の基板への密着性が低下する。ガラスフリットの含有量がこの範囲よりも多い場合、導電性ペーストを焼成して得られる電極の抵抗値は高くなる。なお、ガラスフリットの含有量が比較的少ない場合には、低抵抗の電極を得ることができる。また、ガラスフリットの含有量が比較的多い場合には、耐薬品性に優れる電極を得ることができる。耐薬品性は、電極の表面にめっき膜を形成する場合に、めっき前処理が必要であるために求められる特性である。めっき前処理は、電極の表面から汚染物質を除去し、電極の表面を活性化し、めっきに適した清浄な状態にすることを目的として行われる。除去するべき汚染物質には有機系と無機系に大別できる。前処理工程は、単独の工程で全ての汚染物質を除去する工程ではない。例えば有機系物質は、アルカリ系洗浄剤を用いた工程で除去する。無機系物質は、酸系洗浄剤を用いた工程で除去する。その為、電極に高い耐薬品性が求められる。 In the conductive paste of the present embodiment, the content of (B) glass frit is preferably 1 to 20 parts by weight, preferably 1.5 to 15 parts by weight, based on 100 parts by weight of the alloy particles (A). More preferably, it is more preferably 2 to 10 parts by weight. When the content of the glass frit is less than this range, the adhesion of the electrode obtained by firing the conductive paste to the substrate is lowered. When the content of the glass frit is higher than this range, the resistance value of the electrode obtained by firing the conductive paste becomes high. When the content of the glass frit is relatively small, an electrode having low resistance can be obtained. Further, when the content of the glass frit is relatively large, an electrode having excellent chemical resistance can be obtained. Chemical resistance is a characteristic required because a plating pretreatment is required when a plating film is formed on the surface of the electrode. The pre-plating treatment is performed for the purpose of removing contaminants from the surface of the electrode, activating the surface of the electrode, and making the surface of the electrode a clean state suitable for plating. Pollutants to be removed can be broadly divided into organic and inorganic. The pretreatment step is not a single step of removing all contaminants. For example, organic substances are removed in a process using an alkaline cleaning agent. Inorganic substances are removed in a process using an acid-based cleaning agent. Therefore, the electrodes are required to have high chemical resistance.
　導電性ペーストは、温度の上昇とともにガラスフリットが軟化し、銀の焼結が進む。ガラスフリット含有量が多い場合には、ガラス成分が焼結体の表面に押し出されてくることがある。その場合、焼結体の表面はガラス成分で覆われることがある。焼結体の表面にニッケルめっき膜を形成することで、スズめっき膜から電極へのスズの拡散を抑制できるだけでなく、焼結体の表面がガラス成分で覆われた場合にも焼結体の導電性を向上させることが可能となる。本実施形態の（Ａ）合金粒子は、Ａｇ及びＳｎを含む合金粒子なので、Ａｇ粒子と比べて、焼結性が低い。そのため、焼結体の表面がガラス成分で覆われるという現象の発生を抑制することができる。そのため、ガラスフリットの含有量を増加させることができるので、Ａｇ粒子と比べて、耐薬品性に優れる電極を得ることができる。なお、ガラスフリットと同様の性質及び機能を有する（Ｄ）シリカフィラーについても、その含有量を増加させることができるので、耐薬品性に優れる電極を得ることができる。 In the conductive paste, the glass frit softens as the temperature rises, and silver sintering progresses. If the glass frit content is high, the glass component may be extruded onto the surface of the sintered body. In that case, the surface of the sintered body may be covered with a glass component. By forming a nickel plating film on the surface of the sintered body, not only can the diffusion of tin from the tin plating film to the electrodes be suppressed, but also when the surface of the sintered body is covered with a glass component, the sintered body It is possible to improve the conductivity. Since the alloy particles (A) of the present embodiment are alloy particles containing Ag and Sn, their sinterability is lower than that of Ag particles. Therefore, it is possible to suppress the occurrence of the phenomenon that the surface of the sintered body is covered with the glass component. Therefore, since the content of the glass frit can be increased, it is possible to obtain an electrode having excellent chemical resistance as compared with Ag particles. Since the content of the (D) silica filler having the same properties and functions as the glass frit can be increased, an electrode having excellent chemical resistance can be obtained.
（Ｃ）熱可塑性樹脂
　本実施形態の導電性ペーストは、（Ｃ）熱可塑性樹脂を含む。 (C) Thermoplastic Resin The conductive paste of the present embodiment contains (C) a thermoplastic resin.
　熱可塑性樹脂は、導電性ペースト中において銀粉同士をつなぎあわせるものである。熱可塑性樹脂としては、導電性ペーストの焼成時に焼失するものを用いることができる。 Thermoplastic resin connects silver powders together in a conductive paste. As the thermoplastic resin, one that is burnt down during firing of the conductive paste can be used.
　熱可塑性樹脂としては、例えば、エチルセルロース、ニトロセルロース等のセルロース系樹脂、アクリル樹脂、アルキド樹脂、飽和ポリエステル樹脂、ブチラール樹脂、ポリビニルアルコール、及びヒドロキシプロピルセルロース等を用いることができる。これらの樹脂は、単独で使用することができ、２種類以上を混合して使用することができる。 As the thermoplastic resin, for example, cellulose-based resins such as ethyl cellulose and nitrocellulose, acrylic resins, alkyd resins, saturated polyester resins, butyral resins, polyvinyl alcohol, hydroxypropyl cellulose and the like can be used. These resins can be used alone or in admixture of two or more.
　（Ｃ）熱可塑性樹脂の含有量は、（Ａ）合金粒子１００重量部に対して、好ましくは０．５～４０重量部であり、より好ましくは、１～３５重量部である。導電性ペースト中の熱可塑性樹脂の含有量が上記の範囲内の場合、導電性ペーストの基板への塗布性、ペーストレベリング性が向上し、印刷形状に優れる。一方、熱可塑性樹脂の含有量が上記の範囲を超えると、導電性ペースト中に含まれる熱可塑性樹脂の量が多すぎる。そのため、電極を高精度に形成することができなくなるおそれがある。 The content of the (C) thermoplastic resin is preferably 0.5 to 40 parts by weight, more preferably 1 to 35 parts by weight, based on 100 parts by weight of the alloy particles (A). When the content of the thermoplastic resin in the conductive paste is within the above range, the coating property of the conductive paste on the substrate and the paste leveling property are improved, and the printed shape is excellent. On the other hand, when the content of the thermoplastic resin exceeds the above range, the amount of the thermoplastic resin contained in the conductive paste is too large. Therefore, the electrodes may not be formed with high accuracy.
（Ｄ）シリカフィラー
　本実施形態の導電性ペーストは、（Ｄ）シリカフィラーを更に含むことが好ましい。 (D) Silica Filler The conductive paste of the present embodiment preferably further contains (D) silica filler.
　（Ｄ）シリカフィラーは、例えば、半導体封止材料として市販されている球状シリカ（ＳｉＯ２）粒子を用いることができる。シリカフィラーの形状は、球状以外の形状であってもよい。シリカフィラーの製造方法は特に制限されるものではなく、溶射法などの公知の方法によって製造されたシリカフィラーを用いることができる。シリカフィラーの平均粒径は、２０ｎｍ以上５μｍ以下であることが好ましく、１μｍ以上３μｍ以下であることがさらに好ましい。ここでいう平均粒径は、レーザー回折散乱式粒度分布測定法により得られる体積基準メジアン径（Ｄ５０）を意味する。 As the silica filler (D), for example, spherical silica (SiO 2 ) particles commercially available as a semiconductor encapsulating material can be used. The shape of the silica filler may be a shape other than a spherical shape. The method for producing the silica filler is not particularly limited, and a silica filler produced by a known method such as a thermal spraying method can be used. The average particle size of the silica filler is preferably 20 nm or more and 5 μm or less, and more preferably 1 μm or more and 3 μm or less. The average particle size referred to here means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
　本実施形態の導電性ペーストにおいて、（Ｂ）ガラスフリットは、ＳｉＯ２とＴｉＯ２を含み、（Ｂ）ガラスフリットに含まれるＳｉＯ２の重量Ｂと、（Ｄ）シリカフィラーに含まれるＳｉＯ２の重量Ｄとの比率が、重量Ｂ：重量Ｄ＝１：０．２５～１：９．８であることが好ましく、重量Ｂ：重量Ｄ＝１：０．２５～１：３．５であることが好ましい。 In the conductive paste of the present embodiment, (B) the glass frit contains SiO 2 and TiO 2 , and (B) the weight B of SiO 2 contained in the glass frit and (D) SiO 2 contained in the silica filler. The ratio to the weight D is preferably weight B: weight D = 1: 0.25 to 1: 9.8, and weight B: weight D = 1: 0.25 to 1: 3.5. Is preferable.
　本実施形態の導電性ペーストは、（Ｄ）シリカフィラーを含有することにより、得られる電極の耐薬品性が向上する。一方、シリカフィラーが多すぎる場合には、得られる電極の抵抗値が高くなり、低抵抗の電極を得ることが困難になる。また、（Ｄ）シリカフィラーは、（Ｂ）ガラスフリットと同様の機能を有する。そのため、（Ｂ）ガラスフリットに含まれるＳｉＯ２の重量Ｂと、（Ｄ）シリカフィラーに含まれるＳｉＯ２の重量Ｄとの比率が、上述のような比率の範囲であることにより、適切な耐薬品性を得ることができ、かつ低抵抗の電極を得ることができる。 By containing (D) silica filler in the conductive paste of the present embodiment, the chemical resistance of the obtained electrode is improved. On the other hand, if the amount of silica filler is too large, the resistance value of the obtained electrode becomes high, and it becomes difficult to obtain a low resistance electrode. Further, the (D) silica filler has the same function as the (B) glass frit. Therefore, the ratio of the weight B of SiO 2 contained in (B) the glass frit and the weight D of SiO 2 contained in (D) the silica filler is within the range of the ratio as described above, so that the resistance is appropriate. Chemical properties can be obtained, and an electrode having low resistance can be obtained.
（Ｅ）溶剤
　本実施形態の導電性ペーストは、（Ｅ）溶剤を含んでもよい。溶剤としては、例えば、メタノール、エタノール、イソプロピルアルコール（ＩＰＡ）等のアルコール類、酢酸エチレン等の有機酸類、トルエン、キシレン等の芳香族炭化水素類、Ｎ－メチル－２－ピロリドン（ＮＭＰ）等のＮ－アルキルピロリドン類、Ｎ，Ｎ－ジメチルホルムアミド（ＤＭＦ）等のアミド類、メチルエチルケトン（ＭＥＫ）等のケトン類、テルピネオール（ＴＥＬ）、ブチルカルビトール（ＢＣ）等の環状カーボネート類、及び水等が挙げられる。溶剤の含有量は、特に限定されない。溶剤の含有量は、（Ａ）合金粒子１００重量部に対して、好ましくは１～１００重量部、より好ましくは５～６０重量部である。 (E) Solvent The conductive paste of the present embodiment may contain (E) a solvent. Examples of the solvent include alcohols such as methanol, ethanol and isopropyl alcohol (IPA), organic acids such as ethylene acetate, aromatic hydrocarbons such as toluene and xylene, and N-methyl-2-pyrrolidone (NMP). N-alkylpyrrolidones, amides such as N, N-dimethylformamide (DMF), ketones such as methylethylketone (MEK), cyclic carbonates such as terpineol (TEL) and butyl carbitol (BC), water and the like. Can be mentioned. The content of the solvent is not particularly limited. The content of the solvent is preferably 1 to 100 parts by weight, more preferably 5 to 60 parts by weight, based on 100 parts by weight of the alloy particles (A).
　本実施形態の導電性ペーストの粘度は、好ましくは５０～７００Ｐａ・ｓ（せん断速度：４．０ｓｅｃ－１）、より好ましくは１００～３００Ｐａ・ｓ（せん断速度：４．０ｓｅｃ－１）である。導電性ペーストの粘度がこの範囲に調整されることによって、導電性ペーストの基板への塗布性や取り扱い性が良好になり、導電性ペーストを均一の厚みで基板へ塗布することが可能になる。なお、導電性ペーストの粘度は、ＨＢ型粘度計　ＳＣ４－１４スピンドルを使用（ブルックフィールド社製）により測定することができる。 The viscosity of the conductive paste of the present embodiment is preferably 50 to 700 Pa · s (shear velocity: 4.0 sec -1 ), more preferably 100 to 300 Pa · s (shear velocity: 4.0 sec -1 ). By adjusting the viscosity of the conductive paste within this range, the coatability and handleability of the conductive paste on the substrate are improved, and the conductive paste can be coated on the substrate with a uniform thickness. The viscosity of the conductive paste can be measured by using an HB type viscometer SC4-14 spindle (manufactured by Brookfield).
　本実施形態の導電性ペーストは、その他の添加剤、例えば、分散剤、レオロジー調整剤、顔料などを含有してもよい。 The conductive paste of the present embodiment may contain other additives such as a dispersant, a rheology adjuster, and a pigment.
　本実施形態の導電性ペーストは、上記の各成分を、例えば、ライカイ機、ポットミル、三本ロールミル、回転式混合機、及び／又は二軸ミキサー等を用いて混合することで製造することができる。 The conductive paste of the present embodiment can be produced by mixing each of the above components using, for example, a Raikai machine, a pot mill, a three-roll mill, a rotary mixer, and / or a twin-screw mixer. ..
　本実施形態は、上述の本実施形態の導電性ペーストを焼成して得られる電極である。 This embodiment is an electrode obtained by firing the conductive paste of the above-mentioned embodiment.
　本実施形態は、上述の本実施形態の導電性ペーストを材料として形成された電極である。本実施形態の電極は、導電性ペーストを基板に塗布し、焼成することにより得ることができる。したがって、本実施形態の電極は、（Ａ’）Ａｇ及びＳｎを含む合金粒子と、ガラスフリットを材料とする（Ｂ’）ガラス成分と、を含有することができる。（Ａ’）合金粒子は、焼結された状態になる。本実施形態の電極の（Ａ’）合金粒子におけるＳｎの重量割合が、１０重量％未満である。なお、導電性ペーストに含まれる（Ｃ）熱可塑性樹脂及び（Ｅ）溶剤は、焼成の際に気化又は燃焼するので、電極は実質的に（Ｃ）熱可塑性樹脂及び（Ｅ）溶剤を含まない。 This embodiment is an electrode formed from the above-mentioned conductive paste of this embodiment as a material. The electrode of the present embodiment can be obtained by applying a conductive paste to a substrate and firing it. Therefore, the electrode of the present embodiment can contain alloy particles containing (A') Ag and Sn, and a (B') glass component made of glass frit as a material. The (A') alloy particles are in a sintered state. The weight ratio of Sn in the (A') alloy particles of the electrode of the present embodiment is less than 10% by weight. Since the (C) thermoplastic resin and (E) solvent contained in the conductive paste are vaporized or burned during firing, the electrodes are substantially free of (C) thermoplastic resin and (E) solvent. ..
　本実施形態の電極は、（Ａ’）合金粒子及び（Ｂ’）ガラス成分の他に、（Ｄ’）シリカフィラーを更に含むことができる。また、本実施形態の電極は、（Ａ’）合金粒子におけるＡｇの重量割合、（Ｂ’）ガラス成分の含有量及び（Ｂ’）ガラス成分の組成は、材料となる導電性ペーストに含まれる（Ａ）合金粒子及び（Ｂ）ガラスフリットの重量割合及び組成に対応することになる。 The electrode of this embodiment can further contain (D') silica filler in addition to (A') alloy particles and (B') glass component. Further, in the electrode of the present embodiment, the weight ratio of Ag in the (A') alloy particles, the content of the (B') glass component and the composition of the (B') glass component are contained in the conductive paste as the material. It corresponds to the weight ratio and composition of (A) alloy particles and (B) glass frit.
　本実施形態の電極となる薄膜のシート抵抗は、膜厚により異なるが、概ね１０ｍΩ／□（１０ｍΩ/square）程度又は１０ｍΩ／□以下とすることができる。このため、低抵抗であることが要求される電極の形成に好ましく用いることができる。 The sheet resistance of the thin film used as the electrode of the present embodiment varies depending on the film thickness, but can be approximately 10 mΩ / □ (10 mΩ / square) or 10 mΩ / □ or less. Therefore, it can be preferably used for forming an electrode that is required to have a low resistance.
　次に、本実施形態の導電性ペーストを用いて基板上に電極を形成する方法について説明する。まず、導電性ペーストを基板上に塗布する。塗布方法は任意であり、例えば、ディスペンス、ジェットディスペンス、孔版印刷、スクリーン印刷、ピン転写、又はスタンピングなどの公知の方法を用いて塗布することができる。 Next, a method of forming an electrode on a substrate using the conductive paste of the present embodiment will be described. First, the conductive paste is applied onto the substrate. The coating method is arbitrary, and for example, it can be coated using a known method such as dispense, jet dispense, stencil printing, screen printing, pin transfer, or stamping.
　基板上に導電性ペーストを塗布した後、基板を焼成炉等に投入する。そして、基板上に塗布された導電性ペーストを、５００～９００℃、より好ましくは６００～９００℃、更に好ましくは７００～９００℃で焼成する。これにより、導電性ペーストに含まれる溶剤成分は３００℃以下で蒸発し、樹脂成分は４００℃～６００℃で焼失し、導電性ペーストの焼成体を形成する。このようにして得られた電極は、耐薬品性が高く、基板への密着性が優れている。 After applying the conductive paste on the substrate, put the substrate into a firing furnace or the like. Then, the conductive paste applied on the substrate is fired at 500 to 900 ° C., more preferably 600 to 900 ° C., and even more preferably 700 to 900 ° C. As a result, the solvent component contained in the conductive paste evaporates at 300 ° C. or lower, and the resin component is burnt at 400 ° C. to 600 ° C. to form a fired body of the conductive paste. The electrode thus obtained has high chemical resistance and excellent adhesion to the substrate.
　本実施形態は、上述の電極を有するチップ抵抗器である。 This embodiment is a chip resistor having the above-mentioned electrodes.
　本実施形態の導電性ペーストは、電子部品などのデバイスの回路の形成、電極の形成、及び電子部品などのデバイスの基板への接合等に用いることが可能である。また、本実施形態の導電性ペーストは、チップ抵抗器の電極の形成に好ましく用いることができる。 The conductive paste of this embodiment can be used for forming circuits of devices such as electronic components, forming electrodes, and joining devices such as electronic components to a substrate. Further, the conductive paste of the present embodiment can be preferably used for forming an electrode of a chip resistor.
　図１に、本実施形態のチップ抵抗器１００の断面構造の一例を示す。チップ抵抗器１００は、矩形のアルミナ基板１０２と、アルミナ基板１０２の表面に配置された抵抗体１０４及び取り出し電極１０６とを有することができる。取り出し電極１０６は、抵抗体１０４から電気を取り出すための電極である。また、アルミナ基板１０２の下面には、チップ抵抗器１００を基板へ実装するための下面電極１０８を配置することができる。更に、取り出し電極１０６と下面電極１０８とを接続するための接続電極１１０を、アルミナ基板１０２の端面に配置することができる。本実施形態の導電性ペーストを用いて、取り出し電極１０６、下面電極１０８、及び接続電極１１０の少なくとも１つを形成することができる。特に、取り出し電極１０６は、本実施形態の導電性ペーストを用いて形成されることが好ましい。なお、取り出し電極１０６、下面電極１０８、及び接続電極１１０の上面（アルミナ基板１０２とは反対側の表面）に、ニッケルめっき膜１１２及びスズめっき膜１１４を配置することができる。 FIG. 1 shows an example of the cross-sectional structure of the chip resistor 100 of the present embodiment. The chip resistor 100 can have a rectangular alumina substrate 102, a resistor 104 arranged on the surface of the alumina substrate 102, and a take-out electrode 106. The extraction electrode 106 is an electrode for extracting electricity from the resistor 104. Further, on the lower surface of the alumina substrate 102, a lower surface electrode 108 for mounting the chip resistor 100 on the substrate can be arranged. Further, a connection electrode 110 for connecting the take-out electrode 106 and the bottom electrode 108 can be arranged on the end surface of the alumina substrate 102. The conductive paste of the present embodiment can be used to form at least one of a take-out electrode 106, a bottom electrode 108, and a connection electrode 110. In particular, the take-out electrode 106 is preferably formed using the conductive paste of the present embodiment. The nickel plating film 112 and the tin plating film 114 can be arranged on the upper surfaces of the take-out electrode 106, the lower surface electrode 108, and the connection electrode 110 (the surface opposite to the alumina substrate 102).
　本実施形態の導電性ペーストを用いることにより、高い耐硫化性を有し、かつ低抵抗で、比較的低コストの電極を形成することのできるため、信頼性の高い電極が形成されたチップ抵抗器等の電子装置を得ることができる。 By using the conductive paste of the present embodiment, it is possible to form an electrode having high sulfurization resistance, low resistance, and relatively low cost, so that a chip resistor in which a highly reliable electrode is formed is formed. An electronic device such as a vessel can be obtained.
　以下、実施例により、本発明を具体的に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.
［導電性ペーストの調製］
　以下の（Ａ）～（Ｅ）成分を、表１及び表２に示す割合で混合して導電性ペーストを調製した。なお、表１及び表２に示す各成分の割合は、全て重量部で示している。また、平均粒径は、レーザー回折散乱式粒度分布測定法により得られる体積基準メジアン径（Ｄ５０）のことを意味する。 [Preparation of conductive paste]
The following components (A) to (E) were mixed at the ratios shown in Tables 1 and 2 to prepare a conductive paste. The proportions of each component shown in Tables 1 and 2 are all shown in parts by weight. Further, the average particle size means a volume-based median diameter (D50) obtained by a laser diffraction / scattering type particle size distribution measurement method.
（Ａ）金属粒子
　（Ａ）金属粒子として、以下の金属粒子Ａ１～Ａ７を用いた。下記のＡｇ／Ｓｎの数値は、重量割合である。
　金属粒子Ａ１（合金粒子）：　重量割合Ａｇ／Ｓｎ＝９８／２、平均粒径（Ｄ５０）２．５μｍ。
　金属粒子Ａ２（合金粒子）：　重量割合Ａｇ／Ｓｎ＝９５／５、平均粒径（Ｄ５０）２．５μｍ
　金属粒子Ａ３（合金粒子）：　重量割合Ａｇ／Ｓｎ＝９３／７、平均粒径（Ｄ５０）２．５μｍ
　金属粒子Ａ４：　Ａｇ粒子、平均粒径（Ｄ５０）２．５μｍ
　金属粒子Ａ５：　Ａｇ粒子（平均粒径（Ｄ５０）２．５μｍ）及びＳｎ粒子（平均粒径（Ｄ５０）２．５μｍ）の混合、重量割合Ａｇ粒子／Ｓｎ粒子＝９３／７
　金属粒子Ａ６（合金粒子）：　重量割合Ａｇ／Ｓｎ＝９０／１０、平均粒径（Ｄ５０）２．５μｍ
　金属粒子Ａ７（合金粒子）：　重量割合Ａｇ／Ｓｎ＝７０／３０、平均粒径（Ｄ５０）２．５μｍ (A) Metal Particles (A) The following metal particles A1 to A7 were used as the metal particles. The following Ag / Sn values are weight ratios.
Metal particles A1 (alloy particles): Weight ratio Ag / Sn = 98/2, average particle size (D50) 2.5 μm.
Metal particles A2 (alloy particles): Weight ratio Ag / Sn = 95/5, average particle size (D50) 2.5 μm
Metal particles A3 (alloy particles): Weight ratio Ag / Sn = 93/7, average particle size (D50) 2.5 μm
Metal particles A4: Ag particles, average particle size (D50) 2.5 μm
Metal particles A5: Mixing of Ag particles (average particle size (D50) 2.5 μm) and Sn particles (average particle size (D50) 2.5 μm), weight ratio Ag particles / Sn particles = 93/7
Metal particles A6 (alloy particles): Weight ratio Ag / Sn = 90/10, average particle size (D50) 2.5 μm
Metal particles A7 (alloy particles): Weight ratio Ag / Sn = 70/30, average particle size (D50) 2.5 μm
（Ｂ）ガラスフリット
　（Ｂ）ガラスフリットとして、以下のガラスフリットＢ１及びＢ２を用いた。
　ガラスフリットＢ１：ホウケイ酸チタン系ガラスフリット（成分組成：ＳｉＯ２－Ｂ２Ｏ３－Ｎａ２Ｏ－ＴｉＯ２系）、軟化点（Ｔｓ）＝５７０℃、平均粒径（Ｄ５０）１．４μｍ
　ガラスフリットＢ２：ホウケイ酸バリウム系ガラスフリット（成分組成：ＳｉＯ２－Ｂ２Ｏ３－ＢａＯ系）、軟化点（Ｔｓ）＝７５０℃、平均粒径（Ｄ５０）１．２μｍ (B) Glass frit As the (B) glass frit, the following glass frit B1 and B2 were used.
Glass frit B1: Titanium borosilicate glass frit (component composition: SiO 2- B 2 O 3- Na 2 O- TIO 2 system), softening point (Ts) = 570 ° C., average particle size (D50) 1.4 μm
Glass frit B2: Barium borosilicate glass frit (component composition: SiO 2- B 2 O 3- BaO system), softening point (Ts) = 750 ° C., average particle size (D50) 1.2 μm
（Ｃ）熱可塑性樹脂
　熱可塑性樹脂Ｃ１：エチルセルロース樹脂（STD-200、ダウ・ケミカル社製）
　熱可塑性樹脂Ｃ２：エチルセルロース樹脂（STD-4、ダウ・ケミカル社製） (C) Thermoplastic resin Thermoplastic resin C1: Ethyl cellulose resin (STD-200, manufactured by Dow Chemical Co., Ltd.)
Thermoplastic resin C2: Ethyl cellulose resin (STD-4, manufactured by Dow Chemical Co., Ltd.)
（Ｄ）シリカフィラー
　（Ｄ）シリカフィラーとして、下記のシリカフィラーを用いた。
　球状シリカ（ＳｉＯ２）粉末、平均粒径（Ｄ５０）２μｍ (D) Silica filler The following silica filler was used as the (D) silica filler.
Spherical silica (SiO 2 ) powder, average particle size (D50) 2 μm
（Ｅ）溶剤
　溶剤として、テキサノール（イーストマンケミカル株式会社製）を用いた。 (E) Solvent Texanol (manufactured by Eastman Chemical Company, Inc.) was used as the solvent.
［試験片の作製］
　調製した導電性ペーストを用いて、以下の手順により、試験片を作製した。まず、２０ｍｍ×２０ｍｍ×１ｍｍ（ｔ）のアルミナ基板上に、スクリーン印刷によって導電性ペーストを塗布した。これにより、一辺が１．５ｍｍの角パッド形状からなるパターンを、アルミナ基板上に２０個形成した。パターンの形成には、ステンレス製の２５０メッシュのマスクを用いた。つぎに、熱風式乾燥機を用いて、１５０℃で１０分間、導電性ペーストを乾燥させた。導電性ペーストを乾燥させた後、焼成炉を用いて、導電性ペーストを焼成した。焼成温度は８５０℃で１０分間キープ、トータル焼成時間６０分である。 [Preparation of test piece]
Using the prepared conductive paste, a test piece was prepared by the following procedure. First, a conductive paste was applied by screen printing on an alumina substrate of 20 mm × 20 mm × 1 mm (t). As a result, 20 patterns having a square pad shape with a side of 1.5 mm were formed on the alumina substrate. A stainless steel 250 mesh mask was used to form the pattern. Next, the conductive paste was dried at 150 ° C. for 10 minutes using a hot air dryer. After the conductive paste was dried, the conductive paste was fired using a firing furnace. The firing temperature is 850 ° C. for 10 minutes, and the total firing time is 60 minutes.
［シート抵抗の測定］
　まず、試験片であるアルミナ基板上に形成された角パッドパターンのシート抵抗Ｒ０を測定した。シート抵抗Ｒ０は、テスターを用いて４端子法にて測定した。次に、高硫黄環境での耐硫化試験を、ASTM B809-95（６０℃、１０００時間）に準じて行った。すなわち、デシケーターの底に０．５ｗｔ％の硝酸カリウム水溶液２００ｇを入れ、目皿の上に、硫黄粉５０ｇ及び試験片を載置し、デシケーターの蓋をして、６０℃で１０００時間、保管することにより、電極の硫化の加速試験を行った。この保管後、シート抵抗Ｒ１を測定した。硫化による電極の劣化を評価するために、保管の前後のシート抵抗の変化率を下記の式により算出した。表１及び２に、実施例及び比較例のシート抵抗の変化率を示す。
　シート抵抗の変化率　＝　（Ｒ1－Ｒ０）／Ｒ０ [Measurement of sheet resistance]
First, the sheet resistance R 0 of the square pad pattern formed on the alumina substrate, which is a test piece, was measured. The sheet resistance R 0 was measured by the 4-terminal method using a tester. Next, a sulfurization resistance test in a high sulfur environment was performed according to ASTM B809-95 (60 ° C., 1000 hours). That is, 200 g of a 0.5 wt% potassium nitrate aqueous solution is placed in the bottom of the desiccator, 50 g of sulfur powder and a test piece are placed on a perforated plate, the desiccator is covered, and the mixture is stored at 60 ° C. for 1000 hours. The accelerated test of sulfide of the electrode was performed. After this storage, it was measured sheet resistance R 1. In order to evaluate the deterioration of the electrode due to sulfurization, the rate of change in sheet resistance before and after storage was calculated by the following formula. Tables 1 and 2 show the rate of change in sheet resistance of Examples and Comparative Examples.
Rate of change in sheet resistance = (R 1- R 0 ) / R 0
［ＳＥＭによる撮影］
　図２に、シート抵抗の変化率が比較的小さかった実施例４と同様の条件で作製した試験片の断面を、１５００倍の倍率で走査型電子顕微鏡（ＳＥＭ）によって撮影したＳＥＭ写真を示す。図３に、シート抵抗の変化率が大きかった（絶縁体だった）比較例３と同様の条件で作製した試験片の断面を、１５００倍の倍率でＳＥＭによって撮影したＳＥＭ写真を示す。なお、試験片は、硫黄雰囲気（６０℃）で１０００時間、保管した後に、ＳＥＭ観察を行った。 [SEM shooting]
FIG. 2 shows an SEM photograph of a cross section of a test piece prepared under the same conditions as in Example 4 in which the rate of change in sheet resistance was relatively small, taken with a scanning electron microscope (SEM) at a magnification of 1500 times. FIG. 3 shows an SEM photograph of a cross section of a test piece prepared under the same conditions as in Comparative Example 3 (which was an insulator) having a large rate of change in sheet resistance, taken by SEM at a magnification of 1500 times. The test piece was stored in a sulfur atmosphere (60 ° C.) for 1000 hours, and then SEM observed.
　表１及び表２に示す結果から分かる通り、実施例１～１０の導電性ペーストを焼成して得られた電極パターンは、シート抵抗の変化率が１１％以下であり、比較的低かった。これに対し、比較例１～４の導電性ペーストを焼成して得られた電極パターンは、シート抵抗の変化率が９５％以上であるか、又は硫化の加速試験の保管後のシート抵抗が高すぎて測定不能だった。 As can be seen from the results shown in Tables 1 and 2, the electrode patterns obtained by firing the conductive pastes of Examples 1 to 10 had a rate of change in sheet resistance of 11% or less, which was relatively low. On the other hand, in the electrode patterns obtained by firing the conductive pastes of Comparative Examples 1 to 4, the rate of change in sheet resistance is 95% or more, or the sheet resistance after storage in the sulfide acceleration test is high. It was too much to measure.
　図２に示す実施例のＳＥＭ写真では、硫化により硫化銀２０が形成された部分は、導電性ペーストの焼成体１０（銀粒子）の表面の膜厚ｄ＝５０ｎｍ程度の部分であった。図２に示す実施例では、電極表面に硫化銀の膜は析出しているが、硫黄は、電極内部までは侵入していない。そのため、電極内部には、クラックなどの発生は観察されなかった。すなわち、図２に示す実施例では、硫化銀２０の形成により、焼成体１０に対する影響はほとんどないことが明らかである。 In the SEM photograph of the example shown in FIG. 2, the portion where the silver sulfide 20 was formed by sulfurization was a portion having a film thickness d = 50 nm on the surface of the fired body 10 (silver particles) of the conductive paste. In the embodiment shown in FIG. 2, a silver sulfide film is deposited on the surface of the electrode, but sulfur does not penetrate into the inside of the electrode. Therefore, no cracks or the like were observed inside the electrode. That is, in the example shown in FIG. 2, it is clear that the formation of the silver sulfide 20 has almost no effect on the fired body 10.
　一方、図３に示す比較例のＳＥＭ写真では、硫化により硫化銀２０が形成された部分は、導電性ペーストの焼成体１０（銀粒子）には膜厚ｄ＝２５０ｎｍ程度まで硫化銀２０が形成された。すなわち、図２に示す実施例と比較して、図３に示す比較例の場合には硫化銀の薄膜が厚く、電極の内部まで硫化されたことが理解できる。そのため、図３のＳＥＭ写真において明らかなように、図３の試験片の場合には、焼成体１０（電極）の内部にクラック３０が発生した。すなわち、比較例においてシート抵抗が大きく上昇した理由は、硫化による影響のために発生したクラックによるものと考えられる。 On the other hand, in the SEM photograph of the comparative example shown in FIG. 3, in the portion where the silver sulfide 20 was formed by sulfurization, the silver sulfide 20 was formed on the fired body 10 (silver particles) of the conductive paste up to a film thickness d = 250 nm. Was done. That is, it can be understood that in the case of the comparative example shown in FIG. 3, the thin film of silver sulfide was thicker than that of the example shown in FIG. 2, and the inside of the electrode was sulfided. Therefore, as is clear from the SEM photograph of FIG. 3, in the case of the test piece of FIG. 3, cracks 30 were generated inside the fired body 10 (electrode). That is, it is considered that the reason why the sheet resistance increased significantly in the comparative example is due to the cracks generated due to the influence of sulfurization.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　１０　導電性ペーストの焼成体
　２０　硫化銀
　３０　クラック
　１００　チップ抵抗器
　１０２　アルミナ基板
　１０４　抵抗体
　１０６　取り出し電極
　１０８　下面電極
　１１０　接続電極
　１１２　ニッケルめっき膜
　１１４　スズめっき膜
　ｄ　硫化銀の膜厚 10 Fired body of conductive paste 20 Silver sulfide 30 Crack 100 Chip resistor 102 Alumina substrate 104 Resistor 106 Extraction electrode 108 Bottom electrode 110 Connection electrode 112 Nickel plating film 114 Tin plating film d Thickness of silver sulfide

Claims (7)

  1. 　（Ａ）Ａｇ及びＳｎを含む合金粒子と、
    　（Ｂ）ガラスフリットと、
    　（Ｃ）熱可塑性樹脂と、を含有し、
    　（Ａ）合金粒子におけるＳｎの重量割合が、１０重量％未満である、導電性ペースト。     (A) Alloy particles containing Ag and Sn, and
    (B) Glass frit and
    (C) Containing with a thermoplastic resin,
    (A) A conductive paste in which the weight ratio of Sn in the alloy particles is less than 10% by weight.
  2. 　（Ａ）合金粒子におけるＡｇの重量割合が、５０重量％以上である、請求項１に記載の導電性ペースト。 (A) The conductive paste according to claim 1, wherein the weight ratio of Ag in the alloy particles is 50% by weight or more.
  3. 　前記（Ｂ）ガラスフリットの含有量は、前記（Ａ）合金粒子１００重量部に対して１～２０重量部である、請求項１又は２に記載の導電性ペースト。 The conductive paste according to claim 1 or 2, wherein the content of the (B) glass frit is 1 to 20 parts by weight with respect to 100 parts by weight of the (A) alloy particles.
  4. 　（Ｄ）シリカフィラーを更に含む、請求項１～３のいずれか１項に記載の導電性ペースト。 (D) The conductive paste according to any one of claims 1 to 3, further comprising a silica filler.
  5. 　前記（Ｂ）ガラスフリットは、ＳｉＯ２とＴｉＯ２を含み、
    　前記（Ｂ）ガラスフリットに含まれるＳｉＯ２の重量Ｂと、前記（Ｄ）シリカフィラーに含まれるＳｉＯ２の重量Ｄとの比率が、重量Ｂ：重量Ｄ＝１：０．２５～１：９．８である、請求項４に記載の導電性ペースト。     The (B) glass frit contains SiO 2 and TiO 2 and contains
    The ratio of the weight B of SiO 2 contained in the (B) glass frit to the weight D of SiO 2 contained in the (D) silica filler is weight B: weight D = 1: 0.25 to 1: 9. 8. The conductive paste according to claim 4.
  6. 　請求項１～５のいずれか１項に記載の導電性ペーストを焼成して得られる電極。 An electrode obtained by firing the conductive paste according to any one of claims 1 to 5.
  7. 　請求項６に記載の電極を有するチップ抵抗器。 A chip resistor having the electrode according to claim 6.
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