Classifications

• • 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
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form

Definitions

• the present invention relates to a conductive paste used for forming electrodes of electronic components, for example.
• the present invention also relates to an electrode formed using the conductive paste, and an electronic component such as a chip resistor having the electrode.
• FIG. 1 shows an example of a cross-sectional structure of a chip resistor 100.
• the chip resistor 100 has a rectangular alumina substrate 102, and a resistor 104 and an extraction electrode 106 for extracting electricity from the resistor 104 are formed on the upper surface of the alumina substrate 102.
• a lower surface electrode 108 is formed on the lower surface of the alumina substrate 102 for mounting the chip resistor 100 on the substrate.
• a connection electrode 110 for connecting the extraction electrode 106 and the lower surface electrode 108 is formed on the end surface of the alumina substrate 102.
• the extraction electrode 106 and the lower surface electrode 108 are each formed by applying a conductive paste to the upper and lower surfaces of the alumina substrate 102 by printing and then firing the paste.
• a nickel plating film 112 and a tin plating film 114 are formed on the extraction electrode 106, the bottom electrode 108, and the connection electrode 110.
• Patent Document 1 discloses a paste for a top electrode of a chip resistor, which is made by dispersing conductive powder, glass frit, and an inorganic binder in an organic vehicle.
• Patent Document 2 discloses that the conductive particles contain (A) surface-treated metal particles containing Ag and Sn, (C) glass frit, and (B) binder resin, and (A) the weight of Sn in the conductive particles. Conductive pastes are disclosed in which the proportion is less than 10% by weight.
• electrodes whose main material is metal such as silver used in devices such as chip resistors require highly sulfidation-resistant electrodes.
• an object of the present invention is to provide a conductive paste that has high sulfidation resistance and can form a relatively low-cost electrode.
• the present invention has the following configuration.
• Configuration 1 includes (A) conductive particles; (B) A conductive paste containing a binder resin, (A) the conductive particles include surface-treated metal particles, The surface-treated metal particles include metal particles and a surface treatment layer disposed on at least a portion of the surface of the metal particles, The surface treatment layer is a conductive paste containing a palladium compound.
• Configuration 2 is the conductive paste of Configuration 1, in which the content of palladium contained in the surface-treated metal particles is 0.01 to 1.0 parts by weight based on 100 parts by weight of the metal particles.
• Structure 3 is the conductive paste of Structure 1 or 2, in which the content of palladium contained in the surface-treated metal particles is 0.01 to 0.6 parts by weight based on 100 parts by weight of the metal particles.
• Configuration 4 is the conductive paste according to any one of Configurations 1 to 3, wherein the content of palladium contained in the surface-treated metal particles is 0.05 to 0.4 parts by weight based on 100 parts by weight of the metal particles. It is.
• Structure 5 is the conductive paste of any one of Structures 1 to 4, wherein the surface treatment layer further contains an organic substance.
• Configuration 6 is the conductive paste according to any one of Configurations 1 to 5, in which the metal particles contain 50% by weight or more of silver.
• Configuration 7 is the conductive paste of any of Configurations 1 to 6, wherein the average particle diameter (D50) of the surface-treated metal particles (A) is 0.1 to 10 ⁇ m.
• Configuration 8 is the conductive paste according to any one of Configurations 1 to 7, wherein the content of the binder resin (B) is 0.1 to 30 parts by weight based on 100 parts by weight of the (A) surface-treated metal particles. It is.
• Configuration 9 is the conductive paste of any one of Configurations 1 to 8, wherein the conductive paste further contains (C) glass frit.
• Structure 10 is the conductive paste of Structure 9, in which the glass frit (C) contains Bi 2 O 3 .
• Structure 11 is the conductive material of Structure 9 or 10, wherein the content of the (C) glass frit in the conductive paste is 0.05 to 10 parts by weight based on 100 parts by weight of the (A) surface-treated metal particles. It is a paste.
• Structure 12 is the conductive paste of any one of Structures 1 to 11, wherein the conductive paste further contains (F) a curing agent.
• Structure 13 is an electrode obtained by firing or heat-treating the conductive paste of any of Structures 1 to 12.
• Configuration 14 is the electrode of Configuration 13, wherein the electrode contains 0.01 to 10% by weight of palladium.
• Configuration 15 is an electronic component or electronic device that includes the electrode of configuration 13 or 14.
• FIG. 2 is a schematic diagram showing an example of a cross-sectional structure of a chip resistor. It is a schematic diagram which shows the shape of the test piece for the sulfidation resistance test of an Example and a comparative example. It is an optical micrograph which shows the shape of the test print pattern of the test piece for the migration resistance test of an Example and a comparative example. 4 is an optical microscope photograph showing an enlarged view of the center of the optical microscope photograph of the test print pattern of the test piece for the migration resistance test shown in FIG. 3.
• FIG. A scanning electron microscope (SEM) photograph of the surface of a fired conductive paste after a test piece prepared under the same conditions as in Example 3 was stored in a sulfur-containing gas atmosphere for 150 hours to sulfurize it.
• SEM scanning electron microscope
• FIG. 3 is a diagram showing changes over time in insulation resistance values of Example 1, Example 3, and Comparative Example 1 when an anti-migration test was conducted.
• the conductive paste of this embodiment includes (A) conductive particles and (B) a binder resin.
• the conductive paste of this embodiment can be preferably used to form electrodes of electronic components such as chip resistors.
• the conductive particles can contain 50% by weight or more of surface-treated metal particles including a surface-treated layer surface-treated with a palladium compound.
• the conductive paste of this embodiment includes (A) conductive particles.
• the conductive particles include surface-treated metal particles.
• the surface-treated metal particles include metal particles and a surface treatment layer disposed on at least a portion of the surface of the metal particles.
• the surface treatment layer is a thin film containing a palladium compound.
• the surface treatment layer is formed by surface treating metal particles with the palladium compound.
• the inventors of the present invention have discovered that the (A) conductive particles of the conductive paste of this embodiment include predetermined surface-treated metal particles, thereby improving the migration resistance of the resulting electrode as an additional effect. We also found that it improved.
• Migration resistance means a property capable of suppressing migration. Migration is when a voltage is applied to a pair of electrodes (a positive electrode and a negative electrode), and if water and/or water vapor is present near the electrodes, the metals contained in the electrodes and wiring become ionized, and the positive This is a phenomenon in which metal dendrites move from the electrode to the negative electrode and the insulation between wiring parts decreases. Furthermore, migration may occur even in an atmosphere not affected by moisture, such as at 100° C. or higher or in a vacuum.
• Migration resistance means such a property that can suppress migration, which has been widely known in the past.
• a pair of electrodes may be short-circuited due to metal migration. By improving migration resistance, short circuits of the electrodes can be suppressed.
• the conductive paste of this embodiment is not only a conductive paste of a type that is fired at a relatively high temperature (for example, 500 to 900 °C), but also a conductive paste that is fired at a relatively low temperature (for example, 100 to 200 °C). It has been found that even in the case of a thermosetting conductive paste that is thermally cured by the method, the migration resistance of the resulting electrode is improved. However, the advantage of improved migration resistance is not necessarily an essential effect of the conductive paste of this embodiment, but is considered to be one advantage.
• the conductive particles can contain metals other than the surface-treated metal particles. However, in order to reliably obtain an electrode having low electrical resistance and high sulfidation resistance, it is preferable that (A) the conductive particles contain 50% by weight or more of surface-treated metal particles; It is more preferable to contain 80% by weight or more of surface-treated metal particles, it is even more preferable to contain 90% by weight or more of surface-treated metal particles, and it is especially preferable that the surface-treated metal particles are composed only of surface-treated metal particles.
• "(A) conductive particles consist only of surface-treated metal particles” means that (A) conductive particles do not intentionally contain any metal other than surface-treated metal particles. This does not exclude the inclusion of conductive particles other than the surface-treated metal particles that are inevitably mixed in.
• the conductive particles can include metal particles of materials such as Zn, In, Al, and/or Si as metal particles other than the surface-treated metal particles, as long as the effects of this embodiment are not impaired.
• the metal particles included in the surface-treated metal particles and the metal particles other than the surface-treated metal particles can be metal particles of an alloy.
• the metal particles included in the surface-treated metal particles and the metal particles other than the surface-treated metal particles can include metal particles of a plurality of different types of metals or alloys.
• the surface-treated metal particles include metal particles and a surface treatment layer disposed on at least a portion of the surface of the metal particles.
• the surface treatment layer is a thin film formed on at least a portion of the surface of the metal particles.
• the material of the metal particles whose surface is treated with a palladium compound As the material of the metal particles whose surface is treated with a palladium compound, Ag, Cu, In, Al, or an alloy thereof can be used. Since the electrical conductivity is relatively high, the material of the metal particles is preferably Ag and/or Cu, and more preferably Ag.
• the metal particles preferably contain 50% by weight or more of silver (Ag), more preferably 80% by weight or more of silver (Ag), and 90% by weight of silver (Ag). It is more preferable to contain silver (Ag) in an amount of 95% by weight or more.
• the metal particles of the surface-treated metal particles contained in the conductive paste of this embodiment consist only of silver (Ag) particles. This is because the electrical conductivity of silver is relatively high compared to other metals.
• the metal particles of the surface-treated metal particles consist only of silver (Ag) particles means that metal particles other than silver (Ag) particles are intentionally not used as the metal particles. This does not preclude the inclusion of metal particles other than silver (Ag) particles that are unavoidably mixed. Similarly, other similar descriptions do not exclude substances that are unavoidably mixed.
• the conductive paste of this embodiment preferably contains 50 parts by weight or more of surface-treated metal particles, more preferably 70 parts by weight or more, and still more preferably 80 parts by weight or more, based on 100 parts by weight of the conductive paste. preferable. Further, the conductive paste of the present embodiment preferably contains 50 to 99 parts by weight of surface-treated metal particles, more preferably 70 to 97 parts by weight or more, and 80 to 95 parts by weight, based on 100 parts by weight of the conductive paste. It is more preferable to include parts by weight. By being within the above range, it is possible to form an electrode with high sulfidation resistance and relatively low cost.
• the method for producing metal particles is not particularly limited, and can be produced by, for example, a reduction method, a pulverization method, an electrolysis method, an atomization method, a heat treatment method, or a combination thereof.
• Flake-shaped metal particles can be produced, for example, by crushing spherical or granular metal particles using a ball mill or the like.
• the surface-treated metal particles include a surface treatment layer disposed on at least a portion of the surface of the metal particles.
• the surface treatment layer is a thin film formed on at least a portion of the surface of the metal particles by surface treating the metal particles with a surface treatment agent containing a palladium compound.
• Palladium compounds that serve as raw materials for surface treatment of metal particles include palladium (II) chloride, palladium (II) oxide, organic palladium compounds, palladium fluoride, palladium on carbon, n-allyl palladium complex, cyclopentadienyl allyl palladium. , dichlorobis(triphenylphosphine)palladium (II), palladium bromide, and palladium complexes such as palladium fatty acid complexes such as palladium oleate. It is preferable to use palladium chloride as a palladium compound that is a raw material for surface treating metal particles.
• the surface treatment layer can be formed by surface treatment using a palladium compound by a known method. Specifically, the surface treatment layer is formed by attaching a palladium soap solvent (surface treatment agent) containing palladium or palladium ions, an organic substance for dispersing these, and a solvent to the surface of the metal particles, and then applying the palladium soap solvent (surface treatment agent) containing palladium or palladium ions, an organic substance for dispersing these, and a solvent to the surface of the metal particles. , with the solvent removed. Thereby, a surface treatment layer containing a palladium compound can be formed on the surface of the metal particles.
• a palladium soap solvent surface treatment agent
• the organic substance for dispersing palladium or palladium ions is preferably at least one selected from fatty acids and triazole compounds.
• fatty acids include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, cabric acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, margaric acid, and stearic acid.
• fatty acids oleic acid, vaccenic acid, linoleic acid, linolenic acid, arachidic acid, eicosadienoic acid, eicosatrienoic acid, eicosatetraenoic acid, arachidonic acid, behenic acid, lignoceric acid, nervonic acid, cerotic acid, montanic acid, and At least one selected from melisic acid and the like can be used.
• these fatty acids it is preferable to use at least one selected from palmitic acid, stearic acid, and oleic acid. It is more preferable to use oleic acid as the organic substance (fatty acid) contained in the surface treatment agent.
• benzotriazole can be used as the triazole compound.
• the solvent contained in the surface treatment agent for forming the surface treatment layer may be any solvent that can be used to disperse palladium or palladium ions and to properly adhere the palladium compound to the metal particles.
• solvents include alcohols such as methanol, ethanol, and isopropyl alcohol (IPA), organic acids such as ethylene acetate, aromatic hydrocarbons such as toluene and xylene, N-methyl-2-pyrrolidone (NMP), etc.
• N-alkylpyrrolidones amides such as N,N-dimethylformamide (DMF), ketones such as methyl ethyl ketone (MEK), cyclic carbonates such as terpineol (TEL), and diethylene glycol monobutyl ether (butyl carbitol, BC) , bis[2-(2-butoxyethoxy)ethyl]adipate, 2,2,4-trimethylpentane-1,3-diol monoisobutyrate (Texanol), and water.
• DMF N,N-dimethylformamide
• MEK methyl ethyl ketone
• TEL cyclic carbonates
• TEL terpineol
• BC diethylene glycol monobutyl ether
• a surface treatment layer can be formed on the surface of the metal particles by attaching a surface treatment agent containing a solvent in which the above palladium compound is dispersed to the surface of the metal particles and removing the solvent by drying. In this way, surface-treated metal particles can be obtained.
• the surface treatment layer of the surface treated metal particles can be manufactured as follows. That is, first, metal particles are dispersed in water. A solvent in which the above-mentioned palladium compound is dispersed is added as a coating agent to water in which metal particles are dispersed to obtain a water slurry containing metal particles coated with a coating agent containing palladium, and then the coating is performed by decantation. The metal particles coated with the agent are allowed to settle. Next, the supernatant liquid is removed, and the resulting wet metal particles coated with the coating material are added together with an acrylic dispersant to a polar solvent having a boiling point of 150 to 300°C.
• surface-treated metal particles can be produced by drying in a nitrogen atmosphere at a temperature from room temperature to 100° C., preferably at a temperature of 80° C. or less for 12 hours or more to remove moisture. Note that if the drying temperature is too high, the surface-treated metal particles will be sintered, which is not preferable.
• the surface treatment layer of the surface treated metal particles contained in the conductive paste of this embodiment further contains an organic substance.
• the surface treatment layer when the surface treatment layer is formed using the above-mentioned palladium compound, the surface treatment layer contains an organic substance. Since the surface-treated metal particles have a surface-treated layer containing an organic substance, the resulting electrode can have high sulfidation resistance even if the amount of palladium compound is small.
• the organic substance may be a liquid organic fatty acid or a solid fatty acid.
• liquid fatty acids examples include saturated fatty acids such as butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, and pelargonic acid, as well as myristoleic acid, palmitoleic acid, ricinoleic acid, oleic acid, linoleic acid, and linolenic acid. Unsaturated fatty acids such as These fatty acids may be used alone or in combination of two or more. Among these, it is preferable to use oleic acid, linoleic acid, or a mixture thereof.
• solid fatty acids include saturated fatty acids having 10 or more carbon atoms, such as capric acid, palmitic acid, and stearic acid, and unsaturated fatty acids, such as crotonic acid and sorbic acid.
• the surface treatment layer of the surface treated metal particles used in this embodiment is a thin film of a palladium compound.
• This embodiment is characterized in that the surface treatment layer of the surface treatment metal particles is not a thin film made of palladium metal or palladium alloy.
• the surface treatment layer is a thin film made of palladium metal or palladium alloy, the amount of palladium blended is too large, which may cause adverse effects such as an increase in the electrical resistance of the resulting electrode.
• a large amount of palladium metal or palladium alloy is present on the surface of the metal particles, which deteriorates the wettability of the solder to metal particles such as silver particles, increasing the possibility that soldering will be inhibited.
• the amount of palladium used increases, the cost will be high.
• the surface treatment layer is a thin film formed on at least a portion of the surface of the metal particles.
• the surface treatment layer is preferably a thin film that covers 50% or more of the surface of the metal particle, more preferably a thin film that covers 80% or more of the surface of the metal particle, and covers 90% or more of the surface of the metal particle.
• a thin film is preferable, and a thin film covering 95% or more of the surface of the metal particles is particularly preferable.
• the surface treatment layer is a thin film that covers the entire surface of the metal particles.
• the thickness of the surface treatment layer of the surface-treated metal particles does not necessarily have to be uniform, but is preferably uniform in order to more effectively suppress sulfidation of the metal particles.
• the thickness of the surface treatment layer can be controlled by, for example, controlling the viscosity of the palladium soap solvent (surface treatment agent) in which the palladium compound is dispersed, and the concentration of the palladium compound in the palladium soap solvent (surface treatment agent). It can be controlled by adjusting. Further, by controlling the thickness of the surface treatment layer, the amount of palladium contained in the surface treatment layer can be controlled.
• the thickness of the surface treatment layer is preferably from 1 to 100 nm, more preferably from 1 to 70 nm, particularly preferably from 1 to 50 nm.
• the thickness of the surface treatment layer can be measured, for example, by X-ray photoelectron spectroscopy. By setting the thickness of the surface treatment layer within this range, an electrode with high sulfidation resistance can be formed while using a small amount of palladium compound.
• the conductive paste of this embodiment contains (A) surface-treated metal particles surface-treated with a palladium compound as the conductive particles, an electrode having high sulfidation resistance can be created without using a large amount of expensive palladium. can be formed. Therefore, by using the conductive paste of this embodiment, an electrode having high sulfidation resistance and relatively low cost can be formed. In particular, when silver particles are used as metal particles, silver is easily sulfurized. By using the conductive paste of this embodiment, it is possible to effectively suppress disconnection of an electrode mainly made of silver due to sulfurization at low cost.
• the reason why sulfidation of the silver particles can be suppressed by using surface-treated metal particles (surface-treated silver particles) that have been surface-treated with a palladium compound is as follows. It can be inferred as follows. That is, it is presumed that palladium as a surface treatment component and metal particles form a uniform alloy layer through sintering, thereby improving the sulfidation resistance.
• a type of conductive paste that is fired at a relatively high temperature for example, 500 to 900°C
• the palladium in the palladium compound is mixed with metal particles and a palladium metal alloy layer (if the metal particles are silver particles, palladium - silver alloy layer).
• this palladium metal alloy layer imparts high sulfidation resistance to the metal particles.
• a palladium compound is formed as a thin film on the surface of metal particles such as silver particles.
• sulfidation resistance can be obtained.
• the content of palladium contained in the surface treatment layer is not very large. Therefore, compared to the case where palladium particles are added separately, the amount of palladium used can be reduced, and high sulfidation resistance can be obtained at relatively low cost.
• the electrode thus obtained has high sulfidation resistance and excellent adhesion to the substrate. Similar inferences can be made regarding metal particles other than silver particles. However, the present invention is not limited to this inference.
• the migration resistance of the obtained electrode can be improved as an additional effect.
• the reason why migration resistance can also be improved by using surface-treated metal particles (surface-treated silver particles) whose surface has been treated with a palladium compound is that by using surface-treated metal particles whose surface has been treated with a palladium compound, migration resistance can also be improved.
• the density of the electrode is also improved. It is presumed that this improves migration resistance.
• the present invention is not limited to this inference.
• the content of palladium contained in the surface-treated metal particles is preferably 0.01 parts by weight or more, and preferably 0.05 parts by weight or more, based on 100 parts by weight of the metal particles.
• the amount is more preferably 0.08 parts by weight or more, and particularly preferably 0.08 parts by weight or more.
• the palladium content is preferably 1.0 parts by weight or less, more preferably 0.8 parts by weight or less, and 0.6 parts by weight or less based on 100 parts by weight of the metal particles. is more preferable, particularly preferably 0.4 parts by weight or less, and most preferably 0.3 parts by weight or less.
• the content of palladium contained in the surface-treated metal particles is within the above range, the amount of palladium used is small, and the change in resistance value of the electrode due to sulfidation of the electrode can be reduced while the cost is low.
• the content of palladium contained in the surface-treated metal particles can be measured by ICP emission spectrometry (high frequency inductively coupled plasma emission spectrometry).
• the shape of the conductive particles is not particularly limited, and for example, spherical, granular, flaky, and/or scaly surface-treated metal particles can be used.
• the average particle size of the conductive particles is preferably 0.1 ⁇ m to 10 ⁇ m, more preferably 0.2 ⁇ m to 8 ⁇ m, even more preferably 0.3 ⁇ m to 7 ⁇ m, particularly preferably 0.4 to 6 ⁇ m. It is.
• the average particle diameter herein means the volume-based median diameter (D50) obtained by laser diffraction scattering particle size distribution measurement method.
• the conductive paste of this embodiment contains (B) a binder resin.
• the (B) binder resin connects the (A) conductive particles together in the conductive paste.
• the conductive paste of this embodiment may or may not include (C) glass frit, which will be described later.
• the function of the binder resin (B) included in the conductive paste of this embodiment is different depending on whether it contains (C) glass frit or not.
• the conductive paste of this embodiment includes (C) glass frit
• the conductive paste of this embodiment is applied to a predetermined base material so as to form a predetermined electrode pattern, and heated to a relatively high temperature (for example, 500 to 900°C). ), an electrode can be formed.
• the binder resin (B) is burned out during firing. Therefore, the function of the binder resin (B) in this case is to (A) connect the conductive particles together when the conductive paste of this embodiment is applied to a predetermined base material in a predetermined electrode pattern. That's true.
• the conductive paste of this embodiment does not contain (C) glass frit
• the conductive paste of this embodiment is applied to a predetermined base material so as to form a predetermined electrode pattern, and the conductive paste is applied at a relatively low temperature (for example, 100 to 200 °C), an electrode can be formed.
• the binder resin (B) is not burned out during heat treatment.
• the function of the binder resin (B) is to connect the conductive particles (A) to each other when the conductive paste of this embodiment is applied to a predetermined base material in a predetermined electrode pattern.
• the shape of the electrode after the heat treatment is maintained by connecting the conductive particles together after the heat treatment.
• binder resin for example, cellulose resins such as ethyl cellulose resin and nitrocellulose resin, thermoplastic resins such as acrylic resin, alkyd resin, saturated polyester resin, butyral resin, polyvinyl alcohol, and hydroxypropyl cellulose may be used. I can do it. These resins can be used alone or in combination of two or more.
• binder resin (B) it is preferable to use at least one selected from cellulose resins such as ethyl cellulose resins and nitrocellulose resins, and alkyd resins.
• epoxy resin is used as the binder resin.
• any known epoxy resin can be used.
• epoxy resins include bisphenol A type, bisphenol F type, biphenyl type, tetramethylbiphenyl type, cresol novolac type, phenol novolac type, bisphenol A novolac type, dicyclopentadienephenol condensation type, phenol aralkyl condensation type, and glycidylamine.
• epoxy resins such as molds, brominated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.
• epoxy resins can be used alone or in combination of two or more.
• a thermosetting resin other than epoxy resin may be used for the purpose of improving the adhesion between surface-treated metal particles.
• thermoplastic resins such as polyurethane resins and/or polycarbonate resins may also be used.
• the content of the binder resin (B) is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 15 parts by weight, and The amount is preferably 1 to 10 parts by weight, particularly preferably 1.5 to 8 parts by weight.
• the content of the binder resin (B) in the conductive paste is within the above range, the applicability of the conductive paste to the substrate (base material) and/or the paste leveling properties are improved, resulting in an excellent printed shape. Obtainable.
• the content of the binder resin (B) exceeds the above range, the amount of the binder resin (B) contained in the applied conductive paste is too large. Therefore, there is a possibility that electrodes and the like cannot be formed with high precision.
• the conductive paste of this embodiment can further include (C) glass frit.
• the conductive paste of this embodiment includes (C) glass frit
• the conductive paste of this embodiment is applied to a predetermined base material so as to form a predetermined electrode pattern, and heated to a relatively high temperature (for example, 500 to 900°C). ), an electrode can be formed.
• a relatively high temperature for example, 500 to 900°C.
• the above-mentioned binder resin (B) is burned out during firing.
• the (C) glass frit contained in the conductive paste connects the (A) conductive particles to each other, so that the shape of the electrode after firing can be maintained.
• the glass frit is not particularly limited, but a glass frit with a softening point of preferably 300°C or higher, more preferably 400 to 900°C, and even more preferably 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 (C) examples include borosilicate-based and barium borosilicate-based glass frits.
• glass frits include bismuth borosilicate, alkali metal borosilicate, alkaline earth metal borosilicate, zinc borosilicate, lead borosilicate, lead borate, lead silicate, and bismuth borate. and zinc borate-based glass frits. These glass frits can also be used in combination of two or more types.
• the glass frit is preferably lead-free from the viewpoint of environmental considerations.
• the glass frit contains at least one selected from the group consisting of ZnO, Bi 2 O 3 , BaO, Na 2 O, CaO, and Al 2 O 3 . More preferably, the glass frit contains at least one selected from the group consisting of ZnO and Bi 2 O 3 .
• the conductive paste of this embodiment includes (C) glass frit
• the glass frit includes ZnO.
• a glass frit containing ZnO zinc-based glass frit
• an electrode with higher sulfidation resistance can be obtained.
• the conductive paste of this embodiment includes (C) glass frit
• the glass frit includes Bi 2 O 3 .
• a glass frit containing Bi 2 O 3 bismuth-based glass frit
• the density of the electrode can be improved.
• the average particle size of the glass frit is preferably 0.1 to 20 ⁇ m, more preferably 0.2 to 10 ⁇ m, particularly preferably 0.5 to 5 ⁇ m.
• the average particle size here means the volume-based median diameter (D50) obtained by laser diffraction scattering particle size distribution measurement method.
• the content of (C) glass frit is preferably 0.05 to 10 parts by weight based on 100 parts by weight of (A) conductive particles.
• the amount is preferably 0.5 to 8 parts by weight, more preferably 1 to 6 parts by weight, and particularly preferably 2 to 4 parts by weight. If the content of glass frit is less than this range, the adhesion of the electrode obtained by firing the conductive paste to the substrate (base material) will decrease. If the content of glass frit is more than this range, the resistance value of the electrode obtained by firing the conductive paste will be high, and the surface of the fired body will be covered with the glass component, resulting in poor plating properties.
• Chemical resistance is a required property because plating pretreatment is required when forming a plating film on the surface of an electrode. Plating pretreatment is performed for the purpose of removing contaminants from the electrode surface, activating the electrode surface, and bringing it into a clean state suitable for plating.
• the pollutants that need to be removed can be broadly divided into organic and inorganic pollutants.
• the pretreatment step is not a single step that removes all contaminants. For example, organic substances are removed in a process using an alkaline cleaning agent. Inorganic substances are removed in a process using acid-based cleaning agents. Therefore, electrodes are required to have high chemical resistance.
• the conductive paste of this embodiment includes (C) glass frit, the glass frit softens as the temperature rises, and the sintering (firing) of the (A) conductive particles progresses.
• the glass frit content is large, the glass component may be pushed out to the surface of the fired body. In that case, the surface of the fired body may be covered with a glass component.
• the glass frit contains zinc oxide, the Zn component in the glass frit precipitates as ZnO at the crystallization temperature, so the (A) conductivity after firing is similar to palladium in the surface-treated metal particles. It can contribute to the sulfidation resistance of particles.
• the conductive paste of this embodiment can contain a dispersant as the (D) additive.
• the dispersant in the conductive paste of this embodiment, the dispersibility of (A) conductive particles in the conductive paste can be improved, and (A) conductive particles can be prevented from agglomerating. can.
• the dispersant a known dispersant can be used.
• a fatty acid amide an acid type low molecular dispersant, or bismuth oxide (Bi 2 O 3 ) can be used.
• the conductive paste of the present embodiment may contain organic additives, inorganic additives, and the like as (D) additives other than the dispersant.
• additives for example, silica filler, rheology modifier, and/or pigment can be used.
• the conductive paste of this embodiment can contain (E) a solvent.
• solvents 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 such as, amides such as N,N-dimethylformamide (DMF), ketones such as methyl ethyl ketone (MEK), cyclics such as terpineol (TEL), and diethylene glycol monobutyl ether (butyl carbitol, BC)
• Examples include carbonates, bis[2-(2-butoxyethoxy)ethyl]adipate, 2,2,4-trimethylpentane-1,3-diol monoisobutyrate (Texanol), and water.
• the content of the solvent in the conductive paste of this embodiment is not particularly limited.
• the content of the solvent is, for example, preferably 1 to 100 parts by weight, more preferably 5 to 60 parts by weight, and still more preferably 8 to 35 parts by weight, based on 100 parts by weight of the (A) conductive particles.
• the viscosity of the conductive paste of this embodiment is preferably 50 to 700 Pa ⁇ s (shear rate: 4.0 sec ⁇ 1 ), more preferably 100 to 300 Pa ⁇ s (shear rate: 4.0 sec ⁇ 1 ).
• the viscosity of the conductive paste of this embodiment can be adjusted by appropriately controlling the content of the solvent. By adjusting the viscosity of the conductive paste within this range, the applicability and/or handling of the conductive paste to the substrate (base material) becomes good, and the conductive paste can be applied to the substrate with a uniform thickness. becomes possible.
• the viscosity of the conductive paste can be measured at a temperature of 25° C. and 10 rpm using an HB type viscometer (manufactured by Brookfield Corporation) (SC4-14 spindle).
• the conductive paste of this embodiment further contains (F) a curing agent.
• the conductive paste of this embodiment contains an epoxy resin as the binder resin (B), the curing of the epoxy resin can be appropriately controlled by including the curing agent (F).
• a known curing agent can be used as the curing agent.
• the curing agent preferably contains at least one selected from a phenolic curing agent, a cationic polymerization initiator, an imidazole curing agent, and a boron trifluoride compound.
• the boron trifluoride compound include boron trifluoride monoethylamine, boron trifluoride piperidine, and boron trifluoride diethyl ether.
• boron trifluoride monoethylamine can be preferably used.
• the conductive paste of this embodiment when the total weight of (A) conductive particles and (C) epoxy resin as a binder resin is 100 parts by weight, the conductive paste contains 0 (F) curing agent. .1 to 5 parts by weight, more preferably 0.15 to 2 parts by weight, even more preferably 0.2 to 1 parts by weight, particularly 0.3 to 0.6 parts by weight. preferable.
• the epoxy resin that is the binder resin component (B) can be appropriately cured, and an electrode with a desired shape can be obtained.
• the conductive paste of this embodiment can be manufactured by mixing the above-mentioned components using, for example, a Raikai machine, a pot mill, a three-roll mill, a rotary mixer, and/or a twin-shaft mixer. .
• This embodiment is an electrode obtained by firing or heat-treating the conductive paste of this embodiment described above.
• the conductive paste of this embodiment includes (C) glass frit
• the conductive paste of this embodiment is applied to a predetermined base material so as to form a predetermined electrode pattern, and heated to a relatively high temperature (for example, 500 to 900°C). ), the electrode can be formed by firing in an air atmosphere. Therefore, when the conductive paste of this embodiment contains (C) glass frit, the electrode is made of (A') conductive particles containing surface-treated metal particles and (C) glass frit. It can contain a glass component. After firing, the conductive particles (A') are in a sintered state.
• the electrode does not substantially contain (B) binder resin and (E) solvent.
• the conductive paste of this embodiment does not contain (C) glass frit
• the conductive paste of this embodiment is applied to a predetermined base material so as to form a predetermined electrode pattern, and the conductive paste is applied at a relatively low temperature (for example, 100 to 200 °C), an electrode can be formed. Therefore, when the conductive paste of this embodiment does not contain (C) glass frit, the electrode of this embodiment is made of (A') conductive particles containing surface-treated metal particles and (B) a binder resin. (B') a binder component. (A') The conductive particles are connected via the (B') binder component.
• the electrode of this embodiment contains palladium.
• the electrode of this embodiment preferably contains 0.01 to 10% by weight of palladium, more preferably 0.05 to 5% by weight of palladium, and even more preferably 0.07 to 1% by weight of palladium. , it is particularly preferable to contain palladium in an amount of 0.08 to 0.5% by weight.
• the electrode of this embodiment can contain palladium resulting from (C) glass frit. Since the electrode of this embodiment contains a predetermined amount of palladium, the electrode of this embodiment can have high sulfidation resistance. Note that the palladium content in the electrode can be measured by elemental analysis using EDS (Energy Dispersive X-ray Spectroscopy).
• the electrode of this embodiment can contain zinc (zinc oxide) resulting from (C) glass frit. Since the electrode of this embodiment contains zinc in addition to palladium, high sulfidation resistance can be obtained.
• the sheet resistance of the thin film serving as the electrode of this embodiment varies depending on the film thickness, but can be approximately 10 m ⁇ / ⁇ (10 m ⁇ /square) or less than 10 m ⁇ / ⁇ . Therefore, it can be preferably used for forming electrodes that are required to have low resistance.
• a method for forming electrodes on a substrate (base material) using the conductive paste of this embodiment will be described.
• a conductive paste is applied onto the substrate.
• the conductive paste can be applied by any known method, such as dispensing, jet dispensing, stencil printing, screen printing, pin transfer, or stamping.
• the conductive paste of this embodiment includes (C) glass frit
• the conductive paste applied onto the substrate is fired at 500 to 900°C, more preferably 600 to 880°C, and still more preferably 700 to 870°C.
• a specific example of the firing temperature is 850°C.
• the solvent component contained in the conductive paste evaporates at 300° C. or lower, and the resin component is burned out at 400° C. to 600° C., forming a fired body (electrode) of the conductive paste.
• the organic components contained in the surface-treated metal particles disappear by firing in an air atmosphere, and the palladium in the palladium compound is formed by forming a palladium metal alloy layer on the surface of the metal particles (if the metal particles are silver particles, palladium - silver alloy layer). It is believed that the palladium metal alloy layer on the surface of the metal particles imparts high sulfidation resistance to the metal particles. Therefore, high sulfidation resistance can be obtained when the metal particles include a thin film surface treatment layer containing a palladium compound. Further, the content of palladium contained in the surface treatment layer is not very large.
• the electrode thus obtained has high sulfidation resistance and excellent adhesion to the substrate.
• the conductive paste of this embodiment does not include (C) glass frit
• the conductive paste is applied onto the substrate, and then the substrate is placed in a heat treatment furnace or the like. Then, the conductive paste applied on the substrate is heat treated at 100 to 200°C, more preferably 150 to 200°C.
• the heat treatment time is preferably 20 to 90 minutes, more preferably 30 to 60 minutes.
• a specific example of the heat treatment conditions is 150° C. for 60 minutes.
• a cured body (electrode) of the conductive paste can be formed by drying the solvent component contained in the conductive paste and thermosetting the conductive paste. The electrode thus obtained has high sulfidation resistance and excellent adhesion to the substrate.
• an example of a particularly preferable content of palladium contained in the electrode of this embodiment is 0.2 to 0.5% by weight.
• the electrode obtained as described above using the conductive paste of this embodiment can have the additional advantage of improved migration resistance.
• This additional advantage can be obtained both when the conductive paste contains (C) a glass frit and (C) does not contain a glass frit.
• this advantage is not necessarily an essential effect of the conductive paste of this embodiment, but is considered to be one advantage.
• This embodiment is an electronic component or electronic device having the above-described electrode.
• electronic components refer to components used in electronic devices, such as chip resistors and board circuits.
• an electronic component means a component that operates electronically, and specifically can be a component that operates at 48 V or less of DC.
• an electronic device means a device including an electronic component having the electrode of this embodiment.
• the conductive paste of this embodiment can be used for forming circuits of electronic components or electronic equipment, forming electrodes, and bonding devices such as electronic components (for example, semiconductor chips) to a substrate (base material). be.
• FIG. 1 shows an example of a cross-sectional structure of a chip resistor 100 of this embodiment.
• the chip resistor 100 can include a rectangular alumina substrate 102, a resistor 104 and an extraction electrode 106 arranged on the surface of the alumina substrate 102.
• 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 extraction electrode 106 and the lower surface electrode 108 can be arranged on the end surface of the alumina substrate 102.
• At least one of the extraction electrode 106, the bottom electrode 108, and the connection electrode 110 can be formed using the conductive paste of this embodiment.
• the extraction electrode 106 be formed using the conductive paste of this embodiment.
• a nickel plating film 112 and a tin plating film 114 can be disposed on the top surface of the extraction electrode 106, the bottom electrode 108, and the connection electrode 110 (the surface opposite to the alumina substrate 102).
• the electrode of this embodiment is not limited to the electrode of a chip resistor. Electrodes formed using the conductive paste of this embodiment can be used as electrodes for various types of electronic components. Electronic components include passive components (for example, chip resistors, capacitors, resistors, inductors, etc.), circuit boards (for example, a predetermined circuit (electrode or wiring) on a substrate such as an alumina substrate, an aluminum nitride substrate, a glass substrate, etc.). ), solar cells, and electromagnetic shields. The conductive paste of this embodiment can be used to form electrodes and/or wiring of these electronic components. Examples of electronic devices including electronic components having the electrodes of this embodiment include semiconductor devices, photovoltaic modules, and electronic devices including circuit boards.
• the conductive paste of this embodiment can be used as a die attach material for attaching a semiconductor chip in a semiconductor device.
• the semiconductor device is a power semiconductor device, it can be used as a brazing material for attaching a power semiconductor chip.
• the conductive paste of this embodiment can be used as an electrode of a solar cell.
• the conductive paste of this embodiment can be used as a conductive adhesive.
• the conductive paste of this embodiment can be suitably used not only for forming terminal electrodes of chip resistors, but also as a conductive paste for terminal electrodes of passive components such as MLCCs and chip inductors. .
• the conductive paste of this embodiment it is possible to form an electrode that has high sulfidation resistance, low resistance, and relatively low cost. Therefore, by using the conductive paste of this embodiment, electronic components such as chip resistors in which highly reliable electrodes are formed can be obtained at relatively low cost.
• a conductive paste was prepared by mixing the following components (A) to (F) in the proportions shown in Tables 1 to 3. Note that the proportions of each component shown in Tables 1 to 3 are all shown in parts by weight. In Tables 1 to 3, the weight of (A) conductive particles (total weight of metal particles and surface-treated metal particles) was 100 parts by weight. Moreover, the average particle size means the volume-based median diameter (D50) obtained by laser diffraction scattering particle size distribution measuring method.
• (A) Conductive Particles Table 5 shows metal particles a1 to a4 and surface-treated metal particles A1 to A6 used as (A) conductive particles (component (A)) in Examples and Comparative Examples.
• Metal particles a1 and a2 are silver particles, and metal particle a4 is a palladium particle.
• Metal particles a1 to a4 are not surface-treated.
• Surface-treated metal particles A1 to A6 are produced by attaching a palladium soap solvent (surface treatment agent) in which a palladium compound is dispersed in a solvent to the surface of silver particles, which are metal particles, and removing the solvent through a drying process.
• the surface-treated metal particles A1 to A6 have a surface-treated layer containing a palladium compound.
• the weight ratio of palladium contained in the surface treatment layer to the weight of the surface treatment metal particles A1 to A6 is shown in units of weight %.
• the weight proportion of palladium in the surface-treated metal particles was measured by ICP emission spectroscopy (high frequency inductively coupled plasma emission spectroscopy).
• Surface treatment of silver particles with a palladium compound was performed as follows. That is, the surface treatment of the silver particles with a palladium compound was performed using a palladium soap solvent (surface treatment agent) containing a palladium compound, an organic substance for dispersing these, and a solvent. The surface treatment was performed by attaching a palladium soap solvent (surface treatment agent) to the surface of the silver particles and removing the solvent through a drying process. Palladium chloride was used as the palladium compound. Furthermore, oleic acid was used as the solvent contained in the silver particle surface treatment agent. As described above, surface treatment layers were formed on the surface treatment metal particles A1 to A6.
• Binder resin Table 5 shows the (B) binder resins (resins B1 to B5) used in the examples and comparative examples.
• Tables 1 to 3 show the blending amounts of resins B1 to B5 in the conductive pastes of Examples and Comparative Examples.
• (C) Glass Frit Table 6 shows the (C) glass frits (C1 to C4) used in the Examples and Comparative Examples.
• Tables 1 to 3 show the blending amounts of glass frits C1 to C4 in the conductive pastes of Examples and Comparative Examples.
• Additives Table 7 shows the (D) additives (Additives D1 to D3) used in Examples and Comparative Examples. Tables 1 to 3 show the amounts of additives D1 to D3 in the conductive pastes of Examples and Comparative Examples.
• Additive D1 is an organic additive. By adding additive D1, the printability of the conductive paste can be improved.
• Additive D2 is a dispersant. By adding additive D2, the dispersibility of (A) conductive particles and the like can be improved.
• Additive D3 is an inorganic additive. By adding additive D3, the adhesion of the conductive paste after firing can be improved.
• (E) Solvents Table 8 shows the (E) solvents (solvents E1 to E3) used in the Examples and Comparative Examples. Tables 1 to 3 show the blending amounts of solvents E1 to E3 in the conductive pastes of Examples and Comparative Examples.
• (F) Curing Agent In the conductive pastes of Examples and Comparative Examples, boron trifluoride monoethylamine (Stella Chemifa Co., Ltd., model number: BF3MEA) was used as the (F) curing agent F1. Tables 1 to 3 show the amount of curing agent F1 in the conductive pastes of Examples and Comparative Examples.
• FIG. 2 shows a schematic diagram of a test piece 50 for the sulfidation resistance test.
• C Test pieces 50 for sulfidation resistance tests of Examples 1 to 16 and Comparative Examples 1 to 5 were prepared using a conductive paste containing glass frit according to the following procedure.
• a zigzag printed pattern 54 for sulfidation resistance testing as shown in FIG. 2 is formed by screen printing.
• a conductive paste was applied.
• the length between the two ends 54a and 54b of the printed pattern 54 for sulfidation resistance testing is 71 mm, and the width of the printed pattern 54 for sulfidation resistance testing is 1 mm.
• screen printing was performed using a stainless steel 325 mesh screen (emulsion thickness 5 ⁇ m).
• the printed pattern 54 for sulfidation resistance test of the conductive paste was dried at 150° C. for 10 minutes using a batch type hot air dryer. After drying the printed pattern 54 for sulfidation resistance test of the conductive paste, the printed pattern 54 for sulfidation resistance test was fired using a belt-type firing furnace. The firing temperature was maintained at 850°C for 10 minutes. The total time from putting it in the kiln to taking it out was 60 minutes. In the manner described above, test pieces 50 of Examples 1 to 16 and Comparative Examples 1 to 5 were produced.
• Resistance value change rate (electrical resistance after sulfidation - initial electrical resistance) / initial electrical resistance
• test piece for adhesive strength test Using the prepared conductive paste, test pieces of Examples 1 to 16 and Comparative Examples 1 to 5 containing (C) glass frit were produced according to the following procedure. First, a conductive paste was applied by screen printing onto a 20 mm x 20 mm x 1 mm (t) alumina substrate (purity 96%). As a result, 25 (5 ⁇ 5) adhesive strength test patterns each having a square pad shape of 1.5 mm on a side were formed on the alumina substrate. In order to form a pattern for testing the adhesive strength of the conductive paste, screen printing was performed using a stainless steel 325 mesh screen (emulsion thickness: 5 ⁇ m).
• the conductive paste was dried at 150° C. for 10 minutes using a batch hot air dryer. After drying the pattern for testing the adhesive strength of the conductive paste, the pattern for testing the adhesive strength of the conductive paste was fired using a belt-type firing furnace. The firing temperature was maintained at 850°C for 10 minutes. The total time from putting it in the kiln to taking it out was 60 minutes. In the manner described above, test pieces of Examples 1 to 16 and Comparative Examples 1 to 5 were prepared.
• Ni/Au plating was performed on the adhesive strength test pattern.
• solder M705 manufactured by Senju Metal Industry Co., Ltd., a Sn alloy containing 3.0% by weight of Sn-Ag and 0.5% by weight of Cu
• a Sn-plated annealed copper wire (diameter 0.8 mm) was soldered to the adhesive strength test pattern.
• For soldering the Sn-plated annealed copper wire out of the 5 x 5 adhesive strength test patterns on the alumina board, one for each of the 5 pieces in the second row, for a total of 5 Sn-plated annealed copper wires.
• the conductive pastes prepared as Examples 17 to 19 were used on a 20 mm x 20 mm x 1 mm (t) alumina substrate (purity 96%). Then, a conductive paste was applied by screen printing. As a result, 25 (5 ⁇ 5) adhesive strength test patterns each having a square pad shape of 1.5 mm on a side were formed on the alumina substrate. Next, the conductive paste was heat-treated at 150° C. for 10 minutes using a hot air dryer to harden the adhesive strength test pattern of the conductive paste. Test pieces of Examples 17 to 19 were prepared as described above.
• the results of the adhesive strength test were obtained by measuring the tensile adhesive strength of 10 test pieces of each example and each comparative example.
• the "Adhesive Strength (N)" column of Tables 1 to 3 shows the average value of the tensile adhesive strength of the 10 test pieces of each Example and each Comparative Example measured as described above.
• FIG. 3 shows an optical micrograph of test print patterns 64a and 64b of an example of the test piece 60 for the migration resistance test.
• test pieces 60 for the migration resistance test of Examples 1, 3, and 17 to 19 and Comparative Example 1 were prepared according to the following procedure.
• Test pieces 60 for the migration resistance test of Examples 1 and 3 and Comparative Example 1 were produced in the following procedure. First, on a 110 mm x 20 mm x 0.8 mm (t) alumina substrate 62 (purity 96%) for migration resistance testing, as shown in FIG. 3 and FIG. The conductive paste was applied so that the two comb-shaped migration resistance test printed patterns 64a and 64b were alternated. The printed pattern for migration resistance test 64a is connected to the first electrode 66a, and the printed pattern for migration resistance test 64b is connected to the second electrode 66b. The print width L of the migration resistance test print patterns 64a, 64b is 200 ⁇ m, and the space S between the migration resistance test print patterns 64a, 64b is 200 ⁇ m.
• printed patterns 64a, 64b and electrodes 66a, 66b for conductive paste migration resistance testing screen printing was performed using a 400 mesh screen made of stainless steel (emulsion thickness 10 ⁇ m).
• the printed patterns 64a, 64b for the migration resistance test of the conductive paste and the electrodes 66a, 66b were dried at 150° C. for 10 minutes using a batch type hot air dryer.
• the migration resistance test printed patterns 64a, 64b and electrodes 66a, 66b were fired using a belt-type firing furnace. . The firing temperature was maintained at 850°C for 10 minutes.
• test pieces 60 for the migration resistance test of Examples 1 to 16 and Comparative Examples 1 to 5 were prepared.
• Test pieces 60 for the migration resistance test of Examples 17 to 19 were produced in the following procedure. First, in the same way as the test piece 60 of Examples 1 and 3 and Comparative Example 1, a diagram was printed by screen printing on a 110 mm x 20 mm x 0.8 mm (t) alumina substrate 62 (purity 96%) for migration resistance testing. As shown in FIGS. 3 and 4, the conductive paste was applied so that the two comb-shaped migration resistance test printed patterns 64a and 64b were alternated. Next, the conductive paste was heat-treated at 200° C. for 30 minutes using a hot air dryer to harden the adhesive strength test pattern of the conductive paste. In the manner described above, test pieces for the migration resistance tests of Examples 17 to 19 were prepared.
• the migration resistance of the printed patterns 64a and 64b for the migration resistance test of the test piece 60 of Examples 1, 3, and 17 to 19 and Comparative Example 1 was measured according to the following procedure. First, as shown in FIG. 3, a voltage (40 V) was applied between the first electrode 66a and the second electrode 66b of the two migration resistance test printed patterns 64a and 64b. The insulation resistance value between the first electrode 66a and the second electrode 66b was measured while stored in an environment with a temperature of 85° C. and a humidity of 85%. The insulation resistance value was calculated from the measured value of the current flowing between the first electrode 66a and the second electrode 66b and the applied voltage of 40V.
• test piece 60 to which an applied voltage of 40 V was applied was held in an environment of a temperature of 85° C. and a humidity of 85% for a maximum of 487 hours.
• Table 9 shows the results of the migration resistance test. Before the test, the insulation resistance values of all samples were 10 7 ⁇ or more. A test piece 60 whose insulation resistance value became 10 6 ⁇ or less within 10 hours was judged to be defective, and was written as "defective" in Table 9. Test piece 60, whose insulation resistance value did not fall below 10 6 ⁇ even after 80 hours, was determined to have a certain degree of migration resistance and could be used for some purposes, and was marked as "usable” in Table 9. It was written as. Test piece 60 whose insulation resistance value did not fall below 10 6 ⁇ even after 487 hours was judged to have excellent migration resistance and was listed as "good” in Table 9.
• FIG. 7 shows changes over time in the insulation resistance values of Example 1, Example 3, and Comparative Example 1 when an anti-migration test was conducted.
• Test piece 60 of Example 3 which was judged to have excellent migration resistance (described as "good” in Table 9), did not have an insulation resistance value of 10 6 ⁇ or less even after 480 hours.
• Test piece 60 of Example 1 (described as "usable” in Table 9), which was determined to be usable for some applications due to its excellent migration resistance, had an insulation resistance value of 10 even after 80 hours. It did not go below 6 ⁇ .
• Test piece 60 of Comparative Example 1, which was determined to have poor migration resistance (described as "defective” in Table 9), had an insulation resistance value of 10 6 ⁇ or less within 10 hours.
• solder heat resistance test Using the prepared conductive paste, test pieces for the soldering heat resistance test of Examples 1 to 16 and Comparative Examples 1 to 5 containing (C) glass frit were prepared according to the following procedure.
• a conductive paste was applied by screen printing onto a 20 mm x 20 mm x 1 mm (t) alumina substrate (purity 96%).
• 25 (5 ⁇ 5) adhesive strength test patterns each having a square pad shape of 1.5 mm on a side were formed on the alumina substrate.
• screen printing was performed using a stainless steel 325 mesh screen (emulsion thickness: 5 ⁇ m).
• the conductive paste was dried at 150° C. for 10 minutes using a batch hot air dryer. After drying the pattern for testing the adhesive strength of the conductive paste, the pattern for testing the adhesive strength of the conductive paste was fired using a belt-type firing furnace. The firing temperature was maintained at 850°C for 10 minutes. The total time from putting it in the kiln to taking it out was 60 minutes. In the manner described above, test pieces of Examples 1 to 16 and Comparative Examples 1 to 5 were prepared.
• soldering heat resistance tests of Examples 17 to 19 were carried out using conductive paste not containing (C) glass frit. A test piece was prepared for this purpose. However, in the case of the test pieces of Examples 17 to 19, instead of drying and baking the adhesive strength test pattern of the conductive paste, a hot air dryer was used to dry the conductive paste at 150°C for 10 minutes. The adhesive strength test pattern of the conductive paste was cured by heat treatment.
• solder bath solder temperature: 260°C
• solder M705 manufactured by Senju Metal Industry Co., Ltd., a Sn alloy containing 3.0% by weight of Sn-Ag and 0.5% by weight of Cu
• the pieces were immersed for 10 seconds.
• soldering heat resistance test After immersing the test piece in the solder bath, the test piece was taken out, and if 95% or more of the electrode remained on the test piece, it was judged as having passed the soldering heat resistance test.
• soldering heat resistance column of Table 9, "good” was written when the soldering heat resistance test was passed, and “poor” was written when the soldering heat resistance test was failed.
• Figure 5 shows the surface of a test piece prepared under the same conditions as test piece 50 of the sulfidation resistance test of Example 3, in which the rate of change in resistance value was relatively small, using a scanning electron microscope (SEM) at a magnification of 5000 times. This shows an SEM photograph taken by.
• FIG. 6 shows an SEM photograph taken at a magnification of 5000 times of the surface of a test piece prepared under the same conditions as test piece 50 of the sulfidation resistance test of Comparative Example 1 in which the rate of change in resistance value was large. Note that, as in the case of the sulfidation resistance test, the test piece was stored in a sulfur atmosphere (60° C.) for 150 hours, and then subjected to SEM observation.
• SEM scanning electron microscope
• the tensile adhesive strength of the adhesive strength test patterns obtained by firing the conductive pastes of Examples 1 to 19 was 13.2 N (Example 17) to 17 N. .8N (Examples 11 and 15), and a high tensile adhesive strength could be obtained.
• the tensile adhesive strength of the electrode patterns obtained by firing the conductive pastes of Comparative Examples 1 to 4 was in the range of 14.2 N (Comparative Example 4) to 15.2 N (Comparative Examples 1 to 3), The tensile adhesive strength was within a acceptable range.
• the tensile adhesive strength of the electrode pattern obtained by firing the conductive paste of Comparative Example 5 was 7.1N. It is considered that the conductive paste of Comparative Example 5 had a lower tensile adhesive strength because it had poor sinterability compared to other Examples and Comparative Examples.
• Example 3 Comparing the SEM photographs of Example 3 shown in FIG. 5 and Comparative Example 1 shown in FIG. 6, it can be seen that the crystals of silver sulfide 20 are formed larger due to sulfidation in Comparative Example 1 than in Example 3. . Similar trends were observed for other Examples and Comparative Examples. Therefore, it can be said that the electrode of the example of this embodiment has higher sulfidation resistance than that of the comparative example. Furthermore, when the Pd content in the depth direction of the sample of Example 3 was measured by X-ray photoelectron spectroscopy (XPS), it was found that there was a portion with a Pd content of about 30 at.% at a depth of 80 nm. confirmed. This suggests that at least in the sample of Example 3, the sulfidation resistance of the electrode was improved by forming a silver-palladium alloy layer on the surface of the electrode.
• XPS X-ray photoelectron spectroscopy
• Test piece for sulfidation resistance test 52 Alumina substrate for sulfidation resistance test 54 Printed pattern for sulfidation resistance test 54a, 54b Edges of printed pattern for sulfidation resistance test 60
• Test piece for migration resistance test 62 Alumina for migration resistance test Substrate 64a, 64b Printed pattern for migration resistance test 66a First electrode 66b Second electrode 100 Chip resistor 102 Alumina substrate 104 Resistor 106 Takeout electrode 108 Bottom electrode 110 Connection electrode 112 Nickel plating film 114 Tin plating film

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