Conductive paste

Abstract

This conductive paste contains: a conductive powder containing copper as the main ingredient; a glass frit; a binder resin; and an organic solvent. The glass frit contains substantially no elemental Zn, and contains, in mass% in terms of the oxides, 40.0-65.0 BaO, 15.0-23.0% B2O3, 2.0-12.0% Al2O3, 4.0-8.0% SiO2, 3.0-7.5% CaO, 2.5-5.0% MnO2, and 10.0-14.0% CuO. The total content of MnO2 and CuO contained in the glass frit is 12.5-17.5%, and the mass ratio of CuO contained in the glass frit with respect to MnO2 contained in the glass frit is 2.0-4.0. The use of this conductive paste makes it possible to manufacture an electronic component that is provided with a highly dense terminal electrode and that has excellent flexural strength.

Description

conductive paste

[0001] This invention relates to a conductive paste using a conductive powder mainly composed of copper. In particular, it relates to a conductive paste for forming terminal electrodes of multilayer ceramic electronic components such as multilayer ceramic capacitors, multilayer inductors, multilayer piezoelectric actuators, and multilayer thermistors.

[0002] Multilayer ceramic electronic components such as multilayer ceramic capacitors, multilayer inductors, multilayer piezoelectric actuators, and multilayer thermistors (hereinafter sometimes simply referred to as "electronic components") are generally manufactured as follows.

[0003] First, a conductive paste for internal electrodes is printed in a predetermined pattern onto a dielectric ceramic green sheet, such as a barium titanate ceramic. Then, multiple sheets of this paste are stacked and pressed together to obtain an unfired laminate in which ceramic green sheets and internal electrode paste layers are alternately stacked. The obtained laminate is cut into a rectangular parallelepiped shape and fired to obtain a laminated base body. Subsequently, a conductive paste for terminal electrodes, consisting of conductive powder, binder resin, organic solvent, glass frit, etc., is printed onto the exposed ends of the internal electrodes of the laminated base body by dip printing or the like to form a conductive paste layer. After drying as necessary, it is further fired at a high temperature to form the terminal electrodes.

[0004] Furthermore, a plating layer of nickel, tin, or other materials may be formed on the terminal electrodes by electroplating or other methods, as needed.

[0005] As mentioned above, in some cases a conductive paste layer is formed on the ends of a laminated body obtained by firing a rectangular parallelepiped-shaped laminate and then fired again, while in other cases a conductive paste layer is formed on the ends of an unfired rectangular parallelepiped-shaped laminate and these are fired simultaneously. In this specification, in either case, the structure excluding the terminal electrodes is referred to as a "rectangular parallelepiped-shaped laminate" before firing and as a "laminated body" after firing.

[0006] Traditionally, precious metals such as palladium, silver-palladium, and platinum were used as internal electrode materials. However, due to demands for resource conservation and cost reduction, and especially in sintered types, there are requirements to prevent delamination and cracking caused by oxidative expansion during sintering of palladium and silver-palladium. For this reason, in recent years, base metals such as nickel, cobalt, and copper have become the mainstream choice. Consequently, copper, nickel, cobalt, or alloys thereof, which readily form good electrical connections with base metal internal electrodes, are now being used as terminal electrode materials instead of the conventional silver and silver-palladium.

[0007] When base metals are used for the internal electrodes and terminal electrodes in this manner, the firing of the terminal electrodes is usually carried out in a non-oxidizing atmosphere with the lowest possible oxygen partial pressure, for example, in an inert gas atmosphere with an oxygen content of several ppm to several tens of ppm, at a temperature of, for example, 700°C to 900°C, so that these base metals are not oxidized during firing.

[0008] Furthermore, when electroplating terminal electrodes formed using a conductive paste containing glass frit, the glass component may be altered or dissolved by the acidic electroplating solution, destroying the glass structure and significantly reducing the adhesive strength between the terminal electrode film and the ceramic body. Therefore, terminal electrodes are required to exhibit excellent acid resistance (plating solution resistance) and to be dense, preventing problems such as reduced adhesive strength or peeling due to penetration of the plating solution. To meet these requirements, for example, Patent Document 1 describes a conductive paste containing conductive powder, glass frit, and an organic vehicle, wherein the conductive powder is mainly composed of copper and / or nickel, the glass frit is substantially free of Pb, Cd, and Bi, and contains BaO 40-65% and B in terms of mass percent on an oxide basis. ２ O ３ 15-23%, Al ２ O ３ 2-12%, SiO ２ 4-8%, ZnO 0-5%, TiO ２ It contains 0.5-7% of [unclear], 3-7.5% of CaO, and MnO ２ , one or more of CuO and CoO, MnO２ It is characterized by containing in the range of 0 to 7% of [substance not specified], 0 to 16% of CuO, and 0 to 5% of CoO, and a conductive paste is disclosed.

[0009] International Publication No. WO2017 / 057246

[0010] In recent years, due to the high functionality of mobile terminals such as smartphones and the spread of electric vehicles, the demand for electronic components has been increasing steadily. The shipment value of passive components has increased by more than 50% in the past 10 years, and there is a demand for further expanding the production volume of multilayer ceramic electronic components manufactured using conductive paste. However, when the inventors tried to mass-produce electronic components using the conductive paste within the range disclosed in Patent Document 1, a problem occurred in that the frequency of maintenance required for the production equipment increased. Also, when investigating, studying, and attempting to solve the cause, a new problem occurred in that the incidence rate of electronic components with insufficient flexural strength increased.

[0011] Therefore, an object of the present invention is to provide a conductive paste that can mass-produce more electronic components than before, which have highly dense terminal electrodes and excellent flexural strength.

[0012] The present invention for solving the above problems relates to the conductive paste described below. (1) A conductive paste containing conductive powder mainly composed of copper, glass frit, binder resin, and organic solvent, wherein the glass frit substantially does not contain Zn element, the Ba element is 40.0 mass% or more and 65.0 mass% or less in terms of BaO, the B element is 15.0 mass% or more and 23.0 mass% or less in terms of B ２ O ３ in terms of conversion, the Al element is 2.0 mass% or more and 12.0 mass% or less in terms of Al ２ O ３ in terms of conversion, the Si element is 4.0 mass% or more and 8.0 mass% or less in terms of SiO ２ in terms of conversion, the Ca element is 3.0 mass% or more and 7.5 mass% or less in terms of CaO, and the Mn element is in terms of MnO ２The glass frit contains 2.5% to 5.0% by mass in terms of equivalent weight, and Cu element in terms of 10.0% to 14.0% by mass in terms of equivalent weight of CuO, and the total content of Mn element and Cu element in terms of oxides (MnO ２ The amount of CuO in the glass frit is 12.5% ​​by mass or more and 17.5% by mass or less, and the mass ratio of the Cu element in the glass frit in terms of oxides to the Mn element in the glass frit is (CuO / MnO ２ A conductive paste characterized in that the ratio is 2.0 or more and 4.0 or less. (2) The conductive paste according to (1) above, characterized in that, by thermogravimetric analysis, when 20 mg of the glass frit is heated from room temperature to 1000°C at a heating rate of 20°C / min in an atmospheric environment, the absolute value ΔTG of the difference between the lowest value [%] of the weight loss rate in the range of 100°C to 800°C and the highest value [%] of the weight loss rate in the range of the temperature above the lowest value and 800°C is 0.62% or less. (3) The conductive paste according to (1) or (2) above, characterized in that when the glass constituting the compact is melted by heating the compact in a nitrogen atmosphere at a rate of 10°C / min to 750°C, the contact angle of the glass with respect to the copper plate is 60° or less, the dry film density of the conductive paste is 4.1 g / cm³, the dry film density of the conductive paste is 4.1 g / cm³, the dry film density of the conductive paste is 4.1 g / cm³, the dry film density of the conductive paste is 4.1 g / cm³. ３ 4.7g / cm or more ３ A conductive paste according to any one of the above items (1) to (3), characterized in that: (5) The tap density of the conductive powder mainly composed of copper is 3.0 g / cm³ ３ 5.0g / cm or more ３ A conductive paste according to any one of the above items (1) to (4), characterized in that: (6) the tap density of the glass frit is 1.0 g / cm³ ３ 1.5g / cm or more ３A conductive paste according to any one of the above items (1) to (5), characterized in that: (7) The conductive paste according to any one of the above items (1) to (6), characterized in that the volume-based cumulative 50% particle size D50 in the laser diffraction particle size distribution measurement of the glass frit is 0.3 μm or more and 3.0 μm or less.

[0013] According to the present invention, it is possible to provide a conductive paste that enables the mass production of electronic components equipped with highly dense terminal electrodes and excellent flexural strength, even more so than in the past.

[0014] Figure 1 shows the internal structure of a multilayer ceramic capacitor 10, which is an example of an electronic component, when mounted on a circuit board.

[0015] The conductive paste according to the present invention contains conductive powder, glass frit, binder resin, and an organic solvent. The conductive powder, glass frit, binder resin, and organic solvent, which constitute the conductive paste according to the present invention, will be described in detail below.

[0016] <Conductive Powder> The conductive powder in this invention may be mainly composed of copper, but it is preferable that the copper content in the conductive powder be 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, and particularly preferably 100% by mass (pure copper). Since the glass frit in this invention contains a predetermined amount of Cu oxide (Cu element), when the copper content in the conductive powder is in the range of 80% by mass or more and 100% by mass or less, the wettability of the glass to the conductive powder in this invention is improved, the glass spreads appropriately in the film during firing, and oxygen can be supplied more uniformly to the ceramic in the coating film and near the interface between the coating film and the laminated body. As a result, it becomes easier to obtain electronic components that have highly dense terminal electrodes and excellent bending strength.

[0017] The conductive powder in this invention may be a mixed powder of copper powder and other elemental metal powders such as nickel powder or silver powder, or an alloy powder of copper and other elemental metals such as nickel or silver. Furthermore, it may be a composite powder in which copper powder is coated with glass or ceramic, or it may have an oxide film on its surface. Furthermore, it may be surface-treated with organometallic compounds or surfactants, and two or more of these conductive powders may be mixed and used.

[0018] In this specification (the present invention), "main component" means that the component makes up more than 50% by mass of the whole, and in particular, in the case of conductive powder having copper as the main component, it means that the copper component makes up more than 50% by mass of the total conductive powder contained in the conductive paste of the present invention, which includes the aforementioned mixed powder and alloy powder.

[0019] The tap density of the copper-based conductive powder in this invention is 3.0 g / cm³. ３ 5.0g / cm or more ３ Preferably, it is 3.3 g / cm³. ３ 4.7g / cm or more ３ It is more preferable that the following conditions be met: 3.6 g / cm³ ３ 4.4g / cm or more ３ It is even more preferable that the following conditions be met: 3.9 g / cm³ ３ 4.1g / cm or more ３ The following is particularly preferable:

[0020] The tap density of the conductive powder, which mainly consists of copper, is 3.0 g / cm³. ３ 5.0g / cm or more ３ By being within the following range, shrinkage of the conductive paste during firing can be suppressed, thereby suppressing stress on the laminated body and enabling the manufacture of electronic components with even greater bending strength. Note that the higher the tap density of the copper-based conductive powder, the more difficult it becomes to secure a removal pathway for organic matter in the film during firing, making it harder to remove the organic matter and increasing the likelihood of carbon residue. However, the glass frit in this invention is suitably effective in removing organic matter, thus reducing carbon residue even when the tap density of the conductive powder is high.

[0021] In other words, by using the glass frit in the present invention and setting the tap density of the conductive powder, which mainly consists of copper, within the range described above, it becomes particularly easy to obtain electronic components that have highly dense terminal electrodes and excellent bending strength. The above tap density can be determined, for example, by weighing 20 g of copper powder using a tap density measuring device (KYT-4000, manufactured by Seishin Corporation) and measuring it over 20 cm. ３ Place the sample in the cell, set the tapping stroke to 20 mm, and the number of taps to 200, then measure the sample volume (cm³) after tapping. ３ It can be calculated as the ratio of the sample weight (g) to the given value.

[0022] In the present invention, the volume-based cumulative 50% particle size D50 of the copper-based conductive powder in laser diffraction particle size distribution measurement is preferably 0.3 μm to 4.5 μm, more preferably 0.4 μm to 4.0 μm, even more preferably 0.5 μm to 3.5 μm, and particularly preferably 0.6 μm to 3.5 μm. Having the D50 of the copper-based conductive powder within the above range of 0.3 μm to 4.5 μm facilitates the sintering of the conductive powder, making it easier to form dense terminal electrodes. While the easier the sintering of the conductive powder, the narrower the organic matter removal pathway at lower temperatures, making carbon residue more likely, the glass frit in the present invention is suitable for removing organic matter, thus reducing carbon residue even when the conductive powder particle size is small and sintering is easily achieved.

[0023] In the present invention, the ratio of the average major axis to the average minor axis of the copper-based conductive powder is preferably 1.5 or more and 8.0 or less, more preferably 2.0 or more and 6.0 or less, more preferably 2.5 or more and 5.0 or less, and particularly preferably 2.5 or more and 4.5 or less. By having the ratio of the average major axis to the average minor axis of the copper-based conductive powder within the above range of 1.5 or more and 8.0 or less, shrinkage of the conductive paste during firing can be suppressed, thereby suppressing stress on the laminated body and making it easier to manufacture electronic components with even better bending strength.

[0024] The average major axis mentioned above can be measured using a scanning electron microscope. Specifically, 100 conductive particles can be randomly selected by scanning electron microscopy observation, and the average length of the long side of the major axis circumscribing each particle, with the area minimized, can be measured as the average major axis. The average minor axis mentioned above can be measured by scanning electron microscopy observation of a cross-section of a dried film formed using the conductive paste of the present invention. More specifically, the conductive paste of the present invention can be cast onto a PET film using an applicator to form a coating film with a thickness of 250 μm, and this coating film can be dried in an air atmosphere at 150°C for 10 minutes to form a dried film. The cross-section of the dried film can be exposed using an ion milling device (e.g., IM4000 manufactured by Hitachi High-Tech Corporation), and the cross-section of the dried film can be observed with a scanning electron microscope (e.g., SU-8020 manufactured by Hitachi High-Tech Corporation). From this observation, 100 conductive particles can be randomly selected, and the average length of the short side of the rectangle circumscribing the conductive particles can be measured as the average minor axis.

[0025] The method for producing the copper-based conductive powder in the present invention is not particularly limited, and spherical conductive powder can be produced by, for example, spray pyrolysis, physical vapor phase method, chemical vapor phase method, liquid phase reduction method, atomization method, etc.

[0026] <Glass Frit> The glass frit in this invention is substantially free of Zn, contains 40.0% to 65.0% by mass of Ba element in terms of BaO, and contains B element. ２ O ３ Converted to 15.0% by mass or more and 23.0% by mass or less, Al element ２ O ３ Converted to 2.0% to 12.0% by mass, Si element is SiO ２ Converted to 4.0% to 8.0% by mass, Ca element to 3.0% to 7.5% by mass in CaO equivalent, Mn element to MnO ２ It contains 2.5% by mass or more and 5.0% by mass or less in terms of conversion, and Cu element in terms of 10.0% by mass or more and 14.0% by mass or less in terms of CuO conversion. In addition, the total content of Mn element and Cu element in terms of oxide conversion contained in the glass frit (MnO ２The amount of CuO in the glass frit is 12.5% ​​by mass or more and 17.5% by mass or less, and the mass ratio of the Cu element in the glass frit in terms of oxides to the Mn element in the glass frit is (CuO / MnO ２ ) is between 2.0 and 4.0.

[0027] The reason for the above composition of the glass frit in this invention is explained below. According to the inventors' studies, in glass frits within the range of glass compositions described in Patent Document 1 (hereinafter referred to as "prior compositions"), glass formation becomes easier when a small amount of ZnO of a few percent is added, making the production of glass frit easier. However, on the other hand, when glass frit containing a small amount of ZnO in the prior compositions is blended into a conductive paste and fired in a non-oxidizing atmosphere, the Zn component contained in the glass component leaches out and gradually accumulates in the manufacturing equipment as a deposit containing Zn element. This problem became particularly pronounced when attempting to mass-produce the product, and the deposit containing Zn element in the manufacturing equipment had to be removed frequently to prevent blockage inside the equipment, leading to an increased maintenance frequency.

[0028] Therefore, in order to solve this problem, we attempted to mass-produce multilayer ceramic electronic components using a conductive paste with glass frit that does not contain Zn in the prior composition. However, the rate of electronic components with insufficient bending strength increased compared to before. The reason for this is not clear, but since the above problem tends to occur in large-scale manufacturing equipment suitable for mass production, the inventors speculate that when the conductive paste using glass frit that does not contain Zn in the prior composition undergoes the binder removal process, the difficulty in controlling a uniform / homogeneous atmosphere due to the large size of the manufacturing equipment, combined with the fact that some carbon components remain in the conductive paste. In the subsequent firing process at high temperatures in a non-oxidizing atmosphere, the residual carbon that could not be completely removed deprives oxygen from the ceramic in the multilayer body, resulting in a decrease in the bending strength of the electronic components.

[0029] Therefore, the inventors first considered introducing oxygen into the firing furnace in the manufacturing equipment. However, when the aforementioned phenomenon occurs, it occurs locally near the interface between the laminated body and the terminal electrode. For this reason, the inventors speculated that this method of supplying oxygen from the outside would be difficult to solve because the terminal electrode (or the conductive paste film or the film produced during its firing process) would act as a barrier, preventing a sufficient amount of oxygen from being supplied to the oxygen-deficient areas.

[0030] Figure 1 shows the internal structure of a multilayer ceramic capacitor 10 as an example of an electronic component when mounted on a substrate. The multilayer ceramic capacitor 10 includes a laminated body 1 having opposing end faces and sides connecting these end faces. The laminated body 1 is composed of a plurality of internal electrode layers 2 and a ceramic layer 3. The plurality of internal electrode layers 2 overlap and face each other inside the laminated body 1 and are led out to alternately opposing end faces. Terminal electrodes 4 are formed on both end faces of the laminated body 1.

[0031] As shown in Figure 1, when the substrate 6 on which the multilayer ceramic capacitor 10 (electronic component) is mounted flexes, the greatest stress is applied near the edge of the part where the terminal electrode 4 wraps around the substrate 6, and cracks often occur in the multilayer body starting from this point of greatest stress (stress concentration point 5). Since this stress concentration point 5 is covered by the terminal electrode 4, the oxygen deficiency cannot be resolved by supplying oxygen from the outside as described above.

[0032] Therefore, the inventors considered the opposite: by utilizing the fact that the conductive paste is in contact with the laminated body (especially the stress concentration areas), they thought that oxygen could be efficiently supplied to the vicinity of the aforementioned interface where localized oxygen deficiency occurs by supplying oxygen from the glass frit contained in the conductive paste.

[0033] As a result of various studies on glass composition conducted by the inventors, they found that by using a conductive paste containing the aforementioned glass frit, which substantially does not contain Zn elements in the prior composition and contains a balanced and sufficient amount of Mn oxide (Mn element) and Cu oxide (Cu element), they were able to mass-produce electronic components with highly dense terminal electrodes and excellent flexural strength even more than before.

[0034] The glass frit contains a sufficient amount of Cu oxide (Cu element), which improves the wettability between the glass and the copper-based conductive powder, allowing the glass to spread appropriately within the film during firing. In addition, the glass frit contains a balanced and sufficient amount of Mn oxide (Mn element) and Cu oxide (Cu element), which have different oxygen release temperatures, allowing for a sufficient supply of oxygen from the glass over a wide temperature range. The inventors speculate that this eliminates the aforementioned localized oxygen deficiency, thereby achieving the effects of the present invention.

[0035] By using this conductive paste containing glass frit, electronic components with highly dense terminal electrodes and excellent flexural strength can be mass-produced even more than before. Note that "substantially absent" does not mean completely absent; it may contain Zn in an oxide equivalent of 1000 ppm or less, as long as it does not impair the effects of the present invention. When Zn is present in the glass frit, it is present in the form of an oxide such as ZnO. Furthermore, the glass frit in the conductive paste of the present invention may contain Zn in an oxide equivalent of 1000 ppm or less. The above Zn content is the content when converted to ZnO.

[0036] The glass frit in this invention is substantially free of ZnO. This suppresses the accumulation of Zn-containing deposits in the electronic component manufacturing equipment, allowing for the production of electronic components in much larger quantities than before without increasing the frequency of maintenance.

[0037] The glass frit in this invention is made of Mn O ２ It contains 2.5% to 5.0% by mass in terms of equivalent composition, and Cu in terms of CuO, ranging from 10.0% to 14.0% by mass. In addition, the total content of Mn and Cu in terms of oxides (MnO ２ The amount of CuO is 12.5% ​​by mass or more and 17.5% by mass or less, and the mass ratio of Cu element to Mn element in terms of oxide (CuO / MnO ２The ratio is between 2.0 and 4.0. The respective content and ratio of Mn and Cu elements in terms of oxides, as well as the total content, are within the above range. When firing the conductive paste applied to the laminated body, a sufficient amount of oxygen can be supplied to the ceramic within the coating film and near the interface between the coating film and the laminated body over a wide temperature range during firing. Therefore, even when firing the conductive paste in a non-oxidizing atmosphere, the reduction in residual carbon not only increases the density of the terminal electrodes but also increases the bending strength of the electronic components.

[0038] Mn O ２ The converted content should be 2.5% by mass or more and 5.0% by mass or less, but preferably 2.5% by mass or more and 4.0% by mass or less. Mn element MnO ２ The fact that the converted content falls within this range allows for a sufficient supply of oxygen even at relatively low temperatures such as 700°C. ２ When the converted content exceeds 5.0% by mass, the viscous behavior of the glass at high temperatures tends to become unstable.

[0039] The Cu content, in terms of CuO, should be between 10.0% by mass and 14.0% by mass, preferably between 10.0% by mass and 13.0% by mass, and particularly preferably between 10.0% by mass and 12.0% by mass. Having the Cu content, in terms of CuO, within the above range of 10.0% by mass and 14.0% by mass improves the wettability of the glass to the copper-based conductive powder in this invention. During firing, the glass spreads appropriately within the film, allowing for a more uniform supply of oxygen to the ceramic within the coating and near the interface between the coating and the laminated body. This makes it easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength. Furthermore, having the Cu content, in terms of CuO, within the above range allows for a sufficient supply of oxygen even at higher temperatures such as 800°C. Note that if the Cu content, in terms of CuO, exceeds 14.0% by mass, the glass tends to crystallize more easily, resulting in uneven dispersion of the conductive powder.

[0040] In terms of making glass easier to form, the total content of Mn and Cu elements in terms of oxides (MnO ２ The upper limit of +CuO) should be 17.5% by mass, but it is preferable that the upper limit be 17.0% by mass. In terms of the total amount of oxygen that can be supplied, the total content of Mn and Cu elements in terms of oxides (MnO ２ The lower limit of (+CuO) should be 12.5 mass%.

[0041] In terms of supplying oxygen over a wide temperature range, the mass ratio of Cu to Mn in terms of oxides (CuO / MnO) ２ The ratio should be between 2.0 and 4.0. From the perspective of increasing oxygen supply in a relatively low temperature range such as 700°C, the mass ratio of Cu element to Mn element in terms of oxide (CuO / MnO) ２ The ratio is preferably 2.0 to 3.5, more preferably 2.0 to 3.0, and particularly preferably 2.0 to 2.5. From the viewpoint of increasing the oxygen supply in higher temperature ranges such as 800°C, the mass ratio of Cu element to Mn element in terms of oxide (CuO / MnO ２ The value of ) is preferably 2.5 or more and 4.0 or less, more preferably 3.0 or more and 4.0 or less, and particularly preferably 3.5 or more and 4.0 or less.

[0042] SiO ２ and B ２ O ３ It acts as a glass-forming component. The glass frit in this invention is composed of Si element and SiO ２ Converted to 4.0% by mass or more and 8.0% by mass or less, element B is B ２ O ３ It contains in an amount of 15.0% to 23.0% by mass, calculated as SiO. ２ If the Si content of the converted glass falls below this range, the acid resistance of the glass decreases, and if it exceeds this range, the viscosity increases, making it difficult to sinter. Also, B ２ O ３ If the content of element B in the conversion falls below this range, glass formation becomes difficult; if it exceeds this range, acid resistance and water resistance deteriorate, and resistance to plating solutions decreases. SiO ２The preferred range for the Si element content in the conversion is 4.0% by mass or more and 7.0% by mass or less. ２ O ３ The preferred range for the content of element B in the conversion is 15.0% by mass or more and 21.0% by mass or less.

[0043] Al ２ O ３ It acts as a component that improves acid resistance while assisting in glass formation. The glass frit in this invention is made of Al element. ２ O ３ Contains in an amount of 2.0% by mass or more and 12.0% by mass or less. ２ O ３ If the Al content of the converted glass falls below this range, the acid resistance of the glass decreases; if it exceeds this range, the glass becomes more prone to crystallization. ２ O ３ The preferred range for the converted Al element content is 6.0% by mass or more and 12.0% by mass or less.

[0044] BaO acts as a component that lowers the softening point of glass and increases wettability with conductive powder by reducing viscosity. The glass frit in this invention contains Ba element in a range of 40.0% to 65.0% by mass in terms of BaO. If the Ba element content in terms of BaO is below this range, the softening point will rise and wettability with conductive powder will decrease, and if it is above this range, glass formation will be inhibited. The preferred range for the Ba element content in terms of BaO is 42.0% to 60.0% by mass.

[0045] CaO acts as a component that controls the viscosity of glass. The glass frit in this invention contains Ca element in a range of 3.0% to 7.5% by mass in terms of CaO. If the Ca element content in terms of CaO falls below this range, the viscosity of the glass tends to decrease, and if it exceeds this range, the viscosity of the glass increases, reducing the wettability with conductive powder. The preferred range for the Ca element content in terms of CaO is 3.0% to 6.0% by mass.

[0046] The glass frit in this invention may be further reduced to a small amount of other oxides, such as Na, to the extent that it does not affect the effects of the present invention. ２ O, K ２ O, Cs ２ O, Li２ O, MgO, SrO, NiO, CoO, CeO ２ , TiO ２ , ZrO ２ , La ２ O ３ , Fe ２ O ３ , Ga ２ O ３ , V ２ O ５ , Nb ２ O ５ , SnO or SnO ２ , Ta ２ O ５ , Pr ６ O １１ , Tb ４ O ７ , Ag ２ O, TeO ２ , P ２ O ５ etc. can be included.

[0047] The glass frit in the present invention preferably contains substantially no Pb element (i.e., in the range of 1000 mass ppm or less in terms of PbO).

[0048] The glass frit in the present invention preferably contains substantially no Cd element (i.e., in the range of 1000 mass ppm or less in terms of CdO).

[0049] The glass frit in the present invention preferably contains substantially no Bi element (i.e., in the range of 1000 mass ppm or less in terms of Bi ２ O ３ conversion).

[0050] The glass frit in the present invention preferably contains substantially no Mo element (i.e., in the range of 1000 mass ppm or less in terms of MoO ３ conversion).

[0051] The tap density of the glass frit in the present invention is preferably 1.0 g / cm ３ or more and 1.5 g / cm ３ or less, and particularly preferably 1.2 g / cm ３ or more and 1.3 g / cm ３ or less.

[0052] In the present invention, the volume-based cumulative 50% particle size D50 of the glass frit in laser diffraction particle size distribution measurement is preferably 0.3 μm to 3.0 μm, more preferably 0.3 μm to 2.5 μm, more preferably 0.3 μm to 2.0 μm, more preferably 0.3 μm to 1.9 μm, more preferably 0.5 μm to 1.8 μm, and particularly preferably 1.0 μm to 1.7 μm. Because the D50 of the glass frit is within the above range of 0.3 μm to 3.0 μm, the glass frit is distributed more uniformly inside the coating film before firing, so that oxygen can be supplied more uniformly to the ceramic inside the coating film and near the interface between the coating film and the laminated body during firing. Therefore, it becomes easier to obtain electronic components equipped with highly dense terminal electrodes and excellent flexural strength.

[0053] In the present invention, the glass transition temperature of the glass frit is preferably 450°C to 650°C, more preferably 450°C to 600°C, and particularly preferably 450°C to 550°C. This allows the glass to spread appropriately within the film during firing, and oxygen to be supplied more uniformly to the ceramic within the coating and near the interface between the coating and the laminated body. As a result, it becomes easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength. Furthermore, the above effects are easier to obtain even when the firing time is shortened, the heating rate is increased, or the firing temperature is lowered, thus improving mass productivity.

[0054] In the present invention, the softening point of the glass frit is preferably 550°C to 750°C, more preferably 550°C to 700°C, and particularly preferably 550°C to 650°C. This allows the glass to spread appropriately within the film during firing, and oxygen to be supplied more uniformly to the ceramic within the coating and near the interface between the coating and the laminated body. As a result, it becomes easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength. Furthermore, the above effects are easier to obtain even when the firing time is shortened, the heating rate is increased, or the firing temperature is lowered, thus improving mass productivity.

[0055] In the present invention, the glass frit is more preferably 0.62% or less, more preferably 0.57% or less, more preferably 0.52% or less, and more preferably 0.44% or less when 20 mg of the glass frit is heated from room temperature to 1000°C at a heating rate of 20°C / min in an atmospheric environment, and the absolute value ΔTG of the difference between the minimum weight loss rate [%] in the range of 100°C to 800°C and the maximum weight loss rate [%] in the range of temperature above the minimum value and below 800°C is determined by thermogravimetric analysis. The lower limit of ΔTG is not particularly limited, but is preferably 0% or more, more preferably 0.25% or more, more preferably 0.32% or more, and more preferably 0.37% or more. This improves the oxygen supply from the glass frit, making it easier to supply oxygen to the ceramic within the coating film and near the interface between the coating film and the laminated body. As a result, it becomes easier to obtain electronic components equipped with highly dense terminal electrodes and excellent flexural strength. Furthermore, the above effects are more easily obtained even when the firing time is shortened, the heating rate is increased, or the firing temperature is lowered, thus improving mass productivity. The reason why oxygen donation is improved when ΔTG is within the aforementioned range is as follows: When manufacturing glass frit, oxygen is absorbed from the atmosphere when the raw materials are melted at a high temperature and then rapidly cooled. The faster the cooling rate of this rapid cooling, the less oxygen is absorbed, resulting in a lower oxygen content in the manufactured glass frit. And the lower the oxygen content in the glass frit, the more oxygen is absorbed when the glass frit is heated in the atmosphere, resulting in a larger value for ΔTG. In other words, when comparing glass frits of the same composition, a larger ΔTG value indicates a lower oxygen content in the glass frit, resulting in lower oxygen donation. To put it another way, a smaller ΔTG value indicates a higher oxygen content in the glass frit, resulting in higher oxygen donation. The aforementioned cooling rate can be controlled by known means, such as adjusting the cooling method, the amount of cooling, the atmosphere during cooling, and the material and thickness of the part in contact with the molten glass.Cooling methods include, for example, cooling the molten glass in a furnace with a controlled temperature profile (furnace cooling), letting the molten glass flow onto a metal plate such as an iron plate and allow it to cool naturally (natural cooling), pressing the glass with another metal plate after letting it flow onto a metal plate such as an iron plate (press cooling), cooling the molten glass by letting it flow into water (water cooling), and letting the molten glass flow into the gap between two rotating rolls (twin-roll cooling).

[0056] In this invention, 40 mg to 60 mg of glass frit is placed in a cylindrical container with an inner diameter of 5 mm and pressure is applied axially at 40 MPa for 30 seconds to produce a cylindrical compact with a diameter of 5 mm and a height of 0.95 mm to 1.05 mm. The compact is then placed on a copper plate so that its flat surface is in contact with the copper plate, and the compact is heated in a nitrogen atmosphere at a heating rate of 10°C / min to 700°C to melt the glass constituting the compact. The contact angle of the glass with respect to the copper plate is preferably 80° or less, more preferably 77° or less, more preferably 75° or less, more preferably 73° or less, and particularly preferably 70° or less. The lower limit of the contact angle of the glass with respect to the copper plate is preferably 40° or more, more preferably 50° or more, and particularly preferably 60° or more. By having a contact angle of glass with the copper plate at 700°C between 40° and 80°, the glass spreads appropriately within the film during firing, allowing for a more uniform supply of oxygen to the ceramic within the coating and near the interface between the coating and the laminated body. This makes it easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength. Furthermore, the above effects are more easily obtained even when the firing time is shortened, the heating rate is increased, or the firing temperature is lowered, thus improving mass production efficiency. As the copper plate, PREC Co., Ltd.'s copper plate C1020 (25 mm long, 25 mm wide, 0.3 mm thick) can be used. Before use, the surface on which the compacted material is placed on this copper plate can be reduced to remove the oxide film. The surface roughness Ra of the surface on which the compacted material is placed on this copper plate can be 100 nm to 200 nm, or 150 nm to 170 nm.

[0057] In this invention, 40 mg to 60 mg of glass frit is placed in a cylindrical container with an inner diameter of 5 mm and pressure is applied axially at 40 MPa for 30 seconds to produce a cylindrical compact with a diameter of 5 mm and a height of 0.95 mm to 1.05 mm. The compact is then placed on a copper plate so that its flat surface is in contact with the copper plate, and the compact is heated in a nitrogen atmosphere at a heating rate of 10°C / min to 750°C to melt the glass constituting the compact. The contact angle of the glass with respect to the copper plate is preferably 60° or less, more preferably 57° or less, even more preferably 55° or less, and particularly preferably 53° or less. The lower limit of the contact angle of the glass with respect to the copper plate is preferably 20° or more, more preferably 30° or more, and particularly preferably 40° or more. When the contact angle of the glass with respect to the copper plate at 750°C is in the range of 20° to 60°, the glass spreads appropriately within the film during firing, allowing for a more uniform supply of oxygen to the ceramic within the coating and near the interface between the coating and the laminated body. As a result, it becomes easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength. Furthermore, the above effects are more easily obtained even when the firing time is shortened, the heating rate is increased, or the firing temperature is lowered, thus improving mass production efficiency.

[0058] Furthermore, it is preferable that at least one of the following conditions is met: the contact angle of the glass with respect to the copper plate at 700°C is in the range of 40° to 80°, and the contact angle of the glass with respect to the copper plate at 750°C is in the range of 20° to 60°. It is particularly preferable that both conditions are met.

[0059] The amount of glass frit in this invention is preferably 5 to 15 parts by mass, and particularly preferably 6 to 13 parts by mass, per 100 parts by mass of conductive powder. Having the amount of glass frit within this range makes it easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength.

[0060] In addition to general methods such as mixing, melting, rapidly cooling, and pulverizing the raw material compounds of each component, the glass frit in this invention can be manufactured using methods such as the sol-gel method, spray pyrolysis method, and atomization method.

[0061] <Binder Resin> The binder resin in this invention is not particularly limited, but it is preferable that it contains an acrylic resin. The ratio of acrylic resin to the total binder resin is preferably more than 50% by mass, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. When an acrylic resin is used, it exhibits excellent thermal decomposition properties in a non-oxidizing atmosphere, so the binder resin can be removed well without oxidizing the copper.

[0062] The amount of binder resin in the present invention is preferably 3 to 11 parts by mass, more preferably 4 to 10 parts by mass, even more preferably 5 to 9 parts by mass, and particularly preferably 6 to 8 parts by mass, per 100 parts by mass of conductive powder. By having the amount of binder resin within the above range, it becomes easier to obtain electronic components that have highly dense terminal electrodes and excellent flexural strength.

[0063] The weight-average molecular weight of the binder resin in this invention is not particularly limited, but for example, one with a molecular weight of 20,000 or more and 1,000,000 or less can be used. Furthermore, two or more binder resins with different weight-average molecular weights and structures may be used in combination.

[0064] <Organic Solvents> The organic solvents used in the present invention are not particularly limited and include terpineol, dihydroterpineol, dihydroterpineol acetate, secondary butyl alcohol, butyl carbitol, butyl carbitol acetate, benzyl alcohol, and the like.

[0065] <Additives> The conductive paste of the present invention may contain additives other than the above components, as necessary, such as defoaming agents, plasticizers, dispersants, and rheology modifiers, as long as they do not impair the effects of the present invention.

[0066] <Conductive Paste> The conductive paste of the present invention is preferably used by applying the conductive paste to a laminated body or the like to form a coating film, drying the coating film as needed to form a dried film, and then firing it. The peak temperature for firing is not particularly limited, and firing can be performed at 650°C to 900°C. From the viewpoint of reducing thermal stress on the laminated body while forming dense terminal electrodes, it is preferably 700°C to 820°C, and particularly preferably 700°C to 800°C. Furthermore, from the viewpoint of suppressing oxidation of the conductive powder mainly composed of copper, it is preferable that the conductive paste of the present invention be fired in a non-oxidizing atmosphere.

[0067] The conductive paste of the present invention has a dry film density of 4.1 g / cm³. ３ 4.7g / cm or more ３ Preferably, it is 4.2 g / cm³. ３ 4.4g / cm or more ３ The following is particularly preferable: The dry film density is 4.1 g / cm³. ３ 4.7g / cm or more ３ By being within the following range, shrinkage of the conductive paste during firing can be suppressed, thereby reducing stress on the laminated body and enabling the manufacture of electronic components with even greater flexural strength.

[0068] Furthermore, the higher the dry film density of the conductive paste, the more difficult it becomes to secure a pathway for removing organic matter from the film during firing, making it harder to remove the organic matter and increasing the likelihood of carbon residue. However, the glass frit in this invention is suitably effective in removing organic matter, thus reducing the likelihood of carbon residue even at high dry film densities.

[0069] In other words, by using the glass frit according to the present invention and setting the dry film density within the above-mentioned range, it becomes particularly easy to obtain electronic components that have highly dense terminal electrodes and excellent bending strength.

[0070] The above dry film density (g / cm³) ３The present invention involves casting the conductive paste onto a PET film to a thickness of 250 μm to form a coating film, drying the coating film under the conditions of air atmosphere, 100°C, and 15 minutes, and then drying it under the conditions of air atmosphere, 150°C, and 15 minutes to form a dried film, cutting the obtained dried film into a circular shape with a diameter of 20 mm, measuring the weight and volume of the cut-out dried film, and determining the volume (cm³). ３ Dry film density (g / cm³) is expressed as the ratio of weight (g) to ) ３ Calculate the result.

[0071] The shear rate of the conductive paste of the present invention, measured at 25°C, is 4s. －１ The viscosity of the conductive paste is not particularly limited, but is preferably 10.0 Pa·s to 80.0 Pa·s, and particularly preferably 20.0 Pa·s to 60.0 Pa·s. Having a viscosity of 10.0 Pa·s to 80.0 Pa·s of the conductive paste results in good printability, allowing the conductive paste to be suitably applied to the edges of the laminated body. This makes it easier to form thin, highly continuous terminal electrodes, and also suppresses the stress on the edges of the laminated body when the conductive paste shrinks during firing, making it easier to obtain electronic components with excellent flexural strength.

[0072] The conductive paste of the present invention preferably has a deflection crack occurrence rate of 5% or less, as measured by the deflection crack occurrence rate measurement method described below. This makes it easier to obtain a conductive paste that can be used to manufacture multilayer ceramic electronic components with excellent deflection strength. (Method for measuring deflection crack occurrence rate) An electronic component is manufactured in which multiple layers of dielectric layers and internal electrode layers are laminated, and the laminated body has a rectangular parallelepiped shape with a length of 0.6 mm, a width of 0.3 mm, and a height of 0.3 mm, with terminal electrodes provided at both ends where the internal electrodes are exposed. As a method for forming the terminal electrodes, for example, the conductive paste according to the present invention is applied by dip printing with a descent speed of 300 μm / s and an uplift speed of 100 μm / s of the laminated body, then held in an air atmosphere at 150°C for 10 minutes, and then heated in a nitrogen atmosphere at a heating rate of 50°C / min until it reaches 780°C, and held for 15 minutes to form the electrodes, and then Ni plating and Sn plating are applied to the outer layer to form the terminal electrodes. Furthermore, a Ni plating layer can be formed on the surface of the terminal electrode by electroplating, and a Sn plating layer can be formed on the Ni plating layer. Next, the electronic components are mounted on a 1.6 mm thick glass epoxy substrate using solder. Then, with the substrate supported 45 mm from the mounting location on both sides in the longitudinal direction of the electronic components, force is applied from the back surface of the substrate where the electronic components are mounted to bend the substrate by 1.5 mm and hold for 5 seconds. The means of applying force are not limited; for example, mechanical stress can be applied by bending the substrate using a pressing jig. After bending the substrate and holding for 5 seconds, the electronic components are removed from the substrate, and evaluation samples are prepared by exposing the cross-sections of each electronic component. For example, each electronic component can be embedded in resin, and the cross-section of each electronic component can be exposed by cutting the electronic component so as to pass through the center of both end faces of the electronic component and perpendicular to the substrate surface. After that, the presence or absence of cracks in the laminated body is observed using the evaluation samples, and the percentage of samples in which cracks occurred is calculated.

[0073] The conductive paste of the present invention is preferable for use as terminal electrodes in multilayer ceramic electronic components such as multilayer ceramic capacitors, multilayer inductors, multilayer piezoelectric actuators, and multilayer thermistors. By using the conductive paste of the present invention as terminal electrodes in multilayer ceramic electronic components, it is possible to obtain electronic components with highly dense terminal electrodes and excellent flexural strength, even when fired in a non-oxidizing atmosphere.

[0074] The method for applying the conductive paste is not particularly limited; for example, dip printing and screen printing methods can be used, with dip printing being particularly preferred. By using dip printing, the conductive paste can be suitably applied to the edges of the laminated body, so that when the conductive paste shrinks during firing, stress is applied more uniformly to the edges of the laminated body. Therefore, it becomes easier to obtain electronic components that have highly dense terminal electrodes and excellent flexural strength.

[0075] The present invention will be described below based on specific experimental examples, but the present invention is not limited to these.

[0076] <Preparation of conductive powder> Zirconia beads with a diameter of 0.1 mm, spherical copper powder, and secondary butyl alcohol were mixed and ground using a bead mill, adjusting the flow rate and number of passes as appropriate to obtain copper powder. The obtained copper powder was measured for D50, the ratio of the average major axis to the average minor axis (average major axis / average minor axis), and the tap density using the method described below.

[0077] <Preparation of Glass Frit> Glass raw materials were each mixed to obtain the oxide composition shown in Table 1 in terms of oxides. These were melted at 1200°C in a platinum crucible, air-cooled or rapidly cooled, and then pulverized to obtain glass frit. The D50 and tap density of the obtained glass frit were measured using the method described below.

[0078] <Measurement of conductive powder and glass frit> (D50) For copper powder and glass frit, the volume-based cumulative 50% particle size D50 was measured using a laser diffraction particle size distribution analyzer (HORIBA LA-960).

[0079] (Average major diameter / Average minor diameter) For copper powder, 100 copper particles were randomly selected by scanning electron microscopy and their major diameters were measured. The average value of the major diameters (average major diameter) was calculated. In addition, the conductive paste prepared in the experimental example described later was cast onto a PET film using an applicator to form a coating film with a thickness of 250 μm. This coating film was dried in an air atmosphere at 150°C for 10 minutes to form a dried film. The cross-section of the dried film was exposed using an ion milling apparatus (Hitachi High-Tech Corporation, IM4000), and the cross-section of the dried film was observed with a scanning electron microscope (Hitachi High-Tech Corporation, SU-8020). From this observation, 100 copper particles were randomly selected and their minor diameters were measured, and the average minor diameter was calculated. The ratio of the average major diameter to the average minor diameter was then calculated.

[0080] (Tap Density) For copper powder and glass frit, a tap density measuring device (KYT-4000, manufactured by Seishin Corporation) was used to weigh 20 g of powder and measure it over 20 cm. ３ Place the sample in the cell, set the tapping stroke to 20 mm, and the number of taps to 200, then measure the sample volume (cm³) after tapping. ３ This was calculated as the ratio of the sample weight (g) to the given value.

[0081] <Preparation of conductive paste> (Experimental Examples 1-12) Mix 100 parts by mass of copper powder, 10 parts by mass of glass frit, and 7 parts by mass of acrylic resin (Dianal MB-2677, manufactured by Mitsubishi Chemical Corporation) dissolved in terpineol (amount as resin component excluding terpineol). Then, knead using a three-roll mill (manufactured by Inoue Seisakusho), dilute with terpineol, and prepare at 25°C and a shear rate of 4s. －１ A conductive paste was prepared by adjusting the viscosity to 30 Pa·s. The prepared conductive paste was used for the evaluation described below. The results are shown in Table 1. Experiments marked with "*" are outside the scope of the present invention. The units of the numerical values ​​for the composition of glass frit in Tables 1 to 3 are "mass%".

[0082] <Evaluation of physical properties of conductive paste> (Viscosity) The viscosity of the conductive paste was measured using a rotational viscometer (Brookfield, model number: HADV-II+Pro) at 25°C with a shear rate of 4s. －１ The measurements were taken under the following conditions.

[0083] (Dry film density) A conductive paste is cast onto a PET film to a thickness of 250 μm to form a coating film. The coating film is dried in an air atmosphere at 100°C for 15 minutes, and then dried again in an air atmosphere at 150°C for 15 minutes to form a dry film. The resulting dry film is cut into a circle with a diameter of 20 mm, and the weight and volume of the cut dry film are measured. ３ Dry film density (g / cm³) is expressed as the ratio of weight (g) to ) ３ ) was calculated.

[0084] <Evaluation Test of Electronic Components> (Fabrication of Electronic Components with Terminal Electrodes) A ​​laminated body was prepared, which is approximately rectangular in shape with a length of 0.6 mm, a width of 0.3 mm, and a height of 0.3 mm, and consists of multiple layers of dielectric layers containing barium titanate and internal electrode layers containing nickel. Conductive paste was applied to the exposed end of this laminated body by dip printing, with the descent speed of the laminated body being 300 μm / s and the pull-up speed being 100 μm / s. The body was then held in an air atmosphere at 150°C for 10 minutes. Subsequently, the temperature was increased in a nitrogen atmosphere at a heating rate of 50°C / min until it reached 780°C, and then held for 15 minutes to form terminal electrodes, thereby fabricating an electronic component with terminal electrodes.

[0085] (Density of terminal electrodes (non-void area ratio)) In each experimental example, 20 of the aforementioned electronic components were prepared. Each electronic component was embedded in resin, and each electronic component was cut in the direction of lamination (perpendicular to the dielectric layer and the internal electrode layer) passing through the center of both end faces of the electronic component, thereby exposing the cross-section of each electronic component and creating a sample for evaluation testing. Next, the evaluation test samples were observed using a scanning electron microscope, with 10 fields of view for each sample, for a total of 200 fields of view, and the ratio of the non-void area to the total electrode area in the field of view was calculated as the non-void area ratio. The value of this non-void area ratio was evaluated in three stages, A, B, and C, based on the following evaluation criteria. [Evaluation Criteria] A: Non-void area ratio of 95% or more B: Non-void area ratio of 90% or more and less than 95% C: Non-void area ratio of less than 90%

[0086] (Deflection strength of electronic components (flection crack occurrence rate)) In accordance with JIS C60068-2-21, the following tests were conducted. First, 20 of the aforementioned electronic components were prepared for each experimental example. A Ni plating layer was formed on the surface of the terminal electrodes of the electronic components by electroplating, and then a Sn plating layer was formed on the Ni plating layer. The aforementioned electronic components were then mounted on a 1.6 mm thick glass epoxy substrate using solder. Next, with the electronic components supported at 45 mm from the mounting location on both sides in the longitudinal direction of the electronic components, the substrate was bent from the back side of the mounting location using a pressing jig to apply mechanical stress. The holding time was 5 seconds, and the bending amount was 1.5 mm. After bending the substrate, the electronic components were removed from the substrate, each electronic component was embedded in resin, and each electronic component was cut perpendicular to the substrate surface, passing through the center of both end faces of the electronic component, to expose the cross-section of each electronic component and prepare evaluation samples. Then, the cracks in the laminated material were observed using the samples, and the percentage of samples that developed cracks (flexure crack occurrence rate) was determined and evaluated in three stages: A, B, and C. [Evaluation Criteria] A: Number of samples with cracks was 0 (flexure crack occurrence rate 0%) B: Number of samples with cracks was 1 (flexure crack occurrence rate greater than 0% and 5% or less) C: Number of samples with cracks was 2 or more (flexure crack occurrence rate greater than 5%)

[0087] (Accumulation of Zn-containing deposits in manufacturing equipment) The laminated bodies coated with conductive paste from Experimental Examples 1 to 12 were fired, and it was confirmed whether Zn-containing deposits had accumulated in the equipment used to manufacture electronic components equipped with terminal electrodes. If such deposits were present, this was indicated as "Yes" in Table 1. The composition of the deposits was analyzed by ICP-MS.

[0088]

[0089] (Experimental Examples 13-18) <Preparation of Glass Frit> Glass raw materials were each prepared so that the oxide composition in terms of oxides was as shown in Table 2, and melted at 1200°C using a platinum crucible to obtain a melt. Glass was obtained by cooling the melt by adjusting the cooling rate as appropriate using the method described above. The obtained glass was crushed to obtain glass frit. The D50 and tap density of the obtained glass frit were measured using the method described above. In addition, ΔTG was measured using the method described below. The results are shown in Table 2.

[0090] <ΔTG> Using a thermogravimetric analyzer, 20 mg of each glass frit from Experimental Examples 13 to 18 was heated from room temperature to 1000°C at a heating rate of 20°C / min in an atmospheric environment. The absolute value of the difference between the lowest weight loss rate [%] in the range of 100°C to 800°C and the highest weight loss rate [%] in the range of 800°C to 1000°C was measured as ΔTG [%].

[0091] <Oxygen Donating Properties> Glass pastes were prepared by kneading each of the glass frits from Experimental Examples 13-18 with an organic vehicle in which acrylic resin was dissolved in terpineol using a three-roll mill. The prepared pastes were screen printed onto an alumina substrate to create two samples for oxygen donating properties for each experimental example. These samples were fired in a belt furnace in a nitrogen atmosphere at a heating rate of 60°C / min to 700°C, and removed from the furnace when 700°C was reached. The residual carbon content of the samples removed from the furnace after firing was measured using a CS (carbon-sulfur) analyzer (HORIBA, EMIA-320V2 / FA), and the average value of two samples for each experimental example was calculated. The results are shown in Table 2.

[0092]

[0093] (Experimental Examples 19-22) <Preparation of Glass Frit> Glass raw materials were each mixed to obtain the oxide composition shown in Table 3 in terms of oxides, melted at 1200°C in a platinum crucible, air-cooled or rapidly cooled, and then pulverized to obtain glass frit. The D50 and tap density of the obtained glass frit were measured using the method described above. In addition, the contact angle of the glass with respect to the copper plate at 750°C was measured using the method described later. The results are shown in Table 3.

[0094] <Contact angle of glass with copper plate at 750°C> 40 mg to 60 mg of the glass frit listed in Table 3 was placed in a cylindrical container with an inner diameter of 5 mm and pressure was applied axially at 40 MPa for 30 seconds to produce a cylindrical compact with a diameter of 5 mm and a height of 0.95 mm to 1.05 mm. The compact was placed on a copper plate so that its flat surface was in contact with the copper plate, and the compact was heated in a nitrogen atmosphere at a heating rate of 10°C / min to 750°C to melt the glass constituting the compact. The contact angle of the glass with the copper plate was then measured. The copper plate used was a C1020 copper plate manufactured by PREC (25 mm long, 25 mm wide, 0.3 mm thick). Before use, the surface on which the compact was placed was subjected to a reduction treatment to remove the oxide film. After the oxide film was removed, the surface roughness Ra of the copper plate on which the compacted powder was placed was between 150 nm and 170 nm.

[0095] <Preparation of Conductive Paste> Conductive paste was prepared using the same method as described above, except that glass frit was used as shown in Table 3. The evaluation described above was performed using the prepared conductive paste. The results are shown in Table 3. Experiments marked with "*" are experiments outside the scope of the present invention.

[0096]

[0097] Table 1 shows that by using glass frit that does not contain Zn, there is no accumulation of Zn-containing deposits in the manufacturing equipment. Furthermore, it can be seen that the bending strength of electronic components is good when the respective content and ratio of Mn and Cu elements in terms of oxides, as well as the total content, are within the range of the present invention. It can also be seen that the bending strength of electronic components is particularly good by controlling the dry film density of the conductive paste, the tap density of the copper powder, the tap density of the glass frit, or the D50 of the glass frit. When the ΔTG was measured for the glass frit used in Experimental Examples 3 to 9 using the method described above, it was all between 0.37% and 0.62%. Furthermore, when the residual carbon content was measured for the glass frit used in Experimental Examples 3 to 9 as an evaluation of oxygen donation using the method described above, it was all less than 100 ppm by mass. Furthermore, when the "contact angle of the glass to the copper plate at 750°C" was measured for the glass frit used in Experimental Examples 3 to 9 using the method described above, it was all between 40° and 57°.

[0098] From the results in Table 2, it can be seen that the smaller the ΔTG value, the less residual carbon there is, and therefore, when comparing with the same composition, a smaller ΔTG value indicates superior oxygen donation. Furthermore, when conductive pastes were prepared using the glass frit from Experimental Examples 13-18 instead of the glass frit from Experimental Example 3 and the aforementioned evaluation was performed, good results were obtained, similar to the other experimental examples within the scope of the present invention. Also, when the "contact angle of the glass to the copper plate at 750°C" was measured for the glass frits used in Experimental Examples 13-18 using the method described above, all were between 40° and 57°. As mentioned above, a smaller ΔTG value indicates superior oxygen donation, so even when firing under conditions that make carbon removal more difficult, such as shorter firing times, faster heating rates, or lower firing temperatures compared to the aforementioned evaluation conditions (firing conditions), it becomes easier to obtain electronic components with highly dense terminal electrodes and excellent flexural strength. In other words, a smaller ΔTG value allows for even greater mass production of electronic components than before (improving the mass-producibility of electronic components).

[0099] Table 3 shows that when the contact angle of the glass frit with respect to the copper plate at 750°C is 60° or less, and especially 57° or less, the bending strength of the electronic component tends to be even better. Furthermore, when the ΔTG was measured for the glass frit used in Experimental Examples 20-22 using the method described above, it was all between 0.38% and 0.55%. Also, when the residual carbon content was measured for the glass frit used in Experimental Examples 20-22 as an evaluation of oxygen donation using the method described above, it was all less than 100 ppm by mass. As mentioned above, the smaller the contact angle with respect to the copper plate at 750°C, the better the wettability of the glass to the copper plate. Therefore, even when firing under conditions where glass is less likely to spread wetting into the film, such as when the firing time is shorter, the heating rate is faster, or the firing temperature is lower compared to the evaluation conditions (firing conditions) described above, it becomes easier to obtain electronic components with highly dense terminal electrodes and excellent bending strength. In other words, the smaller the contact angle of the glass frit with the copper plate at 750°C, the more electronic components can be mass-produced compared to conventional methods (improving the mass-producibility of electronic components).

[0100] 1. Multilayer body 2. Internal electrode layer 3. Ceramic layer 4. Terminal electrode 5. Stress concentration area 6. Substrate 10. Multilayer ceramic capacitor

Claims

1. A conductive paste containing a conductive powder mainly composed of copper, glass frit, a binder resin, and an organic solvent, wherein the glass frit substantially does not contain Zn, contains 40.0% to 65.0% by mass of Ba element in terms of BaO, and contains B element ２ O ３ Converted to 15.0% by mass or more and 23.0% by mass or less, Al element to Al ２ O ３ Converted to 2.0% by mass or more and 12.0% by mass or less, Si element is SiO ２ Converted to 4.0% to 8.0% by mass, Ca element to 3.0% to 7.5% by mass in CaO equivalent, Mn element to MnO ２ The glass frit contains 2.5% to 5.0% by mass in terms of equivalent weight, and Cu element is 10.0% to 14.0% by mass in terms of equivalent weight of CuO, and the total content of Mn element and Cu element in terms of oxides (MnO ２ The amount of CuO in the glass frit is 12.5% ​​by mass or more and 17.5% by mass or less, and the mass ratio of the Cu element in the glass frit in terms of oxides to the Mn element in the glass frit is (CuO / MnO ２ A conductive paste characterized in that the coefficient of ) is between 2.0 and 4.

0.

2. The conductive paste according to claim 1, characterized in that, by thermogravimetric analysis, when 20 mg of the glass frit is heated from room temperature to 1000°C at a heating rate of 20°C / min in an atmospheric environment, the absolute value ΔTG of the difference between the minimum weight loss rate [%] in the range of 100°C to 800°C and the maximum weight loss rate [%] in the range of the temperature above the minimum value and below 800°C is 0.62% or less.

3. The conductive paste according to claim 1 or 2, characterized in that when 40 mg to 60 mg of the glass frit is placed in a cylindrical container with an inner diameter of 5 mm and pressure is applied axially at 40 MPa for 30 seconds to produce a cylindrical compact with a diameter of 5 mm and a height of 0.95 mm to 1.05 mm, the compact is placed on a copper plate so that the flat surface of the compact is in contact with the copper plate, and the compact is heated in a nitrogen atmosphere at a heating rate of 10°C / min to 750°C to melt the glass constituting the compact, the contact angle of the glass with respect to the copper plate is 60° or less.

4. The dry film density of the conductive paste is 4.1 g / cm ３ or more and 4.7 g / cm ３ or less. The conductive paste according to claim 1 or 2, characterized in that.

5. The tap density of the conductive powder mainly composed of copper is 3.0 g / cm³. ３ 5.0g / cm or more ３ The conductive paste according to claim 1 or 2, characterized in that it is as follows:

6. The tap density of the glass frit is 1.0 g / cm³. ３ 1.5g / cm or more ３ The conductive paste according to claim 1 or 2, characterized in that it is as follows:

7. The conductive paste according to claim 1 or 2, characterized in that the volume-based cumulative 50% particle size D50 of the glass frit measured by laser diffraction particle size distribution is 0.3 μm or more and 3.0 μm or less.

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