JP2004273426A - Conductive paste and ceramic multilayer substrate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable conductive paste, having sufficient flatness, excellent dimensional accuracy, and high electrode adhesive strength, capable of laminating such as fine line electrodes in a high density, preventing its electric property from being degraded, and providing a sintered internal layer electrode peripheral, free from drawbacks which may impair its reliability, and to provide a ceramic multilayer substrate using the conductive paste. <P>SOLUTION: The conductive paste contains at least a conductive particle in which a surface of a metal powder consisting of Ag or consisting essentially of Ag is coated with a metal oxide having a higher melting point than Ag, a molybdenum compound, and an organic vehicle. The conductive paste is used as an inner layer electrode 2 for the ceramic multilayer substrate 10. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a ceramic multilayer substrate having high precision and high flatness used for a multilayer ceramic electronic component, and a conductive paste used for manufacturing the same.

  In a low-temperature firing type ceramic multilayer substrate used for a conventional multilayer ceramic electronic component, a three-dimensional circuit is formed by stacking and firing a plurality of ceramic green sheets on which wiring patterns are formed.

  In order to connect the wiring patterns of each layer of the ceramic multilayer substrate, through holes are previously formed in the ceramic green sheet of the desired layer, and a conductive paste such as Ag or Cu is filled in the through holes and laminated, and then fired simultaneously. Thus, a three-dimensional circuit is formed by connecting the wiring patterns of each layer.

  However, in the normal firing method, the firing shrinkage behavior of the conductor material and the ceramic material often differ, and it has been difficult to obtain a large and flat ceramic multilayer substrate.

  Also, it was difficult to obtain a ceramic multilayer substrate having high dimensional accuracy due to shrinkage variation during firing.

  Therefore, as a firing method for obtaining a ceramic multilayer substrate with high dimensional accuracy, a ceramic green sheet made of an inorganic composition that does not sinter at the firing temperature of the ceramic green sheet is constrained on both main surfaces of the ceramic green sheet laminate. Then, a method of firing after lamination is proposed. By using this constraining layer, shrinkage in the plane direction is greatly suppressed, and shrinkage occurs selectively only in the thickness direction. This makes it possible to obtain a flat ceramic multilayer substrate with good dimensional accuracy.

  The constraining layer can be easily removed because sintering has hardly progressed even after firing.

  On the other hand, under normal firing conditions, the firing shrinkage behavior of the conductor paste and the ceramic green sheet material often differs, and the conductive particles, which are conductors, begin to diffuse at a lower temperature than the ceramic material and shrink, and then the ceramic material fires. Because of the shrinkage, the residual internal stress due to shrinkage during firing increases.

  Therefore, when a ground layer (ground layer) occupying a large area of the wiring pattern is formed, many defects such as peeling and cracks occur, and a large and flat ceramic multilayer substrate for improving productivity is obtained. Was difficult. In order to solve this problem, a method in which the surface of conductive particles such as Ag and Cu is coated with a stable metal oxide at a high temperature to shift a firing temperature range to be reacted to a higher temperature side and to match firing shrinkage behavior. Has been proposed.

As prior art document information relating to the invention of this application, for example, Patent Document 1 and Patent Document 2 are known.
Japanese Patent No. 2785544 JP-A-8-7644

  However, a new problem arises in manufacturing a ceramic multilayer substrate by the above-described method.

  In the firing process, the difference between the sintering timing and firing shrinkage behavior of the conductive paste and the ceramic green sheet laminate causes a difference between the inner electrode and the glass ceramic layer and around the inner electrode when the inner electrode layer is made more multilayer. In this case, defects easily occur in the ceramic body. This phenomenon appears remarkably when fine line electrodes and the like are formed at a high density, particularly when they are laminated.

  According to the conventional manufacturing method, defects hardly occur because shrinkage occurs in the three-dimensional direction in the firing process.Also, even if defects occur, fine defects can be sufficiently repaired during firing. there were.

  However, in the manufacturing method of Patent Document 1, since the shrinkage hardly occurs in the plane direction, the possibility of occurrence of the defect is extremely low, and once it occurs, it remains until the final stage. When defects occur at the interface between the inner layer electrode and the glass ceramic layer, the reliability of the ceramic multilayer substrate is greatly reduced.

  On the other hand, with an external electrode such as a surface layer electrode, the adhesion strength between the electrode and the ceramic multilayer substrate cannot be sufficiently obtained, so that the bonding strength with a component to be mounted or the bonding with a printed mounting board is insufficient.

  Therefore, the present invention has sufficient flatness, good dimensional accuracy, and electrode adhesion strength for mounting semiconductors and chip components, enables fine-line electrodes and the like to be stacked at a high density, and has excellent electrical characteristics. It is an object of the present invention to obtain a highly reliable conductive paste which does not deteriorate and does not have a defect such as a decrease in reliability around an inner layer electrode after firing and a ceramic multilayer substrate using the same.

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

  The invention according to claim 1 of the present invention contains at least a conductive particle in which Ag or a metal powder whose main component is Ag is coated with a metal oxide having a melting point higher than Ag, a molybdenum compound, and an organic vehicle. A conductive paste for realizing a ceramic multilayer substrate having high precision and high flatness, which is a conductive paste, can be provided.

The invention according to claim 2 of the present invention is the conductive paste according to claim 1, wherein the molybdenum compound is contained in an amount of 0.1 to 5% by weight in terms of MoO ₃ with respect to the total amount of the organic vehicle and the conductive particles. In addition, a conductive paste having low resistance can be realized in addition to the effect of the first aspect.

According to a third aspect of the present invention, at least two types of metal oxides having a melting point higher than Ag and metal compounds having a lower melting point than the metal oxide are formed on the surface of Ag or a metal powder containing Ag as a main component. And a conductive paste containing at least an organic vehicle and a molybdenum compound in an amount of 0 to 5% by weight in terms of MoO ₃ with respect to the total amount of the organic vehicle and the conductive particles. A conductive paste for realizing a multilayer substrate having flatness can be provided.

  The invention according to claim 4 of the present invention is the conductive paste according to claim 1 or 3, wherein the conductive particles have an average particle size of 0.1 to 3 µm, and the interface between the electrode and the glass ceramic after firing. Since the smoothness is good, it is possible to realize a high-performance internal electrode that is excellent in high-frequency characteristics and excellent in fine line characteristics and has few defects.

  The invention according to claim 5 of the present invention is the conductive paste according to claim 1 or 3, which contains at least 5 to 30% by weight of an organic vehicle and 70 to 95% by weight of conductive particles, and is more excellent in productivity. A high-performance conductive paste can be provided.

The invention according to claim 6 of the present invention is the conductive paste according to claim 1 or 3, wherein the viscosity at 25 ° C. is 1200 Pa · s or more when the shear rate is 0.2 s ⁻¹ , and has excellent reproducibility. A conductive paste with good production efficiency can be provided.

In the invention according to claim 7 of the present invention, the viscosity at 25 ° C. is 300 Pa · s or more at a shear rate of 0.2 s ⁻¹ and 150 Pa · s or less at a shear rate of 20 s ^−1. And a conductive paste capable of forming a highly accurate print pattern.

  According to an eighth aspect of the present invention, there is provided a ceramic green sheet made of a glass ceramic material, wherein a wiring pattern is formed, a plurality of the ceramic green sheets are laminated, and the firing temperature of the ceramic green sheet laminate is formed on both main surfaces thereof. A ceramic multilayer substrate produced by laminating a constraining layer made of a ceramic material that does not sinter, firing the ceramic green sheet laminate, and removing the constraining layer after firing, at least a part or all of the wiring pattern Is a ceramic multilayer substrate formed of the conductive paste according to any one of claims 1 to 7, and a ceramic multilayer substrate having high accuracy and high flatness can be realized.

  According to a ninth aspect of the present invention, a wiring pattern is formed on a ceramic green sheet made of a glass ceramic material, a plurality of the ceramic green sheets are laminated, and the firing temperature of the ceramic green sheet laminate is formed on both main surfaces thereof. A ceramic multilayer substrate manufactured by laminating a constraining layer made of a ceramic material that is not sintered, firing the ceramic green sheet laminate, and removing the constraining layer after firing, wherein at least the front surface or / and the back surface or / and This is a ceramic multilayer substrate in which the wiring pattern on the side surface is formed of the conductive paste according to any one of claims 1 to 7, and a ceramic multilayer substrate with high mounting reliability can be realized.

According to a tenth aspect of the present invention, the glass ceramic material is Al ₂ O ₃ , MgO, ROa (R is at least one element selected from La, Ce, Pr, Nd, Sm and Gd, and a is 10. The ceramic multilayer substrate according to claim 8, comprising a dielectric ceramic component containing at least a stoichiometric value determined according to the valence of R) and an alkaline earth silicate glass component. In addition to the effects of claims 8 and 9, a ceramic multilayer substrate having excellent strength can be realized.

Invention of claim 11 of the present invention, salt-based glass alkaline earth silicate the SiO ₂ 40 to 50 wt%, the B ₂ O ₃ 0 wt%, MeO (Me is Ba, Ca, Sr 11. The ceramic multilayer substrate according to claim 10, wherein the ceramic multilayer substrate has a composition containing 25 to 50% by weight of at least one selected from the group consisting of (a) and (b). be able to.

  By producing a ceramic multilayer substrate using the conductive paste according to the present invention, after firing, defects and the like occur at the interface between the inner layer electrode having fine lines laminated with high precision and the glass ceramic layer and the periphery thereof. It is possible to obtain a ceramic multi-layer substrate having high precision and high flatness and excellent high-frequency characteristics without any problem. Further, it is possible to obtain a ceramic multilayer substrate having an external electrode with high adhesion strength and excellent in mounting reliability.

(Embodiment 1)
Hereinafter, the first embodiment of the present invention will be described with reference to the first embodiment.

  FIG. 1 is a cross-sectional view for explaining a structure of a ceramic multilayer substrate according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining a structure of a ceramic green sheet laminate. FIG. 3 is a cross-sectional view for explaining defects in the peripheral portion of the electrode after firing.

  First, the configuration of the ceramic multilayer substrate 10 will be described with reference to a manufacturing method.

  Reference numeral 1 denotes a ceramic green sheet designed and manufactured to have a predetermined thickness. As the ceramic green sheet 1, a low-temperature sintering type glass ceramic material can be used. By using a glass ceramic material for the ceramic green sheet 1, an electrode material having a high conductivity such as Ag or Cu can be used, and a ceramic multilayer substrate capable of realizing a small, high-performance high-frequency module or the like in high-frequency device applications. Can be provided.

  This ceramic green sheet 1 can be manufactured as follows. First, an appropriate amount of a polyvinyl butyral-based resin binder, a plasticizer, and an organic solvent were added to a glass ceramic material obtained by mixing a ceramic powder and a glass powder, and the mixture was thoroughly dispersed to prepare a ceramic slurry. The glass ceramic used here will be described later in detail.

  Next, the ceramic slurry is formed into a ceramic green sheet 1 having a thickness of 20 to 100 μm on a base film (such as a PET film) by a ceramic green sheet forming method such as a doctor blade method. Here, the PET film is used as the base film, but there is no particular limitation as long as the material has releasability.

  Then, after cutting the ceramic green sheet 1 to a predetermined size, a via hole for forming the via electrode 3 is formed by a method such as punching or laser processing. If necessary, a pilot hole for positioning at the time of lamination is also formed at the same time.

  Thereafter, the via holes 3 are formed by filling the via holes with an electrode paste, and the electrode pattern of the inner layer electrode 2 is printed by a screen printing method. The conductive paste used here will be described later in detail.

  After the via electrode 3 and the inner layer electrode 2 are formed, the base film is faced up, the pins of the laminator are aligned with the pilot holes on the base film, and the base film is peeled off after thermocompression bonding. By repeating this operation for the required number of layers, a laminate of ceramic green sheets 1 using a glass ceramic material is formed.

Further, a constraining ceramic green sheet made of a material such as Al ₂ O ₃ , ZrO ₂ , MgO which does not sinter at the firing temperature of the ceramic green sheet 1 is formed on the upper and lower surfaces of the laminate of the ceramic green sheets 1 as the constraining layer 5. By laminating and pressing this laminate by a hot press, a ceramic green sheet laminate 11 in which the constraining layers 5 are arranged vertically as shown in FIG. 2 is formed. After the ceramic green sheet laminate 11 is degreased at 350 to 600 ° C. and fired at 850 to 950 ° C., a low-temperature fired ceramic multilayer substrate 10 having a three-dimensional wiring circuit as shown in FIG. 1 is obtained. . In FIG. 1, reference numeral 6 denotes a glass ceramic layer obtained by firing the ceramic green sheet 1.

  The surface electrode 4 may be baked simultaneously with the ceramic green sheet laminate 11 or may be baked after the calcination.

  Note that the constraining layer 5 can be easily removed after polishing by a method such as polishing, ultrasonic cleaning, or blasting. Then, after mounting an IC, a SAW filter, a chip component, and the like as necessary on the surface layer of the ceramic multilayer substrate 10 thus formed, the chip is cut into a predetermined chip size by a method such as dicing to obtain a desired multilayer ceramic electronic component. Is obtained.

  With the above configuration, it is possible to efficiently provide the ceramic multilayer substrate 10 having high dimensional accuracy and excellent flatness.

  Next, the conductive paste used for the ceramic multilayer substrate will be described in detail.

  In order to prevent defects around the inner layer electrode 2 due to firing of the ceramic multilayer substrate 10 manufactured by this method, the conductive paste sinters more slowly than a normal Ag paste and before and after the sintering temperature of the glass ceramic material. It is important not to cause sudden shrinkage.

  The conductive paste according to the present invention is a conductive paste containing at least an organic vehicle, conductive particles coated with metal oxide 13 having a melting point higher than Ag on the surface of Ag or metal powder 12 containing Ag as a main component, and a molybdenum compound. It is constituted by.

  By coating the conductive paste with a metal oxide 13 having a melting point higher than that of Ag, even if the average particle size of the Ag powder, which is a conductive particle, is reduced, sintering can be delayed as compared with ordinary Ag powder, and the molybdenum compound can be reduced. By including the same, a gradual shrinkage behavior characteristic can be obtained, so that a conductive paste that does not cause rapid shrinkage before and after the sintering temperature of the glass ceramic material can be realized.

It was also confirmed that Mo metal, MoO ₃ , Mo organic compounds such as naphthenic acid Mo, 2-ethylhexanoic acid Mo, and octylic acid Mo, or MoSiO ₂ as a silicide can exert the effect of the molybdenum compound.

Further, it has been found that the content of the molybdenum compound is preferably 0.1 to 5% by weight in terms of MoO ₃ with respect to the total amount of the organic vehicle and the conductive particles to realize preferable characteristics. When the amount is less than 0.1% by weight, the effect of adding the molybdenum compound is small, and when the amount is more than 5% by weight, the conductor resistance after firing becomes large, the characteristics are deteriorated in a high frequency region, and practicality is poor.

Further, the conductive paste according to the present invention comprises an organic vehicle, a metal oxide 13 having a higher melting point than Ag and a metal compound 14 having a lower melting point than the metal oxide, on the surface of Ag or a metal powder 12 containing Ag as a main component. And a conductive paste containing at least an organic vehicle and containing 0 to 5% by weight of a molybdenum compound in terms of MoO _{3 based} on the total amount of the organic vehicle and the conductive particles. ing.

  This conductive paste has a form in which at least two kinds of metal oxide 13 having a melting point higher than Ag and a metal compound 14 having a lower melting point than the metal oxide are coated on the surface of the Ag powder, and is sintered more than the normal Ag powder. Can be delayed and the sintering temperature can be easily controlled and the gradual shrinkage can be easily achieved by coating with the metal compound 14 having a melting point lower than that of the metal oxide 13 as compared with the case of coating with only one kind of metal oxide. Since the behavior characteristics can be obtained, it is possible to realize a conductive paste that does not cause rapid shrinkage before and after the sintering temperature of the glass ceramic material. Further, even if the molybdenum compound is contained in an amount of 5% by weight or less, more effect can be exhibited.

  Further, the organic vehicle used here contains an organic binder and a solvent, and is not particularly limited. For example, ethyl cellulose, butyral resin, acrylic resin and the like can be used. As the solvent, for example, butyl carbitol, butyl carbitol acetate, terpineol, and the like can be used.

  Further, as the conductive particles, any metal having high conductivity may be used, and Cu or the like can be used by firing in a nitrogen atmosphere. Further, a metal such as Pd, Pt, Au, Cu or the like may be mixed with the Ag powder, if necessary, or may be used as an alloy powder thereof. The content of the metal other than Ag can be determined in consideration of the sintering temperature, conductor resistance, cost, and the like.

The kind of metal oxide having a higher melting point than Ag is not particularly limited, but Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaO, CaO, SiO _{2 and the} like were effective. It is desirable to select the amount so that the amount of the Ag-based powder to be coated is within the required range of the conductor resistance. As a result of the study, a preferable range of the conductor resistance showed excellent high-frequency characteristics in a range of 0.01 to 0.5% by weight.

  The metal compound having a lower melting point than the metal oxide may be a metal oxide having a lower melting point than the metal oxide, or may be an organic metal compound, a molybdenum compound, or the like. It is desirable to select the amount so that the amount of the Ag-based powder to be coated is within the required range of the conductor resistance.

  Here, the coating means not only a state in which the entire surface of the Ag-based powder is continuously coated as shown in FIG. 4, but also a part in which the surface is coated as shown in FIG. 5, and further, as shown in FIG. This includes those that are scattered and attached. The form changes according to the amount of the metal oxide to be coated.

  In the case of coating with a metal oxide 13 having a higher melting point than Ag and a metal compound 14 having a lower melting point than Ag, as shown in FIG. As shown in FIG. 9, there is a type in which only one type is continuously coated, and a type in which both types are partially coated as shown in FIG. 9, and the form of the coating changes according to the amount. It is not limited to the form shown.

  4 to 9, the metal oxide 13 to be coated is in the form of particles, but may be coated with a film-shaped metal oxide 13 as shown in FIG. Further, in the case of this film-like coating, the coating is not limited to the coating as shown in FIG. 10, but also includes a coating that is partially coated or adhered in a dotted manner. Similarly, as shown in FIG. 11, a film-shaped metal oxide 13 and a metal compound 14 may be applied. In this case as well, the powder is not limited to one in which the entire surface of the powder is coated twice without any break as shown in FIG. 11, but also one in which only one kind is coated without any break and one in which both kinds are partially coated are included.

  Further, the conductive paste preferably contains 5 to 30% by weight of the organic vehicle and 70 to 95% by weight of the conductive particles, and preferably has an average particle size of 0.1 to 3 μm. If the conductive particles are less than 70% by weight, the probability of disconnection of the inner layer electrode 2 formed of fine lines after firing increases, and if it is more than 95% by weight, the printability of the fine lines of the inner layer electrode 2 deteriorates. When the average particle size of the conductive particles is smaller than 0.1 μm, the sintering temperature is lowered. When the average particle size is larger than 3 μm, the printability of the fine line of the inner electrode 2 is deteriorated, and the interface between the electrode and the glass ceramic is deteriorated. This is because the smoothness deteriorates and the high frequency characteristics deteriorate.

Next, the viscosity of the conductive paste at 25 ° C. is more preferably 1200 Pa · s or more when the shear rate is 0.2 s ⁻¹ . If the viscosity at 25 ° C. is 1200 Pa · s or more when the shear rate is 0.2 s ⁻¹ , it is possible to greatly reduce the collapse of the pattern that occurs when fine lines are continuously printed.

Further, the viscosity of the conductive paste at 25 ° C. is preferably 300 Pa · s or more at a shear rate of 0.2 s ⁻¹ and 150 Pa · s or less at a shear rate of 20 s ⁻¹ . The reason for setting the preferable viscosity in this range is that if the viscosity at a shear rate of 0.2 s ^-1 is lower than 300 Pa · s, the printing accuracy of the fine line of the inner electrode 2 becomes poor or the fine line of the inner electrode 2 This is because in a pattern in which the space between the fine lines is narrow, the probability of occurrence of short-circuit failure due to dripping of the conductive paste increases. If the viscosity at a shear rate of 20 s ⁻¹ is higher than 150 Pa · s, the printability of the fine line of the inner layer electrode 2 is significantly deteriorated.

  The conductive paste can be produced by kneading conductive particles, a molybdenum compound, and an organic vehicle having a desired composition, and uniformly dispersing these substances with a three-roll mill.

  Next, the glass ceramic material will be described.

  In order to ensure the characteristics of the ceramic multilayer substrate 10 manufactured in the present embodiment, it is necessary that the glass ceramic material can be co-fired with the Ag-based conductive paste and that no defect occurs around the fired electrode. is there. In consideration of the melting point of Ag, the glass ceramic material is preferably sintered at 850 to 950 ° C.

The glass-ceramic material constituting the ceramic multilayer substrate 10 according to the present embodiment is Al ₂ O ₃ , MgO, ROa (R is at least one element selected from La, Ce, Pr, Nd, Sm and Gd. Is preferably a dielectric ceramic component containing at least a stoichiometric value according to the valence of R) and an alkaline earth silicate glass component.

  By using such a glass ceramic material, it was possible to obtain a ceramic multilayer substrate 10 with few internal defects, high strength, high precision, and low loss suitable for use at high frequencies.

Further, salt-based glass alkaline earth silicates SiO ₂ is 40 to 50% by weight constituting the glass-ceramic material of the ceramic multilayer substrate 10, B ₂ O ₃ is 0-10 wt%, MeO (Me is Ba, Ca, (At least one selected from Sr) is preferably contained in the range of 25 to 50% by weight. SiO ₂ is a main oxide of glass, but if it exceeds 50 wt%, the melting temperature becomes too high, and if it is less than 40 wt%, the chemical stability of the glass deteriorates. The glass-ceramic material is more susceptible to attack when performing the plating required to form it.

Further, B ₂ O ₃ has an effect of lowering the glass softening point, but if it exceeds 10 wt%, the softening point is too low, and the reaction with Ag becomes intense. This causes a decrease in conductivity and a decrease in insulation resistance of the glass ceramic material. Further, MeO is related to the crystallinity of the glass material at the time of firing, and the content is optimally 25 to 50% by weight, but this is a more preferable example and is not limited. Other components can be added as long as the characteristics are not significantly impaired, and examples thereof include Al ₂ O ₃ , La ₂ O ₃ , Sn ₂ O ₃ , P ₂ O ₃ , and K ₂ O.

  Next, the preparation of the ceramic powder to be an inorganic filler, the starting material is weighed to have a predetermined composition, mixed with pure water in a mixing facility such as a ball mill, and the mixed ceramic slurry is dried by a dryer, The powder was calcined at 1300 to 1500 ° C. in an electric furnace, and the calcined ceramic powder was pulverized together with pure water by a pulverizing equipment such as a ball mill until the average particle diameter became 1 μm, and then dried by a drier.

  The glass powder was prepared by weighing the starting materials so as to have a predetermined composition, mixing the starting materials with pure water in a mixing facility such as a ball mill, drying the mixed slurry, melting in an electric furnace, quenching, and then crushing. And pulverized to an average particle size of 1 μm.

  These ceramic powder and glass powder were mixed with pure water in a mixing facility such as a ball mill, and dried with a dryer to produce a glass ceramic material.

(Example 1)
A further specific example of the above embodiment will be described in detail.

  In Example 1, a conductive paste having a composition shown in (Table 1) was prepared, a ceramic multilayer substrate 10 was prepared based on the method for preparing the ceramic multilayer substrate 10, and the inner layer electrode 2 and the ceramic multilayer substrate 10 were evaluated. went. Note that the glass ceramic material used here is No. 3 shown in (Table 3). 32 compositions were used.

  As the evaluation items, the viscosity of the conductive paste, the continuous printability, the defect at the peripheral portion of the inner electrode 2 after firing, the conductor resistance, the fine line property, and the adhesion strength of the external electrode were evaluated.

  Regarding the evaluation of the defect around the inner layer electrode 2, a laminate of the ceramic green sheets 1 in which four fine lines of line / space = 50 μm / 50 μm were laminated via the ceramic green sheet 1 having a thickness of 25 μm was prepared. After firing by the manufacturing method described in the embodiment, the cross section of the ceramic multilayer substrate 10 was polished, and the presence or absence of defects or cracks around the inner layer electrode 2 was observed using a metal microscope.

  Further, regarding the fine line property, 30 fine lines having a line / space of 50 μm / 50 μm and a length of 15 mm were printed and formed as inner layer electrodes 2 on a ceramic green sheet 1 having a thickness of 25 μm and fired in the same manner as in the above-described manufacturing method. After that, evaluation was made from short-circuit failure or disconnection failure of the inner electrode 2.

  The continuous printability of the fine line is determined by observing with a metallographic microscope whether or not the pattern has collapsed when a fine line having a line / space of 20 μm / 20 μm is continuously printed 100 times without wiping on the ceramic green sheet 1 having a thickness of 25 μm. did.

  Regarding the adhesion strength of the external electrode, a lead wire was soldered to a 2 mm × 2 mm square surface layer electrode formed by simultaneous firing, and a tensile test was performed in a direction perpendicular to the glass ceramic substrate, and the electrode was broken. The test force at that time was measured.

  The evaluation results are shown in (Table 2), (Table 4) and (Table 5).

  From the results of (Table 2), it is found that No. 2 containing no molybdenum compound. When the paste No. 1 was used, a defect 9 occurred around the inner layer electrode 7 after firing as shown in FIG. When any other molybdenum compound was added, the above defect 9 did not occur. No. 3 in which the addition amount was further increased. In the case of No. 6, a reaction layer was formed at the interface between the inner layer electrode 7 and the glass ceramic layer 6, and the conductor resistance value also increased and changed.

  Also, from the results in Table 4, the paste in which the Ag-based powder 12 is coated with the metal oxide 13 having a higher melting point than Ag and the metal compound 14 having a lower melting point than the metal oxide also has a moderate shrinkage rate during sintering. No defect 9 occurred around the inner electrode 7 after firing.

  Further, from the results of (Table 5), it is found that No. As compared with the case where the paste No. 1 was used, the paste to which the molybdenum compound was added greatly improved the adhesion strength of the external electrode.

  Good results were obtained not only for oxides but also for metal Mo, silicides and organic compounds.

  Next, in the case of No. 3 in which the content of the conductive particles was less than 70 wt%. In No. 18, the number of disconnection failures significantly increased. However, when the content of the conductive particles was 70 to 95 wt%, no disconnection failure occurred. Further, in the case of No. 1 in which the content of the conductive particles exceeds 95 wt%. 14 also showed an increase in disconnection failure.

  In addition, the conductive particles had an average particle size of less than 0.1 μm. In No. 19, a structural defect occurred, and No. 19 was larger than 3 μm. No. 23 resulted in frequent disconnection defects. The reason for this is that if the particle size is too small, the inner electrode 2 shrinks faster than the ceramic green sheet 1. This is because a crack occurs in the layer 6. Conversely, if the particle size is too large, the printability deteriorates, and the disconnection failure rate increases after firing. Therefore, it is preferable to use conductive particles having an average particle size of 0.1 to 3 μm.

  In addition, as for the Ag-based powder, a good result was obtained by using a powder mixture with Pd in addition to Ag alone. Examples of metals other than Ag include metals generally having relatively low conductor resistance, such as Pt, Au, and Cu, in addition to Pd. Further, an alloy powder with these metals may be used.

Next, the measured value at a viscosity of 0.2 s ^-1 at 25 ° C. was less than 300 Pa · s. In No. 24, the number of short-circuit defects increased, and the measured value at 20 s ^-1 exceeded 150 Pa · s. In No. 25, disconnection failure occurred frequently due to poor printability of the fine line. Further, it can be understood that the conductive paste having a characteristic value of 1200 Pa · s or more measured at 0.2 s ⁻¹ has very little pattern collapse during continuous printing.

(Example 2)
In Example 2, a glass ceramic material having the composition shown in (Table 3) was prepared, a plurality of ceramic green sheets 1 were laminated and pressed, and then a 15 mmφ disk and a 5 mm × 30 mm rectangular plate were punched out, and an electric furnace was manufactured. Then, a sintered body of the glass ceramic material alone was produced by firing. Ag electrodes were formed on both main surfaces of the produced sintered body of the disc, and the relative permittivity (εr) and the dielectric loss were measured with an LCR meter. After the rectangular body was polished, the bending strength was measured by a four-point bending method. The results are shown in (Table 3).

  As shown in Table 3, it can be seen that these glass ceramic materials have low loss and high strength characteristics.

The glass here was produced by melting 45% by weight of SiO ₂ , 5% by weight of B ₂ O ₃ , 15% by weight of BaO, 20% by weight of CaO, and 5% by weight of SrO (40% by weight as MeO) at 1450 ° C. What was used was used. This glass has a softening point of 820 ° C.

  Next, the glass ceramic material of (Table 3) and the No. 1 of (Table 1) were used. Using the conductive paste of No. 4, a ceramic multilayer substrate 10 was manufactured in the same manufacturing method as in the embodiment.

  With any of the glass ceramic materials, when a pattern such as the inner layer electrode 2 having fine lines is laminated at a high density, no defects or cracks occur around the inner layer electrode 2 and a highly reliable ceramic multilayer substrate 10 is obtained. Was done. In addition, these ceramic multilayer substrates 10 were extremely high-precision ceramic multilayer substrates 10 with a dimensional accuracy in the plane direction of 1% or less and a flatness as small as 100 μm or less per 100 mm × 100 mm substrate area.

  The conductive paste and the ceramic multilayer substrate using the same according to the present invention make it possible to obtain a ceramic multilayer substrate having high precision and high flatness, and having excellent high-frequency characteristics and a ceramic multilayer substrate having excellent mounting reliability. The present invention is useful as a ceramic multilayer substrate used for a multilayer ceramic electronic component and a conductive paste used for manufacturing the same.

Sectional view of a ceramic multilayer substrate according to an embodiment of the present invention. Sectional view of the same ceramic green sheet laminate Sectional drawing for explaining an example of the defect of the peripheral part of the inner layer electrode Sectional view for explaining an example of an Ag-based powder coated with the same metal oxide Sectional view for explaining another example of the Ag-based powder coated with the same metal oxide Sectional drawing for demonstrating another example of the Ag type powder coat | covered with the same metal oxide. Sectional view for explaining an example of an Ag-based powder coated with the same metal oxide and metal compound Sectional view for explaining another example of the Ag-based powder coated with the metal oxide and the metal compound. Sectional drawing for demonstrating another example of the Ag type powder coat | covered with the same metal oxide and a metal compound. Sectional drawing for demonstrating another example of the Ag type powder coat | covered with the same metal oxide. Sectional drawing for demonstrating another example of the Ag type powder coat | covered with the same metal oxide and a metal compound.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Ceramic green sheet 2 Inner layer electrode 3 Via electrode 4 Surface layer electrode 5 Constraining layer 6 Glass ceramic layer 7 Inner layer electrode 8 Via electrode 9 Defect 10 Ceramic multilayer board 11 Ceramic green sheet laminated body 12 Metal powder mainly composed of Ag or Ag 13 Metal oxide 14 Metal compound

Claims (11)

A conductive paste containing Ag or a metal powder containing Ag as a main component and having a surface coated with a metal oxide having a melting point higher than Ag, a molybdenum compound, and at least an organic vehicle. Conductive paste according to claim 1 containing 0.1 to 5 wt% in terms of MoO ₃ to the total amount of the organic vehicle and conductive particles molybdenum compound. Ag or a metal powder containing Ag as a main component, at least conductive particles coated with at least two kinds of metal oxide having a higher melting point than Ag and a metal compound having a lower melting point than the metal oxide, and at least an organic vehicle. A conductive paste containing a molybdenum compound in an amount of 0 to 5% by weight in terms of MoO _{3 based} on the total amount of the organic vehicle and the conductive particles. The conductive paste according to claim 1, wherein the conductive particles have an average particle size of 0.1 to 3 μm. The conductive paste according to claim 1, comprising at least 5 to 30% by weight of an organic vehicle and 70 to 95% by weight of conductive particles. 4. The conductive paste according to claim 1, wherein the viscosity at 25 ° C. is 1200 Pa · s or more when the shear rate is 0.2 s ⁻¹ . The conductive paste according to claim 1, wherein the viscosity at 25 ° C. is 300 Pa · s or more at a shear rate of 0.2 s ⁻¹ and 150 Pa · s or less at a shear rate of 20 s ⁻¹ . A wiring pattern is formed on a ceramic green sheet made of a glass ceramic material, a plurality of the ceramic green sheets are stacked, and a constraining layer made of a ceramic material that is not sintered at the firing temperature of the ceramic green sheet laminate is stacked on both main surfaces thereof. A ceramic multi-layer substrate manufactured by firing the ceramic green sheet laminate and removing the constraining layer after firing, wherein at least a part or all of the wiring pattern is according to any one of claims 1 to 7. A ceramic multilayer substrate formed from the conductive paste described above. A wiring pattern is formed on a ceramic green sheet made of a glass ceramic material, a plurality of the ceramic green sheets are stacked, and a constraining layer made of a ceramic material that is not sintered at the firing temperature of the ceramic green sheet laminate is stacked on both main surfaces thereof. A ceramic multilayer substrate manufactured by firing the ceramic green sheet laminate and removing the constraining layer after firing, wherein at least the front surface and / or the back surface or / and the side wiring pattern are formed. A ceramic multilayer substrate formed from the conductive paste according to any one of the above. The glass ceramic material is Al ₂ O ₃ , MgO, ROa (R is at least one element selected from La, Ce, Pr, Nd, Sm and Gd, and a is stoichiometric according to the valence of R. 10. The ceramic multilayer substrate according to claim 8, comprising a dielectric ceramic component containing at least (a numerical value defined in (1)) and an alkaline earth silicate-based glass component. Salt-based glass alkaline earth silicate the SiO ₂ 40 to 50 wt%, the B ₂ O ₃ 0 wt%, MeO (Me is Ba, Ca, at least one or more selected from Sr) 25 to 50 weight The ceramic multilayer substrate according to claim 10, wherein the ceramic multilayer substrate has a composition containing 0.1%.

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