JP2008004514A - Conductive paste, and manufacturing method of ceramic multilayer board using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide conductive paste suitable for forming an interlayer connection conductor provided for a ceramic multilayer board manufactured by using a so-called nonshrink process. <P>SOLUTION: This conductive paste contains an inorganic constituent and an organic constituent. In the conductive paste, the inorganic constituent contains silver powder, and additive powder containing alumina and/or anorthite; D<SB>050</SB>, D<SB>min</SB>and a specific surface area of the silver powder are 3-6 μm, not smaller than 1.5 μm and not larger than 0.3 m<SP>2</SP>/g, respectively; D<SB>050</SB>of the additive powder is not larger than 1.0 μm; the content of the silver powder is 85-95 wt.%; and the content of the additive powder is 0.2-1.0 wt.%. This conductive paste is advantageously used for forming non-sintered conductor patterns 3 and 4 formed in relation to a non-sintered ceramic base material layer 1 in a composite layered product 8 manufactured for obtaining a ceramic multilayer board. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductive paste containing silver powder, and a method for producing a ceramic multilayer substrate, which is carried out using the conductive paste for forming a conductor pattern.

  A glass ceramic multilayer substrate has a glass ceramic laminate formed by laminating a glass component and a plurality of glass ceramic layers containing the ceramic component, and a conductor pattern formed on the surface or inside of the glass ceramic laminate. . As this conductor pattern, there are an in-plane conductor extending in the plane direction of the glass ceramic layer and an interlayer connection conductor (typically a via hole conductor) extending so as to penetrate the glass ceramic layer.

  In general, such a glass-ceramic multilayer substrate mounts surface-mounted components such as semiconductor devices and chip multilayer capacitors, and interconnects each surface-mounted component. In addition, passive components such as capacitors and inductors may be built in the glass-ceramic multilayer substrate, and these passive elements are constituted by the above-mentioned in-plane conductors and interlayer connection conductors. Each surface mount component and the built-in passive element are connected.

  In order to make a glass ceramic multilayer substrate more multifunctional, highly functional, and high performance, it is necessary to form the above-described conductor pattern with high accuracy and high density.

  By the way, in order to obtain a glass ceramic multilayer substrate, an unsintered ceramic laminate formed by laminating glass ceramic green sheets must be fired. In this firing step, the glass ceramic green sheet shrinks with the disappearance of the organic binder contained in the green sheet or the sintering of the ceramic powder. Therefore, a dimensional error due to shrinkage variation may occur in the planar direction of the glass ceramic multilayer substrate.

  As a result, undesired deformation or distortion occurs in the conductor pattern, and more specifically, the positional accuracy of the in-plane conductor and the interlayer connection conductor is lowered, and the in-plane conductor and the interlayer connection conductor are disconnected. There is. Such deformation and distortion in the conductor pattern are the main causes that hinder the high density of the conductor pattern.

  Therefore, for example, in manufacturing a ceramic multilayer substrate, a so-called non-shrink process has been proposed that does not cause firing shrinkage in the plane direction of the ceramic multilayer substrate (see, for example, Patent Document 1).

In this non-shrinking process, a glass ceramic green sheet for a substrate mainly comprising glass ceramic powder obtained by mixing glass powder such as borosilicate glass with ceramic powder such as Al ₂ O ₃ is prepared, and Al ₂ A ceramic green sheet for an auxiliary layer (shrinkage suppression layer) mainly composed of O ₃ powder is prepared. Then, after in-plane conductors and interlayer connection conductors are formed on the glass ceramic green sheet for substrates, these are laminated to produce a green glass ceramic laminate, and then both the upper and lower main parts of this glass ceramic laminate An auxiliary layer ceramic green sheet is disposed on the surface, and these are pressure-bonded to produce a composite laminate.

The composite laminate thus obtained is subjected to heat treatment to remove organic components such as an organic binder contained in each green sheet, and then the temperature at which the glass ceramic green sheet is sintered, that is, the glass ceramic powder. Is fired at a temperature for sintering. In this firing step, since the Al ₂ O ₃ powder contained in the ceramic green sheet for the auxiliary layer is not substantially sintered, the ceramic green sheet for the auxiliary layer is not substantially shrunk, and the upper and lower sides of the glass ceramic laminate are both upper and lower. A restraining force is exerted on the main surface. From this, the shrinkage | contraction of the plane direction of a glass-ceramic laminated body is suppressed substantially, and a glass-ceramic laminated body shrink | contracts substantially only in the thickness direction. After the firing step, by removing the porous layer of Al ₂ O ₃ powder from the ceramic green sheet for the auxiliary layer, a glass ceramic laminate formed by sintering, i.e. a glass ceramic multilayer substrate is taken out.

  According to the non-shrink process described above, the dimensional accuracy of the laminated glass ceramic green sheets is maintained in the planar direction, so that non-uniform deformation is unlikely to occur, and undesired deformation or distortion of the conductor pattern is caused. Therefore, it is possible to obtain a glass ceramic multilayer substrate having a highly reliable conductor pattern which is difficult to be pulled down and formed with high accuracy.

  However, according to the above-described non-shrink process, the green glass ceramic laminate does not substantially shrink in the plane direction, but greatly shrinks in the thickness direction. Therefore, voids are generated inside the in-plane conductor or interlayer connection conductor due to the difference in sintering behavior between the in-plane conductor or interlayer connection conductor and the glass ceramic green sheet. An air gap is generated between the glass ceramic layer portion, a crack is generated in the glass ceramic layer portion around the in-plane conductor and the interlayer connection conductor, or the end portion of the interlayer connection conductor is a ceramic multilayer substrate. In some cases, the surface of the ceramic multi-layer substrate protrudes from the surface of the ceramic multi-layer substrate to form a convex shape.

  The above problems also cause the following problems.

  In other words, when voids are generated inside the in-plane conductors and interlayer connection conductors, the specific resistance values of the in-plane conductors and interlayer connection conductors increase, and in particular, the loss of signals in the high frequency band increases, resulting in the operability of semiconductor elements, etc. May deteriorate.

  In addition, if voids or cracks occur around the in-plane conductor or interlayer connection conductor, moisture penetrates from here during plating, and this moisture diffuses the conductor component contained in the in-plane conductor or interlayer connection conductor. (Typically silver) migration may occur.

  Furthermore, if moisture accumulates in the void, when the semiconductor element or chip capacitor is mounted on the substrate surface with solder after plating, the accumulated moisture evaporates due to heat generated by reflow during solder melting, and the evaporated moisture May cause a problem of so-called “solder explosion” that blows away the melted solder and short-circuits the surrounding parts. "Solder explosion" also occurs due to voids in the in-plane conductors and interlayer connection conductors.

  In addition, if the interlayer connection conductor has a convex shape on the surface of the ceramic multilayer substrate, the smoothness of the surface of the ceramic multilayer substrate is impaired. In particular, a semiconductor element or chip capacitor is mounted on the convex portion via solder. Then, the strength of the joint portion is lowered, and there is a problem that the joint portion breaks due to generally-known solder joint stress.

  The cause of these problems is the difference in firing shrinkage and firing shrinkage behavior between the conductive paste applied to form in-plane conductors and interlayer connection conductors and the unsintered glass ceramic laminate in the firing process. It seems to be greatly related. That is, if there is a large deviation in the firing shrinkage amount or firing shrinkage behavior between the unsintered glass ceramic laminate and the conductive paste, the fired ceramic multilayer substrate and the in-plane conductors and interlayer connection conductors formed therein Excessive stress and strain are generated between the above, and voids, voids, cracks as described above, and convex shapes due to interlayer connection conductors on the surface of the ceramic multilayer substrate are generated.

  By the way, in the non-shrink process described above, there is also a technique of firing while forcibly applying pressure in the laminating direction of the unsintered glass ceramic laminate (see, for example, Patent Document 2). In this way, it is considered that voids, voids, cracks, and convex shapes due to interlayer connection conductors can be suppressed by firing while forcibly applying high pressure.

In fact, according to the pressure firing as described above, generation of convex shapes due to voids, voids, cracks, and interlayer connection conductors can be suppressed. However, when trying to carry out pressure firing, not only the equipment cost for pressurization increases, but the glass in the glass ceramic green sheet tends to float on the surface of the substrate by pressurization, so glass is contained in the auxiliary layer. Since the auxiliary layer reacts violently with the Al ₂ O _{3 being used} and the auxiliary layer is unnecessarily sintered, it is difficult to remove the auxiliary layer after firing.
Japanese Patent No. 2554415 JP-A-10-84056

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a silver powder capable of suppressing the generation of voids and producing a highly reliable ceramic multilayer substrate in a so-called non-shrinking process. It is an object of the present invention to provide a conductive paste including the same and a method for manufacturing a ceramic multilayer substrate using the same.

The conductive paste according to the present invention includes an inorganic component and an organic component. The inorganic component includes silver powder and an additive powder containing alumina and / or anorthite. Silver powder has an integrated 50% particle size (D ₀₅₀ ) of 3 to 6 μm, an integrated minimum particle size (D _min ) of 1.5 μm or more, and a specific surface area (SSA) of 0.3 m ² / g or less. The product powder has an integrated 50% particle size (D ₀₅₀ ) of 1.0 μm or less. Moreover, content of silver powder is 85 to 95 weight%, and content of additive powder is 0.2 to 1.0 weight%.

In the conductive paste according to the present invention, the silver powder has an accumulated 50% particle diameter (D ₀₅₀ ) of 3.5 to 5 μm and an accumulated minimum particle diameter (D _min ) of 2 μm or more, and the content of the additive powder Is preferably 0.2 to 0.8% by weight.

  The silver powder is preferably spherical.

  The present invention is also directed to a method for manufacturing a ceramic multilayer substrate, which is performed using the above-described conductive paste.

  The method for producing a ceramic multilayer substrate according to the present invention comprises a plurality of unsintered ceramic base layers and a non-sintered conductor pattern provided in association with the unsintered ceramic base layers. Inhibition of shrinkage, provided to be in contact with the unsintered ceramic laminate and unsintered ceramic substrate layer, and does not substantially sinter at the temperature at which the unsintered ceramic substrate layer and unsintered conductor pattern sinter And a step of producing a composite laminate including a layer, and a temperature at which the shrinkage suppression layer is not substantially sintered and the unsintered ceramic base layer and the unsintered conductor pattern are sintered. A step of firing, wherein the unsintered conductor pattern is formed by the conductive paste according to the present invention described above.

  In the firing step described above, it is preferable to fire the composite laminate without forcible pressurization.

Moreover, it is preferable that an unsintered ceramic base material layer is provided with the green sheet for base material layers comprised including a ceramic powder and glass powder. In this case, the green sheet for the base layer includes CaO—Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ glass powder and Al ₂ O ₃ ceramic powder, while the shrinkage suppression layer is Al ₂ O _3. The ceramic ceramic powder is preferably included.

  Further, in the composite laminate, when the shrinkage suppression layers are located on both main surfaces of the unsintered ceramic laminate, a step of removing the shrinkage suppression layer is further performed after the firing step. On the other hand, in the composite laminate, the shrinkage suppression layer may be located between a plurality of unsintered ceramic base layers.

  The method for manufacturing a ceramic multilayer substrate according to the present invention may further include a step of mounting a surface mount component.

  In a method for manufacturing a ceramic multilayer substrate implemented by applying a so-called shrinkless process, when the conductive paste according to the present invention is used to form a conductor pattern such as an in-plane conductor or an interlayer connection conductor, the conductor pattern It is possible to eliminate defects such as internal voids, to generate cracks and voids in the ceramic portion around the conductor pattern, and to eliminate defects such as convex shapes due to interlayer connection conductors.

  That is, according to the conductive paste of the above composition according to the present invention, when firing the ceramic multilayer substrate, the inorganic component of the inorganic component is adjusted so that the firing shrinkage behavior of the thick film conductor pattern by the conductive paste matches the firing shrinkage behavior of the ceramic. Since the composition is adjusted, defects such as internal voids in in-plane conductors and interlayer connection conductors are eliminated, cracks and voids are generated in the ceramic area around in-plane conductors and interlayer connection conductors, and interlayer connections Defects such as a convex shape due to the conductor can be eliminated.

  More specifically, since the particle size, particle size distribution and specific surface area of the silver powder are specified, and the composition and particle size of the additive powder are specified, the alumina powder or anorthite powder which is the additive powder Is held as the core of the conductor pattern during firing, so that sintering (necking) between the silver powders is controlled, and the additive powder containing the added alumina and / or anorthite is further added to the ceramic base layer, In particular, by diffusing into the glass of the ceramic substrate layer, it is possible to suppress the softening shrinkage of the glass around the thick film conductor pattern, and within the firing shrinkage temperature range of the unfired ceramic substrate layer, The conductor pattern follows the firing shrinkage, eliminates defects such as internal voids in the in-plane conductor and interlayer connection conductor, and cracks and voids in the ceramic area around the in-plane conductor and interlayer connection conductor In addition, defects such as convex shapes due to interlayer connection conductors can be eliminated, and a highly reliable conductor pattern such as an in-plane conductor or interlayer connection conductor can be formed inside the ceramic multilayer substrate. .

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that defects such as voids in the in-plane conductors and interlayer connection conductors in the ceramic multilayer substrate manufactured by applying a so-called shrink-free process. In addition, in order to eliminate the occurrence of cracks and voids around the in-plane conductors and interlayer connection conductors, and unwanted defects such as convex shapes due to interlayer connection conductors,
(1) Compared to the unsintered ceramic base layer, the sintering temperature of the conductive paste for the interlayer connection conductor, the sintering start temperature, etc. should not be too low.
(2) During firing, the difference in softening temperature between the ceramic around the in-plane conductor / interlayer connection conductor and the ceramic in the other part and the difference in the speed of softening should not occur.
For that purpose, among the inorganic components contained in the conductive paste for forming the in-plane conductor and the interlayer connection conductor, it is necessary to specify the particle size and content of the silver powder, and the additive type, etc. I came to find out.

That is, the conductive paste according to the present invention has, as an inorganic component, an integrated 50% particle size (D ₀₅₀ ) of 3 to 10 μm, an integrated minimum particle size (D _min ) of 1.5 μm or more, and a specific surface area (SSA). Is contained in an amount of 85 to 95% by weight of silver powder having a particle size of 0.3 m ² / g or less, and 0.2 to 1.0% by weight of additive powder containing alumina and / or anorthite having a D ₀₅₀ of 1.0 μm or less. It is characterized by containing.

  According to the conductive paste of the present invention, during the firing cycle, in the temperature region lower than the sintering temperature of the ceramic multilayer substrate, the unsintered ceramic substrate layer does not sinter and shrink, and the silver powder is alumina powder or the like. Since the additive powder is present between the silver powders, the sintering is suppressed. In the vicinity of the sintering temperature of the ceramic multilayer substrate, the unsintered ceramic base material layer starts sintering shrinkage, and accordingly, the unsintered conductor pattern for forming in-plane conductors, interlayer connection conductors, etc. The volume also shrinks. At this time, silver powder is in a state where silver powder can move relatively freely because additive powder such as alumina powder is present between the silver powders, thus preventing silver sintering (necking). The volume shrinkage of the unsintered conductor pattern occurs following the sintering shrinkage of the unsintered ceramic base layer. Further, at this time, the additive powder particles such as added alumina are contained in the ceramic around the conductor pattern. The particles are dissolved in the ceramic glass, and the softening of the glass is suppressed, and the non-uniformity of the softened state of the ceramic in the ceramic multilayer substrate is alleviated. For this reason, it is possible to eliminate the occurrence of cracks and voids in the ceramic portion around the in-plane conductor and the interlayer connection conductor, and defects such as a convex shape due to the interlayer connection conductor.

  Hereinafter, the conductive paste according to the present invention will be described in more detail.

  As a conductive material in the conductive paste, silver which is a low resistance and hardly oxidizable material is used. The silver is preferably pure silver, but may contain a very small amount of platinum or palladium.

Silver powder in the conductive paste according to the present _invention, it is necessary that _{D 050} is 3 to 6 [mu] m, is preferably 3.5～5Myuemu.

When D ₀₅₀ is less than 3 μm, sintering starts from the low temperature region side regardless of additives such as alumina powder, and the volume shrinkage of the conductor pattern also increases. The timing is greatly deviated, and defects such as voids and voids are likely to occur inside the obtained in-plane conductor and interlayer connection conductor. Further, if _D050 is less than 3 μm, the amount of diffusion of silver into the ceramic increases, so that the softening and shrinkage of the ceramic in the vicinity of the in-plane conductor and interlayer connection conductor is accelerated, and voids are formed in the vicinity of the in-plane conductor and interlayer connection conductor. Is likely to occur.

In addition, the phenomenon that the softening of the glass due to the diffusion of silver is accelerated is that, when silver diffuses into the ceramic glass, the silver enters the lattice of SiO ₂ constituting the glass and cuts the bond of SiO _2. It is believed that.

On the other hand, if D ₀₅₀ is larger than 6 μm, sintering of the in-plane conductor and the interlayer connection conductor is difficult to proceed, and it becomes impossible to follow the shrinkage amount of the ceramic in the thickness direction, and voids are generated inside the interlayer connection conductor. Can be seen. Also, printability is reduced.

Further, even when D ₀₅₀ is within the above appropriate range, when a large amount of silver powder having a small particle diameter is contained, silver is likely to diffuse in the vicinity of the in-plane conductor and the interlayer connection conductor. Since it melts in the ceramic glass near the interlayer connection conductor and promotes softening and shrinkage of the ceramic, voids are likely to occur in the vicinity of the in-plane conductor / interlayer connection conductor. From this, _Dmin needs to be 1.5 μm or more, and preferably 2 μm or more.

Similarly, even when D ₀₅₀ is within the above appropriate range, when the SSA becomes a silver powder larger than 0.3 m ² / g, the ratio of the glass softened during firing to contact with the in-plane conductor / interlayer connection conductor increases. Silver easily diffuses and dissolves in the ceramic glass near the in-plane conductor / interlayer connection conductor to promote softening and shrinkage of the ceramic, so that voids are likely to occur near the in-plane conductor / interlayer connection conductor. Therefore, SSA needs to be 0.3 m ² / g or less.

In addition, in order to make SSA of silver powder 0.3 m < ² > / g or less, it is preferable that silver powder is a spherical shape which can make SSA smaller further.

The particle diameters D ₀₅₀ and D _min of the silver powder and the additive powder described later can be calculated by measuring with a laser particle size distribution measuring device, for example. Further, SSA of silver powder is determined by the BET method.

  Content of the silver powder contained in an electrically conductive paste needs to be 85 to 95 weight%.

  When the content of the silver powder is less than 85% by weight, if the conductive paste is used for the interlayer connection conductor, the filling amount of the conductive material in the hole for receiving the interlayer connection conductor is reduced. In the vicinity of the center in the thickness direction of the multilayer substrate where the influence of the force is small, the ceramic base material layer locally shrinks in the plane direction during firing and is easily peeled off at the boundary with the interlayer connection conductor.

  On the other hand, when the content of silver powder is more than 95% by weight, when the ceramic base material layer shrinks in the thickness direction during firing, the conductive paste cannot follow, and the interlayer connection conductor protrudes from the surface of the ceramic multilayer substrate. The ceramic multilayer substrate is easily damaged.

  Therefore, the content of the silver powder contained in the conductive paste needs to be 85 to 95% by weight, and more preferably in the range of 88 to 92% by weight.

In addition, it is desirable that the silver powder as the main component powder has no coarse powder or extremely agglomerated powder, and the particle diameter (D _max ) of the maximum coarse particles after making the conductive paste is 50 μm or less.

The conductive paste contains additive powder containing alumina (Al ₂ O ₃ ) and / or anorsite (CaAl ₂ Si ₂ O ₈ ) in addition to the main component silver powder.

The average particle diameter D ₀₅₀ of the additive powder needs to be 1.0 μm or less. When the average particle size is larger than 1.0 μm, these additives are not diffused into the glass during firing, and the main component silver is preferentially diffused into the glass, and as a result, the additive is contained in the conductor. Since the proportion occupied increases and the conductor resistance value increases, the electrical conductivity and thermal conductivity decrease.

  Further, the content of the additive powder is required to be 0.2 to 1.0% by weight, and preferably 0.2 to 0.8% by weight.

  When the content of the additive powder is less than 0.2% by weight, the additive powder becomes less reactive with the glass in the ceramic, so that the effect of suppressing the softening of the ceramic cannot be sufficiently obtained, and the shrinkage Since the suppression effect cannot be obtained sufficiently, the generation of voids in the vicinity of the in-plane conductor / interlayer connection conductor cannot be suppressed.

  On the other hand, if the content of the additive powder is more than 1.0% by weight, the conductor and the ceramic do not shrink due to unnecessarily preventing the shrinkage during sintering of the conductor, and the conductor and the ceramic peel off during firing. It becomes easy. Therefore, between the in-plane conductor and the ceramic base layer, and between the interlayer connection conductor and the surrounding ceramic base layer, that is, accept the interlayer connection conductor on the outer peripheral surface of the interlayer connection conductor and the ceramic base layer side. An air gap occurs between the inner peripheral surface defining the hole, a crack occurs in the ceramic base layer around the in-plane conductor / interlayer connection conductor, or the end of the interlayer connection conductor is a ceramic multilayer It protrudes from the surface of the substrate, and further, the embedded interlayer connection conductor pushes up the ceramic layer and tends to give a convex shape to this surface.

  In addition, when the average particle diameter of the additive powder is less than 0.01 μm, the specific surface area becomes large, aggregation of the additive powders proceeds, and the additive powder does not diffuse uniformly in the conductive paste. There is. As a result, the additive is not sufficiently diffused in the vicinity of the in-plane conductor / interlayer connection conductor, so that the softening of the ceramic cannot be suppressed and the generation of voids in the vicinity of the in-plane conductor / interlayer connection conductor cannot be suppressed. is there. From this, the average particle size of the additive powder is preferably 0.01 μm or more.

  The conductive paste according to the present invention is prepared by adding a predetermined amount of an organic vehicle as an organic component at a predetermined ratio to the above inorganic component, and stirring and kneading, that is, the above inorganic component is A paste-like composition uniformly dispersed together with a binder and a solvent constituting an organic binder.

  As the binder contained in the organic vehicle, for example, ethyl cellulose, alkyd resin, acrylic resin, polyvinyl butyral, methacrylic resin, or the like can be used. As the solvent contained in the organic vehicle, for example, terpineol, dihydroterpineol, dihydroterpineol acetate, butyl carbitol, butyl carbitol acetate, octanediol, texanol, alcohols and the like can be used. Moreover, you may add various dispersing agents, a plasticizer, an activator, etc. to an electrically conductive paste as needed.

  The viscosity of the conductive paste is preferably 50 to 700 Pa · s in consideration of printability.

  Hereinafter, an embodiment of a method for producing a ceramic multilayer substrate according to the present invention will be described with reference to the sectional views of FIGS.

  First, as shown in FIG. 1, a green sheet 1a for a base material layer to be an unsintered ceramic base material layer 1 (see FIG. 2) is prepared. The base layer green sheet 1a is prepared by, for example, preparing a slurry by dispersing a glass-ceramic raw material mixture in an organic vehicle composed of an organic binder, an organic solvent, a plasticizer, and the like. It is manufactured by forming into a sheet shape by a blade method or a casting method.

Specifically, the glass ceramic raw material mixture includes CaO: 10 to 55 wt%, SiO ₂ : 35 to 70 wt%, Al ₂ O ₃ : 0 to 30 wt%, impurities: 0 to 10 wt%, and B ₂ O ₃ : Glass powder having a composition of 5 to 20% by weight: 50 to 64% by weight and Al ₂ O ₃ powder having impurities of 0 to 10% by weight: 35 to 50% by weight are used. .

  The unsintered ceramic base layer 1 is preferably provided by the green sheet 1a formed by the above-described sheet forming method, but is provided by the unsintered thick film printed layer formed by the thick film printing method. May be.

In addition, the ceramic powder contained in the base layer green sheet 1a includes a dielectric material such as a powder made of a magnetic material such as ferrite, a dielectric material such as barium titanate, in addition to the insulating material powder such as the Al ₂ O ₃ powder described above. It is also possible to use powder made of body material. In any case, it is preferable that the green sheet 1a for the base material layer is sintered at a temperature of 1050 ° C. or lower. For this reason, the glass powder described above has a softening point of 750 ° C. or lower. It is preferable.

  Next, referring also to FIG. 1, interlayer connection conductor holes 2 are formed in the base layer green sheet 1 a by punching or laser processing. Then, the interlayer connection conductor hole 2 is filled with the conductive paste according to the present invention, and the unsintered interlayer connection conductor 3 is formed. Subsequently, the unsintered in-plane conductor 4 is formed by printing the electroconductive paste which concerns on this invention on the green sheet 1a for base materials by the screen printing method, the gravure printing method, etc. In the illustrated embodiment, some of the in-plane conductors 4 are formed on a shrinkage suppression layer green sheet 5a described later.

  When applying the so-called non-shrink process, the ceramic laminate shrinks greatly in the thickness direction (roughly shrinks by about 45 to 55%) instead of substantially shrinking in the plane direction due to firing. It is important to match the firing shrinkage behavior of the interlayer connection conductor with the firing shrinkage behavior of the ceramic laminate. Therefore, the conductive paste according to the present invention is particularly advantageously used for forming an interlayer connection conductor (via hole conductor) provided in a ceramic multilayer substrate.

  Therefore, when the conductive paste according to the present invention is used to form the interlayer connection conductor, the in-plane conductor does not necessarily need to use the conductive paste according to the present invention. An in-plane conductor can be formed by a method such as transferring a metal foil having a predetermined shape.

  On the other hand, similarly as shown in FIG. 1, a green sheet 5a for a shrinkage suppression layer to be the shrinkage suppression layer 5 (see FIG. 2) is prepared. The shrinkage-suppressing layer green sheet 5a is made of ceramic powder such as alumina that is not substantially sintered at a temperature at which the base layer green sheet 1a and the unsintered interlayer connection conductor 3 and in-plane conductor 4 are sintered. Is included. The green sheet 5a for the shrinkage suppression layer is prepared by dispersing ceramic powder in an organic vehicle composed of an organic binder, an organic solvent, a plasticizer, and the like, and preparing the slurry by using a doctor blade method or a casting method. It is produced by molding into a shape. The sintering temperature of the shrinkage suppression layer green sheet 5a is, for example, 1400 to 1600 ° C., and the sintering temperature of the base material layer green sheet 1a is not substantially sintered.

  In addition, it is preferable that the average particle diameter of the ceramic powder contained in the green sheet 5a for shrinkage | contraction suppression layers is 0.1-5.0 micrometers.

  When the average particle size of the ceramic powder in the green sheet 5a for shrinkage suppression is less than 0.1 μm, the ceramic powder is intensely mixed with the glass contained in the vicinity of the surface of the ceramic base layer 1 in the firing step described later. The ceramic base material layer 1 and the shrinkage suppression layer 5 adhere to each other after firing and the shrinkage suppression layer 5 cannot be removed, or the organic components such as a binder in the sheet are fired due to the small particle size. In the process, decomposition and scattering are difficult, and therefore delamination may occur in the obtained ceramic multilayer substrate 6 (see FIG. 4).

  On the other hand, when the average particle size of the ceramic powder in the green sheet 5a for the shrinkage suppression layer exceeds 5.0 μm, the firing shrinkage suppression force becomes small, and the ceramic multilayer substrate 6 shrinks or swells in the plane direction. There is a tendency.

  Further, as described above, the ceramic powder in the green sheet 5a for the shrinkage suppression layer is substantially sintered at a temperature at which the unsintered ceramic base material layer 1, the interlayer connection conductor 3, and the in-plane conductor 4 are sintered. In addition to alumina, ceramic powder made of zirconia, magnesia or the like can also be used. However, in order to allow a large amount of glass to be present in the surface layer region of the unsintered ceramic base material layer 1, the surface glass is suitable for the shrinkage suppression layer 5 at the boundary where the surface layer and the shrinkage suppression layer 5 are in contact with each other. Therefore, the ceramic powder in the green sheet 5a for shrinkage suppression layer is preferably the same type as the ceramic powder contained in the unsintered ceramic base layer 1.

  Next, a plurality of green sheets 1a for base material layers each formed with a conductor pattern such as an interlayer connection conductor 3 and an in-plane conductor 4 are laminated to produce a green ceramic laminate 7 as shown in FIG. Is done. In the ceramic laminate 7, the base layer green sheet 1 a constitutes the unsintered ceramic base layer 1. Moreover, the green sheet 5a for shrinkage | contraction suppression layers is superimposed on each of the one main surface and the other main surface of the unsintered ceramic multilayer body 7, whereby the one main surface and the other main surface of the ceramic multilayer body 7 are overlapped. The shrinkage | contraction suppression layer 5 is formed along. The composite laminate 8 obtained in this way is pressure-bonded by a hydrostatic press or the like under a pressure of 5 to 200 MPa, for example.

  The thickness of the shrinkage suppression layer 5 is preferably 25 to 500 μm. When this thickness is less than 25 μm, the suppression of firing shrinkage is reduced, and the obtained ceramic multilayer substrate 6 may shrink or swell in the plane direction. On the other hand, when the thickness exceeds 500 μm, Organic components such as a binder in the shrinkage suppression layer 5 are not easily decomposed and scattered during firing, and delamination tends to occur in the obtained ceramic multilayer substrate 6.

  The shrinkage suppression layer 5 may be composed of one green sheet 5a, but may be composed by laminating a plurality of green sheets 5a.

  Next, using a well-known belt furnace or batch furnace, the shrinkage suppression layer 5 is not substantially sintered, and the unsintered ceramic base material layer 1, the unsintered interlayer connection conductor 3 and the in-plane conductor 4 are formed. The composite laminate 8 is fired at a sintering temperature, for example, a temperature of 850 to 950 ° C. The firing atmosphere is an air atmosphere, but may be a low oxygen atmosphere if necessary. Moreover, in this baking process, the composite laminated body 8 is baked without forced pressurization.

  As a result of the above-described firing step, the shrinkage suppression layer 5 is not substantially sintered in the composite laminate 8, but the ceramic base material layer 1, the interlayer connection conductor 3 and the in-plane conductor 4 constituting the ceramic laminate 7 are fired. As a result, as shown in FIG. 3, a sintered ceramic laminate 7, that is, a ceramic multilayer substrate 6 is provided between the shrinkage suppression layers 5. As can be seen from a comparison between FIG. 2 and FIG. 3, the ceramic multilayer substrate 6 after sintering is suppressed from contracting in the planar direction by the action of the shrinkage suppressing layer 5 compared to the ceramic laminate 7 before firing. ing. On the other hand, regarding the thickness direction, FIG. 2 shows the thickness T1 of the ceramic laminate 7 before firing, and FIG. 3 shows the thickness T2 of the ceramic multilayer substrate 6 after sintering. The sintered ceramic multilayer substrate 6 contracts relatively greatly in the thickness direction as compared with the ceramic laminate 7 before firing.

  Next, by removing the shrinkage suppression layer 5 from the fired composite laminate 8, the sintered ceramic multilayer substrate 6 is taken out as shown in FIG. In the composite laminate 8 after firing shown in FIG. 3, the shrinkage suppression layer 5 is not substantially sintered as described above, and the organic components contained before firing are scattered. However, since it is in a porous state, it can be easily removed by a sand blast method, a wet blast method, an ultrasonic vibration method, or the like.

  In manufacturing the ceramic multilayer substrate 6 taken out as described above, since the conductive paste according to the present invention is used to form the interlayer connection conductor 3 and the in-plane conductor 4, in the firing step, the composite laminate The ceramic multilayer substrate 6 can be obtained without any defects without forcibly pressing the body 8. Therefore, equipment costs can also be reduced.

  On the upper main surface of the ceramic multilayer substrate 6, surface mount components 11 and 12 are mounted as shown in the sectional view of FIG. One surface-mounted component 11 is a chip capacitor, for example, and is electrically connected to the in-plane conductor 4 located on the outer surface via the solder 13. The other surface mounting component 12 is, for example, a semiconductor chip, and is electrically connected to the in-plane conductor 4 located on the outer surface via the solder bumps 14.

  Instead of the in-plane conductor 4 used for electrical connection of the surface mount components 11 and 12, the end face (part exposed on the surface) of the specific interlayer connection conductor 3 itself may be used.

  Further, as shown in the cross-sectional view of FIG. 6, the ceramic multilayer substrate 6 is mounted on the mother substrate 15. At this time, the in-plane conductor 4 formed on the lower main surface of the ceramic multilayer substrate 6 is electrically connected to the conductive land 17 on the mother substrate 15 via the solder 16.

  As described above, the conductive paste according to the present invention is preferably used in a manufacturing method including a step of removing the shrinkage suppression layers 5 located on both main surfaces of the unsintered ceramic laminate 7 after firing. However, a manufacturing method that uses a glass flow between the unsintered ceramic substrate layer and the shrinkage suppression layer (for example, JP 2000-25157)).

  Below, the experiment example implemented in order to confirm the effect by this invention is demonstrated.

First, 40 parts by weight of alumina powder and 60 parts by weight of SiO ₂ (60% by weight) -B ₂ O ₃ (8% by weight) -Al ₂ O ₃ (6% by weight) -CaO (26% by weight) glass. The powder (softening point: 700 ° C.) is dispersed in an organic vehicle containing an organic binder made of acrylic resin, an organic solvent made of toluene and isopropylene alcohol, and a plasticizer made of di-n-butyl phthalate. Prepared. Subsequently, this slurry was formed into a sheet by a doctor blade method to prepare a green sheet for a base material layer having a thickness of 100 μm.

  In addition, an alumina powder (average particle size: 0.4 μm) that is not substantially sintered at the firing temperature of the green sheet for the base material layer, an organic binder composed of polyvinyl butyral, an organic solvent composed of toluene and isopropylene alcohol, and di A slurry was prepared by dispersing in an organic vehicle containing a plasticizer composed of n-butyl phthalate. Next, the slurry was formed into a sheet by a doctor blade method to produce a green sheet for a shrinkage suppression layer having a thickness of 100 μm. In addition, the sintering temperature of this green sheet for shrinkage | contraction suppression layers is 1600 degreeC.

  Moreover, as shown in Table 1, silver powder and alumina powder are made into solid content (inorganic component), and resin (ethylcellulose, alkyd resin) and solvent (terpineol) are added to this as organic components, and premixed with a stirrer Thereafter, the mixture was kneaded with a kneader to prepare conductive pastes according to samples 1 to 20. The viscosity of these conductive pastes was adjusted to be about 200 Pa · s.

  Similarly, as shown in Table 2, silver powder and anorthite powder were made into solid content (inorganic component), and resin (ethylcellulose, alkyd resin) and solvent (terpineol) were added to this as organic components, and agitator was used. Preliminary mixing was performed, and then kneading was performed using a kneader to prepare conductive pastes according to samples 21 to 23. The viscosity of these conductive pastes was adjusted to be about 200 Pa · s.

  Similarly, as shown in Table 3, silver powder and molybdenum oxide powder were made solid (inorganic component), and resin (ethylcellulose, alkyd resin) and solvent (terpineol) were added to the organic component, and this was stirred with a stirrer. Preliminary mixing was performed, and then the mixture was kneaded with a kneader to prepare a conductive paste according to each of samples 24-26. The viscosity of these conductive pastes was adjusted to be about 200 Pa · s.

  Similarly, as shown in Table 4, silver powder and borosilicate glass powder are made into a solid content (inorganic component), and resin (ethyl cellulose, alkyd resin) and a solvent (terpineol) are added thereto as an organic component, and the mixture is added to a stirrer. Then, the mixture was premixed and then kneaded with a kneader to prepare a conductive paste according to each of samples 27 to 29. The viscosity of these conductive pastes was adjusted to be about 200 Pa · s.

  Furthermore, as shown in Table 5, alumina-coated silver powder (corresponding to 0.5% by weight of alumina) was used as the silver powder, and only in samples 31 and 32, molybdenum oxide powder was added and solid content (inorganic component) The resin (ethyl cellulose, alkyd resin) and solvent (terpineol) are added as organic components to this, premixed with a stirrer, and then kneaded with a kneader to conduct the conductivity of each of the samples 30 to 32 Paste was prepared. The viscosity of these conductive pastes was adjusted to be about 200 Pa · s.

  In Samples 1 to 32 shown in Tables 1 to 5, a spherical powder was used as the silver powder. However, for the sample 20 in Table 1, a flat shape (flakes) was used. In addition, as the alumina powder, anorthite powder, molybdenum oxide powder and borosilicate glass powder, spherical ones were used.

  Next, a hole for an interlayer connection conductor having a diameter of 200 μm was formed in the green sheet for the base material layer by punching, and the conductive paste was filled in the hole by printing.

  Next, 11 green sheets for the base material layer were laminated to obtain a green ceramic laminate having a total thickness of 1.1 mm, and 3 green sheets for the shrinkage suppression layer were formed on the upper and lower main surfaces. A composite laminate was produced in which the sheets were superposed one by one and a shrinkage suppression layer having a total thickness of 0.3 mm was provided on each main surface of the unsintered ceramic laminate. Then, the composite laminate was pressed at a pressure of 100 MPa.

Next, the composite laminate was placed on an alumina setter and baked at a temperature of 900 ° C. for 1 hour in an atmosphere having a low oxygen concentration (PO ₂ : 1% or less). Then, the shrinkage | contraction suppression layer in a porous state was removed from the composite laminated body after baking by the wet blast method, and the ceramic multilayer substrate was taken out.

  About the obtained ceramic multilayer substrate according to each sample, the cross section is polished to a mirror surface, and then the maximum void in the vicinity of the interlayer connection conductor (within a distance of 30 μm from the interlayer connection conductor interface) by a SEM capable of measuring the length The diameter of was measured. The measurement results are shown in Table 6.

  Further, with respect to the ceramic multilayer substrate according to each sample, the amount of protrusion of the interlayer connection conductor was measured from the surface of the ceramic multilayer substrate using a laser three-dimensional length measuring machine. The results are also shown in Table 6.

  A sample having a maximum void diameter of 12 μm or more is determined as a failure, and a sample having an absolute value of the amount of protrusion of the interlayer connection conductor greater than 10 μm is determined as a failure. In FIG. 6, “x” was assigned to the “determination” column, and “◯” was assigned to the other samples.

In order to obtain a ceramic multilayer substrate satisfying the conditions that the maximum void diameter in the vicinity of the interlayer connection conductor is less than 12 μm and the protruding amount of the interlayer connection conductor is within the range of −10 μm to 10 μm from Table 6, the additive powder as an inorganic component is In samples 1 to 20 which are alumina powders, as in samples 2, 3, 4, 7, 8, 11, 12, 14, 15, 18 and 19, the silver powder has an integrated 50% particle size (D ₀₅₀ ). 3 to 6 μm, the cumulative minimum particle size (D _min ) is 1.5 μm or more, the specific surface area (SSA) is 0.3 m ² / g or less, and the content thereof is 85 to 95% by weight, Further, it is understood that the alumina powder needs to have an integrated 50% particle size (D ₀₅₀ ) of 1.0 μm or less and a content of 0.2 to 1.0% by weight. .

In addition, in Samples 21 to 23 in which the additive powder is anorthite powder, in order to obtain a ceramic multilayer substrate that satisfies the above conditions, as in Samples 21 and 22, the silver powder has an integrated 50% particle size (D ₀₅₀ ) is 3 to 6 μm, the cumulative minimum particle size (D _min ) is 1.5 μm or more, the specific surface area (SSA) is 0.3 m ² / g or less, and the content is 85 to 95% by weight. In addition, the anorthite powder needs to have an integrated 50% particle size (D ₀₅₀ ) of 1.0 μm or less and a content of 0.2 to 1.0% by weight. I understand that.

  On the other hand, as in sample 1, when the silver powder content in the conductive paste is less than 85% by weight, the amount of sintering shrinkage increases more than necessary, so the maximum void diameter near the interlayer connection conductor is 12 μm or more. As a result, defects were present in the ceramic multilayer substrate, the amount of protrusion of the interlayer connection conductor was less than −10 μm, and the interlayer connection conductor was recessed. This defect causes an interlayer short in the ceramic multilayer substrate.

  Further, as in Sample 5, when the silver powder content in the conductive paste is more than 95% by weight, the amount of sintering shrinkage is unnecessarily reduced. Since the conductor jumped out and the interlayer connection conductor was peeled off from the ceramic on the side wall, the maximum void diameter in the vicinity of the interlayer connection conductor was increased to 12 μm or more.

  Further, as in Sample 6, when the content of alumina powder in the conductive paste is less than 0.2% by weight, it is not possible to follow the sintering shrinkage in the thickness direction of the green sheet for the base layer, and the vicinity of the interlayer connection conductor The maximum void diameter was 12 μm or more, and defects were present in the ceramic multilayer substrate. This defect makes it easier to trap moisture during plating, and easily causes solder explosion and migration failure.

  Further, as in Sample 9, when the content of alumina powder in the conductive paste exceeds 1.0% by weight, the amount of protrusion of the interlayer connection conductor becomes larger than 10 μm, the interlayer connection conductor pops out, and the interlayer connection conductor becomes Since the ceramic on the side wall was peeled off, the maximum void diameter in the vicinity of the interlayer connection conductor was as large as 12 μm or more.

Further, as in sample 10, when the silver powder particle size (D ₀₅₀ ) in the conductive paste is less than 3 μm, the amount of silver diffusion increases, and the softening and shrinkage of the ceramic around the interlayer connection conductor proceeds rapidly. The maximum void diameter in the vicinity of the connecting conductor was 12 μm or more, and defects were present in the ceramic multilayer substrate. This defect makes it easier to trap moisture during plating, and easily causes solder explosion and migration failure.

Further, as in Sample 13, when the silver powder particle size (D ₀₅₀ ) in the conductive paste is larger than 6 μm, the sintering of the silver powder becomes too slow, and the amount of protrusion of the interlayer connection conductor becomes larger than 10 μm. Since the connecting conductor popped out and the interlayer connecting conductor was peeled off from the ceramic on the side wall, the maximum void diameter in the vicinity of the interlayer connecting conductor was increased to 12 μm or more.

In addition, when the alumina powder particle size (D ₀₅₀ ) in the conductive paste is larger than 1 μm as in the sample 16, the alumina is difficult to diffuse into the ceramic near the interlayer connection conductor, and it is difficult to suppress the softened state of the ceramic. Therefore, the protruding amount of the interlayer connection conductor is larger than 10 μm, the interlayer connection conductor protrudes, and the interlayer connection conductor is peeled off from the ceramic on the side wall, so that the maximum void diameter in the vicinity of the interlayer connection conductor is increased to 12 μm or more. .

Further, as in Sample 17, when the D _min of the silver powder in the conductive paste is smaller than 1.5 μm, the silver powder having a particle diameter of less than 1.5 μm diffuses violently into the ceramic and promotes softening shrinkage of the ceramic. Therefore, the protruding amount of the interlayer connection conductor is larger than 10 μm, the interlayer connection conductor protrudes, and the interlayer connection conductor is peeled off from the ceramic on the side wall, so that the maximum void diameter in the vicinity of the interlayer connection conductor is increased to 12 μm or more. I have.

Further, as in Sample 20, when the SSA of the silver powder in the conductive paste is larger than 0.3 m ² / g, the proportion of the glass softened during firing comes into contact with the interlayer connection conductor increases, so that silver diffuses. Since it melts in the ceramic glass near the interlayer connection conductor and promotes softening and shrinkage of the ceramic, the amount of protrusion of the interlayer connection conductor becomes larger than 10 μm, and the interlayer connection conductor pops out, and the interlayer connection conductor However, since the ceramic on the side wall was peeled off, the maximum void diameter in the vicinity of the interlayer connection conductor was increased to 12 μm or more.

  Further, as in Sample 23, when the content of anorthite powder in the conductive paste is more than 1.0% by weight, the interlayer connection conductor is the same as in the case of Sample 9 containing more than 1.0% by weight of alumina powder. Since the amount of protrusion was larger than 10 μm, the interlayer connecting conductor was popped out, and the interlayer connecting conductor was peeled off from the ceramic on the side wall, so that the maximum void diameter in the vicinity of the interlayer connecting conductor was increased to 12 μm or more.

  In addition, when molybdenum oxide powder, which is neither alumina powder nor anorthite powder, was added as in samples 24-26, the softening of the ceramic was accelerated by molybdenum oxide diffused in the ceramic. Even if the amount is in the range of 0.2 to 1.0% by weight or 1.2% by weight, the amount of protrusion of the interlayer connection conductor is larger than 10 μm, and the maximum void diameter in the vicinity of the interlayer connection conductor is 12 μm. It has grown bigger than above.

  Moreover, when the borosilicate glass powder which is neither an alumina powder nor an anorthite powder was added like the samples 27-29, since the effect which suppresses the shrinkage | contraction softening of the ceramic near an interlayer connection conductor became small, addition Even if the amount is in the range of 0.2 to 1.0% by weight or 1.2% by weight, the amount of protrusion of the interlayer connection conductor is within the range of −10 μm to 10 μm, but the maximum in the vicinity of the interlayer connection conductor The void diameter has become larger than 12 μm.

  Further, when the alumina-coated silver powder is used as an inorganic component as in the sample 30, the sintering of silver is greatly delayed, and when the sintering starts, it contracts rapidly. A large difference was generated in the amount of shrinkage, the amount of protrusion of the interlayer connection conductor was larger than 10 μm, and the maximum void diameter in the vicinity of the interlayer connection conductor was as large as 12 μm or more.

  Further, when the alumina-coated silver powder and the molybdenum oxide powder are used as inorganic components as in the samples 31 and 32, the softening of the ceramic is accelerated by the molybdenum oxide diffused in the ceramic. Due to the powder, the sintering of silver was too slow, so that even when the addition amount was in the range of 0.5 to 1.0% by weight, the protruding amount of the interlayer connection conductor was larger than 10 μm, and the interlayer connection conductor Popped out, and cracks larger than 50 μm were generated in the vicinity of the interlayer connection conductor, and the maximum void diameter in the vicinity of the interlayer connection conductor was increased to 12 μm or more.

  From Samples 24-32 above, it can be seen that the additive powder must contain alumina and / or anorthite.

FIG. 5 is a cross-sectional view illustrating a method for manufacturing a ceramic multilayer substrate according to the present invention, in which a base layer green sheet 1a and a shrinkage suppression layer green sheet 5a are separated from each other. It is sectional drawing which shows the unsintered composite laminated body 8 obtained by laminating | stacking the green sheet 1a for base materials shown in FIG. 1, and the green sheet 5a for shrinkage | contraction suppression layers. It is sectional drawing which shows the state after baking the composite laminated body 8 shown in FIG. It is sectional drawing which shows the ceramic multilayer substrate 6 after the sintering removed by removing the shrinkage | contraction suppression layer 5 shown in FIG. FIG. 5 is a cross-sectional view showing a state where surface-mounted components 11 and 12 are mounted on the ceramic multilayer substrate 6 shown in FIG. 4. FIG. 6 is a cross-sectional view showing a state in which the ceramic multilayer substrate 6 shown in FIG. 5 is mounted on a mother substrate 15.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Green sheet for base material layer 1 Ceramic base material layer 3 Interlayer connection conductor 4 In-plane conductor 5a Green sheet for shrinkage suppression layer 5 Shrinkage suppression layer 6 Ceramic multilayer substrate 7 Unsintered ceramic laminate 8 Composite laminate

Claims (10)

A conductive paste containing an inorganic component and an organic component,
The inorganic component includes silver powder and additive powder containing alumina and / or anorthite,
The silver powder has an integrated 50% particle size (D ₀₅₀ ) of 3 to 6 μm, an integrated minimum particle size (D _min ) of 1.5 μm or more, and a specific surface area (SSA) of 0.3 m ² / g or less,
The additive powder has an integrated 50% particle size (D ₀₅₀ ) of 1.0 μm or less,
The silver powder content is 85-95 wt%,
The content of the additive powder is 0.2 to 1.0% by weight,
Conductive paste. The silver powder has an integrated 50% particle size (D ₀₅₀ ) of 3.5 to 5 μm and an integrated minimum particle size (D _min ) of 2 μm or more, and the content of the additive powder is 0.2 to 0.00. The electrically conductive paste of Claim 1 which is 8 weight%.   The conductive paste according to claim 1 or 2, wherein the silver powder is spherical. A non-sintered ceramic laminate having a non-sintered conductor pattern provided in association with the non-sintered ceramic base layer, wherein the non-sintered ceramic base material layer is laminated. A composite laminate including a shrinkage suppression layer provided in contact with the sintered ceramic base layer and not substantially sintered at a temperature at which the green ceramic base layer and the green conductor pattern are sintered. A step of producing
Firing the composite laminate at a temperature at which the shrinkage suppression layer does not substantially sinter and the unsintered ceramic base layer and the unsintered conductor pattern sinter. A manufacturing method of
The unsintered conductor pattern is formed by a conductive paste,
The conductive paste includes an inorganic component and an organic component,
The inorganic component includes silver powder and additive powder containing alumina and / or anorthite,
The silver powder has an integrated 50% particle size (D ₀₅₀ ) of 3 to 6 μm, an integrated minimum particle size (D _min ) of 1.5 μm or more, and a specific surface area (SSA) of 0.3 m ² / g or less,
The additive powder has an integrated 50% particle size (D ₀₅₀ ) of 1.0 μm or less,
The silver powder content is 85-95 wt%,
The content of the additive powder is 0.2 to 1.0% by weight,
A method for producing a ceramic multilayer substrate.   The method for producing a ceramic multilayer substrate according to claim 4, wherein, in the firing step, the composite laminate is fired without forced pressurization.   The method for producing a ceramic multilayer substrate according to claim 4 or 5, wherein the unsintered ceramic substrate layer is provided by a green sheet for a substrate layer comprising ceramic powder and glass powder. The green sheet for base material layer includes CaO—Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ glass powder and Al ₂ O ₃ ceramic powder, and the shrinkage suppression layer is Al ₂ O ₃ ceramic powder. The manufacturing method of the ceramic multilayer substrate of Claim 6 containing these.   In the composite laminate, the shrinkage suppression layer is located on both main surfaces of the unsintered ceramic laminate, and further includes a step of removing the shrinkage suppression layer after the firing step. A method for producing a ceramic multilayer substrate according to any one of 4 to 7.   9. The method for producing a ceramic multilayer substrate according to claim 4, wherein in the composite laminate, the shrinkage suppression layer is located between a plurality of the unsintered ceramic base layers.   Furthermore, the manufacturing method of the ceramic multilayer substrate of Claim 8 or 9 provided with the process of mounting surface mounting components.

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