JP3216260B2 - Low temperature fired ceramic multilayer substrate and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature fired ceramic multilayer substrate and a method for producing the same, and more particularly, to a low-temperature fired using Cu as a conductor material for mounting LSIs and chip parts and interconnecting them. The present invention relates to a ceramic multilayer substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art Heretofore, alumina having excellent insulating properties, thermal conductivity, stability and mechanical strength has been widely used as a mounting substrate for LSIs and chip parts. However, since the alumina substrate has a high dielectric constant and needs to be fired at a high temperature, it has a high conduction resistance as a wiring conductor.
And Mo must be used, and there are disadvantages such as poor matching of the coefficient of thermal expansion with silicon.
However, it is difficult to increase the processing speed of the electric signal, increase the frequency of the electric signal, or improve the reliability. In recent years, in order to solve these problems, Au, A
g, Ag-Pd, Cu, etc., using a conductor material with low conduction resistance, using a ceramic material that can be fired at a temperature equal to or lower than the melting point of these metals as an insulator, and simultaneously firing the conductor, a low-temperature fired ceramic multilayer. Substrates are being developed.

However, among these conductor materials, A
Since noble metals such as u can be fired in an oxidizing atmosphere, they are highly reliable but scarce in terms of resources, are expensive, have large price fluctuations, and are difficult to use economically.

On the other hand, although Cu must be fired in a non-oxidizing atmosphere such that it is not oxidized, it is inexpensive, has low resistance, and has excellent migration resistance. It is attracting attention as a leading conductor material for a mounting substrate that can cope with higher density and higher frequency. However, firing in a non-oxidizing atmosphere makes it difficult to decompose and scatter the organic binder contained in the green sheet and the conductor paste. As a result, the organic binder is carbonized and remains in the substrate, and the sintering of the copper powder and the ceramic powder is hindered, thereby deteriorating the substrate characteristics such as electrical conductivity, insulation, and withstand voltage of the conductor. Had.

In order to solve such a problem, a method of removing binder in a nitrogen atmosphere containing water vapor (Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 0-254697 and Japanese Patent Application Laid-Open No. 2-141458) have been proposed, but this method has a problem that it is not economical since a long time calcination is required for the binder removal step.

A method of performing a binder removal step in an air atmosphere (Japanese Patent Application Laid-Open No. 2-155294) has also been proposed. However, in this method, the amount of carbon remaining in the fired material after the binder removal step is reduced from 600. 1500 ppm or 60
It must be adjusted within the range of 0 to 3000 ppm, and it is extremely difficult to set conditions for the binder removal step.
Furthermore, when the copper conductor is fired simultaneously with the ceramic,
If copper is oxidized even a little, it expands, so that the ceramic layer is easily cracked, and it has been very difficult to remove the binder in the oxidizing atmosphere in a non-oxidized state of copper.

Further, a method has been proposed in which a binder is removed by a heat treatment in a weakly oxidizing atmosphere, followed by baking in a reducing atmosphere (Japanese Patent Laid-Open No. 2-25094).
In this method, too, the adjustment of the firing atmosphere for maintaining the balance between the oxidation combustion of the resin binder and the prevention of oxidation of copper is very delicate, and it is difficult to achieve both at the same time, so that the productivity is low. Further, if the number and size of the laminates and the conductor pattern change, the balance between the oxidative combustion of the resin binder and the prevention of copper oxidation also changes, so that there is a problem that the firing atmosphere must be newly adjusted.

Further, a method has been proposed in which a multi-layer substrate of copper conductor is obtained by firing in a nitrogen atmosphere containing trace amounts of water vapor and oxygen (Japanese Patent Laid-Open No. 63-292892).
This method has a problem that the setting and adjustment of the firing atmosphere is not easy and continuous production is difficult. Although a method using an easily decomposable resin has been proposed (JP-A-2-16795), this method also has a problem that the adjustment of the firing atmosphere is similarly difficult.

In order to solve the above-mentioned problems, copper oxide is used as a conductor wiring material, and internal organic components are thermally decomposed and scattered by baking in an oxidizing atmosphere. A method for obtaining a multilayer wiring board by sintering copper and ceramics in an atmosphere reduced to copper (Japanese Patent Laid-Open No. 61-262)
No. 93) and a binder removing step by heat treatment in air using copper oxide as a conductor wiring material, a reducing step of reducing cupric oxide to metallic copper, and further sintering and integrating copper and a substrate material. A method has been proposed in which the organic binder can be completely removed by performing a sintering step (Japanese Patent Publication No. 3-21109).

[0010]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No. 61-26293 and Japanese Patent Publication No. Hei 3-21109 describe the above.
In the method disclosed in Japanese Patent Application Laid-Open No. H11-284, there is too much difference in the amount of shrinkage between the conductor portion and the low-temperature fired ceramic insulating portion, and thus there are disadvantages such as deformation of the substrate or disconnection of the conductor wiring. That is, the volume shrinkage of the conductor is about 44% at the stage of reducing copper oxide to copper.
In addition, while about 25% of shrinkage due to sintering of copper is added, the volume shrinkage of the low-temperature fired ceramic part is only shrinkage due to sintering, and is generally about 44%. When it is large, there is a problem that the substrate is easily deformed or the conductor wiring is easily broken.

In the copper oxide reduction step, since the reducing gas reduces the copper oxide in the internal conductor layer, the low-temperature fired ceramic layer must be unsintered porous so that the reducing gas can penetrate. For this reason, the ceramic layer at this stage is in a very brittle state, and there has been a problem that cracks and deformation may occur in the substrate due to stress generated by volume shrinkage due to reduction of copper oxide.

A substrate manufactured using copper oxide as a conductor raw material in this manner has shape defects such as deformation and cracks.
In addition, there is a problem that a small electronic component cannot be mounted at a high density because the wiring portion may be disconnected.

[0013] The present invention has been made in view of the above-mentioned problems, and can fully exhibit the characteristic that copper has a small conduction resistance, and can completely complete the binder removal step. By matching the amount of contraction between the conductor part and the ceramic insulation part, it is possible to suppress the occurrence of shape defects such as deformation and cracks in the substrate and the occurrence of disconnection, and to mount small electronic components at high density. It is an object of the present invention to provide a low-temperature fired ceramic multilayer substrate and a method of manufacturing the same.

[0014]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted research on a low-temperature fired ceramic multilayer substrate and a method for manufacturing the same. The binder removal process is enabled, the binder removal can be completely performed, and by adding a shrinkage inhibitor to the copper oxide powder, the shrinkage of the conductor portion and the ceramic insulation portion in the subsequent reduction and firing process can be matched. As a result, the present inventors have found that a shape defect such as deformation or cracks is generated in the ceramic multilayer substrate and that the occurrence of disconnection can be suppressed, and the present invention has been completed.

The low-temperature fired ceramic multilayer substrate according to the present invention, which is the gist of the present invention, comprises ceramic particles having a melting point higher than the melting point of copper in the internal copper conductor, or glass particles having a softening point higher than the melting point of copper. Alternatively, mixed particles of ceramic particles having a melting point equal to or higher than the melting point of copper and glass particles having a softening point equal to or higher than the melting point of copper are present.

Further, in the method of manufacturing a low-temperature fired ceramic multilayer substrate according to the present invention, a green sheet is prepared by mixing an organic binder and a plasticizer with a ceramic raw material, and the green sheet is formed of copper oxide. Ceramic powder having a melting point higher than the melting point of copper or glass powder having a softening point higher than the melting point of copper, or ceramic powder having a melting point higher than the melting point of copper and glass powder having a softening point higher than the melting point of copper Printing a paste having a mixed powder as a main component into a desired circuit pattern; laminating green sheets on which the circuit pattern is printed to form a green sheet laminate; A binder step of decomposing and scattering the organic binder, and after the binder removal step, a reducing atmosphere having a temperature equal to or lower than the melting point of copper. It is characterized in that it contains a reduction firing step of firing at the same time reducing the copper oxide in the gas ceramics.

Further, another low-temperature fired ceramic multilayer substrate according to the present invention is characterized in that the internal copper conductor has ceramic particles having a melting point higher than the melting point of copper, glass particles having a softening point higher than the melting point of copper, or the melting point of copper. It is characterized in that there are mixed particles of ceramic particles having the above melting point and glass particles having a softening point equal to or higher than the melting point of copper, and glass particles having a softening point equal to or lower than the melting point of copper.

Further, the above-mentioned another method for producing a low-temperature fired ceramic multilayer substrate according to the present invention comprises the steps of:
A step of preparing a green sheet by mixing an organic binder and a plasticizer, and the green sheet has a ceramic powder having a melting point equal to or higher than the melting point of copper in a main component made of copper oxide,
Or a glass powder having a softening point equal to or higher than the melting point of copper, or a mixed powder of a ceramic powder having a melting point equal to or higher than the melting point of copper and a glass powder having a softening point equal to or higher than the melting point of copper, and having a softening point equal to or lower than the melting point of copper A step of printing a paste containing glass powder as a main component in a desired circuit pattern, a step of laminating green sheets on which the circuit pattern is printed to form a green sheet laminate, and an organic layer in the green sheet laminate. A binder removal step of decomposing and scattering the binder, and a reduction firing step of firing the ceramic while reducing the copper oxide in a reducing atmosphere at a temperature equal to or lower than the melting point of copper after the binder removal step. Features.

The copper oxide used in the above method may be either cuprous oxide or cupric oxide, and preferably has a particle size of about 0.5 μm to 10 μm, which can be pasted. If the particle size is less than 0.5 μm, the powder becomes bulky, so that the powder content in the paste becomes low, it becomes difficult to form a good conductor, and the volume shrinkage due to sintering of reduced copper is extremely large, It is not preferable because the substrate is easily deformed. On the other hand, when the particle size exceeds 10 μm, the printability deteriorates, which is not preferable.

Further, in the present invention, since the shrinkage of the copper conductor is suppressed by utilizing the action of the shrinkage inhibitor, a porous sintered copper conductor is formed. When copper powder is used, the neck diameter of the conductive net of the copper conductor becomes about 3 μm or more, and good conductivity is obtained. When a copper oxide powder having a small particle size is used, the neck diameter of the conductive net network of the copper conductor is also reduced, and the conductivity is reduced.

As the shrinkage inhibitor, a ceramic powder having a melting point higher than the melting point of copper or a glass powder having a softening point higher than the melting point of copper is used. Since it is necessary to be chemically stable also in the binder removal step in air and the reduction / calcination step in a reducing atmosphere, oxides such as alumina, zirconia, magnesia or silica, aluminum nitride, A nitride such as silicon nitride or a mixture thereof can be used, but alumina is preferred from the viewpoint of cost. Further, a glass having a softening point equal to or higher than the melting point of copper needs to be chemically stable in a binder removal step and a reduction / calcination step in a reducing atmosphere, for example, Al ₂ O ₃ —SiO ₂ —CaO ₂
Base glass can be used. The upper limit of the particle size of the shrinkage inhibitor may be 10 μm or less, which can be printed as a paste, and there is no particular lower limit on the particle size. The shrinkage-suppressing effect of the shrinkage-suppressing agent is large because the smaller the particle size, the more uniformly the particles are dispersed. The optimal particle size of the shrinkage-suppressing agent is 1 μm or less, preferably 0.1 μm or less. The amount of shrinkage inhibitor added is copper oxide 1
Less than 10 parts by weight based on 00 parts by weight. If the addition amount of the shrinkage inhibitor is at least 10 parts by weight based on 100 parts by weight of copper oxide, the conductivity of the copper conductor wiring after firing is undesirably reduced. In addition, since the shrinkage inhibitor having a smaller particle size has a higher shrinkage suppression effect, the amount of addition can be reduced. Further, a preferred combination of the particle size and the amount of addition of the shrinkage inhibitor is 9 parts by weight or less for 100 parts by weight of copper oxide in the case of a shrinkage inhibitor having a particle size of 0.5 μm or less.

Further, glass powder having a softening point equal to or lower than the melting point of copper may be added to the copper oxide paste in order to improve the adhesion between the copper conductor and the ceramic insulating layer. These adhesives react during firing to bond the copper conductor and the ceramic insulating layer. Known glass powders can be used, and lead borosilicate glass is preferred because it satisfies the above softening point conditions. The addition amount of the glass powder is desirably less than 5 parts by weight based on 100 parts by weight of copper oxide. 5
If the amount is more than the weight part, the conduction resistance of copper increases, which is not preferable.

To form a copper oxide paste, a copper oxide powder and a shrinkage inhibitor or a copper oxide powder, a shrinkage inhibitor and glass powder having a softening point of copper or less are mixed in a vehicle in which a resin is dissolved in a solvent and a plasticizer. What is necessary is just to knead with this roll mill. Ethyl cellulose or acrylic resin can be used as the resin, terpineol can be used as the solvent, and dibutyl phthalate can be used as the plasticizer.

The low-temperature fired ceramics usable in the present invention must be fired at a temperature lower than the melting point of copper, and include glass composite ceramics in which glass and an inorganic filler are mixed, crystallized glass-based ceramics, and non-glass-based ceramics. . For example, ceramics in which inorganic fillers such as alumina, mullite, and forsterite are combined with borosilicate glass are desirable.

The slurry of the ceramic raw material is prepared by wet-pulverizing and mixing the ceramic raw material in a solvent, and then mixing and mixing an organic binder, a dispersant, a plasticizer and the like as appropriate.

As the solvent, an organic solvent such as alcohol, toluene, acetone, methyl ethyl ketone, trichloroethylene or a mixture thereof, or water can be used. As the organic binder, a thermally decomposable organic binder such as a methacrylate polymer, an acrylate-methacrylate copolymer, an α-methylstyrene polymer, and a tetrafluoroethylene polymer can be used. However, polyvinyl butyral, vinyl acetate, and the like, which are widely used as organic binders, are not preferable because a high temperature is required for removing the binder. As the dispersant, octadecylamine, glyceryl monooleate, sorbitan monooleate and the like are used. Dioctyl phthalate (DOP), dibutyl phthalate (DB)
P), polyethylene glycol, glycerin and the like can be used.

From the slurry obtained by the above method, a green sheet having a uniform thickness is formed by a known method such as a doctor blade method, and dried to a state in which it can be handled. The green sheet is processed into a desired shape by a cutter or a punching die, and if necessary, a through hole is formed at a desired position by a punching die or the like. Thereafter, the copper oxide paste is screen-printed on the processed green sheet to form a wiring pattern, and a predetermined number of the green sheets on which the wiring pattern has been formed are stacked and pressed to form a laminate.

The heat treatment of the laminate includes two steps, a binder removal step in air and a reduction firing step in a reducing atmosphere, and both steps can be performed in a belt furnace having high continuous productivity.

In the binder removing step of the laminated green sheets, it is desirable to heat the mixture in air from 550 ° C. to a temperature lower than the sintering start temperature of the low-temperature fired ceramics. When the heating temperature is lower than 550 ° C., the binder removal becomes insufficient. On the other hand, when the temperature exceeds the sintering start temperature, the low-temperature fired ceramics starts sintering shrinkage and densifies. At the temperature below the melting point of copper, there is almost no sintering shrinkage of copper oxide in the air, so that only the low-temperature fired ceramics shrinks and undesirably deforms the multilayer body.

The reduction firing step after the binder removal step is performed at 800 ° C. to 1050 ° C. in a nitrogen gas atmosphere containing 3% or less of hydrogen.
It is desirable to carry out by heating to ° C. If the hydrogen concentration exceeds 3%, there is a risk of explosion and there is a safety problem. If the temperature is lower than 800 ° C., the ceramic may not be sintered. If the temperature exceeds 1050 ° C., copper is melted and fluidized, and the wiring pattern is undesirably broken. After the reduction step is performed at about 400 ° C., the firing step may be performed in a neutral atmosphere.

[0031]

In the low-temperature fired ceramic multilayer substrate according to the first aspect, the use of copper oxide as a starting material for the conductor material enables the binder removal step to be performed in the air, thereby completely removing the resin binder. Therefore, good conductor characteristics and substrate characteristics can be obtained. Further, ceramic particles having a melting point higher than the melting point of copper, or glass particles having a softening point equal to or higher than the melting point of copper, or ceramic particles having a melting point equal to or higher than the melting point of copper and the melting point of copper or higher as the copper oxide as a shrinkage inhibitor Mixed particles with glass particles having a softening point are added, and the shrinkage inhibitor suppresses the amount of shrinkage due to reduction of copper oxide to copper, and the amount of shrinkage due to sintering of copper. By matching the amount of shrinkage of the insulating portion, it is possible to suppress the occurrence of shape defects such as deformation and cracks on the substrate and the occurrence of disconnection, and it is possible to mount small electronic components with high density. Become.

The reason why the shrinkage inhibitor has the melting point of copper or higher is that if it is lower than the melting point of copper, the firing temperature of the low-temperature fired ceramic is lower than the melting point of copper. Therefore, when firing the low-temperature fired ceramics, the ceramic powder or glass powder as the shrinkage suppressor is melted, softened and fluidized, respectively, and shrinkage due to reduction of copper oxide and sintering of reduced copper. This is because they flow at the same time, and the contraction of the conductor cannot be suppressed.

According to the method for manufacturing a low-temperature fired ceramic multilayer substrate according to the second aspect, the low-temperature fired ceramic multilayer substrate according to the first aspect can be reliably and easily obtained.

In the low-temperature fired ceramic multilayer substrate according to the third aspect, the copper conductor according to the first aspect further includes glass particles having a softening point equal to or lower than the melting point of copper.
It has the same function as that of the first aspect, and furthermore, the glass particles react at the time of sintering, so that the adhesiveness between the copper conductor portion and the ceramic insulating layer can be improved.

According to the method for manufacturing a low-temperature fired ceramic multilayer substrate according to the fourth aspect, the low-temperature fired ceramic multilayer substrate according to the third aspect can be reliably and easily obtained.

[0036]

Examples and Comparative Examples Examples and comparative examples of a low-temperature fired ceramic multilayer substrate and a method of manufacturing the same according to the present invention will be described below. First, alumina powder and borosilicate glass powder are mixed at 50% by weight, respectively, and pulverized and mixed to obtain a ceramic raw material. 69% of this ceramic material, 9% of methacrylate resin, 3% of DOP, 9% of toluene
% And isopropyl alcohol 10%, a trace amount of an octadecylamine-based dispersant was added and mixed with a ball mill to form a ceramic slurry. After defoaming this slurry with a vacuum defoaming machine, a green sheet having a thickness of 250 μm was prepared from the ceramic slurry by a doctor blade method. After cutting this green sheet into a predetermined size, a through hole having a diameter of 200 μm was formed at a necessary portion.

Next, copper oxide powder shown in Table 1 and alumina powder as a shrinkage inhibitor shown in Table 2 (melting point: 2055 ° C.)
And SiO ₂ —CaO—MgO-based glass (softening point 13
Table 3 shows borosilicate glass (softening point: 500 ° C., particle size: 5 μm) as a glass powder for bonding.
Was blended in the composition shown in Table 1 and mixed.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3-1]

[0041]

[Table 3-2]

[0042]

[Table 3-3]

[0043]

[Table 3-4]

Next, the mixture was mixed with ethyl cellulose 5
%, Terpineol 55%, dibutyl phthalate 40%
And kneaded with a three-roll mill to form a paste. This paste containing copper oxide as a main component was applied by screen printing on the processing agent green sheet to form a wiring pattern. The printing area ratio of the copper oxide paste on the green sheet was set to about 60% of the sheet.

In this printing process, the inside of the through hole is filled with a copper oxide paste. Thereafter, the desired green sheets on which a wiring pattern had been formed were stacked and laminated at a pressure of 30 MPa and a temperature of 100 ° C. to be integrated. FIG. 1 shows the green sheet laminate after the wiring pattern is pressed, 11 denotes a green sheet, 12 denotes an internal conductor paste, and 13 denotes a surface conductor paste.

Next, the binder is removed from the laminate of the unsintered green sheets. 600 ° C peak temperature in air
Heating was performed with a heating profile of 3 hours including a peak retention time of 90 minutes.

Next, heat treatment including reduction of copper oxide in the laminate to metallic copper and integrated firing of the reduced copper and ceramics are performed. The binder-removed green sheet laminate is 1 to
A peak temperature of 900 ° C. in a mixed gas of 4% hydrogen and nitrogen,
Firing was performed with a heating profile of 1.5 hours including a peak temperature holding time of 30 minutes to produce a low-temperature fired ceramic substrate having an internal copper conductor.

The copper conductor circuit of the uppermost layer is formed by printing a copper conductor paste in a predetermined pattern on the fired substrate, and under a nitrogen atmosphere, at a peak temperature of 900 ° C. and a peak temperature holding time of 10 hours.
Baking with a heating profile of 60 minutes including the minutes to obtain a final circuit board.

Next, the following experiments were conducted using the low-temperature fired ceramic multilayer substrate, and the results are shown in Table 3.

Each of the two sides of the front and back of the substrate measured by the surface roughness meter
The average value of the difference between the maximum value and the minimum value (ie, the highest peak and the lowest valley) of the diagonal irregularities is represented as the deformation amount of the substrate. Further, in the same table, the conduction resistance of the internal copper wiring was represented by a sheet resistance value.

Embodiment No. Nos. 1 to 35 are copper oxides containing alumina particles as a shrinkage inhibitor. 71 and 72 are conductors obtained by adding SiO ₂ —CaO—MgO-based glass powder as a shrinkage inhibitor to copper oxide, and Examples 73 and 74 are conductors obtained by adding a mixed powder of the alumina powder and the glass powder to a copper oxide as a shrinkage inhibitor. Since the paste is used, the deformation of the substrate is as small as 4 μm or less, and the sheet resistance is excellent.

Further, in Example No. 36 to 70 are alumina particles as a shrinkage inhibitor and SiO ₂ for adhesion to copper oxide.
The -B ₂ O ₃ based glass, No. 76, 77 a SiO ₂ -CaO-MgO based glass powder and SiO ₂ -B ₂ O ₃ based glass for adhesion as shrinkage-suppressing agent in the copper oxide, No. 7
No. 5 uses a conductive paste obtained by adding the alumina powder, the glass powder, and the glass particles for bonding as a shrinkage inhibitor to copper oxide, and has an excellent sheet resistance value. In Example No. 1 to
It can be said that it is even smaller than 35, 71 and 72.

In Comparative Examples 1 and 2, the copper oxide paste did not contain the shrinkage inhibitor and the glass particles for bonding, and the deformation of the substrate was much larger than that of the Example, and the sheet resistance was also inferior. . Furthermore, since the glass oxide for adhesion is contained in the copper oxide pastes of Comparative Examples 3 to 6, the deformation of the substrate is smaller than that of Comparative Examples 1 and 2, but it is very large compared to those of the Examples. Understand. Further, those of Comparative Examples 2 and 3 were disconnected.

Also, in all of Examples 1 to 77, the carbon content of the multilayer body after the binder removal step is sufficiently low as 50 ppm or less, and is an amount that does not adversely affect the sinterability and the substrate characteristics of copper and low-temperature fired ceramics. is there.

As described above, Examples 1 to 35 and 71 to 71
No. 74 can sufficiently exhibit the property that the conduction resistance of copper is small, and can completely complete the binder removal step. Further, the copper oxide has a melting point higher than the melting point of copper as a shrinkage inhibitor. As a ceramic having alumina or a glass having a softening point equal to or higher than the melting point of copper, a mixed powder of SiO ₂ -CaO-MgO-based glass or a mixed powder of the alumina and SiO ₂ -CaO-MgO-based glass is added and pasted, The shrinkage inhibitor suppresses the amount of copper oxide reduced to copper and the amount of shrinkage due to sintering of copper, and by matching the amount of shrinkage with the amount of shrinkage of the ceramic insulating portion, the substrate has a shape defect such as deformation or crack. And the occurrence of disconnection can be suppressed, and small electronic components can be mounted at high density.

In Examples 36 to 70 and 75 to 77, borosilicate glass was added to the paste as a glass powder having a softening point lower than the melting point of copper for bonding. Reacts to improve the adhesion between the copper conductor and the ceramic insulating layer,
The effect of suppressing deformation of the substrate and the like can be further enhanced.

[0057]

As is apparent from the above description, in the low-temperature fired ceramic multilayer substrate according to the first aspect of the present invention, the binder removal step is performed by using copper oxide as a starting material for the conductor material. In this case, the resin binder can be completely removed, so that good conductor characteristics and substrate characteristics can be obtained. Further, ceramic particles having a melting point higher than the melting point of copper, or glass particles having a softening point equal to or higher than the melting point of copper, or ceramic particles having a melting point equal to or higher than the melting point of copper and the melting point of copper or higher as the copper oxide as a shrinkage inhibitor Mixed particles with glass particles having a softening point are reduced by the shrinkage inhibitor to reduce the amount of copper oxide reduced to copper and the amount of shrinkage due to sintering of the copper, thereby reducing the amount of shrinkage and shrinkage of the ceramic insulating portion. By matching the amounts, it is possible to suppress the occurrence of shape defects such as deformation and cracks in the substrate and the occurrence of disconnection, and it is possible to mount small electronic components at high density.

According to the method for manufacturing a low-temperature fired ceramic multilayer substrate according to the second aspect, the low-temperature fired ceramic multilayer substrate according to the first aspect can be reliably and easily obtained.

In the low-temperature fired ceramic multilayer substrate according to the third aspect, the copper conductor according to the first aspect further includes glass particles having a softening point equal to or lower than the melting point of copper.
It has the same effect as that of the first aspect, and furthermore, the glass particles react at the time of sintering, so that the adhesiveness between the copper conductor portion and the ceramic insulating layer can be improved.

According to the method for manufacturing a low-temperature fired ceramic multilayer substrate according to the fourth aspect, the low-temperature fired ceramic multilayer substrate according to the third aspect can be reliably and easily obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an intermediate process product of a low-temperature fired ceramic multilayer substrate.

[Description of sign]

 11 Green sheet 12 Internal conductor paste 13 Surface conductor paste

Claims (4)

(57) [Claims] A ceramic particle having a melting point equal to or higher than the melting point of copper, a glass particle having a softening point equal to or higher than the melting point of copper, or a ceramic particle having a melting point equal to or higher than the melting point of copper. A multilayer ceramic substrate fired at low temperature, characterized in that mixed particles with glass particles having a softening point are present. 2. A step of producing a green sheet by mixing an organic binder and a plasticizer with a ceramic raw material; and adding a ceramic powder having a melting point equal to or higher than the melting point of copper to a main component comprising copper oxide; A paste containing a glass powder having a softening point equal to or higher than the melting point of copper, or a mixed powder of a ceramic powder having a melting point equal to or higher than the melting point of copper and a glass powder having a softening point equal to or higher than the melting point of copper is used as a main component. Forming a green sheet laminate by laminating the green sheets on which the circuit patterns are printed; a binder removing step of decomposing and scattering an organic binder in the green sheet laminate; After the binder step, the copper oxide is reduced in a reducing atmosphere at a temperature equal to or lower than the melting point of copper. Method for producing a low-temperature co-fired ceramic multilayer substrate according to claim 1, characterized in that it comprises a firing step. 3. A ceramic particle having a melting point equal to or higher than the melting point of copper, a glass particle having a softening point equal to or higher than the melting point of copper, or a ceramic particle having a melting point equal to or higher than the melting point of copper. A low-temperature fired ceramic multilayer substrate comprising mixed particles with glass particles having a softening point and glass particles having a softening point equal to or lower than the melting point of copper. 4. A step of preparing a green sheet by mixing an organic binder and a plasticizer with a ceramic raw material; and adding a ceramic powder having a melting point equal to or higher than the melting point of copper to a main component made of copper oxide; Glass powder having a softening point equal to or higher than the melting point of copper, or mixed powder of ceramic powder having a melting point equal to or higher than the melting point of copper and glass powder having a softening point equal to or higher than the melting point of copper, and glass having a softening point equal to or lower than the melting point of copper A step of printing a paste containing powder as a main component in a desired circuit pattern; a step of laminating green sheets on which the circuit pattern is printed to form a green sheet laminate; and an organic binder in the green sheet laminate. A binder removal step of decomposing and scattering the copper oxide, and after the binder removal step, the copper oxide is placed in a reducing atmosphere at a temperature equal to or lower than the melting point of copper. Method for producing a low-temperature co-fired ceramic multilayer substrate according to claim 3, characterized in that it comprises a reduction firing step of firing the reduction to simultaneously ceramics.