JP2007015878A - Ceramic composition, ceramic substrate, and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic composition for obtaining a ceramic substrate capable of enhancing acid resistance of the ceramic substrate while maintaining good sinterability in spite of containing a glass component to enable firing at relatively low temperatures. <P>SOLUTION: This ceramic composition is a mixture of borosilicate-based glass powder comprising 28-50 wt.% SiO<SB>2</SB>, 36-55 wt.% MO (MO is at least either of CaO and MgO), 0-20 wt.% Al<SB>2</SB>O<SB>3</SB>and 5-17.5 wt.% B<SB>2</SB>O<SB>3</SB>and ceramic powder containing ≥1 wt.% ZrO<SB>2</SB>, which comprises 40-80 wt.% borosilicate glass powder and 60-20 wt.% ceramic powder, respectively. The ceramic substrate is provided with a ceramic layer 3 comprising a ceramic sintered body obtained by forming and firing the ceramic composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ceramic composition, a ceramic substrate composed of the ceramic composition, and an electronic component including the ceramic substrate, and more particularly to a technique for increasing acid resistance of the ceramic substrate.

  As a ceramic substrate, for example, there is one having a laminated structure including a plurality of ceramic layers. The ceramic substrate having such a laminated structure often includes, as a wiring conductor, an inner conductor film and a via-hole conductor formed inside the ceramic substrate, and an outer conductor film formed on the outer surface of the ceramic substrate. ing.

  In order to increase the frequency and speed of electronic equipment, a low-resistance metal such as Au, Ag, Ag—Pd, Ag—Pt, Cu, or the like is used as a conductive material constituting the wiring conductor. preferable. However, since the low-resistance metal as described above generally has a relatively low melting point, when this is used as a conductive material for the above-described internal conductor film or via-hole conductor, the firing temperature for obtaining the ceramic substrate is a problem. It becomes.

  Therefore, a ceramic substrate that can be obtained by firing at a relatively low temperature such as 1000 ° C. or less has been proposed. Such a low-temperature fireable ceramic substrate is generally obtained by molding and firing a ceramic composition containing glass powder and ceramic powder, using glass as a matrix and ceramic powder as a filler therefor. The ceramic sintered body is included.

  Conventionally, the following materials have been proposed for materials for ceramic substrates that can be fired at a low temperature as described above.

Japanese Unexamined Patent Publication No. 2000-351668 (Patent Document 1) describes a ceramic substrate that can be fired at a low temperature, and includes a ceramic sintered body containing a borosilicate glass as a matrix and an alumina filler therein. Here, the glass composition, from 5 to 17.5 wt% of B ₂ O _3, 28 to 40 wt% of SiO _2, 0 to 20 wt% Al ₂ O _3, and 36 to 50 wt% of MO (note , MO can be fired at low temperature by adjusting the weight ratio of glass / alumina filler to 40-49 / 60-51 while selecting to contain at least one selected from CaO, MgO and BaO). Thus, a ceramic substrate having high strength and low dielectric loss is obtained.

  However, in the ceramic substrate described in Patent Document 1, MO such as CaO, which is a glass network modifying oxide, is used in the glass for 36 to 50 in order to promote softening and fluidization of the glass so that it can be fired at a low temperature. A relatively large amount such as% by weight is contained. Thus, when the amount of MO is large, for example, when exposed to an acidic solution such as a plating solution in wet plating, there is a problem that MO such as CaO is easily dissolved in the acidic solution. On the other hand, if the amount of MO is small, when Ag is contained in the wiring conductor, Ag is likely to diffuse into the glass in the firing step, and the difference in shrinkage behavior between the wiring conductor and the ceramic sintered body increases. .

Next, Japanese Patent Laid-Open No. 6-221571 (Patent Document 2) describes a low-temperature fireable ceramic substrate comprising a ceramic sintered body containing a borosilicate glass as a matrix and a zirconia filler therein. Yes. Here, the glass composition is selected so that it contains 75 to 85 wt% SiO ₂ , 15 to 20 wt% B ₂ O ₃ , and 0.1 to 5 wt% Al ₂ O _3. By adjusting the weight ratio of the zirconia-based filler to 75 to 45/25 to 55, a ceramic substrate that can be fired at a low temperature and has a high strength and a low dielectric constant is obtained.

However, in the ceramic substrate described in Patent Document 2, since the amount of SiO _{2 in} the glass is relatively large, if the powder characteristics of the glass and filler, the production conditions of the molded body, and the firing conditions are not controlled to a high degree, It tends to be defective.

Next, Japanese Patent Application Laid-Open No. 11-43369 (Patent Document 3) describes a low-temperature fired ceramic substrate including a ceramic sintered body made of glass and filler. The glass is made of SiO ₂ , Al ₂ O _3. , Alkaline earth metal, ZnO and B ₂ O ₃ , the filler is composed of CaO and ZrO ₂ , or a compound thereof, and the starting material composition contains 45 to 80% by weight of glass and 5 to 30% by weight of filler. It is said that a ceramic substrate having a high strength and a high dielectric constant can be obtained by adjusting to include.

  However, the ceramic substrate described in Patent Document 3 has a problem that since ZnO is contained in the glass, this ZnO generally tends to be eluted into the plating solution and deteriorates the plating solution.

Next, Japanese Patent Application Laid-Open No. 2000-223619 (Patent Document 4) describes a low-temperature fireable ceramic substrate including a ceramic sintered body made of glass and filler, and the glass contains 5 to 60% by weight of BaO. And the filler contains metal oxide particles having a coefficient of thermal expansion of 40 ppm / K or more at 40 to 400 ° C., and contains Zr compound in glass and / or filler in an amount of 1 to 30% by weight in terms of ZrO _2. It is said that a ceramic substrate having a thermal expansion coefficient at 400 ° C. of 8.5 to 18 ppm / K is obtained.

Next, Japanese Patent Application Laid-Open No. 2001-196503 (Patent Document 5) describes a low-temperature fireable ceramic substrate including a ceramic sintered body made of glass and filler, and the glass is 15 to 60% by weight of BaO. 1 to 6% by weight Al ₂ O ₃ , and 25 to 60% by weight SiO ₂ , the filler includes metal oxide particles having a thermal expansion coefficient of 40 to 400 ° C. of 6 ppm / K or more, glass and By containing 1 to 30% by weight of the Zr compound in terms of ZrO _{2 in the} filler and not containing cristobalite, the thermal expansion coefficient at 40 to 400 ° C. is 8.5 to 18 ppm / K, and 40 to 400 ° C. A ceramic substrate having no inflection point in the range is obtained.

  However, in the ceramic substrates described in Patent Documents 4 and 5, since the glass contains BaO, the weight of the ceramic substrate is increased, resulting in a problem of increased costs. .

Next, in the pamphlet of International Publication No. 97/11919 (Patent Document 6), an alkali-free glass substrate is described, and the acid resistance of the substrate is improved by including ZrO ₂ as a glass constituent. This is because the ZrO ₂ contained in the glass forms a slightly soluble hydrate in a wide pH range and exists stably, so that the portion becomes a barrier and further dissolution of the glass component is suppressed, thereby improving acid resistance. It is thought to do.

However, in the substrate described in Patent Document 6, a portion of the glass where ZrO ₂ is present serves as a barrier, but a portion where ZrO ₂ does not exist does not have a barrier, so that CaO, MgO, etc. are likely to be eluted. As a result, sufficient acid resistance cannot be improved.
JP 2000-351668 A JP-A-6-21571 Japanese Patent Laid-Open No. 11-43369 JP 2000-223619 A JP 2001-196503 A International Publication No. 97/11919 Pamphlet

  Accordingly, an object of the present invention is to provide a ceramic composition that can improve acid resistance while solving the above-described problems, a ceramic substrate that includes the ceramic composition, and an electronic device that includes the ceramic substrate. Is to try to provide parts.

The ceramic composition according to the present invention is a mixture of glass powder and ceramic powder. When this is fired into a ceramic sintered body, the glass powder becomes a matrix and the ceramic powder becomes a filler. The glass powder comprises 28-50 wt% SiO ₂ , 36-55 wt% MO (where MO is at least one of CaO and MgO), 0-20 wt% Al ₂ O ₃ , and 5-17. It is composed of borosilicate glass composed of 5% by weight of B ₂ O ₃ . On the other hand, the ceramic powder contains 1% by weight or more of ZrO ₂ . And borosilicate type | system | group glass powder contains 40 to 80 weight%, and ceramic powder contains 60 to 20 weight%.

In the ceramic composition according to the present invention, when the ceramic powder as the filler includes a ceramic other than ZrO _2, As the ceramic other than the ZrO _2, it is preferred that only Al ₂ O _3. That is, the ceramic powder preferably contains no components other than ZrO ₂ and Al ₂ O ₃ .

  The present invention is also directed to a ceramic substrate including a ceramic sintered body obtained by molding and firing the ceramic composition described above.

  The present invention is also directed to a ceramic substrate having a laminated structure including first and second ceramic layers. In this case, in the above laminated structure, the first ceramic layer is positioned so as to form at least the outermost layer, and the first ceramic layer forms and fires the ceramic composition according to the present invention described above. It consists of a ceramic sintered body obtained in this way. The second ceramic layer has a higher thermal conductivity than the first ceramic layer.

The second ceramic layer preferably does not contain ZrO ₂ .

  The present invention is particularly advantageously applied when the ceramic substrate further includes an outer conductor film formed on the outer surface of the ceramic substrate, and the outer conductor film is subjected to wet plating.

  The present invention is further directed to an electronic component including the ceramic substrate as described above.

  According to the ceramic composition of the present invention, simply speaking, while maintaining good sinterability, the acid resistance of a ceramic substrate provided with a ceramic sintered body obtained by molding and firing the ceramic substrate is increased. Can do.

  More specifically, in the ceramic composition according to the present invention, MO (at least one of CaO and MgO) contained in the borosilicate glass powder functions as a glass network modifying oxide and promotes softening and fluidization of the glass. Acts like If the MO component is small, the viscous flow becomes insufficient and the sinterability becomes a problem. For this reason, the borosilicate glass powder needs to contain a certain amount of MO component.

  On the other hand, the ceramic substrate is often exposed to an acidic solution, such as a plating solution in a wet plating process. In this case, MO has a property of being easily eluted in an acidic solution. Therefore, if the MO component is contained in a large amount, the elution of the ceramic substrate damages the ceramic substrate and leads to deterioration of the plating solution as the acidic solution, resulting in an increase in cost.

Therefore, according to the present invention, since the ceramic powder as the filler contains ZrO ₂ , the MO component is dissolved (diffused) in ZrO ₂ or reacted to react with the ceramic powder. It is held by ZrO ₂ contained in. Therefore, the amount of MO remaining as a network modification oxide in the glass is reduced.

  From the above, it is possible to ensure good softening and fluidization of glass, and therefore it is possible to obtain a ceramic substrate with good acid resistance while realizing good sinterability. Also, the plating solution can be made difficult to deteriorate.

In the ceramic composition according to the present invention, if the ceramic powder comprises a ceramic other than ZrO _2, as a ceramic other than ZrO _2, when it is so it contains only Al ₂ O _3, and ZrO ₂ and Al ₂ O ₃ The reaction does not occur and can exist stably in each state, so that the stability of the obtained ceramic substrate can be enhanced.

In the ceramic substrate according to the present invention, since the filler of the ceramic sintered body provided therein contains ZrO ₂ , the thermal conductivity is lowered. Therefore, when an IC (such as a power amplifier IC) that generates heat relatively easily is mounted on the ceramic substrate, a temperature rise due to heat generation may be a problem.

In order to solve this problem, it is conceivable to provide a heat radiating via conductor or the like on the ceramic substrate. However, the ceramic substrate has a laminated structure constituted by the first and second ceramic layers. In this laminated structure, the first ceramic layer is made of a ceramic sintered body obtained by molding and firing the ceramic composition according to the present invention, and is positioned so as to form at least the outermost layer. If the second ceramic layer has a higher thermal conductivity than the first ceramic layer, for example, by forming the second ceramic layer from a ceramic sintered body not containing ZrO ₂ , special heat dissipation as described above is possible. Therefore, the degree of freedom in designing the ceramic substrate can be increased.

  FIG. 1 is a front view showing an electronic component 2 including a ceramic substrate 1 according to a first embodiment of the present invention, and the ceramic substrate 1 is shown in a sectional view.

  The ceramic substrate 1 includes a plurality of laminated ceramic layers 3.

  The ceramic substrate 1 further includes a wiring conductor. The wiring conductor is used to form a passive element such as a capacitor or an inductor, or to perform connection wiring such as an electrical connection between the elements. ˜6 and several via-hole conductors 7.

  The conductor film 4 is formed inside the ceramic substrate 1. Conductive films 5 and 6 are formed on the outer surface of ceramic substrate 1, that is, on one main surface and the other main surface, respectively. The via-hole conductor 7 is provided so as to be electrically connected to any one of the conductor films 4 to 6 and penetrate the specific ceramic layer 3 in the thickness direction.

  On one main surface of the ceramic substrate 1, chip components 8 and 9 are mounted in a state of being electrically connected to the external conductor film 5, and an electronic component 2 including the ceramic substrate 1 is configured.

To produce the ceramic substrate 1, 28-50 wt% SiO ₂ , 36-55 wt% MO (where MO is at least one of CaO and MgO), 0-20 wt% Al ₂ O ₃ , and A borosilicate glass powder composed of ₅ to 17.5% by weight of B ₂ O ₃ and a ceramic powder containing 1% by weight or more of ZrO ₂ are mixed, and the borosilicate glass powder is 40 to 80% by weight. A ceramic composition containing 60 to 20% by weight of ceramic powder is prepared.

Ceramic powder described above, if it contains a ceramic other than ZrO _2, As the ceramic other than the ZrO _2, it is preferred that only Al ₂ O _3.

  The ceramic composition described above is slurried by adding an organic vehicle or the like thereto. This slurry is formed into a sheet by applying, for example, a doctor blade method to the slurry, whereby a green sheet containing the ceramic composition is obtained. A conductive paste is applied to a specific one of the green sheets in order to form the conductive films 4 to 6 and the via-hole conductor 7 described above. The conductive paste preferably contains a low resistance metal such as Au, Ag, Ag—Pd, Ag—Pt, or Cu as a conductive component.

  Next, a raw laminated body is obtained by laminating the plurality of green sheets described above. The raw laminate is then fired at a temperature of 1000 ° C. or less, for example 900 ° C. Thereby, the ceramic substrate 1 is obtained. In this firing step, the above-described green sheet is sintered to become the ceramic layer 3, and the conductive paste is sintered to become the conductor films 4 to 6 and the via-hole conductor 7.

  In addition, in the state which prepared the green sheet for shrinkage | contraction suppression containing the inorganic material powder which does not sinter at the calcination temperature for obtaining the ceramic substrate 1 mentioned above, and this was piled up on the both main surfaces of the raw laminated body mentioned above. When the firing step is performed, the shrinkage-suppressing green sheet does not substantially shrink due to firing, and thus acts to suppress the shrinkage of the green sheet to be the ceramic layer 3. Therefore, in the obtained ceramic substrate 1, undesired deformation such as warpage can be made difficult to occur, and as a result, the dimensional accuracy of the ceramic substrate 1 can be increased.

The outer conductor films 5 and 6 formed on the outer surface of the ceramic substrate 1 obtained as described above are subjected to wet plating, for example, a nickel plating film and a solder or tin plating film thereon. Is formed. In this wet plating process, since the ceramic layer 3 provided in the ceramic substrate 1 includes ZrO ₂ in the ceramic sintered body constituting the ceramic layer 3, the MO component in the glass serving as the matrix of the ceramic sintered body is reduced. , ZrO ₂ dissolves or reacts. As a result, the acid resistance of the ceramic substrate 1 becomes good, and the MO component in the glass contained in the ceramic layer 3 can be made difficult to elute into the plating solution. For this reason, the ceramic substrate 1 is hardly damaged and the deterioration of the plating solution can be suppressed.

  Next, the electronic component 2 is completed through a process of mounting the chip components 8 and 9 so as to be electrically connected to the external conductor film 5 on one main surface of the ceramic substrate 1.

  FIG. 2 is a view corresponding to FIG. 1 for explaining a second embodiment of the present invention. In FIG. 2, elements corresponding to those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  The electronic component 2a shown in FIG. 2 includes a ceramic substrate 1a, and the ceramic substrate 1a has a laminated structure including first and second ceramic layers 3a and 3b. As can be seen from FIG. 2, in the laminated structure, the first ceramic layer 3a is positioned so as to form at least the outermost layer.

In such a ceramic substrate 1a, the first ceramic layer 3a is composed of a ceramic sintered body obtained by firing the same ceramic composition as the ceramic layer 3 shown in FIG. On the other hand, the second ceramic layer 3b has a higher thermal conductivity than the first ceramic layer 3a. Compared to the first ceramic layer 3a, the second ceramic layer 3b does not contain, for example, ZrO ₂ and has a composition containing Al ₂ O ₃ instead.

  According to the ceramic substrate 1a shown in FIG. 2, the low thermal conductivity of the first ceramic layer 3a is compensated by the second ceramic layer 3b, so that the overall thermal conductivity of the ceramic substrate 1a is relatively high. can do. Therefore, for example, even when the chip component 9 is a component that generates heat relatively easily such as a power amplifier IC, heat dissipation for suppressing a temperature rise due to the heat generation is performed relatively well in the ceramic substrate 1a. I can do it.

  Next, experimental examples carried out to confirm the effects of the present invention will be described.

Table 1 shows various compositions of the ceramic compositions prepared for obtaining the ceramic substrate produced in this experimental example. In Table 1, the “glass powder” column shows the composition of the borosilicate glass powder, and the “ceramic composition” column shows “ZrO ₂ ” contained in “glass powder” and “ceramic powder”. And the mixing ratio of “Al ₂ O ₃ ” is shown.

  A borosilicate glass powder and a ceramic powder having a composition as shown in Table 1 are prepared, and 100 parts by weight of an organic solvent is added to 100 parts by weight of an inorganic powder mixed at a mixing ratio as shown in Table 1. Further, 10 parts by weight of a butyral binder and 1 part by weight of a plasticizer were added, and wet-mixed under predetermined conditions to obtain a slurry. Next, the obtained slurry was formed into a sheet shape by a doctor blade method to obtain green sheets for a substrate having a thickness of about 50 μm and a thickness of about 100 μm, respectively.

  On the other hand, 100 parts by weight of an organic solvent is mixed with 100 parts by weight of alumina powder, 10 parts by weight of a butyral binder and 1 part by weight of a plasticizer are added thereto, and wet-mixed under predetermined conditions to obtain a slurry. Got. Next, the obtained slurry was formed into a sheet by a doctor blade method to obtain a green sheet for shrinkage suppression having a thickness of about 200 μm.

  Next, both the green sheet for substrate and the green sheet for shrinkage suppression were cut to have a planar size of 100 mm × 100 mm.

  Next, for the samples 1 to 17 and 20 to 31 shown in Table 1, one sheet for suppressing shrinkage, 10 sheets for green sheet for substrate of about 100 μm thickness, and one sheet for suppressing shrinkage are provided. The layers were laminated in this order, and the resulting raw composite laminate was pressed with a press.

  On the other hand, for Sample 18, one sheet of shrinkage-suppressing green sheet, one sheet of about 50 μm thick substrate having the composition labeled “surface layer” in the remarks column of Table 1, and “inner layer” are also displayed. In this order, nine green sheets for a substrate having a thickness of about 100 μm having the same composition, one green sheet for a substrate having a thickness of about 50 μm, which is also indicated as “surface layer”, and one green sheet for suppressing shrinkage are arranged in this order. The resulting raw composite laminate was pressed with a press.

  For sample 19, a raw composite was prepared in the same manner as in sample 18 except that the shrinkage-suppressing green sheets were not laminated at both ends in the lamination direction of the composite laminate in sample 18. A laminate was obtained.

  Next, the raw composite laminate after pressing described above is fired under the conditions of a firing temperature of 900 ° C. and a holding time of 10 minutes, and then for shrinkage suppression adhered to the surface of the fired sample in powder form The green sheet green body was removed by ultrasonic cleaning to obtain a ceramic substrate according to each sample.

  Next, after evaluating the warpage of the ceramic substrate according to each sample obtained, the ceramic substrate according to each sample was cut with a diamond cutter so as to have a plane size of 4 mm × 45 mm, and sintered and acid resistant. And the bending strength was evaluated. Moreover, it cut so that it might become a plane dimension of 8 mm x 8 mm, and heat conductivity was evaluated only about the specific sample.

  Regarding the warpage of the ceramic substrate, the ceramic substrate is placed on a flat plate, the height (T1) of the highest position from this plate and the thickness (T2) of the ceramic substrate are measured, and (T1-T2) Determined by

  Sinterability was evaluated by an ink test check.

  For acid resistance, each of the 10 samples was immersed in 1N sulfuric acid at 30 ° C. for 10 minutes, the weight loss before and after this immersion was determined, and this was evaluated as the amount eluted from the ceramic substrate.

  The bending strength was measured by three-point bending under conditions of a crosshead speed of 0.5 mm / min and a span of 30 mm.

  The thermal conductivity was measured at room temperature by the laser flash method.

  Table 2 shows the evaluation results of the above items.

  Of the samples shown in Table 2 and Table 1 above, Samples 1 to 19 are examples within the scope of the present invention, and Samples 20 to 31 are comparative examples outside the scope of the present invention.

  First, regarding the comparative example, in the sample 20, as shown in Table 1, since the glass powder content is as low as 35% by weight, which is less than 40% by weight, the softening / fluidization of the glass is difficult to occur in the firing process. As shown in Table 2, the sinterability was insufficient. On the other hand, in the sample 21, the glass powder content is as high as 85% by weight exceeding 80% by weight, so that the breakage starting from the defects inherent in the glass is likely to occur, and the strength of the ceramic substrate is insufficient.

Next, as shown in Table 1, in Sample 22, the amount of ZrO ₂ added in the ceramic powder was as low as 0.5% by weight, less than 1% by weight, and in Sample 23, ZrO ₂ was not added. Therefore, in both samples 22 and 23, a large amount of MO component remained in the glass, and as shown in Table 2, the acid resistance was insufficient.

Next, in the sample 24, as shown in Table 1, the glass powder contains 20% by weight of the ZrO ₂ component, and the ceramic powder does not contain ZrO ₂ . In this case, CaO, which is a network-modifying oxide in the glass, remains in the glass, so that elution into the acid is likely to occur, and as shown in Table 2, the acid resistance was insufficient. .

Next, in the sample 25, as shown in Table 1, the SiO ₂ component in the glass powder is as low as 20% by weight, which is less than 28% by weight. SiO ₂ is a glass network-forming oxide. In Sample 25, since this SiO ₂ was small, sufficient strength could not be obtained as shown in Table 2. On the other hand, in the sample 26, since the SiO ₂ component in the glass powder was as large as 54% by weight exceeding 50% by weight, the glass was hardly softened and fluidized, and the sinterability was insufficient.

In Sample 27, as shown in Table 1, the CaO component in the glass powder is as low as 30% by weight, less than 36% by weight. The CaO component is a glass network modifying oxide, and is a component that promotes softening and fluidization of glass. In sample 27, since this CaO component was small, the glass was not easily softened or fluidized, and as shown in Table 2, the sinterability was insufficient. On the other hand, in sample 28, the CaO component in the glass powder is as high as 60% by weight exceeding 55% by weight. For this reason, even if the ceramic powder contains 40% by weight of ZrO ₂ , the acid resistance was poor due to excessive CaO component remaining in the glass.

Next, in the sample 29, as shown in Table 1, the Al ₂ O ₃ component in the glass powder is as high as 24% by weight exceeding 20% by weight. Al ₂ O ₃ is a glass network intermediate oxide and stabilizes the glass structure. In sample 29, since this Al ₂ O ₃ is large, the glass is hardly softened and fluidized, and as shown in Table 2, the sinterability was insufficient.

Next, in the sample 30, as shown in Table 1, the B ₂ O ₃ component in the glass powder is as low as 2% by weight, less than 5% by weight. The B ₂ O ₃ component is a glass network-forming oxide, and is a component that lowers the softening temperature of glass and promotes viscous flow. In sample 30, since this B ₂ O ₃ component is small, the glass is hardly softened and fluidized, and as shown in Table 2, the sinterability was insufficient. On the other hand, in the sample 31, the B ₂ O ₃ component in the glass powder was as large as 22% by weight exceeding 17.5% by weight, so that the water resistance of the glass was not sufficient. Thus, if the water resistance of the glass is not sufficient, the ceramic substrate may be altered when used in an environment of high temperature and high humidity.

  On the other hand, Samples 1 to 19, which are examples within the scope of the present invention, as shown in Table 2, have obtained satisfactory results with respect to sinterability, acid resistance, bending strength and warpage. .

In particular, in Samples 1 to 5, as shown in Table 1, the ratio of glass powder / ceramic powder is changed in the range of 40/60 to 80/20. In these samples 1 to 5, since the CaO component in the glass powder was 43% by weight, the viscous flow of the glass was sufficient, and as shown in Table 2, good sinterability was exhibited. In addition, since the ceramic powder contains ZrO ₂ , CaO dissolves or reacts with ZrO ₂ to reduce the CaO component remaining in the glass, thereby improving the acid resistance and improving the ceramic into the acidic liquid. The amount of elution of the substrate was 1% by weight or less.

Next, in Samples 6 to 9, as shown in Table 1, both ZrO ₂ and Al ₂ O ₃ are used as the ceramic powder. As can be seen from these samples 6 to 9, by containing 1% by weight or more of ZrO ₂ with respect to the weight of the ceramic substrate, sufficient dissolution or reaction of the CaO component occurred, and as shown in Table 2, acid resistance As a result, the elution amount of the ceramic substrate in the acidic solution was 1.5% by weight or less.

  Next, in the sample 10, as shown in Table 1, a part of CaO in the glass powder is replaced with MgO. Even in this case, as shown in Table 2, the viscous flow of the glass was sufficient, the sinterability was sufficient, and the acid resistance and strength were sufficient.

Next, in Samples 11 to 17, as shown in Table 1, the weight ratio of SiO ₂ , CaO, Al ₂ O ₃ and B ₂ O ₃ which are components of the glass powder is changed to evaluate the characteristics of the ceramic substrate. It was done. In any of the samples 11 to 17, SiO ₂ is 28 to 50% by weight, CaO is 36 to 55% by weight, Al ₂ O ₃ is 0 to 20% by weight, and B ₂ O ₃ is 5 to 17.5% by weight. Within each range. Also, the ceramic powders are all made of ZrO _2, the ratio of the glass powder / ceramic powder is 60/40. As can be seen from Samples 11 to 17, if the range as described above is satisfied, as shown in Table 2, the glass has sufficient viscous flow, good sinterability, and the CaO component is ZrO _2. The CaO component remaining in the glass was reduced, the acid resistance was good, and the elution amount of the ceramic substrate in the acidic liquid was 1.5% by weight or less.

Next, in the sample 18, as shown in Table 1, a green sheet using ZrO ₂ as the ceramic powder is used as the surface layer, and a green sheet using Al ₂ O ₃ as the ceramic powder is used as the inner layer. When ZrO ₂ is used for the ceramic powder, the thermal conductivity becomes low, and the higher the ZrO ₂ content, the lower the thermal conductivity. This can be seen from the thermal conductivity of Samples 3, 4, 7 and 8 in Table 2. Such a decrease in thermal conductivity can be suppressed by positioning a ceramic layer obtained by firing a green sheet using Al ₂ O ₃ as the ceramic powder in the inner layer as in Sample 18. . This can be seen by comparing Sample 18 with Samples 3, 4, 7 and 8 for “thermal conductivity” in Table 2. Moreover, it can be seen from Table 2 that good acid resistance can be maintained by positioning a ceramic layer obtained by firing a green sheet using ZrO ₂ as the ceramic powder, as in Sample 18, on the surface layer.

  Next, the sample 19 is different from the sample 18 in that the green sheet for suppressing shrinkage is not used. Therefore, as shown in Table 2, the characteristics of the ceramic substrate excluding warpage were substantially the same as those of Sample 18, but the warpage of Sample 19 was relatively large at 350 μm. It was. However, this degree of warping is not a problem in practice.

It is a front view which shows the electronic component 2 provided with the ceramic substrate 1 by 1st Embodiment of this invention, and about the ceramic substrate 1, it has shown with sectional drawing. It is a figure equivalent to FIG. 1 which shows the electronic component 2a provided with the ceramic substrate 1a by 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Ceramic substrate 2,2a Electronic component 3 Ceramic layer 3a 1st ceramic layer 3b 2nd ceramic layer 4-6 Conductor film 7 Via-hole conductor 8,9 Chip component

Claims (7)

28 to 50 wt% SiO ₂ , 36 to 55 wt% MO (where MO is at least one of CaO and MgO), 0 to 20 wt% Al ₂ O ₃ , and 5 to 17.5 wt% A borosilicate glass powder composed of B ₂ O ₃ ;
A ceramic powder containing 1% by weight or more of ZrO ₂ is mixed,
Containing 40-80 wt% of the borosilicate glass powder and 60-20 wt% of the ceramic powder,
Ceramic composition. The ceramic composition according to claim 1, wherein the ceramic powder contains only Al ₂ O _{3 in} addition to ZrO ₂ .   A ceramic substrate provided with the ceramic sintered compact obtained by shape | molding and baking the ceramic composition of Claim 1 or 2. Having a laminated structure composed of first and second ceramic layers;
In the laminated structure, the first ceramic layer is positioned so as to form at least an outermost layer,
The first ceramic layer comprises a ceramic sintered body obtained by molding and firing the ceramic composition according to claim 1 or 2,
The second ceramic layer has a higher thermal conductivity than the first ceramic layer;
Ceramic substrate. The ceramic substrate according to claim 4, wherein the second ceramic layer does not contain ZrO ₂ .   The ceramic substrate according to claim 3, further comprising an external conductor film formed on an outer surface, wherein the external conductor film is subjected to wet plating.   An electronic component comprising the ceramic substrate according to claim 3.

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