JP4688460B2 - Glass ceramic multilayer wiring board with built-in capacitor - Google Patents

Description

The present invention relates to a capacitor-embedded glass ceramic multilayer wiring board in which a capacitor portion is built in an insulating base made of a glass ceramic sintered body.

  Conventionally, in the fields of portable electronic devices and portable information terminals, module boards in which resistors, capacitors, inductors, etc. are mounted on a substrate such as a printed circuit board as passive components are used together with a multilayer wiring board on which semiconductor elements are mounted. Has been. As such a multilayer wiring board, a glass ceramic multilayer wiring board capable of cofiring with a low melting point metal such as Ag or Cu having a small specific resistance is used.

However, in recent years, there has been a strong demand for downsizing, compounding, and high performance of components used in such portable electronic devices and portable information terminals, and as a passive component inside a multilayer wiring board on which a semiconductor element is mounted. The flow of integration of components in which electronic circuit elements having corresponding functions are incorporated and semiconductor elements and passive components are mounted at a high density is advancing. To a take write over there inside the multilayer wiring board of these passive components, eliminating the need to secure a mounting space for these passive components on the multilayer wiring substrate surface and to increase the freedom of design, miniaturization of the multilayer wiring board It can contribute to.

  For example, as shown in FIG. 1, a glass-ceramic multilayer wiring board 1 with a built-in capacitor has a dielectric layer 3 made of a dielectric material having a high dielectric constant such as barium titanate on an insulating substrate 2 and metal powder above and below it. The metal layer 4 made of the sintered body is formed and connected to the wiring layer 6 by the metal layer 4 and the through conductor 5.

  When it is necessary to form a capacitor locally, a dielectric paste made of a dielectric material is partially applied to a glass ceramic green sheet (hereinafter also referred to as a green sheet) for forming an insulating layer. After forming a layer, a green sheet on which a desired conductor pattern is formed and a green sheet on which a dielectric layer is formed are laminated, and the dielectric layer and the conductor pattern are fired simultaneously with the green sheet. You can also.

In general, a glass ceramic multilayer wiring board using a low melting point metal such as Ag or Cu as a wiring conductor is sintered at 800 ° C. to 1000 ° C., but a sintering temperature of a dielectric material mainly composed of barium titanate is 1200 to Since the temperature is 1300 ° C., low temperature sintering of the dielectric material is indispensable when the dielectric layer mainly composed of barium titanate is formed on the glass ceramic multilayer wiring board by simultaneous firing. For example, low temperature sintering of barium titanate is performed by pulverizing barium titanate particles and adding a small amount of glass as a sintering aid.
Tatsuya Ueda, “Low temperature fired multilayer substrates, high dielectric constant materials for built-in capacitors and their applications,” Fine Ceramics Report, Japan Fine Ceramics Association, 1996, Vol. 14, No. 8, p. 220-222 Nobuo Kamehara and Shinichi Niwa, “CR Composite Substrate”, New Ceramics, 1995, No. 1, p. 39-44

However, while the dielectric powder mainly composed of barium titanate has achieved an average particle size of 0.3 μm or less, the glass powder is limited to an average particle size of about 1 μm, and since the addition amount thereof is very small, segregation of glass even when thoroughly mixed dielectric powder and glass powder was not avoided. As a result, local variations in the composition of the dielectric sintered body and the presence of abnormally grown grains are unavoidable, and it is difficult to stabilize the characteristics of the built-in capacitor.

  In addition, interdiffusion of glass or the like occurs between the insulating substrate and the dielectric layer during the sintering process, and the insulating substrate reacts with the dielectric material, generating voids inside the insulating substrate, or the relative dielectric constant of the dielectric material. However, there is a problem that the insulation of the insulating substrate is lowered and the electric capacity of the built-in capacitor cannot be managed.

  In addition, since the insulating base made of a sintered body of glass and filler has a dielectric layer mainly composed of barium titanate, the insulating base and the dielectric are caused by the difference in the thermal shrinkage. Stress is generated between the layers. As a result, there is a problem that cracks are generated inside the insulating substrate and the insulating property of the insulating substrate is lowered.

  The present invention has been completed in view of the above-mentioned problems, and its purpose is to prevent segregation of glass, thereby having a uniform composition and no composition variation or abnormally grown grains in the dielectric sintered body. It is an object of the present invention to provide a capacitor built-in glass ceramic multilayer wiring board capable of forming a built-in capacitor having a high capacity and a stable capacity by forming a dielectric layer. Furthermore, when the insulating substrate and the dielectric layer are fired simultaneously, the difference in heat shrinkage between the insulating substrate and the dielectric layer is reduced, and the interdiffusion between the insulating substrate and the dielectric layer is suppressed, thereby increasing the An object of the present invention is to provide a capacitor built-in glass ceramic multilayer wiring board capable of forming an insulating base having insulation reliability and a high-capacity built-in capacitor.

The glass-ceramic multilayer wiring board with a built-in capacitor according to the present invention (hereinafter also referred to as a capacitor-embedded board) is a dielectric having barium titanate as a main component inside an insulating base made of a glass ceramic sintered body containing glass and filler. A capacitor-embedded glass-ceramic multilayer wiring board in which a capacitor portion made of a metal layer made of a sintered body of metal powder laminated on and under the layer is formed, wherein the dielectric layer is mainly composed of barium titanate And a perovskite compound powder having an average particle size of 0.3 μm or less and a glass powder having a softening temperature of 400 ° C. to 600 ° C., and the volume ratio of the perovskite compound in the sintered body is 90% by volume or more And the metal layer formed between the insulating substrate and the dielectric layer is made of Ag or Cu. 5 contains vol% or more, the capacitor portion, the which each dielectric diffusion barrier layer and metallization diffusion barrier layer of the upper and lower surfaces of the capacitor portion is formed by sequentially laminating the metallized diffusion barrier layer has an average particle size Ri formed of a sintered body of 2μm to 5μm der Ru a g powder or Cu powder, wherein the metal layer, characterized that you have independently without being connected.

  In the present invention, preferably, the metal layer formed between the insulating base and the dielectric layer has a thickness of 10 μm or more.

  In the present invention, it is preferable that the metal layer formed between the insulating base and the dielectric layer is made of an Ag powder or Cu powder sintered body having an average particle diameter of 2 μm to 5 μm. It is characterized by.

In the present invention, it is preferable that the dielectric layer contains barium titanate as a main component, glass containing B ₂ O ₃ , SiO ₂ , CaO, BaO, and ZnO, and CuO. The content of CuO is 2 to 10 parts by mass with respect to 100 parts by mass of barium titanate, respectively.

According to the substrate with a built-in capacitor of the present invention, since the average particle size of the perovskite compound powder mainly composed of barium titanate is 0.3 μm or less, the firing temperature of a general glass ceramic multilayer wiring substrate is 800 ° C. Liquid phase sintering of the perovskite compound powder is possible at 1000 to 1000 ° C. This is because in the final stage of liquid phase sintering, the perovskite powder having a small particle size dissolves in the liquid phase glass and precipitates as a perovskite powder having a large particle size, and grain growth proceeds. This is because the solubility in the liquid phase glass increases as the particle size decreases.

  Further, since the softening temperature of the glass powder is set to 400 ° C. to 600 ° C., a liquid phase is generated between the perovskite compound powders at 400 ° C. or higher when the volatile decomposition of the organic binder component contained in the dielectric layer before sintering is completed. . At this time, since the glass amount is 10% by volume or less in the volume ratio, the liquid phase glass is segregated between the perovskite compound powders. However, since the viscosity of the glass decreases exponentially as the temperature increases, a uniform glass between the perovskite compound powders in the temperature range of 800 ° C. to 1000 ° C., which is the firing temperature of a general glass ceramic multilayer wiring board. Can be filled with liquid phase. As a result, the dielectric layer can have a local composition variation due to segregation of glass and an abnormally grown grain of the perovskite compound powder, and the characteristics of the capacitor portion can be stabilized. Further, when the dielectric layer is observed by a cross-sectional area, 90% by volume or more of the dielectric layer is a sintered body of the perovskite compound powder, so that the dielectric constant of the dielectric layer can be increased.

  Further, since the metal layer formed between the insulating substrate and the dielectric layer is a sintered body of low melting point metal powder containing 95% by volume or more of Ag or Cu, the metal layer is heated to 700 ° C. A dense sintered body can be obtained at 900 ° C. Thereby, the mutual diffusion of the glass between the insulating substrate and the dielectric layer can be prevented, and the reaction between the insulating substrate material and the dielectric material can be suppressed. As a result, the insulating substrate and the dielectric layer do not react to generate voids inside the insulating substrate, and the dielectric constant of the dielectric layer does not significantly decrease. Therefore, the insulation reliability of the insulating substrate is high, and the capacitor portion can have a high capacity.

  In the capacitor-embedded substrate of the present invention, the thickness of the metal layer formed between the insulating base and the dielectric layer is preferably 10 μm or more. Diffusion can be suppressed more effectively, and stress caused by the difference in thermal expansion coefficient between the insulating substrate and the dielectric layer can be effectively alleviated. As a result, it is possible to obtain a capacitor built-in substrate in which a capacitor portion and an insulating base are not cracked and a high-capacity capacitor is built in.

  Further, in the capacitor-embedded substrate of the present invention, the metal layer formed between the insulating base and the dielectric layer is preferably a sintered body of Ag powder or Cu powder having an average particle diameter of 2 μm or more. Therefore, the heat shrinkage characteristic of the metal layer can be made closer to the heat shrinkage curve side of the insulating substrate than the heat shrinkage characteristic of the dielectric layer, and the stress generated by the difference in the heat shrinkage characteristic of the insulating substrate and the dielectric layer can be reduced. Can be relaxed by the heat shrinkage property of the metal layer formed between the metal layer and the dielectric layer.

  That is, in the substrate with a built-in capacitor according to the present invention, the dielectric layer is a sintered body of a perovskite compound powder and a glass powder having a softening temperature of 400 ° C. to 600 ° C. In the process of wetting and spreading the phased glass, a force in the attractive direction acts between the perovskite compound powders, and the rearrangement of the perovskite compound powders causes shrinkage of the unsintered dielectric layer from 600 to 700 ° C. This shrinkage start temperature is lower than the shrinkage start temperature of a general glass ceramic sintered body, and it is unsintered due to the stress generated by the difference in thermal shrinkage characteristics between the insulating substrate and the dielectric layer, so that the temporary strength of the insulating substrate is low. Cracks may occur in the fired body. However, by reducing the heat shrinkage characteristics of the metal layer formed between the insulating base and the dielectric layer closer to the insulating base than the heat shrink characteristics of the dielectric layer, the stress generated in the insulating base is relaxed and unsintered. It is possible to prevent cracks from occurring in the insulating substrate. In addition, since the heat shrink property of the metal layer is controlled not by the addition of the glass component but by the particle size of the metal powder, the glass component added to the metal layer diffuses, and the sintered body and metal comprising the perovskite compound powder and the glass powder. The dielectric constant of the dielectric layer is not significantly lowered by reaction with the glass component added to the layer.

  In addition, since the metal layer formed between the insulating substrate and the dielectric layer is a sintered body of Ag powder or Cu powder having an average particle size of 5 μm or less, the metal layer is further heated at 700 ° C. to 900 ° C. It becomes a dense sintered body and can suppress mutual diffusion between the dielectric layer and the insulating substrate. As a result, it is possible to obtain a capacitor built-in substrate having a high insulation reliability of the insulating base and a high capacitance of the capacitor portion.

In addition, according to the substrate with built-in capacitor of the present invention, the dielectric diffusion prevention layer and the metallized diffusion prevention layer are sequentially laminated on the upper and lower surfaces of the capacitor part, so that the influence of diffusion from the insulating substrate to the dielectric layer is reduced. It can be made even smaller. As a result, the capacitor portion can be made to have higher insulation reliability.

Further, in the capacitor-embedded substrate of the present invention, preferably, the dielectric layer contains barium titanate as a main component, glass containing B ₂ O ₃ , SiO ₂ , CaO, BaO and ZnO, and CuO. Since the content of glass and CuO is 2 to 10 parts by mass with respect to 100 parts by mass of barium titanate, the dielectric layer becomes a dense sintered body in the temperature range of 800 ° C. to 1000 ° C. The capacity of can be increased.

  The substrate with built-in capacitor according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 2 is a cross-sectional view for explaining an example of the embodiment of the substrate with built-in capacitor of the present invention. The capacitor built-in substrate 10 of the present invention includes an insulating substrate 11 formed by laminating a plurality of insulating layers 11a and 11b, a plurality of dielectric layers 12a to 12c, a plurality of metal layers 13a to 13d, a wiring layer 14, And a through conductor 15.

The insulating layers 11a and 11b in the capacitor built-in substrate 10 of the present invention are made of a sintered body of a glass component and ceramic powder (ceramic filler). Examples of the glass component include SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M is Glass of Ca, Sr, Mg, Ba or Zn) and the like, and the softening temperature of the glass component is selected in the range of 750 ° C. to 950 ° C. Examples of the ceramic powder include Al ₂ O ₃ , SiO ₂ , composite oxide of ZrO ₂ and alkaline earth metal oxide, composite oxide of TiO ₂ and alkaline earth metal oxide, Al ₂ O _3. And composite oxides containing at least one selected from SiO ₂ (for example, spinel, mullite, cordierite) and the like.

  The green sheet, which is a green sheet before firing of the insulating layers 11a and 11b, is made by adding and mixing glass powder and ceramic powder, an organic binder, an organic solvent, a plasticizer and the like into a slurry, and using the slurry, a doctor blade Molding is performed by adopting the method or calendar roll method. As the organic binder, those conventionally used for ceramic green sheets can be used. For example, acrylic (acrylic acid, methacrylic acid or ester homopolymer or copolymer, specifically acrylic Homopolymers such as acid ester copolymers, methacrylate ester copolymers, acrylic ester-methacrylic ester copolymers, etc.), polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene carbonate, cellulose, etc. Or a copolymer is mentioned.

  As an organic solvent used in a slurry for forming a green sheet, the organic solvent, glass powder, ceramic powder, and an organic binder are kneaded to obtain a slurry having a viscosity suitable for green sheet forming, for example, carbonization. Examples thereof include hydrogen, ethers, esters, ketones, alcohols and the like.

  A through hole is formed in the green sheet produced as described above by mechanical processing such as die processing, laser processing, micro drilling, punching, or the like as necessary. This through hole is filled with a paste for penetrating conductor obtained by adding an appropriate organic binder and solvent to a metal powder such as Ag, Cu, Ag-Pt, Ag-Pd, and glass powder, and then mixed with the screen through printing. A conductor 15 is formed.

  In addition, a paste for wiring conductor in which a metal powder such as Ag, Cu, Ag-Pt, or Ag-Pd and a glass powder is mixed with a suitable organic binder and solvent is applied to the surface of these green sheets by screen printing or the like. Then, the wiring layer 14 may be formed.

  In the present invention, the dielectric layers 12a, 12b, and 12c are made of a sintered body of a perovskite compound powder mainly composed of barium titanate powder and a sintering aid such as glass powder. Here, the glass powder used as the sintering aid needs to have a softening temperature of 400 to 600 ° C. Since the softening temperature of the glass powder is set to 400 to 600 ° C., the glass powder is unevenly distributed between the perovskite compound powders mainly composed of barium titanate at 400 to 600 ° C. to generate a liquid phase of the glass. However, since the viscosity of the glass decreases exponentially as the temperature rises, the glass glass multilayer wiring board firing temperature of 800 ° C. to 1000 ° C. is a small glass amount of 10% by volume or less at a volume ratio. Even between them, the space between the perovskite compound powders can be filled with a uniform glass liquid phase. As a result, the dielectric layers 12a, 12b, and 12c can be made dielectric layers 12a, 12b, and 12c without local compositional variation due to glass segregation and abnormally grown grains of the perovskite powder. Stabilization is possible. Further, since the dielectric layers 12a, 12b, and 12c are composed of a perovskite compound mainly composed of barium titanate when the cross-sectional area is observed, the volume ratio is 90% by volume or more, so that the dielectric layers 12a, 12b, and 12c The dielectric constant can be increased.

For example, examples of the glass powder having a softening temperature of 400 ° C. to 600 ° C. include glass powder containing B ₂ O ₃ , SiO ₂ , CaO, BaO, and ZnO.

  In the present invention, in order to make the dielectric layer a dense sintered body having a high dielectric constant and high reliability, the average particle size of the perovskite compound powder needs to be 0.3 μm or less. That is, in the final stage of sintering of the perovskite compound powder and the glass powder, the perovskite compound powder having a small particle size is dissolved in the liquid phase glass and precipitated on the perovskite compound powder having a large particle size. Growth progresses. Since the solubility of the perovskite compound powder in the liquid phase glass increases as the particle size decreases, the perovskite compound has a denseness at a temperature of 800 ° C. to 1000 ° C. which is a firing temperature of a general glass ceramic multilayer wiring board. In order to obtain a sintered body, the average particle size of the perovskite compound powder needs to be 0.3 μm. When the average particle size of the perovskite compound powder exceeds 0.3 μm, the grain growth of the perovskite compound powder does not proceed sufficiently and a dense sintered body cannot be obtained.

  In addition, the perovskite compound powder having barium titanate as a main component here is one in which a part of barium titanate is replaced with Mg, Ca, Sr or the like, or barium titanate powder and magnesium titanate powder. , Calcium titanate powder, strontium titanate powder, and the like are mixed, and after sintering, Mg, Ca, Sr are replaced with some elements of barium titanate.

  The dielectric green sheet, which is a green sheet before firing of the dielectric layers 12a, 12b, and 12c, is prepared by adding and mixing barium titanate powder and glass powder with an organic binder, an organic solvent, a plasticizer, and the like. The slurry is molded by adopting a doctor blade method or a calendar roll method. As the organic binder added to and mixed with the barium titanate powder and the glass powder, those used for the ceramic green sheet constituting the insulating substrate 11 can be used. For example, acrylic (acrylic acid, methacrylic acid or those) Homopolymers or copolymers of esters, specifically acrylic ester copolymers, methacrylic ester copolymers, acrylic ester-methacrylic ester copolymers, etc.), polyvinyl butyral, polyvinyl alcohol, Examples include homopolymers or copolymers such as acrylic-styrene, polypropylene carbonate, and cellulose.

  As an organic solvent used in a slurry for forming a green sheet, the organic solvent, glass powder, ceramic powder, and an organic binder are kneaded to obtain a slurry having a viscosity suitable for green sheet forming, for example, carbonization. Examples thereof include hydrogen, ethers, esters, ketones, alcohols and the like.

  The metal layers 13a, 13b, 13c, and 13d are obtained by screen printing or the like using a dielectric green sheet and a metal paste obtained by adding an appropriate organic binder and solvent to a metal powder mainly composed of Ag or Cu. Can be formed by coating.

  Since the metal layers 13a and 13d formed between the insulating base 11 and the dielectric layer 12 are made of a sintered metal powder containing 95% by volume or more of Ag or Cu which is a low melting point metal, The metal layers 13a and 13d can be formed into a dense sintered body at 700 ° C. to 900 ° C. Thereby, the mutual diffusion of the glass between the insulating base 11 and the dielectric layers 12a and 12c can be prevented, and the reaction between the insulating base 11 and the dielectric layers 12a and 12c can be suppressed. As a result, the material of the insulating base 11 and the dielectric layers 12a and 12c do not react to generate voids inside the insulating base 11, and the dielectric constants of the dielectric layers 12a and 12c are not significantly reduced. Therefore, the insulation reliability of the insulating base 11 can be increased, and the capacitor portion can have a high capacity.

The thickness of the metal layers 13a and 13d is preferably 10 μm or more. Thereby, the mutual diffusion between the insulating base 11 and the dielectric layers 12a and 12c is effectively suppressed, and the stress due to the difference in thermal expansion coefficient between the insulating base 11 and the dielectric layers 12a and 12c is also effective. It is possible to alleviate the damage, and it is possible to prevent the occurrence of defects such as cracks in the insulating substrate 11 and the dielectric layers 12 a and 12 c.

  If the thickness of the metal layers 13a and 13d is smaller than 10 μm, the difference in thermal expansion coefficient between the dielectric layers 12a and 12c and the insulating base 11 cannot be sufficiently relaxed, and cracks may be formed in the dielectric layers 12a and 12c. The upper limit of the thickness of the metal layers 13a and 13d is not a problem as long as it does not exceed the range of the metallized thickness used in a general glass ceramic multilayer wiring board.

  More preferably, the metal layers 13a and 13d are made of a sintered body of a paste of Ag powder or Cu powder (metal powder) having an average particle diameter of 2 μm to 5 μm. Since the dielectric layers 12a, 12b, and 12c are sintered bodies of the perovskite compound powder and the glass powder having a softening temperature of 400 to 600 ° C., the dielectric layers 12a, 12b, and 12c are formed between the perovskite compound powders in the process of spreading the glass between the perovskite compound powders. A force in the attractive direction acts to cause rearrangement of the perovskite compound powder. As a result, the shrinkage of the unsintered dielectric layers 12a, 12b, and 12c starts from 600 to 700 ° C. This shrinkage start temperature is lower than the shrinkage start temperature of a general glass ceramic sintered body, and the strength is unsintered due to the stress generated by the difference in thermal shrinkage characteristics between the insulating substrate 11 and the dielectric layers 12a, 12b, and 12c. Cracks may occur in the calcined body of the low insulating substrate 11.

  By setting the average particle diameter of Ag powder or Cu powder to 2 μm or more, the heat shrinkage characteristics of the metal layers 13a, 13d are made closer to the heat shrinkage curve side of the insulating substrate 11 than the heat shrinkage characteristics of the dielectric layers 12a, 12b, 12c. be able to. As a result, the stress generated by the difference in heat shrinkage characteristics between the insulating base 11 and the dielectric layers 12a, 12b, and 12c is caused by the metal layers 13a and 13d formed between the insulating base 11 and the dielectric layers 12a and 12c. It can be mitigated by heat shrinkage characteristics. Further, since the heat shrinkage characteristics are not controlled by the addition amount of the glass component but by the particle size of the Ag powder or Cu powder, the perovskite compound that forms the dielectric layers 12a and 12c with the glass component of the metal layers 13a and 13d. The dielectric constant of the dielectric layers 12a and 12c does not significantly decrease due to the reaction between the powder and the sintered body of the glass powder.

Further, in the present invention, preferably, the metal layers 13a and 13d are made of a sintered body of Ag powder or Cu powder having an average particle size not exceeding 5 μm. By forming a bonded body, mutual diffusion between the insulating substrate 11 and the dielectric layer 12 can be suppressed. As a result, the insulating substrate 11 of the capacitor-embedded substrate 10 has high insulation reliability free from cracks and voids, and the capacitor-embedded substrate 10 capable of forming a high-capacitance capacitor portion can be obtained.

  When the average particle diameter of the Ag powder or Cu powder forming the metal layers 13a and 13d is smaller than 2 μm, the heat shrink characteristics of the metal layers 13a and 13d approach the heat shrink characteristics of the dielectric layers 12a, 12b, and 12c. 11 and the dielectric layers 12a, 12b, and 12c have no effect of relieving stress due to the difference in thermal shrinkage characteristics. When the average particle diameter of the Ag powder or Cu powder is larger than 5 μm, the metal layers 13a and 13d are not sufficiently densified, and the reaction between the insulating base 11 and the dielectric layers 12a, 12b, and 12c cannot be prevented. There is.

Moreover, co the respective upper and lower surfaces of the capacitor portion, by sequentially laminating a dielectric diffusion barrier layer and metallization diffusion barrier layer can be made higher insulation reliability of the capacitor portion.

  Furthermore, the green sheet used as the insulating substrate 11 and the dielectric green sheet are heat-pressed at a pressure of 3 to 20 MPa and a temperature of 50 to 80 ° C. to produce a laminate. After that, for example, when the sintered body of the metal powder forming the wiring layer 14 or the metal layers 13a to 13d is Ag, the wiring layer 14 or the metal layers 13a to 13c are formed at a temperature of 800 to 1000 ° C. in the atmosphere. When the sintered body of the metal powder is Cu, the capacitor-embedded substrate 10 of the present invention is obtained by firing the laminate in a nitrogen atmosphere.

  In addition, when the laminate is fired, a constrained green sheet made of an inorganic component that does not substantially shrink and shrink at the temperature at which the green sheet sinters, such as alumina, is laminated on both sides of the laminate and fired. Since the shrinkage at the time of firing in the main surface direction of the multilayer body is restrained and suppressed by the sheet, warpage and deformation of the capacitor built-in substrate 10 can be more suitably suppressed.

  Furthermore, the wiring layer 14 located on the surface of the capacitor built-in substrate 10 is made of nickel, copper, gold, or the like in order to improve solder wettability when mounting electronic components on the surface and to prevent corrosion of the wiring layer 14. A plating layer may be applied.

Further, main Taraizu diffusion preventing layer, the method of forming the dielectric diffusion barrier layer is agnostic example above. In the embodiment of the present invention, an example in which a capacitor having three dielectric layers 12a to 12c is incorporated has been described. However, the number of dielectric layers may be any. It may be formed using a green sheet, or a dielectric paste applied thereto.

  Examples of the substrate with built-in capacitor according to the present invention will be described below.

In order to obtain a green sheet serving as an insulating base of the substrate with a built-in capacitor, 50 parts by mass of SiO ₂ —CaO—MgO glass powder as glass and 50 parts by mass of Al ₂ O ₃ powder as ceramic filler are mixed, and this inorganic powder To 100 parts by mass, 12 parts by mass of an acrylic resin as an organic binder, 6 parts by mass of a phthalic acid plasticizer, and 30 parts by mass of toluene as a solvent were added and mixed by a ball mill method to obtain a slurry. Using this slurry, a green sheet having a thickness of 200 μm was formed by a doctor blade method.

Similarly, in order to obtain a dielectric green sheet serving as a dielectric layer of a capacitor-embedded substrate, B ₂ O ₃ , SiO ₂ , CaO, BaO and ZnO are included as sintering aids with respect to 100 parts by mass of barium titanate powder. 5 parts by mass of glass powder and 5 parts by mass of CuO powder are mixed, 100 parts by mass of this inorganic powder, 12 parts by mass of polyvinyl butyral resin as an organic binder, 6 parts by mass of phthalic acid plasticizer, and toluene 30 as a solvent. A part by mass was added and mixed by a ball mill method to obtain a slurry. Using this slurry, a dielectric green sheet having a thickness of 30 μm was formed by a doctor blade method.

Here, by changing the ratio of B ₂ O ₃ in the glass powder containing B ₂ O ₃ , SiO ₂ , CaO, BaO and ZnO, the softening point of the glass used as a sintering aid is 520 ° C. and 590 ° C. , 650 ° C., and dielectric green sheets 1 to 3 were respectively formed. Moreover, regarding the softening point of glass, it is the result of having measured by DTA (differential thermal analysis) using the temperature increase rate of 10 degree-C / min.

Furthermore, in order to obtain a constrained green sheet that suppresses sintering shrinkage of the capacitor-embedded substrate substantially in the planar direction, 100 parts by mass of Al ₂ O ₃ powder, 12 parts by mass of an acrylic resin as an organic binder, and 6 parts by mass of a phthalic acid plasticizer 30 parts by mass of toluene as a part and a solvent were added and mixed by a ball mill method to obtain a slurry. Using this slurry, a constrained green sheet having a thickness of 200 μm was formed by a doctor blade method.

  Next, on the dielectric green sheet and the green sheet, a metal layer paste to be a metal layer was applied by a screen printing method and dried at 70 ° C. for 30 minutes to form a 10 mm square metal layer. The metal layer paste was prepared by adding 12 parts by mass of an acrylic resin and 6 parts by mass of α-terpineol as an organic solvent to 100 parts by mass of the Ag powder having the particle sizes shown in Tables 1 to 3, and thoroughly mixing them with a stirring deaerator. A thing was used.

  A through hole was formed in a predetermined position on the green sheet and the dielectric green sheet using a punching machine, and this through hole was filled with a paste for a through conductor by a screen printing method. As a paste for penetrating conductor, 10 parts by mass of glass powder is added to 100 parts by mass of Ag powder (average particle size 3 μm), and a predetermined amount of acrylic resin and terpineol are added as an organic binder. Were mixed thoroughly.

Then vacuum heat-pressing a green sheet and a dielectric green sheet in 5MPa pressure and temperature of 50 ° C., to produce a laminated body shown in FIG. 2, FIG. Furthermore, constrained green sheets were vacuum hot-pressed at a pressure of 5 MPa and a temperature of 50 ° C. above and below the laminate.

  Next, this laminate is fired in a firing process comprising a binder combustion process at 500 ° C. for 3 hours and a ceramic sintering process at 900 ° C. for 1 hour, and an insulating material comprising a dense glass ceramic sintered body. Capacitor-embedded substrates (samples 1 to 9) each having a dielectric layer disposed by simultaneous firing inside the body were obtained.

In order to investigate the influence of the softening temperature of the glass used as the sintering aid, laminated blocks 1 to 3 each having 5 layers of dielectric green sheets 1 and 2 were produced, and the relative dielectric constant was measured. Here, the relative permittivity is printed on the laminate blocks 1 to 3 with an electrode pattern (area S) of φ (diameter) 10 mm vertically, the capacity is C, the thickness of the sample is d, and the permittivity of vacuum is ε _0. Is a value obtained from ε = C × d / ε ₀ S. The capacity measurement results are shown in Table 1. Table 1 shows the results of investigation on the softening point of glass added as a sintering aid in the dielectric green sheet and the relative dielectric constant of the laminated and sintered dielectric green sheets. Here, the determination was made with the case where the relative dielectric constant exceeded 1000 as ◯ and the case where the relative dielectric constant did not exceed as ×.

  From Table 1, it was found that when a glass powder having a softening temperature of 650 ° C. is used as a sintering aid, the dielectric constant of the dielectric layer is not sufficiently high.

  Further, the cross sections of the laminate blocks 1 to 3 were mirror-finished and then observed with an SEM. As a result, the segregation of glass was observed in the laminate block 3, and it was confirmed that no glass was locally present between the perovskite compound powders and the perovskite compound did not proceed with sintering.

  Next, in order to investigate the influence of the particle diameter of Ag forming the metal layer, the cracks of the insulating base and the capacitance values thereof were measured for the substrates with built-in capacitors of Samples 1 to 6. The shapes of samples 1 to 6 are shown in FIG. In FIG. 3, the dielectric layers 102 a to 102 c are formed using the dielectric green sheet 1.

Regarding the crack of the insulating substrate, the cross section of the capacitor-embedded substrate was mirror-polished and then observed with a metal microscope (100 times magnification). Also. The capacity was measured using an impedance measuring instrument (manufactured by Agilent Technologies) under the conditions of a measurement frequency of 1 MHz and a measurement temperature of 25 ° C. The relative dielectric constants shown in Table 2 are average dielectric constants of the dielectric layers 102a to 102c. The measured capacitance is C, the sample thickness is d, the applied electrode area is S, and the vacuum dielectric constant is ε. _{When 0} , it is a value obtained from ε = C × d / ε ₀ S.

Table 2 shows the results of investigating the presence or absence of cracks in the insulating substrate when the average particle diameter of the Ag powder forming the metal layer was changed in the sample shape shown in FIG. Here, the determination was made with ○ indicating that there was no crack and having a relative dielectric constant exceeding 1000, and × indicating other. Table 3 shows the particle size distribution of the average particle diameter of each Ag powder.

  From Tables 2 and 3, when the particle size of the Ag powder is in the range of 2 μm to 5 μm, there is no crack in the insulating substrate, so that the insulation reliability is high, and because the dielectric layer has a high relative dielectric constant, a high-capacitance built-in capacitor substrate Confirmed to get.

Next, Table 4 shows the results of investigation on the dielectric constant and dielectric breakdown voltage of the capacitor portion with respect to the effects of the dielectric diffusion prevention layer and the metallization diffusion prevention layer. The shape of sample 7-9 are shown in Figure 2. In FIG. 2 , the dielectric layers 12 a to 12 c are formed using the dielectric green sheet 1. Here, the relative dielectric constant is ε = C × d / ε ₀ S, where C is the obtained capacitance, d is the thickness of the dielectric layer, S is the area of the capacitor portion, and ε ₀ is the dielectric constant of the vacuum. In addition, when the dielectric breakdown voltage is S = 75 mm ² and d = 15 μm, when the voltage is boosted at 10 V / sec, the voltage with a leakage current value exceeding 1 μA is regarded as the dielectric breakdown voltage. However, the area S of the metal layer is the sum of samples 1 to 6 in which a metal layer is formed in a square of 5 mm square and three layers are connected in parallel, and samples 7 to 9 are squares of 8.8 mm square in the metal layer. The value of what was formed. Further, in the determination, the minimum value of the dielectric breakdown voltage is higher than 250V and the relative dielectric constant exceeds 1000, and the others are Δ.

  From Table 4, a dielectric layer having a high relative dielectric constant and a high dielectric breakdown voltage was formed by providing a dielectric diffusion preventing layer and a metallized diffusion preventing layer.

It is sectional drawing which shows one example of the conventional glass ceramic multilayer wiring board with a built-in capacitor | condenser. It is sectional drawing which shows an example of embodiment about the glass-ceramic multilayer wiring board with a built-in capacitor | condenser of this invention. It is a cross-sectional view showing another example of a capacitor built-in glass ceramic multilayer wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass ceramic multilayer wiring board 2 with a capacitor | condenser 2 ... Insulation base | substrate 3 ... Dielectric layer 4 ... Metal layer 5 ... Through conductor 6 ... Wiring layer 10 ... Glass ceramic with a built-in capacitor Multilayer wiring boards 12a to 12c ... Dielectric layers 13a to 13d ... Metal layer 14 ... Wiring layer 15 ... Through conductor

Claims (4)

Capacitor comprising a dielectric layer mainly composed of barium titanate and a metal layer composed of a sintered body of metal powder laminated on the upper and lower sides of an insulating base composed of a glass ceramic sintered body containing glass and filler. Wherein the dielectric layer has a perovskite compound powder having a mean particle size of 0.3 μm or less and a softening temperature of 400 ° C. to 400 ° C. The metal formed of a sintered body with a glass powder at 600 ° C., the volume ratio of the perovskite compound in the sintered body being 90% by volume or more, and formed between the insulating substrate and the dielectric layer The layer contains 95% by volume or more of Ag or Cu, and the capacitor portion is provided with a dielectric on each of the upper and lower surfaces of the capacitor portion Preventing dispersion layer and metallization diffusion barrier layer is formed are sequentially laminated, wherein the metallized diffusion barrier layer, Ri formed of a sintered body having an average particle diameter of Ru 2μm to 5μm der A g powder or Cu powder, the internal capacitors glass ceramic multilayer wiring substrate characterized that you have independently without being connected to the metal layer.   2. The glass ceramic multilayer wiring board with a built-in capacitor according to claim 1, wherein the metal layer formed between the insulating base and the dielectric layer has a thickness of 10 [mu] m or more.   2. The metal layer formed between the insulating base and the dielectric layer is made of a sintered body of Ag powder or Cu powder having an average particle diameter of 2 μm to 5 μm. The glass-ceramic multilayer wiring board with a built-in capacitor according to claim 2. The dielectric layer contains barium titanate as a main component and contains glass containing B ₂ O ₃ , SiO ₂ , CaO, BaO and ZnO and CuO, and the glass and CuO are each barium titanate 100. The glass-ceramic multilayer wiring board with a built-in capacitor according to any one of claims 1 to 3, wherein the content with respect to the mass part is 2 to 10 parts by mass.

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