JP2005159126A - Glass ceramic wiring board incorporated with capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass ceramic wiring board incorporated with a capacitor for suppressing the inter-dissipation of a dielectric layer and a glass ceramic laminate and an electrode layer, for preventing the deterioration of the capacitor formed in a glass ceramic wiring board, and for suppressing the fluctuation of the capacity. <P>SOLUTION: In this glass wiring board incorporated with a capacitor, a capacitor configured by oppositely arranging two-layer structured electrode layers respectively constituted of a pair of first electrode layer 2 and second electrode layer 3 with a dielectric layer 4 constituted of barium titanium interposed is incorporated inside an insulating substrate constituted of glass ceramics. The first electrode layer 2 is constituted of a sintered body made of spherical Cu powder whose integrated 50% grain diameter ranges from 0.8 to 1.2 μm, and whose integrated 10% grain diameter is 0.5 μm or more, and the second electrode layer 3 is constituted of a sintered body made of Cu powder of a 100 parts by weight and glass powder of 0.1 to 10 parts by weight. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a glass-ceramic wiring board with a built-in capacitor in which a capacitive element (capacitor) is built in an insulating layer 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 as passive components on a wiring board such as a printed circuit board are used together with wiring boards on which semiconductor elements are mounted. Has been.

  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 wiring board on which a semiconductor element is mounted. There is an increasing trend of integration in which electronic circuit elements having corresponding functions are incorporated and semiconductor elements and passive components are mounted at high density. Incorporating these passive components into the wiring board eliminates the need for securing a mounting space for the passive components on the surface of the wiring board and increases the degree of freedom in design, thereby contributing to the miniaturization of the wiring board. .

When forming a glass-ceramic wiring board with a built-in capacitor, a dielectric paste is partially applied to a glass-ceramic green sheet as an insulating layer to form a dielectric layer for forming a capacitance. A method of forming a glass ceramic green sheet on which a desired conductor pattern to be an electrode for forming is laminated and a glass ceramic green sheet on which the above dielectric layer is formed, and simultaneously firing the glass ceramic laminate. Is adopted.
JP-A-6-164150

  However, when an electrode layer and a dielectric layer are formed inside the glass ceramic laminate and fired at the same time, the components of the dielectric layer diffuse into the glass ceramic laminate and the electrode layer, and the dielectric layer is sintered. Sex was sometimes inhibited. Further, due to the firing shrinkage difference between the dielectric layer, the glass ceramic laminate, and the electrode layer, peeling or cracking may occur between the layers of the glass ceramic laminate and the electrode layer after firing. For this reason, there has been a problem that the electric capacitance value of the capacitor formed inside the glass ceramic wiring substrate is lowered or the variation of the capacitance value is increased.

  The present invention has been completed in view of the above problems, and its purpose is to suppress interdiffusion between the dielectric layer, the glass-ceramic laminate and the electrode layer, and further, the occurrence of delamination and cracks between the respective layers. It is an object of the present invention to provide a glass-ceramic wiring board with a built-in capacitor that suppresses the above, prevents a decrease in capacitance of a capacitor formed in the glass-ceramic wiring board, and suppresses the variation.

  The glass-ceramic wiring board with a built-in capacitor according to the present invention has a built-in capacitor in which a pair of electrode layers are opposed to each other with a dielectric layer made of barium titanate sandwiched inside an insulating substrate made of glass ceramics. The electrode layer includes a first electrode layer made of a sintered body of Cu powder arranged on the dielectric layer side, and a second electrode made of a sintered body of Cu powder and glass powder arranged on the glass ceramic side. The electrode layer has a two-layer structure.

  The glass-ceramic wiring board with a built-in capacitor according to the present invention is preferably configured as described above, and the first electrode layer has an integrated 50% particle size of 0.8 to 1.2 μm and an integrated 10% particle size of 0.5 μm or more. The second electrode layer is formed of a sintered body of 100 parts by mass of Cu powder and 0.1 to 10 parts by mass of glass powder. is there.

  The glass-ceramic wiring board with a built-in capacitor according to the present invention has a built-in capacitor in which a pair of electrode layers are opposed to each other with a dielectric layer made of barium titanate sandwiched inside an insulating substrate made of glass ceramics. The layer includes a first electrode layer made of a sintered body of Cu powder arranged on the dielectric layer side, and a second electrode layer made of a sintered body of Cu powder and glass powder arranged on the glass ceramic side. Therefore, the first electrode layer can suppress the mutual diffusion of the components of the dielectric layer made of barium titanate, and the second electrode layer has a bonding property with the glass ceramic. As a strong material, it is possible to suppress delamination between layers and generation of cracks.

  In the glass-ceramic wiring board with a built-in capacitor according to the present invention, preferably, the first electrode layer has a spherical Cu powder having an integrated 50% particle size of 0.8 to 1.2 μm and an integrated 10% particle size of 0.5 μm or more. Since the second electrode layer is made of a sintered body of 100 parts by mass of Cu powder and 0.1 to 10 parts by mass of glass powder, shrinkage of the first electrode layer is promoted. Thus, the mutual diffusion of the components of the dielectric layer made of barium titanate can be suppressed, and the second electrode layer can absorb the shrinkage difference between the first electrode layer, the dielectric layer, and the glass ceramic. Thus, delamination between layers and generation of cracks can be suppressed. As a result, it is possible to greatly suppress the capacitance value variation and capacitance value variation of the capacitor formed in the glass ceramic wiring substrate, and to provide a highly reliable glass ceramic wiring substrate with a built-in capacitor.

  The glass-ceramic wiring board with a built-in capacitor according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a glass-ceramic wiring board with a built-in capacitor according to the present invention, wherein 1 is an insulating layer, 2 is a first electrode layer, 3 is a second electrode layer, and 4 is titanic acid. It is a dielectric layer made of barium.

The insulating layer 1 in the present invention is made of glass and ceramic powder. Examples of the glass 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 Ca , Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O system (where M ¹ and M ² are the same or different, and Ca, Sr, Mg, Ba) Or Zn), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ¹ O—M ² O system (where M ¹ and M ² are the same as above), SiO ₂ —B ₂ O ₃ -M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ -B ₂ O ₃ -Al ₂ O ₃ -M ³ ₂ O system (where M ³ is the same as above) ), Pb-based glass, Bi-based glass, and the like.

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.

  A glass ceramic green sheet, which is a green sheet before firing of the insulating layer 1, is formed into a slurry by mixing glass powder and ceramic powder with an organic binder, an organic solvent, a plasticizer, and the like. It is formed into a sheet by adopting a blade method or a calender roll method.

  As the organic binder added to and mixed with the glass powder and the ceramic powder, those conventionally used for ceramic green sheets can be used. For example, acrylic (acrylic acid, methacrylic acid or ester homopolymers thereof) Or a copolymer, specifically an acrylic ester copolymer, a methacrylic ester copolymer, an acrylic ester-methacrylic ester copolymer, etc.), polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene Examples include carbonate-based and cellulose-based homopolymers or copolymers.

  The organic solvent used in the slurry for forming the glass ceramic green sheet is, for example, a hydrocarbon so that a slurry having a viscosity suitable for forming the glass ceramic green sheet can be obtained by dispersing glass powder, ceramic powder and organic binder. Organic solvents such as alcohols, ethers, esters, ketones and alcohols.

  A through-hole conductor in which a through hole is formed in the glass ceramic green sheet produced as described above by die processing or the like if necessary, and an appropriate organic binder and solvent are added to a metal powder such as Cu in the through hole. The paste is filled by screen printing or the like to form a through conductor (not shown).

  Next, on the surface of these glass ceramic green sheets, a first organic layer paste prepared by adding and mixing an appropriate organic binder and solvent to Cu powder, and an appropriate organic binder and solvent to Cu powder and glass powder. The second electrode layer paste formed by addition and mixing is stacked and applied by screen printing or the like, and is fired simultaneously with the glass ceramic green sheet, thereby forming the first electrode layer 2 and the second electrode layer 3. An electrode layer pattern is formed.

  In the present invention, the Cu powder used for the first electrode layer paste is a spherical Cu powder having an integrated 50% particle size of 0.8 to 1.2 μm and an integrated 10% particle size of 0.5 μm or more. preferable. When the cumulative 50% particle size of the Cu powder is less than 0.8 μm, the dispersibility of the Cu powder tends to deteriorate during paste formation, and the screen printability tends to deteriorate. On the other hand, when the cumulative 50% particle size of the Cu powder exceeds 1.2 μm, the components of the dielectric layer 3 are likely to interdiffuse during the sintering of the electrode layer 2 and the sinterability of the dielectric layer 3 tends to deteriorate. There is. Further, when the cumulative 10% particle size of the Cu powder is less than 0.5 μm, the fine powder tends to aggregate, and the dispersibility of the Cu powder tends to be deteriorated when making a paste, and the screen printing property tends to be deteriorated.

  Note that the cumulative 10% particle size is, for example, the particle size is measured by a laser particle size distribution measuring device, the number of powders is integrated from the smaller measured particle size, and the integrated number is 10% of the total. The cumulative 50% particle size is the same when the number of powders is accumulated from the smaller measured particle size and the accumulated number reaches 50% of the total. The particle size.

  The second dielectric layer paste is preferably prepared by mixing 0.1 to 10 parts by mass of glass powder with respect to 100 parts by mass of Cu powder. When the glass powder is less than 0.1 part by mass, the bonding force with the glass ceramic tends to be weak, and there is a tendency that peeling or cracking occurs. On the other hand, if the glass powder exceeds 10 parts by mass, the electrical resistance value of the electrode layer tends to increase, and the electrical characteristics as a wiring board tend to deteriorate.

  Next, barium titanate powder and sintered are formed on the surface of the glass ceramic green sheet on which the electrode layer pattern to be the first electrode layer 2 and the second electrode layer 3 is formed by simultaneous firing with the glass ceramic green sheet. A dielectric layer paste formed by adding an organic binder and a solvent to an auxiliary agent is applied by screen printing or the like, and simultaneously fired with a glass ceramic green sheet, thereby forming a dielectric layer pattern to be a dielectric layer 4. .

The barium titanate powder used for this dielectric layer paste preferably has an average particle size of 0.3 μm or less. When the average particle size of the barium titanate powder exceeds 0.3 μm, the sinterability of the dielectric layer 3 tends to deteriorate. Examples of the sintering aid 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 (however, , M represents Ca, Sr, Mg, Ba, or _{Zn), SiO 2 -B 2 O} 3 -M 1 2 O system (where, ^{M 1} is shows a Li, Na or _K), SiO 2 _-B 2 O ^{_{3 -Al 2 O 3 -M 1 2}} O system (where, ^{M 1} is the same as above), Pb-based glass can be used Bi-based glass.

  Moreover, it is preferable that the addition amount to the dielectric material layer paste of this sintering auxiliary agent is 2-10 mass parts with respect to 100 mass parts of barium titanate powders. When the addition amount of the sintering aid is less than 2 parts by mass, barium titanate tends to be difficult to sinter. On the other hand, when the addition amount of the sintering aid exceeds 10 parts by mass, the dielectric constant of the dielectric layer 4 tends to decrease.

  Next, the glass ceramic green sheet on which the dielectric layer pattern to be the dielectric layer 4 is formed by co-firing with the glass ceramic green sheet is first fired with the previously formed glass ceramic green sheet. The other electrode layer pattern to be the first electrode layer 2 and the second electrode layer 3 is applied and formed so as to be opposed to the electrode layer pattern to be the electrode layer 2 and the second electrode layer 3. . The electrode layer pattern to be the other first electrode layer 2 and second electrode layer 3 can also be applied and formed by screen printing or the like using the previously used electrode layer paste.

  Next, a plurality of these glass ceramic green sheets are stacked and thermocompression bonded at a pressure of 3 to 20 MPa and a temperature of 30 to 80 ° C. to produce a laminate. There is no particular limitation on the position, number and size of the dielectric layer 4 in the laminate, and it may be configured to be a glass-ceramic wiring board with a built-in capacitor having a desired number and size of built-in capacitors. .

  Thereafter, the organic component is removed in a humidified nitrogen atmosphere, and then the laminate is fired at a temperature of 800 to 1000 ° C., whereby the glass-ceramic wiring board with a built-in capacitor of the present invention is obtained.

  In addition, when firing the laminate, a constrained green sheet made of an inorganic component that does not substantially sinter and shrink at the temperature at which the glass ceramic green sheet or dielectric layer 4 is sintered, such as alumina, is laminated on both sides of the laminate. This constrained green sheet restrains and suppresses shrinkage during firing in the main surface direction of the laminate, which improves the dimensional accuracy of the glass ceramic wiring board with a built-in capacitor, and the glass ceramic wiring board with a built-in capacitor. It is possible to reduce the variation in the capacitance value of the capacitor built in the capacitor. Further, when fired by such a method, the firing shrinkage in the thickness direction becomes larger than when fired by a normal method, so that the thickness of the dielectric layer 4 can be made thinner and incorporated. It is easy to increase the capacity of the capacitor.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the dielectric layer 4 is formed by applying a dielectric layer paste to a glass ceramic green sheet. However, the dielectric green sheet previously formed into a sheet shape is punched or the like. The dielectric layer 4 may be formed by processing it into a predetermined shape and transferring it by thermocompression bonding to a glass ceramic green sheet.

  Examples of the glass-ceramic wiring board with a built-in capacitor according to the present invention will be described below.

As a glass ceramic component, 50 parts by mass of SiO ₂ —CaO—MgO glass powder and 50 parts by mass of Al ₂ O ₃ powder are mixed, and 100 parts by mass of this inorganic powder is 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 glass ceramic green sheet having a thickness of 200 μm was formed by a doctor blade method.

  A first electrode layer paste was applied to this glass ceramic green sheet to a thickness of 10 μm by screen printing, and dried at 70 ° C. for 30 minutes to form a pattern of electrode layer paste to be the first electrode layer 2. . The shape of this pattern was a 3 mm square pattern. As the first electrode layer paste, 12 parts by mass of acrylic resin and 2 parts by mass of α-terpineol as an organic solvent are added to 100 parts by mass of Cu powder having the particle size and shape shown in Table 1 below, followed by stirring and removal. After thoroughly mixing with a foaming machine, one kneaded sufficiently with three rolls was used.

  In Table 1, sample NO. No. 1 has an integrated 50% particle size (indicated by D50 in the table) of 0.95 μm and an integrated 10% particle size (indicated by D10 in the table) of 0.62 μm. No. 2 has an integrated 50% particle size of 1.10 μm and an integrated 10% particle size of 0.75 μm. In No. 3, the cumulative 50% particle size is 2.80 μm and the cumulative 10% particle size is 1.74 μm. In the case of flaky Cu powder, sample NO. In No. 4, the cumulative 50% particle size is 3.30 μm and the cumulative 10% particle size is 1.38 μm.

  Next, the second electrode layer paste is stacked and applied to a thickness of 10 μm by a screen printing method on a glass ceramic green sheet on which a pattern of the electrode paste to be the first electrode layer 2 is formed. The electrode layer paste pattern to be the second electrode layer 3 was formed by drying for 30 minutes. The shape of this pattern was also a 3 mm square pattern. As the second electrode layer paste, 100 parts by mass of Cu powder and 5 parts by mass of glass powder are added with 12 parts by mass of acrylic resin and 2 parts by mass of α-terpineol as an organic solvent. And then kneaded sufficiently with three rolls. For comparison, 100 parts by mass of Cu powder is added with 12 parts by mass of acrylic resin and 2 parts by mass of α-terpineol as an organic solvent. What was done was used.

Next, a dielectric layer paste is applied to the thickness of 20 μm by screen printing on the electrode layer pattern to be the second electrode layer 3 by co-firing with the glass ceramic green sheet, and 30 ° C. at 30 ° C. The dielectric layer pattern which becomes the dielectric layer 4 was formed by partial drying. The dielectric layer pattern was a 3 mm square pattern. As a dielectric layer paste, a mixture of glass powder containing 5 parts by mass of B ₂ O ₃ , SiO ₂ , CaO, BaO, ZnO with respect to 100 parts by mass of barium titanate powder, 12 parts by mass of acrylic resin and organic 2 parts by mass of α-terpineol as a solvent was added, and the mixture was sufficiently mixed with a stirring defoamer and then kneaded sufficiently with three rolls.

  Next, an electrode layer similar to the above is disposed on the pattern of the dielectric layer paste so as to face the electrode layer pattern to be the first electrode layer 2 and the second electrode layer 3 previously formed. Capacitors in which the pastes are stacked and applied to a thickness of 10 μm, and a pair of first electrode layer 2 and second electrode layer 3 are disposed opposite to each other with a dielectric layer 4 made of barium titanate in between. Was formed.

  Next, a glass ceramic green sheet in which a portion to be a capacitor is formed and a glass ceramic green sheet in which a portion to be a capacitor is not formed are stacked and heat-pressed at a pressure of 5 MPa and a temperature of 50 ° C. to form a glass ceramic green. A laminate of sheets was produced.

  In addition, the electrode layer paste that becomes the pair of the first electrode layer 2 and the second electrode layer 3 that are arranged to face each other is formed by filling a through hole formed by punching a glass ceramic green sheet with a Cu paste. Each of the through conductors was electrically drawn out to the surface of the multilayer body.

  Next, the laminated body is baked at 500 ° C. for 3 hours in a humidified nitrogen atmosphere to remove organic components, and then baked at 900 ° C. for 1 hour in a nitrogen atmosphere, thereby insulating the dense glass ceramic sintered body. A glass-ceramic wiring board with a built-in capacitor in which the first electrode layer 2, the second electrode layer 3, and the dielectric layer 4 formed by co-firing inside the layer 1 were prepared.

  And about the obtained glass ceramic wiring board with a built-in capacitor, the electric capacity of the capacitor was measured. The capacitance was measured using an impedance measuring instrument (model “4294A Precision Impedance Analyzer”, manufactured by Agilent Technologies, measurement accuracy ± 0.08%) under the conditions of a measurement frequency of 1 MHz and a measurement temperature of 25 ° C.

  Next, the areas of the first electrode layer 2 and the second electrode layer 3 which are electrode layers of the capacitor and the thickness of the dielectric layer 4 were measured. The area of the electrode layer was measured by an optical microscope mirror (magnification 10 times) by polishing the surface from the upper surface of the glass ceramic wiring board with a built-in capacitor, exposing the electrode layer. The thickness of the dielectric layer 4 was measured by a metal microscope (100 times magnification) after mirror-finishing the cross section of the glass ceramic wiring board with a built-in capacitor.

Then, the relative dielectric constant was calculated based on the capacity obtained by the measurement, the area of the electrode layer, and the thickness of the dielectric layer 4. In the case of a parallel plate capacitor, the dielectric constant of the material of the dielectric layer 4 is C = ε ₀ · ε _r · S / d (where C is the capacitance of the capacitor, ε _{0 is} the dielectric constant in air, ε _r : Relative dielectric constant of the material of the dielectric layer 3, S: area of the electrode layer, d: distance between the electrode layers). These measurement results are shown in Table 1.

  From Table 1, Samples 1 and 2 using spherical Cu powder having an integrated 50% particle size of 0.8 to 1.2 μm and an integrated 10% particle size of 0.5 μm or more are used for the first electrode layer 2. It was found that the dielectric layer 4 was densely sintered and the dielectric layer 4 having a high relative dielectric constant was formed. In contrast, Sample 3 using spherical Cu powder with an integrated 50% particle size of 2.80 μm and an integrated 10% particle size of 1.74 μm, and an integrated 50% integrated particle size of 3.30 μm with flakes Sample 4 using Cu powder with a 10% particle size of 1.38 μm is not densified due to diffusion of the sintering aid of dielectric layer 4, and is a dielectric layer 4 having a low relative dielectric constant. I understood it.

  In addition, as a second electrode layer paste, a comparative sample to which no glass powder was added was confirmed to have a polished finish for measuring the thickness of the dielectric layer 4. It was found that partial peeling occurred at the interface between the layer 3 and the insulating layer 1.

It is sectional drawing which shows an example of embodiment about the glass-ceramic wiring board with a built-in capacitor | condenser of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulating layer 2 ... 1st electrode layer 3 ... 2nd electrode layer 4 ... Dielectric layer

Claims (2)

A capacitor in which a pair of electrode layers are arranged opposite to each other with a dielectric layer made of barium titanate sandwiched inside an insulating substrate made of glass ceramics is disposed on the dielectric layer side. A two-layer structure of a first electrode layer made of a sintered body of Cu powder and a second electrode layer made of a sintered body of Cu powder and glass powder disposed on the glass ceramic side. A glass-ceramic wiring board with a built-in capacitor. The first electrode layer is made of a sintered body of spherical Cu powder having an integrated 50% particle size of 0.8 to 1.2 μm and an integrated 10% particle size of 0.5 μm or more, and the second electrode layer The glass-ceramic wiring board with a built-in capacitor according to claim 1, comprising a sintered body of 100 parts by mass of Cu powder and 0.1 to 10 parts by mass of glass powder.

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