JP2010034273A - Multilayer circuit board, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer circuit board which has high thermal conductivity while maintaining insulation and can be baked at low temperature, and a method of manufacturing the same. <P>SOLUTION: The multilayer circuit board includes an insulating base 1 having a plurality of glass ceramic insulating layers 11, 12, 13, 14 laminated, a through conductor 2 formed in the glass ceramic insulating layers 11, 12, 13, 14, and wiring layers 3 formed on principal surfaces of the glass ceramic insulating layers 11, 12, 13, 14, wherein heat dissipating bodies each having an oxide-based ceramic coating of 0.5 to 3 μm in thickness on metal powder are dispersed and contained in the glass ceramic insulating layers 11, 12, 13, 14, and contents of the metal powder in the glass ceramic insulating layers 11, 12, 13, 14 including the heat dissipating bodies are 15 to 45% by mass. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer wiring board suitable for a semiconductor element storage package, a hybrid integrated circuit device, and the like, and a method for manufacturing the same, and in particular, can efficiently dissipate heat generated during the operation of active elements such as semiconductor elements. The present invention relates to a multilayer wiring board and a method for manufacturing the same.

  In recent years, by using glass ceramics, which is a composite material of glass and ceramics, as an insulating layer, a low resistance metal having a low melting point, such as Cu, Ag, Au, etc., which can be fired at a low temperature of 1000 ° C. or lower is used as a wiring layer. A multilayer wiring board that can be used as a forming material has been developed.

For example, a multilayer wiring board in which an insulating layer obtained by adding a SiO ₂ filler to glass and a wiring layer made of a low-resistance metal such as Cu, Ag, Au, etc., at the temperature of 900 to 1050 ° C. has been proposed ( (See Patent Document 1).

  However, with the development of information communication technology, the performance of semiconductor elements such as ICs and LSIs is increasing. Due to the high performance of the semiconductor element, the amount of heat generated from the semiconductor element is increased, and the problem of thermal resistance of the multilayer wiring board to be mounted is increased. Specifically, the glass ceramics in the multilayer wiring board described in Patent Document 1 has a thermal conductivity of about 0.5 to 1.5 W / m · K, and is more thermally conductive than an alumina material that cannot be fired at a low temperature. It is inferior to (heat dissipation).

Therefore, a multilayer wiring board has been proposed in which glass ceramics obtained by mixing and firing AlN having high thermal conductivity and glass is used as an insulating substrate (see Patent Document 2 and Patent Document 3).
Japanese Examined Patent Publication No. 4-12639 JP-A 63-307182 JP-A-4-254477

  However, when non-oxide ceramics such as AlN are mixed with glass and fired, the non-oxide ceramics and glass react during firing to decompose the non-oxide ceramics and generate decomposition gas. The decomposition gas causes expansion of the insulating substrate (porcelain) and swelling (bubbles) on the surface of the insulating substrate (porcelain), making it difficult to obtain a stable external porcelain. Since this phenomenon becomes prominent in firing in an oxidizing atmosphere, it is necessary to reduce the oxygen concentration in the firing atmosphere in order to solve this problem. was there. When the debinding defect occurs, the insulating substrate (porcelain) expands and the insulating substrate (porcelain) surface expands (bubbles), which leads to a decrease in porcelain strength and dielectric loss tangent.

  As another method, a method of dispersing a metal powder having high thermal conductivity (Cu, Ag, Au, etc.) in the glass ceramic insulating layer is conceivable. In this method, the metal powders are in contact with each other and connected. In addition, there is a risk of short-circuiting between the upper and lower wiring layers and between the wiring layers or between the wiring layers and the through conductors. The amount of the metal powder contained in the metal must be about 10% by mass or less, and is not very effective as a method for improving thermal conductivity (heat dissipation).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multilayer wiring board capable of low-temperature firing having high thermal conductivity while maintaining insulation, and a method for manufacturing the same.

  The present invention relates to a multilayer wiring board including an insulating substrate in which a plurality of glass ceramic insulating layers are laminated, a through conductor formed in the glass ceramic insulating layer, and a wiring layer formed on a main surface of the glass ceramic insulating layer. In the glass ceramic insulating layer, a heat radiator in which an oxide ceramic film having a thickness of 0.5 to 3 μm is formed in a metal powder is dispersed and contained. Content of the said metal powder in a glass-ceramic insulating layer is 15-45 mass%, It is characterized by the above-mentioned.

Here, it is desirable that the metal powder is a powder made of at least one selected from the group consisting of Cu, Ag and Au. Moreover, it is desirable that the oxide-based ceramic coating is a coating made of at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ and ZrO ₂ .

  The present invention also includes a step of producing a radiator in which an oxide ceramic coating having a thickness of 0.5 to 3 μm is formed on a metal powder, and a mixture comprising glass powder, an inorganic filler, and the radiator. A step of producing a glass ceramic green sheet so that the content of the metal powder is 15 to 45% by mass, and a through-hole penetrating the glass ceramic green sheet is formed and filled with a paste for through conductor And a step of depositing and forming a wiring layer conductor paste on the surface of the glass ceramic green sheet, and filling the through conductor paste and depositing the wiring layer conductor paste. A multilayer wiring board comprising a step of producing a laminate by laminating a plurality and a step of firing the laminate It is a manufacturing method.

  According to the multilayer wiring board of the present invention, the heat insulating material in which the oxide ceramic coating is formed on the metal powder is dispersed and contained inside the glass ceramic insulating layer. A multilayer wiring board that achieves both (heat dissipation) can be realized.

  Moreover, the manufacturing method of the multilayer wiring board of this invention can disperse | distribute a metal powder to the inside of a glass ceramic insulating layer, without short-circuiting. Therefore, it is possible to improve the thermal conductivity (heat dissipation) while maintaining the insulation of the multilayer wiring board.

  An embodiment of the multilayer wiring board of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view of an embodiment of the multilayer wiring board of the present invention, and FIG. 2 is an enlarged view of a region A shown in FIG.

  In the present invention, as shown in FIG. 1, an insulating substrate 1 in which a plurality of glass ceramic insulating layers 11, 12, 13, and 14 are laminated, and through holes formed in the glass ceramic insulating layers 11, 12, 13, and 14, respectively. A multilayer wiring board including a conductor 2 and a wiring layer 3 formed on the main surfaces of the glass ceramic insulating layers 11, 12, 13, and 14, wherein the glass ceramic insulating layers 11, 12, 13, and 14 The radiator 4 is included in a dispersed manner.

  The insulating substrate 1 is formed by laminating a plurality of glass ceramic insulating layers 11, 12, 13, and 14. The glass ceramic insulating layers 11, 12, 13, and 14 are made of a glass powder made of crystalline glass that precipitates crystals upon firing or non-crystalline glass that does not precipitate crystals and an inorganic filler, and an organic binder and an organic solvent. Etc. were added and fired.

  The glass ceramic insulating layers 11, 12, 13, and 14 include, for example, crystals such as quartz, enstatite, forsterite, cristobalite, cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, and petalite. Yes. This crystal may be precipitated from glass powder as a raw material, or may be mixed as an inorganic filler as a raw material.

  Then, inside the glass ceramic insulating layers 11, 12, 13, and 14, as shown in FIG. 2, an oxide ceramic coating 42 having a thickness of 0.5 to 3 μm is formed on the metal powder 41 as the heat dissipating body. The heat radiator 4 is dispersed and contained, and the content of the metal powder 41 in the glass ceramic insulating layers 11, 12, 13 and 14 including the heat radiator 4 is 15 to 45 mass%. is important. Here, being contained in a dispersed state (in a dispersed state) means that the content of the metal powder 41 is 15 to 45% by mass in any part of the glass ceramic insulating layers 11, 12, 13, and 14. It means that the thermal conductivity is a value of 2 W / m · K or more.

  This radiator 4 is for improving the heat dissipation of the multilayer wiring board. When the thickness of the oxide-based ceramic coating 42 is 0.5 μm or more, it is possible to maintain insulation without short-circuiting even if the adjacent radiators 4 are in contact with each other, and by being 3 μm or less, The sinterability of the glass ceramics is not hindered and the heat dissipation can be improved. That is, if the thickness of the oxide-based ceramic coating 42 is less than 0.5 μm, it is not sufficient to ensure insulation, and if the thickness of the oxide-based ceramic coating 42 exceeds 3 μm, the sinterability of the glass ceramic is hindered, Heat dissipation is not sufficient due to the effects of voids.

  Moreover, heat dissipation can be improved when content of the metal powder 41 is 15 mass% or more, and insulation can be maintained when it is 45 mass% or less. That is, if the content of the metal powder 41 is less than 15% by mass, the amount of the metal powder 41 is too small and the heat dissipation effect is not sufficient, and if the content of the metal powder 41 exceeds 45% by mass, the insulating property May not be sufficient.

  The metal powder 41 has an average particle size of about 0.8 to 5 μm. Here, the metal powder 41 is desirably at least one selected from the group of metals having high thermal conductivity, especially Cu, Ag and Au.

The oxide-based ceramic coating 42 is a coating formed of ceramic fine powder. Here, the oxide-based ceramic coating 42 is preferably a coating made of at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ and ZrO ₂ .

  Thereby, the heat radiator 4 included in the glass ceramic green sheet is included in the glass ceramic insulating layers 11, 12, 13, and 14 after sintering in a state where the oxide ceramic coating 42 is formed on the metal powder 41. And can maintain that state. That is, since the coating is made of oxide ceramics, it does not react with the glass powder contained in the glass ceramic green sheet during sintering, and the metal powder 41 is covered with the oxide ceramic coating 42 to dissipate the radiator 4. Insulation between the through conductors 2 and the wiring layer 3 can be maintained.

  Here, the quantification of each element of the mixture can be obtained by ICP emission spectroscopy (Inductively Coupled Plasma Atomic Emission Spectroscopy), and the thickness of the oxide ceramic coating 42 is determined by the glass ceramic insulating layers 11 and 12. The average value of the thickness of any 10 locations of the oxide ceramic coating 42 in one radiator 4 is calculated from the 1000 times image obtained by scanning electron microscope (SEM) of the cross-sections obtained by cutting 13 and 14. Can be sought.

  A through conductor 2 is formed in each of the glass ceramic insulating layers 11, 12, 13, and 14 so as to penetrate from the one main surface (upper surface) to the other main surface (lower surface). The through conductor 2 is formed by firing a conductor paste containing a low-resistance metal powder such as Cu or Ag. A wiring layer 3 is formed on the main surfaces of the glass ceramic insulating layers 11, 12, 13, and 14. The wiring layer 3 is also formed by firing a conductor paste containing metal powder made of a low resistance metal such as Cu or Ag, like the through conductor 2.

  A multilayer wiring board according to an embodiment of the present invention has the above-described configuration as a basic configuration.

  Hereinafter, a method for manufacturing the multilayer wiring board will be described.

First, the radiator 4 is produced. The heat radiating body 4 is, for example, a metal powder 41 having a high thermal conductivity that is at least one selected from the group of Cu, Ag, and Au having an average particle diameter of 0.8 to 5 μm, and a thickness of 0.5 to 3 μm, for example. It is produced by forming an oxide ceramic coating 42 made of at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ and ZrO ₂ .

  Here, the oxide ceramic coating 42 is formed by adhering a large number of ceramic fine powders having an average particle diameter of 0.01 to 1 μm around the metal powder 41. Method (mechanochemical bonding method) is used. The thickness of the oxide-based ceramic coating 42 is measured by embedding the radiator 4 in a thermosetting resin and then polishing to expose the cross section of the radiator 4 and 1000 times using a scanning electron microscope (SEM). From the above image, the average value of the thickness of any 10 locations of the oxide ceramic coating 42 in one radiator 4 is calculated, and this is used as the thickness of the oxide ceramic coating 42.

  The “average particle diameter” means the particle diameter d50 at which the cumulative curve is 50% when the cumulative curve is obtained with the total volume of the powder group as 100%. The particle size distribution of the powder can be measured using, for example, a Microtrac particle size distribution measuring apparatus X-100 (manufactured by Nikkiso Co., Ltd.) using a laser diffraction / scattering method.

  Next, a glass ceramic green sheet is prepared so that the mixture of the glass powder, the inorganic filler, and the radiator 4 is included, and the content of the metal powder 41 in the mixture including the three types is 15 to 45 mass%. . Here, in order for the content of the metal powder 41 in the mixture to be 15 to 45% by mass, the heat radiating body 4 is considered to be spherical, and the particle size of the metal powder 41 and the thickness of the oxide ceramic coating 42. Each volume may be calculated from the above, and the mass of the metal powder 41 may be determined from the volume and specific gravity. In addition, the particle size of the metal powder 41 when viewed as a spherical shape is obtained by calculating an average value of the diameters of arbitrary 10 locations for the metal powder 41 in one heat radiating body 4. It was.

As the glass powder, either crystalline glass or amorphous glass can be employed. Specifically, borosilicate glass such as borosilicate glass, zinc borosilicate glass, lead borosilicate glass and the like containing alkaline earth metal oxides, lithium silicate glass, and the like can be given. As an average particle diameter of glass powder, 1-5 micrometers is desirable. The inorganic _{filler, Al 2 O 3, SiO 2} , ZrO 2, CaO, and oxides such as MgO or MgO, composite oxides of two or more of these oxides can be used. The average particle size of the inorganic filler is preferably 1 to 5 μm.

  By adjusting the blending ratio of the glass powder and the inorganic filler, it is possible to match the sintering temperature of the through conductor paste and the wiring layer conductor paste, or to increase the bonding strength. In the mixture, it is effective that the mixing ratio of the glass powder and the inorganic filler when excluding the radiator 4 is mixed in a mass ratio of 50:50 to 70:30.

  Ball mills, bead mills, etc. by adding organic binders such as isobutyl methacrylate resin and methyl methacrylate resin and organic solvents such as terpineol, dibutyl phthalate (DBP), toluene and acetone to a mixture consisting of glass powder, inorganic filler and radiator 4 The mixture is mixed for 12 to 24 hours to obtain a slurry, which is then formed into a sheet by a doctor blade method, a rolling method, a pressing method, or the like to produce a glass ceramic green sheet.

Next, through holes are formed in the produced glass ceramic green sheet with a micro drill, a CO ₂ laser, or the like, and a paste for through conductors is embedded in the through holes by a screen printing method. After the conductor paste for wiring layer is deposited on the surface by screen printing, it is dried at 60 to 100 ° C. for about 1 to 3 hours.

  Here, as the metal powder constituting the wiring layer conductor paste and the through conductor paste, low-resistance Cu powder or Ag powder is preferable, and Cu powder is the most effective for suppressing a decrease in reliability due to migration of metal components. desirable. An organic binder, an organic solvent, and the like are added to the metal powder at a ratio suitable for each paste to produce a wiring layer conductor paste and a through conductor paste. The average particle diameter of the metal powder is preferably 0.8 μm or more from the viewpoint of paste viscosity and the like, and 5 μm or less from the viewpoint of fine wiring formation.

Next, a plurality of glass ceramic green sheets filled with the obtained through-conductor paste and coated with the wiring layer conductor paste are stacked to produce a laminate.
Next, the obtained laminate is fired under predetermined conditions (for example, in a nitrogen atmosphere, at a firing temperature of 800 to 1000 ° C. for 1 hour) to sinter the glass ceramic green sheet, the through conductor, and the wiring layer, The multilayer wiring board of the present invention can be obtained.

  According to the above-described method for manufacturing a multilayer wiring board, a multilayer wiring board having excellent heat dissipation can be obtained.

First, a metal powder as a heat radiating body was formed with three kinds of metals shown in Table 1 to an average particle diameter of 3 μm, and Al ₂ O ₃ powder shown in Table 1 having an average particle diameter of 0.05 μm was formed on the metal powder. A heat radiating body was produced by forming oxide ceramic coatings having respective thicknesses shown in Table 1 by depositing them by a dry method (mechanochemical bonding method). In addition, the thickness of the oxide-based ceramic coating is obtained by embedding the radiator in a thermosetting resin and then polishing to expose the cross section of the radiator, and from a 1000 times image obtained by a scanning electron microscope (SEM), It calculated | required by calculating the average value of thickness of arbitrary 10 places about the oxide type ceramic film in one heat radiator.

Then, a glass powder having an average particle diameter of 3 μm and an inorganic filler (SiO ₂ filler) having an average particle diameter of 3 μm made of amorphous SiO ₂ —B ₂ O ₃ —BaO-based borosilicate glass are respectively in a mass ratio of 1: 1. The mixture was mixed at a ratio, and the above heat radiator was added to prepare a mixture containing three kinds. Here, a mixture containing three types is prepared so that the content of the metal powder when the entire mixture is 100% by mass is the content shown in Table 1, but for the content of the metal powder, The heat radiating body was assumed to be spherical, and each volume was calculated from the particle size of the metal powder and the thickness of the oxide ceramic coating, and the mass of the metal powder was determined from the volume and specific gravity. As for the particle size of the metal powder when viewed as a spherical shape, the average value of the diameters of any 10 locations of the metal powder in one heat radiator was calculated and used as the particle size of the metal powder. Furthermore, glass powder, SiO ₂ is 40 _wt%, B 2 _{O 3} is 10 mass%, BaO 40 wt%, _Al 2 _{O 3} is 5% by mass, CaO was used as the 5% by weight of the composition.

  Then, 15 parts by mass of an isobutyl methacrylate-based organic binder and 70 parts by mass of an organic solvent (toluene) were added to 100 parts by mass of the mixture containing these three types, and kneaded in a ball mill for 24 hours to prepare a glass ceramic slurry. Thereafter, it was formed into a sheet by a doctor blade method, dried at 80 ° C. for 10 minutes, and then a glass ceramic green sheet having a thickness of 120 μm was produced.

Next, a through hole having a diameter of 50 μm is formed in the produced glass ceramic green sheet by a CO ₂ laser, and a paste for a through conductor is embedded in the through hole by a screen printing method, and wiring is formed on the surface of the glass ceramic green sheet. The layer conductor paste was deposited by screen printing and then dried at 80 ° C. for 2 hours. The paste used at this time was obtained by adding an isobutyl methacrylate organic binder to 100 parts by mass of a mixed powder consisting of 98% by mass of Cu powder having an average particle size of 2 μm and 2% by mass of borosilicate glass powder having an average particle size of 2 μm. 5 parts by mass, 20 parts by mass of terpineol as an organic solvent are added and mixed by a three-roll mill.

  Further, six layers of glass ceramic green sheets filled with the through-conductor paste and coated with the wiring layer conductor paste were laminated to produce a laminate.

  Finally, the obtained laminate was fired with a nitrogen atmosphere, a firing temperature of 900 ° C., and a holding time of 1 hour to sinter the glass ceramic green sheet, the through conductor, and the wiring layer to obtain a multilayer wiring board.

On the other hand, a laminated body is produced by laminating six layers of glass ceramic green sheets that are not filled with the through-conductor paste and the conductive paste for the wiring layer is formed, and both main surfaces (upper surface and lower surface) of this laminated body. A conductive paste for wiring layer was applied to form a solid wiring pattern, and firing was performed under the same conditions as in the production of the multilayer wiring board. And the insulation resistance was measured about the obtained sample. Specifically, 10 V was applied to the wiring layers on the upper and lower surfaces of the sample using a digital multimeter to measure the insulation resistance, and 1 × 10 ⁶ Ω or less was regarded as defective. The results are shown in Table 1.

  In addition, 20 layers of glass ceramic green sheets that are not filled with through-conductor paste and coated with conductive paste for wiring layers are laminated to produce a laminate, and the laminate is formed into a shape with a diameter of 10 mm and a thickness of 2 mm. It processed and baked on the same conditions as manufacture of a multilayer wiring board, and obtained the sample. About the obtained sample, the heat conductivity was calculated | required with the laser flash method, and less than 2 W / m * K was made into the defect. The results are shown in Table 1.

  According to Table 1, it can be seen that the samples within the scope of the present invention (Sample Nos. 3-7, 10-13, 15, 16) have good values of insulation resistance and thermal conductivity.

  On the other hand, sample no. No. 1 does not include a heat radiating body, so it can be seen that the thermal conductivity is poor.

  In addition, sample No. No. 2 shows that the oxide ceramic coating is as thin as 0.1 μm, so that the insulating property is deteriorated.

  In addition, sample No. In No. 8, since the thickness of the oxide ceramic coating is as thick as 4.0 μm, it is understood that the sintering of the glass ceramic is hindered and the insulating properties are deteriorated.

  In addition, sample No. In No. 9, since the content of the metal powder is as small as 8% by mass, it can be seen that the thermal conductivity is deteriorated.

  In addition, sample No. No. 14 has a high metal powder content of 50% by mass, which indicates that the insulation is poor.

  Although not shown in the table, with respect to the thickness of the oxide ceramic coating in the heat dissipating body included in the fired glass ceramic insulating layer, a scanning electron microscope (SEM) of a section of the glass ceramic insulating layer cut. It was confirmed from the image of 1000 times that the thickness is equal to the thickness of the oxide-based ceramic coating in the heat radiator in the raw material stage before firing. Moreover, it was confirmed by ICP emission spectroscopic analysis that the content of the metal powder in the glass ceramic insulating layer including the heat radiating body after firing is equal to the content of the metal powder in the mixture before firing.

FIG. 1 is a schematic sectional view of an embodiment of a multilayer wiring board according to the present invention. It is an enlarged view of the area | region A shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulating base | substrate 11, 12, 13, 14 ... Glass-ceramic insulating layer 2 ... Through-conductor 3 ... Wiring layer 4 ... Radiator 41 ... Metal powder 42 ... Oxidation Physical ceramic coating

Claims (4)

A multilayer wiring board comprising an insulating substrate in which a plurality of glass ceramic insulating layers are laminated, a through conductor formed in the glass ceramic insulating layer, and a wiring layer formed on a main surface of the glass ceramic insulating layer, The glass ceramic insulating layer includes a heat radiator in which an oxide ceramic film having a thickness of 0.5 to 3 μm is formed on a metal powder, and the glass ceramic insulating layer includes the heat radiator. A multilayer wiring board, wherein the content of the metal powder is 15 to 45 mass%. The multilayer wiring board according to claim 1, wherein the metal powder is made of at least one selected from the group consisting of Cu, Ag and Au. _3. The multilayer wiring board according to claim 1, wherein the oxide-based ceramic coating is made of at least one selected from the group consisting of Al ₂ O ₃ , SiO _2, and ZrO ₂ . Producing a heat radiator in which an oxide ceramic film having a thickness of 0.5 to 3 μm is formed on a metal powder;
Including a mixture of glass powder, an inorganic filler and the radiator, and producing a glass ceramic green sheet so that the content of the metal powder in the mixture is 15 to 45% by mass;
Forming a through-hole penetrating the glass ceramic green sheet and filling with a paste for a through conductor, and forming a conductor paste for a wiring layer on the surface of the glass ceramic green sheet; and
A step of producing a laminate by laminating a plurality of the glass ceramic green sheets filled with the through conductor paste and deposited with the wiring layer conductor paste; and
And a step of firing the laminated body.

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