WO2016148217A1 - Wiring substrate - Google Patents

Abstract

The present invention relates to a wiring substrate. This wiring substrate (12) comprises an insulating substrate (18), surface wiring layers (20, 22) that are provided on the surface of the insulating substrate (18), and an internal wiring layer (24) that is provided within the insulating substrate (18). The crystal phase of the insulating substrate (18) comprises at least Al₂O₃ or a compound containing Al₂O₃ as the main crystal phase, and the crystal grain size of Al₂O₃ is less than 1.5 μm. The surface wiring layers and the internal wiring layer contain copper and tungsten, copper and molybdenum, or copper, tungsten and molybdenum; and the grain sizes of tungsten and molybdenum are less than 1.0 μm. The surface wiring layers and the internal wiring layer have surface roughnesses Ra of less than 2.5 μm.

Description

Wiring board

The present invention relates to a wiring board, for example, a wiring board suitable for use in a ceramic package, a high-frequency circuit board, or the like in which elements such as vibrators are mounted.

As a conventional wiring board, for example, a wiring board having an insulating substrate made of ceramic such as alumina, the wiring board described in, for example, Japanese Patent No. 3827447, Japanese Patent No. 3493310, Japanese Patent No. 3537698, and Japanese Patent No. 3898400 It has been known.

Japanese Patent No. 3827447 discloses an insulating substrate formed by laminating a plurality of insulating layers made of aluminum oxide ceramics having an average crystal grain size of a main crystal phase of 1.5 to 5.0 μm, and disposed inside the insulating substrate. There is described a wiring board having an internal wiring layer and a surface wiring layer disposed on the surface of the insulating substrate. In this wiring board, the copper diffusion distance to the ceramic around the internal wiring layer is 20 μm or less, and the surface roughness (Ra) of the substrate surface on which the surface wiring layer of the insulating substrate is formed is 1 μm or less. It consists of the skin surface.

Japanese Patent No. 3493310 discloses a wiring board comprising a ceramic insulating substrate, and a surface wiring layer and an internal wiring layer formed on the inside and the surface of the insulating substrate by simultaneous firing with the insulating substrate. . In this wiring substrate, the surface wiring layer contains 10 to 70% by volume of copper and 30 to 90% by volume of tungsten and / or molybdenum, and a metal layer is coated on the surface of the surface wiring layer by a plating method. It is formed by wearing. The internal wiring layer contains 20 to 80% by volume of copper and 20 to 80% by volume of tungsten and / or molybdenum. The sheet resistance of the surface wiring layer on which the internal wiring layer and the metal layer are deposited is 6 mΩ / sq. It is as follows.

Japanese Patent No. 3537698 discloses an insulating substrate made of a ceramic having a relative density of 95% or more, containing aluminum as a main component and containing a manganese compound in a ratio of 2.0 to 10.0% by weight in terms of MnO ₂ , A wiring substrate having a surface wiring layer on at least the surface of an insulating substrate is described. The surface wiring layer is formed by co-firing with an insulating substrate and contains 10 to 70% by volume of copper and 30 to 90% by volume of tungsten and / or molybdenum, and in a matrix made of copper. Tungsten and / or molybdenum is dispersed and contained as particles having an average particle diameter of 1 to 10 μm.

In Japanese Patent No. 3898400, at least the surface of an insulating substrate made of ceramics mainly composed of alumina is 10 to 70% by volume of Cu (copper) melted during firing, tungsten (W) particles and / or molybdenum (Mo ) A wiring board on which a metallized wiring layer containing particles in a proportion of 30 to 90% by volume is deposited is described. In this wiring board, Cu and tungsten particles and / or molybdenum particles in the metallized wiring layer are not separated, and the surface of the metallized wiring layer has a surface roughness (Ra) of 2.5 to 4.5 μm. It has become.

In the above-mentioned Japanese Patent No. 3827447, Japanese Patent No. 3493310, Japanese Patent No. 3537698, and Japanese Patent No. 3898400, there is a description that it is desirable to improve the adhesion of the wiring layer to the insulating substrate. However, there is a limit to increasing the adhesion because the grain size of the main crystal phase is large.

The present invention has been made in consideration of such problems, and provides a wiring board that can be produced at a low firing temperature and that can improve the adhesion of the wiring layer to the insulating board. Objective.

[1] A wiring board according to the present invention is a wiring board having an insulating substrate, a surface wiring layer disposed on a surface of the insulating substrate, and an internal wiring layer disposed inside the insulating substrate. The insulating substrate has a crystal phase of at least Al ₂ O ₃ or a compound containing Al ₂ O ₃ as a main crystal phase, the crystal grain size of the Al ₂ O ₃ is less than 1.5 μm, and the surface wiring The layer and the internal wiring layer include copper and tungsten, copper and molybdenum, or copper, tungsten, and molybdenum, and the grain size of the tungsten and molybdenum is less than 1.0 μm, and the surface wiring layer and the surface of the internal wiring layer The roughness Ra is less than 2.5 μm. The surface roughness Ra is more preferably 2.0 μm or less.

[2] In the present invention, it is preferable that at least the surface wiring layer has an adhesive strength of 2 kg or more with the insulating substrate.

[3] In the present invention, the insulating substrate is preferably a sintered body. In this case, the sintering is preferably performed at a temperature of 1200 to 1350 ° C. The temperature is preferably 1200 to 1300 ° C.

[4] In the present invention, the insulating substrate may include only a BaAl ₂ Si ₂ O ₈ crystal phase in addition to the main crystal phase.

[5] In this case, the insulating substrate is composed of 89.0 to 92.0 mass% of Al in terms of Al ₂ O ₃ , 2.0 to 5.0 mass% of Si in terms of SiO ₂ , and Mn in terms of MnO. It is preferable to contain 2.0 to 5.0 mass%, Mg is 0 to 2.0 mass% in terms of MgO, and Ba is 0.05 to 2.0 mass% in terms of BaO.

[6] In the present invention, the insulating substrate may have Al ₂ O ₃ and ZrO ₂ as a main crystal phase, and Mn ₃ Al ₂ (SiO ₄ ) ₃ or MgAl ₂ O ₄ in addition to the main crystal phase. .

[7] In this case, 70.0 to 90.0 wt% of Al in terms of Al ₂ O _3, 10.0 to 30.0 wt% of Zr in terms of ZrO _2, the total of Al ₂ O ₃ and ZrO ₂ When 100 mass%, Mn is 2.0 to 7.0 mass% in terms of MnO, Si is 2.0 to 7.0 mass% in terms of SiO ₂ , and Ba is 0.5 to 2.0 in terms of BaO. It is preferable to contain 0 to 2.0% by mass of Mg and Mg in terms of MgO.

[8] In the present invention, the insulating substrate may have a crystal phase of 3Al ₂ O ₃ .2SiO ₂ as a main crystal phase and Al ₂ O ₃ and ZrO ₂ in addition.

[9] In this case, Al is 40.0 to 70.0% by mass in terms of Al ₂ O ₃ , Zr is 5.0 to 40.0% by mass in terms of ZrO ₂ , and Si is 10.0 to in terms of SiO ₂ It is preferable that 30.0% by mass and Mn is contained in an amount of 2.0 to 8.0% by mass in terms of MnO.

[10] Moreover, Ba is contained when the total of Al ₂ O ₃ , ZrO ₂ , SiO ₂ and MnO is 100 mass%, including at least one element of Ba, Ti, Y, Ca and Mg. If includes 1.5 mass% or less in terms of BaO, if it contains Ti, wherein 1.5 wt% or less in terms of TiO _2, if it contains Y, more than 1.5 wt% in terms _of Y ₂ O ₃ If it contains Ca, it may contain 1.5 mass% or less in terms of CaO, and if it contains Mg, it may contain 1.5 mass% or less in terms of MgO.

The wiring board according to the present invention can be manufactured at a low firing temperature, and the adhesion of the wiring layer to the insulating substrate can be improved.

FIG. 1 is a cross-sectional view showing a ceramic package having a wiring board according to the present embodiment. FIG. 2 is a process block diagram showing a method for manufacturing a ceramic package.

Hereinafter, an embodiment in which a wiring board according to the present invention is applied to a ceramic package will be described with reference to FIGS. In the present specification, “˜” indicating a numerical range is used as a meaning including numerical values described before and after the numerical value as a lower limit value and an upper limit value.

The ceramic package 10 is configured by laminating a wiring board 12 according to the present embodiment, a frame body 14, and a lid body 16 in this order.

The wiring substrate 12 includes an insulating substrate 18, an upper surface wiring layer 20 formed on the upper surface of the insulating substrate 18, a lower surface wiring layer 22 formed on the lower surface of the insulating substrate 18, and an internal formed inside the insulating substrate 18. A wiring layer 24, a first via hole 26 a that electrically connects the internal wiring layer 24 and the lower surface wiring layer 22, and a second via hole 26 b that electrically connects the internal wiring layer 24 and the upper surface wiring layer 20. Have.

In this ceramic package 10, a crystal resonator 30 is electrically connected to the upper surface wiring layer 20 via a conductor layer 32 in a housing space 28 surrounded by the upper surface of the insulating substrate 18 and the frame body 14. Further, in order to protect the crystal unit 30, the lid body 16 is hermetically sealed on the upper surface of the frame body 14 via the glass layer 34.

In the ceramic package 10 described above, an example in which the crystal resonator 30 is mounted in the accommodation space 28 has been shown. However, at least one of a resistor, a filter, a capacitor, and a semiconductor element may be mounted. .

The insulating substrate 18, the frame body 14, and the lid body 16 constituting the ceramic package 10 are made of the same ceramic substrate.

The ceramic substrate constituting the insulating substrate 18 and the like includes Al ₂ O ₃ as a main crystal phase and includes only a BaAl ₂ Si ₂ O ₈ crystal phase.

Specifically, Al is 89.0 to 92.0 mass% in terms of Al ₂ O ₃ , Si is 2.0 to 5.0 mass% in terms of SiO ₂ , and Mn is 2.0 to 5 mass in terms of MnO. It is preferable to contain 0% by mass, 0 to 2.0% by mass of Mg in terms of MgO, and 0.05 to 2.0% by mass of Ba in terms of BaO.

The insulating substrate 18 or the like is composed of 89.0 to 92.0% by mass of Al ₂ O ₃ powder, 2.0 to 5.0% by mass of SiO ₂ powder, and 3.2 to 8.1% by mass of MnCO ₃ powder ( 2.0 to 5.0 mass% in terms of MnO), 0 to 2.0 mass% in MgO powder, 0.06 to 2.6 mass% in BaCO ₃ powder (0.05 to 2.0 mass in terms of BaO) %)), And then the molded body is fired at 1200 to 1350 ° C. (preferably 1200 to 1300 ° C.).

In this case, for Al ₂ O ₃ , the average particle size of the raw material (Al ₂ O ₃ powder) is 0.3 to 2.5 μm, and the crystal grain size of Al ₂ O ₃ when formed into a sintered body is It is preferably 0.3 to 1.5 μm. The crystal grain size of Al ₂ O ₃ is more preferably 0.5 to 1.0 μm.

In addition, the average particle size of the raw material is the integrated amount of passage from the small particle size side (integrated passage fraction) in the volume-based particle size distribution obtained by measuring by the laser diffraction scattering type particle size distribution measurement method (LA-920, manufactured by HORIBA). ) 50% particle size.

The crystal grain size when the sintered body was obtained was determined as follows. That is, when the surface of the sintered body was imaged with a scanning electron microscope, the magnification of the scanning electron microscope was adjusted so that about 500 to 1000 crystal particles were captured in the entire captured image. Then, 100 or more arbitrary crystal particles in the captured image were calculated based on the average particle diameter converted to a perfect circle using image processing software.

MgO powder is added as a sintering aid for Al ₂ O ₃ , SiO ₂ powder is used as a sintering aid for Al ₂ O ₃ , and Mn ₂ SiO ₄ glass phase is generated to lower the sintering temperature. It is added to achieve BaCO ₃ powder is added to suppress the formation of MnAl ₂ O ₄ with increased hardness.

Conventionally, any one or more of TiO ₂ powder, Ce ₂ O ₃ powder, and Fe ₃ O ₄ powder is included. However, since the dielectric loss tangent is increased, it is preferable not to include it as much as possible. Even if it is included, it is 0.1% by mass or less. The dielectric loss tangent is preferably 30 × 10 ⁻⁴ or less at 1 MHz to 10 GHz. More preferably, it is 15 × 10 ⁻⁴ or less, more preferably 10 × 10 ⁻⁴ or less. Thereby, the wiring board 12 can be applied to a high-frequency circuit board, which is preferable.

In addition, you may make it include 1.0 mass% or less of Mo oxide and W oxide as a coloring agent as needed.

Thereby, the insulating substrate 18 can be realized which can be sintered at a low temperature of 1200 to 1350 ° C. (preferably 1200 to 1300 ° C.) and has a bending strength of 600 MPa or more. “Bending strength” refers to a four-point bending strength, which is a value measured at room temperature based on JIS R1601 (bending test method for fine ceramics).

Note that by a 89.0 to 92.0 wt% and the content of Al in terms of Al ₂ O _3, the amount of Al ₂ O ₃ which is generated becomes optimum, the firing temperature is also increased, Al ₂ An increase in the crystal grain size of O ₃ can be suppressed, so that the bending strength can be easily improved.

By setting the Mg content to 0 to 2.0 mass% in terms of MgO, it is possible to suppress the sintering temperature from increasing, to suppress the grain growth of alumina, and to suppress the strength reduction.

By setting the Si content to 2.0 to 5.0 mass% in terms of SiO ₂ , it is possible to suppress a decrease in the amount of the glass phase to be generated, 1200 to 1350 ° C. (preferably 1200 to 1300 ° C.) It is easy to achieve densification in the glass, and it is possible to suppress a decrease in the softening temperature and an increase in the porosity of the produced glass. Furthermore, a decrease in bending strength can be suppressed.

By setting the Mn content to 3.2 to 8.1% by mass in terms of MnCO ₃ , it is possible to suppress a decrease in the amount of the glass phase to be generated, 1200 to 1350 ° C. (preferably 1200 to 1300 ° C.) It is easy to achieve densification in the glass, and it is possible to suppress a decrease in the softening temperature and an increase in the porosity of the produced glass. Furthermore, a decrease in bending strength can be suppressed.

By setting the Ba content to 0.05 to 2.0% by mass in terms of BaO, it becomes easy to suppress the formation of MnAl ₂ O ₄ and suppress the strength reduction. In addition, it is possible to suppress the sintering temperature from increasing, to suppress the grain growth of alumina, and to suppress the strength reduction.

Therefore, by containing Al, Si, Mn, Mg and Ba in the above-described ratios, the strength of the glass phase to be generated can be increased. As a result, the bending strength is increased, and the wiring according to the present embodiment Miniaturization of the ceramic package 10 using the substrate 12 can be promoted. In addition, it can be produced at a low firing temperature, which is advantageous for cost reduction. Furthermore, the generated BaAl ₂ Si ₂ O ₈ crystal phase suppresses extremely high hardness, can reduce the chipping occurrence rate in chip division by the pressure roller, and can improve productivity. it can.

Since the wiring board 12 is composed of the insulating substrate 18 described above, the bending strength is 600 MPa or more. If the bending strength is lower than 600 MPa, thermal stress may be applied during the secondary mounting to cause destruction. Alternatively, there is a risk of destruction due to an impact or the like during handling or use. If the bending strength is 600 MPa or more, such a risk of destruction can be avoided.

Further, even when the ceramic substrate constituting the insulating substrate 18 or the like is used as the insulating substrate 18 and the lid body 16 of the ceramic package 10 without polishing the surface, the lid body 16 is prevented from being broken when hermetically sealed. The manufacturing cost and reliability of the ceramic package 10 can be improved.

Then, since the ceramic substrate constituting the insulating substrate 18 and the like has the above-described composition, it can be sintered at a low temperature of 1200 to 1350 ° C. (preferably 1200 to 1300 ° C.). Therefore, a ceramic substrate precursor (molded body before firing), various wiring layers (upper surface wiring layer 20, lower surface wiring layer 22, internal wiring layer 24) and via holes (first via hole 26a, second via hole 26b). By simultaneous firing, the wiring board 12 can be manufactured, and the manufacturing process can be simplified.

Furthermore, in this wiring board 12, various wiring layers contain copper and tungsten, copper and molybdenum, copper and tungsten and molybdenum, and the particle size of tungsten and the particle size of molybdenum (after firing) are less than 1.0 μm. More preferably, it is 0.7 μm or less.

The particle size of tungsten and / or molybdenum when the sintered body of tungsten contained in the various wiring layers after firing was determined as follows. That is, the magnification of the scanning electron microscope was adjusted so that when the surface of various wiring layers was imaged with a scanning electron microscope, about 500 to 1000 tungsten particles and / or molybdenum particles were captured in the entire captured image. . Then, 100 or more arbitrary tungsten particles and / or molybdenum particles in the captured image were calculated by an average particle diameter converted into a perfect circle using image processing software.

In the wiring board 12, the surface roughness Ra of the upper surface wiring layer 20 and the lower surface wiring layer 22 is less than 2.5 μm. Preferably they are 1.7 micrometers or more and less than 2.5 micrometers, More preferably, they are 1.7 micrometers or more and 2.0 micrometers or less. The surface roughness was measured on the surfaces of the upper surface wiring layer 20 and the lower surface wiring layer 22 with a laser microscope (manufactured by Keyence Corporation: VK-9700) at a magnification of 500 times.

The upper surface wiring layer 20 and the lower surface wiring layer 22 had an adhesive strength with the insulating substrate 18 of 2 kg or more. Within this range, the upper surface wiring layer 20 and the lower surface wiring layer 22 are peeled off (including partial peeling and all peeling) during the manufacturing process of the wiring board 12, transportation, and the process of using as the ceramic package 10. This contributes to improvement in yield and reliability.

Here, the adhesive strength is a concept representing the adhesion between the insulating substrate 18 and the conductor (the upper surface wiring layer 20 and the lower surface wiring layer 22). Specifically, a lead wire obtained by bending a 0.6 mm diameter tin-coated annealed copper wire into an L-shape is soldered to a conductor pattern having a square shape and a side length of 2 mm, and a tensile speed of 20 mm / sec. The tensile strength when pulled vertically. This conductor pattern may be plated with Ni to ensure solder wettability.

Next, a method for manufacturing the ceramic package 10 having the wiring board 12 according to the present embodiment will be described with reference to FIG.

First, in step S1a of FIG. 2, the Al ₂ O ₃ powder is 89.0 to 92.0% by mass, the SiO ₂ powder is 2.0 to 5.0% by mass, and the MnCO ₃ powder is 3.2 to 8.1%. A mixed powder containing 1% by mass, 0 to 2.0% by mass of MgO powder and 0.06 to 2.6% by mass of BaCO ₃ powder is prepared. In step S1b, an organic component (binder) is prepared, and step S1c Prepare a solvent.

As described above, the average particle size of the Al ₂ O ₃ powder is preferably 0.3 to 2.5 μm. The average particle size of the SiO ₂ powder is preferably 0.1 to 2.5 μm. The average particle size of the MnCO ₃ powder is preferably 0.5 to 4.0 μm. The average particle size of the MgO powder is preferably 0.1 to 1.0 μm. The average particle size of the BaCO ₃ powder is preferably 0.5 to 4.0 μm.

Examples of the organic component (binder) prepared in step S1b include a resin, a surfactant, and a plasticizer. Examples of the resin include polyvinyl butyral, examples of the surfactant include tertiary amines, and examples of the plasticizer include phthalic acid esters (for example, diisononyl phthalate: DINP).

Examples of the solvent prepared in step S1c include alcohol solvents and aromatic solvents. Examples of the alcohol solvent include IPA (isopropyl alcohol), and examples of the aromatic solvent include toluene.

Then, in the next step S2, after mixing and dispersing the organic component and the solvent in the above-mentioned mixed powder, in step S3, by a known molding method such as a press method, a doctor blade method, a rolling method, an injection method, A ceramic molded body (also referred to as a ceramic tape) that is a precursor of the ceramic substrate is produced. For example, an organic component or a solvent is added to the mixed powder to prepare a slurry, and then a ceramic tape having a predetermined thickness is formed by a doctor blade method. Alternatively, an organic component is added to the mixed powder, and a ceramic tape having a predetermined thickness is produced by press molding, rolling molding, or the like.

In step S4, the ceramic tape is cut and processed into a desired shape, a first tape having a large area for the first substrate, a second tape having a large area for the second substrate, and a third tape for the frame. Then, a fourth tape for the lid is produced, and further, through holes for forming the first via hole 26a and the second via hole 26b are formed by micro drilling, laser processing, or the like.

Next, in step S5, a conductive paste for forming the upper surface wiring layer 20, the lower surface wiring layer 22, and the internal wiring layer 24 is screen-printed and gravured on the first tape and the second tape manufactured as described above. Printing is applied by a method such as printing, and a conductive paste is filled in the through holes as desired.

Conductor paste uses a mixture of Cu and W, or a mixture of Cu and Mo, or a mixture of Cu, W and Mo as a conductor component, and this is equivalent to Al ₂ O ₃ powder, SiO ₂ powder, or ceramic substrate The powder is preferably added in an amount of, for example, 1 to 20% by mass, particularly 8% by mass or less. Thereby, the adhesiveness of the alumina sintered body and the conductor layer can be enhanced while maintaining the conduction resistance of the conductor layer low, and the occurrence of defects such as lack of plating can be prevented.

Thereafter, in step S6, the first tape and the second tape on which the conductive paste is printed and applied, and the third tape for the frame are aligned and laminated and pressure-bonded to produce a laminated body.

Thereafter, in step S7, dividing grooves for dividing the chip are formed on both surfaces of the laminate by, for example, knife cutting.

In the next step S8, the laminate and the fourth tape are formed into a hydrogen and nitrogen forming gas atmosphere containing 5% or more of hydrogen, for example, a H ₂ / N ₂ = 30% / 70% forming gas atmosphere (wetter temperature 25 to 25%). 47 ° C.) at a temperature range of 1200 to 1350 ° C. (preferably 1200 to 1300 ° C.). As a result, a laminated original plate (multiple substrate) in which the laminate and the conductor paste are simultaneously fired is produced. By this firing, as described above, it is possible to produce a ceramic substrate having a crystal phase of Al ₂ O ₃ as a main crystal phase and including only a BaAl ₂ Si ₂ O ₈ crystal phase, that is, a multi-chip substrate. it can.

The oxidation of the metal in the conductor paste can be prevented by performing the firing atmosphere in the forming gas atmosphere as described above. The firing temperature is preferably in the temperature range described above. When the firing temperature is lower than 1200 ° C., the densification is insufficient and the bending strength does not reach 600 MPa. When the firing temperature is higher than 1350 ° C., the first tape, the second tape, and the third tape constituting the laminated body Variations in shrinkage rate increase and dimensional accuracy decreases. This leads to a decrease in yield and increases the cost. Of course, the higher the firing temperature, the more expensive the equipment.

Next, in step S9, the above-mentioned multi-chip substrate is plated, and the upper wiring layer 20 and the lower wiring layer 22 formed on the surface of the multi-chip substrate are coated with Ni, Co, Cr, Au. A plating layer made of at least one of Pd and Cu is formed.

Thereafter, in step S10, the multi-piece substrate is pressed with a pressing roller or the like and divided into a plurality of pieces (chip division), and a plurality of wiring boards 12 having the accommodation spaces 28 are produced. In step S <b> 11, the crystal resonator 30 is mounted on the upper surface wiring layer 20 via the conductor layer 32 in each accommodation space 28 of the plurality of wiring boards 12.

In step S12, the quartz resonator 30 is mounted on the upper surface of each wiring substrate 12 by hermetically sealing the ceramic substrate 16 with the sealing glass layer 34 formed thereon. A plurality of ceramic packages 10 are completed.

In the method for manufacturing the ceramic package 10, as described above, the crystal phase is a ceramic having Al ₂ O ₃ as the main crystal phase and only including the BaAl ₂ Si ₂ O ₈ crystal phase and a bending strength of 600 MPa or more. A substrate can be made. That is, a ceramic substrate capable of reducing the size and thickness of the ceramic package 10 and the like and improving the bending strength can be produced at a low firing temperature, and the cost of the ceramic substrate and the product using the ceramic substrate can be reduced. Can be reduced.

The ceramic substrate constituting the insulating substrate 18 of the ceramic package 10 described above is configured such that the crystal phase includes Al ₂ O ₃ as the main crystal phase and the BaAl ₂ Si ₂ O ₈ crystal phase alone. The ceramic bodies according to the first to third modifications to be described may be employed.

(First modification)
In the ceramic substrate according to the first modification, the crystal phase includes Al ₂ O ₃ and ZrO ₂ as the main crystal phase, and the crystal phase includes Mn ₃ Al ₂ (SiO ₄ ) ₃ or MgAl ₂ O ₄ .

Specifically, 70.0 to 90.0 wt% of Al in terms of Al ₂ O _3, 10.0 to 30.0 wt% of Zr in terms of ZrO _2, the total of Al ₂ O ₃ and ZrO ₂ 100 If the mass% from 2.0 to 7.0 mass% of Mn in terms of MnO 2.0 to 7.0 mass% of Si in terms of SiO _2, 0.5-2.0 mass Ba in terms of BaO %, Mg is preferably contained in an amount of 0 to 2.0% by mass in terms of MgO.

The ceramic substrate according to the first modification is, for example, 70.0 to 90.0% by mass of Al ₂ O ₃ powder, 10.0 to 30.0% by mass of ZrO ₂ powder, and 2.0 to 7. After forming a molded body containing 0% by mass, SiO ₂ powder 2.0-7.0% by mass, BaO powder 0.5-2.0% by mass, MgO powder 0-2.0% by mass, The compact is produced by firing at 1200 to 1350 ° C. The bending strength of this ceramic substrate is 650 MPa or more.

(Second modification)
In the ceramic substrate according to the second modification, the crystal phase includes 3Al ₂ O ₃ .2SiO ₂ as a main crystal phase, and includes Al ₂ O ₃ and ZrO ₂ in addition.

As the porcelain composition, Al is 40.0 to 70.0% by mass in terms of Al ₂ O ₃ , Zr is 5.0 to 40.0% by mass in terms of ZrO ₂ , and Si is 10.0 to 30 in terms of SiO _2. It is preferable that 0.0% by mass and Mn be contained in an amount of 2.0 to 8.0% by mass in terms of MnO.

As an additive, at least one element of Ba, Ti, Y, Ca, and Mg may be included. When the total of Al ₂ O ₃ , ZrO ₂ , SiO ₂ and MnO is 100% by mass, when Ba is included, 1.5% by mass or less in terms of BaO is included, and when Ti is included, 1 in terms of TiO ₂ It includes .5 wt% or less, if it contains Y is Y include ₂ O ₃ in terms of 1.5 wt% or less, if it contains Ca, comprises 1.5 wt% or less in terms of CaO, when containing Mg is It is preferable to contain 1.5 mass% or less in terms of MgO.

The ceramic substrate according to the second modification is, for example, 3Al ₂ O ₃ .2SiO ₂ (mullite) powder of 50.0 to 93.0 mass%, ZrO ₂ powder of 5.0 to 40.0 mass%, Al ₂ O ₃ After forming a compact containing 0 to 36.0% by mass of powder, 0 to 16.0% by mass of SiO ₂ powder, and 2.0 to 8.0% by mass of MnO powder, It is produced by firing at 0 ° C. The bending strength of this ceramic substrate is 450 MPa or more.

The wiring board using the ceramic substrate according to the first modification and the second modification described above can also be sintered at a low temperature, and the adhesion of the wiring layer to the insulating board can be improved. It can be.

In the above-described example, the example in which the wiring board is applied to the ceramic package is shown, but it can also be applied to a high-frequency circuit board or the like.

For Examples 1 to 9 and Comparative Example 1, a wiring board similar to the wiring board 12 shown in FIG. 1 was prepared, and the sheet resistance of the surface wiring layer and the internal wiring layer, the W contained in the surface wiring layer and the internal wiring layer, and The grain size of Mo, the surface roughness Ra of the surface wiring layer, and the crystal grain size, crystal phase, bending strength (bending strength) of the insulating substrate 18 and adhesion strength of the surface wiring layer were confirmed. In the produced wiring board, the upper surface wiring layer, the lower surface wiring layer and the internal wiring layer shown in FIG. 1 were formed, and the formation of the first via hole and the second via hole was omitted.

[Insulated substrate]
As shown in Table 1 below, six types of insulating substrates (Nos. 1 to 6) were used as the insulating substrate 18. The breakdown will be described below.

(Insulating substrate No. 1)
Al ₂ O ₃ powder was used as the main component of the raw material powder. The average particle diameter of the Al ₂ O ₃ powder is 1.1 μm. The composition of the insulating substrate after firing was Al ₂ O ₃ : 92.5% by mass, SiO ₂ : 4.0% by mass, MnO: 2.9% by mass, MgO: 0.3% by mass, BaO: 0. .2% by mass.

(Insulating substrate No. 2)
Insulating substrate No. 1 except that the average particle size of the Al ₂ O ₃ powder is 0.5 μm. Same as 1.

(Insulating substrate No. 3)
The composition of the insulating substrate after firing was Al ₂ O ₃ : 89.6 mass%, SiO ₂ : 5.6 mass%, MnO: 4.1 mass%, MgO: 0.4 mass%, BaO: 0.3 Except for the mass%, the insulation substrate No. Same as 2.

(Insulating substrate No. 4)
Al ₂ O ₃ powder and ZrO ₂ powder were used as the main component of the raw material powder. Among them, the average particle diameter of the Al ₂ O ₃ powder is 1.1 μm. The composition of the insulating substrate after firing was Al ₂ O ₃ : 68.8% by mass, ZrO ₂ : 18.7% by mass, SiO ₂ : 4.8% by mass, MnO: 5.3% by mass, MgO: 1.0% by mass and BaO: 1.3% by mass.

(Insulating substrate No. 5)
3Al ₂ O ₃ .2SiO ₂ powder and ZrO ₂ powder were used as the main component of the raw material powder. The composition of the insulating substrate after firing was as follows: Al ₂ O ₃ : 50.5% by mass, ZrO ₂ : 24.1% by mass, SiO ₂ : 19.9% by mass, MnO: 4.4% by mass, BaO: 1.1% by mass.

(Insulating substrate No. 6)
Al ₂ O ₃ powder was used as the main component of the raw material powder. The average particle diameter of the Al ₂ O ₃ powder is 1.8 μm. The composition of the insulating substrate after firing is Al ₂ O ₃ : 94.0% by mass, SiO ₂ : 3.0% by mass, and MgO: 3.0% by mass.

<Example 1>
Insulation substrate No. Polyvinyl butyral, tertiary amine and phthalic acid ester (diisononyl phthalate: DINP) as organic components are mixed into 1 raw material powder, and IPA (isopropyl alcohol) and toluene are mixed and diffused as a solvent to prepare a slurry. Thereafter, a ceramic tape having a thickness of 60 to 270 μm was produced by a doctor blade method. Then, the ceramic tape was cut and processed into a desired shape to produce first to fourth tapes.

A conductive paste for forming a surface wiring layer (upper surface wiring layer, lower surface wiring layer) and an internal wiring layer was printed and applied to the first tape and the second tape. The conductor paste used a mixture of Cu and W as a conductor component. The composition of the conductor part after baking is Cu: 12 vol%, W: 88 vol%.

Then, the 1st tape and 2nd tape which carried out the printing application | coating of the conductor paste were aligned, the lamination | stacking pressure bonding was carried out, and the laminated body was produced. The laminated body, the third tape, and the fourth tape are fired in a forming gas atmosphere having a firing temperature (maximum temperature) of 1350 ° C. and H ₂ + N ₂ , and the wiring substrate, the first ceramic substrate, and the first ceramic substrate according to the first embodiment. Two ceramic substrates were produced. The surface wiring layer and the internal wiring layer were formed by simultaneous firing. The first ceramic substrate is used for confirming the crystal grain size and the crystal phase, and the second ceramic substrate is used for confirming the bending strength. The production of the first ceramic substrate and the second ceramic substrate is the same in the following Examples 2 to 9 and Comparative Example 1. The upper surface wiring layer has a square planar shape and a side length of 2 mm for measuring the adhesive strength.

<Example 2>
The same as Example 1 except that the composition of the conductor part after firing for forming the surface wiring layer (upper surface wiring layer, lower surface wiring layer) and the internal wiring layer was Cu: 18 vol%, W: 82 vol% Thus, a wiring board according to Example 2 was produced.

<Example 3>
Insulation substrate No. 2 using the raw material powder, the composition of the conductor part after firing was Cu: 23 vol%, W: 77 vol%, and the firing temperature (maximum temperature) was 1270 ° C. A wiring board according to Example 3 was produced.

<Example 4>
A wiring board according to Example 4 was produced in the same manner as in Example 3 except that the composition of the conductor part after firing was Cu: 35 vol% and W: 65 vol%.

<Example 5>
Insulation substrate No. 3, the composition of the conductor part after firing was Cu: 45 vol%, W: 55 vol%, and the firing temperature (maximum temperature) was 1200 ° C. A wiring board according to Example 5 was produced.

<Example 6>
A wiring board according to Example 6 was produced in the same manner as in Example 5 except that the composition of the conductor part after firing was Cu: 53 vol% and W: 47 vol%.

<Example 7>
Example 7 is the same as Example 5 except that a mixture of Cu and Mo was used as the conductor component of the conductor paste, and the composition of the conductor part after firing was Cu: 53 vol% and Mo: 47 vol%. The wiring board which concerns on was produced.

<Example 8>
Insulation substrate No. The raw material powder of No. 4 was used, the composition of the conductor part after firing was Cu: 15 vol%, W: 85 vol%, and the firing temperature (maximum temperature) was 1310 ° C. A wiring board according to Example 8 was produced.

<Example 9>
Insulation substrate No. 5 using the raw material powder, the composition of the conductor part after firing was Cu: 25 vol%, W: 75 vol%, and the firing temperature (maximum temperature) was 1290 ° C. A wiring board according to Example 9 was produced.

<Comparative Example 1>
Insulation substrate No. The raw material powder of No. 6 was used, the composition of the conductor part after firing was Cu: 5 vol%, W: 95 vol%, and the firing temperature (maximum temperature) was 1500 ° C. A wiring board according to Comparative Example 1 was produced.

[Evaluation methods]
The sheet resistance of the surface wiring layer and the internal wiring layer, the grain size of W and Mo, and the surface roughness Ra of the surface wiring layer were confirmed as follows.

(Sheet resistance)
Each sheet resistance of the upper surface wiring layer, the lower surface wiring layer, and the internal wiring layer was measured by a four-terminal method, and the average value was defined as the sheet resistance.

(Particle size of W and Mo)
When the surface of the upper surface wiring layer, the lower surface wiring layer, and the internal wiring layer is imaged with a scanning electron microscope, about 500 to 1000 W particles and Mo particles are captured in the entire captured image. The magnification was adjusted. Then, in the captured image, arbitrary 100 or more W particles and Mo particles were calculated by average of particle diameters converted into perfect circles using image processing software.

(Surface roughness Ra)
Each surface of the upper surface wiring layer and the lower surface wiring layer was measured with a laser microscope (manufactured by Keyence Corporation: VK-9700) at a magnification of 500 times, and the average value was defined as the surface roughness Ra.

(Adhesive strength)
A lead wire obtained by bending a tin-coated annealed copper wire having a diameter of 0.6 mm into an L-shape was soldered to an upper surface wiring layer having a square shape and a side length of 2 mm, and was pulled vertically at a pulling speed of 20 mm / sec. The tensile strength was measured. The evaluation criteria are divided into three stages A, B, and C with the adhesive strength of 2 kg as the boundary, and the highest adhesive strength range is A, and the evaluation strengths B, C are evaluated in order as the adhesive strength decreases. did. Also, the evaluation strength D was less than 2 kg of adhesive strength.

The crystal grain size, crystal phase and bending strength (bending strength) of the insulating substrate were confirmed as follows.

(Al ₂ O ₃ crystal grain size)
As described above, when the surface of each first ceramic substrate before powdering is imaged with a scanning electron microscope, about 500 to 1000 crystal particles are captured in the entire captured image. The magnification of was adjusted. Then, 100 or more arbitrary crystal particles in the captured image were calculated based on the average particle diameter converted to a perfect circle using image processing software.

(Crystal phase)
Each first ceramic substrate was identified by X-ray diffraction. As a criterion for determining whether or not a crystal phase is contained, the main peak intensity of 3% or more of the intensity of the main peak (104 plane) of alumina was assumed. That is, the contained crystal phase was confirmed based on the position of the main peak intensity (peak position) of 3% or more, the Miller index, the lattice constant, and the like with respect to the intensity of the main peak of alumina.

(Folding strength)
Each second ceramic substrate was measured at room temperature based on a four-point bending strength test of JIS R1601.

[Evaluation results]
The evaluation results of Examples 1 to 9 and Comparative Example 1 are shown in Table 2 below.

In all of Examples 1 to 9, the crystal grain size of Al ₂ O ₃ is less than 1.5 μm, the grain size of tungsten or molybdenum is less than 1.0 μm, and the surface roughness Ra of the surface wiring layer is 2. It was less than 5 μm. As a result, the sheet resistance of the surface wiring layer and the internal wiring layer was 6.0 mΩ / sq. The adhesive strength was 2 kg or more.

Among them, in Examples 5 to 7, the crystal grain size of Al ₂ O ₃ is less than 1.0 μm and the surface roughness Ra of the surface wiring layer is less than 2.0 μm. The sheet resistance of the wiring layer is 3.0 mΩ / sq. The adhesive strength was also evaluated as A.

The insulating substrate of Examples 1-7, other Al ₂ O ₃ crystal phase, comprising a BaAl ₂ Si ₂ O ₈ crystal phase, the insulating substrate of Example 8, another Al ₂ O ₃ crystalline phase, ZrO ₂ includes a crystal phase and MgAl ₂ O ₄ crystalline phase, the insulating substrate of example 9, another Al ₂ O ₃ crystal phase, because they contain a ZrO ₂ crystalline phase and 3Al ₂ O ₃ · 2SiO ₂ crystal phase, anti A bending strength of 600 MPa or more is obtained.

On the other hand, in Comparative Example 1, the evaluation of the adhesive strength was D. This is presumably because the crystal grain size of the insulating substrate is as large as 4.0 μm, and the surface roughness Ra of the surface wiring layer is as large as 3.0 μm, so that the adhesion of the surface wiring layer to the insulating substrate is reduced. In Comparative Example 1, the sheet resistance of the surface wiring layer and the internal wiring layer was 8.0 mΩ / sq. It was high. Furthermore, since the insulating substrate of Comparative Example 1 had only the Al ₂ O ₃ crystal phase as the crystal phase, the bending strength was as low as 550 MPa.

Of course, the wiring board according to the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

Claims (10)

1. An insulating substrate (18);
   Surface wiring layers (20, 22) disposed on the surface of the insulating substrate (18);
   A wiring board having an internal wiring layer (24) disposed inside the insulating substrate (18),
   The insulating substrate (18) has a crystal phase of at least Al ₂ O ₃ or a compound containing Al ₂ O ₃ as a main crystal phase, and the crystal grain size of the Al ₂ O ₃ is less than 1.5 μm,
   The surface wiring layer (20, 22) and the internal wiring layer (24) include copper and tungsten, copper and molybdenum, copper, tungsten and molybdenum,
   The tungsten and molybdenum have a particle size of less than 1.0 μm,
   A wiring board, wherein the surface wiring layer (20, 22) and the internal wiring layer (24) have a surface roughness Ra of less than 2.5 μm.
2. The wiring board according to claim 1,
   At least the surface wiring layers (20, 22) have a bonding strength with the insulating substrate (18) of 2 kg or more.
3. In the wiring board according to claim 1 or 2,
   The wiring substrate, wherein the insulating substrate (18) is a sintered body.
4. The wiring board according to any one of claims 1 to 3,
   The insulating substrate (18) is characterized in that the crystal phase includes only the BaAl ₂ Si ₂ O ₈ crystal phase in addition to the main crystal phase.
5. The wiring board according to claim 4,
   In the insulating substrate (18), Al is 89.0 to 92.0 mass% in terms of Al ₂ O ₃ , Si is 2.0 to 5.0 mass% in terms of SiO ₂ , and Mn is 2.0 in terms of MnO. A wiring board comprising: -5.0 mass%, Mg: 0-2.0 mass% in terms of MgO, and Ba: 0.05-2.0 mass% in terms of BaO.
6. The wiring board according to any one of claims 1 to 3,
   The insulating substrate (18) has a crystal phase of Al ₂ O ₃ and ZrO ₂ as main crystal phases, and additionally contains Mn ₃ Al ₂ (SiO ₄ ) ₃ or MgAl ₂ O _4. .
7. The wiring board according to claim 6,
   70.0 to 90.0 wt% of Al in terms of Al ₂ O _3, 10.0 to 30.0 wt% of Zr in terms of ZrO _2, when the sum of the Al ₂ O ₃ and ZrO ₂ is 100 mass% , Mn is 2.0 to 7.0 mass% in terms of MnO, Si is 2.0 to 7.0 mass% in terms of SiO ₂ , Ba is 0.5 to 2.0 mass% in terms of BaO, and Mg is MgO. A wiring board comprising 0 to 2.0% by mass in terms of conversion.
8. The wiring board according to any one of claims 1 to 3,
   The wiring board, wherein the insulating substrate (18) has a crystal phase of 3Al ₂ O ₃ .2SiO ₂ as a main crystal phase and Al ₂ O ₃ and ZrO ₂ in addition.
9. The wiring board according to claim 8,
   Al is 40.0-70.0% by mass in terms of Al ₂ O ₃ , Zr is 5.0-40.0% by mass in terms of ZrO ₂ , Si is 10.0-30.0% by mass in terms of SiO ₂ , A wiring board comprising Mn in an amount of 2.0 to 8.0% by mass in terms of MnO.
10. The wiring board according to claim 9, wherein
    Including at least one element of Ba, Ti, Y, Ca and Mg,
    When the total of Al ₂ O ₃ , ZrO ₂ , SiO ₂ and MnO is 100% by mass,
    When Ba is contained, it contains 1.5% by mass or less in terms of BaO,
    When Ti is contained, it contains 1.5% by mass or less in terms of TiO ₂ ,
    When Y is included, it is 1.5% by mass or less in terms of Y ₂ O ₃ ,
    When it contains Ca, it contains 1.5 mass% or less in terms of CaO,
    When Mg is contained, it contains 1.5 mass% or less in terms of MgO.

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