JP2010010394A - Ceramic wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic wiring board which has a superior mounting strength and has a low electric resistance for a conductor portion and which can be manufactured without suffering warping, peeling, or the like caused by simultaneous firing. <P>SOLUTION: The ceramic wiring board 10 includes a ceramic substrate 11, chief of which is ceramic that sinters at a temperature higher than the melting point of copper, and conductors 18, 19, 23, 27, and 28 which are formed in the ceramic substrate 11. The conductors 18, 19, 23, 27, and 28 each consist of a mixed phase of a filler and copper. The filler is formed mainly of chromium-based inorganic metal oxide having a melting point higher than that of copper. The content of the inorganic metal oxide in the filler is not less than 10 vol.% nor more than 60 vol.%. A preferred inorganic metal oxide in the filler is, for example, a chromium oxide or a copper-chromium composite oxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ceramic wiring board, and more particularly to a ceramic wiring board characterized by a conductor composition.

  In recent years, semiconductor integrated circuit elements (IC chips) used as computer microprocessor units (MPUs) have become increasingly faster and more functional, with an accompanying increase in the number of terminals and the pitch between terminals. Tend to be narrower. In general, a large number of terminals are densely arranged on the bottom surface of an IC chip, and such a terminal group is connected to a terminal group on the motherboard side in the form of a flip chip. However, it is difficult to connect the IC chip directly on the mother board because there is a large difference in the pitch between the terminals on the IC chip side terminal group and the mother board side terminal group. For this reason, a method is generally employed in which a package is prepared by mounting an IC chip on an IC chip mounting wiring board, and the package is mounted on a motherboard.

  Various insulating materials can be used for the IC chip mounting wiring board constituting this type of package, and examples of which use ceramics are well known. This type of package, called a ceramic package, is mainly made of a ceramic material mainly composed of alumina for the insulator part and tungsten, which is a refractory metal that can be fired simultaneously with alumina, for the conductor part. Yes. The ceramic package made of the above material has advantages such as high strength and sufficient mounting strength, and high sealing performance, but has a drawback that the wiring resistance of the conductor portion is higher than copper wiring and the like. Have.

  On the other hand, low-temperature fired materials such as glass ceramics have been developed in recent years, and as a result, it has become possible to reduce the resistance of the conductor part by using copper or silver having high conductivity as the material of the conductor part. It was. On the other hand, since glass ceramic has a composition containing a large amount of glass, it is weak in strength and is liable to be attacked by the plating solution, so that there is a problem that sufficient mounting strength cannot be obtained.

Furthermore, in view of these problems, a ceramic material mainly composed of alumina for the insulator portion and a mixture of tungsten and copper for the conductor portion has been proposed in the past (for example, Patent Documents). 1, 2, 3). And, according to such a combination of materials, it is expected that both improvement in mounting strength and reduction in resistance can be achieved.
Japanese Patent Application Laid-Open No. 07-015101 JP 05-144316 A Japanese Patent No. 3493310

  By the way, when manufacturing a ceramic package having a conductor made of copper-tungsten as in the above-described prior art, assuming that the firing temperature is set to a low temperature according to low melting point copper (1083 ° C.), simultaneous firing is performed. The sintering of alumina becomes insufficient and the desired strength cannot be achieved. Also, if the firing temperature is simultaneously fired according to the sintering temperature of the insulator, the low melting point copper melts and the flow and volatilization of the copper occurs as a result of the melting, so that the conductor (particularly the wiring pattern part) There is a problem that a suitable pattern shape cannot be maintained due to bleeding or pulling down. On the other hand, the electrical resistance of the conductor also increases, and the superiority of containing low resistance copper in the conductor is impaired.

Tungsten is oxidized and sublimated by reaction with oxygen as an impurity at 800 ° C. or higher in a nitrogen atmosphere, so that the inside of the firing furnace and the ceramic wiring substrate are easily contaminated. Therefore, in order to avoid such contamination, low (below 1 × 10 ^-21 atm, for example 800 ° C.) the oxygen partial pressure by allowed to mix a large amount of hydrogen during sintering must be kept, thus Manufacturing cost increases.

  Furthermore, when manufacturing a ceramic package having a conductor made of copper-tungsten as in the prior art, warping and peeling occur if the firing shrinkage ratios of the ceramic and metal do not match when fired simultaneously. There was also a problem that the yield decreased.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its purpose is to provide a ceramic wiring board that has excellent mounting strength and low electrical resistance of a conductor portion, and can be manufactured without causing warpage or peeling by simultaneous firing. Is to provide.

  In order to solve the above-mentioned problems, the inventors of the present invention have conducted intensive research and sought a means for preventing the flow and volatilization of the molten copper by simultaneous firing. As a specific means for maintaining the temperature, a new finding that a filler mainly composed of a specific inorganic metal oxide may be used. It has also been newly found out that the co-firing property can be improved by using a predetermined amount of a filler mainly composed of the specific inorganic metal oxide. The inventors of the present application have further developed these new findings and have come up with the following solution.

  That is, as means (means 1) for solving the above-mentioned problems, in the ceramic wiring board in which the conductor is formed on the ceramic base mainly composed of ceramic sintered at a temperature higher than the melting point of copper, the conductor is It consists of a mixed phase of copper and a filler mainly composed of a chromium-based inorganic metal oxide having a melting point higher than the melting point of copper, and the content of the inorganic metal oxide is not less than 10% by volume and not more than 60% by volume. There is a ceramic wiring board characterized by the following.

  Therefore, according to the means 1, since the conductor is formed including copper, the resistance is lower than that of a conductor formed using tungsten as a main component. In addition, since it is a conductor composed of a mixed phase of copper and a filler mainly composed of a chromium-based inorganic metal oxide having a higher melting point than copper, the filler itself has a high melting point even if copper is melted during simultaneous firing. Therefore, it maintains a solid state without melting and stays there, preventing the flow and volatilization of the molten copper. As a result, copper in the conductor is held in that position, and generation of voids in the conductor and protrusion of the conductor from the ceramic portion are prevented, so that a conductor having a relatively good shape can be obtained.

  Moreover, since an appropriate amount of filler mainly composed of a chromium-based inorganic metal oxide is used, the co-firing property is improved, and the firing shrinkage rate of the ceramic and the metal is matched, so there is no warping or peeling. Simultaneous firing can be performed.

  From the above, according to the above means 1, it is possible to provide a ceramic wiring board that has excellent mounting strength and low electrical resistance of the conductor portion, and can be manufactured without causing warpage or peeling due to simultaneous firing.

  The ceramic substrate constituting the ceramic wiring board is mainly composed of a ceramic sintered at a temperature higher than the melting point of copper (1083 ° C.).

  The ceramic as the insulator material is not particularly limited, and specific examples thereof include sintered bodies of high-temperature fired ceramics such as alumina, aluminum nitride, boron nitride, silicon carbide, and silicon nitride. A sintered body of low-temperature fired ceramic such as glass ceramic obtained by adding an inorganic ceramic filler such as alumina to borosilicate glass or lead borosilicate glass is not used here because it is weak in strength. Usually, the ceramic substrate is plate-shaped and has, for example, a rectangular shape in plan view.

  A conductor is formed on the ceramic substrate. Specific examples of such conductors include inner layer conductor patterns and via conductors formed inside the ceramic substrate, outer layer conductor patterns formed on the surface of the ceramic substrate, and mounting pads. These conductors are composed of a mixed phase of a filler mainly composed of a chromium-based inorganic metal oxide having a higher melting point than copper and copper.

The reason for choosing copper as one of the conductor forming materials is that copper is a metal with a low electrical resistivity (1.69 × 10 ⁻⁸ Ω · m) compared to silver or gold. Because it is cheap. However, since copper has a low melting point (1083 ° C.), a filler mainly composed of a chromium-based inorganic metal oxide having a high melting point is mixed with copper.

  Here, the conductor needs to be a mixed phase, not an alloy phase of copper and the inorganic metal oxide. The reason is that, in the alloy phase, copper and the inorganic metal oxide are naturally integrated, so that the flow and volatilization of the molten metal cannot be effectively prevented.

  The filler is preferably mainly composed of a chromium-based inorganic metal oxide having a melting point higher than that of copper. Specifically, the melting point is preferably 1400 ° C. or higher. The reason for this is that such a high melting point chromium-based inorganic metal oxide reliably maintains a solid state even after the temperature during co-firing and has a thickening effect on molten liquid copper. This is because the flow and volatilization of the copper can be reliably prevented. In addition, since the conductor should just have the said chromium-type inorganic metal oxide as a main body, if it is a small quantity, it may contain the other metal or inorganic compound.

Examples of the inorganic metal oxide in the filler include an inorganic compound composed of chromium and oxygen (chromium oxide: Cr ₂ O ₃ ) and an inorganic compound composed of a metal other than chromium and chromium and oxygen. it can. As the latter compound, for example, an inorganic compound composed of chromium, copper and oxygen, that is, a copper chromium composite oxide such as CuCrO ₂ , CuCr ₂ O ₄ , Cu ₂ Cr ₂ O ₄ , Cu ₂ Cr ₂ O _5, etc. Is preferred.

  Since chromium oxide and copper-chromium composite oxide are inherently oxides, they are hardly affected by the oxygen partial pressure during simultaneous firing. Therefore, it is not necessary to mix a large amount of hydrogen in order to keep the oxygen partial pressure low at the time of simultaneous firing, which is advantageous in that the burden of atmosphere control is reduced. Of these types of compounds, chromium oxide is particularly cheaper than tungsten, which is a general conductive material, and is advantageous in that it does not increase costs even when used as a filler. In addition, since both chromium oxide and copper-chromium composite oxide have the property of being familiar with and easy to get wet with copper, even if they are mixed with copper, they do not repel copper and can exist in a uniformly dispersed state. In particular, a copper-chromium composite oxide containing copper in its composition exhibits this property more strongly than chromium oxide. These are presumed to contribute to the reduction in resistance of the conductor.

  The average particle size of the filler is not particularly limited, but is preferably 10 μm or less. The reason is that if the filler is fine and uniform, it can be easily dispersed uniformly in the molten copper, and the flow and volatilization of the molten copper can be effectively prevented. For the same reason, it is preferable that the average particle diameter of copper is 10 μm or less. When the average particle size is more than 10 μm, the effect of suppressing copper from being raised in a ball shape especially for a large area pattern such as a mounting pad is diminished, and bleeding and thinning of the wiring are suppressed. The effect will also fade. The average particle size of the filler and copper is more preferably 2 μm or less, further preferably 1 μm or less, and particularly preferably 0.5 μm or less.

  The content of the inorganic metal oxide in the conductor is 10 volume% or more and 60 volume% or less. If this content is less than 10% by volume, the amount of filler may be reduced, so that the flow and volatilization of the molten copper may not be effectively prevented. Therefore, especially for a large area pattern such as a mounting pad, the effect of suppressing the copper from protruding into a ball shape is reduced, and the effect of suppressing the bleeding and thinning of the wiring is also reduced. Furthermore, the firing shrinkage rate with the ceramic substrate does not match, and warping and peeling are likely to occur.

  Conversely, if this content is more than 60% by volume, the copper content will be too low, and copper particles cannot be connected in the conductor, resulting in an increase in the specific resistance of the wiring. End up. Considering the above, the content of the inorganic metal oxide in the conductor is particularly preferably 20% by volume or more and 40% by volume or less.

  Hereinafter, a ceramic package 10 according to an embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

  As shown in FIG. 1, the ceramic package 10 (ceramic wiring substrate) of the present embodiment is a device for mounting a semiconductor integrated circuit element such as an IC chip 21 or an optical element such as a VICSEL. The ceramic substrate 11 constituting the ceramic package 10 is a member having a rectangular flat plate shape having an upper surface 12 (substrate surface) and a lower surface 13. The ceramic substrate 11 has a three-layer structure in which three ceramic sintered layers 14, 15 and 16 are laminated. In the present embodiment, the upper ceramic sintered layer 14, the intermediate ceramic sintered layer 15, and the lower ceramic sintered layer 16 are all made of an alumina sintered body. In the present embodiment, a three-layer structure is used, but a two-layer structure may be adopted, or a multilayer structure having four or more layers may be adopted.

  The ceramic substrate 11 includes a cavity 22 that opens on the upper surface 12. The cavity 22 of the present embodiment has a substantially rectangular shape in plan view, but a shape other than the substantially rectangular shape may be employed. The outer dimension of the cavity 22 is set to about 50% to 90% of the outer dimension of the ceramic base 11, and is set to about 65% of the outer dimension of the ceramic base 11 in this embodiment. The depth of the cavity 22 corresponds to the thickness of the upper ceramic sintered layer 14. At two spaced locations on the bottom surface of the cavity 22, an upper surface side mounting pad 23 made of a metallized layer obtained by simultaneous firing with ceramic is formed. The IC chip 21 is bonded onto these upper surface side mounting pads 23 using Ag epoxy resin or Ag-Si resin. The IC chip 21 may be bonded to the upper surface side mounting pad 23 by Au-Au bonding. A nickel layer or a gold layer (both not shown) may be formed on the upper surface side mounting pad 23 as necessary.

  A via conductor 18 is formed at a location corresponding to the upper surface side mounting pad 23 in the intermediate ceramic sintered layer 15. An inner layer conductor pattern 28 made of a metallized layer obtained by co-firing with ceramic is formed at the interface between the intermediate ceramic sintered layer 15 and the lower ceramic sintered layer 16. Each of the conductors 18 is electrically connected to the lower end.

  As shown in FIG. 1, via conductors 19 obtained by co-firing with ceramic are also formed at locations corresponding to the inner conductor pattern 28 in the lower ceramic sintered layer 16. A plurality of lower surface side mounting pads 27 made of a metallized layer obtained by simultaneous firing with ceramic are provided on the outer peripheral portion of the lower surface 13 of the ceramic substrate 11. The lower surface side mounting pads 27 are electrically connected to the lower ends of the via conductors 19 of the lower ceramic sintered layer 16, respectively. These lower surface side mounting pads 27 are bonded to a plurality of substrate side terminals when the ceramic package 10 is mounted on another substrate (on the motherboard) (not shown). The package form is not particularly limited and may be arbitrary. For example, any of BGA (ball grid array), PGA (pin grid array), and LGA (land grid array) may be used.

  In the ceramic package 10 of the present embodiment, each portion of the conductor (that is, the via conductors 18 and 19, the upper surface side mounting pad 23, the lower surface side mounting pad 27, and the inner layer conductor pattern 28) has a melting point higher than that of alumina. It is made of a mixed phase of a filler mainly composed of a certain chromium-based inorganic metal oxide and copper.

  Next, a method for manufacturing the ceramic package 10 having the above structure will be described with reference to FIGS.

  First, the preparatory process which prepares the ceramic unsintered body which should become the ceramic base | substrate 11 is implemented. Specifically, a ceramic powder such as alumina powder, an organic binder, a solvent, a plasticizer, and the like are mixed to prepare a slurry. Then, this slurry is formed into a sheet having a thickness of 100 μm to 300 μm by a conventionally known method (for example, a doctor blade method or a calender roll method), and three ceramic green sheets 64, 65, 66 as shown in FIG. 2 are produced. To do. A cavity 22 having a substantially rectangular shape in plan view is formed through substantially the center of the upper ceramic green sheet 64. The cavity 22 may be formed by a conventionally known punching (punching) process, or may be formed by a technique such as laser processing or drilling.

More specifically, in the present embodiment, an alumina powder having an average particle diameter of 0.8 μm is used, and this is 90% by weight, and the balance thereof is SiO ₂ , MgO, BaO, MnO ₂ , Nb ₂ O ₅ or the like. Mixed. Such a mixed powder was mixed with a butyral binder, a plasticizer, a solvent and the like to form a slurry.

  In the subsequent drilling step, holes 76 that will later become via conductors 18 are formed through the ceramic green sheets 64, 65, 66, which are ceramic unsintered bodies, respectively (see FIG. 3). The hole 76 may be formed by a conventionally known punching (punching) process, or may be formed by a technique such as laser processing or drilling.

  In the subsequent conductor portion forming step, the conductor portions are respectively formed in the holes 76. More specifically, first, via metallization filling is performed by a conventionally known paste printing apparatus to fill the hole 76 with the conductor paste 77 (see FIG. 4). Next, a predetermined conductor paste 77 is screen-printed in a predetermined pattern on the ceramic green sheets 65 and 66. These printed layers are portions to be the upper surface side mounting pad 23, the lower surface side mounting pad 27, and the inner layer conductor pattern 28 later.

  In the subsequent lamination process, the intermediate ceramic green sheet 65 and the upper ceramic green sheet 64 are sequentially laminated on the lower ceramic green sheet 66, and a predetermined load is applied in the thickness direction using a conventionally known laminating apparatus, These are crimped and integrated to form a laminate (see FIG. 5).

  And after degreasing | defatting this laminated body in nitrogen, it baked by the predetermined | prescribed temperature (1200 to 1400 degreeC) which an alumina can sinter in the humidified nitrogen hydrogen mixed gas under the desired oxygen partial pressure. After this firing step, the upper ceramic green sheet 64, the intermediate ceramic green sheet 65, and the lower ceramic green sheet 66 are sintered, and the ceramic substrate 11 having the cavity 22 is obtained. Also, the upper surface side mounting pad 23, the lower surface side mounting pad 27, the inner layer conductor pattern 28, and the via conductor 18 are formed by sintering the conductor paste 77. It can be understood that the product in this state is a multi-cavity ceramic package having a structure in which a plurality of product regions to be the ceramic package 10 are arranged vertically and horizontally along the plane direction.

  Furthermore, the multi-cavity ceramic package is divided along break grooves (not shown) and separated into individual pieces (see FIG. 6). Thereafter, the IC chip 21 is accommodated in the cavity 22 and soldering is performed. As a result, the element-equipped ceramic package 10 shown in FIG. 1 is completed.

  Next, the evaluation test performed in this embodiment will be described.

  In this evaluation test, a metal material constituting the conductor was changed to prepare a plurality of types of samples (see Nos. 1 to 17 in Table 1), and specific resistance (μΩ · cm) and conductor layer shape (bleeding, Copper ball-like protrusions and warping) were investigated. The results are shown in Table 1. Here, a test sample having a line-shaped conductor layer having a width of 200 μm and a length of 30 mm and a square conductor layer having a size of 12.5 mm × 12.5 mm was prepared by the above-described procedure.

  About specific resistance, after measuring the resistance value of the said line-shaped conductor layer with a 4-terminal ohmmeter, the value was computed based on the cross-sectional area and wiring length of the said line-shaped conductor layer. And if the value of specific resistance was 10 microhm * cm or less, it judged with "good". As for the shape of the conductor layer, the conductor layer was visually observed with a magnifying glass, and “◯ (good)” was given if copper was not extruded onto the surface of the conductor layer or the pad portion. In addition, when the firing shrinkage rates of the ceramic and the square conductor layer did not match and the square conductor layer warped by 200 μm or more, it was determined as “x (defect)”.

Here, Sample No. 1, a conductor paste containing 100 parts by volume of copper (Cu) was used to obtain a conductor layer made of only copper. Sample No. In No. 2, a conductor paste containing 65 parts by volume of tungsten (W) filler and 35 parts by volume of copper was used to obtain a conductor layer composed of a mixed phase of the filler and copper. Sample No. 3, a conductive paste containing 40 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 60 parts by volume of copper having a particle diameter of 0.5 μm is used, and a conductor layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. In 4, the filler 10 parts by volume of chromium oxide (Cr 2 _{O 3),} by using a conductive paste containing copper 90 parts by volume of particle size 0.5 [mu] m, a conductive layer comprising a mixed phase of the filler and copper Obtained. Sample No. 5, a conductor paste containing 70 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 30 parts by volume of copper having a particle size of 0.5 μm is used, and a conductor layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. 6, a conductor paste containing 80 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 20 parts by volume of copper having a particle size of 0.5 μm is used, and a conductor layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. 7, a conductor paste including 70 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 30 parts by volume of copper having a particle diameter of 0.5 μm is used, and a conductor layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. 8, a conductive paste containing 60 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 40 parts by volume of copper having a particle size of 0.5 μm is used, and a conductor layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. 9, a conductor paste containing 50 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 50 parts by volume of copper having a particle size of 0.5 μm is used, and a conductor layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. 10, a conductive paste containing 40 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 60 parts by volume of copper having a particle size of 0.5 μm is used, and a conductive layer made of a mixed phase of the filler and copper is used. Obtained. Sample No. 11, a conductor paste containing 70 parts by volume of chromium oxide (Cr ₂ O ₃ ) filler and 30 parts by volume of copper having a particle size of 5 μm was used to obtain a conductor layer composed of a mixed phase of the filler and copper. . Sample No. 12, a conductive paste containing 70 parts by volume of a copper chromium composite oxide (CuCr ₂ O ₄ ) filler and 30 parts by volume of copper having a particle size of 1.2 μm is used, and is composed of a mixed phase of the filler and copper. A conductor layer was obtained. Sample No. No. 13, a conductive paste containing 60 parts by volume of a copper-chromium composite oxide (CuCr ₂ O ₄ ) filler and 40 parts by volume of copper having a particle size of 1.2 μm is used, and consists of a mixed phase of the filler and copper. A conductor layer was obtained. Sample No. In 14, by using a conductive paste containing a filler 50 parts by volume of the copper chromium complex oxide (CuCr ₂ O _4), and copper 50 parts by volume of particle size 1.2 [mu] m, consists of mixed phases of the filler and copper A conductor layer was obtained. Sample No. 15, a conductive paste containing 40 parts by volume of a copper-chromium composite oxide (Cu ₂ Cr ₂ O ₄ ) filler and 60 parts by volume of copper having a particle size of 1.5 μm is used, and the mixed phase of the filler and copper is used. A conductor layer was obtained. Sample No. 16, a conductive paste containing 70 parts by volume of a copper-chromium composite oxide (Cu ₂ Cr ₂ O ₄ ) filler and 30 parts by volume of copper having a particle size of 1.5 μm is used, and the mixed phase of the filler and copper is used. A conductor layer was obtained. Sample No. In No. 17, a conductor layer comprising 70 parts by volume of a copper chromium composite oxide (CuCrO ₂ ) filler and 30 parts by volume of copper having a particle size of 1.5 μm is used, and a conductor layer comprising a mixed phase of the filler and copper. Got.

  As shown in Table 1, when each sample was prepared, Sample No. 1 (Cu100) and sample no. With respect to 2 (Cu35: W65), bleeding, copper ball-like embossing, and warping were remarkable, and a suitable sample capable of measuring specific resistance could not be obtained.

Regarding the specific resistance, the sample No. In 5-17, the value became lower than 10x10 < ^-8 > ohm * m, and it turned out that it is sufficiently lower than the value of a present article. In particular, sample no. 6 is the lowest, 2 × 10 ⁻⁸ Ω · m, then sample No. 5, no. 7 was as low as 3 × 10 ⁻⁸ Ω · m. On the other hand, sample No. 3, no. 4 exceeded 10 × 10 ⁻⁸ Ω · m, and the resistance could not be sufficiently reduced.

  No. 3-No. Regarding No. 17, the conductor layer shape was good, and bleeding, copper ball-like protrusion and warping were hardly observed.

FIG. 7 is a micrograph (SEM photograph) of the conductor layer of the sample (for example, No. 6) that showed a good result in the previous evaluation test, and FIG. 8 is also a micrograph (TEM photograph) of the conductor layer. In both cases, the dark color particles are Cr ₂ O ₃ and the light color portion is Cu. According to the SEM photograph of FIG. 7, it can be seen that Cr ₂ O ₃ is uniformly dispersed in Cu. Further, Cr ₂ O ₃ grains do not form cohesive unit (more mass diameter 10 [mu] m), the air gap it can be seen that does not exist. According to the TEM photograph of FIG. 8, it can be seen that Cu and Cr ₂ O ₃ are in close contact with each other, and no intermediate layer exists between them. In other words, both chromium oxide and copper-chromium composite oxides are easy to wet with copper and easily wet, so it has been demonstrated that even when mixed with copper, it does not repel copper and exists in a uniformly dispersed state. . It was speculated that this contributed to the reduction in resistance of the conductor.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) Each conductor in the ceramic wiring board 10 of the present embodiment is composed of a mixed phase of copper and a filler mainly composed of a chromium-based inorganic metal oxide having a melting point higher than that of copper. Further, the content of the inorganic metal oxide is set to 10% by volume or more and 60% by volume or less. In this case, since the conductor is formed including copper, the resistance is lower than that of a conventional conductor formed mainly of tungsten. In addition, since it is a conductor composed of a mixed phase of copper and a filler mainly composed of a chromium-based inorganic metal oxide having a melting point higher than that of alumina, even if copper is melted during simultaneous firing, the filler itself is Since it has a high melting point, it remains in a solid state without melting and prevents the molten copper from flowing and volatilizing. As a result, the copper in the conductor is held in that position, and the generation of voids in the conductor and the protrusion of the conductor from the alumina portion are prevented, so that a conductor having a relatively good shape can be obtained.

  Moreover, since an appropriate amount of filler mainly composed of a chromium-based inorganic metal oxide is used, the co-firing property is improved, and the firing shrinkage rate of alumina and metal is also matched, so there is no warping or peeling. Simultaneous firing can be performed.

  From the above, according to the present embodiment, it is possible to obtain the ceramic wiring substrate 10 that has excellent mounting strength and low electrical resistance of the conductor portion, and can be manufactured without causing warpage or peeling due to simultaneous firing.

  In addition, you may change embodiment of this invention as follows.

For example, in the above embodiment, an example of forming a conductor using a chromium oxide, an example of forming a conductor using _{CuCrO 2, CuCr 2 O 4,} Cu 2 Cr 2 O 4 is a copper chromium complex oxide Indicated. However, conductors can also be formed using other copper-chromium complex oxides such as Cu ₂ Cr ₂ O ₅ . Alternatively, the conductor can be similarly formed by using two or more kinds of chromium oxide and the above-mentioned various copper-chromium composite oxides.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above are listed below.

  (1) It has a structure in which a conductor is formed on a ceramic substrate mainly composed of a ceramic sintered at a temperature higher than the melting point of copper, and the conductor is mainly composed of a chromium-based inorganic metal oxide having a melting point higher than that of copper. A ceramic wiring substrate manufacturing method comprising a mixed phase of filler and copper, wherein the content of the inorganic metal oxide is 10% by volume or more and 60% by volume or less, and is fired at a temperature higher than the melting point of copper. Using a non-sintered ceramic substrate mainly composed of ceramic to be bonded, a conductor forming material containing a filler mainly composed of a chromium-based inorganic metal oxide having a melting point higher than copper and copper, and later becomes a conductor. A step of forming an unsintered conductor part to form an unsintered conductor part, and heating the unsintered ceramic base to a temperature at which the ceramic is sintered to fire the unsintered ceramic base and the unsintered conductor part. by doing, Method for producing a ceramic wiring substrate comprising a co-fired to form a ceramic substrate having a conductor content is 60 vol% or less than 10% by volume consists of a mixed phase wherein the inorganic metal oxide of serial filler and copper.

The schematic sectional drawing which shows the ceramic package of embodiment which actualized this invention. The schematic sectional drawing for demonstrating the manufacturing procedure of the ceramic package of embodiment. The schematic sectional drawing for demonstrating a manufacture procedure similarly. The schematic sectional drawing for demonstrating a manufacture procedure similarly. The schematic sectional drawing for demonstrating a manufacture procedure similarly. The schematic sectional drawing for demonstrating a manufacture procedure similarly. The SEM photograph of a conductor part. TEM photograph of conductor part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Ceramic wiring board 11 ... Ceramic base | substrate 18, 19 ... Via conductor as a conductor 23 ... Mounting pad as a conductor 27 ... Mounting pad as a conductor 28 ... Inner layer conductor pattern as a conductor

Claims (7)

In a ceramic wiring board in which a conductor is formed on a ceramic base mainly composed of a ceramic sintered at a temperature higher than the melting point of copper,
The conductor is composed of a mixed phase of a filler mainly composed of a chromium-based inorganic metal oxide having a melting point higher than that of the copper, and the content of the inorganic metal oxide is 10% by volume to 60% by volume. A ceramic wiring board characterized by the above.   The ceramic wiring board according to claim 1, wherein the inorganic metal oxide in the filler is chromium oxide.   The ceramic wiring board according to claim 1, wherein the inorganic metal oxide in the filler is a copper-chromium composite oxide.   The ceramic wiring board according to claim 1, wherein the filler has an average particle size of 10 μm or less.   5. The ceramic wiring board according to claim 1, wherein the conductor is an inner layer conductor pattern and a via conductor formed inside the ceramic base. 6.   5. The ceramic wiring board according to claim 1, wherein the conductor is a mounting pad formed on a surface of the ceramic base. 6. The ceramic wiring board according to claim 1, wherein the conductor has an electric resistivity of 10 × 10 ⁻⁸ Ω · m or less.