JPH11157921A - Oxide ceramic material and multilayer wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-temperature sintering substrate which has a high alumina content, exhibits the inherent characteristics of alumina such as high thermal conductivity, and can be simultaneously fired with a low-resistance wiring metal. Give the material. SOLUTION: The main component contains aluminum oxide,
Further, an oxide ceramic material containing two or more metal oxides capable of forming a stoichiometric compound having a liquid phase generation temperature of 700 ° C. or more and 1060 ° C. or less. Examples of two or more kinds of metal oxides capable of forming a low ratio compound include a combination of manganese oxide and vanadium oxide, a combination of vanadium oxide and magnesium oxide, and a combination of manganese oxide and bismuth oxide. Further, the content of aluminum oxide is desirably 70% by weight or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina (aluminum oxide, aluminum
_{The present invention} relates to an oxide ceramic material mainly composed of ₂ O ₃ ) and a multilayer wiring board using the same.

[0002]

2. Description of the Related Art Multilayer wiring boards on which semiconductor ICs and the like are mounted are roughly classified into an organic substrate mainly composed of an organic material such as glass epoxy, and an inorganic substrate mainly composed of ceramic or glass such as alumina. . Inorganic substrates generally have high heat resistance, high thermal conductivity, low thermal expansion, and high reliability, and are widely used. Inorganic multi-layer substrates are large, and are HTCC (High Temperature Co-fired Ce).
ramics) and LTCC (Low Temperature Co-fired Cer)
amics) system. HTCC uses Al ₂
O ₃ and AlN, in which using BeO, SiC-BeO and the like. These ceramic materials are manufactured by forming a powdery raw material and then firing at a high temperature of 1600 ° C. or higher. Therefore, Mo or W having a high melting point is used as a conductor material formed inside the multilayer substrate. Mo and W have the drawback of having high resistivity as a conductor, but Ag and Cu having low resistivity have low melting points,
If it is fired at a high temperature, it melts and cannot be used as a wiring conductor. Further, the firing temperature of 1600 ° C. or more is a large loss in energy.

Accordingly, LTCC is a ceramic material such as alumina which can be sintered at a low temperature in which Ag and Cu are not melted. LTCC is a ceramic raw material,
By mixing low melting glass materials, it is possible to fire at low temperature, for example, lead borosilicate glass + alumina or borosilicate glass + cordierite,
There are various other composition systems. Since these can be fired at a temperature of 900 ° C. or less, low-resistance Ag or Cu can be used as the internal conductor. For this reason, LTCC is becoming the mainstream of inorganic multilayer substrates rather than HTCC.

[0004]

However, in these LTCCs, 50% by weight of glass is used for low-temperature firing.
More than about. Glass has low thermal conductivity,
The property of high thermal conductivity of HTCC materials is
LTCC has a problem that it is lost.

[0005] The present invention has been made in order to solve the above problems.
An object of the present invention is to enable firing at a low temperature while keeping the content of alumina having high thermal conductivity high.

[0006]

In order to solve the above problems, the oxide ceramic material of the present invention has alumina as a main component and a liquid phase formation temperature of 700 as a subcomponent.
It is characterized by containing two or more kinds of metal oxides capable of forming a stoichiometric compound having a temperature of not less than 1060 ° C. The liquid phase formation temperature referred to here is the temperature at which a liquid phase is first generated when the stoichiometric compound is heated and heated. In many cases, the stoichiometric compound is decomposed at that temperature to form a liquid phase. And other compounds.

It is desirable that at least one of the two or more metal oxides capable of forming the stoichiometric compound is either manganese oxide or vanadium oxide, and in particular, manganese oxide and vanadium oxide, and vanadium oxide and oxide It is desirable to use any combination of magnesium, manganese oxide and bismuth oxide.

Further, it is desirable that manganese oxide and titanium oxide are contained as the fourth and fifth components. However, when either manganese oxide or titanium oxide is contained as the oxide forming the stoichiometric compound, only the other may be contained as the fourth component.

Among them, in particular, it contains at least manganese oxide, vanadium oxide and titanium oxide as subcomponents, and further comprises at least one of bismuth oxide and copper oxide, and / or calcium oxide, strontium oxide and barium oxide. It is desirable to include one or more types from the group.

It is desirable that the amount of aluminum oxide contained in the ceramic is not less than 70% by weight and not more than 98% by weight.

The material is preferably fired at a temperature of 1060 ° C. or less, and more preferably at a temperature of 960 ° C. or less.

The thermal conductivity of the material is 5 W / m · K
It is desirable that it is above.

Further, the inorganic multilayer substrate of the present invention has at least an insulating layer made of the above ceramic material and a conductor. This conductor preferably contains copper or silver as a main component.

[0014]

Embodiments of the present invention will be described below in detail. Alumina (aluminum oxide, Al
₂ O ₃ ) and various metal oxide powders are mixed well using a mixer such as a ball mill. A small amount of a molding organic binder such as polyvinyl alcohol is mixed with the mixed powder, and the mixture is passed through a mesh to granulate the mixture. This granulated powder is placed in a mold of an appropriate size, and molded using a pressure press to obtain a molded body.

An organic binder and a solvent for sheet molding are sufficiently mixed and kneaded with the same mixed powder to form a slurry. The slurry is drawn on a base film to form a sheet. Is dried to obtain a green sheet.

On the other hand, a metal for conductor or its precursor powder, an oxide glass powder, and an organic vehicle component comprising an organic binder and a solvent are sufficiently mixed and kneaded to prepare a conductor paste for inner wiring. A conductor paste for a via is similarly produced with the same composition or a slightly changed composition ratio. A via hole is formed on the green sheet prepared above. Then, the via paste of the green sheet is filled with the via conductor paste. Next, after a wiring pattern is printed on the green sheets using the conductor paste for inner wiring, these green sheets are laminated to form a laminate. The green body laminate and the green body containing the oxide of the present invention prepared as described above are subjected to a binder removal treatment in a heating furnace at a temperature of about 600 ° C. At a suitable temperature to obtain a sintered body and a multilayer substrate.

In the present invention, by mixing alumina powder with manganese oxide, vanadium oxide, titanium oxide powder, etc., sintering can be performed at a temperature much lower than that of ordinary alumina. This is very advantageous in terms of the cost of the furnace used. Also, 1
Since firing can be performed at 060 ° C. or lower, simultaneous firing can be performed using low-resistance Cu as a conductor, and high heat conduction can be maintained when applied to a multilayer substrate or the like. Furthermore, by mixing with bismuth oxide powder or copper oxide powder, sintering can be performed at a lower temperature,
Since firing can be performed at 960 ° C. or lower, simultaneous firing can be performed using low-resistance Ag as a conductor.

Further, when any one or more of calcium oxide, strontium oxide and barium oxide is included, the dielectric properties thereof are improved. However, the amount of alumina is
It is preferable that the content be 70% by weight or more, and more preferably 80% by weight or more. Further, as for the additives other than alumina, the sinterability and the dielectric properties are better when the mutual ratio is within a specific range.

The particle size of the alumina powder used as a raw material can be used as long as it is not extremely rough. However, in order to obtain a higher density at a lower temperature, the smaller the particle size, the better.
It is desirable that: On the other hand, considering the case of molding, if it is too small, it is difficult to handle.
It is desirable that the thickness be 1 μm or more. The particle size of the additives other than alumina may be slightly larger than this.

The conductor used for the multilayer substrate of the present invention is not particularly limited. However, in order to take advantage of the fact that it can be sintered at a low temperature, it is preferable that copper or silver having low resistance be a main component. In particular, it is preferable to use silver because the binder can be removed in the air.

There is no particular limitation on the method for producing the molded article and the green sheet, and examples thereof include a uniaxial molding method, an isostatic pressing method, a doctor blade method, a calendar method, and a roll coater method.

As the base film for holding the sheet, for example, polyethylene resin, polyester resin, paper, etc. can be used. Further, as a method of forming a via hole in the insulating sheet, for example, punching or laser processing can be used.

The atmosphere for the heat treatment of the laminate is not particularly limited, and can be appropriately selected depending on the type of the conductive metal used and the purpose of binder removal, metallization, firing and the like.
Nitrogen, hydrogen, carbon dioxide or a mixed gas thereof can be used.

According to the present invention, the reason why the ceramic mainly composed of alumina sinters at a low temperature is not clear, but it is considered as follows. In other words, when sintering the hardly sinterable alumina at a low temperature, the intervention of the liquid phase by the additive is indispensable. However, it does not mean that a liquid phase only needs to be generated, and the liquid phase generation temperature is important. That is, if the liquid phase generation temperature is too high, it cannot naturally contribute to sintering at a low temperature. Conversely, if the liquid phase is formed at too low a temperature, for example, around 650 ° C.,
In the vicinity of ° C., even if a liquid phase exists, sintering does not progress much because the temperature is too low and the mass transfer rate is slow.
If the temperature is raised to about ° C. or higher, only the liquid phase exudes below the sintered body before sintering progresses, and in this case also, it cannot contribute to sintering.

On the other hand, if an additive capable of forming a stoichiometric compound having a specific liquid phase formation temperature is used, the formation of the stoichiometric compound limits the liquid phase formation temperature to a specific range. It is considered that this can effectively contribute to promotion of sintering of alumina. The liquid phase formation temperature of the stoichiometric compound is 70
The reason why the temperature is limited to 0 ° C. or more and 1060 ° C. or less is the same. The reason why the system containing manganese oxide or vanadium oxide is particularly effective is considered to be because the wettability between the generated liquid phase and alumina and the solubility of alumina in the liquid phase differ depending on the liquid phase composition.

[0026]

The present invention will be described below in detail with reference to examples. <Example 1> Aluminum oxide (Al ₂ O ₃ ) powder as a reagent and powders of various metal oxides were used as starting materials. These have the composition ratio shown in Table 1 and the total weight is 2
It was weighed so as to be 00 g and wet-mixed for 12 hours in a ball mill using alumina balls. After drying the powder,
A small amount of an aqueous solution of polyvinyl alcohol was mixed and passed through a # 32 mesh sieve to granulate. This powder was uniaxially pressed into a mold having a diameter of 12 mm and a thickness of about 1 mm in a mold. The obtained molded body is placed in air at 500 ° C. for 1 hour.
After heating for a time to perform binder-out, baking was performed at 1060 ° C. for 30 minutes. The sintered density was calculated by measuring the size and weight of the sintered body.

A plurality of the same sintered bodies were prepared, crushed, and the true density was measured using a pycnometer, and the relative sintered density was determined from the sintered density / true density. Further, the thermal conductivity of the sample was measured by a laser flash method. The results are shown in Table 1.

[0028]

[Table 1]

As is clear from Table 1, alumina alone,
Alternatively, when only one type of various additives was used, no sintering was performed at all even if the additives used had a low melting point, such as Bi ₂ O ₃ or V ₂ O ₅ . On the other hand, the sample No. 8,
In the case of a combination of oxides capable of forming a stoichiometric compound such as 9,13,16,21,23,24 and the liquid phase formation temperature is 700 ° C or higher and 1060 ° C or lower, the density becomes considerably high. , The thermal conductivity also became 10 W / m · K or more.

Sample No. Samples Nos. 11, 18, 20, and 22 form stoichiometric compounds, but their liquid phase formation temperatures are too high. 15 also formed a stoichiometric compound, but its liquid phase formation temperature was 650 ° C., which was lower than 700 ° C., so sintering did not proceed very much. Note that this No. 16 and No.
24, when two or more stoichiometric compounds are formed, the lowest liquid phase formation temperature among them is required to be 700 ° C. or more and 1060 ° C. or less.

Next, the sample No. showing the low-temperature sinterability was prepared. 8,
If you compare 9,13,16,21,23,24,
Sample No. Nos. 8, 9, and 13 have the highest density. 2
Nos. 3 and 24 are next. 16 and 21 had lower densities than the others. Therefore, the combination containing manganese oxide or vanadium oxide had the greatest effect, and particularly the combination of manganese oxide and vanadium oxide, manganese oxide and bismuth oxide, and vanadium oxide and magnesium oxide exhibited the greatest effect.

<Example 2> In the same manner as in Example 1, raw material powders having the composition ratios shown in Table 2 were prepared.
By sintering at 940 ° C. for 6 hours in the same manner as described above, a sintered body was prepared, and the relative sintered density and the thermal conductivity were measured in the same manner. The results are shown in Table 2.

[0033]

[Table 2]

As is clear from Table 2, alumina alone,
Alternatively, when only one type of various additives was used, the density of the sintered body did not increase and the thermal conductivity was low even when the amount of the low melting point additive increased to 40% by weight. In contrast, Mn and V form a stoichiometric compound having a low liquid phase formation temperature.
In the composite addition of the oxide, a remarkable densification effect was recognized even with a small amount of addition, and the thermal conductivity was improved with the densification. However, when the added amount exceeded a certain level, the thermal conductivity began to decrease, and when the added amount was 40% by weight, it became extremely low.

The reason why the amount of alumina of the present invention is limited to 70% by weight or more is that if the amount is less than 70% by weight, as shown in this example, the alumina content decreases too much, and the inherent characteristics of alumina are reduced. This is because it is no longer exhibited, and it is more desirable that the amount of alumina is 80% by weight or more. On the other hand, if alumina is contained in a certain amount or more,
The mixing ratio of the two kinds of oxides, manganese oxide and vanadium oxide in this example, is as far as densification and thermal conductivity are concerned.
Sample No. The ratio did not have to be 1: 1 as shown in FIGS. 13-15, but could be used in any of a fairly wide range of ratios.

Next, the same alumina content (88% by weight)
As compared with Sample No., Sample No. 13 contains oxides of Mn and V, while Sample No. 13 18 further contains an oxide of Ti, and simultaneously contains Mn and Ti. As a result, Sample No. containing only Mn and V was used. 13 and higher density and higher thermal conductivity. A similar relationship is obtained with Sample No. 1 containing Mg and V oxides. Sample No. 19 obtained by further adding oxides of Mn and Ti to Sample No. 19. It was also seen during the 20th.

That is, as shown in Example 1, Mn
The addition of Ti and Ti alone did not contribute much to low-temperature sintering.
Further, by containing oxides of Mn and Ti, densification was further improved and higher thermal conductivity was obtained. Note that when one of the two oxides is an oxide of Mn or Ti, only the other one needs to be added. 18 is more obvious.

Next, the sample no. Sample No. 21 is obtained by further adding Bi to Mn and V. 1
Sample No. 3 containing only Mn and Bi. Compared to No. 17, it became more dense. This is a system including two sets of two types of oxides, Mn and V, and Mn and Bi, which form a stoichiometric compound having a low liquidus phase formation temperature. The effect became remarkable.

Sample No. Similarly, Mg and V, Mn
And V; 23 is also more effective because it contains Mg and V and Mn and Bi. However, the sample No. In the case of No. 24, for example, There was no particular advantage compared to 19. Furthermore, the highest density and the highest thermal conductivity, Comparing Nos. 18, 20, 21, and 23, No. 3 containing three components of Mn, V, and Ti simultaneously.
Nos. 18 and 20 were characterized in that the dielectric loss was particularly small.

In summary, the combination of two or more oxides forming a stoichiometric compound having a low liquid phase formation temperature may be obtained by including two or more combinations, or by including one set and Mn and Ti.
Densification and higher thermal conductivity were possible than when one set was included. Considering also the dielectric loss, those containing the three components of Mn, V and Ti at the same time were the best.

<Example 3> In the same manner as in Example 1, raw material powders were prepared in which the weight ratio of the oxides of each component had the composition ratio shown in Table 3. As the alkaline earth metal, calcium carbonate, strontium carbonate, and barium carbonate were used as raw material powders, and weighed so that the weight ratio when each was thermally decomposed into CaO, SrO, and BaO became (Table 3). did. From this, 900 to 1040 in the same manner as (Example 1)
It was fired at each temperature of 1 ° C. for 1 hour to obtain a sintered body. The relative density of the obtained sintered body was measured, and the lowest sintering temperature of 96% or more was determined. At this time, the thermal conductivity and dielectric loss of the sintered body were measured. The results are shown in Table 3.

[0042]

[Table 3]

As is clear from Table 3, Mn, V, Ti
Further, by adding Bi or Cu alone or in combination, it is possible to densify at lower temperature. In addition, Ca, S
By adding r and Ba, the dielectric loss was significantly improved.

Example 4 In the same manner as in Example 3, alumina was 90% by weight, and the total amount of other components was 10% by weight.
The weight ratio of each oxide in the other components is shown in Table 4.
Was prepared and fired at each temperature of 920 ° C. for 2 hours in the same manner as in Example 3. The relative density, thermal conductivity, and dielectric loss of the obtained sintered body were measured. The results are shown in Table 4.

[0045]

[Table 4]

As is clear from Table 4, Mn, V, T
i, Bi, Cu, Sr complex addition system, density, thermal conductivity,
All of the good dielectric loss is due to the fact that manganese oxide
Weight% or more and 40 weight% or less, vanadium oxide is 20 weight% or more and 70 weight% or less, titanium oxide is 1 weight% or more and 5 weight% or less, and the total amount of bismuth oxide and copper oxide is 5 weight% or more and 40 weight% or less, In this case, the amount of strontium carbonate was 1% by weight or more and 10% by weight or less in terms of strontium oxide.

The present inventors conducted similar experiments by changing strontium to calcium, barium, or a combination thereof. In any case, the total amount was 1% by weight to 10% by weight in terms of oxide. In the case of the above, all of the density, the thermal conductivity, and the dielectric loss were good.

The present inventor has set the amount of alumina to 70 to
A similar experiment was performed, changing to 98% by weight. as a result,
As the amount of alumina increases, it is necessary to fire at a higher temperature in order to obtain good properties, and as the amount decreases, the thermal conductivity of the obtained sintered body decreases. As for manganese oxide, manganese oxide is 15% by weight or more and 40% by weight or less, and vanadium oxide is 20% by weight or more and 70% by weight or less.
Wt% or less, titanium oxide is 1 wt% to 5 wt%,
The best results are obtained when the total amount of bismuth oxide and copper oxide is 5% by weight or more and 40% by weight or less, and the total amount of calcium carbonate, strontium carbonate and barium carbonate is 1% by weight or more and 10% by weight or less in terms of oxide. Characteristics were obtained.

<Embodiment 5> In the same manner as in Embodiment 1, A
90% by weight of l ₂ O ₃ , ₃ % by weight of Mn ₃ O _{4 and 5} % of V ₂ O 5
After weighing so that the content of TiO ₂ becomes 2% by weight and wet mixing and drying, 15% by weight of an acrylic resin as a binder and 15% by weight of toluene as a binder are prepared in 70% by weight of the mixed powder. After sufficiently mixing and kneading with a ball mill, the mixture was defoamed to prepare a slurry. The slurry was formed into a sheet having a thickness of about 200 μm by a doctor blade method on a base film (polyphenyl sulfide) having a surface subjected to a release treatment. For comparison, a slurry was prepared in the same manner as described above using a powder containing 99% by weight of Al ₂ O ₃ and 1% by weight of MgO, and an alumina green sheet was formed on a base film.

Next, silver or copper and glass powder were prepared as raw materials for the conductor paste. To these powders, an ethylcellulose-based resin as an organic binder and an appropriate amount of terpineol as a solvent were added, and the mixture was sufficiently mixed and kneaded with a three-roll mill to prepare an inner-layer wiring conductor paste and a via conductor paste.

Next, a φ0.
After punching a 15 mm via hole by punching and filling the via holes of the required number of insulating sheets with a via conductor paste, a wiring pattern was formed on the sheet by screen printing using an inner layer wiring paste. The base sheet was peeled off, the insulating sheets were laminated, and thermocompression bonded at 80 ° C. to obtain a laminated body.

When the metal in the conductor is silver, the obtained laminate is subjected to binder removal treatment at 600 ° C. in the air in a heating furnace.
Further, firing was performed at a predetermined temperature. If the metal is copper,
The laminate was subjected to a binder removal treatment in a heating furnace at 700 ° C. in an atmosphere of nitrogen containing 60 ppm of oxygen, and was fired at a predetermined temperature in a nitrogen gas atmosphere containing 20 ppm of oxygen. The conduction between the inner layer wiring and the via conductor of the inorganic multilayer wiring substrate thus obtained and the substrate strength were evaluated. Table 5 shows the results
It was shown to.

[0053]

[Table 5]

As is clear from Table 5, when a conductor having a low resistance of silver or copper as a main component is used, when Ag is used as a conductor, Cu is set to about 940 ° C. or less, according to the melting point. In this case, it is necessary to fire at about 1060 ° C. or less. However, when the material of the present invention is used, it is possible to densify even at 900 ° C. or less, so that an appropriate firing temperature of 1060 ° C. or less can be selected. There is no problem in the conduction of the substrate and the strength of the substrate. On the other hand, in the case of conventional alumina, silver and copper were melted when fired at a temperature (1500 ° C. or higher) at which strength as a substrate was exhibited, and the conductor was disconnected, and could not be used.

[0055]

As described above, the present invention is a ceramic material containing aluminum oxide and two or more specific metal oxides, and can be fired at a much lower temperature than before. Restrictions on energy costs and furnaces used are reduced. Further, since the content of aluminum oxide is large, it exhibits characteristics similar to the original alumina, such as high thermal conductivity, and can be used as a substitute material for alumina. Further, since sintering can be performed at a temperature of 1060 ° C. or less, a structure containing a conductor having copper or silver as a main component having a low resistivity can be included in the inside thereof.
It is extremely useful for applications involving wiring.

Claims (14)

[Claims] 1. An aluminum oxide as a main component,
As a subcomponent, the liquid phase formation temperature is 700 ° C or higher and 1060 ° C
An oxide ceramic material comprising two or more metal oxides capable of forming the following stoichiometric compound. 2. The oxide ceramic material according to claim 1, wherein at least one of the two or more metal oxides capable of forming the stoichiometric compound is manganese oxide or vanadium oxide. 3. The method of claim 2, wherein the two or more metal oxides capable of forming the stoichiometric compound are selected from the group consisting of a combination of manganese oxide and vanadium oxide, a combination of vanadium oxide and magnesium oxide, and a combination of manganese oxide and bismuth oxide. The oxide ceramic material according to claim 1, wherein the material comprises at least one combination. 4. The oxide ceramic material according to claim 1, further comprising manganese oxide and titanium oxide at the same time. 5. The method according to claim 1, wherein the auxiliary component contains at least manganese oxide, vanadium oxide and titanium oxide, and further contains at least one oxide of the following group A. The oxide ceramic material according to the above. Group A: bismuth oxide, copper oxide. 6. The method according to claim 1, wherein the auxiliary component contains at least manganese oxide, vanadium oxide and titanium oxide, and further contains one or more oxides of the following group B. The oxide ceramic material according to the above. Group B: calcium oxide, strontium oxide, barium oxide. 7. The method according to claim 5, wherein the auxiliary component includes manganese oxide, vanadium oxide, and titanium oxide, and further includes at least one oxide of the following Group A and Group B, respectively. Oxide ceramic materials. Group A: bismuth oxide, copper oxide Group B: calcium oxide, strontium oxide, barium oxide. 8. The ratio of each of the above oxides to the total amount of manganese oxide, vanadium oxide, titanium oxide, and at least one oxide selected from each of the groups A and B constituting the subcomponent 15 wt% ≦ manganese oxide ≦ 40 wt%, 20 wt% ≦ vanadium oxide ≦ 70 wt%, 1 wt% ≦ titanium oxide ≦ 10 wt%, 5 wt% ≦ Group A oxide ≦ 40 wt%, 1 wt respectively The oxide ceramic material according to claim 7, wherein% ≦ B group oxide ≦ 10% by weight. 9. The oxide ceramic material according to claim 1, wherein the content of said aluminum oxide is 70% by weight or more and 98% by weight or less. 10. The oxide ceramic material according to claim 1, which can be fired at a temperature of 1060 ° C. or less. 11. The oxide ceramic material according to claim 1, which can be fired at a temperature of 960 ° C. or lower. 12. The oxide ceramic material according to claim 1, having a thermal conductivity of 5 W / m · K or more. 13. A multilayer wiring board comprising at least an insulating layer made of the oxide ceramic material according to claim 1 and a conductor. 14. The multilayer wiring board according to claim 13, wherein said conductor contains copper or silver as a main component.