JPH0529315B2 - - Google Patents

Description

[Detailed description of the invention]

[Purpose of the Invention] (Field of Industrial Application) The present invention provides a surface conductive ceramic substrate using a nitride-based ceramic substrate having a conductive metallized layer with excellent surface properties and electrical properties, a method for manufacturing the same, and a nitrided ceramic substrate. The present invention relates to a metallizing composition useful for solid ceramic substrates. (Prior Art) In recent years, nitride-based ceramic substrates such as AlN substrates, which have high thermal conductivity, have been attracting attention as circuit boards for hybrid ICs and the like. By the way, when a ceramic substrate is used as a circuit board, it is essential to form a conductive layer on its surface, and the conventional method for forming a conductive layer on the surface of the above-mentioned nitride-based ceramic substrate is as follows. It was done by method. A metallizing paste is prepared from a mixed powder of a high melting point metal such as Mo or W with the addition of a nitride of an active metal such as Ti, and this metallizing paste is applied onto a ceramic substrate and then fired. A method of bonding high melting point metals to the ceramic substrate surface by improving the leakage of the ceramic substrate through the action of active metals. A metallizing paste made by adding and mixing compounds such as oxides and nitrides of active metals such as Ti to Mo and W compounds such as Li ₂ MoO ₄ is applied, and the paste is fired and reduced to form Mo and W compounds. How to form a metallized layer. (Problem to be solved by the invention) However, in the method of using a metallizing paste made by adding and mixing an active metal nitride to a high-melting point metal such as Mo or W, the firing temperature is 1700°C to 1800°C.
Sufficient bonding strength cannot be obtained unless the temperature is high.
As a result, the substrate may warp, and a metallized layer cannot be formed unless the active metal is added in a large amount, at least 70% by weight, resulting in a reduction in the amount of high melting point metal. However, since the electrical resistance is large and the difference in coefficient of thermal expansion from the ceramic substrate is large, cracks are likely to occur due to heating and cooling cycles. In addition, this method can be applied to AlN ceramic substrates with a thermal conductivity of about 150 W/m・k and a large number of grain boundary phases; There was also the problem that it could not be applied to materials with few interphases due to variations in strength. This is because the grain boundary constituent phase components unevenly present in the AlN ceramic substrate contribute to the bonding between the metallized layer and the ceramic substrate during firing, and also.
AlN ceramic substrates with many grain boundary phases of about 150 W/m·k also have problems such as variations in bonding strength. Furthermore, when semiconductor elements and the like are actually mounted on this metallized layer, this is done after plating the surface of the metallized layer, but once the grain boundary phase appears on the surface of the metallized layer, the plating layer is reliably formed. There is also the problem of not being able to do so. In addition, when applying a metallizing paste containing Mo or W compounds as the main components, bleeding occurs during application and firing, making it difficult to maintain the shape of the circuit pattern, and insufficient surface properties are obtained. There was a problem. The present invention was made to address these conventional problems, and even at a relatively low firing temperature, the electrical resistance is small, the variation in bonding strength is small, the strength is high, and the shape of the pattern is maintained. The present invention aims to provide a surface conductive ceramic substrate having a metallized layer with good properties, a method for manufacturing the same, and a metallizing composition used therein. [Structure of the Invention] (Means for Solving the Problems) The surface conductive ceramic substrate of the present invention has Mo and/or W, a group a active metal element, V, Cr, Mn,
It is characterized in that a conductive metallized layer containing at least one element selected from Fe, Co, and Ni as a constituent element is formed. Further, the method for manufacturing a surface conductive ceramic substrate of the present invention includes:
Combined with a metallizing composition mainly composed of Mo and/or W, an oxide of a group A active metal, and a compound of at least one element selected from V, Cr, Mn, Fe, Co, and Ni. A conductive metallized layer is formed by applying a fluid material, such as a paste-like material, containing an agent and then firing at 1700° C. or lower in an inert atmosphere. Furthermore, the metallizing composition for nitride-based ceramic substrates of the present invention is composed of Mo and/or W.
from 26 to 90% by weight, and 5% by weight of group A active metal oxide.
~70 wt% with V, Cr, Mn, Fe, Co and Ni
A compound of at least one element selected from 2
~20% by weight. Examples of the nitride-based ceramic substrate used in the present invention include those made of a ceramic sintered body containing AlN, Si ₃ N ₄ , SiAlON, etc. as a main component. The conductive metallized layer in the surface conductive ceramic substrate of the present invention comprises Mo and/or W, a group a active metal element, and at least one element selected from V, Cr, Mn, Fe, Co, and Ni. It is contained as an element, and Mo and W are high melting point metals that do not oxidize even at high temperatures and serve as main conductors. In particular, W has a coefficient of thermal expansion closer to that of nitride ceramic substrates than Mo.
It also has good electrical conductivity and thermal conductivity. Group a active metal elements, namely Ti, Zr and
At least one element selected from Hf is present in the conductive metallized layer in the form of nitride or the like,
This is a component that firmly bonds the conductive metallized layer to the ceramic substrate, and also reacts with the components of the ceramic substrate to form an intermediate reaction layer between the ceramic substrate surface and the conductive metallized layer, further improving the bonding strength. It is possible to do so. At least one element selected from V, Cr, Mn, Fe, Co and Ni reacts with a compound of group a active metal element to form a composite compound, and this composite compound is heated at a temperature of about 1300℃ to 1450℃. Since it forms a liquid phase at a relatively low temperature, it contributes to lowering the firing temperature. In order to form a conductive metallized layer containing such constituent elements, it is necessary to use Mo and/or W.
, an oxide of a group a active metal, V, Cr, Mn,
It can be easily obtained by using a metallizing composition containing as a main component a compound of at least one element selected from Fe, Co, and Ni. The components in this metallizing composition are 26 to 90% by weight of a high melting point metal, 5 to 70% by weight of an oxide of a group A active metal, V, Cr, Mn, Fe,
It is preferable that the compound of at least one element selected from Co and Ni be blended in an amount of 2 to 20% by weight. The reason why each component in this metallizing composition and its blending ratio was defined as above is as follows. If the blending ratio of the high melting point metal is less than 26% by weight, the electrical resistance of the resulting conductive metallized layer will increase, and if it exceeds 90% by weight, the bonding strength to the ceramic substrate will decrease. Oxides of Group A active metals are activated at the firing temperature and react with the nitride-based ceramic substrate as a base material to mainly form nitrides, which can improve the bonding strength of the conductive metallized layer.
Ti oxides such as TiO and TiO ₂ are highly reactive and effective. If the blending ratio of the group A active metal oxide is less than 5% by weight, the effects of lowering the bonding strength and lowering the firing temperature will not be sufficiently obtained, and even if it exceeds 70% by weight, no further effect will be obtained. Not only is this not possible, but the blending ratio of the high melting point metal is reduced, which increases the electrical resistance of the conductive metallized layer. Moreover, the strength of the metallized layer itself is reduced. As compounds of V, Cr, Mn, Fe, Co, and Ni,
Examples include oxides, chlorides, fluorides, etc., especially
Co oxides such as Co ₂ O ₃ are effective. V, Cr,
If the blending ratio of the compound of at least one element selected from Mn, Fe, Co, and Ni is less than 2% by weight, the effect of lowering the firing temperature will not be sufficiently achieved,
If it exceeds % by weight, the blending ratio of the high-melting point metal decreases similarly to the oxide of the Group A active metal, making it difficult to obtain sufficient electrical conductivity of the metallized layer. Furthermore, in addition to the above-mentioned components, the metallizing composition of the present invention may contain Ni or Ca compounds such as CaO, CaF ₂ , and CaCO ₃ in order to improve the sinterability of high-melting point metals. It is. In addition,
If Na is used, use its metal powder. This fourth component also has the effect of preventing agglomeration of the metallizing composition during firing, which also provides the advantage of reducing the need to strictly control the firing atmosphere. The blending amount of this Ni or Ca compound is preferably 2 to 15% by weight; if it is less than 2% by weight, it is difficult to obtain the above-mentioned effects sufficiently;
Even if it exceeds % by weight, no further effect can be obtained. The surface conductive ceramic substrate of the present invention is manufactured, for example, as follows. First, a metallizing composition consisting of the above-mentioned components is mixed with an organic binder and, if necessary, a dispersion medium to prepare a metallizing paste having a desired viscosity. Then, this metallizing paste is applied to the surface of a nitride-based ceramic substrate in the desired pattern shape by, for example, screen printing, and after drying, it is heated at a temperature of 1700°C or less in an inert atmosphere such as nitrogen gas. The conductive metallized layer is formed by heating and firing, preferably at a temperature of 1,600°C or lower, more preferably at a temperature of 1,450°C to 1,550°C. The firing temperature in the present invention is such that the oxide of group a active metal in the metallizing composition and V, Cr, Mn,
Due to the action of at least one element selected from Fe, Co, and Ni, it is possible to form a metallized layer with strong bonding strength even at a relatively low temperature of 1700° C. or lower. This can be used, for example, as a ceramic substrate.
AlN substrate using Y ₂ O ₃ as sintering aid,
Ti oxide as a group a active metal oxide, V,
Considering the case where Co oxide is used as a compound of at least one element selected from Cr, Mn, Fe, Co, and Ni, Ti oxide and Co oxide are combined in the firing stage of the metallizing paste. For example, xCoO・yTiO
(x:y=2:1, 1:1, etc.). Since such a composite compound has a low melting point, it forms a liquid phase during the firing process, and the metallized layer components are sufficiently diffused without melting the AlN grain boundary constituent phase components, thereby forming an intermediate reaction layer.
This intermediate reaction layer is composed of a Ti compound such as TiN, which is formed when a part of the Ti oxide reacts with AlN during firing, and Y ₂ O ₃ , which is a phase component of the grain boundary of AlN.
It is a solidified liquid phase component formed by compounds such as YAG, YAM, and YAL, which are produced by the reaction of Al ₂ O ₃ , which is formed at the same time as TiN is formed. By forming a liquid phase between the metallized phase and the ceramic substrate, excellent bonding strength can be obtained even at a relatively low temperature of 1700℃ or less, and each component forming this intermediate reaction layer At the firing temperature of the present invention, it does not penetrate to the surface of the metallized layer and solidifies at the interface between the metallized layer and the ceramic substrate, so there is no fear of an increase in electrical resistance. In addition, as mentioned above, the liquid phase formed by the composite compound of Ti oxide and Co oxide
Since diffusion of AlN into the grain boundary constituent phase on the metallized layer side is promoted, strong bonding is possible even on ceramic substrates with few grain boundary constituent phases, in other words, ceramic substrates with high purity and high thermal conductivity. . Furthermore, the Ti oxide reacts with AlN to form a Ti nitride, thereby contributing to bonding of the metallized layer. By producing a surface conductive ceramic substrate in this way, it is possible to combine nitrides of group A active metals and oxides of group A active metals with V, Cr, Mn, Fe,
Although it contains a complex compound with a compound of at least one element selected from Co and Ni, W and
A surface conductive ceramic substrate is obtained in which a conductive metallized layer with a high Mo content is firmly bonded to a nitride ceramic substrate by an intermediate reaction layer. (Function) In the present invention, oxides of group a active metals and V, Cr, Mn, Fe, Co
and a compound of at least one element selected from Ni, these produce a low melting point composite, which forms a liquid phase to form a metallized layer on the ceramic substrate at low temperatures. This makes it possible to form a large amount of W and Mo, and also allows the amount of W and Mo to be increased far more than in the past. In addition, the liquid phase of this composite compound promotes diffusion of the metallized layer side into the grain boundary constituent phases of the nitride-based ceramic substrate, resulting in a ceramic substrate with less grain boundary constituent phases, in other words, a ceramic with high purity and high thermal conductivity. Also on the substrate, an intermediate reaction layer that acts as an adhesive between the ceramic substrate and the metallized layer is sufficiently formed.
Therefore, a surface conductive ceramic substrate with excellent bonding strength between the ceramic substrate and the metallized layer is obtained. Furthermore, the grain boundary constituent phase components of the nitride-based ceramic substrate diffused to the metallized layer side almost become the constituent components of the intermediate reaction layer, and hardly seep out onto the surface of the metallized layer, making it easy to form a plating layer. becomes. (Example) Next, an example of the present invention will be described. Examples 1 to 3 First, Co ₂ O ₃ powder was added to a mixed powder of Mo and TiO ₂ to form a paste. In this case, Mo and
By changing the mixing ratio of the mixed powder with TiO ₂ and the mixing ratio of Co ₂ O ₃ powder to this mixed powder as follows,
Three types of pastes with different composition ratios were prepared. The composition ratio (weight ratio) is as follows. (Mo：
TiO ₂ ):Co ₂ O ₃ = (75:25): 5, (90:10): 5,
(95:5):5. Further, an aluminum nitride substrate was manufactured using a powder obtained by adding 3% by weight of Y ₂ O ₃ powder to aluminum nitride powder. and,
The prepared paste was applied to a thickness of approximately 10 μm on the surface of an aluminum nitride substrate. Next, the paste applied to the aluminum nitride substrate was fired. This firing temperature is 1700℃, 1650℃, 1600℃, 1550℃,
The temperature was changed to 1500℃. The firing atmosphere is
It is _N2 gas. A test was conducted to measure the bonding strength of the metallized layer on the surface conductive ceramic substrate thus produced. In this test method, a Ni plating layer with a thickness of 5 μm to 7 μm is formed on the surface of the metallized layer, and a solder-plated annealed copper wire with a length of 60 mm and a diameter of 0.8 mm is formed on a 2 mm x 2 mm portion of this plating layer. In this method, a pin is soldered, a tensile force is applied to the pin, and the tensile force when the pin is removed is determined as the joint strength. As a result, the bonding strength of the metallized layer of each circuit board was 4 Kgf/mm ² to 5 Kgf/mm ² when fired at temperatures of 1550°C and 1500°C.
Further, no variation in bonding strength was observed depending on the metallized layer of each circuit board. Examples 4 and 5 First, 2~2~ of Y ₂ O ₃ was added to AlN powder as a sintering aid.
Using a mixed powder containing 4% by weight, the thickness is 0.4mm.
AlN ceramic substrate A with a thermal conductivity of 200 W/m・k and a thermal conductivity of 260 W/m・k with a thickness of 0.5 mm.
An AlN ceramic substrate B was fabricated. On the other hand, using Mo powder, TiO ₂ powder, and Co ₂ O ₃ powder, these were mixed with Mo81.8% by weight, _TiO2 9.1% by weight,
Co ₂ O ₃ was mixed to a concentration of 9.1% by weight, and the average particle size was
A 0.8 μm metallizing composition was prepared, and then an organic binder and a dispersion medium were added to the metallizing composition and thoroughly mixed to prepare a metallizing paste a. Next, this metallizing paste a was screen printed on the ceramic substrates A and B described above with a #325 mesh to a thickness of 20 μm after drying.
After drying, the ceramic substrate A was heated at 1500°C and the ceramic substrate B was heated at 1550°C for 180 minutes to make it conductive. A ceramic substrate with a metallized layer was manufactured. The ceramic substrate thus obtained was examined using a scanning electron microscope and an energy-dispersive
Analysis using a line microanalyzer revealed that at a depth of 10 to 12 μm from the surface, there is a metallized layer containing Mo as the main component and trace amounts of TiN and a compound of TiO and CoO, and the relationship between this metallized layer and the ceramic substrate. An intermediate reaction layer containing a compound of Al and Y and TiN was observed at the interface. Furthermore, the bonding strengths of the metallized layer thus obtained, measured in the same manner as in Example 1, were 4Kgf/mm ² to 4.5Kgf/mm ² and 2.5Kgf/mm ² to 3, respectively.
It had an excellent Kgf/ ^mm2 . In addition, the surface resistance of these metallized layers is 102mΩ/□, respectively.
It was a good value of 105 mΩ/□. On the other hand, for comparison with the present invention, a metallizing paste (Comparative Example 1) obtained by mixing Mo powder and Ti powder at a composition ratio (weight ratio) of 1:2 and adding a binder and Mo powder and Ti powder were prepared. The ceramic substrate A used in Examples 4 and 5 was prepared using a metallizing paste (Comparative Example 2) obtained by mixing TiO ₂ powder at a composition ratio (weight ratio) of 68:32 and adding a binder. and B were respectively coated and fired at a heating temperature of 1700° C., but in both cases the bonding strength of the metallized layer was as low as 0.8 Kgf/mm ² or less.
Moreover, the surface resistance was approximately 200 mΩ/□. Examples 6 to 25 Metallizing compositions were prepared using the compounding ratios shown in Table 1, and then metallizing pastes were prepared in the same manner as in Example 1. Using these metallizing pastes, the ceramic substrates A and B used in Examples 4 and 5 were coated in the same manner as in Example 1 using the combinations shown in Table 2, and heated at the firing temperatures shown in Table 2. A metallized layer was formed. As shown in Table 2, the bonding strengths of the obtained metallized layers all showed large values. Furthermore, the electrical resistance was also excellent. Furthermore, for each ceramic substrate, -55℃
After 1000 cycles of a heat cycle test with one cycle ranging from ~room temperature to 150°C, the bonding strength was measured in the same manner, and as shown in Table 2, there was almost no decrease in the bonding strength.

【table】

【table】

[Table] [Effects of the Invention] As is clear from the above examples, according to the present invention, the bonding strength of the conductive metallized layer is large and there is little variation, and moreover, the high melting point metal is contained in 90% by weight of the metallized layer. Surface conductive ceramic substrates with significantly improved electrical properties, reduced residual stress due to a smaller difference in coefficient of thermal expansion between the ceramic substrate and the metallized layer, and improved reliability. can be provided. In addition, since the metallized layer can be formed at a much lower firing temperature than conventional methods, it is possible to prevent the substrate from warping, thereby providing advantages such as reducing manufacturing costs and making the manufacturing process more continuous. Furthermore, it is now possible to form a conductive metallized layer with sufficient strength even on a high-purity nitride-based ceramic substrate with few grain boundary constituent phase components, in other words, a ceramic substrate with high thermal conductivity.
Therefore, it becomes possible to mount a high output chip in a small module.

[Claims]

1. A printed wiring board in which a conductor circuit and a plating resist which is formed other than the conductor circuit and also serves as an insulating layer are formed to have substantially the same thickness, and a resistor is formed between the conductor circuits, At least the following
1. A method for manufacturing a printed wiring board with a resistor, the method comprising manufacturing through steps including (a) to (e). (a) A step of forming an adhesive layer on the surface of the base material, which is made by dispersing heat-resistant resin fine particles that are soluble in an oxidizing agent and have been cured in advance in a heat-resistant resin. (b) Roughening the adhesive layer with an oxidizing agent. (c) A step of forming a plating resist on the roughened adhesive layer by exposing and developing it. (d) A process of applying electroless plating on the adhesive layer on which no plating resist is formed to form a conductor circuit with approximately the same thickness as the plating resist. (e) A step of forming a resistor by depositing a resistor paste at predetermined positions between the conductor circuits and heating and curing it.

Claims (1)

1. A method for producing a surface conductive ceramic substrate, which comprises firing at a temperature below 0.degree. C. to form a conductive metallized layer. 4 26 to 90% by weight of Mo and/or W,
5 to 70% by weight of an oxide of a group A active metal, V,
1. A metallizing composition for a nitride-based ceramic substrate, comprising 2 to 20% by weight of a compound of at least one element selected from Cr, Mn, Fe, Co, and Ni. 5 Mo and/or W at 26 to 90% by weight,
5 to 70% by weight of an oxide of a group A active metal, V,
2 to 20% by weight of a compound of at least one element selected from Cr, Mn, Fe, Co and Ni;
1. A metallizing composition for a nitride-based ceramic substrate, comprising 2 to 15% by weight of a compound of Ca and/or Ca.