JPS6130366B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a metallizing composition for forming a conductive metal layer on an alumina ceramic substrate. Conventional metallizing compositions include metal powder and glass frit. The metal powder includes W metal powder alone, Mo metal powder alone, a mixture of W metal powder and Mn metal powder, and Mo metal powder and
Mixtures with Mn metal powder are most commonly used. In recent years, in the manufacture of wiring boards, a technology has been developed in which sintering of ceramic and formation of a conductive metal layer are performed by simultaneous firing in a humidified reducing atmosphere. However, while humidification has the effect of promoting the decomposition of the organic binder and the bonding between the metal layer and the ceramic layer, depending on the humidification conditions, the metal may be excessively oxidized.
This has the disadvantage of increasing the electrical resistance of the conductive metal layer and decreasing the sinterability of the conductive metal layer. Therefore, the present invention has been made to eliminate such drawbacks, and provides a metallizing composition that can prevent oxidation of metal powder due to changes in humidification conditions, and thereby prevents the sintering phenomenon between metal particles. The purpose is to promote the electrical resistance of the conductive metal layer and to reduce the electrical resistance of the conductive metal layer. In order to form a conductive metal layer on an alumina ceramic substrate, the metallizing composition according to the present invention contains one or more of W, Mo, and Mn metal powders in a total amount of 80 to 99% by weight, carbon powder is 0.01
~1% by weight, the same composition as the alumina ceramic substrate, characterized by a total of 0.99~19% by weight of one or both of calcined powder and glass frit, and the same composition as the metal powder, carbon powder, and alumina ceramic substrate. It is characterized in that the average particle size of the calcined powder and/or glass frit is 0.1 to 5 μm. The carbon powder acts as a strong reducing agent, controlling oxidation of the metal powder due to excessive humidification during firing in a humidified non-oxidizing atmosphere. Further, the calcined powder of the base alumina ceramic substrate raw material is added for the purpose of contributing to adhesion between the conductive metal layer and the substrate. The purpose of calcination is to prevent phase separation of the low-density oxide raw material in the metallizing paste. Furthermore, since glass frit is added for the purpose of contributing to adhesion between the conductive metal layer and the substrate, the type of glass frit used is particularly limited as long as it is compatible with this purpose and has a softening temperature of 600°C or higher. Not done. The content and average particle size of the carbon powder, calcined powder, and glass frit in the above composition may vary within the above range depending on the type, particle size, amount, and firing temperature of the metal powder contained in the composition. can be taken. Incidentally, when the total amount of one or more of W, Mo, and Mn metal powders is less than 80% by weight, the sheet resistance value increases. On the other hand, if the amount exceeds 99% by weight, the surface adhesion strength of the electrode will decrease. Furthermore, if the carbon powder content is less than 0.01% by weight, the sheet resistance value of the electrode increases depending on the humidification conditions, and the surface adhesion strength also decreases. On the other hand, 1% by weight
If the amount is more, the strength of the electrode film decreases. moreover,
Base alumina ceramic substrate raw material calcined powder, glass frit, or the total of both is 0.99% by weight
When the amount is less than 19% by weight, the surface adhesion strength of the electrode decreases, and when it is more than 19% by weight, the sheet resistance value increases. Furthermore, if the average particle size of the metal powder, carbon powder, calcined powder, or glass frit is less than 0.1μ, the purity of the powder will decrease and the cost will increase. On the other hand, if it is larger than 5μ, the sinterability of the electrode decreases in the case of metal powder, and the sheet resistance value increases due to segregation of carbon particles in the case of carbon powder. In the case of calcined powder or glass frit, the sinterability of the electrode decreases, the sheet resistance increases due to segregation, and the surface adhesion strength decreases. By using carbon powder as described above, the present invention has completed a new and excellent metallizing composition. Hereinafter, the present invention will be specifically explained with reference to Examples. First, W, Mo, and Mn powders are commercially available with an average particle size of
Glass frit powder was commercially available Al ₂ O ₃ -SiO ₂ - with a softening point of 1100°C.
MgO--MnO ₂ glass frits with average particle sizes of 0.1, 1, 5, and 10 μm are used in a ball mill. In addition, the unsintered raw alumina ceramic sheet for printing is an industrial raw material (purity of 98% or more).
Al ₃ O ₃ 96% by weight, SiO ₂ 3% by weight, MgO 0.5
% by weight, CaO is mixed to a composition ratio of 0.5% by weight, and made into a raw alumina ceramic sheet using a known technique. The base alumina ceramic substrate raw material calcined product is made by mixing 1300% raw material powder with the above composition ratio.
Calcinate at ℃ and use a ball mill to reduce the average particle size to 0.1.
These are powders with sizes of 1, 5, and 10μ. The composition ratio and average particle size of such a metallizing composition are shown in Table 1 below. A metallizing paste is obtained using the composition. The metallizing paste was printed on the unsintered alumina ceramic sheet, the binder was removed in the atmosphere, and then the paste was heated at 1500°C to 1600°C in a moist green gas with a dew point (dp) of 0°C to 40°C. Let's do it. Using the metallized substrate thus obtained, various properties as shown in Table 2 below were investigated.

【table】

【table】

[Table] As is clear from Tables 1 and 2, Examples No. 1 to No. 5 are within the scope of the present invention, and the others are comparative examples outside the scope. The samples within the range of the present invention exhibit excellent properties in terms of surface resistance, surface adhesion strength, and degree of sintering. Further, properties outside the scope of the present invention are poor. In this example, the degree of sintering was determined from the degree to which the electrode film was scratched with a knife and the specific resistance value of the electrode film. Further, in general, it is desirable that the sheet resistance value of the electrode portion of the wiring board is 20 mΩ/□ or less, and the surface adhesion strength is preferably 5 Kg/mm ² or more. As described above, the metallizing composition of the present invention has
It has extremely excellent performance as an electrode material for wiring boards, is extremely stable in industrial mass production, and has great industrial value.

Claims (1)

[Claims] 1 In order to form a conductive metal layer on an alumina ceramic substrate, one or two types of W, Mo, and Mn metal powders are used.
Total content of seeds and above is 80-99% by weight, carbon powder is 0.01-1%
% by weight, one or both of calcined powder and glass frit having the same composition as the above alumina ceramic group, and a total of 0.99 to 19% by weight, and each of the above powders and glass frit has an average particle size of
A composition for metallization, characterized in that it has a thickness of 0.1 to 5μ.