RU2336249C1 - Paste for metallisation of dielectric materials and products from them - Google Patents

Abstract

FIELD: chemistry, electricity.

SUBSTANCE: claimed is paste for metallisation of dielectric materials based on molybdenum, manganese and cake of aluminium, calcium, magnesium, silicon, titanium, barium, iron oxides, with the following ratio of components, wt %: molybdenum 50-65, manganese 10-5, cake 40-3.

EFFECT: enhancing quality of metal coating and duration of operating terms at these temperatures.

5 ex, 1 tbl

Description

The invention relates to chemistry and metallurgy, and in particular to pastes for metallization of dielectric materials and products from them, and can be used in radio engineering, instrumentation, nuclear and other fields of technology, where products based on dielectric materials can be used, especially in technology Microwave

The main requirements for metallized dielectric products are:

- high mechanical strength

- vacuum density

- high heat resistance,

- high operating temperature and duration at this temperature without violating their strength and heat resistance.

The essence of metallization with pastes is to apply the paste to the surface and then burn it.

Today known pastes for metallization of dielectric materials are made on the basis of refractory metals and metal oxides and non-metals. In the process of burning pasta, a glass phase forms, which has one or another viscosity.

The glass phase present in the metallization coating must have optimal viscosity.

Since its presence with high viscosity allows you to work:

- firstly, with high temperature solders,

- secondly, at high temperatures and for a long time without violating the integrity of metallized dielectric products.

And its presence with low viscosity completely excludes the possibility of working with high-temperature solders, since even small temporary overexposure at high temperature during the soldering of metallized dielectric products leads to the displacement of the glass phase from the metallization coating by molten solder, as a result of softening of the joint and, consequently, a decrease in mechanical strength metallized dielectric products.

Known paste for the metallization of dielectric materials based on molybdenum and oxides of manganese, aluminum, calcium, silicon in the following ratio of components, wt.%:

manganese oxide 6.9-9.0 aluminium oxide 5.1-5.9 calcium oxide 4.2-4.8 silica 11.7-12.6 molybdenum the rest [1]

This paste is suitable only for soldering with low-temperature solders, since during the burning process, these oxides form a glass phase with low viscosity. And when soldering with high-temperature solders, for example, with copper, the glass phase is easily made from a metallization coating, which results in softening of the junction and, consequently, a decrease in the mechanical strength of metallized dielectric products.

Known paste for metallization of dielectric materials of VK94-1 ceramics is also based on molybdenum and sinter from VK94-1 ceramics itself, for which it is pre-crushed, in the following ratio of components, wt.%:

molybdenum 75-80 spec 25-20 [2]

This paste during the burning process forms a small amount of glass phase with a high viscosity, which allows it to be used when soldering with high-temperature solders and with a sufficiently long operating time at these temperatures.

Moreover, molybdenum and VK94-1 ceramics have close coefficients of thermal expansion, which ensures low stresses in the joint and, therefore, high mechanical strength of metallized dielectric products.

However, the burning of a metallization coating based on this paste requires high temperatures of the order of 1450-1550 ° C, at which deformation is observed when large-sized thin-walled dielectric products are used for metallization.

Known paste for the metallization of dielectric materials, also based on molybdenum and cake of aluminum and calcium oxides, in the following ratio of components, wt.%:

molybdenum 65-95 spec 35-5 - prototype [3]

The advantage of this paste over the previous one is the reduction of the burning temperature from 1450-1550 ° C to 1400-1420 ° C, which is essential both for the metallization process of products made of dielectric materials and their subsequent operation.

However, the burning temperature remains high enough, which is completely unacceptable for the metallization of large-sized products made of dielectric materials, since they are deformed.

The technical result of the invention is to improve the quality of the metallization coating, by increasing the mechanical strength, ensuring vacuum density at high operating temperatures and the duration of the work at these temperatures.

The specified technical result is achieved by using a paste based on molybdenum and sintered metal oxides of aluminum and calcium, while the paste additionally contains manganese, in the following ratio of components, wt.%

molybdenum 50-65 manganese 10-5 spec 40-30,

and the spec additionally contains oxides of magnesium, silicon, titanium, barium, iron, with the following ratio of components in it, wt.%

aluminium oxide 52-48 calcium oxide 22-20 magnesium oxide 4-2 silica 17-22 titanium oxide 1.2-0.8 barium oxide 3-6 iron oxide 0.8-1.2

The presence of additional manganese in the paste, and in the cake of oxides of magnesium, silicon, titanium, barium, iron, will allow:

First, reduce the burning temperature to 1350 ° C.

The presence of manganese in combination with oxides of calcium, aluminum and magnesium made possible the formation of a glass phase, which

a) partially crystallized, and, therefore, it is not displaced from the metallization coating during brazing with high-temperature solders,

b) has a high viscosity, and as mentioned above, this will allow working with high-temperature solders and for a long time without violating the integrity of metallized dielectric products.

Secondly, the presence in the cake of oxides of silicon, titanium, barium and iron leads to:

a) to obtain a glass phase with a thermal expansion coefficient close in value to the thermal expansion coefficients of molybdenum and dielectric material, which in turn provides a reduction in stresses at the interface of the metallization coating - dielectric material and, consequently, an increase in the mechanical strength of the metallization coating,

b) to increase the wettability of the glass phase, which ensures its uniform distribution between the molybdenum grains and improves the wettability of the dielectric material with it and, therefore, the quality of the metallization coating.

Thus, the proposed paste for metallization of dielectric materials, on the one hand, will reduce the burning temperature to 1350 ° C, and, on the other hand, will allow it to work at higher temperatures of about 1100 ° C, which is especially important when used in microwave technology.

Example 1

The proposed paste was used for metallization of VK94-1 ceramics.

The technological process includes:

- preparation of cake, for which they mix the components of cake composition and amount corresponding to the average values specified in the claims, followed by heat treatment in air at a temperature of 1300 ° C for two hours. Next, grind the cake;

- preparation of the actual paste for metallization, for which molybdenum is milled, then molybdenum, manganese, cake and binder powders are mixed, which is used as a solution of nitrocellulose in isoamyl acetate.

Examples 2-5

Analogously to example 1, pastes for metallization were prepared, but with other quantitative values of the components, both indicated in the claims (examples 2-3), and beyond it (examples 4-5).

The prepared paste compositions for metallization are applied by rotational printing on the surface of products made of VK94-1 ceramics with a coating thickness of 65 ± 5 μm, followed by annealing in a hydrogen furnace in a humidified atmosphere with a dew point temperature of + 25 ° C a mixture of nitrogen and hydrogen gases when they are 2: 1 ratio, respectively, at a temperature of 1350 ° C for 30-60 minutes.

Next, these products are soldered, for which nickel 3 microns thick is applied to their metallized surfaces.

Then, the indicated products are brazed, for which purpose nickel 3 microns thick is applied on the metallized surfaces by a galvanic method, and then the products are brazed with copper solder with 29NK insidious.

After soldering, the samples were transferred for testing for:

- mechanical strength, through bending and tearing,

- vacuum density leak detector immediately after soldering and then according to OST 11.332.702-83.

The test results are presented in the table.

As can be seen from the table, samples of ceramic products VK94-1, metallized by the proposed paste (examples 1-3), passed all types of tests, unlike the sample of the product (example 4), in which the junction was not obtained at all due to the insufficient amount of molybdenum in the composition of the paste and the excess amount of oxides in the cake, and the product sample (example 5), in which there is a decrease in the order of 50 and 25 percent of mechanical strength and vacuum density, respectively.

The same results as in example 5 are observed in the prototype.

Thus, the proposed paste for metallization of dielectric materials and products from them will allow, in comparison with the prototype, to improve the quality of the metallization coating.

At the same time, mechanical strength and vacuum density are increased by 50 and 25 percent, respectively.

And this is in conditions of elevated operating temperatures of about 1100 ° C and a duration of about 5 minutes or more at these temperatures during operation of these products, which is especially important when using these products in microwave technology.

No. p \ p The composition of metallization paste Test results Mo Mn spec Mechanical strength, MPa average Vacuum density,% σ _{mfd separation} σ after soldering after testing according to OCT 11.332.702-83 one 57 8 35 180 80 one hundred one hundred 2 fifty 10 40 170 70 one hundred one hundred 3 65 5 thirty 160 70 one hundred one hundred four 45 13 42 junctions not received junctions not received junctions not received junctions not received 5 70 four 26 120 45 one hundred 75 prototype 75 - 25 130-140 No data one hundred 70

Information sources

1. USSR author's certificate No. 514797, IPC 41B 41/14, bull. No. 19, 1976

2. P. N. Ermakov, N. T. Andrianov and others. The influence of some factors on the quality of metallization coatings of VK94-1 ceramics. // Electronic Engineering, ser. 14. Materials, issue 1, 1982

3. USSR author's certificate No. 429714, IPC С04В 41/88, bull. No. 18, 1974

Claims (1)

Paste for metallization of dielectric materials and products from them based on molybdenum and sinter of metal oxides of aluminum and calcium, characterized in that the paste additionally contains manganese in the following ratio of components, wt.%: molybdenum 50-65 manganese 10-5 spec 40-30, wherein the cake additionally contains oxides of magnesium, silicon, titanium, barium, iron in the following ratio of components in it, wt.%: aluminium oxide 52-48 calcium oxide 22-20 magnesium oxide 4-2 silica 17-22 titanium oxide 1.2-0.8 barium oxide 3-6 iron oxide 0.8-1.2