RU2755344C1 - Method for obtaining thick-film structures for thermal power generators - Google Patents

Abstract

FIELD: electronic technology.

SUBSTANCE: invention relates to electronic technology, and specifically to the production of thick-film structures based on samarium monosulfide, which can be used in the production of thermal power generators (TPG). In the proposed method, a resistive layer is applied in the required proportions from a mixture of the first resistive paste and the second paste containing samarium monosulfide (SmS) particles, while the applied layers are burned in two cycles at a temperature of 750-850°C for 50 minutes, in 7-10 minutes of which the burning is carried out at the maximum temperature, and at a temperature of 820-1200°C for 50 minutes, in 10-20 minutes of which at the maximum temperature.

EFFECT: increasing the yield of suitable TPG structures with a high efficiency coefficient on the contact pads of the conductor layer.

1 cl, 1 dwg

Description

The invention relates to electronic engineering, namely the production of thick-film structures based on samarium monosulfide (SmS). Semiconductor materials based on samarium monosulfide are promising for the creation of n-type thermoelectric generators (TEG). The invention can be used in electronic, radio engineering, nuclear industry, medicine and other industries

State of the art

There is a known method of manufacturing thick-film resistors, protected by the patent [1], according to which the resistor is made by traditional methods of thick-film technology, including sequential screen printing on any substrate of conductive and resistive layers, drying and burning them in an air atmosphere at required temperatures, and first the first conductive layer is applied. Glass or glass-ceramic composition contained in the resistive layer contains substances capable of reduction (transition metal oxides in the highest oxidation state or their compounds). As a result of their recovery during firing, an electrically conductive phase is formed in the resistive layer.

The disadvantage of this method is the low efficiency of the thermoelectric generator.

There is a known method of manufacturing precision chip resistors using hybrid technology, protected by a patent [2], which includes sequential formation of electrode contacts on an insulating substrate based on thick-film technology. Based on thin-film technology, a resistive layer is formed, followed by breaking the insulating substrate into chips. First, a layer of silver or silver-palladium paste is applied to the ground (back) surface of the insulating substrate by screen printing, followed by its firing, thereby forming electrode contacts on the back side of the substrate. Then, a resistive layer is sprayed onto the polished (front) side of the insulating substrate using the vacuum (thin-film) technology, the topology of the resistive layer is formed on the substrate by photolithography and ion etching, after which a layer of low-temperature silver paste with its subsequent firing, thereby forming electrode contacts on the front side. Further, by the method of laser trimming, the value of the resistance of the resistors is adjusted to the nominal value. Then, by the method of screen printing, a layer of low-temperature protective paste is applied to the resistive layer, followed by burning in a layer of low-temperature protective paste, forming a protective layer, scribing and breaking the plate of the insulating substrate into rows (strips). Using the method of vacuum (thin-film) technology from an alloy of nickel with chromium, the end layer is sprayed onto the highlanders of the rows, while electrically connecting the electrode contacts of the front and back sides of the substrate, breaking the rows onto chips, electroplating over the electrodes - front, front and back the sides - a layer of nickel, and a layer of solder (tin-lead alloy) is applied over the nickel layer by the galvanic method.

The disadvantage of the analogue is a large number of technological operations both in thin-film and thick-film technologies, which makes its technical implementation laborious.

Closest to the claimed technical essence and the achieved result, selected as a prototype, is a method of manufacturing thick-film resistive elements, protected by a patent [3].

This method of manufacturing thick-film resistive elements includes sequential screen printing of conductive and resistive layers on an insulating substrate and firing in an air atmosphere.

The method alternates the application of a conductive layer with burning it into separate sections of the insulating substrate, at a temperature of 840-860 ° C for 55 ± 5 minutes, then applying a resistive layer, and burning it at a temperature of 805 ± 2 ° C for 70 ± 5 minutes, then the rating of the resistive elements is monitored, if the nominal is overestimated, the adjustment is carried out at a temperature of 820 ± 10 ° C for 5-10 minutes, and if the nominal is too low, at a temperature of 690 ± 10 ° C for 5-10 minutes, then tinning is performed in molten solder by dipping at a temperature of 250 ± 10 ° С

FIG. 1 shows an insulating substrate with conductive and resistive layers.

An insulating substrate with conductive and resistive layers consists of an insulating substrate 1 with ends 2, 3, and planes 4, 5. Thick-film resistors are manufactured according to the proposed method as follows: conductors and resistors are made by screen printing. On the insulating substrate 1 (ends 2 and 3 and planes 4 and 5), a conductive paste, for example, silver-palladium, is sequentially applied. After each application, they are burned in air at a temperature of 850 ° C for 50 minutes. Then a resistive, for example, ruthenium paste 6 is applied and burned in air at a temperature of 805 ° C for 70 minutes.

The disadvantage of this method of thick-film resistive elements is an insufficiently high yield of suitable suitable elements of a heat-electric generator, associated with a large number of technological operations

Technical challenge

The technical result is an increase in the yield of suitable resistive elements of a heat-electric generator with a high efficiency due to an increase in the controllability of the technological process

Solution

To solve the technical problem posed, the following invention is proposed:

A method of manufacturing thick-film structures based on samarium monosulfide (SmS), including sequential screen printing of a conductive layer and a resistive layer on an insulating substrate, characterized in that a resistive layer is applied to the contact pads of the conductive layer from a mixture in the required proportions of the first resistive paste and the second paste containing particles of samarium monosulfide (SmS), while the deposited layers are fired in two cycles at a temperature of 750 - 850 ° C for 50 minutes, 7-10 minutes of which the firing is carried out at a maximum temperature, and at a temperature of 820 - 1200 ° C in within 50 minutes, 10-20 minutes of which are fired at maximum temperature.

The main advantage of the method is that it is possible for them to create sufficiently thick layers of samarium sulfide structures (up to 200 μm), and a large volume of the working substance (a layer with a thickness of more than 1 μm) determines a higher power of the generated signal than in sulfide-samarium structures obtained using thin film technology.

An insulating substrate (for example, a ceramic plate) is used as the basis for the manufactured elements of heat and power generators. By screen printing, conductive layers are formed on the surface of the wafer using conductive pastes. A paste containing particles of samarium monosulfide is applied to the formed contact pads and between them, on the basis of which resistive elements of a heat-electric generator will be formed. Samarium monosulphide resistors are formed by mixing a standard resistive paste with samarium monosulphide paste, drying to remove the volatile component, and two firing cycles at different temperatures. The firing mode includes heat treatment in the temperature range 750 - 850 ° C for 50 minutes, 7-10 minutes of which are carried out at the maximum temperature, the second firing cycle lasting 50 minutes in the temperature range 820 - 1200 ° C, 10-20 minutes of which are carried out at maximum temperature.

All layers are applied by screen printing. First, the first layer is applied - conductive, to create contacts and burn this layer.

Then, a resistive layer is applied to the obtained contact pads from a mixture in the required proportions of the first resistive paste and the second paste containing particles of samarium monosulfide (SmS), while the deposited layers are fired in two cycles at a temperature of 750 -850 ° C for 50 minutes, 7 - 10 minutes of which the firing is carried out at the maximum temperature, and at a temperature of 820 - 1200 ° C for 50 minutes, 10-20 minutes of which the firing is carried out at the maximum temperature.

Example.

The parameters of the obtained heat and power generators (TEG) were monitored using a massive heated copper plate. Heating was carried out using an industrial hair dryer to a temperature of 135 ° C. Temperature control was carried out using copper-coistantane thermocouples embedded in the volume of the plate so that it was possible to evaluate the uniformity of the temperature distribution of the sample under study. In the experiments carried out, the temperature uniformity was within 1 ° C.

To measure the parameters obtained by the TEG, the signal from the contacts of the device through the ADC was output to a computer and statistical processing of the measurement results was carried out. The voltage generated by the TEG was 35 ± 1 mV, and the power at a load of 1 Ohm was 175 ± 5 μW. The reproducibility of the process was checked by measuring the TEG parameters for 20 days, evaluating the standard deviation of the results according to the standard method of statistical processing of the measurement results.

For comparison, a thermoelectric generator was manufactured according to the prototype method. As a result of comparative tests, it was determined that the reproducibility of the parameters of the TEG manufactured by the proposed method exceeded the reproducibility of the parameters of the TEG manufactured by the prototype method by at least 7 times. The yield of suitable devices that have passed life tests exceeded 90%, which exceeded the same indicator for the prototype method by 25 - 30%.

Literature

1. Patent RU 2086027, cl. Н01С 17/06, publ. 07/27/1997

2. Patent RU 2402088, cl. Н01С 17/06, publ. 20.10.2010

3. Patent RU 2497217, cl. Н01С 17/06, publ. 27.10.2013

Claims (1)

A method of manufacturing thick-film structures based on samarium monosulfide (SmS), including sequential screen printing of a conductive layer and a resistive layer on an insulating substrate, characterized in that a resistive layer is applied to the contact pads of the conductive layer from a mixture in the required proportions of the first resistive paste and the second paste containing particles of samarium monosulfide (SmS), while the deposited layers are burned in two cycles at a temperature of 750-850 ° C for 50 minutes, 7-10 minutes of which the burning is carried out at a maximum temperature, and at a temperature of 820-1200 ° C in within 50 minutes, 10-20 minutes of which are fired at maximum temperature.

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