SU1338726A1 - Multiple-element thermoelectric transducer - Google Patents

Description

(46) 07.02.90. BCS. № 5

(21) 4012395 / 31-25

(22) 01/23/86

(71) Institute of Electronics, Academy of Sciences of the BSSR

(72) Yu.I. Gorbachev, I.L. Grigorishin and Yu.M. Gulyuk

(53) 621.362.2 (088.8)

(56) Gurevich M.M. and others. Automated device for accurate measurement of wide-axis voltages. Communications equipment. Seri Radio measurement technique. Issue 1 / 25-, 1979,

with. 102-108.

USSR Author's Certificate No. 1187662, cl. H 01 L 35/02, 1983.

(54) MULTI-ELEMENT THERMOELECTRIC CONVERTER

(57) The invention relates to thermoelectric instrumentation, more specifically to thermoelectric

variable voltage transducers. In a wide frequency range in terms of the root-mean-square value to a constant. The aim of the invention is to improve the accuracy of the conversion of the converter at high frequencies. This goal is achieved by placing the conductive layer placed between the heater and hot thermopile junctions separated along the axis of symmetry of the heater, which is perpendicular to the sides of the heater, into two equal parts, which are galvanically connected to the output thermopaths of the thermopile thermocouple by means of a dielectric extruded on the surface. film conductor substrates. As a result, the conversion accuracy at high frequencies (100 MHz) was 20 times higher, 2 times. The invention relates to a thermoelectric instrument making industry and can be used in alternating voltage converters and in a wide frequency range from the level of a mean CEI value to a constant value. The aim of the invention is to increase the accuracy of the conversion at high frequencies (KFK). 1 shows the proposed thermoelectric multi-element transducer (TEC); in fig. 2 to clarify the principle of operation. TEC at high frequencies is an equivalent circuit showing the relationship between the heater, the conductor layers and the thermopile. The converter contains a dielectric substrate 1, on one of the surfaces of which a film resistive heater 2 is placed, and on the opposite side - conductive layers 3 and 4 and a thermopile consisting of thermocouples, whose branches 5 and 6 have different: different thermoelectric properties:. The hot junctions 7 of the thermocouples are located above the heater 2. The layers 3 and A are placed between the heater 3 and the thermal battery and are separated from it by a film dielectric layer 8 The connecting helix conductors 9 and 10 are placed on the surface of the substrate 1 and are extensions of the respective wires Layers 3 and 4. Heater 2 and thermopile have film contact pads 11 Layer 3 is connected using conductor 9 with one thermopile pole, and layer 4 is connected with a probe. 10 - with the opposite. The 12-thermopair cold junctions are located on the surface of the substrate 1 on either side of the heater 2. In the diagram (see Fig. 2), the resistors (R. ..R,) are the resistive portions of the heater 2 located near the corresponding hot spots of 7p the number of thermocouples of the capacitance (s, .., C) and (C ...) of the capacitance between the 7 thermocouple sections of the conductor layers 3 and 4, located under the hot L1 springs, and the heater 2, respectively; and 4 corresponding elements (ТП,.,. ТТ1 - thermocouples that are part of the thermopile. By design to the characteristics of this TEC, the values of all the resistors indicated on the circuits (R ... R ,,,) are equal to each other, and all indicated capacitances are equal in magnitude to each other not only separately in each of the groups (C) ... C „ ) and (C ...), but also in their totality. In addition, in terms of their electrophysical parameters and functional abilities, the elements of PS and PS, as well as the elements (TP ... TP), are equal. At high frequencies applied to the points a and b of the electric circuit of the alternating voltage i U, the high-frequency leakage currents arising in it through the capacitances (C: .. C) and (C | ... o. C) are completely closed in the corresponding elements and flCj,, do not penetrate into thermocouples (TP .., TP). At the same time, equal high-frequency electric potentials are induced on the surfaces of the PS elements. The same high-frequency potential, which in the case when, points c and d are not connected to the proposed measuring circuit, is equal to / 2, due to the galvanic connection of the PS and PS elements with the TPJ and TP elements, and also the entire surface of the elements ( ТП ,,, -. .ТШ /,), When connecting points c and d to the measuring circuit (preference should be given to symmetrical input circuits that do not require any of these points to be connected to the housing or to the ground wire, for example, based on differential amplifiers with the two differential inputs, the induced high-frequency potentials at the specified points are supplied, followed by the corresponding potentials jia. of the entire surface of the elements (TP., TP), PS and PS, however, the reduction of high-frequency potentials on the surfaces of all marked elements occur by the same and the same magnitude, i.e., with the total surface of the elements of the PS, PS and (TP ... TSH) practically remains under the same high frequency potential, is equivalent, , equipotential. Significantly reduce the high-frequency interconnection between the TEC and the measuring circuit, and also exclude the penetration of high-frequency pickups from the TEC to the specified circuit

It is possible by applying a differential amplifier with high impedance across the inputs and using, for example, simple blocking filters or low-pass filters at its inputs.

An example of a specific implementation. On one of the surfaces of the dielectric substrate 1 made of aluminum oxide or mica with dimensions of 8x4.5x0.03 mm, films of a thickness of 0.8 µm of resistive material (X20H80 nichrome or kermet K50C) are deposited at the location of the heater 2 and a film of 0.6 µm thick specific electrical conductivity (nickel NI in copper MB or silver Ag 999.9) in the location of the contact pads 11 of the heater 2. On the opposite surface of the dielectric substrate 1, films of 0.6 μm thick material with high conductivity are deposited (nickel NP1v, MB or Ag 999.9 silver) in the locations of conductive layers 3 and 4 of connecting conductors 9 and 10 and thermopile contact pads 11, as well as films (0.5-0.9 microns) forming branches 5 and 6 of thermocouples, from various heat-sensitive materials (bismuth-antimony or lead telluride-germanium telluride). Prior to the deposition of branches 5 and 6 of thermocouples on top of the conductive layers 3 and 4, a film layer 8 is deposited with a thickness of (0.5-1.0) μm from a dielectric material (alumina, silica or titanium oxide). Hot junctions 7 and cold 12 thermocouples are formed by sequential deposition of films of heat-sensitive materials with an overlap. The heater, which has a geometrical dimensions of 4.55x0.2 mm, is in thermal contact with 30 thermocouples, each branch of which has geometrical dimensions, 1 mm. The gap between the branches of two adjacent thermocouples is 0.05 mm. The resistance of the heater to a direct current is 75 Ohms, and the total resistance of the thermopile consisting of thermocouples connected in series does not exceed 10 kΩ. At a specified substrate thickness (30 µm) of alumina, the total capacitance between the heater and the two conductors

Claims (1)

In other words, it has a size of about 2 pf. In the proposed TEC, the input capacitance value is not more than 0.5 pF, which, all other things being equal, is 5 times less than that of the prototype TEC and is determined mainly by the parasitic capacitances of external current connectors to the heater, since the total capacity of the heater and its contact pads has a size of about 0.03 pF. The table shows the calculation results taking into account the effect of the input capacitances of the Z and Z modules, j of the complex resistance Z and нагрев of the heaters, respectively, for the proposed TEC and CHP in the prototype, as well as the errors of the Z and Z modules for different frequencies applied to variable heaters wives As the results of the calculation show, in the proposed TEC, at a frequency of 100 MHz, the error due to the change in the impedance of the heater due to the effect of the input capacitance is 0.03%, and at frequencies up to 600 MHz inclusively does not exceed 1%. Compared with the prototype, at high frequencies of the working range (for example, at 100 MHz) the indicated error is reduced, i.e. conversion accuracy is increased not less than 23 times. Claims of the invention A multi-element thermoelectric converter comprising a dielectric substrate, on the surface of which are film films separated by dielectric layers, a symmetric resistive heater with contacts on two mutually opposite and perpendicular to its axis of symmetry, a thermocouple consisting of thermocouples, and located between the heater and its A thermopile with a conductive layer, characterized in that, in order to improve the accuracy of conversion at high frequencies The conductive layer is separated along the symmetry axis of the heater into two equal parts, which are galvanically connected to the output branches of the thermocouple end thermocouple using film conductors made on the surface of the dielectric substrate. but