Thermoanalytical sensor and method for its production

The invention relates to a thermoanalytical sensor having a substrate, through which a heat flow between a to the substrate thermally coupled heat source and at least one measurement position formed on the sensor can be conducted, and with a groove formed on a substantially planar surface of the substrate thermocouple assembly for the supply a thermoelectric signal, and to a method for producing such a sensor.

Such thermal analytical sensors are used, physical and / or chemical properties of a substance, a substance mixture and / or reaction mixtures are subjected to a controlled temperature program, to measure as a function of temperature or time. Well-known examples are the Wärmestromdifferenzkalorimetrie and Leistungskompensationsdifferenzkalorimetrie. In these two cases, the analysis of a sample is done relative to a reference sample, and therefore the sensor is in these cases, having two measurement positions, which serves one of the detecting of the sample and the other of the detection of the reference sample. In the former case, the thermoelectric signal delivered by the thermocouple arrangement, a measure of the difference between the heat flow to the sample and the reference sample. In the second case the current supplied by the thermocouple assembly thermoelectric signal is used to regulate the heat flow to the sample and the reference sample in such a way that the temperature difference between the sample and the comparison sample is regulated to zero.

The thermoanalytical sensors are possible over the entire temperature range of the analysis have a very high sensitivity, so depending on the heat flow a thermoelectric signal highest possible voltage supply. This is a good signal-to-noise ratio is obtained. Therefore, in known thermoanalytical sensors (<patcit id="pcit0001" dnum="DE3916311C2"><text>DE 39 16 311 C2</text></patcit> and <patcit id="pcit0002" dnum="EP0990893A1"><text>EP 0990893 A1</text></patcit>) A number of thermocouple junctions of the thermocouple assembly connected together such that sum the individual thermal stresses in the thermoelectric signal. The relevant thermal contacts of the thermocouple arrangement are arranged in a circle around the center of the measurement position and the centers of the measuring positions around in the smallest possible mutual azimuthal distance so that in these known configurations, increasing the number of thermal contacts for lack of space is no longer possible.

The invention is based on the object at a thermoanalytical sensor of the aforementioned type, the sensitivity continues to increase and to provide a method for manufacturing such a sensor.

According to a first aspect of the invention, the above-mentioned object in a thermoanalytical sensor having a substrate, through which a heat flow between a to the substrate thermally coupled heat source and at least one measurement position formed on the sensor can be conducted, and with a on a substantially planar having surface of the substrate formed thermocouple assembly for providing a thermoelectric signal that one of the measuring position assigned series of connected in a circuit arrangement with one another, composed of two different thermocouple materials thermal contacts according to the invention is achieved in that the thermal contacts are arranged in at least two superimposed and respectively by an insulating layer from each other arranged separate planes in which each extend to form portions of the circuitry serving compounds the thermal contacts and corresponding ends of the sections to form the circuit arrangement are connected by via.

In this inventive solution thus the entire circuit arrangement is divided into at least two sections. By superposition of the individual sections belonging to the thermal contacts available on the sensor space according to the number of stacked layers is often used, whereby the circuitry may have a corresponding multiple of thermal contacts. Accordingly, the circuit arrangement provided by the total available thermoelectric signal can be increased and thereby the sensitivity can be increased.

Conveniently, this idea of ​​the invention is carried out such that are formed on the top with respect to the substrate plane connections to which the signal provided by the thermocouple assembly thermoelectric signal can be tapped off and one end of which is arranged in the bottom with respect to the substrate plane portion of the circuit arrangement is connected through plated-through hole with one of the terminals. The ability to tap the thermoelectric signal to the mounted on the top level connections, facilitates the installation and connection of the sensor in a serving for thermal analysis the entire device.

An advantageous embodiment is to switch the thermal contacts a portion of the circuitry behind the other and the portions interconnect in series with the circuit arrangement, so that a thermopile.

the thermal contacts are arranged such that they surround the azimuthal center of the measurement positions and alternately lie at different radial distances from the center preferably.

A further advantageous embodiment consists essentially form arranged in the different levels of sections circuitry congruent.

In a second aspect of the invention, the thermal analysis sensor is characterized with a substrate through which a heat flow between a to the substrate thermally coupled heat source and at least one measurement position formed on the sensor can be conducted, and formed with one on a substantially planar surface of the substrate thermocouple assembly for delivering a thermoelectric signal, comprising a series of a thermopile connected in series, composed of two different thermocouple materials thermocouple junctions which are the center of the measuring position azimuthally surrounded and arranged alternately at different radial distances from the center of the measurement position, according to the invention is characterized in that a third thermal contact and are provided in series to directly adjacent fourth thermal contact in at least one between a radially center the nearest first thermal contact and two immediately adjacent thereto in the row second thermal contacts azimuthally limited intermediate portion of the surface.

In the thermopile formed by this series connection of the series of thermal contacts thus exists between each two in the row immediately adjacent thermal contacts a radial distance. therefore A to the center of the measurement position through flowing or from the center of the measurement position outflowing heat flow caused due to the thermal resistance of the sensor is a temperature difference between the immediately adjacent each in series thermal contacts, which occur between these thermal contacts thermal stresses which add up due to the series connection. Therefore, the entire thermoelectric signal represents a sum of the thermal stresses occurring between the immediately adjacent in the series first and second thermocouple junctions and the thermal stresses occurring between the immediately adjacent in the series third and fourth thermocouple junctions. The two thermocouple materials may be the same for all thermal contacts. but obviously it is also possible to use a number of different pairs of thermal materials for forming the thermal contacts rather than a single pair of thermocouple materials. As each pair is arranged in the row directly adjacent third and fourth thermocouple junctions in the free intermediate area, which is limited in each case azimuthally between one of the first thermal contacts and the two to the immediately adjacent in the row second thermocouple junctions, the standing on the sensor available space best exploited in order to increase the total number of thermal contacts. The third thermal contacts can be arranged radially relatively close to the center of the radially nearest first thermocouple junctions, while the fourth thermocouple junctions can be arranged radially relatively close to the second thermocouple junctions. A serving for receiving a sample to be analyzed crucible can be dimensioned such that it covers at the measurement position with its base, the first and third thermal contacts, while exposed to the outside radially lying second and fourth thermocouple junctions. Thus, the thermocouple assembly detected particularly effective one occurring in the vicinity of the crucible radial temperature gradient, which corresponds to the information exchanged between the heat source and the crucible heat flux.

A particularly advantageous embodiment is configured such that the first thermocouple junctions on to a surrounding the center as the center of the first circle, the second thermocouple junctions on a concentric to the first circle second circle whose radius is larger than the radius of the first circle, the third thermocouple junctions a concentric to the first circle third circle whose radius is larger than the radius of the first circle and smaller than the radius of the second circle, and the fourth thermocouple junctions on a concentric to the first circle fourth circle whose radius greater than the radius of the third circle, lie. This embodiment takes into account the requirement of radial symmetry of the measuring point and the measuring point in relation to the center and this symmetry requirement corresponding conventional radially symmetrical design of the sample holder. Whose circular base is dimensioned such that their radius is greater than the radius of the third circle, but smaller than the radius of the second circle.

The approximation to a complete as possible radial symmetry, it is also appropriate that the thermocouple junctions are arranged on the respective circles are each at the same angle distance. It is in the sense of the fullest possible radial symmetry useful that the thermocouple material between each immediately adjacent in the series first and second thermal contacts extends in the form of straight strips and that located the thermocouple material between within the same intermediate region, in series in each case immediately adjacent third and fourth thermocouple junctions extends in the form of straight strips. The overall thermocouple arrangement in these cases has the appearance of a binary star, where two centered on the center of the measurement position individual stars are nested. The thus made good use of space allows a particularly large number of thermocouple junctions and a correspondingly high sensitivity of the sensor. Another advantage of this arrangement is that it can be extended by adding further nested stars as long as the radius of the circle of the inner thermocouple junctions of the outermost star is smaller than the radius of the circle of outlying thermal contacts of the innermost star.

For the purposes of radial symmetry, it is also appropriate that the thermocouple material between located in different intermediate regions, extending in series in each case directly adjacent third and fourth thermocouple junctions with a strip-shaped azimuthal section. This azimuthal section may take the form of a circular arc, whose related to the center of the measuring position radius is somewhat larger than the center related to the radial distance of the respective intermediate lying between the two areas of second thermal contact. In this case, an end portion of the arc immediately in the forming an intermediate region with the other thermocouple material the fourth thermal contact. From the opposite end portion of this azimuthal section is a radial section can extend to the third thermocouple junction located in the other intermediate area.

For the connection of the inventive thermoanalytical sensor to an evaluation circuit, it is expedient that are on the surface of the substrate with the two ends of the thermocouple column connected terminals at which the signal provided by the thermopile thermoelectric signal can be tapped, is formed. These ports can be configured for example in the form of flat pads or pads on which to the evaluation leading connecting wires can be connected.

Within the scope of the invention is provided in particular that on the sensor are designed as one of the measurement positions more. In particular, one of the measurement positions serve as a reference position, while the other measuring positions are used to hold samples. The reference position can either be empty or be provided with a known inert reference sample. For performing a differential scanning calorimetry delivered by the individual measurement positions thermoelectric signals can be connected together in such a way that in each case the difference signals between the reference position and the sample positions are obtained.

An important embodiment is characterized in that two of the measurement positions are formed on the sensor. Here, a measurement position as the reference position and the other measuring position serve as a sample position. This configuration corresponds to the skilled worker arrangements for performing the Wärmestromdifferenzkalorimetrie.

In an advantageous alternative embodiment, it is provided that on the sensor, four of the measurement positions are formed, of which the straight connecting line of the centers of a pair of the measurement positions is the mid-perpendicular to the line connecting the centers of the other pair of the measurement positions and vice versa. In this case, the centers of the four measurement positions are on the corner points of an imaginary square. This arrangement is advantageous in terms of the highest possible thermal symmetry of all measurement positions.

In the embodiments discussed so far, the thermocouple assembly of the sensor for detecting a current flowing between the measuring point and the heat source heat flow or a difference of different measuring points associated heat flows used. Moreover, for the thermal analysis, embodiments of the invention, an advantage in which it is provided that on the surface of the substrate at the measurement position a further thermocouple arrangement for providing a an absolute temperature at the measuring position corresponding thermoelectric signal, and terminals at which the absolute temperature corresponding thermoelectric is tapped off signal, are formed. As is known, can be directly measured with a thermocouple, a temperature difference only. For the absolute temperature, the temperature of a measuring point must be known or constant. This is done by the prior art outside of the sensor. The thus-obtained information about the absolute temperature of a measuring point can be used, for example, thermal symmetry deviations correct calculation for sensors with multiple measuring points, which are not covered by a mere temperature differential measurement between the measuring points and their non-detection has an evaluation error result because the asymmetry the temperature difference is not exactly equal to the difference between the heat flows of the different measurement positions.

An expedient embodiment is that which serves to supply the corresponding absolute temperature thermoelectric signal thermocouple assembly comprises one of the thermocouple junctions surrounding the measuring position circumscribed region of a first thermocouple material, from which extends a connecting portion to one of the formed on the surface connections. Here, the detection of the absolute temperature serving more thermocouple assembly is concentrated around the center of the measurement position around and is characterized by the measurement position or a there mounted sample in direct contact temperature. For the purposes of the fullest possible radial symmetry is expediently provided that the circumscribed area of ​​the first thermocouple material is annular.

The training and Abgreifbarkeit the corresponding absolute temperature thermoelectric signal is conveniently accomplished by that in the circumscribed area of ​​the first thermocouple material, a thermal contact is made with a different second thermocouple material extending to one of the formed on the surface connections.

A simplification and particularly good utilization of space on the sensor is achieved in an expedient embodiment, that are formed on the sensor, two of the measurement positions, and a connection between the second thermocouple materials of the two measurement positions are formed on the substrate and led to a common terminal. Between this common connection and the two associated with the first thermocouple material terminals of the two measurement positions in each of the absolute temperature of said measurement positions can be tapped corresponding thermoelectric signal.

In a further expedient embodiment, it is a minimizing of the mounted on the substrate connection structure that are formed on the sensor, two of the measurement positions and on said substrate a connection between two electrically equivalent ends of the two measuring positions associated thermopile is formed and the other two ends of the thermopiles respectively to the tap of the difference between the delivered by the two thermopile thermoelectric signals serving, formed on the substrate terminals are connected. In this embodiment, the two thermocouple columns are mutually electrically connected, so that at the two terminals corresponding to the difference of the temperatures at the measurement positions corresponding thermoelectric signal occurs.

In addition, it may be desirable for the evaluation and correction calculation, to be able to tap the respective approximated the individual heat flows outputs of the two thermopile separated. For a minimization of the necessary connection structure on the substrate, it is advantageous that the connection is connected to a common terminal formed on the substrate. can be picked up between this common terminal and guided to their respective terminals ends of the thermopile thus separately the output of both thermopile.

Within the scope of the invention is provided in particular that the layers formed on the substrate thermocouple assemblies are formed as thick films. The application of the thick film technique for the production of the thermal element arrays on the substrate is in the aforementioned<patcit id="pcit0003" dnum="DE3916311C2"><text>German patent DE 39 16 311 C2</text></patcit> and the underlying <patcit id="pcit0004" dnum="DE3916311A1"><text>German Offenlegungsschrift DE 39 16 311 A1</text></patcit> explained, showing the advantages achieved thereby. In particular, the thick-film technique solves in a simple manner also the insulation of the individual structural elements of the thermocouple assemblies outwards, ie towards crucibles or reference sample crucibles, which are placed on the measurement positions.

With respect to the desired thermal inertia and resistance of the sensor, it is advantageous that the substrate is a ceramic material.

In a third aspect of the invention, the thermal analysis sensor is characterized with a substrate through which a heat flow between a to the substrate thermally coupled heat source and at least one measurement position formed on the sensor can be conducted, and formed with one on a substantially planar surface of the substrate having thermocouple assembly for delivering a thermoelectric signal, one of the measurement position associated series of connected in a circuit arrangement with one another, composed of two different thermocouple materials thermocouple junctions according to the invention is characterized in that the thermal conductivity of the substrate is not greater than 5 watts per meter per Kelvin.

This compared with conventional substrates Alox lower thermal conductivity means that adjusts itself a higher temperature gradient between the thermal contacts located on different temperature levels. This results in a corresponding increase in the current supplied by the thermocouple assembly thermoelectric signal with the result that increase the sensitivity of the sensor and its signal-to-noise ratio. However, increases with the decrease of the thermal conductivity of the substrate, the time constant of the sensor. Even if the reduction of the thermal conductivity would set no material technical limitations, therefore a lower limit should not be exceeded, in just a satisfactory time constant is still achieved. In this regard, for the practical application of thermal conductivities of interest, the value of 0.5 W / (m * K) does not fall below.

It is preferably provided that the thermal conductivity no greater than 3 W / (m * K), more advantageously no greater than 2 W / (m * K). This especially noticeable improvements over conventional Alox substrates are obtained.

An expedient embodiment is that the substrate is a special ceramic material is selected which has a lower conductivity than the conventional oxide ceramics, but comparatively favorable mechanical electrical properties. Suitable, for example, that available under the product name PYTHAGORAS substrate material having a thermal conductivity in the range of 2 W / (m * K). Also suitable, albeit mechanically less favorable, is the glass ceramic substrate available under the product name MACOR having a thermal conductivity of significantly less than 2 W / (m * K).

According to a fourth aspect of the invention features a method for manufacturing a thermoanalytical sensor, in which on a substantially planar surface of a substrate in thick-film technology, a pattern of at least two different thermocouple material pastes is printed which a serving to deliver a thermoelectric signal thermocouple arrangement with an at least a measurement position associated series of connected in a circuit arrangement with one another, composed of the two different thermocouple materials thermocontacts equivalent, and the printed pattern is fired, according to the invention is characterized in that it breaks down the pattern into at least two patterns, producing on the substrate of the partial patterns in thick film technology , above an insulating layer with the context of the partial patterns corresponding via holes applying, on another part of the pattern produces thick-film technology and so long performs this process until all the partial patterns are superimposed prepared.

The thick film technology can be the whole consisting of partial patterns and insulating structure on the substrate with relatively little effort produced. When thermocouple materials can be used for the other thermocouple material conventional pastes, such as gold paste for a thermocouple material and gold / palladium paste. If desired, further materials can be used to form thermal contacts with different properties. These pastes can be applied in a known manner by screen printing method according to the proposed patterns. After each deposition process of the internal operation is carried out in each case. In particular, may initially which is applied a thermocouple material and fired and then applied the other thermocouple material corresponding to the part pattern and fired for each partial pattern. Separate implementation of these two firings favors the thermoelectric performance of thermal contacts such masses formed.

Advantageous embodiments of the method are to make the partial patterns so that the same directly the thermoanalytical sensors formed by repeatedly performing the layered application with the preferred circuitry. The first such feature, perform the partial pattern essentially identical. Another embodiment is to switch the partial pattern only one compound after another, bringing the number of vias can be kept small. A further embodiment is that on the uppermost with respect to the substrate portion pattern an insulating layer having terminals at which the thermoelectric signal can be tapped off is produced, of which at least one is through-contacted to the bottom with respect to the substrate portion pattern.

In the following description of the invention based on embodiments with reference is explained in more detail to the drawings. The drawings show:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic plan view of a first embodiment of an inventive thermoanalytical sensor in the region of a measuring point;</dd><dt>FIG. 2</dt><dd>a schematic view of a second embodiment of an inventive thermoanalytical sensor with two measuring points;</dd><dt>Fig. 3</dt><dd>an exploded view of a third embodiment of an inventive thermoanalytical sensor;</dd><dt>Fig. 4</dt><dd>a schematic plan view of a fourth embodiment of an inventive thermoanalytical sensor, and</dd><dt>Fig. 5</dt><dd>an exploded view of a fifth embodiment of an inventive thermoanalytical sensor.</dd></dl> A first embodiment of an inventive thermoanalytical sensor comprises a cylindrical substrate 1 with a relative to the cylinder radius small cylinder height. Fig. 1 shows A view seen in the direction of the cylinder axis of the substrate 1 is a schematic plan view of a circular disc-shaped surface 2 of the substrate. In a confined between the cylinder axis and its radially outer edge region of the surface 2, a measurement position 3 is formed, which is provided with an applied in thick-film technology thermocouple arrangement.

In this thermocouple assembly respectively the ends overlap strip-shaped portions of two different thermocouple materials and form by this overlap a series of thermal contacts. This thermal contacts are arranged on four concentric circles whose common center 4 forms the center of the measurement position 3rd Located on the center next first district first thermal contacts are designated in FIG. 1 by the reference number 5. They are each composed of overlapping short azimuthal end regions of the two different thermocouple materials 6, 7 assembled, from which the thermocouple materials 6, 7 slightly spaced from each other and parallel to one another substantially radially with respect to the center 4 to the second circuit to the outside extend, where they form 5 as the first thermocouple junctions by overlapping short azimuthal end portions, the second thermocouple junctions. 8

The third thermal contacts 9 are located on the third circle whose radius is larger than the radius of the first circle and smaller than the radius of the second circle. They are similar to the first thermocouple junctions 5 from short azimuthal overlapping end portions of the two thermocouple materials 6, 7, from which the two thermocouple materials 6, 7 substantially radially in strips extend outward up to the fourth circle whose radius is greater than the radius of the second circle. On the fourth circuit the ends of the strips of the thermocouple material are 7. This ends together with them overlapping ends of the thermocouple material 6 which extends following azimuth from there to the fourth circle, the fourth thermocouple junctions 10. These azimuthal strip 11 of the first thermocouple material 6 each extending from the fourth thermal contact 10 to the substantially radial strip of the thermocouple material 6 extending from the next adjacent third azimuthally thermal contact 9th The first, second, third and fourth thermocouple junctions 5, 8, 9 and 10 are arranged on their respective circles azimuthally under the same angular distance.

From the fully symmetrical configuration of the first thermocouple junctions 5 deviates one of the first thermal contacts 5 'characterized from that of the substantially radially emanating from it strips of the first thermocouple material 6' over the radius of the second circle addition to a on the surface 2 of the substrate 1 formed pad 12 is continued. This first thermocouple junction 5 'forms one end of a thermopile, in all thermal contacts 5, 5', 8, 9 and 10 in turn are connected to a row. The other end of the thermopile of this first thermal contact forms 5 'radially adjacent third thermocouple junction 9' downstream fourth thermocouple junction 10 '. 9 of this third thermal contact 'is substantially radially outwardly extending strips of the thermocouple material 7' is contacted at its located on the fourth circle outer end of a strip of the thermocouple material 6 'and forms the fourth thermocouple junction 10'. The strip of the thermal material 6 "is led to a formed on the surface 2 further pad 12 '.

The character design and its description above also show that the thermocouple materials 6, 7 or 7 'only in the areas where they overlap each other and through this overlap contact the thermal contacts 5, 5', 8, 9, 10, 10 form ' , are superimposed. Incidentally extend all thermocouple materials 6, 7 or 7 'side by side in the same plane.

In the to the thermopile cascaded series, wherein the first thermal contact 5 and a second thermal contact 8 'begins, that is a respective first thermal contact 5 and 5' are immediately adjacent until, after a success counter clockwise azimuthal rotation around the center 4 of the the initial first thermocouple junction 5 'azimuth closest first thermocouple junction 5' is achieved. the related by the generally radially extending strips of the thermocouple material 7 further thermocouple junction 8 'is in turn a third thermocouple junction 9 "immediately adjacent, to which in each case immediately adjacent pairs followed by the fourth and the third thermocouple junctions 10 and 9 until the fourth thermocouple junction 10 is reached ', which forms the other end of the thermopile. The overall thermocouple arrangement has the appearance of a double star. The extending in the form of rectilinear strips between the first and second thermocouple junctions 5 and 8 thermocouple materials 6, 7 form an inner star and delimit between them on the surface 2 each azimuthal intermediate portions 13 in each of the pairs in the row immediately adjacent third and fourth thermocouple junctions are 9 and 10 and form with which outgoing thermocouple materials 6, 7 the external rating. The arrangement could be continued in the same way, by 'another azimuthal circulation would be started counterclockwise starting with the thermal contact 10th

A second embodiment of the inventive thermo-electric sensor is shown in Fig. 2 in a representation of the first embodiment in Fig. 1 corresponding view. In this embodiment, two measuring points 3 and 3 'are provided, each in its structure completely described with reference to the FIG. 1 and illustrated measurement position 3 corresponds to, and therefore can be referred to the relevant description. The two measurement positions 3 and 3 'of the second embodiment are arranged with respect to the cylinder axis of the substrate 1 diametrically opposite each other equidistant. In the vicinity of the measuring position 3 is printed on the surface 2, the name "S" for "sample" and in the vicinity of the measuring position 3 ', the term "R" for "Reference". This points to the usefulness of the measurement position 3 for setting up a sample and the usefulness of the measurement position 3 'for setting up an inert reference sample.

With regard to FIG. 1 is an inconsistency only in that the 10'gebildete of the fourth thermocouple junction end of the formed at the measurement position 3 thermopile and also that of the fourth thermocouple junction 10 'formed late at the measurement position 3' trained thermopile deviating from FIG. 1 is not in each case led to a FIG. 1 corresponding separate connector 12 '. Instead, these two ends are connected together by a strip of the thermocouple material 6th The other end of the thermopile forming first thermal contacts 5 'of both measuring positions 3 and 3' are performed as shown in FIG. 1 respectively to a terminal 12. In this way the two thermopile are electrically connected to each other. therefore, the difference in supplied by the two thermopile thermoelectric signals are tapped at the two terminals 12 of the second embodiment while in the first embodiment at the terminals 12, 12 'abuts the total current supplied by the formed at the measurement position 3 thermopile thermoelectric signal.

In a third embodiment of the inventive thermoanalytical sensor, the overall pattern formed by the thermal materials and thermal contacts of the thermocouple array is divided into a plurality of sub-patterns, said sub-pattern superposed and corresponding electrical ends of these sub-patterns are connected to each other. This is represented in Fig. 3 for the sake of clarity in the form of an exploded view, in which the individual layers of this superimposition are shown drawn in the direction of the cylinder axis of the matching with the first and second embodiment of Fig. 1 and 2, the substrate 1 apart. In Fig. 3 a total of three such partial patterns 14, 15 and 16 are provided, each for itself which in the second embodiment provided and illustrated in FIG. 2, the thermocouple assembly forming pattern corresponds. Minor deviations from the pattern shown in FIG. 2 exist only insofar as they are necessary for connecting the electrical ends of the partial patterns.

The lowermost in FIG. 3, part pattern 14 is, as in Fig. 2, arranged on the surface 2 of the substrate. the thermocouple material from one end of the corresponding to the overall pattern entire circuitry forming first thermal contact is 5 'connected to the pad 12 as in Fig. 2. By contrast, the corresponding end-side first thermal contact of the right in FIG. 2 or FIG. 3, part of the pattern, which is interconnected with the left-hand portion by means of the connection 6 from thermocouple material, connected to a Durchkontaktierungsstelle 17, both of which in Fig. 2 or Fig. 3 left-hand pad 12 and the corresponding one in Fig. 2, right pad terminal pad 12, which is, however, formed in FIG. 3 as a non-contiguous with the remaining part pattern island spaced.

On the arranged on the surface 2 partial pattern 14 there is an insulating layer 18 that is congruent to the provided Durchkontaktierungsstelle 17 and the two pads 12 with vias 19th On the part pattern 14 opposite surface 20 of the insulating layer 18, the part pattern 15 is arranged. The corresponding to the run for connecting 12 end of the lowermost part of the pattern 14 end of the central part of the pattern 15 'is connected, which by the Durchkontaktierungsstellen 17, 17' with a Durchkontaktierungsstelle 17 is connected via hole 19 congruent with the Durchkontaktierungsstelle 17th The end of the right in Fig. 3 part of the partial pattern 15 corresponding to the run to Durchkontaktierungsstelle 17 end of the lowermost part of the pattern 14 is led to a stripped from the insulating layer 18 downward Durchkontaktierungsstelle 21st The lowest two pads 12 are carried on by the same via holes to cover 19 through to the surface 20 of the insulating layer 18 and form isolated islands.

At the part provided with the pattern 15 surface 20 of the insulating layer 18 an insulating layer 22 is arranged, which is provided with the Durchkontaktierungsstelle to 21 and the two connecting pads 12 congruent via holes 19 '. The surface 23 of the insulating layer 22 carries in Fig. 3 uppermost part pattern 16. The terminal end of the left part is 'connected, by a to congruent via hole 19' with a Durchkontaktierungsstelle 17 'of the insulating layer 22 through the to congruently arranged Durchkontaktierungsstelle 17' is the central part of the pattern 15. The terminal end of the right part is connected to the right in Fig. 3 pads 12, which is completely contacted by thus congruent via holes 19 'and 19 of both insulating layers 22 and 18. The left pad 12 is of corresponding via holes 19 ', 19 through the left pad 12 of the lowermost in Fig. 3 part pattern 14.

On the provided with the uppermost part pattern 16 surface 23 of the insulating layer 22 an insulating layer 24 is arranged, which "has. At the through these via holes 19" only to the connection pads 12 congruent via holes 19 through-hole pads 12 which is supplied from the entire circuit arrangement thermoelectric signal tapped. It represents the sum of the thermal voltage differences supplied by the individual partial patterns 14, 15 and 16 between the respective left and right each part of each partial pattern.

In addition, arc-shaped marks are on the exposed surface 25 of insulating layer 24 in addition to the already mentioned with reference to FIG. 2 instructions "R" and "S" 26 is provided, which centering the sample and reference pans with respect to the centers 4 and 4 'of facilitating relevant measuring points (see. FIG. 2).

The third embodiment shown in Fig. 3 in particular is produced in thick-film technique. Of the sub-pattern 14 is first printed and fired in a screen printing process from suitable thermocouple material pastes on the surface 2 of the substrate first Preferably, this process takes place in two steps, in the first only be applied from the structural components a thermocouple material existing and immediately fired. In the second step, consisting of the other thermocouple material structure elements are printed and repeated the burning process. This two-step procedure affects the quality of the thermal contacts favorable. After application of the insulating layer 18 is in the same way the second partial pattern 15 made and repeated this entire process until all insulation and partial patterns are completed. Then the uppermost insulating layer 24 is mounted.

A fourth embodiment of the inventive thermoanalytical sensor, which is shown in Fig. 4 in a Fig. 1 corresponding view, has a total of four measurement positions 30, 31, 32 and 33, respectively, each as the measuring position shown in Fig. 1 is designed 3 why reference is made to the description of FIG. 1,. In particular, the ends of the individual thermopiles as shown in Fig. 1 are respectively connected to a pair of terminal pads 12, 12 ', at which the thermoelectric voltage generated by the respective thermopile can be tapped. The centers of the four measurement positions 30, 31, 32, 33 are located on the corners of a square, the diagonals of which intersect at the cylinder axis of the substrate. 1

A fifth embodiment of the inventive thermoanalytical sensor, which is shown in Fig. 5 in the direction of the cylinder axis of the substrate 1 exploded exploded view corresponds, with regard to the layer formed by the connection 6 and the two connecting pads 12 differential circuit between the two double stars completely the reference of FIG. 2 explained second embodiment, so that in this respect can be made to the description thereof. In addition, FIG. 5 shows an existing also in the second embodiment, but not shown in FIG. 2, insulating layer 34 having the connecting pads 12 of the thermocouple assembly congruent window 35 so that there is the signal present at the connection pads 12 thermoelectric difference signal can be tapped. The insulating layer 34 allows the placement of metallic crucible without this results in short courses between the thermocouple junctions.

In addition to those already in the second embodiment shown in FIG. 2 provided for elements 'a further thermocouple assembly 36 or 36' in the fifth embodiment, each of the two measurement positions 3 and 3 formed on the exposed surface 37 of insulating layer 34th Each of these further thermocouple assemblies 36, 36 'has an annular first thermocouple material 38 or 38' which is made relatively respectively in centric arrangement to the center 4 and 4 'of the measuring points 3 and 3'. In Fig. 5, these two further thermocouple assemblies 36, 36 'is shown to illustrate in a larger scale than the underlying parts of the exploded view. In fact, the ring-shaped first thermocouple material is 38 or 38 'respectively disposed within the first circle on which the first thermocouple junctions lie. 5 In through the inner peripheral ring 39 or 39 'bounded region, the insulating layer 34 and the substrate congruent to one another in each case, axially continuous recesses 40, 40' bzw.41, 41 '. Such recesses are present also in the other previously described embodiments and referred to in the relevant figures by corresponding reference numerals.

The annular first thermocouple material 38 or 38 'in each case has a stripe-shaped radial continued 42 or 42', each leading to a pad 43 or 43 '. Further, on the mid-perpendicular to an imaginary line connecting the two centers 4, 4 'of the measuring positions 3 or 3', a common pad 44 centered, from which along this perpendicular bisector between the two connecting pads 43, 43 'through a connecting piece 45 to a Y-shaped branch extends, from where the connecting piece 45 'symmetrical to the mid-perpendicular to the annular first thermocouple materials 38 and 38' extending in two strip-shaped arms 46, 46 inside. The connecting pad 44, the connector 45 and its arms 46, 46 'consist of a second thermocouple material 38 or 38 with the first thermocouple material' each constitutes a thermal contact. The occurring of these two thermal contacts thermoelectric signals between the pad 44 and the connecting pads 43 and 43 'can be tapped. They each provide a an absolute temperature is measured at the position 3 and 3 'corresponding signal. For the determination of the absolute temperature, the signal is processed in a known manner in a suitable circuit on.

In all the embodiments described above, the sensor for thermal coupling to a heat source on an edge region of the substrate 1 with the heat source is thermally contacted. To this end, it can be placed on a correspondingly shaped Wärmeleitflansch the heat source, for example with an annular edge area of ​​its surface 2 opposite underside. In particular, this annular peripheral region between the radially outer edge of the cylindrical disc substrate 1 and a groove formed in the underside flat cylindrical recess may be limited, the radius of which is somewhat smaller than the radius of the substrate first

The thereby adjusting with respect to the centers 4, 4 'of the measurement positions 3, 3', 30, 31, 32, 33 radial temperature gradients are the cause for the generation of thermoelectric voltages between the radially spaced thermocouple junctions 5, 8 and 9, 10. This temperature increase with decreasing thermal conductivity of the substrate first To achieve high sensitivity of the sensor, therefore, substrates 1 are mixed with a relatively small thermal conductivity used λ, particularly with λ no greater than 5 W / (m * K), preferably λ is not greater than 3 W / (m * K) or not greater than 2 W / (m * K). For this purpose, suitable substrates 1 are ceramics with special properties, for example, the ceramic material available under the trade name Pythagoras, or available under the tradename MACOR glass ceramic with a λ 1.5 W / (m * K).

List of reference numerals

<dl id="dl0002" compact="compact"><dt>1</dt><dd>substratum</dd><dt>2</dt><dd>surface</dd><dt>3</dt><dd>measuring position</dd><dt>4, 4 '</dt><dd>Center, center</dd><dt>5, 5 ', 5' '</dt><dd>first thermal contacts</dd><dt>6, 6 ', 6' '</dt><dd>Thermocouple material</dd><dt>7, 7 '</dt><dd>Thermocouple material</dd><dt>8, 8 '</dt><dd>second thermal contacts</dd><dt>9, 9 ', 9' '</dt><dd>third thermal contacts</dd><dt>10, 10 '</dt><dd>fourth thermocouple junctions</dd><dt>11</dt><dd>azimuthal strip</dd><dt>12, 12 '</dt><dd>pad</dd><dt>13</dt><dd>intermediate regions</dd><dt>14, 15, 16</dt><dd>subpattern</dd><dt>17, 17 ', 17' '</dt><dd>Durchkontaktierungsstelle</dd><dt>18</dt><dd>insulating layer</dd><dt>19, 19 ', 19 "</dt><dd>vias</dd><dt>20</dt><dd>surface</dd><dt>21</dt><dd>Durchkontaktierungsstelle</dd><dt>22</dt><dd>insulating layer</dd><dt>23</dt><dd>surface</dd><dt>24</dt><dd>insulating layer</dd><dt>25</dt><dd>surface</dd><dt>26</dt><dd>mark</dd><dt>30, 31, 32, 33</dt><dd>measuring positions</dd><dt>34</dt><dd>insulating layer</dd><dt>35</dt><dd>window</dd><dt>36, 36 '</dt><dd>more thermocouple assemblies</dd><dt>37</dt><dd>surface</dd><dt>38, 38 '</dt><dd>first thermocouple material</dd><dt>39, 39 '</dt><dd>inner ring circumference</dd><dt>40, 40 '</dt><dd>recesses </dd><dt>41, 41 '</dt><dd>recesses</dd><dt>42, 42 '</dt><dd>continuation</dd><dt>43, 43 '</dt><dd>pad</dd><dt>44</dt><dd>pad</dd><dt>45</dt><dd>joint</dd><dt>46, 46 '</dt><dd>poor</dd></dl>