Method for controlling temperature of welded or sintered connected elements, and welding or sintering device

Abstract

The invention relates to an element temperature control method for forming a welded or sintered connection between elements, in which at least one controllable heat source is provided for providing thermal energy to the elements. Measuring a first temperature of the element or the component of the welding or sintering device in thermal contact with the element in a non-contact manner at at least one first temperature point by means of at least one first temperature sensor in thermal contact with the element or the component of the welding or sintering device; a second temperature of the element or a component of the soldering or sintering device in thermal contact with the element is measured in a non-contact manner at at least one second temperature point by means of the at least one second temperature sensor, the first temperature point being spatially farther from the second temperature point such that, upon a change in temperature, the temperature of the element or the component of the soldering or sintering device is measured in a non-contact manner. A temperature gradient is expected to occur between the first temperature and the second temperature. The measured second temperature is calibrated based on the measured first temperature to determine a calibrated second temperature, and the heat source is controlled based at least on the calibrated second temperature. The invention also relates to a correspondingly configured welding or sintering device.

Description

Technical Field

[0001] The present invention relates to a method for controlling the temperature of an element (or component) for forming a welded (brazing) or sintered connection between elements (or components), wherein at least one controllable heat source is provided for providing thermal energy to be transferred to the element (or component).

[0002] Furthermore, the present invention relates to a welding or sintering apparatus for forming a welded or sintered connection between components (or parts), wherein the welding or sintering apparatus has at least one controllable heat source configured to provide thermal energy to be transferred to the components (or parts). Existing technology

[0003] When sintering and brazing (welding) two or more components (especially electronic components and substrates), they can be joined together by a connecting material that is electrically and / or thermally conductive, wherein the connecting material is applied to the components by sintering or melting. The components to be joined can be compressed between an upper and lower die during this process, typically at pressures much higher than those during welding. In conventional sintering or welding equipment, the heat energy required for sintering or welding can be transferred to the components through the upper and lower die.

[0004] Exemplary conventional sintering or welding apparatuses and corresponding methods are described, for example, in DE 10 200 6 034 600B4, DE 203 00 375 U1, DE 10 200 4 047 359 B3, DE 10 201 2 206 403 B3 and WO 2014 / 135151 A2.

[0005] Equipment or apparatus for manufacturing welded or sintered joints may include one or more process chambers for setting the process atmosphere (atmosphere environment) required for the welding or sintering process, and particularly for adjusting the process atmosphere during the process. The components to be joined are pre-assembled into assemblies, which, if necessary, can be secured to each other in the desired position by appropriate means and methods, and then transported between different process chambers via suitable conveying devices. For example, the process atmosphere in each process chamber can be set and / or adjusted, including adjusting its material composition, pressure, and / or temperature. For instance, pressures between 1 hPa and 1200 hPa can be set by using different mixtures of process gases.

[0006] In traditional welding or sintering equipment, heat energy can be input via upper and / or lower tools. Typically, variable-pitch heating plates or infrared radiators can also be used as heat sources. Another method for heating elements is to utilize induction to input heat energy onto the element or a suitable support plate. For this purpose, one or more induction devices can be placed above and / or below the elements to be joined within the process chamber. This forms corresponding induction zones, designed so that the electromagnetic energy generated by the induction devices can be input into the element, inducing eddy currents within the element and thus heating it. To cool the induction devices, they can be directly connected to a coolant circulation loop or cooled through thermal contact with the process chamber walls. Convection cooling can also be employed.

[0007] Generally, for components of different qualities, heat or energy input can be optimized by changing the distance between the sensing device and the component or carrier. To do this, existing sensing devices can be raised or lowered, either as a whole or individually. Furthermore, the shape of the sensing device can be adjusted to fit the shape of the component or carrier, thereby optimizing energy input.

[0008] Compared to heating elements through thermal radiation or thermal contact, the energy input of induction heating is easier to control. Using an induction device, the heat input can be steplessly adjusted from zero power to maximum power in fractions of a second.

[0009] To fully utilize a heat source with highly dynamic heat input (such as the aforementioned sensing device) and achieve precise temperature control that is differentiated in both time and space, adaptive control of the heat source is necessary, while also considering the delay in heat transfer within the component. Accurate measurement of the component temperature is crucial in this process.

[0010] Typically, component temperature is measured using one or more temperature sensors that are in thermal contact with the component; that is, the temperature sensor is either attached to the component being measured or integrated into it. Here, if the location where heat energy is input to the component is far from the location where the temperature is measured, a time lag may occur between the energy input and the temperature measurement due to the component's limited thermal conductivity. This can lead to inaccurate component temperature control and overheating due to "overshoots."

[0011] To reduce such errors, the temperature measurement location can be chosen to be as close as possible to the energy input location. This allows the heat source control to respond quickly to temperature changes. However, since the component is not directly affected by heat energy but indirectly through thermal coupling, there is a time lag, making it impossible to measure the actual temperature of the component very accurately.

[0012] DE 10 2004 047 359 B3 recommends the use of non-contact optical measurement systems (such as pyrometers) for temperature measurement. However, a drawback of such optical measurement systems is that the measured temperature is not an absolute value, but depends on the material and surface properties of the component.

[0013] DE 11 2008 000 853 T1 describes a method for temperature measurement in a heat treatment chamber, which includes a heating element, a contact temperature sensor, and a non-contact temperature sensor. The non-contact temperature sensor is located outside the heat treatment chamber. The temperature recording points of the contact and non-contact temperature sensors are almost identical, thus the measurement differences between the non-contact temperature sensors can be eliminated by the measurement values ​​of the contact temperature sensor. However, the sensor has very low shape stability and mass, which leads to measurement errors, allowing changes in the number of molecules to rapidly affect temperature changes. Summary of the Invention

[0014] The objective of this invention is to provide a method for temperature control (or temperature regulation) of components to establish welded or sintered connections between components, enabling precise control (regulation) of component temperature and flexible arrangement of temperature sensors. This invention also aims to eliminate the interference effects of pressure / gas fluctuations on non-contact sensors.

[0015] This objective is achieved by a method having the features of claim 1. Advantageous embodiments of this method are given in the dependent claims.

[0016] A method for temperature control (regulation) of components to establish welded or sintered connections between components is proposed, wherein at least one controllable (adjustable) heat source is provided to provide heat energy to be transferred to the components. The method involves measuring a first temperature of the component, or a component of the welded or sintered assembly in thermal contact with the component, at at least one first temperature sensor at at least one first temperature point, the at least one first temperature sensor being in thermal contact with the component or component; and measuring a second temperature of the component, or a component of the welded or sintered assembly in thermal contact with the component, at at least one second temperature point in a non-contact manner using at least one second temperature sensor; wherein the first temperature point and the second temperature point are spatially spaced to ensure that a temperature gradient is expected between the first and second temperatures when the temperature changes; and wherein the measured second temperature is calibrated based on the measured first temperature to determine a calibrated second temperature, and wherein the heat source is controlled at least based on the calibrated second temperature. The measurements of the first and second temperatures are preferably performed at different locations. Components of a welding or sintering apparatus (or equipment) that come into thermal contact with components (hereinafter referred to as apparatus components or parts) may be, for example, support plates, support frames, or component brackets, which carry the components to be joined during the manufacturing process. The first temperature can also be determined by a temperature sensor integrated into the component and connected to a control unit intended to perform this method, so as to transmit the first temperature of the component to the control unit. Therefore, if the first temperature of the component or apparatus component is measured by multiple first temperature sensors, the first temperature can be determined in an appropriate manner, such as by averaging the temperature values ​​measured by the multiple first temperature sensors, or by other methods. The second temperature is determined using the same method.

[0017] The spatial distance between the first and second temperature points (which is relatively far apart) means that they are spatially spaced regardless; that is, they are either located on the same side of the component and maintained at a certain distance from each other, or on opposite sides of the component. Therefore, when the first and second temperature sensors are located on the same side of the component, the distance between them can be at least 5% of the component diameter, especially 10%. In any case, during the heating or cooling phase, the measurements recorded by the first and second temperature sensors at different locations will exhibit a temperature gradient. In thermal equilibrium, i.e., after a prolonged period under isothermal conditions, the temperature gradient may decrease or even disappear completely. However, it is foreseeable that when the heat input from the heat source changes during the heating or cooling phase due to spatial distance, the first and second temperature sensors will record different measurements. In any case, it cannot be assumed that the measurements recorded by the first temperature sensor are the same as those of the second temperature sensor; therefore, in the case of temperature changes, especially under dynamic temperature conditions, the second temperature sensor can be calibrated using the first temperature sensor within the temperature gradient range. Advantageously, by arranging temperature sensors at intervals, a highly flexible arrangement can be achieved, such that the second temperature used to control the heat source is preferably recorded by a second temperature sensor located on the side of the component or component bracket (which is in thermal contact with the component as a device part) facing the heat source; while the first temperature sensor can be arranged in an easily mechanically accessible position on the component or component bracket to record the first temperature. Therefore, this spatially spaced arrangement allows for accurate calibration of the second temperature sensor's second temperature using the first temperature sensor's first temperature, even in situations where space is limited or the temperature point location is difficult to access; alternatively, a temperature sensor already integrated into the component can be used, for example, as the first temperature sensor.

[0018] According to the method of the present invention, the first temperature and the second temperature are combined in a suitable manner to achieve optimal temperature control of the element. Preferably, the first and second temperatures are measured such that both temperatures remain constant for a defined period of time, thereby significantly reducing the effects of time lag during the thermal equilibrium process within the element or between the element and contacting device components. The first and second temperatures can be measured on the same element or the same device component, or on different elements or different device components, but in any case, they must be measured at two spatially distant temperature points.

[0019] Here, calibration refers to the sum of a series of activities, under specific conditions, used to determine the correlation between the temperature value measured by the second temperature sensor (and its associated measurement uncertainty) and the temperature value measured by the first temperature sensor (and its associated measurement uncertainty), which serves as a reference temperature sensor. Through this correlation, the influence of the spatial distance between the first and second temperature points, as well as other differences introduced by the measurement technique, will be taken into account.

[0020] Determining the calibrated second temperature is primarily to address the following issue: For non-contact temperature sensors, the measured second temperature often differs from the actual temperature at the measurement point because the temperature measured in a non-contact manner may vary due to the material properties and / or surface characteristics of the components or devices being measured.

[0021] According to a preferred embodiment, the method is carried out in a settable process atmosphere (ambient environment), wherein setting the process atmosphere includes at least setting the material composition, pressure, and / or temperature of the process atmosphere. For example, depending on different stages of the process, the process atmosphere may contain reactive or non-reactive process gases. If the temperature of the process atmosphere changes, this temperature change can also be incorporated into the control of the heat source.

[0022] According to another preferred embodiment, the first temperature sensor is selected from a set including at least a thermistor, a positive temperature coefficient thermistor, a semiconductor temperature sensor, a thermocouple, and a temperature sensor based on an oscillating circuit. Alternatively or additionally, the second temperature sensor is a sensor configured to detect thermal radiation, and is preferably selected from a set including at least a pyrometer, a calorimeter, and a thermopile. The first temperature sensors described above are typical examples of contact temperature sensors. Correspondingly, the second temperature sensors described above are typical examples of non-contact temperature sensors.

[0023] According to another preferred embodiment, the at least one heat source is configured to transfer heat to the element or one or more components in a contact or non-contact manner, and is preferably selected from a collection including electric, magnetic, or electromagnetic field generators, preferably heating plates, induction heating elements, or infrared radiators, which can be coupled to the element or component at least thermally, inductively, or capacitively. The list of possible heat sources is not exhaustive. However, it is evident that inductive coupling between a magnetic field generator (also referred to as an inductor or sensing device) and the aforementioned element or device components is particularly suitable. Using such an inductor, the heat output can be controlled in various ways, such as by changing the operating voltage, operating current, or frequency.

[0024] According to another preferred embodiment, a heat source is controlled during a process step involving welding or sintering connections, and a calibration temperature is determined in at least one calibration step prior to this process step. This calibration step includes generating and storing a corresponding calibration function, based on which a second calibrated temperature is determined from a measured second temperature. The calibration step can be performed, for example, by measuring two different component or part temperatures separately and then determining the calibration function based on the measurements. Multiple calibration steps can also be performed, each determining multiple calibration functions. For example, calibration functions can be generated and stored separately for each component or part.

[0025] According to a preferred embodiment, a calibration step is performed before each process step, wherein the heat source is controlled (or regulated) based on a previously determined calibration function during the process step. Here, it is not necessary to know in advance the characteristics of the component or device measuring the second temperature to select a suitable calibration function. Performing the calibration step before the process step ensures that the temperature change process does not cause component damage due to an incorrect calibration function selection.

[0026] Alternatively or additionally, one or more calibration steps may be performed during the process, preferably at a defined time point or at a time when the temperature of the component has not changed substantially. Performing the calibration step at a time point where the temperature of the component or device remains substantially constant refers to performing calibration when the temperature profile of the component or device exhibits different temperature plateaus. This is done to allow for a pre-set equilibration period, thereby eliminating delays caused by different temperature measurement principles and the spatial location of the measurement points.

[0027] In this regard, it has been shown that it is advantageous to select a calibration function that matches the component to be processed from a plurality of calibration functions stored in a component-characteristic or part-characteristic manner before performing the process steps, wherein heat source control in the process steps is based on the selected calibration function. Generally, it is also possible to select a calibration function first and then check and / or adjust it during the execution of the process steps.

[0028] According to another preferred embodiment, the calibration function is a linear function or a polynomial function, preferably a fourth-order polynomial function. The use of linear functions has proven computationally simple, where any potential inaccuracies can be tolerated. Polynomial functions, especially fourth-order polynomial functions, are particularly suitable for calibrating the measurement characteristics of pyrometers.

[0029] According to another preferred embodiment, the control of the heat source is achieved through a two-stage (or two-phase) approach. In the first stage (first phase), a corrected setpoint temperature is determined based on a measured first temperature and a preset setpoint temperature. In the second stage (second phase), the output from the heat source is controlled based on a measured or calibrated second temperature and the corrected setpoint temperature. This two-stage control is also known as cascaded control. The preset setpoint temperature is not necessarily a fixed setpoint temperature; a curve or slope of the setpoint temperature can also be used as a reference. Specifically, the statement "based on the measured first temperature, the preset setpoint temperature, the measured or calibrated second temperature, and the corrected setpoint temperature" is not limited to the absolute values ​​of these parameters but also explicitly includes their curves changing over time, i.e., their mathematical derivation with respect to time. Furthermore, determining the corrected setpoint temperature based on the measured first temperature and the preset setpoint temperature does not preclude incorporating other parameters or measured values ​​into the determination of the corrected setpoint temperature when necessary. Therefore, the control of the heat source output is not necessarily based solely on the measured or calibrated second temperature and the corrected setpoint temperature; on the contrary, other parameters or measured values ​​can be incorporated. Specifically, feedback can also be provided to the corresponding control loop at each stage of the two-stage method.

[0030] In another preferred embodiment of the method according to the invention, the components to be connected are arranged on a main extension plane, wherein a first temperature sensor is arranged on one side of the main extension plane, and a heat source and a second temperature sensor are arranged on the other side of the main extension plane. Since the second temperature sensor and the heat source are arranged on the same side of the component arrangement, the change in component temperature can be recorded with a very short time delay; however, due to the spatial arrangement of the first temperature sensor, the first temperature it measures will be affected by a certain delay caused by heat conduction within the component or device parts.

[0031] Alternatively, the first and second temperature sensors are arranged on one side of the main expansion plane, and the heat source is arranged on the other side of the main expansion plane. Furthermore, the first and second temperature sensors and the heat source can also be arranged on the same side of the main expansion plane.

[0032] In another aspect, the present invention relates to a welding or sintering apparatus for establishing a welded or sintered connection between elements, the welding or sintering apparatus having at least one controllable heat source configured to provide heat energy to be transferred to the elements; at least one first temperature sensor arranged at at least one first temperature point, the at least one first temperature sensor being in thermal contact with the element, or a portion of the welding or sintering apparatus in thermal contact with the element, and configured to measure a first temperature of the element or portion; and at least one second temperature sensor arranged at at least one second temperature point, the at least one second temperature sensor being configured to measure a second temperature of the element, or a portion of the welding or sintering apparatus in thermal contact with the element, in a non-contact manner; wherein the first temperature point and the second temperature point are spatially spaced far apart so that a temperature gradient is expected between the first temperature and the second temperature when the temperature changes; and a control unit is also provided, the control unit being connected to the heat source, the first temperature sensor, and the second temperature sensor, and configured to perform the method described above. As described above, the first temperature sensor or another first temperature sensor may be a temperature sensor integrated into the element and connected to the control unit in order to transmit the first temperature of the element to the control unit.

[0033] According to a preferred embodiment, the heat source has a measurement window that allows infrared radiation emitted by the element, or a component of the welding or sintering device, to propagate along the direction of the second temperature sensor.

[0034] According to another preferred embodiment, a tube is provided in the measuring window, the tube being at least oriented toward the direction of the second temperature sensor, and configured to guide infrared radiation emitted by the element, or a component of the welding or sintering apparatus, toward the direction of the second temperature sensor, and preferably shielding the second temperature sensor from infrared radiation not emitted by the element or the component.

[0035] According to another preferred embodiment of the welding or sintering apparatus, the component, at least one heat source, at least one first temperature sensor, and at least one second temperature sensor are disposed within or on a hermetically sealed process chamber having a settable process atmosphere, particularly a vacuum, wherein the second temperature sensor is preferably disposed on the side of the heat source away from the component. In other words, the welding or sintering apparatus may include at least one hermetically sealed process chamber in which a settable process atmosphere, such as a low-oxygen or oxygen-free atmosphere, particularly a vacuum atmosphere, is set for heat treatment of the component, particularly for welding or sintering, without oxidation of the component. Both the first and second temperature sensors are disposed within or on the process chamber such that the measured values ​​of the temperature sensors are transmitted to the outside of the process chamber as the first and second temperatures. The second temperature sensor may be disposed inside or outside the process chamber; in the latter case, the second temperature sensor can observe the second temperature point through an optical window on the process chamber wall. A control unit (preferably disposed outside the process chamber) calibrates the second temperature according to the first temperature and controls the heat source according to the calibrated second temperature. This enables precise heat source control, for example, to satisfy a definable temperature gradient between the first and second temperature points. Attached Figure Description

[0036] The following accompanying drawings further illustrate the advantages of the invention. The drawings illustrate examples of the invention. Various combinations of features are included in the drawings, description, and claims. Those skilled in the art can readily consider these features individually and combine them into other meaningful combinations.

[0037] The attached diagram shows:

[0038] Figure 1 A schematic cross-sectional view of a welding or sintering apparatus according to one embodiment is shown.

[0039] Figure 2 and Figure 3 A schematic cross-sectional view of a welding or sintering system according to another exemplary embodiment is shown.

[0040] Figure 4 A graph showing two exemplary temperature curves with a first temperature and a second temperature is provided.

[0041] Figure 5 The diagram illustrates the calibration function used to explain how the second temperature is determined;

[0042] Figure 6 A schematic block diagram of two-stage temperature control is shown;

[0043] Figure 7 Various exemplary temperature curves and graphs of relative (heated) output curves are shown; and

[0044] Figure 8 More exemplary temperature curves and graphs of relative (heated) output curves are shown.

[0045] In the following text, the same reference numerals are used for the same or similar elements.

[0046] Figure 1 shows a schematic diagram and simplified cross-sectional view of a welding apparatus 10 according to an embodiment of the present invention. The welding apparatus 10 includes a dish-shaped (or can-shaped) transport frame 14 with an open bottom, at which a component holder (or carrier) 12 is placed, which is an integral part of the welding apparatus 10. Components 16 and 18 to be joined are placed on the component holder 12. Component 18 may be a substrate (or base), each substrate being joined to multiple components 16, such as power semiconductors, via a welding operation. Connecting materials (not shown) may be respectively provided between components 16 and 18. Below the transport frame 14 containing the component holder 12, an induction device 20 is provided to generate a strong magnetic field that induces eddy currents in at least the component holder 12. These eddy currents cause heating of the component holder 12. It is understood that other heat sources may be provided instead of the induction device 20. The distance between the component holder 12 or the transport frame 14 and the induction device 20 is variable (or adjustable).

[0047] The welding apparatus 10 also includes a first temperature sensor 24 located at a first temperature point position, where the first temperature sensor 24 is located on the upper side of the element 18, which serves as a substrate. The first temperature sensor 24 is guided through the transport frame 14 and contacts one of the elements 18 in a spring-loaded manner, and the first temperature sensor 24 is configured to measure the first temperature.

[0048] The sensing device 20 has a measuring window 22 that allows infrared radiation emitted from the bottom surface of the component holder 12 (as a second temperature point or location) to pass through the window 22 and reach a second temperature sensor 26 disposed below the measuring window 22, thereby measuring the second temperature through the second temperature sensor 26. In this example, the first temperature point and the second temperature point are respectively disposed on opposite (opposite) sides of the component holder 12.

[0049] Preferably, the first temperature point can be the surface of element 18. The second temperature point can preferably be the surface of heat source 20 on the underside of element 18 or element bracket 12 where there is direct or indirect heat input (e.g., radiant heat).

[0050] The first temperature sensor 24 is constructed as a contact temperature sensor and may be a thermistor, a positive temperature coefficient thermistor, a semiconductor temperature sensor, a thermocouple, a temperature sensor based on an oscillation circuit, etc. The second temperature sensor 26 is a non-contact temperature measurement sensor, such as a pyrometer, a volumeometer, or a thermopile, which measures temperature by detecting infrared radiation emitted by the object being measured.

[0051] According to a variant not shown, a tube may be arranged in the area of ​​the measuring window 22, which also surrounds the second temperature sensor 26. This tube concentrates or guides the infrared radiation emitted by the element bracket 12 for easy detection, while keeping external radiation that may interfere with temperature measurement away from the second temperature sensor 26.

[0052] Figure 2 illustrates a welding apparatus 110 designed according to another embodiment, similar in design to the welding apparatus 10 in Figure 1. The welding apparatus 110 includes multiple component holders 12 (three in this example), each component holder 12 equipped with an individually controllable sensing device 20. The distance between the sensing device 20 and the component holder 12 can be individually adjusted. All three component holders 12 are arranged in the same transport frame 14. The associated temperature sensors 24 and 26 are arranged similarly to the example in Figure 1.

[0053] The various components of the welding apparatus 110 are located within a process chamber 28, which provides a settable process environment for the welding process. The process chamber 28 can be temperature-regulated, evacuated, and / or pressurized, and can also be filled with different process gases. The pressure and / or temperature of this process environment can be set to preset values, and in particular, can be adjusted. A first temperature sensor 24 and a second temperature sensor 26 are disposed inside or on the surface of the process chamber 28. Specifically, the second temperature sensor 28 is disposed outside the process chamber and observes a second temperature point through an optical observation window on the process chamber wall.

[0054] Figure 3 shows another example of the welding device 210, which works by reversing the welding device 110 in Figure 2 along a horizontal axis. Unlike the examples in Figures 1 and 2, the first temperature sensor 24 does not directly contact the component 18, but rather contacts the bottom surface of the component carrier 12, serving as the first temperature point. The second temperature sensor 26 does not measure the temperature of the component carrier 12, but instead directly records the temperature of the components 16 and / or 18 located above the component carrier 12, serving as the second temperature point.

[0055] These three examples illustrate welding apparatuses 10, 110, and 210 configured to perform the methods of the present invention. It goes without saying that the arrangement of temperature sensors 24 and 26 described in these examples can also be alternatively applied to sintering apparatuses of corresponding designs. Such sintering apparatuses are typically equipped with additional tools for applying pressure to the components to be joined, thereby manufacturing the sintering apparatus. If necessary, these tools may be provided with suitable measuring openings for non-contact or contact temperature measurement, thereby measuring the temperature of the sintering apparatus components or elements.

[0056] Furthermore, it goes without saying that the welding apparatuses 10, 110, and 210 may also have tools necessary for applying extrusion pressure to the elements 16 and 18. For clarity, these embodiments are not shown in this example.

[0057] The following describes, in a simplified manner, a component temperature control method for forming a welded or sintered connection between components 16 and 18. This method can be implemented using welding apparatuses 10, 110, and 210 shown in Figures 1 to 3, for example, which can be placed in a control unit (not shown) connected to temperature sensors 24 and 26 and a sensing device 20 as a heat source. With this type of control unit, the heat output generated by the heat source 20 can be controlled, thereby heating components 16 and 18 to the desired temperature and cooling the components by reducing or shutting off the heat output.

[0058] While the first temperature sensor 24, due to its contact operation, can determine the component or assembly temperature at a first temperature point with great accuracy, the component or assembly temperature at a second temperature point determined by the non-contact second temperature sensor 26 suffers from systematic measurement errors. An example of such a non-contact temperature sensor is a pyrometer. A pyrometer determines its temperature by measuring the radiant power P emitted by the object being measured. Due to technical limitations, it typically only considers a specific wavelength range within the infrared band. According to the Stefan-Boltzmann law, the total radiant power P of a real object satisfies the following relationship:

[0059] P = ε · σ · A · T 4 (1)

[0060] Where ε is the emissivity,

[0061] σ is the Stefan-Boltzmann constant (σ = 5.6704 · 10⁻⁶). -8 Wm -2 K -4 A is the area (unit: m²)2 T is temperature (in K). Therefore, emissivity ε represents the thermal radiation capacity of the object being measured and depends on the material and surface properties of the object. The second temperature is preferably measured using a short wavelength. The measurement wavelength of the pyrometer is preferably no more than 5 µm, and particularly preferably no more than 2 µm, to limit the impact of inaccurately measured emissivity ε on measurement accuracy.

[0062] Since the emissivity ε of the object being measured (i.e., a component or element of the welding or sintering equipment) is usually not precisely known, or may be affected by local variations, the measured second temperature may have systematic measurement errors. Therefore, a calibrated second temperature needs to be determined based on the measured second temperature, where the measured first temperature is used as a calibration variable. To eliminate the difference between the actual temperature at the first temperature measurement point and the actual temperature at the second temperature measurement point, the temperatures of components 16, 18, or components of the welding apparatus 10, 110, 210 in thermal contact with the components should be kept as balanced as possible, i.e., the temperature gradient between the first and second temperature measurement points should no longer exist. This can be achieved, for example, by keeping the heat output of the heat source constant for a certain equilibrium time, or by adjusting it to a constant temperature, before determining the corresponding measured temperature value.

[0063] For example, the calibrated second temperature can be determined based on the calibration function established during the calibration procedure. The method for determining this calibration function will be described in more detail below.

[0064] One advantage of the method of this invention is that it cleverly combines two measurement methods: one is a first temperature measurement at a first temperature point using a temperature sensor that is in thermal contact with the component or device part. This method has a slower response time but provides very accurate measurements. The other is a second temperature measurement at a second temperature point using a non-contact temperature sensor. This method has a faster response time, but due to its dependence on materials, it can only provide less accurate measurements. By combining the measurements of the first and second temperatures, optimal temperature changes of the component can be achieved. Furthermore, the arrangement of the first and second temperature sensors is more flexible, allowing for a spaced arrangement.

[0065] Figure 4 shows example curves of the first temperature (T1) and the second temperature (T2) changing over time, where the absolute values ​​of the time scales are arbitrary. Temperatures T1 and T2 are measured on opposite sides of a copper element with a thickness of 5 mm. Heat source 20 is located on the same side as temperature sensor 26, which records the second temperature T2, while temperature sensor 24, which records the first temperature T1, is located on the side of the element opposite to heat source 20 (see the arrangement in Figures 1 and 2).

[0066] The maximum value of the second temperature T2 occurs around t = 48 seconds, while the first temperature T1 reaches a plateau around t = 55 seconds, meaning that the first temperature T1 remains essentially unchanged thereafter. The 7-second difference between the maximum value of the second temperature T2 and the plateau of the first temperature T1 is due to the time delay caused by heat transfer across the components.

[0067] In addition, Figure 4 As can be seen, the first temperature T1 exhibits a significantly slower and therefore less volatile change curve (response curve) than the second temperature T2. Furthermore, since calibration has not yet been performed (in... Figure 4 The second temperature T2 is shown in the figure, and there is a temperature difference of approximately 20°C to 25°C between the two temperatures T1 and T2.

[0068] Referring to Figure 5, the calibration procedure is illustrated below with an example. For this purpose, at time point t1, a contact temperature measurement (first temperature T1.1) and a non-contact temperature measurement (second temperature T2.1) are performed on an exemplary component. The temperature of the component increases continuously or intermittently within time point t1. At time point t2, the first temperature T1.2 and the second temperature T2.2 are measured.

[0069] Under the simplified assumption that there is a linear correlation between the measured second temperature T2 and the calibrated second temperature T2', the calibrated second temperature T2' can be determined according to the following equation:

[0070] T2'=k*T2+T offset (2)

[0071] Where k is the calibration factor, T offset It is the temperature difference at time t1. The factor k can be determined by the temperatures measured at time points t1 and t2 according to the following formula:

[0072] k = (3)

[0073] Temperature difference T offset The temperature value can be determined using the following formula:

[0074] T offset =T1.1-(T2.1*k). (4)

[0075] To determine the calibration function, it is best to perform temperature measurements when there is no temperature gradient on the component, meaning the component temperature remains constant for an appropriate period of time during each measurement, such as maintaining a plateau for 5 seconds. Of course, the component temperature must vary between two time points, t1 and t2. Generally, calibration can also be performed again at each preset time point, for example, every 10 seconds.

[0076] Alternatively, the calibration step can be performed as part of a sample calibration step. This sample calibration step targets a sample element whose emission characteristics are matched to those of subsequently processed elements or device assemblies in contact with it, in order to save the calibration function. This calibration function can then be invoked during actual process steps (such as actual soldering or sintering operations) without requiring a new calibration during the process step execution.

[0077] In addition to the calibration method described in Figure 5, the emissivity ε can also be measured directly. For example, the first temperature T1.1 and the second temperature T2.1 can be measured at ambient temperature (e.g., 20°C) using both contact and non-contact methods, similar to those described in Figure 5. The test object is then heated to a higher temperature (e.g., 150°C to 250°C), and the first temperature T1.2 and the second temperature T2.2 are measured again.

[0078] The emissivity ε can then be calculated using the following formula:

[0079] ε = (5)

[0080] Here we assume Less than Otherwise, these values ​​will be swapped so that the emissivity ε ≤ 1.

[0081] Referring to Figure 6, a two-stage or cascaded control of a heat source is described, where the control variable of the heat source is described by the function u2(t). Two temperature sensors are placed on the object being measured, where the first temperature sensor in contact with the object generates a first temperature T1, and the non-contact temperature sensor generates a second temperature T2. The change curve of the first temperature T1 is described by the function yM1(t), and the change curve of the second temperature T2 is described by the function yM2(t). The temperature function w1(t) is set as the input variable for control.

[0082] The difference between signals w1(t) and yM1(1) is obtained from the following equation, thereby generating the difference function e1(1) and passing it to the main controller R1.

[0083] (6)

[0084] The main controller R1 can be designed as a PI controller (proportional-integral controller), which generates the control function u1(t) according to the following equation:

[0085] (7)

[0086] Where kp and ki are the corresponding amplification coefficients. Through positive coupling with the set temperature function w1(t), the modified set temperature function w2(t) is determined from u1(t) according to the following equation.

[0087] (8)

[0088] In the second-level control (stage), the difference between the corrected setpoint temperature function w2(t) and the function yM2(t) is calculated according to the following equation, thereby generating the input function e2(t) from the controller R2.

[0089] (9)

[0090] Based on the following equation, the control variable or control function u2(t) of the heat source is generated from the controller R2.

[0091] (10)

[0092] Where kp and ki are the corresponding amplification factors.

[0093] It should be understood that the specific implementations of cascaded control listed here are purely illustrative and may be modified as necessary. The output power of the heat source is set in an appropriate manner. For example, when using the sensing device 20 shown in Figures 1 to 3 as the heat source, it can be controlled by adjusting its frequency, current, and / or voltage through the control unit of the sensing device 20. Furthermore, the distance to the sensing device 20 can also be included in the control range. When using an infrared heater or an ohmic heating device, the heating current can be controlled.

[0094] Due to the rapid response of the heat source or components 16, 18 or component bracket 12 on the side (face) facing the sensing device 20, the temperature profile of the side (face) facing the sensing device 20 can be controlled according to various functions, such as ramp, S-curve, quadratic function, e-function, stage hold or higher-order polynomial.

[0095] This characteristic can also be used to accelerate the heating of elements 16 and 18. For this purpose, the temperature on the element side facing the sensing device 20 can be increased for a short time to increase the temperature difference between the two sides of the relatively arranged elements 16 and 18.

[0096] Due to differences in component characteristics (properties), especially the differences in properties of the component facing the sensing device 20, the second temperature sensor 26, which performs non-contact measurement, cannot record absolutely accurate temperatures. This shortcoming can be compensated for by the first temperature sensor 24 measuring the component side (face) facing away from the sensing device 20, because the temperature level will be continuously adjusted according to this value, so that the desired temperature can always be set on the components 16 and 18.

[0097] In some cases, external factors (such as gas flowing into process chamber 28) may affect the contact-type first temperature sensor 24, thereby impairing control operation. This can be addressed by modifying the cascaded control described in Figure 6. Here, the control variable u1(t) generated by the main controller R1 can be "frozen" to an appropriate value u1 at a given time point (e.g., the time point of expected gas input). freeze This allows for more precise temperature control. Therefore, the corrected setpoint temperature w2(t) is not generated based on u1(t) and the setpoint temperature w1(t), but rather based on u1. freeze It is generated by w1(t).

[0098] Referring now to Figures 7 and 8, typical curves depicting the changes of functions w1(t), yM1(t), yM2(t), and u2(t) over time are shown, with characteristic event points identified numerically in the figures.

[0099] As shown in Figure 7, the drop in the first temperature T1 occurs at event points 1 and 3 due to factors such as gas flowing into the process chamber. Without the cascaded control of the previously described "freeze function," these temperature drops would cause the cascaded control to produce excessive reaction, as can be clearly seen from the temperature peaks of the second temperature T2 curve at event points 2 and 4.

[0100] By freezing the control variable u1(t) generated by the main controller to the value u1 before the onset of an event that may cause a short-term change in component temperature. freeze This allows for better control of component temperature.

[0101] Referring to Figure 8, the characteristic events and operations (also labeled with numbers) occurring during the aforementioned cascaded control execution process according to the method of the present invention will now be explained. The portion numbered 1 in the second temperature T2 (yM2(t)) curve represents the lower limit of the pyrometer's measurement range. During this period, the control variable u2(t) exhibits a constant curve, as shown in number 2.

[0102] Control begins at event point 3. At event point 4, a strong overshoot occurs at the second temperature T2, but this does not cause an overshoot in the temperature T1 curve (yM1(t)), see point 7.

[0103] The number 5 indicates the difference between the uncalibrated second temperature T2 and the set temperature determined by the function w1(t), which is due to the different surface characteristics of the object or component being measured.

[0104] At event point 6, the first temperature T1 precisely reaches the preset (planned) set temperature, wherein the measurement error of the non-contact measurement second temperature sensor 28 is compensated by calibration as described above.

[0105] List of reference numerals

[0106] 10, 110, 210 welding equipment

[0107] 12-element bracket, device components

[0108] 14 Conveyor Frames

[0109] 16 and 18 components

[0110] 20. Induction device, heat source

[0111] 22 Measurement Window

[0112] 24 First Temperature Sensor

[0113] 26 Second Temperature Sensor

[0114] 28 process chambers

[0115] R1 main controller

[0116] R2 from the regulator

Claims

1. A method for regulating the temperature of components (16, 18) to form a welded or sintered connection between the components (16, 18), the method comprising at least one controllable heat source (20) for providing thermal energy to the components (16, 18); wherein, The first temperature of the element (16, 18) or a component (12) of the welding or sintering apparatus (10, 110, 210) in thermal contact with the element (16, 18) is measured at at least one first temperature point by at least one first temperature sensor (24), the at least one first temperature sensor (24) being in thermal contact with the element (16, 18) or the component (12), and the element (16, 18) or the welding or sintering apparatus (10, 110, 210) in thermal contact with the element (16, 18) is measured in a non-contact manner at at least one second temperature point by at least one second temperature sensor (26). The second temperature of component (12); wherein the first temperature point and the second temperature point are spatially set to be far apart, such that a temperature gradient is expected to occur between the first temperature and the second temperature when the temperature changes; and wherein the measured second temperature is calibrated according to the measured first temperature to determine the calibrated second temperature, and wherein the heat source (20) is controlled at least according to the calibrated second temperature.

2. The method according to claim 1, characterized in that, The method is carried out in a settable process atmosphere, wherein setting the process atmosphere includes at least setting the material composition, pressure and / or temperature of the process atmosphere.

3. The method according to claim 1 or 2, characterized in that, The first temperature sensor (24) is selected from a set of at least thermistors, positive temperature coefficient thermistors, semiconductor temperature sensors, thermocouples and temperature sensors based on oscillation circuits, and / or the second temperature sensor (26) is a sensor configured to detect thermal radiation, and is preferably selected from a set of at least pyrometers, radiometers and thermopile.

4. The method according to any one of the preceding claims, characterized in that, The at least one heat source (20) is configured to transfer heat to the element (16, 18) or one or more of the components (12) in a contact or non-contact manner, and is preferably selected from a collection of electric, magnetic or electromagnetic field generators, preferably heating plates, induction heating elements or infrared radiators, which can be coupled to the element (16, 18) or component (12) at least by thermal coupling, inductive coupling or capacitive coupling.

5. The method according to any one of the preceding claims, characterized in that, In the process step of making a welding or sintering connection, the heat source (20) is controlled, and the calibration temperature is determined in at least one calibration step prior to the process step, wherein the calibration step includes generating and storing a corresponding calibration function, and determining a second calibrated temperature based on the second temperature obtained by measurement.

6. The method according to claim 5, characterized in that, A calibration step is performed before each process step, wherein the heat source (20) is controlled based on a previously determined calibration function in the process step.

7. The method according to claim 5 or 6, characterized in that, In the process steps, one or more calibration steps are also performed, preferably at a defined time point or at a time point when the temperature of the components (16, 18) has not changed substantially.

8. The method according to any one of claims 5 to 7, characterized in that, Before performing the process steps, a calibration function matching the component (16, 18) to be processed is selected from a plurality of calibration functions stored in a component-characteristic or part-characteristic manner, wherein, during the process steps, the heat source (20) is controlled based on the selected calibration function.

9. The method according to any one of claims 5 to 8, characterized in that, The calibration function is a linear function or a polynomial function, preferably a fourth-order polynomial function.

10. The method according to any one of the preceding claims, characterized in that, The control of the heat source (20) is achieved in a two-stage manner, wherein in the first stage, a corrected set temperature is determined based on a measured first temperature and a preset set temperature, and in the second stage, the output from the heat source (20) is controlled based on a measured or calibrated second temperature and the corrected set temperature.

11. The method according to any one of the preceding claims, characterized in that, The components (16, 18) to be connected are arranged on the main extension plane, wherein the first temperature sensor (24) is arranged on one side of the main extension plane, and the heat source (20) and the second temperature sensor (26) are arranged on the other side of the main extension plane; or, wherein the first temperature sensor and the second temperature sensor (24, 26) are arranged on one side of the main extension plane, and the heat source (20) is arranged on the other side of the main extension plane; or, wherein the first temperature sensor and the second temperature sensor (24, 26) and the heat source (20) are arranged on the same side of the main extension plane.

12. A welding or sintering apparatus (10, 110, 210) for establishing a welded or sintered connection between components (16, 18), the welding or sintering apparatus having at least one controllable heat source (20) configured to provide heat energy to be transferred to the components (16, 18); at least one first temperature sensor (24) arranged at at least one first temperature point, the at least one first temperature sensor (24) being in thermal contact with the components (16, 18) or a component (12) of the welding or sintering apparatus (10, 110, 210) in thermal contact with the components (16, 18), and configured to measure a first temperature of the components (16, 18) or the component (12); and at least one second temperature sensor (26) arranged at at least one second temperature point, the at least one second temperature sensor (26) being configured to measure the temperature of the components (16, 18) or the components (16, 18) in a non-contact manner. The second temperature of the component (12) of the thermally contacted welding or sintering apparatus (10, 110, 210); wherein the first temperature point and the second temperature point are spatially arranged to be far apart so that a temperature gradient is expected between the first temperature and the second temperature when the temperature changes; and a control unit is also provided, which is connected to the heat source (20) and the first temperature sensor and the second temperature sensor (24, 26), and is configured to perform the method according to any one of the preceding claims.

13. The welding or sintering apparatus (10, 110, 210) according to claim 12, characterized in that, The heat source (20) has a measurement window (22) that allows infrared radiation emitted by the elements (16, 18) or the components (12) of the welding or sintering apparatus (10, 110, 210) to propagate along the direction of the second temperature sensor (26).

14. The brazing or sintering apparatus (10, 110, 210) according to claim 13, characterized in that, A tube is provided in the measurement window, which is at least oriented toward the second temperature sensor (26) and configured to guide infrared radiation emitted by the elements (16, 18) or the components (12) of the welding or sintering apparatus (10, 110, 210) toward the second temperature sensor (26), and preferably shields the second temperature sensor (26) from infrared radiation not emitted by the elements (16, 18) or the components (12).

15. The welding or sintering apparatus (10, 110, 210) according to any one of claims 12 to 14, characterized in that, The elements (16, 18), at least one heat source (20), at least one first temperature sensor (24) and at least one second temperature sensor (26) are disposed in or on a hermetically sealed process chamber (28) having a settable process atmosphere, particularly a vacuum, wherein the second temperature sensor (24) is preferably disposed on the side of the heat source (20) away from the elements (16, 18).

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