Electronic assembly

Abstract

The invention relates to an electronic assembly (1), having - a main printed circuit board (2) and - a semiconductor component (28) arranged on the main printed circuit board (2), characterized by - a measuring printed circuit board (26) arranged in thermally conducting contact with the semiconductor component (28), and - a temperature sensor (16) arranged on the measuring printed circuit board (26) and configured to measure a temperature, on the basis of which a junction temperature (θ_J) of the semiconductor component (28) can be determined.

Description

[0001] 2024P11295 DE

[0002] 1

[0003] Description

[0004] Electronic arrangement

[0005] Technical field

[0006] The present invention relates to an electronic arrangement and a method for determining a junction temperature.

[0007] Technical background

[0008] The power dissipation of power semiconductors in an electronic circuit often represents the largest heat source within the circuit. To protect these semiconductors from irreversible damage due to overheating, while simultaneously ensuring their full thermal utilization up to their maximum operating temperature, it is essential to measure or estimate the junction temperature of the power semiconductors as accurately as possible. For this purpose, it is crucial to create a thermal path from a power semiconductor to a measurement point at a reference temperature that is as simple and reproducible as possible, as this allows for precise modeling of the thermal path.Knowing the reference temperature, the junction temperature of the power semiconductor can be reliably determined using a model of the thermal path, thus reliably protecting the power semiconductor from overload.

[0009] Fig. 1 shows a basic thermal equivalent circuit of a power semiconductor HL with the thermal path "chip C of the power semiconductor - package G of the power semiconductor - heat sink K - ambient U", which can be used for thermal modeling of the junction temperature 0_J. A point on the heat sink, for example, is suitable as the reference temperature measurement point, since its large thermal mass leads to a stable temperature measurement. The junction temperature 0_J ("J" for "Junction" (Temperature)) of the chip C is coupled to the package temperature 0_G by the thermal resistance R_th_JG, the package temperature 0_G is coupled to the heat sink temperature 0_K by the thermal resistance R_th_GK, and the heat sink temperature 0_K is coupled to the ambient temperature 0_U by the thermal resistance R_th_KU.

[0010] The less accurate the measurement of the reference temperature for the thermal model, the less accurate the determination of the junction temperature. Furthermore, 2024P11295 DE

[0011] Two additional thermal paths introduced into the thermal path "lengthen" or increase the complexity of the thermal model, leading to further inaccuracies. Therefore, efforts are made to keep the thermal path as short as possible, for example, by positioning the reference temperature measurement points as close as possible to the power semiconductor. In practice, however, other requirements such as manufacturability or electrical insulation may necessitate extending the thermal path. In such cases, it is essential to minimize the resulting inaccuracy in determining the junction temperature or reduce it to an acceptable level.

[0012] To measure the heatsink temperature as a reference temperature, it is known to press a temperature sensor against the heatsink using a screw connection in such a way as to ensure reproducible heat transfer. The sensor signal is then transmitted via a cable to an evaluation unit located on the printed circuit board (PCB). However, the screw connection requires additional process steps during the manufacturing of the electronic circuit and thus limits PCB production. Furthermore, such temperature sensors with screw connections and cables occupy a relatively large amount of installation space in an electronic circuit with power semiconductors. In addition, a temperature sensor equipped with a cable is significantly more expensive than an SMD NTC sensor, i.e., an NTC thermistor in the form of an SMD component (NTC = Negative Temperature Coefficient; SMD = Surface-Mounted Device).Mounting an SMD NTC sensor on a heatsink using a screw connection is generally not possible, as no pressure should be exerted on an SMD component; therefore, directly "clamping" the SMD NTC sensor, e.g., with a screw connection, is not feasible. As an alternative, any remaining insulating air gap between the SMD NTC sensor and the heatsink can be filled with thermally conductive filler materials such as a gap filler pad.

[0013] Fig. 2 shows a printed circuit board 2 on which two power semiconductor packages G are arranged. The power semiconductors are electrically connected via connection pins 6 to conductors 8 of an electrical circuit. A heat sink K is arranged on the side of the packages G, which have different heights, facing away from the printed circuit board 2. Two air gaps, located between the surface of the packages G and the heat sink K and having different thicknesses d1, d2, are filled with relatively thermally conductive gap filler pads 4, also called thermal sponges. Fig. 2 represents a cooling arrangement for a case in which the power semiconductor(s) are designed as surface-mount devices (SMDs) and an SMD NTC sensor is placed as close as possible to the power semiconductors in order to estimate their temperature. In this arrangement, the printed circuit board with 2024P11295 DE

[0014] 3

[0015] Current-carrying conductor tracks; furthermore, other components are also arranged on the circuit board, which also generate heat. Therefore, the SMD NTC sensor, which is located directly on the circuit board (= mainboard), also measures temperature influences that have nothing to do with the heat losses of the power semiconductor(s). Thus, a disadvantage of the arrangement sketched in Fig. 2 is that the temperature measurement is distorted by external influences from the mainboard, since the temperature sensor is located on the circuit board and therefore also measures the heat from current-carrying conductor tracks, which are necessary to supply current to the power semiconductor, and from other components.

[0016] It is also known to bend the connection pins of the THT MOSFET by 90° so that the heat-dissipating metallic surface of the semiconductor device (the so-called "heat sink pad," usually electrically connected to the drain pin) faces upwards towards a heat sink. The THT MOSFET can then be mechanically connected and fixed to the circuit board and the heat sink with a screw (THT = Through Hole Technology). The pressure exerted by the screw connection between the heat sink, THT MOSFET, and circuit board results in very good heat transfer between the THT MOSFET and the heat sink. Optionally, thermal paste can be applied between the THT MOSFET and the heat sink to further improve heat transfer. Such a horizontal arrangement of the THT MOSFET can be advantageous for space reasons, allowing a THT MOSFET to be housed in a single package.However, in other housings, a standing arrangement of the THT MOSFET may also be possible.

[0017] DE 10 2023200 324 A1 (Siemens AG) 2024.07.18 describes such an electronic arrangement with a through-hole technology (THT) component 2 with a plate-shaped housing 6. The housing 6 has a through-hole 8 and connection pins 4 protruding from one of the narrow sides 63, 64 of the housing 6. A screw 18, 20, which passes through the through-hole 8, holds a heat sink 14 to a front side 61 and a circuit board 16 to a rear side 62 of the housing 6. The connection pins 4 are bent at approximately 90 degrees so that their ends 41 can be inserted into contact holes 30 of the circuit board 16, as in a conventional "standing" arrangement of the THT components.

[0018] Instead of a complex wired temperature sensor with a screw connection on the heatsink, an SMD temperature sensor, hereinafter also referred to as an SMD sensing element, can be mounted on the back of the circuit board near the mounting screw (screw head or nut). The heat generated by the power semiconductor is first transferred to the heatsink, from there via the metal mounting screw to the back of the circuit board (bottom-side of the circuit board = bottom-side). 2024P11295 DE

[0019] 4

[0020] side of the circuit board (the side of the circuit board facing away from the power semiconductor) and via the screw head or nut of the mounting screw onto one or more copper layers of the circuit board and thus to the SMD temperature sensor, which is soldered directly to one of these copper layers.

[0021] Despite the additional thermal path represented by the mounting screw, the transition from the screw head or nut to the conductor tracks, and the SMD temperature sensor, the overall thermal path is still sufficiently short and simple to allow for a meaningful junction temperature measurement. This thermal path can be optimized by selecting a suitable screw material. For example, a copper screw conducts heat approximately eight times better, and an aluminum screw approximately four times better, than a steel screw. Similarly, using a screw with a large head can increase the contact area on the conductor track and thus improve heat transfer.The heat transfer from the screw head to the SMD temperature sensor can also be improved and adapted to specific requirements by appropriately designing the copper layers of the printed circuit board, both the outer and inner layers. If no electrical insulation is required between the SMD temperature sensor and the heat sink, the SMD temperature sensor can be soldered directly to the outer conductor track against which the screw head presses. If electrical insulation of the SMD sensor is required, at least one inner copper layer, thermally connected to the outer copper layer in the area of ​​the screw head via at least one via, can be used to transfer heat from the outer copper layer to the SMD sensor, thus heating it to approximately the temperature of the outer copper layer.

[0022] Figures 3 and 4 show an embodiment of such an arrangement of an SMD measuring element 16 on the back side 2.2 of a printed circuit board 2. The SMD measuring element 16 is designed as an NTC sensor, i.e., an electronic component whose resistance changes depending on the temperature. Based on a measurement of the resistance R of the NTC sensor 16 using Ohm's law R = U / l, the temperature of the NTC sensor 16 can be determined, and from this, using a thermal model, the temperature of the semiconductor can be deduced. Figure 3 shows the arrangement before the insertion of a screw, and Figure 4 shows the screw head 18 of an inserted screw. To ensure optimal heat conduction from the heat sink to the back side 2.2 of the printed circuit board 2, the area around the through-hole 14 on the back side 2.2 of the printed circuit board 2 is coated with a copper layer 10, so that the screw with its screw head 18 or nut makes direct contact with this 2024P11295 DE

[0023] 5

[0024] The copper layer 10 is present. In the variant shown in Figs. 3 and 4, the SMD measuring element 16 is electrically insulated from the heat sink; thus, there is no electrically conductive connection between the outer layer 10, against which the screw head 18 presses, and the heat sink. The arrangement in Figs. 3 and 4 shows two etched conductor tracks 8 that electrically contact the NTC sensor 16 and form a section of such a circuit, which is intended for measuring the resistance R of the NTC sensor 16.

[0025] Fig. 5 shows an alternative detail of an arrangement of an SMD measuring element 16 on the back side 2.2 of a printed circuit board 2, as shown in Figs. 3 and 4. A circular copper layer 10 is arranged on the back side 2.2 of the printed circuit board 2, on which a screw head 18 of a screw inserted through a through-hole in the printed circuit board 2 rests. The outer copper layer 10 below the screw head 18 is free of solder mask so that there is no additional thermal resistance between the screw head 18 and the copper layer 10. Thus, the SMD measuring element 16 is thermally connected to the heat-emitting semiconductor component in the best possible way.

[0026] The heat from the heat sink is transferred via the screw connection to the copper areas described in Figures 2 to 5, and thus directly to the SMD sensing element. The thermal path is precisely defined and, due to the tight tolerances of printed circuit board manufacturing, highly reproducible, enabling reliable and accurate thermal path modeling. Based on this thermal model, the junction temperature of a power semiconductor can be determined with good accuracy. By varying the distances between the copper layer and the SMD sensing element, different electrical insulation requirements (delayed air gap dielectric strength) can be achieved.

[0027] Regardless of whether an SMD NTC sensor is positioned on the top side of a printed circuit board in close proximity to the power semiconductor being measured (this method is particularly common with SMD power semiconductors, as the heat source, i.e., the chip, is located in close proximity to the circuit board, allowing the SMD NTC sensor to be placed very close to the semiconductor), or whether an SMD NTC sensor is positioned on the back side of a circuit board, as shown in Figures 3 to 5, a significant problem remains: because the circuit board carries current and "contains" all the other components of the electronic circuit, which also generate power losses, this can, since the components are not thermally decoupled, lead to an adverse influence on the measurement of the reference temperature, from which the junction temperature of the power semiconductor is determined using a temperature model. 2024P11295 DE

[0028] 6

[0029] Summary of the invention

[0030] The object of the present invention is therefore to provide an improved measuring arrangement for measuring a reference temperature of a semiconductor device. A further object of the present invention is to provide an improved measuring method.

[0031] This problem is solved by an electronic arrangement with the features specified in claim 1. The electronic arrangement includes a semiconductor device. The semiconductor device can be any electronic component that dissipates heat. Transistors can be bipolar transistors, FETs (e.g., MOSFET, JFET, SIT), IGBTs, GTOs, IGCTs, or other types of transistors. The semiconductor device can also be, for example, a triac, a thyristor, or a diode. The electronic arrangement includes a main circuit board that carries the semiconductor device and provides electrical contacts for electrical connections, e.g., terminal pins, of the semiconductor device. The main circuit board includes an electronic circuit in which the semiconductor device is a component. The electronic arrangement is designed such that the semiconductor device is mounted on the main circuit board.The electronic assembly also includes a measurement circuit board that carries a temperature sensor. The main circuit board and the measurement circuit board are two separate, spatially isolated circuit boards. The measurement circuit board is in thermally conductive contact with the semiconductor device; thus, solid-state thermal conduction occurs between the semiconductor device and the measurement circuit board, and consequently between the measurement circuit board and the temperature sensor located on the measurement circuit board. Heat is transferred from the semiconductor device to the measurement circuit board and into the area where the temperature sensor is located, for example, via vias and conductive layers that run through, in, or on the measurement circuit board. The temperature sensor on the measurement circuit board is configured to detect a temperature. The temperature detected by the temperature sensor is referred to as the reference temperature.Based on the temperature measured by the temperature sensor, the temperature of the semiconductor device, in particular its junction temperature, can be determined using a thermal model, also known as a temperature model. For this purpose, the junction temperature is calculated or modeled based on the temperature measured by the temperature sensor (= reference temperature).

[0032] This problem is also solved by a method with the features specified in claim 15. The method serves to determine a junction temperature of a semiconductor device in an electronic assembly. The semiconductor device is located at 2024P11295 DE

[0033] 7 of a main circuit board. In one process step, a measuring circuit board, on which a temperature sensor is mounted, is placed in thermally conductive contact with the semiconductor device. In a further process step, the temperature sensor detects a temperature, the so-called reference temperature, based on which the junction temperature of the semiconductor device is determined. A measuring and evaluation circuit can be used that employs a thermal model to calculate the junction temperature of the semiconductor device starting from the reference temperature.

[0034] The invention is based on the understanding that the main circuit board, which carries the semiconductor component, is not only exposed to the heat generated by the semiconductor component itself, but also to the heat generated by current-carrying conductors and other electrical and electronic components arranged on the main circuit board. Thus, a temperature sensor mounted directly on the main circuit board would measure a temperature that is not solely caused by the heat generated by the semiconductor component, but is also influenced by heat generated outside of the semiconductor component. The invention is based on the idea that by arranging the temperature sensor on a separate measuring circuit board spatially separated from the main circuit board, the temperature measurement can be almost completely decoupled from the thermal influences of the main circuit board carrying the semiconductor component.A major advantage of the invention is that the proposed temperature measurement is virtually unaffected by external influences from the main circuit board. The temperature sensor essentially measures only the temperature generated by the heat dissipated by the semiconductor component, and not the temperature of current-carrying traces, other components, etc., on the main circuit board. Positioning the temperature sensor on a separate measurement circuit board allows for a wide selection of suitable temperature sensors. Furthermore, this facilitates easy automation of manufacturing, thus reducing costs. The invention therefore offers a cost-effective yet highly accurate measurement method.

[0035] Embodiments of the invention

[0036] Advantageous embodiments and further developments of the invention are specified in the dependent claims. The method according to the invention can also be further developed according to the dependent apparatus claims, and vice versa.

[0037] According to a preferred embodiment of the invention, the measuring circuit board is arranged on the semiconductor device. The measuring circuit board has a surface separate from the semiconductor device. 2024P11295 DE

[0038] 8

[0039] The circuit board has a front side facing away from the semiconductor component and a back side facing the semiconductor component, with the temperature sensor located on the front side. An advantage of this design is that a relatively inexpensive SMD NTC sensor can be used on the circuit board. Heat from the semiconductor component is conducted to the circuit board and, via vias and relatively large conductive layers running through, in, or on the circuit board, is transferred to the area where the temperature sensor is located.

[0040] According to a preferred embodiment of the invention, the electronic assembly includes a fastening device that presses the measuring circuit board against the semiconductor device and the semiconductor device against the main circuit board. The fastening device can be a screw connection, a rivet connection, or any other fastening method, e.g., a (clamping) spring. An advantage of this is that the fastening element of the mounting device allows the measuring circuit board, the semiconductor device, and the main circuit board to be pressed together in such a way that relatively good heat conduction from the semiconductor device to the measuring circuit board takes place.

[0041] According to a preferred embodiment of the invention, the fastening device comprises a fastening element that is inserted through a through-hole extending through the measuring circuit board, the semiconductor device, and the main circuit board. The fastening element can be, for example, a screw or a rivet. An advantage of this is that a semiconductor device with a through-hole can be used, and effective pressure can be applied with a single fastening element of the fastening device: the measuring circuit board, the semiconductor device, and the main circuit board can be pressed together in such a way that relatively good heat conduction from the semiconductor device to the measuring circuit board takes place.

[0042] According to a preferred embodiment of the invention, the electronic assembly includes a heat sink that absorbs some of the waste heat produced by the semiconductor device by thermal conduction and dissipates it to its surroundings, usually air, by convection and thermal radiation. The heat sink can be made of aluminum, copper, or another suitable thermally conductive material. The electronic assembly is designed such that the semiconductor device is positioned between the heat sink and the main circuit board. The measuring circuit board is arranged on the heat sink. Heat is transferred from the heat sink to the measuring circuit board and dissipated, for example, by means of vias and conductive layers that pass through, in, or on the measuring circuit board. 2024P11295 DE

[0043] The current is directed to an area where the temperature sensor is located. Based on the temperature measured at the temperature sensor, the temperature of the semiconductor device, in particular the junction temperature, can be determined using a temperature model. For this purpose, the junction temperature is calculated or modeled based on the measured heatsink temperature (reference temperature). The advantage of using the heatsink temperature as the reference temperature lies in the heatsink's large mass: its high heat capacity ensures a very constant and therefore accurate temperature measurement.

[0044] According to a preferred embodiment of the invention, the measuring circuit board has a front side facing away from the heat sink and a back side facing the heat sink, with the temperature sensor being arranged on the front side of the measuring circuit board. An advantage of this is that an SMD NTC sensor, which is relatively inexpensive, can be used on the measuring circuit board. Heat from the heat sink is conducted to the measuring circuit board and, by means of vias and conductive layers that run through, in, or on the measuring circuit board, is transferred to an area where the temperature sensor is located.

[0045] According to a preferred embodiment of the invention, the electronics assembly comprises a fastening device that presses the measuring circuit board against the heat sink, the heat sink against the semiconductor device, and the semiconductor device against the main circuit board. The fastening device can be a screw connection, a rivet connection, or any other fastening method, e.g., a (clamping) spring. An advantage of this is that the fastening element of the fastening device allows the measuring circuit board, the heat sink, the semiconductor device, and the main circuit board to be pressed together in such a way that relatively good heat conduction from the semiconductor device to the measuring circuit board takes place.

[0046] According to a preferred embodiment of the invention, the mounting device has a fastening element that is inserted through a through-hole extending through the measuring circuit board, the heat sink, the semiconductor component, and the main circuit board. An advantage of this is that the fastening element of the mounting device allows the measuring circuit board, the heat sink, the semiconductor component, and the main circuit board to be pressed together in such a way that relatively good heat conduction from the semiconductor component to the measuring circuit board occurs. The fastening element can be, for example, a screw or a rivet. It is advantageous that a semiconductor component with a through-hole can be used and that effective pressure can be achieved with a single fastening element of the mounting device: the measuring circuit board is 2024P11295 DE.

[0047] 10

[0048] The circuit board, the semiconductor component and the main circuit board can be pressed together in such a way that relatively very good heat conduction takes place from the semiconductor component to the measuring circuit board.

[0049] According to a preferred embodiment of the invention, the electronic arrangement comprises a measuring and evaluation circuit which is connected to the temperature sensor via an electrical circuit and is suitable for determining the temperature of the temperature sensor. An advantage of this is that, based on the temperature measured at the temperature sensor, the temperature of the semiconductor component can be determined by the measuring and evaluation circuit using a temperature model.

[0050] According to a preferred embodiment of the invention, a first section of the circuit runs from the temperature sensor to the measuring and evaluation circuit along an electrically conductive element, e.g., a metal screw or a metal rivet, which is inserted through a through-hole that passes through the measuring circuit board, the heat sink, the semiconductor component, and the main circuit board. The electrically conductive element is a component of a mounting device that presses the measuring circuit board against the heat sink, the heat sink against the semiconductor component, and the semiconductor component against the main circuit board. An advantage of this is that a component of the mounting device simultaneously serves as the current path of the circuit that electrically connects the temperature sensor and the measuring and evaluation circuit.By using a component of a fastening device for contact, no additional components are required for the electrical circuit. The electrically conductive element of the fastening device can be a screw shank of a screw connection, a rivet of a riveted connection, or any other electrically conductive fastening method, e.g., a (clamping) spring.

[0051] According to a preferred embodiment of the invention, another section of the circuit runs from the temperature sensor to the measuring and evaluation circuit, starting at the temperature sensor along vias of the measuring circuit board, through the heat sink and the semiconductor device, along a connection pin, preferably the drain pin, of the semiconductor device, and along a conductor track of the main circuit board to the measuring and evaluation circuit. The semiconductor device has a heat-dissipating metallic surface, a so-called "heat sink pad," on an outer surface facing the heat sink, which is electrically connected to the drain pin of the semiconductor device. The circuit runs via this electrical connection. It is advantageous that the heat sink and the semiconductor device simultaneously serve as a current path.

[0052] Terminal 11 of the circuit serves to electrically connect the temperature sensor and the measurement and evaluation circuit. Due to the contact via the heat sink and the semiconductor component, no additional components are required for the circuit.

[0053] According to a preferred embodiment of the invention, the semiconductor component is a through-hole technology (THT) component. In this embodiment, the connection pins of the THT component are bent by 90° during prefabrication, so that the heat-dissipating metallic surface of the THT component (so-called "heat sink pad," usually electrically connected to the drain pin) faces the heat sink. This has the advantage that the THT component can be processed similarly to an surface-mount device (SMD) component, and the heat sink can be thermally connected very effectively to the THT component by means of the mounting device, e.g., a screw connection.

[0054] According to a preferred embodiment of the invention, the temperature sensor is a thermistor. A thermistor is a semiconductor temperature sensor whose electrical resistance changes by a relatively large amount even with relatively small temperature changes. Thermistors typically have a negative temperature coefficient (NTC), meaning that the electrical resistance of the thermistor decreases as the temperature increases; this property is referred to as "negative temperature coefficient" or "negative thermistor" behavior. The advantage of a thermistor is that it is relatively inexpensive and robust, since it is simply a resistor. However, any other type of temperature sensor or temperature-dependent resistor (PTC, PT100) is equally suitable.

[0055] According to a preferred embodiment of the invention, a thermally conductive layer is arranged between the semiconductor device and the heat sink. This is advantageous because it improves heat transfer from the semiconductor device to the heat sink. The thermally conductive layer can be a solid material (mat, film, fabric, etc.) or a thermal paste. If a section of the circuit from the temperature sensor to the measuring and evaluation circuit runs through the semiconductor device and the heat sink, the thermally conductive layer must not be completely insulating but must allow at least a small current to pass through it. A thermal paste can be advantageous here: due to its viscous properties, it is pushed away from electrical contact points of two pressed-together bodies, i.e., it does not form a completely electrically insulating layer between two bodies under pressure.Since thermistors typically have resistance values ​​in the higher kOhm range, the electrical connection via the thermal interface material must have low resistance, but not in the mOhm range, as high currents are not required. If the connection has a resistance of less than approximately 10 Ohms, this has no significant impact on temperature accuracy, as the value is less than 1% compared to the resistance of the thermistor. Furthermore, a suitable 2024P11295 DE can be used.

[0056] 12

[0057] The selection of the temperature measuring component can be optimized. For example, there are various NTCs that have resistances of 1 kΩ, 10 kΩ, or even 100 kΩ and higher at room temperature. The rest of the characteristic curve then behaves accordingly. The range in which an accurate measurement is possible can also be influenced by a series resistor.

[0058] According to a preferred embodiment of the invention, the back side of the measuring circuit board facing the heat sink is free of solder mask, which is electrically non-conductive. This has the advantage of improving heat transfer from the heat sink to the measuring circuit board.

[0059] Exemplary embodiments of the drawing

[0060] The invention will now be explained using several exemplary embodiments and the accompanying drawing.

[0061] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood through the following description of exemplary embodiments, which will be explained in more detail with reference to the drawings. The drawings are schematic and not to scale.

[0062] Fig. 6 shows a semiconductor component (transistor) in THT package;

[0063] Fig. 7 shows a side view of an electronic arrangement according to the invention, which includes the THT component of Fig. 8;

[0064] Fig. 8 is an enlarged section VIII of Fig. 7;

[0065] Fig. 9 shows section IX of Fig. 8;

[0066] Fig. 10 shows an oblique view of the electronics arrangement of Fig. 7;

[0067] Fig. 11 shows a top view of the electronics arrangement of Fig. 7;

[0068] Fig. 12 shows a section of a first embodiment of the electronic arrangement;

[0069] Fig. 13 shows a bottom view of a measuring circuit board of the electronic arrangement of Fig. 12; 2024P11295 DE

[0070] 13

[0071] Fig. 14 shows a semiconductor component (transistor) of the electronic arrangement of Fig. 12;

[0072] Fig. 15 shows a section of another embodiment of the electronics arrangement;

[0073] Fig. 16 shows different views of a measuring circuit board of the electronic arrangement of Fig. 15;

[0074] Fig. 17 shows an insulating sleeve of the electronic assembly of Fig. 15;

[0075] Fig. 18 shows a top view and a bottom view of a measuring circuit board of a further embodiment of the electronic arrangement;

[0076] Fig. 19 shows the measuring circuit board of Fig. 18 in section;

[0077] Fig. 20 shows a section of an electronics arrangement with a measuring circuit board according to Fig. 18;

[0078] Fig. 21 shows a section of another embodiment of the electronics arrangement;

[0079] Fig. 22 shows a view of a measuring circuit board of the electronic arrangement of Fig. 21;

[0080] Fig. 23 shows an electronic arrangement according to the invention with a semiconductor component (transistor) in SMD design;

[0081] Fig. 24 shows a side view of an electronics arrangement according to the invention without a heat sink; and

[0082] Fig. 25 shows a flowchart of a method according to the invention.

[0083] Detailed description of the exemplary implementations

[0084] Fig. 6 shows a semiconductor device 28 in THT package form with a plate-shaped housing G, which has a front side G.1, a back side G.2 opposite the front side G.1 and narrow sides G.3, G.4, which connect the front side G.1 and the back side G.2.

[0085] The semiconductor device 28 also has four connection pins 6 protruding from one of the narrow sides G.3. The connection pins 6 are bent approximately in their middle, at about 90 degrees towards the back side G.2, so that the ends of the connection pins 6, as in a 2024P11295 DE

[0086] 14 conventional “standing” arrangement of THT components that can be inserted into contact holes of a printed circuit board.

[0087] The package G can be made of plastic. The front side G.1 faces upwards towards a heat sink and has a heat-dissipating metallic surface of the semiconductor device, a so-called "heat sink pad," which is electrically connected to the drain pin D of the semiconductor device. For example, this could be a THT MOSFET 4-pin TO-247-4; however, it could also be any other suitable semiconductor device in a through-hole package. The narrow side G.4 facing the viewer has an edge G.5 where two surfaces (the package wall) of the narrow side G.4, inclined at a few degrees to each other, meet. The semiconductor device 28 also has a through-hole 14 in the plate-shaped package G, which forms a through-hole between the front side G.1 of the package G and the back side G.2 of the package G. The front side G.The housing G carries a thermal interface material (TIM) 38 made of a relatively good thermal conductor. This TIM serves to improve heat dissipation from the semiconductor device 28 by filling an air gap between the housing G of the semiconductor device 28 and a heat sink K mounted on the housing G, thus improving heat conduction from the semiconductor device 28 to the heat sink K. The term "relatively good thermal conductor" in the context of the thermal interface material 38 means that its thermal conductivity should be significantly better than that of air, which is a poor conductor of heat. Therefore, the thermal interface material 38 should ideally be free of air inclusions. Additionally, a thermal paste can fill any air gaps that may be present.

[0088] The thermal interface layer 38 also has a recess that aligns with the through-hole in the semiconductor device 28. The thermal interface layer 30 can be a solid material (mat, film, fabric, etc.) or a thermal paste.

[0089] Figures 7 to 9 show a side view of an electronic assembly comprising the semiconductor device 28 from Figure 8. In addition to the semiconductor device 28, the electronic assembly includes a thermal interface layer 38, a heat sink K, a main circuit board 2 with contact holes 36, and a measuring circuit board 26 mounted on the heat sink K, which carries a temperature sensor 16. The semiconductor device 28 is positioned between the heat sink K and the main circuit board 2. The heat sink K has a plate-shaped base 42, from the top of which cooling fins 40 project. 2024P11295 DE

[0090] 15

[0091] The electronic assembly also includes an electrically conductive screw 18, 19, 32, 34, which is inserted through a through-hole 14 that passes through the measuring circuit board 26, the heat sink K, the thermal interface material 38, the semiconductor device 28, and the main circuit board 2. The screw 18, 19, 32, 34 serves as a fastening device that presses the measuring circuit board 26 against a top surface K.1 of the heat sink K, a bottom surface K.2 of the heat sink K against the semiconductor device 28, and against the thermal interface material 38 arranged between the heat sink K and the semiconductor device 28, and the semiconductor device 28 against the main circuit board 2. This pressure can be achieved by means of a screw head 19, which is supported on a top surface 26.1 of the measuring circuit board 26 and a screw nut 34, which is screwed onto a threaded screw end 32 of the screw 18, 19 and is located on a rear surface 2.2 of the main circuit board 2 supports.

[0092] The electronic arrangement also includes a measuring and evaluation circuit 52, which is arranged on a front side 2.1 of the main circuit board 2. The measuring and evaluation circuit 52 is connected to the temperature sensor 16 by a circuit not shown in Fig. 9 and is suitable for evaluating measurement signals from the temperature sensor 16.

[0093] The connection pins 6 each have a starting section 44 protruding from the housing G, a final section 48 inserted into a contact hole 36 of the main circuit board 2, and a bent section 46 arranged between the starting section 44 and the final section 48, such that the final sections 48 of the connection pins 6 extend through the contact holes 36 of the circuit board 2 and form electrical contacts there according to the through-hole technology (THT) process. The bending 46 of the connection pins 6, e.g., the connection pins 6 are bent by approximately 90 degrees during prefabrication, makes it possible to accommodate the semiconductor component 28 in a limited installation space, so that the cooling pad 38 faces upwards, i.e., is located on the front side G.1 of the housing G facing away from the circuit board 2. This adaptation allows the base body 42 of the heat sink K to be mounted on the front side G.1 of the semiconductor device 28 and thus parallel to the circuit board 2.

[0094] Fig. 8 shows an enlarged section VIII of Fig. 7, and Fig. 9 shows a section IX of Fig. 8. The measuring circuit board 26 is arranged in a space between two adjacent cooling fins 40 of the heat sink K, with its rear side 26.2 resting on the top side K.1 of the base body 42 of the heat sink K. The measuring circuit board 26 is pressed against the base body 42 of the heat sink K by the screw head 19 of the screw 18. 2024P11295 DE

[0095] 16 pressed. On the front side 26.1 of the measuring circuit board 26, the temperature sensor 16 is arranged, which can be designed, for example, as an SM D-NTC sensor.

[0096] Fig. 10 shows an oblique view of the electronics arrangement of Fig. 7, and Fig. 11 shows a top view of the electronics arrangement of Fig. 7. The temperature sensor 16 is located on the front surface 26.1 of the measuring circuit board 26 at a relatively short distance from the screw head 19 of the screw 18. The measuring circuit board 26 projects beyond the edge of the heat sink K at one of its two longitudinal ends. In this projecting area of ​​the measuring circuit board 26, the measuring circuit board 26 has an electrical connection point 60, from which an electrical connecting element 50 in the form of an electrically conductive pin extends downwards to the front surface 2.1 of the main circuit board 2. A first section of the circuit 56, which connects the measuring and evaluation circuit 52 to the temperature sensor 16, runs through this, for example, metallic pin 50; another section of the circuit 56 may run along the screw 18.Alternatively, a first section of the circuit 56 can pass through the metallic pin 50 and another section through a “DrainPad” of the semiconductor component 28 and the heat sink K.

[0097] Fig. 12 shows a section of a first embodiment of the electronic arrangement, in which a circuit 56, 56.1, 56.2 connecting the temperature sensor 16 to the measuring and evaluation circuit 52 runs via a drain connection pin 6 of the semiconductor component 28. A first heat current flows from the heat-generating semiconductor component 28. <t>1. Heat flows via the thermal conductivity layer 38 to the heat sink K. A second heat flow flows from the heat sink K. <t>2 to the measuring circuit board 26. A third heat flow flows from the measuring circuit board 26. <t>3 to the temperature sensor 16. The temperature sensor 16 is connected to the measuring and evaluation circuit 52 by a circuit 56. A first section 56.1 of the circuit 56 runs from the temperature sensor 16 via a conductor 8 on the measuring circuit board 26 to the connection point 60 and further via the metal pin 50 attached to the connection point 60 to the measuring and evaluation circuit 52. A second section 56.2 of the circuit 56 from the measuring and evaluation circuit 52 back to the temperature sensor 16 runs via a conductor 8 on the main circuit board 2 to the connection pin 6 and from there via the electrically conductive parts of semiconductor component 28, thermal interface 38, heat sink K and via vias of the measuring circuit board 26 to the temperature sensor 16.Current can flow from the drain connection pin 6 to a heat-dissipating metallic surface of the semiconductor device 28, the so-called "heat sink pad," because this surface is electrically connected to the drain pin 6. The thermal interface material 38 must not be completely electrically insulating, but must allow at least a small current to pass through it; a thermal paste can be advantageously used here. 2024P11295 DE.

[0098] 17. Due to its viscous properties, it is pushed away from electrical contact points of two bodies pressed together, i.e., it does not form a continuous electrically insulating layer between two bodies under pressure.

[0099] Fig. 13 shows a bottom view of a measuring circuit board 26 of the electronic assembly of Fig. 12. The underside of the measuring circuit board 26 is made of copper and is free of solder mask to ensure optimal thermal conductivity. This results in a flat connection to the heat sink K, allowing heat to penetrate the copper surface optimally. The heat generated by the semiconductor component 28 enters the heat sink K and from there, via the metallic interface between aluminum (heat sink K) and copper (underside of the measuring circuit board 26), reaches the measuring circuit board 26. Electrical and / or thermal vias 12 optimize the heat path to the top side of the measuring circuit board 26, so that the temperature of the temperature sensor 16 can be almost identical to that of the heat sink K. Pin 50 can be configured as a plug-in pin or a solder pin. However, any other possible electrical connection, such as a cable, can also be used.

[0100] Fig. 14 shows a TO-247-4 4-pin THT MOSFET, which, like any other suitable semiconductor device, can be used as a semiconductor device 28 in an arrangement according to the invention. On the left is the back side G.2 of the semiconductor device 28, which, in the arrangement shown in Fig. 12, faces the main circuit board 2. On the right is the front side G.1 of the semiconductor device, which, in the arrangement shown in Fig. 12, faces the heat sink K. The front side G.1 has a heat-dissipating metallic surface 30 of the semiconductor device 28, a so-called "heat sink pad." One of the four connection pins 6, typically the drain connection pin D, is electrically connected to the "heat sink pad." This has the advantage that the heat sink can be thermally connected very effectively to the THT MOSFET.

[0101] Fig. 15 shows a section of a further embodiment of the electronic arrangement, in which a circuit 56, 56.1, 56.2 connecting the temperature sensor 16 to the measuring and evaluation circuit 52 runs over a screw 18 serving as a fastening device. The components can be pressed together by the screw 18. This pressure can be achieved by means of a screw head 18, which is supported on a top surface 26.1 of the measuring circuit board 26, and a nut 34, which is screwed onto a threaded end 32 of the screw 18, 19 and is supported on a rear surface 2.2 of the main circuit board 2. The nut 34 can be designed as a solder nut. 2024P11295 DE

[0102] 18

[0103] A first heat flow flows from the heat-generating semiconductor component 28. <t>1. Heat flows via the thermal conductivity layer 38 to the heat sink K. From the heat sink K, a second heat flow 02 flows to the measuring circuit board 26. From the measuring circuit board 26, a third heat flow 03 flows to the temperature sensor 16. The temperature sensor 16 is connected to the measuring and evaluation circuit 52 by a circuit 56.

[0104] A first section 56.1 of the circuit 56 runs from the temperature sensor 16 via vias of the measuring circuit board 26 and the electrically conductive parts of the heat sink K, thermal interface material 38, and semiconductor device 28 to the terminal pin 6 of the semiconductor device 28 and via a conductor 8 running on the main circuit board 2 to the measuring and evaluation circuit 52. Current can flow from a heat-dissipating metallic area of ​​the semiconductor device 28, the so-called "heat sink pad," to the drain terminal pin 6, since this area is electrically connected to the drain pin 6. The thermal interface material 38 must not be completely electrically insulating, but must allow at least a small current to pass through it; a thermal paste can be advantageous here: due to its viscous properties, it is pushed away from electrical contact points of two bodies pressed together, i.e.,It does not form a continuous electrically insulating layer between two bodies under pressure.

[0105] A second section 56.2 of the circuit 56, running from the measuring and evaluation circuit 52 back to the temperature sensor 16, extends via a via 12 to the underside 2.2 of the main circuit board 2, then via a conductor 8 running along the underside 2.2 of the main circuit board 2 to a screw nut 32, along the screw shaft 18 through the stacked components to a copper layer 10 on which the screw head 19 rests. It is important that this copper layer 10 is free of solder mask in the area where the screw head 19 rests, as otherwise the electrically conductive connection will be interrupted: solder mask is not electrically conductive. From the copper layer 10, the second section 56.2 of the circuit 56 runs via a conductor 8 on the front side 26.1 of the measuring circuit board 26 to the temperature sensor 16.

[0106] To prevent a short circuit between both sections 56.1 and 56.2 in the area of ​​the electrically conductive heat sink K or the thermal interface material 38, an electrically insulating sleeve 62 is placed around the screw shaft 18. This sleeve 62 ensures that the screw 18 and the heat sink K do not make electrical contact. This can be achieved relatively easily with a thin plastic sleeve 62, which is inserted into the bore of the heat sink K and penetrated by the screw 18. The bore in the semiconductor device 2024P11295 DE

[0107] 19

[0108] 28 is usually already insulated; therefore, no sleeve is needed there. Fig. 17 shows an embodiment of such a plastic sleeve 62.

[0109] If technically feasible, precise screw positioning may suffice, provided it is ensured that the screw does not touch the heatsink's bore. Theoretically, the bore could be made with a larger diameter than the screw diameter, and if the screw sits exactly in the center of the bore, a plastic sleeve for insulation might not be necessary. However, tolerances are usually so tight that such an arrangement without a plastic sleeve would be too unreliable, partly because the material can settle or warp over time. In principle, though, a solution without an insulating plastic sleeve would also be conceivable.

[0110] Since NTCs typically have values ​​in the higher kΩ range, the electrical connection via screw 18 must have low resistance, but not in the mΩ range, as no high currents need to be carried here. If the electrical connection has a resistance of less than approximately 10 Ω, this has no significant impact on temperature accuracy, as the value is less than 1% compared to the resistance of the NTC. Measurements have shown that this connection is indeed in the range of less than 1 Ω. The "other" potential is transferred to the main circuit board via the heatsink and the thermal pad or a connection pin. This connection is also very electrically conductive. Thermal paste optimizes the thermal chain; however, electrically non-conductive or very poorly conductive pastes should be used here to prevent an electrical connection from the screw to the heatsink.

[0111] The configuration of the electronics shown in Fig. 15 has the advantage that no additional pin 50 is required for the circuit 56 connecting the temperature sensor 16 and the measuring and evaluation circuit 52. This saves both costs and space, which can then be used for additional volume of the heat sink K. Furthermore, the measuring circuit board 26 can be made smaller, since it no longer needs to extend beyond the heat sink K. It only needs to be minimally larger than the screw head 19, allowing the temperature sensor 16 to be positioned next to the screw head 19.

[0112] Fig. 16 shows various views of a measuring circuit board 26 of the electronic arrangement of Fig. 15. The right view is a top view of the measuring circuit board 26: a copper layer 10 is arranged ring-shaped around the through hole 14 of the measuring circuit board 26 on the top surface 26.1 of the measuring circuit board 26, on which a screw head 19 of a 2024P11295 DE

[0113] 20

[0114] The screw 18 is located in the through-hole 14, as illustrated in the middle view of the front side 26.1 of the circuit board 26. The middle view of the front side 26.1 of the circuit board 26 also illustrates that a first electrical contact of the temperature sensor 16 is electrically connected to this copper layer 10 by a conductor 8. A second electrical contact of the temperature sensor 16 is electrically connected to an outer conductor layer 22 on the back side 26.2 of the circuit board 26 by a via 12, as illustrated in the left view of the back side 26.2 of the circuit board 26. A significant portion of the heat emitted by the semiconductor device 28 is absorbed by the heat sink; some of this heat is then transferred by the heat sink to the outer conductor layer 22 on the back side 26.2 of the circuit board 26.From there, heat is conducted via the vias 12 of the measuring circuit board 26 to the front side 26.1 of the measuring circuit board 26, on which the temperature sensor 16 is located. The temperature sensor 16 is thus "surrounded" by some of the heat emitted by the semiconductor component 28. The temperature sensor 16 is a thermistor, as indicated by the corresponding circuit symbol in Fig. 16.

[0115] The electrical resistance of the temperature sensor 16 is measured in an electrical circuit 56, which is shown in the left and center views. A voltage between two electrical potentials is applied to the temperature sensor 16: the copper layer 10 and the first electrical contact of the temperature sensor 16 are at a first electrical potential Poti, while the conductor layer 22 on the back 26.2 of the measuring circuit board 26, the vias 12, and the second electrical contact of the temperature sensor 16 are at a second electrical potential Pot2. The circuit also includes a measuring and evaluation circuit (not shown in Fig. 16) that determines the electrical resistance of the thermistor 16 and, from this, the temperature of the thermistor 16 and, using a temperature model, the temperature of the semiconductor device. A voltage, e.g., 3 V, can be applied either via a voltage divider, e.g.,A series resistor or a constant current source can be used. A constant, known current, e.g., 1 mA, is passed through the temperature-dependent electrical resistance of the NTC sensor. Using Ohm's law R=U / I, where U is the measured voltage and I is the known value of the constant current, the current resistance R of the NTC sensor (= thermistor) can be calculated. Based on an RT curve stored, for example, in a data memory, which defines a relationship R = f(T) between temperature T and the resistance R of the NTC sensor, the temperature T at the NTC sensor can be determined from the resistance R of the NTC sensor. From this, the junction temperature of the semiconductor device can be calculated using a thermal model. 2024P11295 DE.

[0116] 21

[0117] Fig. 18 shows a measuring circuit board 26 according to a further embodiment of the electronic arrangement. The front side 26.1 of the measuring circuit board 26 has a pair of contact pads 64 to which a thermistor temperature sensor 16 can be electrically connected. The contact pads 64 are each electrically connected by means of conductor tracks 8 to an electrical connection point 60, which extends through the measuring circuit board 26 to the back side 26.2 of the measuring circuit board 26 by means of a via. The electrical connection points 60 can each be electrically connected to a measuring and evaluation circuit, for example by means of pins or cable connections. The front side 26.1 of the measuring circuit board 26 also has a copper layer 10 that extends around the through-hole 14, but maintains a distance A (insulation gap) from the contact pads 64 and the electrical connection points 60. The back side 26.2 of the measuring circuit board 26 carries a copper layer 10 that extends below the contact surfaces 64, but maintains a distance A from the electrical connection points 60. The copper layers serve exclusively to conduct waste heat from the semiconductor component to the thermistor temperature sensor 16, but do not form part of a circuit for measuring the resistance of the thermistor temperature sensor 16. The circuit for measuring the resistance of the thermistor temperature sensor 16 is carried exclusively via the conductor tracks 8 and the electrical connection points 60.

[0118] Fig. 19 shows a section through the measuring circuit board 26 of Fig. 18. If the reference potential of the thermistor temperature sensor does not correspond to that of the semiconductor component or the heat sink, the measuring circuit board can also be designed to be electrically insulated but still thermally conductive. To achieve the best possible thermal coupling, a multilayer structure of the measuring circuit board is advantageous. For example, with a 4-layer measuring circuit board... The following structure is conceivable: The measuring circuit board 26 has the following layers, counting from the front 26.1 to the back 26.2: an outer conductor layer 22 (layer L1), an insulating layer 25 (prepreg P1), an inner conductor layer 24 (layer L2), an insulating layer 25 (core CR), an inner conductor layer 24 (layer L3), an insulating layer 25 (prepreg P2), and an outer conductor layer 22 (layer L4). The conductor layers 22 and 24 are preferably formed as copper layers.From layer L1, the copper layer 10, the contact pads 64, the conductor tracks 8 and the connection points 60 on the front side 26.1 of the measuring circuit board 26 in Fig. 18 are etched. The connection points 60 can also be SMD.

[0119] The inner layers L2 and L3 allow heat to reach relatively close to the thermistor temperature sensor 16. Through-hole connections 12.1 from layer L4 to L2, the 2024P11295 DE

[0120] 22 Thermal path optimized: In order to transfer the heat from the heat sink, which is located at layer L4, to the thermistor temperature sensor 16 as efficiently as possible, the two vias 12.1 , 12.2 create the best possible thermal paths from layer L2 to layer L4 due to the very good conductivity of copper.

[0121] The insulation gap A is then created via the prepreg P1 between layers L1 and L2: The smaller the distance between layers L1 and L2, the better the thermal conductivity can be, but the lower the insulation properties. The structure must be designed and optimized with regard to the electrical insulation concept: Depending on the requirements, the distances between the layers and between the copper areas within the respective layers must be calculated and selected accordingly.

[0122] Fig. 20 shows a cross-section of an electronics arrangement with a measuring circuit board 26 according to Fig. 18. Since the circuit 56, which is provided for measuring the resistance of the NTC sensor 16, is routed independently of the screw 18 and independently of the heat sink K, namely via two conductor tracks 8 to two connection points 60 on the measuring circuit board 26, the measuring and evaluation circuit can be placed at any location, e.g., on a different circuit board than the one that carries the semiconductor component. The electrical connection 50 between the two connection points 60 and the measuring and evaluation circuit 52 can in this case be designed as a fixed line, e.g., two pins or a two-pin header, or as a flexible line, e.g., an insulated two-wire line. The electrical connection 50 can extend upwards or downwards from the two connection points 60.

[0123] Fig. 21 shows a section of another embodiment of the electronic arrangement. Here, the circuit 56, which connects the measuring and evaluation circuit 52 with the temperature sensor 16, runs on one side 56.1 via an electrical connecting element 50 from the measuring circuit board 26 to the measuring and evaluation circuit 52 and on the other side 56.2 along an electrically conductive element 18, which runs through the measuring circuit board 26, the heat sink K, the semiconductor component 28 and the main circuit board 2 and is part of a fastening device 18, 19, 32, 34, which presses the measuring circuit board 26 against the heat sink K, the heat sink K against the semiconductor component 28 and the semiconductor component 28 against the main circuit board 2. The electrically conductive element 18 of the fastening device 18, 19, 32, 34 can be a screw shank of a screw connection or a rivet of a riveted connection. 2024P11295 DE

[0124] 23

[0125] Fig. 22 shows an arrangement of a temperature sensor 16, an NTC sensor, on a measuring circuit board 26 according to the electronic arrangement of Fig. 21. The arrangement shows a copper layer 10 on which an etched conductor track 8 is located. This track electrically contacts a first contact of the NTC sensor 16 and is part of a first section of a circuit designed to measure the resistance R of the NTC sensor 16. The etched conductor track 8 continues on the top surface of the measuring circuit board 26 to pin 50, which provides an electrical connection to the measuring and evaluation circuit.

[0126] A second contact of the NTC sensor 16 is soldered to the copper layer 10, which is located in a second section of the circuit designed to measure the resistance R of the NTC sensor 16. The copper layer 10 is electrically connected by means of a screw 18 to a conductor 8 on the back side 2.2 of the main circuit board 2 and from there to the measuring and evaluation circuit 52 via a via 12 of the main circuit board 2. The measurement of the resistance R of the NTC sensor 16 is carried out using the measuring and evaluation circuit 52, e.g., a controller; both the NTC sensor 16 and the measuring and evaluation circuit 52 are located in the same circuit.

[0127] To optimize the thermal connection of the SMD measuring element, it is recommended to place a copper surface extending below the NTC sensor 16 in at least one inner layer of the measuring circuit board 26 and to thermally connect this inner layer copper surface(s) to the outer layer 10 in the contact area of ​​the screw head 18, preferably with copper-filled vias 12, so that the heat is conducted directly below the NTC sensor 16 and can heat it.

[0128] Different insulation requirements can be achieved by varying the distances of the copper area 10 to the NTC sensor 16 and to the conductor track 8 and / or the distances of the PCB layer structure of the measuring circuit board 26.

[0129] Because the second contact of the NTC sensor 16 is soldered to the copper layer 10, which is pressed against by the screw head, a very good thermal connection of the NTC sensor 16 can be achieved. However, this type of connection depends on the electrical architecture of the hardware. If the NTC sensor 16 is at the same electrical reference potential as the heatsink being measured, the NTC sensor 16 can be soldered directly on one side, as shown in Fig. 22.

[0130] If the temperature sensor 16 is an NTC sensor, an electrical connection is made from the temperature sensor 16 to the measuring and evaluation circuit 52 2024P11295 DE

[0131] 24 is required to evaluate the temperature-dependent electrical resistance of the temperature sensor 16. Depending on the reference potential of the evaluation circuit, one or two pins may be necessary. In the present case shown in Fig. 21, one pin 50 is sufficient, since the "other" potential is established via the electrical connection through the screw 18.

[0132] Fig. 23 shows a side view of an electronic arrangement according to the invention with a semiconductor device 28 (transistor) in SMD package. The semiconductor device 28 (transistor) in SMD package can, for example, be a TOLT (TO-Leaded Top-side Cooling), which are offered, for example, by Infineon Technologies AG. In addition to the semiconductor device 28, the electronic arrangement comprises a thermal interface 38, a heat sink K, a main circuit board 2, and a measuring circuit board 26 arranged on the heat sink K, which carries a temperature sensor 16. The semiconductor device 28 is arranged between the heat sink K and the main circuit board 2. The heat sink K has a plate-shaped base 42, from the top of which cooling fins 40 project.

[0133] The electronic assembly also includes two electrically conductive screws 18, 19, 32, 34, which are inserted through through holes passing through the measuring circuit board 26, the heat sink K, and the main circuit board 2. The screws 18, 19, 32, 34 serve as fastening devices that press the measuring circuit board 26 against a top surface of the heat sink K, a bottom surface of the heat sink K against the semiconductor device 28 and against the thermal interface 38 located between the heat sink K and the semiconductor device 28, and the semiconductor device 28 against the main circuit board 2. This pressure can be achieved by means of screw heads 18, which are supported on a top side of the measuring circuit board 26, and by means of screw nuts 34, which are each screwed onto a threaded screw end 32 of the screws 18, 19 and are supported on a rear side 2.2 of the main circuit board 2.The connection pins 6 of the semiconductor component 28 are electrically connected via conductor tracks, e.g., by solder joints. A measuring and evaluation circuit, which uses a thermal model to calculate the junction temperature of the semiconductor component based on the reference temperature measured by the temperature sensor 16, has been omitted from Fig. 23 to avoid cluttering the drawing; however, such a measuring and evaluation circuit is part of the electronic arrangement and can be located, for example, on the front side of the main circuit board 2, perhaps next to the semiconductor component 28.

[0134] In contrast to the electronic arrangement shown in Fig. 7 with a THT semiconductor component 28, the SMD semiconductor component 28 in the electronic arrangement shown in Fig. 23 does not have a through-hole; nevertheless, to enable the SMD semiconductor component 28 to be used in a way that allows ...

[0135] To enable the SMD semiconductor component 28 to be pressed against the heat sink, the heat sink K extends beyond the SMD semiconductor component 28 on both sides: thus, the SMD semiconductor component 28 can be pressed against the heat sink K using the two screws 18, which pass through the protruding section of the heat sink K. Here, the measuring circuit board 26 can be designed such that one or both of the screws 18 form a current path by which the temperature sensor 16 is electrically connected to a measuring and evaluation circuit arranged on the main circuit board 2.

[0136] Fig. 24 is a side view of an electronics arrangement 1 according to the invention without a heat sink. The arrangement largely corresponds to the electronics arrangement shown in Fig. 7, with the essential difference that the electronics arrangement shown in Fig. 7 has a heat sink, whereas the electronics arrangement shown in Fig. 24 does not: in the electronics arrangement shown in Fig. 24, the semiconductor component 28 releases only enough heat to be dissipated by the electronics arrangement without a separate heat sink. The measuring circuit board 26, which carries the temperature sensor 16, sits directly on the thermal interface material 38.

[0137] Like the electronics assembly shown in Fig. 7, the electronics assembly shown in Fig. 24 also has an electrically conductive screw 18, 19, 32, 34 which is inserted through a through-hole 14 that passes through the measuring circuit board 26, the thermal interface material 38, the semiconductor device 28, and the main circuit board 2. The screw 18, 19, 32, 34 serves as a fastening device that presses the measuring circuit board 26 against the thermal interface material 38, the thermal interface material 38 against the semiconductor device 28, and the semiconductor device 28 against the main circuit board 2. This pressure can be achieved by means of a screw head 19, which is supported on a top side of the measuring circuit board 26 and a screw nut 34, which is screwed onto a threaded screw end 32 of the screw 18, 19 and is supported on a rear side 2.2 of the main circuit board 2.

[0138] Fig. 25 is a flowchart of a method according to the invention for determining the junction temperature of a semiconductor component in an electronic assembly. The semiconductor component is arranged on a main printed circuit board.

[0139] In a first process step 71, a measuring circuit board, on which a temperature sensor is arranged, is placed in thermally conductive contact with the semiconductor device. In a second process step 72, the temperature sensor detects a temperature, the so-called reference temperature, on the basis of which the junction temperature of the semiconductor device is determined by means of thermal modeling. 2024P11295 DE

[0140] 26

[0141] Reference symbol list

[0142] 2 Main circuit board, motherboard

[0143] 2.1 Front of 2

[0144] 2.2 Back of 2

[0145] 4 Gap Filler Pads

[0146] 6 connection pins

[0147] 8 conductor track

[0148] 10 copper layers

[0149] 12 Via (vertical interconnect access)

[0150] 14. Borehole, through hole

[0151] 16 Temperature sensor

[0152] 18 screw

[0153] 19 screw head

[0154] 22 conductor layer, external

[0155] 24 conductor layers, internal

[0156] 25 Insulation layer

[0157] 26 Measuring circuit board

[0158] 26.1 Front of 26

[0159] 26.2 Back of 26

[0160] 28 Semiconductor components

[0161] 30 heat-emitting surface area of ​​28 ("heat sink pad")

[0162] 32 screw ends

[0163] 34 screw nuts

[0164] 36 contact holes

[0165] 38 Thermal conductivity layer, TIM

[0166] 40 cooling fins from K

[0167] 42 Basic bodies of K

[0168] 44 Initial section of 6

[0169] 46 bend section of 6

[0170] 48 End section of 6

[0171] 50 Electrical connecting element

[0172] 52 Measuring and evaluation circuit

[0173] 56 Circuit

[0174] 56.1 Section of 56

[0175] 56.2 Section of 56 2024P11295 DE

[0176] 60 Connection point, electrical

[0177] 62 Insulation sleeve

[0178] 64 contact area

[0179] 71st process step

[0180] 72nd process step

[0181] C chip, power semiconductors (MOSFET, IGBT, etc.)

[0182] CR core d1 thickness, first d2 thickness, second

[0183] A distance, insulation-

[0184] G Housing

[0185] G.1 Front of G

[0186] G.2 Reverse side of G

[0187] G.3 Narrow side of G

[0188] G.4 Narrow side of G

[0189] G.5 edge at G

[0190] K heat sink

[0191] K.1 Top side of K

[0192] K.2 Underside of K

[0193] L1 position, conductive

[0194] L2 position, conductive

[0195] L3 position, conductive

[0196] L4 position, conductive

[0197] P1 position, insulating

[0198] P2 position, insulating

[0199] R_th_GK thermal resistance

[0200] R th JG thermal resistance

[0201] R_th_KU thermal resistance

[0202] U surroundings

[0203] 0_G Case temperature

[0204] 0_J junction temperature

[0205] 0 K heatsink temperature

[0206] 0_U Ambient temperature

[0207] <t>1 Heat flow, first

[0208] 02 Heat flow, second

[0209] 03 Heat flow, third< / t> < / t> < / t> < / t> < / t>

Claims

2024P11295 DE 28 Patent claims 1. Electronic arrangement (1), comprising - a main circuit board (2) and - a semiconductor device (28) arranged on the main circuit board (2), characterized by - a measuring circuit board (26) which is arranged in thermally conductive contact with the semiconductor device (28), and - a temperature sensor (16) which is arranged on the measuring circuit board (26) and is configured to detect a temperature on the basis of which a junction temperature (0_J) of the semiconductor device (28) can be determined.

2. Electronic arrangement according to claim 1, wherein the measuring circuit board (26) is arranged on the semiconductor device (28), wherein the measuring circuit board (26) has a front side (26.1) facing away from the semiconductor device (28) and a back side (26.2) facing the semiconductor device (28), wherein the temperature sensor (16) is arranged on the front side (26.1).

3. Electronic arrangement according to one of the preceding claims, comprising a fastening device (18, 19, 32, 34) which presses the measuring circuit board (26) against the semiconductor component (28) and the semiconductor component (28) against the main circuit board (2).

4. Electronic arrangement according to claim 3, wherein the fastening device (18, 19, 32, 34) has a fastening element (18) which is inserted through a through hole (14) which passes through the measuring circuit board (26), the semiconductor component (28) and the main circuit board (2).

5. Electronic arrangement according to claim 1, comprising a heat sink (K), wherein the semiconductor device (28) is arranged between the heat sink (K) and the main circuit board (2), and wherein the measuring circuit board (26) is arranged on the heat sink (K).

6. Electronic arrangement according to claim 5, 2024P11295 DE 29 wherein the measuring circuit board (26) has a front (26.1) facing away from the heat sink (K) and a back (26.2) facing the heat sink (K), wherein the temperature sensor (16) is arranged on the front (26.1).

7. Electronic arrangement according to one of claims 5 or 6, comprising a fastening device (18, 19, 32, 34) which presses the measuring circuit board (26) against the heat sink (K), the heat sink (K) against the semiconductor component (28) and the semiconductor component (28) against the main circuit board (2).

8. Electronic arrangement according to claim 7, wherein the fastening device (18, 19, 32, 34) has a fastening element (18) which is inserted through a through hole (14) which passes through the measuring circuit board (26), the heat sink (K), the semiconductor component (28) and the main circuit board (2).

9. Electronic arrangement according to one of the preceding claims, comprising a measuring and evaluation circuit (52) which is connected to the temperature sensor (16) by a circuit (56) and is suitable for determining a temperature of the temperature sensor (16).

10. Electronic arrangement according to one of claims 3, 4, 7 or 8, comprising a measuring and evaluation circuit (52) which is connected to the temperature sensor (16) by a circuit (56) and is suitable for determining a temperature of the temperature sensor (16), wherein a first section (56.2) of the circuit (56) extends from the temperature sensor (16) to the measuring and evaluation circuit (52) along an electrically conductive element (18) of the mounting device (18, 19, 32, 34).

11. Electronic arrangement according to claim 10, wherein another section (56.1) of the circuit (56) extends from the temperature sensor (16) to the measuring and evaluation circuit (52), starting at the temperature sensor (16) along vias (12) of the measuring circuit board (26), through the heat sink (K) and the semiconductor device (28), along a connection pin of the semiconductor device (28) and along a conductor track of the main circuit board (2) to the measuring and evaluation circuit (52). 2024P11295 DE 30 12. Electronic arrangement according to one of the preceding claims, wherein the semiconductor device (28) is a THT device.

13. Electronic arrangement according to one of the preceding claims, wherein the temperature sensor (16) is a thermistor.

14. Electronic arrangement according to one of claims 5 to 8, wherein a thermal conductivity layer (38) is arranged between the semiconductor device (28) and the heat sink (K).

15. Method for determining a junction temperature (0_J) of a semiconductor device (28) of an electronic arrangement (1), wherein the semiconductor device (28) is arranged on a main circuit board (2), characterized in that a measuring circuit board (26), on which a temperature sensor (16) is arranged, is arranged in thermally conductive contact with the semiconductor device (28), and that the temperature sensor (16) detects a temperature on the basis of which the junction temperature (0_J) of the semiconductor device (28) is determined.

Images