Heat sink for a semiconductor assembly, semiconductor module, current rectifier and method for producing a heat sink of this type

Abstract

The invention relates to a heat sink for a semiconductor assembly, wherein: the heat sink is produced from a first metal material and the dimension of at least one reference surface of the heat sink is smaller; and the at least one reference surface of the heat sink is raised as a result of an additive manufacturing process.

Description

[0001] 202323094 Foreign version 1 Description Heat sink for a semiconductor arrangement, semiconductor module, power converter and method for producing such a heat sink The invention relates to a heat sink for a semiconductor arrangement, a semiconductor module with a semiconductor arrangement and such a heat sink, a power converter with such a semiconductor module and a method for producing such a heat sink. A typical design of a current series of heat sinks is subtractive. This means that the extruded profile of a heat sink is manufactured with an excess dimension, wherein the heat sink is made of aluminum, for example. The excess dimension is retained due to fluctuations in the manufacturing process of the extruded profile. In order to arrive at the target dimension, a subtractive method is used, for example a subtractive milling process.During the milling process, reference surfaces are created that are essential for downstream manufacturing processes. The costs of the subtracting process step are essentially caused by the milling process and the aluminum allowance. Typical heat sinks contain several functionalities that must be ensured by the dimensional accuracy of the heat sink. Dimensional accuracy is defined in the design using reference surfaces and tolerances. The reference surfaces for the manufacturing process, and thus for ensuring functionality in the device, are defined as follows: For example, the dimensional accuracy of the side surfaces of the heat sink is necessary to ensure that a heat sink cover snaps into place.Elements such as a DCB substrate are also mounted on the heat sink. 202323094 Foreign Version 2 The contact surfaces on the heat sink below the DCB substrate are coated with an adhesion-promoting layer to enable soldering of the substrate to the heat sink. Published patent application WO 2011 / 024377 A1 describes a semiconductor module with a heat radiation element comprising a first element containing aluminum and a second element containing copper, which is embedded in the first element and whose sides are enclosed by the first element; and a semiconductor element that is thermally connected to the heat radiation element.DE 102017 217537 A1 discloses an electrical device comprising: a power module with a circuit carrier on which a circuit component is arranged; a cooling structure; and an intermediate structure arranged between the circuit carrier and the cooling structure, wherein the cooling structure is made of a first metal material and the intermediate structure is made of a second metal material with a higher thermal conductivity than that of the first metal material.EP 2271 196 A1 describes a method for producing a power converter assembly and the power converter assembly itself with a cooling device comprising a metallic molded body having at least one planar portion of a main surface and a plurality of cooling means, and with at least one substrate. It includes essential method steps such as providing a pressure counterpart of the pressure sintering device with a recess for receiving the cooling device, said recess being designed as a negative mold of the cooling device. Subsequently, the cooling device is arranged in the pressure counterpart.This is followed by arranging at least one substrate of the power converter circuit on the associated flat section of the main surface of the cooling device, wherein the respective contact surfaces of the substrate and the cooling device each have a sinterable surface in the region to be connected, and wherein sintered metal of suitable consistency is arranged between these regions to be connected. The pressure-sintered connection is then formed by applying pressure and temperature to the substrate and the cooling device. EP 3624 184 A1 relates to a method for producing a power module unit and to a power module unit. Furthermore, the invention relates to a power supply and a frequency converter. To produce the power module unit, a base plate is provided with cutouts. The base plate is connected to a substrate which carries the power semiconductor.After the substrate is attached to the base plate, the cooling fins are guided into the recesses of the base plate and fastened with a form-fitting and / or force-fitting connection. This design allows a power module unit to be designed with cooling fins as required, while simultaneously simplifying the manufacture of the power module unit. GB 2526 172 A discloses an electronic assembly for an inverter, which comprises a substrate with a dielectric layer and metallic conductor tracks. Several terminals are connected to a DC power source. A first semiconductor and a second semiconductor are connected to one another between the terminals of the DC power source. A primary metallic island (e.g., strip) is located in a primary zone between the first semiconductor and the second semiconductor. The primary metallic island has a greater height or thickness than the metallic conductor tracks.The primary metal island serves as a heat sink for heat dissipation. First and second housing parts can be mounted above and below the substrate, respectively, with the first housing part having a plurality of coolant channels. The heat can be radiated from the metallic islands through vias to a heat sink 2b, which is mounted on the opposite side of the substrate. The object of the invention is to provide an alternative heat sink or an alternative method for producing such a heat sink, in which the complex steps of a subtractive method are avoided. The object of the invention is achieved by the heat sink according to claim 1. Advantageous embodiments of the heat sink according to the invention are specified in claims 2 to 8.The object of the invention is likewise achieved by the semiconductor module according to claim 9 or 10 and the power converter according to claim 11. Furthermore, the object of the invention is achieved by the method according to claim 12. Advantageous embodiments of the method according to the invention are specified in claims 13 and 14. The heat sink according to the invention for a semiconductor device according to claim 1 is made from a first metallic material and has an undersize in at least one reference surface, wherein the at least one reference surface of the heat sink is raised by means of an additive manufacturing process.

[0002] 3 The advantage here is that a complex and cost-intensive subtractive process for producing the heat sink is avoided, and elevations are only made on the necessary reference surfaces. Thus, the heat sink according to the invention can be produced more cheaply than an oversized heat sink with a subsequent subtractive manufacturing process. In one embodiment of the heat sink according to the invention, the additive manufacturing process has deposited metal on the at least one reference surface. In the additive manufacturing process, aluminum (Al) or copper (Cu) can be deposited layer by layer. In a further embodiment of the heat sink according to the invention, the additive manufacturing process is a cold spray process. In one embodiment of the heat sink according to the invention, the additive manufacturing process deposits an adhesion-promoting layer for soldering a second metallic material.In a further embodiment, the elevation by means of the additive manufacturing process has a thickness of 15 µm to 2 mm on at least one reference surface of the heat sink. In a further embodiment of the heat sink according to the invention, the at least one reference surface is part of the side surface of the heat sink, wherein this part serves as an attachment point for a cover for the heat sink. In a further embodiment of the heat sink according to the invention, the at least one reference surface is part of the upper surface of the heat sink, wherein this part serves as an attachment point for a DCB substrate (“Direct Copper Bonding”). 4 The semiconductor module according to the invention comprises at least one semiconductor arrangement and a heat sink according to the invention. The semiconductor arrangement can be a DCB substrate (“direct copper bonding”). The power converter according to the invention comprises a semiconductor module according to the invention.The method for producing a heat sink comprises the following steps: - providing a heat sink made of a first metallic material and having an undersize in at least one reference surface; - detecting at least one actual height value of the at least one reference surface; - determining at least one target height value of the at least one reference surface; and - additively increasing the at least one reference surface of the heat sink to the at least one target height value. In one embodiment of the method according to the invention, this comprises the further step: - placing / soldering a cover or a DCB substrate onto the raised at least one reference surface. In one embodiment of the method, the detection of at least one actual height value of the at least one reference surface is carried out using a laser scanner.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 understandable in connection with the description of the embodiments, which are explained in more detail in conjunction with the figures. 5 Showing: Figure 1 shows a heat sink according to the invention with reference surfaces; Figure 2 shows a heat sink according to the invention with a cover and DCB substrates; Figures 3A and 3B show a heat sink in a side view and a top view before the application of the additive manufacturing process; Figure 4 shows a method according to the invention for producing a heat sink; Figure 5 shows an embodiment of a method according to the invention for producing a heat sink; and Figure 6 shows a power converter according to the invention. Figure 1 shows a heat sink 100 according to the invention. The heat sink 100 is made from a first metallic material, for example aluminum (Al).Furthermore, the heat sink 100 has an undersize in at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106. By means of an additive manufacturing process, the at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106 of the heat sink 100 has been raised. According to the illustration in Figure 1, the at least one reference surface 101, 102, 103, 104 can be a part of the side surface 198 of the heat sink 100, wherein this part serves as an attachment point of a cover 300 for the heat sink 100. Likewise, the at least one reference surface 105, 105', 105"; 106 can be a part of the upper surface 199 of the heat sink 100, wherein this part serves as a fastening point for a DCB substrate ("Direct Copper Bonding"). 6 Figure 2 shows the heat sink 100 according to the invention for a semiconductor device 28 with a cover 300 and DCB substrates 200, 200', 200".The semiconductor arrangement 28 has semiconductor elements which are designed as, in particular, a vertical transistor or as a diode. A transistor can be designed, among other things, as an insulated-gate bipolar transistor (IGBT), as a metal-oxide-semiconductor-field-effect transistor (MOSFET), or as a bipolar transistor. A transistor can be assigned a diode, in particular an antiparallel one. The semiconductor elements are integrally connected to a substrate, for example, the DCB substrate 200, 200', 200", wherein the integral connection can be produced, among other things, by soldering and / or sintering. The additive manufacturing process can, for example, have deposited metal on the at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106. For example, the additive manufacturing process may have deposited aluminum (Al) or copper (Cu) layer by layer. The additive manufacturing process may be a cold spray process.The powder mixture may also contain particles other than aluminum (Al) or copper (Cu), such as Al2O3, but these particles are not deposited in large quantities relative to the main component of the powder in the layer. Figure 3A shows the heat sink 100 according to the invention in a side view, while Figure 3B shows the heat sink 100 according to the invention in a top view. In the side view of Figure 3A, the heat sink 100 has a height H and a width B. In order to attach a cover 300 with an inner width B' to the heat sink 100, the dimensions of the heat sink 100 must be precisely adjusted. By additively applying the material to the reference surfaces 7 101, 102, 103, 104 on the side surface 198 of the heat sink 100, the accurate fit of the cover 300 is ensured and the width B of the heat sink 100 is adapted to the inner width B' of the cover 300.According to the illustration in Figure 3B, the reference surfaces 101, 102, 103, 104, which are located on the side surface 198 of the heat sink 100, serve this purpose. In Figure 3B, the reference surfaces 105, 105', 105" are shown on the upper surface 199 of the heat sink 100; these serve, for example, as attachment points for DCB substrates 200, 200', 200". In this case, the additive manufacturing process is intended to deposit an adhesion-promoting layer that serves to solder a second metallic material. By means of soldering, for example, DCB substrates 200, 200', 200" are connected to the heat sink 100 according to the invention. The elevation by means of the additive manufacturing process on the reference surfaces 101, 102, 103, 104; 105, 105', 105"; 106 of the heat sink 100 can have a thickness of 15 µm to 2 mm. Figure 4 shows a method 1000 according to the invention for producing a heat sink 100.The method comprises the following steps between the start 1001 and the end 1999: - Providing 1010 a heat sink 100 which is made of a first metallic material and in at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106 has an undersize; - detecting 1020 at least one actual height value of the at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106; 8 - determining 1030 at least one desired height value of the at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106; and - additively increasing 1040 the at least one reference surface 101, 102, 103, 104; 105, 105', 105"; 106 of the heat sink 100 to the at least one desired height value. The The desired height value can be determined, for example, from the difference between the inner width B' of a cover 300 and the width B of the provided heat sink 100.The method 1000 according to the invention can be supplemented by a further step, as shown in Figure 5: - Placing / soldering 1050 a cover 300 or a DCB substrate 200, 200', 200'' onto the raised at least one reference surface 101, 102, 103, 104; 105, 105', 105''; 106. The detection 1020 of the at least one actual height value of the at least one reference surface 101, 102, 103, 104; 105, 105', 105''; 106 can be carried out by means of a laser scanner. Any conventional calculation method, for example a computer-aided calculation method, can be used to determine 1030 the at least one desired height value of the at least one reference surface 101, 102, 103, 104; 105, 105', 105''; 106. Figure 6 shows the power converter 64 according to the invention, which comprises a semiconductor module 4. For this purpose, the semiconductor module 4 has a semiconductor arrangement 28 and a heat sink 100 according to the invention.For example, the semiconductor device 28 may comprise a DCB substrate 200, 200', 200". 9 The application of the adhesion-promoting layer may also serve to compensate for height differences and enable subsequent soldering.

Claims

10 patent claims 1. Heat sink (100) for a semiconductor device (28), wherein the heat sink (100) is made of a first metallic material and the heat sink (100) has an undersize in at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106), characterized in that by means of an additive manufacturing process only the at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106) of the heat sink (100) is raised.

2. The heat sink (100) according to claim 1, wherein the additive manufacturing process has deposited metal on the at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106).

3. The heat sink (100) according to claim 2, wherein the additive manufacturing process has deposited aluminum (Al) and / or copper (Cu) in layers.

4. The heat sink (100) according to one of the preceding claims, wherein the additive manufacturing process is a cold spray process. 5.Heat sink (100) according to one of the preceding claims, in which the additive manufacturing process deposits an adhesion-promoting layer for soldering a second metallic material.

6. Heat sink (100) according to one of the preceding claims, in which the elevation produced by the additive manufacturing process on at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106) of the heat sink (100) has a thickness of 15µm to 2mm. 11 7. Heat sink (100) according to one of the preceding claims, in which the at least one reference surface (101, 102, 103, 104) is a part of the side surface (198) of the heat sink (100), this part serving as an attachment point for a cover (300) for the heat sink (100).

8. Heat sink (100) according to one of the preceding claims, in which the at least one reference surface (105, 105', 105''; 106) is a part of the upper surface (199) of the heat sink (100), this part serving as an attachment point for a DCB substrate (200, 200', 200'') ("direct copper bonding").

9. A semiconductor module (4) comprising at least one semiconductor arrangement (28) and a heat sink (100) according to one of the preceding claims.

10. A semiconductor module (4) according to claim 9, wherein the semiconductor arrangement (28) is a DCB substrate (200, 200', 200'') ("direct copper bonding").

11. A power converter (64) comprising at least one semiconductor module (4) according to claim 9 or 10. 12.Method (1000) for producing a heat sink (100), comprising the following steps: - Providing (1010) a heat sink (100) which is made of a first metallic material and has an undersize in at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106); - Detecting (1020) at least one actual height value of the at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106); - Determining (1030) at least one desired height value of the at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106); and - additively increasing (1040) the at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106). 12 of the heat sink (100) to the at least one desired height value.

13. Method (1000) according to claim 12, with the further step: - placing / soldering (1050) a cover (300) or a DCB substrate (200, 200', 200'') onto the raised at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106).

14. Method (1000) according to claim 12 or 13, wherein the detection (1020) of at least one actual height value of the at least one reference surface (101, 102, 103, 104; 105, 105', 105''; 106) is carried out by means of a laser scanner.

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