Semiconductor arrangement with at least one semiconductor element

Abstract

The invention relates to a semiconductor arrangement (2), in particular a power semiconductor arrangement for a converter (50), with at least one semiconductor element (4), wherein the at least one semiconductor element (4) is arranged in a housing (6), in particular a closed housing (6). In order to improve the recyclability of a semiconductor arrangement (2), it is proposed that the housing (6) is at least partially filled with a free-flowing material (30), which contains electrically insulating particles (44) and is in direct contact with the at least one semiconductor element (4).

Description

[0001] Description

[0002] Semiconductor arrangement with at least one semiconductor element

[0003] The invention relates to a semiconductor arrangement, in particular a power semiconductor arrangement for a power converter, with at least one semiconductor element.

[0004] Furthermore, the invention relates to a power converter with at least one such semiconductor arrangement.

[0005] Furthermore, the invention relates to a method for producing a semiconductor arrangement, in particular a power semiconductor arrangement for a power converter, with at least one semiconductor element.

[0006] Furthermore, the invention relates to the use of a free-flowing material containing electrically insulating particles for filling a housing of a semiconductor device.

[0007] Such semiconductor devices are used, for example, in a power converter. A power converter can be, for example, a rectifier, an inverter, a converter, or a DC-DC converter. Such semiconductor devices typically comprise a housing in which at least one semiconductor element is arranged. Such a semiconductor element can be, among other things, a transistor. A soft potting compound, in particular a silicone potting compound, is typically provided within the housing to protect the at least one semiconductor element.

[0008] The published patent application WO 2022 / 033745 A1 describes a power module with at least one power unit, which comprises at least one power semiconductor and a substrate, wherein the at least one power unit is at least partially enclosed by a housing. The housing is filled with a soft encapsulation, in particular with a silicone encapsulation.

[0009] Environmental aspects are also becoming increasingly important in electronics development. In particular, improved recyclability is becoming a focus. Recyclability and repair costs are improved, for example, by eliminating the need for material-to-material connections, which can be created through soldering, sintering, or welding.

[0010] The published patent application EP 3 926 670 A1 describes a power semiconductor module with at least one power semiconductor element. In order to reduce the required installation space of the power semiconductor module and increase its service life, it is proposed that the at least one power semiconductor element be electrically insulating and thermally conductively connected to a cooling element via a dielectric material layer, wherein the dielectric material layer rests flatly on a surface of the cooling element and is force-fittingly connected to the cooling element by means of a first force acting orthogonally to the surface of the cooling element.

[0011] The publication WO 2018 / 046165 A1 describes a power module with a semiconductor component to be contacted on the top and bottom, wherein the semiconductor component is to be electrically contacted on the top side by a leadframe matrix by means of contact pressure.

[0012] Soft encapsulation is very difficult to remove, for example during recycling processes. Against this background, it is an object of the present invention to improve the recyclability of a semiconductor device.

[0013] This object is achieved according to the invention by a semiconductor arrangement, in particular a power semiconductor arrangement for a power converter, with at least one semiconductor element, wherein the at least one semiconductor element is arranged in a, in particular closed, housing, wherein the housing is at least partially filled with a free-flowing material which contains electrically insulating particles and is in direct contact with the at least one semiconductor element.

[0014] Furthermore, the object is achieved according to the invention by a power converter with at least one such semiconductor arrangement.

[0015] Moreover, the object is achieved according to the invention by a method for producing a semiconductor arrangement, in particular a power semiconductor arrangement for a power converter, with at least one semiconductor element, wherein the at least one semiconductor element is arranged in a housing, wherein the housing is at least partially filled with a free-flowing material which contains electrically insulating particles in such a way that the free-flowing material is in direct contact with the at least one semiconductor element, wherein the housing is closed in a further step.

[0016] Furthermore, the object is achieved according to the invention by the use of a free-flowing material which contains electrically insulating particles for filling a housing of a semiconductor arrangement in which at least one semiconductor element is arranged, wherein the filling is carried out in such a way that the free-flowing material is in direct contact with the at least one semiconductor element.

[0017] The advantages and preferred embodiments listed below with regard to the semiconductor device can be transferred analogously to the power converter, the manufacturing method and the use.

[0018] The invention is based on the idea of ​​improving the recyclability of a semiconductor device by replacing a commonly used soft potting compound with a free-flowing material which contains electrically insulating particles. A housing of the semiconductor device, in which at least one semiconductor element is arranged, is at least partially filled with the free-flowing material in such a way that the semiconductor element is in direct contact with the free-flowing material. In particular, the semiconductor element is at least partially surrounded by the free-flowing material. The free-flowing material can contain, for example, quartz sand, carbonate sand, gypsum sand, silicates, but also organic free-flowing substances, e.g. polymers, siloxanes. Due to its sand-like structure, the free-flowing material can be removed much more easily, particularly in comparison to the commonly used soft potting compound.Such a free-flowing filling allows for easy disassembly for repair, refurbishment, or recycling. Furthermore, materials and energy-intensive manufacturing processes are saved.

[0019] A further embodiment provides that the electrically insulating particles of the free-flowing material have a grain size in the range of 0.01 mm to 0.6 mm, in particular 0.1 mm to 0.4 mm. In particular, an average grain size is in the range of 0.2 mm to 0.3 mm. Such a grain size minimizes air gaps and, among other things, achieves a sufficient insulating effect. In particular, gaps can be minimized with a bimodal or higher mixture of the free-flowing material, which further improves the insulating effect.

[0020] A further embodiment provides for the electrically insulating particles of the free-flowing material to contain a metal oxide. For example, the electrically insulating particles contain aluminum and / or titanium oxide, glass, mica, and / or ceramic particles. Such metal oxides provide good insulation. When using inorganic electrically insulating particles such as aluminum oxide sand, the semiconductor device exhibits increased explosion protection, since inorganic materials produce significantly fewer, particularly virtually no, explosion gases, thus no carbon dioxide or water is formed, and compressive forces can be better absorbed.

[0021] A further embodiment provides that the electrically insulating particles of the free-flowing material have a sharply broken, particularly fissured, surface. Such a surface leads to an extension of the creepage distances, particularly compared to a spherical structure.

[0022] Another embodiment provides for the free-flowing material to be filled with a meltable insulating material, in particular a wax. High-melting paraffins or other waxes, in particular with a melting point above 100°C, are suitable for this purpose. For example, gaps are filled with the meltable insulating material, whereby the material creeps into the particle spaces during melting, displacing the air, and hardens upon cooling. This structure significantly increases the breakdown voltage of the module. In particular, a multi-meltable insulating material, such as wax, is relatively fluid in its molten state and easy to remove, e.g., during a recycling process. Furthermore, paraffins or other waxes are biodegradable and / or reusable.

[0023] Another embodiment provides for the free-flowing material to be filled with an insulating fluid. Examples of such insulating fluids include fluorocarbons such as 3M Novec. This insulating fluid can form a slurry that is easily removed during disassembly for repair, refurbishment, or recycling, and improves the insulating effect. Furthermore, the insulating fluid can be an electrically insulating gas that fills the gaps in the free-flowing material to achieve an even greater insulating effect. Another embodiment provides for the insulating fluid to contain a phase-change material, which can cushion thermal peaks.

[0024] A further embodiment provides that a circuit carrier is arranged in the housing, wherein the semiconductor element is non-positively connected to the circuit carrier, in particular by means of a press contact. Such a press contact can be designed, among other things, as a busbar. Alternatively, a spring, a screw and / or a bracket can be used for the non-positive connection of the semiconductor element. A circuit carrier can be, among other things, a substrate, in particular a DCB (Direct Copper Bonded) substrate. Such a non-positive connection of the semiconductor element is detachable and easy to remove when dismantled for repair, refurbishment or recycling, in particular in combination with the filling made of the free-flowing material.

[0025] A further embodiment provides that the housing comprises a heat sink on which the circuit carrier rests flat, wherein the circuit carrier is connected to the heat sink in a force-fitting manner. Such a force-fitting connection can be achieved, among other things, by pressing and facilitates disassembly, for example, for recycling.

[0026] A further embodiment provides that the circuit carrier is detachably and thermally conductively connected to the heat sink, in particular via an oil layer. Such an oil layer establishes a detachable connection between the circuit carrier and the heat sink and compensates for the surface roughness of the surfaces of the heat sink or of the circuit carrier. In particular, a thermally conductive oil in the oil layer improves the thermal connection of the circuit carrier to the heat sink. A further embodiment provides that the semiconductor element has at least one contact on a side facing away from the circuit carrier, the at least one contact being surrounded by a plastic frame, in particular an adhesively bonded or pressed-on frame. A plastic frame of this type improves an insulation distance, in particular for HV power modules.

[0027] A further embodiment provides that a metallic contacting element rests on at least one of the contacts of the semiconductor element and is pressed onto it via a press contact to make force-fitting contact with the semiconductor element. For example, the metallic contacting element is designed as a copper plate or molybdenum plate with a thickness in the range from 10 pm to 250 pm, in particular 25 pm to 250 pm. The metallic contacting element acts as a pressure buffer which distributes pressure forces, e.g. from the press contact, so that the introduction of pressure peaks into the sensitive semiconductor element is prevented. Such an arrangement with a force-fitting pressure buffer facilitates disassembly, for example for recycling.

[0028] In the following, the invention is described and explained in more detail with reference to the exemplary embodiments shown in the figures.

[0029] It shows :

[0030] FIG 1 is a schematic sectional view of a first embodiment of a semiconductor device,

[0031] FIG 2 shows a schematic sectional view of a second embodiment of a semiconductor device,

[0032] FIG 3 is an enlarged schematic representation of a first embodiment of a free-flowing material, FIG 4 is an enlarged schematic representation of a second embodiment of a free-flowing material,

[0033] FIG 5 is an enlarged schematic representation of a third embodiment of a free-flowing material,

[0034] FIG 6 is a schematic diagram of a power converter.

[0035] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another. These also further develop the invention independently of one another and are thus to be regarded as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0036] The same reference symbols have the same meaning in the different figures.

[0037] FIG 1 shows a schematic sectional view of a first embodiment of a semiconductor arrangement 2 with a semiconductor element 4 which is arranged in a closed housing 6. For example, the semiconductor element 4 is designed as a vertical transistor, in particular as an IGBT or vertical SiC-MOSFET. The housing 6 comprises a metallic heat sink 8, a housing frame 10 with a plurality of pins 12 and a housing cover 14. The housing frame 10 and the housing cover 14 are made, for example, from a plastic, with the pins 12 being cast or pressed into the housing frame 10. The heat sink 8, which functions as a base plate, is made, for example, from copper, aluminum or one of their alloys. A circuit carrier 16 is connected flat to the heat sink 8.By way of example, the circuit carrier 16 comprises a dielectric material layer 18, which in particular contains aluminum oxide, aluminum nitride or an organic electrically insulating and thermally conductive material, and a metallization 20, which contains, for example, copper, gold, molybdenum, silver or one of their alloys. The dielectric material layer 18 can be pressed or adhesively bonded to the heat sink. Alternatively, the circuit carrier 16 can be designed as a substrate, in particular as a DCB (Direct Copper Bonded) substrate, which is, for example, soldered onto the heat sink 8.

[0038] The semiconductor element 4 has a first power contact 22, in particular a collector contact, and on an opposite side a second power contact 24, in particular an emitter contact, and a control contact 26, in particular a gate contact. The first power contact 22 of the semiconductor element 4 is, for example, materially connected to the metallization 20 of the circuit carrier 16. The materially connected connection of the semiconductor element 4 to the circuit carrier 16 can be produced, among other things, by soldering and / or sintering. The second power contact 24 and control contact 26, arranged on a side of the semiconductor element 4 facing away from the circuit carrier 16, are each connected to the metallization 20 of the circuit carrier 16 via wiring means 28, the metallization 20 being wired to the pins 12 of the housing 6.In this way, the contacts 22, 24, 26 of the semiconductor element 4 are led out of the housing 6 and can be electrically contacted from the outside via the pins 12. The wiring means 28 are designed, for example, as bonding wires or bonding strips, which are welded in particular by ultrasonic wire bonding.

[0039] The housing 6 is, for example, completely filled with a free-flowing material 30 which contains electrically insulating particles, is in direct contact with the semiconductor element 4 and partially surrounds it. The free-flowing material 30 can contain, among other things, a free-flowing sand which contains electrically insulating particles made of a metal oxide, e.g., aluminum oxide. Additionally or alternatively, the free-flowing material 30 can contain other inorganic substances, e.g., quartz sand, carbonate sand, gypsum sand, silicates, but also organic free-flowing substances, e.g., polymers, siloxanes. In particular, the electrically insulating particles of the free-flowing material 30 have a grain size in the range from 0.01 mm to 0.6 mm, in particular 0.1 mm to 0.4 mm. An average grain size can be, among other things, 0.2 mm to 0.3 mm.The free-flowing material 30 replaces a commonly used encapsulating compound in the semiconductor device 2, which is made, for example, of a difficult-to-remove silicone insulating material. The free-flowing material 30 can be easily removed after opening the housing 6, so that the components in the housing 6 are freely accessible for recycling and repair processes.

[0040] Optionally, the sand filling with the free-flowing material 30 can be layered or otherwise graded, with the electrically insulating particles having different densities for improved separability, for example. Layering can serve, for example, the purpose of using more cost-effective filler materials in areas with non-critical electrical fields or of implementing additional functions such as flame protection, arc quenching, or heat buffering.

[0041] FIG 2 shows a schematic sectional view of a second embodiment of a semiconductor arrangement 2 with, for example, two semiconductor elements 4, which are arranged in a closed housing 6. The housing 6 comprises a metallic heat sink 8, a housing frame 10 and a housing cover, which is not shown in FIG 2 for reasons of clarity. A circuit carrier 16, which is designed, for example, as a DGB substrate and has a dielectric material layer 18 with metallization 20 on both sides, lies flat on the heat sink 8. The heat sink has ribs 34 on a side facing away from the DCB substrate. An oil layer 36 establishes a detachable and thermally conductive connection between the DCB substrate and the heat sink. The thermally conductive oil of the oil layer 36 compensates for the surface roughness of the surfaces of the heat sink 8 or of the circuit carrier 16 and thus improves the thermal connection.

[0042] A metallic contacting element 40 rests on each of the second power contacts 24 of the semiconductor elements 4. Additionally or alternatively, such metallic contacting elements 40 can be arranged between the circuit carrier 16 and the first power contact 22 of the semiconductor elements 4. For example, the metallic contacting elements 40 are designed as copper platelets or molybdenum platelets, each having a thickness in the range from 25 pm to 250 pm. Alternatively, the metallic contacting elements 40 are connected to the respective semiconductor element 4 in a material-locking manner, for example by soldering or sintering. Furthermore, the metallic contacting elements 40 can be sprayed on by means of a thermal spraying process, in particular in the form of copper and / or molybdenum particles.

[0043] By means of press contacts 38, which are contacted via the metallic contacting elements 40 with the second power contacts 24 of the semiconductor elements 4, the semiconductor elements 4 are connected in a force-fitting and detachable manner to the metallization 20 of the circuit carrier 16. The press contacts 38 are designed in FIG. 2 as busbars. For example, the busbars are made of copper or a copper alloy. Additionally or alternatively, the press contacts 38 can have a spring contact. A force F acting orthogonally to the surface of the circuit carrier 16 is transmitted via the busbars, by means of which force the semiconductor elements 4 are fixed. As shown in FIG. 1, the housing 6 is filled with a free-flowing material 30 which contains electrically insulating particles and is in direct contact with the semiconductor elements 4 and partially surrounds them.For example, the free-flowing material 30 contains quartz sand and / or aluminum oxide sand. Optionally, the free-flowing material 30 is completely or partially covered with a film in the area of ​​the housing cover, which is pressed onto the free-flowing material 30, for example, by an elastic intermediate element, in particular a polymer foam. Alternatively, the elastic intermediate element is pressed directly onto the free-flowing material 30, preventing it from trickling and thus the formation of cavities. At the same time, subsequent compaction is achieved, which increases the insulating effect and consequently has a positive impact on operational reliability.

[0044] Particularly for HV power modules, the second power contacts 24 of the semiconductor elements 4 are surrounded by a glued-on or pressed-on plastic frame 42 to improve the insulation gap. Alternatively, the plastic frame 42 can be applied additively, for example, by dispensing or a 3D printing process. To prevent air pockets when the free-flowing material 30 trickles in, holes can be made, for example, in the press contacts 38. The further design of the semiconductor arrangement 2 in FIG. 2 corresponds to the design in FIG. 1.

[0045] FIG. 3 shows an enlarged schematic representation of a first embodiment of a free-flowing material 30, which contains a sand having electrically insulating particles 44 with a spherical structure and a small grain size in the range of 0.01 mm to 0.6 mm, in particular 0.1 mm to 0.4 mm, which facilitates trickling in and reduces the likelihood of air inclusions. For example, the free-flowing material 30 contains quartz sand, in particular securing sand. The further embodiment of the free-flowing material 30 corresponds to that in FIG. 1. FIG. 4 shows an enlarged schematic representation of a second embodiment of a free-flowing material 30, which has electrically insulating particles 44 with a sharply broken, ideally fissured, surface. Such a surface quality lengthens creepage distances 46, in particular compared to a spherical structure.The further design of the free-flowing material 30 in FIG 4 corresponds to that in FIG 3.

[0046] FIG. 5 shows an enlarged schematic representation of a third embodiment of a free-flowing material 30, which is filled with a meltable insulating material, in particular with a wax. High-melting paraffins or other waxes with a melting point above 100°C are suitable for this purpose. Additionally or alternatively, the free-flowing material 30 is filled with an insulating fluid containing fluorocarbons, e.g., 3M Novec. A slurry is formed by the insulating fluid. The insulating fluid can be designed as a phase-change material to absorb heat peaks. To ensure improved partial discharge resistance and thus the service life of the semiconductor device 2, the free-flowing material 30 can contain a material with high resistance to partial discharges, e.g., mica. The further embodiment of the free-flowing material 30 in FIG. 5 corresponds to that in FIG. 3.The particles 44 of the free-flowing material 30 in FIG 5 can at least partially have a sharply broken, ideally fissured, surface as shown in FIG 4.

[0047] FIG 6 shows a schematic representation of a power converter 50 comprising a semiconductor device 2. The power converter 50 may comprise more than one semiconductor device 2.

[0048] In summary, the invention relates to a semiconductor arrangement 2, in particular a power semiconductor arrangement for a power converter 50, having at least one semiconductor element 4, wherein the at least one semiconductor element 4 is arranged in a, in particular closed, housing 6. In order to improve the recyclability of a semiconductor arrangement 2, it is proposed that the housing 6 be at least partially filled with a free-flowing material 30 which contains electrically insulating particles 44 and is in direct contact with the at least one semiconductor element 4.

Claims

Patent claims 1. Semiconductor arrangement (2), in particular a power semiconductor arrangement for a power converter (50), with at least one semiconductor element (4), wherein the at least one semiconductor element (4) is arranged in a, in particular closed, housing (6), wherein the housing (6) is at least partially filled with a free-flowing material (30) which contains electrically insulating particles (44) and is in direct contact with the at least one semiconductor element (4).

2. Semiconductor arrangement (2) according to claim 1, wherein the electrically insulating particles (44) of the free-flowing material (30) have a grain size in the range from 0.01 mm to 0.6 mm, in particular 0.1 mm to 0.4 mm.

3. Semiconductor arrangement (2) according to one of claims 1 or 2, wherein the electrically insulating particles (44) of the free-flowing material (30) contain a metal oxide.

4. Semiconductor arrangement (2) according to one of the preceding claims, wherein the electrically insulating particles (44) of the free-flowing material (30) have a sharply broken, in particular fissured, surface.

5. Semiconductor arrangement (2) according to one of the preceding claims, wherein the free-flowing material (30) is filled with a meltable insulating material, in particular a wax.

6. Semiconductor arrangement (2) according to one of claims 1 to 4, wherein the free-flowing material (30) is filled with an insulating fluid.

7. Semiconductor device (2) according to claim 4, wherein the insulating fluid contains a phase change material.

8. Semiconductor arrangement (2) according to one of the preceding claims, wherein a circuit carrier (16) is arranged in the housing (6), wherein the semiconductor element (4) is non-positively connected to the circuit carrier (16), in particular by means of a press contact (38).

9. Semiconductor arrangement (2) according to claim 8, wherein the housing (6) comprises a heat sink (8) on which the circuit carrier (16) rests flat, wherein the circuit carrier (16) is force-fittingly connected to the heat sink (8).

10. Semiconductor arrangement (2) according to claim 9, wherein the circuit carrier (16) is detachably and thermally conductively connected to the heat sink (8), in particular via an oil layer (36).

11. Semiconductor arrangement (2) according to one of claims 8 to 10, wherein the semiconductor element (4) has at least one contact (22, 24, 26) on a side facing away from the circuit carrier (16), wherein the at least one contact (22, 24, 26) is surrounded by a plastic frame (42), in particular one which is glued or pressed on.

12. Semiconductor arrangement (2) according to claim 11, wherein a metallic contacting element (40) rests on at least one of the contacts (22, 24, 26) of the semiconductor element (4) and is pressed onto it via a press contact (38) for force-fitting contact with the semiconductor element (4).

13. Power converter (50) with at least one semiconductor arrangement (2) according to one of the preceding claims.

14. Method for producing a semiconductor arrangement (2), in particular a power semiconductor arrangement for a power converter (50), with at least one semiconductor element (4), wherein the at least one semiconductor element (4) is arranged in a housing (6), wherein the housing (6) is at least partially filled with a free-flowing material (30) which contains electrically insulating particles in such a way that the free-flowing material (30) is in direct contact with the at least one semiconductor element (4), wherein the housing (6) is closed in a further step.

15. The method according to claim 14, wherein the free-flowing material (30) is filled with a meltable insulating material, in particular a wax.

16. The method according to claim 14, wherein the free-flowing material (30) is filled with an insulating fluid.

17. Use of a free-flowing material (30) which contains electrically insulating particles for filling a housing (6) of a semiconductor arrangement (2) in which at least one semiconductor element (4) is arranged, wherein the filling takes place in such a way that the free-flowing material (30) is in direct contact with the at least one semiconductor element (4).

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