Semiconductor assembly comprising at least one semiconductor element

Abstract

The invention relates to a semiconductor assembly (2), in particular a semiconductor assembly for a rectifier (64), comprising at least one semiconductor element (4). According to the invention, in order to improve the recyclability of the semiconductor assembly (2), the semiconductor element (4) is arranged in a housing (6), wherein the housing (6) is at least partially filled with a potting compound (30) which can be melted via a heating process, and which is directly in contact with the 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 recycling or repairing a semiconductor device comprising a semiconductor element.

[0006] Such semiconductor devices are used, for example, in a power converter. A power converter is understood to mean, for example, a rectifier, an inverter, a converter or a DC-DC converter. Such semiconductor devices usually comprise a housing in which at least one semiconductor element is arranged. Such a semiconductor element can be, among other things, a transistor. Within the housing, a potting made of a thermosetting plastic, in particular a silicone potting or epoxy potting, is usually provided to protect the at least one semiconductor element.

[0007] Such semiconductor arrangements are used, for example, in a power converter. A power converter is understood to mean, for example, a rectifier, an inverter, a converter or a DC-DC converter. Such semiconductor arrangements usually 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 usually provided within the housing to protect the at least one semiconductor element. 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 surrounded by a housing. The housing is filled with a soft potting compound, in particular a silicone potting compound.

[0008] Environmental and sustainability 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.

[0009] 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.

[0010] 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.

[0011] A casting made of a thermoset is, for example,

[0012] Recycling processes, very difficult to remove. 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 semiconductor element is arranged in a housing, wherein the housing is at least partially filled with a potting compound which can be melted by a heating process and which is in direct contact with the 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 recycling or repairing a semiconductor arrangement with a semiconductor element, wherein the semiconductor element is arranged in a housing, wherein the housing is at least partially filled with a potting compound which can be melted by a heating process and which is in direct contact with the semiconductor element, comprising the following steps: liquefying the potting compound by heating, draining the liquefied potting compound from the housing and removing the semiconductor element from the housing.

[0016] Moreover, the object is achieved according to the invention by a method for recycling or repairing a semiconductor arrangement with a semiconductor element, wherein the semiconductor element is arranged in a housing, wherein the housing is at least partially filled with a potting compound which can be melted by a heating process and which is in direct contact with the semiconductor element, comprising the following steps: evaporating the potting compound by heating, discharging the gaseous potting compound from the housing and removing the semiconductor element from the housing. The advantages and preferred embodiments listed below with regard to the semiconductor arrangement can be transferred analogously to the power converter, the manufacturing method and the use.

[0017] The invention is based on the idea of ​​improving the recyclability of a semiconductor device by replacing a commonly used soft potting made of a thermoset with a potting compound that can be melted by means of a heating process. A housing of the semiconductor device, in which at least one semiconductor element is arranged, is at least partially filled with the meltable potting compound such that the semiconductor element is in direct contact with the meltable potting compound. In particular, the semiconductor element is at least partially surrounded by the meltable potting compound. The meltable potting compound is electrically insulating and can, for example, contain a thermoplastic or paraffin. In particular, the meltable potting compound has a dielectric strength of 2 kV / mm at room temperature.For example, high-melting paraffins or other waxes, particularly those with a melting point above 100 °C, can be used. The potting compound can be removed in the liquefied or gaseous state. The potting compound is heated, for example, by an electrical heating device, particularly by means of a hot plate, via a metallic base plate or a heat sink. Compared to commonly used thermosets, the fusible potting compound can be removed much more easily and essentially without residue. Simple disassembly for repair or recycling is made possible by such a fusible potting compound.

[0018] 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 at least one press contact. The circuit carrier can be designed, among other things, as a substrate, in particular as a DCB (Direct Copper Bonded) substrate. 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. Such a non-positive connection of the semiconductor element is detachable and can be removed easily and essentially without residue when dismantled for repair or recycling, in particular in combination with the filling made of the fusible potting compound.

[0019] A further embodiment provides that the housing has a drain opening for removing the meltable potting compound. The drain opening is arranged, for example, in a housing frame or in a housing cover and enables the liquefied or gaseous potting compound to be drained off. In particular, the drain opening can also be used for filling the housing with the meltable potting compound. The drain opening can also be designed as a predetermined breaking point or as markings for creating an opening in the housing. In particular, the drain opening enables draining without removing the cover, wherein the cover achieves more homogeneous heating of the potting compound, thus further simplifying removal of the potting compound without leaving any residue.

[0020] A further embodiment provides that the drain opening is sealed in a fluid-tight and releasable manner with a first closure element during operation of the semiconductor device. The first closure element is designed, for example, as a sealing plug. Such a sealing plug enables easy removal of the encapsulating compound and reliably and cost-effectively ensures the tightness of the housing.

[0021] A further embodiment provides that the housing has a pressure equalization opening which is fluid-tight and releasably closed by a second encryption element during operation of the semiconductor device. The pressure equalization opening can also be designed as a predetermined breaking point or as markings for creating an opening in the housing. The second closure element is designed, for example, as a sealing plug. In particular, the drain opening and the pressure equalization opening are arranged such that at least 60% of the enclosed volume can be located between the openings. An air flow through the pressure equalization opening equalizes the pressure in the housing, so that the potting compound can be removed from the housing essentially without leaving any residue.

[0022] A further embodiment provides that the housing is at least partially made of a meltable material that has a higher melting temperature than the meltable potting compound. This ensures that the housing does not liquefy when the potting compound is heated and drained.

[0023] A further embodiment provides that the semiconductor arrangement comprises an electrical heating device, which is arranged at least partially within the housing. For example, a heating conductor is arranged in the region of an inner surface of a housing frame or a housing cover. Such a heating device reduces the required energy input, particularly compared to heating via a heat sink or a base plate, and prevents unintentional detachment of components within the housing.

[0024] A further embodiment provides that the electrical heating device comprises a heating coil which is at least partially connected to the housing. The heating coil can be connected to an inner surface of a housing frame or a housing cover. The heating coil can be energized, among other things, using a contactless transformer. Such a heating device enables simple and rapid heating of the potting compound. The invention is described and explained in more detail below with reference to the exemplary embodiments illustrated in the figures.

[0025] It shows :

[0026] FIG 1 is a schematic sectional view of a first embodiment of a semiconductor device,

[0027] FIG 2 shows a recycling of a first embodiment of a semiconductor device in a schematic sectional view,

[0028] FIG 3 is a schematic sectional view of a second embodiment of a semiconductor device,

[0029] FIG 4 is a schematic sectional view of a third embodiment of a semiconductor device,

[0030] FIG 5 is a schematic sectional view of a fourth embodiment of a semiconductor device,

[0031] FIG 6 is a schematic diagram of a power converter.

[0032] 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 can be viewed independently of one another. These features also further develop the invention independently of one another and are therefore to be viewed as part 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. The same reference symbols have the same meaning in the various figures.

[0033] 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 DGB (Direct Copper Bonded) substrate, which is, for example, soldered onto the heat sink 8.

[0034] 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.

[0035] The housing 6 is filled with a potting compound 30 which can be melted by a heating process and which is in direct contact with the semiconductor element 4 and partially surrounds it. The potting compound 30 can contain, among other things, a thermoplastic or paraffin. In particular, high-melting paraffins or other waxes with a melting point above 100°C are suitable, so that the potting compound is solid at room temperature. The potting compound 30 can contain fillers such as ceramic particles. The potting compound 30 can be liquefied or vaporized for removal.

[0036] The housing 6 can be made at least partially from a meltable material which has a higher melting point than the meltable potting compound 30 in order to prevent the housing from also liquefying when the meltable potting compound 30 is heated. To remove the meltable potting compound 30, the housing has a drain opening 32 which is closed in a fluid-tight and releasable manner with a first closure element 34 during operation of the semiconductor arrangement 2. The first closure element 34 is designed, for example, as a sealing plug. Furthermore, the housing 6 has a pressure equalization opening 36 which is closed in a fluid-tight and releasable manner with a second closure element 38 during operation of the semiconductor arrangement 2. The openings 32, 36 are arranged in such a way that at least... 60 % of the enclosed volume can be located between the openings 32 , 36 .The openings 32, 36 can also be designed as predetermined breaking points or as markings for creating an opening in the housing 6.

[0037] FIG. 2 shows a recycling of a first embodiment of a semiconductor device 2 in a schematic sectional view, wherein the liquefied potting compound 30 is drained via the drain opening 32. For this purpose, the first closure element 34 is removed from the drain opening 32 and the second closure element 38 is removed from the pressure equalization opening 36. The semiconductor device 2 is designed as shown in FIG. 1. The potting compound 30 is liquefied by heating using an electrical heating device, for example using a heating plate. Alternatively, the potting compound 30 can be converted into the gaseous state for removal by heating.

[0038] The liquefied potting compound 30 is drained through the drain opening 32 into a collecting container 42. For example, the housing 6 is tilted by an angle α. The angle α can be in the range from 10° to 90° and can be varied, in particular repeatedly, during the draining. Additionally or alternatively, the collecting container 42 can comprise a suction device for sucking out the potting compound 30. The separate collection of the potting compound 30 improves environmental compatibility and sustainability. An air flow 43 flowing through the pressure equalization opening 36 equalizes the pressure in the housing 6, so that the potting compound 30 can be removed from the housing 6, in particular without leaving any residue. Alternatively, in the case of wire-bonded circuits, pressure equalization can be achieved without a pressure equalization opening 36 by removing the housing cover 14, whereby the housing cover 14 achieves a more homogeneous heating of the potting compound 30.

[0039] In a further step, the housing cover 14 is opened and the semiconductor element 4 is removed. Furthermore, the circuit carrier 16, in particular the DGB substrate, can be removed. In this way, the components are cleanly separated for further processing.

[0040] Alternatively, the liquefied potting compound 30 can be drained through the drain opening 32 for repair, wherein the housing cover 14 is opened to remove at least one defective semiconductor element 4. In a further step, at least the defective semiconductor element 4 is replaced. In particular, the circuit carrier 16 can be removed with at least one defective semiconductor element 4, and the removed components are replaced in a further step.

[0041] FIG. 3 shows a schematic sectional view of a second embodiment of a semiconductor device 2, wherein the semiconductor element 4 is force-fittingly connected to the circuit carrier 16 by means of a first press contact 44. In addition to mechanical fixation, the first press contact 44 establishes the electrical contact with the second power contact 24 of the semiconductor element 4.

[0042] A first metallic contacting element 46 is connected to the second power contact 24 of the semiconductor element 4 and acts as a buffer layer which distributes a force F from the press contact 44 so that pressure peaks are prevented from being introduced into the sensitive semiconductor element 4. The first metallic contacting element 46 can be designed, among other things, as a metal plate which contains copper and / or molybdenum and can have a thickness in the range from 25 pm to 250 pm. The connection between the first metallic contacting element 46 and the semiconductor element 4 can be materially bonded, e.g. by soldering or sintering. Alternatively, the first metallic contacting element 46 can be sprayed on by means of a thermal spraying process, in particular in the form of copper and / or molybdenum particles.An optional second metallic contacting element 48, which can be designed, among other things, as a metal plate containing copper and / or molybdenum, is arranged between the first power contact 22 and the circuit carrier 16.

[0043] A second press contact 50 and a third press contact 52 are force-fitted to the metallization 20 of the circuit carrier 16 for electrically contacting the first power contact 22 and the control contact 26, respectively, wherein the control contact 26 is connected to the metallization 20 via at least one wiring means 28. Via the press contacts 44, 50, 52, the circuit carrier 16 is pressed against the heat sink 8 and thus force-fitted thereto.

[0044] The press contacts 44, 50, 52 are designed as busbars. For example, the busbars are made of copper or a copper alloy. Additionally or alternatively, the press contacts 44, 50, 52 can have a spring, a screw or a bracket. The busbars are guided out of the housing 6 via sealing elements 54, so that the housing 6 is sealed fluid-tight. A plurality of first press contacts 44 (e.g. 2x2, 2x3, 3x3, 3x4 or 4x4), arranged in particular equidistantly in a square or rectangular shape on the metallic contacting element 46, leads to improved mechanical fixing of the semiconductor element 4, more homogeneous pressure distribution and low-resistance electrical contacting. The further embodiment of the semiconductor arrangement 2 in FIG. 3 corresponds to the embodiment in FIG. 1.Recycling occurs as shown in FIG. 2, wherein, after the potting compound 30 has been drained, the force-fit connections of the press contacts 44, 50, 52 are released, and the semiconductor element 4, now loosely resting on the circuit carrier 16, can be easily and non-destructively removed for further recycling. The circuit carrier 16, now loosely resting on the heat sink 8, can also be easily and non-destructively removed for further recycling.

[0045] FIG 4 shows a schematic sectional view of a third embodiment of a semiconductor arrangement 2, wherein an electrical heating device 56 is arranged in the housing 6. The electrical heating device 56 has a heating coil 58 which is connected, for example, to the housing cover 14. For example, the heating coil 58 is manufactured together with the plastic housing cover 14 using an MID (Molded Interconnect Devices) process. The heating device can comprise electrical contacts 60 for connection to a power source 62, wherein the electrical contacts 60 are arranged running through the housing cover 14. Alternatively, the heating coil 58 can be supplied with current in a contactless manner using a transformer. The further embodiment of the semiconductor arrangement 2 in FIG 4 corresponds to the embodiment in FIG 1. The contacting of the semiconductor element 4 can be effected by means of press contacts 44, 50, 52, as shown in FIG. 3.

[0046] FIG. 5 shows a schematic sectional view of a fourth embodiment of a semiconductor arrangement 2, wherein the electrical heating device 56 comprises at least one electrically insulated heating wire 62, which is arranged to run through the housing 6. The at least one electrically insulated heating wire 62 is potted with the potting compound 30 and can heat it directly. The further embodiment of the semiconductor arrangement 2 in FIG. 5 corresponds to the embodiment in FIG. 4.

[0047] FIG. 6 shows a schematic representation of a power converter 64 comprising a semiconductor device 2. The power converter 64 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 64, having at least one semiconductor element 4. In order to improve the recyclability of a semiconductor arrangement 2, it is proposed that the semiconductor element 4 is arranged in a housing 6, wherein the housing 6 is at least partially filled with a potting compound 30 which can be melted by a heating process and which is in direct contact with the semiconductor element 4.

Claims

Patent claims 1. Semiconductor arrangement (2), in particular a power semiconductor arrangement for a power converter (64), with at least one semiconductor element (4), wherein the semiconductor element (4) is arranged in a housing (6), wherein the housing (6) is at least partially filled with a potting compound (30) which can be melted by a heating process and which is in direct contact with the semiconductor element (4).

2. Semiconductor arrangement (2) according to claim 1, 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 at least one press contact (44, 50, 52).

3. Semiconductor arrangement (2) according to one of claims 1 or 2, wherein the housing (6) has a drain opening (32) for removing the fusible potting compound (30).

4. Semiconductor arrangement (2) according to claim 3, wherein the drain opening (32) is fluid-tightly and releasably closed by a first closure element (34) during operation of the semiconductor arrangement (2).

5. Semiconductor arrangement (2) according to one of claims 3 or 4, wherein the housing (6) has a pressure equalization opening (36) which is fluid-tight and releasably closed by a second closure element (38) during operation of the semiconductor arrangement (2).

6. Semiconductor arrangement (2) according to one of the preceding claims, wherein the housing (6) is at least partially made of a fusible material which has a higher melting temperature than the fusible potting compound (30).

7. Semiconductor arrangement (2) according to one of the preceding claims, comprising an electrical heating device (56) which is arranged at least partially within the housing (6).

8. Semiconductor arrangement (2) according to claim 7, wherein the electrical heating device (56) comprises a heating coil (58) which is at least partially connected to the housing (6).

9. Power converter (64) with at least one semiconductor arrangement (2) according to one of the preceding claims.

10. A method for recycling or repairing a semiconductor device (2) with a semiconductor element (4), wherein the semiconductor element (4) is arranged in a housing (6), wherein the housing (6) is at least partially filled with a potting compound (30) which can be melted by a heating process and which is in direct contact with the semiconductor element (4), comprising the following steps: Liquefying the potting compound (30) by heating, draining the liquefied potting compound (30) from the housing (6) and Removing the semiconductor element (4) from the housing (60).

11. Method according to claim 10, 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 at least one press contact (44, 50, 52), wherein the removal of the semiconductor element (4) from the housing (6) comprises a release of the press contact (44, 50, 52).

12. The method according to one of claims 10 or 11, wherein the housing (6) has a drain opening (32) for removing the meltable potting compound (30), wherein the drain opening (32) is closed in a fluid-tight and releasable manner by a first closure element (34) during operation of the semiconductor device (2), wherein before the liquefied potting compound (30) is drained, the drain opening (32) is opened by removing the first closure element (32), wherein the liquefied potting compound (30) is drained via the drain opening (32).

13. The method according to claim 12, wherein the housing (6) has a pressure equalization opening (36) which is fluid-tight and detachably closed by a second closure element (38) during operation of the semiconductor device (2), wherein before the liquefied potting compound (30) is drained off, the pressure equalization opening (36) is opened by removing the second closure element (38), wherein when the liquefied potting compound (30) is drained off via the drain opening (32), pressure equalization takes place via the pressure equalization opening (36).

14. Method according to one of claims 10 to 13, wherein the semiconductor arrangement (2) comprises an electrical heating device (56) which is arranged at least partially within the housing (6), wherein the heating takes place at least partially via the electrical heating device (56).

15. A method for recycling or repairing a semiconductor device (2) with a semiconductor element (4), wherein the semiconductor element (4) is arranged in a housing (6), wherein the housing (6) is at least partially filled with a potting compound (30) which is meltable by a heating process and which is in direct contact with the semiconductor element (4), comprising the following steps: - evaporating the potting compound (30) by heating, Draining the gaseous potting compound (30) from the housing (6) and Removing the semiconductor element (4) from the housing (6).

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