The invention relates to a semiconductor module comprising at least one semiconductor element.
The invention furthermore relates to a power converter comprising at least one such semiconductor module.
Moreover, the invention relates to a method for producing a semiconductor module comprising at least one semiconductor element.
Such semiconductor modules are usually used in a power converter. A power converter should, for example, be understood to be a rectifier, an inverter, a frequency converter or a DC/DC converter. Such semiconductor modules are, for example, realized by means of planar electronic packaging technology.
Published unexamined patent application WO 2018/202439 A1 describes an electronic assembly comprising a component that is held between a first substrate and a second substrate. According to the invention, it is provided that a gap between the first substrate and the component is connected to a through-hole such that a solder material, for example, can be dispensed through the through-hole using capillary forces acting in the through-hole and in the gap. Herein, the dispensing is automatic since the capillary forces only act in the gap. Tolerances which can be necessary because of differing gap dimensions can advantageously be compensated by the automatic dispensing of the solder material.
Published unexamined patent application WO 2019/015901 A1 describes an electrical assembly which has at least one electronic switching element which is electrically contacted on its underside and on its upper side which is opposite the underside. The electrical assembly also has two wiring supports which are arranged opposite one another on the electrical contacts. These wiring supports are each at least in part made of a permanently elastic, electrically insulating, thermally conductive material.
Published unexamined patent application US 2019/355644 A1 describes an IGBT module with a heat dissipation base plate.
Published unexamined patent application US 2013/299962 A1 describes a semiconductor apparatus with an IGBT as a vertical semiconductor element provided between first and second lead frames in pairs.
With such planar electronic packaging technology, it is difficult to integrate thermal capacities, in particular additional thermal capacities, due to the flat structure. Such thermal capacities are in particular required for high and short-term overload requirements in order, for example, to keep chip temperature fluctuations small.
Against this background, it is the object of the present invention to disclose a semiconductor module with greater reliability than the prior art.
According to the invention, the object is achieved by a semiconductor module comprising at least one semiconductor element, a first substrate and a second substrate, wherein the at least one semiconductor element is contacted on a first side with the first substrate in a planar manner and is contacted on a second side facing away from the first side with a metallic heat sink in a planar manner, wherein the metallic heat sink is in thermally conductive connection with the semiconductor element and is connected to the second substrate in an electrically conductive manner, wherein the metallic heat sink has a main body for planar contacting of the semiconductor element and at least one fin, wherein the second substrate is connected to the main body in an electrically conductive manner and has a recess in which the at least one fin is arranged, wherein the main body has a circumferential contact surface around the at least one fin via which a material-bonded connection is established with the substrate metallization of the second substrate, wherein the circumferential contact surface is arranged on a side of the main body facing away from the semiconductor element.
Moreover, according to the invention, the object is achieved by a semiconductor module comprising at least one semiconductor element, a first substrate and a second substrate, wherein the at least one semiconductor element is contacted on a first side with the first substrate in a planar manner and is contacted on a second side facing away from the first side with a metallic heat sink in a planar manner, wherein the metallic heat sink is in thermally conductive connection with the semiconductor element and is connected to the second substrate in an electrically conductive manner, wherein the metallic heat sink has a main body for planar contacting of the semiconductor element and at least one fin, wherein the second substrate is connected to the main body in an electrically conductive manner and has a recess in which the at least one fin is arranged, wherein the recess of the second substrate, has edge metallization, in particular circumferential edge metallization, via which a material-bonded connection with the metallic heat sink is established.
In addition, according to the invention, the object is achieved by a power converter comprising at least one such semiconductor module.
Moreover, according to the invention, the object is achieved by a method for producing a semiconductor module comprising at least one semiconductor element, a first substrate and a second substrate, wherein the at least one semiconductor element is contacted on a first side with the first substrate in a planar manner and is contacted on a second side facing away from the first side with a metallic heat sink in a planar manner, wherein a thermally conductive connection between the metallic heat sink and the semiconductor element is established and the metallic heat sink is connected to the second substrate in an electrically conductive manner, wherein the metallic heat sink has a main body for planar contacting of the semiconductor element and at least one fin, wherein the second substrate is connected to the main body in an electrically conductive manner and has a recess in which the at least one fin is arranged, wherein the main body has a circumferential contact surface around the at least one fin via which a material-bonded connection with the substrate metallization of the second substrate is established, wherein the circumferential contact surface is arranged on a side of the main body facing away from the semiconductor element.
In addition, according to the invention, the object is achieved by a method for producing a semiconductor module comprising at least one semiconductor element, a first substrate and a second substrate, wherein the at least one semiconductor element is contacted on a first side with the first substrate in a planar manner and is contacted on a second side facing away from the first side with a metallic heat sink in a planar manner, wherein a thermally conductive connection between the metallic heat sink and the semiconductor element is established and the metallic heat sink is connected to the second substrate in an electrically conductive manner, wherein the metallic heat sink has a main body for planar contacting of the semiconductor element and at least one fin, wherein the second substrate is connected to the main body in an electrically conductive manner and has a recess in which the at least one fin is arranged, wherein the main body has a circumferential contact surface around the at least one fin via which a material-bonded connection with the substrate metallization of the second substrate is established, wherein the circumferential contact surface is arranged on a side of the main body facing away from the semiconductor element.
The advantages and preferred embodiments listed below with respect to the semiconductor module can be applied mutatis mutandis to the power converter and the production method.
The invention is based on the concept of increasing the reliability of a semiconductor module by means of an on-chip metallic heat sink, also known as thermal capacity. The semiconductor module has at least one semiconductor element, a first substrate and a second substrate, wherein the at least one semiconductor element is contacted on a first side with the first substrate in a planar manner and is contacted on a second side facing away from the first side with the metallic heat sink in a planar manner. The second substrate is connected to the metallic heat sink in an electrically conductive manner and hence contacted with the semiconductor element via the metallic heat sink. Such a semiconductor element is, for example, embodied as a transistor, diode or logic module. In particular, the transistor is embodied as an insulated-gate bipolar transistor (IGBT), metal oxide semiconductor field-effect transistor (MOSFET) or field-effect transistor. The metallic heat sink is, for example, produced from copper, in particular solid copper, and/or a copper alloy. The contacting of the semiconductor element takes place for example via an electrically conductive thermal paste or via a material-bonded connection. As a result of the contacting, the metallic heat sink is in thermally conductive connection with the semiconductor element so that heat loss occurring in the semiconductor module is at least partially transferred to the metallic heat sink. In the metallic heat sink, the heat loss is, for example, stored and/or dissipated to the ambient atmosphere. The ambient atmosphere is, for example, air or a cooling fluid. Such an arrangement with a metallic heat sink can keep chip temperature fluctuations small, even with high and short-term overloads, thus resulting in an improvement in the reliability of the semiconductor module.
The metallic heat sink has a main body for planar contacting of the semiconductor element and at least one fin, wherein the second substrate is connected to the main body in an electrically conductive manner and has a recess in which the at least one fin is arranged. The main body has, for example, a rectangular contact surface. The planar contacting of the main body achieves optimal heat transfer. The at least one fin can be flush with the second substrate or protrude beyond the second substrate. In particular, the at least one fin is cuboidal or cylindrical in shape in order to achieve the greatest possible thermal capacity.
The main body has a circumferential contact surface around the at least one fin via which a material-bonded connection with the substrate metallization of the second substrate is established. In particular, the contact surface runs around the circumference of the recess of the second substrate. For example, the contact surface is embodied as a circumferential solder ring. Such a circumferential contact surface enables uniform heat distribution thus avoiding hot spots.
The circumferential contact surface is arranged on a side of the main body facing away from the semiconductor element. Such an arrangement of the circumferential contact surface causes the second substrate to at least partially rest on the main body thus resulting in mechanical stabilization of the arrangement and an increase in the contact surface.
The recess of the second substrate has edge metallization, in particular circumferential edge metallization, via which a material-bonded connection to the metallic heat sink is established. A capillary effect can cause a solder of the circumferential solder ring to rise over the edge metallization thus increasing the bonding surface of metallic heat sink to the second substrate and improving thermal bonding to the metallic heat sink.
A further embodiment provides that the semiconductor element is connected to the metallic heat sink in a materially bonded manner and/or wherein the metallic heat sink is connected to a substrate metallization of the second substrate in a materially bonded manner. Such a material-bonded connection is, for example, embodied as a soldered or sintered connection, thus resulting in improved thermal bonding.
A further embodiment provides that the semiconductor element is arranged in a potting chamber between the first substrate and the second substrate and wherein the potting chamber is sealed toward the recess by the material-bonded connection between the substrate metallization of the second substrate and the circumferential contact surface. The potting chamber comprises, for example, a potting compound, in particular an insulating potting compound, which, for example, contains silicone and serves to maintain the necessary voltage clearances and to protect against harmful environmental influences. The material-bonded connection with the circumferential contact surface means no additional sealing elements are required.
A further embodiment provides that the metallic heat sink is produced in one piece from a metallic material with a thermal conductivity of at least 240 W/(m-K) and/or an electrical conductivity of at least 40 MS/m is established. For example, the metallic heat sink is produced from copper or a copper alloy. A one-piece embodiment made of such a material can result in optimal thermal bonding.
A further embodiment provides that the metallic heat sink has a T-shaped cross-sectional profile. In particular, the larger area of the metallic heat sink with the T-shaped cross-sectional profile is provided for contacting the semiconductor element. Such a cross-sectional profile enables optimal thermal bonding to the semiconductor element and large-area contacting of the second substrate thus resulting in increased current-carrying capacity and reduced contact resistance.
The following describes and explains the invention in more detail with reference to the exemplary embodiments depicted in the figures.
The figures show:
The exemplary embodiments explained in the following are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention to be considered independently of one another, which also develop the invention independently of one another and are thus also be to regarded as a component of the invention individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further of the features of the invention that have already been described.
The same reference symbols have the same meaning in the different figures.
The semiconductor element 4 is, by way of example, embodied as an insulated-gate bipolar transistor (IGBT) but can also be embodied as a metal oxide semiconductor field-effect transistor (MOSFET), field-effect transistor, diode, logic module, in particular field programmable gate array (FPGA) or as another type of semiconductor. In particular, the semiconductor element 4 has an area of at least 10 mm2. For example, the semiconductor element 4 embodied as an IGBT is connected via an emitter contact E to the first substrate 8 and via a collector contact K to the metallic heat sink 12. A gate contact of the IGBT depicted in
The first substrate 8 comprises a dielectric material layer 16 containing a ceramic material, for example aluminum nitride or aluminum oxide, or an organic material, for example a polyamide, and has a thickness d of 25 μm to 400 μm, in particular 50 μm to 250 μm. Moreover, the first substrate 8 has upper metallization 18 on a side facing the semiconductor element 4 and lower metallization 20 on a side facing away from the semiconductor element 4, wherein the upper metallization 18 and the lower metallization 20 are, for example, produced from copper. In particular, the first substrate 8 is embodied as direct bonded copper (DBC).
The metallic heat sink 12 has a main body 22 for planar contacting of the semiconductor element 4 and, for example, a fin 24, wherein the metallic heat sink 12 is produced in one piece from a metallic material with a thermal conductivity of at least 240 W/(m·K) and/or an electrical conductivity of at least 40 MS/m. In particular, the metallic heat sink 12 is produced from copper or a copper alloy. For example, the metallic heat sink 12 has a T-shaped cross-sectional profile. While the main body 22 of the metallic heat sink 12 has a rectangular base and is, for example, embodied as a cubold, the fin 24 can, for example, be embodied as a cubold, cylinder or n-cornered prism, in particular a straight prism.
The second substrate 14 is embodied as a multilayer printed circuit board (PCB), wherein the layers of the printed circuit board have structured substrate metallization 26. Furthermore, the second substrate 14 has a recess 28, in which the fin 24 is arranged, wherein the main body 22 of the metallic heat sink 12 is connected to the substrate metallization 26 of the second substrate 14 in a materially bonded manner. In particular, the circumference of the fin 24 is surrounded by the recess 28, wherein an inner contour of the recess 28 is adapted to an outer contour of the fin 24 and wherein the recess 28 is spaced apart from the fin 24 by a gap 30 with a substantially constant width. On a side facing away from the semiconductor element 4, the main body 22 of the metallic heat sink 12 has a circumferential contact surface 32 running around the fin 24 via which the, in particular circumferential, material-bonded connection with the substrate metallization 26 is established on an underside 34 of the second substrate 14. The material-bonded connection of the circumferential contact surface 32 to the substrate metallization 26 is, for example, embodied as a circumferential solder ring and connects the collector contact K to the second substrate 14 via the main body 22 of the metallic heat sink 12. The fin 24 can be flush with the second substrate 24 or protrude beyond the second substrate 24. Between the circumferential contact surface 32 and the fin 24, the metallic heat sink 12 has a groove, in particular a circumferential groove 36.
Furthermore, a metallic spacer element 38 connecting the emitter contact E of the semiconductor element 4 to the second substrate 14 in an electrically conductive manner is arranged between the first substrate 8 and the second substrate 14. The metallic spacer element 38, which is also called a transfer element, is, for example, produced from copper, aluminum or one of their alloys. Moreover, the semiconductor element 4 is arranged in a potting chamber 40 between the first substrate 8 and the second substrate 14, which is filled, in particular completely, by a potting compound. The potting chamber 40 is sealed toward the recess 28 by the material-bonded connection between the substrate metallization 26 of the second substrate 14 and the circumferential contact surface 32 of the metallic heat sink 12. In addition, the first substrate 8 is connected to a metallic base plate 42, which, is, for example, embodied as a heat sink, in particular in a materially bonded manner.
In summary, the invention relates to a semiconductor module 2 comprising at least one semiconductor element 4, a first substrate 8 and a second substrate 14. In order to achieve higher reliability compared to the prior art, it is proposed that the at least one semiconductor element 4 is contacted on a first side 6 with the first substrate 8 in a planar manner and is contacted on a second side 10 facing away from the first side 6 on a second side 10 with a metallic heat sink 12 in a planar manner, wherein the metallic heat sink 12 is in thermally conductive connection with the semiconductor element 4 and connected to the second substrate 14 in an electrically conductive manner.
Number | Date | Country | Kind |
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20212848.4 | Dec 2020 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2021/080533 | 11/3/2021 | WO |