Circuit assembly with a circuit carrier and a semiconductor component
Patent Information
- Application Number
- EP2023726899
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-20
- Filing Date
- 2023-05-10
- Publication Date
- 2025-02-05
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Circuit arrangement with a circuit carrier and a semiconductor component
[0003] The invention relates to a circuit arrangement with a circuit carrier and a semiconductor component.
[0004] In the field of power electronics, semiconductor components, such as switching elements, are usually available in the form of power modules, also known as power modules, or in the form of discrete packages. The semiconductor components are usually contacted using specific wire bonding technologies, and the power modules are attached to a circuit carrier using solder, spring, or press connections, for example. The use of bond wires limits the maximum permissible current density through the semiconductor components. In addition, parasitic inductances occur, which limit the achievable switching speed of the switching elements.
[0005] WO 2020 / 249479 A1 discloses an electronic circuit which, inter alia, has a first circuit carrier, a second circuit carrier and a power electronic semiconductor component. The semiconductor component has an upper side which bears against an underside of the first circuit carrier, and a underside which bears against an upper side of the second circuit carrier. The first circuit carrier has a via which electrically connects the upper side of the first semiconductor component to a conductor track of the first circuit carrier. The second circuit carrier has, for example, an electrically conductive layer forming its upper side and an electrically insulating layer arranged on a side of the electrically conductive layer facing away from the first circuit carrier.The problem with such an arrangement of circuit carriers and semiconductor components is that the two circuit carriers can have very different coefficients of expansion. This leads to significant warping of the assembly after a material-to-material connection, for example by soldering or sintering, has cooled down. As a result, the second circuit carrier cannot be pressed across its entire surface against a heat sink, which impairs heat dissipation from the circuit. The different coefficients of expansion of the circuit carriers can also lead to cracks in the layers of the second circuit carrier, which can cause reliability problems or even failure of the entire circuit.
[0006] JP 2001 156225 A discloses a semiconductor device comprising a pair of heat-radiating elements. Semiconductor chips are arranged between the heat-radiating elements. The heat-radiating elements are made of a metallic material whose electrical and / or thermal conductivity is greater than that of tungsten or molybdenum.
[0007] US 2020 / 343155 A1 discloses a power conversion device having two heat sinks, a circuit board with a circuit pattern formed thereon, and a switching element having an electrode portion electrically connected to the circuit pattern. A first insulating element is arranged between a first heat sink and the circuit board. A second insulating element is arranged between the second heat sink and the switching element.
[0008] DE 10 2014 205 958 A1 discloses a semiconductor switching element arrangement for use in a vehicle, comprising a printed circuit board and a semiconductor switching element mounted on the printed circuit board, which is covered by a metallic cover mounted on the printed circuit board. The metallic cover is in thermally conductive contact with a cooling device or can be brought into such contact.
[0009] EP 3 440 906 A1 discloses an electronic module comprising a printed circuit board, at least one integrated circuit mounted on the printed circuit board, and at least one electromagnetic interference shield mounted on the printed circuit board. The at least one integrated circuit is mounted within a perimeter defined by the shield.
[0010] The invention is based on the object of providing an improved circuit arrangement which overcomes these problems.
[0011] The object is achieved according to the invention by a circuit arrangement having the features of claim 1.
[0012] Advantageous embodiments of the invention are the subject of the dependent claims.
[0013] A circuit arrangement according to the invention comprises
[0014] - a circuit carrier,
[0015] - a leadframe,
[0016] - a semiconductor component arranged between the circuit carrier and the leadframe,
[0017] - a heat sink arranged on a side of the leadframe facing away from the semiconductor component,
[0018] - an electrically insulating insulation element arranged between the leadframe and the heat sink and
[0019] - a pressing device which is designed to press the circuit carrier, the semiconductor component, the leadframe, the insulation element and the heat sink together.
[0020] Compared to the circuit arrangement known from WO 2020 / 249479 A1, for example, the circuit arrangement according to the invention has a circuit carrier and a leadframe between which the semiconductor component is arranged, instead of two circuit carriers between which the semiconductor component is arranged. In addition, the circuit arrangement has an insulation element which is arranged between the leadframe and the heat sink. The leadframe and the insulation element take over the functions of the second circuit carrier of the circuit arrangement known from WO 2020 / 249479 A1, namely the electrical contacting of the semiconductor component on the side of the semiconductor component facing the leadframe and the heat conduction from the semiconductor component to the heat sink.
[0021] By decoupling the leadframe from the insulation element, the problem of warping of the circuit arrangement can be solved. This is achieved by manufacturing the leadframe from a material with a similar coefficient of expansion to that of the circuit carrier, and by not bonding the insulation element and the leadframe. This also significantly reduces the risk of cracking in the leadframe compared to cracking in an electrically conductive layer of a second circuit carrier, and potentially enables a longer service life for the circuit arrangement.
[0022] The pressure device enables large contact surfaces, independent of temperature, and thus good heat transfer between the heat sink, the insulation element and the leadframe, thus improving heat dissipation of the semiconductor component.
[0023] Replacing the second circuit carrier of WO 2020 / 249479 A1 with a combination of the leadframe and the insulation element also advantageously reduces the cost of the circuit arrangement, since no expensive second circuit carrier is required. Furthermore, the thickness of the leadframe can be made significantly greater than the thickness of an electrically conductive layer of the second circuit carrier of WO 2020 / 249479 A1, which leads to improved heat dissipation across the semiconductor component.
[0024] The wording that the circuit arrangement has a semiconductor component does not exclude the possibility that the circuit arrangement has a plurality of semiconductor components and is therefore to be understood such that the circuit arrangement has at least one semiconductor component. The same applies to the wording that the circuit arrangement has a circuit carrier or a leadframe. For example, the circuit arrangement can have a plurality of semiconductor components, each of which is arranged between a circuit carrier and a leadframe, and an insulation element arranged between the heat sink and each leadframe. In this case, the circuit arrangement can have one circuit carrier on which all of the semiconductor components are arranged, or a plurality of circuit carriers, each of which has at least one semiconductor component arranged on it.Accordingly, the circuit arrangement can have one leadframe for all semiconductor components or multiple leadframes for at least one semiconductor component each. If the circuit arrangement has multiple semiconductor components, for example, at least one pair of two of these semiconductor components is electrically connected to form a half-bridge.
[0025] The interconnection of two semiconductor components can be effected, for example, via a circuit carrier on which both semiconductor components are arranged, or via a further circuit carrier which is electrically connected to two circuit carriers on each of which one of the two semiconductor components is arranged.
[0026] In one embodiment of the invention, the insulation element is a ceramic plate. For example, the ceramic plate is made of aluminum oxide, aluminum nitride, or silicon nitride. Such an insulation element exhibits high thermal conductivity and mechanical stability against the pressing force of the pressing device.
[0027] In another embodiment of the invention, the insulation element is an insulation film. For example, the insulation film is made of a silicone-based material. Due to its flexibility, an insulation film is advantageously largely insensitive to temperature changes and the pressing force of the pressing device and is therefore also suitable as an insulation element. In a further embodiment of the invention, the heat sink has a recess into which the insulation element is inserted. The recess advantageously determines the position of the insulation element, in particular if the insulation element is not firmly bonded to the heat sink.
[0028] In a further embodiment of the invention, the insulation element is not materially connected to either the heat sink or the leadframe. As already explained above, a materially connected connection of the insulation element to the heat sink or the leadframe is not desired, so that the insulation element can be pressed against the leadframe and the heat sink by the pressing device flexibly and independently of temperature changes of other components of the circuit arrangement.
[0029] In a further embodiment of the invention, a thermally conductive medium is arranged between the insulation element and the heat sink and / or between the insulation element and the leadframe. For example, the thermally conductive medium is a thermally conductive oil. The thermally conductive medium advantageously increases the heat transfer between the insulation element and the heat sink and / or between the insulation element and the leadframe and thus, in particular, improves the heat dissipation of the semiconductor component.
[0030] In a further embodiment of the invention, the leadframe and the circuit carrier have similar thermal expansion coefficients. This counteracts warping of the leadframe and the circuit carrier due to large differences in the thermal expansion coefficients of the leadframe and the circuit carrier.
[0031] In a further embodiment of the invention, the leadframe is made of copper. This embodiment of the invention is particularly advantageous when the first circuit carrier is a printed circuit board, since conventional printed circuit boards have a similar coefficient of thermal expansion to copper. In a further embodiment of the invention, the pressing device has at least one screw connection which connects the heat sink to the circuit carrier or to a pressing plate which is arranged on a side of the circuit carrier facing away from the heat sink. Such a screw connection is a simple, cost-effective embodiment of the pressing device which can be implemented with a flexible pressing force.
[0032] In a further embodiment of the invention, the circuit carrier is a printed circuit board, in particular a multilayer printed circuit board. Designing the circuit carrier as a printed circuit board has the particular advantage that the semiconductor component can be connected to conductor tracks and vias running in or on the printed circuit board.
[0033] In a further embodiment of the invention, the semiconductor component has a first load terminal, which is arranged on a side of the semiconductor component facing the circuit carrier and is electrically connected to a contact pad of the circuit carrier, and a second load terminal, which is arranged on a side of the semiconductor component facing the leadframe and is electrically connected to the leadframe. In other words, the semiconductor component has load terminals arranged on opposite sides, which are each electrically contacted with the circuit carrier and with the leadframe. This enables contacting of the semiconductor component that is analogous to the contacting known from WO 2020 / 249479 A1.
[0034] In a further embodiment of the invention, the semiconductor component is a transistor, a diode, or a thyristor. A circuit arrangement according to the invention is suitable for all of these semiconductor components, since all of these semiconductor components can be designed such that their load terminals can be arranged on opposite sides of the semiconductor component.
[0035] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings.
[0036] FIG 1 is a schematic sectional view of a first embodiment of a circuit arrangement,
[0037] FIG 2 is a schematic sectional view of a second embodiment of a circuit arrangement.
[0038] Corresponding parts in the figures are provided with the same reference symbols.
[0039] Figure 1 (FIG 1) shows a schematic sectional view of a first embodiment of a circuit arrangement 1.
[0040] The circuit arrangement 1 comprises a circuit carrier 3, a semiconductor component 5, a leadframe 7, an insulation element 9, a heat sink 11 and a pressing device 13.
[0041] The semiconductor component 5 is arranged between the circuit carrier 3 and the leadframe 7. In the illustrated embodiment, the semiconductor component 5 is a transistor with a control terminal, a first load terminal and a second load terminal. The control terminal and the first load terminal face the circuit carrier 3, and the second load terminal faces the leadframe 7. In other embodiments, the semiconductor component 5 can be a diode or a thyristor, for example. If the semiconductor component 5 is a diode, it has no control terminal, but only two load terminals.
[0042] The control terminal of the semiconductor component 5 is connected to a first contact pad 15 of the circuit carrier 3. The first load terminal of the semiconductor component 5 is connected to a second contact pad 17 of the circuit carrier 3. The first contact pad 15 and the second contact pad 17 are arranged on a side of the circuit carrier 3 facing the semiconductor component 5. The second load terminal of the semiconductor component 5 is connected to the leadframe 7 by a connecting material 19, for example a solder or sintered material.
[0043] The circuit carrier 3 is, for example, a multi-layer printed circuit board in which vias run which connect each contact pad 15, 17 to at least one conductor track of the printed circuit board.
[0044] The leadframe 7 is made of a material that has a similar coefficient of thermal expansion to the circuit carrier 3. If the circuit carrier 3 is a printed circuit board, the leadframe 7 can be made of copper, for example. The leadframe 7 is further connected to the circuit carrier 3 via electrically conductive connections 20. The remaining space between the leadframe 7 and the circuit carrier 3 is filled with a potting material 21, for example a casting resin.
[0045] The heat sink 11 and the insulation element 9 are arranged on a side of the leadframe 7 facing away from the semiconductor component 5. The heat sink 11 has a recess 23 on the leadframe side, the extent of which projects beyond the extent of the leadframe 7. The insulation element 9 is inserted into the recess 23, the extent of which also projects beyond the extent of the leadframe 7. The insulation element 9 is thus arranged between the leadframe 7 and the heat sink 11 in the recess 23 of the heat sink 11. A heat-conducting medium 25 is arranged between the insulation element 9 and the heat sink 11 and between the insulation element 9 and the leadframe 7. The heat-conducting medium 25 is, for example, a heat-conducting oil. The insulation element 9 is therefore neither materially connected to the heat sink 11 nor to the lead frame 7, but is only inserted into the recess 23 of the heat sink 11.
[0046] The insulation element 9 is made of an electrically insulating material with good thermal conductivity. For example, the insulation element 9 is a ceramic plate. The ceramic plate is made, for example, of aluminum oxide, aluminum nitride, or silicon nitride. Alternatively, the insulation element 9 is an insulation foil, which is made, for example, of a silicone-based material.
[0047] The pressing device 13 is configured to press the assembly comprising the circuit carrier 3, the semiconductor component 5, and the leadframe 7 against the insulation element 9 and the heat sink 11. In Figure 1, the pressing device 13 is only schematically represented by an arrow symbol, which represents the direction of a pressing force exerted by the pressing device 13.
[0048] Figure 2 (FIG 2) shows a schematic sectional view of a second embodiment of a circuit arrangement 1. This embodiment differs from the embodiment shown in Figure 1 only in that it schematically shows a specific design of the pressing device 13. In this embodiment, the pressing device 13 has a pressing plate 27 and screw connections 29. The pressing plate 27 is arranged on a side of the circuit carrier 3 facing away from the heat sink 11. The screw connections 29 connect the pressing plate 27 to the heat sink 11 and in doing so exert a pressing force via the pressing plate 27 which presses the assembly of the circuit carrier 3, the semiconductor component 5 and the leadframe 7 against the insulation element 9 and the heat sink 11.
[0049] If the circuit carrier 3 is stable enough, the second embodiment shown in Figure 2 can be modified into a third embodiment in which the pressure plate 27 is omitted and the screw connections 29 connect the circuit carrier 3 directly to the heat sink 11. Although the invention has been illustrated and described in detail using preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.
Claims
Patent claims 1. Circuit arrangement (1) , comprising - a circuit carrier (3) , - a leadframe (7) , - a semiconductor device (5) arranged between the circuit carrier (3) and the leadframe (7) , - a heat sink (11) arranged on a side of the leadframe (7) facing away from the semiconductor device (5) , - an electrically insulating insulating element (9) arranged between the leadframe (7) and the heat sink (11) and - a pressing device (13) which is configured to press the circuit carrier (3), the semiconductor device (5), the leadframe (7), the insulating element (9) and the heat sink (11) together, - wherein the circuit carrier (3) is a printed circuit board, in particular a multilayer printed circuit board.
2. Circuit arrangement (1) according to claim 1, wherein the insulating element (9) is a ceramic plate.
3. Circuit arrangement (1) according to claim 2, wherein the ceramic plate is made of aluminium oxide, aluminium nitride or silicon nitride.
4. Circuit arrangement (1) according to claim 1, wherein the insulating element (9) is an insulating film.
5. Circuit arrangement (1) according to claim 4, wherein the insulating film is made of a silicone-based material.
6. Circuit arrangement (1) according to one of the preceding claims, wherein the heat sink (11) has a recess (23) into which the insulating element (9) is inserted.
7. Circuit arrangement (1) according to one of the preceding claims, wherein the insulating element (9) is neither connected to the cooling- body (11) is still conclusively connected to the leadframe (7) material.
8. Circuit arrangement (1) according to one of the preceding claims, wherein a thermal conducting medium (25) is arranged between the insulating element (9) and the heat sink (11) and / or between the insulating element (9) and the leadframe (7).
9. Circuit arrangement (1) according to claim 8, wherein the heat conducting medium (25) is a heat conducting oil.
10. Circuit arrangement (1) according to one of the preceding claims, wherein the leadframe (7) and the circuit carrier (3) have similar coefficients of thermal expansion.
11. Circuit arrangement (1) according to one of the preceding claims, wherein the leadframe (7) is made of copper.
12. Circuit arrangement (1) according to one of the preceding claims, wherein the pressure device (13) has at least one screw connection (29) that connects the heat sink (11) to the circuit carrier (3) or to a pressure plate (27) that is arranged on a side of the circuit carrier (3) facing away from the heat sink (11).
13. Circuit arrangement (1) according to one of the preceding claims, wherein the semiconductor device (5) has a first load terminal which is arranged on a side of the semiconductor device (5) facing the circuit carrier (3) and is electrically connected to a contact pad (17) of the circuit carrier (3), and a second load terminal which is arranged on a side of the semiconductor device (5) facing the leadframe (7) and is electrically connected to the leadframe (7).
14. Circuit arrangement (1) according to one of the preceding claims, wherein the semiconductor device (5) is a transistor or a diode or a thyristor.