Power module comprising a frame structure

Abstract

The invention relates to a power module (10) comprising a frame structure (18), containing an insulation material (20), and at least one plastics frame (12). Circuit elements which are electrically contacted via contacts (22) are arranged in the power module. The contacts (22) are designed as contact tabs (24) which are integrated into the frame structure (18) and are accessible from a top side (60) and a bottom side (58) and to which at least one creepage distance (40, 42) is assigned. The invention also relates to the use of the power module (10) in power electronics systems or inverters for electric drives.

Description

[0001] R.418073

[0002] - 1 -

[0003] Description

[0004] title

[0005] Performance module with a framework structure

[0006] Technical field

[0007] The invention relates to a power module with a frame structure containing an insulating material, comprising at least one plastic frame in which circuit elements are arranged on a circuit carrier and electrically contacted via contacts. Furthermore, the invention relates to the use of the power module in power electronics or inverters of electric drives.

[0008] State of the art

[0009] DE 102014219998 B4 discloses a power module, in particular for providing a phase current for an electric motor. The power module comprises a circuit carrier with a surface, at least two first contact surfaces on the surface, and at least two first power transistors, each having a ground contact surface. One of the first power transistors of the at least two first power transistors is directly arranged on one of the first contact surfaces and electrically connected to the respective first contact surface via its ground contact surface. The power module also comprises a second contact surface on the surface and at least two second power transistors, each having a ground contact surface.The at least two secondary power transistors are arranged directly on the second contact surface and are electrically connected to the second contact surface via their respective ground contact surfaces. Furthermore, the power module comprises at least two third contact surfaces on the surface, with the at least two secondary power transistors having their ground contact surfaces on the surface of the circuit carrier R.418073.

[0010] - 2 -

[0011] Each of the sides facing away from the power module has an additional contact surface, and each of the at least two second power transistors is electrically connected via its additional contact surface to one of the at least two third contact surfaces. The at least two first contact surfaces and the at least two third contact surfaces are arranged alternately one after the other in a longitudinal direction of the power module, and the second contact surface is arranged next to the at least two first contact surfaces and the at least two third contact surfaces.The second contact surface has at least two contact areas, with each of these at least two contact areas located next to one of the at least two first power transistors. The at least two first power transistors each have an additional contact surface on their sides facing away from the surface of the circuit carrier, and each first power transistor of the at least two first power transistors is electrically connected via its additional contact surface to the adjacent contact area of ​​the at least two contact areas of the second contact surface. The at least two contact areas of the second contact surface and the at least two second power transistors are arranged alternately along the longitudinal axis.

[0012] EP 2 418925 B1 relates to an electrical contact between a flexible film having at least one conductor track and at least one electrical contact of a sensor or control unit. In this connection, an end section of the flexible film is electrically contacted at a contact point by means of heat input, wherein the end section of the flexible film is positioned against the aforementioned electrical contacts at the contact point. The end section of the flexible film is designed as a corrugation, in particular as a deflection.

[0013] Disclosure of the invention

[0014] According to the invention, a power module is proposed, comprising a frame structure containing an insulating material and at least one plastic frame in which circuit elements are arranged on a circuit carrier and electrically contacted via contacts. The contacts are designed as contact tabs integrated into the frame structure, accessible from a top and a bottom, and to which at least one creepage distance is assigned. R.418073

[0015] - 3 -

[0016] The solution proposed according to the invention advantageously avoids damage to the frame structure during the formation of the material-bonded connection, which is essentially carried out by laser welding.

[0017] In an advantageous further development of the power module proposed according to the invention, a first free space is provided above the integrated contact tabs and a second free space is provided below the integrated contact tabs. This allows access to the material of the integrated contact tabs from both sides without excessively heating the surrounding frame structure during the creation of the metallurgical bond at the integrated contact tabs. Furthermore, this design enables the metallurgical connection of the power contacts from both the underside and the top side.

[0018] In an advantageous embodiment of the power module proposed according to the invention, creepage paths extend between adjacent contact tabs, formed by the first and second webs. Their length allows for a variable selection of the contact point, i.e., the location where the metallurgical bond, which is essentially produced by laser welding, is established. Due to a favorable design of the welding tools, the design is also suitable for use, for example, in resistance welding.

[0019] The shape of the webs between the contact tabs allows creepage distances, which serve for insulation, to be individually adjusted for different voltage or pollution classes.

[0020] In an advantageous further development, the performance module according to the invention provides that the at least one creepage distance, starting from the first web and / or the second web, extends in a substantially planar manner to a projection of the plastic frame.

[0021] In a further advantageous embodiment of the power module proposed according to the invention, an extension of the at least one creepage distance is formed in at least one of the projections of the plastic frame. R.418073

[0022] - 4 -

[0023] The creepage distance can be extended, for example, by a channel, such as a semicircular or spiral shape, which can be formed in a plastic frame, thereby improving insulation safety.

[0024] Furthermore, in the power module proposed according to the invention, the first and second webs in the plastic frame are designed as design elements whose respective outer surfaces represent an extension of the creepage distances. Designing the webs as design elements, for example in the form of rectangles or squares with or without angled sides or the like, extends the creepage distance without requiring additional components in the power module proposed according to the invention to improve creep resistance.

[0025] Furthermore, the power module proposed according to the invention is designed such that at least one heat sink is arranged below the plastic frame. The heat sink is at chassis potential (zero potential), while the remaining contacts are at high-voltage potential. The provided design serves to isolate the chassis potential from the high-voltage potential.

[0026] Furthermore, in the power module proposed according to the invention, the contact tabs are integrated into the plastic frame in such a way that at least three sides of the contact tabs are enclosed by plastic material.

[0027] Finally, the invention relates to the use of the power module in power electronics or in inverters of electric drives.

[0028] Advantages of the invention

[0029] The solution proposed according to the invention ensures that the connections, designed as integrated contact tabs, are contacted during the formation of material-bonded joints, particularly during laser welding, in such a way that damage to the plastic material of the surrounding frame structure is prevented. The spaces above and below the contact tabs integrated into the frame structure allow them to be freely accessed from the top and bottom, which R.418073

[0030] - 5 -

[0031] The formation of the material-bonded connections is significantly improved by means of the laser welding process. Furthermore, the solution proposed according to the invention makes it possible to maintain minimum distances between the connections, i.e., the weld points, and the heat sink arranged under the power module, in order to ensure sufficient insulation distance.

[0032] Since an insulating material is located below the material-bonded joint, i.e., on the top or bottom of the contact tabs integrated into the frame structure, damage can be ruled out. In particular, creepage paths can be formed in the solution proposed according to the invention, extending from webs in the plastic frame to these opposing projections. With a suitable design, no additional elements are required to form the creepage paths.

[0033] If the first and second webs of the plastic frame are designed as design elements, for example as rectangles, squares or rectangles with beveled sides, the creepage distance can be extended; furthermore, it is possible to extend the creepage distance by forming extensions of the actual creepage distance in the projections of the plastic frame that border the actual creepage distance by means of channels or spiral arcs or the like.

[0034] Brief description of the drawings

[0035] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0036] They show:

[0037] Figure 1 shows a perspective top view of a power module with laterally extending contacts.

[0038] Figure 2 shows a perspective view of a power module with contact tabs integrated into its frame structure along the long side, R.418073

[0039] - 6 -

[0040] Figure 3 shows a perspective view of an enlarged section of the power module according to Figure 2, showing the heat sink from the underside and

[0041] Figure 4 shows a perspective view of one long side of the power module according to Figures 2, 3 and 4, tilted and viewed from below.

[0042] Embodiments of the invention

[0043] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0044] Figure 1 shows a power module 10, which is provided with a plastic frame 12 made of a plastic compound. The power module 10 comprises a longitudinal side 14 and a transverse side 16. Laterally projecting contacts 22 protrude from the plastic material of the plastic frame 12 on the longitudinal sides 14; these contacts serve for the electrical contacting of the semiconductor components or circuit elements arranged in the power module 10, which are not shown in detail here.

[0045] Figure 2 shows a perspective top view of the power module 10. In the embodiment of the power module 10 shown in Figure 2, several plastic frames 12 are provided. The plastic frames 12 are embedded in a frame structure 18, which has a longitudinal side 14 and a shorter transverse side 16 extending perpendicular to this, resulting in a rectangular base for the power module 10. Groups of signal contacts 26, oriented essentially vertically, protrude from a top surface 60 of the frame structure 18. Figure 2 further shows that the frame structure 18, which is essentially made of an insulating material 20, optionally with filler or glass fiber components, or a mixture of several insulating materials 20, has a number of [missing information] embedded in the frame structure 18R.418073 along the longitudinal side 14.

[0046] - 7 -

[0047] The frame structure 18 features embedded, integrated contact tabs 24 made of metallic material. These contact tabs 24, integrated into the frame structure 18, are freely accessible from both the top 60 and a bottom 58 of the frame structure 18, thus allowing for easy access via automated manufacturing processes for the formation of material-jointed connections by laser welding. The free length 38 of the contact tabs 24 integrated into the frame structure 18 is dimensioned such that, during the formation of material-jointed connections on the top or bottom, the heat input into the frame structure 18, which defines the free length 38 of the integrated contact tabs 24, or into its insulating material 20, is limited, preventing damage.

[0048] As can be seen in Figure 2, three integrated contact tabs 24 are embedded in the frame structure 18 along the longitudinal side 14. The free length 38 of the integrated contact tabs 24 is bounded, as shown in Figure 2, by a first web 32 and a second web 34 opposite it, which are part of the frame structure 18. On the sides of the first and second webs 32, 34 facing away from the free length 38 of the integrated contact tabs 24, first and second creepage distances 40, 42, indicated in the top view of Figure 2, extend.

[0049] Figure 3 shows an enlarged section of the longitudinal side 14 of the power module 10 shown in perspective top view in Figure 2.

[0050] Figure 3 shows that, according to this representation, the integrated contact tab 24 extends between the first web 32 and the second web 34. Above and below the integrated contact tab 24, the first clearance 28 is shown, and opposite it, on the underside of the integrated contact tab 24, the second clearance 30 is shown. When forming the material-bonded connection at the integrated contact tab 24, the first and second clearances 28, 30 are dimensioned such that a laser tool can create a material-bonded connection on both surfaces of the integrated contact tab 24 at flexible positions.

[0051] Furthermore, the illustration according to Figure 3 shows that the integrated contact tab 24 between the first web 32 and the second web 34 is configured with the previously mentioned free length 38. The first and second webs 32, 34R.418073

[0052] - 8 -

[0053] are part of the plastic frame 12 or the frame structure 18 and are designed such that they can be configured as design elements 44. In this context, design elements 44 refer to the configuration of the first and second webs 32, 34 such that their surfaces define the first and second creepage distances 40, 42 through their respective outer surfaces. Figure 3 shows that the first and second creepage distances 40, 42 extend from the first and second webs 32, 34 on the sides facing away from the integrated contact tab 24. These creepage distances are shorter than the free length 38 of the integrated contact tabs 24. The first and second creepage distances 40, 42 extend from the outer surfaces of the first and second webs 32, 34, configured as design elements 44, to projections 48 of the plastic frame 12 or the frame structure 18.Extensions 46 of the creepage paths 40, 42 can be formed in these as curved or spirally shaped channels. Furthermore, the creepage paths 40, 42 are arranged such that they run essentially in a horizontal plane aligned with the orientation of the integrated contact tabs 24.

[0054] A heat sink 36 is attached to the underside of the power module 10. This heat sink comprises a number of guide pins 50 and a number of pinfin heat sinks 52. In the preceding context, "zero potential" refers to the voltage potential at which the heat sink 36 is located. This differs from the voltage potential at which all other contacts of the power module 10 are located. Therefore, insulation via creepage distances, such as the first and second creepage distances 40 and 42, of sufficient length, is required. Reference numeral 50 denotes a guide pin that is part of the plastic frame 12 and ensures easy positioning and alignment when connecting it to the heat sink 36. Pinfin heat sinks 52 are pin-shaped elements consisting, for example, of a copper plate a few millimeters thick with pins attached to it.

[0055] Figure 3 further shows that the length 56 of the first and second creepage distances 40, 42 is smaller than the aforementioned free length 38 of the contact tabs 24.R.418073 integrated into the frame structure 18.

[0056] - 9 -

[0057] As can be seen in Figure 4, in this perspective view of the longitudinal side 14 of the power module 10 according to the embodiments shown in Figures 2 and 3, the contact tabs 24 integrated into the frame structure 18 are also accessible from the side. On both sides of the first and second webs 32, 34 extend said creepage sections 40, 42, which have a length 56 that is shorter than said free length 38 of the contact tabs 24 integrated into the frame structure 18. The guide pins 50 are arranged on the underside of the heat sink 36, as well as a number of pin fin heat sinks 52 embedded vertically in the heat sink 36.

[0058] It should also be emphasized that in the embodiment variants of Figures 3 and 4, in which the first web 32 or the second web 34 of the plastic frame 12 or the frame structure 18 are designed as design elements 44, these flanks 54 can be included, as indicated in the enlarged view of the longitudinal side 14 according to Figure 3 as well as in the perspective view of the longitudinal side 14 according to Figure 4.

[0059] The solution proposed according to the invention addresses the fact that damage to the frame structure 18, made of insulating material 20, can be prevented when producing material-bonded connections in an automated manufacturing process, such as laser beam processing. Due to the clearances 28 and 30 on both sides of the integrated contact tabs 24, the high material thicknesses that would otherwise be necessary to avoid damaging the surrounding plastic insulating materials can be avoided. Furthermore, the solution proposed according to the invention ensures that minimum distances are maintained between the material-bonded connection points on the contact tabs 24 integrated into the frame structure 18 and the heat sink 36 to guarantee sufficient insulation clearance.Since there is no insulating material below the contact tabs 24 integrated into the frame structure 18, and thus below the weld point which assumes the highest temperatures during the formation of the material-jointed connection by means of laser welding, damage to the same can be prevented by the solution proposed according to the invention. R.418073.

[0060] - 10 -

[0061] A space located between the contact tabs 24 integrated into the frame structure 18 and the cooling element 36 can be used for creepage distances 40, 42 or their extensions 46 in the projections 48, as shown in Figures 3 and 4. If the first and second webs 32, 34 are advantageously designed as design elements 44, the creepage distance 40, 42 between the material-bonded connection points at the contact tabs 24 integrated into the frame structure 18 and the cooling element 36, which is at zero potential, can be increased without the need for additional components.

[0062] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible that fall within the bounds of what is considered skilled in the art.

Claims

R.418073 - 11 - Claims 1. Power module (10) with a frame structure (18) containing an insulating material (20), with at least one plastic frame (12) in which circuit elements are arranged which are mounted on a circuit carrier and are electrically contacted via contacts (22), characterized in that the contacts (22) are designed as contact tabs (24) integrated into the frame structure (18), which are accessible from a top (60) and a bottom (58) and to which at least one creepage distance (40, 42) is assigned.

2. Power module (10) according to claim 1 , characterized in that a first free space (28) is provided above the integrated contact tabs (24) and a second free space (30) is provided below the integrated contact tabs (24).

3. Power module (10) according to claims 1 to 2, characterized in that creepage distances (40, 42) extend between adjacent contact tabs (24), designed as first web (32) and second web (34) of the frame structure (18).

4. Power module (10) according to claims 1 to 3, characterized in that at least one creepage distance (40, 42; 46) extends on at least one of the webs (32, 34) on the outer side facing away from the integrated contact tab (24).

5. Power module (10) according to claims 1 to 4, characterized in that the at least one creepage distance (40, 42), starting from the first web (32) and / or the second web (34) to a projection (48) of the plastic frame (12), extends substantially in a plane. R.418073 - 12 - 6. Power module (10) according to claims 1 to 5, characterized in that an extension (46) of the at least one creepage distance (40, 42) is formed in at least one of the projections (48) of the plastic frame (12).

7. Power module (10) according to claims 1 to 6, characterized in that the first and second webs (32, 34) in the plastic frame (12) are designed as design elements (44) whose respective outer surfaces represent an extension of the creepage distances (40, 42).

8. Power module (10) according to claims 1 to 7, characterized in that at least one heat sink (36) is arranged below the plastic frame (12).

9. Power module (10) according to claims 1 to 8, characterized in that the contact tabs (24) are integrated into the plastic frame (12) such that at least three sides of the contact tabs (24) are enclosed by plastic material.

10. Use of the power module (10) according to any one of claims 1 to 9 in power electronics or in inverters of electric drives.

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