Power semiconductor module

Abstract

The invention relates to a power semiconductor module. The power semiconductor module has a circuit carrier and at least one semiconductor switch, in particular a semiconductor switch half-bridge, which is connected to the circuit carrier. The circuit carrier of the power semiconductor module has an electrically insulating layer, in particular a ceramic layer, and two electrically conductive layers which are separated from each other by insulating regions, in particular insulating trenches, and which are each connected to the electrically insulating layer. And the conductive layers are electrically connected with contact gap joints of the semiconductor switches respectively. The power semiconductor module has at least one or only one metal molded body which is connected to the electrically conductive layers and is designed to melt and eliminate the insulating regions when a predetermined temperature is exceeded, and to electrically connect the electrically conductive layers separated from one another by the insulating regions to one another, in particular to a low resistance.

Description

Technical Field

[0001] The invention relates to a power semiconductor module, in particular a power semiconductor module having a circuit carrier and at least one semiconductor switch, in particular a semiconductor switch half-bridge, connected to the circuit carrier. Background Art

[0002] DE 198 43 309 A1 discloses a short-circuit-resistant IGBT module in which an additional layer enables a stable short circuit. The layer is in contact with the main electrode of the semiconductor chip as a component of a film, paste or solder. For example, the layer contains silver and forms a eutectic with the semiconductor material, the melting point of which is lower than the melting points of the two partner materials. Summary of the invention

[0003] According to the invention, the circuit carrier of the power semiconductor module of the above type has an electrically insulating layer, in particular a ceramic layer, and two electrically conductive layers separated from each other by an insulating region, in particular an insulating trench, and connected to the electrically insulating layer, respectively. The electrically conductive layers are electrically connected to the contact gap terminals of the semiconductor switch, respectively. The power semiconductor module has at least one or only one metal molded body, which is connected to the electrically conductive layer and is designed to melt when a predetermined temperature is exceeded, eliminate the insulating region, and electrically connect the electrically conductive layers separated from each other by the insulating region to each other, in particular electrically connect them with low resistance.

[0004] Advantageously, the semiconductor switch can therefore be short-circuited safely.

[0005] It has been recognized that, particularly in electric vehicles having an electronic control device and an inverter for supplying an electric drive machine of the vehicle, in the event of a failure of the control device or the inverter, large mechanical counter-torques can be generated by means of currents induced in the machine, causing the vehicle to perform very strong braking.

[0006] Advantageously, a power semiconductor module designed in this way, which is, for example, part of an inverter of an electric vehicle, can be used to safely short-circuit the stator coils of an electric machine, so that such strong braking behavior of the electric vehicle in the event of a fault in the control electronics can be prevented.

[0007] The insulating region, in particular the insulating trench, is preferably formed by a surface region of the circuit carrier, in particular a surface region of the mounting side of the circuit carrier, to which the conductive layer is applied as a redistribution structure. The outwardly directed surface of the insulating region is preferably formed by an electrically insulating layer of the circuit carrier.

[0008] Preferably, the circuit carrier is formed by a ceramic circuit carrier having an electrically insulating ceramic layer and at least two electrically conductive layers. The circuit carrier is, for example, a DCB substrate (DCB=direct copper bonding), an AMB substrate (AMB=active metal brazing), an IMS substrate (IMS=insulated metal substrate) or an HTCC circuit carrier (HTCC=high temperature cofired ceramic) or LTCC circuit carrier (LTCC=low temperature cofired ceramic), a printed circuit board or a lead frame (also known as a stamped grid).

[0009] The semiconductor switch is preferably a MOS-FET, MIS-FET, IGBT (IGBT Insulated Gate Bipolar Transistor), transistor, SiC-FET, GaN-FET or GaO-FET or diamond semiconductor switch. The semiconductor switch can be an IGBT (IGBT=Insulated Gate Bipolar Transistor) or a FET (FET=Field Effect Transistor).

[0010] Preferably, the bypass diode inherently present in the semiconductor switch, which generates strong heating when current flows through it, can be short-circuited by means of the metal shaped body. The bypass diode thus forms a heat source which can heat the semiconductor until the metal shaped body melts and effectively forms a short circuit.

[0011] The electrically conductive layer of the circuit carrier is preferably a copper layer. The electrically insulating layer of the circuit carrier is preferably a ceramic layer, an aluminum oxide layer or an aluminum nitride layer or a silicon nitride layer.

[0012] In a further embodiment, the electrically insulating layer, in particular the ceramic layer, is formed by a boride or a carbide. For example, the electrically insulating layer is a silicon carbide layer, a boron carbide layer or a boron nitride layer.

[0013] In a preferred embodiment, the power semiconductor module, in particular the semiconductor switch half-bridge, has a high-side semiconductor switch and a low-side semiconductor switch. Further preferably, the power semiconductor module is configured such that for each semiconductor switch, in particular the high-side semiconductor switch and the low-side semiconductor switch, at least one metal shaped body is arranged such that each semiconductor switch can be short-circuited when a predetermined temperature, in particular the temperature of the eutectic, is exceeded.

[0014] In a preferred embodiment, the metal shaped body is formed by eutectic formation. Advantageously, all components, in particular alloy components, can be changed from a solid aggregate state to a liquid aggregate state at a predetermined temperature. Advantageously, a sudden volume expansion can thus be performed, so that the bridging of the short-circuit gap in the power semiconductor module can be accelerated by means of the volume expansion.

[0015] In a preferred embodiment, the conductive layers are arranged in a common plane formed by the electrically insulating layer. The conductive layers are preferably each formed by a conductor track of the circuit carrier. Advantageously, the short circuit of the semiconductor switch can thus be formed economically on the circuit carrier.

[0016] In a preferred embodiment, the metal shaped body is formed by a metal shaped part, in particular a soldered shaped part, which is connected to the circuit carrier in a material-locking manner using a flux. Preferably, the flux has a lower melting temperature than the metal shaped part. Advantageously, the metal shaped body can therefore be connected, in particular assembled, with other electronic components, in particular semiconductor switches, to the circuit carrier during an assembly process, in particular during an automated assembly process.

[0017] In a further embodiment, the metal shaped part is bonded to the circuit carrier by means of an adhesive. Advantageously, the position can thus be fixed during molding. For example, the adhesive is an epoxy adhesive or a silicone adhesive.

[0018] In a preferred embodiment of the power semiconductor module, the semiconductor switch and the metal molded body, further preferably at least a part of the circuit carrier, are embedded by means of a plastic block, in particular a molded block. The metal molded body is designed to produce a gap between the plastic block and the circuit carrier in the region of the insulating region when it melts and increases in volume, and thus bridges the insulating region when expanding and expanding in the gap and electrically connects the conductive layers to one another.

[0019] Advantageously, a short-circuit fuse can therefore be formed in a power semiconductor module, which is embedded in the power semiconductor module together with electronic components, in particular power semiconductor switches or other additional electronic components. The short-circuit fuse can therefore be an economically fixed electronic component of the power semiconductor module.

[0020] In a preferred embodiment, the circuit carrier has a viscosity-reducing layer in the region of the insulating region, which covers the insulating layer or additionally covers the conductive layer. Advantageously, during expansion of the metal molded body, the molded piece can be separated, in particular slightly separated, from the circuit carrier there.

[0021] Preferably, the ratio of the thickness of the circuit carrier to the thickness of the molding block is 1:5.

[0022] In a preferred embodiment, the viscosity-reducing layer is a lacquer layer. The lacquer layer is, for example, a solder resist lacquer layer. In a further embodiment, the layer is a plastic layer, for example a gel layer or a silicone gel layer. In a further embodiment, the layer is a particle layer. Advantageously, the viscosity-reducing layer can thus be formed in the region of the insulating region for the casting block.

[0023] In a preferred embodiment, the conductive layer, in particular the conductor tracks, are coated with a solder, in particular a tin layer, in the region of the insulating region. Advantageously, therefore, when the liquefied metal molded body flows in the gap, the material bonding, in particular the electrically conductive connection of the conductive layer can be accelerated.

[0024] In a preferred embodiment, the metal shaped body is formed by a metal foam. Advantageously, a metal foam having a metal lattice and an air volume surrounded by the metal lattice can easily melt when heated, since the heat capacity of the metal shaped body thus formed is smaller than that of a solid metal shaped body of the same volume.

[0025] In a preferred embodiment, the metal shaped body comprises tin. Further advantageous components of the metal shaped body are indium, bismuth, lead, copper, silver, antimony, gold, aluminum, germanium, silicon or combinations of the aforementioned metals.

[0026] Advantageously, therefore, the electrical connection of the electrically conductive layers can be reliably carried out at a predetermined temperature, in particular at the temperature of the eutectic.

[0027] The predetermined temperature is preferably between 400 and 700 degrees Celsius, further preferably between 450 and 550 degrees Celsius, and particularly preferably in the range of 500 degrees Celsius. Advantageously, short-term heating during operation of the power semiconductor module can thus be safely distinguished from faults of the power semiconductor module.

[0028] In a preferred embodiment of the power semiconductor module, at least one metal shaped body is formed on each of the two conductive layers. The metal shaped bodies can preferably flow toward each other when melted. Advantageously, the short-circuit process of the semiconductor switch can therefore be accelerated when a predetermined temperature is exceeded. Thus, the aforementioned gap, which can be formed in the region of the insulating region when liquefied and therefore when the metal shaped body expands, can be quickly closed from both sides by the liquid metal of the metal shaped body expanding in the gap.

[0029] The invention also relates to an electric vehicle having at least one power semiconductor module according to the type described. The electric vehicle has an inverter with at least one power semiconductor module, wherein the inverter is connected to at least one electric drive machine of the electric vehicle. The inverter is configured to supply power to the drive machine to generate a rotating magnetic field. Advantageously, in an electric vehicle having a power semiconductor module, in the event of a fault in the power electronics, a strong deceleration can be avoided, so that the vehicle having the inverter configured in this way can gradually coast to a stop by using the semiconductor switch half-bridge in the power semiconductor module that is thus short-circuited. In this case, the high-voltage battery terminal, in particular the positive terminal or the negative terminal, can be connected to the phase terminal with low resistance by means of a metal bridge.

[0030] The invention also relates to a method for deactivating an electric vehicle, in particular an inverter of an electric vehicle. In the method, at least one power semiconductor switch of the inverter is short-circuited by means of a metal shaped part that melts when the inverter becomes overheated. Further preferably, the metal shaped part is arranged and constructed to bridge two mutually spaced conductive layers of a circuit carrier of the inverter. Therefore, advantageously, the short-circuit fuse of the electric vehicle can be constructed on the circuit carrier, in particular as an electronic component of the circuit carrier.

[0031] In a preferred embodiment of the method, the power semiconductor is embedded in the molded body together with the circuit carrier, and the metal molded part preferably expands when melted and separates the molded body from the circuit carrier by the expansion. Further preferably, the liquefied metal of the metal molded part flows in the gap thus produced between the circuit carrier and the molded body along the gap and connects the conductive layers to one another. Advantageously, the semiconductor switch can be short-circuited economically by means of the electronic components, in particular the metal molded part, which are formed on the circuit carrier.

[0032] Preferably, the metal formed part has a wedge shape, a square shape, a column shape, a truncated pyramid shape, or a truncated triangle shape.

[0033] Advantageously, the pointed shape thus formed can preset the crack propagation direction.

[0034] Preferably, one of the electrically conductive layers and / or one of the electrically insulating layers forms a groove or channel in which the liquefied metal of the metal shaped body can flow. Advantageously, a fast short-circuit of the semiconductor switch can thus be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention is now explained below with reference to further figures and exemplary embodiments. Further advantageous embodiment variants result from the combination of the features described in the figures and in the dependent claims.

[0036] Figure 1 An embodiment of a power semiconductor module having a semiconductor switch is shown, the contact gap connections of which can be connected with low resistance via two metal shaped parts;

[0037] Figure 2 Shows Figure 1 The power semiconductor module shown has a contact gap connection of which has been connected with low resistance via two molten metal shaped parts;

[0038] Figure 3 An exemplary embodiment of a metal shaped part is shown, by which the contact gap connections of a semiconductor switch can be connected with low resistance, wherein the metal shaped part projects into an insulating groove formed between the contact gap connections. DETAILED DESCRIPTION

[0039] Figure 1 An embodiment of a power semiconductor module 1 is shown. The power semiconductor module 1 comprises a circuit carrier 2 and at least one or only one power semiconductor switch 6. The power semiconductor switch 6 can be a component of a semiconductor switch half bridge. The circuit carrier 2 comprises an electrically insulating ceramic layer 3 and an electrically conductive layer, which is materially connected to the electrically insulating layer 3, in particular by sintering.

[0040] The conductive layers are, for example, copper layers and are each formed on the side of a ceramic circuit carrier, in particular an electrically insulating layer 3. Two of the conductive layers are spaced apart from each other by an insulating trench 11, and separate conductive layers 4 and 5 are shown. The conductive layers 4 and 5 are each connected to a contact gap connection of a power semiconductor switch 6. The power semiconductor switch 6 is soldered or sintered to the conductive layer 4 using a contact gap connection, in particular a drain connection. Another contact gap connection of the semiconductor switch 6, in particular a source connection, is connected to the conductive layer 4 via a conductive connection, in particular a bonding wire 7 or a soldered or sintered clip.

[0041] In this embodiment, the insulation trench 11 has a width 12 .

[0042] In this embodiment, the power semiconductor module 1 has two metal molded parts, wherein each metal molded part is electrically connected, in particular soldered, to one of the conductive layers in the groove region. The metal molded part 8 is soldered to the conductive layer 4 via the flux 10, and the metal molded part 9 is soldered to the conductive layer 5 via the flux 10.

[0043] The metal molded parts 8 and 9 are each designed to melt at a predetermined temperature, for example between 400 degrees Celsius and 700 degrees Celsius, further exemplarily between 300 degrees Celsius and 500 degrees Celsius, in particular at a predetermined, in particular eutectic temperature, and to raise the molded body 14 of the power semiconductor module 1 in this process, so that a gap is formed between the molded body and the circuit carrier 2, in particular the electrically insulating layer 3, into which the liquefied metal molded parts 8 and 9 flow, in particular toward each other. Thus, the conductive layers 4 and 5 can be electrically connected to each other according to the predetermined temperature, in particular by means of a metal melt connection formed by the metal molded parts 8 and 9.

[0044] The power semiconductor module 1, in particular the circuit carrier 2, further comprises a lacquer layer 13, which is connected to the electrically insulating layer 3 in the region of the insulating trenches 11 and thus covers the insulating layer 3 in the region of the insulating trenches 11. The lacquer layer 13 facilitates the separation of the potting block 14, in particular the molded body, in particular the transfer molded block of the power semiconductor module 1, in the region of the insulating trenches 11 during expansion of the metal molded parts 8 and 9.

[0045] In this embodiment, the potting block 14 covers the side of the circuit carrier 2, with which the electronic component, in this embodiment, the power semiconductor switch 6 is connected to the circuit carrier 2. The metal molded parts 8 and 9 can be connected to the circuit carrier 2 together with the power semiconductor switch 6 by an automated assembly process. The metal molded parts 8 and 9 can be soldered or sintered to the circuit carrier 2. The power semiconductor switch 6 can be bonded, soldered or sintered to the circuit carrier 2. In the case of a power module with a semiconductor switch half bridge, the other power semiconductor switches of the semiconductor switch half bridge can be bridged with low resistance using two other metal molded parts.

[0046] Figure 2 Shows Figure 1 The power semiconductor module 1 ′ is shown in which the potting block 14 ′ is separated from the circuit carrier 2 in the region of the insulating trench 11 . Figure 2 In the exemplary embodiment shown, a predetermined temperature, in particular 500 degrees Celsius, has been exceeded, so that the metal molded parts 8 ′ and 9 ′ are at least partially or completely melted and the casting, in particular the molded body 14 ′, can therefore separate or break apart from the circuit carrier 2 in the region of the insulating groove 11 .

[0047] Figure 2 A gap 15 is shown in which the liquefied metal shaped bodies 8' and 9' flow toward each other and mix and / or connect with each other to form an electrically conductive melt. The electrically conductive layers 4 and 5 are thus connected to each other by the electrically conductive melt in the region of the insulating trench 11 in a manner that bridges the insulating trench 11 over the trench width 12.

[0048] The bonding wire 7 is shown as an example and is guided in this exemplary embodiment so that when the molded body 14, in particular the molded body 14' is disconnected, the electrical connection between the contact gap connection, in particular the source connection of the power semiconductor switch 6, and the conductive layer 5 remains. In this way, the conductive layers 4 and 5 and the contact gap connection of the power semiconductor switch 6 can be securely connected to each other by means of the metal melt not only in the liquid state of the metal melt (formed by the metal molded parts 8 and 9 that are now connected to each other in a material-locking manner), but also in the cooled state and thus solidified state of the metal melt.

[0049] An electric vehicle having an inverter which has at least one power semiconductor module can thus be safely protected from a short circuit.

[0050] Figure 3An embodiment of a power semiconductor module 20 is shown. The power semiconductor module 20 has a circuit carrier 21, which comprises an electrically insulating layer 22, in particular a ceramic layer, and at least two electrically conductive layers, of which two electrically conductive layers 23 and 24 are shown by way of example. The electrically conductive layers 23 and 24 are each connected to a contact gap connection of a power semiconductor switch 28. The power semiconductor switch 28 is part of a semiconductor switch half bridge of the power semiconductor module 20.

[0051] A contact gap connection, in particular a source connection of a power semiconductor switch 28, is connected to the electrically conductive layer 24 by means of a bonding wire 29. The electrically conductive layer 23 is connected to a drain connection of the power semiconductor switch 28.

[0052] An insulating region is formed between the electrically conductive layers 23 and 24 , in the present exemplary embodiment an insulating trench 25 which is at least partially or completely filled with a plastic layer 27 , in particular a lacquer layer, in the present exemplary embodiment.

[0053] In the present exemplary embodiment, the power semiconductor module 20 comprises a metal molded part, in particular only one metal molded part 30 , which is electrically connected to the electrically conductive layer 23 in a manner at least partially resting thereon, in particular by means of soldering.

[0054] Thus, the metal profile 30 projects with a longitudinal section 33 onto the electrically conductive layer 23 and overlaps with the electrically conductive layer on the longitudinal section 33. The metal profile 30 projects with a longitudinal section 34 into the trench 25 and thus covers the insulating trench 25 over a portion of its trench width 26. The insulating distance 34 between the metal profile 30 and the electrically conductive layer 24 is designed such that during operation of the power semiconductor module 20, no arc or electrical breakdown can occur between the metal profile 30 and the electrically conductive layer 24.

[0055] In this embodiment, the metal molded part 30 forms a temperature protection for the power semiconductor module 20. The metal molded part 30 is configured to melt at a predetermined temperature, in particular the temperature of the eutectic, for example 500 degrees Celsius, and separate the molded body 32 of the power semiconductor module 20 from the circuit carrier 21 in the region of the insulating trench 25, and as shown by the dashed gap 31, flow into the gap 31 and thus cover at least a portion of the conductive layer 24 and make electrical contact with the conductive layer. In this way, a conductive bridge formed by the metal melt of the molten metal molded body 30 can be formed, which electrically connects the conductive layers 23 and 24 to each other.

[0056] The plastic layer 27, in particular the lacquer layer, is configured to promote the separation of the molded piece of the molded body 32 from the circuit carrier 21 in the region of the insulating grooves 25. The conductive layer 24 can be coated with a metal layer, in particular a tin layer or a silver layer, at least in the region of the insulating grooves 25, so that the electrical connection, in particular the material-bonded connection, of the molten metal of the liquefied metal molded body 30 and the conductive layer 24 can be promoted.

[0057] The power semiconductor switch 28 and the metal molded component 30 can each be glued, sintered or soldered to the circuit carrier 2 , in particular the electrically conductive layer 23 .

[0058] and Figure 3 Unlike the illustration, the metal molded body 30 can be connected to the electrically conductive layer 24 and, starting from the electrically conductive layer 24 , protrude into the insulating trench 25 .

[0059] In the present embodiment, the metal shaped body 30 is arranged on the conductive layer 23 together with the power semiconductor switch 28 and is conductively connected to the conductive layer. Therefore, a predetermined potential can be advantageously formed on the metal shaped part 30, so that an electric field can be predetermined between the metal shaped part 30 and the conductive layer 24 (and thus the other contact gap joints of the power semiconductor switch 28).

[0060] In other embodiments, the metal molded body 30 can be connected to the circuit carrier 2 in the region of the insulation trench 25 , but not to one of the electrically conductive layers 23 or 24 and thus not to the contact gap connection of the power semiconductor switch 28 .

[0061] In an embodiment in which the metal formed parts are insulated from the contact gap joints of the power semiconductor switch, the insulation distance between the metal formed parts 30 can be constructed so that when an AC voltage, in particular an intermediate circuit voltage of an inverter, is applied to the conductive layers 23 and 24, no electrical breakdown occurs via the metal formed parts 30.

Claims

1. A power semiconductor module (1, 20), comprising a circuit carrier (2, 21) and at least one semiconductor switch or semiconductor switch half-bridge connected to the circuit carrier (2, 21), characterized in that: The circuit carrier (2, 21) comprises an insulating layer (3, 22) and two conductive layers (4, 5, 23, 24) separated from each other by insulating regions, in particular insulating trenches (11, 25) and connected to the insulating layers (6, 22), respectively, the conductive layers being electrically connected to the contact gap connections of the semiconductor switches (6, 28) or the semiconductor switch half bridges, respectively, wherein the power semiconductor module (1, 20) comprises at least one metal molded body (8, 10, 30) connected to the conductive layers (4, 5, 23, 24) and configured to melt when a predetermined temperature is exceeded, to eliminate the insulating regions (11, 25) and to electrically connect the conductive layers (4, 5, 23, 24) separated from each other by the insulating regions (11, 25) to each other.

2. The power semiconductor module (1, 20) according to claim 1, characterized in that The electrically conductive layers (4, 5, 23, 24) are arranged in a common plane formed by the electrically insulating layers (3, 22).

3. The power semiconductor module (1, 20) according to any one of the preceding claims, characterized in that The metal shaped body (8, 9, 30) is formed by a metal shaped part, in particular a soldering shaped part, which is soldered to the circuit carrier (2, 21) by means of a flux (10) which has a lower melting temperature than the metal shaped body (8, 9, 30).

4. The power semiconductor module (1, 20) according to any one of the preceding claims, characterized in that The semiconductor switch (6, 28) and the metal molded part (8, 9, 30) are embedded by means of a plastic block, in particular a molded block (14, 32), and the metal molded body (8, 9, 30) is designed to produce a gap (31) between the plastic block and the circuit carrier (2, 21) in the region of the insulating region (11, 25) during melting, thereby bridging the insulating region (11, 25) and electrically connecting the conductive layers (4, 5, 23, 24) to one another.

5. The power semiconductor module (1, 20) according to claim 4, characterized in that The circuit carrier (2, 21) has, in the region of the insulating region (11, 25), an adhesion-reducing layer which covers the electrically insulating layer (3, 22) or additionally covers the electrically conductive layer (4, 5, 23, 24), so that the plastic block, in particular the molded block (13, 32), can be separated from the circuit carrier (2, 21) when the metal molded body (8, 9, 30) expands.

6. The power semiconductor module (1, 20) according to claim 4, characterized in that The viscosity-reducing layer (13, 27) is a lacquer layer.

7. The power semiconductor module (1, 20) according to any one of the preceding claims, characterized in that The metal shaped body (8, 9, 30) is formed by metal foam.

8. The power semiconductor module (1, 20) according to any one of the preceding claims, characterized in that The metal shaped body (8, 9, 30) contains tin.

9. The power semiconductor module (1, 20) according to any one of the preceding claims, characterized in that The metal shaped bodies (8, 9) are formed on the two electrically conductive layers (4, 5) and are able to flow towards each other when melted.

10. An electric vehicle having at least one power semiconductor module (1, 20) according to any one of the preceding claims, characterized in that The electric vehicle has an inverter with at least one power semiconductor module (1, 20), wherein the inverter is connected to at least one electric drive machine of the electric vehicle and is designed to supply power to the drive machine to generate a rotating magnetic field.

11. A method for deactivating an electric vehicle, in particular an inverter of the electric vehicle, wherein: At least one power semiconductor switch (6, 28) of the inverter is short-circuited by means of a metal molded part (8, 9, 30) which melts when the inverter overheats, wherein the metal molded part (8, 9, 30) is arranged and constructed to bridge two mutually spaced apart conductive layers (4, 5, 23, 24) of a circuit carrier (2, 21) of the inverter.

12. The method according to claim 11, characterized in that The power semiconductor switch (6, 28) is embedded in a molded body (14, 14', 32) together with the circuit carrier (2, 21), and the metal molded part (8, 10, 30) expands when melted and separates the molded body (14, 14', 32) from the circuit carrier, and electrically connects the conductive layers (4, 5, 23, 24) to each other in the resulting gap by flowing along the gap.

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