Sintered power electronics module

Abstract

The invention relates to a sintered power electronics module (100) having a first plane (E1) and a second plane (E2) different from the first plane (E1). In order to achieve a complete power module that can be sintered in one process and that can be sintered in a plurality of planes, the following steps are proposed:-a first substrate (10) having a first metallization (12) arranged on a first plane (E1),-a second substrate (20) having a second metallization (22) arranged on a second plane (E2),-one or more on-off wafers (40), the first substrate (10) and the second substrate (20) have a plurality of wafers (40), each having at least one first power connection (42) and at least one second power connection (44), the wafers (40) being arranged between the first substrate (10) and the second substrate (20) and being joined to the first metallization (12) by means of the first power connection (42) via a first sintered connection (31) in a first plane (E1), and the second power connection (44) being joined to the second metallization (12) via a second sintered connection (32) in a second plane (E2). The second power connection (44) is joined to the second metallization (22) by means of a second sintered connection (32) in a second plane (E2), and wherein the area (A1) of all sintered connections (31) in the first plane (E1) is 90% to 110%, in particular 95% to 105%, of the area (A2) of all sintered connections (32) in the second plane (E2). The invention also relates to a method for producing a sintered connection (31, 32) of a power module (100).

Description

[0001] The invention relates to a sintered power electronics module and a method for producing a sintered connection of a power electronics module.

[0002] Such power modules can be used, for example, in inverters in industry and electric vehicles.

[0003] Construction systems of power electronics with different joining planes can be metallurgically joined to achieve electrical / thermal and mechanical connections. Due to design and manufacturing requirements, these joining planes are mainly realized using pressure sintered connections or soldered connections made of Ag. Pressure sintered connections have good electrical and high temperature properties. The challenge is to use mechanical pressures of typically 10-20 MPa for the necessary processing and require high temperatures. For sintering in multiple planes and more complex constructions, this arrangement includes active joining areas in parallel and / or in series in terms of force / pressure.

[0004] The object of the present invention is to realize a complete power module sintered in multiple planes, which can be sintered in one process step.

[0005] This object is achieved by a sintered power module having the features of claim 1 .

[0006] A sintered power electronic module has a first plane and a second plane different from the first plane, wherein the power electronic module has a first substrate with a first metallization arranged on the first plane, a second substrate with a second metallization arranged on the second plane, and one or more switchable wafers, each of which has at least one first power connection and at least one second power connection. The wafers are arranged between the first substrate and the second substrate and are joined to the first metallization by means of the first power connection via a first sintered connection in the first plane, and are joined to the second metallization by means of the second power connection via a second sintered connection in the second plane. In order to adjust a constant pressure within a tolerable range during the sintering process, the area of ​​all sintered connections in the first plane is advantageously 90% to 110%, in particular 95% to 105%, of the area of ​​all sintered connections in the second plane. The power module defined in this way can be sintered in one process step and can therefore be manufactured more easily.

[0007] The area can be understood as the cross-sectional area of ​​the sintered connection in relation to the pressure in the plane. The cross-sectional area of ​​the sintered connection can therefore be used in a simplified manner. Since the press used during sintering is force-controlled, it is important to design the modules accordingly in terms of construction so that the pressure generated in the sintered connection or its precursor sintered material is such that a high-quality sintered connection is produced. If the force effect is constant over the entire module or stack, then the equalization of the area of ​​the sintered connection results in a uniform pressure distribution in the individual sintered connections.

[0008] The switchable wafer is a semiconductor element, which can be designed as an IGBT (insulated gate bipolar transistor) or a MOSFET (metal oxide semiconductor field effect transistor), for example. This involves an unpackaged semiconductor, also referred to as a bare wafer or bare chip. Preferably, so-called "wide bandgap" semiconductors are used here. The substrate can be designed as a metal ceramic substrate. In particular, direct copper cladding and active metal brazing substrates should be mentioned here. In addition, a plastic circuit board can also be used as one of the substrates, such as a fiber-reinforced plastic circuit board, such as an FR4 circuit board, a so-called high Tg circuit board (glass transition temperature TG above 150° C.), which is composed of polyimide and / or is designed as a prefabricated lead frame. High-temperature intermediate film materials such as PI, PEEK or LCP have been proven in high-temperature applications.

[0009] In another embodiment, the power electronics module further comprises at least one electrically conductive contact, at which the potential of the first plane is connected to the potential of the second plane. The contact is in contact with the first and second metallizations via compensating sintered connections having different areas from one another. Differences in the areas of the sintered connections in the first plane and the second plane can thereby be advantageously compensated, so that a uniform pressure is established in both planes and the sintered connections are accordingly of high quality.

[0010] In another embodiment, the contact has a first contact surface and a second contact surface, which have different areas, so that the contact can better contribute to the force guidance through its shape and better introduce the force into sintered connections of different sizes.

[0011] In another embodiment, the power electronics module has at least two switchable wafers, each of which has a sintered connection to the metallization. This design is particularly advantageous when a plurality of wafers are arranged, since it allows an optimal distribution of the pressure and the sintering of the number of wafers required for the application.

[0012] In another embodiment, the power electronic module has at least two switchable chips with control connections. These chips are arranged differently with respect to the control connections and the planes adjacent to the control connections. In other words, the chips can be arranged alternately on the upper side and the lower side. It is not necessary to alternately exchange them in close proximity here, the purpose is to arrange the chips so that the area of ​​the sintered connection in the first plane is as equal as possible to the area of ​​the sintered connection in the second plane. Since the chip top side and the chip bottom side have different contact surfaces, alternating the chip orientation is a possibility for further equalizing the area of ​​the sintered connection.

[0013] In another embodiment, the power electronics module has one or more electrically insulating compensating elements, which are arranged such that the sum of the areas of all sintered connections and compensating elements in the first plane is equal to the sum of the areas of all sintered connections and compensating elements in the second plane, taking into account a maximum deviation of 10%. The electrically insulating compensating elements can further equalize the areas, since the pressure generated by force and area acts on these compensating elements in the same way as on the sintered connections. The compensating elements can here protrude through two planes and be in mechanical contact with two metallizations of the substrate.

[0014] In another embodiment, the electronic power module has a third plane different from the first plane and the second plane. In the third plane, a third sintered connection makes contact between the second metallization of the second substrate and a connection element. The connection element can be a metallic connection element for thermal and / or electrical contact of the module with a heat sink or a power connection.

[0015] In another embodiment, the sintered connections are designed as pressure sintered connections. Pressure sintered connections can be produced particularly advantageously in a plurality of planes in one process by means of a modular design. For example, silver-based pressure sintering pastes and preforms can be considered as sintering materials.

[0016] The technical problem is also addressed by a method for producing a plurality of sintered connections of a power electronic module in the form of a stack in at least one first plane and in a second plane different from the first plane, the method comprising the following steps:

[0017] - providing a first substrate having a first metallization arranged at a first plane, a second substrate having a second metallization arranged at a second plane, and one or more switchable chips arranged between the first and second substrates, the chips each having at least one first power connection and at least one second power connection.

[0018] - In the first plane, a sintered material is provided, which contacts the first power connection with the first metallization, and in the second plane, a sintered material is provided, which contacts the second power connection with the second metallization. The area of ​​the sintered material in the first plane is equal to at least 90% and at most 110%, preferably 95% to 105%, of the area of ​​the sintered material in the second plane.

[0019] - A force is applied to the stack at a certain temperature so that a pressure is generated in the sintered material of the first and second planes, which pressure causes the first and second sintered connections to be formed from the sintered material. The sintered connections in different planes can be formed simultaneously or slightly offset one above the other.

[0020] The sintering material can be applied in the form of a preform, screen-printed or other common forms.

[0021] When a force is applied, for example by a sintering press, a pressure is generated in the respective sintered connection depending on the cross-sectional area of ​​the sintered material. Due to the similar area, the pressure in both planes is of similar magnitude by the method according to the invention, thereby ensuring the production and high quality of the sintered connection in both planes.

[0022] Embodiments of the power electronics module can be applied in the method in particular with regard to the arrangement of the sintered connection (or the arrangement of the sintered material in the state before joining) and the area of ​​the sintered material in a plane. The method is used in particular for producing a power electronics module according to one or more of the above-described embodiments.

[0023] In another embodiment, the force is set in such a way that a pressure of at least 10 MPa, in particular at least 15 MPa, is generated in the sintered material of the first and second planes. A pressure range of 10 to 20 MPa can be considered typical here. If an average range of about 15 MPa (12 to 18 MPa) is selected, larger area deviations can be tolerated and the sintered connection is satisfactorily formed without the wafer being subjected to excessive pressure. A temperature range of about 250° C. (220 to 280° C.) has proven to be advantageous.

[0024] In another embodiment, the areas of the sintered material in the first plane and the second plane are selected so that the pressures in these planes differ by a maximum of 1 MPa. Due to the relationship between area, force and pressure, the pressures in the planes can be adjusted to differ only within a permissible range of values. This can reduce the requirements on the sintering press.

[0025] In another embodiment, the force is applied to the entire stack by means of a punch. By means of an advantageous arrangement of the stack and the dimensions of the sintering material, the entire stack can be sintered in a single pressing process.

[0026] In another embodiment, before the force is applied, a plurality of compensating elements are arranged so as to reduce the bulging of at least one substrate. If one of the substrates extends over a larger area than the other substrate, temporary compensating elements can be arranged during the pressing process. These temporary compensating elements are preferably arranged so that they are in direct contact with the press on one side. This ensures a uniform force distribution on the module part that has no direct mechanical connection in the press.

[0027] In another embodiment, the force F for producing the sintered connection is continuously applied until the sintered connection of two planes is produced. In other words, the force F can be applied to the entire stack without being released, and the sintered connection is produced in all planes by means of a pressure adjustable by area.

[0028] In another embodiment, a maximum of 180 seconds is required for all sintered connections ( ) in all planes from the application of the force F to the completion of the production. Since not only intermediate steps after sintering in a single plane, such as the re-application of sintering material, can be significantly omitted, but also the actual duration of the sintering process can be saved, the process time for the production of the completed sintered connection can be significantly shortened by the method. It is conceivable that the sintering process in a plurality of planes lasts longer than the sintering process in a single plane, but the time advantage is still considerable.

[0029] The present invention will be described and explained in detail below based on the embodiments shown in the accompanying drawings. In the accompanying drawings:

[0030] Figure 1 shows an embodiment of a power electronics module,

[0031] Figure 2 The top view shows a cross-sectional view obtained by cutting the first plane,

[0032] Figure 3 The top view shows a cross-sectional view obtained by cutting the second plane.

[0033] Figure 4 shows a further embodiment of a power electronics module in a sintering press, and

[0034] Figure 5 The force profile of the power electronics module in the squeezed state is shown.

[0035] Figure 1An embodiment of a power electronic module 100 is shown, which has a first plane E1 and a second plane E2 different from the first plane. The planes E1 and E2 are arranged parallel to the first substrate 10 and the second substrate 20 of the module 100. The first substrate 10 has a first metallization 12, which is arranged at the first plane E1 and is arranged facing the second metallization 22 of the second substrate 20. The second substrate 20 is arranged at the second plane E2 with its second metallization 22. Here, two switchable wafers 40 are arranged between the metallizations 12 and 22, each of which has a first power connection 42 and a second power connection 44. The wafers 40 each have a control connection 45. The first power connection 42 is connected to the first metallization 12 via a first sintered connection 31. The first metallization 12 is structured in such a way that the electrical components can form a functional unit. For example, a bonding surface is provided on the metallization. Similarly, the second power connection 44 is connected to the second metallization 22 via a second sintered connection 32. The second metallization is structured identically. The control terminal 45 is here bonded to the second metallization 22 via a bonding connection 35. However, the control terminal can also be bonded to the first metallization 12 or differently to the first and second metallizations 12, 22. Depending on the size, the bonding connection can also be designed as a sintered connection or as a soldered connection produced with sintering.

[0036] The power module 100 can be designed as a half-bridge, full-bridge or so-called six-pack, each functional switch having one or more chips 40 (e.g., depending on whether MOSFET or IGBT is used). The other electronic component 41 has two connections and is arranged between the metallizations 12 and 22 like the chip 40.

[0037] The wafer 40 and the further electronic component 41 are each connected to the substrates 10 , 20 or their metallizations 12 , 22 via sintered connections.

[0038] Furthermore, the electrically conductive contact 50 with the compensating sintered connections 36, 38 is arranged such that the area of ​​all sintered connections in the first plane E1 is close to the area of ​​all sintered connections in the second plane E2. In the present case, the compensating sintered connection 36 arranged above the contact 50 is smaller than the compensating sintered connection 38 arranged below the contact 50. If the size of the compensating sintered connections 36, 38 exceeds the required minimum size (for example, prescribed by the current carrying capacity), the size of the compensating sintered connections 36, 38 can be freely selected. The contact 50 can be a copper molded part, which can be designed, for example, as a cuboid or truncated cone or polyhedron with at least two parallel contact surfaces. The size of the compensating sintered connections 36 and 38 does not necessarily correspond to the size of the surface against which the contact is in contact, but can be selected to be smaller.

[0039] Figure 2 The top view schematically shows a cross-sectional view of a first plane E1 of the power electronic module 100, wherein the first substrate 10 consisting of the substrate material 11 and its first metallization 12 and the bonding surface formed thereby can be seen. For simplicity, only the first metallization 12 can be seen. Figure 1 The bonding surface of one of the contacts 50 in the wafer 40 and the bonding surfaces of the two wafers 40 can be seen on the metallization 12. The first sintered connection 31, the power connection of the wafer 40 and the compensation sintered connection 36 can be seen. All sintered connections 31, 36 contribute to the area A1 of the sintered connection, because the force of the sintering press generates a pressure there, which causes the sintered connection to be produced from the sintering material used.

[0040] The central joining surface of the metallization 12 has two mutually separated sintered connections 31, which are designed corresponding to the first power connection 42 of the respective wafer 40. The sintered connection usually has separate surfaces for power connections at the same potential. This depends on the design of the wafer and the product type.

[0041] The smaller area of ​​the compensating sintered connection 36 compared to the existing joining surface of the metallization 12 means that the area A1 of the sintered connection can be adapted here.

[0042] Figure 3 and Figure 2 Similarly, a schematic top view of a cross-section through a second plane E2 of the power electronic module 100 is shown, wherein the second substrate 20 consisting of the substrate material 21 and its second metallization 12 and the bonding surface formed thereby can be seen. The second sintered connection 32, the compensation sintered connection 38 and the bonding connection 35 of the control connection (such as a gate or collector) of the wafer 40 contribute to the second area A2.

[0043] It can be seen that due to the type of construction of the wafer 40 and the bonding connection 35 of the control connection 45, the area of ​​the second sintered connection 32 is smaller than that on the other side of the wafer, i.e. Figure 2 The first sintered connection 31 in the plane E1 is shown. The central connection surface has two second connections 32 here, such a distribution of power connections is common in some wafers. The connection surface on the right of the metallization 22 .

[0044] Furthermore, it can be seen that the compensating sintered connection 38 in the second plane E2 has a greater Figure 2 The larger area of ​​the compensating sintered connection 36 is achieved in the first plane E1 in FIG.

[0045] Thus, by selecting the areas of the compensating sintered connections 36, 38, in addition or as an alternative to the arrangement of the wafer and other elements, it is possible to achieve a mutual compensation of the areas A1 and A2 of the sintered connections in the planes E1 and E2. This advantageously allows

[0046] Figure 4 Another embodiment of a power electronic module 100 between the press tools of a sintering press is shown. The power electronic module 100 is based on Figure 1 The embodiment shown is expanded with respect to the second substrate 20 .

[0047] The sintering press has a punch 200 with a support 201 which exerts a force F on the die block 100 from above.

[0048] The second substrate 20 has a plurality of layers and a second metallization 27. The second metallization 27 serves here to connect a connection element 70, which is joined to the second metallization 27 in the third plane E3 via a third sintered connection 33. In the present case, the connection element 70 is designed as a metal pin, which can provide both a thermal connection and an electrical connection. The pin can be pressed in, for example.

[0049] The lower die 210 serves as a counterpart to the punch 200 and has an adapter plate 212 supported on a support 211. In this case, the adapter plate has a recess adapted to the second base plate 20 or a connecting element 70 arranged on the second base plate.

[0050] The area of ​​the third sintered connection 33 in the third plane E3 can be different from the areas A1, A2 of the sintered connections 31, 32 in the first and second planes E1, E2. The difference in area will lead to a difference in pressure during the pressure sintering process, so in this embodiment, compensation elements 80 and 82 are provided. The compensation elements can be used to distribute the force F more evenly on the surface. In the closed state of the sintering press, the first compensation element 80 is in contact only with the punch 200 and the side of the second substrate 20 facing the punch 200. The cross-sectional areas of the compensation elements 80, 82 in different planes E1, E2, E3 can be used to balance the sum of the areas in the corresponding planes with the other planes, and thus balance the pressure used during the joining. In addition, it is advantageously possible to avoid or reduce arching when the first and second substrates 10, 20 are of different sizes.

[0051] Similar to the first compensation element 80, the second compensation element 82 is arranged below the second substrate 20 to reduce the overhang of the second substrate 20 relative to the connecting element 70. The compensation element can be used multiple times here and does not have to remain on the power electronic module 100. It is conceivable that the compensation element (not shown) is arranged and contained in such a way that the compensation element can remain on the module 100.

[0052] Figure 5 Shows Figure 4 , wherein the sintering press is closed. The punch 200 is thus pressed onto the power electronic module 100 with a force F. The force F is divided into individual force paths F1, ..., Fn, as indicated by dashed lines, which define the pressures generated in each case. The design and process technology measures disclosed in the present invention can optimize the introduction of force and thus improve pressure sintering in multiple planes. This saves a lot of time compared to sequential sintering.

[0053] In summary, the present invention relates to a sintered power electronic module 100 having a first plane E1 and a second plane E2 different from the first plane E1. In order to realize a power module that can be sintered completely and in multiple planes in one process, the following steps are recommended:

[0054] a first substrate 10 having a first metallization 12 arranged at a first plane E1 ,

[0055] a second substrate 20 having a second metallization 22 arranged at a second plane E2,

[0056] one or more switchable wafers 40 , each of which has at least one first power connection 42 and at least one second power connection 44 ,

[0057] The wafers 40 are arranged between the first substrate 10 and the second substrate 20 and are bonded to the first metallization 12 via the first sintered connection 31 in the first plane E1 by means of a first power connection 42 and to the second metallization 22 via the second sintered connection 32 in the second plane E2 by means of a second power connection 44.

[0058] The area A1 of all sintered connections 31 in the first plane E1 is 90% to 110%, in particular 95% to 105%, of the area A2 of all sintered connections 32 in the second plane E2. The present invention also relates to a method for producing sintered connections 31 , 32 of a power module 100 .

[0059] Reference numerals list

[0060] 100 Sintered power electronics modules

[0061] 10, 20 First / Second Substrate

[0062] 11 Substrate material

[0063] 12, 22 Metallization of the first / second substrate

[0064] 27. Second metallization portion of the second substrate

[0065] 31 First sintered connection

[0066] 32 Second sintered connection

[0067] 33 Third sintered connection

[0068] 35 Control joint joint

[0069] 36, 38 Compensating sintered connection

[0070] 40 Switchable chips

[0071] Power connector for 42 and 44 chips

[0072] 45 Chip control connector

[0073] 50 Contact Department

[0074] 70 Connecting elements

[0075] 80, 82 Compensation components

[0076] E1, E2 First and second planes

[0077] A1, A2 The area of ​​all joint connections in the first or second plane

[0078] F1, ..., Fn force paths

[0079] 200 Punch for sintering press

[0080] 201 Punch support

[0081] 210 Lower die of sintering press

[0082] 211 Supporting part of lower mold

[0083] 212 Adapter plate for lower die

Claims

1. A sintered power electronic module (100) having a first plane (E1) and a second plane (E2) different from the first plane (E1), the power electronic module having: - a first substrate (10) having a first metallization (12) arranged at a first plane (E1), - a second substrate (20) provided with a second metallization (22) arranged at a second plane (E2), - one or more switchable wafers (40), each of which has at least one first power connection (42) and at least one second power connection (44), in, The wafers (40) are arranged between the first substrate (10) and the second substrate (20) and are bonded to the first metallization (12) via a first sintered connection (31) in a first plane (E1) by means of the first power connection (42) and to the second metallization (22) via a second sintered connection (32) in a second plane (E2) by means of the second power connection (44), And wherein the area (A1) of all sintered connections (31) in the first plane (E1) is 90% to 110%, in particular 95% to 105%, of the area (A2) of all sintered connections (32) in the second plane (E2).

2. The power electronic module (100) according to claim 1, wherein: The power electronic module also has at least one electrically conductive contact (50), on which the potential of the first plane (E1) is connected to the potential of the second plane (E2), wherein the contact (50) is in contact with the first and second metallizations (12, 22) via compensating sintered connections (36, 38) having different areas.

3. The power electronic module (100) according to claim 2, wherein: The contact portion (50) has a first contact surface and a second contact surface, and the first contact surface and the second contact surface have different areas from each other.

4. The power electronic module (100) according to one of the preceding claims, wherein: The power electronics module has at least two switchable wafers (40), each of which has a sintered connection (31, 32) connected to a metallization (12, 22).

5. The power electronic module (100) according to one of the preceding claims, wherein: The power electronics module has at least two switchable chips (40) with control connections (45), which are arranged differently with respect to their control connections (45) and to planes (E1, E2) adjacent to the control connections.

6. The power electronic module (100) according to one of the preceding claims, wherein: The power electronic module has one or more electrically insulating compensating elements, which are arranged so that the sum of the areas of all sintered connections (21) and the compensating elements in the first plane (E1) is equal to the sum of the areas of all sintered connections (32) and the compensating elements in the second plane (E2) taking into account a maximum deviation of 10%.

7. The power electronic module (100) according to one of the preceding claims, wherein: The electronic power module has a third plane (E3) different from the first plane (E1) and the second plane (E2), wherein in the third plane (E3) a third sintered connection (33) contacts the second metallization (27) of the second substrate (20) with a connection element (70).

8. The power electronic module (100) according to one of the preceding claims, wherein: The sintered connections ( 31 , 32 ) are designed as pressure sintered connections.

9. A method for producing a plurality of sintered connections of a power electronic module (100) in stacked form in at least one first plane (E1) and a second plane (E1) different from the first plane (E1), the method comprising the following steps: - providing a first substrate (10) having a first metallization (12) arranged at a first plane (E1), a second substrate (20) having a second metallization (22) arranged at a second plane (E2), and one or more switchable chips (40) arranged between the first substrate (10) and the second substrate (20), each of which has at least one first power connection (42) and at least one second power connection (44), - providing a sintered material in the first plane (E1), which brings the first power connection (42) into contact with the first metallization (12), and providing a sintered material in the second plane (E2), which brings the second power connection (44) into contact with the second metallization (22), wherein the area of ​​the sintered material in the first plane (E1) is equal to at least 90% and at most 110% of the area of ​​the sintered material in the second plane (E2), and - applying a force (F) to the stack at a certain temperature (T) so as to generate a pressure in the sintered material of the first and second planes (E1, E2), which pressure causes the formation of first and second sintered connections (31, 32) from the sintered material.

10. The method according to claim 9, wherein: The force (F) is dimensioned such that a pressure of at least 10 MPa, in particular at least 15 MPa, is generated in the sintered material of the first and second planes (E1, E2).

11. The method according to claim 9 or 10, wherein: The areas of the sintered material in the first plane (E1) and in the second plane (E2) are selected such that the pressures in these planes (E1, E2) differ by a maximum of 1 MPa.

12. The method according to any one of claims 9 to 11, wherein: The force (F) is applied to the entire stack via the punch (200).

13. The method according to any one of claims 9 to 12, wherein: Prior to applying a force (F), a plurality of compensating elements (80, 82) are arranged to reduce the arching of at least one substrate (10, 20).

14. The method according to any one of claims 9 to 13, wherein: The force F for producing the sintered connection is continuously applied until the two-plane sintered connection has been produced.

15. The method according to any one of claims 9 to 14, wherein: From the application of the force F to the completion of the production, a maximum of 180 seconds is required for all sintered connections ( 31 , 32 ) in all planes.

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