Device for material bonding of bonding partners of power electronic components

Abstract

A device is proposed, which has a die and an elastic cushioning element for pressure-sintering a first bonding partner, in particular a component in a power electronic component, to a second bonding partner, wherein the elastic cushioning element is surrounded by a geometrically stable frame, within which the cushioning element and the mounting element of the die are guided in a linearly movable manner so that the geometrically stable frame is lowered onto the first bonding partner or onto a workpiece carrier on which the first bonding partner is arranged, and after the frame is supported on the first bonding partner or the workpiece carrier, the die is lowered together with the elastic cushioning element onto the second bonding partner, and the elastic cushioning element applies the required pressure to join the first bonding partner to the second bonding partner, and wherein the cushioning element comprises an elastic shell and a liquid or gel-like medium enclosed by the shell.

Description

Technical Field

[0001] The invention relates to a device having a compression-molded and elastic spacer element for pressure-sintering a first joining partner to a second joining partner, in particular a first joining partner to a second joining partner of a component in power electronics. Background Art

[0002] As prior art, DE 10 2015 120 156 A1 discloses a device, which is equipped with a die including an elastic cushioning element for pressure-sintering a first bonding partner of a power electronic component to a second bonding partner, wherein the elastic cushioning element of the die is surrounded by a geometrically stable frame, and the elastic cushioning element and the guide part of the die are guided in a linearly movable manner within the frame so that the geometrically stable frame is lowered onto the first bonding partner or onto a workpiece carrier on which the first bonding partner is arranged, and after the frame is supported on the first bonding partner or the workpiece carrier, the die is lowered together with the elastic cushioning element onto the second bonding partner, and the elastic cushioning element applies the required pressure to join the first bonding partner to the second bonding partner. Summary of the Invention

[0003] The object of the present invention is to provide a device of the type mentioned in the introduction in which the adaptation of the spacer element to the surface contour of the joining partner is improved.

[0004] According to the invention, this object is achieved by a device comprising a die and an elastic spacer element for pressure-sintering a first joining partner to a second joining partner, in particular for pressure-sintering components in power electronics, wherein the elastic spacer element is surrounded by a geometrically stable frame, within which the spacer element and the mounting element of the die are guided in a linearly movable manner so that the geometrically stable frame is lowered onto the first joining partner or onto a workpiece carrier on which the first joining partner is arranged, and after the frame is supported on the first joining partner or the workpiece carrier, the die is lowered together with the elastic spacer element onto the second joining partner, and the elastic spacer element applies the required pressure for joining the first joining partner to the second joining partner, and wherein the spacer element comprises an elastic capsule and a liquid or gel-like medium enclosed by the capsule. In this case, the workpiece carrier can be an integral component of the device, or the workpiece carrier can be supported on the die element, in which case the die element is an integral component of the device. In the latter case, the workpiece carrier is introduced into the device when the device is used and thus temporarily forms part of the mating element of the device.

[0005] Advantageously, the capsule of the gasket element consists of silicone rubber, and the rubber preferably has a Shore A hardness of between 25 and 100, in particular between 50 and 75. It may also be advantageous if the silicone rubber has a thickness in the range of from 0.5 mm to 5 mm, preferably between 1 and 3 mm. In this case, it is preferred that the silicone rubber is stabilized by metal additives, in particular iron, iron compounds, in particular iron oxides, and can therefore be used at temperatures above 175° C., in particular above 210° C., and at pressures between 10 and 40 MPa.

[0006] It is particularly preferred to configure the capsule as a bladder filled with the medium, i.e., in this case, the medium is completely surrounded by the capsule configured as a bladder. The bladder is then preferably materially connected to the die, or more precisely, to the surface portion of the die facing the workpiece carrier, by adhesive bonding. Alternatively, the capsule can be connected to the die in a form-fitting, force-fitting, or materially connected circumferentially, and the medium can be arranged in the resulting volume. For this purpose, the die preferably includes a sealable and pressure-tight filling opening for the medium.

[0007] Preferably, the boiling point of the medium is above 200°C, preferably above 250°C.

[0008] Advantageous media are selected from the group consisting of:

[0009] Silicone fluid; or

[0010] Silicone grease; or

[0011] Oil; or

[0012] metals that are liquid under normal conditions, in particular alloys of gallium, indium and tin; or

[0013] Molten salts, especially sodium thiosulfate; or

[0014] Phase change material. In this case, it is advantageous if the phase change material has a phase change temperature from solid to liquid in the range of 50°C to 250°C, in particular in the range of 80°C to 200°C.

[0015] In this case, it is crucial that the melting point, measured at a standard pressure of 1013 hPa, is above 50° C., preferably above 20° C.

[0016] The viscosity range of the medium can in principle be very wide and can preferably be between 1 mPa·s and 10 6 mPa·s. The most preferred value is 10 2 mPa·s and 10 5 mPa·s.

[0017] Advantageously, during the pressing process, a non-adhesive plastic film, in particular a PTFE film, having a thickness of between 25 μm and 200 μm, in particular between 50 μm and 100 μm, is arranged between the spacer element and the joining partner.

[0018] In the use of the aforementioned device according to the invention for material bonding, in particular pressure sintering bonding, at least one of the following bonds is formed:

[0019] Substrate to heat sink bonding;

[0020] Bonding of power semiconductor components to substrates;

[0021] Bonding of connection elements to substrates or power semiconductor components;

[0022] Bonding of the thin film composite material to a power semiconductor component and / or a substrate, the thin film composite material preferably being configured as an internal bonding device of a power electronic switching device.

[0023] Of course, unless otherwise expressly excluded, features mentioned in the singular, in particular two coupling partners, may also be present in the plural in the device according to the invention or the use of the device according to the invention.

[0024] It should be understood that the various configurations of the present invention can be implemented individually or in any desired combination to achieve improvements. In particular, without departing from the scope of the present invention, whether they are described in the context of the device or in the context of its use, the features mentioned and explained above and below can be used equally not only in the specified combination, but also in other combinations, or individually. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further explanations, advantageous details and features of the invention can be found in the following description of exemplary embodiments of the invention. Figure 1 and Figure 2 These exemplary embodiments or corresponding parts thereof are schematically shown in FIG.

[0026] Figure 1 A first configuration of an arrangement 1 according to the invention is shown having a first power electronic switching arrangement.

[0027] Figure 2 A second configuration of the device 1 according to the invention is shown, having a second power electronic switching device. DETAILED DESCRIPTION

[0028] Figure 1A first configuration of an apparatus 1 according to the present invention is shown, comprising a first power electronic switching device. A workpiece carrier 7, or more generally, a matching molded element, is shown, in the recess of which the power electronic switching device, in this case a substrate 500 of a power semiconductor module, is placed. On its second side, facing away from the workpiece carrier, the substrate 500 comprises a structured metal layer, which is materially bonded to an insulating material body 502. The metal layer forms conductive tracks 504 of the power electronic switching device. Power semiconductor components 600 are arranged on these conductive tracks 504.

[0029] The substrate 500, or more precisely its conductive tracks 504, forms a first bonding partner 5, which is intended to be bonded to a second bonding partner 6, here a power semiconductor component 600, by means of pressure sintering. For this purpose, the bonding partners 5, 6 comprise bonding surfaces with sinterable surfaces. In addition, a sintered metal layer (not shown) in the green state is arranged between the bonding partners 5, 6, or between their bonding surfaces.

[0030] The actual application of pressure 200 for pressure sintering takes place via the die 2, which is shown here in a simplified manner as a geometrically stable metal body 20, and via the backing element 3. In this case, the backing element 3, or more precisely its envelope 30, is two-dimensionally connected to the face of the die 2 facing the substrate 500 by means of an adhesive material.

[0031] In this case, the cushioning element 3 is configured as a bladder filled with a medium 34. The bladder 30 itself has a thickness of 2 mm and is composed of silicone rubber with a hardness of approximately 55 Shore A, stabilized by the addition of iron and iron oxides. In this case, the medium 34 is a silicone grease 340 having a viscosity of approximately 5000 mPa·s measured under standard conditions.

[0032] Furthermore, a geometrically stable frame 4 is shown, which serves to laterally delimit a space in which a quasi-hydrostatic pressure is exerted on all adjacent surfaces via the spacer elements 3. In this configuration, the frame 4 can be lowered onto the first bonding partner 5, here a substrate 500, before the actual pressure for the sintering bond is applied. In this case, the pressure 400 generated on the substrate 500 is several orders of magnitude lower than the pressure 200 for forming the sintering bond, as indicated by the arrows of different sizes representing the pressure.

[0033] Furthermore, a plastic film 8 is shown, which is not adhered to the substrate 500 together with the power semiconductor components 600 arranged thereon. Here, the plastic film is a PTFE film having a thickness of approximately 60 μm, which is arranged on the surface of the substrate 500 together with the power semiconductor components 600 during the sintering process. Once the frame 4 is supported on the substrate 500, the die 2 and the backing element 3 can be lowered together, and the pressure required to form the pressure sintering bond (in this case, approximately 25 MPa) can be applied to the second bonding partner. The workpiece carrier 7, and therefore the substrate 500 and the power semiconductor components 600, can be temporarily heated to approximately 210°C, which promotes the rapid formation of the pressure sintering bond.

[0034] Figure 2 A second configuration of the device 1 according to the invention is shown, which features a second power electronics switching device. This device 1 differs from the first configuration described above in that, in this case, the geometrically stable frame 4 is not lowered onto one or both mating partners and pressed against them. Instead, the frame 4 is lowered onto the workpiece carrier 7 laterally adjacent to the mating partners 5, 6. In this configuration, the frame 4 presses against the workpiece carrier 7 circumferentially around the mating partners with the same force as described above.

[0035] On the other hand, in this case, the die 2 and the backing element 3 are also different. In the second configuration, the capsule 32 is connected to the die 2 in the circumferential edge region by a force fit. For this purpose, a portion of the capsule 32 is held in a circumferential groove 22 near the frame. The volume area thus created between the die and the capsule is filled with oil 342 (as medium 34) through a filling opening.

[0036] In this illustration, the first bonding partner 5 is a power electronic substrate 500 having a power semiconductor component 524 arranged thereon. In this case, the second bonding partner 6 is a power electronic bonding device 620 configured as a film stack of an electrically conductive film and an electrically insulating film. The remaining configuration of the pressure sintering bond is similar to that according to Figure 1 Proceed in a similar manner.

Claims

1. Device (1) having a pressure die (2) and an elastic spacer element (3) for pressure-sintered material bonding of a first joining partner (5) to a second joining partner (6), characterized in that The elastic cushioning element (3) is surrounded by a geometrically stable frame (4), in which the cushioning element (3) and the mounting element (20) of the die (2) are guided in a linearly movable manner so that the geometrically stable frame (4) is lowered onto the first joining partner (5) or onto the workpiece carrier (7) on which the first joining partner (5) is arranged, and after the frame is supported on the first joining partner (5) or the workpiece carrier (7), the die (2) is lowered together with the elastic cushioning element (3) onto the second joining partner (6), and the elastic cushioning element (3) applies the required pressure for joining the first joining partner (5) to the second joining partner (6), and wherein the elastic cushioning element (3) comprises an elastic capsule (32) and a liquid or gel-like medium (34) enclosed by the capsule (32), The capsule (32) is connected to the die (2) in a circumferential region by form fit, force fit or material fit, and the medium (34) is arranged in the volume region thus formed, the die (2) comprises a sealable and pressure-tight filling opening for the medium, and the volume region generated between the die (2) and the capsule (32) is filled with the medium (34) via the filling opening.

2. The device according to claim 1, characterized in that The first bonding partner (5) to the second bonding partner (6) are bonding partners of components in the power electronics.

3. The device according to claim 1, characterized in that The capsule (32) of the gasket element (3) consists of silicone rubber.

4. The device according to claim 3, wherein The capsule (32) of the spacer element (3) has a Shore A hardness between 25 and 100 and a thickness in the range from 0.5 mm to 5 mm.

5. The device according to claim 4, characterized in that The capsule (32) of the spacer element (3) has a Shore A hardness between 50 and 75.

6. The device according to claim 3, characterized in that The silicone rubber is stabilized by metal additives and can therefore be used at temperatures above 175° C. and pressures between 10 and 40 MPa.

7. The device according to claim 6, characterized in that The silicone rubber can be used at a temperature higher than 210°C.

8. The device according to claim 6, characterized in that The silicone rubber is stabilized by iron or iron compounds.

9. The device according to claim 8, characterized in that The silicone rubber is stabilized by iron oxides.

10. The device according to any one of claims 1 to 9, characterized in that The boiling point of the medium (34) is higher than 200°C.

11. The device according to claim 10, characterized in that The boiling point of the medium (34) is higher than 250°C.

12. The device according to any one of claims 1 to 9, characterized in that The medium (34) is selected from the group consisting of: Silicone fluid; or Silicone grease (340); or Oil (342); or metals, which are liquid under normal conditions; or Molten salt; or Phase change materials.

13. The device according to claim 12, characterized in that The metal is an alloy of gallium, indium and tin.

14. The device according to claim 12, characterized in that The molten salt is sodium thiosulfate.

15. The device according to claim 12, characterized in that The phase change temperature of the phase change material from solid to liquid is in the range of 50°C to 250°C.

16. The device according to claim 15, characterized in that The phase change temperature of the phase change material from solid to liquid is in the range of 80°C to 200°C.

17. The device according to any one of claims 1 to 9, characterized in that During the pressing process, a non-adhesive plastic film (8) having a thickness of between 25 μm and 200 μm is arranged between the cushioning element (3) and the joining partner (5, 6).

18. The device according to claim 17, characterized in that The thickness of the plastic film (8) is between 50 μm and 100 μm.

19. The device according to claim 17, characterized in that The plastic film (8) is a PTFE film.

20. Use of the device according to any one of claims 1 to 19, characterized in that For material bonding of a substrate to a heat sink, and / or for material bonding of a power semiconductor component (600) to a substrate (500), and / or for material bonding of a connecting element to a substrate or a power semiconductor component, and / or for material bonding of a thin film composite material (620) to a power semiconductor component (524) and / or a substrate (500).

21. The use according to claim 20, characterized in that For pressure sintering bonding of a substrate to a heat sink, and / or for pressure sintering bonding of a power semiconductor component (600) to a substrate (500), and / or for pressure sintering bonding of a connecting element to a substrate or a power semiconductor component, and / or for pressure sintering bonding of a thin film composite material (620) to a power semiconductor component (524) and / or a substrate (500).

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