Power module and method of manufacturing a power module

Abstract

The invention discloses a power module and a method of manufacturing a power module. The power module comprises a chip and a substrate, the substrate comprises a first surface and a second surface which are opposite, the first surface is provided with a conducting layer, the chip is arranged on the first surface, the substrate further comprises an insulating layer made of a first material, the insulating layer is arranged on the first surface and deviates from the chip, and the insulating layer is made of a second material. A closed space is formed in the insulating layer, a heat transfer structure is arranged in the space, and the heat transfer structure is constructed to be a vacuum channel filled with a phase change material. The heat dissipation capability of the power module is improved.

Description

Technical Field

[0001] The present invention relates to the field of electronic device manufacturing, and specifically relates to a power module and a method for manufacturing a power module. Background Art

[0002] Power modules provide the physical packaging for power semiconductor devices. Power semiconductors are typically soldered or sintered onto a substrate, which supports the power semiconductors, provides electrical and thermal contact, and, where necessary, electrical insulation. Compared to the materials and technologies used for low-power microelectronics, substrates must carry higher currents, provide higher voltage isolation, and operate over a wide temperature range. Summary of the Invention

[0003] One aspect of the present application is to provide a power module, which provides good substrate heat dissipation capability.

[0004] The power module includes a chip and a substrate. The substrate includes a first surface and a second surface opposite to each other. The first surface has a conductive layer, and the chip is arranged on the first surface. The substrate also includes an insulating layer made of a first material, and the insulating layer is arranged on the first surface and faces away from the chip. The insulating layer has an enclosed space inside, and a heat transfer structure is arranged in the space. The heat transfer structure is configured as a vacuum channel filled with a phase change material.

[0005] In one embodiment of the power module, the heat transfer structure is made of the first material.

[0006] In an embodiment of the power module, the channel is configured so that the phase change material flows in the channel in a direction parallel to the insulating layer.

[0007] In one embodiment of the power module, the channel is configured to be defined by a wall of the space, and the space is configured to include a tortuous portion and a connecting portion, wherein the connecting portion connects the tortuous portions so that the phase change material passing through the tortuous portions circulates back to the tortuous portions via the connecting portion.

[0008] In an embodiment of the power module, the zigzag portion has a head end and a tail end, a plurality of parallel pipes are located between the head end and the tail end, adjacent pipes are connected, and the connecting portion connects the head end and the tail end.

[0009] In an embodiment of the power module, the channel is configured so that the phase change material flows in the channel in a direction parallel to the insulating layer.

[0010] In one embodiment of the power module, the channel structure is defined by the wall of the space, the space structure includes a tortuous portion and a connecting portion, the tortuous portion has a head end and a tail end, a plurality of parallel pipes are between the head end and the tail end, and the connecting portion connects the head end and the tail end.

[0011] In an embodiment of the power module, the power module further includes a heat sink, the heat sink is disposed on the second surface, and the second surface has a solder layer.

[0012] In an embodiment of the power module, a plurality of fins are provided inside the heat sink and allow a cooling medium to pass through.

[0013] Another aspect of the present application is to provide a method for manufacturing the power module described in any one of the above embodiments, the method comprising providing a first half having a portion of the heat transfer structure and a second half having a remaining portion of the heat transfer structure; and combining the first half and the second half so that the portion of the heat transfer structure and the remaining portion are docked.

[0014] In one embodiment of the method, the first half is formed with the first material to have a first groove; the second half is formed with the first material to have a second groove; and the first half and the second half are hot pressed so that the first groove and the second groove are combined into the heat transfer structure.

[0015] This application improves the heat dissipation capacity of the power module. The heat transfer structure is arranged inside the insulating layer of the substrate. Through the flow of phase change material in the heat transfer structure, the energy from the heat source is quickly diffused from the concentrated point to the plane where the insulating layer is located.

[0016] The heat transfer structure is integrated into the insulation layer. The heat transfer structure uses the same material as the insulation layer, so it can be stably combined with the insulation layer without causing deformation differences due to thermal expansion and contraction, avoiding the hidden danger of separation from the insulation layer.

[0017] The heat transfer structure is constructed as a closed structure in the base plate without an inlet or outlet, so the base plate does not need to be connected to any additional pipelines.

[0018] The present application provides a method for embedding a heat transfer structure within a substrate by forming two halves of the substrate separately and then combining the two to form an insulating layer and the heat transfer structure therein.

[0019] The heat transfer structure can be formed directly in the process of molding the substrate halves.

[0020] Other aspects and features of the present application will become apparent from the following detailed description, which proceeds with reference to the accompanying drawings. It should be understood, however, that the drawings are designed for illustrative purposes only and are not intended to limit the scope of the present application, as reference should be made to the appended claims. It should also be understood that the drawings are intended only to conceptually illustrate the structures and processes described herein and, unless otherwise indicated, are not necessarily drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present application will be more fully understood by referring to the following detailed description of specific embodiments in conjunction with the accompanying drawings, in which the same reference numerals throughout the drawings refer to the same elements.

[0022] Figure 1 This is a schematic diagram of an embodiment of a power module involved in this application applied to an on-vehicle power electronic device;

[0023] Figure 2 A cross-sectional view of an embodiment of an insulating layer of a power module involved in the present application; and

[0024] Figure 3 This is an exploded view of another embodiment of the insulation layer of the power module involved in this application. DETAILED DESCRIPTION

[0025] In order to help those skilled in the art to accurately understand the subject matter for which protection is sought in this application, the specific implementation methods of this application are described in detail below with reference to the accompanying drawings.

[0026] Figure 1 This is a schematic diagram illustrating an embodiment of a power module according to this application being applied to an on-vehicle power electronic device. The on-vehicle power electronic device 10 may be a power supply device on a vehicle, including but not limited to an inverter, an on-board charger, a DC-DC converter, etc. The on-vehicle power electronic device 10 includes a housing 12. The power module is disposed within the housing 12. The power module includes a chip 14 and a substrate 16. Figure 1The internal structure of an on-board power electronic device is shown in a simplified manner. A chip 14 is supported on a substrate 16, although the substrate can support multiple chips. The chip 14 and substrate 16 are filled with encapsulation material 18 to form a package. The substrate 16 has a multilayer structure. It has a first surface 20 and a second surface 22 that are opposite each other. The first surface 20 is located at the top, and the second surface 22 is located at the bottom. The terms indicating directions are used only to facilitate the description of the drawings and are relative and therefore interchangeable. The first surface 20 has a conductive layer 24, and the second surface 22 has a solder layer 26. The conductive layer 24 and the solder layer 26 are each made of a metal such as copper. The chip 14 is located on the first surface, above the conductive layer 24. Between the first surface 20 and the second surface 22 is an insulating layer 27. The insulating layer 27 forms the main body of the substrate 16 and faces away from the chip 14 at the first surface 20. The insulating layer 27 is made of a first material, such as ceramic. Substrates made of ceramic materials have excellent electrical insulation properties and high thermal conductivity. The interior of the insulating layer 27 has a closed space 28, and a heat transfer structure 30 is provided in the space 28. The heat transfer structure 30 is configured as a vacuum channel filled with a phase change material. The ceramic substrate can be a direct bonded copper (DBC) ceramic substrate or an active metal brazing (AMB) ceramic substrate.

[0027] Figure 2 A cross-sectional view of an embodiment of an insulating layer is shown. As shown, heat transfer structure 30 is made of the same material as insulating layer 27, i.e., a first material. The thermal conductivity of ceramic materials makes the heat transfer structure suitable for ceramics. Since the heat transfer structure and the insulating layer are made of the same material, the two can be integrated. Figure 2 3. The channel is divided into several sub-channels 36, and the phase change material flows in the sub-channels 36. The phase change material flows in the channel in a direction substantially parallel to the insulating layer, as shown in the figure, which is parallel to the insulating layer 27.

[0028] Figure 3 The interior of the insulation layer is shown from another angle. As shown in the figure, the heat transfer structure is constructed as a channel 40 with a loop. The channel 40 is directly defined by the wall of the space. The channel 40 includes a tortuous portion 42, 42' and a connecting portion 44, 44', and the connecting portion 44, 44' connects the tortuous portion 42, 42' so that the phase change material flowing in the tortuous portion 42, 42' can return to the tortuous portion 42, 42' via the connecting portion 44, 44', thereby forming a circulation loop. The tortuous portion 42, 42' has a head end 46, 46' and a tail end 48, 48', and there are multiple parallel pipes between the head end 46, 46' and the tail end 48, 48', and these adjacent pipes are connected. The connecting portion 44, 44' connects the head end 46, 46' and the tail end 48, 48'. Here, the terms "head end" and "tail end" are relative concepts and they are interchangeable.

[0029] Channel 40 is evacuated and then filled with phase change material. Since the diameter of channel 40 is very small, the phase change material forms an alternating distribution of gas plugs and liquid plugs in the channel. Due to the presence of a heat source, the phase change material generates bubbles. As the temperature rises, the pressure inside the bubbles increases, driving the bubbles to move toward a colder temperature. During the movement, the gas plugs merge and the liquid plugs split, and heat is released to the environment in the colder place. The bubble phase changes heat transfer from gas to liquid. Due to the high density of the liquid, the cooled liquid tends to move to a hotter place. In this way, a pressure difference is formed in the channel, driving the phase change material to move back and forth in the channel, thereby realizing heat transfer. The heat generated by the chip operation is transferred to the insulating layer and transferred inside the insulating layer in the heat transfer structure, thereby quickly dissipating the heat and preventing the chip from overheating.

[0030] Back to Figure 1 The substrate 16 is connected to the heat sink 32 at the second surface 22. The solder layer 26 is located at the second surface 22, and the substrate 16 is connected to the heat sink 32 via the solder. The heat sink 32 has a plurality of fins 34 inside and has spaces that allow the passage of a cooling medium. The heat is transferred to the insulating layer 27 and diffused, and then ultimately carried away by the cooling medium via the heat sink 32.

[0031] The present application embeds a heat transfer structure 30 in the insulating layer 27 to diffuse the chip heat from a point heat source to a surface heat source in the insulating layer 27, and then transfers it to the heat sink 32. The heat transfer structure 30 establishes a fast heat dissipation path.

[0032] The manufacturing process of the substrate refers to Figure 3 First, the first half 50 and the second half 52 are formed separately. The first half 50 has a portion of the heat transfer structure, while the second half 52 has the remaining portion of the heat transfer structure. The first half 50 and the second half 52 are then joined, with the portion of the heat transfer structure and the remaining portion butted together, thereby forming a heat transfer structure internally. The portion of the heat transfer structure and the remaining portion can be formed directly on the first half 50 and the second half 52. As shown in the figure, the first half 50 has a first groove 54, while the second half 52 has a second groove 56. The first half 50 and the second half 52 are formed using a first material. A material removal process such as etching is used to form the first groove 54 on the first half 50. The first groove 54 is configured as one half 57 of the channel 40. A second groove 56 is formed on the second half 52. The second groove 56 is configured as the other half 58 of the channel 40. The first half 50 and the second half 52 are then heat-pressed together. When heated, the molecules of the first material at the joining surface of the two halves diffuse, thereby bonding the two halves into one. Next, the combined insulating layer is clad with a copper layer through a DBC or AMB process to form a substrate.

[0033] While specific embodiments of the present application have been shown and described in detail to illustrate the principles of the present application, it will be appreciated that the present application may be embodied in other ways without departing from such principles.

Claims

1. A power module, characterized in that include: chip (14), and A substrate (16) includes a first surface (20) and a second surface (22) facing each other, the first surface (20) having a conductive layer (24), the chip (14) being arranged at the first surface (20), the substrate (16) further including an insulating layer (27) made of a first material, the insulating layer (27) being arranged at the first surface (20) and facing away from the chip (14), the insulating layer (27) having an enclosed space (28) inside, a heat transfer structure (30) being arranged in the space (28), the heat transfer structure (30) being constructed as a vacuum channel (40) filled with a phase change material.

2. The power module according to claim 1, wherein: The heat transfer structure (30) is made of the first material.

3. The power module according to claim 1, wherein: The channel (40) is configured such that the phase change material flows in the channel (40) in a direction parallel to the insulating layer (27).

4. The power module according to claim 3, wherein: The channel (40) is configured to be defined by the wall of the space (28), and the space (28) is configured to include a tortuous portion (42, 42') and a connecting portion (44, 44'), wherein the connecting portion (44, 44') connects the tortuous portions (42, 42') so that the phase change material passing through the tortuous portions (42, 42') circulates back to the tortuous portions (42, 42') via the connecting portion (44, 44').

5. The power module according to claim 4, wherein: The zigzag portion (42, 42') has a head end (46, 46') and a tail end (48, 48'), a plurality of parallel pipes are arranged between the head end (46, 46') and the tail end (48, 48'), adjacent pipes are connected, and the connecting portion (44, 44') connects the head end (46, 46') and the tail end (48, 48').

6. The power module according to claim 1, wherein: The power module further comprises a heat sink (32), the heat sink (32) being arranged at the second surface (20), and the second surface (20) having a solder layer (26).

7. The power module according to claim 6, wherein: The radiator (32) is provided with a plurality of fins (34) inside and allows a cooling medium to pass through.

8. The power module according to any one of claims 1 to 7, wherein: The substrate (16) is a directly bonded copper ceramic substrate or an active metal brazing ceramic substrate.

9. A method for manufacturing a power module according to any one of claims 1 to 8, characterized in that include: providing a first half (50) having a portion of the heat transfer structure and a second half (52) having a remaining portion of the heat transfer structure; as well as Joining the first half (50) and the second half (52) abuts the portion of the heat transfer structure with the remaining portion.

10. The method according to claim 9, wherein: Using the first material to form the first half (50) having a first groove (54); forming the second half (52) having a second groove (56) using the first material; and The first half (50) and the second half (52) are heat-pressed so that the first groove (54) and the second groove (56) are combined into the heat transfer structure.

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