Embedded double-sided direct cooling power module structure based on metal core composite substrate

Abstract

The present invention relates to semiconductor module packaging technology, and aims to provide an embedded double-sided direct cooling power module structure based on a metal core composite substrate. It comprises two stacked sheet-like metal core composite substrates, the composite substrate having multiple metal sheet layers arranged in parallel and connected into a whole through a gap insulator; multiple boss structures are provided at intervals on the inner surface of the metal sheet layer, a double-layer insulation structure for filling is provided in the non-boss area, and a drive circuit layer is embedded; the two composite substrates are arranged relative to each other so that the boss structures are grouped correspondingly and embedded to install power chips; an insulating filling layer is provided in the cavity between the plates, and an external insulating layer is provided on the outer surface to cover all the metal sheet layers at the same time, and a heat sink is provided on the outside of the external insulating layer. The metal sheet layer in the present invention can directly conduct the heat generated by the chip to the bottom of the heat sink, which can significantly shorten the heat dissipation path, reduce the thickness of the module package, and greatly improve the chip flow capacity, packaging reliability and product mechanical properties.

Description

Technical Field

[0001] The present invention relates to a semiconductor module packaging technology, and more particularly to an embedded double-sided direct cooling power module structure based on a metal core composite substrate. Background Art

[0002] Traditional silicon-based power module packaging primarily utilizes DBC substrates and bonding wires to achieve electrical connections between the chip, interconnect layer, and module terminals. However, as wide-bandgap semiconductor devices gradually replace silicon devices in an increasing number of applications, the parasitic inductance introduced by the bonding wires has severely limited their high-frequency applications. Furthermore, existing double-sided copper-clad ceramic substrates only allow for single-layer wiring, severely restricting circuit spatial layout. Other literature has proposed power device packaging solutions based on PCB substrate embedment technology, but the PCB substrate utilizes a large amount of organic composite insulating material, making it difficult to efficiently dissipate heat from the power chip. Furthermore, traditional single-sided heat dissipation methods can cause module temperatures to overheat, severely impacting the performance of wide-bandgap semiconductor devices.

[0003] Therefore, in response to the series of technical challenges faced by large-capacity power modules, it is urgent to develop module packaging methods suitable for wide-bandgap semiconductor power devices. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the high parasitic parameters and heat dissipation deficiencies in the existing large-capacity and high-power module packaging technology, and provide an embedded double-sided direct cooling power module structure based on a metal core composite substrate.

[0005] To solve the technical problem, the solution of the present invention is:

[0006] Provided is an embedded double-sided direct cooling power module structure based on a metal core composite substrate, comprising two stacked sheet-shaped metal core composite substrates and a plurality of power chips arranged in the same layer between the composite substrates; wherein,

[0007] The composite substrate comprises a plurality of metal sheets arranged in parallel, with gaps between adjacent surfaces being filled with gap insulators for bonding; the metal sheets are connected as a whole by the gap insulators, serving as a rigid support structure for the composite substrate;

[0008] Multiple boss structures are spaced apart on the inner surface of each metal sheet; a double-layer insulation structure is provided in the non-boss area for leveling, with the lower layer being an internal insulation layer and the upper layer being an insulating ink layer; the two composite substrates are arranged relative to each other so that the boss structures are grouped in a one-to-one correspondence; a power chip is embedded and installed between each group of boss structures, with its two side surfaces fixedly connected to the surfaces of the boss structures; a drive circuit layer is provided on the metal sheet opposite the power-connected side of the power chip, embedded in the double-layer insulation structure; the drive circuit layer has multiple extensions for connecting to the power chip, and the insulating ink layer has windows in the power-connected area of ​​the power chip, enabling electrical connection between the drive circuit layer and the power chip; after each group of boss structures is connected to the power chip, a cavity is formed between the two composite substrates, and an insulating filling layer is provided in the cavity for bonding;

[0009] The outer surface of the composite substrate has an external insulating layer covering each metal sheet layer, and a heat sink is arranged outside the external insulating layer; the heat generated by each power chip is conducted to the heat sink through the boss structure and the metal sheet layer body.

[0010] As a preferred embodiment of the present invention, the driving circuit layer has a multi-layer structure, including a multi-level stacked driving circuit and an insulating layer for electrical isolation; the driving circuit located in the lower layer and the driving circuit located in the upper layer or the power connection area of ​​the power chip are electrically connected through blind holes or metal connecting blocks.

[0011] As a preferred solution of the present invention, the driving circuit layer is located on the same composite substrate or on two composite substrates respectively, depending on the direction of the power chip's power-connected side.

[0012] As a preferred solution of the present invention, the power chip and the boss structures on both sides thereof are fixedly connected via a sintered solder layer; the power connection area of ​​the power chip and the driving circuit layer are electrically connected via a sintered solder layer.

[0013] As a preferred embodiment of the present invention, a metal connection layer is provided on the surface of the external insulating layer, and the bottom surface of the radiator is connected to the metal connection layer through a sintered solder layer; or a silicone grease thermal conductive layer is provided between the metal connection layer and the bottom surface of the radiator, and the radiator is fixed to the composite substrate using a clamp.

[0014] As a preferred embodiment of the present invention, the external insulating layer and the bottom surface of the radiator are connected by hot pressing; alternatively, a silicone grease thermal conductive layer is provided between the external insulating layer and the bottom surface of the radiator, and the radiator is fixed to the composite substrate by a clamp.

[0015] As a preferred solution of the present invention, an extension portion is provided at one end of at least one metal sheet layer in the composite substrate as a power terminal for installation and connection, and a mounting hole is provided on the power terminal.

[0016] As a preferred solution of the present invention, at the end of the metal sheet layer where the driving circuit layer is located, an extension portion of the driving circuit layer and the bottom metal is provided as a signal terminal.

[0017] The present invention further provides a method for preparing the aforementioned embedded double-sided direct cooling power module structure based on the metal core composite substrate, comprising:

[0018] Using electroplating, etching or deposition process, a boss structure is formed on the inner surface of the metal sheet layer, so that the two become an integrated structure;

[0019] Arrange multiple metal sheets side by side in a mold while maintaining gaps between adjacent surfaces. Fill the gaps with an insulator using hot pressing, sintering, spraying, or deposition processes to achieve electrical insulation between the metal sheets and form a rigid overall structure.

[0020] Using hot pressing, sintering, spraying or deposition process, an external insulating layer is formed on the outer surface of the metal sheet layer to form electrical insulation of the metal sheet layer to the outside; or further using chemical plating, electroplating, deposition or hot pressing process, a metal connecting layer is formed on the surface of the external insulating layer;

[0021] Using a hot pressing process, the non-convex area of ​​the metal sheet is covered with an internal insulating layer; using a photolithography, chemical plating, deposition or evaporation process, a metal circuit is formed on the surface of the internal insulating layer to form a driving circuit layer;

[0022] The surface of the internal insulation layer and the driving circuit layer is covered with an insulating ink layer by spraying or brushing; the surface of the metal sheet layer is formed into a sandwich structure at the location where the driving circuit layer is present, and a double-layer structure at the location where the driving circuit layer is absent;

[0023] Using laser, etching or cutting technology, the insulating ink layer is opened to form an insulating layer groove according to the installation position of the power chip, exposing the surface of the boss structure and the welding position of the power chip contact area on the driving circuit layer for chip positioning and solder printing;

[0024] A printing process is used to arrange solder in the groove of the insulating layer and place the power chip; after the two composite substrates are placed opposite each other and pressed together, a welding or sintering process is used to firmly bond the solder;

[0025] Insulating material is placed in the cavity between the composite substrates using an injection molding or potting process to form an insulating filling layer that firmly bonds the two composite substrates;

[0026] The heat sink is mounted on the external insulating layer by a hot pressing process, or is mounted on the metal connection layer by a welding process; alternatively, a silicone grease thermal conductive layer is coated on the outside of the composite substrate, and the heat sink is fixed to the composite substrate by a clamp.

[0027] As a preferred embodiment of the present invention, the material of the metal sheet layer is copper or aluminum; the material of the gap insulator is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; the material of the external insulating layer is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; the internal insulating layer is a glass fiber composite material; the material of the driving circuit layer is copper or aluminum; the material of the insulating filling layer is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; the material of the metal connection layer is copper or aluminum; or, an anti-oxidation layer of nano-scale metal nickel or gold is further provided on the surface of the metal connection layer.

[0028] Description of the invention principle:

[0029] In the prior art, the design of power modules that use two substrates to clamp the power chip or embed the power chip into the PCB substrate can respectively achieve the functions of double-sided heat dissipation and packaging to reduce parasitic parameters. However, the power modules capable of double-sided heat dissipation recorded in public literature usually use traditional DBC substrates, AMB substrates or other double-sided copper-clad ceramic substrates. Due to the large difference in thermal expansion coefficients between ceramic substrates and metals, it is difficult to achieve a multi-layer structure for power modules using metal-ceramic substrates, and substrate warping and delamination and cracking defects are prone to occur under high temperature conditions. In addition, existing PCB substrate embedding solutions usually use organic resin substrates as packaging insulation materials (such as organic substrates such as FR4). These substrate materials have low thermal conductivity, which will seriously limit the heat dissipation of power devices. Therefore, the drive control board in the current power module usually still adopts a discrete structure.

[0030] The present invention innovatively proposes utilizing multiple parallel metal sheets as the rigid metal core structure of a composite substrate. A boss structure is constructed on the metal sheets, and then two composite substrates are stacked relative to each other, with the power chip embedded between the two metal sheets. This method utilizes the flat metal sheets as a thermal medium, transferring heat generated by the power chip during operation to a heat sink. Furthermore, the present invention abandons the prior art practice of nesting substrates for arranging drive circuits, and instead arranges the drive circuit layer directly within a double-layer insulation structure arranged in the non-boost areas of the metal sheets. This design not only simplifies the product structure and processing, but also allows for the layout of more complex drive control circuits through a multi-layer design, meeting increasingly demanding product functionality. Compared to traditional processes that place metal blocks on the outside of the power chip for electrical connections, the present invention embeds the drive circuit layer within a double-layer insulation structure in the non-boost areas, enabling more flexible circuit pattern design without being restricted by chip layout. At the same time, the metal sheet layer serves as a conductive structure, supporting structure and heat dissipation medium, and its functions and structures are fully utilized, which can further enhance the overall structural strength and heat dissipation efficiency, and further improve the current carrying capacity of the module.

[0031] Furthermore, the present invention proposes using a highly thermally conductive ceramic composite insulation material containing aluminum nitride, silicon nitride, or silicon carbide to fill each insulating layer. In power module products, each insulating component has a thermal expansion coefficient close to that of metal. This ensures a stable overall structure and enhanced product strength while maintaining high thermal conductivity and insulation performance.

[0032] Therefore, the implementation scheme of the present invention breaks through the inherent design thinking of technical personnel in this field. By directly embedding the power module and the drive circuit between two layers of metal core composite substrates, the integrated integration of the substrate and the radiator, the complex control requirements of different chips inside the module, and the double-sided direct sintering scheme of the power chip are realized, thereby achieving the high-efficiency heat dissipation, low noise and integrated integration of the drive circuit of the high-power module.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention adopts direct sintering or welding to realize the connection between the power chip and the boss structure on both sides and the driving circuit layer. The metal sheet layer can directly conduct the heat generated by the chip to the bottom of the radiator, giving full play to the heat dissipation capacity of the large-area metal sheet layer. Compared with the traditional packaging structure, it can significantly shorten the heat dissipation path and reduce the module packaging thickness, while greatly improving the chip flow capacity, packaging reliability and product mechanical performance.

[0035] 2. The present invention completely eliminates the traditional structure of embedding an organic insulating substrate, and instead embeds the drive circuit within the double-layer insulation structure in the non-boss area of ​​the metal sheet layer. This approach can significantly improve the overall thermal conductivity and flow capacity of the substrate. Within the large-area double-layer insulation structure, the distribution of the drive circuits can be flexibly adjusted according to the needs of the drive / power circuit layout, giving full play to the three-dimensional spatial layout capabilities of the package. By eliminating the discrete structure of the power module and the drive control board in the prior art, it is conducive to the integration of the power module and the drive control board, further improving the module packaging integration and performance.

[0036] 3. In the present invention, insulating layers of high thermal conductivity ceramic composite insulating material are respectively arranged on the inner and outer sides of the metal sheet layer. While simplifying the product structure, enhancing the heat dissipation capability, and significantly reducing the thickness of the power module, it can significantly reduce the thermal resistance of the package, reduce the risk of substrate warping under high temperature difference conditions, and improve the insulation performance and reliability of the package.

[0037] 4. The present invention forms an insulating layer groove by performing window processing on the insulating ink layer. The size of the window is consistent with the pad pattern on the chip surface. It is used for solder printing, chip positioning and chip fixation during power module processing to prevent chip deviation during sintering or welding, and can solve the problem of high-precision welding of the gate pad on the chip surface.

[0038] 5. This invention uses an extended metal sheet layer and drive circuit layer to achieve direct lead-out of power and signal terminals. The power terminals and metal sheet layer are integrated into a single structure, providing a wide routing path. This further reduces the high parasitic parameters associated with conventional packaging technologies. Furthermore, since no additional soldered terminals are required, the packaging process is simplified and reliability is improved.

[0039] 6. The present invention utilizes the driving circuit layer to design multiple extension parts to achieve interconnection with the power chip, avoiding the use of bonding wires and reducing the package parasitic parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a cross-sectional schematic diagram of the composite substrate in the present invention.

[0041] Figure 2 Schematic diagram of the cross section of the composite substrate with integrated heat sink.

[0042] Figure 3 This is a schematic diagram of the cross-sectional structure of an embedded double-sided direct cooling power module (without a heat sink installed).

[0043] Figure 4 Schematic diagram of a multi-layer driving circuit layer.

[0044] Figure 5 Schematic diagram of the cross-sectional structure of an embedded double-sided direct cooling power module (the heat sink is directly mounted on the external insulation layer).

[0045] Figure 6 Schematic diagram of the composite substrate at different stages of the processing process.

[0046] Figure 7 A perspective view of the embedded double-sided direct cooling power module structure (without heat sink installed).

[0047] Figure 8 A three-dimensional view of the embedded double-sided direct cooling power module structure.

[0048] Explanation of the reference numerals: 1-1 boss structure; 1-2 driving circuit layer; 1-3 insulating layer groove; 1-4 internal insulating layer; 1-5 insulating ink layer; 1-6 metal sheet layer; 1-7 external insulating layer; 1-8 metal connection layer; 1-9 gap insulator; 2-1 heat sink; 3-1 upper composite substrate; 3-2 power chip; 3-3 insulating filling layer; 3-4 sintered solder layer; 3-5 lower composite substrate; 4-1 bottom driving line; 4-2 metal connection block; 4-3 intermediate driving line; 4-4 blind hole; 4-5 insulating layer; 4-6 part of the boss structure; 4-7 top driving line; 4-8 part of the insulating ink layer. DETAILED DESCRIPTION

[0049] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0050] The serial numbers assigned to components in this application, such as "first" and "second", are used only to distinguish the objects being described and do not have any order or technical meaning. The terms "connection" and "coupling" used in this application include both direct and indirect connections (couplings) unless otherwise specified. In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating positions or positional relationships, are based on the positions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of this application and simplify the description. They do not indicate or imply that the device or element referred to must have a specific position, be constructed and operate in a specific position, and therefore should not be understood as limiting this application.

[0051] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0052] 1. Specific description of product structure

[0053] As shown in the figure, the embedded double-sided direct cooling power module structure based on the metal core composite substrate proposed by the present invention includes two stacked sheet metal core composite substrates (referred to as composite substrates) and multiple power chips 3-2 arranged in the same layer between the composite substrates; wherein the composite substrates are divided into an upper composite substrate 3-1 and a lower composite substrate 3-5, and the structures of the two are roughly the same. Figure 1-3 and Figure 6 As can be seen in the figure, the composite substrate comprises multiple metal sheets 1-6 arranged in parallel, with gaps between adjacent surfaces, filled with gap insulators 1-9 for bonding. The metal sheets 1-6 are connected together by gap insulators 1-9, forming a rigid support structure for the composite substrate.

[0054] Multiple boss structures 1-1 are spaced apart on the inner surface of each metal sheet 1-6. A double-layered insulating structure is provided in the non-boss areas, excluding the boss structures 1-1, for leveling. The lower layer is an internal insulating layer 1-4, and the upper layer is an insulating ink layer 1-5. The upper and lower composite substrates 3-1 and 3-5 are arranged opposite each other, with their respective boss structures 1-1 paired in a one-to-one correspondence. A power chip 3-2 is embedded between each group of boss structures 1-1, with both sides of the power chip 3-2 securely connected to the surfaces of the boss structures 1-1 via a sintered solder layer 3-4. A drive circuit layer 1-2 is embedded within the double-layered insulating structure on the metal sheet 1-6 opposite the power-connected side of the power chip 3-2. Depending on the orientation of the power-connected side of the power chip 3-2, the drive circuit layer 1-2 can be located on the same composite substrate or on two separate composite substrates. The drive circuit layer 1-2 has multiple extensions for connecting to the power chip 3-2. The insulating ink layer 1-5 leaves windows in the power chip 3-2's electrical connection area, enabling electrical connection between the drive circuit layer 1-2 and the power chip 3-2 via the sintered solder layer 3-4. After each set of boss structures 1-1 is connected to the power chip 3-2, a cavity is formed between the two composite substrates. An insulating filler layer 3-3 is provided within this cavity for bonding purposes.

[0055] The outer surface of the composite substrate is provided with an external insulating layer 1-7 covering each metal sheet layer 1-6, and a heat sink 2-1 is provided outside the external insulating layer 1-7. Figure 5 As shown in FIG, the external insulating layer 1-7 and the heat sink 2-1 can be directly connected by a hot pressing process, or by coating a silicone grease heat conductive layer and fixing the heat sink on the composite substrate using a clamp. The heat generated by each power chip 3-2 is conducted to the heat sink 2-1 through the boss structure 1-1 and the body of the metal sheet layer 1-6. Figure 2 As shown in FIG, a metal connecting layer 1-8 can be provided on the surface of the outer insulating layer 1-7, and the bottom surface of the heat sink 2-1 is connected to the metal connecting layer 1-8 via a sintered solder layer. Alternatively, a thermally conductive layer of silicone grease can be applied between the metal connecting layer 1-8 and the bottom surface of the heat sink 2-1, and the heat sink 2-1 can be secured to the composite substrate using a clamp. This heat conduction process is not hindered by the organic sheet material as in the prior art, and the entire metal sheet layer can be utilized to achieve high-performance thermal conductivity and rapid temperature reduction.

[0056] To facilitate power module installation, the present invention provides an extension at one end of at least one metal sheet layer 1-6 in the composite substrate, serving as a power terminal for mounting and connection, and includes mounting holes in the power terminal. To facilitate signal connection and control, an extension of the drive circuit layer 1-2 and the base metal is provided at the end of the metal sheet layer 1-6 where the drive circuit layer 1-2 resides, serving as a signal terminal.

[0057] like Figure 4 As shown, to meet the requirements of multi-type chip installation and more complex control, the present invention further proposes a multi-layered structure design for the drive circuit layer 1-2. In this example, it includes three levels of stacked drive circuits (bottom drive circuit 4-1, middle drive circuit 4-3, and top drive circuit 4-7), as well as multiple insulating layers 4-5 for electrical isolation. The drive circuits on the lower layer (such as the bottom drive circuit 4-1 and middle drive circuit 4-3) are electrically connected to the drive circuits on the upper layer (such as the middle drive circuit 4-3 and top drive circuit 4-7) or the power connection area of ​​the power chip 3-2 through blind vias 4-4 or metal connection blocks 4-2.

[0058] The power chips 3-2 applicable to the present invention include but are not limited to silicon-based, silicon carbide-based, gallium nitride-based and other power chips.

[0059] 2. Description of product preparation method

[0060] The present invention proposes a method for preparing an embedded double-sided direct cooling power module structure based on a metal core composite substrate, which is characterized by comprising:

[0061] Using electroplating, etching or deposition process, a boss structure 1-1 is formed on the inner surface of the metal sheet layer 1-6, so that the two become an integrated structure;

[0062] Arrange multiple metal sheets 1-6 in parallel in the mold and keep gaps between adjacent surfaces. Use hot pressing, sintering, spraying or deposition process to fill the gaps with insulators to form electrical insulation between the metal sheets 1-6 and form a rigid overall structure. Figure 6 As shown in (a), the left side is the lower substrate and the right side is the upper substrate (the same below).

[0063] An external insulating layer 1-7 is formed on the outer surface of the metal sheet layer 1-6 by hot pressing, sintering, spraying or deposition process to provide electrical insulation of the metal sheet layer 1-6 from the outside; or a metal connecting layer 1-8 is further formed on the surface of the external insulating layer 1-7 by chemical plating, electroplating, deposition or hot pressing process;

[0064] Using hot pressing process, the inner insulating layer 1-4 is covered on the non-convex area of ​​the metal sheet layer 1-6. Figure 6 As shown in (b), the gap insulator 1-9 has been covered by the inner insulating layer 1-4.

[0065] Using photolithography, chemical plating, deposition or evaporation process, metal circuits are made on the surface of the internal insulation layer 1-4 to form the driving circuit layer 1-2. Figure 6 As shown in (c).

[0066] The insulating ink layer 1-5 is covered on the surface of the internal insulating layer 1-4 and the driving circuit layer 1-2 by spraying or brushing technology; the surface of the metal sheet layer 1-6 is made into a sandwich structure at the position where the driving circuit layer 1-2 is present, and into a double-layer structure at the position where there is no driving circuit layer.

[0067] Using laser, etching or cutting technology, according to the installation position of the power chip 3-2, the insulating ink layer 1-5 is opened to form an insulating layer groove 1-3, exposing the surface of the boss structure and the welding position of the corresponding power chip connection area on the driving circuit layer for chip positioning and solder printing. Figure 6 As shown in (d), the driving circuit layer 1-2 has been covered by the insulating ink layer 1-5, and the power connection area of ​​the power chip 3-2 is also exposed.

[0068] Solder is arranged in the insulating layer groove 1-3 by a printing process, and the power chip 3-2 is placed. After the two composite substrates are placed opposite to each other and pressed together, a melting or sintering process is used to firmly bond the solder.

[0069] Insulating material is placed in the cavity between the composite substrates using an injection molding or potting process to form an insulating filling layer 3-3 that firmly bonds the two composite substrates;

[0070] The heat sink 2-1 is mounted on the outer insulating layer 1-7 by a hot pressing process, or mounted on the metal connection layer 1-8 by a welding process. Alternatively, thermal conductive silicone grease is applied to the outside of the composite substrate, and the heat sink 2-1 is fixed to the composite substrate using a clamp.

[0071] 3. More specific product or processing details

[0072] The composite substrate structure proposed in the present invention integrates heat dissipation, drive circuits, and metal sheet layers, which can simultaneously realize the three-dimensional spatial layout of the control circuit, chip positioning, interconnection between the upper and lower substrates, efficient heat dissipation of the module, and the shortest path connection between the module and the external radiator on the substrate. It can greatly simplify the manufacturing process of double-sided direct heat dissipation power modules and significantly improve the electrical and thermal performance and packaging reliability of the power modules.

[0073] Both the upper composite substrate 3-1 and the lower composite substrate 3-5 use the metal sheet layer 1-6 as the core structure, which can be used for chip heat dissipation and to build an insulating layer and a drive circuit on its surface to achieve electrical interconnection. At the beginning of the rough material cutting, the structure extending from the end of the metal sheet layer 1-6 is retained, which serves as the power terminal for fixed installation of the power module and the auxiliary drive circuit to form a signal terminal connected to the external circuit. For high-power application scenarios, the metal sheet layer 1-6 is preferably made of metal copper or aluminum. Metal copper or aluminum has excellent electrical and thermal conductivity, and is suitable for high-current application conditions of high-power modules and the heat dissipation requirements of high-power chips.

[0074] Boss structure 1-1 is fabricated using deposition, electroplating, and etching processes, growing on the surface of metal sheet 1-6 and forming an integral structure with metal sheet 1-6. Boss structure 1-1 rapidly transfers heat from power chip 3-2 directly to the metal sheets 1-6 above and below, fully utilizing the chip's upper and lower surfaces for heat dissipation. This eliminates the interconnect copper gasket fabrication and sintering steps typically found in existing embedded packaging processes, simplifying the module packaging process while improving package reliability.

[0075] Through processes such as hot pressing, sintering, and spraying of ceramic structural materials, as well as physical / chemical vapor deposition processes for semiconductor substrate manufacturing, interstitial insulators 1-9 are grown in the gaps between adjacent metal sheets 1-6, achieving electrical insulation between circuit patterns and high-strength connections between discrete metal substrates. For high-voltage / high-power applications, the insulating layer preferably comprises a ceramic composite insulating material with high thermal conductivity and high insulation properties, such as aluminum nitride, silicon nitride, or silicon carbide. Specifically, a high-thermal-conductivity ceramic powder can be doped with a high-insulation matrix material such as epoxy resin or polyurethane.

[0076] Through a combination of hot pressing, sintering, and spraying processes using ceramic structural materials, as well as physical / chemical vapor deposition processes for semiconductor substrate manufacturing, an external insulating layer 1-7 is grown on the backside of the metal sheet 1-6. This ensures insulation between the metal sheet 1-6 and the external heat sink 2-1, as well as efficient heat dissipation from the module. External insulating layer 1-7 is preferably composed of a composite insulating material made of highly thermally conductive and insulating ceramics such as aluminum nitride, silicon nitride, and silicon carbide. While only tens of microns thick, it can achieve a withstand voltage of several thousand volts. Furthermore, the entire backside of the substrate is covered with a highly thermally conductive ceramic composite insulating layer, fully utilizing the entire heat dissipation area of ​​the substrate, achieving an ultra-low thermal resistance power module package.

[0077] A metal connection layer 1-8 is grown on the surface of the external insulating layer 1-7 through a metal film process such as electroless plating, electroplating, physical vapor deposition, or chemical vapor deposition, or a metal foil hot pressing process, to achieve a direct connection between the composite substrate and the heat sink 2-1. The metal connection layer 1-8 is preferably made of a highly thermally conductive metal such as copper or aluminum. A nano-scale nickel or gold anti-oxidation layer can also be provided on the metal connection layer 1-8 to prevent oxidation during module processing and operation.

[0078] Internal insulation layers 1-4 are applied to the metal sheet layers 1-6 through a process such as heat pressing. For high-voltage and high-power applications, internal insulation layers 1-4 are preferably made of fiberglass composite materials, which have excellent thermal conductivity, insulation properties, and mechanical strength.

[0079] A metal circuit is fabricated on the surface of the internal insulating layer 1-4 by using photolithography, chemical plating, deposition or evaporation technology to form a driving circuit layer 1-2; an insulating ink layer 1-5 covers the surface of the internal insulating layer 1-4 and the driving circuit layer 1-2.

[0080] After coating the insulating ink layer 1-5, a window opening process such as laser / etching / cutting is used to make an insulating layer groove 1-3 to expose the surface of the boss structure 1-1 and the welding position of the chip pad corresponding to the driving circuit layer 1-2. It is used for solder printing, chip positioning and chip fixing during power module processing, preventing chip deviation during sintering / welding, and solving the problem of high-precision welding of the gate pad on the chip surface.

[0081] The sintered solder layer 3-4 is preferably made of nanosilver or nanocopper. Nanosilver or nanocopper sintering offers the advantages of low-temperature sintering and high-temperature serviceability, while also exhibiting superior thermal and electrical conductivity compared to conventional solder paste. This is particularly true for high-power modules, which place higher demands on chip heat dissipation and module flow capacity. The thermal expansion coefficient of nanosilver or nanocopper is close to that of the boss structure 1-1 and the drive circuit layer 1-2. Therefore, the thermal stress between the materials is lower than that of other types of solder, further improving module packaging reliability.

[0082] The inter-board insulating filler layer 3-3 provides electrical insulation between the upper and lower composite substrates and between the chips. It is preferably made of a composite insulating material with excellent insulation properties and high-temperature resistance, such as epoxy resin, polyurethane, polyimide, parylene, and silicone. Injection molding, potting, or vacuum potting are preferred methods for filling the inter-board insulating filler layer 3-3. High-temperature vacuum potting effectively fills small internal gaps, prevents air bubbles from forming within the module, and improves the module's insulation performance.

[0083] Finally, heat sink 2-1 is integrated onto the surface of external insulation layer 1-7 or metal connection layer 1-8. The specific operation method for integrating heat sink 2-1 can be hot pressing, applying a silicone grease thermal conductive layer (using a clamp), or using a welding process (for the metal connection layer).

[0084] In summary, the present invention uses integrated heat dissipation and drive metal core composite substrate to realize substrate multi-layer circuit layout, integrated integration of heat sink and substrate, double-sided direct sintering process of chip, high-temperature vacuum potting of insulating medium and other processes, which fully utilizes the three-dimensional space multi-layer circuit layout potential and thermal conductivity of the composite substrate, is conducive to the integration of power module and drive control board, and greatly simplifies the power module packaging process. The use of high thermal conductivity ceramic composite thermal interface connection material on the surface of the substrate greatly improves the module insulation voltage resistance and significantly reduces the package thermal resistance, realizing the direct integration of the external heat sink and the module. The module power and signal terminals are integrated with the integrated heat dissipation and drive metal core composite substrate, without the need for additional welding connection terminals. At the same time, the wide wiring substrate frame greatly reduces the package parasitic parameters.

[0085] Therefore, the present invention is based on an embedded double-sided direct cooling power module structure with integrated heat dissipation and a driven metal core composite substrate, achieving extremely low package thermal resistance and parasitic parameters, while having the advantages of small size, high power density, and integrated double-sided direct heat dissipation. It is a solution with great development potential for the development of power modules towards high frequency, high power density, and high performance.

Claims

1. An embedded double-sided direct cooling power module structure based on a metal core composite substrate, characterized in that: It includes two stacked sheet-shaped metal core composite substrates and a plurality of power chips arranged in the same layer between the composite substrates; wherein, The composite substrate comprises a plurality of metal sheets arranged in parallel, with gaps between adjacent surfaces being filled with gap insulators for bonding; the metal sheets are connected as a whole by the gap insulators, serving as a rigid support structure for the composite substrate; Multiple boss structures are spaced apart on the inner surface of each metal sheet; a double-layer insulation structure is provided in the non-boss area for leveling, with the lower layer being an internal insulation layer and the upper layer being an insulating ink layer; the two composite substrates are arranged relative to each other so that the boss structures are grouped in a one-to-one correspondence; a power chip is embedded and installed between each group of boss structures, with its two side surfaces fixedly connected to the surfaces of the boss structures; a drive circuit layer is provided on the metal sheet opposite the power-connected side of the power chip, embedded in the double-layer insulation structure; the drive circuit layer has multiple extensions for connecting to the power chip, and the insulating ink layer has windows in the power-connected area of ​​the power chip, enabling electrical connection between the drive circuit layer and the power chip; after each group of boss structures is connected to the power chip, a cavity is formed between the two composite substrates, and an insulating filling layer is provided in the cavity for bonding; The outer surface of the composite substrate has an external insulating layer covering each metal sheet layer, and a heat sink is arranged outside the external insulating layer; the heat generated by each power chip is conducted to the heat sink through the boss structure and the metal sheet layer body.

2. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: The driving circuit layer has a multi-layer structure, including multi-level stacked driving circuits and an insulating layer for electrical isolation; The driving circuit on the lower layer is electrically connected to the driving circuit on the upper layer or the power connection area of ​​the power chip through a blind hole or a metal connecting block.

3. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: According to the different directions of the power chip's power-connected side, the driving circuit layers are located on the same composite substrate or on two composite substrates.

4. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: The power chip and the boss structures on both sides thereof are fixedly connected via a sintered solder layer; the power connection area of ​​the power chip and the driving circuit layer are electrically connected via a sintered solder layer.

5. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: A metal connection layer is provided on the surface of the external insulating layer, and the bottom surface of the radiator is connected to the metal connection layer through a sintered solder layer; or a silicone grease heat conductive layer is provided between the metal connection layer and the bottom surface of the radiator, and the radiator is fixed to the composite substrate using a clamp.

6. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: The external insulating layer and the bottom surface of the radiator are connected by hot pressing; alternatively, a silicone grease heat conductive layer is provided between the external insulating layer and the bottom surface of the radiator, and the radiator is fixed on the composite substrate by a clamp.

7. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: An extension portion is provided at one end of at least one metal sheet layer in the composite substrate as a power terminal for installation and connection, and a mounting hole is provided on the power terminal.

8. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that: At the end of the metal sheet layer where the driving circuit layer is located, an extension portion of the driving circuit layer and the bottom metal is provided as a signal terminal.

9. The method for preparing the embedded double-sided direct cooling power module structure based on the metal core composite substrate according to claim 1, characterized in that: include: Using electroplating, etching or deposition process, a boss structure is formed on the inner surface of the metal sheet layer, so that the two become an integrated structure; Arrange multiple metal sheets side by side in a mold while maintaining gaps between adjacent surfaces. Fill the gaps with an insulator using hot pressing, sintering, spraying, or deposition processes to achieve electrical insulation between the metal sheets and form a rigid overall structure. Using hot pressing, sintering, spraying or deposition process, an external insulating layer is formed on the outer surface of the metal sheet layer to form electrical insulation of the metal sheet layer to the outside; or further using chemical plating, electroplating, deposition or hot pressing process, a metal connecting layer is formed on the surface of the external insulating layer; Using a hot pressing process, the non-convex area of ​​the metal sheet is covered with an internal insulating layer; using a photolithography, chemical plating, deposition or evaporation process, a metal circuit is formed on the surface of the internal insulating layer to form a driving circuit layer; The surface of the internal insulation layer and the driving circuit layer is covered with an insulating ink layer by spraying or brushing; the surface of the metal sheet layer is formed into a sandwich structure at the location where the driving circuit layer is present, and a double-layer structure at the location where the driving circuit layer is absent; Using laser, etching or cutting technology, the insulating ink layer is opened to form an insulating layer groove according to the installation position of the power chip, exposing the surface of the boss structure and the welding position of the power chip contact area on the driving circuit layer for chip positioning and solder printing; A printing process is used to arrange solder in the groove of the insulating layer and place the power chip; after the two composite substrates are placed opposite each other and pressed together, a welding or sintering process is used to firmly bond the solder; Insulating material is placed in the cavity between the composite substrates using an injection molding or potting process to form an insulating filling layer that firmly bonds the two composite substrates; The heat sink is mounted on the external insulating layer by a hot pressing process, or is mounted on the metal connection layer by a welding process; alternatively, a silicone grease thermal conductive layer is coated on the outside of the composite substrate, and the heat sink is fixed to the composite substrate by a clamp.

10. The method according to claim 9, characterized in that The material of the metal sheet layer is copper or aluminum; The material of the gap insulator is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; The material of the outer insulating layer is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; The inner insulation layer is a glass fiber composite material; The driving circuit layer is made of copper or aluminum; The material of the insulating filling layer is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; The material of the metal connection layer is copper or aluminum; or, an anti-oxidation layer made of nano-scale metal nickel or gold is further provided on the surface of the metal connection layer.

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