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

Abstract

The invention relates to a semiconductor module packaging technology, and aims to provide an embedded double-sided direct cooling power module structure based on a metal core composite substrate. Comprising two laminated sheet-shaped metal core composite substrates, and each composite substrate is provided with a plurality of metal sheet layers which are arranged in parallel and are connected into a whole through a gap insulator; a plurality of boss structures are arranged on the inner surface of the metal sheet layer at intervals, a double-layer insulation structure used for filling and leveling is arranged in a non-boss area, and a driving circuit layer is arranged in an embedded mode. The two composite substrates are oppositely arranged, so that the boss structures are correspondingly grouped and embedded with the power chips; an insulating filling layer is arranged in the inter-plate cavity, an external insulating layer covering the metal sheet layers simultaneously is arranged on the outer surface of the inter-plate cavity, and a radiator is arranged on the outer side of the external insulating layer. According to the invention, the metal sheet layer can directly conduct heat generated by the chip to the bottom of the heat radiator, so that the heat radiation path can be obviously shortened, the packaging thickness of the module is reduced, and the through-current capability, the packaging reliability and the mechanical performance of the product of the chip are greatly improved.

Description

Technical Field

[0001] The present invention relates to semiconductor module packaging technology, and more specifically, 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 mainly uses DBC substrates and bonding wires to achieve electrical connections between chips, interconnection layers, and module terminals. However, with the increasing replacement of silicon devices by wide-bandgap semiconductor devices in more and more fields, the parasitic inductance introduced by bonding wires severely limits the high-frequency applications of wide-bandgap semiconductor devices. At the same time, the existing double-sided copper-clad ceramic substrates can only achieve single-layer routing of circuits, severely limiting the circuit layout in terms of space. There are also literature proposals for power device packaging solutions based on PCB substrate embedding technology. However, a large amount of organic composite insulating materials are used in the PCB substrate, which makes it difficult to efficiently dissipate the heat of power chips. In addition, the traditional single-sided heat dissipation method will cause the module temperature to be too high, seriously affecting the excellent performance of wide-bandgap semiconductor devices.

[0003] Therefore, in view of the series of technical challenges faced by large-capacity power modules, it is urgent to develop a module packaging method 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 deficiencies of high parasitic parameters and poor heat dissipation in the existing large-capacity 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] Provide an embedded double-sided direct cooling power module structure based on a metal core composite substrate, including two sheet-shaped metal core composite substrates arranged in a stacked manner, and a plurality of power chips arranged on the same layer between the composite substrates; wherein,

[0007] The composite substrate has a plurality of metal sheet layers arranged side by side, with a gap maintained between adjacent surfaces and filled with a gap insulator for bonding; after each metal sheet layer is connected into a whole through the gap insulator, it serves as a rigid support structure of the composite substrate;

[0008] On the inner surface of each metal sheet layer, a plurality of boss structures are provided at intervals; in the non-boss area, a double-layer insulating structure is provided for filling, the lower layer is an internal insulating layer, and the upper layer is an insulating ink layer; two composite substrates are arranged opposite to each other so that the boss structures are grouped in one-to-one correspondence; a power chip is embedded and installed between each group of boss structures, and its two side surfaces are fixedly connected to the surfaces of the boss structures; on the metal sheet layer opposite to the power supply side of the power chip, a driving circuit layer is provided and embedded in the double-layer insulating structure; the driving circuit layer has a plurality of extension parts connecting the power chips, and the insulating ink layer leaves a window in the power supply area of the power chip, so that the driving circuit layer and the power chip can be electrically connected; after each group of boss structures are connected to the power chip, a cavity is formed between the two composite substrates, and an insulating filling layer for bonding is provided in the cavity;

[0009] The outer surface of the composite substrate has an external insulating layer that simultaneously covers each metal sheet layer, and a heat sink is provided on the outside of 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 solution of the present invention, the driving circuit layer has a multi-layer structure, including a plurality of driving circuits arranged in a multi-stage stacked manner and an insulating layer for electrical isolation; between the driving circuit located in the lower layer and the power supply area of the driving circuit or the power chip located in the upper layer, electrical connection is achieved through blind holes or metal connection blocks.

[0011] As a preferred solution of the present invention, according to the different directions of the power supply side of the power chip, the driving circuit layer is located on the same composite substrate or on two composite substrates respectively.

[0012] As a preferred solution of the present invention, the power chip is fixedly connected to the boss structures on its two sides through a sintered solder layer; the power supply area of the power chip is electrically connected to the driving circuit layer through a sintered solder layer.

[0013] As a preferred solution of the present invention, a metal connection layer is provided on the surface of the external insulating layer, and the bottom surface of the heat sink is connected to the metal connection layer through a sintered solder layer; or a silicone grease heat conduction layer is provided between the metal connection layer and the bottom surface of the heat sink, and the heat sink is fixed on the composite substrate by using a fixture.

[0014] As a preferred solution of the present invention, the external insulating layer and the bottom surface of the heat sink are connected by a hot pressing method; or, a silicone grease heat conduction layer is provided between the external insulating layer and the bottom surface of the heat sink, and the heat sink is fixed on the composite substrate by using a fixture.

[0015] As a preferred solution of the present invention, an extension part 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 an installation hole is provided on the power terminal.

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

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

[0018] Adopting electroplating, etching or deposition process to form a boss structure on the inner surface of the metal sheet layer, making the two into an integral structure;

[0019] Arranging multiple metal sheet layers side by side in a mold and keeping a gap between adjacent surfaces, and filling the gap with an insulator by using hot pressing, sintering, spraying or deposition process to form electrical insulation between the metal sheet layers and form a rigid integral structure at the same time;

[0020] Adopting hot pressing, sintering, spraying or deposition process to form an external insulation layer on the outer surface of the metal sheet layer for forming electrical insulation of the metal sheet layer to the outside; or further adopting chemical plating, electroplating, deposition or hot pressing process to form a metal connection layer on the surface of the external insulation layer;

[0021] Adopting hot pressing process to cover the internal insulation layer in the non-boss area of the metal sheet layer; adopting photolithography, chemical plating, deposition or evaporation process to fabricate a metal circuit on the surface of the internal insulation layer to form a driving circuit layer;

[0022] Adopting spraying or brushing process to cover an insulating ink layer on the surface of the internal insulation layer and the driving circuit layer; making the surface of the metal sheet layer into a sandwich structure at the position where there is a driving circuit layer and a double-layer structure at the position where there is no driving circuit layer;

[0023] Adopting laser, etching or cutting process to perform windowing treatment on the insulating ink layer according to the installation position of the power chip to form an insulating layer groove, exposing the surface of the boss structure and the welding position on the driving circuit layer corresponding to the power chip power connection area for chip positioning and solder printing;

[0024] Adopting printing process to arrange solder in the insulating layer groove, place the power chip; after placing two composite substrates opposite to each other and pressing them together, adopt welding or sintering process to firmly bond the solder;

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

[0026] Adopting hot pressing process to install the heat sink on the external insulation layer, or adopting welding process to install the heat sink on the metal connection layer; or, coating a silicone grease heat conduction layer on the outside of the composite substrate and fixing the heat sink on the composite substrate by using a fixture.

[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, further, an anti-oxidation layer made of nanoscale metal nickel or gold is provided on the surface of the metal connection layer.

[0028] Description of the invention principle:

[0029] In the prior art, the design schemes of power modules that use two substrates to clamp power chips or bury power chips in PCB substrates can play the roles of double-sided heat dissipation and reducing parasitic parameters through packaging respectively. However, the power modules capable of double-sided heat dissipation described in the published literature usually adopt traditional DBC substrates, AMB substrates or other double-sided copper-clad ceramic substrates. Due to the generally large gap between the thermal expansion coefficients of ceramic substrates and metals, it is difficult for power modules using metal-ceramic substrates to achieve a multi-layer structure, and warping and delamination cracking defects of the substrates are likely to occur under high-temperature conditions. In addition, the existing PCB substrate embedding scheme usually uses an organic resin substrate as the packaging insulating material (such as organic substrates like FR4). These substrate materials have low thermal conductivity, which will severely limit the heat dissipation of power devices. Therefore, the driving control boards in current power modules usually still adopt a discrete structure.

[0030] The present invention innovatively proposes to use multiple juxtaposed metal sheet layers as the rigid metal core structure of the composite substrate, construct a boss structure on the metal sheet layer, and then stack two composite substrates relatively, embedding the power chip between two metal sheet layers; in this way, the plane-expanded metal sheet layer is used as a heat conduction medium to transfer the heat generated during the operation of the power chip to the radiator. At the same time, the present invention abandons the practice of using nested substrates to arrange driving circuits in the prior art, and directly arranges the driving circuit layer in the double-layer insulating structure arranged in the non-boss area of the metal sheet layer. This design not only simplifies the product structure and processing technology, but also can realize the layout requirements of more complex driving control circuits through a multi-layer design method, meeting the increasingly high requirements for product function realization. Compared with the technology of setting metal blocks outside the power chip for power connection in the traditional process, the present invention embeds the driving circuit layer in the double-layer insulating structure in the non-boss area, which can realize a more flexible layout design of the circuit pattern and is not restricted by the chip layout. At the same time, the metal sheet layer serves as a conductive structure, a support structure and a heat conduction medium at the same time, and its functions and structures are fully utilized, which can further strengthen the overall structural strength and heat dissipation efficiency, and also further improve the current-carrying capacity of the module.

[0031] In addition, the present invention proposes to use a highly thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride, silicon carbide, etc. for filling each insulating layer. In the power module product, each insulating part has a thermal expansion coefficient close to that of a metallic material; while maintaining high thermal conductivity and insulating properties, it can achieve the purpose of a stable overall structure and enhanced product strength.

[0032] Therefore, the implementation solution of the present invention breaks through the inherent design thinking of those skilled in the art. By directly embedding the power module and the drive circuit between two metal core composite substrates, the integration of the substrate and the heat sink, the complex control requirements of different chips inside the module, and the double-sided direct sintering solution of the power chip are realized, obtaining the effects of high-efficiency heat dissipation, low stray inductance, and integrated drive circuit of the high-power module.

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

[0034] 1. In the present invention, the connection between the power chip and the two-sided boss structures and the drive circuit layer is realized by direct sintering or welding. The metal sheet layer can directly conduct the heat generated by the chip to the bottom of the heat sink, 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, reduce the module packaging thickness, and at the same time greatly improve the current-carrying capacity of the chip, packaging reliability, and product mechanical properties.

[0035] 2. In the present invention, the structure of the traditional embedded organic insulating substrate is completely cancelled, and the drive circuit is embedded in the double-layer insulating structure in the non-boss area of the metal sheet layer. This approach can greatly improve the overall thermal conductivity and current-carrying capacity of the substrate. Inside the large-area double-layer insulating structure, the distribution of the drive circuit can be flexibly adjusted according to the layout requirements of the drive / power circuit, giving full play to the three-dimensional space layout ability of the packaging. By cancelling the discrete structure of the power module and the drive control board in the prior art, it is beneficial to realize the integration of the power module and the drive control board, further improving the packaging integration degree and performance of the module.

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

[0037] 4. In the present invention, an insulating layer groove is formed by windowing the insulating ink layer. The window size is the same as the pad pattern on the chip surface, which is used for solder printing, chip positioning, and chip fixation during the processing of the power module, preventing chip offset during the sintering or welding process, and being able to solve the problem of high-precision welding of the gate pads on the chip surface.

[0038] 5. The present invention realizes the direct extraction of power terminals and signal terminals by using the method of extending the metal sheet layer and the driving circuit layer. Among them, the power terminal and the metal sheet layer are an integral structure, which has the characteristic of a wide routing path, further reducing the problem of excessive packaging parasitic parameters brought by the traditional technology. In addition, since there is no need to weld the terminals additionally, the packaging process flow can be further simplified and the packaging reliability can be improved.

[0039] 6. The present invention uses the driving circuit layer to design multiple extension parts to realize the interconnection with the power chip, avoiding the use of bonding wires and reducing the packaging parasitic parameters. Description of the Drawings

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

[0041] Figure 2 It is a schematic cross-sectional view of the composite substrate integrated with a radiator.

[0042] Figure 3 It is a schematic cross-sectional structure view of the embedded double-sided direct cooling power module (without installing a radiator).

[0043] Figure 4 It is a schematic view of the driving circuit layer with a multi-layer structure.

[0044] Figure 5 It is a schematic cross-sectional structure view of the embedded double-sided direct cooling power module (directly installing a radiator on the external insulation layer).

[0045] Figure 6 It is a schematic view of the composite substrate at different stages of the processing process.

[0046] Figure 7 It is a three-dimensional view of the structure of the embedded double-sided direct cooling power module (without installing a radiator).

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

[0048] Description of the reference numerals: 1-1 boss structure; 1-2 driving circuit layer; 1-3 insulation layer groove; 1-4 internal insulation layer; 1-5 insulation ink layer; 1-6 metal sheet layer; 1-7 external insulation layer; 1-8 metal connection layer; 1-9 gap insulator; 2-1 radiator; 3-1 upper composite substrate; 3-2 power chip; 3-3 insulation filling layer; 3-4 sintered solder layer; 3-5 lower composite substrate; 4-1 bottom driving route; 4-2 metal connection block; 4-3 intermediate driving circuit; 4-4 blind hole; 4-5 insulation layer; 4-6 partial boss structure; 4-7 top driving circuit; 4-8 partial insulation ink layer. Detailed Embodiment

[0049] The following further describes in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0050] In this application, the serial numbers assigned to the components themselves, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meanings. And the "connection" and "coupling" mentioned in this application, unless otherwise specified, both include direct and indirect connections (couplings). In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application.

[0051] In this application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0052] I. Specific Description of the Product Structure

[0053] As shown in the figure, the embedded double-sided direct cooling power module structure based on a metal-core composite substrate proposed by the present invention includes two sheet-shaped metal-core composite substrates (referred to as composite substrates for short) arranged in a stacked manner, and a plurality of power chips 3-2 arranged on 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 their structures are substantially the same. From Figure 1-3 and Figure 6 it can be seen that the composite substrate has a plurality of metal sheet layers 1-6 arranged side by side, with a gap maintained between adjacent surfaces, and a gap insulator 1-9 for bonding is filled. After each metal sheet layer 1-6 is connected into a whole through the gap insulator 1-9, it serves as the rigid support structure of the composite substrate.

[0054] On the inner surface of each metal sheet layer 1-6, a plurality of boss structures 1-1 are provided at intervals; in the non-boss area except the boss structures 1-1, a double-layer insulating structure for filling is provided, the lower layer of which is an internal insulating layer 1-4 and the upper layer is an insulating ink layer 1-5. The upper composite substrate 3-1 and the lower composite substrate 3-5 are arranged opposite to each other, and the respective boss structures 1-1 are paired into groups in a one-to-one correspondence; a power chip 3-2 is embedded and installed between each group of boss structures 1-1, and the two side surfaces of the power chip 3-2 are fixedly connected to the surfaces of the boss structures 1-1 through a sintered solder layer 3-4. On the metal sheet layer 1-6 opposite to the power supply side of the power chip 3-2, a driving circuit layer 1-2 embedded in the double-layer insulating structure is provided. Depending on the direction of the power supply side of the power chip 3-2, the driving circuit layer 1-2 is located on the same composite substrate or on two composite substrates respectively. The driving circuit layer 1-2 has a plurality of extending parts connecting the power chip 3-2, and the insulating ink layer 1-5 leaves a window in the power supply area of the power chip 3-2, so that the driving circuit layer 1-2 and the power chip 3-2 can be electrically connected through the sintered solder layer 3-4. After each group of boss structures 1-1 is connected to the power chip 3-2, a cavity is formed between the two composite substrates, and an insulating filling layer 3-3 for bonding is provided in the cavity.

[0055] On the outer surface of the composite substrate, there is an external insulating layer 1-7 that simultaneously covers each metal sheet layer 1-6, and a heat sink 2-1 is provided on the outside of the external insulating layer 1-7. As Figure 5 shown, the external insulating layer 1-7 and the heat sink 2-1 can be directly connected by a hot pressing process, or a silicone grease heat conduction layer can be coated, and the heat sink can be fixed on the composite substrate by using a fixture. The heat generated by each power chip 3-2 is conducted to the heat sink 2-1 through the boss structures 1-1 and the body of the metal sheet layer 1-6. As Figure 2 shown, a metal connection layer 1-8 can be provided on the surface of the external insulating layer 1-7, and the bottom surface of the heat sink 2-1 is connected to the metal connection layer 1-8 through a sintered solder layer. Alternatively, a silicone grease heat conduction layer is coated between the metal connection layer 1-8 and the bottom surface of the heat sink 2-1, and the heat sink 2-1 is fixed on the composite substrate by using a fixture. During the heat conduction process, the heat will not be blocked by the organic board as in the prior art, and high-performance heat conduction and rapid cooling can be achieved by using all the metal sheet layers.

[0056] To realize the installation of the power module, in the present invention, at one end of at least one metal sheet layer 1-6 of the composite substrate, an extending part is provided as a power terminal for installation and connection, and an installation hole is provided on the power terminal. To realize signal connection for control, at the end of the metal sheet layer 1-6 where the driving circuit layer 1-2 is located, an extending part of the driving circuit layer 1-2 and the bottom metal is provided as a signal terminal.

[0057] AsFigure 4 As shown, to meet the requirements of multi-type chip installation and more complex control, the present invention further proposes a multi-layer structure design for the driving circuit layer 1-2. In this example, it includes three levels of stacked driving circuits (the bottom driving circuit 4-1, the middle driving circuit 4-3, and the top driving circuit 4-7), as well as multiple insulating layers 4-5 for electrical isolation; between the driving circuits in the lower layer (such as the bottom driving circuit 4-1 and the middle driving circuit 4-3) and the power chip 3-2's power connection area in the upper layer (such as the middle driving circuit 4-3 and the top driving circuit 4-7), electrical connection is achieved through blind holes 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, power chips based on silicon, silicon carbide, gallium nitride, etc.

[0059] II. Description of the product preparation method

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

[0061] Adopt electroplating, etching, or deposition process to form a boss structure 1-1 on the inner surface of the metal sheet layer 1-6, making the two into an integral structure;

[0062] Arrange multiple metal sheet layers 1-6 side by side in a mold and keep a gap between adjacent surfaces. Adopt hot pressing, sintering, spraying, or deposition process to fill the insulator in the gap, so as to form electrical insulation between the metal sheet layers 1-6 and at the same time form a rigid integral structure. At this time, the inner surface of the substrate is as shown in (a) below, with the left side being the lower substrate and the right side being the upper substrate (the same hereinafter). Figure 6 As shown in (a) below, the left side is the lower substrate and the right side is the upper substrate (the same hereinafter).

[0063] Adopt hot pressing, sintering, spraying, or deposition process to form an external insulating layer 1-7 on the outer surface of the metal sheet layer 1-6 for forming electrical insulation of the metal sheet layer 1-6 to the outside; or further adopt chemical plating, electroplating, deposition, or hot pressing process to form a metal connection layer 1-8 on the surface of the external insulating layer 1-7;

[0064] Adopt hot pressing process to cover the non-boss area of the metal sheet layer 1-6 with the internal insulating layer 1-4. At this time, the inner surface of the substrate is as shown in (b) below, and the gap insulator 1-9 has been covered by the internal insulating layer 1-4. Figure 6 As shown in (b) below, the gap insulator 1-9 has been covered by the internal insulating layer 1-4.

[0065] Adopt photolithography, chemical plating, deposition, or evaporation process to fabricate metal lines on the surface of the internal insulating layer 1-4 to form the driving circuit layer 1-2. At this time, the inner surface of the substrate is as shown in (c) below. Figure 6 As shown in (c) below.

[0066] Adopt the spraying or brushing process to cover the surface of the internal insulation layer 1-4 and the driving circuit layer 1-2 with an insulating ink layer 1-5; make the surface of the metal sheet layer 1-6 have a sandwich structure at the position where there is the driving circuit layer 1-2 and a double-layer structure at the position where there is no driving circuit layer.

[0067] Adopt the laser, etching or cutting process to perform windowing treatment on the insulating ink layer 1-5 according to the installation position of the power chip 3-2 to form an insulating layer groove 1-3, exposing the surface of the boss structure and the welding position on the driving circuit layer corresponding to the power chip power connection area for chip positioning and solder printing. At this time, the inner surface of the substrate is as Figure 6 shown in (d) of the figure. 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] Adopt the printing process to arrange solder in the insulating layer groove 1-3, place the power chip 3-2; after placing the two composite substrates opposite to each other and pressing them together, adopt the melting or sintering process to firmly bond the solder;

[0069] Adopt the injection molding or potting process to fill the cavity between the composite substrates with insulating materials to form an insulating filling layer 3-3 that firmly bonds the two composite substrates;

[0070] Adopt the hot pressing process to install the radiator 2-1 on the external insulation layer 1-7, or adopt the welding process to install the radiator 2-1 on the metal connection layer 1-8. Or, apply thermal conductive silicone grease on the outside of the composite substrate and use a fixture to fix the radiator 2-1 on the composite substrate.

[0071] III. More specific product or processing details

[0072] The composite substrate structure integrating heat dissipation, driving circuit and metal sheet layer proposed by the present invention 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, which can greatly simplify the manufacturing process of the double-sided direct heat dissipation power module and significantly improve the electrical, thermal performance and packaging reliability of the power module.

[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 not only be used for chip heat dissipation, but also build an insulating layer and a driving circuit on its surface to achieve electrical interconnection. At the beginning stage of rough cutting, retain the structure extending from the end of the metal sheet layer 1-6 as the power terminal for fixed installation of the power module and the signal terminal for assisting the driving circuit to form a connection with the external circuit respectively. 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 conductivity and thermal conductivity, and is suitable for the high-current application conditions of high-power modules and the heat dissipation requirements of high-power chips.

[0074] The boss structure 1-1 is fabricated by processes such as deposition / electroplating / etching, etc., and grows on the surface of the metal sheet layer 1-6, being an integral structure with the metal sheet layer 1-6. The boss structure 1-1 can rapidly conduct the heat of the power chip 3-2 directly to the metal sheet layers 1-6 on both the upper and lower sides, making full use of the simultaneous heat dissipation on both the upper and lower surfaces of the chip. At the same time, it avoids processes such as the production of interconnected copper gaskets and sintering in the existing embedded packaging process, simplifies the module packaging process and improves the packaging reliability.

[0075] Through processes such as hot pressing, sintering, spraying of ceramic structural materials and physical / chemical vapor deposition processes for semiconductor substrate manufacturing, etc., the gap insulator 1-9 grows in the gap between adjacent metal sheet layers 1-6, and is used to achieve electrical insulation between circuit patterns and high-strength connection of discrete metal substrates. For high-voltage / high-power application scenarios, the insulating layer preferably includes ceramic composite insulating materials with high thermal conductivity and high insulation performance such as aluminum nitride, silicon nitride, silicon carbide, etc. Specifically, high-thermal-conductivity ceramic powders can be doped into matrix materials with high insulation performance such as epoxy resin and polyurethane.

[0076] Through manufacturing processes such as hot pressing, sintering, spraying of ceramic structural materials and physical / chemical vapor deposition processes for semiconductor substrate manufacturing, etc., the external insulating layer 1-7 grows on the back of the metal sheet layer 1-6, and is used to achieve insulation between the metal sheet layer 1-6 and the external radiator 2-1 and efficient heat dissipation of the module. The external insulating layer 1-7 preferably includes composite insulating materials of ceramics with high thermal conductivity and high insulation performance such as aluminum nitride, silicon nitride, silicon carbide, etc. A thickness of only dozens of microns can achieve a withstand voltage of thousands of volts. At the same time, growing a high-thermal-conductivity ceramic composite insulating layer on the entire back surface of the substrate can make full use of the entire heat dissipation area of the substrate to achieve a power module package with ultra-low thermal resistance.

[0077] Through metal film processes such as electroless plating / electroplating / physical vapor deposition / chemical vapor deposition, or hot pressing of metal foil, the metal connection layer 1-8 grows on the surface of the external insulating layer 1-7, and is used to achieve direct connection between the composite substrate and the radiator 2-1. The metal connection layer 1-8 preferably uses high-thermal-conductivity metal materials such as copper and aluminum. At the same time, a nano-scale metal nickel and gold anti-oxidation layer can also be provided on the metal connection layer 1-8 to prevent oxidation of the metal layer during module processing and operation.

[0078] Through manufacturing processes such as hot pressing, etc., the internal insulating layer 1-4 is covered on the surface of the metal sheet layer 1-6. For high-voltage and high-power application scenarios, the internal insulating layer 1-4 preferably uses glass fiber composite material. Glass fiber composites, etc. have excellent thermal conductivity, insulation performance and mechanical strength.

[0079] Using photolithography, chemical plating, deposition or evaporation processes, metal lines are fabricated on the surface of the internal insulation layer 1-4 to form the drive line layer 1-2; the insulating ink layer 1-5 covers the surface of the internal insulation layer 1-4 and the drive line layer 1-2.

[0080] After coating the insulating ink layer 1-5, windowing processes such as laser / etching / cutting are used to fabricate insulating layer grooves 1-3 in it, for exposing the surface of the boss structure 1-1 and the welding positions of the drive line layer 1-2 corresponding to the chip pads, for solder printing, chip positioning and chip fixing during the power module processing, preventing chip offset during sintering / welding, and solving the problem of high-precision welding of the gate pads on the chip surface.

[0081] The sintered solder layer 3-4 preferably uses nano silver or nano copper materials. Nano silver or nano copper sintering has the advantages of low-temperature sintering and high-temperature service, and at the same time has more excellent thermal conductivity and electrical conductivity compared to conventional solder pastes. Especially for high-power modules, in application scenarios with higher requirements for chip heat dissipation and module current-carrying capacity. The thermal expansion coefficients of nano silver or nano copper are close to those of the boss structure 1-1 and the drive line layer 1-2, so the thermal stress between materials is lower than that of other types of solders, further improving the reliability of module packaging.

[0082] The inter-board insulation filling layer 3-3 is used for electrical insulation between the upper and lower composite substrates and between the substrates and the chips, and preferably uses composite insulation materials such as epoxy resin-based, polyurethane, polyimide, parylene and silicone materials with excellent insulation performance and high temperature resistance. The filling method of the inter-board insulation filling layer 3-3 is preferably injection molding, potting, vacuum potting, etc. High-temperature vacuum potting can effectively fill the internal fine gaps, avoid the generation of air bubbles inside the module, and improve the insulation performance of the module.

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

[0084] In summary, the present invention adopts processes such as integrated heat dissipation, driving a metal core composite substrate to achieve multi-layer circuit layout of the substrate, integrated radiator and substrate, chip double-sided direct sintering process, and high-temperature vacuum potting of insulating media, etc., giving full play to the potential of the three-dimensional space multi-layer circuit layout and heat conduction ability of the composite substrate, being conducive to realizing the integration of the power module and the drive control board, and greatly simplifying the power module packaging process flow. The use of a high thermal conductivity ceramic composite thermal interface connecting material on the substrate surface significantly improves the module's insulation withstand voltage and significantly reduces the packaging thermal resistance, achieving the direct integrated integration of the external radiator and the module. The module power and signal terminals are integrated with the integrated heat dissipation and driving metal core composite substrate as a whole structure, without the need for additional welding of connecting terminals, and at the same time, the wide trace substrate frame greatly reduces the packaging parasitic parameters.

[0085] Therefore, the embedded double-sided direct cooling power module structure of the present invention based on an integrated heat dissipation and driving metal core composite substrate achieves extremely low packaging thermal resistance and parasitic parameters, and at the same time has the advantages of small volume, high power density, and integrated double-sided direct heat dissipation, etc., and is a solution with great development potential in the development direction 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 sheet metal core composite substrates arranged in a stacked manner, and multiple power chips arranged on the same layer between the composite substrates; wherein, The composite substrate has multiple metal sheet layers arranged side by side, with gaps maintained between adjacent surfaces and gap insulators for bonding filled in the gaps; after each metal sheet layer is connected into a whole through the gap insulator, it serves as the rigid support structure of the composite substrate; On the inner surface of each metal sheet layer, multiple boss structures are provided at intervals; a double-layer insulation structure for leveling is provided in the non-boss area, with an internal insulation layer as the lower layer and an insulating ink layer as the upper layer; the two composite substrates are arranged opposite to each other so that the boss structures correspond to each other in groups; a power chip is installed and embedded between each group of boss structures, and its two side surfaces are fixedly connected to the surfaces of the boss structures; on the metal sheet layer opposite to the power supply side of the power chip, a driving circuit layer is provided and embedded in the double-layer insulation structure; the driving circuit layer has multiple extension parts connecting the power chips, and the insulating ink layer leaves a window in the power supply area of the power chip so that the driving circuit layer and the power chip can be electrically connected; 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 for bonding is provided in the cavity; The outer surface of the composite substrate has an external insulation layer that simultaneously covers each metal sheet layer, and a heat sink is provided on the outside of the external insulation 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 multiple driving circuits arranged in a stacked manner and insulating layers for electrical isolation; Between the driving circuit in the lower layer and the power supply area of the driving circuit or power chip in the upper layer, electrical connection is achieved through blind holes or metal connection blocks.

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 supply side of the power chip, the driving circuit layer is located on the same composite substrate or on two composite substrates respectively.

4. The embedded double-sided direct cooling power module structure according to claim 1, wherein The power chip is fixedly connected to the boss structures on its two sides through a sintered solder layer; the power supply area of the power chip is electrically connected to the driving circuit layer through a sintered solder layer.

5. The embedded double-sided direct cooling power module structure according to claim 1, wherein A metal connection layer is provided on the surface of the external insulation layer, and the bottom surface of the heat sink is connected to the metal connection layer through a sintered solder layer; or a silicone grease heat conduction layer is provided between the metal connection layer and the bottom surface of the heat sink, and the heat sink is fixed on the composite substrate by using a fixture.

6. The embedded double-sided direct cooling power module structure according to claim 1, wherein The external insulation layer and the bottom surface of the heat sink are connected by a hot pressing method; or, a silicone grease heat conduction layer is provided between the external insulation layer and the bottom surface of the heat sink, and the heat sink is fixed on the composite substrate by using a fixture.

7. The embedded double-sided direct cooling power module structure according to claim 1, characterized in that, An extension part 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 an installation 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 part of the driving circuit layer and the bottom metal is provided as a signal terminal.

9. The manufacturing method of the embedded double-sided direct cooling power module structure based on the metal core composite substrate according to claim 1, characterized in that, It includes: By using electroplating, etching or deposition processes, boss structures are formed on the inner surface of the metal sheet layer to make them an integral structure; A plurality of metal sheet layers are arranged side by side in a mold with a gap maintained between adjacent surfaces. A hot pressing, sintering, spraying or deposition process is used to fill the gap with an insulator, forming electrical insulation between the metal sheet layers and at the same time forming a rigid integral structure; A hot pressing, sintering, spraying or deposition process is used to form an external insulation layer on the outer surface of the metal sheet layer for forming electrical insulation of the metal sheet layer to the outside; or further, an electroless plating, electroplating, deposition or hot pressing process is used to form a metal connection layer on the surface of the external insulation layer; A hot pressing process is used to cover the non-boss area of the metal sheet layer with an internal insulation layer; a photolithography, electroless plating, deposition or evaporation process is used to fabricate a metal circuit on the surface of the internal insulation layer to form a drive circuit layer; A spraying or brushing process is used to cover the surface of the internal insulation layer and the drive circuit layer with an insulating ink layer; the surface of the metal sheet layer has a sandwich structure at the position where there is a drive circuit layer and a double-layer structure at the position where there is no drive circuit layer; A laser, etching or cutting process is used to perform a windowing process on the insulating ink layer according to the installation position of the power chip to form an insulating layer groove, exposing the surface of the boss structure and the welding position on the drive circuit layer corresponding to the power chip power connection area for chip positioning and solder printing; A printing process is used to arrange solder in the insulating layer groove, and a power chip is placed; after two composite substrates are placed opposite each other and pressed together, a welding or sintering process is used to firmly bond the solder; An injection molding or potting process is used to fill the cavity between the composite substrates with an insulating material to form an insulating filling layer that firmly bonds the two composite substrates; A hot pressing process is used to mount a heat sink on the external insulation layer, or a welding process is used to mount a heat sink on the metal connection layer; or, a silicone grease heat conduction layer is coated on the outside of the composite substrate, and a clamp is used to fix the heat sink on the composite substrate.

10. The method according to claim 9, wherein, 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 insulation layer is a thermally conductive ceramic composite insulating material containing aluminum nitride, silicon nitride or silicon carbide; the internal insulation layer is a glass fiber composite material; the material of the drive 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 further, an anti-oxidation layer made of nano-scale metal nickel or gold is provided on the surface of the metal connection layer.

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