Power module

Abstract

The present invention discloses a power module, which relates to the field of semiconductor technology and includes: a printed circuit board having a first surface for mounting electronic components and a second surface corresponding to the first surface; a first driving chip mounted on the first surface of the printed circuit board; a first gallium nitride power device mounted on the second surface of the printed circuit board, and the position of the first gallium nitride power device is opposite to the position of the first driving chip; a copper-clad ceramic substrate disposed on a surface of the first gallium nitride power device facing away from the printed circuit board; and a packaging plastic for packaging the printed circuit board, the first driving chip, the first gallium nitride power device, and the copper-clad ceramic substrate, and a surface of the copper-clad ceramic substrate facing away from the first gallium nitride power device is exposed from the packaging plastic. This application can effectively reduce parasitic parameters, improve the power conversion efficiency, and increase the power density of the overall module.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a power module. Background Art

[0002] Gallium nitride is known as a representative material of the third-generation semiconductor. In power devices, compared with silicon devices, gallium nitride devices can achieve high-frequency (up to 500KHz - 1MHz) and extremely low-loss switching under high voltage, reduce the cost of the entire power supply system, improve the conversion efficiency, and have higher power density, smaller volume, and better heat dissipation performance. In the field of medium and low-power adapters, gallium nitride-based adapters have been mass-produced, and it is expected to completely replace silicon in some fields in the near future. Discrete gallium nitride drivers pose new challenges to PCB layout because the switching speed of gallium nitride is very fast, and the parasitic parameters of the externally added drive circuit inevitably cause voltage and current oscillations, increasing switching losses and even damaging the device.

[0003] Currently, gallium nitride power devices mainly come in two forms: discrete components and monolithic integrated ICs with drivers. Traditional silicon power modules usually consist of IGBTs plus fast-recovery diodes. Due to the limitations of materials and device structures, they cannot achieve high-frequency and high-efficiency electrical energy control and conversion. Summary of the Invention

[0004] For existing discrete gallium nitride devices, special and relatively long wirings are required on the PCB board, and these wirings will inevitably introduce a large amount of parasitic inductance. At the same time, because each device and driver requires independent packaging, the cost is high, and the occupied circuit board area is large. Even for gallium nitride modules, they are based on wire bonding (copper wires, gold wires, aluminum wires, etc.) designs. The wire bonding itself will bring parasitic inductance and resistance, and the maximum current that can flow through it will also be limited by the thickness and number of the wire bonds.

[0005] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a power module that can effectively reduce parasitic parameters, improve the electrical energy conversion efficiency, and increase the power density of the overall module.

[0006] The specific technical solution of the embodiments of the present invention is as follows:

[0007] A power module, the power module includes:

[0008] A printed circuit board having a first side for mounting electronic components and a second side corresponding to the first side;

[0009] A first driving chip mounted on the first side of the printed circuit board;

[0010] The first gallium nitride power device is mounted on the second surface of the printed circuit board, and the position of the first gallium nitride power device is opposite to the position of the first driving chip;

[0011] The copper-clad ceramic substrate is disposed on the surface of the first gallium nitride power device facing away from the printed circuit board;

[0012] The encapsulation plastic is used to encapsulate the printed circuit board, the first driving chip, the first gallium nitride power device, and the copper-clad ceramic substrate, and the surface of the copper-clad ceramic substrate facing away from the first gallium nitride power device is exposed from the encapsulation plastic.

[0013] Preferably, the interior of the printed circuit board has ceramics extending in the horizontal direction.

[0014] Preferably, the copper-clad ceramic substrate and the first gallium nitride power device are connected by silver sintering or copper sintering to form a first silver sintered layer or a first copper sintered layer.

[0015] Preferably, the first driving chip is a silicon driving chip.

[0016] Preferably, the encapsulation plastic covers the printed circuit board, the first driving chip, the first gallium nitride power device, and the surface of the copper-clad ceramic substrate facing the first gallium nitride power device.

[0017] Preferably, the first gallium nitride power device and the first driving chip are electrically connected by means of routing inside the printed circuit board.

[0018] Preferably, the power module further includes:

[0019] The second driving chip is mounted on the first surface of the printed circuit board;

[0020] The second gallium nitride power device is mounted on the second surface of the printed circuit board, and the position of the second gallium nitride power device is opposite to the position of the second driving chip;

[0021] The copper-clad ceramic substrate is disposed on the surface of the second gallium nitride power device facing away from the printed circuit board.

[0022] Preferably, the copper-clad ceramic substrate and the second gallium nitride power device are connected by silver sintering or copper sintering to form a second silver sintered layer or a second copper sintered layer.

[0023] Preferably, the second gallium nitride power device and the second driving chip are electrically connected by means of routing inside the printed circuit board.

[0024] Preferably, the encapsulation plastic covers the second driving chip and the second gallium nitride power device.

[0025] The technical solution of the present invention has the following remarkable beneficial effects:

[0026] In the present invention, the first driving chip and the first gallium nitride power device are respectively installed on the first side and the second side of the printed circuit board, and their positions are opposite to each other and electrically connected through the internal wiring method of the printed circuit board. The connection distance between the first driving chip and the first gallium nitride power device is minimized to the greatest extent. The connection line is extremely short, and the parasitic inductance brought is extremely small. It can greatly reduce the parasitic parameters brought by the wiring. At the same time, the first driving chip and the first gallium nitride power device are co-encapsulated in the same module through the encapsulation plastic, avoiding the need for wire bonding between the two, which greatly reduces the parasitic parameters again and effectively improves the power conversion efficiency, making the parasitic inductance brought by the co-encapsulation comparable to that of gallium nitride monolithic integration, and also avoiding the disadvantages of single function and high cost of gallium nitride monolithic integration itself. In addition, due to the installation layout of the first driving chip and the first gallium nitride power device, the width of the printed circuit board in the horizontal direction is greatly reduced, making the layout of each component on the entire power module more compact and closer, so that the power density of the entire module can be greatly improved.

[0027] Referring to the following description and the accompanying drawings, specific embodiments of the present invention are disclosed in detail, indicating the ways in which the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope thereby. Within the spirit and terms of the appended claims, the embodiments of the present invention include many changes, modifications, and equivalents. Features described and / or illustrated for one embodiment can be used in the same or similar way in one or more other embodiments, combined with features in other embodiments, or replace features in other embodiments. Description of the Drawings

[0028] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to assist in understanding the present invention, rather than specifically limiting the shapes and proportional dimensions of the components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions according to specific circumstances to implement the present invention under the teaching of the present invention.

[0029] Figure 1 It is a schematic structural diagram of the first embodiment of the power module in the embodiment of the present invention;

[0030] Figure 2 It is a sectional view of the first embodiment of the power module in the embodiment of the present invention;

[0031] Figure 3 This is a schematic structural diagram of the second implementation mode of the power module in the embodiments of the present invention.

[0032] Reference numerals in the above drawings:

[0033] 1. Printed circuit board; 11. First surface; 12. Second surface; 2. First drive chip; 3. First gallium nitride power device; 4. Copper-clad ceramic substrate; 5. Encapsulation plastic; 6. First silver sintering layer or first copper sintering layer; 7. Second drive chip; 8. Second gallium nitride power device; 9. Second silver sintering layer or second copper sintering layer. Specific implementation manners

[0034] Combined with the description of the specific implementation manners of the present invention and the drawings, the details of the present invention can be more clearly understood. However, the specific implementation manners of the present invention described herein are only for the purpose of explaining the present invention and cannot be construed in any way as a limitation of the present invention. Under the teaching of the present invention, those skilled in the art can conceive any possible variations based on the present invention, and all of these should be regarded as belonging to the scope of the present invention. It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, they can be mechanical connections or electrical connections, or they can be the internal communication of two elements. They can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation manner.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific implementation manners and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] In order to effectively reduce parasitic parameters, improve the power conversion efficiency, and increase the power density of the overall module, a power module is proposed in this application. Figure 1 This is a schematic structural diagram of the first implementation mode of the power module in the embodiments of the present invention. Figure 2 This is a sectional view of the first implementation mode of the power module in the embodiments of the present invention, as Figure 1 andFigure 2 As shown in the figure, the power module may include: a printed circuit board 1 having a first surface 11 for mounting electronic components and a second surface 12 corresponding to the first surface 11; a first driving chip 2 mounted on the first surface 11 of the printed circuit board 1; a first gallium nitride power device 3 mounted on the second surface 12 of the printed circuit board 1, the position of the first gallium nitride power device 3 being opposite to the position of the first driving chip 2; a copper-clad ceramic substrate 4 provided on a surface of the first gallium nitride power device 3 facing away from the printed circuit board 1; and a packaging plastic 5 for packaging the printed circuit board 1, the first driving chip 2, the first gallium nitride power device 3, and the copper-clad ceramic substrate 4, and a surface of the copper-clad ceramic substrate 4 facing away from the first gallium nitride power device 3 is exposed from the packaging plastic 5.

[0037] As Figure 1 shown in the figure, the printed circuit board 1 is a double-sided printed circuit board 1 having a first surface 11 and a second surface 12 corresponding to the first surface 11, and electronic components can be mounted on both the first surface 11 and the second surface 12.

[0038] In a feasible implementation manner, the interior of the printed circuit board 1 has ceramics extending in the horizontal direction. The ceramics inside the printed circuit board 1 are non-conductive and are good conductors of heat, which can effectively improve the heat transfer effect of the entire printed circuit board 1. It can quickly and evenly disperse the heat at a certain local part of the printed circuit board 1 to all parts of the entire printed circuit board 1, making the interior of the printed circuit board 1 uniformly heated. In particular, it can transfer the heat on one surface of the printed circuit board 1 to the other surface, so that each part can achieve the purpose of efficient heat dissipation, and can effectively reduce the temperature of the printed circuit board.

[0039] As Figure 1 shown in the figure, the first driving chip 2 is mounted on the first surface 11 of the printed circuit board 1. The first driving chip 2 has gold bumps and is welded to the printed circuit board 1 through the gold bumps. The first driving chip 2 can be a silicon driving chip or a gallium nitride driving chip, and preferably a silicon driving chip. In this application, the first driving chip 2 is a BGA or LGA package driving chip.

[0040] In this application, the gallium nitride (GaN) drive chip can be implemented in a GaN monolithic integration manner. In some GaN processes, the same process can be used to implement integrated resistors, capacitors, diodes, and low-voltage analog active devices. Such a process makes it possible to monolithically integrate GaN analog drive chips and power devices. However, compared with silicon drive chips, the real advantages of GaN drive chips lie in their high breakdown electric field, lower on-resistance, lower parasitic capacitance, etc. However, in terms of integration, there are disadvantages such as the lack of P-type devices and high costs. Silicon drive chips manufactured using silicon integrated circuit (BCD) processes can provide smaller feature sizes, which can reach 0.18 μm or smaller, lower costs, and more comprehensive protection functions, and are the preferred choice for drive chips of GaN power devices.

[0041] As Figure 1 shown, the first GaN power device 3 is mounted on the second side 12 of the printed circuit board 1, and the position of the first GaN power device 3 is opposite to the position of the first drive chip 2. The first GaN power device 3 and the first drive chip 2 are electrically connected by means of internal wiring inside the printed circuit board 1, and the internal wiring can be connected by metal wires or copper pillars, etc. In this application, the first GaN power device 3 is a GaN power device with an LGA package.

[0042] The first GaN power device 3 can be depletion, normally-on type, or enhancement, normally-off type, and the difference lies in the positive and negative values of the threshold voltage. The preparation of GaN power devices starts from the substrate. For cost considerations, most existing GaN power devices use silicon as the substrate material. The wafer size is generally 6 inches or 8 inches. The GaN epitaxial technology determines the performance of the device. Currently, the mainstream enhancement-mode GaN power devices use P-type GaN technology to achieve a positive threshold voltage. However, the P-type GaN layer is similar to a P / N junction diode, and there will be a relatively high leakage current under the condition of the forward voltage drop at the gate level. Therefore, it is not suitable to use too high a gate voltage. The maximum gate voltage of GaN power devices is currently 5V to 7V. The relatively low voltage cannot cooperate with existing ordinary drive chips and requires a dedicated drive chip that matches the GaN power device.

[0043] When using a silicon drive circuit as the drive circuit for a gallium nitride power device, the connection problem between the silicon drive circuit and the gallium nitride power device is inevitably involved. Traditionally, there are two ways: One is that the gallium nitride power device and the silicon drive circuit are two different chips with their own packages respectively. In applications, the layout wiring of the printed circuit board 1 is used to realize the connection between the chips. In this way, since the wiring on the printed circuit board 1 will bring parasitic inductance, causing circuit oscillation and thus reducing efficiency. The second way is the so-called co-packaging mode, that is, the gallium nitride power device and the drive circuit are arranged side by side and co-packaged in a plastic package, and wire bonding is used to connect between the chips. Since the connection wires are shorter in this way, the parasitic inductance brought is relatively small, which can reduce the parasitic parameters brought by the wiring. However, even so, since wire bonding still needs to be used between the gallium nitride power device and the drive circuit, the parasitic inductance of the co-packaging mode is still not as small as that of the gallium nitride monolithic integration.

[0044] As Figure 1 shown, the copper-clad ceramic substrate 4 is disposed on the side of the first gallium nitride power device 3 facing away from the printed circuit board 1, that is to say, the copper-clad ceramic substrate 4 is disposed below the first gallium nitride power device 3. The heat dissipated by the first drive chip 2 is first transferred to the printed circuit board 1, and then transferred to the first gallium nitride power device 3. Then, the heat dissipated by the first gallium nitride power device 3 itself and the heat transferred from the printed circuit board 1 to the first gallium nitride power device 3 are both transferred downward to the copper-clad ceramic substrate 4, and then dissipated outward through the copper-clad ceramic substrate 4. The copper-clad ceramic substrate 4 has a good heat dissipation effect, and it can have a good heat conduction performance with the first gallium nitride power device 3. At the same time, the lower part of the copper-clad ceramic substrate 4 also needs to be used as an electrode for connection and power supply with other components.

[0045] Preferably, the copper-clad ceramic substrate 4 and the first gallium nitride power device 3 can be connected by silver sintering or copper sintering to form a first silver sintering layer or a first copper sintering layer 6. Of course, the copper-clad ceramic substrate 4 and the first gallium nitride power device 3 can also be connected in other ways, such as silver glue connection. However, silver sintering or copper sintering has better thermal conductivity and electrical conductivity than silver glue connection.

[0046] As Figure 1As shown, the encapsulation plastic 5 is used to encapsulate the printed circuit board 1, the first driving chip 2, the first gallium nitride power device 3, and the copper-clad ceramic substrate 4. The encapsulation plastic 5 covers one side of the printed circuit board 1, the first driving chip 2, the first gallium nitride power device 3, and the copper-clad ceramic substrate 4 facing the first gallium nitride power device 3, so that one side of the copper-clad ceramic substrate 4 facing away from the first gallium nitride power device 3 is exposed from the encapsulation plastic 5. Epoxy resin can be preferentially selected as the encapsulation plastic 5. In this way, sufficient heat exchange can be formed with the outside through the side of the copper-clad ceramic substrate 4 facing away from the first gallium nitride power device 3, so as to achieve the purpose of heat dissipation of the copper-clad ceramic substrate 4 and reduce the temperatures of the encapsulated printed circuit board 1, the first driving chip 2, and the first gallium nitride power device 3.

[0047] In the present invention, the first driving chip 2 and the first gallium nitride power device 3 are respectively installed on the first surface 11 and the second surface 12 of the printed circuit board 1, and their positions are opposite to each other. Electrical connection is achieved through the internal wiring of the printed circuit board 1, which minimizes the connection distance between the first driving chip 2 and the first gallium nitride power device 3. The connection line is extremely short, and the parasitic inductance brought is extremely small, which can greatly reduce the parasitic parameters brought by the wiring. At the same time, the first driving chip 2 and the first gallium nitride power device 3 are co-encapsulated in the same module through the encapsulation plastic 5, avoiding the need for wire bonding between the two, which greatly reduces the parasitic parameters and effectively improves the power conversion efficiency, making the parasitic inductance brought by the co-encapsulation comparable to that of a gallium nitride monolithic integration, and also avoiding the disadvantages of single function and high cost of gallium nitride monolithic integration itself. In addition, due to the installation layout of the first driving chip 2 and the first gallium nitride power device 3, the width of the printed circuit board 1 in the horizontal direction is greatly reduced, making the layout of each component on the entire power module more compact and tighter, thus greatly improving the power density of the entire module.

[0048] In a feasible implementation manner, Figure 2 is a schematic structural diagram of the second implementation manner of the power module in the embodiment of the present invention. As Figure 2 shown, the power module may further include: a second driving chip 7 installed on the first surface 11 of the printed circuit board 1; a second gallium nitride power device 8 installed on the second surface 12 of the printed circuit board 1, and the position of the second gallium nitride power device 8 is opposite to the position of the second driving chip 7; the copper-clad ceramic substrate 4 is disposed on one side of the second gallium nitride power device 8 facing away from the printed circuit board 1.

[0049] As Figure 2As shown, similarly, the copper-clad ceramic substrate 4 and the second gallium nitride power device 8 are connected by silver sintering or copper sintering to form a second silver sintering layer or a second copper sintering layer 9. The second gallium nitride power device 8 and the second driving chip 7 are electrically connected by routing inside the printed circuit board 1. The encapsulation plastic 5 covers the second driving chip 7 and the second gallium nitride power device 8.

[0050] In the above manner, it is possible to satisfy the arrangement of the driving chip and the gallium nitride power device according to the half-bridge topology structure. Each gallium nitride power device can be connected to its corresponding driving chip through routing inside the printed circuit board 1. In this way, the parasitic parameters will not increase due to the setting of multiple gallium nitride power devices and driving chips. Moreover, in this way, it is still possible to make the layout of each component on the entire power module compact and tight, which can effectively and significantly improve the power density of the entire module.

[0051] By connecting the first gallium nitride power device 3 and the second gallium nitride power device 8 to the same copper-clad ceramic substrate 4 at the same time, in this way, the heat generated when each gallium nitride power device and its corresponding driving chip work can be transferred to the entire large-area copper-clad ceramic substrate 4, which helps to improve the heat dissipation effect.

[0052] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for various purposes. The term "consisting essentially of" describing a combination should include the identified elements, components, parts or steps and other elements, components, parts or steps that do not substantially affect the basic novel features of the combination. The use of the terms "comprising" or "including" to describe the combination of elements, components, parts or steps herein also contemplates embodiments consisting essentially of these elements, components, parts or steps. Here, by using the term "may", it is intended to indicate that any attribute described as "may" included is optional. Multiple elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step can be divided into separate multiple elements, components, parts or steps. The disclosure of "a" or "an" used to describe an element, component, part or step does not mean to exclude other elements, components, parts or steps.

[0053] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts among the embodiments can be referred to each other. The above embodiments are only for explaining the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, but it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A power module, characterized in that, The power module includes: A printed circuit board having a first side for mounting electronic components and a second side corresponding to the first side; A first drive chip mounted on the first side of the printed circuit board; A first gallium nitride power device mounted on the second side of the printed circuit board, the position of the first gallium nitride power device being opposite to the position of the first drive chip; A copper-clad ceramic substrate provided on a side of the first gallium nitride power device facing away from the printed circuit board; A packaging plastic for encapsulating the printed circuit board, the first drive chip, the first gallium nitride power device, and the copper-clad ceramic substrate, and a side of the copper-clad ceramic substrate facing away from the first gallium nitride power device is exposed from the packaging plastic; The first gallium nitride power device and the first drive chip are electrically connected by a wiring method inside the printed circuit board; Wherein, the first drive chip is a silicon drive chip; The power module further includes: A second drive chip mounted on the first side of the printed circuit board; A second gallium nitride power device mounted on the second side of the printed circuit board, the position of the second gallium nitride power device being opposite to the position of the second drive chip; The copper-clad ceramic substrate is provided on a side of the second gallium nitride power device facing away from the printed circuit board.

2. The power module according to claim 1, characterized in that, The interior of the printed circuit board has ceramics extending in the horizontal direction.

3. The power module according to claim 1, wherein The copper-clad ceramic substrate and the first gallium nitride power device are connected by silver sintering or copper sintering to form a first silver sintered layer or a first copper sintered layer.

4. The power module according to claim 1, characterized in that, The packaging plastic covers the printed circuit board, the first drive chip, the first gallium nitride power device, and a side of the copper-clad ceramic substrate facing the first gallium nitride power device.

5. The power module according to claim 1, characterized in that, The copper-clad ceramic substrate and the second gallium nitride power device are connected by silver sintering or copper sintering to form a second silver sintered layer or a second copper sintered layer.

6. The power module according to claim 1, characterized in that The second gallium nitride power device and the second drive chip are electrically connected by a wiring method inside the printed circuit board.

7. The power module according to claim 1, characterized in that, The packaging plastic covers the second drive chip and the second gallium nitride power device.

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