Power module

Abstract

The embodiment of the utility model relates to the technical field of semiconductors, and discloses a power module. The power module comprises a substrate, a chip and a metal sheet. The chip is arranged on the substrate and is electrically connected with the substrate; the metal sheet is arranged on the front face of the chip and electrically connected with the chip, the metal sheet is provided with a bending structure, and the bending height ranges from 200 micrometers to 800 micrometers; and the metal sheet is provided with a pin terminal for conducting a signal of the chip to external equipment. According to the power module provided by the embodiment of the invention, the influence of thermal stress released when the power module works and emits heat is reduced, so that the service life of the power module is prolonged, and the high reliability requirement of the module is met.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of semiconductor, in particular to a power module. BACKGROUND

[0002] The power module refers to the module used to achieve certain electrical function in electronic equipment, usually including power semiconductor devices, substrates, lead frames and other components, which form a modular structure in the process of plastic packaging, so as to facilitate installation and maintenance. Different power modules have different functions, some power modules can convert the input electric energy into the required output electric energy; some power modules can adjust and control the power supply to ensure stable and reliable output electric energy; some power modules have overload protection, overvoltage protection, short circuit protection and other functions, which can protect electronic equipment and power supply system from damage; some power modules have signal processing function, which can filter, amplify, modulate and process the input signal to meet the specific requirements of the equipment on electric energy; some power modules can dynamically adjust according to the actual load to improve energy utilization and reduce energy consumption. Because of the simplicity and versatility of power module, it is widely used in on-board charger (OBC), uninterruptible power supply (UPS), power conversion system (PCS), photovoltaic power optimizer, photovoltaic inverter, white goods and other products.

[0003] In the existing power module, the wires between the chips or between the chip and the circuit layer of the substrate are connected by bonding wires. The power module connected by the bonding wires has small current cross-sectional area, easy aging and peeling of solder joints, and high stray inductance. In order to solve the problems caused by the bonding wire connection, a new type of power module using copper block instead of bonding wire appears, but because the thermal expansion coefficient of copper block metal does not match the thermal expansion coefficient of chip, when the module works and generates heat, thermal stress will be released, and the chip will be crushed by the copper block, thereby shortening the service life of the module and failing to meet the requirement of high reliability. CONTENT OF THE INVENTION

[0004] The purpose of the embodiment of the present application is to provide a power module, which prolongs the service life of the module and meets the requirement of high reliability.

[0005] To solve the above technical problems, the embodiment of the present application provides a power module, which comprises a substrate, a chip and a metal sheet. The chip is arranged on the substrate and electrically connected with the substrate; the metal sheet is arranged on the front surface of the chip and electrically connected with the chip, and the metal sheet has a bending structure with a bending height of 200-800um; the metal sheet has a pin terminal for conducting the signal of the chip to an external device.

[0006] The power module provided by the embodiments of the present application replaces the traditional bonding wire connection with the electrical connection between the metal sheet and the chip, increases the overcurrent capacity and heat conduction capacity of the power module, and reduces the stray inductance. In addition, the metal sheet has a bending structure with a bending height of 200-800 um, which reduces the influence of the thermal stress released by the power module during operation and heat generation, thereby prolonging the service life of the power module and meeting the high reliability requirement of the module.

[0007] In some embodiments, the metal sheet is provided with a plurality of small holes, and the small holes include a plurality of first small holes penetrating through the side of the bending structure away from the chip.

[0008] In some embodiments, the small holes further include a plurality of second small holes recessed inward along the outer surface of the metal sheet, and the recessed depth is less than the thickness of the metal sheet.

[0009] In some embodiments, the size of the small holes is at least the thickness of the metal sheet and at most 2 / 3 of the width of the metal sheet.

[0010] In some embodiments, the metal sheet has a plurality of metal sheets connected into a whole through a connecting rib, and the chip also has a plurality of chips.

[0011] In some embodiments, the power module further includes a plurality of pins, and part of the pins are connected with the pin terminals, and another part of the pins are connected with the substrate.

[0012] In some embodiments, the power module further includes a plastic package, and the plastic package covers part of the substrate, all of the chips, all of the metal sheets, and part of the pins.

[0013] In some embodiments, the substrate includes, in sequence from the direction away from the chip, a circuit board, an insulating plate, and a metal plate.

[0014] In some embodiments, the side of the metal plate away from the chip is flush with the surface of the plastic package.

[0015] In some embodiments, the chip is fixed on the substrate by solder, sintering material, or conductive glue. BRIEF DESCRIPTION OF DRAWINGS

[0016] One or more embodiments are illustrated by way of example in the figures that form a part of this patent document, these example are not intended to limit the embodiments, elements having the same reference numbers in the figures indicate like elements, unless otherwise specifically noted, the figures in the drawings are not to scale.

[0017] Figure 1 is a side view of the power module provided by some embodiments of the present application;

[0018] Figure 2Fig. 1 is a schematic diagram of a perspective structure of a power module according to some embodiments of the present application;

[0019] Figure 3 Fig. 2 is a schematic diagram of a front structure of a power module according to some embodiments of the present application.

[0020] Fig. 1 is a schematic diagram of a perspective structure of a power module according to some embodiments of the present application; DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments. The division of the following embodiments is for the convenience of description, and should not constitute any limitation on the specific embodiments of the present application. The embodiments can be combined and referenced with each other without contradiction.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the description and the claims of this application and the above description of drawings, the terms "comprise" and "have" and any variations thereof, are intended to cover not exclusively include.

[0023] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0024] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connection" and other terms should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0025] A power module refers to a module used to achieve certain electrical functions in electronic devices, usually including power semiconductor devices, substrates, lead frames and other components. These components form a modular structure during the molding process to facilitate installation and maintenance. Different power modules have different functions. Some power modules can convert input electrical energy into the required output electrical energy; some power modules can regulate and control the power supply to ensure stable and reliable output electrical energy; some power modules have overload protection, overvoltage protection, short circuit protection and other functions to protect electronic devices and power systems from damage; some power modules have signal processing functions, which can filter, amplify, modulate and process input signals to meet the specific requirements of the device for electrical energy; some power modules can dynamically adjust according to the actual load to improve energy utilization and reduce energy consumption. Due to the simplicity and versatility of power modules, they are widely used in on-board chargers (OBC), uninterruptible power supplies (UPS), power conversion systems (PCS), photovoltaic power optimizers, photovoltaic inverters, white goods and other products.

[0026] In existing power modules, the lines between chips and chips or between chips and substrate layers are connected using bonding wires. The module connected by the bonding wire method has a small cross-sectional area of the current, the solder joint is prone to aging and peeling, and the stray inductance is large. In order to solve the problems caused by the bonding wire connection, a new type of power module using a copper block instead of a bonding wire appears, but since the thermal expansion coefficient of the copper block metal does not match the thermal expansion coefficient of the chip, when the module is working and generating heat, thermal stress will be released, the chip will be crushed by the copper block, thereby shortening the service life of the module and failing to meet the high reliability requirements.

[0027] In order to solve the problem that the current through the small cross-sectional area of the existing power module, the solder joint is easy to peel off, the stray inductance is more, and the module life is limited, which cannot meet the requirement of high reliability. Some embodiments of the present application provide a power module, which uses metal sheet and chip electrical connection instead of traditional bonding wire connection, increases the overcurrent capacity and heat dissipation capacity of the power module, and reduces the stray inductance. And the metal sheet has a bending structure, the bending height is between 200um-800um, which reduces the influence of the thermal stress released by the power module when working and heating, thereby prolonging the service life of the power module and meeting the high reliability requirement of the module.

[0028] The power module provided by some embodiments of the present application will be described below in combination with Figure 1 、 Figure 2 and Figure 3 .

[0029] As shown in Figure 1 , the power module provided by some embodiments of the present application includes a substrate 11, a chip 12 and a metal sheet 13. The chip 12 is arranged on the substrate 11 and electrically connected with the substrate 11; the metal sheet 13 is arranged on the front surface of the chip 12 and electrically connected with the chip 12, and the metal sheet 13 has a bending structure 131 with a bending height of 200um-800um; the metal sheet 13 has a pin terminal 132 for conducting signals of the chip 12 to an external device.

[0030] Specifically, the substrate 11 can be a functional substrate 11 with insulation, heat dissipation and patterned circuit layer, such as DBC (Direct Bonded Copper), DBA (Direct Bonded Aluminum), AMB (Active Metal Brazing), etc. The DBC includes Al2O3 material (alumina ceramic), the DBC of ZTA material (zirconia toughened alumina ceramic), the AMB of AlN material (aluminum nitride ceramic), the AMB of Si3N4 material (silicon nitride ceramic), etc. The substrate 11 is arranged so that an insulating sheet does not need to be placed between the heat sinks when the system is installed, which can reduce a layer of heat-conducting silicone grease. The chip 12 is fixed on the substrate 11 and electrically connected with the circuit layer of the substrate 11, and the metal sheet 13 is fixed on the front surface of the chip 12, which can indirectly realize the electrical connection with the circuit layer of the substrate 11 through the metal sheet 13. The chip 12 is responsible for processing and controlling various data and signals, so that the device can operate normally and realize specific functions.

[0031] Furthermore, the metal sheet 13 extends directly from the upper surface of the chip 12 to the side to form a pin terminal 132. The metal sheet 13 acts as a lead frame, and the pin terminal 132 can connect to the pin 14 or be used as a signal terminal to directly connect to peripherals. During the molding process of connecting the pin 14, the entire metal sheet 13 is encapsulated inside. When used as a signal terminal, the side of the metal sheet 13 is exposed outside the molding body 15. The substrate 11 can be a single-layer board or a multi-layer board. In the case of a single-layer board, the substrate 11 is completely encapsulated inside the molding body 15, and the electrical signal is isolated by the molding body 15. In the case of a multi-layer board, the side of the substrate 11 away from the chip 12 can be exposed outside the molding body 15, which provides better heat dissipation.

[0032] The power module provided in the embodiments of this application uses an electrical connection between a metal sheet 13 and a chip 12, replacing the traditional bonding wire connection. This increases the power module's overcurrent capacity and heat dissipation, improving its suitability for high-current and high-temperature applications. Furthermore, power cycle testing of the module enhances its lifespan and reduces stray inductance. Figure 2 and Figure 3 As shown, because the cross-sectional area of ​​the metal sheet 13 is larger than that of the bonding wire, it can carry a larger current, and the solder joint is stronger. The shorter length of the metal sheet 13 compared to the bonding wire reduces stray inductance and lowers the internal resistance introduced by the molding process. Furthermore, the upward bending structure 131 in the middle of the metal sheet 13, with a bending height between 200µm and 800µm, reduces the impact of thermal stress released during power module operation, thereby extending the power module's lifespan and meeting the module's high reliability requirements.

[0033] In some embodiments of this application, the metal sheet 13 is provided with a plurality of small holes 133, the small holes 133 including a plurality of first small holes 1331, the first small holes 1331 penetrating the side of the bent structure 131 opposite to the chip 12.

[0034] It should be noted that the coefficient of thermal expansion of the metal sheet 13 does not match that of the silicon carbide chip 12. When the module generates heat during operation, it releases thermal stress, causing the metal sheet 13 to compress the chip 12 and damage its internal structure. Therefore, drilling small holes 133 of appropriate size and density on the metal sheet 13 is beneficial for releasing the stress after the metal sheet is heated, protecting the chip 12, and also reduces the weight of the module. The small holes 133 can be round or square. The first small hole 1331 on the bent structure 131 penetrates the metal sheet 13, which can fully release the stress after the metal sheet 13 is heated.

[0035] In some embodiments of this application, the small hole 133 further includes a plurality of second small holes 1332, which are recessed inward along the outer surface of the metal sheet 13, and the depth of the recess is less than the thickness of the metal sheet 13.

[0036] That is to say, the small holes 133 include two kinds, one is the first small hole 1331 on the bending structure 131, which penetrates the metal sheet 13, and this kind of small hole 133 can fully release the stress of the metal sheet 13 after being heated. The second small hole 1332 is arranged on the part of the metal sheet 13 directly mounted with the chip 12, and this kind of small hole 133 does not penetrate the metal sheet 13, and the depth of the small hole 133 is less than the thickness of the metal sheet 13. Because, if the small hole 133 arranged at this part penetrates the metal sheet 13, the soldering material will overflow along the small hole 133, affecting the quality of soldering.

[0037] In some embodiments of the present application, the size of the small hole 133 is at least the thickness of the metal sheet 13, and at most 2 / 3 of the width of the metal sheet 13.

[0038] It should be noted that the size of the small hole 133 should not be too large or too small, too small cannot play the role of releasing pressure, and too large will affect the stability of the structure and the metal sheet 13 is easy to break. The thickness of the metal sheet 13 is much smaller than the width of the metal sheet 13.

[0039] In some embodiments of the present application, the metal sheet 13 has multiple, and the multiple metal sheets 13 are connected into a whole through the connecting rib 134, and the chip 12 also has multiple.

[0040] It should be noted that at this time the chip 12 also has multiple, and the multiple metal sheets 13 are fixed on different chips 12 respectively to realize more functions. The connecting rib 134 is made of the same material as the metal sheet 13, and can be made by one-piece forming process with the metal sheet 13 during the production of the metal sheet 13. The one-piece structure of the connecting rib 134 is beneficial to installation and ensures the flatness when the metal sheet 13 is fixed. The material of the metal sheet 13 can be copper or aluminum. Copper and aluminum are common conductive materials due to their excellent conductivity. And because of their strong plasticity, they can be made into metal sheets 13 of various thicknesses, and it is also convenient to punch holes on the metal sheet 13.

[0041] In some embodiments of the present application, the power module further includes multiple pins 14, part of the pins 14 are connected with the pin terminals 132, and another part of the pins 14 are connected with the substrate 11.

[0042] It should be noted that the number of pins 14 can be 8-24, such as Figure 3 As shown, the number of pins 14 is preferably 12, 6 pins 14 are connected with the pin terminals 132 on the metal sheet 13, and 6 pins 14 are connected with the circuit layer on the substrate 11. The specific number of pins 14 is determined according to the function, cost budget and application scene of the power module, and 12 pins 14 can meet the needs of general scenes.

[0043] In some embodiments of the present application, the power module further comprises a plastic package 15, which covers part of the substrate 11, all of the chip 12, all of the metal sheet 13, and part of the pin 14.

[0044] It should be noted that the substrate 11, the chip 12, the metal sheet 13, and part of each pin 14 are connected and fixed according to the designed position to form a to-be-plastic package 15, and the to-be-plastic package 15 is placed in a plastic package mold, and after pouring epoxy resin, a power module structure is formed. The pin 14 extends from the side of the plastic package 15 and can be externally connected to a device to transmit signals. In addition, replacing the traditional bonding wire with the metal sheet 13 can reduce the plastic package internal resistance of the power module during plastic package. The metal sheet 13 is connected to the upper surface of the chip 12 and directly drawn out from the side of the plastic package 15 as a power terminal, which is equivalent to a lead frame. The shape of the plastic package 15 can be SOP (Small Outline Package), DIP (Dual-In-Line Package), SOJ (Small Outline J-lead Package), etc.

[0045] In some embodiments of the present application, the substrate 11 comprises, in order from the direction away from the chip 12, a circuit board 111, an insulating plate 112, and a metal plate 113.

[0046] It should be noted that the substrate 11 comprises, in order from the top to the bottom direction, the circuit board 111 at the upper end, the insulating plate 112 in the middle, and the metal plate 113 at the lower end. Figure 1 The middle of the substrate 11 is an insulating ceramic layer, and the circuit board 111 and the metal plate 113 on both sides can be made of metals such as copper and aluminum. The metal plate 113 has a heat dissipation function, and the metal plate 113 is exposed to the plastic package 15 to dissipate the heat generated by the chip 12 to the surrounding environment. The circuit board 111 has the function of fixing the chip 12 and the pin 14, and the circuit layer on the circuit board 111 electrically connects the chip 12 and the pin 14 to transmit signals.

[0047] In some embodiments of the present application, the metal plate 113 is flush with the surface of the plastic package 15 away from the chip 12.

[0048] It should be noted that the metal plate 113 is flush with the surface of the plastic package 15 away from the chip 12, that is, the outer surface of the metal plate 113 is exposed outside the plastic package 15. On the one hand, it can better conduct the heat generated by the chip 12 from the circuit board 111, the insulating plate 112, and the metal plate 113 in order and finally dissipate to the surrounding environment, increasing the heat dissipation effect of the power module. On the other hand, it ensures the appearance of the entire power module.

[0049] In some embodiments of the present application, the chip 12 is fixed on the substrate 11 by solder, sintering material or conductive glue.

[0050] It should be noted that the solder, sintering material or conductive glue are all conventional methods for fixing the chip 12 on the substrate 11, which can adapt to the existing production process and facilitate production.

[0051] Those skilled in the art can understand that the above-mentioned embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A power module, characterized by The application relates to a chip package, comprising: a substrate; a chip arranged on the substrate and electrically connected to the substrate; a metal sheet arranged on the front surface of the chip and electrically connected to the chip, the metal sheet having a bending structure with a bending height of 200-800 um; the metal sheet has pin terminals for transmitting signals of the chip to external devices.

2. The power module of claim 1, wherein, The metal sheet is provided with a plurality of small holes, the small holes comprising a plurality of first small holes penetrating through the side of the bending structure away from the chip.

3. The power module of claim 2, wherein, The small holes further comprise a plurality of second small holes recessed inward along the outer surface of the metal sheet, the recessed depth being less than the thickness of the metal sheet.

4. The power module of claim 3, wherein, The size of the small holes is the minimum thickness of the metal sheet and the maximum is not more than 2 / 3 of the width of the metal sheet.

5. The power module of claim 1, wherein, There are a plurality of metal sheets, and the metal sheets are connected into a whole through connecting ribs, and there are a plurality of chips.

6. The power module of claim 5, wherein, Further comprising a plurality of pins, part of the pins being connected to the pin terminals and another part of the pins being connected to the substrate.

7. The power module of claim 6, wherein, Further comprising a plastic package, the plastic package covering part of the substrate, all of the chips, all of the metal sheets and part of the pins.

8. The power module of claim 7, wherein, The substrate comprises a circuit board, an insulating plate and a metal plate in sequence away from the chip.

9. The power module of claim 8, wherein, The side of the metal plate away from the chip is flush with the surface of the plastic package.

10. The power module of claim 1, wherein, The chip is fixed on the substrate through solder, sintered material or conductive glue.

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