A laminated power module and a method of manufacturing

Abstract

The application discloses a laminated power module and a preparation method, and relates to the field of semiconductors. The power module comprises a metal radiator and circuit boards which are sequentially stacked above the metal radiator. The function conduction between the circuit boards is realized by arranging conductive columns and conductive vias. The following conditions should be met: a, the conductive columns are fixed on the input end and / or the output end of the bottom circuit board to realize the function conduction between the upper and lower circuit boards; b, the conductive vias are arranged above the conductive columns, and the loop length is the shortest after the function conduction; and c, the conductive columns are vertically fixed on the bottom circuit board after welding by a mold, so that the upper ends of the conductive columns can be assembled into the conductive vias. The application adopts an innovative conductive column direct connection structure design and positioning design, and solves the problems of large module size, poor integration, complicated preparation process, difficult accurate assembly, long loop, large parasitic inductance, high voltage peak and large electromagnetic radiation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a laminated power module and a preparation method, and is especially suitable for use in a welding machine. BACKGROUND

[0002] A power module is a module in which semiconductor devices are combined according to certain functions. Power modules can realize different functions such as rectification and inversion according to different packaged semiconductor components. Since the function switching is convenient, stable and reliable, power modules are widely used in various inverter power supply scenes such as welding machines that require power conversion.

[0003] In the prior art, there are many related technologies involving power modules, including the following:

[0004] For example, the document with publication number CN119383933A discloses an inverter power supply. The inverter power supply directly fixes the power module on the copper-plated layer of the aluminum heat sink, which can utilize the aluminum heat sink as the load output of the power module and effectively improve the heat dissipation effect. Generally, the power circuit in the power module needs to be configured with a driving circuit on a circuit board to control and drive the power circuit to operate normally when the power circuit is working. However, the circuit board carrying the driving circuit is installed on the side of the aluminum heat sink in actual application, and the two are connected by welding metal wires. After careful analysis, it is found that since the driving circuit still belongs to part of the power module, the inverter power supply fails to further integrate the circuit board carrying the driving circuit and the power module, resulting in a large overall volume and a long loop length of the power module, which not only leads to poor integration of the power module, but also leads to large parasitic inductance of the power module loop, high voltage spikes, and large electromagnetic radiation. In addition, the connection between the two through the welding of metal wires causes the problems of difficulty in aligning the metal wires and the welding points, inconvenience in mechanical and intelligent welding, and easy occurrence of virtual welding and build-up welding due to the softness and thinness of the metal wires and the small size of the welding points.

[0005] For example, the document with publication number CN113346713A discloses a discrete device and a power module package, which includes a cooler, a power unit and a driving unit arranged in parallel in three layers of lower, middle and upper. The discrete device in the power unit includes a positive power terminal, a negative power terminal, a control signal terminal and a protective power terminal. The positive power terminal and the negative power terminal are welded on the power unit circuit substrate. The control signal terminal and the protective power terminal are insulated through the insulating hole of the power unit circuit substrate and then welded on the driving circuit board of the driving unit. The package discloses a scheme in which the chip on one layer of circuit board is welded with another circuit board through a pin. However, after careful analysis, it is found that the technology is to package each discrete device (chip) first and then integrate with other circuits into one. It needs to package each discrete device separately first, and then integrate the whole through the circuit board. This makes the power module a device-level packaging and integration structure, which has the problems of complex structure and complicated preparation process. In addition, since each discrete device involves multiple pin terminals, and each discrete device is connected with the signal connection terminal on the driving unit through the pin terminal, not only the circuit position layout on each unit is limited, but also the circuit loop is long, which leads to the problems of large volume, large loop parasitic inductance, high voltage spike and large electromagnetic radiation.

[0006] In addition, the prior art also discloses a connection structure between two circuit boards using a plug and a socket, such as the document with publication number CN215268898U which discloses a plug-in PCB board structure. However, this kind of connection structure needs to process plug and socket on two circuit boards respectively, and in order to facilitate installation, a support seat for adapting the plug pin and the socket hole on the two circuit boards needs to be designed between the two circuit boards. Therefore, the plug and the socket have the problems of complex preparation process on the circuit board, high material cost and production cost. In addition, the socket has a large volume, the plug has a small diameter and is easy to bend and deform, which also has the problems of large area occupation on the circuit board, difficulty in making the power module more miniaturized and difficulty in assembly.

[0007] However, the prior art does not find a direct connection method between the circuit boards through the column and the through hole. Therefore, it is necessary to provide a new technology to solve the above technical problems. SUMMARY

[0008] The present application is directed to the technical problems of the prior art power module, such as large size, poor integration, complicated preparation process, difficult to accurately realize mechanical intelligent welding, poor welding effect, large parasitic inductance, high voltage spike and large electromagnetic radiation caused by long loop, and provides a laminated power module and a preparation method. First, the present application adopts an innovative conductive column direct connection structure design based on the laminated structure, which can realize the functional conduction of the upper and lower circuit boards by using the conductive column and the conductive via, so that the power module realizes chip-level integration. It can not only effectively simplify the structure of the power module and improve the integration, but also reduce the number of pin terminals and maximize the length of the loop, thereby effectively reducing the loop parasitic inductance, voltage spike and electromagnetic radiation of the power module. Secondly, the present application can keep the conductive columns vertical during assembly and sintering by mold positioning, so that each conductive column can be smoothly assembled into each conductive via, avoiding the bending of any conductive column which leads to the failure of assembly. In addition, mechanical intelligent welding can be used during assembly to avoid virtual welding and build-up welding, thereby improving the stability and reliability of welding.

[0009] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0010] A laminated power module, comprising a metal heat sink, a circuit board is sequentially stacked above the metal heat sink, and the functional conduction between the circuit boards is realized by arranging a plurality of conductive columns and a plurality of conductive vias between at least two or more circuit boards, and the following technical requirements should be met:

[0011] a. The lower end of the conductive column is fixed to the input and / or output end of the bottom layer circuit board, and the minimum distance between adjacent conductive columns is 2.2mm, so as to meet the functional conduction between the upper and lower circuit boards;

[0012] b. The conductive via is arranged above the conductive column, and the loop length is the shortest after the functional conduction of the upper and lower circuit boards;

[0013] c. The bottom layer circuit board is limited on the lower mold, and the tin paste is fixed on the position of the conductive column on the bottom layer circuit board; the conductive column is automatically inserted into the positioning hole of the upper mold by using the pin machine, and the lower end of the conductive column is limited by the detachable limiting baffle; the upper mold and the lower mold are combined by using the positioning pin and the positioning hole, and after the combination, the limiting baffle is pulled out, so that the lower end of the conductive column falls into the tin paste position on the bottom layer circuit board; the mold is sent into the welding equipment, and after welding, the conductive column is vertically fixed on the bottom layer circuit board, so as to meet the requirement that the upper end of each conductive column can be correspondingly assembled into each conductive via.

[0014] The conductive column is a T-shaped structure comprising a cylindrical rod and a cylindrical cap, the cylindrical cap is welded and fixed on the bottom layer circuit board, the cylindrical rod is welded and fixed in the conductive via, and the diameter of the cylindrical rod is 1-1.2mm.

[0015] The bottom circuit board is provided with a power circuit, the upper circuit board is provided with a functional circuit, a switching wire and a plurality of power terminals, and the functional circuit and the power terminals are connected with the conductive via respectively through the switching wire; the conductive column is arranged at the input end and / or the output end of the power circuit, and the power circuit and the conductive column are integrally packaged on the bottom circuit board, and the functional circuit is realized through the conductive via and the switching wire.

[0016] The shortest loop length of the upper and lower circuit boards after the functional conduction refers to the shortest length of the switching wire between the conductive via and the functional circuit and the switching wire between the conductive via and the power terminal.

[0017] The power circuit comprises a three-phase rectifier circuit, an inverter circuit and a secondary rectifier circuit, the power input end of the three-phase rectifier circuit is electrically connected with part of the power terminals through the conductive column and the conductive via, the power output end of the three-phase rectifier circuit is electrically connected with part of the power terminals through the conductive column and the conductive via, the signal input end of the inverter circuit is electrically connected with the driving circuit through the conductive column and the conductive via, the power output end of the inverter circuit is electrically connected with part of the power terminals through the conductive column and the conductive via, and the power input end of the secondary rectifier circuit is electrically connected with part of the power terminals through the conductive column and the conductive via.

[0018] The bottom circuit board is a combination structure of a plurality of DBC circuit boards and a copper plating layer, the copper plating layer is coated on a metal heat sink, the DBC circuit boards are welded and fixed on the copper plating layer, the three-phase rectifier circuit and the inverter circuit are arranged at the lower part and the upper part of a DBC circuit board respectively, and the secondary rectifier circuit is arranged on the copper plating layer and the remaining DBC circuit boards.

[0019] The conductive column of the power input end of the three-phase rectifier circuit is located at the lower part of the DBC circuit board and arranged in a matrix, the conductive columns of the power output end of the three-phase rectifier circuit are respectively located at the middle part of the right side and the upper part of the left side of the DBC circuit board, the conductive columns of the signal input end of the inverter circuit are respectively located at the upper middle part of the left side and the upper middle part of the right side of the DBC circuit board, the conductive column of the power output end of the inverter circuit is located at the middle of the upper part of the DBC circuit board, and the conductive columns of the power input end of the secondary rectifier circuit are evenly arranged on the plurality of DBC circuit boards.

[0020] The functional circuit comprises a driving circuit, an IGBT resistance-capacitance absorption circuit and an FRD resistance-capacitance absorption circuit, the IGBT resistance-capacitance absorption circuit is connected in parallel with the three-phase rectifier circuit through the conductive column and the conductive via, the FRD resistance-capacitance absorption circuit is connected in parallel with the secondary rectifier circuit through the conductive column and the conductive via, and the conductive column of the power output end of the three-phase rectifier circuit and the conductive column of the power output end of the inverter circuit are shared between the IGBT resistance-capacitance absorption circuit and the three-phase rectifier circuit, and the conductive columns between the FRD resistance-capacitance absorption circuit and the secondary rectifier circuit are symmetrically arranged on the copper plating layer.

[0021] The upper layer circuit board comprises one PCB circuit board or two PCB circuit boards stacked above the bottom layer circuit board, when the upper layer circuit board comprises one PCB circuit board, the driving circuit, the IGBT resistance-capacitance absorption circuit and the FRD resistance-capacitance absorption circuit are arranged on the PCB circuit board; when the upper layer circuit board comprises two PCB circuit boards, the driving circuit is arranged on one of the PCB circuit boards, the IGBT resistance-capacitance absorption circuit, the FRD resistance-capacitance absorption circuit and the power terminal are arranged on the other PCB circuit board, and the PCB circuit board on which the driving circuit is arranged is above the other PCB circuit board.

[0022] The IGBT resistance-capacitance absorption circuit and the FRD resistance-capacitance absorption circuit are arranged on two PCB circuit boards respectively, the two PCB circuit boards are of the same height and are above the inverter circuit and the secondary rectifier circuit respectively.

[0023] The metal heat sink is fixed with an insulating shell, the bottom layer circuit board, the power circuit and the conductive column are integrally packaged in the insulating shell by a vacuum filling process, the upper part of the insulating shell is provided with positioning grooves on both sides for fixing the power terminal, and the positioning grooves are provided with counterbores, and the counterbores are provided with nuts; the power terminal is an L-shaped copper bar fixed on the upper layer circuit board by welding, one end of each L-shaped copper bar is arranged on the side of the upper layer circuit board, and the other end of each L-shaped copper bar is fixed in the positioning groove by a bolt and a nut and is electrically connected with an external device.

[0024] A preparation method of a stacked power module, comprising designing according to the conduction requirement and heat dissipation requirement of the power module, combining the circuit boards needed to be stacked on the metal heat sink, and determining the layout of the conductive column and the conductive via between the circuit boards to meet the following requirements:

[0025] a. The lower end of the conductive column is fixed to the input end and / or the output end of the bottom layer circuit board, and the minimum distance between adjacent conductive columns is 2.2 mm to meet the functional conduction between the upper and lower circuit boards;

[0026] b. The conductive via is arranged directly above the conductive column to meet the shortest loop length after the functional conduction of the upper and lower circuit boards;

[0027] Based on the above requirements, the preparation method comprises the following steps:

[0028] Step 1, limit the bottom layer circuit board on the lower mold, fix the tin paste on the positions corresponding to the conductive column and the positions corresponding to the power circuit on the bottom layer circuit board, and place the power circuit on the corresponding tin paste; use a pin machine to automatically insert the conductive column into the positioning hole of the upper mold, and use a detachable limiting baffle to limit the lower end of the conductive column;

[0029] Step 2, the upper die and the lower die are closed by using the positioning pin and the positioning hole, the limiting baffle is pulled out after the closing, and the lower ends of the conductive columns fall into the tin paste positions corresponding to the fixed conductive columns on the bottom circuit board respectively;

[0030] Step 3, the mold is sent into a welding device, a vacuum reflow welding process is adopted to weld and fix the power circuit and the conductive columns on the bottom circuit board, and the bottom circuit board is taken out after the welding is completed;

[0031] Step 4, a copper plating layer is coated on the metal radiator, the bottom circuit board is welded and fixed on the copper plating layer, the insulating shell is fixed on the copper plating layer, and a vacuum filling process is adopted to package the bottom circuit board, the power circuit and the lower ends of the conductive columns in the insulating shell.

[0032] Step 5, a correction plate is arranged, the correction plate is provided with a plurality of conical countersunk correction holes corresponding to the conductive columns, the conductive columns are sleeved into the conical countersunk correction holes for correction, and the conductive columns are always kept vertical.

[0033] Step 6, an upper circuit board is arranged, the upper circuit board is provided with a functional circuit, a switching lead and a conductive via hole corresponding to the conductive column, the functional circuit is connected with the conductive via hole through the switching lead, the upper circuit board is moved by an intelligent manipulator to make the conductive via hole correspond to the conductive column, the upper circuit board is controlled to move downwards until the upper ends of all the conductive columns are assembled into the corresponding conductive via holes, and the upper and lower circuit boards are stacked.

[0034] Step 7, the conductive columns and the conductive via holes are welded, the upper and lower circuit boards can be functionally conducted through the conductive columns and the conductive via holes, and the preparation is completed.

[0035] In step 3, the welding conditions of the vacuum reflow welding process are as follows: preheating 100-150 DEG C, temperature rising rate 2-3 DEG C / s, solder reflow temperature 217-227 DEG C, oxygen content < 5ppm during welding, and holding for 30-90 seconds after welding.

[0036] In step 4, the specific process of the vacuum filling process is as follows: the insulating shell and the bottom circuit board are put into a filling mold, air is exhausted after vacuumizing to-0.1 Mpa, then Shore 00-30 hardness silicon gel is injected to fill the gap in the insulating shell and cover the bottom circuit board, the power circuit and the lower ends of the conductive columns, and the vacuum filling is completed after solidification.

[0037] Compared with the prior art, the beneficial effects of the present application are as follows:

[0038] 1. The power module provided by this invention adopts a stacked circuit board structure and an innovative direct-connection structure for conductive pillars. By meeting technical requirements a and b, the positions of conductive pillars, conductive vias, and related circuits can be arranged according to the principle of minimizing the loop length after functional activation to achieve functional activation. During implementation, the layout of circuits and components can be completed in advance before the conductive pillars are uniformly brought out, enabling chip-level integration of the power module, thereby effectively reducing its size and increasing integration density. Furthermore, based on this chip-level integrated power module, the conductive pillars can be brought out after overall layout, reducing the number of pin terminals and simplifying the structure and fabrication process of the power module. In addition, the minimum spacing between adjacent conductive pillars is 2.2mm. This ensures insulation performance while meeting safety regulations, facilitates effective fixing of the conductive pillars to the circuit board, and further reduces the overall size of the power module. Conversely, a spacing larger than 2.2mm will increase the size of the power module, while a spacing smaller than 2.2mm will compromise insulation performance and hinder mechanized fabrication. Correspondingly, due to the reduction in the size of the power module and the shortest circuit length, the parasitic inductance, voltage spikes, and electromagnetic radiation of the power module can be fundamentally reduced.

[0039] It should be noted that due to the large number of conductive posts and their typically small diameter, they are prone to bending during welding and assembly. Even a single bent conductive post will lead to assembly failure. Therefore, this invention, through technical requirement c, ensures that the conductive posts remain vertical throughout the welding and assembly process, preventing bending. This allows multiple conductive posts to be simultaneously installed into each conductive via, ensuring accurate assembly and improving assembly efficiency. Furthermore, the coordinated use of these technical requirements facilitates several benefits. First, the hard contact between the posts and vias makes welding easier. During power module fabrication, it also allows for automated, top-to-bottom alignment of the conductive vias with the conductive posts for welding. This facilitates intelligent mechanical operation, precise positioning, and avoids incomplete soldering and weld buildup, reducing abnormal resistance increases caused by poor contact, ensuring circuit stability, extending the power module's lifespan, and improving production efficiency. Second, the fixed structure of the conductive posts and vias provides stable support for the upper circuit board, further enhancing the stability and reliability of the connections between circuit boards, reducing the risk of connection failure, and ensuring circuit stability. In addition, it reduces the reliance on large amounts of metal wire and lowers the complexity of the bonding process and production costs associated with metal wire bonding.

[0040] 2、The application is beneficial to reduce electromagnetic radiation of high-frequency signals in the transmission process on the basis of ensuring the shortest loop length and smaller volume, and the conductive column and the circuit board itself can be part of the shielding structure, which reduces the signal interference between the circuit boards. This makes the power module have less electromagnetic influence on the surrounding circuit when working, which is beneficial to improve the electromagnetic compatibility of the entire device and reduces the need for additional shielding measures.

[0041] 3、The conductive column of the application adopts a T-shaped structure including a cylindrical rod and a cylindrical cap, which increases the contact area between the conductive column and the bottom circuit board through the cylindrical cap, and improves the welding firmness of the conductive column and the bottom circuit board. Through the cylindrical rod matched with the conductive via, a stable and reliable welding structure can be formed between the two, ensuring the stability and reliability of the circuit transmission. The diameter of the conductive column is 1-1.2mm, which can ensure sufficient structural strength of the conductive column under the premise of appropriate cost, so as to facilitate assembly with the conductive via.

[0042] 4、The length of the adapter wire between the conductive via and the functional circuit and between the conductive via and the power terminal is designed to be the shortest, so that the power module with the shortest loop length after the function is turned on can be obtained, which is beneficial to reduce the volume of the power module and shorten the loop length. In addition, through the cooperation of the power terminal with the conductive column and the conductive via, it is also beneficial to build a current transmission path with the shortest loop length but high efficiency.

[0043] 5、The three-phase rectifier circuit, the inverter circuit and the secondary rectifier circuit on the bottom circuit board and the drive circuit, the IGBT resistance-capacitance absorption circuit and the FRD resistance-capacitance absorption circuit on the upper circuit board can be connected respectively through the cooperation of the conductive column and the conductive via, and the IGBT resistance-capacitance absorption circuit and the three-phase rectifier circuit can share the conductive column of the three-phase rectifier circuit power output end and the conductive column of the inverter circuit power output end, which is beneficial to reduce the number of conductive columns and make the power module smaller in volume and shorter in loop length. The parallel design of the IGBT resistance-capacitance absorption circuit and the FRD resistance-capacitance absorption circuit with the inverter circuit and the secondary rectifier circuit respectively is beneficial to precisely suppress voltage fluctuation in the circuit and improve power conversion efficiency.

[0044] 6、The application can make the power module smaller in volume and shorter in loop length on the basis of sharing the conductive column through the regional layout of the conductive column on the bottom circuit board. In addition, the regional arrangement of each conductive column also has the advantages of facilitating preparation and forming stable support for the upper circuit board as a whole.

[0045] 7. The upper circuit board of this invention may include one PCB circuit board or two PCB circuit boards. When using one PCB circuit board, the power module has a higher integration and smaller size; when using two PCB circuit boards, the power module has a slightly lower integration, but it is easier to disassemble and maintain. In addition, when there are two PCB circuit boards, by further dividing the PCB circuit board where the RC snubber circuit is set into two parts and using them to set the IGBT RC snubber circuit and the FRD RC snubber circuit respectively, compared with setting the RC snubber circuit on the whole PCB circuit board, it is possible to further reduce the PCB circuit board area while ensuring the shortest loop length, and it is also easier to disassemble and maintain the IGBT RC snubber circuit and the FRD RC snubber circuit separately.

[0046] 8. This invention uses vacuum potting to fix the bottom circuit board, power circuit, and conductive pillars within an insulating shell, effectively isolating the internal circuitry from external dust and moisture, thus extending the lifespan of the power module.

[0047] 9. The present invention places the power terminals on both sides of the upper circuit board. Combined with the fixing structure of positioning groove and bolt, it not only facilitates quick docking with external devices and avoids loosening of the connection due to vibration, but also strengthens and fixes the upper circuit board.

[0048] 10. The preparation method of the present invention is simple and easy to implement, and can be intelligently produced by machinery. It has strong promotion and replicability, and the power module obtained has the corresponding advantages mentioned above, which will not be repeated here.

[0049] 11. The present invention employs specific welding conditions in the vacuum reflow soldering process, which has the advantage of improving the welding yield of conductive pillars, and is conducive to improving the pass rate of power modules and ensuring the stable and reliable conduction effect of power modules.

[0050] 12. The present invention employs a specific vacuum potting process, which is beneficial to improving the overall protection performance and stability of the power module. Attached Figure Description

[0051] Figure 1 This is a three-dimensional structural diagram of the present invention when it includes two circuit boards;

[0052] Figure 2 This is a three-dimensional structural diagram of the present invention when it includes a three-layer circuit board;

[0053] Figure 3 This is a planar structural diagram of the three-phase rectifier circuit and inverter circuit on the bottom circuit board.

[0054] Figure 4 This is a planar structural diagram of the secondary rectifier circuit on the bottom circuit board.

[0055] Figure 5 Fig. 1 is a schematic diagram of the structure of the bottom circuit board on the lower mold;

[0056] Figure 6 Fig. 1 is a schematic diagram of the structure of the bottom circuit board on the lower mold;

[0057] Figure 7 Fig. 1 is a schematic diagram of the structure of the bottom circuit board on the lower mold.

[0058] Fig. 1 is a schematic diagram of the structure of the bottom circuit board on the lower mold. DETAILED DESCRIPTION

[0059] Example 1

[0060] As shown in Figure 1 , Figure 2 , the present embodiment provides a laminated power module, which comprises a metal heat sink 15, which can be a finned aluminum heat sink with one side provided with fins and the other side provided with a flat surface. The circuit board is sequentially stacked above the metal heat sink 15. The key is that the function of the circuit boards is conducted through the arrangement of a plurality of conductive columns 4 and a plurality of conductive vias 5 between the at least two layers of circuit boards, and the following technical requirements should be met:

[0061] a. The lower end of the conductive column 4 is fixed to the input end and / or output end of the bottom circuit board 1, and the minimum distance between adjacent conductive columns 4 is 2.2 mm, so as to meet the functional conduction between the upper and lower circuit boards.

[0062] b. The conductive via 5 is arranged on the upper circuit board 2, and the conductive via 5 is arranged directly above the conductive column 4, so as to meet the shortest loop length after the functional conduction of the upper and lower circuit boards.

[0063] c, the bottom layer circuit board 1 is limited on the lower die 18, and the tin paste is applied on the bottom layer circuit board 1 corresponding to the position of the conductive column 4; the conductive column 4 is automatically inserted into the positioning hole 20 of the upper die 19 by using the pin machine, and the lower end of the conductive column 4 is limited by using the detachable limiting baffle 21; the upper die 19 and the lower die 18 are combined by using the positioning pin 23 and the positioning hole 24, the limiting baffle 21 is pulled out after the combination, the lower end of the conductive column 4 falls into the tin paste position on the bottom layer circuit board 1, the mold is sent into the welding equipment, and the conductive column 4 is vertically fixed on the bottom layer circuit board 1 after welding, so that the upper end of each conductive column 4 can be correspondingly assembled into each conductive via hole 5.

[0064] In the technical requirement a, according to the different circuits on the bottom layer circuit board 1, the number of the conductive columns 4 is multiple, and the setting mode has three kinds, which are that the conductive column 4 can be arranged at the input end of the circuit, the conductive column 4 can be arranged at the output end of the circuit, and the conductive column 4 can be arranged at the input end and the output end of the circuit.

[0065] Further, the minimum spacing between adjacent conductive columns 4 is 2.2mm, which can ensure the insulation effect between adjacent conductive columns 4 under the premise of meeting the safety distance, and can further reduce the volume of the power module as a whole.

[0066] In the technical requirement b, in addition to arranging each conductive via hole 5 above each conductive column 4, the spacing between the conductive via hole 5 and each circuit on the upper layer circuit board 2 is set to be the shortest, so that the loop length is the shortest after the upper and lower circuit boards are functionally connected.

[0067] In the technical requirement c, as Figures 5-7As shown, the upper die 19 and the lower die 18 are both graphite molds in rectangular structure, positioning holes 24 are symmetrically arranged at both ends of the die closing surface of the lower die 18, positioning pins 23 are symmetrically fixed at both ends of the die closing surface of the upper die 19, and the positioning pins 23 correspond to the positioning holes 24 one by one, and the positioning pins 23 are further provided with groove bodies, which can form sliding grooves for the sliding of the limiting baffle 21 through the cooperation of the groove bodies on the positioning pins 23 at both ends of the upper die 19. The four corners of the non-die closing surface of the upper die 19 are further respectively fixed with support columns 22, which are used to support the upper die 19 to make the die closing surface face upward when the conductive column 4 is inserted, so as to facilitate the insertion of the conductive column 4 into the positioning insertion hole 20 from above by using the pin inserting machine. The diameter of the lower end of the conductive column 4 is greater than the diameter of the column body, and the positioning insertion hole 20 is matched with the shape of the conductive column 4. The limiting baffle 21 is arranged on the upper die 19 through the sliding groove formed by the positioning pins 23 and can be pulled out of the sliding groove. After the conductive column 4 is inserted into the positioning insertion hole 20 of the upper die 19 by the pin inserting machine, the upper end of the conductive column 4 passes through the positioning insertion hole 20, but the lower end of the conductive column 4 is limited in the positioning insertion hole 20, and then the conductive column 4 is inserted into the limiting baffle 21 to block and limit the lower end of the conductive column 4. At this time, the upper die 19 is flipped arbitrarily, and the conductive column 4 will not fall off. After the positioning pins 23 and the positioning holes 24 are closed, the limiting baffle 21 is pulled out to make the lower end of the conductive column 4 fall into the corresponding tin paste position on the bottom layer circuit board 1 for welding. Through the cooperation of the upper die 19 and the lower die 18, the conductive columns 4 can always remain vertical during welding and assembly, which facilitates the smooth assembly of the conductive columns 4 into the conductive through holes 5. Usually, the limitation of several bottom layer circuit boards 1 can be realized on the same lower die 18, and correspondingly, several conductive columns 4 can be inserted into the same upper die 19 at the same time, so as to realize mass production.

[0068] As understood by those skilled in the art, the above functional conduction refers to the cooperation of the conductive column 4 and the conductive through hole 5 between the two circuit boards, which can realize functions such as power transmission, signal transmission and control logic, so as to ensure that the entire module completes the expected functions of power conversion, signal control and the like according to the design logic. In addition, the spacing between the upper and lower adjacent two layers of circuit boards needs to meet the minimum air insulation safety spacing of 6.5 mm.

[0069] In the embodiment, as shown in Figure 1 , Figure 2 The conductive column 4 is in T-shaped structure including a cylindrical rod and a cylindrical cap, the cylindrical cap is used for welding and fixing on the bottom layer circuit board 1, and the cylindrical rod is used for welding and fixing in the conductive through hole 5. The outer diameter of the cylindrical cap is greater than the outer diameter of the cylindrical rod, which can enhance the stability and reliability of the connection between the conductive column 4 and the bottom layer circuit board 1 through the cylindrical cap. The outer diameter of the cylindrical rod is slightly smaller than the outer diameter of the conductive through hole 5, which facilitates the mechanical operation of the end of the cylindrical rod through the conductive through hole 5 for assembly and welding, can avoid virtual welding and build-up welding, and improves the reliability of welding.

[0070] Further, the diameter of the conductive column 4 can range from 1 to 1.2 mm, which can ensure sufficient structural strength of the conductive column 4 to facilitate assembly with the conductive via 5 while keeping the cost appropriate. Conversely, if the diameter of the conductive column 4 is greater than 1.2 mm, the cost will be too high, and if the diameter of the conductive column 4 is less than 1 mm, the structural strength will be insufficient and the conductive column 4 will be easily bent and unable to be assembled with the corresponding conductive via 5. Of course, the diameter of the conductive column 4 can also be increased accordingly according to some special scenarios that require large current.

[0071] In the present embodiment, the power circuit is arranged on the bottom circuit board 1, the functional circuit, the adapter wire (a copper wire prearranged for conducting electricity), and the plurality of power terminals 6 are arranged on the upper circuit board 2, the functional circuit and the power terminals 6 are respectively connected with the conductive via 5 through the adapter wire, the conductive column 4 is arranged at the input end and / or the output end of the power circuit, and the power circuit and the conductive column 4 are integrally packaged on the bottom circuit board 1, and then the functional circuit is realized through the conductive via 5 and the adapter wire.

[0072] Further, in technical requirement b, the shortest loop length after the functional conduction of the upper and lower circuit boards refers to the shortest length of the adapter wire between the conductive via 5 and the functional circuit and the shortest length of the adapter wire between the conductive via 5 and the power terminal 6, so that the loop length of the power module can be shortened.

[0073] The present embodiment does not limit the power circuit and the functional circuit on the circuit board, and those skilled in the art can arrange the required circuit on the circuit board according to the actual working condition. In summary, through the limitation of technical requirements a-c, the power module can realize chip-level integration, and the functional conduction can be realized by using the conductive column 4 and the conductive via 5, so as to achieve the effects of reducing the volume, improving the integration, simplifying the structure, simplifying the preparation process, facilitating assembly, facilitating mechanical and intelligent welding, improving the welding effect, shortening the loop length, reducing the parasitic inductance, reducing the voltage peak, and reducing the electromagnetic radiation.

[0074] Embodiment 2

[0075] The present embodiment further optimizes the structure of the power module based on embodiment 1.

[0076] In the present embodiment, as Figure 1 , Figure 2DBC circuit boards 17 and copper plating layers 16, the copper plating layers 16 are coated on the metal heat sinks 15, the DBC circuit boards 17 are welded and fixed on the copper plating layers 16, and the power circuit and the conductive columns 4 are arranged on the copper plating layers 16 and the DBC circuit boards 17 respectively. The structure of the bottom circuit board 1 sharing the copper plating layers 16 with the heat sinks is adopted, so that the material can be saved and the heat dissipation effect can be improved. Of course, according to some special functional requirements, the bottom circuit board 1 can also be all DBC circuit boards 17 or other similar circuit boards.

[0077] In the embodiment, as shown in the figure, Figures 1-4 The power circuit includes a three-phase rectifier circuit 10, an inverter circuit 11 and a secondary rectifier circuit 12, and the conductive columns 4 are arranged at the power input end of the three-phase rectifier circuit 10, the power output end of the three-phase rectifier circuit 10, the signal input end of the inverter circuit 11, the power output end of the inverter circuit 11 and the power input end of the secondary rectifier circuit 12 respectively. The three-phase rectifier circuit 10 and the inverter circuit 11 are arranged at the lower part and the upper part of a DBC circuit board 17 respectively, and according to actual working conditions, the three-phase rectifier circuit 10 and the inverter circuit 11 can also be arranged on two DBC circuit boards 17 arranged in an up-down manner respectively. The secondary rectifier circuit 12 is arranged on the copper plating layer 16 and the remaining DBC circuit boards 17 respectively. Specifically, the secondary rectifier circuit 12 includes a chip and a copper connecting piece, the lower surface of the chip is directly welded and fixed on the copper plating layer 16, one end of the copper connecting piece is welded and fixed on the upper surface of the chip, and the other end is welded and fixed on the DBC circuit board 17. At this time, the current generated by the chip can flow to the metal heat sink 15 through the copper plating layer 16, and then the metal heat sink 15 is used as the current output of the secondary rectifier circuit 12.

[0078] Further, the conductive columns 4 at the power input end of the three-phase rectifier circuit 10 are arranged in a matrix at the lower part of the DBC circuit board 17, the conductive columns 4 at the power output end of the three-phase rectifier circuit 10 are arranged at the middle part of the right side and the upper part of the left side of the DBC circuit board 17 respectively, the conductive columns 4 at the signal input end of the inverter circuit 11 are arranged at the upper middle part of the left side and the upper middle part of the right side of the DBC circuit board 17 respectively, the conductive column 4 at the power output end of the inverter circuit 11 is arranged at the middle of the upper part of the DBC circuit board 17, and the conductive columns 4 at the power input end of the secondary rectifier circuit 12 are evenly arranged on the plurality of DBC circuit boards 17. Through the sub-regional layout of the conductive columns 4 on the bottom circuit board 1, the module volume can be smaller and the loop length can be shorter, and the upper circuit board 2 can be stably supported as a whole.

[0079] Further, the functional circuit includes the driving circuit 13, the IGBT resistance-capacitance absorption circuit 3 and the FRD resistance-capacitance absorption circuit 14, and the specific connection relationship between the power circuit and the functional circuit is that the power input end of the three-phase rectifier circuit 10 is electrically connected with part of the power terminal 6 through the conductive column 4 and the conductive via 5, the power output end of the three-phase rectifier circuit 10 (the power input end of the inverter circuit 11) is electrically connected with part of the power terminal 6 through the conductive column 4 and the conductive via 5, the signal input end of the inverter circuit 11 is electrically connected with the driving circuit 13 through the conductive column 4 and the conductive via 5, the power output end of the inverter circuit 11 is electrically connected with part of the power terminal 6 through the conductive column 4 and the conductive via 5, and the power input end of the secondary rectifier circuit 12 is electrically connected with part of the power terminal 6 through the conductive column 4 and the conductive via 5. The IGBT resistance-capacitance absorption circuit 3 is connected in parallel with the three-phase rectifier circuit 10 through the conductive column 4 and the conductive via 5, the FRD resistance-capacitance absorption circuit 14 is connected in parallel with the secondary rectifier circuit 12 through the conductive column 4 and the conductive via 5, and the conductive column 4 of the power output end of the three-phase rectifier circuit 10 and the conductive column 4 of the power output end of the inverter circuit 11 are shared between the IGBT resistance-capacitance absorption circuit 3 and the three-phase rectifier circuit 10, and the conductive column 4 between the FRD resistance-capacitance absorption circuit 14 and the secondary rectifier circuit 12 is symmetrically arranged on the copper plating layer 16. By sharing the conductive column 4, the number of conductive columns 4 is reduced, the cost is reduced, and the volume of the power module is reduced.

[0080] It should be noted that the specific circuit structure of the three-phase rectifier circuit 10, the inverter circuit 11, the secondary rectifier circuit 12, the driving circuit 13 and the resistance-capacitance absorption circuit in the embodiment and the connection mode therebetween are all conventional technologies, for example, the three-phase rectifier circuit 10 includes multiple rectifier diode chips and corresponding copper tabs, the inverter circuit 11 includes multiple IGBT chips and corresponding copper tabs, and the secondary rectifier circuit 12 includes multiple FRD chips and corresponding copper tabs.

[0081] The power terminals 6 in the embodiment can be set according to the specific circuit, and based on the specific circuit, the number of the power terminals 6 can be 11. Among them, 3 power terminals 6 can be used as the power input terminals of the three-phase rectifier circuit 10, 2 power terminals 6 can be used as the power output terminals of the inverter circuit 11, 2 power terminals 6 can be used as the power input terminals for external capacitors, and the two power input terminals for external capacitors are connected to the power output terminals of the three-phase rectifier circuit 10 (the power input terminals of the inverter circuit 11) through the conductive columns 4, and the last 4 power terminals 6 can be used as the power input terminals of the secondary rectifier circuit 12. Correspondingly, the three-phase rectifier circuit 10 is electrically connected with 5 power terminals 6 (including 3 power input terminals of the three-phase rectifier circuit 10 and 2 power output terminals for external capacitors) through the conductive columns 4 and the conductive vias 5, the inverter circuit 11 is electrically connected with 2 power terminals 6 (2 power output terminals of the inverter circuit 11) through the conductive columns 4 and the conductive vias 5, and the secondary rectifier circuit 12 is electrically connected with 4 power terminals 6 (4 power input terminals of the secondary rectifier circuit 12) through the conductive columns 4 and the conductive vias 5.

[0082] In the embodiment, the number of the conductive columns 4 of the power input terminals of the three-phase rectifier circuit 10 can be 9, 12 or 16, etc., the number of the conductive columns 4 from the power output terminals of the three-phase rectifier circuit 10 to the external capacitors can be 4 or 8, etc., the number of the conductive columns 4 between the driving circuit 13 and the signal input terminals of the inverter circuit 11 can be 3, 4, 7 or 8, etc., the number of the conductive columns 4 between the IGBT resistance-capacitance absorption circuit 3 and the inverter circuit 11 is 2n, n is a natural number, and the number of the conductive columns 4 between the FRD resistance-capacitance absorption circuit 14 and the secondary rectifier circuit 12 is 2n, n is a natural number. Of course, according to the different current and the different connection mode of each circuit, the number of the conductive columns 4 can also be increased or decreased accordingly.

[0083] Figure 3A circuit structure diagram of a three-phase rectifier circuit 10 and an inverter circuit 11 on a bottom circuit board 1 is shown, from which it can be known that the number of conductive posts 4 at the power input end of the three-phase rectifier circuit 10 is 9 (located at the lower part of the DBC circuit board 17 and arranged in a 3*3 matrix), the number of conductive posts 4 at the power output end of the three-phase rectifier circuit 10 (the power input end of the inverter circuit 11) to the conductive posts 4 for external capacitors is 8 (of which 4 are located at the right middle part of the DBC circuit board 17 and arranged vertically, and the other 4 are located at the upper left side and arranged in a 2*2 matrix), the number of conductive posts 4 at the signal input end of the inverter circuit 11 is 7 (of which 4 are located at the upper middle part of the left side of the DBC circuit board 17 and arranged in a 2*2 matrix, and the other 3 are located at the upper middle part of the right side and arranged in a triangle), and the number of conductive posts 4 at the power output end of the inverter circuit 11 is 8 (located at the upper middle part of the DBC circuit board 17 and arranged vertically). The number of conductive posts 4 between the IGBT resistance-capacitance absorption circuit 3 and the inverter circuit 11 is 16, which are shared with the conductive posts 4 between other circuits. Specifically, the IGBT resistance-capacitance absorption circuit 3 is divided into four paths, and each IGBT resistance-capacitance absorption circuit 3 is connected in parallel with four IGBT chips of the inverter circuit 11, and the four IGBT resistance-capacitance absorption circuits 3 share 16 conductive posts 4 with the power input end (the power output end of the three-phase rectifier circuit 10) and the power output end of the inverter circuit 11.

[0084] Figure 4 A circuit structure diagram of a secondary rectifier circuit 12 on a copper plating layer 16 is shown, from which it can be known that the number of conductive posts 4 on the secondary rectifier circuit 12 is 48, of which 44 conductive posts 4 are used for electrical connection with four power terminals 6 (four power input ends of the secondary rectifier circuit 12), and the other four conductive posts 4 are connected with the FRD resistance-capacitance absorption circuit 14.

[0085] In this embodiment, as Figure 1 , Figure 2As shown, the upper circuit board 2 can be a structure comprising one PCB circuit board, or a structure comprising two PCB circuit boards stacked on top of the lower circuit board 1. When the upper circuit board 2 comprises one PCB circuit board, the drive circuit 13, the IGBT RC snubber circuit 3, and the FRD RC snubber circuit 14 are all disposed on this PCB circuit board; when the upper circuit board 2 comprises two PCB circuit boards, the drive circuit 13 is disposed on one of the PCB circuit boards, and the IGBT RC snubber circuit 3, the FRD RC snubber circuit 14, and the power terminal 6 are disposed on the other PCB circuit board, with the PCB circuit board containing the drive circuit 13 located above the other PCB circuit board. Typically, there is a certain distance between the three-phase rectifier circuit 10 and the secondary rectifier circuit 12, and the area of ​​the PCB circuit board containing the RC snubber circuit is larger than the area of ​​the PCB circuit board containing the drive circuit 13. To improve the stability of the circuit board after fixing and to facilitate the subsequent disassembly and replacement of the drive circuit 13, it is preferable that the PCB circuit board containing the drive circuit 13 is located above the other PCB circuit board. Of course, without considering the aforementioned requirements, the PCB circuit board containing the drive circuit 13 can also be located below the other PCB circuit board. In addition, while meeting the functional requirements of this embodiment, the number of PCB circuit boards included in the upper circuit board 2 can be expanded as needed.

[0086] Furthermore, such as Figure 2 As shown, the IGBT RC snubber circuit 3 and the FRD RC snubber circuit 14 are again respectively mounted on two PCB circuit boards. These two PCB circuit boards are of the same height and are located above the inverter circuit 11 and the secondary rectifier circuit 12, respectively. Compared to mounting the IGBT RC snubber circuit 3 and the FRD RC snubber circuit 14 on a single PCB circuit board, this layer uses two PCB circuit boards, which reduces material usage and PCB area while ensuring the shortest possible circuit length, and facilitates individual disassembly and maintenance.

[0087] When the upper circuit board 2 comprises two PCBs, the PCB with the RC snubber circuit is designated as the first PCB, and the PCB with the drive circuit 13 is designated as the second PCB. In this case, functional communication is achieved between the lower circuit board 1 and the first PCB, and between the lower circuit board 1 and the second PCB, through conductive posts 4 and conductive vias 5. There are two connection structures between the lower circuit board 1 and the second PCB, as follows:

[0088] The first method involves insulating the conductive post 4 on the bottom circuit board 1 through the first PCB circuit board and then soldering it into the conductive through hole 5 on the second PCB circuit board. In this case, the driving circuit 13 on the second PCB circuit board can be connected to the power circuit on the bottom circuit board 1 through this part of the conductive post 4.

[0089] The second type is to provide a conductive post 4 between the first PCB circuit board and the second PCB circuit board. The conductive post 4 can be soldered to the first PCB circuit board or the second PCB circuit board. Preferably, the conductive post 4 is soldered to the second PCB circuit board. The other end of the conductive post 4 can be soldered to the conductive through hole 5 of the first PCB circuit board. In this case, the driving circuit 13 on the second PCB circuit board can be connected to the power circuit through the conductive post 4 between the second PCB circuit board and the first PCB driving circuit 13 board, and the conductive post 4 between the first PCB driving circuit 13 board and the bottom circuit board 1.

[0090] To facilitate the fixing of the second PCB circuit board, support columns and positioning columns can be set on the first PCB circuit board, and the second PCB circuit board can be supported and fixed by corresponding screws and screw holes.

[0091] In this embodiment, as Figure 1 , Figure 2 As shown, an insulating shell 7 is also fixed to the metal heat sink 15. This insulating shell 7 can be fixed to the copper-plated layer 16 by bolts or other means. The bottom circuit board 1, power circuit, and conductive pillar 4 are all encapsulated in the insulating shell 7 using a vacuum potting process. Furthermore, positioning grooves 8 for fixing power terminals 6 are respectively opened on both sides of the upper part of the insulating shell 7. The positioning grooves 8 have polygonal countersunk holes 9, and polygonal nuts are installed in the countersunk holes 9, which can restrict the rotation of the nuts. Preferably, the power terminals 6 are L-shaped copper busbars welded and fixed to the upper circuit board 2. One end of each L-shaped copper busbar is respectively located on both sides of the upper circuit board 2, and the other end of each L-shaped copper busbar is fixed in the positioning groove 8. After placing the other end of the L-shaped copper busbar in the positioning groove 8, the L-shaped copper busbar can be fixed in the positioning groove 8 by bolts and nuts, realizing the fixation of the upper circuit board 2 and electrical connection with external devices. In addition, the L-shaped copper busbar can also cooperate with the conductive pillar 4 to achieve enhanced fixation of the upper circuit board 2, making the upper circuit board 2 more stable and vibration-resistant.

[0092] In this embodiment, during the preparation process, the mold can be used to simultaneously weld and fix each circuit and the conductive post 4 on the bottom circuit board 1. Each circuit can be prepared separately using different molds or simultaneously using the same mold. It is only necessary to design corresponding limiting areas and corresponding positioning holes 20 on the upper and lower molds.

[0093] The working principle of this embodiment is as follows:

[0094] When the power circuit is working, the external three-phase power supply is connected to the three power terminals 6 on the upper layer circuit board 2 as the power input end, and the current enters the power input end of the three-phase rectifier circuit 10 through the preset switching wire, the conductive through hole 5 and the 9 conductive columns 4, and is output to the inverter circuit 11 after being rectified by the three-phase rectifier circuit 10. At the DC output end of the three-phase rectifier circuit 10 (the power input end of the inverter circuit 11), the current is output to the two power terminals 6 for external capacitor through the 8 conductive columns 4, and the inverter circuit 11 is output to the two power terminals 6 as the power output end through the 8 conductive columns 4. The two power terminals 6 are connected to the primary of the transformer, and the secondary of the transformer is connected to the secondary rectifier circuit 12 through the four power terminals 6. The current is input to the secondary rectifier circuit 12 through the 44 conductive columns 4, and the output current of the secondary rectifier circuit 12 can be output to the load through the metal radiator 15. After receiving the external control signal, the driving circuit 13 transmits the control signal to the signal input end of the inverter circuit 11 through the 7 conductive columns 4, and drives and controls the inverter circuit 11. The IGBT resistance-capacitance absorption circuit 3 absorbs the inverter circuit 11 through the 16 conductive columns 4, and the FRD resistance-capacitance absorption circuit 14 absorbs the secondary rectifier circuit 12 through the 4 conductive columns 4, which is used to suppress the voltage fluctuation in the circuit and improve the power conversion efficiency.

[0095] The power module provided by the embodiment has the advantages of small size, high integration, simple structure and preparation process, good welding effect, short loop length, low parasitic inductance, low voltage peak and small electromagnetic radiation, and is especially suitable for welding machines.

[0096] Embodiment 3

[0097] The embodiment provides a method for preparing the laminated power module in the embodiment 1 or the embodiment 2,

[0098] The method comprises the following steps: according to the conduction requirement and the heat dissipation requirement of the power module, combining the circuit boards which need to be laminated on the metal radiator 15 to design, and determining that the layout of the conductive columns 4 and the conductive through holes 5 between the circuit boards should meet the following requirements:

[0099] a. The lower end of the conductive column 4 is fixed at the input end and / or the output end of the bottom layer circuit board 1, and the minimum distance between adjacent conductive columns 4 is 2.2 mm, so as to meet the functional conduction between the upper and lower circuit boards.

[0100] b. The conductive through hole 5 is arranged on the upper layer circuit board 2 and corresponds to the upper side of the conductive column 4, so as to meet the shortest loop length after the functional conduction of the upper and lower circuit boards.

[0101] Based on the above requirements, the preparation method comprises the following steps:

[0102] Step 1, limit the bottom layer circuit board 1 on the lower mold 18, and point the tin paste on the bottom layer circuit board 1 corresponding to the fixed conductive column 4 position and the fixed power circuit position, and place the power circuit on the tin paste position corresponding to the fixed power circuit; adopt the pin machine to automatically insert the conductive column 4 into the positioning hole 20 of the upper mold 19, and use the detachable limiting baffle 21 to limit the lower end of the conductive column 4.

[0103] Step 2, use the positioning pin 23 and the positioning hole 24 to make the upper mold 19 and the lower mold 18 close, and after closing, pull out the limiting baffle 21, so that the lower end of the conductive column 4 falls into the tin paste position corresponding to the fixed conductive column 4 on the bottom layer circuit board 1.

[0104] Step 3, send the mold into the welding equipment, and use the vacuum reflow welding process to weld and fix the power circuit and the conductive column 4 on the bottom layer circuit board 1, and after welding, open the mold and take out the bottom layer circuit board 1.

[0105] Step 4, coat the copper plating layer 16 on the metal heat sink 15, weld and fix the bottom layer circuit board 1 on the copper plating layer 16, then fix the insulating shell on the copper plating layer 16, and use the vacuum filling process to package the bottom layer circuit board 1, the power circuit and the lower end of the conductive column 4 in the insulating shell.

[0106] Step 5, set a correction plate, the correction plate is provided with a plurality of tapered countersunk correction holes corresponding to each conductive column 4, the conductive column 4 is sleeved into the tapered countersunk correction hole for correction, so that the conductive column 4 always remains vertical.

[0107] Step 6, set the upper layer circuit board 2, the upper layer circuit board 2 is provided with a functional circuit, a switching wire and a conductive via hole 5 corresponding to the conductive column 4, the functional circuit is connected with the conductive via hole 5 through the switching wire; move the upper layer circuit board 2 by the intelligent mechanical hand to make the conductive via hole 5 correspond to the conductive column 4, control the upper layer circuit board 2 to move downward, until the upper end of all the conductive columns 4 is respectively assembled into the corresponding conductive via hole 5, realize the upper and lower layers of the circuit board. In order to improve the preparation efficiency, this step can be carried out synchronously with steps 1-5.

[0108] Step 7, weld the conductive column 4 and the conductive via hole 5, so that the upper and lower circuit boards can be functionally conducted through the conductive column 4 and the conductive via hole 5, and the preparation is completed.

[0109] In this embodiment, the welding conditions of the vacuum reflow welding process are: preheating 100-150℃, heating rate 2-3℃ / s, solder reflow temperature 217-227℃, oxygen content <5ppm during welding, and holding time 30-90 seconds after welding. By using this specific welding condition, the welding yield of the conductive column 4 is improved, thereby improving the qualified rate of the power module.

[0110] In the embodiment, the specific process of the vacuum potting process is as follows: the insulating shell 7 and the bottom layer circuit board 1 are placed into a potting mold, air is exhausted after vacuumizing to-0.1Mpa, then Shore 00-30 hardness silicon gel is injected to fill the gaps in the insulating shell 7 and cover the bottom layer circuit board 1, the power circuit and the lower end of the conductive column 4, and the vacuum potting is completed after solidification. The specific vacuum potting process is beneficial to improving the protection performance and stability of the power module as a whole.

[0111] The method will be described in detail taking the laminated power module provided in the preparation example 2 as an example.

[0112] It is assumed that the three-phase rectification circuit 10 and the inversion circuit 11 are respectively installed on two DBC circuit boards 17, and the secondary rectification circuit 12 is respectively installed on the copper-plated layer 16 and four DBC circuit boards 17. Specifically, as shown in FIG. 2, Figures 5-7

[0113] When the three-phase rectification circuit 10 is prepared, in the lower mold 18, the DBC circuit board 17 is first placed in the limiting area of the lower mold 18, and the tin paste is dotted on the DBC circuit board 17 corresponding to the positions of the fixed conductive column 4, the fixed chip and the fixed copper tab, the rectifier diode chip is placed on the tin paste corresponding to the fixed chip, the tin paste is dotted on the rectifier diode chip, and the two ends of the copper tab are respectively placed on the tin paste corresponding to the fixed copper tab position and the tin paste of the rectifier diode chip. In the upper mold 19, the conductive column 4 is automatically inserted into the positioning hole 20 of the upper mold 19 by using the pin inserting machine, and the lower end of the conductive column 4 is limited by the limiting baffle 21, then the positioning pin 23 and the positioning hole 24 are used to make the upper mold 19 and the lower mold 18 close, after closing, the limiting baffle 21 is withdrawn, so that the lower end of each conductive column 4 automatically falls on the tin paste corresponding to the fixed conductive column 4 position under the action of gravity, and the welding equipment is sent to realize the welding and fixation of the three-phase rectification circuit 10 and the conductive column 4 on the DBC circuit board 17.

[0114] Similarly, the preparation of the inversion circuit 11 and the secondary rectification circuit 12 can be completed, and it is necessary to note that when the secondary rectification circuit 12 is prepared, the FRD chip is directly placed in the limiting area of the lower mold 18, and the FRD chip and the DBC circuit board 17 are connected into a whole through the copper tab, and finally the corresponding circuits and conductive columns 4 are welded on the copper-plated layer 16.

[0115] In detail, based on the same innovative concept, the specific implementation process of the embodiment can be referred to the implementation of the power module described above, and the repeated parts will not be described herein.

[0116] ​The above description is only a specific implementation of the present application. Any feature disclosed in the specification can be replaced by other equivalent features unless specifically stated otherwise. All features disclosed in the specification, or all steps in the methods or processes, can be combined in any manner unless mutually exclusive features and / or steps are specifically stated.

Claims

1. A stacked power module comprising a metal heat sink (15) on top of which a circuit board is stacked one after the other, characterized in that: The function conduction between the at least two layers of circuit boards is realized through a plurality of conductive columns (4) and a plurality of conductive vias (5), and the following technical requirements should be met: a. The lower end of the conductive column (4) is fixed at the input end and / or output end of the bottom layer circuit board (1), and the minimum spacing between adjacent conductive columns (4) is 2.2 mm to meet the function conduction between the upper and lower circuit boards; b. The conductive via (5) is correspondingly arranged above the conductive column (4), and the loop length after the function conduction of the upper and lower circuit boards is the shortest; c. The bottom layer circuit board (1) is limited on the lower mold (18), and the tin paste is fixed on the position of the bottom layer circuit board (1) corresponding to the conductive column (4); the conductive column (4) is automatically inserted into the positioning hole (20) of the upper mold (19) by using the pin machine, and the lower end of the conductive column (4) is limited by the detachable limiting baffle (21); the upper mold (19) and the lower mold (18) are combined by using the positioning pin (23) and the positioning hole (24), after the combination, the limiting baffle (21) is pulled out, so that the lower end of the conductive column (4) falls into the tin paste position on the bottom layer circuit board (1), the mold is sent into the welding equipment, and after welding, the conductive column (4) is vertically fixed on the bottom layer circuit board (1), so that the upper end of each conductive column (4) can be correspondingly assembled into each conductive via (5); The bottom layer circuit board (1) is configured with a power circuit, the upper layer circuit board (2) is configured with a function circuit, a switching wire and a plurality of power terminals (6), and the function circuit and the power terminal (6) are connected with the conductive via (5) through the switching wire respectively; the conductive column (4) is arranged at the input end and / or output end of the power circuit, and after the power circuit and the conductive column (4) are integrally packaged on the bottom layer circuit board (1), the function circuit is realized through the conductive via (5) and the switching wire; The shortest loop length after the function conduction of the upper and lower circuit boards refers to the shortest length of the switching wire between the conductive via (5) and the function circuit and between the conductive via (5) and the power terminal (6).

2. A laminated power module according to claim 1, characterized in that: The conductive column (4) is a T-shaped structure including a cylindrical rod and a cylindrical cap, the cylindrical cap is welded and fixed on the bottom layer circuit board (1), the cylindrical rod is welded and fixed in the conductive via (5), and the diameter of the cylindrical rod is 1-1.2 mm.

3. The laminated power module of claim 1, wherein: The power circuit includes a three-phase rectifier circuit (10), an inverter circuit (11) and a secondary rectifier circuit (12), the power input end of the three-phase rectifier circuit (10) is electrically connected with part of the power terminals (6) through the conductive column (4) and the conductive via (5), the power output end of the three-phase rectifier circuit (10) is electrically connected with part of the power terminals (6) through the conductive column (4) and the conductive via (5), the signal input end of the inverter circuit (11) is electrically connected with the driving circuit (13) through the conductive column (4) and the conductive via (5), the power output end of the inverter circuit (11) is electrically connected with part of the power terminals (6) through the conductive column (4) and the conductive via (5), and the power input end of the secondary rectifier circuit (12) is electrically connected with part of the power terminals (6) through the conductive column (4) and the conductive via (5).

4. A laminated power module according to claim 3, characterized in that: The bottom layer circuit board (1) is a combination structure of multiple DBC circuit boards (17) and copper plating layers (16), the copper plating layer (16) is coated on the metal heat sink (15), the DBC circuit board (17) is welded and fixed on the copper plating layer (16), the three-phase rectifier circuit (10) and the inverter circuit (11) are arranged at the lower part and the upper part of a DBC circuit board (17) respectively, and the secondary rectifier circuit (12) is arranged on the copper plating layer (16) and the remaining DBC circuit boards (17).

5. A laminated power module according to claim 4, characterized in that: The conductive column (4) of the power input end of the three-phase rectifier circuit (10) is arranged in a matrix at the lower part of the DBC circuit board (17), the conductive column (4) of the power output end of the three-phase rectifier circuit (10) is arranged at the right middle part and the left upper part of the DBC circuit board (17) respectively, the conductive column (4) of the signal input end of the inverter circuit (11) is arranged at the left middle upper part and the right middle upper part of the DBC circuit board (17) respectively, the conductive column (4) of the power output end of the inverter circuit (11) is arranged at the middle of the upper part of the DBC circuit board (17), and the conductive column (4) of the power input end of the secondary rectifier circuit (12) is evenly arranged on the multiple DBC circuit boards (17).

6. A laminated power module according to any one of claims 3-5, characterized in that: The functional circuit includes a driving circuit (13), an IGBT resistance-capacitance absorption circuit (3) and an FRD resistance-capacitance absorption circuit (14), the IGBT resistance-capacitance absorption circuit (3) is connected in parallel with the three-phase rectifier circuit (10) through the conductive column (4) and the conductive via (5), the FRD resistance-capacitance absorption circuit (14) is connected in parallel with the secondary rectifier circuit (12) through the conductive column (4) and the conductive via (5), and the conductive column (4) of the power output end of the three-phase rectifier circuit (10) and the conductive column (4) of the power output end of the inverter circuit (11) are shared between the IGBT resistance-capacitance absorption circuit (3) and the three-phase rectifier circuit (10), and the conductive column (4) between the FRD resistance-capacitance absorption circuit (14) and the secondary rectifier circuit (12) is symmetrically arranged on the copper plating layer (16).

7. A laminated power module according to claim 6, characterized in that: The upper layer circuit board (2) includes one PCB circuit board or two PCB circuit boards stacked above the bottom layer circuit board (1), when the upper layer circuit board (2) includes one PCB circuit board, the driving circuit (13), the IGBT resistance-capacitance absorption circuit (3) and the FRD resistance-capacitance absorption circuit (14) are arranged on the PCB circuit board; when the upper layer circuit board (2) includes two PCB circuit boards, the driving circuit (13) is arranged on one of the PCB circuit boards, the IGBT resistance-capacitance absorption circuit (3), the FRD resistance-capacitance absorption circuit (14) and the power terminal (6) are arranged on the other PCB circuit board, and the PCB circuit board on which the driving circuit (13) is arranged is located above the other PCB circuit board.

8. A laminated power module according to claim 7, characterized in that: The IGBT resistance-capacitance absorption circuit (3) and the FRD resistance-capacitance absorption circuit (14) are arranged on two PCB circuit boards respectively, the two PCB circuit boards have the same height and are located above the inverter circuit (11) and the secondary rectifier circuit (12) respectively.

9. The laminated power module of claim 1, wherein: The metal radiator (15) is fixed with an insulating shell (7), the bottom layer circuit board (1), the power circuit and the conductive column (4) are integrally packaged in the insulating shell (7) through a vacuum filling process, the upper part of the insulating shell (7) is provided with positioning grooves (8) for fixing the power terminals (6) on both sides, and the positioning grooves (8) are provided with counterbores (9), and the counterbores (9) are provided with nuts; the power terminals (6) are L-shaped copper bars welded and fixed on the upper layer circuit board (2), one end of each L-shaped copper bar is arranged on the two sides of the upper layer circuit board (2), and the other end of each L-shaped copper bar is fixed in the positioning groove (8) through a bolt and a nut and is electrically connected with an external device.

10. A method of manufacturing a stacked power module, characterized by: According to the requirements of the power module, the design of the circuit board stacked on the metal radiator (15) is combined, and the layout of the conductive column (4) and the conductive via (5) between the circuit boards should meet the following requirements: a. The lower end of the conductive column (4) is fixed to the input and / or output end of the bottom layer circuit board (1), and the minimum distance between adjacent conductive columns (4) is 2.2mm, so as to meet the functional conduction between the upper and lower circuit boards; b. The conductive via (5) is arranged above the conductive column (4) to meet the shortest loop length after the functional conduction of the upper and lower circuit boards; Based on the above requirements, the preparation method comprises the following steps: Step 1, limit the bottom layer circuit board (1) on the lower mold (18), point the tin paste on the bottom layer circuit board (1) corresponding to the position of the conductive column (4) and the position of the power circuit, and place the power circuit on the corresponding tin paste; the conductive column (4) is automatically inserted into the positioning hole (20) of the upper mold (19) by using the pin machine, and the lower end of the conductive column (4) is limited by using the detachable limiting baffle (21); Step 2, use the positioning pin (23) and the positioning hole (24) to make the upper mold (19) and the lower mold (18) close, after closing, pull out the limiting baffle (21), so that the lower end of the conductive column (4) falls into the tin paste position corresponding to the fixed conductive column (4) on the bottom layer circuit board (1); Step 3, send the mold into the welding equipment, and use the vacuum reflow welding process to weld and fix the power circuit and the conductive column (4) on the bottom layer circuit board (1), and after welding, open the mold and take out the bottom layer circuit board (1); Step 4, coat a copper plating layer (16) on the metal radiator (15), weld and fix the bottom layer circuit board (1) on the copper plating layer (16), then fix the insulating shell on the copper plating layer (16), and use the vacuum filling process to package the bottom layer circuit board (1), the power circuit and the lower end of the conductive column (4) in the insulating shell; Step 5, set a correction plate, the correction plate is provided with a plurality of conical countersunk correction holes corresponding to each conductive column (4), the conductive column (4) is inserted into the conical countersunk correction hole for correction, so that the conductive column (4) always remains vertical; Step 6, set the upper layer circuit board (2), the upper layer circuit board (2) is configured with functional circuit, adapter wire and conductive hole (5) corresponding to the conductive column (4), the functional circuit is connected with the conductive hole (5) through the adapter wire; the conductive hole (5) is corresponding to the conductive column (4) by moving the upper layer circuit board (2) through the intelligent manipulator, the upper layer circuit board (2) is controlled to move downward, until the upper end of all conductive columns (4) is respectively assembled into the corresponding conductive hole (5), realizing the upper and lower layers of the circuit board are stacked; Step 7, the conductive column (4) and the conductive hole (5) are welded, so that the upper and lower circuit boards can be functionally conducted through the conductive column (4) and the conductive hole (5), and the preparation is completed; The bottom layer circuit board (1) is configured with a power circuit, and the upper layer circuit board (2) is configured with a functional circuit, an adapter wire and a plurality of power terminals (6), the functional circuit and the power terminals (6) are respectively connected with the conductive hole (5) through the adapter wire; the conductive column (4) is arranged at the input end and / or the output end of the power circuit, and after the power circuit and the conductive column (4) are integrally packaged on the bottom layer circuit board (1), the functional circuit is realized by the conductive hole (5) and the adapter wire. The shortest loop length after the functional conduction of the upper and lower circuit boards refers to the shortest length of the adapter wire between the conductive hole (5) and the functional circuit and the adapter wire between the conductive hole (5) and the power terminal (6).

11. The method of claim 10, wherein: In step 3, the welding conditions of the vacuum reflow soldering process are: preheating 100-150℃, heating rate 2-3℃ / s, solder reflow temperature 217-227℃, maintaining oxygen content <5ppm during welding, and holding for 30-90 seconds after welding; In step 4, the specific process of the vacuum filling process is: the insulating shell (7) and the bottom layer circuit board (1) are put into the filling mold, vacuumized to-0.1Mpa, then air is discharged, then Shore 00-30 hardness silicone gel is injected to fill the gap in the insulating shell (7) and cover the bottom layer circuit board (1), the power circuit and the lower end of the conductive column (4), and the vacuum filling is completed after curing.

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