Half-bridge power module welding jig based on reflow soldering process and reflow soldering process of half-bridge power module

Abstract

The invention relates to a half-bridge power module welding jig based on a reflow soldering process and the reflow soldering process of a half-bridge power module. Comprising a bottom plate, the upper plate surface of the bottom plate is provided with an embedding groove, the bottom of the embedding groove is provided with a heat dissipation plate mounting groove, and the bottom of the heat dissipation plate mounting groove is provided with extending holes which penetrate through the bottom plate and are used for extending of heat dissipation bottom plate pin fins; two half-square frames are further included, the two opposite ends of each half-square frame are fixed into the corresponding embedding groove through positioning pieces, a containing gap used for containing a soldering lug is formed between the two half-square frames, and the half-square frames are movably connected with the positioning pieces; the inner plate surface of the pressing plate is provided with an accommodating groove in which the bottom plate can be embedded in a close fit manner; an operation hole is formed in the pressing plate, a pressing block used for pressing a terminal pin of the terminal frame is tightly matched and connected to the pressing plate in a penetrating manner, and one end of the pressing block extends into the embedding groove; according to the design of the half-bridge power module welding jig based on the reflow soldering process, the reflow soldering process efficiency can be improved, only one-time vacuum reflow is needed, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of welding fixture technology, and in particular to a welding fixture for a half-bridge power module based on reflow soldering process and a reflow soldering process for the half-bridge power module. Background Technology

[0002] In the soldering process of half-bridge power module packaging, the soldering steps are mostly step-by-step. The heat sink, copper-clad ceramic sheet, chip, and terminal frame are soldered in multiple steps in a vacuum reflow oven using solder pads. This process is inefficient, involves multiple vacuum reflows, and is costly. Furthermore, multiple soldering reflows can damage the back gold of the chip, potentially leading to a decrease in the chip's electrical performance or even failure.

[0003] Therefore, in order to address the above problems, the present invention urgently needs to provide a welding fixture for a half-bridge power module. Summary of the Invention

[0004] The purpose of this invention is to provide a half-bridge power module welding fixture based on reflow soldering technology and a reflow soldering process for half-bridge power modules. By proposing a half-bridge power module welding fixture based on reflow soldering technology, the invention can solve the technical problems existing in the soldering process of half-bridge power module packaging, which involves multiple steps of soldering. The heat sink base plate, copper-clad ceramic sheet, chip, and terminal frame are soldered in multiple steps in a vacuum reflow oven using solder pads. This is inefficient, costly due to multiple vacuum reflows, and damage to the back gold of the chip caused by multiple soldering reflows, which may lead to a decrease in the electrical performance of the chip or even failure.

[0005] The present invention provides a welding fixture for a half-bridge power module based on reflow soldering process, including a base plate, an embedding groove on the surface of the base plate, a heat sink mounting groove at the bottom of the embedding groove, and an insertion hole through the base plate for the heat sink base plate pin fins to extend into the bottom of the heat sink mounting groove. It also includes two half-frames, each half-frame being fixed to the embedded groove at opposite ends by positioning elements, with a placement gap between the two half-frames for placing the welding piece, and the half-frames being movably connected to the positioning elements. It also includes a pressure plate for pressing the terminal frame, the inner plate of the pressure plate is provided with a base plate that can be tightly fitted into an embedded receiving groove; the pressure plate is provided with an operating hole, and a pressure block for pressing the terminal foot of the terminal frame is also tightly fitted on the pressure plate, with one end of the pressure block extending into the embedded groove.

[0006] Preferably, each half-frame has a mating groove on its outer wall at both ends that matches the corresponding positioning component, and the upper inner wall and lower inner wall of each mating groove penetrate the upper and lower surfaces of the half-frame. The inner wall of the semi-square frame is provided with protrusions at intervals, and the corners of the semi-square frame are provided with clearance grooves.

[0007] Preferably, an overlap post for overlapping the terminal frame is provided between two adjacent positioning members.

[0008] Preferably, the side wall of the base plate is provided with a first side hole communicating with the heat sink mounting groove and a second side hole communicating with the embedding groove. The top of the second side hole penetrates the upper surface of the base plate, and the first side hole and the second side hole are in communication.

[0009] Preferably, the base plate is provided with frame limiting posts at opposite corners.

[0010] Preferably, multiple slots are spaced apart on the pressure plate on both sides of the operating hole, and each slot has an insertion hole that penetrates the pressure plate. The pressure block includes a first pressure section that is tightly fitted into the slot, and a second pressure section that can extend out of the insertion hole at one end of the first pressure section.

[0011] Preferably, the positioning component includes a positioning post, which is fixedly connected to the base plate, and the semi-rectangular frame is inserted and fixed to the positioning post.

[0012] Preferably, the cross-section of the overlapping column is either square or circular.

[0013] Preferably, the upper end face of the lap post and the upper end face of the positioning member are on the same plane.

[0014] The present invention also provides a reflow soldering process for a half-bridge power module, comprising the following steps: Prepare a welding fixture for a half-bridge power module based on reflow soldering process as described in any of the above-mentioned examples; Place the heat sink base plate with pin fins into the heat sink mounting slot of the base plate, with the pin fins of the heat sink base plate extending into the insertion hole. The half-square is fixed in the embedded groove by the positioning piece; Place the copper-clad ceramic sheet solder pad that is compatible with the copper-clad ceramic sheet onto the heat sink base plate; Place the copper-clad ceramic sheet on the copper-clad ceramic sheet solder pad; Place the terminal lead solder pads and chip solder pads into the corresponding positions on the copper-clad ceramic sheet; Place the chip on the chip solder pad; Place the terminal frame on the base plate, with the terminal feet of the terminal frame positioned above the terminal foot solder pads; Place the pressure plate, insert each pressure block onto the pressure plate, and extend one end of the pressure block into the embedded groove to crimp the terminal feet of the terminal frame. After assembly, it is placed in a vacuum furnace for welding. After welding is completed, the welding fixture for the half-bridge power module is removed to obtain the half-bridge power module.

[0015] The present invention provides a welding fixture for a half-bridge power module based on reflow soldering technology and a reflow soldering process for the half-bridge power module, which have the following advantages compared with the prior art: 1. The half-bridge power module welding fixture based on reflow soldering technology provided by this invention features a heat sink mounting groove on the base plate. The bottom of the heat sink mounting groove has an insertion hole to accommodate a heat sink base plate with pin fins. The pin fins of the heat sink base plate can extend through the insertion hole, preventing unevenness between the terminal frame and the base plate after installation (the bottom of the pin fins of the terminal frame is not a flat plane). The outer edge of the heat sink base plate overlaps with the edge of the heat sink mounting groove, increasing the thermal conductivity of the heat sink base plate and enhancing the thermal conductivity of the vacuum reflow oven heating stage, ensuring welding results. The cooperation of two half-frames and positioning components allows the two half-frames to be fixed in the embedding groove, used to limit the copper-clad ceramic sheet. Furthermore, during reflow soldering, the solder sheet changes from solid metal to liquid metal and is in a flowing state, which may cause solder overflow. The half-frame design reduces the contact area with the liquid solder, allowing for easy disassembly of the fixing frame and reducing the technical problem of ceramic sheet breakage caused by disassembly of the fixing frame. The pressure plate design allows for the pressing of the terminal frame, ensuring its flatness. The pressure block facilitates the pressing of the terminal feet, enabling control over the solder thickness at the terminal feet. This structural design allows for the complete soldering of the half-bridge power module in a single operation, resulting in high efficiency, reduced costs, and avoiding the damage to the chip's back gold caused by multiple soldering reflows, thus ensuring the chip's electrical performance.

[0016] 2. This invention proposes a reflow soldering process for half-bridge power modules, which can complete the soldering process in one step to obtain the half-bridge power module without the need for step-by-step soldering. The heat sink, copper-clad ceramic sheet, chip, terminal frame, and solder pads are soldered in a vacuum reflow oven in one step, which is highly efficient, reduces costs, effectively avoids damage to the back gold of the chip caused by multiple soldering, and ensures the electrical performance of the chip. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram (three-dimensional view) of the welding fixture structure for the half-bridge power module described in this invention. Figure 2 This is a schematic diagram (three-dimensional view) of the structure of the base plate described in this invention. Figure 3 This is a schematic diagram (perspective view) of the assembly of the base plate and the semi-square frame described in this invention. Figure 4 This is a schematic diagram (perspective, bottom view) of the pressure plate described in this invention. Figure 5 This is a schematic diagram (perspective, top view) of the pressure plate described in this invention. Figure 6 This is a schematic diagram (three-dimensional view) of the semi-rectangular frame described in this invention. Figure 7 This is a schematic diagram (three-dimensional view) of the structure of the pressure block described in this invention. Figure 8 This is a schematic diagram (sectional view) of the assembly of the half-bridge power module and welding fixture described in this invention. Figure 9 for Figure 8 Enlarged view of point A in the middle.

[0019] Explanation of reference numerals in the attached figures: 1. Base plate; 2. Embedded groove; 3. Heat sink mounting groove; 4. Insertion hole; 5. Semi-square frame; 51. Butt groove; 52. Protrusion; 53. Clearance groove; 7. Overlap post; 8. Pressure plate; 9. Positioning component; 10. First side hole; 11. Second side hole; 12. Frame limiting post; 81. Receiving groove; 82. Operating hole; 83. Slot; 84. Insertion hole; 13. Pressure block; 131. First pressure section; 132. Second pressure section; 14. Heat sink base plate; 15. Copper-clad ceramic sheet; 16. Copper-clad ceramic sheet solder pad; 17. Terminal pin solder pad; 18. Chip solder pad; 19. Chip; 20. Terminal frame. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] like Figure 1 , Figure 2 , Figure 3 As shown, this embodiment provides a welding fixture for a half-bridge power module based on reflow soldering process, including a base plate 1, an embedding groove 2 on the upper surface of the base plate 1, a heat sink mounting groove 3 at the bottom of the embedding groove 2, and an insertion hole 4 through the base plate 1 for the heat sink mounting groove 3 to extend into the heat sink mounting groove 3; it also includes two half-frames 5, each half-frame 5 is fixed to the embedding groove 2 at opposite ends by positioning members 9, and a placement gap for placing solder pieces is provided between the two half-frames 5, and the half-frames 5 are movably connected to the positioning members 9; it also includes a pressure plate 8 for pressing the terminal frame, the inner surface of the pressure plate 8 is provided with a receiving groove 81 for the base plate to be tightly fitted and embedded; the pressure plate 8 is provided with an operating hole 82, and a pressure block 13 for pressing the terminal feet of the terminal frame is also tightly fitted and inserted into the pressure plate 8, one end of the pressure block 13 extending into the embedding groove 2.

[0024] The present invention provides a welding fixture for a half-bridge power module based on reflow soldering technology. A heat sink mounting groove 3 is designed on the base plate 1, with an insertion hole 4 at the bottom. A heat sink base plate with pin fins can be inserted into the insertion hole 4, the depth of which matches the length of the pin fins, ensuring the pin fins are parallel to the bottom surface of the base plate 1. The outer edge of the heat sink base plate overlaps with the edge of the heat sink mounting groove 3, increasing the thermal conductivity of the heat sink base plate and enhancing the heat conduction of the vacuum reflow oven heating stage, thus ensuring welding effectiveness. The cooperation of two half-frames 5 and positioning elements 9 fixes the two half-frames 5 in the embedding groove 2, limiting the position of the copper-clad ceramic sheet. Furthermore, during reflow soldering, the solder sheet changes from solid metal to liquid metal and is in a flowing state, which can lead to solder overflow. The half-frame design reduces the contact area with the liquid solder, allowing for easy disassembly of the fixing frame and reducing the technical problem of ceramic sheet breakage caused by frame removal. The design of pressure plate 8 enables the pressing of the terminal frame, ensuring its flatness. Pressure block 13 facilitates the pressing of the terminal feet of the terminal frame, allowing control over the solder thickness under the terminal feet. In other words, this structural design allows for the one-time completion of half-bridge power module soldering, resulting in high efficiency, reduced costs, and avoidance of the damage to the chip's back gold caused by multiple soldering reflows, thus ensuring the chip's electrical performance.

[0025] The base plate 1 of the present invention is sized to match the terminal frame, and the outer edge of the terminal frame overlaps the base plate 1.

[0026] like Figure 6 As shown, in this embodiment, each half-frame 5 has a mating groove 51 on its outer wall at both ends that matches the corresponding positioning member 9. The upper inner wall and lower inner wall of each mating groove 51 penetrate the upper and lower surfaces of the half-frame 5. The inner wall of the half-frame 5 is provided with protrusions 52 at intervals, and the corner of the half-frame 5 is provided with a clearance groove 53. Through the above structural design, the contact area between the half-frame 5 and the welding piece is further reduced, the fixing frame can be easily disassembled, and the technical problem of reducing the failure mode of ceramic piece breakage caused by disassembling the fixing frame is reduced.

[0027] like Figure 3 As shown, in this embodiment, an overlapping post 7 for overlapping the terminal frame is provided between two adjacent positioning members 9; the design of the overlapping post 7 can support the terminal frame and prevent the terminal frame from deforming.

[0028] like Figure 2 , Figure 3 As shown, in this embodiment, the side wall of the base plate 1 is provided with a first side hole 10 that communicates with the heat sink mounting groove 3 and a second side hole 11 that communicates with the embedding groove 2. The top of the second side hole 11 penetrates the upper surface of the base plate 1. The first side hole 10 and the second side hole 11 are connected. The design of the first side hole 10 and the second side hole 11 can achieve uniform heat distribution and facilitate demolding.

[0029] like Figure 3 As shown, in this embodiment, the base plate 1 is provided with frame limiting posts 12 at opposite corners. The frame limiting posts 12 can limit the terminal frame to prevent the terminal frame from moving and ensure the final welding effect.

[0030] like Figure 4 , Figure 5 As shown, in this embodiment, multiple slots 83 are spaced apart on the pressure plates 8 located on both sides of the operating hole 82. Each slot 83 has an insertion hole 84 that penetrates the pressure plate 8. The pressure block 13 includes a first pressure section 131 that is tightly fitted into the slot 83. One end of the first pressure section 131 has a second pressure section 132 that can extend out of the insertion hole 84. Through the above structural design, the pressure block 13 can be fastened to ensure the crimping of the terminal pin. At the same time, the position can be moved to control the solder thickness. In addition, the stepped design of the slots 83 and the insertion holes 84 can limit the pressure block 13 to avoid excessive pressure on the terminal pin, which would make it impossible to control the solder thickness.

[0031] The positioning component 9 in this embodiment includes a positioning post, which is fixedly connected to the base plate 1. The semi-square frame 5 is inserted and fixed to the positioning post. The structure is simple and easy to install. Preferably, the cross-section of the positioning post is circular.

[0032] In this embodiment, the cross-section of the overlapping column 7 is either square or circular. Preferably, the cross-section of the overlapping column 7 is square to increase the contact area and ensure the support effect.

[0033] In this embodiment, the upper end face of the lap post 7 and the upper end face of the positioning member 9 are on the same plane; the positioning member 9 can not only achieve the positioning function, but also the supporting function of the terminal frame, so as to prevent the terminal frame from deforming.

[0034] The present invention also provides a reflow soldering process for a half-bridge power module, comprising the following steps: 1) Prepare a half-bridge power module welding fixture based on reflow soldering process as described in any one of the above-mentioned methods; 2) Place the heat dissipation base plate 14 with pin fins into the heat dissipation plate mounting groove 3 of the base plate 1, with the pin fins of the heat dissipation base plate extending into the insertion hole 4. 3) Fix the semi-rectangular frame 5 into the embedded groove 2 using the positioning piece 9; 4) Place the copper-clad ceramic sheet solder pad 16, which is compatible with the copper-clad ceramic sheet 15, onto the heat dissipation base plate 14; 5) Place the copper-clad ceramic sheet 15 on the copper-clad ceramic sheet solder pad 16; 6) Place the terminal lead solder pads 17 and chip solder pads 18 into the corresponding positions on the copper-clad ceramic sheet 15; 7) Place chip 19 on chip solder pad 18; 8) Place the terminal frame 20 on the base plate 1, with the terminal feet of the terminal frame 20 positioned above the terminal foot solder pads 17; 9) Place the pressure plate 8 and insert each pressure block 13 onto the pressure plate 8. One end of the pressure block 13 extends into the embedded groove 2 to press the terminal pins of the terminal frame 20. 10) After assembly, place it in a vacuum furnace to complete welding; 11) After welding is completed, remove the welding fixture for the half-bridge power module to obtain the half-bridge power module.

[0035] This invention proposes a reflow soldering process for half-bridge power modules, which can complete the soldering process in one step to obtain the half-bridge power module without the need for step-by-step soldering. The heat sink, copper-clad ceramic sheet, chip, terminal frame, and solder pads are soldered in a vacuum reflow oven in one step, which is highly efficient, reduces costs, effectively avoids damage to the back gold of the chip caused by multiple soldering, and ensures the electrical performance of the chip.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welding fixture for a half-bridge power module based on reflow soldering process, characterized in that: Includes a base plate (1), the upper surface of the base plate (1) is provided with an embedding groove (2), the bottom of the embedding groove (2) is provided with a heat sink mounting groove (3), and the bottom of the heat sink mounting groove (3) is provided with an insertion hole (4) that penetrates the base plate (1) for the heat sink base plate pin fins to extend into. It also includes two half-frames (5), each half-frame (5) is fixed in the embedded groove (2) at opposite ends by positioning member (9), and a placement gap for placing welding pieces is provided between the two half-frames (5), and the half-frames (5) are movably connected to the positioning member (9); It also includes a pressure plate (8) for pressing the terminal frame. The inner plate surface of the pressure plate (8) is provided with a base plate (1) that can be tightly fitted into an embedded receiving groove (81). The pressure plate (8) is provided with an operating hole (82). The pressure plate (8) is also tightly fitted with a pressure block (13) for pressing the terminal foot of the terminal frame. One end of the pressure block (13) extends into the embedded groove (2).

2. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 1, characterized in that: Each half-square (5) has a mating groove (51) on the outer wall at both ends that matches the corresponding positioning part (9). The upper inner wall and lower inner wall of each mating groove (51) are connected to the upper and lower surfaces of the half-square (5). The inner wall of the semi-square (5) is provided with protrusions (52) at intervals, and the corner of the semi-square (5) is provided with a relief groove (53).

3. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 1, characterized in that: An overlap post (7) for overlapping of terminal frames is provided between two adjacent positioning members (9).

4. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 1, characterized in that: The side wall of the base plate (1) is provided with a first side hole (10) that communicates with the heat sink mounting groove (3) and a second side hole (11) that communicates with the embedding groove (2). The top of the second side hole (11) penetrates the upper surface of the base plate (1), and the first side hole (10) and the second side hole (11) are connected.

5. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 1, characterized in that: The base plate (1) is provided with frame limiting columns (12) at opposite corners.

6. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 1, characterized in that: Multiple slots (83) are spaced apart on the pressure plate (8) located on both sides of the operating hole (82). Each slot (83) has an insertion hole (84) that penetrates the pressure plate (8). The pressure block (13) includes a first pressure section (131) that is tightly fitted into the slot (83). One end of the first pressure section (131) has a second pressure section (132) that can extend out from the insertion hole (84).

7. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 1, characterized in that: The positioning component (9) includes a positioning post, which is fixedly connected to the base plate (1), and the half-square frame (5) is inserted and fixed to the positioning post.

8. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 3, characterized in that: The cross-section of the lap column (7) is either square or circular.

9. The welding fixture for a half-bridge power module based on reflow soldering process according to claim 3, characterized in that: The upper surface of the lap column (7) and the upper surface of the positioning component (9) are on the same plane.

10. A reflow soldering process for a half-bridge power module, characterized in that: Includes the following steps: Prepare a welding fixture for a half-bridge power module based on reflow soldering process as described in any one of claims 1-9; Place the heat dissipation base plate (14) with pin fins into the heat dissipation plate mounting groove (3) of the base plate (1), and extend the pin fins of the heat dissipation base plate into the insertion hole (4). The half-square (5) is fixed in the embedded groove (2) by the positioning piece (9); Place the copper-clad ceramic sheet solder pad (16) that is compatible with the copper-clad ceramic sheet (15) onto the heat dissipation base plate (14); Place the copper-clad ceramic sheet (15) on the copper-clad ceramic sheet solder sheet (16); Place the terminal lead solder pads (17) and chip solder pads (18) into the corresponding positions on the copper-clad ceramic sheet (15); Place the chip (19) on the chip solder pad (18); Place the terminal frame (20) on the base plate (1), with the terminal feet of the terminal frame (20) positioned above the terminal foot solder pads (17); Place the pressure plate (8), insert each pressure block (13) onto the pressure plate (8), and insert one end of the pressure block (13) into the embedded groove (2) to crimp the terminal feet of the terminal frame (20); After assembly, it is placed in a vacuum furnace for welding. After welding is completed, the welding fixture for the half-bridge power module is removed to obtain the half-bridge power module.

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