Insulated gate bipolar transistor (IGBT) module production method capable of reducing holes, production equipment and IGBT module

Abstract

The invention provides a production method of an IGBT module capable of reducing cavities, the IGBT module comprises a copper bottom plate and two cuboid DBC plates, the two ends of the copper bottom plate in the length direction are upwarped, the two DBC plates are welded on the two sides of the middle position of the copper bottom plate in the length direction through soldering tin, and the two DBC plates are welded on the two sides of the middle position of the copper bottom plate in the length direction through soldering tin. A plurality of criss-cross air outlet grooves facilitating volatilization of soldering flux are formed in the positions, corresponding to a DBC plate, of the copper bottom plate, and the production method is characterized by specifically comprising the following steps that firstly, the copper bottom plate provided with the air outlet grooves is fed to a preset position; 2, solder paste printing is carried out on the area, where the DBC board is placed, of the copper bottom board; step 3, placing the DBC board on the solder paste; 4, placing a limiting jig on the copper bottom plate, wherein the limiting jig is used for limiting the DBC plate; fifthly, products in the fourth step are put into an oven together, the products are baked through the oven, in the baking process, the solder paste is melted, the melted solder paste flows, a part of the melted solder paste flows into an air outlet groove, and the volatilized soldering flux runs out of the air outlet groove; and step 6, cooling after baking for a preset time, and taking out the product from the oven after cooling to obtain the IGBT module.

Description

Technical Field

[0001] This invention relates to the field of IGBT modules, and more particularly to a method, equipment and module for producing IGBT modules that can reduce voids. Background Technology

[0002] During IGBT module production, solder paste is first printed onto a copper base plate. Then, the DBC (Digital Bracket Cell) is placed on the solder paste and baked in an oven. During baking, the solder paste melts. To improve soldering quality, flux is often added to the solder paste. However, this flux evaporates during baking. Because there is a large coverage area between the DBC and the copper base plate, some of this flux may not evaporate completely, resulting in voids. Summary of the Invention

[0003] The main objective of this invention is to provide a method, equipment, and module for producing IGBT modules that can reduce voids. In this IGBT module, venting grooves are formed on the copper base plate, which allows the volatile flux to escape in a timely manner during the production process, thereby reducing voids.

[0004] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for producing an IGBT module that reduces voids, wherein the IGBT module includes a copper base plate and two DBC boards, the DBC boards being cuboids, the two ends of the copper base plate curving upwards along its length, the two DBC boards being soldered to both sides of the copper base plate at the middle position along its length, and multiple crisscrossing venting grooves for facilitating flux evaporation being provided on the copper base plate at positions corresponding to the DBC boards, characterized in that the production method specifically includes the following steps: Step 1: Place the copper base plate with the air vent groove into the predetermined position; Step 2: Print solder paste on the area where the DBC board will be placed on the copper base plate; Step 3: Place the solder paste onto the DBC board; Step 4: Place a limiting fixture on the copper base plate. The limiting fixture is used to limit the DBC board. Step 5: Place the products from Step 4 into the oven and bake them. During the baking process, the solder paste melts, flows, and some of it flows into the venting tank. The volatile flux escapes from the venting tank. Step 6: After baking for the predetermined time, cool the product and remove it from the oven to obtain the IGBT module.

[0005] Preferably, the steel mesh includes a mesh plate with multiple sets of mesh ports on the mesh plate. Each set of mesh ports corresponds to an IGBT module to be produced. The number of mesh ports in each set is multiple and corresponds one-to-one with the area divided by the venting groove on the copper base plate. The venting groove corresponds to the mesh plate between adjacent mesh ports.

[0006] Preferably, in step two, when solder paste needs to be printed, the stencil is moved directly above the copper base plate and then moved downwards to contact the copper base plate. Molten solder paste is placed on the stencil, and the solder paste is moved from one side to the other by a squeegee. When passing through the stencil opening, some solder paste will enter the opening and stick to the corresponding area on the copper base plate. Then the stencil is moved upwards to achieve the printing of solder paste.

[0007] Preferably, the thickness of the mesh openings in each group that are at a predetermined distance from the center of the copper base plate is set to be thicker than that of the mesh openings in other positions.

[0008] Preferably, the limiting fixture is a rectangular frame structure with positioning holes at the four corners of the copper base plate and positioning posts at the corresponding positioning holes, the positioning posts being able to be inserted into the positioning holes; two partition plates are provided inside the limiting fixture and at the middle position along the length direction of the copper base plate, and multiple abutment posts are provided on the inner edge of the limiting fixture, the two partition plates being used to separate the two DBC plates, and the abutment posts being used to abut against the edge of the DBC plates.

[0009] The present invention also provides an IGBT module, which is prepared using the above-described manufacturing method.

[0010] This invention also provides a production equipment for an IGBT module. The IGBT module includes a copper base plate and two DBC boards. The DBC boards are cuboids. The two ends of the copper base plate are curved upwards along its length. The two DBC boards are soldered to both sides of the copper base plate at the middle position along its length. Multiple crisscrossing venting grooves are provided on the copper base plate at positions corresponding to the DBC boards to facilitate flux evaporation. The production equipment includes: The copper base plate loading module is used to load the copper base plate to the predetermined position; Solder paste printing module, used to print solder paste on the side of the copper base plate on which the DBC board is placed; A limiting fixture is used to limit the movement of the DBC board placed on a copper base plate; The baking module is used to bake the assembled copper base plate, solder paste, DBC board, and limit fixture. The solder paste printing module includes a stencil and a squeegee. The stencil includes a movable stencil plate with multiple sets of slots. Each set of slots corresponds to one IGBT module. The number of slots in each set is multiple and corresponds one-to-one with the area divided by the venting groove on the copper base plate. The venting groove corresponds to the stencil plate between adjacent slots. The squeegee is movable.

[0011] Preferably, the thickness of the mesh ports in each group that are at a predetermined distance from the center of the copper base plate is set to be thicker than that of the mesh ports at other locations.

[0012] Preferably, the limiting fixture is a rectangular frame structure with positioning holes at the four corners of the copper base plate and positioning posts at the corresponding positioning holes, the positioning posts being able to be inserted into the positioning holes; two partition plates are provided inside the limiting fixture and at the middle position along the length direction of the copper base plate, and multiple abutment posts are provided on the inner edge of the limiting fixture, the two partition plates being used to separate the two DBC plates, and the abutment posts being used to abut against the edge of the DBC plates.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1) The copper base plate of the present invention has an venting groove, which allows the volatile flux to escape from the venting groove during the production process, reducing voids in the solder. 2) The different thicknesses of the mesh openings of the steel mesh of the present invention allow for the printing of more solder paste near the center of the copper base plate, thereby ensuring more solder in the center of the copper base plate. Attached Figure Description

[0014] Figure 1 This is a structural diagram of the copper base plate; Figure 2 This is a structural diagram of the assembled copper base plate, DBC plate, and limit fixture; Figure 3 This is a structural diagram of the limiting fixture; Figure 4 This is a structural diagram of the steel mesh. Detailed Implementation

[0015] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0016] Example 1 A method for producing an IGBT module with reduced voids, the IGBT module comprising a copper base plate 1 and two DBC boards 2, the copper base plate 1 being a cuboid with both ends slightly curved upwards along its length, and two DBC boards 2 being soldered to both sides of the copper base plate 1 at the midpoint along its length. Multiple crisscrossing venting grooves 101 are provided on the copper base plate at positions corresponding to the DBC boards 2, through which flux volatilized during baking escapes.

[0017] The production method specifically includes the following steps: Step 1: Load the copper base plate 1 with the air vent groove into the predetermined position; Step 2: Print solder paste on the area where DBC board 2 is placed on the copper base plate; Step 3: Place the solder paste onto DBC board 2; Step 4: Place the limiting fixture 3 on the copper base plate. The limiting fixture is used to limit the position of the DBC board 2 to prevent the position of the DBC board 3 from changing due to the flow of molten solder during the baking process. Step 5: Place the products from Step 4 into the oven and bake them. During the baking process, the solder paste melts and flows, with some flowing into the venting groove. This prevents the solder paste from accumulating and allows the volatile gases to escape from the venting groove. Step 6: After baking for the predetermined time, cool the product and remove it from the oven to obtain the IGBT module.

[0018] The stencil 4 includes a stencil plate 41 with multiple sets of slots 42. Each set of slots 42 corresponds to one IGBT module, meaning one stencil 4 can simultaneously print solder paste onto multiple IGBT modules. Each set of slots 42 has multiple slots, each corresponding to an area on the copper base plate 1 divided by venting grooves 101. The venting grooves 101 correspond to the stencil plates 41 between adjacent slots, ensuring that solder paste is not printed in the venting grooves during solder paste printing. When solder paste printing is required, the stencil 4 is moved directly above the copper base plate 1 and then downwards until it contacts the copper base plate 1. Molten solder paste is placed on the stencil plate 41. A squeegee moves across the stencil plate 41, transferring the solder paste from one side to the other. As the solder paste passes through the slots 42, some enters the slots 42 and adheres to the corresponding area on the copper base plate 1. Then, the stencil 4 is moved upwards, completing the solder paste printing.

[0019] Preferably, since the copper base plate 1 is curved, lower in the middle and higher at both ends, to ensure sufficient solder paste near the center of the copper base plate 1, the thickness of the mesh openings 42 near the center of the copper base plate 1 is set to be greater than the thickness of the mesh openings further away from the center of the copper base plate 1. However, since the molten solder will flow during baking, the thickness of the mesh openings 42 that are a predetermined distance away from the center of the copper base plate 1 is set to be thicker than the mesh openings at other locations. When printing solder paste, the thicker mesh openings contain more solder paste. Each DBC board has six mesh openings, with the thickness of the mesh opening corresponding to the center of each DBC set to 0.65 mm, and the thickness of the remaining mesh openings set to 0.4 mm.

[0020] Preferably, the limiting fixture 3 is a cuboid frame structure. Positioning holes 102 are provided at the four corners of the copper base plate 1, and positioning posts 301 are provided at the corresponding positions of the positioning holes 102 in the limiting fixture 3. The positioning posts 301 can be inserted into the positioning holes 102. Two partition plates 302 are provided inside the limiting fixture 3 at the midpoint along the length of the copper base plate 1. Multiple abutment posts 303 are provided on the inner edge of the limiting fixture 3. The two partition plates 302 are used to separate the two DBC boards, and the abutment posts 303 are used to abut against the edge of the DBC board 2 to fix the DBC board 2, preventing the DBC board from moving due to the melting and flow of solder paste during baking. The limiting fixture 3 is a high-temperature plastic part made of PA6T material.

[0021] Example 2 This embodiment describes a production equipment for IGBT modules, including: The copper base plate loading module is used to load the copper base plate to a predetermined position, and can employ existing technology. Solder paste printing module, used to print solder paste on the side of the copper base plate on which the DBC board is placed; A limiting fixture is used to limit the movement of the DBC board placed on a copper base plate; The baking module is used to bake the assembled copper base plate, solder paste, DBC board, and limiting fixture, and can employ existing technology. The solder paste printing module includes a stencil and a squeegee. The stencil includes a movable stencil plate with multiple sets of slots. Each set of slots corresponds to one IGBT module. Each set of slots has multiple slots, and each slot corresponds one-to-one with an area on the copper base plate divided by venting grooves. The venting grooves correspond to the stencil plates between adjacent slots. The squeegee is movable. The movement of the stencil and squeegee can employ existing technology.

[0022] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A production method of an IGBT module capable of reducing cavities, the IGBT module comprising a copper base plate and two DBC plates, the DBC plates being cuboids, both ends of the copper base plate in the length direction being upwardly curved, the two DBC plates being soldered to both sides of the copper base plate at a middle position in the length direction by soldering tin, a plurality of gas outlet grooves for facilitating the volatilization of flux being provided on the copper base plate at positions corresponding to the DBC plates, characterized in that, The production method specifically comprises the following steps: Step one, loading the copper base plate with gas outlet grooves to a predetermined position; Step two, printing tin paste on the area of the copper base plate where the DBC plate is placed; Step three, placing the DBC plate on the tin paste; Step four, placing a limiting jig on the copper base plate, which is used to limit the DBC plate; Step five, placing the product of step four together into an oven, which is used to bake, in the process of baking, the tin paste melts, the melted tin paste flows and part of it flows into the gas outlet groove, and the volatilized flux runs out of the gas outlet groove; Step six, cooling after baking for a predetermined time, and taking out the product from the oven after cooling to obtain the IGBT module.

2. The production method according to claim 1, characterized by, The steel mesh comprises a mesh plate, a plurality of groups of mesh openings are arranged on the mesh plate, each group of mesh openings corresponds to one IGBT module to be produced, the number of mesh openings in each group of mesh openings is multiple and corresponds to the areas on the copper base plate divided by the gas outlet grooves one by one, and the mesh plate corresponds between the gas outlet grooves and the adjacent mesh openings.

3. The production method according to claim 2, characterized by, In step two, when the tin paste needs to be printed, the steel mesh is moved to the top of the copper base plate and is moved downward to be in contact with the copper base plate, the melted tin paste is placed on the mesh plate, the tin paste is moved from one side to the other side on the mesh plate by moving the squeegee, part of the tin paste enters the mesh opening and is adhered to the corresponding area on the copper base plate when passing through the mesh opening, and then the steel mesh is moved upward to realize the printing of the tin paste.

4. The production method according to claim 3, characterized by, The thickness of the mesh openings in each group of mesh openings that are different from the middle position of the copper base plate by a predetermined distance is set to be thicker than that of the mesh openings at other positions.

5. The production method according to claim 1, characterized by, The limiting jig has a frame-shaped structure, positioning holes are arranged at the positions of the four corners of the copper base plate, positioning columns are arranged at the positions of the limiting jig corresponding to the positioning holes, the positioning columns can be inserted into the positioning holes, two partition plates are arranged inside the limiting jig and correspond to the middle positions of the copper base plate in the length direction, and a plurality of abutting columns are arranged at the inner edges of the limiting jig, the two partition plates are used to divide the two DBC plates, and the abutting columns are used to abut against the edges of the DBC plates.

6. An IGBT module characterized by comprising: The production method is prepared by any one of claims 1-5.

7. An apparatus for producing an IGBT module, characterized by comprising: The IGBT module comprises a copper base plate and two DBC plates, the DBC plates are cuboids, the two ends of the copper base plate in the length direction are upwardly curved, the two DBC plates are welded to the two sides of the middle position of the copper base plate in the length direction by soldering, a plurality of longitudinal and transverse intersecting gas outlet grooves for facilitating the volatilization of flux are arranged on the copper base plate corresponding to the positions of the DBC plates, and the production equipment comprises: A copper base plate loading module is used to load the copper base plate to a predetermined position; A tin paste printing module is used to print tin paste on one side of the copper base plate where the DBC plate is placed; A limiting jig is used to limit the DBC plate placed on the copper base plate; A baking module is used to bake the assembled copper base plate, tin paste, DBC plate and limiting jig, The tin paste printing module comprises a steel mesh and a scraper, the steel mesh comprises a movable mesh plate, a plurality of groups of mesh openings are arranged on the mesh plate, each group of mesh openings corresponds to one IGBT module, the number of mesh openings in each group of mesh openings is multiple and corresponds to the areas on the copper base plate divided by air outlet grooves one by one, the mesh plate corresponding to the air outlet grooves and the adjacent mesh openings, and the scraper is movable.

8. The apparatus for producing an IGBT module according to claim 7, wherein The thickness of the mesh openings in each group of mesh openings and having a predetermined distance from the middle position of the copper base plate is set to be thicker than that of the mesh openings at other positions.

9. The apparatus for producing an IGBT module according to claim 7, wherein The limiting jig has a frame type structure, positioning holes are arranged at the positions of the four corners of the copper base plate, positioning columns are arranged at the positions corresponding to the positioning holes of the limiting jig, the positioning columns can be inserted into the positioning holes, two partition plates are arranged at the positions corresponding to the middle positions of the copper base plate in the length direction inside the limiting jig, a plurality of abutting columns are arranged at the inner edges of the limiting jig, the two partition plates are used for dividing the two DBC plates, and the abutting columns are used for abutting against the edges of the DBC plates.

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