A packaging structure for power semiconductor module

Abstract

The present invention provides a packaging structure for a power semiconductor module, belonging to the technical field of power semiconductor module packaging structure, the structure includes a metal plate for mounting a power semiconductor, and a closed cover covering the metal plate, the inner top wall of the closed cover is pre-coated with heat dissipation silicone, the left and right sides of the closed cover each have a wedging edge, the front and rear sides thereof each have a mounting bar, the left and right sides of the metal plate each have a wedging groove, the wedging edge is wedged into the wedging groove and fixed, the mounting bar and the metal plate are fixed by a sealant, and the amount of the heat dissipation silicone must be such that after the closed cover is fixed on the metal plate, it overflows from an overflow hole on the side of the closed cover, and the overflow hole is sealed with its outer port by a closing bolt. The packaging structure for the power semiconductor module is stable and reliable, easy to package, and has excellent heat dissipation.

Description

Technical Field

[0001] The present invention relates to a power semiconductor module packaging technology. Specifically, the present invention mainly relates to a packaging structure for a power semiconductor module. Background Art

[0002] Power semiconductors are core components for power conversion and circuit control in electronic devices. They can support high voltage and high current, and realize the functions of power switching and power conversion through the unidirectional conductivity of semiconductors. The main uses of power semiconductors include frequency conversion, rectification, voltage conversion, power amplification, power control, etc., and they are often accompanied by a lot of heat during operation. Generally speaking, in addition to ensuring the normal operation of the circuit, power semiconductors can also reduce the waste of electric energy and play a role in energy saving and power saving; among them, the power semiconductor module is a module that is potted into one by combining high-power electronic power devices according to certain functions. These devices or integrated circuit chips can work at very high frequencies, and the circuit can be more energy-saving and material-saving when working at high frequencies, which can greatly reduce the size and weight of the equipment.

[0003] When power semiconductor modules are packaged, each has a corresponding design based on different functions and layout requirements. As a commonly used design structure, a sealing cover for packaging is fixedly covered on a metal plate to seal the internal power semiconductor, and then the sealing cover is directly glued and fixed to the metal plate around the edges to achieve packaging. Under this single fixed structure, after long-term use, the sealing cover is easy to fall off the metal plate, and a gap appears between the two. There are also direct mechanical socket connections or snap connections in the prior art. This fixing form is similar to the fixing of general mechanical components, and its reliability is mainly reflected by the tolerance accuracy of the interference fit. The metal plate or sealing cover used for packaging is different from the material of general mechanical components, and the size is generally much smaller. This high-precision fit is difficult to process and difficult to manufacture.

[0004] In addition, the sealing cover is not easy to position during the adhesive packaging. The pressure applied during the bonding process for reinforcement can easily cause the sealing cover to deviate, or even cause a rigid collision between the sealing cover and the power semiconductor module inside, thereby causing the power semiconductor module to shift or loosen.

[0005] In addition, in the existing packaging structure, a large amount of heat emitted by the packaged power semiconductor module cannot be transferred to the closed cover through the surrounding air in a timely manner and then transferred to the external environment, and its heat dissipation is poor. Summary of the invention

[0006] One of the technical problems to be solved by the present invention is that the sealing cover and the metal plate in the existing packaging structure are not fixed firmly enough, and the overall heat dissipation is poor. The packaging structure for the power semiconductor module can better solve this problem, achieve the technical effect of quickly and reliably fixing the packaging, and having excellent heat dissipation.

[0007] In order to achieve the above-mentioned purpose, those skilled in the art have adopted the following technical scheme: a packaging structure for a power semiconductor module, comprising a metal plate for mounting a power semiconductor, and a closing cover covering the metal plate, the inner top wall of the closing cover being pre-coated with heat dissipation silicone, the left and right sides of the closing cover each having a wedging edge, and the front and rear sides each having a mounting strip, the left and right sides of the metal plate each having a wedging groove, after the wedging edge is wedged into the wedging groove and fixed, the mounting strip is fixed to the metal plate by a sealant, and the amount of the heat dissipation silicone must be such that after the closing cover is fixed on the metal plate, it overflows from an overflow hole on the side of the closing cover, and the overflow hole is sealed at its outer port by a closing bolt.

[0008] Specifically, the cross-section of the wedged edge is V-shaped, and the cross-section of the wedged groove is also V-shaped that can fit with the wedged edge. The wedged groove has a slot on one side wall near its slot, and one end of a connecting piece is inserted into the slot. The upper surface of the connecting piece is coated with sealant, and the other end of the connecting piece is in contact with a slider in the metal plate. The slider is connected to the metal plate through a first spring, and the pushing force of the first spring on the slider causes the connecting piece to be horizontally placed between the slot and the slider and positioned across the slot of the wedged groove; when the wedged edge is vertically inserted into the wedged groove, the connecting piece is bent into a V shape and fits tightly against the wedged edge.

[0009] The inner surface of the wedging edge of the present invention has a two-level step structure, the first-level step surface of the two-level step structure is in contact with the surface of the metal plate, and the second-level step surface is bonded to the sealant on the connecting piece.

[0010] The metal plate is provided with an installation cavity adjacent to the wedging groove and close to the outside of the sealing cover, the first spring is horizontally installed in the installation cavity, the free end of the first spring is connected to a slide plate, the slide plate and the slider are vertically slidably matched, the slide plate can slide horizontally in the installation cavity under the action of the first spring, and is always in compression contact with the side wall of the slider; the slider has a fitting surface that can fit with the side wall of the connection piece after being pressed and bent, and the bottom of the slider is in horizontal sliding contact with the bottom of the installation cavity through the second spring;

[0011] When the connecting piece is horizontally placed on the wedged groove, the top end of the slider is squeezed into contact with the inner top wall on one side of the cavity opening of the installation cavity and is kept fixed under the action of the connecting piece. When the connecting piece is bent, the slider slides horizontally out of the inner top wall under the thrust of the first spring and pops out of the installation cavity.

[0012] Specifically, a positioning platform is provided on the contact surface of the slider, and when the connecting piece is in a horizontally placed position, the other end of the connecting piece is pressed and contacted on the positioning platform. A horizontally arranged limiting contact surface is provided at the root of the outer side wall of the wedging edge, and when the contact surface contacts the side wall of the connecting piece, the top of the slider is fixedly contacted with the limiting contact surface.

[0013] There is a screw hole at one end of the two mounting strips, and two positioning studs are arranged on the metal plate. The two screw holes are respectively used for the positioning studs to pass through, and the two studs are not located on the same side. The optical axis section of the stud slides with the screw hole to achieve the socket positioning of the wedging edge and the wedging groove; a locking nut for squeezing the mounting strip is screwed on the stud. An inclined threaded hole is arranged on the side wall of the closure cover, and the threaded hole is used for the installation of the closure bolt, and one end of the threaded hole facing the closure cover is lower than the other end.

[0014] The cavity opening of the above installation cavity is detachably provided with a cover plate, which can cover the cavity opening, and one end of the cover plate is in contact with a connecting piece attached to the side wall of the wedged edge.

[0015] Compared with the prior art, the invention has the following beneficial effects: the invention uses the wedging grooves on the metal plate on the left and right sides through the wedging edges to achieve rapid installation, the structure is simple and easy to use, and the stamping bending deformation force of the connecting piece pre-inserted and positioned at one end is used to quickly adhere to the surface of the wedging edge and bond with it, and then the slider is fastened by two elastic forces in perpendicular directions to quickly fix the closure cover on the metal plate, and the bonding of the mounting strip cooperates to fully, quickly and reliably fix the closure cover on the metal plate. At the same time, the heat dissipation silicone in the closure cover overflows, so that the heat dissipation silicone pre-coated inside can fully wrap the power semiconductor module on the metal plate, firstly, the heat dissipation is good, secondly, the power semiconductor chip is further fixed, and thirdly, the power semiconductor chip has a protective effect of buffering and shock absorption.

[0016] As for other positive effects, advantages, and optimized technical features of the present invention, they will be illustrated through detailed elaboration of subsequent specific embodiments. Some technical features still require general technicians in this field to fully study and practice the present invention in order to be better understood and applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A front view of the packaging structure of the power semiconductor module of the present invention;

[0018] Figure 2 This is a diagram of the socket-fit installation structure between the right side of the closure cover and the metal plate;

[0019] Figure 3 This is a diagram showing the matching positions of the wedging edge and the wedging groove at the beginning of the installation of the closure cover;

[0020] Figure 4 A bottom view of the closure cover.

[0021] Among them, the metal plate 1, the power semiconductor chip 2, the pre-coated heat dissipation silicone layer 3, the gap 301, the heat dissipation silicone 4, the closing cover 5, the wedging edge 501, the first step 502, the second step 503, the limiting plane 504, the positioning stud 6, the wedging groove 7, the connecting piece 8, the sealing rubber layer 9, the slider 10, the slide plate 11, the second spring 12, the first spring 13, the installation cavity 14, the cover plate 15, the closing bolt 16, the installation strip 17, and the screw hole 18. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the principle of the present invention will be explained in depth with reference to the accompanying drawings and at least one detailed embodiment. Those skilled in the art should be aware that the specific embodiments described below are only intended to explain the technical principles of the present invention, and are not intended to limit the present invention to be implemented in this way.

[0023] like Figure 1As shown, this embodiment proposes a packaging structure for a power semiconductor module, the main structure of which includes a metal plate 1 for mounting a power semiconductor, the metal plate 1 is preferably made of a material with good heat dissipation performance, and also has a closed cover 5 covering the metal plate 1. When the closed cover 5 is actually manufactured, it can be a rectangular cover structure. During implementation, the inner top wall of the closed cover 5 is pre-coated with heat dissipation silica gel 4, which can be concentratedly brushed at a certain position of the inner top wall, so that the glue coating time is shorter and the installation is faster. In addition, continue to refer to coating 1, there is a wedging edge 501 on the left and right sides of the closed cover 5, and a mounting strip 17 on the front and rear sides of the closed cover 5, which can be integrally formed with the metal plate 1. The mounting strip 17 can be a structure with a rectangular cross section, and a wedging groove 7 is provided on the left and right sides of the metal plate 1. During packaging, after the wedging edge 501 is wedged into the wedging groove 7 and fixed, the mounting strip 17 and the metal plate 1 are fixedly connected by a sealant to achieve the fixation of the front and rear sides of the closed cover 5 with the metal plate 1. The sealant here can be a heat dissipation silica gel. As one of the important design points, the amount of heat dissipation silicone 4 applied to the top wall of the sealing cover 5 in this embodiment must be such that after the sealing cover 5 is fixed on the metal plate 1, it can overflow from an overflow hole on the side of the sealing cover 5. In this way, it can be ensured that when the sealing cover 5 is pressed down and covered on the metal plate 1, it can be fixedly assembled, and the corresponding components of the power semiconductor, such as the power semiconductor chip 2, are fully and reliably sealed in the heat dissipation silicone 4, which not only plays a good heat dissipation role, but also plays a good buffering and shock absorbing role. In order to close the sealing cover 5, the overflow hole is sealed at its outer port by a closing bolt 16. The closing bolt 16 here also has two functions. On the one hand, it blocks the overflow hole itself, and on the other hand, it can further extrude the heat dissipation silicone 4 in the sealing cover 5, so that it can more densely wrap the power semiconductor chip 2 and other related components. In actual production, since there may be a situation where multiple chips are stacked, such as Figure 1 As shown, the two chips are previously bonded together by heat dissipation silicone 4 to form a sandwich layer 3 pre-coated with heat dissipation silicone 4, and all the chips become a whole, because during assembly, the bottom chip can be directly bonded to the metal plate 1 by heat dissipation silicone 4, and then covered with a sealing cover 5 for packaging. In order to improve the tightness of the installation, in practice, the heat dissipation silicone 4 between the two adjacent chips is not fully coated in advance, so that when the sealing cover 5 is pressed down, the heat dissipation silicone 4 later coated on the inner top wall of the sealing cover 5 can flow into the gap 301 between the two adjacent chips near the edge, so that the chip is more reliably fixed in the sealing cover 5.

[0024] As one of the specific implementation structures, such as Figure 2-4The cross section of the wedging edge 501 is roughly V-shaped, and the cross section of the wedging groove 7 is also a V-shaped structure that can be socket-fitted with the wedging edge 501, so that the two can be positioned and connected in a socket-fitted manner. Specifically, the wedging groove 7 has a slot on one side wall near its slot, and this slot can be a horizontally set blind hole with a shape consistent with the connecting piece 8 mentioned later. This slot is for one end of a connecting piece 8 to be inserted to achieve the pre-positioning and positioning of the connecting piece 8, and a sealant layer 9 is coated on the upper surface of the connecting piece 8. This layer of sealant is mainly used for subsequent contact and bonding with the above-mentioned wedging edge 501. The other end of the connecting piece 8 is in contact with a slider 10 in the metal plate 1, and the slider 10 is connected to the metal plate 1 by a first spring 13, that is, the slider 10 can be elastically telescopically moved horizontally, and the thrust of the first spring 13 on the slider 10 causes the connecting piece 8 to be horizontally placed between the slot and the slider 10, and as shown Figure 3 As shown, it crosses the upper end surface of the notch of the wedging groove 7. During packaging, after the wedging edge 501 is vertically inserted into the wedging groove 7 to the limit, the connecting piece 8 is bent into a V shape and closely adheres to the wedging edge 501. Since one end of the connecting piece 8 has been inserted and installed in the above-mentioned slot, the other end, when turned upward, closely adheres to the outer side wall of the wedging edge 501, clamping the outer side wall and further bonding them together because of the pre-applied sealant.

[0025] More specifically, if Figure 2-3 The inner surface of the wedged edge 501 has a secondary step 503 structure, the primary step 502 surface of the secondary step 503 structure is in contact with the surface of the metal plate 1, and the secondary step 503 surface is bonded to the sealant on the connecting piece 8, thereby improving the installation tightness of the connecting piece 8 at one end of the slot. In practice, during the manufacturing process, a mounting cavity 14 adjacent to the wedging groove 7 and close to the outer side of the closing cover 5 is provided on the metal plate 1, and a first spring 13 is horizontally installed in the mounting cavity 14, and a slide plate 11 is connected to the free end of the first spring 13, and the slide plate 11 and the slider 10 are vertically slidably matched, for example, the slide plate 11 and the slider 10 are matched through a T-shaped slide groove, so that when the slide plate 11 slides vertically relative to the slider 10, it never separates from the slider 10, and the slide plate 11 can slide horizontally in the mounting cavity 14 under the action of the first spring 13, and is always in compression contact with the side wall of the slider 10; the slider 10 has a fitting surface that can fit with the side wall of the bent connecting piece 8, so as to press the connecting piece 8 from the outside toward the wedging edge 501, and the bottom of the slider 10 is in horizontal sliding contact with the bottom of the mounting cavity 14 through the second spring 12, so that when the slider 10 approaches the wedging edge 501 and is about to contact and fit, it pops out vertically from the cavity mouth of the mounting cavity 14. In this embodiment, at the beginning of packaging, when the connecting piece 8 is placed horizontally on the wedging groove 7, Figure 3, the top end of the slider 10 is pressed and contacted with the inner top wall on one side of the cavity opening of the installation cavity 14, and is kept fixed by the action of the connecting piece 8. When the connecting piece 8 is bent downward, the slider 10 slides out horizontally under the thrust of the first spring 13. After the slider 10 is exposed from the inner top wall, it is gradually ejected vertically out of the installation cavity 14 until the fitting surface of the slider 10 finally contacts the side wall of the bent connecting piece 8. In order to pre-place the connecting piece 8, a positioning sink is specially provided on the fitting surface of the slider 10. When the connecting piece 8 is in a horizontal rest position, its other end is pressed and contacted on the positioning sink so as to be subjected to horizontal force. In addition, if Figure 2 A horizontally arranged limiting contact surface is provided at the root of the outer side wall of the wedged edge 501. When the fitting surface contacts the side wall of the connecting piece 8, the top of the slider 10 fits and is fixed with the limiting contact surface, thereby combining the elastic force of the first spring 13 to make the connecting piece 8 close to the wedged edge 501, and then the wedged edge 501 is fixed on the metal plate 1. Compared with the traditional quick-installation method of directly plugging or buckling the closing cover 5 on the metal plate 1, this structure has multiple fastening forces and multiple properties of fastening forces, and is more firm and reliable.

[0026] As a recommended structure, Figure 2 As shown, the opening of the installation cavity 14 in the above embodiment is detachably mounted with a cover plate 15, which can be fixed by screws. The cover plate 15 can cover the opening of the cavity, and one end of the cover plate 15 contacts and contacts the connecting piece 8 attached to the side wall of the wedging edge 501, thereby fixing the wedging edge 501 in the wedging groove 7 to the maximum extent, that is, the closing cover 5 is fixed on the metal plate 1. When it is necessary to disassemble and repair, it is only necessary to disassemble the cover plate 15, and then pull the corresponding springs in the direction away from the slider 10 to expose the end of the connecting piece 8, insert a flat screwdriver between the connecting piece 8 and the wedging edge 501, pry open one end of the connecting piece 8, and then sequentially separate the connecting piece 8 and the wedging edge 501, so as to separate the closing cover 5.

[0027] In order to quickly position the closure 5, Figure 1 A screw hole 18 may be provided at one end of the two mounting strips 17, and two positioning studs 6 are provided on the metal plate 1. The two screw holes 18 are respectively used for the optical axis sections of the positioning studs 6 to pass through, and the two studs are not located on the same side. The optical axis section of the stud 6 is slidably matched with the screw hole 18, so as to pre-position the closing cover 5, and then realize the socket positioning of the wedging edge 501 and the wedging groove 7. A locking nut for squeezing the mounting strip 17 is screwed on the stud, so that after the closing cover 5 is buckled on the metal plate 1, the locking nut can be tightened to further fix it.

[0028] To block the overflow of the heat dissipation silica gel 4, it can be as follows Figure 2As shown, an inclined threaded hole is provided on the side wall of the closing cover 5, and the threaded hole is used to install the closing bolt 16, and one end of the threaded hole facing the closing cover 5 is lower than the other end thereof, so as to avoid the heat dissipation silica gel 4 from flowing out in a non-overflowing form as much as possible.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. A series of detailed descriptions of the embodiments of the present application, as for the specific examples used in the present application, have been described in detail on the technical principles and implementation methods of the present application. They are only used to help those skilled in the art to have an in-depth and comprehensive understanding of the design concept of the present application, and should not be understood as a sole or selective limitation on the technical principles of the present application. As for the detailed description of the present invention by the preferred embodiments mentioned in the present application, a person of ordinary skill in the art should be able to make simple modifications to the technical solutions of the present invention or replace them with equivalent means on the basis of these preferred embodiments, but the core technical principles should be covered in the scope of protection embodied in the claims of the present invention without departing from the technical ideas, design purposes and scope of application of the present invention.

Claims

1. A packaging structure for a power semiconductor module, comprising a metal plate (1) for mounting a power semiconductor, and a sealing cover (5) covering the metal plate (1), Features: The inner top wall of the closure cover (5) is pre-coated with heat dissipation silica gel (4), the left and right sides of the closure cover (5) are each provided with a wedging edge (501), and the front and rear sides thereof are each provided with a mounting strip (17), the left and right sides of the metal plate (1) are each provided with a wedging groove (7), after the wedging edge (501) is wedged into the wedging groove (7) and fixed, the mounting strip (17) and the metal plate (1) are fixedly connected by means of a sealant, and the amount of the heat dissipation silica gel (4) must be such that after the closure cover (5) is fixed on the metal plate (1), it overflows from an overflow hole on the side of the closure cover (5), and the overflow hole is sealed at its outer end by a closing bolt (16); The cross section of the wedging edge (501) is V-shaped, and the cross section of the wedging groove (7) is also V-shaped that can be plugged into the wedging edge (501). The wedging groove (7) has a slot on one side wall near its slot opening, and one end of a connecting piece (8) is inserted into the slot. The upper surface of the connecting piece (8) is coated with a sealant. The other end of the connecting piece (8) contacts a slider (10) in the metal plate (1). The slider (10) is connected to the metal plate (1) through a first spring (13), and the first spring (13) pushes the slider (10) so that the connecting piece (8) is horizontally placed between the slot and the slider (10) and is located across the slot opening of the wedging groove (7). When the wedging edge (501) is vertically inserted into the wedging groove (7), the connecting piece (8) is bent into a V shape and is tightly attached to the wedging edge (501).

2. A packaging structure for a power semiconductor module according to claim 1, Features: The inner surface of the wedged edge (501) has a secondary step (503) structure, the primary step (502) surface of the secondary step (503) structure is in contact with the surface of the metal plate (1), and the secondary step (503) surface is bonded to the sealant on the connecting piece (8).

3. The packaging structure for a power semiconductor module according to claim 1, Features: The metal plate (1) is provided with a mounting cavity (14) adjacent to the wedge groove (7) and close to the outside of the closing cover (5); the first spring (13) is horizontally mounted in the mounting cavity (14); the free end of the first spring (13) is connected to a slide plate (11); the slide plate (11) and the slider (10) are vertically slidably matched; the slide plate (11) can slide horizontally in the mounting cavity (14) under the action of the first spring (13) and is always in compression contact with the side wall of the slider (10); the slider (10) has a fitting surface that can fit with the side wall of the bent connecting piece (8); the bottom of the slider (10) is in horizontal sliding contact with the bottom of the mounting cavity (14) through the second spring (12); When the connecting piece (8) is horizontally placed on the wedged groove (7), the top end of the slider (10) is pressed into contact with the inner top wall on one side of the cavity opening of the installation cavity (14) and is kept fixed under the action of the connecting piece (8); when the connecting piece (8) is bent, the slider (10) slides horizontally out of the inner top wall under the thrust of the first spring (13) and pops out of the installation cavity (14).

4. A packaging structure for a power semiconductor module according to claim 3, Features: The fitting surface of the sliding block (10) is also provided with a positioning sink. When the connecting piece (8) is in a horizontally placed position, the other end of the connecting piece (8) is located on the positioning sink in a pressed contact manner.

5. The packaging structure for a power semiconductor module according to claim 3, Features: A horizontally arranged limiting contact surface is provided at the root of the outer side wall of the wedged edge (501), and when the fitting surface contacts the side wall of the connecting piece (8), the top of the sliding block (10) fits against the limiting contact surface and is fixed.

6. The packaging structure for a power semiconductor module according to claim 1, Features: A screw hole (18) is provided at one end of the two mounting strips (17); two positioning studs (6) are provided on the metal plate (1); the two screw holes (18) are respectively used for the positioning studs (6) to pass through, and the two studs are not located on the same side; the optical axis section of the stud is slidably matched with the screw hole (18) to achieve the socket positioning of the wedging edge (501) and the wedging groove (7); a locking nut for squeezing the mounting strip (17) is screwed on the stud.

7. The packaging structure for a power semiconductor module according to claim 1, Features: An inclined threaded hole is provided on the side wall of the closing cover (5), the threaded hole is used for installing the closing bolt (16), and one end of the threaded hole facing the inside of the closing cover (5) is lower than the other end thereof.

8. The packaging structure for a power semiconductor module according to claim 3, Features: A cover plate (15) is detachably mounted on the cavity opening of the installation cavity (14); the cover plate (15) can cover the cavity opening and abut against a connecting piece (8) attached to the side wall of the wedging edge (501).

9. A packaging structure for a power semiconductor module according to claim 8, Features: One end of the cover plate (15) is fixedly connected to the metal plate (1) by means of screws, and the other end of the cover plate (15) is in contact with the connecting piece (8).

Images