Power device frame
By designing the side heat dissipation structure, including the heat dissipation groove and the heat dissipation fin in the TO-247plus package, the problem of insufficient heat dissipation performance of the package is solved, and better heat dissipation effect and device reliability are achieved.
Patent Information
- Application Number
- CN202421504428.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-28
- Publication Date
- 2025-06-03
- Estimated Expiration
- 2034-06-28
AI Technical Summary
The thermal performance of the TO-247plus package is limited, especially in multi-chip and compact designs, resulting in the risk of thermal failure of the chip.
A power device frame is designed, including a chip placement area, a heat sink and a heat dissipation fin, and a side heat dissipation structure is added to guide heat to dissipate from the side and reduce the junction-to-shell thermal resistance of the device.
By increasing the side heat dissipation structure, the heat dissipation performance of the device is improved, the device temperature is reduced, and the package reliability and compactness are improved.
Smart Images
Figure CN222939925U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductors, in particular to a power device framework. Background Art
[0002] In power device products, TO-247 packaging is widely used. Currently, the commonly used framework structure in the industry for TO-247 packaging is a three-pin structure with a metal backplane. The three pins are usually referred to as pin 1, pin 2, and pin 3. Pin 2 is connected to the pad, and the pad mainly provides a heat dissipation function. There is an opening with a radius of 3.3 - 3.8 mm (slightly different for different manufacturers) in the middle of the upper half of the TO-247 framework pad, which is convenient for fixing it to the heat sink with screws. When in use, the screw holes of the device and the heat sink need to be aligned first, and then screws are driven. At the same time, the torque needs to be considered. The TO-247 packaging size is between that of a module and a single transistor, and it can package most electronic components. In the fields of diodes, triodes, MOSFETs, IGBTs, thyristors, power modules, etc., the processes and technologies have become relatively perfect, and the reliability of this packaging has been widely recognized.
[0003] With the continuous development of silicon carbide and IGBT towards high power, the required chip area is getting larger and larger. For this reason, TO-247plus packaging has been introduced. After canceling the installation holes, the heat dissipation area in contact with the outside at the back of TO-247plus has increased by 10% - 20% compared with TO-247 packaging. However, the area for placing chips on the front pad has increased by more than 30%. TO-247plus has a larger pad to place chips. If the heat dissipation performance cannot be improved, it will lead to the risk of chip thermal failure. However, the existing packaging structure can only rely on backside heat dissipation, and the backside heat dissipation area of TO-247plus has reached the limit. For this packaging, the heat dissipation performance limits multi-chip and more compact design schemes. Summary of the Utility Model
[0004] The utility model aims at the above problems and provides a power device framework with a delicate structure and improved heat dissipation performance of the packaged device.
[0005] The technical solution of the utility model is as follows:
[0006] A power device framework, comprising:
[0007] A chip placement area, arranged on the front of the framework;
[0008] A heat dissipation groove, located at the top of the framework; and
[0009] Heat dissipation fins, arranged on the side of the framework.
[0010] Specifically, an anti-overflow groove is provided at the edge of the chip placement area; the chip is arranged in the anti-overflow groove.
[0011] Specifically, the heat dissipation groove is semi-closed.
[0012] Specifically, the heat dissipation groove is located at the top corner of the frame.
[0013] Specifically, the heat dissipation fins are located on the front of the frame, outside the chip placement area.
[0014] Specifically, the heat dissipation fins are in a C-shaped structure.
[0015] Specifically, the bottom of the frame is provided with second pins extending downward.
[0016] Advantages of the present utility model:
[0017] Currently, the encapsulation of surface mount devices mainly dissipates heat through a bottom heat sink, and there are also a small number of designs with a top heat dissipation structure. Due to the large size of the TO-247 package, for wire bonding devices, the top heat dissipation cannot be used. In this case, a TO-247 frame structure with a side heat dissipation structure is designed. This frame adds two small vertical structures at the top, namely the heat dissipation grooves in this case, and two larger embedded vertical structures on the side, namely the heat dissipation fins in this case, which can guide the heat to dissipate from the side and reduce the thermal resistance from the junction to the case of the device. Description of the drawings
[0018] Figure 1 It is a three-dimensional structure schematic diagram of step S110;
[0019] Figure 2 It is a three-dimensional structure schematic diagram of step S120;
[0020] Figure 3 It is a three-dimensional structure schematic diagram of step S130;
[0021] Figure 4 It is a three-dimensional structure schematic diagram of the 90° bending of the copper fin plate in step S140;
[0022] Figure 5 It is a three-dimensional structure schematic diagram of the die shaping in step S140;
[0023] Figure 6 It is a three-dimensional structure schematic diagram of forming the heat dissipation groove and the heat dissipation fin in step S140;
[0024] Figure 7 It is a three-dimensional structure schematic diagram of punching out a long strip at the edge;
[0025] Figure 8 It is a three-dimensional structure schematic diagram of step S200;
[0026] Figure 9 It is a three-dimensional structure schematic diagram of step S300;
[0027] Figure 10 It is a schematic three-dimensional structure of the connection state between the device and the circuit board Figure 1 ;
[0028] Figure 11 It is a schematic three-dimensional structure of the connection state between the device and the circuit board Figure 2 ;
[0029] Figure 12 It is a device temperature test diagram without air convection, only considering the case of air thermal expansion and rising
[0030] Figure 13 It is a device temperature test diagram with an air flow rate of 5 m / s and the direction blowing from the top of the device to the pins
[0031] Figure 14 It is a device temperature test diagram with an air flow rate of 1 m / s and the direction blowing from the top of the device to the pins
[0032] In the figure, 100 is the frame, 110 is the chip placement area, 111 is the anti-overflow groove, 120 is the heat dissipation groove, 121 is the heat dissipation protrusion, 122 is the long strip opening, 130 is the heat dissipation fin, 131 is the rectangular hole
[0033] 200 is the chip
[0034] 310 is the first pin, 320 is the second pin, 330 is the third pin
[0035] 400 is the plastic package
[0036] 500 is the circuit board
[0037] 600 is the radiator, 610 is the fixing base, 611 is the fixing plate, 612 is the pressing foot Detailed implementation manners
[0038] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention
[0039] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In the description of the present utility model, unless otherwise specified, the meaning of "a plurality of" is two or more than two.
[0040] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.
[0041] The following refers to Figure 1-14 describe the present utility model;
[0042] A power device frame, or a TO-247plus package frame for short, includes:
[0043] A chip placement area 110, which is arranged on the front of the frame;
[0044] A heat dissipation groove 120, which is located at the top of the frame and is used for assisting heat dissipation and enhancing the plastic packaging strength; and
[0045] Heat dissipation fins 130, which are arranged on the side of the frame.
[0046] In this case, the heat dissipation groove 120 and the heat dissipation fins 130 not only improve the heat dissipation performance of the device, but also are used for plastic packaging positioning.
[0047] The frame 100 is further optimized:
[0048] An anti-overflow groove 111 is provided at the edge of the chip placement area 110; the chip 200 is arranged in the anti-overflow groove 111.
[0049] A second lead 320 extending downward is provided at the bottom of the frame. The first lead 310 and the third lead 330 are symmetrically distributed on the sides of the second lead 320 respectively.
[0050] The heat dissipation groove 120 is further defined:
[0051] The heat dissipation groove 120 is in a semi-closed shape.
[0052] The heat dissipation grooves 120 are located at the top corners of the frame, and in this case, there are a pair of heat dissipation grooves 120.
[0053] The heat dissipation fins 130 are further defined as follows:
[0054] The heat dissipation fins 130 are located on the front of the frame, outside the chip placement area 110.
[0055] The heat dissipation fins 130 are in a C-shaped structure.
[0056] In this case, both the heat dissipation grooves 120 and the heat dissipation fins 130 are provided with glue-locking holes to improve the bonding strength with the plastic package.
[0057] The package further includes:
[0058] A chip 200, which is arranged in the chip placement area 110; the distance between the chip 200 and the edge of the anti-overflow groove 111 is not less than 1.5 mm to reduce the risk of water vapor intrusion;
[0059] A first pin 310, which is arranged at intervals at the bottom of the frame 100 and is electrically connected to the chip 200 through a bonding wire;
[0060] A third pin 330, which is arranged at intervals at the bottom of the frame 100, is located at the side of the first pin 310, and is electrically connected to the chip 200 through a bonding wire;
[0061] A plastic package 400, which wraps the chip 200, and its side is connected to the heat dissipation fins 130, and the top is connected to the heat dissipation grooves 120.
[0062] Specifically, the outer regions of the heat dissipation fins 130 and the heat dissipation grooves 120 are respectively exposed outside the plastic package 400. In this case, the back of the frame 100 is exposed outside the plastic package 400.
[0063] Currently, the heat dissipation of surface mount devices is mainly through the bottom heat sink, and there are also a small number of designs with a top heat dissipation structure. Since the TO-247 package has a large size, for wire bonding devices, the top heat dissipation cannot be used. In this case, a TO-247 frame structure with a side heat dissipation structure is designed. This frame adds two small vertical structures at the top, namely the heat dissipation grooves 120 in this case, and two larger embedded vertical structures on the side, namely the heat dissipation fins 130 in this case, which can guide the heat to dissipate from the side and reduce the junction-to-case thermal resistance of the device.
[0064] The assembly component includes:
[0065] A circuit board 500, and the pins of the package are inserted into the corresponding electrode sockets of the circuit board.
[0066] The back of the package in this case is detachably and fixedly connected to the radiator 600 to improve the heat dissipation efficiency.
[0067] The back surface of the package is detachably and fixedly connected to the radiator 600. For example:
[0068] A fixing seat 610 is provided on the bottom plate of the radiator 600; the fixing seat 610 includes:
[0069] A fixing plate 611, which is arranged on the fin side of the radiator 600;
[0070] There are several pressing feet 612, each of which has an L-shaped structure. One end is connected to the fixing plate 611, and the other end extends to one side of the package through the fixing plate 611. By rotating the bolts in the middle of the fixing plate 611, the several pressing feet 612 are fixedly connected to the package. In this case, the materials of the fixing plate 611 and the pressing feet 612 are both copper alloy materials.
[0071] In this case, the positions and quantities of the pressing feet 612 are corresponding to the positions of the heat dissipation grooves 120 and the heat dissipation fins 130, that is, four pressing feet 612 are provided in this case, two of which are pressed in the heat dissipation grooves 120, and the other two are pressed in the heat dissipation fins 130.
[0072] The preparation method of the assembly component includes the following steps:
[0073] S100, the preparation of the frame; the frame can be made of a copper alloy plate;
[0074] S110, using a stamping die, stamp out a heat dissipation protrusion 121 extending towards the chip placement area 110 on the top of the frame 100, as Figure 1 shown;
[0075] Specifically, a long strip opening 122 is stamped out at the edge of the back surface of the frame 100 through a die, as Figure 7 shown, which is used to enhance the bonding force between the frame 100 and the plastic package 400, thereby enhancing the product reliability;
[0076] S120, stamp the upper surface of the pad of the frame 100 to prepare an anti-overflow groove 111 outside the chip placement area 110, and open a rectangular hole 131 on the inner side edge of the copper fin plate used to prepare the heat dissipation fin 130;
[0077] Specifically, opening the rectangular hole 131 facilitates the bending and forming of the heat dissipation fin 130, and the anti-overflow groove 111 can effectively prevent the overflow of the soft solder and enhance the bonding force between the frame 100 and the plastic package 400;
[0078] S130, cut the heat dissipation protrusion 121 to form a preliminary heat dissipation groove 120, as Figure 3 shown;
[0079] Specifically, the inner sidewall of the heat dissipation groove 120 protrudes from the front surface of the frame 100. The height of the inner sidewall is 1 mm and it is perpendicular to the front surface of the frame 100. The wall thickness of the inner sidewall is 0.3 mm. The inner sidewall of the heat dissipation groove 120 in this case has a polygonal structure, which increases the heat dissipation area. The protruding inner sidewall can ensure that the device is protected from water vapor intrusion while the larger surface area enhances the bonding force with the plastic package 400.
[0080] S140, as Figure 4 shown, bend the copper fin plate by 90° so that it is perpendicular to the frame 100; as Figure 5 shown, shape the frame through a mold to form the heat dissipation groove 120 and the heat dissipation fins 130, as Figure 6 shown;
[0081] Specifically, the thickness of the copper fin plate is 0.5 mm. In order to further enhance the bonding strength between the heat dissipation structure and the plastic package 400, a plurality of glue locking holes are added on the sidewalls of the heat dissipation groove 120 and the heat dissipation fins 130.
[0082] S200, die bonding and wire bonding, as Figure 8 shown;
[0083] S210, use soft solder to weld the chip 200 to the chip placement area 110;
[0084] S220, use ultrasonic welding to weld the aluminum wire to the upper surface of the chip and the first pin 310 and the second pin 330 to obtain the assembled frame 100;
[0085] S300, plastic encapsulation and lead frame trimming.
[0086] Plastic encapsulate the assembled frame 100 and cut off the redundant frame metal to form a complete device wrapped by plastic encapsulation material, that is, the TO-247plus package.
[0087] After the TO-247plus package is finished, it is assembled with the circuit board 500:
[0088] As Figure 10 shown, insert the three pins into the sockets of the circuit board 500, and the back surface of the frame 100 contacts the radiator 600 to improve the heat dissipation performance of the device; the TO-247plus package is snapped into the four press feet 612 and tightened with screws to press the device tightly on the radiator 600.
[0089] The structural design of the press feet 612 made of metal can enhance the side heat dissipation while contacting the radiator 600 and also play a role in fixing the device. When fixed from the back with screws, after the screws are tightened, the press feet press the device tightly on the heat dissipation bottom plate. At the same time, the structure of this case avoids the screw stress acting on the plastic package 400 and affecting the chip.
[0090] The conventional package and the improved TO-247plus frame in the present utility model are simulated and verified. The materials of the two packaged models are set to be the same, and the power applied to the two internal chips is 3W. Figure 12 For the stable device temperatures of the two devices when the chip power is 3W, the external environment is 25°C, there is no air convection, and only the air thermal expansion rising is considered. It is found by comparison that the chip temperature of the conventional package is 211.6°C, and the improved package of the present utility model is 210.9°C.
[0091] Figure 13 For the stable device temperatures of the two devices when the chip power is 3W, the external environment is 25°C, the air flow rate is 5m / s, the direction is from the top of the device to the pins, and the air thermal expansion rising is considered at the same time. The chip temperature of the conventional package is 95.1°C, and the chip temperature of the improved package of the present utility model is 91.2°C. In the case of external air flow, the improved package of the present utility model has better heat dissipation efficiency to the outside, and the higher the air flow rate, the higher the heat dissipation efficiency.
[0092] Figure 14 For the stable device temperatures of the two devices when the chip power is 3W, the external environment is 25°C, the air flow rate is 1m / s, the direction is from the top of the device to the pins, and the air thermal expansion rising is considered at the same time. Calculate the thermal resistance of the two packages.
[0093]
[0094] The thermal resistance from the junction to the case of the conventional package is: (146.57 - 137.33) / 6 = 1.54°C / W
[0095] The thermal resistance from the junction to the case of the improved package of the present utility model is: (145.25 - 136.34) / 6 = 1.485°C / W
[0096] Compared with the conventional package, the thermal resistance from the junction to the case of the improved package of the present utility model is reduced by about 4%.
[0097] For the content disclosed in this case, the following points need to be explained:
[0098] (1). The attached drawings of the embodiments disclosed in this case only relate to the structures involved in the embodiments disclosed in this case, and other structures can refer to the usual designs;
[0099] (2). Without conflict, the embodiments disclosed in this case and the features in the embodiments can be combined with each other to obtain new embodiments;
[0100] The above is only the specific implementation manners disclosed in this case, but the protection scope of this disclosure is not limited thereto. The protection scope disclosed in this case shall be subject to the protection scope of the claims.
Claims
1. A power device frame, characterized in that: include: A chip placement area (110) is arranged on the front side of the frame; A heat sink (120) located at the top of the frame; and The heat dissipation fins (130) are arranged on the side of the frame.
2. The power device frame according to claim 1, characterized in that: An anti-overflow groove (111) is provided at the edge of the chip placement area (110); the chip (200) is arranged in the anti-overflow groove (111).
3. The power device frame according to claim 1, characterized in that: The heat dissipation slot (120) is in a semi-closed shape.
4. The power device frame according to claim 1, characterized in that: The heat dissipation slot (120) is located at the top corner of the frame.
5. The power device frame according to claim 1, characterized in that: The heat dissipation fins (130) are located on the front side of the frame and outside the chip placement area (110).
6. The power device frame according to claim 1, characterized in that: The heat dissipation fins (130) are in a C-shaped structure.
7. The power device frame according to claim 1, characterized in that: A second pin (320) extending downward is provided at the bottom of the frame.