Patent Publication Number: US-2022223506-A1

Title: Lead frame, packaged integrated circuit board, power chip, and circuit board packaging method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2020/117850, filed on Sep. 25, 2020, which claims priority to Chinese Patent Application No. 201910944602.5, filed on Sep. 30, 2019. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of integrated circuit packaging technologies, and in particular, to a lead frame for circuit board packaging, a packaged integrated circuit board, and a packaging method for packaging a circuit board by using the lead frame. 
     BACKGROUND 
     With development of communications technologies, a demand for a power circuit that supplies power to a communications apparatus is also increasing. To implement power conversion with relatively high efficiency, a printed circuit board (PCB) of the power circuit includes a relatively large quantity of electronic components, but a use environment of the power circuit is increasingly severe. For example, the power circuit is required to occupy a smaller area, and have stronger anti-corrosion and anti-radiation capabilities. Currently, the following solution is used: The printed circuit board of the power circuit is directly plastically packaged by being covered with a plastic packaging material, and then a pin for a conductive connection is connected to a conductive pad exposed by grinding a part of the plastic packaging material. However, in this manner of directly plastically packaging the printed circuit board and then connecting the pin, the plastic packaging material and the printed circuit board are prone to be cracked, causing a failure in the plastic packaging of the power circuit. Therefore, safety and reliability are relatively low. 
     SUMMARY 
     A technical problem to be resolved in embodiments of this application is to provide a circuit board packaging solution for improving safety and reliability. The packaging solution includes a lead frame for circuit board packaging, a packaged integrated circuit board, a power chip, and a circuit board packaging method. 
     The packaging method includes the following steps: 
     providing a circuit board, where the circuit board includes a first base board, the first base board includes a first base surface and a second base surface that are opposite, and a plurality of electronic components, a plurality of conductive lines, and a plurality of conductive connection pads are disposed on each of the first base surface and the second base surface; 
     providing a lead frame, where the lead frame includes a plurality of frame units disposed in parallel in a first direction, the frame unit includes a hollow bezel, a plurality of pins, and connecting ribs, each pin includes a first pin part and a second pin part that extend in a same direction and that are integrally formed, the first pin part is disposed in the bezel, the second pin is connected and fastened to the bezel, and the connecting rib is connected between the first pin part and the bezel; 
     fastening and connecting the circuit board to the lead frame, where the circuit board is correspondingly disposed in a hollow part in the lead frame, and the conductive connection end is correspondingly connected and fastened to the first pin part; 
     plastically packaging the circuit board and the first pin part, to form a packaging casing and obtain a packaged circuit board module; and 
     performing a cutting operation at positions of connecting ribs in pins in each frame unit, so that the plurality of pins are separated from the lead frame, to obtain a plurality of packaged integrated circuit boards. 
     A plastic packaging process is performed on the first pin part together with the circuit board, instead of connecting the first pin part in a conductive connection manner such as reflow soldering only after the circuit board is separately plastically packaged and is formed through cutting. Therefore, connection fastness between the first pin part and the conductive connection pad in the circuit board is improved, and safety and reliability of the circuit board are improved. 
     The electronic components are disposed on each of the first base surface and the second base surface that are opposite in the first base board, so that plastic packaging of a dual-sided circuit board can be implemented, thereby effectively improving integration of a packaged circuit board. 
     In an embodiment of this application, the plurality of conductive connection ends are disposed on at least one side of the first base board. In addition, at least one electronic component and conductive line of the first base board are exposed on two opposite sides of the lead frame from the hollow part. 
     In an embodiment of this application, the circuit board is a power circuit board, and the power circuit board is configured to perform functions such as power conversion, distribution, and detection, and other power management and control. 
     In an embodiment of this application, the circuit board is a microprocessor circuit board, a central processing unit circuit board, a graphics processing unit circuit board, a baseband circuit board, or the like. 
     In an embodiment of this application, the connecting rib includes a horizontal rib, reinforcing ribs, and auxiliary ribs, the horizontal rib is connected to the second pin part of each pin and the bezel, the reinforcing rib is connected to the horizontal rib and the bezel, and the auxiliary rib is connected to the horizontal rib and the first pin part. 
     The step of performing a cutting operation at positions of connecting ribs in pins further includes: 
     performing cutting at a connection position between the second pin part and the bezel, and breaking a connection between the second pin part and the bezel; 
     performing cutting between the plurality of pins and the horizontal rib, and breaking connections between the plurality of pins and the horizontal rib; and 
     performing cutting on the auxiliary rib, and breaking connections between the plurality of pins in each frame unit and the bezel. 
     When the horizontal rib and the plurality of pins are cut from the bezel, the auxiliary rib is still connected to the pin, thereby effectively preventing the pin from being damaged when the pin is cut from the horizontal rib. 
     In an embodiment of this application, after cutting is performed at the connection position between the second pin part and the bezel and cutting is performed between the plurality of pins and the horizontal rib, the second pin part is bent by a first angle relative to the first pin part, and cutting is performed on the auxiliary rib. After the horizontal rib and the plurality of pins are cut from the bezel, the auxiliary rib is still connected to the pin, and then when the second pin part is bent, the auxiliary rib can assist in completing automatic bending of the second pin part, and can effectively prevent the pin from being damaged during bending, thereby improving safety and reliability of the packaged integrated circuit board. 
     In an embodiment of this application, the first pin part includes a first penetration hole that penetrates through the first pin in a direction perpendicular to the first base board, and the first penetration hole is configured to accommodate a conductive connection agent. The step of fastening and connecting the circuit board to the lead frame includes: 
     coating, with the conductive connection agent, a position that is in the first pin part and that corresponds to the first penetration hole; and 
     after the plurality of conductive connection pads are correspondingly aligned with a plurality of first pin parts, electrically fastening and electrically connecting the plurality of conductive connection pads to the plurality of first pin parts in a one-to-one manner by using the conductive connection agent. 
     After the first pin part is electrically connected to the conductive connection pad in the circuit board by using the conductive connection agent, the plastic packaging process is performed on the first pin part together with the circuit board, thereby ensuring connection fastness between the first pin part and the conductive connection pad in the circuit board. 
     In an embodiment of this application, the first pin part includes a boss, a recessed part, and a second penetration hole. The boss is disposed on the first pin part in a direction perpendicular to the first pin part. Corresponding to a position of the boss, the first pin part further includes the recessed part recessed in the direction perpendicular to the first base board. The recessed part and the boss are located on a same straight line in the first direction. The second penetration hole penetrates through the recessed part in the direction perpendicular to the first base board. The recessed part and the second penetration hole are configured to accommodate a plastic packaging material. The step of plastically packaging the circuit board includes: 
     plastically packaging the circuit board and the first pin part by using the plastic packaging material in a direction adjacent to the first base surface and a direction adjacent to the second base surface, and forming a packaging casing on the first base surface, the second base surface, and the plurality of first pin parts, where a contact area and a binding force between the first pin part and the plastic packaging material are increased by using the boss, the recessed part, and the second penetration hole, the packaging casing covers the circuit board and the first pin part in two opposite directions of a corresponding hollow part in each frame unit, and all parts of the lead frame except the first pin part are exposed outside the packaging casing. 
     The first base surface and the second base surface that are opposite and on each of which the electronic components are disposed in the first base board are simultaneously plastically packaged in two directions, thereby effectively improving plastic packaging efficiency. 
     In an embodiment of this application, after the circuit board is plastically packaged, the method further includes: electroplating the second pin part, to protect the second pin part from being corroded or worn. 
     In an embodiment of this application, after the circuit board is plastically packaged, the method further includes: grinding the packaging casing at a position of at least one electronic component in the circuit board, where the at least one electronic component is exposed from the packaging casing, thereby improving heat dissipation efficiency of the electronic component. 
     In an embodiment of this application, a lead frame applied to a circuit board packaging manner is provided. The lead frame includes a plurality of frame units disposed in parallel in a first direction. The frame unit includes a hollow bezel, and a plurality of pins and connecting ribs that are disposed in the bezel. Each pin includes a first pin part and a second pin part that extend in a second direction and that are integrally formed, the first pin part is disposed in the bezel, the first pin part is configured to be electrically connected to a circuit board, and the second pin is connected and fastened to the bezel. The second direction is perpendicular to the first direction. The connecting rib is connected between the first pin part and the bezel. 
     When the lead frame is applied to a plastic packaging process of the circuit board, after the first pin part is electrically connected to a conductive connection pad in the circuit board by using a conductive connection agent, a plastic packaging process is performed on the first pin part together with the circuit board, thereby ensuring connection fastness between the first pin part and the conductive connection pad in the circuit board, so that safety and reliability of an electrical connection are improved when the circuit board is connected to another conductive circuit. In addition, during plastic packaging, only a corresponding circuit board and first pin part in each frame unit need to be plastically packaged, without a need to plastically package other parts in the lead frame, thereby effectively saving a plastic packaging material and reducing plastic packaging difficulty. 
     In an embodiment of this application, the bezel is rectangular, and includes two oppositely disposed first arms and two oppositely disposed second arms, the plurality of pins are disposed in parallel in a direction parallel to the second arm, and an extension direction of the plurality of pins is parallel to the first arm. The first arm extends in the second direction, and the second arm extends in the first direction, so that the plurality of pins are disposed in parallel in the first direction and extend in the second direction. 
     The connecting rib includes a horizontal rib, reinforcing ribs, and auxiliary ribs, the horizontal rib is connected to the first pin part of each pin and the bezel, the reinforcing rib is connected to the horizontal rib and the bezel, and the auxiliary rib is connected to the horizontal rib and the first pin part. Disposition of the connecting rib effectively improves connection strength between the pin and the bezel, and ensures safety of the pin in packaging and cutting processes. 
     In an embodiment of this application, the first pin part includes a first penetration hole that penetrates through the first pin in a third direction, the first penetration hole is configured to accommodate a conductive connection agent, and the third direction is perpendicular to a plane on which the first direction and the second direction are located. The first penetration hole can accommodate a relatively large quantity of conductive connection agents, so that the first pin part can be reliably electrically connected to another conductive connection part. 
     In an embodiment of this application, the first pin part includes a boss, the boss is connected to the first pin part in a direction perpendicular to an extension direction of the first pin part, the first pin part further includes a recessed part recessed in the third direction, and the recessed part and the boss are located on a same straight line in the first direction. The recessed part includes a second penetration hole, the second penetration hole penetrates through the recessed part in the third direction, and the second penetration hole is configured to accommodate a plastic packaging material. The recessed part, the boss, and the second penetration hole cooperate to effectively increase a contact area of the first pin part with the plastic packaging material in a subsequent plastic packaging process, improve a binding force between the first pin part and the plastic packaging material, and enhance plastic fastness. 
     In an embodiment of this application, a packaged integrated circuit board is provided. The packaged integrated circuit board includes a first base board, a plurality of pins, and a packaging casing. The first base board includes a first base surface and a second base surface that are oppositely disposed. A plurality of electronic components, a plurality of conductive lines, and a plurality of conductive connection pads are disposed on each of the first base surface and the second base surface, and the plurality of electronic components are electrically connected to the plurality of conductive connection pads through the plurality of conductive lines. The plurality of pins include first pin parts and second pin parts, and the first pin parts in the plurality of pins are electrically connected to the plurality of conductive connection pads in a one-to-one manner by using a conductive connection agent. The packaging casing is formed by plastically packaging the first base board and the first pin part by using a plastic packaging material after the plurality of pins are electrically connected to the plurality of conductive connection pads by using the conductive connection agent, and the second pin part is exposed outside the packaging casing. 
     After the first pin part is electrically connected to the conductive connection pad in a circuit board by using the conductive connection agent, a plastic packaging process is performed on the first pin part together with the circuit board, thereby ensuring connection fastness between the first pin part and the conductive connection pad in the circuit board, so that safety and reliability of an electrical connection are improved when the circuit board is connected to another conductive circuit. In addition, the electronic components are disposed on each of the first base surface and the second base surface that are opposite in the first base board, so that plastic packaging of a dual-sided circuit board can be effectively implemented, thereby effectively improving integration of the circuit board. 
     In an embodiment of this application, the circuit board is a power circuit board, and the power circuit board is configured to perform functions such as power conversion, distribution, and detection, and other power management and control. Correspondingly, the packaged integrated circuit board is a power chip. 
     In an embodiment of this application, the packaged integrated circuit board is a microprocessor, a central processing unit, a graphics processing unit, a baseband chip, a system on chip, or the like. 
     In an embodiment of this application, the first pin part and the second pin part extend in a same direction and are integrally formed. In a plurality of pins disposed in parallel on one side of the packaged integrated circuit board, auxiliary ribs in the foregoing connecting rib are disposed at first pin parts of pins arranged at the first position and the last position. The auxiliary rib can effectively protect safety of the pin in packaging, cutting, and bending processes. 
     In an embodiment of this application, the first pin part includes a first penetration hole that penetrates through the first pin in a direction perpendicular to the first base surface, and a conductive connection agent is accommodated in the first penetration hole, so that the first pin part can be reliably electrically connected to the conductive connection pad. 
     In an embodiment of this application, the first pin part further includes a boss. The boss is connected to the first pin part in a direction perpendicular to the first pin part. Corresponding to a position of the boss, the first pin part further includes a recessed part recessed in the direction perpendicular to the first base surface. The recessed part is configured to accommodate a plastic packaging material. The recessed part and the boss are located on a same straight line in a first direction. Corresponding to the recessed part, the first pin part includes a second penetration hole, the second penetration hole penetrates through the recessed part in the direction perpendicular to the first base surface, and the second penetration hole is configured to accommodate the plastic packaging material. The recessed part, the boss, and the second penetration hole cooperate to effectively increase a contact area of the first pin part with the plastic packaging material in a subsequent plastic packaging process, improve a binding force between the first pin part and the plastic packaging material, and enhance plastic fastness. 
     In an embodiment of this application, at least one of the plurality of electronic components is exposed from the packaging casing, thereby improving heat dissipation efficiency of the electronic component. 
     In an embodiment of this application, a power chip is provided. The power chip includes a first base board, a plurality of pins, and a packaging casing. The first base board includes a first base surface and a second base surface that are opposite, a plurality of electronic components, a plurality of conductive lines, and a plurality of conductive connection pads are disposed on each of the first base surface and the second base surface, the plurality of electronic components are electrically connected to the plurality of conductive connection pads through the plurality of conductive lines, and the plurality of electronic components cooperate with the plurality of conductive lines to perform power conversion, distribution, and detection. Each of the plurality of pins includes a first pin part and a second pin part, and first pin parts in the plurality of pins are electrically connected to the plurality of conductive connection pads in a one-to-one manner by using a conductive connection agent. The packaging casing is formed by plastically packaging a circuit board and the first pin part by using a plastic packaging material after the plurality of pins are connected to the plurality of conductive connection pads, and the second pin part is exposed outside the packaging casing. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a planar structure of a lead frame according to an embodiment of this application; 
         FIG. 2  is a schematic diagram of a partially enlarged structure, of the lead frame shown in  FIG. 1 , along a line I; 
         FIG. 3  is a schematic diagram of a cross-sectional structure along a line A-A in the lead frame shown in  FIG. 2 ; 
         FIG. 4  is a schematic diagram of a cross-sectional structure along a line B-B in the lead frame shown in  FIG. 2 ; 
         FIG. 5  is a flowchart of a method for packaging a circuit board by using the lead frame shown in  FIG. 1  and  FIG. 2 ; 
         FIG. 6  is a schematic diagram of a planar structure of a circuit board; 
         FIG. 7  is a schematic diagram of a cross-sectional structure, of the circuit board shown in  FIG. 6 , along a line C-C; 
         FIG. 8  is a schematic diagram of a planar structure of a first motherboard that includes a plurality of circuit boards; 
         FIG. 9  is a schematic diagram of a planar structure obtained after a circuit board is fastened to a lead frame; 
         FIG. 10  is a schematic diagram of a planar structure of a packaged circuit board module obtained after a circuit board and a lead frame that complete fastening are plastically packaged; 
         FIG. 11  is a schematic diagram of a planar structure for cutting a packaged circuit board module; 
         FIG. 12  is a schematic diagram of a planar structure obtained after a packaged circuit board module is cut and a pin is bent according to a second embodiment of this application; 
         FIG. 13  is a schematic diagram of a top-view structure of a packaged integrated circuit board; 
         FIG. 14  is a schematic diagram of a front-view structure of a packaged integrated circuit board; 
         FIG. 15  is a schematic diagram of a left-view structure of a packaged integrated circuit board; 
         FIG. 16  is a schematic diagram of a cross-sectional structure of a packaged integrated circuit board along a line D-D shown in  FIG. 13 ; 
         FIG. 17  is a schematic diagram of a planar structure obtained after a packaged circuit board module is ground according to a third embodiment of this application; and 
         FIG. 18  is a schematic diagram of a cross-sectional structure, of a packaged integrated circuit board obtained after cutting separation is performed on the packaged circuit board module shown in  FIG. 17  and a lead frame, along E-E. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a schematic diagram of a planar structure of a lead frame  100  according to an embodiment of this application. 
     As shown in  FIG. 1 , the lead frame  100  includes a plurality of frame units  10   a , and the plurality of frame units  10   a  are disposed in parallel in a first direction X. In this embodiment, the lead frame  100  is applied to an integrated packaging process of a circuit board, to perform, together with a circuit board (refer to  FIG. 6 ), a packaging process on a pin (refer to  FIG. 2 ) that performs a conductive connection. 
       FIG. 2  is a schematic diagram of a partially enlarged structure, of the lead frame  100  shown in  FIG. 1 , along a line I. As shown in  FIG. 2 , each frame unit  10   a  includes a hollow bezel  101 , a plurality of pins P, and connecting ribs  103 . The plurality of pins P and the connecting ribs  103  are located in a hollow part in the bezel  101 . The connecting ribs  103  are connected between the plurality of pins P and the bezel  101 , and are configured to fasten and connect the plurality of pins P to the bezel  101 . 
     Specifically, the bezel  101  includes oppositely disposed first arms a 1  and second arms a 2 , and a length of the first arm a 1  is greater than a length of the second arm a 2 . The two first arms a 1  extend in a second direction Y and are disposed at an interval of a preset distance in the first direction X, and the second arms a 2  extend in the first direction X and are disposed at an interval of a preset distance in the second direction Y. Therefore, the two first arms a 1  and the two second arms a 2  are spaced apart from each other and connected end to end to form a hollow rectangular structure. In other embodiments of this application, a length of the first arm a 1  is different from a length of the second arm a 2 , in other words, the bezel  101  is of a hollow square structure. In this embodiment, the first direction X, the second direction Y, and a third direction Z are perpendicular to each other and form three-dimensional coordinates. It should be noted that arrows in the first direction X, the second direction Y, and the third direction Z all represent positive/negative directions of the directions. 
     The plurality of pins P extend in the second direction Y and are disposed in parallel in a hollow region in the frame  101  in the first direction X, and the plurality of pins P are connected to the second arms a 2  in a direction perpendicular to an extension direction of the second arm a 2 . That is, an extension direction of the plurality of pins P is parallel to an extension direction of the first arm a 1 , an arrangement direction of the plurality of pins P is parallel to the second arm a 2 , and the plurality of pins P are adjacent to the two second arms a 2  and are fastened and connected to the second arms a 2  through abutting. 
     In this embodiment, the plurality of pins P include a first pin group P 1  and a second pin group P 2 , the first pin group P 1  is connected to one second arm a 2 , and the second pin group P 2  is connected to the other second arm a 2 . 
     Specifically, each of the plurality of pins P includes a first pin part Pa and a second pin part Pb that extend in the second direction Y and that are integrally formed. The first pin part Pa is disposed at a hollow position in the bezel  101 , and the first pin part Pa is configured to be electrically connected to a circuit board (not shown in the figure). That is, the first pin Pa is disposed in the hollow region in the bezel  101  through suspending. The second pin part Pb is connected to the second arm a 2 , so that the second pin part Pb is configured to be connected to another conductive line other than the circuit board. Therefore, the circuit board is electrically connected to the another conductive line by using the plurality of pins P. In this embodiment, a width size of the first pin part Pa in the first direction X is greater than a width size of the second pin part Pb in the first direction X. The first pin part Pa is an internal pin, and the second pin part Pb is an external pin. 
       FIG. 3  is a schematic diagram of a cross-sectional structure along a line A-A in the lead frame shown in  FIG. 2 .  FIG. 4  is a schematic diagram of a cross-sectional structure along a line B-B in the lead frame shown in  FIG. 2 . 
     As shown in  FIG. 2 , the first pin part Pa includes a first penetration hole Ph 1  that penetrates through the first pin part Pa in the third direction Z, and the first penetration hole Ph 1  is configured to accommodate a conductive connection agent, so that the first pin part Pa can be reliably electrically connected to another conductive connection part. The third direction Z is perpendicular to a plane in which the first direction X and the second direction Y are located. In this embodiment, the plane defined by the first direction X and the second direction Y is parallel to a plane in which the frame is located, and the third direction Z is a thickness direction of the pin P. 
     As shown in  FIG. 2  and  FIG. 4 , the first pin part Pa further includes a boss Pt. The boss Pt is disposed by extending from the first pin part Pa in the first direction X. That is, the boss Pt is perpendicular to the first pin part Pa and is disposed on the first pin part Pa through protrusion. 
     Corresponding to a position of the boss Pt, the first pin part Pa further includes a recessed part Pg recessed in the third direction Z and a second penetration hole Ph 2  that penetrates through the recessed part Pg in the third direction Z, and the recessed part Pg and the second penetration hole Ph 2  are configured to accommodate a plastic packaging material. The boss Pt and the recessed part Pg are substantially located on a same straight line in the first direction X. In other words, the boss Pt and the recessed part Pg are disposed in parallel in the first direction X. The first penetration hole Ph 1  and the second penetration hole Ph 2  are also located on a same straight line parallel to the second direction Y. In other words, the first penetration hole Ph 1  and the second penetration hole Ph 2  are disposed in parallel in the second direction Y. In this embodiment, the recessed part Pg does not penetrate through the first pin part Pa, and the recessed part Pg is formed by half etching the first pin Pa. For example, a recession dimension of the recessed part Pg is 50% of an overall thickness of the first pin part Pa. 
     In this embodiment, the recessed part Pg, the boss Pt, and the second penetration hole Ph 2  cooperate to effectively increase a contact area of the first pin part Pa with the plastic packaging material in a subsequent plastic packaging process, improve a binding force between the first pin part Pa and the plastic packaging material, and enhance plastic fastness. 
     Refer to  FIG. 2  again. One connecting rib  103  is correspondingly disposed for each pin group. For example, for the first pin group P 1 , a connecting rib  103  is connected to a plurality of pins P and the first arms a 1  and a second arm a 2  in the frame  101  and is configured to fasten the plurality of pins P to the hollow part in the frame  101 . 
     Specifically, as shown in  FIG. 2 , the connecting rib  103  includes a horizontal rib  103   a , reinforcing ribs  103   b , and auxiliary ribs  103   c.    
     The horizontal rib  103   a  is disposed by extending in the first direction X, is connected to a first pin part Pa of each of the plurality of pins P and the two oppositely disposed first arms a 1 , and is configured to fasten and connect the plurality of pins P to the frame  101  in the first direction X. 
     In other embodiments of this application, the horizontal rib  103   a  may be alternatively connected to each pin P in a non-perpendicular manner. For example, the horizontal rib  103   a  may be connected to the pin P in an acute angle or an obtuse angle manner. 
     The reinforcing rib  103   b  is disposed by extending in the second direction Y and is connected between the horizontal rib  103   a  and the second arm a 2 . In this embodiment, two reinforcing ribs  103   b  are correspondingly included for one pin group P 1  or one pin group P 2 . The two reinforcing ribs  103   b  are separately disposed adjacent to the two first arms a 1 , in other words, disposed between the pin group P 1  or the pin group P 2  and the two first arms a 1 . That is, in a plurality of pins P disposed in parallel on one side of each frame unit  10   a  in the lead frame  100 , reinforcing ribs  103   b  are disposed between pins P arranged at the first position and the last position and the first arms a 1 . The reinforcing rib  103   b  is configured to fasten the horizontal rib  103   a  to the second arm a 2 , to enhance connection strength between the pin P and the frame  101 , and prevent the pin P from falling off from the frame  101 . 
     The auxiliary rib  103   c  includes two parts (not marked) that extend in different directions, is connected between the horizontal rib  103   a  and the first pin part Pa, and is configured to enhance connection strength between the first pin part Pa and a circuit board in a circuit board packaging process. 
     In this embodiment, the auxiliary rib  103   c  includes two parts that are perpendicular to each other, and a connecting rib  103  corresponding to one pin group includes two auxiliary ribs  103   c . The two auxiliary connecting ribs  103   c  are respectively disposed at first pin parts Pa of pins P arranged at the first position and the last position in one pin group. That is, in a plurality of pins P disposed in parallel on one side of each frame unit  10   a  in the lead frame  100 , connecting ribs  103   c  are disposed between first pin parts Pa of pins P arranged at the first position and the last position and the horizontal rib  103   a.    
       FIG. 5  is a flowchart of a method for packaging a circuit board by using the lead frame  100  shown in  FIG. 1  and  FIG. 2 . 
     As shown in  FIG. 5 , the packaging method includes the following steps: 
     Step  501 : Provide a circuit board  200 . 
       FIG. 6  is a schematic diagram of a planar structure of the circuit board  200 .  FIG. 7  is a schematic diagram of a cross-sectional structure, of the circuit board  200  shown in  FIG. 6 , along a line C-C. 
     As shown in  FIG. 6  and  FIG. 7 , the circuit board  200  includes a first base board  201 , the first base board  201  includes a first base surface  20   a  and a second base surface  20   b  that are opposite, and a plurality of electronic components (not marked), a plurality of conductive lines (not shown), and a plurality of conductive connection pads Pads are disposed on each of the first base surface  20   a  and the second base surface  20   b . The first base surface  20   a  and the second base surface  20   b  are parallel to the plane defined by the first direction X and the second direction Y. 
     In this embodiment, the first base board  201  is a printed circuit board (PCB), and the plurality of electronic components may be components such as an integrated chip, a switching component, a resistor, a capacitor, and a magnetic core. The integrated chip may be a voltage conversion chip, a transformer chip, or the like. The plurality of electronic components are electrically connected through the plurality of conductive lines, and the plurality of electronic components are electrically connected to the plurality of conductive connection pads Pads through the conductive lines. 
     In an embodiment of this application, the circuit board  200  is a power circuit board, and the power circuit board is configured to perform functions such as power conversion, distribution, and detection, and other power management and control. 
     In other modified embodiments of this application, the circuit board  200  may be alternatively a microprocessor (Microcontroller Unit, MCU) circuit board, a central processing unit (CPU) circuit board, a graphics processing unit (GPU) circuit board, a baseband circuit board, or a system on chip (SoC) circuit board. 
     Specifically, the first base board  201  is rectangular as a whole, and includes two first side edges  201   a  and two second side edges  201   b . The first side edge  201   a  extends in the second direction Y, the second side edge  201   b  extends in the second direction X, and a length of the first side edge  201  is greater than a length of the second side edge  201 . 
     A first electronic component group EC 1  is disposed on the first base surface  20   a , and the first electronic component group EC 1  correspondingly includes a plurality of different electronic components and conductive lines. The plurality of electronic components may be components such as an integrated chip, a resistor, and a capacitor. 
     A second electronic component group EC 2  is disposed on the second base surface  20   b , and the second electronic component group EC 2  also correspondingly includes a plurality of different electronic components. 
     In this embodiment, the plurality of conductive connection pads Pads are disposed on edges of two opposite ends of the first base surface  20   a . More specifically, the plurality of conductive connection pads Pads are disposed at positions that are in the first base surface  20   a  and that are adjacent to the second side edges  201   b , and the two second side edges  201   b  correspond to different quantities of conductive connection pads Pads. The electronic components are disposed on each of the two opposite base surfaces of the first base board  201 , so that plastic packaging of a dual-sided circuit board can be effectively implemented, thereby effectively improving integration of the circuit board  200 . 
     In other embodiments of this application, when the two second side edges  201   b  correspond to different quantities of conductive connection pads Pads, one second side edge  201  may correspond to 0 conductive connection pads Pads, in other words, all the conductive connection pads Pads are disposed on the first base surface  20   a  corresponding to one second side edge  201 . 
     In other modified embodiments of this application, the two second side edges  201   b  may correspond to a same quantity of conductive connection pads Pads, a same quantity of conductive connection pads Pads are separately disposed on three side edges of the first base surface  20   a , not completely same quantities of conductive connection pads Pads are separately disposed on three side edges of the first base surface  20   a , a same quantity of conductive connection pads Pads are separately disposed on the two first side edges  201   a  and the two second side edges  201   b , or not completely same quantities of conductive connection pads Pads are separately disposed on the two first side edges  201   a  and the two second side edge  20   b.    
     In other modified embodiments of this application, one or more conductive connection pads may also be disposed at positions that are in the second base surface  20   b  and that are adjacent to one or more side edges. 
     In this embodiment, to obtain the circuit board  200  shown in  FIG. 6  and  FIG. 7 , refer to  FIG. 8 .  FIG. 8  is a schematic diagram of a planar structure of a first motherboard Mb that includes a plurality of circuit boards  200 . 
     As shown in  FIG. 8 , the first motherboard Mb includes a plurality of circuit boards  200  arranged in a matrix. A first cutting line CL 1  is disposed between adjacent circuit boards  200 . The first motherboard Mb is cut along first cutting lines CL 1 , to obtain a plurality of individual circuit boards  200  shown in  FIG. 6  to  FIG. 7 . Electronic components (not marked) and conductive connection pads Pads may be simultaneously disposed on the plurality of circuit boards  200  in the first motherboard Mb, and the electronic component may be mounted onto the first base board  201  by using a technology such as a surface mount technology (SMT). 
     Still refer to  FIG. 5 . In step  503 , the lead frame  100  shown in  FIG. 1  is provided. In this embodiment, the lead frame  100  is fastened to a process device (not shown in the figure). 
     Still refer to  FIG. 5 . In step  505 , the circuit board  200  is fastened and connected to the lead frame  100 . 
     Specifically, refer to  FIG. 9 .  FIG. 9  is a schematic diagram of a planar structure obtained after the circuit board  200  is fastened to the lead frame  100 . 
     The circuit board  200  is aligned with a frame unit  10   a  in the lead frame  100 , that is, one circuit board  200  is disposed through aligning with a hollow part in one frame unit  10   a  in the lead frame  100 . More specifically, in the circuit board  200 , the first side edge  201   a  corresponds to the first arm a 1 , the second side edge  201   b  corresponds to the second arm a 2 , and the plurality of conductive connection pads Pads are connected to a plurality of first pin parts Pa in a one-to-one manner by using the conductive connection agent, to implement an electrical connection and fastening between the plurality of conductive connection pads Pads and the plurality of first pin parts Pa. 
     In this embodiment, the conductive connection agent is solder, a position that is in the first pin part Pa and that corresponds to the first penetration hole Ph 1  ( FIG. 2 ) is coated with the conductive connection agent before the circuit board  200  is in contact with the lead frame, and the conductive connection agent is enabled to be in full contact with the first penetration hole Ph 1  ( FIG. 2 ), to help enhance connection strength between the first pin part Pa and the conductive connection pad Pad. 
     After the first pin part Pa of the frame unit  10   a  in the lead frame  100  is coated with the conductive connection agent, the plurality of circuit boards  200  are fastened to the lead frame  100  in a one-to-one correspondence manner between the plurality of conductive connection pads Pads of the circuit board  200  and the first pin parts Pa of the plurality of pins P. In this embodiment, a quantity of circuit boards  200  is the same as a quantity of frame units  10   a , and circuit boards  200  are electrically connected and fastened to frame units  10   a  through aligning in a one-to-one manner. 
     After corresponding fastening to the lead frame  100  is completed, electronic components on the first base surface  20   a  and the second base surface  20   b  that are opposite and that are included in the first base board  201  are exposed outside the frame unit  10   a  in the lead frame  100  in two opposite directions of the hollow part in the lead frame  100 , in other words, a plurality of electronic components and conductive lines on the first base board  201  are exposed on two opposite sides of the lead frame  100  from the hollow part in the lead frame  100 . 
     Still refer to  FIG. 5 . In step  507 , the circuit board  200  and the first pin part Pa are plastically packaged to form a packaging casing, to obtain a packaged circuit board module  300 . 
     Specifically, refer to  FIG. 10 .  FIG. 10  is a schematic diagram of a planar structure of the packaged circuit board module  300  obtained after the circuit board  200  and the lead frame  100  that complete fastening are plastically packaged. 
     As shown in  FIG. 10 , corresponding to each frame unit  10   a  in the lead frame  100 , the circuit board  200  ( FIG. 7 ) and the first pin part Pa ( FIG. 2 ) are plastically packaged with a mold by using a plastic packaging material in an injection molding manner in a direction adjacent to the first base surface  20   a  ( FIG. 7 ) and a direction adjacent to the second base surface  20   b  ( FIG. 7 ), in other words, the circuit board  200  is plastically packaged both in a positive direction and a negative direction of the third direction Z, so that the packaging casing CA is formed on the first base surface  20   a  and the second base surface  20   b . In this embodiment, the plastic packaging material may be epoxy resin, an organosilicon rubber material, polyimide, fiber, metal, ceramic, or the like. 
     The packaging casing CA covers the circuit board  200  and the first pin part Pa ( FIG. 2 ) in two opposite directions of the hollow part in the lead frame  100 . In addition, in addition to the first pin part Pa, a frame including the first arms a 1  and the second arms a 2 , the second pin part Pb, and the connecting rib  103  in the lead frame  100  are all exposed outside the packaging casing CA, to form the packaged circuit board module  300 . 
     In this embodiment, the circuit board  200  is packaged by using a structure of the lead frame  200 , so that only a corresponding circuit board  200  and first pin part Pa in each frame unit  10   a  need to be plastically packaged, without a need to plastically package a frame and a second pin part Pb in the lead frame  100 , thereby effectively saving a plastic packaging material and reducing plastic packaging difficulty. In addition, after the first pin part Pa is electrically connected to the conductive connection pad Pad in the circuit board  200  by using the conductive connection agent, a plastic packaging process is performed on the first pin part Pa together with the circuit board  200 , thereby ensuring connection fastness between the first pin part Pa and the conductive connection pad Pad in the circuit board  200 , so that safety and reliability of an electrical connection are improved when the circuit board  200  is connected to another conductive circuit. In addition, the first base surface  20   a  and the second base surface  20   b  that are opposite and on each of which the electronic components are disposed in the first base board are simultaneously plastically packaged in two directions, thereby effectively improving plastic packaging efficiency. 
     In this embodiment, after the circuit board  200  is plastically packaged, the method further includes: performing an electroplating process on the second pin part Pa exposed outside the packaging casing CA, to protect the second pin part Pa from being corroded or worn. An electroplating material is tin. In other embodiments of this application, the electroplating material may be alternatively another material, such as gold, silver, aluminum, zinc, copper, chromium, nickel, or palladium. Certainly, the electroplating material is not limited thereto. 
     Still refer to  FIG. 5 . In step  509 , a cutting operation is performed at a position of the connecting rib  103  in the pin P, so that the pin P is separated from the lead frame  100 , to obtain a packaged integrated circuit board  400 . 
     Specifically, refer to  FIG. 11 .  FIG. 11  is a schematic diagram of a planar structure for cutting the packaged circuit board module  300 . A cutting operation is performed between the second pin part Pb and the second arm a 2  along a second cutting line CL 2 , and a connection between the second pin part Pb and the second arm a 2  is broken, so that the second pin part Pb is disconnected from the second arm a 2 . In this embodiment, the second cutting line CL 2  includes a plurality of line segments at different positions and in different directions. 
     Cutting is performed between the plurality of pins P and the horizontal rib  103   a , and connections between the plurality of pins P and a connection between the pin P and the horizontal rib  103   a  are broken, so that the plurality of pins P are independent of each other without a connection relationship, and the pin P and the horizontal rib  103   a  are independent of each other without a connection relationship. 
     A cutting operation is performed on the auxiliary rib  103   c  along a third cutting line CL 3 , and a connection between the first pin part Pa and the horizontal rib  103   a  is broken, so that all the pins P are disconnected from the bezel  101  in the lead frame  100 . In this case, a packaged circuit board  200  in the packaged circuit board module  300  is detached from the lead frame  100  with disconnection of the plurality of pins P from the bezel  101 , to obtain a plurality of independent packaged integrated circuit boards  400  shown in  FIG. 13 . 
     In this embodiment, an angle between the first pin part Pa and the second pin Pb in the first pin P is 180°. In other words, the first pin part Pa and the second pin Pb are substantially located on a same straight line. 
     In this embodiment, when the horizontal rib  103   a  and the plurality of pins P are cut from the bezel  101 , the auxiliary rib  103   c  is still connected to the pin P, thereby effectively preventing the pin P from being damaged when the pin P is cut from the horizontal rib  103   a.    
     In this embodiment, when the corresponding circuit board  200  is a power circuit board, the packaged integrated circuit board  400  is a power chip. 
     In other modified embodiments of this application, when the circuit board  200  may be alternatively a microprocessor circuit board, a central processing unit circuit board, a graphics processing unit circuit board, a baseband circuit board, or a system on chip circuit board, the packaged integrated circuit board is a corresponding microprocessor, central processing unit, graphics processing unit, baseband chip, or system on chip. 
       FIG. 12  is a schematic diagram of a planar structure obtained after the packaged circuit board module  300  is cut and a pin is bent according to a second embodiment of this application. 
     Refer to  FIG. 11  and  FIG. 12  together. Cutting is performed between the second pin part Pb and the second arm a 2  along a second cutting line CL 2 , and connections between the plurality of pins P and a connection between the pin P and the connecting rib  103  are broken, so that the second pin part Pb is disconnected from the second arm a 2 . 
     In addition, cutting is performed between the plurality of pins P and the horizontal rib  103   a , and a connection between the first pin part Pa and the horizontal rib  103   a  is broken, so that the plurality of pins P are independent of each other without a connection relationship, and the pin P and the horizontal rib  103   a  are independent of each other without a connection relationship. 
     Further, the second pin part Pb is bent by a first angle at a position in which the first pin part Pa is adjacent to the second pin part Pb, in other words, the second pin part Pb is enabled to be substantially perpendicular to the first pin part Pa. In this embodiment, the first angle is 90°. 
     Further, as shown in  FIG. 11 , a cutting operation is performed on the auxiliary rib  103   c  along a third cutting line CL 3 , and a connection between the first pin part Pa and the horizontal rib  103   a  is broken, so that a plurality of plastically packaged circuit boards  200  in the packaged circuit board module  300  are detached from the lead frame  100 , to obtain a plurality of independent packaged integrated circuit boards  400  shown in  FIG. 13 . 
     In this embodiment, after the horizontal rib  103   a  and the plurality of pins P are cut from the bezel  101 , the auxiliary rib  103   c  is still connected to the pin P, and then when the second pin part Pb is bent, the auxiliary rib  103   c  can assist in completing automatic bending of the second pin part Pb, and can effectively ensure safety of the pin P during bending. Because the auxiliary rib  103   c  can effectively ensure safety of the pin P, there is no need to dispose another auxiliary structure to protect the pin P, thereby effectively reducing an area of the packaged integrated circuit board  400 . 
     In addition, the plastic packaging process is performed on the first pin part Pa together with the circuit board  200 , instead of connecting the first pin part Pa in a conductive connection manner such as reflow soldering only after the circuit board  200  is separately plastically packaged and is formed through cutting. Therefore, a conductive connection step of the pin P and the circuit board  200  is omitted while connection fastness between the first pin part Pa and the conductive connection pad Pad in the circuit board  200  is improved, thereby simplifying a packaging process of the circuit board  200 . In addition, when the packaged circuit board module  300  is cut, cutting needs to be performed only on the second pin part Pb and the connecting rib  103 , without a need to cut the plastic packaging casing CA, thereby effectively reducing cutting difficulty. In addition, safety of electronic components on the circuit board  200  in the plastic packaging casing CA can be ensured. 
     The electronic components are disposed on each of the first base surface  20   a  and the second base surface  20   b  that are opposite in the first base board  201 , so that plastic packaging of a dual-sided circuit board can be effectively implemented, thereby effectively improving integration of the circuit board  200 . 
       FIG. 13  is a schematic diagram of a top-view structure of the packaged integrated circuit board  400 .  FIG. 14  is a schematic diagram of a front-view structure of the packaged integrated circuit board  400 .  FIG. 15  is a schematic diagram of a left-view structure of the packaged integrated circuit board  400 .  FIG. 16  is a schematic diagram of a cross-sectional structure of the packaged integrated circuit board  400  along a line D-D shown in  FIG. 13 . 
     As shown in  FIG. 13  to  FIG. 16 , the first pin part Pa and the auxiliary rib  103   c  are substantially covered by the packaging casing CA, and the second pin part Pb is perpendicular to the first pin part Pa and is exposed outside the packaging casing CA. In this embodiment, the second pin part Pb is configured to be electrically connect to another conductive line (not shown) by using the conductive connection agent. In a plurality of pins P disposed in parallel on one side of the packaged integrated circuit board  400 , first pin parts of pins P arranged at the first position and the last position are connected to the auxiliary ribs  103   c  in the connecting rib  103 . 
     As shown in  FIG. 16 , the electronic components on the first base surface  20   a  and the second base surface  20   b  located on upper and lower sides in the circuit board  200  are packaged in the packaging casing CA together with the first base board  201 , thereby effectively improving integration of the circuit board  200 , and also effectively improving safety of the electronic components in the circuit board  200 . The plastic packaging process is performed on the pin P together with the circuit board  200 , thereby effectively improving connection strength between the pin P and the conductive connection pad Pad in the circuit board  200 . 
       FIG. 17  is a schematic diagram of a planar structure obtained after the packaged circuit board module  300  is ground according to a third embodiment of this application.  FIG. 18  is a schematic diagram of a cross-sectional structure, of the packaged integrated circuit board  400  obtained after cutting separation is performed on the packaged circuit board module  300  shown in  FIG. 17  and the lead frame  100 , along E-E. 
     As shown in  FIG. 17 , after the circuit board  200  is plastically packaged and the packaged circuit board module  300  is obtained, plastic packaging materials at a position L 1  of a first electronic component Eca and a position L 2  of a second electronic component Ecb in the second electronic component group EC 2  ( FIG. 7 ) are ground, so that the first electronic component Eca and the second electronic component Ecb are exposed from the packaging casing CA in the packaged integrated circuit board  400  shown in  FIG. 18 , thereby improving heat dissipation efficiency of the first electronic component Eca and the second electronic component Ecb. 
     In this embodiment, the first electronic component Eca and the second electronic component Ecb each are an electronic component that emits a relatively large amount of heat in a working process, such as a transformer or a magnetic core. 
     The foregoing descriptions are merely specific implementations of this application, but are not intended to limit the protection scope of this application. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.