Abstract:
A power supply module and a packaging and integrating method thereof are provided. The power supply module includes a lead frame, a passive element, an integrated circuit (IC), and a power switch Metallic Oxide Semiconductor Field Effect Transistor (MOSFET). The passive element is soldered onto the lead frame by using the surface mount technology. The IC is a flip chip and is mounted and soldered onto the lead frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/CN2011/073523, filed on Apr. 29, 2011, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE APPLICATION 
       [0002]    The present application relates to the field of power supply equipment technologies, and in particular, to a power supply module and a packaging and integrating method thereof. 
       BACKGROUND OF THE APPLICATION 
       [0003]    Main components of a power supply module include a power switch, a control IC (Integrated circuit, integrated circuit), an input capacitor, an output capacitor, a power inductor, and a resistor and a capacitor which are configured for signal processing. The power switch is often an MOSFET (Metallic Oxide Semiconductor Field Effect Transistor, metallic oxide semiconductor field effect transistor) or an IGBT(Insulated Gate Bipolar Transistor, insulated gate bipolar transistor), and the control IC may be a driver chip, or a PWM (Pulse Width Modulation, pulse width modulation) control chip, or a combination of the two. At present, power supply and semiconductor manufacturers are all developing packaging and integrating technologies of the power supply module, integration schemes of the power supply manufacturers and the semiconductor manufacturers gradually produce an intersection in the field of semiconductor packaging and integrating on the chip level, structures such as the MOSFET, the IC, and the passive element (such as an inductor, a resistor, and a capacitor) are often used, a PCB (Printed Circuit Board, printed circuit board) or other substrates are embedded, and an interconnection manner of gold wire or copper wire bonding is adopted. The MOSFET, as the switch, is controlled or driven by the IC to complete the pulse width modulation of the input voltage, and output the voltage required by a load after filtering by the inductor and the capacitor. 
         [0004]    In power supply modules of the prior art, the inductor may be formed by soldering multiple copper pieces with a copper lead frame and additionally adding a magnetic core, and may also be formed by soldering a ready inductance component onto the copper lead frame by using the SMT (Surface Mount Technology, surface mount technology). According to the different integration manner of the IC and the MOSFET, the packaging and integrating structure of the power supply module is also different, which mainly has the following two manners: 
         [0005]    1. The IC and the MOSFET may be integrated on one chip, an IC and an MOSFET integrated chip are connected to the lead frame and the inductor through the gold wire bonding. 
         [0006]    2. The IC and the MOSFET are independent chips, the IC is assembled on the PCB, the PCB is then assembled on the lead frame, and the IC and the MOSFET chip are interconnected through the gold wire or copper wire bonding. 
         [0007]    Whatever kind of the packaging and integrating structure is, multiple gold wires or copper wires for bonding are required for electrical connection, so that the costs are high. Further, the gold wire bonding process has defects, such as the diameter of the gold wire is small, the wire length is large, so that parasitic parameters such as parasitic impedance during heat dissipation and working are not ideal and the power efficiency is affected. In addition, for the above second manner, a layer of PCB interconnection is added, the degree of technical difficulty of the process and the cost are increased. 
       SUMMARY OF THE APPLICATION 
       [0008]    Embodiments of the present application provide a power supply module and a packaging and integrating method thereof to solve the problems in the prior art that parasitic parameters may be increased, the heat dissipation performance and the power efficiency are affected because of using the connection manner of the gold wire bonding, and simplify the interconnection manner. 
         [0009]    In order to solve the above technical problems, the technical solutions adopted by the embodiments of the present application are as follows: 
         [0010]    A power supply module includes a lead frame, a passive element, an integrated circuit IC, and a power switch Metallic Oxide Semiconductor Field Effect Transistor MOSFET. The passive element is soldered onto the lead frame by using the surface mount technology. The IC is a flip chip and is mounted and soldered onto the lead frame by using a flip-chip technology. 
         [0011]    A packaging and integrating method of a power supply module includes: 
         [0012]    soldering a passive element onto a lead frame by using the surface mount technology; 
         [0013]    mounting and soldering a flip chip on which a power switch Metallic Oxide Semiconductor Field Effect Transistor MOSFET and an integrated circuit IC are integrated to the lead frame by using the flip-chip technology to form a power supply module; 
         [0014]    plastic encapsulating the power supply module; and 
         [0015]    separating the power supply module after the plastic encapsulating is completed. 
         [0016]    A packaging and integrating method of a power supply module includes: 
         [0017]    soldering a passive element onto a lead frame by using the surface mount technology; 
         [0018]    soldering each of two power switch Metallic Oxide Semiconductor Field Effect Transistor MOSFET chips onto the lead frame; 
         [0019]    mounting and soldering a flip-chip mode integrated circuit IC chip onto the lead frame to form a power supply module; 
         [0020]    plastic encapsulating the power supply module; 
         [0021]    separating the power supply module after the plastic encapsulating is completed. 
         [0022]    A packaging and integrating method of a power supply module, includes: 
         [0023]    soldering a passive element onto a lead frame by using the surface mount technology; 
         [0024]    mounting and soldering a flip-chip mode integrated circuit IC chip onto the lead frame by using a flip-chip technology; 
         [0025]    alternately stacking and mounting two power switch Metallic Oxide Semiconductor Field Effect Transistor MOSFET chips and two copper pieces to achieve electrical connection of the MOSFET chips to the lead frame to form a power supply module; 
         [0026]    plastic encapsulating the power supply module; and 
         [0027]    separating the power supply module after the plastic encapsulating is completed. 
         [0028]    In the power supply module and the packaging and integrating method thereof provided in the embodiments of the present application, the passive element is soldered onto the lead frame by using the surface mount technology. The IC is designed as a flip chip and is mounted and soldered onto the lead frame by using the flip-chip technology without the need of connection through gold wire or copper wire bonding, and a connection distance between the chip and the lead frame is short, so that the parasitic parameters are effectively decreased and the heat dissipation performance and the power efficiency are effectively improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    To describe the technical solutions according to the embodiments of the present application or in the prior art more clearly, the accompanying drawings for describing the embodiments or the prior art are introduced briefly in the following. Apparently, the accompanying drawings in the following description are only some embodiments of the present application, and persons of ordinary skill in the art can derive other drawings from the accompanying drawings without creative efforts. 
           [0030]      FIG. 1  is a schematic connection diagram of a flip chip and a lead frame according to an embodiment of the present application; 
           [0031]      FIG. 2  is a schematic diagram of a single-chip structure of a power supply module according to an embodiment of the present application; 
           [0032]      FIG. 3  is a schematic diagram of another single-chip structure of a power supply module according to an embodiment of the present application; 
           [0033]      FIG. 4  is a schematic diagram of another single-chip structure of a power supply module according to an embodiment of the present application; 
           [0034]      FIG. 5  is a schematic diagram of another single-chip structure of a power supply module according to an embodiment of the present application; 
           [0035]      FIG. 6  is a schematic diagram of a tri-chip structure of a power supply module according to an embodiment of the present application; 
           [0036]      FIG. 7  is a schematic connection diagram of a flip MOSFET chip with a vertical structure and a lead frame according to an embodiment of the present application; 
           [0037]      FIG. 8  is a schematic connection diagram of a normal MOSFET chip of a vertical structure and a lead frame according to an embodiment of the present application; 
           [0038]      FIG. 9  is a schematic connection diagram of a flip MOSFET chip of a planar structure and a lead frame according to an embodiment of the present application; 
           [0039]      FIG. 10  is a schematic connection diagram of a normal MOSFET chip with a planar structure and a lead frame according to an embodiment of the present application; and 
           [0040]      FIG. 11  is a schematic diagram of another tri-chip structure of a power supply module according to an embodiment of the present application. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0041]    To make persons in the art better understand the solutions of according to embodiments of the present application, the embodiments of the present application are described below in further detail with reference to the accompanying drawings and implementation. 
         [0042]    For some problems existing in the power supply module in which the connection of the gold wire or copper wire bonding is used in the prior art, an embodiment of the present application provides a power supply module, which includes: a lead frame, a passive element, an integrated circuit IC, and MOSFETs. Passive elements include passive elements such as a power inductor, an input capacitor, an output capacitor, and a resistor. The passive elements are soldered onto the lead frame by using the surface mount technology. In the embodiment of the present application, the IC is a flip chip and is mounted and soldered onto the lead frame by using the flip-chip technology. The IC may act as a driver chip of the MOSFETs. 
         [0043]    In the power supply module, generally two MOSFETs are required. Therefore, in the power supply module of the embodiment of the present application, two MOSFETs and the IC may be integrated on one flip chip (a single-chip structure for short); or the two MOSFETs may be designed as two chips independent of the IC (a tri-chip structure for short), and in this case, the two MOSFET chips may be designed as flip chips or normal chips. 
         [0044]    The flip chip and the normal chip refer to two types of chip having different packaging manners. 
         [0045]    The packaging manner of the flip chip is that a front side of the chip face downwards towards a substrate to form a shortest circuit without lead bonding, thereby reducing the resistance; a metal solder joint such as a copper stud solder joint or a tin ball solder joint that exists below the flip chip, the connection manner in which the flip chip and the lead frame are connected is as shown in  FIG. 1 , a flip chip  11  is soldered onto a lead frame  10  through metal solder joints  12 . 
         [0046]    The normal chip is a chip with a conventional structure and is connected to the lead frame through a bottom surface of the chip. 
         [0047]    The single-chip structure and the tri-chip structure are taken as examples to further describe the power supply module of the embodiment of the present application. 
         [0048]    As shown in  FIG. 2 ,  FIG. 2  is a schematic diagram of a single-chip structure according to an embodiment of the present application; 
         [0049]    In this embodiment, passive elements  211 ,  212 ,  213  are soldered onto a lead frame  20  by using the surface mount technology. The passive elements may specifically be inductors, capacitors, and resistors. Two MOSFETs and an IC are integrated on a flip chip  22 , and the flip chip  22  is mounted and soldered onto the lead frame  20  by using the flip-chip technology. 
         [0050]    The lead frame  20  in this embodiment may be of an array structure, that is, multiple modules are arranged in matrix in the lead frame. 
         [0051]    The following assembling sequence may be used for integrating the power supply module with such a structure: 
         [0052]    (1) The passive elements are soldered onto the lead frame by using the surface mount technology. 
         [0053]    (2) After being cleaned, the flip chip on which the MOSFETs and the IC are integrated is mounted and soldered to the lead frame by using the flip-chip technology, and then the whole module is cleaned. 
         [0054]    (3) Filling adhesive is filled in the bottom of the flip chip by using the underfill technology and cured in the bottom of the flip chip, and then the whole module is cleaned. 
         [0055]    (4) The whole module is plastic encapsulated by using the plastic encapsulation technology. 
         [0056]    (5) The power supply module is separated through stamping separation or cutting separation after the plastic encapsulating is completed. 
         [0057]    It should be noted that, the processes of the cleaning in steps (2) and (3) or the underfill process in step (3) is optional, whether the cleaning processes and the underfill process are performed may be determined according to actual needs. 
         [0058]    In addition, in an actual application, the above assembling sequence may be adjusted flexibly. For example, the flip chip is assembled first, and then the passive elements are assembled. 
         [0059]    It can be seen that, in the power supply module in the embodiment of the present application, without the need of connection through the gold wire or the copper wire bonding, the MOSFETs and the IC are directly mounted to the lead frame through the flip chip, and a connection distance between the chip and the lead frame is short, so that the parasitic parameters are effectively decreased and the heat dissipation performance and the power efficiency are effectively improved. 
         [0060]    In order to further improve the heat dissipation performance of the power supply module, in the embodiment of the present application, a copper piece may also be disposed on a back surface of the flip chip on which the MOSFETs and the IC are integrated, so as to facilitate heat dissipation and reduce electrical noise. The copper piece may be soldered onto the back surface of the flip chip or adhere to the back surface of the flip chip through high thermal conductive adhesive. Through an appropriate chip design, the two MOSFETs integrated on the chip are all designed as the vertical structure or partially designed as the vertical structure, electrodes of the MOSFETs may be on an upper surface of the chip, the copper piece may also, as an external connection line of the MOSFET electrodes, provide an electrical connection function. 
         [0061]    In an actual application, the structure, the mounting position and the mounting manner of the copper piece may be flexibly designed according to the size and the assembling position of the flip chip, which is not limited by the embodiment of the present application, and examples are provided below for illustration only. 
         [0062]    As shown in  FIG. 3 ,  FIG. 3  is a schematic diagram of another single-chip structure of a power supply module according to an embodiment of the present application. 
         [0063]    Different from the embodiment shown in  FIG. 2 , in this embodiment, two copper pieces  31 ,  32  are mounted to the back surface of the flip chip  22 . The copper pieces  31 ,  32  are connected to the lead frame  20  through their respective bent edges. The copper pieces  31 ,  32  not only play roles of heat dissipation and electrical noise reduction, but also provide, as an external connection line of the electrodes of the MOSFETs, the electrical connection function when the two MOSFETs integrated on the chip are designed as the vertical structure. 
         [0064]    As shown in  FIG. 4  and  FIG. 5 ,  FIG. 4  and  FIG. 5  are schematic diagrams of structural variations of the power supply module with the single-chip structure shown in  FIG. 3 . 
         [0065]    In the two structures, a copper piece, such as a copper piece  41  shown in  FIG. 4  and a copper piece  51  shown in  FIG. 5 , is mounted to the back surface of the flip chip  22 . A difference between the copper pieces shown in  FIG. 4  and  FIG. 5  lies in that, the bent edges of the copper pieces are connected to different positions of the lead frame  20 . 
         [0066]    Similarly, in the two structures, the copper pieces  31 ,  32  not only play roles of heat dissipation and electrical noise reduction, but also provide, as an external connection line of the electrodes of the MOSFET, the electrical connection function when one MOSFET integrated on the chip is designed as the vertical structure. The other MOSFET in the chip may be designed as the planar structure and is connected to the lead frame through solder balls of the flip chip or connected to the one MOSFET directly through an internal structure of the chip. 
         [0067]    Definitely, in an actual application, the power supply module may further have other structural variations, which are not described through examples one by one herein. 
         [0068]    The assembling and integrating processes of the power supply modules shown in  FIG. 3  to  FIG. 5  are similar to the assembling and integrating processes of the power supply module shown in  FIG. 2 , and are not repeated herein. In the above embodiment of the single-chip structure, in an alternative solution of the copper piece, for  31 ,  32  in  FIG. 3 ,  41  in  FIG. 4 ,  51  in  FIG. 5 , an aluminum strip may be used to replace the copper piece, the aluminum strip is soldered onto a corresponding chip surface and a lead frame surface by using the aluminum line and aluminum strip soldering technology. The aluminum strip is a strip-shaped interconnecting material with the shape similar to that of the copper piece. 
         [0069]    As mentioned in the preceding, in the power supply module of the embodiment of the present application, the two MOSFETs and the IC may be integrated on one flip chip (a single-chip structure for short); or two MOSFETs may be designed as two chips independent of the IC (a tri-chip structure for short), and in this case, the two MOSFETs may be designed as flip chips or normal chips. 
         [0070]    As shown in  FIG. 6 ,  FIG. 6  is a schematic diagram of a tri-chip structure of a power supply module according to an embodiment of the present application. 
         [0071]    In this embodiment, passive elements  611 ,  612 ,  613  are soldered onto a lead frame  60  by using the surface mount technology. The passive elements may specifically be inductors, capacitors, and resistors. An IC and two MOSFETs are three independent chips, which are an IC chip  62  and MOSFET chips  63 ,  64  shown in the drawing. The IC chip  62  is a flip chip and is mounted and soldered onto the lead frame  60  by using a flip-chip technology; the two MOSFET chips  63 ,  64  may be flip chips or normal chips, and each of them soldered onto the lead frame  60  through the manner corresponding to chip packaging. 
         [0072]    The MOSFET chip  63  is connected to the lead frame  60  through a copper piece  631 , and the MOSFET chip  64  is connected to the lead frame  60  through a copper piece  641 . Each of the copper piece  631  and the copper piece  641  is connected to their respective MOSFET chips and the lead frame  60  through the soldering or the adhering manner (such as adhering through adhesive of high thermal conductivity), so as to connect the MOSFET chips to the lead frame  60  and interconnect the two MOSFET chips. 
         [0073]    The lead frame  60  in this embodiment may be of an array structure, that is, multiple modules are arranged in matrix in the lead frame. 
         [0074]    The following assembling sequence may be used for integrating the power supply module of this structure: 
         [0075]    (1) The passive elements are soldered onto the lead frame by using the surface mount technology. 
         [0076]    (2) After being cleaned, each of the two MOSFET chips is soldered onto the lead frame; for the flip MOSFET chip, the flip MOSFET chip may be mounted and soldered onto the lead frame by using the flip chip mount technology; for the normal chip, the normal chip may be soldered onto the lead frame by using the normal chip mount technology through a soldering tin or the adhesive of high thermal conductivity. 
         [0077]    (3) The copper pieces are soldered (for example, by using the soldering tin solder technology) or adhere (for example, through the adhesive of high thermal conductivity) to the MOSFET chips and the lead frame by using the copper piece mount technology to achieve interconnection of the MOSFETs and the lead frame, and then the whole module is cleaned. 
         [0078]    (4) The flip chip mode IC chip is mounted and soldered onto the lead frame by using the flip-chip technology, and then the whole module is cleaned. 
         [0079]    (5) Filling adhesive is filled in the bottom of the flip chip by using the underfill technology and cured in the bottom of the flip chip, and then the whole module is cleaned. 
         [0080]    (6) The whole module is plastic encapsulated by using the plastic encapsulation technology. 
         [0081]    (7) The power supply module is separated through stamping separation or cutting separation after the plastic encapsulating is completed. 
         [0082]    It should be noted that, the cleaning in steps (2) to (5) or the underfill process in step (5) is optional, whether the cleaning processes and the underfill process are may be determined according to actual needs. 
         [0083]    In addition, in an actual application, the above assembling sequence may be adjusted flexibly. For example, the chips are assembled first, and then the passive elements are assembled. 
         [0084]    It should be noted that, the two MOSFETs in  FIG. 6  may be two flip MOSFET chips with the vertical structure, but according to requirements of an application, normal MOSFET chips with the vertical structure may also be used. Definitely, the flip MOSFET chip or the normal MOSFET chip with the planar structure may also be used, but when the structure and packaging of the MOSFET are different, the number and the connection manner of the copper pieces mounted to the MOSFET chip require appropriate adjustment, the copper piece mounted to the MOSFET chip may be connected to different electrodes of the MOSFET. In addition, the structures and the packaging modes of the two MOSFET chips of the embodiment of the present application may be completely the same or different. 
         [0085]    The connection modes between the MOSFETs with different structures and packaging manners and the lead frame of the embodiment of the present application are described briefly in the following. 
         [0086]    A current between a source and a drain of the MOSFET with the vertical structure longitudinally passes between an upper surface and a lower surface of the chip, the source and the drain are located on the upper surface and the lower surface of the chip; a current between a source and a drain of the MOSFET with the planar structure horizontally passes along a single surface of the chip. The source and the drain are located on the same plane. 
         [0087]    As shown in  FIG. 7 ,  FIG. 7  is a schematic connection diagram of a flip MOSFET chip with the vertical structure and a lead frame according to an embodiment of the present application. 
         [0088]    In the drawing, two electrodes on a lower surface of a flip MOSFET chip  71  are connected to a soldering end of a lead frame  70  through flip chip solder balls, an electrode on an upper surface is connected to the soldering end of the lead frame  70  through a copper piece  72  mounted to the electrode at the upper surface. 
         [0089]    As shown in  FIG. 8 ,  FIG. 8  is a schematic connection diagram of a normal MOSFET chip with the vertical structure and a lead frame according to an embodiment of the present application. 
         [0090]    In the drawing, an electrode on a lower surface of a normal MOSFET chip  81  is connected to a soldering end of a lead frame  80  through a soldering tin or the adhesive of high thermal conductivity, two electrodes on an upper surface are connected to the soldering end of the lead frame  80  through copper pieces  821 ,  822  mounted to the two electrodes on the upper surface. 
         [0091]    As shown in  FIG. 9 ,  FIG. 9  is a schematic connection diagram of a flip MOSFET chip with the vertical structure and a lead frame according to an embodiment of the present application. 
         [0092]    In the drawing, an electrode on a lower surface of a flip MOSFET chip  91  is soldered onto a soldering end of the lead frame  90  through solder balls of the flip chip, so as to connect three electrodes of the MOSFET to the lead frame  90 . 
         [0093]    As shown in  FIG. 10 ,  FIG. 10  is a schematic connection diagram of a normal MOSFET chip with the planar structure and a lead frame according to an embodiment of the present application. 
         [0094]    In the drawing, a lower surface of a normal MOSFET chip  101  is connected to a soldering end of a lead frame  100  through a soldering tin or adhesive of high thermal conductivity, three electrodes on an upper surface are connected to the soldering end of the lead frame  100  through copper pieces  1011 ,  1012 ,  1013  mounted to the three electrodes on the upper surface. 
         [0095]    In the above embodiment of the tri-chip structure, in an alternative solution of the copper piece, for  631 ,  641  in  FIG. 6 ,  72  in  FIG. 7 ,  821 ,  822  in  FIG. 8 ,  1011 ,  1012 ,  1013  in  FIG. 10 , an aluminum strip may be used to replace the copper piece. The aluminum strip is soldered onto a corresponding chip surface and a lead frame surface by using the aluminum line and aluminum strip soldering technology. The aluminum strip is a strip-shaped interconnecting material with the shape similar to that of the copper piece. 
         [0096]    It can be seen that, in the power supply module of the embodiment of the present application, the interconnection of the MOSFET chips does not need gold wire or copper wire bonding, and the assembling of the IC chip does not need an embedded PCB or other substrates, but directly solders the IC to the lead frame by using the flip-chip technology, a connection distance between the chip and the lead frame is short, so that the parasitic parameters may be effectively decreased, a heat dissipation channel and heat dissipation performance of the chip are improved, the performance of the power supply module is improved, and the passive elements are also directly soldered onto the lead frame by using the surface mount technology. For the power supply module of the embodiment of the present application, the costs are low, the number of internal solder joints is greatly reduced, failure probability of the solder joints is reduced, and reliability is increased. 
         [0097]    As shown in  FIG. 11 ,  FIG. 11  is a schematic diagram of another tri-chip structure of a power supply module according to an embodiment of the present application. 
         [0098]    In this embodiment, passive elements  611 ,  612 ,  613  are soldered onto a lead frame  60  by using the surface mount technology. The passive elements may specifically be inductors, capacitors, and resistors. An IC and two MOSFETs are three independent chips, which are an IC chip  62  and MOSFET chips  65 ,  66  shown in the drawing. The IC chip  62  is a flip chip, and is mounted and soldered onto the lead frame  60  by using the flip-chip technology; the two MOSFET chips  65 ,  66  may be flip chips. 
         [0099]    Different from the structure shown in  FIG. 6 , in this embodiment, the two MOSFET chips  65 ,  66  and two copper pieces  651 ,  661  are alternately stacked and mounted. As shown in  FIG. 11 , the MOSFET chip  65  is soldered onto the lead frame  60  through a manner corresponding to the chip packaging, the copper piece  651  is mounted to the MOSFET chip  65  by using the copper piece mount technology (that is, soldering or adhering), and then the MOSFET chip  66  is soldered onto the copper piece  651  through a manner corresponding to the chip packaging, the copper piece  661  is mounted to the MOSFET chip  66  by using the copper piece mount technology. The two copper pieces  651 ,  661  are configured to achieve the connection of the two MOSFET chips to the lead frame  60  and the interconnection of the two MOSFET chips. 
         [0100]    The lead frame  60  in this embodiment may be of an array structure, that is, multiple modules are arranged in matrix in the lead frame. 
         [0101]    The following assembling sequence may be used for integrating the power supply module with such a structure: 
         [0102]    (1) The passive elements are soldered onto the lead frame by using the surface mount technology. 
         [0103]    (2) The flip chip mode IC chip is mounted and soldered onto the lead frame by using the flip-chip technology, and then the whole module is cleaned. 
         [0104]    (3) Filling adhesive is filled in the bottom of the flip chip by using the underfill technology and cured in the bottom of the flip chip, and then the whole module is cleaned. 
         [0105]    (4) The two MOSFET chips and the two copper pieces are alternately stacked and mounted to complete the interconnection of the MOSFET chips and the lead frame, and then the whole module is cleaned. 
         [0106]    (5) The whole module is plastic encapsulated by using the plastic encapsulation technology. 
         [0107]    (6) The power supply module is separated through stamping separation or cutting separation after the plastic encapsulating is completed. 
         [0108]    It should be noted that, the cleaning processes in steps (2) to (5) or the underfill process in step (3) are optional, whether to the cleaning processes and the underfill process are may be determined according to actual needs. 
         [0109]    In addition, in an actual application, the above assembling sequence may be adjusted flexibly. For example, the chips are assembled first, and then the passive elements are assembled. 
         [0110]    In addition, it should be noted that, in an actual application, the position and the stacking sequence of the MOSFET chips and the copper pieces may be flexibly adjusted according to the structure and the packaging mode of the MOSFET chips actually used if only the copper pieces mounted on the MOSFET chips can achieve the connection of the electrodes of the MOSFETs to the lead frame, which is not limited by the embodiment of the present application. 
         [0111]    It can be seen that, in the power supply module of the embodiment of the present application, the interconnection of the MOSFET chips does not need gold wire or copper wire bonding, and the assembling of the IC chip does not need an embedded PCB or other substrates, but directly solders the IC onto the lead frame by using the flip-chip technology, a connection distance between the chip and the lead frame is short, so that the parasitic parameters may be effectively decreased, a heat dissipation channel and heat dissipation performance of the chip are improved, the performance of the power supply module is improved, and the passive elements are also directly soldered onto the lead frame by using the surface mount technology. For the power supply module of the embodiments of the present application, the costs are low, the number of the internal solder joints is greatly reduced, failure probability of the solder joints is reduced, and reliability is increased. 
         [0112]    In the embodiment of the tri-chip structure, in an alternative solution of the copper piece, the copper pieces in  FIG. 11  may be replaced by an aluminum strip. The aluminum strip is soldered onto a corresponding chip surface and a lead frame surface by using the aluminum line and aluminum strip soldering technology. The aluminum strip is a strip-shaped interconnecting material with the shape similar to that of the copper piece. 
         [0113]    It should be noted that, the IC the embodiments may only include the driver chip which is configured to drive the MOSFET driver circuit, or may be the control/driver chip with a PWM controller. The PWM controller is configured to control the above driver circuit. 
         [0114]    The technical solutions according to the embodiments of the present application may be used for semiconductor packaging and integrating of a POL (Point Of Load, point of load) power supply, the packaging and integrating of a PWM controller, and part of secondary power supply module integration. 
         [0115]    It should be noted that all embodiments in the present specification adopt an incremental manner for description. The same or similar parts of the embodiments may be referred to each other. Each embodiment focuses on the differences thereof from other embodiments. Some or all of the modules may be selected to achieve the objective of the present application according to actual needs. Persons with ordinary skill in the art can understand and implement the present application without inventive work. 
         [0116]    The above descriptions are merely exemplary embodiments of the present application, but not intended to limit the protection scope of the present application. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present application should fall within the protection scope of the present application.