Abstract:
A power semiconductor module in which a main circuit terminal lead frame part and a control circuit lead frame part are bent toward a main circuit lead frame part, is provided. The power semiconductor module includes a main circuit part; a control circuit part and a control circuit terminal which are placed along a plane perpendicular to the main circuit part; a main circuit terminal placed along another plane perpendicular to the main circuit part, facing the control circuit part the control circuit terminal; a bonding wire; and a mold compound. Accordingly, it is possible to realize a light and compact intelligent power module that is simple to manufactured at a low cost.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a power semiconductor module, and more particularly, to a power semiconductor module in which a main circuit terminal lead frame part and a control circuit lead frame part are bent toward a main circuit lead frame part.  
           [0003]    2. Description of the Related Art  
           [0004]    Advancement in the power electronics industry, e.g., inverters and servo drivers, triggers a need for a light and compact power system that is manufactured at a low cost and operates more efficiently. To realize such a power system, electronic components are integrated into one package, i.e., a power semiconductor module, and a large number of power devices and control integrated circuits (IC), which control the power devices, are integrated into one power semiconductor module that is capable of controlling and protecting power devices. This power semiconductor module is called an ‘intelligent power module’.  
           [0005]    [0005]FIGS. 1 through 3 are views of conventional power semiconductor modules. FIG. 1 is a view of a semiconductor package disclosed in U.S. Pat. No. 6,002,166. Referring to FIG. 1, all components (some not shown) such as a semiconductor device and a control circuit device are combined with one another by solder (not shown), and a semiconductor chip  1  attached to a lead frame (not shown) is electrically connected with a terminal  5  by a bonding wire (not shown). The size of the semiconductor package of FIG. 1 is determined according to the sizes of all components attached to the lead frame. Thus, an increase in the number of components required results in an increase in the size of the semiconductor package. As the size of the semiconductor package increases, more components, such as a substrate and a mold compound, are required in fabricating the semiconductor package, thus increasing manufacturing costs therefor. Also, in the semiconductor package, the distance between a base substrate  3 , which contacts a heat sink (not shown), and a terminal  5  extended to the exterior of a mold compound  7 , which molds the semiconductor package, is approximately 4-5 mm. In other words, the isolation height h, which is the distance between the terminal  5  connected to the exterior circuit and the heat sink, is about 4-5 mm. Therefore, the isolation height of the semiconductor package is lower than the UL (underwriters laboratory) standard, i.e., 12.7 mm. If the isolation height is below the UL, the electrical insulation of a semiconductor package deteriorates.  
           [0006]    [0006]FIG. 2 is a view of a semiconductor package disclosed in U.S. Pat. No. 5,521,437. Referring to FIG. 2, all components are attached to an insulated metal substrate  16  and are electrically connected to one another by a bonding wire  18 . Thus, the size of the semiconductor package is determined by the size of the insulated metal substrate  16  to which all components are attached. That is, an increase in the number of the components required results in an increase in the size of the semiconductor package. Also, as the size of the semiconductor package increases, a great number of components, such as an insulated metal substrate and a mold compound, are required in fabricating the semiconductor package, thus raising manufacturing costs therefor. In FIG. 2, reference numerals  11 ,  13 ,  15 ,  17  and  19  denote a case, a control circuit terminal, a main circuit terminal, a main circuit part, and a control circuit unit, respectively.  
           [0007]    [0007]FIG. 3 is a view of a semiconductor package disclosed in U.S. Pat. No. 5,471,089. Referring to FIG. 3, a main circuit part  35  having a power semiconductor device and a control circuit part  33  including a control circuit device are formed on different substrates. The main circuit part  35  and the control circuit part  33  are installed at the top and bottom of the semiconductor package, respectively. Also, they are connected to each other by a metal connection  37 . Portions of the main circuit part  35  and the control circuit part  33  that contact the metal connection  37  are soldered by a solder  32 . In conclusion, in the semiconductor package shown in FIG. 3, the main circuit part  35  and the control circuit part  33  are formed on different substrates at the top and bottom of the semiconductor package. Also, the metal connection  37  and the solder  32  are indispensable in connecting the main circuit part  35  with the control circuit part  33 . Accordingly, it is very difficult to realize such a semiconductor package. Here, reference numerals  31  and  39  denote a terminal and a case, respectively.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    To solve the above problem, it is a first objective of the present invention to provide a light and compact power semiconductor module that is simple to manufacture at a lower cost.  
           [0009]    It is a second objective of the present invention to provide a method of fabricating such a power semiconductor module.  
           [0010]    Accordingly, to achieve an aspect of the first objective, there is provided a three-dimensional power semiconductor module according to an embodiment of the present invention. The power semiconductor module includes a main circuit part mounted on an isolation substrate and including a power semiconductor device; a control circuit part positioned along a plane, forming a predetermined angle to the main circuit part, the control circuit part attached to a control circuit device; a control circuit terminal connected to the control circuit part; a main circuit terminal positioned along another plane, forming a predetermined angle to the main circuit part; a bonding wire for electrically connecting the control circuit terminal, the control circuit device, the power semiconductor device, and the main circuit terminal; and a mold compound for completely molding the main circuit part and the control circuit part.  
           [0011]    Preferably, the main control part is attached to the isolation substrate by an adhesive, and the control circuit part is positioned along a plane perpendicular to the main circuit part.  
           [0012]    Preferably, the control circuit terminal is positioned along the same plane as the control circuit part.  
           [0013]    Preferably, the main circuit terminal is placed along a different plane, making it symmetrical with the control circuit part with reference to the main circuit part.  
           [0014]    Preferably, the main circuit part and the control circuit part are completely molded by the mold compound such that a trench is formed in a space between the control circuit terminal and the main circuit terminal.  
           [0015]    Preferably, an impulse buffer agent is formed at the ends of the bonding wire.  
           [0016]    To achieve another aspect of the first objective, there is provided a three dimensional power semiconductor module. The power semiconductor module includes a main circuit part mounted on an isolation substrate and including a power semiconductor device thereon; a control circuit part placed along a plane perpendicular to the main circuit part such that a control circuit device turns toward the power semiconductor device included in the main circuit part, the control circuit part including the control circuit device; a control circuit terminal placed along the same plane as the control circuit part, the control circuit terminal connected to the control circuit part; a main circuit terminal positioned along a different plane perpendicular to the main circuit part, facing the control circuit part and the control circuit terminal; a bonding wire for electrically connecting the control circuit terminal, the control circuit terminal, the power semiconductor device, and the main circuit terminal; and a mold compound for molding the main circuit part, the control circuit part, a portion of the main circuit terminal, and the entire isolation substrate, excluding its lower part, thereby conforming the module into a hexahedral shape.  
           [0017]    Preferably, the main circuit part is bonded to the isolation substrate by an adhesive.  
           [0018]    Preferably, an impulse buffer agent is formed at the ends of the bonding wire.  
           [0019]    To achieve still another aspect of the first objective, there is provided a three dimensional power semiconductor module. The power semiconductor module includes a main circuit part mounted on an isolation substrate and including a power semiconductor device; a control circuit part placed along a plane perpendicular to the main circuit part such that a control circuit device turns toward the power semiconductor device in the main circuit part, the control circuit part including the control circuit device; a control circuit terminal placed along the same plane as the control circuit part and connected to the control circuit part; a main circuit terminal placed along a different plane perpendicular to the main circuit part, facing the control circuit part and the control circuit terminal; a bonding wire for electrically connecting the control circuit terminal, the control circuit device, the power semiconductor device, and the main circuit terminal, the bonding wire including an impulse buffer agent at its end; and a mold compound for molding the main circuit part, the control circuit part, a portion of the main circuit terminal, and the entire substrate, excluding its lower portion, such that a trench is formed in a space between the control circuit part and the main circuit terminal.  
           [0020]    To achieve the second objective, there is provided a method of fabricating a three-dimensional power semiconductor module, including the steps of: (a) making a lead frame having notches in its bending regions, the lead frame including a control circuit terminal lead frame part, a control circuit lead frame part, a main circuit lead frame part, and a main circuit terminal lead frame part; (b) attaching a power semiconductor device to the main circuit lead frame part, attaching a control circuit device to the control circuit lead frame part, and performing wire bonding thereon; (c) bending the control circuit terminal lead frame part, the control circuit lead frame part, and the main circuit terminal lead frame part at the respective bending regions; (d) mounting the control circuit lead frame part on an isolation substrate, and then molding the lead frame and the isolation substrate; and (e) trimming the lead frame.  
           [0021]    Preferably, the bending regions includes a first bending region that is a border between the main circuit lead frame part and the control circuit lead frame part; and a second bending region that is a border between the main circuit terminal lead frame part functioning as a main circuit terminal and the main circuit lead frame part, the second bending region being connected to the main circuit lead frame part.  
           [0022]    Preferably, the step (b) further includes forming an impulse buffer agent on the metal connections of the bonding wire after the wire bonding.  
           [0023]    Preferably, in the step (d), the control circuit lead frame part is mounted on the isolation substrate after soldering on the isolation substrate.  
           [0024]    A semiconductor power module according to the present invention is configured such that a main circuit terminal lead frame part and a control circuit lead frame part are bent from a main circuit lead frame part, thereby reducing its size and weight, and manufacturing cost therefor. Also, a process of fabricating the power semiconductor module can be simplified. Further, it is possible to sufficiently increase the height of an isolation between an outer connection terminal and a heat sink. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The above objectives and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:  
         [0026]    [0026]FIGS. 1 through 3 are views of conventional power semiconductor modules;  
         [0027]    [0027]FIGS. 4 through 11B are views for explaining a method of fabricating a three dimensional power semiconductor module according to a preferred embodiment of the present invention and the structure thereof; and  
         [0028]    [0028]FIGS. 12A through 13B are views for explaining a method of fabricating a three dimensional power semiconductor module according to another preferred embodiment of the present invention and the structure thereof. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    The present invention now will be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. The same reference numerals in different drawings represent the same elements so that descriptions of the elements.  
         [0030]    A power semiconductor module according to a preferred embodiment of the present invention includes a main circuit part having a power semiconductor device and a control circuit part having a control circuit device. The power semiconductor module can be applicable to inverters, converters, and dynamic brakes. The power semiconductor device may include a power MOSFET (metal oxide semiconductor field effect transistor). The power MOSFET is preferably a vertical power MOSFET. A vertical power MOSFETs has a source region and a gate region at one side of a semiconductor die while the drain region is at the other side of the semiconductor die. In operation, current passes vertically through the semiconductor die. A vertical MOSFET may also have a planar or trenched gate region. Trenched gate regions are preferred in some embodiments.  
         [0031]    Hereinafter, a power semiconductor module according to the present invention will be now described with reference to FIGS. 11A, 11B,  13 A, and  13 B, and a method of fabricating the power semiconductor module will be later described with reference to FIGS. 4 through 13B.  
         [0032]    [0032]FIGS. 11A and 11B are views of a power semiconductor module according to a preferred embodiment of the present invention. In detail, FIG. 11A is a front view of the power semiconductor module, and FIG. 11B is a cross sectional view of the left side thereof  
         [0033]    Referring to FIGS. 11A and 11B, the power semiconductor module includes a main circuit part  230 , a control circuit part  220  and control circuit terminals  410  which are placed perpendicular at one portion of the main circuit part  230 , main circuit terminals  440  which are placed perpendicular at another portion of the main circuit part  230 , facing the control circuit part  220  and the control circuit terminals  410 , a bonding wire  250 , and a mold compound  350  formed to conform the power semiconductor module to a hexahedron. As shown in FIG. 11B, the mold compound  350  encapsulates the control circuit part  220 , the main circuit part  230 , and part of the isolation substrate  310  (except for a lower portion of the isolation substrate  310 ). Also, as shown in FIG. 11B, in this embodiment, the main circuit terminals  440  and the control circuit terminals  410  extend out of the mold compound  350  and are substantially parallel to each other.  
         [0034]    The main circuit part  230  has a structure in which a power semiconductor device  232  is attached to a main circuit lead frame (not shown). The main circuit part  230  is mounted on an isolation substrate  300 . The isolation substrate  300  and the main circuit part are placed firmly in contact with each other by the mold compound  350 . The main circuit part  230  maybe bonded to the isolation substrate  300  by an adhesive  310 .  
         [0035]    In the control circuit part  220 , a control circuit device  222  is attached to a control circuit lead frame (not shown). The control circuit part  220  is positioned perpendicular at a portion of the main circuit part  230  so that the control circuit device  222  included therein faces the power semiconductor device  232  in the main circuit part  230 . However, it is possible to position the control circuit part  220  such that it forms an acute angle or obtuse angle with the main circuit part  230  if necessary.  
         [0036]    The control circuit terminal  410  is directly connected to the control circuit part  220  and thus, preferably placed along the same vertical plane as the control circuit part  220 . The control circuit terminal  410  is electrically connected to the control circuit device  222  by the bonding wire  250 , allowing an electrical signal to be transmitted to the outside.  
         [0037]    The main circuit terminal  440  is placed on a plane perpendicular to the main circuit part  230  that is a different from the vertical plane along which the control circuit part  220  is positioned. Also, the main circuit terminal  440  faces the control circuit part  220 . The main circuit terminal  440  is electrically connected to the power semiconductor device  232  formed on the main circuit part  230 .  
         [0038]    The bonding wire  250  electrically connects the control circuit terminal  410  to the control circuit device  222 , and the control circuit device  222  to the power semiconductor device  232 . Also, it electrically connects the power semiconductor device  232  and the control circuit terminal  440 . It is preferable that an impulse buffer agent  252  is formed at the ends of the bonding wire  250 . The impulse buffer agent  252  prevents the bonding wires  250  from detaching from the main circuit part  230 , the control circuit part  220 , and the control circuit terminal  410  when an impulse is imparted to the connections which the bonding wires  250  are connected therewith. Therefore, it is preferable that the impulse buffer agent  252  is formed of a silicon based rubber or polyamide.  
         [0039]    The mold compound  350  molds the main circuit part  230 , the control circuit part  220 , a portion of the main circuit terminal  440 , a lower portion of the control circuit terminal  410 , and the entire isolation substrate  300  except for a lower portion thereof, thereby shaping the power semiconductor module into a hexahedron.  
         [0040]    [0040]FIGS. 13A and 13B are views of a power semiconductor module according to a modified example of the embodiment shown in FIGS. 11A and 11B. FIG. 13A is a front view of the power semiconductor module and FIG. 13B is a cross sectional view of the left side thereof. In comparison with the components in the semiconductor power module shown in FIGS. 11A and 11B, those of the semiconductor power module in FIGS. 13A and 13B, except for a mold compound, are the same in terms of structure, function, and effects and thus their explanations will be omitted here.  
         [0041]    Referring to FIGS. 13A and 13B, the power semiconductor module includes a main circuit part  230 , an isolation substrate  300 ; a control circuit part  220  and a control circuit terminal  410  that are placed along a plane perpendicular to the main circuit part  230 , a main circuit terminal  440  that is placed along another plane perpendicular to the main circuit part  230  and faces the control circuit part  220  and the control circuit terminal  410 , a bonding wire  250 , and a mold compound  350  having a trench  360  between the control circuit part  220  and the main circuit terminal  440 .  
         [0042]    The power semiconductor module shown in FIGS. 13A and 13B is characterized in that the mold compound  350  molds the main circuit part  230 , the control circuit part  220 , a portion of the main circuit terminal  440 , a portion of the control circuit terminal  410 , and the entire isolation substrate  300 , except for a lower portion thereof, so that a trench  360  is formed between the control circuit part  220  and the main circuit terminal  440 . Forming the trench  360  results in a reduction in the amount of material needed for the mold compound  350 , thereby lightening the weight of the power semiconductor module and lowering the manufacturing cost thereof.  
         [0043]    In conclusion, unlike the conventional power semiconductor modules shown in FIGS. 2 and 3, the size of an isolation substrate is small and no metal connections metals are required because only components related to a main circuit part are mounted on a power semiconductor module according to the present invention. Thus, it is possible to reduce the size and weight of the power semiconductor module and the manufacturing costs therefor. Further, a power semiconductor module according to the present invention uses a method of bending a lead frame, thus removing unnecessary components and processes as explained later with reference to FIGS. 4 through 13B. Accordingly, a process of fabricating the power semiconductor module can be simplified. Also, the size of a power semiconductor module according to the present invention is smaller compared with the conventional one shown in FIG. 1. Further, the isolation height h can be increased so that it satisfies the requirement of the UL (underwriters laboratory) standard providing that the height of isolation be 12.7 mm.  
         [0044]    Hereinafter, a method of fabricating a power semiconductor module according to the present invention will be now described with reference to FIGS. 4 through 13B.  
         [0045]    [0045]FIG. 4 is a plan view of a lead frame and FIGS. 5A and 5B are diagrams for explaining notches. In detail, FIGS. 5A and 5B are magnifications of embodiments of part “A” shown in FIG. 4. Referring to FIG. 4, a lead frame  100  having a notch  160  at first and second bending regions  151  and  152  is formed. The lead frame  100  is composed of a main circuit lead frame part  130 , a control circuit lead frame part  120 , a control circuit terminal lead frame part  110 , and a main circuit terminal lead frame part  140 .  
         [0046]    A power semiconductor device (not shown) is attached to the main circuit lead frame part  130 , and a control circuit device (not shown) is attached to the control circuit lead frame part  120 . The control circuit terminal lead frame part  110  is connected to the control circuit lead frame part  120  and functions as a control circuit terminal. The main circuit terminal lead frame part  140  is connected with the main circuit lead frame part  130  and functions as a main circuit terminal.  
         [0047]    The control circuit lead frame part  130  is bent at the first bending region  151 , which is a border between the main circuit lead frame part  130  and the control circuit lead frame part  120 . Also, the main circuit terminal lead frame part  140  is bent at the second bending region  152 , which is a border between the main circuit lead frame part  130  and the main circuit terminal lead frame part  140 .  
         [0048]    First, the notch  160  is formed at the first and second bending regions  151  and  152  so that the control circuit lead frame part  130  and the main circuit terminal lead frame part  140  can be easily bent. The shape of the notch  160  may vary. For example, the notch  160  may be formed with dots at the first and second bending regions  151  and  152 , as shown in FIG. 5A. Or, as shown in FIG. 5B, the notch  160  may be formed via a line at the first and second bending regions  151  and  152 .  
         [0049]    Thereafter, a power semiconductor device  232  and a control circuit device  222  are attached to the lead frame  100 , and a bonding wire  250  is bonded thereon, as shown in FIG. 6. The control circuit part  220  is completed by attaching the control circuit device  222  to the control circuit lead frame part  120  shown in FIG. 4, and the main circuit part  230  is completed by attaching the power semiconductor device  232  to the main circuit lead frame part  130  shown in FIG. 4. The bonding wire  250  bonds the control circuit terminal lead frame part  110  to the control circuit device  222 , the control circuit device  222  to the power semiconductor device  232 , and the power semiconductor device  232  to the main circuit terminal lead frame part  140 , for an electrical connection therebetween.  
         [0050]    [0050]FIG. 7 is a magnification of part “B” shown in FIG. 6. Referring to FIG. 7, an impulse buffer agent  252  is formed on metal connections electrically connecting the bonding wire  250  and the control circuit lead frame part  110 . The impulse buffer agent  252  is preferably formed at every end of the bonding wire  22 , which is electrically bonded with other components. With the impulse buffer agent  252 , it is possible to prevent the bonding wire  250  from detaching from the main circuit terminal lead frame part  140  or the control circuit lead frame part  120  when an impulse is imparted thereto. The impulse buffer agent  252  is preferably formed of a silicon-based rubber or polyamide.  
         [0051]    Next, as shown in FIGS. 8A through 8C, the control circuit part  220  is bent at the first bending region  151  shown in FIG. 6, and the main circuit terminal lead frame part  140  is bent at the second bending region  152 . FIG. 8A is a plan view of the lead frame  110  in which the control circuit part  220  and the main circuit terminal lead frame  140  are bent, FIG. 8B is a front view of the lead frame shown in FIG. 8A, and FIG. 8C is a cross sectional view of the left side of the lead frame shown in FIG. 8A.  
         [0052]    Preferably, the control circuit part  220  is bent to form a right angle  224  (hereinafter, a ‘first angle’) to the main circuit part  230 , and the main circuit terminal lead frame part  140  is bent to form a right angle  144  (hereinafter, a ‘second angle’) to the main circuit part  230 . However, the control circuit part  220  and the main circuit terminal lead frame part  140  may be bent to form first and second angles  244  and  144  which are acute or obtuse. During the bending process, the first and second angles  224  and  144  are preferably at the same angle so that the control circuit part  220  and the control circuit terminal lead frame  110  are symmetrical to the main circuit terminal lead frame part  140  on the main circuit part  230 .  
         [0053]    As shown in FIGS. 9A and 9B, the main circuit part  230  is mounted on the isolation substrate  300  so that its lower portion  235  is in contact with the isolation substrate  300 . FIG. 9A is a front view of the lead frame  100  in which the main circuit part  230  is mounted on the isolation substrate  300 , and FIG. 9B is a cross sectional view of the left side of the lead frame  100  shown in FIG. 9A. The lower portion of the main circuit part  230  may be in contact with the isolation substrate  300  via an adhesive  310 . The width of the isolation substrate  300  is preferably larger than that of the main circuit part  230 . In this power semiconductor module, the control circuit part does not need to be formed on the isolation substrate  300 , thus reducing manufacturing cost and the weight of the power semiconductor module.  
         [0054]    Next, as shown in FIGS. 10A and 10B, a molding process is performed on the main circuit part  230 , the control circuit part  220 , a portion of the main circuit terminal lead frame part  140 , and the entire isolation substrate  300 , excluding a portion that contacts a heat sink (not shown). FIG. 10A is a front view of the lead frame  100  in which a molding process is performed, and FIG. 10B is a cross sectional view of the left side of the lead frame  100  shown in FIG. 10A. The exterior of a power semiconductor module according to the present invention is shaped into a hexahedron by the molding process.  
         [0055]    As shown in FIGS. 11A and 11B, the lead frame  100  is trimmed to form the control circuit terminal  410  and the main circuit terminal  440 . FIG. 11A is a front view of the lead frame  100  in which a trimming process is performed, and FIG. 11B is a cross sectional view of the left side of the lead frame  100  shown in FIG. 11A.  
         [0056]    [0056]FIGS. 12A through 13B are views for explaining a method of fabricating a modified example of the embodiment of the power semiconductor module shown in FIGS. 11A and 11B. Compared with the previous embodiment, the processes of fabricating and bending a lead frame are the same for the modified examples, but a molding process is different. In other words, a lead frame is fabricated and then is bent as explained in the previous embodiment (refer to the descriptions for FIGS. 4 through 9B). FIG. 12A is a front view of the modified example of the power semiconductor module in which a molding process has been performed, and FIG. 12B is a cross sectional view of the left side of the power semiconductor module shown in FIG. 12A. Also, FIG. 13A is a front view of the power semiconductor module in which a trimming process has been performed, and FIG. 13B is a cross sectional view of the left side of the power semiconductor module shown in FIG. 13A.  
         [0057]    Referring to FIGS. 12A and 12B, the main circuit part  230 , the control circuit device  220 , a portion of the main circuit terminal lead frame part  140 , and the entire isolation compound  300 , excluding a portion contacting a heat sink (not shown), are molded by a mold compound  350  to form a trench  360  in a space formed by the control circuit part  230  and the main circuit terminal lead frame part  140 . Next, the lead frame  100  is trimmed to form the control circuit terminal  410  and the main circuit terminal  440 . It is possible to save trouble, time and costs needed in molding an unnecessary portion during the manufacture of the power semiconductor module by forming the trench  360 , thereby reducing manufacturing costs.  
         [0058]    A power semiconductor module according to the present invention is configured such that a main circuit terminal lead frame part and a control circuit lead frame part are bent from a main circuit lead frame part. As a result, only a portion corresponding to the main circuit part of the power semiconductor module is mounted on an isolation substrate, thereby reducing the size and weight of the power semiconductor module that is one package into which electronic components are integrated and reducing manufacturing cost therefor. Also, a process of fabricating the power semiconductor module can be simplified. Further, it is possible to sufficiently increase the height of an isolation between an outer connection terminal and a heat sink.