Patent Publication Number: US-10770379-B2

Title: Semiconductor device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor device that can be used as a bidirectional switch. 
     2. Description of the Related Art 
     As a semiconductor device, there is known a semiconductor device (hereinafter referred to as “conventional semiconductor device”) that includes a first semiconductor chip, constituted of a MOSFET, a second semiconductor chip, constituted of a MOSFET, a first drain terminal, a first source terminal, a first gate terminal, a second drain terminal, a second source terminal, and a second gate terminal. The first drain terminal, the first source terminal, and the first gate terminal are electrically connected to a drain electrode, a source and a gate electrode, respectively of the first semiconductor chip. The second drain terminal, the second source terminal, and the second gate terminal are electrically connected to a drain electrode, a source and a gate electrode, respectively of the second semiconductor chip. 
     SUMMARY OF THE INVENTION 
     The inventor of preferred embodiments of the present invention described and claimed in the present application conducted an extensive study and research regarding a semiconductor device, such as the one described above, and in doing so, discovered and first recognized new unique challenges and previously unrecognized possibilities for improvements as described in greater detail below. 
     If the conventional semiconductor device is to be used as a bidirectional switch with an arrangement where two MOSFETs are connected back-to-back, the source terminal of the first semiconductor chip and the source terminal of the second semiconductor chip must be connected via a connecting member at an exterior of the semiconductor device. 
     An object of the present invention is to provide a semiconductor device which, in use as a bidirectional switch, does not require the source terminal of the first semiconductor chip and the source terminal of the second semiconductor chip to be connected externally and enables miniaturization. 
     In order to overcome the previously unrecognized and unsolved challenges described above, a preferred embodiment of the present invention provides a semiconductor device. A preferred embodiment of the present invention provides a semiconductor device. The semiconductor device includes a first semiconductor chip, constituted of a MOSFET, a second semiconductor chip, constituted of a MOSFET, a first drain terminal, electrically connected to a drain electrode of the first semiconductor chip, a first gate terminal, electrically connected to a gate electrode of the first semiconductor chip, a second drain terminal, electrically connected to a drain electrode of the second semiconductor chip, a second gate terminal, electrically connected to a gate electrode of the second semiconductor chip, a common source terminal, electrically connected to a source electrode of the first semiconductor chip and a source electrode of the second semiconductor chip, and a sealing resin, sealing the respective semiconductor chips and the respective terminals, and each of the terminals has an exposed surface substantially flush with an outer surface of the sealing resin and exposed from the outer surface. 
     With the present semiconductor device, the source electrode of the first semiconductor chip and the source electrode of the second semiconductor chip are electrically connected to the common source terminal. Therefore, when the present semiconductor device is used as a bidirectional switch, there is no need to connect the source electrode of the first semiconductor chip and the source electrode of the second semiconductor chip at an exterior of the semiconductor device. 
     Also with the present semiconductor device, each terminal has the exposed surface that is substantially flush with the outer surface of the sealing resin and exposed from the outer surface and therefore miniaturization can be achieved in comparison to a semiconductor device having lead terminals projecting from the outer surface of the sealing resin. 
     In the preferred embodiment of the present invention, the sealing resin has two opposing surfaces and a side surface joining the surfaces. 
     In the preferred embodiment of the present invention, the exposed surface of each terminal includes a first exposed surface substantially flush with one surface of the two surfaces of the sealing resin and exposed from the one surface. 
     In the preferred embodiment of the present invention, the exposed surface of each terminal further includes a second exposed surface, continuous to the first exposed surface of the terminal, substantially flush with the side surface of the sealing resin and exposed from the side surface. 
     In the preferred embodiment of the present invention, the sealing resin is of rectangular parallelepiped shape with plan view shapes of the two surfaces being rectangular and the side surface includes four side surfaces joining opposing sides of the two surfaces to each other. 
     In the preferred embodiment of the present invention, the one surface of the sealing resin has a first side and a second side that are mutually opposed, a third side joining one ends of the first side and the second side together, and a fourth side joining other ends of the first side and the second side together, the first exposed surface of the first drain terminal is disposed at a first corner portion at which the first side and the third side of the one surface are joined, and the first exposed surface of the second drain terminal is disposed at a second corner portion at which the first side and the fourth side of the one surface are joined. Also, the first exposed surface of the first gate terminal is disposed at a third corner portion at which the second side and the third side of the one surface are joined, and the first exposed surface of the second gate terminal is disposed at a fourth corner portion at which the second side and the fourth side of the one surface are joined. The first exposed surface of the common source terminal is disposed at an intermediate position of the one surface between the first exposed surface of the first gate terminal and the first exposed surface of the second gate terminal. 
     In the preferred embodiment of the present invention, the first exposed surface of each terminal has a rectangular shape having four sides parallel to the four sides of the one surface. And if, with the first exposed surface of each drain terminal, a length of the side parallel to the first side is LD1 and a length of the side parallel to the third side is LD2, and with the first exposed surface of each gate terminal, a length of the side that is parallel to the first side is LG1 and a length of the side parallel to the third side is LG2, and with the first exposed surface of the source terminal, a length of the side that is parallel to the first side is LS1 and a length of the side parallel to the third side is LS2, and an interval, along a direction along the first side, between the first exposed surface of the first drain terminal and the first exposed surface of the second drain terminal is d1, an interval, along a direction along the second side, between the first exposed surface of the first gate terminal and the first exposed surface of the common source terminal is d2, an interval, along the direction along the second side, between the first exposed surface of the second gate terminal and the first exposed surface of the common source terminal is d3, an interval, along a direction along the third side, between the first exposed surface of the first drain terminal and the first exposed surface of the first gate terminal is d4, and an interval, along a direction along the fourth side, between the first exposed surface of the second drain terminal and the first exposed surface of the second gate terminal is d5, the following formulae (a) and (b) are established.
 
 d 1= d 2= d 3= d 4= d 5  (a)
 
 LS 2= LG 2  (b)
 
     In the preferred embodiment of the present invention, the following formulae (c) to (f) are further established.
 
 LS 1= d 1  (c)
 
 LD 2= LD 1  (d)
 
 LG 2= LG 1  (e)
 
 LD 1&gt; LG 1  (f)
 
     In the preferred embodiment of the present invention, a sum of an area of the first exposed surface of the first drain terminal and an area of the first exposed surface of the second drain terminal is ¼ to ⅜ of an area of an entirety of the one surface of the sealing resin. 
     In the preferred embodiment of the present invention, a sum of an area of the first exposed surface of the first drain terminal, an area of the first exposed surface of the second drain terminal, an area of the first exposed surface of the first gate terminal, an area of the first exposed surface of the second gate terminal, and an area of the first exposed surface of the common source terminal is ⅓ to 11/24 of an area of an entirety of the one surface of the sealing resin. 
     In the preferred embodiment of the present invention, the first exposed surface of each of the first drain terminal, the second drain terminal, the first gate terminal, and the second gate terminal has, in plan view, a quadrilateral shape having a fifth side and a sixth side, matching two sides of a corner portion of the sealing resin at which the exposed surface is disposed, and a seventh side and an eighth side, with one ends connected to the fifth side and sixth side, respectively, and other ends connected to each other, and a connection portion of the seventh side and the eighth side is formed to a curved shape projecting outward of the first exposed surface. 
     In the preferred embodiment of the present invention, the first exposed surface of the common source terminal has, in plan view, a quadrilateral shape having a ninth side matching the second side of the one surface of the sealing resin, a tenth side and an eleventh side, with one ends respectively connected to respective ends of the ninth side, and a twelfth side, connecting the tenth side and the eleventh side, and a connection portion of the tenth side and the twelfth side and a connection portion of the eleventh side and the twelfth side are formed to curved shapes projecting outward of the first exposed surface. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustrative perspective view of a semiconductor device according to a first preferred embodiment of the present invention. 
         FIG. 2  is an illustrative plan view of  FIG. 1 . 
         FIG. 3  is an illustrative front view of  FIG. 1 . 
         FIG. 4  is an illustrative rear view of  FIG. 1 . 
         FIG. 5  is an illustrative left side view of  FIG. 1 . 
         FIG. 6  is an illustrative right side view of  FIG. 1 . 
         FIG. 7  is an illustrative bottom view of  FIG. 1 . 
         FIG. 8  is a plan view of an internal structure. 
         FIG. 9  is a sectional view taken along line IX-IX of  FIG. 8 . 
         FIG. 10  is a sectional view taken along line X-X of  FIG. 8 . 
         FIG. 11  is a sectional view taken along line XI-XI of  FIG. 8 . 
         FIG. 12  is a sectional view, corresponding to the sectional view of  FIG. 9 , of a mounted state of the semiconductor device of  FIG. 1 . 
         FIG. 13  is a sectional view, corresponding to the sectional view of  FIG. 10 , of the mounted state of the semiconductor device of  FIG. 1 . 
         FIG. 14  is an electric circuit diagram of an electric circuit of a bidirectional switch realized by the semiconductor device of  FIG. 1 . 
         FIG. 15  is a circuit diagram for describing an example of use of the bidirectional switch of  FIG. 14 . 
         FIG. 16  is an illustrative perspective view of a semiconductor device according to a second preferred embodiment of the present invention. 
         FIG. 17  is an illustrative plan view of  FIG. 16 . 
         FIG. 18  is an illustrative front view of  FIG. 16 . 
         FIG. 19  is an illustrative rear view of  FIG. 16 . 
         FIG. 20  is an illustrative left side view of  FIG. 16 . 
         FIG. 21  is an illustrative right side view of  FIG. 16 . 
         FIG. 22  is an illustrative bottom view of  FIG. 16 . 
         FIG. 23  is a plan view of an internal structure. 
         FIG. 24  is a sectional view taken along line XXIV-XXIV of  FIG. 23 . 
         FIG. 25  is a sectional view taken along line XXV-XXV of  FIG. 23 . 
         FIG. 26  is a sectional view taken along line XXVI-XXVI of  FIG. 23 . 
         FIG. 27  is a sectional view, corresponding to the sectional view of  FIG. 24 , of a mounted state of the semiconductor device of  FIG. 16 . 
         FIG. 28  is a sectional view, corresponding to the sectional view of  FIG. 25 , of the mounted state of the semiconductor device of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention shall now be described in detail with reference to the attached drawings. 
       FIG. 1  is an illustrative perspective view of a semiconductor device according to a first preferred embodiment of the present invention.  FIG. 2  is an illustrative plan view of  FIG. 1 .  FIG. 3  is an illustrative front view of  FIG. 1 .  FIG. 4  is an illustrative rear view of  FIG. 1 .  FIG. 5  is an illustrative left side view of  FIG. 1 .  FIG. 6  is an illustrative right side view of  FIG. 1 .  FIG. 7  is an illustrative bottom view of  FIG. 1 .  FIG. 8  is a plan view of an internal structure.  FIG. 9  is a sectional view taken along line IX-IX of  FIG. 8 .  FIG. 10  is a sectional view taken along line X-X of  FIG. 8 .  FIG. 11  is a sectional view taken along line XI-XI of  FIG. 8 . 
     The semiconductor device  1  shown in  FIG. 1  to  FIG. 11  is a device arranged to realize a bidirectional switch  100  represented by an electric circuit such as shown in  FIG. 14 . The bidirectional switch  100  includes a first MOSFET  101  and a second MOSFET  102  that are connected back-to-back (back-to-back connection). In the example of  FIG. 1 , each of the MOSFETs  101  and  102  is an n channel type MOSFET. The first MOSFET  101  has a first parasitic diode  111 . The first parasitic diode  111  is antiparallel-connected to the first MOSFET  101 . Specifically, an anode of the first parasitic diode  111  is connected to a source of the first MOSFET  101 , and a cathode of the first parasitic diode  111  is connected to a drain of the first MOSFET  101 . 
     The second MOSFET  102  includes a second parasitic diode  112 . The second parasitic diode  112  is antiparallel-connected to the second MOSFET  102 . Specifically, an anode of the second parasitic diode  112  is connected to a source of the second MOSFET  102 , and a cathode of the second parasitic diode  112  is connected to a drain of the second MOSFET  102 . 
     The source of the first MOSFET  101  is connected to the source of the second MOSFET  102 . That is, the source of the first MOSFET  101  and the source of the second MOSFET  102  are serially connected (back-to-back connected) such that directions of the first parasitic diode  111  and the second parasitic diode  112  are opposite. 
     The bidirectional switch  100  includes a first drain terminal  4 , connected to a drain electrode of the first MOSFET  101 , and a first gate terminal  5 , connected to a gate electrode of the first MOSFET  101 . The bidirectional switch  100  also includes a second drain terminal  6 , connected to a drain electrode of the second MOSFET  102 , and a second gate terminal  7 , connected to a gate electrode of the second MOSFET  102 . The bidirectional switch  100  further includes a common source terminal  8  connected to a source electrode of the first MOSFET  101  and a source electrode of the second MOSFET  102 . 
     When a gate signal applied to the first gate terminal  5  and the second gate terminal  7  is set to an active level, the first and second MOSFETs  101  and  102  are turned on and it thus becomes possible to make a current flow bidirectionally between the first drain terminal  4  and the second drain terminal  6 . When the gate signal applied to the first gate terminal  5  and the second gate terminal  7  is set to an inactive level, the first and second MOSFETs  101  and  102  are turned off. The parasitic diodes  111  and  112  are connected so as to be mutually opposite in direction and therefore in the state where the first and second MOSFETs  101  and  102  are off, the bidirectional flow of current is prevented. 
     Such a bidirectional switch  100  is, for example, provided in a power supply portion  130  inside a notebook type PC as shown in  FIG. 15 . Specifically, one drain terminal  6  of the bidirectional switch  100  is connected to a battery  121 . The other drain terminal  4  of the bidirectional switch  100  is connected to a DC input terminal  122  and an internal circuit  123 . The gate signal of the bidirectional switch  100  is controlled by a controller  124 . When the gate signal of the bidirectional switch  100  is set to the active level, the bidirectional switch  100  is turned on and the battery  121  is connected to the DC input terminal  122  and the internal circuit  123 . When the gate signal of the bidirectional switch  100  is set to the inactive level, the bidirectional switch  100  is turned off and the battery  121  is disconnected from the DC input terminal  122  and the internal circuit  123 . 
     The semiconductor device  1  shall now be described in detail with reference to  FIG. 1  to  FIG. 11 . In the following description, up shall refer to an upper side of the paper surface of  FIG. 3  (front view), down shall refer to a lower side of the paper surface of  FIG. 3 , left shall refer to a left side of the paper surface of  FIG. 3 , right shall refer to a right side of the paper surface of  FIG. 3 , front shall refer to a lower side of the paper surface of  FIG. 2  (plan view), and rear shall refer to an upper side of the paper surface of  FIG. 2 .  FIG. 1  shows an appearance of the semiconductor device  1  in a state where a bottom surface (lower surface) is disposed to face upward. In  FIG. 1 , a rear surface (rear side surface) of the semiconductor device  1  faces forward and a front surface (front side surface) of the semiconductor device  1  faces rearward. 
     Mainly referring to  FIG. 1  and  FIG. 8  to  FIG. 11 , the semiconductor device  1  includes a first semiconductor chip  2 , functioning as the first MOSFET  101  of  FIG. 14 , a second semiconductor chip  3 , functioning as the second MOSFET  102  of  FIG. 14 , the first drain terminal  4 , the first gate terminal  5 , the second drain terminal  6 , the second gate terminal  7 , the common source terminal  8 , first to fourth bonding wires (metal connecting members)  11  to  14 , and a sealing resin  9 . 
     The first semiconductor chip  2  is die-bonded on the first drain terminal  4  in a state where a surface (device forming surface), at a side at which a functional element is formed, is faced upward. A drain electrode is formed at a bottom surface (lower surface) of the first semiconductor chip  2 . The drain electrode of the first semiconductor chip  2  is mechanically and electrically connected to an upper surface of the first drain terminal  4 . 
     A source electrode (source pad)  2 S and a gate electrode (gate pad)  2 G (see  FIG. 8 ) are formed on a top surface (upper surface) of the first semiconductor chip  2 . The source electrode  2 S is connected to the common source terminal  8  by the bonding wire  11 . The gate electrode  2 G is connected to the first gate terminal  5  by the bonding wire  12 . 
     The second semiconductor chip  3  is die-bonded on the second drain terminal  6  in a state where a surface (device forming surface), at a side at which a functional element is formed, is faced upward. A drain electrode is formed at a bottom surface (lower surface) of the second semiconductor chip  3 . The drain electrode of the second semiconductor chip  3  is mechanically and electrically connected to an upper surface of the second drain terminal  6 . 
     A source electrode (source pad)  3 S and a gate electrode (gate pad)  3 G (see  FIG. 8 ) are formed on a top surface (upper surface) of the second semiconductor chip  3 . The source electrode  3 S is connected to the common source terminal  8  by the bonding wire  13 . The gate electrode  3 G is connected to the second gate terminal  7  by the bonding wire  14 . The respective terminals  4  to  8  are formed from metal thin plates constituted of copper or an alloy that contains copper. 
     The sealing resin  9  is constituted, for example, of an epoxy resin. As shown in  FIG. 1 , the sealing resin  9  is formed, for example, to a substantially rectangular parallelepiped shape that is flat in a vertical direction. The vertical direction is synonymous to a thickness direction of the semiconductor device  1 . The sealing resin  9  of substantially rectangular parallelepiped shape has an upper surface  9   a , constituting a top surface, a lower surface  9   b , constituting a bottom surface, and side surfaces  9   c  to  9   f  extending in substantially perpendicular directions with respect to the upper surface  9   a  and the lower surface  9   b . The upper surface  9   a  and the lower surface  9   b  are both flat surfaces. 
     The upper surface  9   a  and the lower surface  9   b  are formed to rectangular shapes that are long in a right/left direction in plan view. The side surfaces  9   c  to  9   f  are continuous to the upper surface  9   a  and the lower surface  9   b . In detail, the side surfaces  9   c  to  9   f  are formed over an entire periphery, excluding the upper surface  9   a  and the lower surface  9   b , of the semiconductor device  1 . In other words, the semiconductor device  1  has the four side surfaces  9   c  to  9   f  that are continuous to respective four sides of the upper surface  9   a  and the lower surface  9   b . The four side surface  9   c  to  9   f  are constituted of the front side surface  9   c , the left side surface  9   d , the rear side surface  9   e , and the right side surface  9   f.    
     As shown in  FIG. 8 , when an interior of the sealing resin  9  is viewed from a plane, the first drain terminal  4  is disposed at a left rearward corner portion, the second drain terminal  6  is disposed at a right rearward corner portion, the first gate terminal  5  is disposed at a left forward corner portion, the second gate terminal  7  is disposed at a right forward corner portion, and the common source terminal  8  is disposed at a position between the first gate terminal  5  and the second gate terminal  7 . 
     Referring to  FIG. 1 ,  FIG. 8 , and  FIG. 9 , the first drain terminal  4  has, integrally, a terminal main body portion  41  of rectangular parallelepiped shape having a rectangular bottom surface shape, and a terminal detachment restraining portion  42 . The terminal main body portion  41  has a lower surface  43 , an upper surface  44 , positioned at an opposite side to the lower surface  43 , and four side surfaces  45 , connecting the lower surface  43  and the upper surface  44 . The lower surface  43  of the terminal main body portion  41  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  43  of the terminal main body portion  41  constitutes a first exposed surface of the first drain terminal  4 . In bottom view (plan view), the terminal main body portion  41  is disposed at the left rear side corner portion of the lower surface  9   b  of the sealing resin  9  in an orientation where four sides of the lower surface  43  of the terminal main body portion  41  are substantially parallel to four sides of the lower surface  9   b  of the sealing resin  9 . 
     Among the four side surfaces  45  of the terminal main body portion  41 , each of the left side surface and the rear side surface has a first side surface portion  46 , a second side surface portion  48 , and a joining portion  47 . The first side surface portion  46  is continuous to the lower surface  43  and extends substantially perpendicularly toward the upper surface  44 . The second side surface portion  48  is continuous to the upper surface  44  and extends substantially perpendicularly toward the lower surface  43 . At each of the left side surface and the rear side surface of the terminal main body portion  41 , the first side surface portion  46  protrudes further outward in a side direction (direction orthogonal to the vertical direction) than the second side surface portion  48 . At each of the left side surface and the rear side surface of the terminal main body portion  41 , the joining portion  47  extends from the second side surface portion  48  toward the first side surface portion  46  while expanding outward gradually in the side direction and connects the second side surface portion  48  and the first side surface portion  46 . 
     The first side surface portion  46  of the left side surface and the first side surface portion  46  of the rear side surface of the terminal main body portion  41  are respectively substantially flush with the left side surface  9   d  and the rear side surface  9   e  of the sealing resin  9  and are exposed from the left side surface  9   d  and the rear side surface  9   e . That is, the first side surface portion  46  of the left side surface and the first side surface portion  46  of the rear side surface of the terminal main body portion  41  constitute second exposed surfaces of the first drain terminal  4  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  46  of the terminal main body portion  41  and angle portions formed by intersections of the respective first side surface portions  46  and the lower surface  43  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  42  is formed such as to protrude outward in side directions from the right side surface and the front side surface of the terminal main body portion  41 . The terminal detachment restraining portion  42  is formed to be thinner than the terminal main body portion  41 . An upper surface of the terminal detachment restraining portion  42  is flush with the upper surface  44  of the terminal main body portion  41 . The first semiconductor chip  2  is die-bonded to the upper surface of the first drain terminal  4  (including the upper surface  44  of the terminal main body portion  41  and the upper surface of the terminal detachment restraining portion  42 ). 
     A solder plating layer (not shown), arranged to increase solder wettability, is formed on the lower surface  43  of the terminal main body portion  41  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  46  exposed from the left side surface  9   d  and the rear side surface  9   e  of the sealing resin  9 . 
     The second drain terminal  6  has, integrally, a terminal main body portion  61  of rectangular parallelepiped shape having a rectangular bottom surface shape, and a terminal detachment restraining portion  62 . The terminal main body portion  61  has a lower surface  63 , an upper surface  64 , positioned at an opposite side to the lower surface  63 , and four side surfaces  65 , connecting the lower surface  63  and the upper surface  64 . The lower surface  63  of the terminal main body portion  61  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  63  of the terminal main body portion  61  constitutes a first exposed surface of the second drain terminal  6 . In bottom view (plan view), the terminal main body portion  61  is disposed at the right rear side corner portion of the lower surface  9   b  of the sealing resin  9  in an orientation where four sides of the lower surface  63  of the terminal main body portion  61  are substantially parallel to the four sides of the lower surface  9   b  of the sealing resin  9 . 
     Among the four side surfaces  65  of the terminal main body portion  61 , each of the right side surface and the rear side surface has a first side surface portion  66 , a second side surface portion  68 , and a joining portion  67 . The first side surface portion  66  is continuous to the lower surface  63  and extends substantially perpendicularly toward the upper surface  64 . The second side surface portion  68  is continuous to the upper surface  64  and extends substantially perpendicularly toward the lower surface  63 . At each of the right side surface and the rear side surface of the terminal main body portion  61 , the first side surface portion  66  protrudes further outward in a side direction (direction orthogonal to the vertical direction) than the second side surface portion  68 . At each of the right side surface and the rear side surface of the terminal main body portion  61 , the joining portion  67  extends from the second side surface portion  68  toward the first side surface portion  66  while expanding outward gradually in the side direction and connects the second side surface portion  68  and the first side surface portion  66 . 
     The first side surface portion  66  of the right side surface and the first side surface portion  66  of the rear side surface of the terminal main body portion  61  are respectively substantially flush with the right side surface  9   f  and the rear side surface  9   e  of the sealing resin  9  and are exposed from the right side surface  9   f  and the rear side surface  9   e . That is, the first side surface portion  66  of the right side surface and the first side surface portion  66  of the rear side surface of the terminal main body portion  61  constitute second exposed surfaces of the second drain terminal  6  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  66  of the terminal main body portion  61  and angle portions formed by intersections of the respective first side surface portions  66  and the lower surface  63  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  62  is formed such as to protrude outward in side directions from the left side surface and the front side surface of the terminal main body portion  61 . The terminal detachment restraining portion  62  is formed to be thinner than the terminal main body portion  61 . An upper surface of the terminal detachment restraining portion  62  is flush with the upper surface  66  of the terminal main body portion  61 . The second semiconductor chip  3  is die-bonded to the upper surface of the second drain terminal  6  (including the upper surface  64  of the terminal main body portion  61  and the upper surface of the terminal detachment restraining portion  62 ). 
     A solder plating layer (not shown), arranged to increase solder wettability, is formed on the lower surface  63  of the terminal main body portion  61  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  66  exposed from the right side surface  9   f  and the rear side surface  9   e  of the sealing resin  9 . 
     Referring to  FIG. 1 ,  FIG. 8 , and  FIG. 10 , the first gate terminal  5  has, integrally, a terminal main body portion  51  of rectangular parallelepiped shape having a rectangular bottom surface shape, and a terminal detachment restraining portion  52 . The terminal main body portion  51  has a lower surface  53 , an upper surface  54 , positioned at an opposite side to the lower surface  53 , and four side surfaces  55 , connecting the lower surface  53  and the upper surface  54 . The terminal main body portion  51  has its lower surface  53  exposed from the lower surface  9   b  of the sealing resin  9 . The lower surface  53  of the terminal main body portion  51  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  53  of the terminal main body portion  51  constitutes a first exposed surface of the first gate terminal  5 . In bottom view (plan view), the terminal main body portion  51  is disposed at the left front side corner portion of the lower surface  9   b  of the sealing resin  9  in an orientation where four sides of the lower surface  53  of the terminal main body portion  51  are substantially parallel to the four sides of the lower surface  9   b  of the sealing resin  9 . 
     Among the four side surfaces  55  of the terminal main body portion  51 , each of the left side surface and the front side surface has a first side surface portion  56 , a second side surface portion  58 , and a joining portion  57 . The first side surface portion  56  is continuous to the lower surface  53  and extends substantially perpendicularly toward the upper surface  54 . The second side surface portion  58  is continuous to the upper surface  54  and extends substantially perpendicularly toward the lower surface  53 . At each of the left side surface and the front side surface of the terminal main body portion  51 , the first side surface portion  56  protrudes further outward in a side direction (direction orthogonal to the vertical direction) than the second side surface portion  58 . At each of the left side surface and the front side surface of the terminal main body portion  51 , the joining portion  57  extends from the second side surface portion  58  toward the first side surface portion  56  while expanding outward gradually in the side direction and connects the second side surface portion  58  and the first side surface portion  56 . 
     The first side surface portion  56  of the left side surface and the first side surface portion  56  of the front side surface of the terminal main body portion  51  are respectively substantially flush with the left side surface  9   d  and the front side surface  9   c  of the sealing resin  9  and are exposed from the left side surface  9   d  and the front side surface  9   c . That is, the first side surface portion  56  of the left side surface and the first side surface portion  56  of the front side surface of the terminal main body portion  51  constitute second exposed surfaces of the first gate terminal  5  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  56  of the terminal main body portion  51  and angle portions formed by intersections of the respective first side surface portions  56  and the lower surface  53  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  52  is formed such as to protrude outward in side directions from the right side surface and the rear side surface of the terminal main body portion  51 . The terminal detachment restraining portion  52  is formed to be thinner than the terminal main body portion  51 . An upper surface of the terminal detachment restraining portion  52  is flush with the upper surface  54  of the terminal main body portion  51 . One end of the second bonding wire  12  is connected to the upper surface of the first gate terminal  5  (including the upper surface  54  of the terminal main body portion  51  and the upper surface of the terminal detachment restraining portion  52 ). 
     A solder plating layer (not shown), arranged to increase solder wettability, is formed on the lower surface  53  of the terminal main body portion  51  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  56  exposed from the left side surface  9   d  and the front side surface  9   c  of the sealing resin  9 . 
     The second gate terminal  7  has, integrally, a terminal main body portion  71  of rectangular parallelepiped shape having a rectangular bottom surface shape, and a terminal detachment restraining portion  72 . The terminal main body portion  71  has a lower surface  73 , an upper surface  74 , positioned at an opposite side to the lower surface  73 , and four side surfaces  75 , connecting the lower surface  73  and the upper surface  74 . The lower surface  73  of the terminal main body portion  71  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  73  of the terminal main body portion  71  constitutes a first exposed surface of the second gate terminal  7 . In bottom view (plan view), the terminal main body portion  71  is disposed at the right front side corner portion of the lower surface  9   b  of the sealing resin  9  in an orientation where four sides of the lower surface  73  of the terminal main body portion  71  are substantially parallel to the four sides of the lower surface  9   b  of the sealing resin  9 . 
     Among the four side surfaces  75  of the terminal main body portion  71 , each of the right side surface and the front side surface has a first side surface portion  76 , a second side surface portion  78 , and a joining portion  77 . The first side surface portion  76  is continuous to the lower surface  73  and extends substantially perpendicularly toward the upper surface  74 . The second side surface portion  78  is continuous to the upper surface  74  and extends substantially perpendicularly toward the lower surface  73 . At each of the right side surface and the front side surface of the terminal main body portion  71 , the first side surface portion  76  protrudes further outward in a side direction (direction orthogonal to the vertical direction) than the second side surface portion  78 . At each of the right side surface and the front side surface of the terminal main body portion  71 , the joining portion  77  extends from the second side surface portion  78  toward the first side surface portion  76  while expanding outward gradually in the side direction and connects the second side surface portion  78  and the first side surface portion  76 . 
     The first side surface portion  76  of the right side surface and the first side surface portion  76  of the front side surface of the terminal main body portion  71  are respectively substantially flush with the right side surface  9   f  and the front side surface  9   c  of the sealing resin  9  and are exposed from the right side surface  9   f  and the front side surface  9   c . That is, the first side surface portion  76  of the right side surface and the first side surface portion  76  of the front side surface of the terminal main body portion  71  constitute second exposed surfaces of the second drain terminal  7  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  76  of the terminal main body portion  71  and angle portions formed by intersections of the respective first side surface portions  76  and the lower surface  73  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  72  is formed such as to protrude outward in side directions from the left side surface and the rear side surface of the terminal main body portion  71 . The terminal detachment restraining portion  72  is formed to be thinner than the terminal main body portion  71 . An upper surface of the terminal detachment restraining portion  72  is flush with the upper surface  74  of the terminal main body portion  71 . One end of the fourth bonding wire  14  is connected to the upper surface of the second gate terminal  7  (including the upper surface  74  of the terminal main body portion  71  and the upper surface of the terminal detachment restraining portion  72 ). 
     A solder plating layer (not shown), arranged to increase solder wettability, is formed on the lower surface  73  of the terminal main body portion  71  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  76  exposed from the right side surface  9   f  and the front side surface  9   c  of the sealing resin  9 . 
     Referring to  FIG. 1 ,  FIG. 8 ,  FIG. 10 , and  FIG. 11 , the common source terminal  8  has, integrally, a terminal main body portion  81  of rectangular parallelepiped shape having a rectangular bottom surface shape, and a terminal detachment restraining portion  82 . The terminal main body portion  81  has a lower surface  83 , an upper surface  84 , positioned at an opposite side to the lower surface  83 , and four side surfaces  85 , connecting the lower surface  83  and the upper surface  84 . The lower surface  83  of the terminal main body portion  81  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  83  of the terminal main body portion  81  constitutes a first exposed surface of the common source terminal  8 . In bottom view (plan view), the terminal main body portion  81  is disposed at a front side central portion of the lower surface  9   b  of the sealing resin  9  in an orientation where four sides of the lower surface  83  of the terminal main body portion  81  are substantially parallel to the four sides of the lower surface  9   b  of the sealing resin  9 . 
     Among the four side surfaces  85  of the terminal main body portion  81 , the front side surface has a first side surface portion  86 , a second side surface portion  88 , and a joining portion  87 . The first side surface portion  86  is continuous to the lower surface  83  and extends substantially perpendicularly toward the upper surface  84 . The second side surface portion  88  is continuous to the upper surface  84  and extends substantially perpendicularly toward the lower surface  83 . The first side surface portion  86  protrudes further outward in a side direction (direction orthogonal to the vertical direction) than the second side surface portion  88 . The joining portion  87  extends from the second side surface portion  88  toward the first side surface portion  86  while expanding outward gradually in the side direction and connects the second side surface portion  88  and the first side surface portion  86 . 
     The first side surface portion  86  of the terminal main body portion  81  is substantially flush with the front side surface  9   c  of the sealing resin  9  and is exposed from the front side surface  9   c . That is, the first side surface portion  86  of the front side surface of the terminal main body portion  81  constitutes a second exposed surface of the common source terminal  8  that is continuous to the first exposed surface. An angle portion formed by intersection of the first side surface portion  86  of the terminal main body portion  81  and the lower surface  83  is also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  82  is formed such as to protrude rearward from the rear side surface of the terminal main body portion  81 . The terminal detachment restraining portion  82  is formed to be thinner than the terminal main body portion  81 . An upper surface of the terminal detachment restraining portion  82  is flush with the upper surface  84  of the terminal main body portion  81 . One ends of the first bonding wire  11  and the third bonding wire  13  are connected to the upper surface of the common source terminal  8  (including the upper surface  84  of the terminal main body portion  81  and the upper surface of the terminal detachment restraining portion  82 ). 
     A solder plating layer (not shown), arranged to increase solder wettability, is formed on the lower surface  83  of the terminal main body portion  81  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portion  86  exposed from the front side surface  9   c  of the sealing resin  9 . 
     In a state where the respective terminals  4 ,  5 ,  6 ,  7 , and  8  are resin-sealed together with the first semiconductor chip  2  and the second semiconductor chip  3 , the sealing resin  9  extends around to below the respective terminal detachment restraining portions  42 ,  52 ,  62 ,  72 , and  82 , thus preventing detachment of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  from the sealing resin  9 . 
     Referring to  FIG. 7 , the lower surface  9   b  of the sealing resin  9  has a front side  10   c , a left side  10   d , a rear side  10   e , and a right side  10   f  corresponding respectively to the front side surface  9   c , the left side surface  9   d , the rear side surface  9   e , and the right side surface  9   f . In the present preferred embodiment, a shape and size of the lower surface  43  of the first drain terminal  4  and a shape and size of the lower surface  63  of the second drain terminal  6  are substantially equal. Also, a shape and size of the lower surface  53  of the first gate terminal  5  and a shape and size of the lower surface  73  of the second gate terminal  7  are substantially equal. 
     Let a length of the front side  10   c  (rear side  10   e ) of the lower surface  9   b  of the sealing resin  9  be L and a length of the left side  10   d  (right side  10   f ) be W. With each of the lower surface  43  of the first drain terminal  4  and the lower surface  63  of the second drain terminal  6 , let a length of a side parallel to the front side  10   c  of the lower surface  9   b  be LD1 and a length of a side parallel to the left side  10   d  of the lower surface  9   b  be LD2. 
     With each of the lower surface  53  of the first gate terminal  5  and the lower surface  73  of the second gate terminal  7 , let a length of a side parallel to the front side  10   c  of the lower surface of the sealing resin  9  be LG1 and a length of a side parallel to the left side  10   d  of the lower surface of the sealing resin  9  be LG2. With the lower surface  83  of the common source terminal  8 , let a length of a side parallel to the front side  10   c  of the lower surface of the sealing resin  9  be LS1 and a length of a side parallel to the left side  10   d  of the lower surface of the sealing resin  9  be LS2. 
     Let an interval between the lower surface  43  of the first drain terminal  4  and the lower surface  63  of the second drain terminal  6  in a direction along the rear side  10   e  of the lower surface of the sealing resin  9  be d1. Let an interval between the lower surface  53  of the first gate terminal  5  and the lower surface  83  of the common source terminal  8  in a direction along the front side  10   c  of the lower surface of the sealing resin  9  be d2. Let an interval between the lower surface  73  of the second gate terminal  7  and the lower surface  83  of the common source terminal  8  in the direction along the front side  10   c  of the lower surface of the sealing resin  9  be d3. Let an interval between the lower surface  43  of the first drain terminal  4  and the lower surface  53  of the first gate terminal  5  in a direction along the left side  10   d  of the lower surface of the sealing resin  9  be d4. Let an interval between the lower surface  63  of the second drain terminal  6  and the lower surface  73  of the second gate terminal  7  in a direction along the right side  10   f  of the lower surface of the sealing resin  9  be d5. 
     The semiconductor device  1  preferably satisfies the following formulae (1) and (2).
 
 d 1= d 2= d 3= d 4= d 5  (1)
 
 LS 2= LG 2  (2)
 
     The semiconductor device  1  preferably further satisfies the following formulae (3), (4), (5), and (6).
 
 LS 1= d 1  (3)
 
 LD 2= LD 1  (4)
 
 LG 2= LG 1  (5)
 
 LD 1&gt; LG 1  (6)
 
     In the present preferred embodiment, LD1, LD2, LS1, LS2, LG1, LG2, LS1, LS2, and d1 to d5 are set to satisfy the formulae (1) to (6). 
     Specifically, in the present preferred embodiment, LD1, LD2, LS1, LS2, LG1, LG2, LS1, LS2, and d1 to d5 are set to the following lengths.
 
 LD 1= LD 2=0.3 mm
 
 LG 1= LG 2= LS 2=0.1 mm
 
 d 1= d 2= d 3= d 4= d 5= LS 1=0.2 mm
 
     For efficient dissipation of the heat of the semiconductor chips  2  and  3 , it is better for areas of the lower surfaces  43  and  63  of the drain terminals  4  and  6  to be larger. However if the areas of the lower surfaces  43  and  63  of the drain terminals  4  and  6  are increased, the semiconductor device  1  increases in size. In the present preferred embodiment, to miniaturize the semiconductor device  1 , sizes of the lower surfaces  43  and  63  of the drain terminals  4  and  6  are set to the minimum necessary sizes for heat dissipation of the semiconductor chips  2  and  3 . Specifically, the lengths LD1 and LD2 of the sides of the lower surfaces  43  and  63  of the drain terminals  4  and  6  are set to 0.3 mm. 
     The one ends of the bonding wires  12  and  14  are connected to the upper surfaces  54  and  74  of the gate terminals  5  and  7 . In the present preferred embodiment, in order to miniaturize the semiconductor device  1 , sizes of the upper surfaces  54  and  74  of the gate terminals  5  and  7  are set to the minimum necessary sizes for connecting the one ends of the bonding wires  12  and  14 . Specifically, the sizes of the upper surfaces  54  and  74  of the gate terminals  5  and  7  are set to 0.1 mm×0.1 mm. Accordingly, the lengths LG1 and LG2 of the sides of the upper surfaces  54  and  74  of the gate terminals  5  and  7  are set to 0.1 mm. 
     As shall be described below, in mounting the semiconductor device  1  on a mounting substrate  201  (see  FIG. 12  and  FIG. 13 ), the lower surfaces  43 ,  53 ,  63 ,  73 , and  83  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  are coated with solder  211 . In this process, a measure must be taken to prevent mutual contact of the solder coated on the lower surfaces of the terminals  4  to  8  that are adjacent. In the present preferred embodiment, in order to miniaturize the semiconductor device  1 , the intervals between the terminals  4  to  8  that are adjacent are set to the minimum necessary intervals for preventing mutual contact of the solder coated on the terminals  4  to  8  that are adjacent. Specifically, the intervals d1 to d5 between the terminals  4  to  8  that are adjacent are set to 0.2 mm. 
     To acquire such intervals d1 to d5, the lengths LS1 and LS2 of the two mutually adjacent sides of the lower surface  83  of the common source terminal  8  are set to 0.2 mm and 0.1 mm, respectively. 
     That is, in the present preferred embodiment, the length L of the semiconductor device  1  is 0.8 mm (=0.3 mm+0.2 mm+0.3 mm). The width W of the semiconductor device  1  is 0.6 mm (=0.1 mm+0.2 mm+0.3 mm). A height H (see  FIG. 5  and  FIG. 6 ) of the semiconductor device  1  is 0.36 mm. Also, a height h (see  FIG. 5  and  FIG. 6 ) of each of the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  exposed from the side surfaces  9   c  to  9   f  of the sealing resin  9  is 0.06 mm. The abovementioned dimensions of the respective portions are but an example and are not restricted thereto. 
     In the present preferred embodiment, a sum of the area of the lower surface  43  of the first drain terminal  4  and the area of the lower surface  63  of the second drain terminal  6  is 0.3*0.3+0.3*0.3+0.3*0.3=0.18 mm 2 . The total sum of the areas of the lower surfaces of the drain terminals  4  and  6  is ⅜ (=18/48) of an area of an entirety of a lower surface of the semiconductor device  1 . Also, a total sum of the areas of the lower surfaces of the metal terminals (the drain terminals  4  and  6 , the gate terminals  5  and  7 , and the common source terminal  8 ) is 11/24 (=(18+1+1+2)/48) of the area of the entirety of the lower surface of the semiconductor device  1 . A heat dissipation property is thus satisfactory with the semiconductor device  1  of the present preferred embodiment. 
     Also, the areas of the bottom surfaces  43  and  63  of the drain terminals  4  and  6  may be made even smaller to further prevent the mutual contact of solder. For example, it may be arranged such that LD2=0.2 mm and LD1=0.3 mm or LD2=0.3 mm and LD1=0.2 mm. In such case, the total sum of the areas of the lower surfaces  43  and  63  of the drain terminals  4  and  6  is ¼ (=12/48) of the area of the entirety of the lower surface of the semiconductor device  1  and the total sum of the areas of the lower surfaces of the metal terminals (the drain terminals  4  and  6 , the gate terminals  5  and  7 , and the common source terminal  8 ) is ⅓ (=(12+1+1+2)/48) of the area of the entirety of the lower surface of the semiconductor device  1 . 
     That is, from the standpoint of heat dissipation property, it is preferable for the total sum of the areas of the lower surfaces  43  and  63  of the drain terminals  4  and  6  to be ¼ to ⅜ of the area of the entirety of the lower surface of the semiconductor device  1 . Also preferably, the total sum of the areas of the lower surfaces of the metal terminals (the drain terminals  4  and  6 , the gate terminals  5  and  7 , and the common source terminal  8 ) is ⅓ to 11/24 of the area of the entirety of the lower surface of the semiconductor device  1 . 
       FIG. 12  and  FIG. 13  are illustrative sectional views of a mounted state of the semiconductor device  1 .  FIG. 12  is a sectional view corresponding to  FIG. 9 , and  FIG. 13  is a sectional view corresponding to  FIG. 10 . 
     The semiconductor device  1  is mounted on a surface of the mounting substrate (wiring substrate)  201 . A first drain terminal land  204 , a first gate terminal land  205 , a second drain terminal land  206 , a second gate terminal land  207 , and a common source terminal land  208  are formed on the surface  202  of the mounting substrate  201 . 
     To mount the semiconductor device  1  on the mounting substrate  201 , first, the solder  211  that is creamy is coated on surfaces of the respective lands  204  to  208  on the mounting substrate  201 . Next, the semiconductor device  1  is placed on the lands  204  to  208  in an orientation such that the lower surface  43  of the terminal  4 , the lower surface  53  of the terminal  5 , the lower surface  63  of the terminal  6 , the lower surface  73  of the terminal  7 , and the lower surface  83  of the terminal  8  of the semiconductor device  1  face the lands  204 ,  205 ,  206 ,  207 , and  208 , respectively, on the mounting substrate  201 . 
     Next, the semiconductor device  1 , in a state of being pressed against the lands  204  to  208  of the mounting substrate  201 , is heated for a fixed time and thereafter cooled. The terminals  4 ,  5 ,  6 ,  7 , and  8  of the semiconductor device  1  are thereby bonded by the solder  211  to the lands  204 ,  205 ,  206 ,  207 , and  208 , respectively, on the mounting substrate  201 . 
     The plating layers for increasing solder wettability are formed on the lower surfaces  43 ,  53 ,  63 ,  73 , and  83  and the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8 . Therefore when the lower surfaces  43 ,  53 ,  63 ,  73 , and  83  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  become bonded to the cream solder  211  on the respective lands  204 ,  205 ,  206 ,  207 , and  208 , the cream solder  211  closely adheres, so as to creep up, to the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8 . Consequently, a mounting strength of the semiconductor device  1  and the mounting substrate  201  can be improved and connection reliability can be improved. 
     Also, so-called solder fillets are thereby formed on the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  and therefore bonding (soldering) states of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  and the respective lands  204 ,  205 ,  206 ,  207 , and  208  can be readily inspected visually. 
     With the semiconductor device  1  according to the first preferred embodiment described above, the source electrode of the first semiconductor chip  2  and the source electrode of the second semiconductor chip  3  are electrically connected to the common source terminal  8 . Therefore there is no need to connect a source terminal of the first semiconductor chip  2  and a source terminal of the second semiconductor chip  3  at an exterior of the semiconductor device  1  in using the semiconductor device  1  as a bidirectional switch. 
     Also with the semiconductor device according to the first preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the lower surfaces (first exposed surfaces)  43 ,  53 ,  63 ,  73 , and  83  that are substantially flush with the lower surface  9   b  of the sealing resin  9  and are exposed from the lower surface  9   b  of the sealing resin  9 , and therefore miniaturization can be achieved in comparison to a semiconductor device having lead terminals projecting from an outer surface of the sealing resin  9 . 
     Also with the semiconductor device  1  according to the first preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the first side surface portions (second exposed surfaces)  46 ,  56 ,  66 ,  76 , and  86  that are exposed from the side surfaces  9   c  to  9   f  of the sealing resin  9  and therefore confirmation of the bonding states (mounting properties) of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  and the respective lands  204 ,  205 ,  206 ,  207 , and  208  is made easy. 
     Although with the first preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the first side surface portions (second exposed surfaces)  46 ,  56 ,  66 ,  76 , and  86  that are exposed from the side surfaces  9   c  to  9   f  of the sealing resin  9 , such exposed surfaces  46 ,  56 ,  66 ,  76 , and  86  do not have to be provided. 
     Also although with the first preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the lower surfaces (first exposed surfaces)  43 ,  53 ,  63 ,  73 , and  83  that are exposed from the lower surface  9   b  of the sealing resin  9 , the respective terminals  4  to  8  may have, in place of such exposed surfaces, upper surfaces that are substantially flush with the upper surface  9   a  of the sealing resin  9  and are exposed from the upper surface  9   a  of the sealing resin  9 . 
     Also, the first and second drain terminals  4  and  6  may have exposed surfaces exposed from one surface among the upper surface  9   a  and the lower surface  9   b  of the sealing resin  9 , and the first gate terminal  5 , the second gate terminal  7 , and the common source terminal  8  may have exposed surfaces exposed from the other surface among the upper surface  9   a  and the lower surface  9   b  of the sealing resin  9 . 
       FIG. 16  is an illustrative perspective view of a semiconductor device according to a second preferred embodiment of the present invention.  FIG. 17  is an illustrative plan view of  FIG. 16 .  FIG. 18  is an illustrative front view of  FIG. 16 .  FIG. 19  is an illustrative rear view of  FIG. 16 .  FIG. 20  is an illustrative left side view of  FIG. 16 .  FIG. 21  is an illustrative right side view of  FIG. 16 .  FIG. 22  is an illustrative bottom view of  FIG. 16 .  FIG. 23  is a plan view of an internal structure.  FIG. 24  is a sectional view taken along line XXIV-XXIV of  FIG. 23 .  FIG. 25  is a sectional view taken along line XXV-XXV of  FIG. 23 .  FIG. 26  is a sectional view taken along line XXVI-XXVI of  FIG. 23 . 
     As with the semiconductor device  1  according to the first preferred embodiment, the semiconductor device  1 A shown in  FIG. 16  to  FIG. 26  is a device arranged to realize the bidirectional switch  100  represented by the electric circuit such as shown in  FIG. 14 . 
     The semiconductor device  1 A shall now be described in detail with reference to  FIG. 16  to  FIG. 26 . The semiconductor device  1 A has a substantially oblong shape in plan view. For convenience of description, a +X direction, a −X direction, a +Y direction, a −Y direction, a +Z direction, and a −Z direction, shown in  FIG. 16 , may be used below. The +X direction and the −X direction are two directions along a long side of the semiconductor device  1 A in plan view and these shall be referred to simply as the “X direction” when referred to collectively. The +Y direction and the −Y direction are two directions along a short side of the semiconductor device  1 A in plan view and these shall be referred to simply as the “Y direction” when referred to collectively. 
     The +Z direction and the −Z direction are two directions perpendicular to a surface of the semiconductor device  1 A in plan view and these shall be referred to simply as the “Z direction” when referred to collectively. A +Z direction side surface of the semiconductor device  1 A may be referred to as an upper surface, and a −Z direction side surface of the semiconductor device  1 A may be referred to as a lower surface or a bottom surface.  FIG. 16  shows an appearance of the semiconductor device  1 A in a state where the lower surface (−Z direction side surface) is disposed to face upward. 
     Mainly referring to  FIG. 16  and  FIG. 23  to  FIG. 26 , the semiconductor device  1 A includes a first semiconductor chip  2 , functioning as the first MOSFET  101  of  FIG. 14 , and a second semiconductor chip  3 , functioning as the second MOSFET  102  of  FIG. 14 . The semiconductor device  1 A also includes the first drain terminal  4 , the first gate terminal  5 , the second drain terminal  6 , the second gate terminal  7 , the common source terminal  8 , first to fourth bonding wires (metal connecting members)  11  to  14 , and a sealing resin  9 . 
     A large difference between the semiconductor device  1 A according to the second preferred embodiment and the semiconductor device  1  according to the first preferred embodiment is that the shapes of the first drain terminal  4 , the first gate terminal  5 , the second drain terminal  6 , the second gate terminal  7 , and the common source terminal  8  are different. 
     The first semiconductor chip  2  is die-bonded on the first drain terminal  4  in a state where a surface (device forming surface), at a side at which a functional element is formed, is faced in the +Z direction. A drain electrode is formed at a bottom surface (lower surface) of the first semiconductor chip  2 . The drain electrode of the first semiconductor chip  2  is mechanically and electrically connected to an upper surface (+Z direction side surface) of the first drain terminal  4 . 
     A source electrode (source pad)  2 S and a gate electrode (gate pad)  2 G (see  FIG. 23 ) are formed on an upper surface of the first semiconductor chip  2 . The source electrode  2 S is connected to the common source terminal  8  by the bonding wire  11 . The gate electrode  2 G is connected to the first gate terminal  5  by the bonding wire  12 . 
     The second semiconductor chip  3  is die-bonded on the second drain terminal  6  in a state where a surface (device forming surface), at a side at which a functional element is formed, is faced upward. A drain electrode is formed at a bottom surface (lower surface) of the second semiconductor chip  3 . The drain electrode of the second semiconductor chip  3  is mechanically and electrically connected to an upper surface (+Z direction side surface) of the second drain terminal  6 . 
     A source electrode (source pad)  3 S and a gate electrode (gate pad)  3 G (see  FIG. 23 ) are formed on an upper surface of the second semiconductor chip  3 . The source electrode  3 S is connected to the common source terminal  8  by the bonding wire  13 . The gate electrode  3 G is connected to the second gate terminal  7  by the bonding wire  14 . The respective terminals  4  to  8  are formed from metal thin plates constituted of copper or an alloy that contains copper. 
     The sealing resin  9  is constituted, for example, of an epoxy resin. As shown in  FIG. 16 , the sealing resin  9  is formed, for example, to a rectangular parallelepiped shape that is flat in the Z direction. The Z direction is synonymous to a thickness direction of the semiconductor device  1 A. The sealing resin  9  of rectangular parallelepiped shape has an upper surface  9   a , constituting a +Z direction side surface, a lower surface  9   b , constituting a −Z direction side surface, and side surfaces  9   c  to  9   f  extending in substantially perpendicular directions with respect to the upper surface  9   a  and the lower surface  9   b . The upper surface  9   a  and the lower surface  9   b  are both flat surfaces. 
     The upper surface  9   a  and the lower surface  9   b  are formed to rectangular shapes that are long in the X direction in plan view. The side surfaces  9   c  to  9   f  are continuous to the upper surface  9   a  and the lower surface  9   b . In detail, the side surfaces  9   c  to  9   f  are formed over an entire periphery, excluding the upper surface  9   a  and the lower surface  9   b , of the semiconductor device  1 A. In other words, the semiconductor device  1 A has the four side surfaces  9   c  to  9   f  that are continuous to respective four sides of the upper surface  9   a  and the lower surface  9   b . The four side surfaces  9   c  to  9   f  are constituted of the +Y direction side surface  9   c , the −X direction side surface  9   d , the −Y direction side surface  9   e , and the +X direction side surface  9   f.    
     As shown in  FIG. 23 , when an interior of the sealing resin  9  is viewed from a plane, the first drain terminal  4  is disposed at a corner portion at a −Y direction side and −X direction side and the second drain terminal  6  is disposed at a corner portion at a −Y direction side and +X direction side. Also, the first gate terminal  5  is disposed at a corner portion at a +Y direction side and −X direction side, the second gate terminal  7  is disposed at a corner portion at a +Y direction side and +X direction side, and the common source terminal  8  is disposed at a position between the first gate terminal  5  and the second gate terminal  7 . 
     Referring to  FIG. 16 ,  FIG. 17 ,  FIG. 22 ,  FIG. 23 , and  FIG. 24 , the first drain terminal  4  has, integrally, a terminal main body portion  41  of quadratic prism shape having a quadrilateral bottom surface shape, and a terminal detachment restraining portion  42 . The terminal main body portion  41  has a lower surface  43 , an upper surface  44 , positioned at an opposite side to the lower surface  43 , and four side surfaces, connecting the lower surface  43  and the upper surface  44 . The four side surfaces are constituted of a +Y direction side surface  45   c , a −X direction side surface  45   d , a −Y direction side surface  45   e , and a +X direction side surface  45   f.    
     The −X direction side surface  45   d  is parallel to the Y direction in plan view. The −Y direction side surface  45   e  extends in the +X direction from a −Y direction side edge portion of the −X direction side surface  45   d  in plan view. The +X direction side surface  45   f  extends in the +Y direction and obliquely toward the −X direction from a +X direction side edge portion of the −Y direction side surface  45   e  in plan view. The +Y direction side surface  45   c  extends in the +X direction and obliquely toward the −Y direction from a +Y direction side edge portion of the −X direction side surface  45   d  and is connected to a +Y direction side edge portion of the +X direction side surface  45   f  in plan view. A connection portion of the +X direction side surface  45   f  and the +Y direction side surface  45   c  is formed to a curved surface  45   g  projecting outward of the terminal main body portion  41  in plan view. 
     The lower surface  43  of the terminal main body portion  41  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  43  of the terminal main body portion  41  constitutes a first exposed surface of the first drain terminal  4 . In bottom view (plan view), the terminal main body portion  41  is disposed at the corner portion at the −Y direction side and −X direction side of the lower surface  9   b  of the sealing resin  9 . More specifically, in bottom view, the terminal main body portion  41  is disposed in an orientation where, two sides, among four sides of the lower surface  43  of the terminal main body portion  41 , that correspond to a lower edge of the −X direction side surface  45   d  and a lower edge of the −Y direction side surface  45   e  are respectively substantially parallel to two sides, among four sides of the lower surface  9   b  of the sealing resin  9 , that correspond to a lower edge of the −X direction side surface  9   d  and a lower edge of the −Y direction side surface  9   e.    
     That is, the lower surface (first exposed surface)  43  of the terminal main body portion  41  is, in plan view, of a quadrilateral shape having a first side and a second side matching two sides of the corner portion of the sealing resin  9  at which the lower surface  43  is disposed and having a third side (lower edge of the +X direction side surface  45   f ) and a fourth side (lower edge of the +Y direction side surface  45   c ) with one ends connected respectively to the first side and the second side and other ends connected mutually. A connection portion of the third side and the fourth side is formed to a curved shape projecting outward of the lower surface (first exposed surface)  43 . 
     Each of the −X direction side surface  45   d  and the −Y direction side surface  45   e  of the terminal main body portion  41  has a first side surface portion  46 , a second side surface portion  48 , and a joining portion  47 . The first side surface portion  46  is continuous to the lower surface  43  and extends substantially perpendicularly toward the upper surface  44 . The second side surface portion  48  is continuous to the upper surface  44  and extends substantially perpendicularly toward the lower surface  43 . At each of −X direction side surface  45   d  and the −Y direction side surface  45   e  of the terminal main body portion  41 , the first side surface portion  46  protrudes further outward in a side direction (direction orthogonal to the Z direction) than the second side surface portion  48 . At each of the −X direction side surface  45   d  and the −Y direction side surface  45   e  of the terminal main body portion  41 , the joining portion  47  extends from the second side surface portion  48  toward the first side surface portion  46  while expanding outward gradually in the side direction and connects the second side surface portion  48  and the first side surface portion  46 . 
     The first side surface portion  46  of the −X direction side surface  45   d  and the first side surface portion  46  of the −Y direction side surface  45   e  of the terminal main body portion  41  are respectively substantially flush with the −X direction surface  9   d  and the −Y direction side surface  9   e  of the sealing resin  9  and are exposed from the −X direction side surface  9   d  and the −Y direction side surface  9   e . That is, the first side surface portion  46  of the −X direction side surface  45   d  and the first side surface portion  46  of the −Y direction side surface  45   e  of the terminal main body portion  41  constitute second exposed surfaces of the first drain terminal  4  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  46  of the terminal main body portion  41  and angle portions formed by intersections of the respective first side surface portions  46  and the lower surface  43  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  42  is formed such as to protrude outward in side directions from upper portions of the +X direction side surface  45   f  and the +Y direction side surface  45   c  of the terminal main body portion  41 . An upper surface of the terminal detachment restraining portion  42  is flush with the upper surface  44  of the terminal main body portion  41 . 
     At the +X direction side surface  45   f  and the +Y direction side surface  45   c  of the terminal main body portion  41 , a side surface portion  49 , between a lower edge of the terminal detachment restraining portion  42  and a lower edge of the terminal main body portion  41 , extends while narrowing gradually inward in side directions from the lower edge of the terminal detachment restraining portion  42  to the lower edge of the terminal main body portion  41  and connects the lower edge of the terminal detachment restraining portion  42  and the lower edge of the terminal main body portion  41 . A height position of the lower edge of the terminal detachment restraining portion  42  is further to the upper side (+Z direction side) by just h1 than height positions of upper ends of the first side surface portions  46  of the −X direction side surface  45   d  and the −Y direction side surface  45   e  of the terminal main body portion  41 . 
     The first semiconductor chip  2  is die-bonded to the upper surface of the first drain terminal  4  (including the upper surface  44  of the terminal main body portion  41  and the upper surface of the terminal detachment restraining portion  42 ). 
     A solder plating layer  94 , arranged to increase solder wettability, is formed on the lower surface  43  of the terminal main body portion  41  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  46  exposed from the −X direction side surface  9   d  and the −Y direction side surface  9   e  of the sealing resin  9 . In  FIG. 16  to  FIG. 23 , the lead plating layer  94  is omitted for convenience of description. 
     The second drain terminal  6  has, integrally, a terminal main body portion  61  of quadratic prism shape having a quadrilateral bottom surface shape, and a terminal detachment restraining portion  62 . The terminal main body portion  61  has a lower surface  63 , an upper surface  64 , positioned at an opposite side to the lower surface  63 , and four side surfaces, connecting the lower surface  63  and the upper surface  64 . The four side surfaces are constituted of a +Y direction side surface  65   c , a −X direction side surface  65   d , a −Y direction side surface  65   e , and a +X direction side surface  65   f.    
     The +X direction side surface  65   f  is parallel to the Y direction in plan view. The −Y direction side surface  65   e  extends in the −X direction from a −Y direction side edge portion of the +X direction side surface  65   f  in plan view. The −X direction side surface  65   d  extends in the +Y direction and obliquely toward the +X direction from a −X direction side edge portion of the −Y direction side surface  65   e  in plan view. The +Y direction side surface  65   c  extends in the −X direction and obliquely toward the −Y direction from a +Y direction side edge portion of the +X direction side surface  65   f  and is connected to a +Y direction side edge portion of the −X direction side surface  65   d  in plan view. A connection portion of the −X direction side surface  65   d  and the +Y direction side surface  65   c  is formed to a curved surface  65   g  projecting outward of the terminal main body portion  61  in plan view. 
     The lower surface  63  of the terminal main body portion  61  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  63  of the terminal main body portion  61  constitutes a first exposed surface of the second drain terminal  6 . In bottom view (plan view), the terminal main body portion  61  is disposed at the corner portion at the −Y direction side and +X direction side of the lower surface  9   b  of the sealing resin  9 . More specifically, in bottom view, the terminal main body portion  61  is disposed in an orientation where, two sides, among four sides of the lower surface  63  of the terminal main body portion  61 , that correspond to a lower edge of the +X direction side surface  65   f  and a lower edge of the −Y direction side surface  65   e  are respectively substantially parallel to two sides, among the four sides of the lower surface  9   b  of the sealing resin  9 , that correspond to a lower edge of the +X direction side surface  9   f  and the lower edge of the −Y direction side surface  9   e.    
     That is, the lower surface (first exposed surface)  63  of the terminal main body portion  61  is, in plan view, of a quadrilateral shape having a first side and a second side matching two sides of the corner portion of the sealing resin  9  at which the lower surface  63  is disposed and having a third side (lower edge of the +Y direction side surface  65   c ) and a fourth side (lower edge of the −X direction side surface  65   d ) with one ends connected respectively to the first side and the second side and other ends connected mutually. A connection portion of the third side and the fourth side is formed to a curved shape projecting outward of the lower surface (first exposed surface)  63 . 
     Each of the +X direction side surface  65   f  and the −Y direction side surface  65   e  of the terminal main body portion  61  has a first side surface portion  66 , a second side surface portion  68 , and a joining portion  67 . The first side surface portion  66  is continuous to the lower surface  63  and extends substantially perpendicularly toward the upper surface  64 . The second side surface portion  68  is continuous to the upper surface  64  and extends substantially perpendicularly toward the lower surface  63 . At each of the +X direction side surface  65   f  and the −Y direction side surface  65   e  of the terminal main body portion  61 , the first side surface portion  66  protrudes further outward in a side direction (direction orthogonal to the Z direction) than the second side surface portion  68 . At each of the +X direction side surface  65   f  and the −Y direction side surface  65   e  of the terminal main body portion  61 , the joining portion  67  extends from the second side surface portion  68  toward the first side surface portion  66  while expanding outward gradually in the side direction and connects the second side surface portion  68  and the first side surface portion  66 . 
     The first side surface portion  66  of the +X direction side surface  65   f  and the first side surface portion  66  of the −Y direction side surface  65   e  of the terminal main body portion  61  are respectively substantially flush with the +X direction side surface  9   f  and the −Y direction side surface  9   e  of the sealing resin  9  and are exposed from the +X direction side surface  9   f  and the −Y direction side surface  9   e . That is, the first side surface portion  66  of the +X direction side surface  65   f  and the first side surface portion  66  of the −Y direction side surface  65   e  of the terminal main body portion  61  constitute second exposed surfaces of the second drain terminal  6  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  66  of the terminal main body portion  61  and angle portions formed by intersections of the respective first side surface portions  66  and the lower surface  63  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  62  is formed such as to protrude outward in side directions from upper portions of the −X direction side surface  65   d  and the +Y direction side surface  65   c  of the terminal main body portion  61 . An upper surface of the terminal detachment restraining portion  62  is flush with the upper surface  64  of the terminal main body portion  61 . 
     At the −X direction side surface  65   d  and the +Y direction side surface  65   c  of the terminal main body portion  61 , a side surface portion  69 , between a lower edge of the terminal detachment restraining portion  62  and a lower edge of the terminal main body portion  61 , extends while narrowing gradually inward in side directions from the lower edge of the terminal detachment restraining portion  62  to the lower edge of the terminal main body portion  61  and connects the lower edge of the terminal detachment restraining portion  62  and the lower edge of the terminal main body portion  61 . A height position of the lower edge of the terminal detachment restraining portion  62  is further to the upper side (+Z direction side) by just h1 than height positions of upper ends of the first side surface portions  66  of the +X direction side surface  65   f  and the −Y direction side surface  65   e  of the terminal main body portion  61 . 
     The second semiconductor chip  3  is die-bonded to the upper surface of the second drain terminal  6  (including the upper surface  64  of the terminal main body portion  61  and the upper surface of the terminal detachment restraining portion  62 ). 
     A solder plating layer  96 , arranged to increase solder wettability, is formed on the lower surface  63  of the terminal main body portion  61  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  66  exposed from the +X direction side surface  9   f  and the −Y direction side surface  9   e  of the sealing resin  9 . In  FIG. 16  to  FIG. 23 , the lead plating layer  96  is omitted for convenience of description. 
     Referring to  FIG. 16 ,  FIG. 17 ,  FIG. 22 ,  FIG. 23 , and  FIG. 25 , the first gate terminal  5  has, integrally, a terminal main body portion  51  of quadratic prism shape having a quadrilateral bottom surface shape, and a terminal detachment restraining portion  52 . The terminal main body portion  51  has a lower surface  53 , an upper surface  54 , positioned at an opposite side to the lower surface  53 , and four side surfaces, connecting the lower surface  53  and the upper surface  54 . The four side surfaces are constituted of a +Y direction side surface  55   c , a −X direction side surface  55   d , a −Y direction side surface  55   e , and a +X direction side surface  55   f.    
     The +Y direction side surface  55   c  is parallel to the X direction in plan view. The −X direction side surface  55   d  extends in the −Y direction from a +X direction side edge portion of the +Y direction side surface  55   c  in plan view. The −Y direction side surface  55   e  extends in the +X direction and obliquely toward the +Y direction from a −Y direction side edge portion of the −X direction side surface  55   d  in plan view. The +X direction side surface  55   f  extends in the −Y direction and obliquely toward the −X direction from a +X direction side edge portion of the +Y direction side surface  55   c  and is connected to a +X direction side edge portion of the −Y direction side surface  55   e  in plan view. A connection portion of the +X direction side surface  55   f  and the −Y direction side surface  55   e  is formed to a curved surface  55   g  projecting outward of the terminal main body portion  51  in plan view. 
     The terminal main body portion  51  has its lower surface  53  exposed from the lower surface  9   b  of the sealing resin  9 . The lower surface  53  of the terminal main body portion  51  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  53  of the terminal main body portion  51  constitutes a first exposed surface of the first gate terminal  5 . In bottom view (plan view), the terminal main body portion  51  is disposed at the corner portion at the +Y direction side and −X direction side of the lower surface  9   b  of the sealing resin  9 . More specifically, in bottom view, the terminal main body portion  51  is disposed in an orientation where, two sides, among four sides of the lower surface  53  of the terminal main body portion  51 , that correspond to a lower edge of the −X direction side surface  55   d  and a lower edge of the +Y direction side surface  55   c  are respectively substantially parallel to two sides, among the four sides of the lower surface  9   b  of the sealing resin  9 , that correspond to the lower edge of the −X direction side surface  9   d  and a lower edge of the +Y direction side surface  9   c.    
     That is, the lower surface (first exposed surface)  53  of the terminal main body portion  51  is, in plan view, of a quadrilateral shape having a first side and a second side matching two sides of the corner portion of the sealing resin  9  at which the lower surface  53  is disposed and having a third side (lower edge of the +X direction side surface  55   f ) and a fourth side (lower edge of the −Y direction side surface  55   e ) with one ends connected respectively to the first side and the second side and other ends connected mutually. A connection portion of the third side and the fourth side is formed to a curved shape projecting outward of the lower surface (first exposed surface)  53 . 
     Each of the −X direction side surface  55   d  and the +Y direction side surface  55   c  of the terminal main body portion  51  has a first side surface portion  56 , a second side surface portion  58 , and a joining portion  57 . The first side surface portion  56  is continuous to the lower surface  53  and extends substantially perpendicularly toward the upper surface  54 . The second side surface portion  58  is continuous to the upper surface  54  and extends substantially perpendicularly toward the lower surface  53 . At each of the −X direction side surface  55   d  and the +Y direction side surface  55   c  of the terminal main body portion  51 , the first side surface portion  56  protrudes further outward in a side direction (direction orthogonal to the Z direction) than the second side surface portion  58 . At each of the −X direction side surface  55   d  and the +Y direction side surface  55   c  of the terminal main body portion  51 , the joining portion  57  extends from the second side surface portion  58  toward the first side surface portion  56  while expanding outward gradually in the side direction and connects the second side surface portion  58  and the first side surface portion  56 . 
     The first side surface portion  56  of the −X direction side surface  55   d  and the first side surface portion  56  of the +Y direction side surface  55   c  of the terminal main body portion  51  are respectively substantially flush with the left side surface  9   d  and the front side surface  9   c  of the sealing resin  9  and are exposed from the left side surface  9   d  and the front side surface  9   c . That is, the first side surface portion  56  of the −X direction side surface  55   d  and the first side surface portion  56  of the +Y direction side surface  55   c  of the terminal main body portion  51  constitute second exposed surfaces of the first gate terminal  5  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  56  of the terminal main body portion  51  and angle portions formed by intersections of the respective first side surface portions  56  and the lower surface  53  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  52  is formed such as to protrude outward in side directions from upper portions of the +X direction side surface  55   f  and the −Y direction side surface  55   e  of the terminal main body portion  51 . An upper surface of the terminal detachment restraining portion  52  is flush with the upper surface  54  of the terminal main body portion  51 . 
     At the +X direction side surface  55   f  and the −Y direction side surface  55   e  of the terminal main body portion  51 , a side surface portion  59 , between a lower edge of the terminal detachment restraining portion  52  and a lower edge of the terminal main body portion  51 , extends while narrowing gradually inward in side directions from the lower edge of the terminal detachment restraining portion  52  to the lower edge of the terminal main body portion  51  and connects the lower edge of the terminal detachment restraining portion  52  and the lower edge of the terminal main body portion  51 . A height position of the lower edge of the terminal detachment restraining portion  52  is further to the upper side (+Z direction side) by just h1 than height positions of upper ends of the first side surface portions  56  of the −X direction side surface  55   d  and the +Y direction side surface  55   c  of the terminal main body portion  51 . 
     One end of the second bonding wire  12  is connected to the upper surface  54  of the terminal main body portion  51  within the upper surface of the first gate terminal  5  (including the upper surface  54  of the terminal main body portion  51  and the upper surface of the terminal detachment restraining portion  52 ). 
     A solder plating layer  95 , arranged to increase solder wettability, is formed on the lower surface  53  of the terminal main body portion  51  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  56  exposed from the −X direction side surface  9   d  and the +Y direction side surface  9   c  of the sealing resin  9 . In  FIG. 16  to  FIG. 23 , the lead plating layer  95  is omitted for convenience of description. 
     The second gate terminal  7  has, integrally, a terminal main body portion  71  of quadratic prism shape having a quadrilateral bottom surface shape, and a terminal detachment restraining portion  72 . The terminal main body portion  71  has a lower surface  73 , an upper surface  74 , positioned at an opposite side to the lower surface  73 , and four side surfaces, connecting the lower surface  73  and the upper surface  74 . The four side surfaces are constituted of a +Y direction side surface  75   c , a −X direction side surface  75   d , a −Y direction side surface  75   e , and a +X direction side surface  75   f.    
     The +X direction side surface  75   f  is parallel to the Y direction in plan view. The +Y direction side surface  75   c  extends in the −X direction from a +Y direction side edge portion of the +X direction side surface  75   f  in plan view. The −X direction side surface  75   d  extends in the −Y direction and obliquely toward the +X direction from a −X direction side edge portion of the +Y direction side surface  75   c  in plan view. The −Y direction side surface  75   e  extends in the −X direction and obliquely toward the +Y direction from a −Y direction side edge portion of the +X direction side surface  75   f  and is connected to a −Y direction side edge portion of the −X direction side surface  75   d  in plan view. A connection portion of the −X direction side surface  75   d  and the −Y direction side surface  75   e  is formed to a curved surface  75   g  projecting outward of the terminal main body portion  71  in plan view. 
     The lower surface  73  of the terminal main body portion  71  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  73  of the terminal main body portion  71  constitutes a first exposed surface of the second gate terminal  7 . In bottom view (plan view), the terminal main body portion  71  is disposed at the corner portion at the +Y direction side and +X direction side of the lower surface  9   b  of the sealing resin  9 . More specifically, in bottom view, the terminal main body portion  71  is disposed in an orientation where, two sides, among four sides of the lower surface  73  of the terminal main body portion  71 , that correspond to lower ends of the +X direction side surface  75   f  and the +Y direction side surface  75   c  are respectively substantially parallel to two sides, among the four sides of the lower surface  9   b  of the sealing resin  9 , that correspond to lower ends of the +X direction side surface  9   f  and the +Y direction side surface  9   c.    
     That is, the lower surface (first exposed surface)  73  of the terminal main body portion  71  is, in plan view, of a quadrilateral shape having a first side and a second side matching two sides of the corner portion of the sealing resin  9  at which the lower surface  73  is disposed and having a third side (lower edge of the −X direction side surface  75   d ) and a fourth side (lower edge of the −Y direction side surface  75   e ) with one ends connected respectively to the first side and the second side and other ends connected mutually. A connection portion of the third side and the fourth side is formed to a curved shape projecting outward of the lower surface (first exposed surface)  73 . 
     Each of the +X direction side surface  75   f  and the +Y direction side surface  75   c  of the terminal main body portion  75  has a first side surface portion  76 , a second side surface portion  78 , and a joining portion  77 . The first side surface portion  76  is continuous to the lower surface  73  and extends substantially perpendicularly toward the upper surface  74 . The second side surface portion  78  is continuous to the upper surface  74  and extends substantially perpendicularly toward the lower surface  73 . At each of the +X direction side surface  75   f  and the +Y direction side surface  75   c  of the terminal main body portion  71 , the first side surface portion  76  protrudes further outward in a side direction (direction orthogonal to the Z direction) than the second side surface portion  78 . At each of the +X direction side surface  75   f  and the +Y direction side surface  75   c  of the terminal main body portion  71 , the joining portion  77  extends from the second side surface portion  78  toward the first side surface portion  76  while expanding outward gradually in the side direction and connects the second side surface portion  78  and the first side surface portion  76 . 
     The first side surface portion  76  of the +X direction side surface  75   f  and the first side surface portion  76  of the +Y direction side surface  75   c  of the terminal main body portion  71  are respectively substantially flush with the +X direction side surface  9   f  and the +Y direction side surface  9   c  of the sealing resin  9  and are exposed from the +X direction side surface  9   f  and the +Y direction side surface  9   c . That is, the first side surface portion  76  of the +X direction side surface  75   f  and the first side surface portion  76  of the +Y direction side surface  75   c  of the terminal main body portion  71  constitute second exposed surfaces of the second gate terminal  7  that are continuous to the first exposed surface. An angle portion formed by intersection of the two first side surface portions  76  of the terminal main body portion  71  and angle portions formed by intersections of the respective first side surface portions  76  and the lower surface  73  are also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  72  is formed such as to protrude outward in side directions from upper portions of the −X direction side surface  75   d  and the −Y direction side surface  75   e  of the terminal main body portion  71 . An upper surface of the terminal detachment restraining portion  72  is flush with the upper surface  74  of the terminal main body portion  71 . 
     At the −X direction side surface  75   d  and the −Y direction side surface  75   e  of the terminal main body portion  71 , a side surface portion  79 , between a lower edge of the terminal detachment restraining portion  72  and a lower edge of the terminal main body portion  71 , extends while narrowing gradually inward in side directions from the lower edge of the terminal detachment restraining portion  72  to the lower edge of the terminal main body portion  71  and connects the lower edge of the terminal detachment restraining portion  72  and the lower edge of the terminal main body portion  71 . A height position of the lower edge of the terminal detachment restraining portion  72  is further to the upper side (+Z direction side) by just h1 than height positions of upper ends of the first side surface portions  76  of the +X direction side surface  75   f  and the +Y direction side surface  75   c  of the terminal main body portion  71 . 
     One end of the fourth bonding wire  14  is connected to the upper surface  74  of the terminal main body portion  71  within the upper surface of the first gate terminal  7  (including the upper surface  74  of the terminal main body portion  71  and the upper surface of the terminal detachment restraining portion  72 ). 
     A solder plating layer (not shown)  97 , arranged to increase solder wettability, is formed on the lower surface  73  of the terminal main body portion  71  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portions  76  exposed from the +X direction side surface  9   f  and the +Y direction side surface  9   c  of the sealing resin  9 . In  FIG. 16  to  FIG. 23 , the lead plating layer  97  is omitted for convenience of description. 
     Referring to  FIG. 16 ,  FIG. 17 ,  FIG. 22 ,  FIG. 23 ,  FIG. 25 , and  FIG. 26 , the common source terminal  8  has, integrally, a terminal main body portion  81  of quadratic prism shape having a quadrilateral (trapezoidal) bottom surface shape, and a terminal detachment restraining portion  82 . The terminal main body portion  81  has a lower surface  83 , an upper surface  84 , positioned at an opposite side to the lower surface  83 , and four side surfaces, connecting the lower surface  83  and the upper surface  84 . The four side surfaces are constituted of a +Y direction side surface  85   c , a −X direction side surface  85   d , a −Y direction side surface  85   e , and a +X direction side surface  85   f.    
     The +Y direction side surface  85   c  is parallel to the X direction in plan view. The −X direction side surface  85   d  extends in the −Y direction and obliquely toward the +X direction from a −X direction side edge portion of the +Y direction side surface  85   c  in plan view. The +X direction side surface  85   f  extends in the −Y direction and obliquely toward the −X direction from a +X direction side edge portion of the +Y direction side surface  85   c  in plan view. The −Y direction side surface  85   e  connects a −Y direction side edge portion of the −X direction side surface  85   d  and a −Y direction side edge portion of the +X direction side surface  85   f  in plan view. Each of a connection portion of the −X direction side surface  85   d  and the −Y direction side surface  85   e  and a connection portion of the +X direction side surface  85   f  and the −Y direction side surface  85   e  is formed to a curved surface  85   g  projecting outward of the terminal main body portion  81 . 
     The lower surface  83  of the terminal main body portion  81  is substantially flush with the lower surface  9   b  of the sealing resin  9  and is exposed from the lower surface  9   b . That is, the lower surface  83  of the terminal main body portion  81  constitutes a first exposed surface of the common source terminal  8 . In bottom view (plan view), the terminal main body portion  81  is disposed at a front side central portion of the lower surface  9   b  of the sealing resin  9 . More specifically, in bottom view, the terminal main body portion  81  is disposed in an orientation where, a side, among four sides of the lower surface  83  of the terminal main body portion  81 , that corresponds to a lower edge of the +Y direction side surface  85   c  is substantially parallel to a side, among the four sides of the lower surface  9   b  of the sealing resin  9 , that corresponds to the lower edge of +Y direction side surface  9   c.    
     That is, the lower surface (first exposed surface)  83  of the terminal main body portion  81  is, in plan view, of a quadrilateral shape having a first side, matching a side of the lower surface  9   b  of the sealing resin  9  corresponding to the lower edge of the +Y direction side surface  9   c , a second side (lower edge of the −X direction side surface  85   d ) and a third side (lower edge of the +X direction side surface  85   f ) with respective one ends connected to respective ends of the first side, and a fourth side (lower edge of the −Y direction side surface  85   e ) connecting another end of the second side and another end of the third side. A connection portion of the second side and the fourth side and a connection portion of the third side and the fourth side are formed to curved shapes projecting outward of the lower surface (first exposed surface)  83  of the terminal main body portion  81 . 
     Among the four side surfaces  85  of the terminal main body portion  81 , the +Y direction side surface  85   c  has a first side surface portion  86 , a second side surface portion  88 , and a joining portion  87 . The first side surface portion  86  is continuous to the lower surface  83  and extends substantially perpendicularly toward the upper surface  84 . The second side surface portion  88  is continuous to the upper surface  84  and extends substantially perpendicularly toward the lower surface  83 . The first side surface portion  86  protrudes further outward in a side direction (direction orthogonal to the Z direction) than the second side surface portion  88 . The joining portion  87  extends from the second side surface portion  88  toward the first side surface portion  86  while expanding outward gradually in the side direction and connects the second side surface portion  88  and the first side surface portion  86 . 
     The first side surface portion  86  of the +Y direction side surface  85   c  of the terminal main body  81  is substantially flush with the +Y direction side surface  9   c  of the sealing resin  9  and is exposed from the +Y direction side surface  9   c . That is, the first side surface portion  86  of the +Y direction side surface  85   c  of the terminal main body portion  81  constitutes a second exposed surface of the common source terminal  8  that is continuous to the first exposed surface. An angle portion formed by intersection of the first side surface portion  86  of the terminal main body portion  81  and the lower surface  83  is also exposed from the sealing resin  9 . 
     The terminal detachment restraining portion  82  is formed such as to protrude outward in side directions from upper portions of the −X direction side surface  85   d , the −Y direction side surface  85   e , and the +X direction side surface  85   f  of the terminal main body portion  81 . An upper surface of the terminal detachment restraining portion  82  is flush with the upper surface  84  of the terminal main body portion  81 . 
     At the −X direction side surface  85   d , the −Y direction side surface  85   e , and the +X direction side surface  85   f  of the terminal main body portion  81 , a side surface portion  89 , between a lower edge of the terminal detachment restraining portion  82  and a lower edge of the terminal main body portion  81 , extends while narrowing gradually inward in side directions from the lower edge of the terminal detachment restraining portion  82  to the lower edge of the terminal main body portion  81  and connects the lower edge of the terminal detachment restraining portion  82  and the lower edge of the terminal main body portion  81 . A height position of the lower edge of the terminal detachment restraining portion  82  is further to the upper side (+Z direction side) by just h1 than a height position of an upper end of the first side surface portions  86  of the +Y direction side surface  85   c  of the terminal main body portion  81 . 
     One ends of the first bonding wire  11  and the third bonding wire  13  are connected to the upper surface  84  of the terminal main body portion  81  within the upper surface of the common source terminal  8  (including the upper surface  84  of the terminal main body portion  81  and the upper surface of the terminal detachment restraining portion  82 ). 
     A solder plating layer  98 , arranged to increase solder wettability, is formed on the lower surface  83  of the terminal main body portion  81  exposed from the lower surface  9   b  of the sealing resin  9  and the first side surface portion  86  exposed from the +Y direction side surface  9   c  of the sealing resin  9 . In  FIG. 16  to  FIG. 23 , the lead plating layer  98  is omitted for convenience of description. 
     In a state where the respective terminals  4 ,  5 ,  6 ,  7 , and  8  are resin-sealed together with the first semiconductor chip  2  and the second semiconductor chip  3 , the sealing resin  9  extends around to below the respective terminal detachment restraining portions  42 ,  52 ,  62 ,  72 , and  82 , thus preventing detachment of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  from the sealing resin  9 . 
     Referring to  FIG. 23 , in the present preferred embodiment, in plan view, Y-direction distances between each of a connection point of the wire  12  at the first gate terminal  5 , a connection point of the wire  11  at the common source terminal  8 , a connection point of the wire  13  at the common source terminal  8 , and a connection point of the wire  14  at the second gate terminal  7  and the +Y direction side surface  9   c  of the sealing resin  9  are all equal. 
     Also, in regard to the X direction, a connection point of the wire  12  and a connection point of the wire  11  at the first semiconductor chip  2  and a connection point of the wire  13  and a connection point of the wire  14  at the second semiconductor chip  3  are positioned between the connection point of the wire  12  at the first gate terminal  5  and the connection point of the wire  14  at the second gate terminal  7 . 
     Also, in regard to the X direction, the connection point of the wire  12  at the first gate terminal  5  is positioned in an interval from a −X direction end to a +X direction end of the first semiconductor chip  2 . On the other hand, in regard to the X direction, the connection point of the wire  11  at the common source terminal  8  is positioned further to a +X direction side than the +X direction end of the first semiconductor chip  2 . 
     Similarly, in regard to the X direction, the connection point of the wire  14  at the second gate terminal  7  is positioned in an interval from a −X direction end to a +X direction end of the second semiconductor chip  3 . On the other hand, in regard to the X direction, the connection point of the wire  13  at the common source terminal  8  is positioned further to a −X direction side than the −X direction end of the second semiconductor chip  3 . 
     Also, an X direction distance between the connection point of the wire  11  at the common source terminal  8  and the connection point of the wire  13  at the common source terminal  8  is shorter than an X direction distance between the connection point of the wire  12  at the first gate terminal  5  and the connection point of the wire  11  at the common source terminal  8 . Similarly, an X direction distance between the connection point of the wire  11  at the common source terminal  8  and the connection point of the wire  13  at the common source terminal  8  is shorter than an X direction distance between the connection point of the wire  14  at the second gate terminal  7  and the connection point of the wire  13  at the common source terminal  8 . 
     Referring to  FIG. 22 , the lower surface  9   b  of the sealing resin  9  has a +Y direction side  10   c , a −X direction side  10   d , a −Y direction side  10   e , and a +X direction side  10   f  corresponding respectively to the +Y direction side surface  9   c , the −X direction side surface  9   d , the −Y direction side surface  9   e , and the +X direction side surface  9   f . In the present preferred embodiment, in bottom view, a shape of the lower surface  43  of the first drain terminal  4  and a shape of the lower surface  63  of the second drain terminal  6  are line symmetrical with respect to a virtual line passing through a center of an X-direction gap between these surfaces and extending in the Y direction. Also, a shape of the lower surface  53  of the first gate terminal  5  and a shape of the lower surface  73  of the second gate terminal  7  are line symmetrical with respect to a virtual line passing through a center of an X-direction gap between these surfaces and extending in the Y direction. 
     Let a length of the +Y direction side  10   c  (−Y direction side  10   e ) of the lower surface  9   b  of the sealing resin  9  be L and a length of the −X direction side  10   d  (+X direction side  10   f ) be W. Let a length in the X direction of each of a side of the lower surface  43  of the first drain terminal  4  corresponding to the −Y direction side surface  45   e  and a side of the lower surface  63  of the second drain terminal  6  corresponding to the −Y direction side surface  65   e  be LD1. Let a length in the Y direction of each of a side of the lower surface  43  of the first drain terminal  4  corresponding to the −X direction side surface  45   d  and a side of the lower surface  63  of the second drain terminal  6  corresponding to the +X direction side surface  65   f  be LD2. 
     Let a length in the X direction of each of a side of the lower surface  53  of the first gate terminal  5  corresponding to the +Y direction side surface  55   c  and a side of the lower surface  73  of the second gate terminal  7  corresponding to the +Y direction side surface  75   c  be LG1. Let a length in the Y direction of each of a side of the lower surface  53  of the first gate terminal  5  corresponding to the −X direction side surface  55   d  and a side of the lower surface  73  of the second gate terminal  7  corresponding to the +X direction side surface  75   f  be LG2. Let an X-direction length of a side of the lower surface  83  of the common source terminal  8  corresponding to the +Y direction side surface  85   c  be LS1. Let a Y-direction length of the lower surface  83  of the common source terminal  8  be LS2. 
     Let an X-direction interval between the side of the lower surface  43  of the first drain terminal  4  corresponding to the −Y direction side surface  45   e  and the side of the lower surface  63  of the second drain terminal  6  corresponding to the −Y direction side surface  65   e  be d1. Let an X-direction interval between the side of the lower surface  53  of the first gate terminal  5  corresponding to the +Y direction side surface  55   c  and the side of the lower surface  83  of the common source terminal  8  corresponding to the +Y direction side surface  85   c  be d2. 
     Let an X-direction interval between the side of the lower surface  73  of the second gate terminal  7  corresponding to the +Y direction side surface  75   c  and the side of the lower surface  83  of the common source terminal  8  corresponding to the +Y direction side surface  85   c  be d3. Let a Y-direction interval between the side of the lower surface  43  of the first drain terminal  4  corresponding to the −X direction side surface  45   d  and the side of the lower surface  53  of the first gate terminal  5  corresponding to the −X direction side surface  55   d  be d4. Let a Y-direction interval between the side of the lower surface  63  of the second drain terminal  6  corresponding to the +X direction side surface  65   f  and the side of the lower surface  73  of the second gate terminal  7  corresponding to the +X direction side surface  75   f  be d5. 
     The semiconductor device  1  preferably satisfies the following formulae (7) and (8).
 
 d 1= d 2= d 3= d 4= d 5  (7)
 
 LS 2= LG 2  (8)
 
     The semiconductor device  1  preferably further satisfies the following formulae (9), (10), (11), and (12).
 
 LS 1= d 1  (9)
 
 LD 2= LD 1  (10)
 
 LG 2= LG 1  (11)
 
 LD 1&gt; LG 1  (12)
 
     In the present preferred embodiment, LS1, LS2, LG1, LG2, LS1, LS2, and d1 to d5 are set to satisfy the formulae (7) to (12). 
     Specifically, in the present preferred embodiment, LS1, LS2, LG1, LG2, LS1, LS2, and d1 to d5 are set to the following lengths.
 
 LD 1= LD 2=0.3=
 
 LG 1= LG 2= LS 2=0.1=
 
 d 1 =d 2= d 3= d 4= d 5= LS 1=0.2 mm
 
     For efficient dissipation of the heat of the semiconductor chips  2  and  3 , it is better for areas of the lower surfaces  43  and  63  of the drain terminals  4  and  6  to be larger. However if the areas of the lower surfaces  43  and  63  of the drain terminals  4  and  6  are increased, the semiconductor device  1 A increases in size. In the present preferred embodiment, to miniaturize the semiconductor device  1 A, sizes of the lower surfaces  43  and  63  of the drain terminals  4  and  6  are set to the minimum necessary sizes for heat dissipation of the semiconductor chips  2  and  3 . Specifically, the lengths LD1 and LD2 of the two sides of the lower surfaces  43  and  63  of the drain terminals  4  and  6  are set to 0.3 mm. 
     The one ends of the bonding wires  12  and  14  are connected to the upper surfaces  54  and  74  of the gate terminals  5  and  7 . In the present preferred embodiment, in order to miniaturize the semiconductor device  1 A, sizes of the upper surfaces  54  and  74  of the gate terminals  5  and  7  are set to the minimum necessary sizes for connecting the one ends of the bonding wires  12  and  14 . Specifically, the lengths LG1 and LG2 of the two sides of the upper surfaces  54  and  74  of the gate terminals  5  and  7  are set to 0.1 mm. 
     As shall be described below, in mounting the semiconductor device  1 A on a mounting substrate  201  (see  FIG. 12  and  FIG. 13 ), the lower surfaces  43 ,  53 ,  63 ,  73 , and  83  (more accurately, the lead plating layers  94 ,  95 ,  96 ,  97 , and  98 ) of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  are coated with solder  211 . In this process, a measure must be taken to prevent mutual contact of the solder coated on the lower surfaces of the terminals  4  to  8  (more accurately, the lead plating layers  94  to  98 ) that are adjacent. In the present preferred embodiment, in order to miniaturize the semiconductor device  1 A, the intervals between the terminals  4  to  8  that are adjacent are set to the minimum necessary intervals for preventing mutual contact of the solder coated on the terminals  4  to  8  (more accurately, the lead plating layers  94  to  98 ) that are adjacent. Specifically, the intervals d1 to d5 between the terminals  4  to  8  that are adjacent are set to 0.2 mm. 
     To acquire such intervals d1 to d5, the X-direction length LS1 and the Y-direction LS2 of the lower surface  83  of the common source terminal  8  are set to 0.2 mm and 0.1 mm, respectively. 
     That is, in the present preferred embodiment, the length L of the semiconductor device  1 A is 0.8 mm (=0.3 mm+0.2 mm+0.3 mm). The width W of the semiconductor device  1 A is 0.6 mm (=0.1 mm+0.2 mm+0.3 mm). A height H (see  FIG. 20  and  FIG. 21 ) of the semiconductor device  1 A is 0.36 mm. Also, a height h (see  FIG. 20  and  FIG. 21 ) of each of the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  exposed from the side surfaces  9   c  to  9   f  of the sealing resin  9  is 0.06 mm. The abovementioned dimensions of the respective portions are but an example and are not restricted thereto. 
       FIG. 27  and  FIG. 28  are illustrative sectional views of a mounted state of the semiconductor device  1 A.  FIG. 27  is a sectional view corresponding to  FIG. 24 , and  FIG. 28  is a sectional view corresponding to  FIG. 25 . 
     The semiconductor device  1 A is mounted on a surface of the mounting substrate (wiring substrate)  201 . A first drain terminal land  204 , a first gate terminal land  205 , a second drain terminal land  206 , a second gate terminal land  207 , and a common source terminal land  208  are formed on the surface  202  of the mounting substrate  201 . 
     To mount the semiconductor device  1 A on the mounting substrate  201 , first, the solder  211  that is creamy is coated on surfaces of the respective lands  204  to  208  on the mounting substrate  201 . Next, the semiconductor device  1 A is placed on the lands  204  to  208  in an orientation such that the lower surface  43  of the terminal  4 , the lower surface  53  of the terminal  5 , the lower surface  63  of the terminal  6 , the lower surface  73  of the terminal  7 , and the lower surface  83  of the terminal  8  of the semiconductor device  1 A face the lands  204 ,  205 ,  206 ,  207 , and  208 , respectively, on the mounting substrate  201 . 
     Next, the semiconductor device  1 A, in a state of being pressed against the lands  204  to  208  of the mounting substrate  201 , is heated for a fixed time and thereafter cooled. The terminals  4 ,  5 ,  6 ,  7 , and  8  of the semiconductor device  1 A are thereby bonded by the solder  211  to the lands  204 ,  205 ,  206 ,  207 , and  208 , respectively, on the mounting substrate  201 . 
     The plating layers  94 ,  95 ,  96 ,  97 , and  98  for increasing solder wettability are formed on the lower surfaces  43 ,  53 ,  63 ,  73 , and  83  and the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8 . Therefore when the lower surfaces  43 ,  53 ,  63 ,  73 , and  83  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  become bonded to the cream solder  211  on the respective lands  204 ,  205 ,  206 ,  207 , and  208 , the cream solder  211  closely adheres, so as to creep up, to the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8 . Consequently, amounting strength of the semiconductor device  1 A and the mounting substrate  201  can be improved and connection reliability can be improved. 
     Also, so-called solder fillets are thereby formed on the first side surface portions  46 ,  56 ,  66 ,  76 , and  86  of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  and therefore bonding (soldering) states of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  and the respective lands  204 ,  205 ,  206 ,  207 , and  208  can be readily inspected visually. 
     With the semiconductor device  1 A according to the second preferred embodiment described above, the source electrode of the first semiconductor chip  2  and the source electrode of the second semiconductor chip  3  are electrically connected to the common source terminal  8 . Therefore there is no need to connect a source terminal of the first semiconductor chip  2  and a source terminal of the second semiconductor chip  3  at an exterior of the semiconductor device  1 A in using the semiconductor device  1 A as a bidirectional switch. 
     Also with the semiconductor device  1 A according to the second preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the lower surfaces (first exposed surfaces)  43 ,  53 ,  63 ,  73 , and  83  that are substantially flush with the lower surface  9   b  of the sealing resin  9  and are exposed from the lower surface  9   b  of the sealing resin  9 , and therefore miniaturization can be achieved in comparison to a semiconductor device having lead terminals projecting from an outer surface of the sealing resin  9 . 
     Also with the semiconductor device  1 A according to the second preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the first side surface portions (second exposed surfaces)  46 ,  56 ,  66 ,  76 , and  86  that are exposed from the side surfaces  9   c  to  9   f  of the sealing resin  9  and therefore confirmation of the bonding states (mounting properties) of the respective terminals  4 ,  5 ,  6 ,  7 , and  8  and the respective lands  204 ,  205 ,  206 ,  207 , and  208  is made easy. 
     Although with the second preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the first side surface portions (second exposed surfaces)  46 ,  56 ,  66 ,  76 , and  86  that are exposed from the side surfaces  9   c  to  9   f  of the sealing resin  9 , such exposed surfaces  46 ,  56 ,  66 ,  76 , and  86  do not have to be provided. 
     Also although with the second preferred embodiment described above, the respective terminals  4 ,  5 ,  6 ,  7 , and  8  have the lower surfaces (first exposed surfaces)  43 ,  53 ,  63 ,  73 , and  83  that are exposed from the lower surface  9   b  of the sealing resin  9 , the respective terminals  4  to  8  may have, in place of such exposed surfaces, upper surfaces that are substantially flush with the upper surface  9   a  of the sealing resin  9  and are exposed from the upper surface  9   a  of the sealing resin  9 . 
     Also, the first and second drain terminals  4  and  6  may have exposed surfaces exposed from one surface among the upper surface  9   a  and the lower surface  9   b  of the sealing resin  9 , and the first gate terminal  5 , the second gate terminal  7 , and the common source terminal  8  may have exposed surfaces exposed from the other surface among the upper surface  9   a  and the lower surface  9   b  of the sealing resin  9 . 
     The present application corresponds to Japanese Patent Application No. 2017-57831 filed in the Japan Patent Office on Mar. 23, 2017 and Japanese Patent Application No. 2017-249969 filed in the Japan Patent Office on Dec. 26, 2017, and the entire disclosures of these applications are incorporated herein by reference. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and sprit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.