Patent Publication Number: US-2023163051-A1

Title: Semiconductor device

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to semiconductor devices. 
     Description of the Background Art 
     A semiconductor device in which a plurality of terminals protruding from one side of a mold member are bent alternately at a location close to the mold member and at a location away from the mold member along the one side has been proposed. That is to say, the semiconductor device in which bends as bent portions of the terminals are staggered along the one side of the mold member has been proposed. 
     Furthermore, Japanese Patent Application Laid-Open No. 2019-75523 proposes a configuration in which bends located close to a mold member and bends located away from the mold member differ in width, for example. 
     In the configuration proposed in Japanese Patent Application Laid-Open No. 2019-75523, the bends located close to the mold member and the bends located away from the mold member differ in width. In this configuration, however, angles at which terminals are bent at the bends might vary when the terminals are bent with constant bending force. 
     SUMMARY 
     The present disclosure has been conceived in view of a problem as described above, and it is an object of the present disclosure to provide technology that can achieve a semiconductor device including appropriate terminals. 
     A semiconductor device according to the present disclosure includes: a semiconductor element; a mold member covering the semiconductor element; and a first terminal and a second terminal electrically connected to the semiconductor element, protruding from one side of the mold member, and alternating along the one side. The first terminal includes a first bend, and the second terminal includes: a second bend located further from the one side of the mold member than the first bend, and having the same width as the first bend in plan view; and a portion located between the one side of the mold member and the second bend of the second terminal, and being wider than the second bend. 
     The semiconductor device including appropriate terminals can be achieved. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a plan view illustrating a configuration of a semiconductor device according to Embodiment 1; 
         FIG.  2    is a cross-sectional view illustrating the configuration of the semiconductor device according to Embodiment 1; 
         FIG.  3    is a side view illustrating an outer shape of the semiconductor device according to Embodiment 1; 
         FIG.  4    is a plan view illustrating a portion of the configuration of the semiconductor device according to Embodiment 1; 
         FIG.  5    is a plan view illustrating a portion of the configuration of the semiconductor device according to Embodiment 1; 
         FIG.  6    is a flowchart showing a method of manufacturing the semiconductor device according to Embodiment 1; 
         FIG.  7    is a cross-sectional view illustrating a portion of a configuration of a semiconductor device according to Modification 2; and 
         FIG.  8    is a plan view illustrating a portion of a configuration of a semiconductor device according to Embodiment 2. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments will be described below with reference to the accompanying drawings. Features described in the embodiments below are examples, and all the features are not necessarily required. In description made below, similar components in the embodiments bear the same or similar reference signs, and different components will mainly be described. In description made below, specific locations and directions represented by terms such as “upper”, “lower”, “left”, “right”, “front”, and “back” may not necessarily match locations and directions in actual implementation. 
     Embodiment 1 
       FIG.  1    is a plan view illustrating a configuration of a semiconductor device according to Embodiment 1, and  FIG.  2    is a cross-sectional view illustrating the configuration. 
     The semiconductor device according to Embodiment 1 includes semiconductor elements. The semiconductor elements include integrated circuits (ICs)  1 , power chips  2   a,  freewheel diodes  2   b,  and bootstrap diodes  3 . The ICs  1 , the power chips  2   a,  the freewheel diodes  2   b,  and the bootstrap diodes  3  are electrically connected, and the power chips  2   a  and the freewheel diodes  2   b  as second semiconductor elements are controlled and driven by the ICs  1  as first semiconductor elements. An upper IC  1  in  FIG.  1    is a high voltage IC to control an upper arm composed of three power chips  2   a,  and a lower IC in  FIG.  1    is a low voltage IC to control a lower arm composed of three power chips  2   a.    
     At least the ICs  1  or the power chips  2   a  are semiconductor switching elements, such as metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). At least the freewheel diodes  2   b  or the bootstrap diodes  3  are diode elements, such as Schottky barrier diodes (SBDs) and PN junction diodes (PNDs). 
     In addition to the above-mentioned semiconductor elements, the semiconductor device according to Embodiment 1 includes a plurality of control terminals  6   a,  a plurality of power terminals  6   b,  wires  7 , and a mold member  9 . 
     The control terminals  6   a  are illustrated on a left side of  FIGS.  1  and  2   , and the power terminals  6   b  are illustrated on a right side of  FIGS.  1  and  2   . In an example of  FIGS.  1  and  2   , the control terminals  6   a  and the power terminals  6   b  are lead frames electrically connected to the semiconductor elements. The ICs  1  and the bootstrap diodes  3  are bonded to upper surfaces of any of the plurality of control terminals  6   a,  and the power chips  2   a  and the freewheel diodes  2   b  are bonded to upper surfaces of any of the plurality of power terminals  6   b.    
     The wires  7  selectively connect the ICs  1 , the power chips  2   a,  the freewheel diodes  2   b,  the bootstrap diodes  3 , the control terminals  6   a,  and the power terminals  6   b.  An electrical circuit is formed by the connection. A material for the wires  7  includes gold, copper, and aluminum, for example. 
     The mold member  9  shown by dotted lines in  FIGS.  1  and  2    covers the semiconductor elements, a portion of the control terminals  6   a,  a portion of the power terminals  6   b,  and the wires  7 . The mold member  9  is a transfer mold member formed of an insulating member, such as resin. The mold member  9  is rectangular in plan view, and the plurality of control terminals  6   a  protrude from one side of the mold member  9  and the plurality of power terminals  6   b  protrude from another side opposite the one side of the mold member  9 . 
       FIG.  3    is a side view illustrating an outer shape of the semiconductor device according to Embodiment 1. Control terminals  6   a  are illustrated on an upper side of  FIG.  3   , and a power terminal  6   b  is illustrated on a lower side of  FIG.  3   . The plurality of control terminals  6   a  protrude from the same location along the thickness (a side to side direction in  FIG.  3   ) of the mold member  9 , and the plurality of power terminals  6   b  protrude from the same location along the thickness of the mold member  9 . Portions of the control terminals  6   a  and the power terminals  6   b  not covered with the mold member  9  are illustrated to extend in an in-plane direction in  FIG.  2    for the sake of convenience, but are accurately bent as illustrated in  FIG.  3   . 
       FIG.  4    is a plan view illustrating the control terminals  6   a  before being bent. The plurality of control tell finals  6   a  include inner control terminals  6   a   1  as first terminals and outer control terminals  6   a   2  as second terminals. The inner control terminals  6   a   1  and the outer control terminals  6   a   2  alternate along the one side of the mold member  9 , and a pair of an inner control terminal  6   a   1  and an outer control terminal  6   a   2  is illustrated in  FIG.  4   . 
     The inner control terminals  6   a   1  include inner bends  6   a   6  as first bends. The outer control terminals  6   a   2  include outer bends  6   a   7  as second bends and wide portions  6   a   8  as portions of the outer control terminals  6   a   2 . In an example of  FIGS.  3  and  4   , the inner control terminals  6   a   1  are each bent at a single inner bend  6   a   6 , and the outer control terminals  6   a   2  are each bent at a single outer bend  6   a   7 . 
     The outer bend  6   a   7  is located further from the one side of the mold member  9  than the inner bend  6   a   6 . That is to say, the distance between the one side of the mold member  9  and the outer bend  6   a   7  is greater than the distance between the one side of the mold member  9  and the inner bend  6   a   6 . The inner control terminals  6   a   1  and the outer control terminals  6   a   2  alternate along the one side of the mold member  9 , so that the inner bends  6   a   6  and the outer bends  6   a   7  are staggered along the one side of the mold member  9 . 
     A tie bar  6   c  in  FIG.  4    includes a portion of the inner control terminal  6   a   1  and a portion of the outer control terminal  6   a   2 .  FIG.  5    is a plan view illustrating the semiconductor device before the inner control terminals  6   a   1  and the outer control terminals  6   a   2  are bent in a process of manufacturing the semiconductor device. In  FIG.  5   , the shapes of the inner control terminals  6   a   1  and the outer control terminals  6   a   2  are simplified. As illustrated in  FIG.  5   , the inner control terminals  6   a   1  and the outer control terminals  6   a   2  are substantially connected by the tie bar  6   c.    
     Portions of the tie bar  6   c  shown in alternate long and two short dashes lines in  FIG.  4    are removed by cutting, such as pressing. Portions of the tie bar  6   c  remaining after cutting correspond to the inner bends  6   a   6  of the inner control terminals  6   a   1  and the wide portions  6   a   8  of the outer control terminals  6   a   2 . The wide portions  6   a   8  are located between the one side of the mold member  9  and the outer bends  6   a   7  of the outer control terminals  6   a   2 . 
     As illustrated in  FIG.  4   , the inner bends  6   a   6  and the outer bends  6   a   7  have the same width in plan view. This means that a difference in width between the inner bends  6   a   6  and the outer bends  6   a   7  is, for example, 2% or less of the width of the inner bends  6   a   6  or the outer bends  6   a   7  herein. A portion of each of the inner control terminals  6   a   1  exposed from the mold member  9  is widest at the inner bend  6   a   6 . A portion of each of the outer control terminals  6   a   2  exposed from the mold member  9  is widest at the wide portion  6   a   8 , and is narrowest at a distal end portion (an upper portion in  FIG.  4   ). In Embodiment 1 as described above, the wide portion  6   a   8  is wider not only than the outer bend  6   a   7  but also than the inner bend  6   a   6 , which is separated from the one side of the mold member  9  by the distance between the one side of the mold member  9  and the wide portion  6   a   8 . 
       FIG.  6    is a flowchart showing a method of manufacturing the semiconductor device according to Embodiment 1. First, in a power chip die bonding process in step S 1 , the power chips  2   a  are bonded to lead frames using bonding members, such as solder. In a diode die bonding process in step S 2 , the freewheel diodes  2   b  and the bootstrap diodes  3  are bonded to lead frames using bonding members, such as solder. In an IC die bonding process in step S 3 , the ICs  1  are bonded to a lead frame using bonding members, such as solder. The processes in steps S 1  to S 3  may be performed in parallel, or may be performed in a different order. 
     In a wire bonding process in step S 4 , the lead frames, the ICs  1 , the power chips  2   a,  the freewheel diodes  2   b,  and the bootstrap diodes  3  are selectively connected by the wires  7  to form the electrical circuit. A state after completion of the wire bonding process substantially corresponds to a state in  FIG.  1   . 
     In a transfer molding process in step S 5 , a portion of the lead frames, the power chips  2   a,  the freewheel diodes  2   b,  the bootstrap diodes  3 , the ICs  1 , and the wires  7  are sealed with the mold member  9  to be insulated from the outside. A state after completion of the transfer molding process substantially corresponds to a state in  FIG.  5   . 
     In a tie bar cutting process in step S 6 , the portions in the alternate long and two short dashes lines in  FIG.  4    are cut to be removed. In a lead cutting process in step S 7 , distal ends of the lead frames are formed by cutting, such as pressing, to form the inner control terminals  6   a   1  and the outer control terminals  6   a   2  before being bent. 
     In a lead forming process in step S 8 , the inner control terminals  6   a   1  are bent at the inner bends  6   a   6 , and the outer control terminals  6   a   2  are bent at the outer bends  6   a   7 . The semiconductor device according to Embodiment 1 as illustrated in  FIG.  3    is manufactured by the above-mentioned processes. 
     Summary of Embodiment 1 
     In the semiconductor device according to Embodiment 1, the inner bends  6   a   6  and the outer bends  6   a   7  have the same width in plan view. A variation between an angle at which the inner control terminals  6   a   1  are bent at the inner bends  6   a   6  and an angle at which the outer control terminals  6   a   2  are bent at the outer bends  6   a   7  can thus be reduced even when the inner control terminals  6   a   1  and the outer control terminals  6   a   2  are bent with the same force. 
     In Embodiment 1, the wide portions  6   a   8  wider than the outer bends  6   a   7  are located between the one side of the mold member  9  and the outer bends  6   a   7  of the outer control terminals  6   a   2 . According to such a configuration, deformation, by external force, of portions of the outer control terminals  6   a   2 , which are more likely to be interfered with the outside than the inner control terminals  6   a   1 , between the one side of the mold member  9  and the outer bends  6   a   7  can be suppressed. 
     In Embodiment 1, the semiconductor elements include the bootstrap diodes  3  covered with the mold member  9 . According to such a configuration, a customer and the like are not required to externally attach the bootstrap diodes  3  to the mold member  9 , so that an apparatus to which the semiconductor device is attached can be reduced in size. 
     &lt;Modification 1&gt; 
     While the plurality of control terminals  6   a  include the staggered bends in Embodiment 1, the power terminals  6   b  may include staggered bends. The power terminals  6   b  may include inner power terminals similar to the inner control terminals  6   a   1  and outer power terminals similar to the outer control terminals  6   a   2 . That is to say, bends of the inner power terminals and bends of the outer power terminals may have the same width, and wide portions may be located between one side of the mold member  9  and the bends of the outer power terminals. 
     While the control terminals  6   a  and the power terminals  6   b  are located on two respective sides of the mold member  9  in Embodiment 1, the control terminals  6   a  and the power terminals  6   b  may be located on the same side of the mold member  9 . In this configuration, the bends of the control terminals  6   a  and the power terminals  6   b  may be staggered without any distinction between the control terminals  6   a  and the power terminals  6   b.  The bends may have the same width in this configuration. Modification 1 may be applied to Embodiment 2, which will be described below. 
     &lt;Modification 2&gt; 
     While the semiconductor elements, such as the ICs  1 , the power chips  2   a,  and the freewheel diodes  2   b,  are mounted on the lead frames in Embodiment 1, the configuration in the mold member  9  may be changed as appropriate. For example, the semiconductor device may include metal layers  11  and an insulating layer  12  as illustrated in  FIG.  7   . The metal layers  11  may electrically be connected to the control terminals  6   a  or the power terminals  6   b  by ultrasonic bonding, soldering, or the like, and the ICs  1 , the power chips  2   a,  and the like may be mounted on the metal layers  11 . The insulating layer  12  may be bonded to surfaces of the metal layers  11  opposite surfaces on which the semiconductor elements are mounted. The metal layers  11  and the insulating layer  12  may constitute an insulating substrate. Modification 2 may be applied to Embodiment 2, which will be described below. 
     &lt;Modification 3&gt; 
     While the semiconductor elements include the power chips  2   a  and the freewheel diodes  2   b  provided separately from each other in Embodiment 1, the semiconductor elements are not limited to such semiconductor elements. For example, the semiconductor elements may include elements each including a single semiconductor substrate having an IGBT region and a diode region, such as reverse conducting-IGBTs (RC-IGBTs). In a configuration in which the semiconductor elements include the RC-IGBTs, the semiconductor elements can be reduced in size compared with a configuration in which the semiconductor elements include the power chips  2   a  and the freewheel diodes  2   b,  so that the semiconductor device can be reduced in size. 
     A material for the semiconductor elements may include a wide bandgap semiconductor having a wider bandgap than silicon (Si). The wide bandgap semiconductor may include silicon carbide (SiC), gallium nitride (GaN), and diamond, for example. In a configuration in which the material for the semiconductor elements includes the wide bandgap semiconductor, lower energy losses or faster switching speeds of the semiconductor device can be achieved. 
     While the semiconductor elements include the first semiconductor elements and the second semiconductor elements in Embodiment 1, the semiconductor elements may include only the first semiconductor elements or only the second semiconductor elements. Modification 3 may be applied to Embodiment 2, which will be described below. 
     Embodiment 2 
       FIG.  8    is a plan view illustrating a portion of a semiconductor device according to Embodiment 2, and is specifically a plan view illustrating the control terminals  6   a  before being bent. In Embodiment 2, the outer control terminals  6   a   2  each include the outer bend  6   a   7  as the second bend, the wide portion  6   a   8 , and a constricted portion  6   a   9 . The other configuration in Embodiment 2 is similar to that in Embodiment 1. 
     The wide portion  6   a   8  formed by tie bar cutting is located between the one side of the mold member  9  and the outer bend  6   a   7  of the outer control terminal  6   a   2  as in Embodiment 1. In Embodiment 2, the wide portion  6   a   8  may be wider than the outer bend  6   a   7 , or may have the same width as or may be narrower than the outer bend  6   a   7  in plan view. 
     The constricted portion  6   a   9  is also referred to as a neck portion, and is located between the outer bend  6   a   7  and the wide portion  6   a   8 . That is to say, the constricted portion  6   a   9  is narrower than each of the outer bend  6   a   7  and the wide portion  6   a   8  in plan view. 
     Summary of Embodiment 2 
     In the semiconductor device according to Embodiment 2 as described above, a distance A between the inner bend  6   a   6  and the wide portion  6   a   8  can be increased due to the presence of the constricted portion  6   a   9 . This can increase a tie bar cutting area, that is, a punching area to reduce wear of a punching die. The tie bar cutting area can be increased to increase the distance A as an insulating distance between the inner control terminal  6   a   1  and the outer control terminal  6   a   2 , so that insulation can be improved, or the semiconductor device can be reduced in size by bringing the terminals closer to each other. The distance A can be further increased when the wide portion  6   a   8  is narrower than the outer bend  6   a   7  in plan view. 
     Embodiments and modifications can freely be combined with each other, and can be modified or omitted as appropriate. 
     While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.