Patent Publication Number: US-2020294896-A1

Title: Lead Frame Stabilizer for Improved Lead Planarity

Description:
BACKGROUND 
     Semiconductor dies are commonly packaged with a lead frame in a molded semiconductor package. According to this technique, a lead frame structure is provided with a central die paddle and several elongated leads that extend towards the die paddle. The leads and the die paddle are typically physically supported by a peripheral ring-like structure. One or more semiconductor dies are mounted on the die paddle and electrically connected to the individual leads of the lead frame, e.g., using conductive bond wires, metal clips, etc. An electrically insulating mold compound, e.g., plastic, ceramic, etc., is formed around the semiconductor die and associated electrical connections. As a result, an insulative mold body is provided. The mold body protects the semiconductor die and electrical connections from damaging environmental conditions, such as moisture, foreign particles, etc. After the mold body is formed, the leads and the die paddle are detached from the peripheral ring, e.g., by mechanical cutting. Exposed outer ends of the leads provide externally accessible terminals for the package device that are configured to interface with another device, such as a printed circuit board. 
     Molded semiconductor packages can be configured according to a variety of different standardized package types. These package types differ in some structural aspect, e.g., lead configuration, mold configuration, etc. One example of a specific package type is a so-called flat no-lead package. This package type is characterized by leads that are coplanar with the molded encapsulant material at the bottom side of the package. This configuration provides so-called surface mount capability wherein the package can be directly placed on and simultaneously electrically connected with a printed circuit board. 
     One problem that arises in the fabrication of flat no-lead packages is the issue of mold flashing. Mold flashing refers to unwanted portions of the mold compound that partially cover the leads after the molding process is complete. This mold compound can be difficult or impossible to remove by conventional cleaning techniques. Mold flashing can determinately impact yield, as the leads may be ineffective as electrical terminals if sufficiently covered by mold compound. 
     SUMMARY 
     A packaged semiconductor device is disclosed. According to an embodiment, the packaged semiconductor device includes a die paddle, a semiconductor die mounted on the die paddle, a plurality of fused leads extending away from a first side of the die paddle, a discrete lead that extends away from the first side of the die paddle and is physically detached from the plurality of fused leads, a first electrical connection between a first terminal of the semiconductor die and the discrete lead, an encapsulation material that encapsulates the semiconductor die, and a stabilizer bar connected to a first outer edge side of the discrete lead. The first outer edge side of the discrete lead is opposite from a second outer edge side of the discrete lead which faces the plurality of fused leads. 
     A lead frame is disclosed. According to an embodiment, the lead frame includes a die paddle, a semiconductor die mounted on the die paddle, a plurality of fused leads extending away from a first side of the die paddle, a discrete lead that extends away from the first side of the die paddle and is physically detached from the plurality of fused leads, a first electrical connection between a first terminal of the semiconductor die and the discrete lead, an encapsulation material that encapsulates the semiconductor die, and a stabilizer bar connected to a first outer edge side of the discrete lead. The first outer edge side of the discrete lead is opposite from a second outer edge side of the discrete lead which faces the plurality of fused leads. 
     A method of manufacturing a lead frame is disclosed. According to an embodiment, the method includes providing a planar sheet metal, and structuring the planar sheet metal to include a peripheral structure, a die paddle connected to the peripheral structure and comprising a first edge side that faces and is spaced apart from a first edge side of the peripheral structure, a plurality of fused leads that are each connected to the first edge side of the peripheral structure and are each fused together by a fuse connector at a location that is between the first edge side of the peripheral structure and the die paddle, a discrete lead that is connected to the first edge side of the peripheral structure, and is separated from the fuse connector, and a stabilizer bar that is connected between the peripheral structure and an outer edge side of the discrete lead. 
     Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. The features of the various illustrated embodiments can be combined unless they exclude each other. Embodiments are depicted in the drawings and are detailed in the description which follows. 
         FIG. 1  illustrates a lead frame with a stabilizer bar, according to an embodiment. 
         FIG. 2  illustrates a lead frame with a stabilizer bar, according to another embodiment. 
         FIG. 3 , which includes  FIGS. 3A and 3B , illustrates cross-sectional views of specific regions of a lead frame with a stabilizer bar, according to an embodiment. 
         FIG. 4  illustrates forming a packaged semiconductor device on a lead frame with a stabilizer bar, according to another embodiment. 
         FIG. 5 , which includes  FIGS. 5A and 5B , illustrates a packaged semiconductor device formed from a lead frame with a stabilizer bar, according to an embodiment.  FIG. 5A  shows a lower side of the packaged semiconductor device from a plan-view perspective.  FIG. 5B  illustrates a side view of the packaged semiconductor device. 
         FIG. 6  illustrates the influence of a stabilizer bar on the movement of a discrete lead, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to embodiments described herein, a lead frame is provided to include a stabilizer bar that advantageously mitigates the problem of mold flashing and improves wire bond capability. In more derail, a lead frame includes a die paddle, a peripheral structure, a plurality of fused leads, and a discrete lead. The discrete lead is independent from the fused leads and, in the absence of further measures, would be prone to tilting and/or flexing during various steps for processing and handling of the lead frame. Advantageously, the lead frame additionally includes a stabilizer bar that mitigates this tilting and/or flexing of the discrete lead. The stabilizer bar is connected between an outer edge side of the discrete lead and the peripheral structure. This connection anchors the discrete lead at a second location before and during the encapsulation process. Consequently, the lower surface of the discrete lead is more closely aligned with the lower surface of the die paddle and the fused leads at the lower side of the completed packaged device. This mitigates so-called mold flashing wherein liquified mold compound accumulates on the discrete lead as a result of the non-planarity of the discrete lead. Additionally, this improves wire bond capability by providing a more stable surface that is less prone to movement (e.g., from bouncing of the discrete lead) during the wire bond process. 
     Referring to  FIG. 1 , a lead frame  100  that is used to form a packaged semiconductor device is depicted, according to an embodiment. The lead frame  100  is provided from a lead frame strip  102  that includes a plurality of identically configured unit lead frames  100 , two of which are depicted in  FIG. 1 . 
     The lead frame  100  includes a peripheral structure  104 . The peripheral structure  104  is an outside portion of the lead frame  100  that does not form part of the completed package device. Instead, the peripheral structure  104  is used mechanically support the features of the lead frame  100  during processing. In the depicted embodiment, the peripheral structure  104  forms a loop around a centrally located die paddle  106 . In the depicted embodiment, the peripheral structure  104  includes first, second, third, and fourth edge sides  108 ,  110 ,  112 , and  114  that surround a central opening  116 . These edge sides  108 ,  110 ,  112 , and  114  form an angled intersection with one another. That is, these edge sides  108 ,  110 ,  112 , and  114  form oblique angles with one another. In the depicted embodiment, each of the first, second, third, and fourth edge sides  108 ,  110 ,  112 , and  114  form ninety-degree angles with one another such that the central opening  116  has a general shape of a rectangle. More generally, the peripheral structure  104  can be configured in a variety of different geometries, and the inner edge sides of the peripheral structure  104  can include non-perpendicular angles and/or curved geometries. 
     The lead frame  100  includes a die paddle  106  that is disposed within the central opening  116  of the peripheral structure  104 . As depicted, the die paddle  106  has a generally rectangular shape, with first, second, third and fourth edge sides  118 ,  120 ,  122 , and  124  that respectively face the first, second, third and fourth edge sides  108 ,  110 ,  112 , and  114  of the peripheral structure  104 . More generally, the die paddle  106  can have a variety of geometries. The die paddle  106  is physically connected to the peripheral structure  104  and hence mechanically supported by the peripheral structure  104 . In the depicted embodiment, this physical connection is provided by a number of tie bars  126  extending between the third edge side  122  of the die paddle  106  and the third edge side  112  of the peripheral structure  104 . Additionally, or alternatively, one or more leads (not shown) may be connected between the die paddle  106  and the peripheral structure  104 . 
     The lead frame  100  includes several leads that face the first edge side  118  of the die paddle  106 . Each of these leads are connected to the first edge side  108  of the peripheral structure  104 . In more detail, each of these leads include opposite facing outer edge sides that intersect and merge with the peripheral structure  104  at the first edge side  108  of the peripheral structure  104 . This location of the leads will be referred to as the distal end of the leads in the following description. Each of these leads include ends opposite from the distal ends that face the first edge side of the die pad. This location of the leads will be referred to as the proximal ends of the leads in the following description. According to an embodiment, the proximal end of each lead is spaced apart from the first edge side  118  of the die paddle  106 . Alternatively, one or more leads may extend completely from the first edge side  108  of the peripheral structure  104  to the first edge side  118  of the die paddle  106 . 
     Included in the leads that face the first edge side  118  of the die paddle  106  is a plurality (i.e., two or more) of fused leads  126 . The fused leads  126  are fused together by a fuse connector  128 . The fuse connector  128  is disposed at a location that is between the first edge side  108  of the peripheral structure  104  and the first edge side  118  of die paddle  106 . This means that the fuse connector  128  is closer to the first edge side  118  of the die paddle  106  than the distal ends of the fused leads  126 . The fuse connector  128  can be provided from a continuous metal pad that includes an inner edge side  130  and an outer edge side  132 . The inner edge side  130  of the fuse connector  128  extends transversely across outer edge sides of the fused leads  126 . The outer edge side  132  of the fuse connector  128  faces and is spaced apart from the die paddle  106 . In the depicted embodiment, the outer edge side  132  of the fuse connector  128  is coextensive with the proximal ends of the fused leads  126 . In other embodiments, the outer edge side  132  can be located between the distal and proximal ends of the fused leads  126  such that the fused leads  126  regain the shape of individual leads as they approach the first edge side  118  of the die paddle  106 . 
     Also included in the leads that face the first edge side  118  of the die paddle  106  is a discrete lead  134 . The discrete lead  134  is separated from the fuse connector  128 . This means that the outer edge sides of the discrete lead  134  do not contact the fuse connector  128 . Put another way the discrete lead  134  is separate and independent from the fused leads  126  except for the connections to the peripheral structure  104 , which are eventually severed in the completed device. 
     The discrete lead  134  includes first and second opposite facing outer edge sides  136 ,  138  that each connect to the first edge side  108  of the peripheral structure  104 . The first outer edge side  136  of the discrete lead  134  faces the second edge side  110  of the peripheral structure  104 . The second outer edge side  138  of the discrete lead  134  faces the plurality of fused leads  126 . According to an embodiment, the discrete lead  134  is an outermost lead of all of the leads that are connected to the first edge side  108  of the peripheral structure  104 . This means that no other leads are disposed between the discrete lead  134  and the peripheral structure  104  in a lateral direction of the leads, i.e., a direction that is perpendicular to the outer edge sides of the leads. 
     According to an embodiment, a gap  140  that spans a complete length of the discrete lead  134  is provided between the second outer edge side  138  of the discrete lead  134  and the plurality of fused leads  126 . In this context, the complete length of the discrete lead  134  refers to a length of the discrete lead  134  from the distal end to the proximal end of the discrete lead  134 . In this embodiment, the second outer edge side  138  of the discrete lead  134  directly faces an edge side of one of the leads from the plurality of fused leads  126 . In other embodiments (not shown) additional elements, such as additional discrete leads, may be disposed between the discrete lead  134  and the fused leads  126 . In any case, the second outer edge side  138  of the discrete lead  134  is physically spaced apart from the fused leads  126  due to the gap  140 . Moreover, because of the gap  140 , the discrete lead  134  forms a separate electrical node as the fused leads  126  in the completed device. 
     The lead frame  100  additionally includes a first stabilizer bar  142 . The first stabilizer bar  142  is connected between the peripheral structure  104  and an outer edge side of the discrete lead  134 . According to an embodiment, the first stabilizer bar  142  extends transversely away from one of the outer edge sides of the discrete lead  134 . This means that the first stabilizer bar  142  forms an angled intersection with an outer edge side of the discrete lead  134 . For example, as shown, the first stabilizer bar  142  may include opposite facing outer edge sides that join and form a substantially perpendicular angle with the first outer edge side  136  of the discrete lead  134 . More generally, the first stabilizer bar  142  can be disposed at any oblique angle relative to an edge side of the discrete lead  134 . According to an embodiment, first stabilizer bar  142  is disposed on a side of the discrete lead  134  that does not face any leads. For example, in the depicted embodiment wherein the discrete lead  134  is an outermost lead, the first stabilizer bar  142  is provided in a region of the opening  116  that is between the first outer edge side  136  of the discrete lead  134  and the second outer edge side  110  of the peripheral structure  104 . In this example, the first stabilizer bar  142  extends directly between the second edge side  110  of the peripheral structure  104  and the first edge side of the discrete lead  134 . As previously explained, the geometry of the peripheral structure  104  may vary from what is shown in different lead frame  100  configurations. In any case, the geometry of the first stabilizer bar  142  can be adapted so that the first stabilizer bar  142  proves a direct connection between an outer edge side of the discrete lead  134  and an edge side of the peripheral structure  104 . For example, the first stabilizer bar  142  can include angled or curved geometries to complete this direct connection. 
     As a result of the first stabilizer bar  142 , the discrete lead  134  is physically coupled to the peripheral structure  104  at two locations. Specifically, the first stabilizer bar  142  connects directly to the peripheral structure  104  at a first location  144 . The first location  144  is the intersection between the first and second outer edge  136 ,  138  sides of the discrete lead  134  and the first edge side  108  of the peripheral structure  104 , i.e., the distal end of the discrete lead  134 . Additionally, the discrete lead  134  is physically coupled to the peripheral structure  104  at a second location  146 . The second location  146  is at an intersection between edge sides of the first stabilizer bar  142  and an outer edge side of the discrete lead  134 . The second location  146  is closer to the die paddle  106  than the first location  144 . This means that the connection between the first stabilizer bar  142  and the discrete lead  134  is closer to the proximal end of the discrete lead  134  than the first location  144 . In the depicted embodiment, the second location  146  is about halfway between the distal and proximal ends of the discrete lead  134 . More generally, the second location  146  can be disposed at any location that is spaced apart from the distal end of the discrete lead  134 , including a location that is at or near the proximal end of the discrete lead  134 . 
     According to an embodiment, the lead frame  100  includes a second stabilizer bar  143  connected between the peripheral structure  104  and an outer edge side of the discrete lead  134 . The second stabilizer bar  143  may be configured in a substantially similar or identical manner as the first stabilizer bar  142  according to any of the embodiments of the first stabilizer bar  142  described herein. As shown, the second stabilizer bar  143  connects to the first outer edge side  136  of the discrete lead  134  at a third location  148  that is closer to the die paddle  106  than the first and second locations  144 ,  146 . Moreover, the second stabilizer bar  143  comprises outer edge sides that are substantially parallel to the outer edge sides of the first stabilizer bar  142  and perpendicular to the first outer edge side  136  of the discrete lead  134 . More generally, the second stabilizer bar  143  can be oriented at any angle relative to the discrete lead  134  and edge sides of the peripheral structure  104  in a similar manner as previously described with reference to the first stabilizer bar  142 . 
     Referring to  FIG. 2 , a lead frame  100  that is used to form a packaged semiconductor device is depicted, according to another embodiment. The lead frame  100  of  FIG. 2  is substantially identical to the lead frame  100  of  FIG. 1 , with the exception that this lead frame  100  additionally includes a second discrete lead  135  and a third stabilizer bar  145  connected between the second discrete lead  135  and the peripheral structure  104 . In this configuration, the second discrete lead  135  is an outermost lead that is provided at the opposite lateral end of the plurality as the first discrete lead  134 . An inner edge side of the second discrete lead  135  is spaced apart from the fused leads  126  by a second gap  147  that spans the length of the second discrete lead  135  in a similar manner as previously discussed. The third stabilizer bar  145  is connected between the outer edge side of the second discrete lead  135  and the third edge side  144  of the peripheral structure  104 . The third stabilizer bar  145  may be configured in a substantially similar or identical manner as the first stabilizer bar  142  according to any of the embodiments of the first stabilizer bar  142  described herein. 
     Referring to  FIG. 3 , various cross-sectional views of the lead frame  100  are shown.  FIG. 3A  depicts a view of the lead frame  100  along a cross-section that includes the peripheral structure  104 , the first stabilizer bar  142  and the discrete lead  134 .  FIG. 3B  depicts a view of the lead frame  100  along a cross-section that includes a proximal end of the first stabilizer bar  142  and the die paddle  106 . 
     As shown in  FIG. 3A , the first stabilizer bar  142  can be configured as a reduced thickness portion of the lead frame  100 . That is, the first stabilizer bar  142  can be relatively thinner in comparison to other portions of the lead frame  100 , e.g., the discrete lead  134 , the die paddle  106 , etc. In this context, the thickness of the lead frame  100  refers to the shortest distance measured between opposite facing upper and lower surfaces  148 ,  150  of the lead frame  100 . In the example of  FIG. 3A , the reduced thickness of the lead frame  100  is provided by a vertical offset of the lower surface  150  of the lead frame  100  in the region of the first stabilizer bar  142 . Meanwhile, the upper surface  148  of the lead frame  100  at the first stabilizer bar  142  is substantially coplanar with the upper surface  148  of the lead frame  100  at the discrete lead  134 . Thus, the reduction in thickness is provided exclusively at one side of the lead frame  100 . As shown in  FIG. 3B , the upper and lower surfaces  148 ,  150  of the lead frame  100  at the discrete lead  134  are substantially coplanar with the upper and lower surfaces  148 ,  150  of the lead frame  100  in the die paddle  106 . Hence, the above described vertical offset of the lower surface  150  at the first stabilizer bar  142  means that a bottom side of the first stabilizer bar  142  is offset from bottom sides of the leads and the die paddle  106 . 
     The lead frame  100  as described herein can be formed by the following technique. Initially, a sheet layer of electrically conductive material (e.g., copper, aluminum, alloys thereof, etc., is provided). Subsequently, openings are formed in the sheet layer which define the edge sides of the various geometric features, e.g., the leads, the die paddle  106 , the first stabilizer bar  14 , etc. These openings can be formed according to a variety of different techniques, such as etching, stamping, punching, etc. In addition, or in the alternative, structures can be attached to the lead frame  100  using techniques such as soldering, riveting, etc., to provide at least some of the various geometric features of the lead frame  100  described herein. 
     According to an embodiment, the reduced thickness geometry of the first stabilizer bar  142  as described with reference to  FIG. 3A  is formed using a half-etch technique. Half-etching refers to a technique whereby the etching is controlled, e.g., through appropriate use of mask geometry, time, etchant chemical, etc., to prevent the etchant from completely penetrating the material. In one example of this technique, two masks are provided on both sides of a planar sheet metal. These masks are patterned as mirror images of one another, except that the half-etched features are only structured on one side of the two masks. The etching process is carried to remove about half of the thickness of the sheet metal such that complete openings form in the regions exposed by both masks, and half depth recesses form in the regions that are only exposed by one mask, i.e., the half-etched regions. 
     Referring to  FIG. 4 , the lead frame  100  as described with reference to  FIG. 1  can be used to form a packaged semiconductor device  200  (shown in  FIG. 5 ) according to the following technique. Once the lead frame  100  is provided, the lead frame  100  can placed on a temporary carrier (not shown) that is suitable for handling and transfer of electronic components through various semiconductor processing tools. A semiconductor die  152  is mounted on the upper surface  148  of the lead frame  100  at the die paddle  106 . This can be done by providing an adhesive, e.g., solder, sinter, tape, etc., between the lower side of the semiconductor die  152  and the die paddle  106 . Subsequently, electrical connections are provided between the terminals of the semiconductor die  152  and the various leads of the lead frame  100 . Generally speaking, these electrical connections can be provided according to any conventionally known technique, such as bond wires, clips, ribbon, etc. In the depicted embodiment, the semiconductor die  152  includes a first terminal  154  that is electrically connected to the discrete lead  134  by a single bond wire  156 , and a second terminal  158  that is electrically connected to the fused leads  126  by a plurality of bond wires  160 . 
     According to an embodiment, the semiconductor die  152  is configured as a power device, i.e., a device that is configured to block large voltages, e.g., 200 volts or more, and/or accommodate large currents, e.g., 1 ampere or more. For example, the semiconductor die  152  can be configured as a power transistor, such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistors) or Insulated Gate Bipolar Transistor (IGBT) wherein the first terminal  154  is a gate terminal and the second terminal  158  is a drain terminal of the device. In that case, the source terminal can be provided on the lower side of the semiconductor die  152 , and the die paddle  106  provides a corresponding source connection for the semiconductor die  152 . 
     More generally, the semiconductor die  152  can have any of a wide variety of device configurations. These device configurations include discrete devices such as HENT (high electron mobility transistor) devices, diodes, thyristors, etc. These device configurations also include integrated devices such as, controllers, amplifiers, etc. These device configurations include vertical device configurations, i.e., devices which conduct in a direction perpendicular to the upper and lower surfaces of the die, and lateral device configurations, i.e., devices which conduct in a direction parallel to the upper and lower surfaces of the die. In any case, the discrete lead  134  and the fused leads  126  can be separately electrically connected to different terminals of the semiconductor die  152 . Without necessarily being limited thereto, the fused leads  126  are generally preferable for large current carrying terminals, e.g., source, drain, etc. By contrast, the discrete leads  134  are generally preferable for smaller current carrying terminals, e.g., gate, sensor, etc. 
     After electrically connecting the semiconductor die  152  to the lead frame  100 , the semiconductor die  152  is encapsulated with an electrically insulating mold compound  162 . The mold compound  162  is shown as translucent in  FIG. 4  so that the encapsulated components are visible in the figure. However, in practice, this material is typically opaque. The mold compound  162  can include a wide variety of electrically insulating materials such as ceramics, epoxy materials and thermosetting plastics, to name a few. The mold compound  162  can be formed using any of a variety of known techniques, such as injection molding, transfer molding, compression molding, etc. The mold compound  162  is formed to completely encapsulate, i.e., cover and surround, the semiconductor die  152  and associated electrical connections, which in the depicted embodiment are provided by the bond wires  156  and  160 . In an embodiment, the mold compound  162  can be formed to expose the distal ends of each of the leads, e.g., as shown. After the mold compound  162  is formed and hardened, each of the leads can be separated from the peripheral structure  104 , e.g., by a mechanical cutting process. 
     Referring to  FIG. 5 , a completed packaged semiconductor device  200  is shown after separation from the peripheral structure  104  of the lead frame  100 , according to an embodiment. As shown in  FIG. 5A , the lower surface  150  of the lead frame  100  in the die paddle  106  and lead regions is exposed at the bottom side of the packaged device. According to an embodiment, the exposed portions of the lower surface  150  of the lead frame  100  are coplanar with the lower surface of the mold compound  162 . As a result, the die paddle  106  and leads provide so-called surface mount capability that allow the packaged semiconductor device  200  to interface with a corresponding device, e.g., a PCB socket. Various planarization and or cleaning techniques can be performed so that the metal portions of the lead frame  100  are clearly exposed from the mold compound  162  and provide a clean surface connection. 
     As shown in  FIG. 5B , the first and second stabilizer bars  142  and  143  extend to an outer side surface of the mold compound  162  body. In the depicted embodiment, ends of the first and second stabilizer bars  142  and  143  are exposed from the mold compound  162 . In general, these ends can be disregarded as functional features, as the discrete lead  134  provides electrical access to the same terminal. However, if desired, an additional molding step can be performed to cover the exposed ends of the first and second stabilizer bars  142  and  143 . 
     As can be seen, the first and second stabilizer bars  142  and  143  are covered on both sides by the mold compound  162 . This configuration can be made possible by forming the stabilizer bars  142  and  143  with the reduced thickness geometry as described with reference to  FIG. 3A . By vertically offsetting the lower surface  150  of the lead frame  100  as previously described, the encapsulation process completely covers the lower surface  150  of the lead frame  100  at the first and second stabilizer bars  142  and  143  with the mold compound  162 . Hence, as shown in  FIG. 5A , the first and second stabilizer bars  142  and  143  are not exposed at the lower side of the packaged device. Thus, the first and second stabilizer bars  142  and  143  do not alter the surface mount footprint of the device. 
     Referring to  FIG. 6 , potential range of movement  164  for a hypothetical discrete lead  165  that is not connected to the peripheral structure  104  is shown. This range of movement  164  illustrates a tilting and/or flexing of the hypothetical discrete lead  165  wherein the hypothetical discrete lead  165  deviates from the plane of the die paddle  106 . This movement can be caused by forces applied to the discrete lead  134  during various processing steps for forming the packaged device. For example, this movement can arise from mechanical forces applied to the lead frame  100  during handling of the lead frame  100 . Alternatively, this movement may arise from compressive or tensile stresses that arise in the packaged device  200  during high temperature processing steps, wherein materials with different coefficients of thermal expansion expand or contract at different rates. As can be seen, the first connection point  144  between the discrete lead  134  and the peripheral structure  104  acts as a fulcrum such that the proximal end of the discrete lead  134  has significant leverage. Thus, significant rotational movement of the discrete lead  134  is possible with low amounts of force. By way of comparison, the fused leads  126  as described herein are less prone to this kind of movement due to the added mechanical strength provided by the fuse connector  128 . Moreover, the fused leads  126  move independently from the discrete lead  134 . Thus, in the absence of an anchor mechanism, the discrete lead  134  can become tilted relative to the fused leads  126  due to the above described phenomena. 
     Because the first and second stabilizer bars  142 ,  143  physically couple the discrete lead  134  to the peripheral structure  104  at the second and third locations  146 ,  148 , there is less leverage at the proximal end of the discrete lead  134 . Hence, the above described mechanical forces applied to the lead frame  100  are less effective at tilting or flexing the discrete lead  134 . Hence, the discrete lead  134  remains aligned at or close to the plane of the die paddle  106  throughout the encapsulating of the semiconductor die  152 . Once the mold compound  162  is hardened, the position of the discrete lead  134  is fixed and the first and second stabilizer bars  142 ,  143  can be detached. 
     Referring again to  FIG. 5 , an area  166  of the packaged device is shown that is susceptible to mold flashing if the discrete lead  134  is permitted to move by the potential range of movement  164  as shown in  FIG. 6 . If the discrete lead  134  is sufficiently tilted relative to the die paddle  106  and/or the fused leads  126 , this area  106  becomes covered with mold compound  162  in the completed device. Hence, the first stabilizer bar  142  advantageously avoids this outcome by preventing the discrete lead  134  from tilting in this way. 
     While  FIG. 6  illustrates an embodiment that includes both the first and second stabilizer bars  142 ,  143 , a beneficial impact on rotational movement and/or reduction in mold flashing as described herein can be achieved with different numbers and or configurations of stabilizers, including embodiments that include only one stabilizer bar connected to a discrete lead. 
     An embodiment of a packaged semiconductor device includes a die paddle, a semiconductor die mounted on the die paddle, a plurality of fused leads extending away from a first side of the die paddle, a discrete lead that extends away from the first side of the die paddle and is physically detached from the plurality of fused leads, a first electrical connection between a first terminal of the semiconductor die and the discrete lead, an encapsulation material that encapsulates the semiconductor die, and a stabilizer bar connected to a first outer edge side of the discrete lead. The first outer edge side of the discrete lead is opposite from a second outer edge side of the discrete lead which faces the plurality of fused leads. 
     According to an embodiment that can be combined with others, the fused leads and the discrete lead extend to a first outer sidewall of the encapsulation material, wherein the stabilizer bar extends to a second outer sidewall of the encapsulation material, and the first and second outer sidewalls of the encapsulation material are angled relative to one another. 
     According to an embodiment that can be combined with others, a gap that spans a complete length of the discrete lead is provided between the second outer edge side of the discrete lead and the plurality of fused leads. 
     According to an embodiment that can be combined with others, a thickness of the stabilizer bar is less than a thickness of the discrete lead. 
     According to an embodiment that can be combined with others, the stabilizer bar comprises an upper surface that is coplanar with an upper surface of the discrete lead and a lower surface that is vertically offset from a lower surface of the discrete lead, and wherein the lower surface of the stabilizer bar is covered by the encapsulation material. 
     According to an embodiment that can be combined with others, the packaged device further includes a second stabilizer bar connected to the first outer edge side of the discrete lead. 
     An embodiment of a method of forming a semiconductor device comprises providing a lead frame that comprises a peripheral structure, a die paddle connected to the peripheral structure and comprising a first edge side that faces and is spaced apart from a first edge side of the peripheral structure, a plurality of fused leads that are each connected to the first edge side of the peripheral structure and are each fused together by a fuse connector at a location that is between the first edge side of the peripheral structure and the die paddle, a discrete lead that is connected to the first edge side of the peripheral structure, and is separated from the fuse connector, and a stabilizer bar that is connected between the peripheral structure and an outer edge side of the discrete lead, mounting a semiconductor die on the die paddle, and encapsulating the semiconductor die with an electrically insulating mold compound while the stabilizer bar connected between the peripheral structure and an outer edge side of the discrete lead. 
     According to an embodiment that can be combined with others, the discrete lead comprises first and second opposite facing outer edge sides that each connect to the first edge side of the peripheral structure at a first location, and wherein the stabilizer bar connects to the first outer edge side of the discrete lead at a second location that is closer to the die paddle than the first location. 
     According to an embodiment that can be combined with others, the discrete lead comprises a proximal end that faces the die paddle, and the second location is between the first location and the proximal end of the discrete lead. 
     According to an embodiment that can be combined with others, the second outer edge side of the discrete lead faces the plurality of fused leads, and a gap that spans a complete length of the discrete lead is provided between the second outer edge side of the discrete lead and the plurality of fused leads. 
     According to an embodiment that can be combined with others, the peripheral structure comprises a second edge side that forms an angled intersection with the first edge side, and the stabilizer bar extends between the second edge side of the peripheral structure and the first outer edge side of the discrete lead. 
     According to an embodiment that can be combined with others, the fuse connector is a continuous metal pad that comprises an inner edge side and an outer edge side, the inner edge side of the fuse connector extends transversely across outer edge sides of the fused leads, and the outer edge side of the fuse connector faces and is spaced apart from the die paddle. 
     According to an embodiment that can be combined with others, the discrete lead is an outermost lead of all leads connected to the first edge side of the peripheral structure, and the stabilizer bar is disposed on a side of the discrete lead that does not face any leads. 
     According to an embodiment that can be combined with others, the lead frame further comprises a second stabilizer bar connected between the peripheral ring and the outer edge side of the discrete lead. 
     According to an embodiment that can be combined with others, the stabilizer bar is a reduced thickness portion of the lead frame. 
     According to an embodiment that can be combined with others, the lead frame comprises opposite facing upper and lower surfaces, the upper surface of the lead frame at the stabilizer bar is substantially coplanar with the upper surface of the lead frame at discrete lead, and the lower surface of the lead frame at the stabilizer bar is vertically offset from the lower surface of the lead frame at discrete lead. 
     According to an embodiment that can be combined with others, encapsulating the semiconductor die comprises completely covering the lower surface of the lead frame at the stabilizer bar. 
     A lead frame includes a die paddle, a semiconductor die mounted on the die paddle, a plurality of fused leads extending away from a first side of the die paddle, a discrete lead that extends away from the first side of the die paddle and is physically detached from the plurality of fused leads, a first electrical connection between a first terminal of the semiconductor die and the discrete lead, an encapsulation material that encapsulates the semiconductor die, and a stabilizer bar connected to a first outer edge side of the discrete lead. The first outer edge side of the discrete lead is opposite from a second outer edge side of the discrete lead which faces the plurality of fused leads. 
     According to an embodiment that can be combined with others, the discrete lead comprises first and second opposite facing outer edge sides that each connect to the first edge side of the peripheral structure at a first location, and the stabilizer bar connects to the first outer edge side of the discrete lead at a second location that is closer to the die paddle than the first location. 
     According to an embodiment that can be combined with others, the discrete lead comprises a proximal end that faces the die paddle, and the second location is between the first location and the proximal end of the discrete lead. 
     According to an embodiment that can be combined with others, the second outer edge side of the discrete lead faces the plurality of fused leads, and a gap that spans a complete length of the discrete lead is provided between the second outer edge side of the discrete lead and the plurality of fused leads. 
     According to an embodiment that can be combined with others, the peripheral structure comprises a second edge side that forms an angled intersection with the first edge side, and the stabilizer bar extends between the second edge side of the peripheral structure and the first outer edge side of the discrete lead. 
     According to an embodiment that can be combined with others, the discrete lead is an outermost lead of all leads connected to the first edge side of the peripheral structure, and the stabilizer bar is disposed on a side of the discrete lead that does not face any leads. 
     According to an embodiment that can be combined with others, the lead frame further comprises a second stabilizer bar connected between the peripheral ring and the outer edge side of the discrete lead. 
     According to an embodiment that can be combined with others, a thickness of the stabilizer bar is less than a thickness of the discrete lead. 
     According to an embodiment that can be combined with others, the lead frame comprises opposite facing upper and lower surfaces, the upper surface of the lead frame at the stabilizer bar is substantially coplanar with the upper surface of the lead frame at discrete lead, and the lower surface of the lead frame at the stabilizer bar is vertically offset from the lower surface of the lead frame at discrete lead. 
     A method of manufacturing a semiconductor device comprises providing a lead frame comprising a die paddle, a peripheral structure, a plurality of fused leads, a discrete lead, and a stabilizer bar that extends away from an outer edge side of the discrete lead, mounting a semiconductor die on the die paddle, electrically connecting a first terminal of the semiconductor die to the discrete lead, electrically connecting a second terminal of the semiconductor die to the fused leads, encapsulating the semiconductor die with an electrically insulating mold compound, and physically coupling the discrete lead to the peripheral structure via the stabilizer bar during the encapsulating of the semiconductor die. 
     According to an embodiment that can be combined with others, a distal end of the discrete lead is physically coupled to the peripheral structure at a first location during the encapsulating of the semiconductor die, and the discrete lead is physically coupled to the peripheral structure via the stabilizer bar at a second location that is spaced apart from the distal end of the discrete lead. 
     According to an embodiment that can be combined with others, the distal end of the discrete lead is physically coupled to the peripheral structure at the first location by a direct connection between opposite facing outer edge sides of the discrete lead and a first edge side of the peripheral structure, and each of the fused leads comprise distal ends that are directly connected to the first edge side of the peripheral structure. 
     According to an embodiment that can be combined with others, the peripheral structure comprises a second edge side that is oriented transversely relative to the first edge side of the peripheral structure, and physically coupling the discrete lead to the peripheral structure via the stabilizer bar comprises coupling the discrete lead to the second edge side of the peripheral structure. 
     A method of forming a lead frame comprises providing a planar sheet metal, and structuring the planar sheet metal to include a peripheral structure, a die paddle connected to the peripheral structure and comprising a first edge side that faces and is spaced apart from a first edge side of the peripheral structure, a plurality of fused leads that are each connected to the first edge side of the peripheral structure and are each fused together by a fuse connector at a location that is between the first edge side of the peripheral structure and the die paddle, a discrete lead that is connected to the first edge side of the peripheral structure, and is separated from the fuse connector, and a stabilizer bar that is connected between the peripheral structure and an outer edge side of the discrete lead. 
     According to an embodiment that can be combined with others, the discrete lead comprises first and second opposite facing outer edge sides that each connect to the first edge side of the peripheral structure at a first location, and wherein the stabilizer bar connects to the first outer edge side of the discrete lead at a second location that is closer to the die paddle than the first location. 
     According to an embodiment that can be combined with others, the second outer edge side of the discrete lead faces the plurality of fused leads, and a gap that spans a complete length of the discrete lead is provided between the second outer edge side of the discrete lead and the plurality of fused leads. 
     According to an embodiment that can be combined with others, structuring the planar sheet metal comprises forming the stabilizer bar to be a reduced thickness portion of the lead frame. 
     According to an embodiment that can be combined with others, forming the stabilizer bar to be a reduced thickness portion of the lead frame comprises performing a half-etch technique. 
     The term “substantially” encompasses absolute conformity with a requirement as well as minor deviation from absolute conformity with the requirement due to manufacturing process variations, assembly, and other factors that may cause a deviation from the ideal. Provided that the deviation is within process tolerances so as to achieve practical conformity and the components described herein are able to function according to the application requirements, the term “substantially” encompasses any of these deviations. 
     Spatially relative terms such as “under,” “below,” “lower,” “over,” “upper” and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first,” “second,” and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description. 
     As used herein, the terms “having,” “containing,” “including,” “comprising” and the like are open-ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a,” “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise. 
     With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Instead, the present invention is limited only by the following claims and their legal equivalents.