Patent Description:
High voltage semiconductor devices such as MOSFETs (metal oxide semiconductor field effect transistors) or IGBTs (insulated gate bipolar transistors) are commonly packaged in a molded semiconductor package that includes a number of through-hole configured leads protruding out of the encapsulant body. Important design considerations for these types of packages include creepage and clearance. Creepage refers to the shortest path between two package leads along the surface of an isolating structure between the two leads, e.g., a sidewall of the encapsulant body. Clearance refers to the shortest path between two package leads in a direct line, e.g., through air. Maintaining high creepage and clearance is particularly important between two package leads that accommodate a large voltage difference, e.g., between the source and drain leads of a high voltage MOSFET device. However, increasing creepage and clearance conflicts with an overall desire to make semiconductor packages as small as possible. Furthermore, some high voltage rated semiconductor devices include additional terminals that are used to finely tune the operation of the device for optimum performance. Examples of these terminals include source sense terminals, gate terminals, temperature sense terminals, etc. These additional terminals require another package lead, thus impacting the maximum possible creepage and clearance between the voltage blocking leads of the device. The <CIT> discloses a semiconductor package and a leadframe, wherein in an outermost lead of a row of leads a width of a central span of the lead is greater than the width of an interior span and the width of an outer span of the lead. Similar semiconductor packages and leadframes are also disclosed in the <CIT> and the <CIT>.

A lead frame is disclosed. According to an embodiment, the lead frame comprises a die pad comprising a die attach surface, a row of two or more leads that extend away from a first side of the die pad, and a peripheral structure disposed opposite the first side of the die pad and connected to each lead from the row of two or more lead. A first outermost lead of the row is continuously connected to the first side of the die pad. A second outermost lead of the row comprises an interior end that faces and is spaced apart from the first side of the die pad. A width of the second lead in a central span of the second lead is greater than the width of the second lead in an interior span of the second lead and in an outer span of the second lead, the interior span of the second lead separating the central span of the second lead from the interior end of the second lead, the outer span of the second lead separating the central span of the second lead from the peripheral structure. The second lead comprises an inner edge side that faces the first lead and extends from the interior end of the second lead to the peripheral structure, the inner edge side of the second lead is closer to the first lead in the central span of the second lead than in the interior and outer spans of the second lead.

Separately or combination, in the central span of the second lead, the inner edge side of the second lead comprises a central edge and first and second angled edges, and the central edge of the second lead is a closest surface of the second lead to the first lead.

Separately or combination, the row of leads comprises a third lead that is immediately adjacent to the second lead and comprises an interior end that faces and is spaced apart from the first side of the die pad, the third lead comprises an angled span disposed between interior and outer spans of the third lead, the interior span of the third lead separating the angled span from the interior end of the third lead, the angled span is disposed closer to the die pad than the central span of the second lead, and the angled span shifts the third lead away from the second lead.

Separately or combination, an angled width of the third lead in the angled span is no greater than <NUM> times the width of the third lead in the interior span, the angled width being measured in a direction that is perpendicular an outer edge side of the third lead in the angled span.

Separately or combination, a width of the first lead tapers incrementally moving from the die pad towards the peripheral structure.

Separately or combination, the first lead comprises an interior span, a central span, and an outer span, the interior span of the first lead separating the central span of the first lead from the die pad, the outer span of the first lead separating the central span of the first lead from the distal end of the first lead, the interior span of the first lead is wider than the central span of the first lead, and the central span of the first lead is wider than the outer span of the first lead.

Separately or combination, the first lead comprises an inner edge side that faces the second lead and extends from the die pad to the peripheral structure, the inner edge side of the first lead is closer to the second lead in the interior span of the first led than in the central span of the first lead, and the inner edge side of the first lead is closer to the second lead in the central span of the first lead than in the outer span of the first lead.

A semiconductor package is disclosed. According to an embodiment, the semiconductor package comprises a die pad comprising a die attach surface, a first semiconductor die mounted on the die attach surface, an encapsulant body of electrically insulating mold compound that encapsulates the first semiconductor die and comprises first, second and third outer faces, the first outer face extending between the second and third outer faces, and a row of two or more leads that extend away from a first side of the die pad and protrude out of the first outer face. A first outermost lead of the row is continuously connected to the first side of the die pad. A second outermost lead of the row comprises an interior end that faces and is spaced apart from the first side of the die pad. A width of the second lead in a central span of the second lead is greater than the width of the second lead in an interior span of the second lead and in an outer span of the second lead, the interior span of the second lead separating the central span of the second lead from the interior end of the second lead, the outer span of the second lead separating the central span of the second lead from a distal end of the second lead. The second lead comprises an inner edge side that faces the first lead and extends from the interior end to the distal end of the second lead, the inner edge side of the second lead is closer to the first lead in the central span of the second lead than in the interior and outer spans of the second lead.

Separately or in combination, in the central span of the second lead, the inner edge side of the second lead comprises a central edge and first and second angled edges, and the central edge of the second lead is a closest surface of the second lead to the first lead.

Separately or in combination, the row of leads comprises a third lead that is immediately adjacent to the second lead and comprises an interior end that faces and is spaced apart from the first side of the die pad, the third lead comprises an angled span disposed between an interior span and an outer span of the third lead, the interior span of the third lead separating the angled span from the interior end of the third lead, and the angled span is disposed closer to the die pad than the central span of the second lead, and the angled span shifts the third lead away from the second lead.

Separately or in combination, the semiconductor package further comprises first and second bond wires, both of the first and second bond wires are electrically connected to the second lead.

Separately or in combination, the semiconductor package further comprises a second semiconductor die mounted on the die attach surface, the first bond wire electrically connects the second lead to the first semiconductor die, and the second bond wire electrically connects the second lead to the second semiconductor die.

Separately or in combination, each of the first and second semiconductor dies is configured as a power transistor, and the second lead is configured as a control terminal of the semiconductor package.

Separately or in combination, the row of two or more leads comprises a third lead that protrudes out of the first outer wall and is immediately adjacent to the second lead, and the third lead is configured as a sensing terminal of the semiconductor package.

Separately or in combination, the row of two or more leads comprises a fourth lead that protrudes out of the first outer wall and is immediately adjacent to the first lead, the first and fourth leads are configured as voltage blocking terminals of the semiconductor package, and the encapsulant body further comprises an indentation in the first outer wall between the first and fourth leads.

According to another embodiment, the semiconductor package comprises a die pad comprising a die attach surface, a first semiconductor die mounted on the die attach surface, an encapsulant body of electrically insulating mold compound that encapsulates the first semiconductor die and comprises first, second and third outer faces, the first outer face extending between the second and third outer faces, and a row of two or more leads that extend away from a first side of the die pad and protrude out of the first outer face. A first outermost lead of the row is continuously connected to the first side of the die pad. A second outermost lead of the row comprises an interior end that faces and is spaced apart from the first side of the die pad. A width of the first lead tapers incrementally moving from the die pad towards a distal end of the first lead.

Separately or in combination, the first lead comprises an interior span, a central span, and an outer span, the interior span of the first lead separating the central span of the first lead from the die pad, the outer span of the first lead separating the central span of the first lead from the distal end of the first lead, the interior span of the first lead is wider than the central span of the first lead, and the central span of the first lead is wider than the outer span of the first lead.

Separately or in combination, the first lead comprises an inner edge side that faces the second lead and extends from the die pad to the peripheral structure, the inner edge side of the first lead is closer to the second lead in the interior span of the first lead than in the central span of the first lead, and the inner edge side of the first lead is closer to the second lead in the central span of the first lead than in the outer span of the first lead.

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.

Embodiments of a lead frame with an advantageous lead configuration and a corresponding semiconductor package is described herein. The lead frame includes a row of leads extending away from a first side of a die pad. The row of leads includes a first outermost lead at one side of the row and a second outermost lead at an opposite side of the row. The first outermost lead is continuously connected to the die pad, and may be configured as a drain terminal of the semiconductor package, for example. The second outermost lead is detached from the die pad, and may be configured as a gate terminal of the semiconductor package, for example. Both the first and second outermost leads have an advantageous multi-width configuration. Specifically, the width of the first outermost lead incrementally tapers moving away from the die pad. This tapered configuration provides mechanical support and stability to the die pad while simultaneously increasing the separation distance between the first outermost lead and the immediately adjacent lead, thereby improving creepage and clearance between the two. The width of the second outermost lead increases in a central span that is between an interior span and an outer span. This widened portion of the second outermost lead mitigates vibration of the second outermost lead during wire bonding. This allows for a narrowing of the interior portion of the second outermost lead, thereby improving creepage and clearance.

Referring to <FIG>, a lead frame assembly <NUM> is depicted, according to an embodiment. The lead frame assembly <NUM> is used to manufacture a molded semiconductor package. The lead frame assembly <NUM> includes a lead frame <NUM>, two semiconductor dies <NUM>, and a number of bond wires <NUM> forming electrical connections between the semiconductor die and the lead frame <NUM>.

The lead frame <NUM> includes an electrically conductive material such as copper (Cu) Nickel, (nickel phosphorous) NiP, silver (Ag), palladium (Pd) gold (Au), etc., alloys or combinations thereof. According to one technique, the lead frame <NUM> is provided by a sheet of metal, and the various features of the lead frame <NUM> are formed by performing techniques such as stamping, punching, etching, bending, etc., on this planar sheet of metal.

The lead frame <NUM> includes a die pad <NUM> with a generally planar die attach surface that is dimensioned to accommodate the semiconductor dies <NUM>. The lead frame <NUM> additionally includes a row of two or more leads that extend away from a first side <NUM> of the die pad <NUM>. The row of leads includes a first lead <NUM> and a second lead <NUM>. The first and second leads <NUM>, <NUM> are outermost leads, meaning that these leads include an outer edge side that does not face any other leads from the row. In the depicted embodiment, the row of leads additionally includes a third lead <NUM> and a fourth lead <NUM> disposed between the first and second leads <NUM>, <NUM>. The third and fourth leads <NUM>, <NUM> are interior leads, meaning that meaning that both outer edge sides of these leads face other leads from the row. The first lead <NUM> is continuously connected to the die pad <NUM>. That is, the first lead <NUM> is directly attached or merges with the first side <NUM> of the die pad <NUM>. The second, third and fourth leads <NUM>, <NUM>, <NUM> each include an interior end <NUM> that is spaced apart from the first side <NUM> of the die pad <NUM>.

The lead frame <NUM> additionally includes a peripheral structure <NUM>. The peripheral structure <NUM> is a handling feature for supporting and moving the lead frame <NUM> through the various processing tools that perform the semiconductor package assembly steps, e.g., die attach, wire bonding, encapsulation, etc. In the depicted embodiment, the peripheral structure <NUM> has a ring shape and the die pad <NUM> is centrally located inside of the ring. In other embodiments, the peripheral structure <NUM> may form a ring disposed only on one side of the die pad <NUM>, and may include dam bars between two or more leads and/or spaced apart rails for handling and supporting the lead frame <NUM> during manufacture.

The semiconductor dies <NUM> may each include a lower surface terminal (not shown) that faces the die pad <NUM>. The first lead <NUM> may be electrically connected to the lower surface terminals of the first and second semiconductor dies <NUM> via the die pad <NUM>. To this end, a conductive adhesive, e.g., solder, sinter, conductive glue, diffusion solder, etc., may be provided between the rear side of the semiconductor dies <NUM> and the die attach surface. Additionally, the semiconductor dies <NUM> each include first, second and third upper surface terminals <NUM>, <NUM>, <NUM> that face away from the die pad <NUM>. These upper surface terminals are electrically connected to the second, third and fourth leads <NUM>, <NUM>, <NUM> by the electrically conductive bond wires <NUM>. Specifically, one of the bond wires <NUM> is connected between the second lead <NUM> and the first upper surface terminal <NUM> from each semiconductor die <NUM>, one of the bond wires <NUM> is connected between the third lead <NUM> and the second upper surface terminal <NUM> from each semiconductor die <NUM>, and two of the bond wires <NUM> are connected between the fourth lead <NUM> and the third upper surface terminal <NUM> from each semiconductor die <NUM>.

According to an embodiment, the semiconductor dies <NUM> are each configured as power transistors, e.g., MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or Insulated Gate Bipolar Transistors (IGBT) configured to control large voltages, e.g., <NUM> volts or more, and/or accommodate large currents, e.g., <NUM> ampere or more. In this embodiment, the semiconductor dies <NUM> are connected in parallel with one another. In this example, the lower surface terminals of the semiconductor dies <NUM> can be the drain or collector terminals, the first upper surface terminals <NUM> can be the gate terminals, the second upper surface terminals <NUM> can be sensing terminals, and the third upper surface terminals <NUM> can be the source or emitter terminals. The sensing terminals are optional terminals used to finely tune the operation of the device. For example, the second upper surface terminal <NUM> can be a gate terminal that indicates a gate current of the device. In another example, the second upper surface terminal <NUM> can be a source sense terminal that indicates a source current of the device. In another example, second upper surface terminal <NUM> can be may be a temperature sense terminal that indicates the temperature of the semiconductor die.

More generally, the semiconductor dies <NUM> can have a variety of device configurations. For example, the semiconductor dies <NUM> can be configured as transistors, diodes, thyristors, etc. Moreover, the semiconductor dies <NUM> may have vertical device configurations and lateral device configurations. The lead frame <NUM> can be adapted to have a lead count commensurate with a particular device configuration. For example, in the case that the semiconductor die <NUM> is configured as a three-terminal device (e.g., a transistor without a sense terminal), the lead frame <NUM> can have a similar configuration as shown, but with the third lead <NUM> omitted. In the case that the semiconductor die <NUM> is configured as a two-terminal device (e.g., a diode), the lead frame <NUM> can have a similar configuration as shown, but with the third and fourth leads <NUM>, <NUM> omitted. The lead frame assembly <NUM> may also be implemented with different numbers of dies. For instance, the lead frame assembly <NUM> may be used to package one, two, three, four, etc., semiconductor dies. The lead configuration of lead frame <NUM> may also be implemented in other taped of packages, such as intelligent power modules (IPMs), power modules (PMs), dual inline packages (DIPs) or surface mounted power packages (SMDs).

The first lead <NUM> has a width that tapers incrementally moving from the die pad <NUM> towards the peripheral structure <NUM>. That is, the first lead <NUM> includes distinguishable spans that get progressively narrower moving away from the die pad <NUM>. In the depicted embodiment, the first lead <NUM> includes an interior span <NUM>, a central span <NUM>, and an outer span <NUM>. The interior span <NUM> of the first lead <NUM> separates the central span <NUM> of the first lead <NUM> from the die pad <NUM>, and the outer span <NUM> of the first lead <NUM> separates the central span <NUM> from the peripheral structure <NUM>. The interior span <NUM> of the first lead <NUM> is wider than the central span <NUM> of the first lead <NUM>, and the central span <NUM> of the first lead <NUM> is wider than the outer span <NUM> of the first lead <NUM>. Generally speaking, the width of the first lead <NUM> in the interior span <NUM> can be between about <NUM> to <NUM> times the width of the first lead <NUM> in the central span <NUM>, and the width of the first lead <NUM> in the central span <NUM> can be between about <NUM> to <NUM> times the width of the first lead <NUM> in the outer span <NUM>. Stated in terms of exemplary absolute values, the width of the first lead <NUM> in the interior span <NUM> can be between about <NUM> and <NUM>, the width of the first lead <NUM> in the central span <NUM> can be between about <NUM> and <NUM>, and width of the first lead <NUM> in the outer span <NUM> can be between about <NUM> and <NUM>. In this context, the width of the first lead <NUM> is a separation distance between the inner and outer edge sides <NUM>, <NUM> of the second lead <NUM> measured along a line which crosses inner and outer edge sides <NUM>, <NUM> of the first lead <NUM> at the same separation distance from the interior end <NUM> of the first lead <NUM>.

According to an embodiment, the inner edge side <NUM> of the first lead <NUM> has an undulating profile. The inner edge side <NUM> of the first lead <NUM> faces the second lead <NUM> and extends from the die pad <NUM> to the peripheral structure <NUM>. The undulating profile of the inner edge side <NUM> is such that the nearest surface of the first lead <NUM> moves away from the second lead <NUM> as the first lead <NUM> approaches the peripheral structure <NUM>. Specifically, the inner edge side <NUM> of the first lead <NUM> is closer to the second lead <NUM> in the interior span <NUM> of the first lead <NUM> than in the central span <NUM> of the first lead <NUM>, and is closer to the second lead <NUM> in the central span <NUM> of the first lead <NUM> than in the outer span <NUM> of the first lead <NUM>. In the depicted embodiment, the inner edge side <NUM> of the first lead <NUM> includes angled transitions between the interior span <NUM> and the central span <NUM> and between the central span <NUM> and the outer span <NUM>. More generally, the inner edge side <NUM> of the first lead <NUM> may include abrupt or perpendicular angled and/or curved transitions between the various spans of the first lead <NUM>.

The second lead <NUM> has a width that increases in a central region that is between the interior end <NUM> of the second lead <NUM> and the peripheral structure <NUM>. The second lead <NUM> includes an interior span <NUM>, a central span <NUM>, and an outer span <NUM>. The interior span <NUM> of the second lead <NUM> separates the central span <NUM> of the second lead <NUM> from the interior end <NUM> of the second lead <NUM>, and the outer span <NUM> of the second lead <NUM> separates the central span <NUM> from the peripheral structure <NUM>. A width of the second lead <NUM> is greater in the central span <NUM> than the width of the second lead <NUM> in the interior span <NUM>. Moreover, the width of the second lead <NUM> is greater in the central span <NUM> than the width of the second lead <NUM> in the outer span <NUM>. The width of the second lead <NUM> is measured between inner and outer edge sides <NUM>, <NUM> of the second lead <NUM>. The inner and outer edge sides <NUM>, <NUM> of the second lead <NUM> each extend from the interior end <NUM> of the second lead <NUM> to the peripheral structure <NUM>. In this context, the width of the second lead <NUM> is a separation distance between the inner and outer edge sides <NUM>, <NUM> of the second lead <NUM> measured along a line which crosses inner and outer edge sides <NUM>, <NUM> of the second lead <NUM> at the same separation distance from the interior end <NUM> of the second lead <NUM>.

Generally speaking, the width of the second lead <NUM> in the central span <NUM> can be between about <NUM> to <NUM> times the width of the second lead <NUM> in both the interior span <NUM> of the of the second lead <NUM> and in the outer span <NUM> of the second lead <NUM>. In these embodiments, the width of the second lead <NUM> in the interior span <NUM> need not be identical to the width of the second lead <NUM> in the outer span <NUM>. For instance, the width of the second lead <NUM> in the interior span <NUM> may be between about <NUM> and <NUM> times the width of the second lead <NUM> in the outer span <NUM>. Stated in terms of exemplary absolute values, the width of the second lead <NUM> in the central span <NUM> can be between about <NUM> and <NUM> (millimeters), the width of the second lead <NUM> in the interior span <NUM> can be between about <NUM> and <NUM>, and the width of the second lead <NUM> in the outer span <NUM> can be between about <NUM> and <NUM>.

According to an embodiment, the inner edge side <NUM> of the second lead <NUM> has an undulating profile. The inner edge side <NUM> of the second lead <NUM> faces the first lead <NUM> and extends from the die pad <NUM> to the peripheral structure <NUM>. The inner edge side <NUM> of the second lead <NUM> undulates such that the inner edge side <NUM> of the second lead <NUM> is closer to the first lead <NUM> in the central span <NUM> of the second lead <NUM> than in the interior and outer spans <NUM>, <NUM> of the second lead <NUM>. In an embodiment, the inner edge side <NUM> of the second lead <NUM> includes a central edge <NUM>, which is a closest surface of the first lead <NUM> to the second lead <NUM>, and first and second angled edges <NUM> that transition from the central edge <NUM> to the narrower portions of the second lead <NUM>. The first and second angled edges <NUM> form angled intersections in the inner edge side <NUM> of the second lead <NUM>. These angled intersections may form angles of between about <NUM> and <NUM> degrees in the inner edge side <NUM> of the second lead <NUM>, for example. More generally, the increased width of the central span <NUM> can be obtained by any undulating profile in the inner edge side <NUM> of the second lead <NUM> which produces a wing-shaped feature extending towards the first lead <NUM>. The undulating profile may include curved surfaces, for example.

The third lead <NUM> is an interior lead that is immediately adjacent to the second lead <NUM> and has a shifted geometry. This shifted geometry accommodates the widening of the second lead <NUM> while maintaining minimum separation distance between the second and third leads <NUM>, <NUM>. To this end, the third lead <NUM> includes an angled span <NUM> disposed between an interior span <NUM> and an outer span <NUM> of the third lead <NUM>. The interior span <NUM> of the third lead <NUM> separates the angled span <NUM> from the interior end <NUM> of the third lead <NUM>. Likewise, the outer span <NUM> of the third lead <NUM> separates the angled span <NUM> from the peripheral structure <NUM>. The angled span <NUM> is disposed closer to the die pad <NUM> than the central span <NUM> of the second lead <NUM>. This means that a closet portion of the angled span <NUM> to the die pad <NUM> is closer than a closest portion of the central span <NUM> of the second lead <NUM> to the die pad <NUM>. The angled span <NUM> shifts the third lead <NUM> away from the second lead <NUM>. The geometry of the angled span <NUM> may mirror that of the central span <NUM> of the second lead <NUM> to maintain minimum separation distance between the two leads. For instance, an edge side <NUM> of the third lead <NUM> which faces the second lead <NUM> may have the same orientation as the first angled edge <NUM> of the second lead <NUM> such that these two edges are parallel to one another.

According to an embodiment, an angled width of the third lead <NUM> in the angled span <NUM> is the same or substantially close to the width of the third lead <NUM> in the interior span <NUM> of the third lead <NUM> and/or the outer span <NUM> of the third lead <NUM>. For example, the angled width of the third lead <NUM> in the angled span <NUM> may be no greater than <NUM> times the greater of the width of the third lead <NUM> in the interior span <NUM> and the width of the third lead <NUM> and the outer span <NUM>. In a preferred embodiment, the angled width of the third lead <NUM> is between about <NUM> and <NUM> times the width of the third lead <NUM> in the interior span <NUM>. Stated in terms of exemplary absolute values, the angled width of the third lead <NUM> can be between about <NUM> and <NUM>, the width of the third lead <NUM> in the interior span <NUM> can be between about <NUM> and <NUM>, and the width of the third lead <NUM> in the outer span <NUM> can be between about <NUM> and <NUM>. In this context, the angled width of the third lead <NUM> in the angled span <NUM> is a separation distance between the edge sides <NUM> of the third lead <NUM> measured along a line which is perpendicular to the edge sides <NUM> of the third lead <NUM> in the angled span <NUM>, and the width of the third lead <NUM> in the inner and outer spans <NUM>, <NUM> is a separation distance between the edge sides <NUM> of the third lead <NUM> measured along a line which crosses the outer edge sides <NUM> of the third lead <NUM> at the same separation distance from the interior end <NUM> of the third lead <NUM>.

The lead frame assembly <NUM> is used to form a packaged semiconductor device in the following way. Initially, the semiconductor dies <NUM> are mounted on the die pad <NUM> using a conductive adhesive, e.g., solder, sinter, conductive glue, etc. Subsequently, a wire bonding process is performed to electrically connect the various leads of the lead frame <NUM> to the various terminals of the semiconductor dies <NUM>. Subsequently, an encapsulation process is performed to encapsulate the semiconductor die and associated electrical connections between the terminals of the semiconductor dies <NUM> and the leads. The encapsulant body can be formed by a molding process such injection molding, transfer molding, compression molding, etc. After performing the encapsulation process, a lead trimming process is performed. The lead trimming process separates each of the leads from the peripheral structure <NUM> along the cutting line <NUM> shown in <FIG>.

Referring to <FIG>, a semiconductor package <NUM> that is formed using the leadframe assembly of <FIG> is depicted, according to an embodiment. The semiconductor package <NUM> includes an encapsulant body <NUM> of electrically insulating mold compound. The encapsulant body <NUM> can include electrically insulating materials such as ceramics, epoxy materials and thermosetting plastics, to name a few. The encapsulant body <NUM> includes a first outer face <NUM> that extends between opposite facing second and third outer faces <NUM>, <NUM>. Each of the first, second, third and fourth leads <NUM>, <NUM>, <NUM>, <NUM> protrudes out of the first outer face <NUM>. Moreover, each of the first, second, third and fourth leads <NUM>, <NUM>, <NUM>, <NUM> includes a distal end <NUM> that is opposite from the die pad <NUM>. These distal ends <NUM> are formed by the lead trimming process as described above.

According to an embodiment, the first and fourth leads <NUM>, <NUM> are configured as voltage blocking terminals by virtue of the above discussed electrical connections to the corresponding terminals of the semiconductor dies <NUM>. A voltage blocking terminal refers to a device terminal to which an operating voltage is applied across. For example, in the case that the semiconductor dies <NUM> are configured as MOSFETs, the first and fourth leads <NUM>, <NUM> can be the drain and source terminals of the device. Along similar lines, the second lead <NUM> may be configured as a control terminal (e.g., a gate) and the third lead <NUM> may be configured as a sensing terminal (e.g., source sense, temperature sense, etc.) by virtue of the above discussed electrical connections to the corresponding terminals of the semiconductor dies <NUM>.

The encapsulant body <NUM> is formed to include an indentation <NUM> in the first outer face <NUM>. The indentation <NUM> is a feature which increases the creepage, i.e., length along the encapsulant material, between the first and fourth leads <NUM>, <NUM>, i.e., the voltage blocking terminals of the device. Generally speaking, the indentation <NUM> is configured to have as much surface length as possible. Instead of the rectangular-shaped configuration shown in the depicted embodiment, the indentation <NUM> may include curved surfaces and/or obtuse angles.

The lead configuration of the semiconductor package <NUM> enables an advantageously high creepage and clearance between the first and fourth leads <NUM>, <NUM>, which form the voltage blocking terminals of the device. The lead configuration of the semiconductor package <NUM> allows for increased separation between the first and fourth leads <NUM>, <NUM>, both within the encapsulant body <NUM> and at the location wherein the first and fourth leads <NUM>, <NUM> protrude from the first outer face <NUM> of the encapsulant body <NUM>. This enables an increase in the straight-line distance between the first and fourth leads <NUM>, <NUM> and enables a larger sized indentation <NUM>.

The configuration of the second and third leads <NUM>, <NUM> allows for increased separation between the first and fourth leads <NUM>, <NUM> by enabling a thinning of the second and third leads <NUM>, <NUM> without impacting the integrity of the wire bond connections. One problem with reducing the width of a package lead is that thinner leads have a greater tendency to vibrate during the wire bonding process. This is particularly problematic in the case that two separate wire bonds are made to a single package lead, as is the case for the second and third leads <NUM>, <NUM> in the above embodiments. In that case, the vibration of the lead can disrupt and detach the first-formed wire bond when forming the subsequent wire bond. The multi-width configuration of the second and third leads <NUM>, <NUM> produces greater stabilization for the wire bonding tool to grasp these lead and mitigate vibration. The angled span <NUM> of the third lead <NUM> accommodates the widened the central span <NUM> of the second lead <NUM> while also providing a locally wider portion in the third lead <NUM> to mitigate lead vibration. However, the inventors have observed that widening the angled span <NUM> the third lead <NUM> too much causes unwanted mechanical weakness at the transition between the outer span <NUM> of the third lead <NUM> and the angled span <NUM> of the third lead <NUM>. Generally speaking, keeping the angled width of the angled span <NUM> to be the same or substantially close to the width of the third lead <NUM> in other regions, e.g., no greater than <NUM> times the width of the third lead <NUM> in the outer span <NUM> and/or the interior span <NUM>, maintains acceptable mechanical strength. Collectively, the geometries of the second and third leads <NUM>, <NUM> allows for narrowing of the interior spans <NUM> of these leads, which enables shifting of both leads away from the first lead <NUM>, thereby improving creepage and clearance.

The lead configuration of the first lead <NUM> enables the advantageously high creepage and clearance by allowing for a larger separation distance between the first and fourth leads <NUM>, <NUM> while maintaining adequate mechanical support of the die pad <NUM>. As the first lead <NUM> is directly connected to the die pad <NUM>, it provides some or all of the mechanical support to the die pad <NUM> during the assembly process. By forming the first lead <NUM> with a tapered width, and particularly by configuring the interior span <NUM> of the first lead <NUM> as the widest portion of the lead, the first lead <NUM> provides enhanced mechanical support to the die pad <NUM> in comparison to a uniform or decreased width configuration in this portion of the lead. Thus, the die pad <NUM> remains mechanically stable during die attach, wire bonding, encapsulation, etc., thereby mitigating the possibility of detachment or failure of the various elements. Meanwhile, by gradually narrowing and shifting away from the fourth lead <NUM> as the first lead <NUM> moves away from the die pad <NUM>, a greater separation distance between the first and fourth leads <NUM>, <NUM> is produced, and a larger sized indentation <NUM> is possible.

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.

Claim 1:
A lead frame (<NUM>), comprising:
a die pad comprising a die attach surface;
a row of two or more leads (<NUM>, <NUM>) that extend away from a first side (<NUM>) of the die pad; and
a peripheral structure (<NUM>) disposed opposite the first side (<NUM>) of the die pad and connected to each lead (<NUM>, <NUM>) from the row of two or more leads (<NUM>, <NUM>),
wherein a first outermost lead (<NUM>) of the row is continuously connected to the first side (<NUM>) of the die pad,
wherein a second outermost lead (<NUM>) of the row comprises an interior end (<NUM>) that faces and is spaced apart from the first side (<NUM>) of the die pad,
wherein a width of the second lead (<NUM>) in a central span (<NUM>) of the second lead (<NUM>) is greater than the width of the second lead (<NUM>) in an interior span (<NUM>) of the second lead (<NUM>) and in an outer span (<NUM>) of the second lead (<NUM>), the interior span (<NUM>) of the second lead (<NUM>) separating the central span (<NUM>) of the second lead (<NUM>) from the interior end (<NUM>) of the second lead (<NUM>), the outer span (<NUM>) of the second lead (<NUM>) separating the central span (<NUM>) of the second lead (<NUM>) from the peripheral structure (<NUM>), wherein the second lead (<NUM>) comprises an inner edge side (<NUM>) that faces the first lead (<NUM>) and extends from the interior end (<NUM>) of the second lead (<NUM>) to the peripheral structure (<NUM>), characterized in that the inner edge side (<NUM>) of the second lead (<NUM>) is closer to the first lead (<NUM>) in the central span (<NUM>) of the second lead (<NUM>) than in the interior and outer spans (<NUM>, <NUM>) of the second lead (<NUM>).