Power module and related method

Abstract

The present invention is entitled "Power Module and Related Methods". Embodiments of the power module may include: a substrate having a first side and a second side. The power module may include a plurality of leads coupled to the second side of the substrate and a molding compound over a portion of five or more surfaces of the substrate. The power module may also include an opening extending from the first side of the substrate to an outer edge of the molding compound. The opening may be configured to receive a coupling device, and the coupling device may be configured to couple to a heat sink or a package support.

Description

[0001] Cross-references to related patent applications

[0002] This document claims the benefit of the filing date of U.S. Provisional Patent Application 62 / 736,521 to Zhou et al., entitled “Power Modules and Related Methods,” filed on September 26, 2018, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] Aspects of this document generally relate to power modules, such as switches, bridges, and inverters. More specific embodiments relate to metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). Background Art

[0004] The power integrated module processes the power according to the information content at the control interface. The functions covered by the power module include the type of power source bus, the passive components integrated into the bus, and the passive components integrated into the load. The integrated power module provides a physically closed package for several power components (usually power semiconductor devices). Summary of the invention

[0005] Embodiments of a power module may include: a substrate having a first side and a second side. The power module may include a plurality of leads coupled to the second side of the substrate and a molding compound over a portion of five or more surfaces of the substrate. The power module may also include an opening extending from the first side of the substrate to an outer edge of the molding compound. The opening may be configured to receive a coupling device, and the coupling device may be configured to couple to a heat sink or a package support.

[0006] Embodiments of the power module may include one, all or any of the following:

[0007] The power module may further include a standoff unit positioned around the opening on the outer edge of the molding compound. The standoff unit may be configured to support the package against a heat sink or a package support.

[0008] The package of claim 1, further comprising a second opening, wherein the first opening and the second opening are evenly spaced within the package.

[0009] The plurality of leads may include a 3.81 mm pitch.

[0010] The plurality of leads may each be an equal distance away from two or more leads on one side of a lead frame including the plurality of leads.

[0011] The power module may also include one or more dies mechanically and electrically coupled to the second side of the substrate.

[0012] Embodiments of the power module may be formed using a method of forming a power module, the method may include: coupling a lead frame to a substrate. The lead frame may have a plurality of leads extending from the frame on each of four sides of the lead frame. The method may include selectively trimming a first plurality of leads of the plurality of leads. The method may also include forming an encapsulation around at least five surfaces of the substrate and a portion of each of the second plurality of leads of the plurality of leads. The method may include trimming the lead frame, trimming the lead frame including trimming one or more of the plurality of leads to a predetermined length.

[0013] Embodiments of a method of forming a power module may include one, all, or any of the following:

[0014] The method may further include using a securing device to prevent the flow envelope from entering one or more mounting holes in the substrate.

[0015] The lead frame may be coupled to the substrate by one of soldering or sintering.

[0016] Forming the encapsulant may include using a transfer molding process.

[0017] A first plurality of the plurality of leads may not extend into the encapsulation and may be completely removed with the lead frame during trimming of the lead frame.

[0018] The base plate may also include a mounting hole extending from the first side to the second side of the base plate.

[0019] The substrate may include one of the following: a direct bonded copper substrate (DBC) with a ceramic core, a direct bonded aluminum (DBA) substrate, an active metal brazing (AMB) substrate, an insulated metal substrate (IMS), an electroplated ceramic substrate, a high layer count (HLC) printed wiring board (PWB), a low temperature co-fired ceramic (LTCC) substrate, a high temperature co-fired ceramic (HTCC) substrate, or a polymer-coated conductive plate.

[0020] Embodiments of the power module may be formed using a method of forming a power module, the method may include providing a substrate having a first side, a second side, and one or more mounting holes extending from the first side to the second side. The method may include coupling a lead frame having a plurality of leads to the substrate. The method may include selectively trimming a first plurality of leads from the plurality of leads. The method may include encapsulating at least five surfaces and a portion of each of the plurality of leads in a molding compound. The method may include trimming the lead frame from the plurality of leads.

[0021] Embodiments of a method of forming a power module may include one, all, or any of the following:

[0022] The base plate may include two mounting holes extending from a first side of the base plate to a second side of the base plate.

[0023] The selectively trimmed leads of a first plurality of leads among the plurality of leads may not extend into a cavity included in the transfer molding process.

[0024] Forming the encapsulant may include using a transfer molding process.

[0025] The encapsulant may include one of an epoxy, a resin, a polymer, or any combination thereof.

[0026] The foregoing and other aspects, features and advantages will be apparent to those skilled in the art from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments will be described below in conjunction with the accompanying drawings, in which like reference numerals represent like elements, and:

[0028] Figure 1 is a cross-sectional view of an embodiment of a power module;

[0029] Figure 2 is a top view of an embodiment of a lead frame;

[0030] Figure 3 is a top view of an embodiment of a substrate;

[0031] Figure 4 is a top view of an embodiment of a lead frame coupled to a second side of an embodiment of a substrate;

[0032] Figure 5 is a top view of an embodiment of a cylinder inserted through a mounting hole of an embodiment of a base plate;

[0033] Figure 6 is a top view of an embodiment of a cylinder inserted through a mounting hole of an embodiment of a base plate, the base plate being encapsulated with a molding compound;

[0034] Figure 7 is a top view of an embodiment of a substrate and a lead frame encapsulated with a molding compound;

[0035] Figure 8 is a top view of an embodiment of a substrate coupled to an embodiment of a plurality of leads;

[0036] Fig. 9 is a top view of another embodiment of a lead frame having selectively trimmed leads;

[0037] Fig.10 is a top view of another embodiment of a substrate;

[0038] Fig.11 is a top view of an embodiment of a lead frame coupled to an embodiment of a substrate;

[0039] Fig.12 is a top view of an embodiment of a substrate and an embodiment of a lead frame encapsulated with a molding compound;

[0040] Fig.13 is a top view of an embodiment of a substrate coupled to an embodiment of a plurality of leads;

[0041] Fig.14 is a top view of an embodiment of a power module;

[0042] Fig.15 is a top view of an embodiment of a set of substrates;

[0043] Fig.16 is a perspective view of a first side of an embodiment of a power module having a first mounting hole; and

[0044] Fig.17 is a perspective view of a second side of an embodiment of a power module having a first mounting hole and a second mounting hole. DETAILED DESCRIPTION

[0045] The present disclosure, its aspects, and embodiments are not limited to the specific components, assembly processes, or method elements disclosed herein. Many additional components, assembly processes, and / or method elements known in the art that are consistent with the intended power module will be readily apparent for use with specific embodiments of the present disclosure. Thus, for example, although the present invention discloses specific embodiments, such embodiments and implementation components may include any shape, size, style, type, model, version, measurement, concentration, material, quantity, method element, step, etc. known in the art for such power modules and implementation components and methods that are consistent with the intended operation and method.

[0046] In various power module designs, it is generally desirable to keep the package size as small as possible.At least some of the power modules and packages disclosed in this document may be referred to as quad lead frame packages (QLPs).

[0047] refer to Figure 1, a side view of an embodiment of a power module 2 is shown. The power module includes a substrate 4, which is coupled to a lead 6 and encapsulated with a molding compound 8. In the specific embodiment shown, the substrate 4 is a direct bonded copper substrate (DBC) with a ceramic core. The substrate can be electrically insulated from the exposed portions for heat conduction. In various embodiments, the substrate can be (as a non-limiting example): a direct bonded aluminum (DBA) substrate, an active metal brazing (AMB) substrate, an insulated metal substrate (IMS), an electroplated ceramic substrate, a high-layer count (HLC) printed wiring board (PWB), a low-temperature co-fired ceramic (LTCC) substrate, a high-temperature co-fired ceramic (HTCC) substrate, a polymer-coated conductive plate, or any other substrate type with desired reliability, heat dissipation and / or local emission characteristics. In various embodiments, the ceramic may include an aluminum oxide (Al2O3) ceramic doped with zirconium dioxide (ZrO2), a silicon nitride (Si3N4) ceramic, an aluminum nitride (AlN) ceramic, a high-strength AlN (H-AlN) ceramic, or any combination thereof.

[0048] Module 2 also includes mounting holes 10 extending from a first side 12 of the module to a second side 14 of the module. Mounting holes 10 can be used to mount a heat sink to the module and / or to mount the module to a support (circuit board, motherboard, etc.). As shown, supports 16 are positioned around the periphery of mounting holes 10. These supports can support the weight of the heat sink and protect the module from deflection / bending under the force of screws or other coupling devices that hold the module to the support or heat sink. In various embodiments, the package may include a first mounting hole and a second mounting hole. In other embodiments, the package may include more than two mounting holes. As shown, in this embodiment, one or more dies are coupled to the first side of the substrate. Wire bonding is also shown, which couples one or more dies to other parts of the substrate and other devices in the module mechanically and electrically. The structure of the module can have high reliability and extremely low thermal resistance. The module can also have a high current capacity in the range of about 75A to about 150A.

[0049] Various embodiments of the power module may include a silicon carbide freewheeling diode (FWD). The FWD may be included in a power integrated module (PIM) or a converter inverter brake (CIB). The CIB has three functional modules, including a converter, an inverter, and a brake. The converter may include a rectifier with four to six diodes. The inverter may include six IGBTs and six FWDs. The brake may be integrated with the FWD.

[0050] refer to Figures 2 to 6, various power module embodiments are shown after various processing steps in an embodiment of a method for forming a power module. As will be described, the assembly process of such a power module can be simplified, and a compact and lighter package can be produced. The method includes providing a lead frame 18. As shown here, the lead frame 18 is fully populated with a plurality of leads 20 having a pitch of approximately 3.8 mm. The plurality of leads are positioned on four sides of the frame and inward toward the center of the lead frame. Each group of the plurality of leads 20 on the lead frame includes leads that are equidistant relative to each other (except on the right side of the corner area, where the leads are offset to accommodate the corner).

[0051] refer to Figure 3 The method includes providing a substrate 22. In various embodiments, the substrate may include a DBC substrate. Fig.15 As shown, the substrate can be separated from a set of substrates 23 (sometimes referred to as a master card of substrates). In various embodiments, the method may include forming a hole 24 through the substrate, wherein the hole will form Figure 1 . In other embodiments, the base plate may be preassembled with a hole therethrough. The hole may be formed by, as a non-limiting example, drilling, laser drilling, punching, or any other method of forming an opening. Figure 4 , the method includes coupling the lead frame 18 and the substrate 22 together. The lead frame is coupled to the second side of the substrate. In various embodiments, the substrate can be coupled to the first side or the second side of the substrate. In some methods, the leads can be coupled to the substrate by (as non-limiting examples) adhesives, welding, ultrasonic welding, or other methods for coupling metal parts.

[0052] The method also includes inserting the cylinder / rod through the mounting hole in the base plate. Figure 5, showing a cylinder 25 positioned through the mounting hole 24 of the substrate 22. The cylinder is used for exemplary purposes of the present disclosure, and, by way of non-limiting example, various tools, molds (multiple or single pieces), fixtures or fixtures may be used in various embodiments that are designed to prevent encapsulation from flowing into the mounting hole. During the molding process, the cylinder / tool ​​prevents the molding compound from filling or covering the mounting hole. In various embodiments, the cylinder / tool ​​may be formed of a durable metal including steel. In other embodiments, the cylinder / tool ​​may be formed of plastic, resin, or another material that can withstand high temperatures and high pressures. The material of the cylinder / tool ​​may also be a material that does not react with the molding compound / encapsulant or other components of the semiconductor and the materials used in the process of forming the semiconductor material. In other embodiments, other tools or fixtures may be configured to prevent the molding compound from flowing into the mounting hole during encapsulation. In some embodiments, the substrate may include more than one mounting hole, and the tool / fixture may be configured to prevent the encapsulant from flowing into all mounting holes during encapsulation.

[0053] The method also includes forming a molding compound 26 over the substrate 22 and over a portion of the leads 20 extending from the lead frame 18. The molding compound is also formed around the cylinder in the mounting hole. Figure 6 , shows the substrate 22 and lead frame after being encapsulated with the molding compound 24. The molding compound may be formed using transfer molding techniques. Transfer molding is a manufacturing process in which a molding material (such as (as a non-limiting example) a resin or epoxy) is forced into a mold or cavity. The molding material is measured and placed into a molding pot. As the material is heated, pressure forces the material into the mold / cavity. In various embodiments of the method of forming a power module, the molding cavity may include a cylinder that is positioned in a hole in the substrate to form a Figure 1 The mounting holes shown in the figure are used to prevent the molding compound from entering the area of ​​the mounting holes. In some embodiments, the molding compound used may include (as a non-limiting example) epoxy resins, resins, polymers, and other materials that can withstand high temperatures and high electronic stresses. In some embodiments of the method of forming a semiconductor package, the cylinder can be removed after encapsulation with the molding compound. Reference Figure 7 , shows the substrate after the cylinder is removed. In some embodiments, the cylinder is not removed until after the leadframe is trimmed from the leads.

[0054] The method of forming a power module includes trimming / singling a lead frame from a plurality of leads 20. The resulting package with exposed leads may be a high voltage power module including, but not limited to, a switch (MOSFET, IGBT) with an anti-parallel diode, a half-bridge (an inverter leg with two switches and their corresponding diodes), a three-phase inverter (six switches and corresponding diodes), or any other power device / module described herein. Figure 8 , showing the formed power module 28. The power module 28 includes a substrate having a first side and a second side. The substrate may include (as a non-limiting example): a direct bonded copper substrate (DBC) with a ceramic core, a direct bonded aluminum (DBA) substrate, an active metal brazing (AMB) substrate, an insulated metal substrate (IMS), a plated ceramic substrate, a high-layer count (HLC) printed wiring board (PWB), a low-temperature co-fired ceramic (LTCC) substrate, a high-temperature co-fired ceramic (HTCC) substrate, a polymer-coated conductive plate, or any other substrate type with desired reliability, heat dissipation and / or local emission characteristics. As previously described, the ceramic within the substrate may include an aluminum oxide (Al2O3) ceramic doped with zirconium dioxide (ZrO2), a silicon nitride (Si3N4) ceramic, an aluminum nitride (AlN) ceramic, a high-strength AlN (H-AlN) ceramic, or any combination thereof.

[0055] Still reference Figure 8 , the substrate is encapsulated in a molding compound 26. In various embodiments, the molding compound may include epoxy resins, resins, polymers, and other materials that can withstand high temperatures and high electronic stresses. The power module 28 also includes an opening 24 extending from the first side of the substrate to the outer edge of the molding compound. The opening may be configured to receive a coupling device, and the coupling device may be configured to couple to a heat sink or one of the package supports. In various embodiments, the opening may be preformed in the substrate. In other embodiments, the method may include forming an opening in the substrate by drilling / forming using any method disclosed herein. The plurality of leads may include a spacing of approximately 3.81 mm. As shown, the plurality of leads are each equidistant from two leads on either side of each of the leads.

[0056] In various embodiments, the die can be mechanically and electrically coupled to the second side of the substrate. In various embodiments, the power module can be used in high power applications such as, by way of non-limiting example, commercial applications, industrial applications, automotive applications, and other applications requiring reduced package size and sufficient clearance distance.

[0057] refer to Figures 9 to 13 , shows a power module after various processing steps used in another embodiment of a method of forming a power module. The method includes providing a lead frame. Reference Fig. 9 , a lead frame 30 is shown. The lead frame 30 includes a plurality of leads 32 on four sides of the frame. The plurality of leads on each side of the lead frame are equidistant from each other (except in the corner areas to accommodate the shape of the corners). In various embodiments, the leads have a pitch of about 3.81 mm, but in various embodiments, many other pitch values ​​may be utilized.

[0058] The method includes selectively trimming one or more leads of the lead frame to a predetermined length (a first group in the leads). The trimmed leads 34 extend from the frame a distance less than the distance of the untrimmed leads 36. The trimmed leads 34 may be referred to as being selectively removed. This selective trimming process may be performed when the lead frame is initially formed (i.e., the lead frame is formed to have shortened leads when manufactured). In some method embodiments, the selective trimming process may be performed after the lead frame is initially formed, wherein one or more leads in the already formed leads are trimmed to a desired length. In various embodiments, the leads may be trimmed by cutting.

[0059] refer to Fig.10 , the method further includes providing a substrate 38. In various embodiments, the substrate 38 may be any type of substrate disclosed herein, such as (as a non-limiting example) a direct bonded aluminum (DBA) substrate, an active metal brazed (AMB) substrate, an insulated metal substrate (IMS). As shown, the substrate 38 includes a hole 40 extending from a first side of the substrate to a second side of the substrate. In various embodiments of the method, the substrate 38 may be provided with pre-made holes. In other embodiments, the method may include cutting / drilling holes through the substrate using any method disclosed herein.

[0060] The method includes coupling a lead frame to a substrate. Fig.11 , shows a lead frame 30 coupled to a substrate 38 by solder. In other embodiments, coupling the lead frame 30 to the substrate may include an adhesive or other material to securely couple the lead frame to the substrate. In other embodiments, the lead frame may be coupled to the substrate by ultrasonic welding or other methods for coupling metal parts. As shown, the shortened leads 34 are not soldered to the substrate (partially because they are too short to reach / contact the substrate).

[0061] The method also includes forming a molding compound around five or more sides of the substrate. Fig.12, a molding compound 40 is formed on a substrate 38 and around a portion of a plurality of leads 32 extending from a lead frame 30. The shortened leads 34 do not extend into the molding compound 40. In various embodiments, a molding compound is formed around the substrate and the leads using a transfer molding technique. In some embodiments, the cavity design used for a lead frame with shortened leads in a transfer molding technique may be the same as the cavity design used for a method including a fully filled lead frame. Using the same cavity design may increase design flexibility so that when a method for selectively removing leads is used, no molding compound flows out of the cavity. Using the same cavity design for two embodiments of the method for forming a power module may reduce the cost of manufacturing a power module as described herein. In various embodiments, the molding compound or encapsulant may include an epoxy, a resin, a polymer, any combination thereof, or any other material for protecting semiconductor components.

[0062] In some embodiments, the cylinder can be inserted into the mounting hole and then the substrate and lead frame can be encapsulated with a molding compound. Figure 1 As shown, the cylinder may be left in the mounting hole to form a support for the mounting hole. In other embodiments, the cylinder may be removed after encapsulation or after lead trimming. In other embodiments, the cylinder may be replaced with a different cylinder or material that will remain in the semiconductor package. In some embodiments, the cylinder may be formed of a metal or may be formed of a non-electroactive / non-chemically reactive material, such as any material disclosed herein.

[0063] The method also includes trimming the lead frame from the power module. Fig.13 , shows a power module 42 after trimming the lead frame by cutting through those leads (the second group of leads) that were not shortened or previously formed by selective trimming. In various embodiments, the lead frame can be trimmed by cutting the tie bars between the frame and the leads encapsulated in the molding material. Trimming the lead frame also includes removing the shortened leads from around the power module. The power module 42 formed by this embodiment can be described as having selectively removed leads.

[0064] As shown, the power module 42 includes a molding compound 40 formed around a substrate. The substrate includes a first side and a second side. The substrate is coupled to a plurality of leads by solder, adhesive, ultrasonic welding, sintering, any combination thereof, or other methods for coupling metal parts. In various embodiments, the substrate may include: a direct bonded copper substrate (DBC) with a ceramic core, a direct bonded aluminum (DBA) substrate, an active metal brazing (AMB) substrate, an insulated metal substrate (IMS), an electroplated ceramic substrate, a high-layer count (HLC) printed wiring board (PWB), a low temperature co-fired ceramic (LTCC) substrate, a high temperature co-fired ceramic (HTCC) substrate, a polymer-coated conductive plate, or any other substrate described herein.

[0065] refer to Fig.14 , a top view of another embodiment of a power module 44 with selectively removed leads is shown. In this view, a screw hole or mounting hole 46 is shown as being located at the center of the substrate. In other embodiments, the mounting hole may be located at another location in the substrate. A molding compound is shown surrounding the substrate 50. The molding compound 48 may cover five sides of the substrate 50. As described above, in various illustrations, the molding compound covers a first side of the power module, thereby encapsulating the substrate, die, wire bonds, and leads. In some embodiments, the molding compound may include an epoxy, resin, or other material that can withstand high temperatures and high voltages.

[0066] refer to Fig.16 , a first side 52 of an embodiment of a power module 50 is shown. The package 50 includes a single mounting hole 54. The step width of the package is 3.2 mm. In various embodiments, the step width may be larger (such as) or smaller (such as a step width of 1.5 mm). The step width of 3.2 mm is designed to accommodate a plastic shell used in the process of installing the power module. In various embodiments, a stabilizing structure such as a plastic shell with a knob or protrusion (not shown) may be required to prevent the package from rotating about the first mounting hole 54 during installation. In some embodiments, the plastic shell may also reduce or prevent residual stress on a printed circuit board or other structure on which the power module is mounted. In this particular embodiment, 78 pins may be used.

[0067] refer to Fig.17 , a second side 58 of an embodiment of a power module 60 is shown. This embodiment includes a first mounting hole and a second mounting hole. The combination of two mounting holes 62 and 65 can help to make it easier to install the power module for some devices. In various embodiments, a plastic shell is used to facilitate installation of the power module. Where multiple mounting holes are used, the plastic shell may not include knobs or protrusions, which can reduce stress caused by knobs or protrusions in various embodiments. The step width of this module is 3.2 mm. In other embodiments, the step width may be 1.5 mm, or the step width may be larger, depending on the needs of the device.

[0068] Power modules can be used in a variety of applications, including: embedded computing, accelerator devices, controllers, processors, network processors and noise-sensitive applications. Other applications include mobile Internet devices, tablets and other single-cell lithium-powered devices. Personal navigation devices and consumer and in-vehicle infotainment devices can also use integrated power modules.

[0069] In various package embodiments, the plurality of leads may have a pitch of 3.2 mm.

[0070] In various package implementations, the leadframe may be coupled to the substrate by one of soldering or sintering.

[0071] In various embodiments, forming the encapsulant may include using a transfer molding process.

[0072] In various package embodiments, the encapsulant may include an epoxy, a resin, a polymer, or any combination thereof.

[0073] In various package implementations, the mounting holes may extend from a first side to a second side of the substrate.

[0074] In various package embodiments, the plurality of leads may have a pitch of 3.81 mm.

[0075] In various package implementations, the power module may include one or more dies mechanically and electrically coupled to the second side of the substrate.

[0076] In various embodiments, the package may include a substrate that is one of: a direct bonded copper substrate (DBC) with a ceramic core, a direct bonded aluminum (DBA) substrate, an active metal brazing (AMB) substrate, an insulated metal substrate (IMS), an electroplated ceramic substrate, a high layer count (HLC) printed wiring board (PWB), a low temperature co-fired ceramic (LTCC) substrate, a high temperature co-fired ceramic (HTCC) substrate, or a polymer-coated conductive plate.

[0077] Where reference is made in the above description to specific embodiments of the power module and to implementing components, sub-components, methods and sub-methods, it should be apparent that various modifications may be made without departing from the essence thereof, and that these embodiments, implementing components, sub-components, methods and sub-methods may be applied to other power modules.

Claims

1. A semiconductor package, comprising: a substrate comprising a first side and a second side; a plurality of leads coupled to the second side of the substrate; a molding compound, the molding compound included over a portion of five or more surfaces of the substrate; and A first opening extending from the first side of the substrate to an outer edge of the molding compound and having a cylindrical shape is configured to receive a coupling device configured to couple to one of a heat sink or a package support. 2 . The package of claim 1 , further comprising a standoff unit positioned around the first opening on the outer edge of the molding compound, wherein the standoff unit is configured to support the package against one of the heat sink or the package support. 3 . The package of claim 1 , further comprising a second opening, wherein the first opening and the second opening are evenly spaced within the package. 4 . The package of claim 1 , wherein each of the plurality of leads is an equal distance from two or more leads on one side of a lead frame including the plurality of leads.

5. A method for forming a semiconductor package, the method comprising: coupling a lead frame to a substrate having one or more mounting holes extending from a first side of the substrate to a second side of the substrate and having a cylindrical shape, wherein the lead frame has a plurality of leads extending from each of four sides of the lead frame; selectively trimming a first group of the plurality of leads; forming an enclosure around at least five surfaces of the substrate and a portion of each lead of a second group of the plurality of leads with one or more cylinders inserted through the one or more mounting holes in the substrate; as well as The lead frame is trimmed by trimming one or more of the plurality of leads to a predetermined length.

6. The method of claim 5, further comprising using a securing device to prevent the encapsulant from flowing into the one or more mounting holes in the substrate. 7 . The method of claim 6 , wherein the first group of the plurality of leads do not extend into the encapsulation and are completely removed with the lead frame during trimming of the lead frame.

8. A method of forming a semiconductor package, the method comprising: providing a base plate having a first side, a second side, and one or more mounting holes extending from the first side to the second side and having a cylindrical shape; coupling a lead frame having a plurality of leads to the substrate; selectively trimming a first group of the plurality of leads; encapsulating at least five surfaces of the substrate and a portion of each lead in a second group of the plurality of leads in a molding compound with one or more cylinders inserted through the one or more mounting holes in the substrate; and The lead frame is trimmed from the remaining plurality of leads. 9 . The method of claim 8 , wherein further the base plate comprises two mounting holes extending from the first side of the base plate to the second side of the base plate.

10. The method of claim 8, wherein the first group of the plurality of leads does not extend into a cavity included in a transfer molding process.

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