Discrete semiconductor device package with lead frame clip

Abstract

The invention relates to a discrete semiconductor device package with lead frame clips. A package includes a semiconductor die attached to a die attach pad by a first sinter bond. The package also includes a clip having a first end and a second end. The first end of the clip is attached to a device contact pad on the semiconductor die by a second sinter bond, and the second end of the clip is attached to a post of a lead by a joint. The package also includes a mold body that encapsulates the semiconductor die.

Description

Technical Field

[0001] This specification relates to packaging of semiconductor dies and integrated circuits. Background Art

[0002] A semiconductor package consists of a metal, plastic, glass, or ceramic housing that contains one or more semiconductor devices or integrated circuits. Individual components are manufactured on semiconductor wafers (usually silicon or silicon carbide wafers) before being cut into dies, tested, and packaged. The package provides a means of connecting the semiconductor device or integrated circuit to an external environment such as a printed circuit board via leads such as pads, balls, or pins; as well as protection against threats such as mechanical shock, chemical contamination, and light exposure. As the demand for high-performance integrated circuits continues to increase, improvements in packaging technology are needed to address performance and reliability issues. Summary of the invention

[0003] In a general aspect, a package includes a semiconductor die attached to a die attach pad by a first sintered bond and a clip having a first end and a second end. The first end of the clip is attached to a device contact pad on the semiconductor die by a second sintered bond, and the second end of the clip is attached to a post of a lead by a joint. The package also includes a mold body encapsulating the semiconductor die.

[0004] In a first aspect, the first sintered bond and the second sintered bond are low temperature silver based sintered bonds.

[0005] In a second aspect, the lead extends outside the mold body to form an external terminal of the package, wherein the second end of the clip is attached to the post of the lead.

[0006] In a third aspect, the device contact pad is a source contact pad, and wherein the external terminal is an external source terminal of the package.

[0007] In a fourth aspect, the device contact pad is a first device contact pad and the lead is a first lead, and the semiconductor die further comprises a second device contact pad connected to a post of a second lead by wire bonding.

[0008] In a fifth aspect, the wire bond is an aluminum wire bond.

[0009] In a sixth aspect, the second device contact pad is a gate contact pad, and the second lead extends outside the mold body to form an external gate terminal of the package.

[0010] In a seventh aspect, the semiconductor die includes a silicon carbide (SiC) power transistor.

[0011] In a general aspect, a package includes a semiconductor die attached to a die attach pad on a substrate. The semiconductor die includes a source contact pad, a gate contact pad, and a source sense pad. The package also includes a mold body encapsulating the semiconductor die and a clip connecting the source contact pad to a lead post of a lead forming an external terminal of the package. A first end of the clip is attached to the source contact pad by a sintered bond, and a second end of the clip is attached to the lead post by a fusion bond. The lead post is a lead end that extends outside the mold body to form an external source terminal of the package.

[0012] In a first aspect, the fusion bond is a silver sintered bond.

[0013] In a second aspect, the fusion bond is a welded joint.

[0014] In a third aspect, the gate contact pad and the source sense pad are connected by leads bonded to corresponding gate lead posts and corresponding source sense lead posts.

[0015] In a fourth aspect, the lead is an aluminum lead.

[0016] In a fifth aspect, the semiconductor die includes a silicon carbide (SiC) power transistor.

[0017] In general, a method includes sintering a semiconductor die to a die attach pad (DAP) in a lead frame structure, and connecting a source contact pad formed on the semiconductor die to a lead post of a lead with a clip. The method also includes encapsulating the semiconductor die in a mold body, wherein the leads extend from the mold body as external terminals of the package.

[0018] In a first aspect, sintering the semiconductor die to the DAP includes disposing a silver particle paste between the semiconductor die and the DAP; and applying pressure to the semiconductor die.

[0019] In a second aspect, connecting the source contact pad on the semiconductor die to a lead post of a lead with a clip includes sintering a first end of the clip to the source contact pad.

[0020] In a third aspect, sintering the first end of the clip to the source contact pad includes positioning a silver sinter preform on top of the first end of the clip to abut the source contact pad and apply pressure to a back side of the semiconductor die on which the source contact pad is formed.

[0021] In a fourth aspect, connecting a source contact pad formed on the semiconductor die to the lead post of the lead with the clip further comprises soldering a second end of the clip to the lead post of the lead.

[0022] In a fifth aspect, the semiconductor die includes a silicon carbide (SiC) power transistor.

[0023] The details of one or more implementations are set forth in the accompanying drawings and the description that follows. Other features will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A semiconductor device package is shown in cross-section.

[0025] Figure 2 An assembly of components of a semiconductor die package is shown in plan view at an intermediate stage of construction.

[0026] Figure 3 The engagement of one end of a metal clip with a lead post is schematically shown.

[0027] Figure 4 An exemplary wound substrate frame is shown.

[0028] Figure 5 Schematically showing sintering one end of a metal clip to a source contact pad in a fixture.

[0029] Figure 6 is a flow chart illustrating a method for preparing a leadframe unit having a semiconductor die sinter-bonded to a substrate.

[0030] 7A to 7F A leadframe unit is shown at various stages of a method of sinter bonding a semiconductor die to a die attach pad (DAP) in a leadframe structure.

[0031] Figure 8 is a flow chart showing a method of preparing a metal clip for sintering bonding using a sintering preform.

[0032] 9A to 9H Various stages of a process for placing an Ag sintered preform on a metal clip for sinter bonding are shown.

[0033] Fig.10 It shows the combination Figure 6 and Figure 8 The method results in a flow chart of a method for manufacturing a discrete semiconductor die package.

[0034] FIG. 11A to FIG. 11D Shown in Fig.10 The steps of the method are shown in the following figure with some steps encapsulating the assembly view.

[0035] FIG. 12A to FIG. 12F Shown in Fig.10 The method wraps the component's view under some additional steps.

[0036] Fig.13 is a flow chart illustrating an exemplary method for packaging a semiconductor die. DETAILED DESCRIPTION

[0037] A semiconductor device package includes a semiconductor die mounted on a lead frame structure that includes leads that provide external electrical connections (external to the package) for a single device or integrated circuit in the semiconductor die. The semiconductor die may be mounted on a paddle or flag in the lead frame structure. In addition, the device contact pads on the semiconductor die are electrically connected to corresponding leads in the leads using wire bonding (e.g., aluminum wire bonding). The leads extending to the outside of the package body form external terminal pins that can be used to mount the package on a printed circuit board or terminal strips. In an exemplary embodiment, the terminal pins may be mounted in a socket or soldered to a printed circuit board (PCB) or terminal strips.

[0038] There are a variety of package types used in various applications. Some are defined by international, national or industry standards, while others are specific to a single manufacturer. The number and configuration of the external terminal pins of a package type may be defined by international, national or industry standards.

[0039] An exemplary semiconductor die package may include a discrete semiconductor device such as a power transistor, a silicon carbide (SiC) MOSFET, or another device.

[0040] In a power module package, a semiconductor die is attached to a DAP (die attach pad) on a lead frame, which may form an external terminal of the package. Leads are welded to connect contact pads (e.g., source contact pads, gate contact pads, and source sense contact pads) on the semiconductor die to a single lead post on the lead frame to form an external terminal of the package. Some regulations restrict chemicals and heavy metals in electronic components, solders, and materials. The present disclosure describes a power module package that complies with at least some regulatory directives. The power module packaging method disclosed herein avoids the use of leads (PB) and other restricted chemicals.

[0041] According to the principles of the present disclosure, in exemplary packaging implementations, a frit (e.g., a silver (Ag) frit, a silver-based frit) can be used to couple, bond, or attach two different components of a semiconductor die package to each other. In some implementations, two different components of a semiconductor die package can be bonded (e.g., welded) or fused together without adding any intermediate material (e.g., solder).

[0042] The disclosed power module package uses sintering (e.g., silver (Ag) sintering) to attach the semiconductor die to the DAP in the lead frame structure. In addition, Ag sintering can be used to connect one end of a metal clip to the die and the second end of the metal clip to the lead post in the lead frame. In some specific implementations, the second end of the metal clip can be welded to the lead post.

[0043] In accordance with principles of the present disclosure, in an exemplary packaging implementation, a frit (eg, silver or a silver-based frit) may be used to couple, bond, or attach two different components of a semiconductor die package to one another.

[0044] During the sintering process, the sintering substance (e.g., Ag atoms) can diffuse into the two different components and hold the two different components together. Sintering improves the reliability of attaching (bonding) the two components together by avoiding the use of an intermediate bonding layer (e.g., solder or adhesive) that may crack during temperature cycling, for example. In an exemplary implementation, for example, an Ag-based sinter can be used to attach a semiconductor die to a die attach pad (DAP) in a lead frame structure.

[0045] In an exemplary implementation, a copper clip may be used to connect a source contact pad on a semiconductor die to a source lead contact stud in a leadframe structure to form an external source lead of a package.

[0046] In an exemplary implementation, a first end of the copper clip may be sintered to a source contact pad on the semiconductor die. In some exemplary implementations, a second end of the copper clip is soldered to a source lead contact post in a lead frame structure. In some other exemplary implementations, a second end of the copper clip is sintered to a source lead contact post in a lead frame structure.

[0047] Figure 1 A cross-sectional view of a package 10 is shown, including components coupled together by sintering (eg, Ag sintering, etc.) or soldering, in accordance with the principles of the present disclosure.

[0048] In the package 10 (e.g., a discrete semiconductor device package), a semiconductor die 130 (e.g., a 1200V SiC MOSFET, with a maximum current of about 600A and a power of about 500KW) is encapsulated in a mold 140 made of epoxy resin or molding compound. The semiconductor die 130 may be disposed on a die attach pad (DAP) 120 on a surface S of a flag or pad 102 of a lead frame structure in the package. The semiconductor die 130 may be attached to the DAP 120 by sinter bonding (e.g., Ag sinter 131). The lead 3 may include a lead portion 3-0 that forms an external terminal of the package. The lead 3 may be connected to a device contact pad (e.g., a source contact pad, not shown) on the semiconductor die 130 by a metal clip 160.

[0049] The metal clip 160 may include a first end 160 - 1 attached to a source contact pad on the semiconductor die and a second end 160 - 2 attached to a lead 3 forming an external terminal of the package.

[0050] In at least exemplary implementations, a first end 160-1 of the metal clip 160 may be attached to a source contact pad on the semiconductor die by a sintered bond (e.g., Ag sinter 132). In at least exemplary implementations, a second end 160-2 of the metal clip 160 may be attached to a lead post 3-0 of a lead 3 forming an external terminal of the package by a fusion bond 161. In some exemplary implementations, the fusion bond 161 may be, for example, a joint (e.g., a welded joint) formed by bonding (e.g., welding) the second end 160-2 of the metal clip 160 to the lead post 3-0 of the lead 3. In some exemplary implementations, the fusion bond 161 may be formed by an Ag sinter between the second end 160-2 of the metal clip 160 and the lead post 3-0 of the lead 3.

[0051] In some exemplary implementations, the lead portion 3-0 of the lead 3 forming the external terminal of the package may extend in the y direction and generally lie in the xy plane. The first end 160-1 attached to the source contact pad on the semiconductor die may generally lie in another xy plane (parallel to the device contact pad on the semiconductor die 130) that is offset from the xy plane of the lead portion 3-0 by a distance Z1. The clip 160 may be bent to continuously transition the distance Z1 from the xy plane of the second end 160-2 to the xy plane of the first end 160-1.

[0052] The lead 3 may have a thickness TE. According to the industry standard of the device package (e.g., for a 1200V SiC MOSFET, a maximum current of about 600A, a power of about 500KW, a device package), the thickness TE may correspond to the thickness requirement for coupling the external terminal formed by the lead 3 to the printed circuit board. For example, for the industry standard D2PAK, the thickness TE may be about 0.5 mm.

[0053] In an exemplary implementation, the flag or pad 102 can be coupled to a header portion (e.g., header 110) disposed above the flag (e.g., in the y-direction). Header 110 can be electrically connected to DAP 120 through the substrate and can be a drain or ground terminal for a semiconductor die in the package.

[0054] Figure 2 A semiconductor die package (eg, Fig.12F1 and 1 . An assembly of component 250 at an intermediate stage of construction of a discrete semiconductor die package 1200 is shown. According to the principles of the present disclosure, a semiconductor die package may include components coupled together by sintering (e.g., Ag sintering, etc.) and the semiconductor die may be connected to lead posts in a leadframe structure using metal clips soldered to the lead posts.

[0055] like Figure 2 As shown, the assembly of component 250 includes a lead frame structure 200A and another lead frame structure 200B. The lead frame structure 200A and the lead frame structure 200B can be made of copper or other metals, for example. The lead frame structure 200A coupled to the corresponding lead frame structure 200B may be referred to herein as a lead frame unit (e.g., Figure 4 lead frame unit 40).

[0056] The leadframe structure 200A may include a substrate 100 (eg, a copper block) attached to a header 110 . A die attach pad such as a DAP 122 may be formed on a surface S of the substrate 100 .

[0057] The leadframe structure 200B may include a plurality of metal strips or leads (e.g., lead 1, lead 2, lead 3, lead 4, lead 5, lead 6, and lead 7). An annular ring or collar 210 having, for example, a width CW (in the x-direction) and a height CH (in the y-direction) may hold portions (e.g., lead portion 1-0, lead portion 2-0, lead portion 3-0, lead portion 4-0, lead portion 5-0, lead portion 6-0, and lead portion 7-0, etc.) of the plurality of metal strips (e.g., leads 1-7). These lead portions may extend from a top portion CT of the collar 210 (in the y-direction) to a bottom portion CB of the collar 210 and may generally lie in a plane (e.g., an xy plane) of the collar 210. These lead portions may be precursors to external terminals (e.g., gate terminals, source sense terminals, and source terminals) of a package using the leadframe structure 200B.

[0058] Lead portions including lead portion 1-0, lead portion 2-0, lead portion 3-0, lead portion 4-0, lead portion 5-0, lead portion 6-0, and lead portion 7-0 may extend above the top CT of collar 210 to form lead posts, such as gate lead post 170G, source sensing lead post 170SS, and source lead post 170S. Source lead post 170S may be common to lead portion 3-0, lead portion 4-0, lead portion 5-0, lead portion 6-0, and lead portion 7-0. In an exemplary implementation, gate lead post 170G, source sensing lead post 170SS, and source lead post 170S may be coated or plated with nickel (Ni).

[0059] like Figure 2As shown, in the assembly of the semiconductor die package, the semiconductor die 130 may be placed on the DAP 122 on the substrate 100 of the leadframe structure 200A. The semiconductor die 130 may be attached to the DAP 122 of the leadframe structure 200A via an Ag frit (not visible) disposed between the die and the DAP.

[0060] The surface of the semiconductor die may expose source contact pad 132S, gate contact pad 132G, and source sense contact pad 132SS. In an exemplary implementation, gate contact pad 132G and source sense contact pad 132SS may be electrically connected to gate lead post 170G and source sense lead post 170SS (on lead frame structure 200B) respectively through wire bonding 172. Wire bonding 172 may be aluminum or copper wire.

[0061] Furthermore, in an exemplary implementation, the source contact pad 132S can be electrically connected to the source lead post 170S via a metal clip 160 (e.g., a copper clip). In an exemplary implementation, the first end 160-1 of the metal clip 160 can be attached to the source contact pad 132S on the semiconductor die via an Ag sinter (not visible).

[0062] In an exemplary embodiment, the second end 160-2 of the metal clip 160 may be fused to the metal clip 161 ( Figure 1 ) is attached to the source lead post 170S. Since the source lead post 170S is common to lead portion 3-0, lead portion 4-0, lead portion 5-0, lead portion 6-0, and lead portion 7-0, any one of leads 3-7 can be used as an external source terminal of the package. In some specific implementations, as shown in FIG. Figure 1 As discussed, the fused bond 161 may be, for example, a joint (eg, a welded joint) formed by bonding (eg, welding) the second end 160 - 2 of the metal clip 160 to the lead post 3 - 0 of the lead 3 .

[0063] Figure 3 The schematic diagram shows that the second end 160-2 of the metal clip 160 is welded to the source lead post 170S. Figure 3 As shown, the welding tip 310 of the welding tool 300 may be used to apply pressure and temperature to the second end 160 - 2 of the metal clip 160 in contact with the source lead post 170S to weld the second end 160 - 2 to the source lead post 170S.

[0064] In an exemplary implementation, for an automated (or partially automated) assembly line configuration of a package (e.g., a device package), an array of leadframe structures including an array of leadframe structures 200A coupled to leadframe structures 200B may be provided on a wound substrate frame (e.g., provided to an assembly line tool). The leadframe structure 200A coupled to the leadframe structure 200B may be held in the wound substrate frame between a pair of spaced-apart runner strips having reference holes. The wound substrate frame including the leadframe structures may be manufactured by electroplating copper traces and pads (on a printed circuit board (PCB) sheet). Each

[0065] Figure 4 An exemplary wound substrate frame 400 is shown that includes an array of leadframe structures 200A (eg, array 40A) and an array of leadframe structures 200B (eg, array 42A).

[0066] The lead frame structure 200A coupled to the corresponding lead frame structure 200B may be referred to herein as a lead frame unit 40. Each wound substrate frame 400 may, for example, include a plurality of lead frame units 40. In an exemplary implementation, each wound substrate frame 400 may, for example, include ten to thirty lead frame units (e.g., sixteen lead frame units).

[0067] The wound substrate frame 400 may include spaced apart perforated runner strips. The runner strips may include reference holes 410 to help position and align the wound substrate frame 400 with, for example, assembly line processing tools (e.g., singulation tools, die pick and place tools, material injection tools, etc.).

[0068] Reference again Figure 2 As previously mentioned, the first end 160 - 1 of the metal clip 160 may be attached to the source contact pad 132S on the semiconductor die 130 via Ag sinter.

[0069] Figure 5 It is schematically shown that one end of the metal clip 160 is silver-based sintered to the source contact pad 132S in the clamp 500 .

[0070] The second end 160-2 of the metal clip 160 is welded to the source lead post 170S ( Figure 3 ), the lead frame structure may be flipped over and placed in a support tray 50 in a fixture 500. The support tray 50 may include a horizontal shelf 52A separated from another horizontal shelf 52B by a groove or slot 52T. The horizontal shelf 52A and the horizontal shelf 52B may have a vertical height difference d corresponding to, for example, a distance Z1 from the xy plane of the second end 160-2 of the metal clip 160 to the xy plane of the first end 160-1 (e.g., Figure 1 The support tray 50 may further include a third horizontal shelf 52C that is adjacent to the horizontal shelf 52A but has a lower height (eg, height h) than the horizontal shelf.

[0071] like Figure 5 As shown, the lead frame structure can be turned over and placed in the support tray 50. The lead frame structure 200B can be formed by winding the substrate frame (eg, winding the substrate frame 400, Figure 4 ) is connected to the lead frame structure 200B. In the tray 50, the lead frame structure 200B can be horizontally positioned on the horizontal shelf 52B. The portion of the metal clip 160 outside the xy plane of the lead frame structure 200B can be accommodated in the groove or trench 52T. In addition, the lead frame structure 200A can be horizontally positioned on the horizontal shelf 52A, wherein the back side of the substrate 100 faces upward (in the z direction) in a horizontal position. In this position, the first end 160-1 of the metal clip 160 can be located on the third horizontal shelf 52C facing the source contact pad 132S on the substrate 100. The silver sintered material (e.g., the sintered material 160S) can be disposed between the source contact pad 132S and the first end 160-1 of the metal clip 160 on the third horizontal shelf 52C.

[0072] The fixture 500 may include a press or weight 50W, which may be applied to the back side of the substrate 100 (eg, Figure 5 ), to apply pressure to the combination of the source contact pad 132S, the sintering material 160S and the first end 160-1 of the metal clip 160, thereby sintering the metal clip 160 to the source contact pad 132S.

[0073] Figure 6 , Figure 8 and Fig.10 Methods are shown that can be used to prepare various components or implement various stages in the manufacture of semiconductor die packages.

[0074] Figure 6 is a flow chart illustrating a method 600 for preparing a leadframe unit of a semiconductor die having a DAP that is Ag sinter bonded to a substrate.

[0075] Method 600 includes preparing a lead frame unit for receiving a semiconductor die (610). The lead frame unit may include a first lead frame structure including a DAP formed on a substrate and a second lead frame structure including a plurality of leads configured to function as one of a plurality of external terminals of a package. Method 600 may be implemented in an automated (or partially automated) assembly line for constructing semiconductor die packages. The lead frame unit may be provided as a wound substrate frame (e.g., wound substrate frame 400, Figure 4 ). In the wound substrate frame, the first lead frame structure and the second lead frame structure in the lead frame unit can be joined together by a bracket or a strip connector. In the completed single die package, the first lead frame structure and the second lead frame structure are connected by a metal clip (e.g., metal clip 160, Figure 2 )connect.

[0076] Preparing a leadframe unit for receiving a semiconductor die may include silver plating a DAP formed on a substrate in a first leadframe structure.

[0077] The method 600 also includes disposing a sintering (eg, Ag sintering) material on the DAP (620). The Ag sintering material (eg, Ag particle slurry) may be disposed as an Ag sintering tape applied on the DAP.

[0078] The method 600 also includes placing a single semiconductor die on the sintered material in the DAP (630). The placement of the single semiconductor die may be performed by a die pick and place operation of a tool in a manufacturing assembly line.

[0079] The method 600 also includes placing a protective tape on the DAP covering the single semiconductor die (640), and applying pressure to the top of the semiconductor die through the protective tape (650). The pressure applied to the top of the semiconductor die can attach the semiconductor die to the DAP through high pressure sintering. The high pressure can be applied by a stamping tool in a manufacturing assembly line. The protective tape can protect the semiconductor from damage caused by contact with the stamping tool.

[0080] 7A to 7E Views of a leadframe unit are shown at various stages of the process of Ag sinter bonding a semiconductor die to a DAP in a leadframe structure (eg, leadframe 200 ).

[0081] Fig. 7A An exemplary lead frame 200 (eg Figure 2 250 is also shown). The leadframe unit includes a leadframe structure 200A and a leadframe structure 200B. The leadframe structure 200A includes a substrate 100 on which a DAP (e.g., DAP 122) is formed. In an exemplary implementation, in a first stage of construction, DAP 122 is plated or coated with silver. Fig. 7A , silver plating is indicated as Ag plating 124 .

[0082] In the next stage of construction, Figure 7B As shown, an Ag sintered tape 126 may be applied to the DAP 122 .

[0083] In the next stage of construction, Figure 7CAs shown, a semiconductor die (eg, semiconductor die 130) may be placed on Ag sintered tape 126 in DAP 122. Semiconductor die 130 may be placed in the DAP in a pick and place operation in an assembly line.

[0084] In the next stage of construction, Fig.7D As shown, a protective tape may be disposed over substrate 100 to cover a semiconductor die (eg, semiconductor die 130 ) placed on Ag sintered tape 126 in DAP 122 .

[0085] In the next stage of construction, Fig. 7E As shown, a press or a weight (e.g., weight 702) may be disposed on the protective tape 128 above the substrate 100. The press or the weight may apply pressure to the semiconductor die 130 through the protective tape 128 and sinter-bond the semiconductor die (e.g., semiconductor die 130) placed on the Ag sintering tape 126 to the DAP 122. The protective tape 128 may protect the semiconductor die 130 from damage due to direct contact with the weight 702. After the sintering bonding is completed, the press or the weight (e.g., weight 702) may be removed to produce a lead frame unit having a semiconductor die sinter-bonded to the DAP on the substrate by Ag. For example, in Figure 7F 1. Leadframe 200 having semiconductor die 130 sinter-bonded to DAP 122 by Ag is shown in FIG.

[0086] Figure 8 is a flow chart illustrating a method 800 of preparing a metal clip (eg, the metal clip 160 ) using an Ag sintered preform for sinter bonding the metal clip to a lead frame 200 .

[0087] The method 800 may include holding a plurality of metal clips (e.g., metal clips 160) on a clip holding tray. The plurality of metal clips (e.g., metal clips 160) in the clip holding tray may be processed simultaneously on an assembly line. In an exemplary implementation, the plurality of metal clips (or portions of the metal clips) may be initially silver plated.

[0088] The tray may include a row of grooves in a bottom plate of the tray and a raised portion or table along the row of grooves. The method 800 may include placing a protective tape on a top surface of the raised portion or table along a row of grooves in a bottom plate holding the tray (810), and placing a plurality of metal clips in the tray such that a first end (e.g., first end 160-1 of metal clip 160) rests horizontally on the raised portion or table (820).

[0089] In this case, placing the metal clip in the tray may include placing the second end portion (e.g., the second end 160-2 of the metal clip 160) in a groove in the bottom plate of the tray, while the first end portion (e.g., the first end 160-1 of the metal clip 160) rests horizontally on a raised portion or table along the row of grooves.

[0090] The method 800 also includes placing an Ag sintered preform on top of the first end portion of each of the metal clips (830). A pick and place tool can be used to place the Ag sintered preform on top of each of the first end portions (e.g., the first end 160-1 of the metal clip 160) that rests horizontally on the raised portion or mesa along the row of grooves.

[0091] 9A to 9E Various stages of a process for placing an Ag sintered preform on a metal clip for sinter bonding are shown.

[0092] Fig.9A is an illustration of an exemplary clip holding tray 900 that may be used to hold a plurality of metal clips for processing. Fig. 9B An exploded view of a portion of the clip holding tray 900 is shown, and Fig. 9C A cross-sectional view of a clip holding tray 900 is shown. Clip holding tray 900 may include a raised seat or terrace 96 next to an array of grooves or channels (e.g., array 92A of grooves 92) cut into a bottom plate (e.g., bottom plate 94) of the tray. Raised seat or terrace 96 may include two adjacent strips or shelves (e.g., seat 96A and seat 96B) at different heights (in the z-direction) above bottom plate 94. As shown in FIG. Fig. 9C As shown, seat 96A may be at a height h1 above bottom plate 94, and seat 96B may be at a height h above seat 94A.

[0093] Prior to placing a plurality of metal clips (e.g., metal clip 160) in clip holding tray 900, protective film 97 is disposed on at least a portion of raised seats or mesas 96 in clip holding tray 900. For example, Fig.9D A protective film 97 is shown disposed on the seat 96A of the raised portion or platform 96 in the clip retaining tray 900 .

[0094] Fig.9E and Fig.9FA plurality of metal clips 160 are shown disposed in the tray such that a first end portion (e.g., a first end 160-1 of the metal clip 160) rests horizontally on a protective film 97 disposed on a seat 96A in a raised seat or table 96. A second end portion (e.g., a second end 160-2 of the metal clip 160) rests in a groove (e.g., groove 92) in the tray floor.

[0095] Figure 9G and Figure 9H An Ag sintered preform 99 is shown disposed on a first end portion (eg, first end 160 - 1 of a metal clip 160 ) resting horizontally on a protective film 97 disposed on a seat 96A of a raised seat or mesa 96 .

[0096] Fig.10 is a flow chart illustrating a method 1000 that combines the results of method 600 and method 800 to fabricate a discrete semiconductor die package.

[0097] Method 1000 includes placing a die-attached lead frame in a clip holding tray holding a plurality of metal clips (1010). The die-attached lead frame may include a plurality of lead frame units, wherein each lead frame unit includes a semiconductor die Ag-sintered to a DAP. The semiconductor die may have a top surface exposing a source contact pad, a gate contact pad, and a source sense contact pad. A plurality of metal clips in a clip holding tray holding a plurality of metal clips may have an Ag-sintered preform disposed on top of each of the first end portions of the metal clips, which rest on a raised mesa in the clip holding tray. Placing the die-attached lead frame in a clip holding tray holding a plurality of metal clips 1010 may include placing the die-attached lead frame such that the Ag-sintered preform disposed on top of each of the first end portions is aligned and abutted with a source contact pad of a corresponding semiconductor die (which is Ag-sintered to a DAP).

[0098] The method 1000 also includes applying pressure to the back side of the die attached lead frame held in the clip holding tray (1020). A press or other pressure tool can be used to apply (sintering) pressure to the back side of the semiconductor die on which the source contact pad is formed. The applied pressure can sinter the Ag sintered preform (Ag sintered preform 99, Figure 9G and Figure 9H ) is sintered to a source contact pad on the semiconductor die.

[0099] The method 1000 also includes removing the lead frame from the clip holding tray and inverting the lead frame (1030), and welding the second end portion of the metal clip to the lead post of the lead frame (1040).

[0100] The method 1000 also includes wire bonding a gate contact pad and a source sense contact pad on the semiconductor die to a single lead post 1050. Al wires or Cu wires may be used to wire bond the gate and source sense pads.

[0101] The method 1000 also includes wire bonding a gate contact pad and a source sense contact pad on the semiconductor die to a single lead post 1050. Al wires or Cu wires may be used to wire bond the gate and source sense pads.

[0102] The method 1000 may include packaging the semiconductor die in a mold body after connecting the leads to corresponding device contact pads. The method 1000 may also include removing (e.g., cutting) the annular collar to individually separate the leads attached to the annular collar. The method 1000 may also include shaping the lead portions extending outside the mold body into external terminals of a discrete semiconductor device package.

[0103] The method 1000 also includes encapsulating the semiconductor die in a molding compound ( 1060 ), and trimming and forming a molded package assembly ( 1070 ).

[0104] The method 1000 may include electroplating (eg, tinning) the leads prior to trimming and forming the molded package assembly.

[0105] FIG. 11A to FIG. 11D and FIG. 12A to FIG. 12F Various views of the package assembly are shown at various steps of method 1000 .

[0106] Fig.11A A plan view of a wound substrate frame 1100 disposed in a clip holding tray (eg, clip holding tray 900 ) is shown.

[0107] The wound substrate frame 1100 may include a plurality of lead frame units 40. For example, using the above method 600, each lead frame unit may include a semiconductor die attached to a DAP of a substrate (e.g., substrate 100). The semiconductor die and the DAP on the front side of the substrate are connected to each other. Fig.11A The clip holding tray 900 may include a plurality of metal clips 160 having an Ag sintered preform on top of a first end 160-1 of each of the metal clips. The Ag sintered preform and the first end portion are disposed on the top of the first end 160-1 of each of the metal clips. Fig.11A Not visible in the view shown. A metal clip may be made using, for example, the method 800 described above, by sintering the preform with Ag.

[0108] The wound substrate frame 1100 may be positioned in the clip holding tray 900 such that source contact pads (eg, source contact pads 132S) in the semiconductor die attached to the DAP are aligned with and in contact with the Ag sintered preform on the corresponding metal clip 160 .

[0109] Fig. 11B An exploded view of a portion of a wound substrate frame disposed in a clip holding tray is shown, and Fig. 11C A cross-sectional view of a wound substrate frame disposed in a clip holding tray is shown.

[0110] Fig.11D An exploded view of a portion of a wound substrate frame is shown (eg Fig. 11B ), where a press or weight 50W is applied to the back side of the substrate 100 to apply pressure to the combination of the source contact pad 132S, the Ag sintered preform 99, and the first end 160-1 of the metal clip 160. The applied pressure can sinter-bond the metal clip 160 to the source contact pad 132S at a low temperature.

[0111] Fig. 12A A plan view of the frame unit 40 is shown after the wound substrate frame 1100 is removed from the clip holding tray and inverted. Fig. 12B A view of the frame unit 40 is shown after the second end 160-2 of the metal clip 160 is welded to the lead post (eg, the source lead post 170S), as previously described with reference to FIG. Figure 3 discussed.

[0112] also, Fig. 12C A plan view of the frame unit 40 is shown after forming wire bonds between the device contact pads (e.g., gate contact pad 132G and source sense pad 132SS) connected to lead posts (e.g., gate lead posts 170G and source sense lead posts 170SS) via wire bonds 172. The wire bonds 172 may be, for example, aluminum wire bonds.

[0113] also, Fig.12D A plan view of the frame unit 40 is shown, wherein the wire bonds 172 ( Fig. 12C )After that, the semiconductor die is encapsulated in a mold body 1202 made of epoxy molding compound (EMC).

[0114] also, Fig.12E FIG. 1 shows a plan view of the frame unit 40 after portions of the lead frame structures 200A and 200B outside of the mold body 1202 have been tinned. Fig.12E Indicated by the arrow marked 1210.

[0115] Fig.12F Shown in Fig.12E A three-dimensional perspective view of the resulting discrete semiconductor die package 1200 after trimming and forming operations of the molded body.

[0116] The trimming and forming operation includes removing (eg, cutting) the annular collar (eg, by singulation) to individually separate the annular collars (eg, collar 210, Figure 2 ) and forming the leads extending outside the mold body into external terminals of the discrete semiconductor device package.

[0117] The Ag sintering material used in the aforementioned method may be, for example, a Ag particle slurry. In addition, in addition to applying pressure to the component, the Ag sintering step described above may include a low-temperature sintering process. In an exemplary implementation, the low-temperature sintering may include a sintering temperature, for example, in the range of about 200° C. to about 300° C. (e.g., 250° C.). The sintering process may result in the sintering material (e.g., Ag substance) being fully diffused into the sintered component.

[0118] In an exemplary implementation, the package (e.g., discrete semiconductor die package 1200) may be of a type intended for surface mounting on a circuit board, with the external terminals being shaped to lie flat on the surface of the circuit board (e.g., PCB). Fig.12F In the example shown, the lead portions are bent so that their end portions lie flat in the xy plane along the bottom of the mold body 1202 .

[0119] Fig.13 13 is a flow chart illustrating an exemplary method for packaging a semiconductor die. The semiconductor die may include a silicon carbide (SiC) power transistor.

[0120] Method 1300 includes sintering a semiconductor die to a die attach pad (DAP) in a lead frame structure (1310), connecting a source contact pad formed on the semiconductor die to a lead post of a lead with a clip (1320), and packaging the semiconductor die in a mold body, wherein the leads extend from the mold body as external terminals of the package (1330).

[0121] In method 1300 , sintering the semiconductor die to the DAP includes disposing a silver particle paste between the semiconductor die and the DAP and applying pressure on the semiconductor die.

[0122] In method 1300, connecting a source contact pad on a semiconductor die to a lead post of a lead with a clip includes sintering a first end of the clip to the source contact pad. Sintering the first end of the clip to the source contact pad includes placing a silver sinter preform on top of the first end of the clip to abut against the source contact pad and applying pressure to a back side of the semiconductor die on which the source contact pad is formed.

[0123] Additionally, in method 1300 , connecting a source contact pad formed on the semiconductor die to a lead post of a lead with the clip includes soldering a second end of the clip to the lead post of the lead.

[0124] It should be understood that in the foregoing description, when an element such as a layer, region, substrate or part is mentioned as being on another element, connected to another element, electrically connected to another element, coupled to another element, or electrically coupled to another element, the element may be directly on another element, connected to or coupled to another element, or one or more intermediate elements may be present. On the contrary, when an element is mentioned as being directly on another element or layer, directly connected to another element or layer, or directly coupled to another element or layer, there is no intermediate element or layer. Although the term directly on, directly connected to, or directly coupled to may not be used in the entire specific embodiment, the element shown as being directly on an element, directly connected, or directly coupled can be mentioned in this manner. The claims of the present application (if any) may be revised to narrate the example relationships described in the specification or shown in the accompanying drawings.

[0125] As used in this specification and claims, singular forms may include plural forms unless the context dictates otherwise. Spatially relative terms (e.g., above, above, above, below, below, below, below, etc.) are intended to encompass different orientations of the device in use or operation, in addition to the orientations shown in the drawings. In some implementations, the relative terms above and below may include vertically above and vertically below, respectively. In some implementations, the term adjacent can include lateral adjacent or horizontal adjacent.

[0126] Some implementations may be implemented using various semiconductor processing and / or packaging technologies. Some implementations may be implemented using various types of semiconductor processing technologies associated with semiconductor substrates, including but not limited to, for example, silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), etc.

[0127] Although certain features of the described implementations have been described as described herein, those skilled in the art will now appreciate that many modifications, alternatives, variations, and equivalents are contemplated. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations that fall within the scope of the implementations. It should be understood that these modifications and variations are presented only by way of example and not limitation, and that various changes in form and detail may be made. In addition to mutually exclusive combinations, any portion of the apparatus and / or method described herein may be combined in any combination. The implementations described herein may include various combinations and / or sub-combinations of the functions, components, and / or features of the different implementations described.

Claims

1. A package, comprising: a semiconductor die attached to the die attach pad by a first sinter bond; a clip having a first end and a second end, the first end being attached to a device contact pad on the semiconductor die by a second sintered bond and the second end being attached to a post of a lead by a tab; and A mold body encapsulates the semiconductor die. 2 . The package of claim 1 , wherein the first sintered bond and the second sintered bond are low temperature silver-based sintered bonds.

3. The package of claim 1 , wherein the second end of the clip is attached to the lead of the post of the lead extending outside the mold body to form an external terminal of the package, wherein the device contact pad is a source contact pad, and wherein the external terminal is an external source terminal of the package.

4. The package of claim 1 , wherein the device contact pad is a first device contact pad and the lead is a first lead, and wherein the semiconductor die further comprises a second device contact pad connected to a post of a second lead by wire bonding, wherein the second device contact pad is a gate contact pad, and wherein the second lead extends outside the mold body to form an external gate terminal of the package.

5. A package, comprising: a semiconductor die attached to a die attach pad on the substrate, the semiconductor die having a source contact pad, a gate contact pad, and a source sense pad; A mold body, wherein the mold body encapsulates the semiconductor die; and A clip connects the source contact pad to a lead post of a lead to form an external terminal of the package, a first end of the clip being attached to the source contact pad by sinter bonding, and a second end of the clip being attached to the lead post by fusion bonding, the lead post being a lead end extending outside the mold body to form an external source terminal of the package. The package of claim 5 , wherein the fusion bond is one of a silver sintered bond and a solder joint. 7 . The package of claim 5 , wherein the gate contact pad and the source sense pad are connected by wires bonded to corresponding gate lead posts and corresponding source sense lead posts.

8. A method comprising: sintering a semiconductor die to a die attach pad DAP in a lead frame structure; connecting a source contact pad formed on the semiconductor die to a lead post of a lead using a clip; as well as The semiconductor die is packaged in a mold body, wherein the leads extend from the mold body as external terminals of the package.

9. The method of claim 8, wherein sintering the semiconductor die to the DAP comprises: disposing a silver particle paste between the semiconductor die and the DAP; and applying pressure to the semiconductor die, and wherein connecting the source contact pad on the semiconductor die to a lead post of a lead with a clip comprises sintering a first end of the clip to the source contact pad, and wherein sintering the first end of the clip to the source contact pad comprises: placing a silver sintered preform on top of the first end of the clip to abut against the source contact pad; as well as Pressure is applied to the back side of the semiconductor die on which the source contact pad is formed.

10. The method of claim 8, wherein connecting a source contact pad formed on the semiconductor die to the lead post of the lead with the clip further comprises soldering a second end of the clip to the lead post of the lead.

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