Mould forming power module

Abstract

A molded power module (100) includes a thermally conductive and electrically insulating substrate (120) and at least one power semiconductor die (110), where the at least one power semiconductor die (110) has a top surface (110a) and a bottom surface (110b) opposite the top surface (110a). The bottom surface (110b) is attached to the substrate (120). The power semiconductor die (110) includes one or more terminal pads (111, 112, 113), where the one or more terminal pads (111, 112, 113) are formed on the top surface (110a) for electrically connecting the power semiconductor die. The module (100) comprises a molding compound (140), where the molding compound (140) at least partially encapsulates the at least one power semiconductor die. The mold-forming compound has an upper main surface (140a) and a lower main surface (140b) facing the upper main surface (140a). The upper main surface (140a) faces the top surface (110a) of the power semiconductor die (110). One or more contact holes (150a, 150c) penetrate the molding compound (140) from the upper main face (140a) to respective terminal pads (111) on the top face (110a) of the power semiconductor die (110). Each contact hole (150a, 150c) is formed with an undercut profile (151). The undercut profile enables a contact element (130a, 130c) to be unidirectionally inserted into the contact hole for electrical contact with the corresponding terminal pad (111).

Description

Technical Field

[0001] The present invention relates to the technical field of panel-level packaging of mold-formed high-power modules. Specifically, the present invention relates to a mold-formed power module having at least one semiconductor die. Background Art

[0002] The scaling of production formats can increase productivity and improve economic efficiency. Similar to front-end device technologies, packaging technologies also exhibit this trend. In logic or information and communication technology (ICT) applications (such as mobile communication chip sets or automotive radar chip sets), panel-level packaging technologies such as chip embedding / embedded component packaging (CE / ECP) and fan-out panel level packaging (FO-PLP) are currently replacing traditional strip mold-formed small-size QFP or BGA packages. Since panel-level packaging has potential economic benefits compared to the standard sequential module packaging concept, panel-level packaging is also attractive for power modules. To industrialize the panel manufacturing of mold-formed high-power modules, a flexible and scalable power terminal structure that can be integrated into the panel-level packaging process is needed, but such a structure does not currently exist. Summary of the Invention

[0003] The present invention provides a solution for a mold-formed power module, the power module employing a flexible and scalable power terminal structure that can be manufactured by a panel-level packaging process.

[0004] The above and other objectives and other purposes are achieved by the features of the independent claims. Other implementations are apparent in the dependent claims, the description, and the drawings.

[0005] The present invention provides a solution for how to manufacture the power terminals of high-power modules that can be produced at the panel level. This solution can produce multiple contacts at once through parallel processing or batch processing. Therefore, productivity is increased by increasing throughput, raising the production format from single modules to panel format, and by spreading tooling costs across different products. This solution can be applied to single-sided cooling modules with power terminals in the form of pins on the upper surface and various other power modules. The pin layout is fully customizable.

[0006] The embodiments described in the present invention may include:

[0007] - A single-sided cooling mold-formed power module having a mold body, with an open contact hole from the outer surface to the metal plating at the substrate or die.

[0008] - The chip contacts of the mold-formed power module include blind holes with locking features.

[0009] - The contact holes can have an undercut profile formed by a consumable material that retains its shape during mold forming and can be completely removed after mold forming.

[0010] - The blind holes with an undercut profile can belong to a locking function (not achievable by prior art drilling / laser / mold forming), which allows the power pins to be inserted unidirectionally into the contact holes and keeps the power pins in place to perform their functions during the product lifetime.

[0011] - The contact element consists of 3 segments: (a) an outer segment protruding from the upper surface; (b) an intermediate segment with locking features in the x / y dimension; (c) a contact segment with elasticity and compliance in the z dimension for maintaining and constraining the contact force applied to the pads of the die / substrate during the product lifetime.

[0012] - For different current-carrying capacities, there can be different types of contact elements.

[0013] - The locking function can be achieved in different ways.

[0014] - The insertion can be performed in different ways during production.

[0015] - In the case of direct contact with the chip surface, a metal plating reinforcement may be required on the chip pads to protect the chip from damage and contamination.

[0016] The embodiments described in the present invention can be applied to power modules with a single-sided cooling interface and a power range in the tens of kW range. The present invention can also be used in applications where the power terminals and signal terminals are located on the upper main surface and are directly connected to the power PCB or busbar. Exemplary applications are power modules for photovoltaic (PV) inverters, data center power conversion, and industrial-grade applications of power modules.

[0017] To describe the present invention in detail, the following terms, abbreviations, and symbols are used:

[0018] FOWLP

[0019] FO-WLP Fan-out wafer level packaging

[0020] FOPLP

[0021] FO-PLP Fan-out panel level packaging

[0022] RDL Redistribution layer

[0023] PCB Printed Circuit Board

[0024] SSC Single sided cooling

[0025] DSC Double(or dual)sided cooling

[0026] CE Chip Embedding

[0027] ECP Embedded Component Package or Packaging

[0028] QFP Quad flat pack

[0029] BGA Ball grid array

[0030] ICT Information&communication technology

[0031] The panel-level packaging and fan-out panel-level packaging in the present invention refer to the general concept of using RDL metal plating equipment in the PCB industry to improve the production format of fan-out wafer-level package (FO-WLP) to the PCB panel format of 24"×18" (600mm×450mm), with the goal of achieving the economic benefits of mass production. Equivalent to FO-WLP, "fan-out" in FO-PLP means that the package can be larger than the die, and the RDL of the board-level interface extends beyond the projection area of the chip. It also means that multiple chips can be in one package, and these chips must be rearranged or reconfigured in key process steps.

[0032] In the present invention, the laminated chip embedding and embedded component encapsulation refer to the practice of embedding a chip into a PCB core board and a prepreg laminate sheet and implementing the RDL metal plating using the PCB process. Although panel-level packaging more commonly includes the use of moldable materials, chip embedding or laminated chip embedding generally does not include materials that are not supplied as sheets and cannot be processed in a PCB laminator.

[0033] The strip mold forming in the present invention refers to the mold forming using the manufacturing format of a typical lead frame. The typical size range is 70mm / 90mm×270mm / 300mm.

[0034] The panel mold forming in the present invention refers to the mold forming using the panel production format. Due to the lack of large-area equipment (excessive closing force), this does not include transfer mold forming equipment. Panel mold forming generally refers to compression mold forming with a liquid mold forming compound and the corresponding equipment, or the combined use of a mold forming sheet and a laminator. It generally does not include packaging materials with a fiberglass matrix. The mold forming compound is usually filled with glass or ceramic type particles.

[0035] The power terminal in the present invention refers to the pin, bolt, or nut-type metal feature of a power module, which has mechanical stability, can support a current of more than 100A, and provides isolation / clearance for a voltage of more than 100V.

[0036] The chip embedding or embedded component packaging (CE / ECP) in the present invention refers to a packaging technology, that is, embedding a bare die usually with a Cu metal plating into a PCB material and connecting it to the Cu wiring on the package through electroplated micro-vias.

[0037] According to a first aspect, the present invention relates to a molded power module, comprising: a thermally conductive and electrically insulating substrate; at least one power semiconductor die, wherein the at least one power semiconductor die has a top surface and a bottom surface opposite the top surface, the bottom surface being attached to the substrate, and the at least one power semiconductor die includes one or more terminal pads formed on the top surface for electrically connecting the at least one power semiconductor die; a molding compound, wherein the molding compound at least partially encapsulates the at least one power semiconductor die, the molding compound having an upper major surface and a lower major surface opposite the upper major surface, the upper major surface facing the top surface of the at least one power semiconductor die; one or more contact holes, wherein the one or more contact holes penetrate from the upper major surface of the molding compound through the molding compound to corresponding terminal pads on the top surface of the at least one power semiconductor die; wherein each contact hole is formed with an undercut profile that enables a contact element to be inserted unidirectionally into the contact hole for electrical contact with the corresponding terminal pad.

[0038] Such a molded power module provides a flexible and scalable power terminal structure that can be easily manufactured by a panel-level packaging process. The one or more contact holes can be produced in one pass by parallel processing or batch processing. Applying such a molded power module can increase productivity by increasing throughput, raising the production format from individual modules to panel format, and by spreading tooling costs across different products. The molded power module can be used as a single-sided cooling module with power terminals in the form of pins on the upper surface. The pin layout of the molded power module is fully customizable.

[0039] The undercut profile described in the present invention is a profile formed by cutting away material from the bottom surface of an object to leave a protruding overhang.

[0040] The undercut or undercut profile of a contact hole is any depression or protrusion in the contact hole that prevents a contact element from exiting the contact hole when it is moved into the contact hole. For example, the purpose of the undercut (or undercut profile) is to lock the contact element into the contact hole. This is also referred to as the undercut function.

[0041] In an exemplary implementation of the molded power module, in addition to enabling unidirectional insertion of the contact element, the undercut profile also enables the contact element to be locked in the contact hole. Locking means that the contact element is fixed in the contact hole and cannot be released from the contact hole without damaging the contact element or the contact hole. For example, locking means that the contact element is fixed at the insertion position in the contact hole. Thus, the molded power module ensures that the contact element is fixed within the contact hole.

[0042] In an exemplary implementation of the molded power module, the substrate includes: an upper metallization layer, a lower metallization layer opposite the upper metallization layer, and an insulating layer between the upper metallization layer and the lower metallization layer, wherein the bottom surface of the at least one power semiconductor die is attached to the upper metallization layer; the substrate includes one or more substrate pads, wherein the one or more substrate pads are formed on the upper metallization layer for electrically connecting the upper metallization layer; the molded power module includes: one or more other contact holes, wherein the one or more other contact holes penetrate from the upper main surface of the molded compound to the corresponding substrate pads on the upper metallization layer of the substrate; wherein each other contact hole is formed with an undercut profile that enables a contact element to be inserted unidirectionally into the other contact hole for electrical contact with the corresponding substrate pad.

[0043] This provides the following advantages: Multiple contact holes can be formed, which can contact the terminal pads of the power semiconductor die or directly contact the substrate pads on the substrate (for example, contact at the traces on the substrate under the power semiconductor die). Therefore, the molded power module can be flexibly designed according to the position where the contact holes can be formed, the geometry of the contact holes, and the type of the contact holes, etc.

[0044] In an exemplary implementation of the molded power module, each contact hole includes a first axial segment having a first width and an adjacent second axial segment, wherein the second axial segment has a second width greater than the first width; wherein the first axial segment is formed at the upper main surface of the molded compound. Thus, the larger width of the second axial segment provides a locking feature through which the contact element can be locked in the contact hole.

[0045] The different axial segments of the contact hole are not limited to a circular axial geometry. They can also have any other axial geometry or a combination of different axial geometries, such as square, rectangular, ellipsoidal, regular polygonal, or symmetric axial segments of any other shape. For a circular axial geometry, the widths of these segments can be referenced to the corresponding diameters of the axial segments.

[0046] In an exemplary implementation of the molded power module, a first contact hole among the contact holes is configured to receive a signal pin; a second contact hole among the contact holes is configured to receive a power pin; a first width of a first axial segment of the second contact hole is greater than a first width of a first axial segment of the first contact hole; and / or a second width of a second axial segment of the second contact hole is greater than a second width of a second axial segment of the first contact hole. Thus, different types of pins can be efficiently contacted. For the power pin, a large current will flow, so a larger width is provided for the power pin. For the signal pin, only a small current will flow, so for the signal pin, a smaller width is sufficient.

[0047] In an exemplary implementation of the molded power module, a undercut profile of the contact hole includes one of the following: a stepped or multi-stepped sidewall profile; an inwardly inclined sidewall profile; a concave or convex sidewall profile; a hyperbolic sidewall profile. Thus, flexible design options can be adopted.

[0048] In an exemplary implementation of the molded power module, the molded power module includes: one or more contact elements in electrical contact with the corresponding terminal pad, wherein the one or more contact elements are attached to the corresponding terminal pad through the contact hole above the corresponding terminal pad. Thus, a flexible and scalable power terminal structure can be provided. The contact hole can be attached to the corresponding terminal pad during a panel-level packaging process or after the production of the molded power module.

[0049] In an exemplary implementation of the molded power module, each contact element includes: an external segment protruding from an upper main surface of the molded compound; a contact segment contacting the corresponding terminal pad; an intermediate segment between the external segment and the contact segment, wherein the intermediate segment is configured to lock the contact element in the contact hole above the corresponding terminal pad.

[0050] The contact segment of the corresponding contact element can be shaped to be compliant to limit mechanical forces, thereby protecting the metal pad (terminal pad) and maintaining sufficient clamping force throughout the life of the module. The molded power module provides efficient electrical and mechanical contact characteristics.

[0051] In an exemplary implementation of the molded power module, each contact element includes one or more spring elements, wherein the one or more spring elements engage with an undercut of the contact hole to clamp the contact element in the contact hole above the corresponding terminal pad.

[0052] This enables the contact element to be efficiently clamped in the contact hole.

[0053] In an exemplary implementation of the molded power module, each contact element includes one or more fixing elements, wherein the one or more fixing elements are joined to the upper main surface of the molding compound to clamp the contact element on the upper main surface of the molding compound. This enables the contact element to be efficiently clamped on the molding compound.

[0054] In an exemplary implementation of the molded power module, the one or more contact elements are made of metal. Specifically, metals with high electrical and thermal conductivity should be used, such as Cu, Ni, Cu:Fe, Ni:Fe, Cu:Be. The elastic properties of the metal can be enhanced by additives of alloys or metal composites, or by specific heat treatments. The contact element can be made of sheet metal by methods such as stamping, embossing, bending, forging, etc. The contact element can have a surface coating to enhance the electrical contact resistance and avoid surface oxidation.

[0055] This provides excellent electrical conductivity and mechanical stability.

[0056] In an exemplary implementation of the molded power module, the one or more contact elements attached to the corresponding terminal pads undergo plastic deformation compared to the initial shape of the one or more contact elements; the locking of the contact element is caused by the plastic deformation. Due to the plastic deformation, the contact element can be excellently locked in the contact hole. In other words, the contact point deforms during insertion through the shrinkage and flexure of the thin contact material to irreversibly clamp the contact element in the contact hole, thereby forming an arch or a sleeve.

[0057] In an exemplary implementation of the molded power module, the one or more contact elements attached to the corresponding terminal pads buckle compared to the initial shape of the one or more contact elements; the locking of the contact element is caused by the buckling of the contact element. Due to the buckling of the contact element, the contact element can be excellently locked in the contact hole. During insertion or in the last few micrometers of the insertion length, buckling can be induced by shrinking / touching the bottom of the contact hole. The locking function is caused by the buckling effect.

[0058] In an exemplary implementation of the molded power module, the one or more contact holes are at least partially filled with a metal layer. This means that the sidewalls of the contact holes and the semiconductor metal pads or substrate pads can be metallized. This provides excellent electrical conductivity of the contact point between the contact hole and the contact element.

[0059] In an exemplary implementation of the mold - formed power module, the one or more contact elements include connecting elements, wherein the connecting elements are configured to connect the one or more contact elements to each other before being inserted into the one or more contact holes, and the connecting elements are configured to separate after being inserted into the one or more contact holes. These connecting elements provide mechanical stability to the contact elements.

[0060] The connecting elements can be interconnected according to a predefined grid. The grid can be any regular or repeating pattern, but is not limited to such patterns. The grid can also be any type of regular or irregular connection, for example, connected by connecting rods or other elements. Since it is possible to attempt to reuse the stamping tool plates, the grid configuration helps to minimize tooling costs. This element connection facilitates mass production. The connected elements (e.g., connected by connecting rods) can be separated again by a cutting tool after insertion.

[0061] In an exemplary implementation of the mold - formed power module, the one or more contact elements include an electro - deposited metal layer, wherein the electro - deposited metal layer is formed after the contact element is inserted to increase the electrical contact area with the corresponding terminal pad, so as to reduce the resistance and / or thermal resistance and protect the contact area through metal sealing. The electro - deposited metal layer here refers to an additional post - insertion deposited metal layer. This post - insertion implemented metal plating is designed to increase the electrical contact area by closing gaps. This can increase the electrical contact area with the corresponding terminal pad, thereby reducing the resistance and / or thermal resistance and protecting the contact area through metal sealing.

[0062] In an exemplary implementation of the mold - formed power module, the mold - formed power module includes a single - side cool (SSC) power module. This enables the efficient provision of SSC power modules through panel - level packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Other embodiments of the present invention will be described in conjunction with the following drawings, in which:

[0064] Figure 1 A schematic cross - section of the mold - formed power module 100 provided by the present invention is shown;

[0065] Figure 2 Shows Figure 1 A schematic cross - section of the shown mold - formed power module 100, wherein no contact element is inserted into the contact hole;

[0066] Figure 3 a in Figure 3 b in Figure 3a) in and after insertion ( Figure 3 b) in Figure 3 , the locking features of power pin 301, signal pin 302 and alternative signal pin 303 achieved by the barb spring metal contact element;

[0067] Figure 4 a in and Figure 4 b in Figure 4 shows different schematic cross-sections of the molded power module 100, showing the locking features of power pin 401 and signal pin 402 achieved by the plastic deformation of contact holes 410a, 410b, 411a, 411b of different shapes during insertion ( Figure 4 a) in and after insertion ( Figure 4 b) in Figure 4 , the locking features of power pin 401 and signal pin 402 achieved by the plastic deformation of contact holes 410a, 410b, 411a, 411b of different shapes;

[0068] Figure 5 a in Figure 5 shows a schematic cross-section of the molded power module 100, showing the locking features achieved by the plastic deformation of power pins 501 of different shapes after insertion;

[0069] Figure 5 b in Figure 5 shows a top view of an example of a structured metal sheet 510 for inserting signal pins and power pins. Detailed Description

[0070] In the following detailed description, reference is made to the accompanying drawings which form a part of this specification, and in which are shown by way of illustration specific aspects of the invention that may be practiced. It is to be understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the invention. Accordingly, the following detailed description should not be taken in a limiting sense, and the scope of the invention is defined by the appended claims.

[0071] It should be understood that the notes related to the described method are also applicable to the corresponding device or system for performing the method, and vice versa. For example, if a specific method step is described, the corresponding device may include units for performing the described method step, even if such units are not elaborated or illustrated in detail in the figures. Additionally, it should be understood that unless otherwise explicitly stated, the features of the various exemplary aspects described herein may be combined with each other.

[0072] Figure 1 Shows a schematic cross-section of the molded power module 100 provided by the present invention. The upper figures 100a and 100b represent enlarged views of the contact areas of the first type of contact element 100a (e.g., signal pin) and the second type of contact element 100b (e.g., power pin).

[0073] The molded power module 100 includes: a thermally conductive and electrically insulating substrate 120; at least one power semiconductor die 110; a molding compound 140; and one or more contact holes 150a, 150c.

[0074] At least one power semiconductor die 110 has a top surface 110a and a bottom surface 110b opposite to the top surface 110a. The bottom surface 110b is attached to the substrate 120. At least one power semiconductor die 110 includes one or more terminal pads 111, 112, 113, wherein the one or more terminal pads 111, 112, 113 are formed on the top surface 110a for electrically connecting at least one power semiconductor die 110.

[0075] The molding compound 140 at least partially encapsulates at least one power semiconductor die. The molding compound 140 has an upper major surface 140a and a lower major surface 140b opposite to the upper major surface 140a. As Figure 1 shown, the upper major surface 140a faces the top surface 110a of at least one power semiconductor die 110.

[0076] One or more contact holes 150a, 150c penetrate from the upper major surface 140a of the molding compound 140 through the molding compound 140 to the corresponding terminal pads 111 on the top surface 110a of at least one power semiconductor die 110.

[0077] Each contact hole 150a, 150c is formed with an undercut profile 151. The undercut profile 151 enables contact elements 130a, 130c to be inserted unidirectionally into the contact holes 150a, 150c for electrical contact with the corresponding terminal pads 111.

[0078] The undercut profile 151 is formed by cutting away the material of the bottom surface of an object (here, the inner cavity of the molding compound 140) to leave a protruding overhanging portion, as Figure 1 shown, particularly as shown in the enlarged views 100a and 100b.

[0079] As can be seen from Figure 1 the undercut profile 151 of the contact holes 150a, 150c is a depression or protrusion in the contact holes 150a, 150c that prevents the contact elements 130a, 130c from exiting the contact holes 150a, 150c when moving into the contact holes 150a, 150c. The purpose of the undercut profile 151 is to lock the contact elements 130a, 130c into the contact holes 150a, 150c. This is also referred to as the undercut function.

[0080] In addition to enabling the contact elements 130a, 130c to be inserted unidirectionally, the undercut profile 151 also enables the contact elements 130a, 130c to be locked in the corresponding contact holes 150a, 150c.

[0081] The locking here means that the contact elements 130a and 130c are fixed in the contact holes 150a and 150c and cannot be released from the contact holes 150a and 150c without damaging the contact elements 130a and 130c or the contact holes 150a and 150c. The locking means the insertion positions where the contact elements 130a and 130c are fixed in the contact holes 150a and 150c.

[0082] The substrate 120 includes: an upper metallization layer 121, a lower metallization layer 123 opposite to the upper metallization layer 121, and an insulating layer 122 between the upper metallization layer 121 and the lower metallization layer 123. It should be understood that other metallization layers and / or insulating layers may be included in the substrate. The bottom surface 110b of at least one power semiconductor die 110 is attached to the upper metallization layer 121.

[0083] The substrate 120 may include one or more substrate pads 124 and 125, where the one or more substrate pads 124 and 125 are formed on the upper metallization layer 121 for electrically connecting the upper metallization layer 121. One or more substrate pads 124 may be used for electrically connecting signal pins. One or more substrate pads 125 may be used for electrically connecting power pins. The size of the substrate pad 125 may be larger than the size of the substrate pad 124.

[0084] The molded power module 100 may include one or more other contact holes 150b and 150d, where the one or more other contact holes 150b and 150d penetrate through the upper main surface 140a of the molding compound 140 to the corresponding substrate pads 124 and 125 on the upper metallization layer 121 of the substrate 120. One or more other contact holes 150b may be designed to accommodate the corresponding contact elements 130b of signal pins. One or more other contact holes 150d may be designed to accommodate the corresponding contact elements 130d of power pins.

[0085] Each of the other contact holes 150b and 150d may be formed with an undercut profile 151, which enables the corresponding contact elements 130b and 130d to be inserted into the other contact holes 150b and 150d unidirectionally for electrical contact with the corresponding substrate pads 124 and 125.

[0086] Each of the contact holes 150a, 150c, 150b, and 150d may include a first axial segment 153 having a first width and an adjacent second axial segment 154, where the second axial segment 154 has a second width greater than the first width, for example, as shown in the scaled view 100a. The first axial segment 153 may be formed at the upper main surface 140a of the molding compound 140.

[0087] As described above, the different axial segments of the contact holes 150a, 150b, 150c, 150d are not limited to a circular axial geometry. They can also have any other axial geometry or a combination of different axial geometries, for example, square, rectangular, ellipsoidal, regular polygonal, or symmetric axial segments of any other shape.

[0088] For a circular axial geometry, the width of these segments can be referenced to the corresponding diameter of the axial segment.

[0089] From Figure 1 It can be seen that the first contact hole 150a can be used to accommodate signal pins; the second contact hole 150c can be used to accommodate power pins.

[0090] The first width of the first axial segment 153 of the second contact hole 150c can be greater than the first width of the first axial segment 153 of the first contact hole 150a.

[0091] The second width of the second axial segment 154 of the second contact hole 150c can be greater than the second width of the second axial segment 154 of the first contact hole 150a.

[0092] The undercut profile 151 can be implemented based on different shapes. For example, the undercut profiles 151 of the contact holes 150a, 150c can include: stepped or multi-stepped sidewall profiles; inwardly inclined sidewall profiles; concave or convex sidewall profiles; hyperbolic sidewall profiles or various other profile types.

[0093] One or more contact elements 130a, 130c for making electrical contact with the corresponding terminal pads 111 can be attached to the corresponding terminal pads 111 through the contact holes 150a, 150c above the corresponding terminal pads 111.

[0094] In Figure 1 Figure, the molded power module 100 is shown as having contact elements 130a, 130b, 130c inserted into the contact holes 150a, 150b, 150c. However, the molded power module 100 can also not have the contact elements 130a, 130b, 130c inserted into the contact holes 150a, 150b, 150c, as Figure 2 shown.

[0095] Each contact element 130a, 130c can include: an external segment 131 protruding from the upper main surface 140a of the molded compound 140, as Figure 1 shown; a contact segment 133 contacting the corresponding terminal pad 111; an intermediate segment 132 between the external segment 131 and the contact segment 133. The intermediate segment 132 is used to lock the contact elements 130a, 130c in the contact holes 150a, 150c above the corresponding terminal pads 111.

[0096] As described above, the contact segments of the respective contact elements 130a, 130b, 130c, 130d can be shaped to be compliant to limit mechanical forces, thereby protecting the metal pads (terminal pads) and maintaining sufficient clamping force throughout the life of the module.

[0097] Each of the contact elements 130a, 130c can include one or more spring elements 134 which, for example, as shown in the scaled view 100b, engage undercuts of the contact holes 150a, 150c to clamp the contact elements 130a, 130c in the contact holes 150a, 150c above the respective terminal pads 111.

[0098] Each of the contact elements 130a, 130c can include one or more fixing elements 135 which, for example, as shown in the scaled view 100b, engage the upper main surface 140a of the mold compound 140 to clamp the contact elements 130a, 130c on the upper main surface 140a of the mold compound 140.

[0099] One or more of the contact elements 130a, 130c can be made of metal.

[0100] One or more of the contact elements 130a, 130c attached to the respective terminal pads 111 can undergo plastic deformation compared to the initial shape of the one or more of the contact elements 130a, 130c, for example, as described below in connection with Figure 4 and Figure 5 described. Locking of the contact elements 130a, 130c can be caused by plastic deformation. In other words, the contacts deform during insertion by shrinking and flexing of the thin contact material to clamp the contact elements in the contact holes.

[0101] One or more of the contact elements 130a, 130c attached to the respective terminal pads 111 can buckle compared to the initial shape of the one or more of the contact elements 130a, 130c, for example, as described below in connection with Figure 4 and Figure 5 described. Locking of the contact elements 130a, 130c can be caused by buckling of the contact elements. Buckling can be initiated during insertion or in the last few microns of the insertion length by shrinking / touching the bottom of the contact hole. The locking function is caused by the buckling action.

[0102] The contact holes 150a, 150c can be at least partially filled with a metal layer. This means that the sidewalls of the contact holes and the semiconductor metal pads or substrate pads can be metallized. This can improve the contact between the contact holes 150a, 150c and the respective contact elements 130a, 130c.

[0103] One or more contact elements 130a, 130c may include connection elements, e.g., connection element 510 as shown, for connecting one or more contact elements 130a, 130c to each other before insertion into one or more contact holes 150a, 150c. The connection elements are for separation after insertion into one or more contact holes 150a, 150c. Figure 5 The connection elements may be interconnected according to a predefined grid. The grid may be any regular or repeating pattern, but is not limited to such patterns. The grid may also be any type of regular or irregular connection, e.g., connected by connecting rods or other elements. Such connection elements facilitate mass production. The connected elements (e.g., connected by connecting rods) may be separated again by a cutting tool after insertion.

[0104] Since the stamping tool plates can be attempted to be reused, the grid configuration helps to minimize tooling costs.

[0105] One or more contact elements 130a, 130c may include an electrodeposited metal layer, wherein the electrodeposited metal layer is formed after insertion of the contact element to increase the electrical contact area with the corresponding terminal pad 111 in order to reduce resistance and / or thermal resistance and protect the contact area by metal sealing. The electrodeposited metal layer herein refers to an additional post-insertion deposited metal layer. This post-insertion achieved metal plating is intended to increase the electrical contact area by closing gaps.

[0106] In one example, the molded power module 100 may include a single-sided cooling power module.

[0107] The molded power module 100 can be efficiently produced at the panel level. Multiple contacts between contact elements 130a, 130b, 130c, 130d and corresponding contact holes 150a, 150b, 150c, 150d can be produced at once by parallel processing or batch processing. For example, the molded power module can be used as a single-sided cooling module with power terminals in the form of pins on the upper surface. The pin layout is fully customizable.

[0108] The main features of such a single-sided cooling molded power module 100 can be summarized as follows.

[0109] The single-sided cooling molded power module 100 having a mold body 140 has open contact holes 150a, 150b, 150c from the outer surface to the metal plating of the substrate 120 or the die 110.

[0110]

[0111] ​The contact holes 150a, 150b, 150c, 150d have an undercut profile 151 formed of a consumable material that retains its shape during mold forming and can be completely removed after mold forming.

[0112] The undercut profile 151 is a feature as part of the locking function (not achievable by prior art drilling / laser / mold forming), which enables the power pins to be inserted unidirectionally into the contact holes 150a, 150b, 150c, 150d and holds the power pins in place to serve their purpose during the product life.

[0113] The contact elements 130a, 130b, 130c, 130d can include three segments: (a) an external segment 131 protruding from the upper surface; (b) an intermediate segment 132 with locking features in the x / y dimension; (c) a contact segment 133 that is elastic and compliant in the z dimension for maintaining and constraining the contact force applied to the pads of the die / substrate during the product life.

[0114] For different current-carrying capabilities, there can be different types of contact elements 130a, 130b, 130c, 130d, as described in the following embodiments.

[0115] The locking function can be achieved in different ways, as described in the following embodiments.

[0116] The insertion can be performed in different ways during production, as described in the following embodiments.

[0117] In the case of direct contact with the chip surface, metal plating reinforcement may be required on the chip pads 111, 112, 113 to protect the chip 110 from damage and contamination.

[0118] Figure 2 is shown Figure 1 A schematic cross-section of the molded power module 100 is shown, where no contact element is inserted into the contact hole.

[0119] Figure 2 The shown molded power module 100 is the same as Figure 1 shown, but in contrast to Figure 1 no contact elements 130a, 130b, 130c are inserted into the contact holes 150a, 150b, 150c.

[0120] The contact elements 130a, 130b, 130c can be inserted into the contact holes 150a, 150b, 150c during panel-level packaging or after panel-level packaging, for example, when the molded power module 100 is applied on-site.

[0121] Figure 1 and Figure 2 The molded power module 100 shown represents a general design of such a molded power module, but other embodiments are described in the following figures, which represent variations that replace and change the function and insertion method of the locking mechanism during production.

[0122] Figure 3 a in Figure 3 and b in Figure 3 a) during insertion ( Figure 3 a) and after insertion (

[0123] Figure 3 a in Figure 3 and b in

[0124] This embodiment describes the elastic barb features of the contact elements 301, 302, 303 that snap into the support grooves of the contact holes during insertion. Different implementations are shown for the signal or low-power connections 302, 303 (middle and right figures) and the large-area contact element (left figure) with an array of dimples 301 for point contact with the pads of the die / substrate.

[0125] After insertion as shown in Figure 3 b, the contact elements 301, 302, 303 are clamped between the undercut steps 151 or grooves in the side walls of the upper section of the contact hole and the bottom metal plating 310 of the contact holes 150c, 150a.

[0126] Figure 4 a in Figure 4 and b in Figure 4 a) during insertion ( Figure 4 a) and after insertion (

[0127] Figure 4 a in Figure 4 and b in

[0128] Figure 4 a in shows that the contact elements can be inserted simultaneously from a pre-loaded carrier plate (e.g., the platen 420), which abuts against the panel (parallel processing, batch processing).

[0129] The contact holes can be the conical 410a for accommodating the power pins 401 or the conical 410b for accommodating the signal pins 402.

[0130] Alternatively, the contact holes can have grooves with non-conical sidewalls 411a for accommodating the power pins 401, or grooves with non-conical sidewalls 410b for accommodating the signal pins 402.

[0131] In the third embodiment ( Figure 4 not shown), the locking feature can be achieved by a buckling action triggered by touching the bottoms of the contact holes 150a, 150c.

[0132] Figure 5 a in shows a schematic cross-section of the molded power module 100, showing the locking feature achieved by plastic deformation of different-shaped power pins 501 after insertion.

[0133] The locking feature is caused by the plastic deformation of the contact segments 133 of the contact elements (e.g., the power pins 501) and the fixing elements 135.

[0134] In this implementation, the contact elements 501, 130c can include one or more fixing elements 135, where the one or more fixing elements 135 are engaged with the upper main surface 140a of the molded compound 140 to clamp the contact elements 501, 130c on the upper main surface 140a of the molded compound 140.

[0135] As described above in connection with Figure 4 the contact holes can have grooves with non-conical sidewalls 411a for accommodating the power pins 501.

[0136] In the seventh embodiment, the insertion of the power pins and signal pins can be performed through the structured metal sheet 510.

[0137] Figure 5 b in shows a top view of an example of the structured metal sheet 510 for inserting the signal pins and power pins. Specifically, Figure 5 b in shows the metal sheet 510 of the connecting elements connected together by connecting rods. Above the metal sheet 510 shown in Figure 5 b, a cross-section of the metal sheet 510 is shown, which can reveal the 3D structure formed by stamping / embossing of the metal sheet.

[0138] The structured metal sheet 510 can be used to insert contact elements simultaneously. The structured metal sheet 510 can form contact elements on the metal sheet 510 that can be connected to each other.

[0139] The contact elements can be connected by connecting rods and can be separated in subsequent steps after panel-level insertion. For panel-level insertion, a metal plate with grid holes to appropriately accommodate the outer portions of the contact elements can be used, and pressure can be uniformly applied using a typical laminator or the like.

[0140] In a fourth embodiment (not shown in the figures), the mold body 140 can have partially filled through-mold contact holes, for example, partially metallized contact holes. The metal plating can provide mechanical protection, corrosion protection, and contamination protection for the sensitive die surface or substrate surface at the bottom of the contact hole. The metal plating can be achieved by a standard PCB-type process for blind via metal plating, using a seed process and subsequently a process of electroplating or chemical metal deposition from a liquid. Importantly, according to the standard, these processes are available at the panel level.

[0141] The metal plating can also utilize the function of a sliding medium to directly insert the contact elements into the contact holes by pressing. The metal plating electrically connects the sidewalls of the contact holes to the substrate or chip metal plating at the bottom of the contact holes. The metal plating can form a cold weld connection with the contact elements during insertion.

[0142] Combined with an undercut step on the inner sidewall of the contact hole, a more reliable locking press-fit connection can be made.

[0143] In a fifth embodiment, a sixth embodiment, a seventh embodiment, and an eighth embodiment (not shown in the figures), the method of inserting contact elements during production can vary as follows.

[0144] In the fifth embodiment, the contact elements can be inserted one by one in sequence into the contact openings of the panel (sequential insertion, discrete insertion, serial process).

[0145] In the sixth embodiment, the contact elements can be inserted simultaneously from a pre-loaded carrier plate (e.g., Figure 4 the pressing plate 420 shown), and the pre-loaded carrier plate abuts against the panel (parallel processing, batch processing).

[0146] In the seventh embodiment, for example, the contact elements can be inserted simultaneously through the structured metal sheet 510 having contact elements connected together as described above.

[0147] After inserting the contact element, the contact element can be separated by a cutting process (e.g., laser cutting, sawing, etc.). Alternatively, after inserting the contact element, a subsequent electroplated reinforcing metal coating can be performed, e.g., to reinforce the dot-like electrical connection and improve the current-carrying capacity of the power terminal. After performing the reinforcing metal coating, the contact element can be separated by a cutting process (e.g., laser cutting, sawing, etc.).

[0148] The key points of the embodiments introduced in the present invention are summarized below.

[0149] By using a consumable material to form contact holes in the mold body of a single side cool (SSC) high-power module through mold forming, contact holes of any shape and inner wall profiles of any shape can be achieved.

[0150] An SSC power module is provided, which has a mold body with through-mold contact holes, and the contact holes have undercut sidewall profiles. This realizes the locking function of the corresponding metal pin contact elements.

[0151] An SSC power module is provided, which has a mold body with through-mold contact holes with or without partial metallization, and the contact holes have undercut sidewall profiles. This realizes the combination of the pressing and locking functions to enhance the reliability of the power terminal connection.

[0152] A high-power module with power pins and signal pins and corresponding contact holes is provided, and the power pins and signal pins have a locking insertion function. In this way, high-power modules with power terminals can be manufactured with high throughput in an economical manner.

[0153] Contact holes and contact elements that can be manufactured and integrated into a panel-level packaging production process are provided.

[0154] The inserted contact elements can be electroplated for reinforcement. This can improve the current-carrying capacity and reliability of the power terminals.

[0155] Although a particular feature or aspect of the present invention may have been disclosed only in connection with one of several implementations, such feature or aspect may be combined with one or more other features or aspects in other implementations, as long as it is desired or advantageous for any given or particular application. Additionally, to the extent that the terms "comprises," "has," "includes," or other variants of these words are used in the detailed description or claims, such terms are similar to the term "comprising" in that they are intended to be inclusive. Similarly, the terms "exemplary," "for example" are merely meant to be examples, and not the best or optimal. The terms "coupled" and "connected" and derivatives thereof may have been used. It should be understood that these terms may be used to indicate that two elements cooperate or interact with each other, whether they are in direct physical contact or electrical contact, or whether they are not in direct contact with each other.

[0156] Although specific aspects have been illustrated and described herein, those of ordinary skill in the art will appreciate that many alternative and / or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present invention. This application is intended to cover any modifications or variations of the specific aspects discussed herein.

[0157] Although the elements in the following claims are recited in a particular order with corresponding labels, these elements need not be implemented in that particular order unless the claim recitation implies a specific order for implementing some or all of these elements.

[0158] In light of the above guidance, many alternatives, modifications, and variations will be apparent to those of skill in the art. Of course, those of skill in the art will readily recognize that there are numerous other applications of the present invention in addition to those described herein. Although the present invention has been described with reference to one or more specific embodiments, those of skill in the art recognize that many changes may be made thereto without departing from the scope of the present invention. Accordingly, it should be understood that the present invention may be practiced in a manner different from that specifically described herein, so long as it is within the scope of the appended claims and their equivalents.

Claims

1. A mold-formed power module (100), characterized in that, Comprising: A thermally and electrically insulating substrate (120); At least one power semiconductor die (110), wherein the at least one power semiconductor die (110) has a top surface (110a) and a bottom surface (110b) opposite to the top surface (110a), the bottom surface (110b) is attached to the substrate (120), and the at least one power semiconductor die (110) includes one or more terminal pads (111, 112, 113) formed on the top surface (110a) for electrically connecting the at least one power semiconductor die (110); A molding compound (140), wherein the molding compound (140) at least partially encapsulates the at least one power semiconductor die, and the molding compound has an upper major surface (140a) and a lower major surface (140b) opposite to the upper major surface (140a), and the upper major surface (140a) faces the top surface (110a) of the at least one power semiconductor die (110); One or more contact holes (150a, 150c), wherein the one or more contact holes (150a, 150c) penetrate from the upper major surface (140a) of the molding compound (140) through the molding compound (140) to a corresponding terminal pad (111) on the top surface (110a) of the at least one power semiconductor die (110); Wherein each contact hole (150a, 150c) is formed with an undercut profile (151), and the undercut profile (151) enables a contact element (130a, 130c) to be inserted unidirectionally into the contact hole (150a, 150c) for electrical contact with the corresponding terminal pad (111).

2. The molded power module (100) according to claim 1, characterized in that In addition to enabling the unidirectional insertion of the contact element (130a, 130c), the undercut profile (151) also enables the contact element (130a, 130c) to be locked in the contact hole (150a, 150c).

3. The molded power module (100) according to claim 1 or 2, characterized in that The substrate (120) includes: an upper metallization layer (121), a lower metallization layer (123) opposite to the upper metallization layer (121), and an insulating layer (122) between the upper metallization layer (121) and the lower metallization layer (123), wherein the bottom surface (110b) of the at least one power semiconductor die (110) is attached to the upper metallization layer (121); The substrate (120) includes one or more substrate pads (124), wherein the one or more substrate pads (124) are formed on the upper metallization layer (121) for electrically connecting the upper metallization layer (121); The molded power module (100) includes: One or more other contact holes (150b, 150d), wherein the one or more other contact holes (150b, 150d) penetrate the mold compound (140) from the upper main surface (140a) of the mold compound (140) to corresponding substrate pads (111) on the upper metallization layer (121) of the substrate (120); Wherein each other contact hole (150b, 150d) is formed with an undercut profile (151), and the undercut profile (151) enables a contact element (130b) to be inserted unidirectionally into the other contact hole (150b, 150d) for electrical contact with the corresponding substrate pad (124).

4. The molded power module (100) according to any one of the above claims, characterized in that Each contact hole (150a, 150c, 150b, 150d) includes a first axial segment (153) having a first width and an adjacent second axial segment (154), wherein the second axial segment (154) has a second width greater than the first width; Wherein the first axial segment is formed at the upper main surface (140a) of the mold compound (140).

5. The molded power module (100) according to any one of the above claims, characterized in that The first contact hole (150a) among the contact holes (150a, 150c, 150b, 150d) is for accommodating a signal pin; The second contact hole (150c) among the contact holes (150a, 150c, 150b, 150d) is for accommodating a power pin; The first width of the first axial segment (153) of the second contact hole (150c) is greater than the first width of the first axial segment (153) of the first contact hole (150a); and / or The second width of the second axial segment (154) of the second contact hole (150c) is greater than the second width of the second axial segment (154) of the first contact hole (150a).

6. The mold-formed power module (100) according to any one of the above claims, characterized in that, The undercut profile of the contact holes (150a, 150c) includes one of the following: A stepped or multi-stepped sidewall profile; An inwardly inclined sidewall profile; A concave or convex sidewall profile; A hyperbolic sidewall profile.

7. The die-formed power module (100) according to any one of the above claims, characterized in that, Comprising: One or more contact elements (130a, 130c) in electrical contact with the corresponding terminal pads (111), wherein the one or more contact elements (130a, 130c) are attached to the corresponding terminal pads (111) through the contact holes (150a, 150c) above the corresponding terminal pads (111).

8. The mold-formed power module (100) according to claim 7, characterized in that, Each contact element (130a, 130c) includes: An external segment (131) protruding from the upper main surface (140a) of the mold compound (140); A contact segment (133) contacting the corresponding terminal pad (111); An intermediate section (132) between the external section (131) and the contact section (133), wherein the intermediate section (132) is configured to lock the contact elements (130a, 130c) in the contact holes (150a, 150c) above the respective terminal pads (111).

9. The molded power module (100) according to claim 7 or 8, characterized in that Each contact element (130a, 130c) includes one or more spring elements (134), wherein the one or more spring elements (134) engage with an undercut of the contact holes (150a, 150c) to clamp the contact elements (130a, 130c) in the contact holes (150a, 150c) above the respective terminal pads (111).

10. The molded power module (100) according to any one of claims 7 to 9, characterized in that Each contact element (130a, 130c) includes one or more fixing elements (135), wherein the one or more fixing elements (135) engage with the upper main surface (140a) of the molded compound (140) to clamp the contact elements (130a, 130c) on the upper main surface (140a) of the molded compound (140).

11. The molded power module (100) according to any one of claims 7 to 10, characterized in that The one or more contact elements (130a, 130c) are made of metal.

12. The molded power module (100) according to any one of claims 7 to 11, characterized in that The one or more contact elements (130a, 130c) attached to the respective terminal pads (111) are plastically deformed as compared to the initial shape of the one or more contact elements (130a, 130c); The locking of the contact elements (130a, 130c) is caused by the plastic deformation.

13. The molded power module (100) according to any one of claims 7 to 12, characterized in that The one or more contact elements (130a, 130c) attached to the respective terminal pads (111) are buckled as compared to the initial shape of the one or more contact elements (130a, 130c); The locking of the contact elements (130a, 130c) is caused by the buckling of the contact elements.

14. The molded power module (100) according to any one of claims 7 to 13, characterized in that The one or more contact holes (150a, 150c) are at least partially filled with a metal layer.

15. The molded power module (100) according to any one of claims 7 to 14, characterized in that The one or more contact elements (130a, 130c) include connecting elements, wherein the connecting elements are used to connect the one or more contact elements (130a, 130c) to each other before being inserted into the one or more contact holes (150a, 150c). The connecting elements are used to separate after being inserted into the one or more contact holes (150a, 150c).

16. The molded power module (100) according to any one of claims 7 to 15, characterized in that The one or more contact elements (130a, 130c) include an electroplated metal layer, wherein the electroplated metal layer is formed after the contact elements are inserted to increase the electrical contact area with the corresponding terminal pads (111) so as to reduce the resistance and / or thermal resistance and protect the contact area by metal sealing.

17. The molded power module (100) according to any one of the above claims, characterized in that It includes a single side cool (SSC) power module.

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