Rigid-flexible PCB, power module including PCB, and method for manufacturing power module

Abstract

Embodiments of the present disclosure relate to a rigid-flexible PCB, a power module including the PCB, and a method of manufacturing the power module. The power module includes a rigid-flexible PCB separated from the resin molded case and including: a first PCB region having a stacked structure of stacked layers; a second PCB region, the second PCB region having the stack structure, the stack structure also being locally bounded at a first side by a top reinforcement element and at a second, opposite side by a bottom reinforcement element; and a third PCB region having the stacked structure without the top reinforcement element and the bottom reinforcement element. The top reinforcement element and the bottom reinforcement element extend at side surfaces of the molded case where the PCB is away from the molded case and are configured to locally increase stiffness of the PCB relative to areas of the PCB in which the top reinforcement element and the bottom reinforcement element are absent. A power module and a method of manufacturing a power module are also provided.

Description

Technical Field

[0001] The present disclosure relates to a rigid-flex printed circuit board (PCB), a power module, and a method for manufacturing a power module. Background Art

[0002] In the art, transfer molding module (TMM) power modules (PMs) for traction inverters have a rigid structure suitable for mass production, as they use overmolded housings commonly used in the mass production of discrete electronic components. Participants in the automotive field require product families configured to cover as wide a range of power and applications as possible. However, slightly different applications typically require costly modifications to the product outline assembly drawing (POA) for the TMM PM.

[0003] At the same time, PM manufacturers want to provide flexible but reliable open-market solutions in terms of the POA.

[0004] In the known art ( Figure 1 ), a rigid lead frame 1 is typically used to construct the TMM package. The rigid lead frame 1 is provided with a rigid connection (bus bar for electrical connection) and control pins (pin-shaped) 2 for control input connections. The control pins (pin-shaped) 2 are bent after the molding step. The rigid connection exits the encapsulation molding (resin plastic housing) for connection to the PCB. As described above, the packages manufactured in this way are suitable for mass production. However, many customers require components that cover as wide a range of applications as possible. Different applications typically require costly modifications to the production line.

[0005] The lead frame located between the two parts of the mold does not allow sustainable flexibility in maintaining the position of the control pins without modifying the lead frame itself and the molding tool.

[0006] There is a need to provide a solution that allows greater flexibility in possible applications without affecting the manufacturing / production line in terms of costly modifications to the manufacturing / production line. Summary of the Invention

[0007] A rigid-flex PCB, a power module, and a method for manufacturing a power module as defined in the appended claims are provided. Brief Description of the Drawings

[0008] Embodiments of the present disclosure will now be described, by way of non-limiting example only, with reference to the accompanying drawings:

[0009] Figure 1 Illustrates a TMM PM according to the known art;

[0010] Figure 2 Illustrates a power module according to the present disclosure;

[0011] Figure 3 illustrates Figure 2 the amplification part of the power module;

[0012] Figure 4 illustrates Figure 3 a cross-sectional view of the amplification part of the power module;

[0013] Figure 5 illustrates, according to one embodiment, Figure 4 a detailed cross-sectional view;

[0014] Figure 6 illustrates, according to an alternative embodiment, Figure 4 a detailed cross-sectional view; and

[0015] Figure 7A and Figure 7B illustrates a part of the manufacturing process for manufacturing Figure 2 a part of the power module. DETAILED DESCRIPTION

[0016] Figure 2 The power module 10 is illustrated in a three-axis system of orthogonal axes X, Y, Z. The power module 10 is represented in a top view in an intermediate manufacturing step and in the plane XY.

[0017] The power module 10 includes a rigid or solid part (or rigid / solid body) 12, and the rigid or solid part 12 includes one or more layers of a conductive material (such as copper (Cu)). The rigid part 12 is at least partially covered by a molded housing 14 of an electrical insulating material (for example, made of an epoxy resin, an epoxy-based molding compound, or other plastic material). The molded housing 14 is formed, for example, by resin transfer molding (RTM) in a manner known per se in the art. For better understanding of the present disclosure and to more clearly illustrate the top conductive layer of the rigid part 12 and other elements related to the present disclosure as disclosed, the molded housing 14 is illustrated as being open at selective portions.

[0018] The rigid part 12 is shaped such that a plurality of conductive paths 16 are defined for signal transmission.

[0019] According to one aspect of the present disclosure, the power module 10 further includes one or more PCBs 20 (FPCs, FPCs with stiffeners, rigid-flex PCBs, etc.), each PCB 20 including a flexible insulating support member over (or within) which one or more conductive tracks or traces extend. The PCB 20 is also referred to as the flexible PCB 20. For example, each PCB 20 is configured to buckle or bend up to at least 90 degrees or at least 180 degrees or 360 degrees relative to the stationary condition of the PCB without undergoing damage or breakage or loss of its functionality.

[0020] The flexible PCB 20 is in the form of an elongated strip (for the sake of generality, a plurality of flexible strips 20 are shown in Figure 2 . The conductive tracks of each flexible strip 20 are electrically coupled to the rigid portion 12, such as at least one corresponding conductive path 16.

[0021] Figure 3 Illustrated (in a top view, in the XY plane) Figure 2 is an enlarged view at the point where one flexible strip 20 is coupled to the rigid portion 12. As shown, the flexible strip 20 includes a plurality of conductive traces 22. Generally, the conductive traces extend parallel to each other; generally, the conductive traces extend on the insulating portion of the flexible strip 20 and form corresponding conductive paths that are electrically isolated from each other. Each conductive trace 22 is made of copper, for example.

[0022] Figure 4 Schematically shows Figure 3 a cross-section (in the XZ plane) of the view taken along the Figure 3 section line IV-IV.

[0023] Figure 5 and Figure 6 Illustrates Figure 4 a detailed embodiment of the material stack of the cross-section.

[0024] With joint reference to Figures 3 to 6 , the power module 10 includes 4 main parts or regions 30 - 36.

[0025] The first region 30 includes the rigid portion 12, including an electrical connection between the rigid portion 12 (such as the path 16) and the flexible strip 20.

[0026] The second region 32 includes a portion 20a of the flexible strip 20 that departs from the rigid portion 12 (electrically and physically coupled to the rigid portion), or otherwise extends from the rigid portion 12 towards the external environment 60, which is outside the power module 10.

[0027] The first region 30 and the second region 32 are covered by a cured resin, which forms the molded housing 14. The portion 20a of the flexible strip 20 that is buried within the molded housing 14 is rigidly held with the molded housing 14, and after the molded housing 14 is manufactured, the portion 20a of the flexible strip 20 is fixed or blocked in its position and is prevented from moving.

[0028] The third region 34 forms a transition for the flexible strip 20 between the molded housing 14 and the external environment 60. A transition portion 35 is provided at the "exit point" (side or side end 14a) of the molded housing 14, at which the flexible strip 20 exits the molded housing 14. The transition portion 35 is more rigid than the second region 32 (and more rigid than the fourth region 36 described later). In one embodiment, the transition portion 35 extends partially within the molded housing 14 and partially outside the molded housing 14; in one embodiment, the transition portion 35 is fully contained within the molded housing 14; in one embodiment, the transition portion 35 has an outer surface that is exposed towards the external environment 60 and that is coplanar with the side 14a of the molded housing 14. The transition portion 35 includes one or more membranes or layers of, for example, a non-conductive material (e.g., polyimide), the one or more membranes or layers being configured to act as a local stiffener for the flexible strip 20. The reinforcing film can be, for example, Other materials that can be used for the reinforcing film include (but are not limited to): FR4, IMS, polyimide, other plastics and / or composite materials, aluminum, stainless steel, copper, and their alloys.

[0029] The fourth region 36 includes the portion 20b of the flexible strip 20 that exits from the transition portion 35; in other words, the portion 20b of the flexible strip 20 extends from the transition portion 35 towards the external environment 60 and terminates in the external environment 60. Emerging from the molding material and the transition portion 35, the flexible strip 20 is free to move and can be bent as the case may be to communicatively couple to an external PCB or other device by, for example, mating with a JEDEC-compliant connector to form an electrical connection of the power module 10 in order to transfer electrical signals (including, for example, one or more of power supply, information data, signals, etc.).

[0030] The second region 34 and the fourth region 36 are formed by the same stack of stacked layers and / or membranes at least in corresponding portions. The third region 34 includes the same stack, but differs from the second region 32 and the fourth region 34 in that there are also reinforcing films that protect and strengthen the stack of stacked layers / membranes at the top and bottom.

[0031] In the presence of the reinforcing film, the flexible strip 20 has a value between 20 - 40 kg / cm 2higher local stiffness within the range of; in the absence of the reinforcing film, the flexible strip 20 has a lower local stiffness in the range of 30 - 50 kg / cm 2 range.

[0032] The lower local stiffness is achieved at the second region 32 (however, due to the presence of the molding case 14, at the second region 32, the flexible strip is blocked and cannot move or bend freely). The lower local stiffness is also achieved after the transition portion 35, at the fourth portion 36. The higher local stiffness is achieved at the transition portion 35 (the third region 34).

[0033] Figure 5 is Figure 4 a more detailed representation of the cross-section, where the sub-layers forming the power module 10 (limited to the regions 32 - 36 described above) are shown.

[0034] Referring to the first region 30, the rigid portion 12 of the power module 10 includes a ceramic substrate 40 that extends between a top conductive substrate 41 and a bottom conductive substrate 42 (e.g., a metal material such as Cu). The substrates 41 and 42 are coupled to the intermediate substrate 40, for example, by reflow soldering, or ultrasonic welding, or laser welding, or pressureless sintering, or conductive adhesive.

[0035] The flexible strip 20 is physically and electrically coupled (e.g., by welding) to the rigid portion 12 at the coupling region 45. The flexible strip 20 extends on top of the conductive substrate 41 and is welded to the top conductive substrate 41 at the welding region 45. The flexible strip 20 (such as the first portion 20a) includes a first conductive layer 44 (e.g., a metal material such as Cu), a first polyimide layer 46 that extends on the first conductive layer 44, and a second conductive layer 48 (e.g., a metal material such as Cu) that extends on the first polyimide layer 46 and is electrically connected to the first conductive layer 44 through one or more conductive vias 50 (e.g., a metal material such as Cu). In this way, the first polyimide layer 46 extends between (or is sandwiched between) the first conductive layer 44 and the second conductive layer 48. The second polyimide layer 47 of the flexible strip 20 extends on the second conductive layer 48 and is physically coupled to the second conductive layer 48 through an adhesive film 52.

[0036] The transition portion 35 is formed as part of the flexible strip 20 by coupling a top reinforcement film or layer 56 (which can be of Kapton material or other suitable materials as listed previously) to the second polyimide layer 47 via an adhesive or bonding film 54. The transition portion 35 further includes a third polyimide layer 58 that extends over the exposed surface of the first conductive layer 44 (i.e., the surface of layer 44 opposite the surface over which the first polyimide layer 46 extends). The third polyimide layer 58 is coupled to the first conductive layer 44 via a bonding film 60. Over the third polyimide layer 58, a bottom reinforcement film or layer 62 extends (similar to the top reinforcement film 56, which can be of Kapton material or other suitable materials as listed previously). The bottom reinforcement film 62 is coupled to the third polyimide layer 58 via an adhesive or bonding film 64.

[0037] The flexible strip 20 has an elongated shape with a major extension along the X-axis when stretched. Depending on the application and circumstances, the flexible strip 20 has an extension along the X-axis, for example, between a few millimeters (e.g., starting from 2 mm) and a few centimeters (e.g., up to 6 - 10 cm). The length of the reinforcement films 56, 62 along the X-axis is, for example, equal to or greater than 2 mm. The length of the portion 32 (i.e., the portion 20a of the strip 20 that is embedded in the molded housing 14 up to the coupling region 45 with the rigid portion 12) along the X-axis is in the range of, for example, 1 - 10 mm.

[0038] Figure 5 It is shown that the transition portion 35 extends partially within the molding material and partially outside the molding material; however, the present disclosure is not limited to this specific embodiment, and Figure 5 the description also applies to other disclosed embodiments in which the transition portion 35 is fully contained within the molding material or has an outer surface coplanar with the corresponding outer surface of the molding material / housing 14.

[0039] Further referring to Figure 5 , the second portion 20b of the flexible strip 20 has the same cross-section in terms of the material stack as the first portion 20a and is not further described.

[0040] Figure 6 Another embodiment of the flexible strip 20 is illustrated, which is Figure 5 an alternative to the embodiment of Figure 5 and Figure 6 The common elements / features of the embodiment of Figure 6In the embodiment of, the flexible strip 20 includes only one conductive layer (e.g., the first conductive layer 44), and it does not include the polyimide layer 46, the conductive vias 50, and the second conductive layer 48. The polyimide layers 47, 58 (corresponding to Figure 5 the second polyimide layer 47 and the third polyimide layer 58 of ) extend at opposite sides of the conductive layer 44 and are coupled to the conductive layer 44 through the adhesive films 52, 60.

[0041] Figure 5 The embodiment of can handle higher currents than the embodiment of Figure 6 and can be selected when the maximum current level handled by the flexible trace 20 must be improved (depending on the application).

[0042] Figure 5 and Figure 6 The exemplary thicknesses (in the Z direction) of the layers / films of and are indicated below in the possible ranges and preferred values (the ends of the ranges are included as possible thickness values).

[0043] Rigid portion 12 (e.g., between about 600 μm and 1400 μm):

[0044] Top copper substrate 41: 300 - 800 μm, preferably 500 μm,

[0045] Bottom copper substrate 42: 300 - 800 μm, preferably 500 μm,

[0046] Ceramic substrate 40: 0.2 - 0.65 mm.

[0047] Welding area 45: 40 - 70 μm, preferably 60 μm.

[0048] PCB 20 (e.g., in the absence of a reinforcing film, the total thickness is between 100 μm and 400 μm; in the presence of a reinforcing film, the total thickness is between 200 μm and 1000 μm):

[0049] First conductive layer 44: 15 - 35 μm, preferably 18 μm,

[0050] First polyimide layer 46: 20 - 75 μm, preferably 25 μm,

[0051] Second conductive layer 48: 15 - 35 μm, preferably 18 μm,

[0052] First adhesive film 52: 20 - 75 μm, preferably 25 μm,

[0053] Second adhesive film 60: 20 - 75 μm, preferably 25 μm,

[0054] Second polyimide layer 47: 10 - 50 μm, preferably 25 μm,

[0055] The third polyimide layer 58: 10 - 50 μm, preferably 25 μm,

[0056] The top reinforcing film 56: 50 - 300 μm,

[0057] The bottom reinforcing film 62: 50 - 300 μm.

[0058] Part of the manufacturing process of the power module 10 is illustrated in Figure 7A and Figure 7B and is limited to the steps relevant to the present disclosure (such as resin injection and the advantages associated with the presence of the top reinforcing film 56 and the bottom reinforcing film 62).

[0059] After coupling (by gluing, welding, etc.) the flexible strip 20 to the rigid part 12 and before forming the molded housing 14, the power module 10 is inserted onto the support part of the mold chase 100 ( Figure 7A ). The mold chase 100 is, for example, stainless steel.

[0060] The mold chase 100 includes a first part 100a and a second part 100b, which are configured to be coupled together to define a first inner chamber 101 and a second inner chamber 102. The first inner chamber 101 is shaped to receive the rigid part 12 and a first part 20a of the flexible part 20. The second inner chamber 102 is shaped to receive a second part 20b of the flexible strip 20. The mold 100 includes a transition region 104 between the inner chamber 101 and the inner chamber 102, and the transition region 104 includes a top limiting element 106a and a bottom limiting element 106b. The mold chase 100 is configured such that when the power module 10 is disposed in the mold chase 100, the transition part 35 extends at least partially between the inner chamber 101 and the inner chamber 102 at the transition region 104.

[0061] An opening 108 in the mold chase 100 is configured to allow resin injection within the first inner chamber 101, and the opening 108 is fluidly coupled to the first inner chamber 101 and not to the second inner chamber 102.

[0062] The top limiting element 106a and the bottom limiting element 106b are shaped such that when the parts 100a, 100b of the mold housing 100 are coupled together before resin injection, the top limiting element 106a and the bottom limiting element 106b are adjacent to the top reinforcing film 56 and the bottom reinforcing film 62 respectively. When the mold is closed, the top limiting element 106a and the bottom limiting element 106b exert a certain force on the top reinforcing film 56 and the bottom reinforcing film 62, such that when resin is injected into the first inner chamber 101, the same resin does not flow from the inner chamber 101 to the second inner chamber 102. There are damping rods with the same function in the mold housing lead frame cavity. A force (pressure) P is applied at opposite sides of the mold (in the Z direction), and for example within the range of pressure injecting resin (e.g., 4 - 7 MPa).

[0063] The presence of the top reinforcing film 56 and the bottom reinforcing film 62 helps to prevent resin from flowing into the second inner chamber 102 and at the same time protects the flexible strip 20 from being damaged during the pressing of the mold housing 100.

[0064] Then, the step of curing the resin is performed in a manner known per se (depending on the type of resin used) to cure the resin.

[0065] Then, the mold housing 100 is removed.

[0066] After manufacturing (i.e., in the final power module 10), the presence of the transition part 35 is useful for indentation via the reference points.

[0067] Based on the foregoing discussion, the advantages provided by the present disclosure are obvious.

[0068] In addition to the advantages already pointed out, the proposed solution makes the SIP production very flexible in product series or open market versions without being bound by customer requirements, thus reducing costs. Moreover, the possibility of having overlapping layers can allow for reducing the L stray inductance inside the module.

[0069] Due to the selection of high - temperature - resistant materials such as polyimide, the rigid section (rigid damping rod) of the rigid element leaving the plastic housing allows overcoming the difficulties of the individual applicability of the flexible PCB in terms of resin injection temperature.

[0070] It is possible to customize only the external interface or the internal layout of the power module that needs to be changed based on customer requirements without changing the molding tool (advantageous in terms of POA) or the lead frame. The plastic housing topology does not need to be changed or adjusted.

[0071] Obviously, modifications and variations can be made to what has been described and illustrated herein without thereby departing from the scope of the present disclosure.

[0072] The present disclosure relates to a PCB 20 having: a first PCB region 32 having a stacked structure of layers and / or films stacked along the Z direction; a second PCB region 34 having the stacked structure, the stacked structure further including a top reinforcing film 56 at a first side and having a bottom reinforcing film 62 at a second side, the second side being opposite to the first side along the Z direction; and a third PCB region 36 having the stacked structure without the top reinforcing film 56 and the bottom reinforcing film 62. The first PCB region 32 is physically and electrically continuous with the second PCB region 34, and the second PCB region 34 is physically and electrically continuous with the third PCB region 36. The top reinforcing film 56 and the bottom reinforcing film 62 are configured to locally increase the stiffness of the PCB 20 relative to regions of the PCB 20 where the top and bottom reinforcing films do not exist. The PCB 20 may be referred to as a rigid-flex PCB because it includes flexible portions 32, 36 and an intermediate rigid portion 34.

[0073] Figure 7A and Figure 7B The chamber 102 in [reference] and [figure] may not be closed on the left hand side of the figure, i.e., the chamber 103 is open to the external environment 60.

[0074] The stiffeners 106a, 106b may be shaped along the Z axis, i.e., they may have any shape (not necessarily the rectangular shape as shown, but any polygon or irregular shape) and any thickness (even a thickness that varies along the Z axis). The PCB portion between the stiffeners is flexible and can follow the shape of the stiffeners.

[0075] The power module (10) is generally described as including: a first portion (30, 12) including a substrate (12, 40 - 42) including a conductive material; a second portion (32, 36) including a PCB (20) having a stacked structure of layers stacked along a first direction (Z), the stacked structure being electrically coupled to the rigid substrate (12) at a coupling region; and a molded housing (14) embedding portions of the rigid substrate (12) and the PCB (20) and having a side surface where the PCB (20) protrudes outside the molded housing (14), wherein at the side surface of the molded housing (14), the stacked structure of the PCB (20) is locally bounded by a top reinforcing element (56) at a first side and by a bottom reinforcing element (62) at a second side, the second side being opposite to the first side along the first direction (Z), and the top and bottom reinforcing elements are configured to locally increase the stiffness of the PCB (20) relative to regions of the PCB (20) where the top and bottom reinforcing elements do not exist.

[0076] The top reinforcement element and the bottom reinforcement element (56, 62) have extensions that are limited to the transition region (35) of the PCB (20) from the inside of the molded housing (14) to the outside of the molded housing (14).

[0077] The PCB (20) has an elongated shape with a main extension along a second direction (X) that is orthogonal to the first direction (Z).

[0078] The PCB (20) has an extension that is higher than 2 mm along the second direction (X), and the top reinforcement element and the bottom reinforcement element (56, 62) have extensions that are higher than 2 mm along the second direction (X).

[0079] Both the top reinforcement element (56) and the bottom reinforcement element (62) are at least partially embedded within the molded housing (14).

[0080] The top reinforcement element and the bottom reinforcement element (56, 62) are in direct physical contact with the molded housing (14).

[0081] The PCB (20) has a first PCB region and a second PCB region (20a, 20b) and a third PCB region (35), the first PCB region and the second PCB region having a first stiffness value, and the third PCB region having a second stiffness value that is higher than the first stiffness value.

[0082] Each of the first PCB region and the second PCB region (20a, 20b) includes the stacked structure, and the third PCB region includes: the stacked structure, a top reinforcement element (56) on a first side of the stacked structure, and a bottom reinforcement element (62) on a second side of the stacked structure, the second side being opposite the first side along the first direction (Z).

[0083] The first PCB region (20a) is embedded within the molded housing (14), and the second PCB region (20b) protrudes outside the molded housing (14) and is configured to move and / or bend freely.

[0084] The first stiffness value enables the second PCB region (20b) to be bent up to 90 degrees or 180 degrees or up to 360 degrees relative to the rest condition of the PCB (20) without losing its function.

[0085] The top reinforcement element (56) and the bottom reinforcement element (62) are films of polyimide material that have respective thicknesses in the range of 30 - 1500 μm along the first direction (Z).

[0086] The top reinforcement element (56) and the bottom reinforcement element (62) are of at least one of the following materials: FR4, IMS, polyimide, plastic material, aluminum, stainless steel, copper, alloys of aluminum, stainless steel, and copper.

[0087] The top reinforcement element (56) and the bottom reinforcement element (62) are made of polyimide and are made of at least one of the following materials: FR4, IMS, polyimide, plastic material, aluminum, stainless steel, copper, alloys of aluminum, stainless steel, and copper.

[0088] The PCB (20) includes a connector configured to be electrically connected to another printed circuit board.

[0089] The stacked structure of the PCB includes at least a first conductive layer (44) sandwiched between two insulating layers (47, 58).

[0090] The stacked structure of the PCB further includes at least a second conductive layer (48) and an intermediate insulating layer (46) between the first conductive layer and the second conductive layer (44, 48), and the first conductive layer (44), the second conductive layer (48), and the intermediate insulating layer (46) are sandwiched between the two insulating layers (47, 58).

[0091] The top reinforcement element and the bottom reinforcement element (56, 62) are coupled to the stacked structure of the PCB through respective adhesive films (54, 64).

[0092] A method of manufacturing a power module (10), the power module comprising: a substrate (12) comprising a conductive material; a PCB (20) having a first PCB region with a stacked structure of layers and / or films stacked along a first direction (Z); a second PCB region having the stacked structure, the stacked structure being locally defined by a top reinforcement element (56) at a first side and by a bottom reinforcement element (62) at a second side, the second side being opposite the first side along the first direction (Z); and a third PCB region comprising the stacked structure, wherein the first PCB region is electrically coupled between the rigid substrate (12) and a first end of the second PCB region, and the third PCB region is electrically coupled to a second end of the second PCB region, the second end being opposite the first end, and wherein the top reinforcement element and the bottom reinforcement element are configured to locally increase the stiffness of the PCB (20) relative to the first and third regions of the PCB (20) that do not have the top and bottom reinforcement elements, the method comprising the steps of: providing a mold (100) having a base element (100b) and a cap element (100a), one of the base element and the cap element being provided with a passing hole (108), the base element and the cap element being shaped to define a first inner chamber (101), a second inner chamber (102), and restricted regions (104, 106a, 106b), the restricted regions (104, 106a, 106b) including a first protrusion (106a) from the base element and a second protrusion (106b) from the cap element between the first inner chamber and the second inner chamber; arranging the power module (10) on a support portion within the base element such that the top reinforcement element (56) corresponds to the first protrusion (106a) and the bottom reinforcement element (62) corresponds to the second protrusion (106b); coupling the base element and the cap element together and applying a pressure (P) on the top reinforcement element and the bottom reinforcement element by means of the first and second protrusions (106a, 106b); injecting a resin (16) into the first inner chamber (101) through the passing hole (108); curing the resin (16) within the first inner chamber (101); and removing the mold (100).

[0093] The PCB (20) is outlined to include: a first PCB region (20a, 32); a second PCB region (20b, 36); a third PCB region (34); wherein the first PCB region, the second PCB region, and the third PCB region extend in a physically and electrically continuous manner with each other, the stacked structure includes a plurality of stacked layers along a first direction (Z), wherein each of the first PCB region and the second PCB region (20a, 20b) includes the stacked structure, and wherein the third PCB region includes: the stacked structure, a top reinforcement element (56) on a first side of the stacked structure, and a bottom reinforcement element (62) on a second side of the stacked structure, the second side being opposite to the first side along the first direction (Z), and the top reinforcement element and the bottom reinforcement element are configured to locally increase the stiffness of the PCB (20) at the third PCB region.

[0094] The first PCB region (20a, 32) and the second PCB region (20b, 36) are of a flexible type.

[0095] The first PCB region (20a, 32) and the second PCB region (20b, 36) are configured to be bent up to at least 90 degrees or up to at least 180 degrees or up to 360 degrees relative to the stationary condition of the PCB (20) without losing their functions.

[0096] The various above-described embodiments can be combined to provide additional embodiments. Aspects of the embodiments can be modified as needed to incorporate concepts from various patents, applications, and publications to provide additional embodiments.

[0097] These and other changes can be made to the embodiments in accordance with the above detailed description. In general, in the appended claims, the terms used should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments and the full scope of equivalents to such claims. Thus, the claims are not limited by the present disclosure.

Claims

1. A power module, comprising: a first portion, the first portion comprising a rigid substrate having a conductive material; a second part, the second part comprising a printed circuit board PCB, the PCB having a stacked structure of layers, the layers being stacked along a first direction, the stacked structure being electrically coupled to the rigid substrate at a coupling region; a molded housing that embeds a portion of the rigid substrate and a portion of the PCB and has a side surface at which the PCB protrudes out of the molded housing, wherein, at the side surface of the molded housing, the stacked structure of the PCB is partially defined at a first side by a top reinforcement element and partially defined at a second side by a bottom reinforcement element, the second side being opposite to the first side along the first direction, The top stiffening element and the bottom stiffening element are configured to locally increase the stiffness of the PCB relative to areas of the PCB where the top stiffening element and the bottom stiffening element are not present. 2 . The power module according to claim 1 , wherein the top stiffening member and the bottom stiffening member have extensions, the extensions being limited to a transition region of the PCB from an interior of the molded case to an exterior of the molded case. 3 . The power module of claim 2 , wherein the PCB has an elongated shape with a main extension along a second direction, the second direction being orthogonal to the first direction. 4 . The power module according to claim 3 , wherein the PCB has an extension higher than 2 mm in the second direction, and the top stiffening element and the bottom stiffening element have an extension higher than 2 mm in the second direction. 5 . The power module of claim 1 , wherein both the top stiffening member and the bottom stiffening member are at least partially embedded within the molded housing. 6 . The power module of claim 1 , wherein the top stiffening member and the bottom stiffening member are in direct physical contact with the molded housing.

7. The power module according to claim 1, wherein the PCB has a first PCB area, a second PCB area, and a third PCB area, the first PCB area and the second PCB area have a first stiffness value, the third PCB area has a second stiffness value, and the second stiffness value is greater than the first stiffness value.

8. The power module according to claim 7, wherein each of the first PCB area and the second PCB area includes the stacked structure, and The third PCB area includes the stack structure, the top reinforcement element on a first side of the stack structure, and the bottom reinforcement element on a second side of the stack structure, the second side being opposite to the first side along the first direction.

9. The power module according to claim 7, wherein: The first PCB region is embedded within the molded housing, and the second PCB region protrudes out of the molded housing and is configured to move or bend freely.

10. The power module of claim 7, the first stiffness value enabling the second PCB area to be bent up to 90 degrees or 180 degrees or up to 360 degrees relative to a static condition of the PCB without losing functionality of the PCB. 11 . The power module of claim 1 , wherein the top stiffening member and the bottom stiffening member are films of a polyimide material having respective thicknesses in the range of 30-1500 μm along the first direction.

12. The power module of claim 1, wherein the top stiffening member and the bottom stiffening member are from at least one of the following materials: FR4, IMS, Polyimide, Plastic material, Aluminum, Stainless steel, Copper, Alloy of aluminum, stainless steel, copper.

13. The power module of claim 1, wherein the top stiffener and the bottom stiffener are polyimide, which is at least one of the following materials: FR4, IMS, Polyimide, Plastic material, Aluminum, Stainless steel, Copper, Alloy of aluminum, stainless steel, copper.

14. The power module of claim 1, wherein the PCB comprises a connector configured to be electrically connected to another printed circuit board. 15 . The power module according to claim 1 , wherein the stack structure of the PCB comprises at least a first conductive layer sandwiched between two insulating layers.

16. The power module according to claim 15, wherein the stacked structure of the PCB comprises at least a second conductive layer and an intermediate insulating layer, the intermediate insulating layer being between the first conductive layer and the second conductive layer, The first conductive layer, the second conductive layer, and the intermediate insulating layer are sandwiched between the two insulating layers. 17 . The power module of claim 1 , wherein the top stiffener and the bottom stiffener are coupled to the stack structure of the PCB through respective adhesive films.

18. A method for manufacturing a power module, the power module comprising: a rigid substrate comprising a conductive material; A PCB having a first PCB region, wherein the first PCB region has a stacked structure of layers or films stacked along a first direction; a second PCB area having the stacked structure partially bounded at a first side by a top stiffening element and partially bounded at a second side by a bottom stiffening element, the second side being opposite to the first side along the first direction; and a third PCB region, the third PCB region comprising the stacked structure, wherein the first PCB region is electrically coupled between the rigid substrate and a first end of the second PCB region, and the third PCB region is electrically coupled to a second end of the second PCB region, the second end being opposite to the first end, and wherein the top stiffening element and the bottom stiffening element are configured to locally increase the stiffness of the PCB relative to the first region and the third region of the PCB where the top stiffening element and the bottom stiffening element are not present, the method comprising: providing a mold having a base element and a cover element, one of the base element and the cover element including a through hole, the base element and the cover element being shaped to define a first interior chamber, a second interior chamber, and a restricted area, the restricted area including a first protrusion from the base element and a second protrusion from the cover element between the first interior chamber and the second interior chamber; placing the power module on a support portion within the base member such that the top reinforcing member corresponds to the first protrusion and the bottom reinforcing member corresponds to the second protrusion; coupling the base member and the cover member together, applying pressure on the top reinforcement member and the bottom reinforcement member by means of the first protrusion and the second protrusion; injecting resin into the first inner chamber through the through hole; curing the resin in the first inner chamber; and The mold is removed.

19. A PCB, comprising: First PCB area; Second PCB area; a third PCB region, wherein the first PCB region, the second PCB region, and the third PCB region extend in physical and electrical continuity with each other; as well as A stacking structure comprising a plurality of stacking layers, wherein the plurality of stacking layers are along a first direction, wherein each of the first PCB region and the second PCB region comprises the stacking structure, and wherein the third PCB area includes the stacking structure, a top reinforcing element and a bottom reinforcing element, the top reinforcing element is on a first side of the stacking structure, the bottom reinforcing element is on a second side of the stacking structure, and the second side is opposite to the first side along the first direction, The top stiffening element and the bottom stiffening element are configured to locally increase the stiffness of the PCB at the third PCB area.

20. The PCB of claim 19, wherein the first PCB area and the second PCB area are of a flexible type.

21. The PCB of claim 19, wherein the first PCB area and the second PCB area are configured to be bent up to at least 90 degrees, or up to at least 180 degrees, or up to 360 degrees relative to a static condition of the PCB without losing functionality of the PCB.

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