Power device and PCB

Abstract

The embodiment of the utility model relates to a power device and a PCB. The power device includes a rigid-flexible PCB that is separated from a resin molded case and includes: 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 device is also provided.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to rigid-flex printed circuit board (PCB) and power device. BACKGROUND

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

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

[0004] In the known art ( Figure 1 ), TMM packages are usually built using rigid leadframes 1 provided with rigid connections (busbars for power connections) and control pins (needles) 2 for control input connections, which are bent after the molding step. The rigid connections exit the package molding (resin plastic housing) for connection with the PCB. As mentioned above, packages thus manufactured are suitable for mass production. However, many customers require components covering as wide a range of applications as possible. Different applications often require expensive modifications to the production line.

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

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

[0007] According to the present disclosure, a power device and a printed circuit board are provided.

[0008] According to a first aspect, there is provided a power device. The power device comprises a first part, a second part, and a molded housing. The first part comprises a rigid substrate having an electrically conductive portion. The second part comprises a printed circuit board, PCB, having a stack of layers, the layers being stacked along a first direction, the stack being electrically coupled to the rigid substrate at a coupling region. The molded housing embeds portions of the rigid substrate and the PCB, and has a side surface at which the PCB protrudes outside the molded housing. At the side surface of the molded housing, the stack of the PCB is locally delimited at a first side by a top stiffening element, and at a second side by a bottom stiffening element, the second side being opposite the first side along the first direction. The top stiffening element and the bottom stiffening element are configured to locally increase a stiffness of the PCB with respect to a region of the PCB in which the top stiffening element and the bottom stiffening element are absent.

[0009] In some embodiments, the top stiffening element and the bottom stiffening element have an extension limited to a transition region of the PCB, the transition region being from an interior of the molded housing to an exterior of the molded housing.

[0010] In some embodiments, the PCB has an elongated shape having a main extension along a second direction, the second direction being orthogonal to the first direction.

[0011] In some embodiments, the PCB has an extension along the second direction higher than 2 mm, and the top stiffening element and the bottom stiffening element have an extension along the second direction higher than 2 mm.

[0012] In some embodiments, the top stiffening element and the bottom stiffening element are both at least partially embedded within the molded housing.

[0013] In some embodiments, the top stiffening element and the bottom stiffening element are in direct physical contact with the molded housing.

[0014] In some embodiments, the PCB has a first PCB region and a second PCB region, and a third PCB region, the first PCB region and the second PCB region having a first stiffness value, the third PCB region having a second stiffness value, the second stiffness value being greater than the first stiffness value.

[0015] In some embodiments, each of the first PCB region and the second PCB region comprises the stack, and the third PCB region comprises the stack, the top stiffening element on a first side of the stack, and the bottom stiffening element on a second side of the stack, the second side being opposite the first side along the first direction.

[0016] In some embodiments, the first PCB region is embedded within the molded housing, and the second PCB region protrudes outside the molded housing and is configured to be free to move or bend.

[0017] In some embodiments, the first stiffness value enables the second PCB region to be bent up to 90 degrees or 180 degrees or up to 360 degrees with respect to the rest condition of the PCB without losing the PCB functionality.

[0018] In some embodiments, the top and bottom reinforcing elements are films of polyimide material, the films having respective thicknesses in the range 30-1500 pm along the first direction.

[0019] In some embodiments, the top and bottom reinforcing elements are of at least one material from the following: FR4, IMS, polyimide, plastic material, aluminum, stainless steel, copper, alloys of aluminum, stainless steel, copper.

[0020] In some embodiments, the top and bottom reinforcing elements are of polyimide, of at least one material from the following: FR4, IMS, polyimide, plastic material, aluminum, stainless steel, copper, alloys of aluminum, stainless steel, copper.

[0021] In some embodiments, the PCB comprises a connector configured to be electrically connected to a further printed circuit board.

[0022] In some embodiments, the stack structure of the PCB comprises at least a first conductive layer, the first conductive layer being sandwiched between two insulating layers.

[0023] In some embodiments, the stack 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 two insulating layers.

[0024] In some embodiments, the top and bottom reinforcing elements are coupled to the stack structure of the PCB through respective adhesive films.

[0025] According to a second aspect, there is provided a PCB. The PCB comprises a first PCB region, a second PCB region, a third PCB region and a stack structure. The first, second and third PCB regions extend in a physically and electrically continuous manner with each other. The stack structure comprises a plurality of build-up layers, the plurality of build-up layers being along a first direction. Each of the first and second PCB regions comprises the stack structure. The third PCB region comprises the stack structure, a top stiffening element on a first side of the stack structure and a bottom stiffening element on a second side of the stack structure, the second side being opposite the first side along the first direction. The top and bottom stiffening elements are configured to locally increase a stiffness of the PCB at the third PCB region.

[0026] In some embodiments, the first and second PCB regions are of a flexible type.

[0027] In some embodiments, the first and second PCB regions are configured to be bent up to at least 90 degrees or up to at least 180 degrees or up to 360 degrees with respect to a rest condition of the PCB without losing functionality of the PCB.

[0028] According to embodiments of the present disclosure, power devices and printed circuit boards with improved performance can be implemented. BRIEF DESCRIPTION OF DRAWINGS

[0029] Embodiments of the present disclosure will now be described, by way of non-limiting example only, with reference to the accompanying drawings:

[0030] Figure 1 illustrating a TMM PM according to known technology;

[0031] Figure 2 illustrating a power device according to the present disclosure;

[0032] Figure 3 illustrating Figure 2 an enlarged portion of the power device of

[0033] Figure 4 illustrating Figure 3 a cross-sectional view of an enlarged portion of the power device of

[0034] Figure 5 illustrating Figure 4 a detailed cross-sectional view of the power device of

[0035] Figure 6 illustrating Figure 4 a detailed cross-sectional view of the power device of according to one alternative embodiment; and

[0036] Figure 7A and Figure 7Ba portion of a manufacturing process for manufacturing a portion of a power device. Figure 2 of the power device. DETAILED DESCRIPTION

[0037] Figure 2 The power device 10 is illustrated in a three-axis system of orthogonal axes X, Y, Z. The power device 10 is represented in a top view on the plane XY at an intermediate manufacturing step.

[0038] The power device 10 comprises a rigid or solid portion (or rigid / solid body) 12 comprising one or more layers of electrically conductive portions (e.g. copper (Cu)). The rigid portion 12 is at least partially covered by a molded shell 14 of electrically insulating material (e.g. made of epoxy resin, epoxy-based molding compound or other plastic material). The molded shell 14 is formed for example by resin transfer molding (RTM), in a manner known per se in the art. In order to better understand the present disclosure and to more clearly illustrate the top conductive layer of the rigid portion 12 and other elements relevant to the disclosed present disclosure, the molded shell 14 is illustrated as open at selective portions.

[0039] The rigid portion 12 is shaped so as to define a plurality of electrically conductive paths 16 for signal transmission.

[0040] According to one aspect of the present disclosure, the power device 10 further comprises one or more PCBs 20 (FPC, FPC with stiffener, rigid-flex PCB, etc.), each PCB 20 comprising a flexible insulating support on which (or within which) one or more electrically conductive tracks or traces extend. The PCB 20 is also referred to as a flexible PCB 20. For example, each PCB 20 is configured to be flexed or bent by up to at least 90 degrees or at least 180 degrees or 360 degrees with respect to a rest condition of the PCB without being subjected to damage or breaking or losing its functionality.

[0041] The flexible PCB 20 is in the form of an elongated strip (a plurality of flexible strips 20 are shown in Figure 2 without loss of generality). The electrically conductive tracks of each flexible strip 20 are electrically coupled to the rigid portion 12, such as to at least one respective electrically conductive path 16.

[0042] Figure 3 An enlarged view is illustrated (in a top view, on the XY plane) of a point in Figure 2 at which one flexible strip 20 is coupled to the rigid portion 12. As shown, the flexible strip 20 comprises a plurality of electrically conductive traces 22. Typically, the electrically conductive traces extend parallel to each other; typically, the electrically conductive traces extend on the insulating portion of the flexible strip 20 and form respective electrically conductive paths electrically isolated from each other. Each electrically conductive trace 22 is made for example of copper.

[0043] Figure 4 schematically illustrates Figure 3 the view along Figure 3 the section (in the XZ plane) considered along the section line IV-IV of

[0044] Figure 5 and Figure 6 illustrates Figure 4 a detailed embodiment of the material stack of the section of

[0045] Referring jointly to Figures 3 to 6 , the power device 10 includes 4 main sections or regions 30-36.

[0046] The first region 30 includes the rigid section 12, including electrical connections between the rigid section 12 (such as the traces 16) and the flexible strip 20.

[0047] The second region 32 includes a portion 20a of the flexible strip 20 that exits (is electrically and physically coupled to) the rigid section 12, or otherwise extends from the rigid section 12 toward the external environment 60, which is external to the power device 10.

[0048] The first region 30 and the second region 32 are covered by the 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 by the molded housing 14, and after the molded housing 14 is manufactured, the portion 20a of the flexible strip 20 is fixed or plugged in its position and is prevented from moving.

[0049] 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 entirely contained within the molded housing 14; in one embodiment, the transition portion 35 has an outer surface that is exposed toward the external environment 60, which is coplanar with the side 14a of the molded housing 14. The transition portion 35 includes one or more films or layers of, for example, a non-conductive portion (e.g., polyimide) configured to act as a local stiffener for the flexible strip 20. The stiffening film can be, for example, a polyimide film, such as Kapton®. Other materials that can be used for the stiffening film include (but are not limited to): FR4, IMS, polyimide, other plastics and / or composites, aluminum, stainless steel, copper, and alloys thereof.

[0050] The fourth region 36 comprises the portion 20b of the flexible strip 20 exiting 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. From the moulding material and the transition portion 35, the flexible strip 20 is free to move and can be bent according to the case to be communicatively coupled to an external PCB or other device by joining, for example, a connector compliant with JEDEC, forming an electrical connection of the power device 10, so as to transfer electrical signals (including one or more of, for example, power supply, information data, signals, etc.).

[0051] The second region 34 and the fourth region 36 are formed at least in the respective portions by the same stack of build-up layers and / or films. The third region 34 comprises the same stack, but differs from the second region 32 and the fourth region 34 in that there is also a reinforcement film that protects and reinforces the stack of build-up layers / films at the top and at the bottom.

[0052] In the presence of the reinforcement film, the flexible strip 20 has a higher local stiffness in the range 20-40 kg / cm 2 ; in the absence of the reinforcement film, the flexible strip 20 has a lower local stiffness in the range 30-50 kg / cm 2 .

[0053] The lower local stiffness is achieved at the second region 32 (however, due to the presence of the moulding 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 at the fourth portion 36, after the transition portion 35. The higher local stiffness is achieved at the transition portion 35 (third region 34).

[0054] Figure 5 is a more detailed representation of the cross-section of Figure 4 , in which the sub-layers (limited to the regions 32-36 described above) forming the power device 10 are shown.

[0055] With reference to the first region 30, the rigid portion 12 of the power device 10 comprises a ceramic substrate 40 extending between a top conductive substrate 41 and a bottom conductive substrate 42 (for example, of a metallic 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 glue.

[0056] The flexible strip 20 is physically and electrically coupled (e.g., by soldering) with the rigid portion 12 at the coupling region 45. The flexible strip 20 extends on top of the conductive substrate 41 and is soldered to the top conductive substrate 41 at the soldering region 45. The flexible strip 20, such as the first portion 20a, includes a first conductive layer 44 (e.g., of a metallic material such as Cu), a first polyimide layer 46 extending on the first conductive layer 44, and a second conductive layer 48 (e.g., of a metallic material such as Cu) extending on the first polyimide layer 46 and electrically connected to the first conductive layer 44 by one or more conductive vias 50 (e.g., of a metallic material such as Cu). In this manner, the first polyimide layer 46 extends between (or is sandwiched between) the first and second conductive layers 44, 48. A 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 by an adhesive film 52.

[0057] The transition portion 35 is formed as part of the flexible strip 20 by coupling a top reinforcing film or layer 56 (which can be of Kapton material or other suitable material as listed previously) on the second polyimide layer 47 by an adhesive or adhesive film 54. The transition portion 35 also includes a third polyimide layer 58 extending on an exposed surface of the first conductive layer 44 (i.e., the surface of the layer 44 opposite to the surface on which the first polyimide layer 46 extends). The third polyimide layer 58 is coupled to the first conductive layer 44 by an adhesive film 60. On the third polyimide layer 58, a bottom reinforcing film or layer 62 extends (similar to the top reinforcing film 56, which can be of Kapton material or other suitable material as listed previously). The bottom reinforcing film 62 is coupled to the third polyimide layer 58 by an adhesive or adhesive film 64.

[0058] The flexible strip 20 has an elongated shape with a main extension along the X-axis when stretched. Depending on the application and circumstances, the flexible strip 20 has an extension along the X-axis of, for example, between a few millimeters (e.g., from 2 millimeters) and a few centimeters (e.g., up to 6-10 centimeters). The length of the reinforcing films 56, 62 along the X-axis is, for example, equal to or larger than 2 millimeters. 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, for example, in the range of 1-10 mm.

[0059] Figure 5 It is shown that the transition portion 35 extends partly within the molding material and partly outside the molding material; however, the present disclosure is not limited to this specific embodiment, and Figure 5The description also applies to other disclosed embodiments in which the transition portion 35 is completely contained within the molding material or has an outer surface coplanar with the corresponding outer surface of the molding material / shell 14.

[0060] Further reference Figure 5 The second part 20b of the flexible strip 20 has the same cross-section as the first part 20a in terms of material stacking and is not described further.

[0061] Figure 6 Another embodiment of the flexible strip 20 is illustrated. Figure 5 Alternative embodiments of the present invention. Figure 5 and Figure 6 Common elements / features of the embodiments are identified using the same reference numerals and are not described further. Figure 6 In this embodiment, the flexible strip 20 includes only one conductive layer (e.g., a first conductive layer 44), and it does not include the polyimide layer 46, the conductive via 50, or the second conductive layer 48. Polyimide layers 47 and 58 (corresponding to...) Figure 5 The second polyimide layer 47 and the third polyimide layer 58 extend on opposite sides of the conductive layer 44 and are coupled to the conductive layer 44 via adhesive films 52 and 60.

[0062] Figure 5 The embodiments are capable of handling more Figure 6 The embodiments offer higher current and can be selected when the maximum current level handled by the flexible trace 20 must be improved (depending on the application).

[0063] Figure 5 and Figure 6 The exemplary thickness (along the Z direction) of the layer / film is indicated within a possible range and preferred value (the ends of the range are included as possible thickness values).

[0064] Rigid portion 12 (e.g., between approximately 600 μm and 1400 μm):

[0065] Top copper substrate 41: 300-800μm, preferably 500μm.

[0066] Bottom copper substrate 42: 300-800μm, preferably 500μm.

[0067] Ceramic substrate 40: 0.2-0.65mm.

[0068] The welding area is 45: 40-70μm, preferably 60μm.

[0069] PCB 20 (e.g. between 100 and 400 pm in total thickness in the absence of a reinforcement film; between 200 and 1000 pm in total thickness in the presence of a reinforcement film):

[0070] First conductive layer 44: 15-35 pm, preferably 18 pm,

[0071] First polyimide layer 46: 20-75 pm, preferably 25 pm,

[0072] Second conductive layer 48: 15-35 pm, preferably 18 pm,

[0073] First adhesive film 52: 20-75 pm, preferably 25 pm,

[0074] Second adhesive film 60: 20-75 pm, preferably 25 pm,

[0075] Second polyimide layer 47: 10-50 pm, preferably 25 pm,

[0076] Third polyimide layer 58: 10-50 pm, preferably 25 pm,

[0077] Top reinforcement film 56: 50-300 pm,

[0078] Bottom reinforcement film 62: 50-300 pm.

[0079] A part of the manufacturing process of the power device 10 is illustrated in Figure 7A and Figure 7B , which part is limited to the steps relevant to the present disclosure (such as resin injection and the advantages associated with the presence of the top and bottom reinforcement films 56 and 62).

[0080] After coupling (by gluing, soldering, etc.) the flexible strip 20 to the rigid portion 12, and before forming the molded case 14, the power device 10 is inserted on the support portion of the mold chase 100 Figure 7A . The mold chase 100 is for example stainless steel.

[0081] The mold shell 100 comprises a first portion 100a and a second portion 100b 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 house the rigid portion 12, and the first portion 20a of the flexible portion 20. The second inner chamber 102 is shaped to house the second portion 20b of the flexible strip 20. The mold 100 comprises a transition area 104 between the inner chamber 101 and the inner chamber 102, the transition area 104 comprising a top limiting element 106a and a bottom limiting element 106b. The mold shell 100 is configured so that, when the power device 10 is arranged in the mold shell 100, the transition portion 35 extends at least partially between the inner chamber 101 and the inner chamber 102, at the transition area 104.

[0082] The opening 108 in the mold shell 100 is configured to allow resin injection within the first inner chamber 101, the opening 108 being fluidly coupled to the first inner chamber 101, without being coupled to the second inner chamber 102.

[0083] The top limiting element 106a and the bottom limiting element 106b are shaped so that, when the portions 100a, 100b of the mold shell 100 are coupled together before resin injection, the top limiting element 106a and the bottom limiting element 106b are adjacent to the top stiffening film 56 and the bottom stiffening 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 stiffening film 56 and the bottom stiffening film 62, so that, when resin is injected within the first inner chamber 101, the same resin does not flow from the inner chamber 101 to the second inner chamber 102. There are dampening rods in the mold shell leadframe cavities that have the same function. The force (pressure) P is exerted at the opposite sides of the mold (in the Z direction), and is for example within the range of pressure injection resins (e.g. 4-7 MPa).

[0084] The presence of the top stiffening film 56 and the bottom stiffening film 62 helps to avoid resin flowing into the second inner chamber 102, and at the same time protects the flexible strip 20 from being damaged during pressing of the mold shell 100.

[0085] Then, a step of curing the resin is performed in a manner known per se (depending on the type of resin used) to cure the resin.

[0086] Then, the mold shell 100 is removed.

[0087] After manufacturing (i.e. in the final power device 10), the presence of the transition portion 35 is useful for the indentation via the fiducial point.

[0088] From the foregoing discussion it will be apparent that the present disclosure provides advantages.

[0089] In addition to the advantages already noted, the proposed solution makes SIP production highly flexible across product lines or open-market versions, free from customer constraints, thereby reducing costs. Furthermore, the possibility of overlapping layers allows for a reduction in stray L-inductance within the module.

[0090] The selection of high-temperature resistant materials, such as polyimide, allows the rigid sections (rigid damping rods) with rigid elements separated from the plastic housing to overcome the difficulties of the sole applicability of flexible PCBs in terms of resin injection temperature.

[0091] We can customize only the external interfaces or internal layout of the power devices that need to be changed based on customer requirements, without altering the molding tools (an advantage in POA) or lead frames. The plastic housing topology does not need to be changed or adjusted.

[0092] Obviously, modifications and changes can be made to the content described and illustrated herein without departing from the scope of this disclosure.

[0093] This disclosure relates to a PCB 20 having: a first PCB region 32 having a stacked structure of layers and / or films deposited 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 a bottom reinforcing film 62 at a second side 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 and the second PCB region 34 are physically and electrically continuous, and the second PCB region 34 and the third PCB region 36 are physically and electrically continuous. 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 are absent. The PCB 20 may be referred to as a rigid-flexible PCB because it includes flexible portions 32 and 36 and an intermediate rigid portion 34.

[0094] Figure 7A and Figure 7B The chamber 102 on the left side of the figure can be left open, that is, the chamber 103 is open to the external environment 60.

[0095] The reinforcing members 106a and 106b can be shaped along the Z-axis, meaning they can have any shape (not necessarily the rectangular shape shown, but any polygonal or irregular shape) and any thickness (even a variable thickness along the Z-axis). The PCB portion between the reinforcing members is flexible and can conform to the shape of the reinforcing members.

[0096] The power device (10) is generalized to comprise: a first portion (30, 12) comprising a substrate (12, 40-42) comprising an electrically conductive portion; a second portion (32, 36) comprising a PCB (20) having a stack structure of layers stacked along a first direction (Z), the stack structure being electrically coupled with the rigid substrate (12) at a coupling region; a molded housing (14) embedding a portion of the rigid substrate (12) and a portion of the PCB (20) and having a lateral surface at which the PCB (20) protrudes outside the molded housing (14), wherein, at said lateral surface of the molded housing (14), the stack structure of the PCB (20) is locally delimited, at a first side, by a top stiffening element (56) and, at a second side, by a bottom stiffening element (62), the second side being opposite to the first side along the first direction (Z), the top and bottom stiffening elements being configured to locally increase the rigidity of the PCB (20) with respect to a region of the PCB (20) in which said top and bottom stiffening elements are absent.

[0097] The top and bottom stiffening elements (56, 62) have an extension limited to a transition region (35) of the PCB (20) from an interior of the molded housing (14) to an exterior of the molded housing (14).

[0098] The PCB (20) has an elongated shape having a main extension along a second direction (X) orthogonal to the first direction (Z).

[0099] The PCB (20) has an extension along the second direction (X) higher than 2 mm and said top and bottom stiffening elements (56, 62) have an extension along the second direction (X) higher than 2 mm.

[0100] Both the top (56) and bottom (62) stiffening elements are at least partially embedded within the molded housing (14).

[0101] The top and bottom stiffening elements (56, 62) are in direct physical contact with the molded housing (14).

[0102] The PCB (20) has a first and a second PCB region (20a, 20b) having a first rigidity value and a third PCB region (35) having a second rigidity value higher than the first rigidity value.

[0103] Each of the first and second PCB regions (20a, 20b) comprises said stack structure, and the third PCB region comprises: said stack structure, a top stiffening element (56) on a first side of the stack structure, and a bottom stiffening element (62) on a second side of the stack structure, the second side being opposite the first side along the first direction (Z).

[0104] 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 be freely moved and / or bent.

[0105] 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 with respect to a resting condition of the PCB (20) without losing its functionality.

[0106] The top and bottom stiffening elements (56, 62) are films of polyimide material having respective thicknesses in the range 30-1500 pm along the first direction (Z).

[0107] The top and bottom stiffening elements (56, 62) are of at least one material from: FR4, IMS, polyimide, plastic material, aluminum, stainless steel, copper, alloys of aluminum, stainless steel, copper.

[0108] The top and bottom stiffening elements (56, 62) are of polyimide, of at least one material from: FR4, IMS, polyimide, plastic material, aluminum, stainless steel, copper, alloys of aluminum, stainless steel, copper.

[0109] The PCB (20) comprises a connector configured to be electrically connected to a further printed circuit board.

[0110] The stack structure of the PCB comprises at least a first conductive layer (44) sandwiched between two insulating layers (47, 58).

[0111] The stack structure of the PCB further comprises at least a second conductive layer (48) and an intermediate insulating layer (46) between the first and second conductive layers (44, 48), the first conductive layer (44), the second conductive layer (48) and the intermediate insulating layer (46) being sandwiched between said two insulating layers (47, 58).

[0112] The top and bottom stiffening elements (56, 62) are coupled to said stack structure of the PCB by respective adhesive films (54, 64).

[0113] A method of manufacturing a power device (10) comprising: a substrate (12) comprising an electrically conductive portion; a PCB (20) having a first PCB region having a stack structure of layers and / or films stacked along a first direction (Z); a second PCB region having said stack structure, said stack structure being locally delimited at a first side by a top stiffening element (56) and at a second side by a bottom stiffening element (62), the second side being opposite to the first side along the first direction (Z); and a third PCB region comprising said stack structure, wherein the first PCB region is electrically coupled between the rigid substrate (12) and a first end portion of the second PCB region, and the third PCB region is electrically coupled to a second end portion of the second PCB region, the second end portion being opposite to the first end portion, and wherein the top stiffening element and the bottom stiffening element are configured to locally increase the rigidity of the PCB (20) with respect to said first and third regions of the PCB (20) in the absence of said top and bottom stiffening 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 so as to define, for example, a first inner chamber (101), a second inner chamber (102) and a limiting region (104, 106a, 106b) comprising a first protrusion (106a) from the base element and a second protrusion (106b) from the cap element between the first and second inner chambers; arranging the power device (10) on a support portion within said base element so that the top stiffening element (56) corresponds to the first protrusion (106a) and the bottom stiffening element (62) corresponds to the second protrusion (106b); coupling the base element and the cap element together, exerting a pressure (P) on the top and bottom stiffening elements by means of the first and second protrusions (106a, 106b); injecting a resin (16) within 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).

[0114] The PCB (20) is profiled to comprise: a first PCB region (20a, 32); a second PCB region (20b, 36); a third PCB region (34); wherein the first, second and third PCB regions extend in a physically and electrically continuous manner with each other, the stack structure comprises a plurality of build-up layers along a first direction (Z), wherein each of the first and second PCB regions (20a, 20b) comprises the stack structure, and wherein the third PCB region comprises: the stack structure, a top stiffening element (56) on a first side of the stack structure, and a bottom stiffening element (62) on a second side of the stack structure, the second side being opposite the first side along the first direction (Z), the top and bottom stiffening elements being configured to locally increase a stiffness of the PCB (20) at the third PCB region.

[0115] The first (20a, 32) and second (20b, 36) PCB regions are of a flexible type.

[0116] The first (20a, 32) and second (20b, 36) PCB regions are configured to be bent up to at least 90 degrees or up to at least 180 degrees or up to 360 degrees with respect to a rest condition of the PCB (20) without losing its functionality.

[0117] The various embodiments described above can be combined to provide further embodiments. Various aspects of the embodiments can be modified as desired to employ concepts of various patents, applications, and publications to provide further embodiments.

[0118] These and other changes can be made to the embodiments in light of the above- described detailed description. In general, the selected terms used in the following claims are not to be construed as limiting the claims to the specific embodiments that were disclosed, but rather to include all possible embodiments and the scope of the claims shall cover all possible embodiments including such claims that are identical to those claimed below. Therefore, the claims are not limited to the disclosed embodiments.

Claims

1. A power device, characterized by, Comprising: a first portion comprising a rigid substrate having an electrically conductive portion; a second portion comprising a printed circuit board (PCB) having a stack of layers, the layers being piled along a first direction, the stack being electrically coupled to the rigid substrate at a coupling area; a molded housing embedding portions of the rigid substrate and of the PCB and having a side surface at which the PCB protrudes out of the molded housing, wherein, at the side surface of the molded housing, the stack of the PCB is locally bounded at a first side by a top stiffening element and at a second side by a bottom stiffening element, the second side being opposite to the first side along the first direction, the top stiffening element and the bottom stiffening element being configured to locally increase the rigidity of the PCB with respect to areas of the PCB where the top stiffening element and the bottom stiffening element are absent.

2. The power device of claim 1, wherein, the top stiffening element and the bottom stiffening element having extensions limited to a transition area of the PCB from an interior of the molded housing to an exterior of the molded housing.

3. The power device of claim 2, wherein, the PCB having an elongated shape having a main extension along a second direction, the second direction being orthogonal to the first direction.

4. The power device of claim 3, wherein, the PCB having an extension along the second direction higher than 2 mm and the top stiffening element and the bottom stiffening element having an extension along the second direction higher than 2 mm.

5. The power device of claim 1, wherein, both the top stiffening element and the bottom stiffening element being at least partially embedded within the molded housing.

6. The power device of claim 1, wherein, the top stiffening element and the bottom stiffening element being in direct physical contact with the molded housing.

7. The power device of claim 1, wherein, the PCB having a first PCB area and a second PCB area having a first rigidity value and a third PCB area having a second rigidity value, the second rigidity value being greater than the first rigidity value.

8. The power device of claim 7, wherein, each of the first PCB area and the second PCB area comprises the stack, and the third PCB area comprises the stack, the top stiffening element on a first side of the stack, and the bottom stiffening element on a second side of the stack, the second side being opposite to the first side along the first direction.

9. The power device of claim 7, wherein, the first PCB area being embedded within the molded housing and the second PCB area protruding out of the molded housing and being configured to be free to move or to bend.

10. The power device of claim 7, wherein, the first rigidity value enabling the second PCB area to be bent up to 90 degrees or 180 degrees or up to 360 degrees with respect to a rest condition of the PCB without losing the functionality of the PCB.

11. The power device of claim 1, wherein, Said top and bottom reinforcing elements are polyimide films having respective thicknesses in the range 30-1500 pm along said first direction.

12. The power device of claim 1, wherein, Said PCB comprises a connector configured to be electrically connected to a further printed circuit board.

13. The power device of claim 1, wherein, Said stack structure of said PCB comprises at least a first conductive layer sandwiched between two insulating layers.

14. The power device of claim 13, wherein, Said stack structure of said PCB comprises at least a second conductive layer and an intermediate insulating layer between said first and second conductive layers, Said first and second conductive layers and said intermediate insulating layer are sandwiched between said two insulating layers.

15. The power device of claim 1, wherein, Said top and bottom reinforcing elements are coupled to said stack structure of said PCB by respective adhesive films.

16. A PCB, characterized by Comprises: a first PCB region; a second PCB region; a third PCB region, wherein said first, second and third PCB regions extend in physical and electrical continuity with each other; and a stack structure comprising a plurality of stacked layers along a first direction, wherein each of said first and second PCB regions comprises said stack structure, and wherein said third PCB region comprises said stack structure, a top reinforcing element on a first side of said stack structure and a bottom reinforcing element on a second side of said stack structure opposite said first side along said first direction, said top and bottom reinforcing elements being configured to locally increase the stiffness of said PCB at said third PCB region.

17. The PCB of claim 16, wherein, Said first and second PCB regions are of the flexible type.

18. The PCB of claim 16, wherein, Said first and second PCB regions are configured to be bent up to at least 90 degrees or up to at least 180 degrees or up to 360 degrees with respect to a rest condition of said PCB without losing the functionality of said PCB. Said top and bottom reinforcing elements are polyimide films having respective thicknesses in the range 30-1500 pm along said first direction. Said PCB comprises a connector configured to be electrically connected to a further printed circuit board. Said stack structure of said PCB comprises at least a first conductive layer sandwiched between two insulating layers. Said stack structure of said PCB comprises at least a second conductive layer and an intermediate insulating layer between said first and second conductive layers, Said first and second conductive layers and said intermediate insulating layer are sandwiched between said two insulating layers. Said top and bottom reinforcing elements are coupled to said stack structure of said PCB by respective adhesive films. Comprises: a first PCB region; a second PCB region; a third PCB region, wherein said first, second and third PCB regions extend in physical and electrical continuity with each other; and a stack structure comprising a plurality of stacked layers along a first direction, wherein each of said first and second PCB regions comprises said stack structure, and wherein said third PCB region comprises said stack structure, a top reinforcing element on a first side of said stack structure and a bottom reinforcing element on a second side of said stack structure opposite said first side along said first direction, said top and bottom reinforcing elements being configured to locally increase the stiffness of said PCB at said third PCB region. Said first and second PCB regions are of the flexible type. Said first and second PCB regions are configured to be bent up to at least 90 degrees or up to at least 180 degrees or up to 360 degrees with respect to a rest condition of said PCB without losing the functionality of said PCB.

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