Encapsulating printed circuit board assemblies

Abstract

The present invention discloses a packaged printed circuit board (PCB) assembly (1) for electrically connecting to a high or medium voltage power conductor in a power distribution network, the packaged PCB assembly comprising: a) a PCB (10) defined by a peripheral edge (20) and comprising a high tension pad (60, 62) at a voltage of at least one kilovolt; b) an electrically insulating package body (70) in surface contact with and encapsulating the high tension pad and at least a portion of the PCB edge adjacent to the high tension pad, c) a shielding layer (80) located on an outer surface (90) of the package body and for maintaining electrical ground or low voltage to shield at least a low voltage portion of the PCB. The high tension pad extends to the peripheral edge of the PCB.

Description

Background Art

[0001] The present disclosure relates to a packaged printed circuit board in a high or medium voltage power distribution network, as well as a cable accessory and a network comprising such a packaged printed circuit board.

[0002] Sensing the voltage of power cables in a power distribution network is essential for maintaining the network in a stable state. Suitable voltage sensors typically use a voltage divider to sense the voltage of the cable. Certain types of these voltage dividers are electrically connected between a cable at a high or medium voltage (collectively referred to herein as "boosted voltage") and an electrical ground or a certain low voltage. The components of these voltage dividers, such as resistors or capacitors, are typically arranged on a printed circuit board ("PCB"). Some of these components are at boosted voltage, and the conductive traces connecting these components to each other and the contacts (such as solder contacts connecting these components to the PCB) are also at boosted voltage. The conductive traces and contacts on the main surface of the PCB, such as solder contacts (at boosted voltage when in use), are collectively referred to herein as "high tension pads".

[0003] Discharge through the air may occur between components at elevated voltage and components at electrical ground or low voltage. To reduce the risk of discharge, the PCB is typically encapsulated in a solid, insulating encapsulation body. Such an encapsulation body may, for example, be formed of a liquid resin that flows over the PCB, components at elevated voltage, and high tension pads while in liquid form, and then solidifies to form the encapsulation body.

[0004] The outer surface of such a package body is usually coated with a conductive layer that shields the PCB and the components thereon. The shield is primarily maintained at electrical ground potential, rarely at low voltage, and in either case a strong electric field exists between the high tension pads at elevated voltage and the shield. The smaller the package body, the closer the shield is to the high tension pads, and the stronger the field, the greater the probability of discharge.

[0005] While the high-tension pad is a conductive material (usually metal) and the PCB substrate ("PCB body") is primarily a fiber-reinforced plastic or ceramic material, the package body is typically made of a third type of material (usually a hardened epoxy material or a silicone rubber material). These different materials expand at different rates when heated, so that a void may be formed between the PCB body and the package body. The void is typically filled with air. In its length direction, such a void may extend along the surface of the PCB body (particularly along the edge of the PCB) and may be quite long (e.g., several millimeters). In its width direction (i.e., perpendicular to the surface of the PCB body), the void is smaller, extending only a few microns. In the case where the length direction of such an elongated void is oriented in a direction parallel to the electric field lines (i.e., away from the high-tension pad toward the shielding layer), the voltage difference between one end of the void and the opposite end of the void may be large enough to make discharge between these ends through the air in the void more likely. Such discharge may damage the PCB assembly and may cause the PCB assembly to fail in its intended use.

[0006] In order to reduce the risk of discharge through the gap between the high tension pad and the shielding layer, so-called stress control can be used (i.e., applying means to reduce the concentration of field lines near the high tension pad). An example of such stress control is described in US patent application US2006 / 0007624A1, in which a conductive surface coupled to a component under electrical stress is provided.

[0007] However, there is still a need to further reduce the possibility of discharge between the high tension pad and the shield layer, that is, to improve the voltage robustness of the package PCB assembly. A more robust PCB assembly can allow the size of the package body to be reduced and the space and weight of the assembly to be reduced while maintaining sufficient voltage robustness. Summary of the invention

[0008] To further enhance the voltage robustness of the packaged PCB in applications with elevated voltages, the inventors surprisingly discovered that discharge is less likely to occur with a specific arrangement of high tension pads on the PCB.

[0009] Accordingly, the present disclosure provides an encapsulated printed circuit board assembly for electrical connection to a high voltage or medium voltage power conductor in a power distribution network, the PCB assembly comprising:

[0010] a) a printed circuit board (PCB) defined by a peripheral edge and having a first major surface and an opposing second major surface and comprising a high tension pad on the first major surface, wherein in use, the high tension pad is at a voltage of at least one kilovolt,

[0011] b) an electrically insulating package body in surface contact with and encapsulating the high-tension pad and at least a portion of a peripheral edge adjacent to the high-tension pad,

[0012] c) a conductive low voltage shielding layer arranged on a first surface area of ​​an outer surface of the package body and used to be maintained at an electrical ground or low voltage to shield at least a low voltage portion of the PCB,

[0013] It is characterized by high tension pads extending to the peripheral edge of the PCB.

[0014] Tests have shown that discharges are less likely to occur in package PCB assemblies, especially after thermal cycling, where the high tension pads extend to the edge of the PCB. It is speculated that the geometry of the present invention prevents the formation of longer, elongated voids at the edge of the PCB that are oriented longitudinally along the field lines. By positioning the high tension pads at the edge, or equivalently by removing PCB substrate material from the initial edge of the PCB up to the high tension pads, the field lines between the high tension pads and the shielding layer do not extend along the surface of the PCB. Therefore, the long, elongated voids between the PCB and the package body that may be formed by thermal cycling may not extend longitudinally parallel to the field lines. The absence of such voids results in a reduced likelihood of discharges from the high tension pads to the low voltage shielding layer.

[0015] The present disclosure relates to PCB assemblies for use with MV or HV power distribution networks. In such networks, power is distributed via HV / MV cables, transformers, switchgear, substations, etc., with currents of hundreds of amperes and voltages of tens of kilovolts. As used herein, the term "medium voltage" or "MV" refers to an AC or DC voltage in the range of 1 kV to 72 kV, while the term "high voltage" or "HV" refers to an AC or DC voltage greater than 72 kV. Medium voltage and high voltage are collectively referred to herein as "boosted voltage".

[0016] A power conductor is an element in a power distribution network that conducts power over a specific distance, such as a buried or aerial power cable or a busbar or switch in a switchgear or transformer of a power distribution network. A power conductor is designed to transmit power at a voltage of 1 kV or more and at a current of 10 amperes or more.

[0017] A printed circuit board for use according to the present disclosure may generally be any of the many types of PCBs that exist. The PCB comprises a substrate, also referred to as a PCB body. Electrical elements, such as solder contacts, conductive traces, or electrical or electronic components, such as capacitors, resistors, inductors, or integrated circuits (ICs), may be arranged on the body, i.e., on an accessible major surface of the body or in the body. In particular, the PCB body may have varying degrees of flexibility, i.e., the PCB body may be a rigid PCB body or a flexible PCB body.

[0018] The PCB body can be made of different materials, for example, the PCB body can be a ceramic PCB body or a PCB body including a ceramic material. However, the PCB body can be made of or include more conventional materials such as FR4 or other fiber reinforced materials. In certain advantageous embodiments of the present packaged PCB assembly, the PCB includes a ceramic material, such as aluminum oxide or aluminum nitride.

[0019] The PCB body may be a single layer PCB body, or it may include multiple layers, for example to form a multilayer PCB. In a multilayer PCB, electrical components (eg, conductive traces) may be arranged in the PCB body between two adjacent layers of the multilayer PCB body.

[0020] The PCB may include a plurality of discrete impedance elements (such as discrete capacitors, discrete resistors, or discrete inductors) electrically connected in series with one another to form a voltage divider or a portion of a voltage divider for sensing the voltage of a power conductor to which the PCB assembly of the present disclosure may be connected. The discrete impedance elements may be arranged linearly in a chain ("voltage divider chain") configuration, such as in a straight chain or in a zigzag chain. A first end of the chain of discrete impedance elements may be electrically connected to a power conductor at an elevated voltage. A second, opposite end of the chain of discrete impedance elements may be electrically connected to an element that is electrically grounded or at a low voltage.

[0021] In certain embodiments, the PCB includes a plurality of discrete capacitors electrically connected in series with one another to form a voltage divider for sensing an AC voltage of a power conductor to which the PCB assembly of the present disclosure may be connected.

[0022] Capacitive voltage dividers are proven and cost-effective devices for dividing the boosted voltage of a power conductor. Capacitive voltage dividers can be used to divide voltage sensors to sense boosted voltage relative to electrical ground. Therefore, in certain embodiments, and independent of the features of other embodiments, the packaged PCB assembly according to the present disclosure also includes a plurality of discrete capacitors arranged on the PCB and electrically connected in series with each other so as to be able to operate as a voltage divider for sensing the boosted voltage of the high or medium voltage power conductor.

[0023] The PCB has two opposing parallel main surfaces, and its extension in the thickness direction is usually much smaller than its extension along the main surfaces. The PCB and the PCB body are defined by a peripheral edge. This edge forms the outer boundary of the main surface.

[0024] In certain embodiments of the PCB assembly described herein, the peripheral edge may have additional protrusions or recesses to provide a longer path for leakage current along the peripheral edge. Such additional protrusions or recesses may be particularly useful if arranged near the high tension pads or near any or all of the high tension pads.

[0025] Conductive traces and contacts on the major surfaces of the PCB, such as solder contacts, which are at elevated voltage when in use, are collectively referred to herein as "high tension pads". Specifically, solder contacts on the first major surface are referred to as high tension pads, which provide electrical connection and mechanical attachment of electrical components on the PCB and are at elevated voltage when in use. In the context of the present disclosure, the term "high tension" refers to high electrical potential, not to mechanical stress. The high tension pad may be, for example, a solder contact or solder pad, or a conductive trace on a major surface of a PCB that connects two electronic components.

[0026] In the thickness direction of the PCB, the high tension pads do not extend much on the main surface on which they are arranged, i.e. their thickness is small. The thickness of the high tension pads may, for example, be less than the thickness of the PCB body, or they may have a thickness of less than 2 mm, or less than 1 mm. Some preferred high tension pads may have a thickness between 35 μm (micrometers) and 200 μm. The thickness is measured perpendicular to the portion of the main surface of the PCB on which the high tension pads are arranged.

[0027] In the direction along the main surface, the high-tension pad may have dimensions ranging from a fraction of a square millimeter up to several square centimeters or even larger.

[0028] In the plane of the main surface in which the high-tension pad is arranged, the shape of the high-tension pad is not particularly limited. The high-tension pad may have, for example, a generally circular shape, an elliptical shape, a square shape, a rectangular shape, a triangular shape, or a hexagonal shape. The high-tension pad may have an irregular shape. In certain preferred embodiments, the high-tension pad has a rectangular shape with an aspect ratio of about 2: 1 (i.e., the long side of the rectangle is about twice as long as the short side). In embodiments in which the high-tension pad has a polygonal shape (e.g., a square, rectangle, triangle, hexagon, etc.), the corners of the polygon may be rounded. This helps to avoid field lines from concentrating at the corners and thereby further reduce the risk of discharge.

[0029] In some embodiments, one or all of the high-tension pads have a rectangular shape in which the corners are rounded with a radius equal to half the length of the short side of the rectangle. These high-tension pads have a rectangular shape in which the short sides form corresponding semicircles. In other embodiments, one or all of the high-tension pads have a rectangular shape in which the corners are rounded with a radius less than half the length of the short side of the rectangle (e.g., less than 50%, less than 40%, 30%, 20%, or less than 10% of the length of the short side of the rectangle).

[0030] Regardless of the shape of the peripheral edge of the PCB (e.g., generally straight or with protrusions or recesses as described below), it is generally desirable that the high tension pad not only extends to the peripheral edge of the PCB, but also extends a certain distance along the peripheral edge. If the peripheral edge of the PCB and the peripheral boundary of the high tension pad coincide by a certain distance (the distance is measured along their common edge), then the high tension pad extends that distance along the peripheral edge. In a preferred embodiment, the high tension pad extends a distance of 1 mm or more, 3 mm or more, 5 mm or more, or more than 10 mm along the peripheral edge.

[0031] In the case where the PCB as described herein includes the high tension pad and at least one additional high tension pad, each of the plurality of high tension pads may have the same shape. Alternatively, they may have different shapes. Regardless of the shape of the high tension pad, any additional high tension pad may have a shape as described herein.

[0032] In some embodiments, the high tension pad on the first major surface of the PCB extends to the second major surface.Then, the high tension pad includes a portion on the first major surface and another portion on the second major surface.

[0033] The electrical connection between the portion on the first major surface and the portion on the second major surface may be established in at least two different ways: through the PCB or via the edge of the PCB. The portion of the high tension pad on the first major surface may be electrically connected to the portion on the second major surface via a conductive plated through hole (a so-called "via") passing through the PCB. Alternatively, the two portions may be electrically connected via a conductive trace extending from the first major surface around the peripheral edge of the PCB to the second major surface.

[0034] Thus, generally speaking, in certain embodiments, the high-tension pad extends to the second major surface via a conductive trace formed through the PCB or via a conductive trace formed around a peripheral edge.

[0035] In certain embodiments of the packaged PCB assembly according to the present disclosure, the high tension pads extend only to the peripheral edge on the first major surface. In other embodiments, the high tension pads extend to the peripheral edge on the second major surface. In other embodiments of these embodiments, the high tension pads extend to the peripheral edge on both the first major surface and the second major surface.

[0036] The function of the package body is to reduce the risk of discharge between elements of the PCB at elevated voltage (such as high tension pads or electrical or electronic components at high voltage) and elements of the PCB at ground or at low voltage. Its function can also be to reduce the risk of discharge between elements of the PCB at elevated voltage and other elements at ground or at low voltage (such as the grounded shield of the PCB assembly or the grounded outer layer of the power conductor). The second function is to provide mechanical stability to the PCB assembly and to provide protection for the PCB, the high tension pads and the electronic components supported by the PCB from mechanical, chemical, physical or general environmental influences.

[0037] The package body is electrically insulating. The package body may be made of or include a material having a relative dielectric constant of 1.5 or more, at least 2, at least 3, or at least 5. Generally speaking, the relative dielectric constant of the material forming or included in the package body may be higher than the relative dielectric constant of air.

[0038] In certain embodiments, the encapsulated body is for example formed by hardenable liquid resin by molding, and this hardenable liquid resin solidifies to form the encapsulated body when hardening.In certain embodiments, the encapsulated body comprises cured resin (such as cured epoxy resin, polyurethane resin) or comprises cured silicone rubber.

[0039] In certain of these embodiments, the package body is formed, for example by molding, from a liquid resin that flows while liquid over the PCB, over components at elevated voltages, and over high-tension pads, and then solidifies to form the package body.

[0040] The package body may be in surface contact with at least a portion of the PCB and with at least a portion of the high-tension pad. In some embodiments, the package body is in surface contact with a portion of the PCB and with the high-tension pad.

[0041] In some embodiments, the package body encapsulates (i.e., encapsulates) a portion of the PCB. In some embodiments of these embodiments, the package body encapsulates the entire PCB. The package body can encapsulate the entire PCB and the entire high-tension pad. The wires can be connected to contacts on the PCB for electrically connecting the PCB to the MV / HV power conductor and / or electrically connected to electrical ground or lower voltage, and / or electrically connected to a processing unit. The processing unit can process a signal voltage generated on the PCB indicating the voltage of the power conductor relative to ground, and thereby sense the voltage of the power conductor.

[0042] The shape of the package body is not particularly limited. Advantageously, the shape of the package body corresponds to the shape of the PCB. For example, in the case where the PCB has an elongated straight shape, the package body may have an elongated straight shape.

[0043] Generally speaking, a smaller size of the package body saves space and reduces the amount of packaging material required. However, in a smaller package body, the low-voltage shielding layer on the outer surface of the package body is usually closer to the high-tension pad, which results in a stronger electric field between the pad and the shielding layer, thereby generating a higher risk of discharge. Therefore, in some embodiments, the package body is formed so that the distance between any part of the high-tension pad and any part of the low-voltage shielding layer is at least 2 mm, at least 3 mm, at least 5 mm, or at least 10 mm.

[0044] In a PCB assembly according to the present disclosure, a high tension pad extending to the peripheral edge of the PCB reduces the risk of discharge, allowing the package body to be smaller. Therefore, in certain embodiments, the geometric distance between any portion of the high tension pad and the nearest portion of the outer surface of the package body is twenty millimeters (mm) or less, 10 mm or less, 5 mm or less, or even 4 mm or less. In the case of a boost voltage of about 12 kV, the geometric distance between any portion of the high tension pad and the nearest portion of the outer surface of the package body is advantageously about 5 mm or less.

[0045] In many embodiments, the package body has an elongated shape. The elongated shape defines the length direction of the package body. In the case where the PCB has an elongated shape defining the length direction of the PCB, the PCB can be arranged in the package body so that the length direction of the PCB is parallel to the length direction of the package body.

[0046] In certain embodiments, the encapsulated body is shaped so that its outer surface has the same cross section everywhere along its length. In certain embodiments, the outer shape of the encapsulated body is cylindrical. In certain embodiments, the encapsulated body is shaped so that its outer surface has an oval cross section, a circular cross section or an elliptical cross section along its length. However, the encapsulated body may alternatively have an irregular shape.

[0047] The package body may be rigid, for example having an elongated shape and being rigid. Alternatively, the package body may be flexible. In most embodiments, the flexibility of the packaged PCB assembly (i.e., the PCB encapsulated in the package body) is less than the flexibility of the PCB alone when measured under the same conditions and in the same direction. Flexibility may be measured, for example, by determining the elastic modulus.

[0048] During years of use, the temperature of a PCB assembly according to the present disclosure may experience changes. In the case where the body of the PCB and the package body have significantly different thermal expansion coefficients, the changes in temperature may result in gaps and subsequent air voids between the PCB body and the package body. Such air voids in strong electric fields may result in electrical discharges that ultimately damage or destroy the PCB assembly.

[0049] Therefore, it is advantageous to manufacture the PCB body and the package body from materials having similar coefficients of thermal expansion. Therefore, in certain embodiments of the present PCB assembly, the package body includes a cured first material having a first coefficient of thermal expansion at 20°C, and the PCB includes a PCB body composed of a second material having a second coefficient of thermal expansion at 20°C, the first coefficient and the second coefficient being determined under the same conditions and using the same method, wherein the difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion is 50% or less of the value of the first coefficient of thermal expansion.

[0050] It may be advantageous to use ppm (1 / 10 6 ) / Kelvin temperature change (abbreviated as "ppm / K") represents the thermal expansion coefficient. Therefore, in certain embodiments, the package body includes a cured first material having a first thermal expansion coefficient (expressed in ppm / K) at 20°C, and the PCB includes a PCB body composed of a second material having a second thermal expansion coefficient (also expressed in ppm / K) at 20°C, the first coefficient and the second coefficient being determined under the same conditions and using the same method, wherein the difference between the first thermal expansion coefficient and the second thermal expansion coefficient is 40 ppm / K or less.

[0051] The PCB assembly according to the present disclosure includes a conductive low-voltage shielding layer arranged on a first surface area of ​​the outer surface of the package body. In use, the low-voltage shielding layer is maintained at an electrical ground or low voltage and shields the PCB and the high-tension pad. In the context of this patent application, low voltage refers to an AC voltage of 100 volts or less.

[0052] As will be described below, the PCB assembly may further include a second shielding layer, i.e., a boosted voltage shielding layer, arranged on a second surface area of ​​the outer surface of the package body. The first surface area and the second surface area do not overlap, i.e., the first surface area and the second surface area are separate surface areas of the outer surface of the package body.

[0053] In some embodiments of the present package PCB assembly, the low voltage shielding layer or any portion thereof is or includes a coating (e.g., a vapor deposition coating or a paint layer) on the outer surface of the package body. In other embodiments, the low voltage shielding layer is or includes a conductive foil wrapped around at least a portion of the outer surface of the package body.

[0054] Regardless of the nature of the low voltage shielding layer, in certain embodiments, the boosted voltage shielding layer or any portion thereof is also or includes a coating (e.g., a vapor deposited coating or a paint layer) on the outer surface of the package body. In other embodiments, the boosted voltage shielding layer is or includes a conductive foil wrapped around the outer surface of the package body.

[0055] The low voltage shielding layer or part thereof can be continuous or discontinuous. The discontinuous layer (part) can be patterned, i.e. it can have a plurality of non-conductive gaps. The gaps can occupy up to 50% of the surface area of ​​the low voltage shielding layer. Similarly, the boost voltage shielding layer or part thereof can also be continuous or discontinuous. The discontinuous layer (part) can be patterned, i.e. it can have a plurality of non-conductive gaps. The gaps can occupy up to 50% of the surface area of ​​the boost voltage shielding layer.

[0056] The low voltage shielding layer is electrically conductive. It may be composed of or contain an electrically conductive material, such as copper, silver, gold, aluminum, or another electrically conductive metal. In certain embodiments, the low voltage shielding layer comprises an electrically conductive polymer. In a specific embodiment, the low voltage shielding layer comprises an epoxy resin containing graphite. In different embodiments, the low voltage shielding layer comprises an electrically conductive silicone coating or an electrically conductive silicone paint. In a specific embodiment, the low voltage shielding layer comprises an electrically conductive wire mesh.

[0057] In the case where the PCB assembly includes a boosted voltage shielding layer, the boosted voltage shielding layer is conductive. It may be composed of or include a conductive material, such as copper, silver, gold, aluminum, or another conductive metal. In certain embodiments, the boosted voltage shielding layer includes a conductive polymer. In a specific embodiment, the boosted voltage shielding layer includes an epoxy resin containing graphite. In different embodiments, the boosted voltage shielding layer includes a conductive silicone coating or a conductive silicone paint. In a specific embodiment, the boosted voltage shielding layer includes a conductive wire mesh.

[0058] In certain embodiments, the low voltage shielding layer is arranged only on a first portion of the outer surface of the package body. A second portion (e.g., the remaining portion) of the outer surface of the package body may remain free of any shielding layer. In certain preferred embodiments, the low voltage shielding layer is arranged on a first portion of the outer surface of the package body, wherein the first portion encapsulates the entire PCB and the high tension pads. In other preferred embodiments, wherein the electrical or electronic components are arranged on the PCB, the low voltage shielding layer is arranged on a first portion of the outer surface of the package body, wherein the first portion encapsulates the electrical or electronic components on the PCB.

[0059] It may be desirable to provide a second boosted voltage shield layer, for example because the printed circuit board assembly of the present disclosure may form a voltage divider or part of a voltage divider for sensing the voltage of a power conductor. In such a voltage divider, a plurality of discrete impedance elements may be arranged on the PCB, the plurality of discrete impedance elements being electrically connected in series with each other between the boosted voltage of the power conductor and ground or a low voltage to divide the boosted voltage. Preferably, these voltage dividing discrete impedance elements are arranged linearly on the PCB in a chain-like configuration, thereby forming a chain of voltage divider elements or a "voltage divider chain" on the PCB. The boosted voltage end of the divider chain may be electrically connected to the power conductor, and the low voltage end of the divider chain may be electrically connected to ground or a low voltage.

[0060] In the voltage divider chain, the voltage of the discrete impedance elements at the boosted voltage end and the high tension pads for connecting these discrete impedance elements to each other and to the PCB is higher than the voltage of the discrete impedance elements at the low voltage end and the high tension pads for connecting these discrete impedance elements to each other and to the PCB because the boosted voltage is divided by the voltage divider chain so that the corresponding voltage decreases from one end of the chain to the other end.

[0061] In addition to forming a linear voltage divider, there may be other reasons to place electrical components at a boosted voltage on a first portion of the PCB (the boosted voltage portion of the PCB) and at a low voltage or ground on a second portion of the PCB (the low voltage portion of the PCB).

[0062] In order to reduce parasitic currents between the discrete impedance element or its high tension pad and the shielding layer, it has been found that it may be advantageous to separate the shielding layer into two conductive portions separated by an intermediate insulating gap on the outer surface of the package body. Therefore, in certain preferred embodiments of the present disclosure, a low voltage shielding layer is applied on the outer surface of the package body so as to encapsulate the low voltage portion of the PCB and maintain it at electrical ground or low voltage, and a boosted voltage shielding layer is applied on the outer surface of the package body to encapsulate the boosted voltage portion of the PCB and maintain it at high voltage.

[0063] Therefore, the electrical components on the low voltage portion of the PCB are shielded by the low voltage shielding layer at an electrical ground or low voltage, which reduces the voltage difference and parasitic current between the electrical components in the low voltage portion of the PCB and the low voltage shielding layer. Similarly, the electrical components on the boosted voltage portion of the PCB are shielded by the boosted voltage shielding layer at a boosted voltage, which reduces the voltage difference and parasitic current between the electrical components in the boosted voltage portion of the PCB and the boosted voltage shielding layer.

[0064] The low voltage shielding layer and the boosted voltage shielding layer are not applied on top of each other, but are applied side by side on separate surface areas of the outer surface of the package body. The middle surface area of ​​the outer surface of the package body encapsulating the PCB (i.e., the surface area of ​​the middle part of the encapsulating PCB between the boosted voltage part and the low voltage part of the PCB) is not provided with a shielding layer. This unshielded gap is necessary to avoid discharges between the boosted voltage shielding layer and the low voltage shielding layer.

[0065] Therefore, generally speaking, in certain embodiments of the PCB assembly according to the present disclosure, the packaged PCB assembly also includes a conductive boosted voltage shielding layer, which is arranged on the second surface area of ​​the outer surface of the package body, and is used to maintain a boosted voltage to shield at least the boosted voltage portion of the PCB; wherein the first surface area and the second surface area are separated by a third surface area, which is electrically insulating and does not contain a conductive layer, and is arranged between the first surface area and the second surface area, and is used to insulate the boosted voltage shielding layer from the low voltage shielding layer.

[0066] The boosted voltage shielding layer may be arranged and dimensioned to form a conductive envelope around the boosted voltage portion of the PCB.The low voltage shielding layer may be arranged and dimensioned to form a conductive envelope around the low voltage portion of the PCB.

[0067] In a specific embodiment, wherein the PCB has an elongated shape and is completely enclosed by the package body, and wherein the low voltage portion and the boosted voltage portion of the PCB are arranged at opposite end portions of the PCB, the boosted voltage shielding layer is arranged on a first surface area of ​​the outer surface of the package body so as to enclose the boosted voltage portion of the PCB. The low voltage shielding layer is arranged on a second surface area of ​​the outer surface of the package body so as to enclose the low voltage portion of the PCB. The first surface area and the second surface area are separated by a third surface area, the third surface area is electrically insulated and does not contain a conductive layer, is arranged between the first surface area and the second surface area, and is used to insulate the boosted voltage shielding layer from the low voltage shielding layer.

[0068] In use, there is a strong electric field between the edge portion of the low voltage shielding layer adjacent to one side of the third surface area and the edge portion of the boosted voltage shielding layer adjacent to the opposite side of the third surface area. In order to reduce the risk of discharge between these edge portions, the distance between them can be made larger, thereby increasing the size of the third surface area. Alternatively, the third surface area can be provided with an electrically insulating envelope. The envelope can be rigid. In this case, it can be made of, for example, another hardened resin. Alternatively, the envelope can be elastic, in which case it can be made of, for example, an insulating rubber material.

[0069] Generally, the insulating envelope may be disposed on the third surface area, but optionally also on the low voltage shielding layer or a portion thereof. Similarly, the insulating envelope may be disposed on the third surface area, but optionally also on the boosted voltage shielding layer or a portion thereof. The insulating envelope may be disposed on the third surface area, but optionally also on the low voltage shielding layer or a portion thereof and the boosted voltage shielding layer or a portion thereof. In certain embodiments, the insulating envelope may be disposed on the entire surface of the package body.

[0070] Thus, generally speaking, in certain embodiments, at least a portion of the package body is encapsulated by a rigid or resilient electrically insulating packaging envelope disposed on at least the third surface area.

[0071] In the case where a further reduction in electrical stress between the relative edges of the low voltage shielding layer and the boosted voltage shielding layer is desired, the edges can be shaped to form a geometric stress control surface. To this end, the shielding layer can extend onto the packaging envelope. The portion of the envelope supporting the corresponding edge of the shielding layer can be shaped so that the relative edges are appropriately shaped for geometric stress control.

[0072] In the case where the package body has an elongated shape, the shape defines a length direction and a radial direction orthogonal to the length direction. The low voltage shielding layer and the boosted voltage shielding layer may be spaced apart from each other in the length direction. The package envelope may then extend radially from the third surface portion so that the surface area of ​​the envelope may support the corresponding relative edge portions of the shielding layer. These surface areas of the envelope may be shaped so that the relative edge portions of the shielding layer extend in the radial direction and have a convex shape. The convex shape refers to that the central portions of the relative edge portions are closer to each other than the portions that are arranged radially more outward. In other words, from one edge portion, the relative edge portions have a convex shape. The convex shape can be used for geometric stress control between shielding layers.

[0073] Thus, in certain embodiments, the boosted voltage shielding layer extends onto a first surface portion of the package envelope, and wherein the low voltage shielding layer extends onto a second surface portion of the package envelope, and wherein each of the first surface portion and the second surface portion is shaped to reduce electrical stress between the boosted voltage shielding layer and the low voltage shielding layer. Suitable geometric stress control shapes are well known or can be found in standard textbooks.

[0074] It has been found that the risk of discharges starting from the high-tension pads is reduced if the electric field lines originating from the high-tension pads extend less along the exposed parts of the main surface of the PCB (i.e. the parts not covered by the high-tension pads). In other words: the high-tension pads are advantageously arranged on the protrusions of the peripheral edge of the PCB and extend to the peripheral edge of the protrusions.

[0075] Describing the same geometry another way, the high tension pad on the non-recessed portion of the peripheral edge is advantageously disposed proximate to the recessed portion of the peripheral edge of the PCB and extends to the peripheral edge in both the non-recessed portion and the recessed portion.

[0076] Therefore, in certain embodiments of the PCB assembly according to the present disclosure, the peripheral edge includes a recessed portion and a non-recessed portion connected to each other by the recessed portion in the plane of the PCB, and the high-tension pad extends to the peripheral edge in the non-recessed portion and to the peripheral edge in the recessed portion.

[0077] It is particularly advantageous to provide a recessed portion of the peripheral edge between two adjacent high-tension pads on the first main surface. In the case where two adjacent high-tension pads extend "laterally" (i.e. in a direction substantially along the peripheral edge) up to the recessed portion, a recessed portion helps to reduce the risk of discharge originating from any adjacent high-tension pad.

[0078] Therefore, in some embodiments, the PCB as described above includes a second high-tension pad, which is on the first major surface, adjacent to the (first) high-tension pad and extends to the peripheral edge of the PCB, wherein in use, the second high-tension pad is at a voltage of at least one thousand volts, and the peripheral edge includes a recessed portion arranged between the first high-tension pad and the second high-tension pad.

[0079] In certain embodiments, the peripheral edge of the PCB includes a recessed portion disposed between two adjacent high-tension pads, and the two adjacent high-tension pads extend to the recessed portion.

[0080] In certain embodiments that are particularly cost-effective to manufacture, the depression has a rectangular shape, a square shape, a triangular shape, a semicircular shape, or a trapezoidal shape.

[0081] In order to effectively reduce the risk of discharge, the recessed portion in the peripheral edge preferably has a width (i.e., an extension measured in the large-scale general direction of the peripheral edge) of at least one millimeter (mm), at least 2 mm, at least 3 mm, or at least 5 mm. In the case where the boost voltage is about 12 kV, and the recessed portion is arranged between the first high-tension pad and the second high-tension pad, the recessed portion preferably has a width of at least 3 mm.

[0082] Thus, in certain advantageous embodiments, the recess has a rectangular shape defined by a recessed portion of the peripheral edge and two opposing parallel recessed portions of the peripheral edge, wherein the width of the recess measured as the length of the shortest straight line between the recessed portions is one millimeter or greater.

[0083] In order to further effectively reduce the risk of discharge, the recessed portion in the peripheral edge preferably has a depth (i.e., an extension measured orthogonal to the large-scale general direction of the peripheral edge) of one millimeter (mm) or more, 2 mm or more, 3 mm or more, or 5 mm or more. In the case where the boost voltage is about 12 kV, and in the case where the recessed portion is arranged between the first high-tension pad and the second high-tension pad, the depth of the recessed portion is preferably 2 mm or more.

[0084] Thus, in certain advantageous embodiments, the recess has a rectangular shape defined by a recessed portion of the peripheral edge and two opposing parallel recessed portions of the peripheral edge, wherein a depth of the recess measured in a large-scale overall direction orthogonal to the peripheral edge is one millimeter or greater.

[0085] In the case where the PCB assembly forms a voltage divider or part of a voltage divider for sensing the elevated voltage of an MV / HV power conductor, a plurality of discrete impedance elements (i.e., discrete capacitors, discrete resistors, discrete inductors) may be arranged on the PCB and electrically connected in series with each other so as to be able to operate as a voltage divider. These impedance elements may be connected to the PCB via further solder contacts so that the PCB includes more than one high tension pad. In the case where an elevated voltage of about 12 kV is to be sensed, ten or more discrete impedance elements at elevated voltage may be used. In some available embodiments, the PCB has six or more high tension pads at a voltage of 1 kV or more. Advantageously, they all extend to the peripheral edge of the PCB. In order to reduce the risk of discharge, the package body covers each of these high tension pads.

[0086] Thus, in certain embodiments, the PCB of the packaged PCB assembly includes at least five additional high-tension pads on the first major surface, each of the additional high-tension pads being at a voltage of at least one thousand volts when in use and extending to a peripheral edge of the PCB, wherein the package body makes surface contact with and encapsulates each of the additional high-tension pads.

[0087] The packaged PCB assembly as described herein can be used as a component of a cable accessory for HV / MV power cables for power distribution networks. Such cable accessories can be, for example, cable terminals, cable joints, or pluggable connectors, such as elbow plugs or T-connectors used with switchgear and transformers. Such cable accessories typically include an insulating sleeve for placement around a power cable, wherein the cable can be partially stripped to expose a center conductor. To accommodate the PCB assembly, the accessory can have a cavity in the insulating sleeve.

[0088] The insulating sleeve may be or may include an electrically insulating rubber material, such as an insulating synthetic rubber or natural rubber, such as EPDM rubber (ethylene propylene diene monomer rubber) or a rubber containing silicone. The insulating sleeve may be an elastic sleeve. It may be elastically expandable or radially contractible. Some insulating sleeves may be elastic and radially contractible.

[0089] Therefore, the present disclosure also provides a cable accessory for use on a high voltage or medium voltage power cable in a power distribution network, comprising an insulating sleeve having a) a receiving space for receiving a section of the power cable so that the sleeve surrounds the power cable, and b) a cavity containing a PCB assembly as described herein.

[0090] The present disclosure also provides a power distribution network including high or medium voltage power conductors and a packaged PCB assembly electrically connected to the power conductors as described herein. In such a network, the packaged PCB assembly as described herein can be used to facilitate voltage sensing of the power conductors, which allows for better control of network performance, greater network operational safety, and therefore higher network availability and / or enhanced network performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] A PCB assembly according to the present disclosure will now be described in more detail with reference to the following drawings which illustrate specific embodiments of the present disclosure.In some of the drawings, certain dimensions and / or thicknesses are exaggerated for greater clarity.

[0092] Figure 1 a cross-section of a first PCB assembly according to the present disclosure;

[0093] Figure 2 a cross-section of a second PCB assembly according to the present disclosure;

[0094] Figure 3 a top view of a third PCB of a third PCB assembly according to the present disclosure;

[0095] Figure 4 a top view of a fourth PCB of a fourth PCB assembly according to the present disclosure;

[0096] Figure 5 a perspective view of a fifth PCB assembly according to the present disclosure;

[0097] Figure 6 a partial cross-section of a sixth PCB assembly according to the present disclosure;

[0098] Figure 7 A circuit diagram of a divided voltage sensor connected to an HV / MV power conductor; and

[0099] Figure 8A perspective view of a seventh PCB assembly according to the present disclosure including a packaging envelope. DETAILED DESCRIPTION

[0100] Figure 1 A first PCB assembly 1 according to the present disclosure is shown in cross-sectional view. The first PCB assembly 1 comprises a PCB 10 having a first major surface 30 and an opposing second major surface 40. The PCB 10 is bounded by a peripheral edge 20. The PCB 10 supports a plurality of electrical and electronic components 50, 51 on its first major surface 30, only two of which are Figure 1 These components 50, 51 are discrete capacitors 50, 51 which are electrically connected in series with each other to form a voltage divider or part of a voltage divider for sensing the voltage of a power conductor to which the PCB assembly 1 can be electrically connected.

[0101] The discrete capacitor 51 is attached to the first surface 30 and is electrically connected to other components by soldering at two soldering pads 60, 61. Similarly, the discrete capacitor 50 is attached to the first surface 30 and is electrically connected to other components by soldering at two soldering pads 61, 62. The pads 60, 61, 62 are at an elevated voltage of several kilovolts (kV) when in use, so they are also referred to herein as "high tension pads" 60, 61, 62. The high tension pads 60, 62 near the peripheral edge 20 of the PCB 10 extend all the way to the peripheral edge 20. Therefore, between the respective high tension pads 60, 62 and the edge 20 (the nearest part thereof), no part of the first main surface 30 is exposed.

[0102] The PCB 10 (including the electrical and electronic components 50, 51 and the high-tension pads 60, 61, 62) is packaged in an electrically insulating package body 70, which makes surface contact with the PCB 10, the high-tension pads 60, 61, 62 and the electrical and electronic components 50, 51. The package body 70 encloses the PCB 10, the high-tension pads 60, 61, 62 and the electrical and electronic components 50, 51 on all sides.

[0103] The conductive shielding layer 80 is disposed on the outer surface 90 of the package body 70. The shielding layer 80 is maintained at an electrical ground to shield the PCB 10, the high-tension pads 60, 61, 62, and the electric and electronic components 50, 51.

[0104] exist Figure 2 1 shows a second PCB assembly 2 according to the present disclosure in cross-sectional view. In addition to the high tension pads 160, 162 near the peripheral edge 20 of the PCB 10, the second PCB assembly 2 is Figure 1The high tension pad 160 of the second PCB assembly 2 extends from the first surface 30 through the PCB 10 to the second surface 40. The upper portion 170 of the high tension pad 160 is arranged on the first main surface 30, the lower portion 180 is arranged on the second main surface 40, and the conductive trace 190 (i.e., the through-hole portion 190) electrically connects the upper portion 170 with the lower portion 180 through the PCB 10 in the thickness direction of the PCB 10. The upper portion 170 of the high tension pad 160 covers a portion of the first surface 30 close to the edge 20 and extends to the peripheral edge 20 of the PCB 10 on the first surface 30. The lower portion 180 covers a portion of the second surface 40 close to the peripheral edge 20 and also extends to the edge 20 of the PCB 10 on the second surface 40.

[0105] Figure 3 An end portion of a third PCB 11 of a third PCB assembly according to the present disclosure is shown in top view. The package body and its shielding layer are not shown. The third PCB 11 is similar to the PCB 10 of the first PCB assembly 1, except that it carries only a single row of discrete capacitors 50, which are electrically connected in series to form a capacitive voltage divider for sensing the boosted voltage of the MV / HV power conductor.

[0106] On the left side of the PCB 11, it includes a high voltage contact 200 for connecting the PCB 11 to a power conductor at an elevated voltage. Conductive traces 210 on the first major surface 30 of the PCB 11 connect the high voltage contact 200 to the discrete capacitor 50 and connect the discrete capacitor 50 with adjacent capacitors 50 to form a chain of voltage-dividing capacitors 50 that can operate as a voltage divider for sensing the elevated voltage of the power conductor.

[0107] The PCB 11 has pads 60, 62, also referred to as high tension pads 60, 62, for connecting discrete capacitors 50 to the PCB 11. The high tension pads 60, 62 are arranged in two linear rows. The high tension pads 60 of the first row are arranged on the straight first portion 21 of the peripheral edge 20, and the high tension pads 62 of the second row are arranged on the opposite straight second portion 22 of the peripheral edge 20, so that a pair of two high tension pads 60, 62 are arranged opposite to each other on the first major surface 30. The capacitor 50 is soldered between two opposite high tension pads 60, 62, i.e., between one high tension pad 60 of the first row and the opposite high tension pad 62 of the second row.

[0108] For clarity, Figure 3 The right hand side of FIG. 1 shows only three capacitors 50 soldered to the PCB 11 , while the leftmost two pairs of high tension pads 60 , 62 are shown (before capacitors 50 are soldered therebetween).

[0109] Each of the high tension pads 60, 62 extends to the peripheral edge 20 of the PCB 11, similar to Figure 1 The contents shown in the cross section of PCB 10 in the first PCB assembly 1.

[0110] After connecting the missing two capacitors 50 to the two leftmost pairs of high tension pads 60, 62, Figure 3 The illustrated PCB 11 may then be packaged in a package body that makes surface contact with the high tension pads 60, 62, with exposed portions of the first major surface 30 and the opposing second major surface 40 of the PCB 11, and with the capacitor 50. Wires may electrically connect the high voltage contacts 200 to the power conductors.

[0111] exist Figure 4 A similar PCB 12 is shown in top view in FIG. Figure 3 The third PCB 11 of FIG. 1 is the same as the third PCB 11 of FIG. 1, except that its peripheral edge 20 includes an edge recess 220 between two corresponding adjacent non-recessed portions 240. Each of the non-recessed portions 240 supports a high-tension pad 60, 62 on the non-recessed portion 240 of the peripheral edge 20. The high-tension pads 60, 62 are arranged on the non-recessed portion 240 and extend to the peripheral edge 20. The edge recess 220 extends transversely (i.e., in the length direction of the PCB 12) up to the high-tension pads 60, 62, so that the high-tension pads 60, 62 extend up to the peripheral edge in the recess 220. The depth of the recess 220 (i.e., its extension in the width direction 230 of the PCB 12) is selected so that it is about 50% of the depth of the high-tension pads 60, 62 (extension in the width direction 230 of the PCB 12).

[0112] Alternatively, the same geometry can also be described such that the peripheral edge 20 comprises an edge protrusion 240 in the plane of the PCB 12, which carries the high-tension pads 60, 62. The high-tension pads 60, 62 extend up to the peripheral edge 20 of the edge protrusion 240. The extension of the protrusion 240 in the width direction 230 of the PCB 12 is selected such that about 50% of the depth (extension in the width direction 230 of the PCB 12) of the high-tension pads 60, 62 is arranged on the protrusion 240.

[0113] It is currently believed that providing the recesses 220 in the peripheral edge 20 between adjacent high-tension pads 60, 62 reduces the risk of electrical discharge between the high-tension pads 60, 62 and the shielding layer 80 due to fewer electric field lines from the high-tension pads 60, 62 toward the shielding layer 80 crossing the exposed surface of the first major surface 30 of the PCB 12. The package body 70 filling the recesses 220 between adjacent high-tension pads 60, 62 appears to reduce the risk of electrical discharge compared to the portion of the PCB body that fills the recesses 220.

[0114] Figure 5 A fifth PCB assembly 5 according to the present disclosure is shown in a perspective view. The PCB assembly 5 has an elongated shape and comprises a PCB 12 similar to Figure 4 The PCB 12 of the present invention has a peripheral edge 20 including a recessed portion 220 between two corresponding adjacent non-recessed portions 240 , and wherein the high-tension pad 60 on the first surface 30 is arranged on the non-recessed portion 240 and extends up to the peripheral edge 20 .

[0115] The PCB 12 supports twenty-eight discrete capacitors 50 arranged in two parallel rows and electrically connected in series so as to be operable as a voltage divider for sensing the power conductor 700 (to which the PCB assembly 5 can be connected via the high voltage contacts 200). Figure 7 The capacitor 50 is attached to the PCB 12 at the high tension pad 60. Figure 7 , the capacitor 50 forms a high voltage side 750 of the voltage divider, and the low voltage side 760 is arranged at the end portion of the PCB 12. The wires for connecting to the electrical ground and for transmitting the signal voltage to the external processing unit are led to the outside of the PCB assembly 5 through the cable 500.

[0116] The PCB 12 is encapsulated in an electrically insulating encapsulation body 70 of hardened resin, which makes surface contact with the capacitor 50, high tension pads 60 and peripheral edge 20 of the PCB 12. Figure 5 In the figure, for greater clarity, the package body 70 is drawn as transparent. However, it can be transparent, translucent or opaque as needed.

[0117] The outer surface 90 of the package body 70 includes three surface areas, which are arranged side by side and adjacent to their adjacent surface areas: the first surface area 510 is provided with a conductive low-voltage shielding layer 80, the second surface area 520 is provided with a conductive increased-voltage shielding layer 550, and the third surface area 530 without a conductive layer is arranged between the first surface area 510 and the second surface area 520 and separates these surface areas 510 and 520.

[0118] The first surface area 510 and the second surface area 520 are electrically insulated from each other by the third surface area 530. In use, the low voltage shielding layer 80 and the boosted voltage shielding layer 550 are maintained at different voltages: the low voltage shielding layer 80 is maintained at electrical ground, while the boosted voltage shielding layer 550 is maintained at the boosted AC voltage of the power conductor. The latter is achieved by a protrusion of the high voltage contact 200, which extends inside the package body 70 to the outer surface 90 of the package body 70 to contact the boosted voltage shielding layer 550.

[0119] Both the boosted voltage shield 550 and the low voltage shield 80 are formed of conductive paint applied respectively to the first surface area 510 and the second surface area 520. Likewise, the shields 80, 50 are drawn as transparent for clarity only and may actually be transparent, translucent or opaque.

[0120] The low voltage shielding layer 80 encapsulates and thereby shields those discrete capacitors 50 on the low voltage portion 560 of the PCB 12. Correspondingly, the boosted voltage shielding layer 550 encapsulates and thereby shields those discrete capacitors 50 on the boosted voltage portion 570 of the PCB 12.

[0121] Figure 5 The PCB assembly 5 shown has a substantially oval cross section, a length of about 20 cm and a width of about 2.5 cm. The extension of the third surface area 530 in the length direction is about 5 cm.

[0122] Figure 6 A portion of a sixth PCB assembly 6 according to the present disclosure is shown in cross-sectional view. The sixth PCB assembly 6 and Figure 2 The second PCB assembly 2 shown is identical except that the lower portion 180 of the high-tension pad 164 is electrically connected to the upper portion 170 via an edge cover portion 600 rather than a through-hole portion 190. Both the upper portion 170 on the first major surface 30 and the lower portion 180 on the second major surface 40 extend to the peripheral edge 20 of the PCB 10. The edge cover portion 600 of the high-tension pad 164 is formed by a conductive trace that extends between the upper portion 170 and the lower portion 180 around the edge 20 (i.e., above the edge surface).

[0123] Figure 7 7 is a simplified circuit diagram for illustrating the use of a packaged PCB assembly according to the present disclosure. A medium voltage power cable 700 is shown in perspective view with its insulation layer 710 partially removed to expose a center conductor 720. Cable 700 is an example of a power conductor 700 in a power distribution network. In use, center conductor 720 is at a boosted AC voltage of tens of kilovolts and can conduct tens of amperes of current. Figure 7In the right portion of the circuit diagram, a voltage divider 730 is electrically connected between the boosted voltage of the center conductor 720 and ground 740 .

[0124] The voltage divider 730 includes a plurality of discrete voltage-dividing capacitors 50 electrically connected in series with each other so that the voltage divider 730 can sense the boosted voltage of the power cable 700. The capacitors 50 connected to the boosted voltage form the high-voltage side 750 of the voltage divider 730, and the low-voltage side 760 is formed by a single discrete capacitor 59. A pick-up contact 770 is electrically connected between the high-voltage side 750 and the low-voltage side 760. A divided voltage can be picked up at the pick-up contact 770, which varies in proportion to the voltage of the power cable 700. The proportionality factor between the boosted voltage and the divided voltage is determined by the ratio of the total impedance of the high-voltage side 750 and the low-voltage side 760. By determining the divided voltage at the pick-up contact 770, the boosted voltage of the power cable 700 can be sensed.

[0125] The packaged PCB assembly 1, 2, 5, 6, 7 disclosed herein may include an entire voltage divider 730 (eg, Figure 7 ), or alternatively only includes the high voltage side 750 of the voltage divider 730. The voltage dividing capacitor 50 can be arranged on the PCB 10, for example, as Figure 1 shown.

[0126] Figure 8 A seventh PCB assembly 7 according to the present disclosure is shown in a perspective view. PCB 10 is similar to Figure 1 The PCB 10 shown in the figure has a high tension pad 60 extending to the peripheral edge 20 of the PCB 10. The PCB 10 is encapsulated in a package body 70, which is drawn as if it is transparent. The boosted voltage shielding layer 550 is arranged on a first surface area of ​​the package body 70, and the low voltage shielding layer 80 is arranged on a second surface area of ​​the package body 70. The third surface area is arranged between the first surface area and the second surface area. It is not visible because a rigid electrically insulating packaging envelope 800 is arranged on it. It is made of hardened resin and insulates the low voltage shielding layer 80 from the boosted voltage shielding layer 550 from each other, and the degree of insulation is better than the degree to which air insulates the low voltage shielding layer from each other, thereby reducing the risk of discharge between the shielding layers 80 and 550.

[0127] The envelope 800 has a generally cylindrical shape, having a first end face 810 of three-dimensional curvature and a similarly shaped opposite end face 820. Its end faces 810, 820 are not flat, but each of them has a convex shape. The end portion of the low-voltage shielding layer 80 extends on the second end face 820 and covers all the end faces 820, so that the end portion of the low-voltage shielding layer 80 has the convex shape of the second end face 820 of the envelope 800. Similarly, the end portion of the boost voltage shielding layer 550 extends to the first end face 810 of the envelope 800 and covers the entire first end face 810, so that the end portion of the boost voltage shielding layer 550 has the convex shape of the first end face 810 of the envelope 800. The relative convex shapes of the shielding layers 80, 550 form a geometric stress control component, and contribute to reducing the risk of discharge between the relative parts. Therefore, the relative end portions of the respective shielding layers 80, 550 are shaped to reduce the electrical stress between them.

Claims

1. A packaged printed circuit board assembly (1, 2, 5, 6, 7) for electrical connection to a high voltage or medium voltage power conductor (700) in a power distribution network, the printed circuit board assembly comprising: a) a printed circuit board (10, 11, 12) defined by a peripheral edge (20) and having a first major surface (30) and an opposing second major surface (40) and comprising a high tension pad (60, 62, 160, 162, 164) on the first major surface, wherein in use the high tension pad is at a voltage of at least one kilovolt, b) an electrically insulating package body (70) in surface contact with and encapsulating the high-tension pad and at least a portion of the peripheral edge adjacent to the high-tension pad, c) a conductive low voltage shielding layer (80) arranged on a first surface area (510) of an outer surface (90) of the package body and used to be maintained at an electrical ground or low voltage to shield at least a low voltage portion (560) of the printed circuit board, Wherein, the high tension pad (60, 62, 160, 162, 164) extends to the peripheral edge (20) of the printed circuit board (10, 11, 12).

2. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1, wherein the peripheral edge (20) includes a recessed portion and a non-recessed portion (240) connected to each other by a recessed portion in the plane of the printed circuit board, and wherein the high-tension pad (60, 62, 160, 162, 164) extends to the peripheral edge (20) in the non-recessed portion (240) and to the peripheral edge (20) in the recessed portion.

3. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1, wherein: The high tension pads (60, 62, 160, 162, 164) include a first high tension pad and a second high tension pad, wherein the second high tension pad is located on the first main surface (30), adjacent to the first high tension pad and extends to the peripheral edge (20) of the printed circuit board, wherein the peripheral edge includes a recessed portion (220) disposed between the first high tension pad and the second high tension pad.

4. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 3, wherein the recessed portion (220) has a rectangular shape, a triangular shape, a semicircular shape or a trapezoidal shape.

5. A packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 4, wherein the recess (220) has a rectangular shape, the recess (220) being defined by a recessed portion of the peripheral edge (20) and two opposite parallel recessed portions of the peripheral edge, wherein the width of the recess (220) measured as the length of the shortest straight line between the recessed portions is one millimeter or greater.

6. The packaged printed circuit board assembly (1, 2, 5, 6, 7) of claim 1, wherein the high-tension pad (60, 62, 160, 162, 164) extends to the second major surface (40) via a conductive trace (190) formed within the printed circuit board or via a conductive trace (600) formed around a peripheral edge (20) of the printed circuit board.

7. The packaged printed circuit board assembly (1, 2, 5, 6, 7) of claim 6, wherein the high tension pad (60, 62, 160, 162, 164) extends to the peripheral edge (20) on the second major surface (40).

8. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1, further comprising a plurality of discrete capacitors (50), which are arranged on the printed circuit board (10, 11, 12) and are electrically connected in series with each other so as to be able to operate as a voltage divider for sensing the boosted voltage of the high or medium voltage power conductor (700).

9. The packaged printed circuit board assembly (1, 2, 5, 6, 7) of claim 1, wherein a geometric distance between any portion of the high-tension pad (60, 62, 160, 162, 164) and a nearest portion of the outer surface (90) of the package body (70) is twenty millimeters or less.

10. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1, wherein the package body (70) includes a cured first material having a first thermal expansion coefficient at 20°C, and wherein the printed circuit board (10, 11, 12) includes a printed circuit board body composed of a second material having a second thermal expansion coefficient at 20°C, the first thermal expansion coefficient and the second thermal expansion coefficient being determined under the same conditions and using the same method, wherein the difference between the first thermal expansion coefficient and the second thermal expansion coefficient is 50% or less of the value of the first thermal expansion coefficient.

11. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1, further comprising a conductive boosted voltage shielding layer (550) disposed on a second surface area (520) of the outer surface (90) of the package body (70) for being maintained at a boosted voltage to shield at least a boosted voltage portion (570) of the printed circuit board; The first surface area (510) and the second surface area (520) are separated by a third surface area (530), which is electrically insulating and does not contain a conductive layer, is arranged between the first surface area (510) and the second surface area (520), and is used to insulate the boosted voltage shielding layer (550) from the low voltage shielding layer (80).

12. The packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 11, wherein at least a portion of the package body (70) is encapsulated by a rigid or elastic electrically insulating package envelope (800) arranged on at least the third surface area (530).

13. A packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 12, wherein the boosted voltage shielding layer (550) extends onto a first surface portion (810) of the package envelope (800), and wherein the low voltage shielding layer (80) extends onto a second surface portion (820) of the package envelope (800), and wherein each of the first surface portion (810) and the second surface portion (820) is shaped so as to reduce electrical stress between the boosted voltage shielding layer (550) and the low voltage shielding layer (80).

14. A cable accessory for use on a high voltage or medium voltage power cable (700) in a power distribution network, the cable accessory comprising an insulating sleeve, the insulating sleeve having: a) a receiving space for receiving a section of the power cable such that the sleeve surrounds the power cable, and b) A cavity containing the encapsulated printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1.

15. A power distribution network comprising a high or medium voltage power conductor (700) and a packaged printed circuit board assembly (1, 2, 5, 6, 7) according to claim 1, the packaged printed circuit board assembly being electrically connected to the power conductor.

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