Planar transformer with improved reliability

Abstract

The invention relates to a planar transformer with improved reliability. A galvanic insulation device includes: an upper coil in a first insulating layer; a lower coil in the second insulating layer; a current insulating region extending between the first insulating layer and the second insulating layer; and a first conductive via. Each of the upper coil and the lower coil includes a turn, a first electrical contact region and a second electrical contact region electrically coupled to the turn. A first conductive via is coupled to the first structural portion of the lower coil (2b), to the turn or to the first or second electrical contact area. The first structural portion includes a first stress dissipation region having a curved shape and not aligned with the upper coil.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a planar transformer with improved reliability. In detail, it relates to a galvanic insulation device and to an electronic device comprising the same. BACKGROUND

[0002] Transformers are widely used in various application fields, such as galvanic insulation, signal transfer and energy transfer. For example, in the field of galvanic insulation, integrated transformers are key components of many modern electronic products that need to exchange data and / or transfer energy between two galvanically insulated domains, such as medical devices, motor controllers and communication devices.

[0003] Commercial systems often use a variety of coupling methods, which include inductive coupling based on planar transformers (i.e. coils lying on respective planes parallel to each other). There are many reasons for this choice, and they include, for example, protection against voltages and currents.

[0004] In planar transformers, the coils are made of electrically conductive material, in particular metallic material such as gold, and are vertically spaced apart from each other and galvanically decoupled by one or more layers of dielectric material, in particular polymeric material such as polyimide (PIX).

[0005] Typically, the thermal expansion coefficients (CTEs) of the coils and of the layers of dielectric material are significantly different from each other. Therefore, the production of these transformers is critical, as the manufacturing steps, including thermal cycles (i.e. repeated significant temperature variations), can damage these devices.

[0006] In fact, during the production of the transformer (for example during the hardening / thermal annealing step), the high CTE difference causes a high concentration of mechanical stress at the interface between the coils and the dielectric material. This can cause breakdown, delamination of the dielectric layer, separation of the metal area at the conductive via, and more generally breakdown or failure of the transformer.

[0007] Similar risks also exist during the operation of the device, in particular in the case of transformers for energy transfer / management (for example integrated transformers), which can be subjected to self-heating during use.

[0008] A known solution to this problem involves the use of materials with a lower CTE difference. However, this complicates the design of the transformer, introduces greater design constraints and generally reduces their electrical performance.

[0009] Other known solutions involve manufacturing the transformer through techniques that limit the number and extent of thermal cycles. However, this complicates the production of the transformer and generally worsens its final structure, thus reducing its electrical performance.

[0010] Moreover, current insulation devices need to withstand high voltage differences both in short periods (for example during breakdown voltage tests) and in long periods (i.e. during the expected lifetime). However, when the polymer materials previously mentioned are used as insulation and / or passivation layers, it is difficult to obtain an optimal thickness uniformity within the tube. This means that, in practice, the thickness of the polyimide between the upper coil and the lower coil usually has significant variations along the horizontal plane (in detail, the thickness in the central portion of the transformer is greater than the thickness in the extreme portions, causing the transformer to assume a "dome" shape in cross section).

[0011] The non-planarity of the insulating polymer layer between the two coils requires the upper coil to also follow a "dome" profile in cross section. This means that in the outermost regions of the transformer, the distance of the upper coil from the lower coil is reduced with respect to the distance between the two coils at the center of the transformer. The reduction of the distance between the coils at the respective outer turns generates an unwanted increase of the electric field between the coils, which contributes to the formation of discharges between the coils at the outer turns, determining the failure of the device. This thickness non-uniformity is caused, for example, by the manufacturing process of the transformer, in particular by the pyramidal multi-coating step.

[0012] Therefore, there is a need for an insulating polymer material of uniform thickness to allow voltage insulation both with respect to short voltage pulses and during the lifetime of the transformer. In fact, in current insulation devices comprising a PIX, a non-uniformity of the thickness of the PIX layer can cause premature breakdown phenomena, reduced electrical performance and reduced lifetime of the device. SUMMARY

[0013] The present disclosure relates to providing a current insulation device and an electronic device comprising the same, which overcomes the drawbacks of the prior art.

[0014] According to the present disclosure, a current insulation device and an electronic device comprising the same are provided. BRIEF DESCRIPTION OF DRAWINGS

[0015] For a better understanding of the present disclosure, some embodiments are now described, by way of non-limiting example only, with reference to the accompanying drawings in which:

[0016] Figure 1 a circuit comprising a current insulation device, in particular a transformer, is shown;

[0017] Figure 2 a portion of a current insulation device according to an embodiment of the present disclosure is illustrated in a purely qualitative lateral cross-sectional view; Figure 1 a portion of a current insulation device according to an embodiment of the present disclosure is illustrated in a purely qualitative lateral cross-sectional view;

[0018] Figure 3 a current insulation device according to an embodiment of the present disclosure is shown in a top view; Figure 2a primary winding of a current-insulating device; and

[0019] Figures 4 to 7 a current-insulating device according to respective embodiments of the present disclosure is shown in a top view Figure 2 a secondary winding of a current-insulating device.

[0020] In particular, the drawings refer to a three-axial Cartesian system defined by an X-axis, a Y-axis and a Z-axis, which are orthogonal to each other.

[0021] In the following description, elements common to different embodiments are indicated with the same reference numerals. DETAILED DESCRIPTION

[0022] The present disclosure finds use in current-insulating devices, in particular planar transformers, implemented in PCB substrates comprising a plurality of stacked dielectric layers, as well as in current-insulating devices, in particular planar transformers, made by using MEMS manufacturing techniques based on semiconductor substrate processing. The present disclosure can also be applied to planar transformers integrated into semiconductor structures (wafers, chips or dies) housing a plurality of electronic devices.

[0023] Figure 1 The equivalent circuit of Fig. 1 shows a current-insulating device, in particular a transformer 2, which can be used for power transmission and / or conversion from an input port (input power Pl applied) to an output port (output power P2 generated). Thus, in use, power can be transferred through the transformer 2, or signals converted between two different voltage levels using the transformer 2.

[0024] During use, the input power Pl is supplied to the primary winding 2a; the secondary winding 2b is coupled to the primary winding 2a and generates the output power P2 according to the transformation ratio in a manner known per se.

[0025] In the following, the terms "coil" and "winding" are used synonymously and interchangeably. The term "turn" identifies a single coil turn or winding loop of a spiral coil.

[0026] The primary winding 2a and the secondary winding 2b are electrically insulated from each other, but magnetically connected, to allow the transfer of power or electrical signals from one winding to the other (and thus through the current induced by the cascading magnetic flux between the two windings). For this purpose, there can be a common core 3.

[0027] When an electric current flows through the turns of the primary coil 2a, a magnetic field is generated, which induces a voltage in the turns of the secondary coil 2b. In use, the primary coil 2a of the transformer 2 is coupled to an input power voltage generator (not shown) and converts (or transforms) the power PI provided by the generator into a magnetic field; the secondary coil 2b converts the magnetic field into a power P2 that generates an output voltage. This possible application of the transformer 2 is illustrated for illustrative purposes only and does not limit the present disclosure.

[0028] With reference to Figure 2 , a portion of the electronic device or electronic assembly 1 is illustrated in a lateral cross-sectional view and in a three-axial reference system X, Y, Z.

[0029] The electronic device 1 comprises a current insulation device 2. In particular, the current insulation device 2 can be a transformer, and therefore in the following it is also referred to as transformer 2.

[0030] The transformer 2 is of the planar type (i.e., it has coils 2a and 2b lying on respective planes parallel to each other and to the XY plane, also called lying planes).

[0031] Figure 2 Purely qualitatively, and illustrating various elements of the transformer 2, it is not necessarily visible along the same cross-sectional line. Figure 3 and 4

[0032] Considering the extension of the transformer 2 along the Z axis (orthogonal to the XY plane), the transformer 2 comprises an upper coil (in this example, the primary coil 2a) and a lower coil (in this example, the secondary coil 2b) extending into a first insulating layer 8 and a second insulating layer 9, respectively, of electrically insulating material or dielectric material (in detail, a polymeric material, such as PIX).

[0033] The coils 2a and 2b are vertically aligned with each other, i.e., along the Z axis.

[0034] The coils 2a and 2b are formed, respectively, by a respective plurality of turns 4, 5. It is clear that the number of turns is selected based on the needs of the application in which the transformer 2 is used or designed, and is selected in the design step in a manner known per se, for example in a number equal to or greater than 2, for example comprised between 2 and 30.

[0035] The primary coil 2a and the secondary coil 2b extend along the Z axis from each other by a distance dB, separated from each other by one or more insulating layers of electrically insulating material or dielectric material (in detail, a polymeric material, such as PIX), which forms a current insulation region 11. The thickness of this current insulation region 11 along the Z axis can be a few tens of microns, for example comprised between 20 and 60 pm, for example 40 pm.

[0036] ​The primary coil 2a and the secondary coil 2b comprise respective turns 4, 5 extending according to a spiral path parallel to the XY plane.

[0037] A first upper electrical contact area 4a, made of a metallic material (e.g. copper or gold), extends coplanarly (i.e. on the same metal level) with the turns 4 of the primary coil 2a, within the turns 4 of the primary coil 2a. The first upper electrical contact area 4a is electrically coupled to the turns 4 of the primary coil 2a. More particularly, the first upper electrical contact area 4a is electrically coupled to the innermost turns 4’ of the primary coil 2a.

[0038] Similarly, a second upper electrical contact area 4b, made of a metallic material (e.g. copper or gold), extends coplanarly with the turns of the primary coil 2a, outside the turns of the primary coil 2a; the second upper electrical contact area 4b is electrically coupled to the turns of the primary winding 2a, in particular to the outermost turns 4”.

[0039] The first and second upper electrical contact areas (or pads) 4a, 4b are configured to be electrically contacted in order to bias the respective primary coil 2a with a primary biasing voltage, as discussed with reference to Figure 1 .

[0040] The secondary coil 2b also has two lower electrical contact areas (or pads) 5a, 5b (hereinafter first lower electrical contact area 5a and second lower electrical contact area 5b, respectively), configured to be electrically contacted in order to bias the secondary coil 2b with a secondary biasing voltage.

[0041] Both the first lower electrical contact area 5a and the second lower electrical contact area 5b extend outside the turns 5 of the secondary coil 2b.

[0042] In order to form a suitable electrical connection between the innermost turns (or inner turns) 5’ of the secondary coil 2b and the first lower electrical contact area 5a, an electrically conductive track 13 extends to a metal level different from the metal level in which the secondary coil 2b extends (also referred to as “cross-under” metal level). In particular, the electrically conductive track 13 extends at the bottom of the secondary coil 2b, considering the Z axis as the vertical axis. For example, the electrically conductive track 13 is the same material as the secondary coil 2b.

[0043] The outermost turns (or outer turns) 5” of the secondary coil 2b are electrically connected to the second lower electrical contact area 5b, for example through a first joint portion 38 which is continuous with the second lower electrical contact area 5b and with the first end of the secondary coil 2b (in detail, with the outer end of the turns 5), and can be the same material as the second lower electrical contact area 5b and the secondary coil 2b. In this case, in fact, it is not necessary to use a metal level different from the metal level in which the secondary coil 2b is formed to form the connection track between the outermost turns and the second lower electrical contact area 5b.

[0044] It is clear that, in order to avoid short circuits between the electrically conductive track 13 and all the turns of the secondary coil 2b, the electrically conductive track 13 is electrically insulated from the secondary coil 2b (except for the innermost turn of the secondary coil 2b) by means of the interposed insulating layer 12 (in particular of the same material as the current insulation region 11).

[0045] By means of the interposed insulating layer 12, a first electrically conductive via 15 is formed, which vertically (i.e. along the Z axis) connects the innermost turn 5’ and the electrically conductive track 13, and a second electrically conductive via 18, which vertically connects the electrically conductive track 13 and the first lower electrical contact region 5a. In particular, the electrically conductive vias 15 and 18 are of the same material as the secondary coil 2b and the electrically conductive track 13.

[0046] In detail, the innermost turn 5’ is connected to a first end 13’ of the electrically conductive track 13 by means of the first electrically conductive via 15, while the first lower electrical contact region 5a is connected to a second end 13” of the electrically conductive track 13, opposite the first end 13’, by means of the second electrically conductive via 18.

[0047] In more detail, the innermost turn 5’ of the secondary coil 2b has a first structural portion 28, which defines a second end of the secondary coil 2b (in detail, an end or inner end located inside the turn 5).

[0048] The first structural portion 28 comprises a first connection region 20, which is vertically superimposed (i.e. superimposed along the Z axis) on the first electrically conductive via 15. In particular, the first connection region 20 and the first electrically conductive via 15 are continuous with each other.

[0049] As Figure 4 Better shown, the first lower electrical contact region 5a is comprised in a lower electrical contact conductive region 32 of the secondary coil 2b, which is coplanar with the turn 5, physically separated from the turn 5 (i.e. it does not make direct physical contact with the turn 5), and electrically connected to the turn 5 by means of the electrically conductive track 13 and the electrically conductive vias 15 and 18.

[0050] In addition to the first lower electrical contact region 5a, the lower electrical contact conductive region 32 comprises a second structural portion 30, described in more detail below.

[0051] The first lower electrical contact region 5a and the second structural portion 30 are joined together, for example, by means of a second joint portion 34 of the lower electrical contact conductive region 32. The second joint portion 34 extends between the first lower electrical contact region 5a and the second structural portion 30, extending in a manner continuous with both. In detail, the first lower electrical contact region 5a, the second joint portion 34 and the second structural portion 30 are made of the same electrically conductive material (for example, copper or gold).

[0052] The second structural portion 30 comprises a second connection region 22 which is vertically superimposed on the second conductive via 18. In particular, the second connection region 22 and the second conductive via 18 are continuous with each other.

[0053] The turns of each coil 2a, 2b are arranged in electrical continuity between two respective end portions 4a, 4b and 5a, 5b to form a respective spiral. The present disclosure includes any spiral shape, including circular spirals, quadrangular spirals and polygonal spirals, in particular with rounded corners.

[0054] In the radial direction (i.e. along an axis which is coplanar with the respective coil 2a, 2b under consideration and passes through the center of the respective coil 2a and 2b, as Figure 4 indicated with reference number 36), a portion of the first or second insulating layer 8, 9 of electrically insulating or dielectric material (in detail, a polymeric material, such as PIX) extends between the turns of each respective coil 2a, 2b.

[0055] The magnetic core 3 Figure 2 (not illustrated in the drawings) can optionally be present at the central region of the coils 2a, 2b, i.e. the region internally delimited by the innermost turns of the coils 2a, 2b.

[0056] Figure 3 is a plan view (on the XY plane) of the primary coil 2a of the transformer 2 according to an exemplary embodiment.

[0057] In the example illustrated in Figure 3 , the primary coil 2a has turns 4 which, in the radial direction, have a uniform and constant width by way of example. However, the turns 4 can also have a variable width. Moreover, the turns 4 of the primary coil 2a can have a shape different from the circular one illustrated (for example quadrangular turns, etc.). Figure 3

[0058] Figure 4 is a plan view (on the XY plane) of the secondary coil 2b of the transformer 2 according to an exemplary embodiment.

[0059] In the example illustrated in Figure 4 , the secondary coil 2b has turns 5 which, in the radial direction, have a uniform and constant width by way of example. However, the turns 5 can also have a variable width. Moreover, the turns 5 of the primary coil 2b can have a shape different from the circular one illustrated (for example quadrangular turns, etc.). Figure 3

[0060] As illustrated in Figure 4 , the first structural portion 28 comprises, in addition to the first connection region 20, a first stress dissipation region 24. Similarly, the second structural portion 30 comprises, in addition to the second connection region 22, a second stress dissipation region 26. ​​

[0061] The first stress-dissipation region 24 is joined to the first connection region 20 in a continuous manner with the first connection region 20 (in detail, it is the same material as the first connection region 20). The first connection region 20 is interposed between the first stress-dissipation region 24 and the remaining part of the innermost turn 5’ (typically the secondary winding 2b).

[0062] Similarly, the second stress-dissipation region 26 is joined to the second connection region 22 in a continuous manner with the second connection region 22 (in detail, it is the same material as the second connection region 22). The second connection region 22 is interposed between the second stress-dissipation region 26 and the second joint portion 34.

[0063] In the embodiment of Figure 4 , the stress-dissipation regions 24 and 26 have a curved (in detail, bent) shape in plan view to facilitate the dissipation of mechanical stresses. For illustrative purposes, the stress-dissipation regions 24 and 26 have a wave shape, a comma shape or a tear drop shape.

[0064] In particular, the stress-dissipation regions 24 and 26 are arched in such a way as to move away from the turns of the secondary winding 2b.

[0065] In detail, the stress-dissipation regions 24 and 26 have a first end 24’ and 26’ and a second end 24” and 26”, respectively, opposite each other. The second ends 24” and 26” are located at the respective connection regions 20 and 22, while the first ends 24’ and 26’ extend on the opposite side of the stress-dissipation regions 24 and 26 with respect to the connection regions 20 and 22.

[0066] The stress-dissipation regions 24 and 26 are curved in such a way that the first ends 24’ and 26’ have a respective minimum distance E 1’ and E 2’ from the turns 5 greater than the respective minimum distance E 1” and E 2” of the second ends 24” and 26” from the turns 5. In detail, the minimum distances E 1’ , E 2’ , E 1” , E 2” are measured between the respective ends 24’, 26’, 24”, 26” and a point of the turns 5 closer to the respective ends 24’, 26’, 24”, 26”. For example, the minimum distances E 1’ , E 2’ , E 1” , E 2” are measured radially with respect to the center 36 of the secondary winding 2b.

[0067] In other words, considering that the first structural portion 28 is radially inner to the turn 5, the first end 24' is closer to the center 36 with respect to the second end 24", while considering that the second structural portion 30 is radially outer to the turn 5, the first end 26' is farther from the center 36 with respect to the second end 26".

[0068] According to one embodiment, the stress-dissipation regions 24 and 26 have a curved (in detail, concave) surface with a radius of curvature comprised between about 10 pm and about 600 pm and, for example, equal to about 150 pm. The radius of curvature of the stress-dissipation regions 24 and 26 can also be different from each other.

[0069] The relative distance of the stress-dissipation regions 24 and 26 between the respective first end 24', 26' and the respective second end 24", 26" is comprised between about 150 pm and about 350 pm and, for example, equal to about 250 pm. These relative distances can also be different from each other.

[0070] Furthermore, the first ends 24' and 26' are vertically misaligned with respect to the conductive track 13 and the primary coil 2a. In other words, the first ends 24' and 26' are staggered along the Z axis with respect to the conductive track 13 and the primary coil 2a, so as not to extend above or below other metal portions of the transformer 2, i.e. other portions with a high CTE.

[0071] It has been verified that the stress-dissipation regions 24 and 26 reduce the mechanical stresses that can be generated between the respective connection regions 20 and 22 and the respective conductive vias 15 and 18 after a temperature variation, for example due to thermal cycles performed for manufacturing the transformer 2 or use of the transformer 2. This reduction of mechanical stresses avoids the formation of cracks and separations between the connection regions 20 and 22 and the respective conductive vias 15 and 18, thus making the transformer 2 more stable and reliable in use.

[0072] In detail, the shape of the previously described stress-dissipation regions 24 and 26 moves the points of accumulation of mechanical stresses away from the conductive vias 15 and 18 and causes these mechanical stresses to dissipate in regions immersed in the previously described polymeric material, for example PIX, and away from the turn 5.

[0073] According to Figure 5 and 6 different embodiments shown, the secondary coil 2b also comprises one or more support elements 40, which are coplanar with the turn 5 and have a free shape, whose topography at least partially surrounds the outer periphery of the turn 5 in the plane of the secondary coil 2b. In the following, the case of a plurality of support elements 40 is exemplarily considered.

[0074] In detail, the support elements 40 are coupled (in detail, joined) to the first joining portion 38 and / or to the second joining portion 34. Additionally or alternatively, the support elements 40 can be defined by the second structural portion 30 or can be coupled (in detail, joined) to the second structural portion 30.

[0075] The support elements 40 can have the same material as the second structural portion 30, the first joining portion 38 and the second joining portion 34 and can have the same thickness as the second structural portion 30, the first joining portion 38 and the second joining portion 34. For example, they can be made using “Electrochemical Deposition (ECD) plating”, in particular simultaneously with the second structural portion 30, the first joining portion 38 and the second joining portion 34.

[0076] The support elements 40 provide support to the portions of the transformer 2 extending at the level of the support elements 40, in particular to the current insulation region 11. Their arrangement with respect to the radially external portion of the turns 5 allows the current insulation region 11 to be supported in a substantially homogeneous manner with respect to that made by the same turns 5. In other words, the presence of the support elements 40 provides the extreme regions of the transformer 2 (i.e. the regions lying externally to the turns 5 in plan view) with the same current insulation region 11 as that provided by the turns 5 at the central region of the transformer 2 (i.e. the region lying centrally in plan view and corresponding to the turns 5 or lying internally to the turns 5). This allows a uniform thickness of the insulation layer forming the current insulation region 11 to be obtained, thus avoiding the formation of regions in which the distance between the coils 2a, 2b is reduced. This avoids a local and unnecessary increase in the electric field between the external turns 4”, 5” of the coils 2a, 2b, thus preventing malfunctions of the transformer 2.

[0077] To this end, the support elements 40 can surround a portion of the outer periphery of the turns 5, which can be between about 50% and about 95% of the outer periphery and, for example, equal to about 75% of the outer periphery.

[0078] The support elements 40 comprise support fingers 42.

[0079] The support fingers 42 have an open shape, i.e. do not define a closed shape (for example having a shape different from a ring shape). In fact, the open shape of the support fingers 42 prevents the generation of a current along a closed path (for example a circular path), which can cause unnecessary magnetic fields and energy losses (for example due to parasitic currents induced).

[0080] Furthermore, the support fingers 42 are electrically coupled to the first lower electrical contact region 5a and / or to the second lower electrical contact region 5b in such a way as to be at the same voltage as the first lower electrical contact region 5a and / or to the second lower electrical contact region 5b, respectively. In other words, the support fingers 42 are not of the floating type.

[0081] In detail, the support fingers 42 have an elongated shape (e.g. bar-shaped in plan view) and have a first end 42’ and a second end 42” opposite each other. The support fingers 42 are physically coupled to the first 38 and / or second 34 joint portions (thus to the first 5a and / or second 5b lower electrical contact areas, respectively) by their second ends 42”. The first ends 42’ are immersed in the electrically insulating or dielectric material (herein PIX for illustrative purposes).

[0082] In general, as long as the support fingers 42 are open, they have a free shape, thus Figure 4 and 5 The shapes shown are indicated purely for illustrative and non-limiting purposes, as other shapes can be similarly considered.

[0083] For example, the minimum distance of the support element 40 from the outermost turn 5” of the secondary coil 2b, measured in the radial direction, can be greater than about 50 pm.

[0084] In the embodiment of Figure 5 the support element 40 is exemplarily comprised in the first joint portion 38.

[0085] In the embodiment of Figure 5 the support element 40 is coupled to the first joint portion 38, which extends radially between the outermost turn 5” and the second lower electrical contact area 5b. The support element 40 here has two branches, which extend circumferentially around the turn 5 starting from the first joint portion 38, one clockwise and the other counterclockwise, for example until close to the second structural portion 30 (but not in contact with it).

[0086] For illustrative purposes, each branch comprises two support fingers 42, which can extend substantially parallel to each other around the turn 5. In other words, the support fingers 42 of each branch are one inside and one outside each other in the radial direction with respect to the center 36. The support fingers 42 have a shape, size and mutual arrangement that maximize the footprint to optimize the planarization of the current insulation area 11.

[0087] As previously described, other shapes, sizes, numbers and arrangements of the support fingers 42 can be similarly considered (e.g. three or more support fingers 42 per branch, different numbers of support fingers 42 for different branches, etc.). Moreover, the support element 40 can be alternatively or partially coupled to the second joint portion 34 in combination with the previously described.

[0088] In the embodiment of Figure 6 the support element 40 is exemplarily partially coupled in the first joint portion 38 and partially in the second structural portion 30.

[0089] In Figure 6 , the support elements 40 coupled to the first joint portions 38 are similar to those described in Figure 5 . Conversely, the support elements 40 coupled to the second structural portion 30 are jointed to the second connection areas 22 and, in the example described in Figure 6 , have one branch with two support elements 40 that extend circumferentially with respect to the turn 5 and clockwise with respect to the second connection areas 22.

[0090] In detail, in this embodiment, the support elements 40 coupled to the first joint portions 38 define the second stress dissipation areas 26 previously described and, in particular, have an at least partially curved shape and have a first end 42’ that is more distant from the turn 5 than a second end 42”. Moreover, the first end 42’ is not vertically aligned with respect to the electrically conductive track 13 and the primary coil 2a. In this way, the second stress dissipation areas 26 are useful both to improve the distribution of any mechanical stresses and to ensure a uniform thickness of the current insulation area 11.

[0091] The advantages offered by the present disclosure are evident through the review of the features thereof made in accordance with the present disclosure.

[0092] In particular, the stress dissipation areas 24, 26 improve the distribution of the mechanical stresses due to the CTE differences in the material of the transformer 2 after thermal cycles caused by the manufacturing steps of the transformer 2 or by its use. In fact, the stress dissipation areas 24, 26 balance the torque of mechanical stress generation caused by the thermal deformation of the metal material used during thermal cycles.

[0093] For example, the first stress dissipation areas 24 reduce the stresses at the first electrically conductive via 15 by about 35% (this value is evidently dependent on the manufacturing process used and on the material chosen). This avoids the delamination and breakdown phenomena of the connection areas 20, 22 with the electrically conductive via 15, 18 previously described.

[0094] Moreover, the support elements 40 improve the planarization of the current insulation area 11, avoiding the thickness of the current insulation area 11 to be not uniform. This is achieved by providing a support similar to that generated by the secondary coil 2b.

[0095] The support elements 40 keep the electrical performances of the transformer 2 (such as the quality factor and the maximum gain obtainable) substantially unchanged, so that they do not significantly affect its operation.

[0096] Therefore, the stress dissipation areas 24, 26 and the support elements 40 avoid damages to the current insulation area 11, such as its breakdown.

[0097] The stress dissipation areas 24, 26 and the support element 40 may be formed together with the secondary winding 2b (eg by the same photolithographic mask being appropriately patterned). Therefore, their presence does not complicate the manufacture of the transformer 2, as it does not require additional steps in the manufacturing process.

[0098] Finally, it is obvious that modifications and variations can be made to the present disclosure as described and illustrated herein without departing from the scope of the present disclosure, as defined in the appended claims.For example, the different embodiments described can be combined with each other to provide other solutions.

[0099] Furthermore, the stress dissipation regions 24, 26 can be used for galvanic isolation not only in planar transformers, but also in any galvanic isolation device and general electronic device where conductive vias are present and the CTE differences of the materials used are high.

[0100] Furthermore, the number of conductive vias may differ from that previously described (e.g., a single conductive via or more than two conductive vias), as well as their arrangement and function (e.g., they may be conductive vias coupled to the primary coil 2a rather than the secondary coil 2b).

[0101] Furthermore, it is even possible to have only one of the structural parts 28 and 30 .

[0102] Furthermore, according to various embodiments, the transformer 2 comprises a support element 40, while the stress dissipation areas 24 and 26 are absent. Figure 7 An example of this embodiment of the transformer 2 is shown in .

[0103] In the case of transformer 2 without stress dissipation areas 24 and 26, connection to conductive vias 15 and 18 occurs in a manner known per se. In other words, connection areas 20, 22 are bonded to conductive vias 15, 18 and any mechanical stress is dissipated at connection areas 20, 22.

[0104] Similar to previously described, the support element 40 is coupled to at least one of the second connection region 22 , the first engagement portion 38 , and the second engagement portion 34 .

[0105] exist Figure 7 In the example shown, the support element 40 includes a branch with two support fingers 42 extending clockwise around the turn 5 starting from the second engagement portion 34, a branch with two support fingers 42 extending counterclockwise around the turn 5 starting from the second connection area 22, and a branch with two support fingers 42 extending counterclockwise around the turn 5 starting from the first engagement portion 38. Nevertheless, different structures of the support element 40 can be similarly considered (for example, by the shape and number of support fingers 42). For example, each branch can include three or more support fingers 42, compatible with the available free area.

[0106] In Figure 7 the embodiment, the shape and the arrangement of the support elements 40 are free, provided that, similarly to what previously described, the support fingers 42 have an open shape and are electrically coupled to the first lower electrical contact area 5a and / or to the second lower electrical contact area 5b.

[0107] In Figure 7 the embodiment and differently from what previously described, for example with reference to Figure 6 the support elements 40 coupled to the second connection area 22 can not have an at least partially curved shape and can not have a first end 42’ distanced from the turns 5 more than a second end 42” and not vertically aligned with respect to the conductive track 13 and to the primary coil 2a. In fact, in this case, the presence of these support elements 40 is to improve the planarization of the transformer 2 and not to improve the dissipation of the mechanical stresses previously described.

[0108] A current insulation device (2) is summarized as comprising: an upper coil (2a) extending in a first insulation layer (8) parallel to a lying plane (XY); a lower coil (2b) extending in a second insulation layer (9) parallel to the lying plane (XY); a current insulation region (11) extending between the first insulation layer (8) and the second insulation layer (9); and at least a first conductive via (15; 18), wherein each of the upper coil (2a) and the lower coil (2b) comprises a plurality of turns (4; 5), a first electrical contact area (4a; 5a) and a second electrical contact area (4b; 5b), the first electrical contact area (4a; 5a) and the second electrical contact area (4b; 5b) being electrically coupled to the plurality of turns (4; 5), wherein the first conductive via (15; 18) is coupled to a first structural portion (28; 30) of the upper coil (2a) or of the lower coil (2b) and to a turn (4; 5) or to the first electrical contact area (4a; 5a) or to the second electrical contact area (4b; 5b), wherein the first structural portion (28; 30) comprises a first stress dissipation region (24; 26) having a curved shape parallel to the lying plane (XY) and having a first end (24’; 26’) misaligned with respect to the other one of the upper coil (2a) and of the lower coil (2b) along a first axis (Z) orthogonal to the lying plane (XY).

[0109] The first structural portion (28; 30) further comprises a first connection region (20; 22) coupled to the first conductive via (15; 18), aligned along the first axis (Z) with the first conductive via (15; 18), and interposed between the first stress dissipation region (24; 26) and the turn (4; 5) to which the first stress dissipation region (24; 26) is coupled or the first (4a; 5a) or second (4b; 5b) electrical contact region, parallel to the lying plane (XY), wherein the first stress dissipation region (24; 26) also has a second end (24"; 26") opposite the first end (24'; 26'), the first stress dissipation region (24; 26) being joined to the first connection region (20; 22) through the second end (24"; 26").

[0110] The first end (24'; 26') of the first stress dissipation region (24; 26) has a minimum distance (E 1’ ; E 2’ ) from the turn (5) of the respective upper (2a) or lower (2b) coil, which minimum distance (E 1’ ; E 2’ ) is greater than the respective minimum distance (E 1” ; E 2” ) of the second end (24"; 26") of the first stress dissipation region (24; 26) from the turn (5) of the respective upper (2a) or lower (2b) coil.

[0111] The first conductive via (15; 18) is coupled to the first structural portion (28; 30) of the lower coil (2b).

[0112] The lower coil (2b) comprises: inner turns (5’); outer turns (5”); one or more intermediate turns (5) extending in electrical continuity between the inner turns (5’) and the outer turns (5”), electrically coupled to the inner turns and to the outer turns, wherein the inner turns (5’), the outer turns (5”) and the one or more intermediate turns (5) extend parallel to the lying plane (XY) according to a helical path, wherein a first electrical contact area (5a) and a second electrical contact area (5b) of the lower coil (2b) extend outside the turns (5) of the lower coil (2b), wherein the outer turns (5”) of the lower coil (2b) are electrically connected to the second electrical contact area (5b) of the lower coil (2b), wherein the galvanic insulation device (2) further comprises an electrically conductive track (13) extending parallel to the lying plane (XY) and along the first axis (Z), extending at different levels with respect to the levels in which the secondary coil (2b) extends, the electrically conductive track (13) having a first end (13’) and a second end (13”) opposite each other, wherein the galvanic insulation device (2) further comprises a second electrically conductive via (18; 15), and wherein one of the first electrically conductive via (15; 18) and the second electrically conductive via (18; 15) extends between an inner end of the inner turns (5’) of the lower coil (2b) and the first end (13’) of the electrically conductive track (13), and the other of the first electrically conductive via (15; 18) and the second electrically conductive via (18; 15) electrically connects the second end (13”) of the electrically conductive track (13) and the first electrical contact area (5a) of the lower coil (2b), the first electrical contact area (5a) defining, through the electrically conductive track (13) and the first electrically conductive via (15; 18) and the second electrically conductive via (18; 15), an electrically conductive path between the inner turns (5’) of the lower coil (2b) and the first electrical contact area (5a) of the lower coil (2b).

[0113] The first structural portion (28) defines an inner end of the inner turns (5’) of the lower coil (2b), and the first electrically conductive via (15) extends between the first structural portion (28) and the first end (13’) of the electrically conductive track (13), wherein a first end (24’) of the first structural portion (28) is misaligned along the first axis (Z) with respect to the upper coil (2a) and the electrically conductive track (13), wherein the second electrically conductive via (18) extends between the second end (13”) of the electrically conductive track (13) and a second structural portion (30) of the lower coil (2b), the second structural portion (30) being coupled to the first electrical contact area (5a) of the secondary coil (2b), and wherein the second structural portion (30) comprises a second stress dissipation area (26) having a curved shape parallel to the lying plane (XY) and having a first end (26”) misaligned along the first axis (Z) with respect to the upper coil (2a) and the electrically conductive track (13).

[0114] The first stress-dissipating region (24; 26) has a concave surface having a curvature defined by a radius of curvature between 10 pm and 600 pm.

[0115] The first insulating layer (8), the second insulating layer (9) and the current- insulating region (11) comprise a polymeric material, in particular a polyimide.

[0116] The current-insulating device (2) is a planar transformer, and wherein the upper coil (2a) and the lower coil (2b) are aligned with each other along a first axis (Z).

[0117] The lower coil (2b) further comprises one or more support elements (40) which are coplanar with the turns (5) of the lower coil (2b), external to the turns (5) of the lower coil (2b) and at least partially surround the outer periphery of the turns (5) of the lower coil (2b).

[0118] The support elements (40) surround between 50% and 95% of the outer periphery of the turns (5) of the lower coil (2b).

[0119] The one or more support elements (40) comprise a support finger (42) having an open shape and being electrically coupled to the first electrical contact area (5a) and / or to the second electrical contact area (5b) of the lower coil (2b).

[0120] The lower coil (2b) further comprises a first joint portion (38) and a second joint portion (34) which are coplanar with the turns (5) of the lower coil (2b), wherein the first joint portion (38) extends between an outer turn (5”) of the lower coil (2b) and the second electrical contact area (5b) of the lower coil (2b) and the second joint portion (34) extends between the first electrical contact area (5a) of the lower coil (2b) and the other one of the first conductive via (15; 18) and the second conductive via (18; 15), wherein the support finger (42) has an elongated shape with a first end (42’) and a second end (42”) opposite each other and is joined to the first joint portion (38) or to the second joint portion (34) by the second end (42”).

[0121] The second structural portion (30) defines one of the support elements (40) and wherein the second stress-dissipating region (26) forms one of the support fingers (42).

[0122] The support element (40) has at least two branches of the support finger (42) which extend around the turns (5) circumference of the secondary coil (2b) starting from the first joint portion (38) and / or the second joint portion (34), one clockwise and the other counterclockwise.

[0123] An electronic device (1) is generalized to include any of the above-mentioned current insulation devices (2).

[0124] An electronic device is generalized to include a current insulation device comprising: a first coil extending in a first insulation layer; a second coil extending in a second insulation layer; a current insulation layer extending between the first coil and the second coil; and a first conductive via electrically coupled to the second coil; wherein each of the first coil and the second coil comprises turns, a first electrical contact area, and a second electrical contact area electrically coupled to two opposite ends of the turns; wherein the second coil further comprises a stress dissipation area arched away from the turns of the second coil in the second insulation layer and the stress dissipation area is misaligned with respect to the first coil.

[0125] The current insulation device further comprises: a second conductive via electrically coupled to the second coil; and a conductive track at a different level with respect to the level in which the second coil extends, the conductive track having a first end and a second end opposite to each other, one end of the turns of the second coil being electrically coupled to the first end of the conductive track through the first conductive via, and the other end of the turns of the second coil being electrically coupled to the first electrical contact area through the second conductive via.

[0126] A current insulation device is generalized to include: an upper coil extending in an upper insulation layer, the upper coil comprising a first upper electrical contact area, a second upper electrical contact area, and upper turns electrically coupling the first upper electrical contact area and the second upper electrical contact area; a lower coil extending in a lower insulation layer, the lower coil comprising a first lower electrical contact area, a second lower electrical contact area, and lower turns electrically coupling the first lower electrical contact area and the second lower electrical contact area, and a stress dissipation area electrically coupled to an end of the lower turns or the first lower electrical contact area, the stress dissipation area being arched away from the lower turns and misaligned with the upper coil; and a current insulation layer extending between the upper insulation layer and the lower insulation layer.

[0127] The stress dissipation area has a first end and a second end opposite to each other, the first end being arched away from the lower turns, and the second end being electrically coupled to the end of the lower turns or the first lower electrical contact area, a minimum distance between the first end and the lower turns being greater than a minimum distance between the second end and the lower turns.

[0128] The various embodiments described above can be combined to provide further embodiments. If necessary, the concepts of various patents, applications, and publications can be employed to provide further embodiments, and various aspects of the embodiments can be modified.

[0129] These and other changes can be made to the embodiments in light of the above detailed description. In general, in the following claims, the used terms such as "comprising," "including," "carrying," "containing," "characterized by," "comprised of," and the like are not used as limitation but rather as open ended language to be interpreted based on the description in the specification and the valid scope of the claims. Thus, the scope of the claims should not be limited to the specific embodiments described in the specification and the claims.

Claims

1. A current insulation device comprising: an upper coil extending parallel to the horizontal plane in the first insulating layer; a lower coil extending in the second insulating layer parallel to the horizontal plane; a galvanic insulating region extending between the first insulating layer and the second insulating layer; as well as at least a first conductive via, wherein each of the upper coil and the lower coil comprises a plurality of turns, a first electrical contact area, and a second electrical contact area, the first electrical contact area and the second electrical contact area being electrically coupled to the plurality of turns, wherein the first conductive via is coupled to the first structural portion of the upper coil or the first structural portion of the lower coil and is coupled to the turn, or is coupled to the first electrical contact area or the second electrical contact area, and The first structural portion includes a first stress dissipation region having a curved shape parallel to the lying plane and having a first end that is not aligned relative to the other of the upper coil and the lower coil along a first axis orthogonal to the lying plane.

2. The galvanic insulation device of claim 1 , wherein the first structural portion further comprises a first connection region coupled to the first conductive via, aligned with the first conductive via along the first axis, and interposed parallel to the horizontal plane between the first stress dissipation region and the turn or the first electrical contact region or the second electrical contact region to which the first stress dissipation region is coupled, The first stress dissipation region further has a second end opposite to the first end, and the first stress dissipation region is connected to the first connection region through the second end.

3. The current insulation device of claim 2 , wherein the first end of the first stress dissipation region has a minimum distance from the turn of the corresponding upper coil or the lower coil, the minimum distance being greater than the corresponding minimum distance between the second end of the first stress dissipation region and the turn of the corresponding upper coil or the lower coil. 4 . The galvanic isolation device of claim 1 , wherein the first conductive via is coupled to the first structural portion of the lower coil.

5. The current isolation device of claim 4, wherein the lower coil comprises: inner turn; outer turn; one or more intermediate turns extending in electrical continuity between the inner turn and the outer turn, being electrically coupled to the inner turn and the outer turn, wherein the inner turn, the outer turn and the one or more intermediate turns extend according to a spiral path parallel to the horizontal plane, wherein the first electrical contact region and the second electrical contact region of the lower coil extend outside the turns of the lower coil, wherein the outer turns of the lower coil are electrically connected to the second electrical contact area of ​​the lower coil, wherein the current insulating device further comprises a conductive track extending parallel to the horizontal plane and extending along the first axis at a different level relative to the level in which the lower coil extends, the conductive track having a first end and a second end opposite to each other, wherein the current isolation device further comprises a second conductive via, and One of the first conductive via and the second conductive via extends between the inner end of the inner turn of the lower coil and the first end of the conductive track, and the other of the first conductive via and the second conductive via electrically connects the second end of the conductive track and the first electrical contact area of ​​the lower coil, the first electrical contact area defining a conductive path between the inner turn of the lower coil and the first electrical contact area of ​​the lower coil through the conductive track and the first and second conductive vias.

6. The current isolation device of claim 5 , wherein the first structural portion defines the inner end of the inner turn of the lower coil, and the first conductive via extends between the first structural portion and the first end of the conductive track, wherein the first end of the first structural portion is misaligned along the first axis relative to the upper coil and the conductive track, wherein the second conductive via extends between the second end of the conductive track and a second structural portion of the lower coil, the second structural portion being coupled to the first electrical contact area of ​​the secondary coil, and The second structural portion includes a second stress dissipation region having a curved shape parallel to the lying plane and having a first end that is misaligned along the first axis relative to the upper coil and the conductive track. 7 . The current isolation device of claim 1 , wherein the first stress dissipation region has a concave surface having a curvature defined by a radius of curvature between 10 μm and 600 μm.

8. The galvanic isolation device of claim 1, wherein the first insulating layer, the second insulating layer, and the galvanic isolation region comprise a polymer material.

9. The galvanic isolation device of claim 8, wherein the first insulating layer, the second insulating layer, and the galvanic isolation region comprise polyimide.

10. The galvanic isolation device of claim 1, wherein the galvanic isolation device is a planar transformer, and wherein the upper coil and the lower coil are aligned with each other along the first axis.

11. The current isolation device of claim 1 , wherein the lower coil further comprises one or more support elements coplanar with, external to, and at least partially surrounding the circumference of the turns of the lower coil.

12. The current isolation apparatus of claim 11, wherein the support element surrounds between 50% and 95% of the circumference of the turns of the lower coil. 13 . The current isolation device of claim 11 , wherein the one or more support elements comprise support fingers having an open shape and electrically coupled to the first electrical contact area or the second electrical contact area of ​​the lower coil.

14. The current isolation device of claim 5, wherein the lower coil further comprises a first engagement portion and a second engagement portion coplanar with the turns of the lower coil, wherein the first engaging portion extends between the outer turn of the lower coil and the second electrical contact area of ​​the lower coil, and the second engaging portion extends between the first electrical contact area of ​​the lower coil and the other of the first conductive via and the second conductive via, and The supporting finger has an elongated shape, has a first end and a second end opposite to each other, and is coupled to the first coupling portion or the second coupling portion through the second end.

15. The current isolation device of claim 6, wherein the second structural portion defines one of the support elements, and wherein the second stress dissipation region forms one of the support fingers.

16. The current insulation device according to claim 11, wherein the support element has at least two support finger branches, which extend around the turn circumference of the secondary coil starting from the first engaging portion or the second engaging portion, one extending clockwise and the other extending counterclockwise.

17. An electronic device comprising: Current isolation equipment, including: a first coil extending in a first insulating layer along a first direction; a second coil extending in the second insulating layer; a galvanic insulating layer extending between the first coil and the second coil; and a first conductive via electrically coupled to the second coil; wherein each of the first coil and the second coil comprises a turn, a first electrical contact area, and a second electrical contact area, the first electrical contact area and the second electrical contact area being electrically coupled to two opposite ends of the respective first coil or the second coil; The second coil further includes a stress dissipation region, the stress dissipation region is arched away from the second coil in the second insulating layer, and the stress dissipation region does not overlap with the first coil along a second direction transverse to the first direction.

18. The electronic device of claim 17, wherein the galvanic isolation device further comprises: a second conductive via electrically coupled to the second coil; as well as a conductive track located at a different level relative to the level in which the second coil extends, the conductive track having a first end and a second end opposite to each other, one end of the turn of the second coil being electrically coupled to the first end of the conductive track through the first conductive via, and the other end of the turn of the second coil being electrically coupled to the first electrical contact area through the second conductive via.

19. A current insulation device comprising: an upper coil extending in the upper insulating layer, the upper coil including a first upper electrical contact region, a second upper electrical contact region, and the upper coil electrically coupling the first upper electrical contact region and the second upper electrical contact region; a lower coil extending in the lower insulating layer, the lower coil including a first lower electrical contact region, a second lower electrical contact region, and a stress dissipation region, the stress dissipation region being electrically coupled to an end of the first lower electrical contact region, the lower coil being electrically coupled to the first lower electrical contact region and the second lower electrical contact region, the stress dissipation region being arched away from the lower coil and not overlapping the upper coil; as well as A current insulating layer extends between the upper insulating layer and the lower insulating layer.

20. The current isolation device of claim 19 , wherein the stress dissipation region has a first end and a second end opposite each other, the first end being arched away from the lower coil, the second end being electrically coupled to an end of the lower coil or an end of the first lower electrical contact region, and a minimum distance between the first end and the lower coil being greater than a minimum distance between the second end and the lower coil.

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