Electronic device
By designing a circuit structure with a rounded convex corner and a long corner, the problems of increased material and manufacturing costs and reduced insulation when reducing the substrate area are solved, and effective suppression of discharge and maintenance of insulation are achieved without the use of sealing resin.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DENSO CORP
- Filing Date
- 2022-05-26
- Publication Date
- 2026-07-14
AI Technical Summary
While existing technologies can reduce the substrate area, they also result in increased material costs and reduced insulation, especially when sealing with sealing resin without relying on creepage distance, leading to increased manufacturing costs and reduced insulation due to resin peeling.
By designing the shapes of the first and second conductive parts, the convex corners are rounded and the distance between the corners is longer than the distance between the corners, thus avoiding the use of sealing resin and suppressing discharge solely through circuit design.
It effectively suppresses discharge, reduces material and manufacturing costs, and avoids insulation degradation caused by resin peeling, thus improving insulation performance.
Smart Images
Figure CN117616878B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to an electronic device having a substrate and circuitry mounted on the substrate. Background Technology
[0002] Among the aforementioned electronic devices, there exists an electronic device in which the circuit has a defined first conductive portion, and next to the first conductive portion is a second conductive portion at a different potential from the first conductive portion. In this case, it is necessary to ensure a creepage distance between the first conductive portion and the second conductive portion to prevent discharge. However, for purposes such as miniaturization of the substrate, it is desirable to suppress the aforementioned creepage distance as small as possible.
[0003] Therefore, in electronic devices, there exist those that seal at least one of a first conductive part and a second conductive part with an insulating resin in order to suppress discharge without relying on creepage distance. Moreover, as a document illustrating this technology, there is the following Patent Document 1.
[0004] Existing technical documents
[0005] Patent documents
[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-77744 Summary of the Invention
[0007] According to the above technology, by filling the discharge space with sealing resin, discharge can be suppressed without depending on the creepage distance. Therefore, the substrate area can be reduced.
[0008] However, in this case of sealing the conductor with a sealing resin, the sealing resin itself is required, thus increasing material costs. Furthermore, during manufacturing, recesses are needed to accumulate the flowing sealing resin. Therefore, manufacturing costs also increase accordingly, corresponding to the number of recesses. Additionally, the process of allowing the sealing resin to flow into the recesses and then cure it further increases manufacturing costs. Moreover, since a resin different from the substrate material is used to seal the conductor, there are concerns about reduced insulation due to resin peeling caused by years of degradation.
[0009] This disclosure is made in view of the above circumstances, and its main purpose is to suppress discharge while mitigating concerns about increased costs in materials and manufacturing, and reduced insulation due to years of deterioration.
[0010] The electronic device disclosed herein has a substrate and a circuit mounted on the substrate, the circuit having a first conductive portion and a second conductive portion at a different potential from the first conductive portion.
[0011] When viewed from above along the thickness direction of the substrate, the first conductive portion has a convex corner with a rounded top, and the second conductive portion has a concave corner opposite the convex corner. In this top view, the extensions of two straight lines that continuously form the outline of the first conductive portion with respect to the convex corner form a convex corner, and the extensions of two straight lines that continuously form the outline of the second conductive portion with respect to the concave corner form a concave corner.
[0012] In the following top-down view, the straight line passing through the vertices of the convex and concave angles is designated as the "angle line," the intersection of the angle line and the convex angle is designated as the "convex angle point," and the intersection of the angle line and the concave angle is designated as the "concave angle point." In the top-down view, the distance from the convex angle point to the concave angle point, i.e., the "inter-angle distance," is longer than the distance from the vertex of the convex angle to the vertex of the concave angle, i.e., the "inter-angle distance."
[0013] The inventors discovered the following in cases where the convex corner has a convex apex and the concave corner has a concave apex: Discharge between the first conductive portion and the second conductive portion does not necessarily begin at the point in the first and second conductive portions that are closest to each other in terms of creepage distance, such as parallel portions. In most cases, although the distance is greater than in the case of parallel portions, the discharge begins between the apex of the convex corner of the first conductive portion and the apex of the concave corner of the second conductive portion. That is, it was found that the initiation of discharge along the angle passing through the apex of the convex corner and the apex of the concave corner is, in most cases, a determining factor in the rate of insulation failure.
[0014] In this respect, this disclosure firstly includes a convex corner with a rounded top. This allows for the suppression of electric field concentration relative to the top of the convex corner, thereby suppressing discharge at the top of the convex corner.
[0015] Furthermore, in this disclosure, the distance between the aforementioned corners is made longer than the distance between corners. That is, for example, the distance from the convex corner point to the concave corner point is longer than the case where the concave corner is rounded in a shape parallel to the convex corner. As a result, the distance from the first conductive part to the second conductive part on the corner line, which is a determining factor of the rate of insulation failure, can be increased as much as possible, thereby further suppressing discharge.
[0016] Furthermore, this structure allows for the suppression of discharge through circuit design alone, without the use of sealing resins or similar materials, thus mitigating the increase in material and manufacturing costs. Moreover, since sealing the conductors with sealing resins or similar materials is unnecessary, there is no concern about reduced insulation due to resin peeling caused by years of degradation.
[0017] According to this disclosure, discharge can be suppressed while mitigating concerns about increased costs in materials and manufacturing, and reduced insulation due to years of deterioration. Attached Figure Description
[0018] The above-mentioned objects, other objects, features, and advantages of this disclosure will become clearer with reference to the accompanying drawings and the following detailed description. The accompanying drawings are described below.
[0019] Figure 1 This is a circuit diagram showing the electronic device and its surroundings according to the first embodiment.
[0020] Figure 2 This is a top view of an electronic device.
[0021] Figure 3 It is Figure 2 A magnified top view of a portion of the image.
[0022] Figure 4 This is a top view showing the corner and its surrounding area of Comparative Example 1 and this embodiment.
[0023] Figure 5 This is a front sectional view showing the power lines, etc., of Comparative Example 1.
[0024] Figure 6 This is a front cross-sectional view showing the power lines, etc., of this embodiment.
[0025] Figure 7 It is a graph showing the discharge start voltage of the shape of each corner.
[0026] Figure 8 This is a top view showing the corner and its surrounding area of the first variation.
[0027] Figure 9 This is a top view showing the corner and its surrounding area of the modified example two.
[0028] Figure 10 This is a top view showing the corner and its surrounding area of variation example three.
[0029] Figure 11 This is a top view showing the corner and its surrounding area of variation example four.
[0030] Figure 12 This is a top view showing the corner and its surrounding area of variation example five.
[0031] Figure 13 This is a top view showing the corner and its surrounding area of variant example six. Detailed Implementation
[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments, and can be implemented by appropriate modifications without departing from the spirit of the disclosure.
[0033] [First Implementation Method]
[0034] Figure 1 This is a circuit diagram showing the switch drive device 40 and its surroundings, which are electronic devices in this embodiment. The vehicle 90 is equipped with a main battery 10, an inverter 30, a switch drive device 40, and a three-phase coil 50. Hereinafter, electrical connections will be simply referred to as "connections".
[0035] The main battery 10 has multiple individual cells 11 connected in series. Each individual cell 11 is a lithium-ion battery or the like. A positive electrode wire 30p is connected to the positive terminal of the main battery 10, and a negative electrode wire 30n is connected to the negative terminal of the main battery 10. The positive electrode wire 30p and the negative electrode wire 30n are connected via a smoothing capacitor 20. Hereinafter, the potential of the positive electrode wire 30p will be referred to as the "positive electrode potential Vp", and the potential of the negative electrode wire 30n will be referred to as the "negative electrode potential Vn".
[0036] The inverter 30 has a total of six switches 31-36, consisting of three upper switches 31-33 and three lower switches 34-36. The three upper switches 31-33 consist of the U-phase upper switch 31, the V-phase upper switch 32, and the W-phase upper switch 33. On the other hand, the three lower switches 34-36 consist of the U-phase lower switch 34, the V-phase lower switch 35, and the W-phase lower switch 36.
[0037] Each of the six switches 31 to 36 mentioned above is a semiconductor switch such as IGBT, MOSFET, or bipolar transistor (IGBT in the figure), and has a positive terminal (collector terminal in the figure), a negative terminal (emitter terminal in the figure), and a control terminal (gate terminal in the figure).
[0038] The positive terminal of each of the three upper switches 31 to 33 is connected to a positive wiring 30p. Furthermore, the negative terminal of each of the three lower switches 34 to 36 is connected to a negative wiring 30n.
[0039] The three-phase coil 50 has three coils 51 to 53: a U-phase coil 51, a V-phase coil 52, and a W-phase coil 53. In this embodiment, these three coils 51 to 53 are connected in a star configuration. That is, one end of the U-phase coil 51, one end of the V-phase coil 52, and one end of the W-phase coil 53 are connected to each other at the neutral point C. However, alternatively, a delta configuration may also be used.
[0040] One end of the U-phase coil 51, opposite to the neutral point C, is connected to the negative terminal of the U-phase upper switch 31 and the positive terminal of the U-phase lower switch 34 via the U-phase wiring 30u. One end of the V-phase coil 52, opposite to the neutral point C, is connected to the negative terminal of the V-phase upper switch 32 and the positive terminal of the V-phase lower switch 35 via the V-phase wiring 30v. One end of the W-phase coil 53, opposite to the neutral point C, is connected to the negative terminal of the W-phase upper switch 33 and the positive terminal of the W-phase lower switch 36 via the W-phase wiring 30w.
[0041] Hereinafter, the potential of the U-phase wiring 30u will be referred to as "U-phase potential Vu", the potential of the V-phase wiring 30v will be referred to as "V-phase potential Vv", and the potential of the W-phase wiring 30w will be referred to as "W-phase potential Vw".
[0042] The switch drive device 40 has a total of six drive circuits 41-46, consisting of three upper drive circuits 41-43 and three lower drive circuits 44-46. The three upper drive circuits 41-43 are composed of a U-phase upper drive circuit 41, a V-phase upper drive circuit 42, and a W-phase upper drive circuit 43. On the other hand, the three lower drive circuits 44-46 are composed of a U-phase lower drive circuit 44, a V-phase lower drive circuit 45, and a W-phase lower drive circuit 46.
[0043] The six drive circuits 41-46 each have a reference potential terminal as the negative side and an output terminal as the positive side. The reference potential terminal of the U-phase drive circuit 41 is connected to the U-phase wiring 30u, and its output terminal is connected to the control terminal of the U-phase switch 31. The reference potential terminal of the V-phase drive circuit 42 is connected to the V-phase wiring 30v, and its output terminal is connected to the control terminal of the V-phase switch 32. The reference potential terminal of the W-phase drive circuit 43 is connected to the W-phase wiring 30w, and its output terminal is connected to the control terminal of the W-phase switch 33. Therefore, the reference potential of the U-phase drive circuit 41 is the U-phase potential Vu, the reference potential of the V-phase drive circuit 42 is the V-phase potential Vv, and the reference potential of the W-phase drive circuit 43 is the W-phase potential Vw.
[0044] The reference potential terminal of the U-phase lower drive circuit 44 is connected to the negative terminal wiring 30n, and its output terminal is connected to the control terminal of the U-phase lower switch 34. The reference potential terminal of the V-phase lower drive circuit 45 is connected to the negative terminal wiring 30n, and its output terminal is connected to the control terminal of the V-phase lower switch 35. The reference potential terminal of the W-phase lower drive circuit 46 is connected to the negative terminal wiring 30n, and its output terminal is connected to the control terminal of the W-phase lower switch 36. Therefore, the reference potential of each of the three lower drive circuits 44 to 46 is the negative potential Vn.
[0045] The switch drive unit 40 has a control circuit 48 that controls the six drive circuits 41 to 46. The control circuit 48 is powered by the auxiliary battery 19. By controlling the six drive circuits 41 to 46, the control circuit 48 performs DUTY control on the six switches 31 to 36, and controls the flow of three-phase alternating current to the three-phase coil 50. The DUTY control itself is well-known, therefore, its detailed description is omitted.
[0046] In this DUTY control, the U-phase upper switch 31 is turned on and the U-phase lower switch 34 is turned off at the same time, and the U-phase upper switch 31 is turned off and the U-phase lower switch 34 is turned on at the same time. Hereinafter, the state in which the U-phase upper switch 31 is turned on and the U-phase lower switch 34 is turned off is called the "U-phase on state", and the state in which the U-phase upper switch 31 is turned off and the U-phase lower switch 34 is turned on is called the "U-phase off state".
[0047] Similarly, the state in which the upper switch 32 of phase V is turned on and the lower switch 35 of phase V is turned off is called the "phase V on state", and the state in which the upper switch 32 of phase V is turned off and the lower switch 35 of phase V is turned on is called the "phase V off state". Similarly, the state in which the upper switch 33 of phase W is turned on and the lower switch 36 of phase W is turned off is called the "phase W on state", and the state in which the upper switch 33 of phase W is turned off and the lower switch 36 of phase W is turned on is called the "phase W off state".
[0048] With the above circuit structure, the U-phase potential Vu becomes a positive potential Vp when U-phase is on and a negative potential Vn when U-phase is off. Similarly, the V-phase potential Vv becomes a positive potential Vp when V-phase is on and a negative potential Vn when V-phase is off. Likewise, the W-phase potential Vw becomes a positive potential Vp when W-phase is on and a negative potential Vn when W-phase is off.
[0049] Furthermore, the timing of the switch from the U-phase on state to the U-phase off state, the timing of the switch from the V-phase on state to the V-phase off state, and the timing of the switch from the W-phase on state to the W-phase off state are staggered. Therefore, the reference potential (Vu, Vv, Vw) of each of the three upper drive circuits 41 to 43 is at a different potential from each of the other two reference potentials for a certain period of time.
[0050] On the other hand, the reference potential terminal, which is the negative terminal of the control circuit 48, is connected to the vehicle body 90. Hereinafter, the potential of this vehicle body will be referred to as the "ground potential Vg". Therefore, the reference potential of the control circuit 48 is the ground potential Vg. The positive potential Vp is higher than this ground potential Vg, and the negative potential Vn is lower than this ground potential Vg. Therefore, the reference potential (Vg) of the control circuit 48 is different from the reference potential (Vu, Vv, Vw, Vn) of any of the six drive circuits 41 to 46. Therefore, the control circuit 48 is connected to the six drive circuits 41 to 46 respectively via insulating elements 48i such as couplers and capacitors.
[0051] Figure 2 This is a top view showing the switch drive device 40. Six drive circuits 41-46 and a control circuit 48 are mounted on a substrate 49, which is an insulator such as glass epoxy resin. Hereinafter, referring to the accompanying drawings, the thickness direction of the substrate 49 will be referred to as "vertical Z," a predetermined direction orthogonal to vertical Z will be referred to as "left-right X," and a direction orthogonal to both vertical Z and left-right X will be referred to as "front-back Y." However, this embodiment can be implemented by setting any three directions described below as orthogonal to each other.
[0052] Should Figure 2 This is a top view of the switch drive device 40 as seen from above. Hereinafter, this top-down view will be simply referred to as the "top view". The three upper drive circuits 41 to 43 are arranged in a left-right (X) configuration. Specifically, the V-phase upper drive circuit 42 is located to the right of the U-phase upper drive circuit 41, and the W-phase drive circuit is located to the right of the V-phase upper drive circuit 42. Furthermore, the U-phase lower drive circuit 44 is located in front of the U-phase upper drive circuit 41, the V-phase lower drive circuit 45 is located in front of the V-phase upper drive circuit 42, and the W-phase lower drive circuit 46 is located in front of the W-phase upper drive circuit 43. The control circuit 48 is configured to surround the six drive circuits 41 to 46 from the front-back (Y) and left-right (X) configurations when viewed from above.
[0053] When viewed from above, the outer edge of each of the six drive circuits 41 to 46 is at its own reference potential (Vu, Vv, Vw, Vn). Furthermore, when viewed from above, the inner edge of the control circuit 48, i.e., the portion opposite to each of the six drive circuits 41 to 46, is at its own reference potential (Vg).
[0054] As described above, a creepage distance G is ensured between the control circuit 48 and each of the six drive circuits 41-46. Furthermore, a creepage distance G is also ensured between the three upper drive circuits 41-43 and the three lower drive circuits 44-46, and between the three upper drive circuits 41-43 and each other. This creepage distance G is approximately 4 mm.
[0055] Furthermore, no creepage distance G is guaranteed between the three lower drive circuits 44-46. This is because the reference potential of each of the three lower drive circuits 44-46 is the negative potential Vn, and the reference potentials are equal to each other.
[0056] Figure 3 It is Figure 2 A partially enlarged top view, specifically, a top view showing the front left corner of the outer edge of the U-phase drive circuit 44, the front left corner of the inner edge of the control circuit 48, and their surroundings. Hereinafter, refer to this... Figure 3 The shape of the switch drive device 40 when viewed from above is described.
[0057] Hereinafter, one of the two conductors with different potentials that are separated by a creepage distance G will be referred to as the first conductive part A, and the other as the second conductive part B. Thus, in this… Figure 3 In this case, the first conductive part A is a conductor located on the outer edge of the U-phase driving circuit 44, and the second conductive part B is a conductor located on the inner edge of the control circuit 48. Therefore, the potential of the first conductive part A is the negative potential Vn, and the potential of the second conductive part B is the ground potential.
[0058] Furthermore, the first conductive part A and the second conductive part B can each be a single layer, or multiple layers can be formed in the vertical direction (multi-layer). In addition, when multiple layers are formed, they can be connected by lamination or by through-holes.
[0059] The first conductive portion A has a convex corner portion AC with a rounded top that curves into an arc shape. The extensions of two straight lines that continuously form the outline of the first conductive portion A along this convex corner portion AC form a convex angle (an angle less than 180°). Furthermore, these two straight lines are the two lines forming the front and left sides of the outer edge of the first conductive portion A, and the convex angle here is 90°. Hereinafter, the radius of curvature of the convex corner portion AC will be referred to as the "first radius of curvature Ra".
[0060] On the other hand, the second conductive part B has a concave corner part BC opposite to the convex corner part AC. The extensions of two straight lines that continuously form the outline of the second conductive part B with the concave corner part BC form a concave angle (an angle greater than 180°). In addition, the two straight lines here are the two straight lines forming the front and left sides of the inner edge of the second conductive part B, and the concave angle here is 270°.
[0061] Hereinafter, the radius of curvature of the concave corner BC will be referred to as the "second radius of curvature Rb". The second radius of curvature Rb is smaller than the first radius of curvature Ra. In this embodiment, the second radius of curvature Rb is 0.2 mm or less. Preferably, the second radius of curvature Rb is as small as possible. That is, preferably, the concave corner BC is as non-circular as possible. Specifically, preferably, the concave corner BC is actually concave and has a substantial apex of concave angle.
[0062] Hereinafter, the vertex of the aforementioned convex angle will be referred to as "convex angle vertex aC", and the vertex of the aforementioned concave angle will be referred to as "concave angle vertex bC". Furthermore, the straight line passing through the convex angle vertex aC and the concave angle vertex bC will be referred to as "angle line Lab", the intersection of angle line Lab and the convex angle AC will be referred to as "convex angle point aP", and the intersection of angle line Lab and the concave angle BC will be referred to as "concave angle point bP". Moreover, the distance from the convex angle vertex aC to the concave angle vertex bC will be referred to as "angle distance Dc", and the distance from the convex angle point aP to the concave angle point bP will be referred to as "angle distance Dp".
[0063] In this embodiment, as described above, the second radius of curvature Rb is smaller than the first radius of curvature Ra. Therefore, the corner distance Dp is longer than the corner distance Dc. Specifically, in this embodiment, the corner distance Dp is more than 1.1 times the corner distance Dc.
[0064] Hereinafter, the portions of the first conductive portion A and the second conductive portion B that are parallel to each other and separated by a creepage distance G will be referred to as the "parallel portions," and the portion formed by the convex corner portion AC, the concave corner portion BC, and their peripheries will be referred to as the "corner portions." The above refers to... Figure 2 The left-front corner of the inner edge of the control circuit 48 shown has been described, but the same applies if the first conductive part A is appropriately replaced with the corresponding part at the left-rear corner, right-rear corner, and right-front corner. Specifically, in the case of the left-rear corner, the outer edge of the U-phase upper drive circuit 41 is the first conductive part A; in the case of the right-rear corner, the outer edge of the W-phase upper drive circuit 43 is the first conductive part A; and in the case of the right-front corner, the outer edge of the W-phase lower drive circuit 46 is the first conductive part A. Furthermore, in any of the above cases, the inner edge of the control circuit 48 is the second conductive part B.
[0065] Figure 4 This is a top view showing the corners of Comparative Example 1 and this embodiment, respectively. Figure 4 In Comparative Example 1 shown in (a), neither the convex corner AC nor the concave corner BC becomes rounded. Therefore, point aP of the convex corner is the convex corner vertex aC itself, and point bP of the concave corner is the concave corner vertex bC itself. Therefore, the distance between the corners Dp is equal to the distance between the corners Dc.
[0066] Next, referring to this comparative example, the focus of this embodiment will be explained. The discharge between the first conductive portion A and the second conductive portion B does not necessarily begin at the point in the first conductive portion A and the second conductive portion B that is closest to each other in terms of creepage distance, such as a parallel portion. In most cases, the discharge begins between the convex corner point aP and the concave corner point bP, although this is farther away than in the case of a parallel portion. That is, focusing on the start of the discharge at the corner line Lab, it is in most cases a determining factor in the rate of insulation failure.
[0067] Therefore, such as Figure 4 As shown in (b), in this embodiment, by making the convex corner AC rounded, the electric field concentration relative to the convex corner AC is suppressed as much as possible. On the other hand, by minimizing the rounding of the concave corner BC, the distance between the first conductive part A and the second conductive part B on the corner line Lab, which is a factor determining the rate of insulation failure, is increased as much as possible, i.e., the corner distance Dp. As a result, the corner distance Dp becomes longer than the corner distance Dc.
[0068] Figure 5 It means Figure 4 (a) shows a cross-sectional view of the VV line at the corner of Comparative Example 1, specifically the cross-section of the corner line Lab. Furthermore, here, the first conductive portion A and the second conductive portion B are each formed in multiple layers in the vertical direction, and it is assumed that each layer of the first conductive portion A and each layer of the second conductive portion B are at the same potential. This is as shown below. Figure 6 The same applies to the middle section. Hereinafter, the edge of the upper surface of the first conductive part A on the side of the second conductive part B in this cross section will be referred to as the "first edge aPE". That is, the first edge aPE is the upper end of the convex corner point aP.
[0069] At the convex corner point aP where the electric field concentrates when viewed from above, the electric field also concentrates at the first edge aPE when viewed from above. Therefore, electric field lines Le radiate from the first edge aPE in a direction obliquely upward relative to the side of the second conductive portion B. This is because the electric field lines Le radiate in a direction perpendicular to the equipotential line Lv. Therefore, for example, at the upper surface of the first conductive portion A, since the equipotential line Lv extends along the upper surface of the first conductive portion A, the electric field lines Le radiate upward. On the other hand, at the end face of the first conductive portion A on the side of the second conductive portion B, since the equipotential line Lv extends vertically Z, the electric field lines Le radiate towards the side of the second conductive portion B. This is why the electric field lines Le radiate from the first edge aPE in a direction obliquely upward relative to the side of the second conductive portion B in the middle.
[0070] As shown above, the electric field line Le extends from the first edge aPE in a parabolic manner to the near part of the concave corner point bP. Furthermore, the reason why the electric field line Le reaches the near part of the concave corner point bP rather than directly to it is that, when viewed from above, the equipotential line Lv near the concave corner BC does not extend by bending along the edge of the concave corner BC, but rather extends and extends by taking a gentle shortcut through the inside of its edge.
[0071] Figure 6 It means Figure 4 (b) shows a cross-sectional view of the corner VI-VI line of this embodiment, i.e., the cross-section of the corner line Lab. In this embodiment, as described above, by rounding the convex corner AC when viewed from above, the concentration of the electric field at the convex corner point aP is suppressed. Furthermore, in this embodiment, the corner distance Dp is longer than the corner distance Dc, therefore its corner distance Dp is longer than the corner distance Dp of Comparative Example 1. Therefore, in Figure 6 In the embodiment shown, with Figure 5 Compared to Comparative Example 1, the spacing Lg of the equipotential lines Lv is larger. Therefore, compared to Comparative Example 1, the discharge between the first conductive part A and the second conductive part B at the corner is suppressed. That is, the discharge initiation voltage increases.
[0072] Figure 7 This is a graph showing the different discharge initiation voltages caused by different corner shapes. Specifically, it shows the discharge initiation voltage of the portion indicated by the thick dashed line. The higher the discharge initiation voltage, the more difficult it is to initiate a discharge. The inventors discovered that, with this... Figure 7 Compared to the parallel portion shown on the left, the corner portion of Comparative Example 1 shown on its right is more prone to the discharge described above. That is, the inventors found that although the corner distance Dp of Comparative Example 1 is √2 times the creepage distance G at the parallel portion, the corner portion of Comparative Example 1 is more prone to discharge than the parallel portion. Furthermore, the discharge initiation voltage at the corner portion of Comparative Example 1 is actually lower than that at the parallel portion.
[0073] In the case of Comparative Example 2, which is adjacent to Comparative Example 1 on its right, if the convex corner AC is rounded and the concave corner BC is rounded parallel to it, firstly, the electric field concentration at the convex corner point aP is mitigated, making discharge less likely to occur compared to Comparative Example 1. However, in the case of Comparative Example 2, compared to Comparative Example 1, the distance Dp between the corners is actually shorter and becomes equal to the creepage distance G at the parallel portion. Therefore, at this point, discharge is more likely to occur. However, the positive effect of rounding the convex corner AC in the former case outweighs the negative effect of shortening the distance Dp between the corners in the latter case. Therefore, in general, as... Figure 7As shown, compared with Comparative Example 1, discharge is more difficult to occur in Comparative Example 2, and the discharge initiation voltage is higher.
[0074] In response to this, Figure 7 In the embodiment shown in (d), by rounding the convex corner AC while minimizing the rounding of the concave corner BC, the concentration of the electric field at the convex corner point aP is suppressed, and the distance Dp between the corners is longer than in Comparative Examples 1 and 2. Therefore, compared to Comparative Example 2, discharge is less likely to occur, and the discharge initiation voltage is further increased. Thus, in this embodiment, the discharge initiation voltage at the corner is approximately equal to the discharge initiation voltage at the parallel portion, suppressing the corner from becoming a rate-determining factor for insulation failure.
[0075] The effects of this implementation method are summarized below.
[0076] In this embodiment, the convex corner AC has a rounded top shape. This allows for the suppression of electric field concentration relative to the convex corner point aP, thereby suppressing discharge at the convex corner AC.
[0077] Furthermore, the corner distance Dp is longer than the corner distance Dc. Therefore, the distance from the first conductive part A to the second conductive part B on the corner line Lab, which is a determining factor of the rate of insulation failure, can be increased as much as possible, thereby further suppressing discharge.
[0078] Furthermore, according to this embodiment, discharge can be suppressed solely through circuit design without the use of sealing resins or the like, thus reducing the increase in material and manufacturing costs. Moreover, since it is not necessary to seal the conductors with sealing resins or the like, there is no concern about reduced insulation due to resin peeling caused by years of deterioration.
[0079] According to this embodiment, discharge can be suppressed while addressing concerns about increased costs in materials and manufacturing, as well as reduced insulation due to years of deterioration.
[0080] Furthermore, in this embodiment, the second radius of curvature Rb is made smaller than the first radius of curvature Ra; specifically, the second radius of curvature Rb is 0.2 mm or less. This effectively makes the corner distance Dp longer than the corner distance Dc.
[0081] Furthermore, in this embodiment, the first conductive part A is the outer edge of the drive circuits 41, 43, 44, and 46 constituting the switch drive device 40, and the second conductive part B is the inner edge of the control circuit 48 constituting the switch drive device 40. Therefore, the above-mentioned effects are obtained in the switch drive device 40.
[0082] [Other Implementation Methods]
[0083] The embodiments described above can be modified and implemented, for example, as shown in the following variations.
[0084] In the first embodiment, the convex angle is 90° and the concave angle is 270°. Alternatively, it can be as follows: Figure 8 As shown in the first variation, the convex angle is made obtuse, meaning it is greater than 90°, and the concave angle is less than 270°. Alternatively, it can be done as follows: Figure 9 As shown in the second variation, the convex angle is set as an acute angle, even if it is less than 90°, and the concave angle is greater than 270°.
[0085] In the first embodiment, the sum of the convex angle (90°) and the concave angle (270°) is 360°. Alternatively, it can be as follows: Figure 10 As shown in Variation Example 3, the sum can be made less than 360°, or conversely, the sum can be made greater than 360°.
[0086] In the first embodiment, the convex corner AC is rounded into an arc shape. Alternatively, for example, ... Figure 11 , Figure 12 As shown, the convex corner AC can also be rounded into an elliptical arc shape. Specifically, for example, it can also be like... Figure 11 As shown in Variation Example 4, the convex corner AC is shaped like an elliptical arc near the minor axis of an ellipse. Furthermore, in this case, the radius of curvature Ra of the convex corner AC is the radius of the circle tangent to the ellipse from the outside. Alternatively, for example, it could be as follows... Figure 12 As shown in Variation Example 5, the convex corner AC is designed to be rounded into an elliptical arc shape near the major axis of an ellipse. Furthermore, in this case, the radius of curvature of the convex corner AC is the radius of the circle tangent to the ellipse from the inside.
[0087] In the first embodiment, the convex corner AC is rounded into an arc shape. Alternatively, for example, it could be... Figure 13 As shown in the sixth variation, the convex corner AC is made into a rounded oval shape.
[0088] The above-described embodiments and variations can be further modified and implemented by the following methods.
[0089] In the first embodiment, the following structure is used in the switch drive circuit: by rounding the convex corner AC and minimizing the rounding of the concave corner BC, the distance Dp between the corners is made as long as possible. Alternatively, such a structure can also be used in any circuit other than the switch drive circuit that has the convex corner AC and the concave corner BC.
[0090] In the first embodiment, the second radius of curvature Rb is 0.2 mm or less, but it is also possible to set the second radius of curvature Rb to 0.2 mm or more within the range where the distance between corners Dp is longer than the distance between corners Dc.
[0091] In the first embodiment, the corner distance Dp is at least 1.1 times the corner distance Dc, but it may be less than 1.1 times. However, even in this case, in order to fully exert the effect of suppressing discharge, it is preferable that the corner distance Dp is at least 1.05 times the corner distance Dc, and more preferably at least 1.07 times the corner distance Dc.
[0092] Furthermore, when the first conductive portion A is multi-layered, not only is a convex corner portion AC provided on the surface layer of the first conductive portion A, but a convex corner portion AC with the same shape as the convex corner portion AC of the surface layer of the first conductive portion A may also be provided on the inner layer of the first conductive portion A. Similarly, when the second conductive portion B is multi-layered, not only is a concave corner portion BC provided on the surface layer of the second conductive portion B, but a concave corner portion BC with the same shape as the concave corner portion BC of the surface layer of the second conductive portion B may also be provided on the inner layer of the second conductive portion B.
[0093] While this disclosure has been described based on embodiments, it should be understood that this disclosure is not limited to the above embodiments and structures. This disclosure also includes various modifications and equivalent variations. Furthermore, various combinations and arrangements, and consequently, combinations and arrangements containing only one element, or more than or less thereof, also fall within the scope and spirit of this disclosure.
Claims
1. An electronic device having a substrate and a circuit mounted on the substrate, the circuit having a first conductive portion and a second conductive portion at a different potential from the first conductive portion. When viewed from above in the thickness direction of the substrate, The first conductive portion has a convex corner with a rounded top, and the second conductive portion has a concave corner opposite the convex corner. The convex angle is formed by the extensions of two straight lines that continuously form the outline of the first conductive part. The concave angle is formed by the extensions of two straight lines that continuously form the contour of the second conductive portion. Define the straight line passing through the vertices of the convex and concave angles as an angle line, define the intersection of the angle line and the convex angle as the convex angle point, and define the intersection of the angle line and the concave angle as the concave angle point. The distance from the convex corner to the concave corner, i.e., the inter-corner distance, is longer than the distance from the vertex of the convex corner to the vertex of the concave corner, i.e., the inter-corner distance. The circuit includes a drive circuit for driving the inverter's switches and a control circuit for controlling the drive circuit. The first conductive part is part of the driving circuit, and the second conductive part is part of the control circuit.
2. The electronic device as claimed in claim 1, characterized in that, The radius of curvature of the concave corner is smaller than that of the convex corner.
3. The electronic device as described in claim 2, characterized in that, The radius of curvature of the concave corner is less than 0.2 mm.
4. The electronic device as claimed in any one of claims 1 to 3, characterized in that, The concave corner portion is substantially concave in shape and substantially has a concave apex.
5. An electronic device having a substrate and a circuit mounted on the substrate, the circuit having a first conductive portion and a second conductive portion at a different potential from the first conductive portion. When viewed from above along the thickness direction of the substrate, the first conductive portion has a convex corner portion whose top changes from a convex angle to a rounded shape, and the second conductive portion has a concave corner portion opposite to the convex corner portion, which is substantially concave in shape and has a concave apex. The circuit includes a drive circuit for driving the inverter's switches and a control circuit for controlling the drive circuit. The first conductive part is part of the driving circuit, and the second conductive part is part of the control circuit.