Electronic Control Unit

Abstract

The electronic control unit has a substrate (30), the substrate (30) includes terminal connection parts (33, 34), the terminal connection parts (33, 34) are through holes extending from a first surface (301) through the substrate to a second surface (302). Resist openings (37, 38) along the outer edges of the terminal connection parts (33, 34) expose the circuit pattern from the surface resist layer (47). A plurality of vias (331, 332, 341, 342) are arranged at positions adjacent to the resist openings in a heat receiving area (H) to facilitate heat transfer from the first surface (301) to the second surface (302) during a soldering process.

Description

Technical Field

[0001] The present disclosure relates to an electronic control unit (ECU) and an electric power steering apparatus using the ECU. Background Art

[0002] Hitherto, drive devices provided with connectors are known. For example, in Japanese Patent No. JP2015-106973 (i.e., Patent Document 1), connector terminals are inserted into a substrate from one side of the substrate (i.e., from one of the two main surfaces of the substrate) and connected to wiring on the surface on the other side of the substrate.

[0003] When the substrate and the terminal are connected by soldering the terminal to one surface of the substrate, it may not be easy to transfer the heat of soldering to the other surface of the substrate, which may result in poor solderability of the terminal and the substrate. Summary of the invention

[0004] The electronic control unit of the present disclosure includes a substrate and an outermost terminal. The substrate includes a plurality of circuit patterns, a surface resist layer, a terminal connection portion, a resist opening, and a plurality of via holes.

[0005] The circuit pattern is layered into the first layer to the nth layer, wherein n is an integer of 2 or greater. The surface resist layer is arranged on the first layer or on the first layer side of the substrate. The terminal connection portion is a through hole that penetrates the first main surface of the substrate, extends through the substrate and penetrates the second main surface of the substrate. The resist opening exposes the first circuit pattern on the first layer from the surface resist layer along the outer edge of the terminal connection portion. A plurality of vias are arranged outside the resist opening and adjacent to the position of the resist opening.

[0006] The vias include a plurality of external vias formed in the heat receiving region and on the peripheral side of the substrate between the resist opening and the periphery of the substrate. The heat receiving region is configured to receive heat from a connecting member such as welding during a connection process when the outermost terminal is inserted into the terminal connecting portion and connected to the outermost terminal by the connecting member.

[0007] By forming a via in the heat receiving area, the via can help assist the terminal connection part in transferring heat from the first surface side to the second surface side of the substrate during the welding process to improve the weldability of the terminal to the substrate in the terminal connection part to provide a better welding connection between the terminal and the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings, in which:

[0009] Figure 1 A block diagram showing a steering system in a first embodiment of the present disclosure;

[0010] Figure 2 shows a cross-sectional view of the drive device in the first embodiment;

[0011] Figure 3 A plan view showing a first surface side of a substrate in a first embodiment;

[0012] Figure 4 A plan view showing a power terminal connection portion and a ground terminal connection portion in a first embodiment;

[0013] Figure 5 shows a plan view of a ground terminal connecting portion according to a first embodiment;

[0014] Figure 6 shows a plan view of the via in the first embodiment;

[0015] Figure 7 Shown along Figure 5 A cross-sectional view of the substrate and the ground terminal taken along line VII-VII in FIG.

[0016] Figure 8 shows a cross-sectional view of a substrate in a second embodiment of the present disclosure;

[0017] Fig. 9 A schematic diagram showing a second circuit pattern in a second embodiment;

[0018] Fig.10 A schematic diagram showing a third circuit pattern in the second embodiment;

[0019] Fig.11 A plan view showing a ground terminal connecting portion in a third embodiment of the present disclosure;

[0020] Fig.12 shows a plan view of a via of a third embodiment;

[0021] Fig.13 Shown along Fig.11 A cross-sectional view of the substrate and the ground terminal connection portion taken along the line XIII-XIII in FIG.

[0022] Fig.14 shows a cross-sectional view of a substrate in a fourth embodiment of the present disclosure;

[0023] Fig.15 A schematic diagram showing a second circuit pattern in a fourth embodiment;

[0024] Fig.16 A schematic diagram showing a third circuit pattern in a fourth embodiment;

[0025] Fig.17 a view showing the second surface side of the ground terminal connecting portion in the fourth embodiment; and

[0026] Fig.18 A cross-sectional view of a substrate in a fifth embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0027] Various embodiments of the present disclosure are described with reference to the accompanying drawings. In the following embodiments, the same features and elements in each embodiment may be denoted by the same reference numerals, and repeated descriptions of the same features and elements previously described may be omitted from the descriptions of the following embodiments.

[0028] (First Embodiment)

[0029] Reference Figure 1 An electronic control unit (ECU) 10 and a motor 80 are included together in the electric power steering device 8 to provide power assistance (eg, power steering) to assist the vehicle steering operation. Figure 1 The overall configuration of a steering system 90 including the electric power steering device 8 is shown. The steering system 90 further includes a steering wheel 91, a steering shaft 92, a pinion 96, a rack shaft 97, and wheels 98, as well as the electric power steering device 8.

[0030] The steering wheel 91 is connected to a steering shaft 92. The steering shaft 92 includes a torque sensor 94 for detecting a steering torque. The torque sensor 94 includes a first torque detection unit 194 and a second torque detection unit 294. A pinion 96 is provided at one end of the steering shaft 92. The pinion 96 meshes with a rack shaft 97. Wheels 98 are connected to both ends of the rack shaft 97 via a connecting rod or a similar mechanical link.

[0031] When the driver rotates the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 is rotated. The rotational motion of the steering shaft 92 is converted into linear motion by the pinion 96, so that the rack shaft 97 moves in a linear manner. A pair of wheels 98 is turned at an angle corresponding to the displacement amount of the rack shaft 97.

[0032] The electric power steering device 8 includes a reduction gear 89 and a drive device 40 having a motor 80 and an ECU 10. The reduction gear 89 is a power transmission unit that reduces the rotation of the motor 80 and transmits the rotation to the steering shaft 92. In the present embodiment, the electric power steering device 8 may be, for example, a "column-assisted" electric power steering device. However, the electric power steering device 8 may also be a "rack-assisted" electric power steering device that transmits the rotation of the motor 80 to the rack shaft 97.

[0033] like Figure 2As shown, the motor 80 outputs part or all of the torque for steering and is driven by power provided by a battery (not shown) to rotate the reduction gear 89 back and forth. The motor 80 may be, for example, a three-phase brushless motor having a rotor 860 and a stator 840.

[0034] The motor 80 has a first motor winding 180 and a second motor winding 280. The first motor winding 180 may be a first winding group, for example, having a winding corresponding to each of the three phases (e.g., U phase, V phase, and W phase). Similarly, the second motor winding 280 may be a second winding group. The motor windings 180 and 280 have the same electrical characteristics and are de-wound on a common stator 840, wherein the electrical angles of the motor windings 180 and 280 are offset by 30 degrees from each other. In response to such a configuration, the motor windings 180 and 280 are controlled to receive a supply of phase currents having a 30-degree phase shift between phases, respectively. By optimizing the phase difference of the supply current, the output torque can be improved. The sixth harmonic (e.g., sixth harmonic distortion) of the torque ripple can also be reduced by optimizing the phase difference. Since the current is averaged by the phase difference supply, the amount of electrical noise and vibration that can be eliminated is maximized. Since heat generation is also averaged, temperature-related inter-system errors occurring in detection values ​​of sensors (for example, torque values ​​detected by a torque sensor) can be reduced, and the amount of current that can be supplied is also averaged.

[0035] The combination of devices related to the drive control of the motor 80 through the first motor winding 180 is referred to as a first system, and the combination of devices related to the drive control of the motor 80 through the second motor winding 280 is referred to as a second system. In addition, the devices related to the first system are mainly numbered with 100 (i.e., with "1" as a prefix or as the most significant digit), and the devices related to the second system are mainly numbered with 200. In the first system and the second system, the same features, elements, and configurations can be numbered with the same numbers (e.g., the least significant digits are the same numbers). For example, the first motor winding is 180, where "1" in 180 indicates that the first motor winding 180 is in the first system. The second motor winding is 280, where "2" in 280 indicates that the second motor winding 280 is in the second system. The first motor winding 180 and the second motor winding 80 both have "80" as the least significant digit, indicating substantially similar or identical features, elements, or configurations.

[0036] The drive device 40 can integrate the ECU 10 and the motor 80 together in an integral package as a "mechanical-controller integrated" drive device 40. The ECU 10 can be "axially" set at one end of the motor 80. That is, the ECU 10 can be set at one end of the motor 80 along the direction of the longitudinal axis Ax. Although the ECU 10 and the motor 80 are described as being integrated here, the motor 80 and the ECU 10 can be set separately. The ECU 10 is set on one side of the motor 80 coaxially with the axis Ax of the shaft 870 and opposite to the output shaft of the motor 80. However, the ECU 10 can be set on the output shaft side of the motor 80. By adopting a mechanical-controller integrated configuration, the ECU 10 and the motor 80 can be efficiently arranged and installed in a vehicle with a limited amount of installation space.

[0037] The motor 80 includes a stator 840, a rotor 860, and a housing 830. The housing 830 accommodates both the rotor 860 and the stator 840 and other components. The stator 840 is fixed to the housing 830, and the motor windings 180 and 280 are wound on the stator 840. The rotor 860 is disposed on the radial inner side of the stator 840 (that is, the rotor is disposed closer to the shaft 870 than the stator 840). The rotor 860 rotates relative to the stator 840.

[0038] The shaft 870 is inserted into the rotor 860 to form an integral assembly, and the shaft 870 rotates integrally with the rotor 860. The shaft 870 is rotatably supported by bearings 835 and 836 in the housing 830. The end of the shaft 870 on the ECU 10 side protrudes from the housing 830 toward the ECU 10. The magnet 875 is provided on the end of the shaft 870 on the ECU 10 side. The magnet 875 rotates with the shaft 870 and can be used as a detection target (for example, to detect the rotation of the shaft 870 and the rotor 860).

[0039] The housing 830 has a closed bottom cylindrical housing 834 including a rear frame end 837 as a bottom. The open side of the housing 834 is covered by a front frame end 838. The housing 834 and the front frame end 838 are fastened to each other by fasteners such as bolts. A lead insertion hole 839 is formed through the rear frame end 837. The leads 185 and 285 are connected to the respective phases of the motor windings 180 and 280 and are inserted through the lead insertion hole 839. The leads 185 and 285 extend out from the lead insertion hole 839 and extend toward the ECU 10 and are connected to the substrate 30.

[0040] The ECU 10 includes a cover 460 , a substrate 30 , and various electronic components mounted on the substrate 30 .

[0041] The cover 460 protects the electronic components from external impact and prevents contaminants such as dust and water from entering the interior of the ECU 10. The cover 460 includes a cover body 461 and a connector portion 462.

[0042] The cover body 461 and the connector portion 462 may be integrally formed so that the cover 460 is a one-piece structure. Alternatively, the connector portion 462 may be provided separately from the cover body 461.

[0043] The connector portion 462 is disposed at an axial end (e.g., along the axis Ax) of the drive device 40. The connector portion 462 has an opening facing away from the motor 80. The connector portion 462 includes a power terminal 463 and a ground terminal 464. The end of the power terminal 463 on the connector portion 462 is connected to a power source (not shown). The end of the ground terminal on the connector portion 462 is connected to a ground or power return path (not shown). The other ends of the power terminal 463 and the ground terminal 464 are connected to the substrate 30. The power terminal 463 and the ground terminal 464 may also be referred to as the outermost terminals 463 and 464.

[0044] Although not in Figure 2 , but the connector portion 462 may also include a control terminal including a vehicle communication terminal for connecting the drive device 40 to the vehicle communication system and a torque terminal for connecting the drive device 40 to the torque sensor 94. The control terminal and the torque terminal may be integrally formed in the connector portion 462, or may be a portion separate from the connector portion 462. For example, based on the number of input signals to the drive device 40 / the number of output signals from the drive device 40, the number of connectors and the number of terminals may be arbitrarily changed.

[0045] The substrate 30 may be, for example, a printed circuit board (PCB). The substrate 30 has one main side (i.e., main face / main surface) facing the rear frame end 837 and one main side facing the connector portion 462. The facing direction of the main surface of the substrate 30 may also be described relative to the motor 80 (e.g., facing the motor 80 or facing away from the motor 80).

[0046] like Figure 7As shown in , the substrate 30 may be a four-layer substrate having multi-layer through holes (e.g., vias) drilled through one or more layers of each layer to electrically connect circuits on different layers. In the present embodiment, since the power terminal 463 and the ground terminal 464 are inserted into the through holes on the substrate 30 on the side of the substrate 30 opposite to the motor 80, the tips of the power terminal 463 and the ground terminal 464 protrude toward the motor 80. Therefore, welding work of welding the tips of the power terminal 463 and the ground terminal 464 to the substrate 30 is performed on the side of the substrate 30 facing the motor 80 (i.e., on the motor-facing side of the substrate 30). Welding can be used to attach electronic components to the substrate 30, and to form an electrical connection between such electronic components and the substrate 30. Therefore, welding can also be referred to as a connecting member.

[0047] Of the two main surfaces of the substrate 30, the surface facing the motor 80 on which the welding work is performed (i.e., the motor side surface) is referred to as the first surface 301, and the other surface opposite to the motor 80 (i.e., the surface facing away from the motor 80) is referred to as the second surface 302. The layers of the substrate 30 are referred to as the first layer L11, the second layer L12, the third layer L13, and the fourth layer L14. These layers are arranged in ascending order from the first surface 301, wherein the first layer L11 is disposed closest to the motor 80. A first circuit pattern 41 is formed on the first layer L11, a second circuit pattern 42 is formed on the second layer L12, a third circuit pattern 43 is formed on the third layer L13, and a fourth circuit pattern 44 is formed on the fourth layer L14. An interlayer insulating layer 49 is formed between the circuit patterns 41, 42, 43, and 44 (i.e., 41 to 44). A surface resist layer 47 is formed on the first surface 301, and a surface resist layer 48 is formed on the second surface 302.

[0048] like Figure 2 and Figure 3 As shown in FIG. 1 , the switch elements 121 and 221, the rotation angle sensor 25, and a custom integrated circuit (IC) (not shown) forming a drive circuit are mounted on the first surface 301 of the substrate 30. The rotation angle sensor 25 is mounted at a position facing the magnet 875 to detect a change in the magnetic field caused by the rotation of the magnet 875.

[0049] like Figure 3As shown in the figure, capacitors 128 and 228, coil 29 and computers 130 and 230 are mounted on the second surface 302 of the substrate 30. Computers 130 and 230 can be small computers (i.e., microcomputers), such as microcontrollers or systems on chips (SoCs). Capacitors 128 and 228 smooth the power input from a battery (not shown). Capacitors 128 and 228 also assist in supplying power to the motor 80 by storing charge. Capacitors 128 and 228 and coil 29 form a filter circuit to reduce electrical noise transmitted to / from other devices that share a battery with the drive device 40. Other electrical components such as power relays, motor relays and current sensors (all not shown) can also be mounted on the first surface 301 or on the second surface 302. In the present embodiment, electronic components are mounted on a single substrate 30. However, electronic components can be mounted on two or more substrates.

[0050] A substrate fixing portion 31, motor wire connection portions 186 and 286, a control terminal connection portion 32, a power terminal connection portion 33, and a ground terminal connection portion 34 are formed on the substrate 30. The substrate fixing portion 31, the motor wire connection portions 186 and 286, the control terminal connection portion 32, the power terminal connection portion 33, and the ground terminal connection portion 34 are all arranged in a peripheral area near the outer edge / periphery of the substrate 30. By arranging the substrate fixing portion 31, the motor wire connection portions 186 and 286, the control terminal connection portion 32, and the power terminal connection portion 33 near the periphery, more space toward the center of the substrate (e.g., away from the periphery) can be provided / reserved as an installation space for installing electrical components. The substrate fixing portion 31, the motor wire connection portions 186 and 286, the control terminal connection portion 32, the power terminal connection portion 33, and the ground terminal connection portion 34 are through holes extending through the substrate 30 to establish an electrical connection between the first surface 301 and the second surface 302. The inner wall of the through hole is plated with a conductive material such as copper to form a through hole pad / through hole barrel. The through hole pad may refer to the electroplated portion of the through hole closer to the first surface 301 and the second surface 302, and the through hole solder barrel may refer to the plated portion set in the center of the middle of the substrate 30. For ease of description, the through hole pad may refer to the plated portion at any position on the through hole regardless of the position, and includes the pad portion and the solder barrel portion. The inner wall of the substrate fixing portion 31 may not be plated.

[0051] Screws or the like connectors (not shown) are inserted into the substrate fixing portion 31 to fix the substrate 30 to the rear frame end portion 837 .

[0052] Lead wire 185 is inserted into motor wire connection portion 186 and can be electrically connected to the motor wire connection portion by solder or similar bonding material / process. Similarly, lead wire 285 is inserted into and soldered to motor wire connection portion 286. Control terminal is inserted into control terminal connection portion 32 and is electrically connected to control terminal connection portion 32 by solder or similar bonding material / connection member.

[0053] like Figure 4 As shown in FIG. 3 , the power terminal 463 is inserted into the power terminal connection portion 33 and electrically connected to the power terminal connection portion 33 by solder or a similar bonding material / connecting member. The grounding terminal 464 is inserted into the grounding terminal connection portion 34 and electrically connected to the grounding terminal connection portion 34 by solder or a similar bonding material / connecting member. A through-hole pad is formed on the inner wall surface of the power terminal connection portion 33. A portion of the through-hole pad on the first surface 301 side is exposed from the surface resist layer 47 and is referred to as a resist opening 37. A through-hole pad is formed on the inner wall surface of the grounding terminal connection portion 34. Figure 7 The through hole pad 39 shown in FIG. Figure 4 and Figure 5 As shown in FIG. 3 , a portion of the via pad 39 on the first surface 301 side is exposed from the surface resist layer 47 and is referred to as a resist opening 38. The via pad is connected to the circuit pattern of each layer and can be considered as a part of the circuit pattern.

[0054] like Figure 3 and Figure 4 As shown in the plan view in FIG. 1 , the power terminal connection portion 33 and the ground terminal connection portion 34 each have a substantially elliptical shape. The short sides of the power terminal connection portion 33 and the ground terminal connection portion 34 are arranged adjacent to each other. Assuming that the terminal connection portions 33 and 34 have an elliptical shape, the short side here refers to the area around the vertex on the major axis of the ellipse (i.e., the side near the end of the major axis of the ellipse).

[0055] like Figure 3 As shown in FIG. 1 , the coil 29 is installed at a position close to the power terminal connection portion 33. The coil 29 is arranged radially inside the power terminal connection portion 33 (i.e., at a position closer to the center of the substrate 30). The power terminal connection portion 33 and the coil 29 are connected by a wide circuit pattern having a width greater than half that of the power terminal connection portion 33.

[0056] The power terminal connection portion 33 has a circuit pattern having a width greater than half the length of the long side of the power terminal connection portion 33 (e.g., greater than half the width of the long axis of the power terminal connection portion). For example, the circuit pattern may have a width of 2 mm or more. Therefore, when the power terminal 463 and the power terminal connection portion 33 are connected by welding, it may be easy to dissipate heat through the circuit pattern, and it is not easy to transfer the heat from the welding process to the second surface 302 of the substrate 30, which may affect the weldability of the power terminal 463 to the power terminal connection portion 33. On the other hand, in the case where the terminal is narrow, for example, in the case where the terminal is a thin line and the circuit pattern of the connection portion is narrow, it is not easy to dissipate heat from the welding process toward the circuit pattern and therefore not easy to dissipate heat from the welding process through the circuit pattern. Therefore, the heat from the welding operation of welding the control terminal to the control terminal connection portion can be better transferred from the first surface 301 to the second surface 302 to improve the weldability of the control terminal to the substrate 30. Therefore, when the power terminal 463 and the substrate 30 are welded, the heat from the welding may be dissipated through the wide circuit pattern, and the weldability of the power terminal 463 to the substrate 30 may be worse than the weldability of the control terminal to the substrate 30. In terms of welding, the same as the power terminal 463 may be applied to the ground terminal 464, that is, the connection to the wide circuit pattern may affect the weldability of the ground terminal 464 to the substrate 30.

[0057] In the present embodiment, the terminal connection parts 33 and 34 are arranged side by side, wherein the short sides of the terminal connection parts 33 and 34 are adjacent to each other. In this arrangement, it is easier to dissipate heat than in an arrangement in which the long sides of the terminal connection parts 33 and 34 are adjacent to each other. The power terminal 463 is arranged relatively close to the coil 29. The coil 29 is a relatively large component with a large heat capacity, and therefore, there may be a problem that the heat from the welding operation is dissipated to the coil 29. Although the weldability of the object to the substrate 30 can be improved by heating the welding object before welding, such an approach may cause damage to the substrate 30 and the components mounted on the substrate 30, increase the energy used for welding, increase the manufacturing time, and may cause other problems.

[0058] In this embodiment, if Figure 4 and Figure 5 As shown in FIG. 1 , via holes 331 and 332 are disposed outside the resist opening 37 and adjacent to the resist opening 37 to surround the power terminal connection portion 33. Similarly, via holes 341 and 342 are disposed outside the resist opening 38 and adjacent to the resist opening 38 to surround the ground terminal connection portion 34. In the present embodiment, the via holes 331, 332, 341, and 342 are arranged along the outer edges of the resist openings 37 and 38.

[0059] The vias 331 and 332 are connected to the through-hole pad / solder barrel formed in the power terminal connection portion 33 through the circuit pattern, and the vias 331 and 332 have the same potential as the power terminal connection portion 33. The vias 341 and 342 are connected to the through-hole pad / solder barrel 39 formed in the ground terminal connection portion 34 through the circuit pattern, and the vias 341 and 342 have the same potential as the ground terminal connection portion 34.

[0060] The inner vias 331 and 341 are formed and arranged closer to the center of the substrate 30 than the terminal connections 33 and 34. The outer vias 332 and 342 are formed and arranged closer to the periphery of the substrate 30 than the terminal connections 33 and 34. The functions of the inner vias 331 and 341 are the same, and the functions of the outer vias 332 and 342 are the same. Therefore, the following description focuses on the vias 341 and 342 formed around the ground terminal connection 34.

[0061] like Figure 5 and Figure 6 As shown in FIG. 3 , vias 341 and 342 are formed in the heat receiving region H. The heat receiving region H is a region that contacts the solder during soldering. Since the substrate 30 of the present embodiment is a through-hole substrate, the vias 341 and 342 are through holes extending through the entire substrate 30 to connect the first surface 301 and the second surface 302. That is, the vias 341 and 342 penetrate the first surface 301, extend through the substrate 30, and penetrate the second surface 302 to form a through hole extending through the substrate 30.

[0062] Figure 6 One internal via 341 is shown. Since the internal via 341 is a through hole, the surface resist layer 47 cannot be formed on the surface of the internal via 341. Therefore, the first circuit pattern 41 of the first layer L11 is exposed around the internal via 341. The circuit pattern around the external via 342 is configured in the same manner. For example, Figure 5 As shown, a surface resist layer 47 is formed at a position between the via holes 341 and 342 and the resist opening 38 on the first surface 301. In other words, the via holes 341 and 342 and the resist opening 37 do not form a continuous area, and the surface resist layer 47 is inserted therebetween to separate the via holes 341 and 342 from the resist opening 37.

[0063] exist Figure 6 The heat receiving area H is indicated by a double-dashed line in FIG. The heat receiving area H is an area that contacts the solder when the ground terminal 464 and the substrate 30 are connected. During soldering, heat is transferred to the second surface 302 in order to generate a solder reflow fillet. Therefore, in this embodiment, Figure 5 and Figure 7As shown in , the circuit pattern 41 on the first surface 301 (i.e., the soldering surface) is spread wide to better receive the heat from soldering and assist in dissipating the heat to the second surface 302 (i.e., the non-soldering surface). The internal via 341 also acts as an obstacle to limit and / or prevent the heat on the first surface 301 from being dissipated toward the center of the first surface 301 of the substrate 30, so as to better retain the heat around the ground terminal connection portion 34 and guide the transfer of heat from the first surface 301 to the second surface 302. As shown in FIG. Figure 7 As shown near the top of Figure 7 The right side of is a direction extending toward the periphery of the substrate 30 , and the left side is a direction extending toward the center of the substrate 30 .

[0064] like Figure 7 As shown in , the radial dimensions of the circuit patterns 42, 43, and 44 can be made smaller than the radial dimensions of the circuit pattern 41 in the outer region extending toward the periphery on the peripheral side of the outer via 342. By making the circuit patterns 42, 43, and 44 formed on the layers L12, L13, and L14, respectively, as small as possible in the outer region (i.e., on the peripheral side), heat dissipation toward the periphery of the substrate 30 can be limited and / or prevented. Such a configuration can be used to improve solder swelling during the soldering operation, and is particularly beneficial in the case of poor solder swelling.

[0065] In an area radially closer to the center of the substrate than the internal via 341, the circuit patterns 42, 43, and 44 formed on the layers L12, L13, and L14, respectively, include isolation portions 425, 435, and 445, respectively, for separating a portion of each corresponding pattern 42, 43, and 44 connected to the center of the substrate 30 from a portion of each corresponding pattern connected to the ground terminal connection portion 34. The isolation portions 425, 435, and 445 limit and / or prevent heat from being dissipated radially toward the center of the substrate 30 to better retain heat around the ground terminal connection portion 34 and improve heat transfer from the first surface 301 to the second surface 302 during a soldering operation.

[0066] As described above, the ECU 10 in the present embodiment includes a substrate 30, a power terminal 463, and a ground terminal 464. The substrate 30 has circuit patterns 41 to 44, a surface resist layer 47, terminal connection parts 33 and 34, resist openings 37 and 38, and a plurality of vias 331, 332, 341, and 342. The circuit patterns 41 to 44 are layered into the first layer to the nth layer, where n is an integer of 2 or more. In the present embodiment, there are four layers of circuit patterns (i.e., n=4). The surface resist layer 47 is disposed on the first layer L11. The terminal connection parts 33 and 34 are through holes that penetrate the first surface 301 on the first layer L11, extend through the substrate 30, and penetrate the second surface 302 on the fourth layer L14, the nth layer in this example. The resist openings 37 and 38 expose the circuit pattern from the surface resist layer 47 along the outer edges of the terminal connection parts 33 and 34. The via holes 331 , 332 , 341 , and 342 are provided at positions outside the resist openings 37 and 38 .

[0067] The power terminal 463 is inserted into the power terminal connection portion 33 near the outermost periphery of the substrate 30 , and is electrically connected to the substrate 30 by soldering.

[0068] The ground terminal 464 is inserted into the ground terminal connection portion 34 near the outermost periphery of the substrate 30 and is electrically connected to the substrate 30 by welding. The outermost terminals of the present embodiment are the power terminal 463 connected to the power supply (not shown) and the ground terminal 464 connected to the ground or power return path (not shown). On the substrate 30, no other terminals are provided outside the power terminal 463 and the ground terminal 464 (i.e., at a position closer to the periphery of the substrate 30 than the terminals 463 and 464). In this way, the terminals 463 and 464 are considered to be "outermost terminals".

[0069] The vias include a plurality of external vias 332 formed and disposed in the heat receiving region H. The heat receiving region H receives heat from soldering when the power terminal 463 is soldered to the substrate 30. The external vias 332 are formed / disposed closer to the substrate periphery than the resist openings 37.

[0070] The vias also include a plurality of external vias 342 formed / arranged in the heat receiving region H. The heat receiving region H receives heat from welding when the ground terminal 464 is welded to the substrate 30, wherein the external vias 342 are formed / arranged closer to the periphery of the substrate 30 than the resist opening 38.

[0071] The heat receiving area H is an area in contact with the solder during welding. Vias 331, 332, 341 and 342 are formed / arranged in the heat receiving area H to receive heat from the first surface 301 (i.e., the surface 301 (i.e., welding surface) of the substrate 30 being welded). The terminal connecting parts 33 and 34 can contribute to the heat dissipation from the first surface 301 to the second surface 302. That is, by limiting and / or preventing heat from being dissipated toward the center of the substrate 30 or the periphery of the substrate 30 via the circuit pattern, the vias 331, 332, 341 and 342 can also keep heat around the terminal connecting parts 33 and 34. By configuring the substrate 30 to dissipate and manage the heat from welding in such a way, the welding of electronic components to the substrate 30 is improved, and thus the connectivity between the substrate 30 and the terminals 463 and 464 is improved. In particular, when a terminal with a wider width (e.g., power terminal 463 or ground terminal 464) is connected to a relatively wide circuit pattern, or when a component with a large heat capacity is mounted near such a terminal with a wider width, heat tends to be dissipated toward such a circuit pattern or a component with a large heat capacity. Therefore, by including vias 331, 332, 341, and 342 to assist in heat dissipation and heat control, heat dissipation can be better controlled and the solderability of the component to the substrate 30 can be improved.

[0072] The vias include a plurality of external vias 332 and 342 and a plurality of internal vias 331 and 341, and the plurality of internal vias 331 and 341 are formed closer to the center of the substrate 30 than the external vias 332 and 342. Similar to the external vias 332 and 342, the internal vias 331 and 341 assist in transferring heat from the first surface 301 to the second surface 302. The internal vias 331 and 341 also act as obstacles to limit and / or prevent heat from being radially dissipated toward the center of the substrate via the circuit pattern. By controlling the dissipation of heat in this way, the solderability of the component to the substrate 30 can be improved.

[0073] The vias 331, 332, 341, and 342 are through holes that penetrate the first surface 301 and the second surface 302 and extend through the layers of the substrate 30. A surface resist layer 47 is formed between the vias 331, 332, 341, and 342 and the resist opening 37 on the first surface 301. In the present embodiment, since the vias 331 and 332 and the power terminal connection portion 33 are connected by a circuit pattern, the expansion of the resist opening 37 can be limited and / or prevented by covering the connection circuit pattern with a resist. Similarly, since the vias 341 and 342 and the ground terminal connection portion 34 are connected by a circuit pattern, the expansion of the resist opening 38 can be limited and / or prevented by covering the connection circuit pattern with a resist.

[0074] The circuit pattern formed at a position closer to the center of the substrate 30 than the terminal connection parts 33 and 34 includes isolation parts 425, 435 and 445 to separate the circuit pattern connected to the terminal connection parts 33 and 34 from the circuit pattern extending toward the center of the substrate 30. In the present embodiment, the isolation parts 425, 435 and 445 are formed (i.e., provided) in the circuit patterns 42, 43 and 44, respectively (i.e., in the circuit pattern other than the first circuit pattern 41). By including such isolation parts 425, 435 and 445 in the circuit pattern, the radial dissipation of heat away from the connection terminals 33 and 34 and toward such circuit pattern extending toward the center of the substrate 30 can be reduced / or eliminated (i.e., suppressed) to improve the heat transfer from the first surface 301 to the second surface 302.

[0075] The electric power steering device 8 includes an ECU 10 and a motor 80. The electric power steering device 8 has power terminals such as a power terminal 463 and a ground terminal 464 that can handle large currents. Because large currents can be supplied to terminals 463 and 464, terminals 463 and 464 are configured to have a wider width than other terminals and are connected to a wider circuit pattern with a larger area in the substrate 30. However, such a large circuit pattern can allow heat from the welding operation to be dissipated through the circuit pattern, and this may cause problems with the welding operation. Therefore, by forming vias 331, 332, 341 and 342, heat from the welding process can be kept around the terminal connection parts 33 and 34. It is also possible to better dissipate heat from the welding process from the first surface 301 to the second surface 302 via vias 331, 332, 341 and 342 connected to the terminal connection parts 33 and 34, while limiting and / or preventing heat dissipation to the circuit pattern. By controlling heat dissipation in this way, the solderability of electronic components to the substrate 30 can be improved.

[0076] (Second Embodiment)

[0077] Reference Figure 8 , Fig. 9 and Fig.10 A second embodiment of the present disclosure is described. In this embodiment, the ground terminal connection portion 34 and the vias 341 and 342 are mainly described, with attention paid to the circuit patterns 42, 43, and 44 in the second layer L12, the third layer L13, and the fourth layer L14, respectively. As described with reference to the first embodiment, the power terminal connection portion 33 and the vias 331 and 332 are substantially the same in the second embodiment, and therefore a repeated description of these features in the second embodiment is omitted. In subsequent embodiments, the same features and elements previously described in the previous embodiments may be omitted from the description of the subsequent embodiments.

[0078] Figure 8The cross section of the substrate 30 shown in FIG. Figure 7 A cross section of a first embodiment is described. Fig. 9 The circuit pattern 42 of the second layer L12 is shown. Fig.10 The circuit pattern 43 of the third layer L13 is shown. Fig. 9 and Fig.10 2 and 3 show circuit patterns around / near the ground terminal connection portion 34. Fig. 9 and Fig.10 In both, the upper side of the figure corresponds to the orientation toward the periphery of the substrate 30, and the lower side of the figure corresponds to the orientation toward the center of the substrate 30. In the present embodiment, the circuit pattern of the first layer L11 is the same as that in the first embodiment, for example, as shown in FIG. Figure 5 The circuit pattern 44 of the fourth layer L14 is the same as the circuit pattern 43 of the third layer L13.

[0079] In some cases, the inner via 341 may be connected to the ground pattern 421 on the center side of the second layer L12 for product performance. In such an example, the isolation portion 425 cannot be formed on the second layer L12. When the inner via 341 is not provided, the heat received from the first surface 301 during welding is transferred to the second surface 302 only through the ground terminal connection portion 34 and the outer via 342. In this case, the heat can be mainly dissipated from the ground terminal connection portion 34 to the inner layer pattern, and the heat dissipated to the second surface 302 can be reduced. That is, the heat transferred from the first surface 301 to the second surface 302 may not be sufficient to ensure a good welding operation.

[0080] In the present embodiment, the internal via 341 helps to transfer heat from the first surface 301 to the second surface 302, and the internal via 341 also acts as an obstacle to suppress the heat dissipation toward the center of the substrate 30 to the connected circuit pattern. In the second circuit pattern 42 of the second layer L12, when the ground pattern 421 extending toward the center of the substrate 30 is connected to the ground terminal connecting portion 34, as shown in FIG. Fig. 9 As shown in , the number of connections between the vias and the ground pattern 421 is limited to a minimum to limit the number of possible heat dissipation paths to the surrounding patterns. Fig. 9 In the example of , the ground pattern 421 is connected to the inner via 341 but not to the outer via 342. Fig. 9 In the example of , seven internal vias 341 are formed, all of which are connected to the pattern 421. However, in order to minimize the number of heat dissipation paths as described above, only five of the internal vias 341 may be connected to the pattern 421, while two of the internal vias 341 are not connected to the pattern 421.

[0081] On the second layer L12, the external via 342 and the ground terminal connection portion 34 are connected by an auxiliary pattern 422. The auxiliary pattern 422 is a relatively narrow circuit pattern having a width substantially equal to the outer diameter of the external via 342. The external via 342 is not connected to other circuit patterns (i.e., patterns other than the auxiliary pattern 422) to limit heat dissipation to other circuit patterns to better facilitate heat dissipation to the second surface 302. A resist layer is formed on the auxiliary pattern 422 to limit and / or prevent any expansion of the through-hole pad 39.

[0082] Reference Figure 8 and Fig.10 , on the third layer L13, the circuit pattern is not connected around the ground terminal connection portion 34. Therefore, both the internal via 341 and the external via 342 are connected to the ground terminal connection portion 34 through the auxiliary pattern 432. The internal via 341 and the external via 342 are not connected to other circuit patterns (i.e., patterns other than the auxiliary pattern 432) to limit heat dissipation to other circuit patterns, better retain heat around the terminal connection portion (e.g., the terminal connection portion 34), and better facilitate heat dissipation from the first surface 301 to the second surface 302. The same principle applies to the fourth layer L14.

[0083] Depending on the amount of power supplied to the substrate 30, there may be only one circuit pattern (e.g., a power pattern) on a single layer connected to the power terminal connection portion 33. In this case, the internal via and the external via may be connected to the terminal connection portion through an auxiliary pattern, similar to Fig.10 The arrangement shown in .

[0084] On the third layer L13 and the fourth layer L14, the vias 341 and 342 are connected to the ground terminal connection portion 34 through the auxiliary pattern 432 included for each via. On the second layer L12, the inner via 341 is included in the pattern 421 extending from the ground terminal connection portion 34 toward the center of the substrate 30, and the outer via 342 is connected to the ground terminal connection portion 34 through the auxiliary pattern 422 provided for each via.

[0085] When the connection between the ground terminal connection portion 34 and the pattern 421 extending toward the center of the substrate 30 is provided for product performance, the connection between the connection portion 34 and the pattern 421 is provided by the minimum number of connections, and has been / or provided by other auxiliary connections using relatively narrow / thin auxiliary patterns 422 and 432. By limiting the connection of the vias 341 and 342 to the pattern extending toward the center of the substrate 30 as much as possible, heat transfer toward the second surface 302 is better facilitated while suppressing heat dissipation to other circuit patterns. By including the internal via 341 in the ground pattern 421, the internal via 341 acts as a heat dissipation obstacle to reduce the heat dissipated radially toward the center of the substrate 30, compared to a design that does not include the via 341 in the ground pattern 421. In the present embodiment, the same advantageous effects as those achieved by the first embodiment can also be achieved by the configuration in the second embodiment.

[0086] (Third Embodiment)

[0087] Reference Fig.11 , Fig.12 and Fig.13 A third embodiment of the present disclosure is described. The substrate 50 in the present embodiment is a six-layer substrate (eg, a laminated substrate) having buildup layers.

[0088] Reference Fig.13 , one of the two main surfaces of the substrate 50 is a first surface 501, and the other main surface is a second surface 502. From the first surface 501 side, the substrate includes a first layer L21, a second layer L22, a third layer L23, a fourth layer L24, a fifth layer L25, and a sixth layer L26. The first circuit pattern 61 is included in the first layer L21, the second circuit pattern 62 is included in the second layer L22, the third circuit pattern 63 is included in the third layer L23, the fourth circuit pattern 64 is included in the fourth layer L24, the fifth circuit pattern 65 is included in the layer L25, and the sixth circuit pattern 66 is included in the sixth layer L26. An interlayer insulating layer 69 is formed between the circuit patterns 61, 62, 63, 64, 65, and 66 (i.e., 61 to 66). A surface resist layer 67 is formed on the first surface 501, and a surface resist layer 68 is formed on the second surface 502.

[0089] Reference Fig.11 , similar to the first embodiment, the circuit pattern 61 is near the first surface 501 side of the substrate 50. The description of this embodiment assumes that the first surface 501 is a soldering surface, that is, a surface on which a soldering operation is performed to solder a component to the substrate 50. The circuit pattern 61 is wide to extend across a larger area to better receive heat from soldering.

[0090] like Fig.11As shown, when viewed from the first surface 501 side, vias 351 and 352 are formed to surround the ground terminal connection portion 34. On the substrate 50, an inner via 351 is formed on the central side of the ground terminal connection portion 34 (i.e., the side oriented toward the center of the substrate 50), and an outer via 352 is formed on the peripheral side of the ground terminal connection portion 34. In the present embodiment, the vias 351 and 352 are concentrically arranged in two groups of ellipses around the ground terminal connection portion 34. The vias 351 and 352 in the present embodiment are laser vias, and as shown in FIG. Fig.13 As shown, the circuit pattern 61 of the first layer L21 is connected to the circuit pattern 62 of the second layer L22. The inside of the vias 351 and 352 is filled with a conductor such as copper. Filling the vias 351 and 352 with a conductive material allows the vias 351 and 352 to handle a larger current load than when only the through holes are set as vias. In order to distinguish the vias 351 and 352 from a plurality of other vias (e.g., vias 341 and 342), the vias 351 and 352 may be referred to as front side vias 351 and 352 because the vias 351 and 352 are provided on the side of the substrate 50 opposite to the rear side vias described in the later embodiments.

[0091] Fig.12 An internal via 351 is shown. Fig.12 As shown, since there is no hole in the via hole 351, the portion on which the via hole 351 is formed is covered with the surface resist layer 67, and the surface resist layer 67 has no opening at a position above the via hole 351. Therefore, except for the resist openings 37 and 38 formed at the outer edges of the terminal connection parts 33 and 34, the heat receiving area H is covered by the surface resist layer 67. In this way, the via holes 351 and 352 are configured to limit and / or eliminate the generation of foreign matter and defects such as solder balls.

[0092] like Fig.13 As shown, since the vias 351 and 352 as laser vias are filled with conductive materials (i.e., conductors) in the vias, more heat energy can be transferred to the inner layer. The vias 351 and 352 help to dissipate heat from the first surface 501 side to the second surface 502 side, similar to the vias 341 and 342 in the aforementioned embodiment. Similarly, the internal via 351 also acts as an obstacle to limit and / or prevent heat from spreading toward the center of the substrate 50. Therefore, the internal via 351 also plays the role of keeping heat around the connection portion 34 on the center side of the connection portion 34.

[0093] The circuit patterns 63, 64, 65, and 66 (i.e., 63 to 66) are formed smaller than the circuit patterns 61 and 62 in the peripheral side area of ​​the outer via hole 352. By making the circuit patterns 63 to 66 on the third layer L23 to the sixth layer L26 as small as possible on the peripheral side of the via hole 352, heat is restricted and / or prevented from escaping toward the periphery of the substrate 50. Therefore, heat can be better retained around the connection portion 34 on the center side of the connection portion 34.

[0094] The circuit patterns 62 to 66 of the layers other than the first layer L21 located on the center side of the inner via 351 toward the center of the substrate 50 include isolation portions 625, 635, 645, 655, and 665 to separate the corresponding circuit patterns extending toward the center of the substrate 50 from the circuit patterns connected to the ground terminal connection portion 34. Such isolation portions 625, 635, 645, 655, and 665 are formed on the center side of the inner via 351 (i.e., the isolation portions are disposed more toward the center of the substrate 50 than the front side inner via 351). The isolation portions 625, 635, 645, 655, and 665 limit and / or prevent heat from being dissipated toward the center of the substrate 30 to better retain heat around the connection portion 34.

[0095] The vias 351 and 352 connect the first circuit pattern 61 on the first layer L21 to the second circuit pattern 62 on the second layer L22, and the interior of each of the vias 351 and 352 is filled with a conductive material. The first surface 501 of the substrate 50 is covered with a surface resist layer 67. In this embodiment, the vias 351 and 352 are laser vias. In this way, when the substrate 50 is connected to the terminals 463 and 464 by a welding process, the generation of solder balls can be reduced and / or eliminated. Since the interior of the vias 351 and 352 is filled with a conductor, a high current can be used for the vias 351 and 352. This embodiment can also achieve the same beneficial effects as those achieved by the previous embodiment.

[0096] (Fourth Embodiment)

[0097] Reference Figures 14 to 17 Description of the Fourth Embodiment In the present embodiment, the circuit patterns 62 to 66 on the second layer L22 to the sixth layer L26 are mainly described. Fig.14 The substrate shown in FIG. 1 is similar to that of the third embodiment. Fig.13 The substrate 50 in the embodiment of the present invention. Fig.15 The circuit pattern 62 of the second layer L22 is shown, and Fig.16 The circuit pattern 63 of the third layer L23 is shown, wherein Fig.15 and Fig.16 2 and 3 show the circuit pattern around the ground terminal connection portion 34. Assume that the circuit pattern 61 of the first layer L21 is the same as the first layer L21 of the third embodiment, and refer to Fig.11 The circuit pattern 61 of the first layer L21 is described, and it is assumed that the circuit patterns 64 and 65 of the fourth and fifth layers L24 and L25 are respectively the same as the circuit pattern 63 of the third layer L23 .

[0098] As described previously in the second embodiment, when the inner via 351 and the inner circuit pattern 621 need to be connected on the center side of the second layer L22 for product performance, the isolation portion 625 cannot be formed as, for example, a ground pattern.

[0099] In this embodiment, if Fig.14 and Fig.15 As shown, the circuit pattern 62 of the second layer L22 includes an inner circuit pattern 621 in which the inner via hole 351 is formed and an outer circuit pattern 622 in which the outer via hole 352 is formed. Fig.15 As shown, the internal circuit pattern 621 includes a recess 627 having an opening on the periphery, and the external circuit pattern 622 is positioned in the recess 627. The through-hole pad 39 is used to connect the patterns 621 and 622. A separation groove 623 is formed between the internal pattern 621 and the external pattern 622, and the internal pattern 621 and the external pattern 622 are separated from each other by a certain gap distance except for the portion of the patterns 621 and 622 connected by the through-hole pad 39. By using such a configuration, heat dissipation from the external pattern 622 to the internal pattern 621 can be reduced and / or eliminated (i.e., suppressed). The external pattern 622 helps to transfer the heat received by the first layer L21 to the ground terminal connection portion 34.

[0100] like Fig.15 As shown, two extensions 621a of the inner circuit pattern 621 are formed to extend to the periphery of the substrate 50 on both sides of the outer pattern 622. The extension 621a is separated from the outer circuit pattern 622 by a separation gap 623. In the inner circuit pattern 621, intermediate layer vias 355 and 356 are formed to connect the circuit patterns 62 to 65 on the second layer L22 to the fifth layer L25. The intermediate layer vias 355 and 356 are separated from the vias 351 and 352 (e.g., the front side vias 351 and 352) connecting the first layer L21 and the second layer L22.

[0101] The intermediate layer via 355 is formed in a region on the central side of the inner via 351 (i.e., more toward the center of the substrate 59 than the inner via 351), and the intermediate layer via 356 is formed in a region of the extension 621a of the inner circuit pattern 621, and the intermediate layer via 356 is disposed adjacent to the separation gap 623 and relative to the outer circuit pattern 622 to face the outer circuit pattern 622. By arranging the intermediate layer vias 355 and 356 separately from the ground terminal 34 and the vias 351 and 352 connected to the ground terminal connection portion 34, heat can be transferred to the ground terminal connection portion 34 through the vias 351 and 352, while the intermediate layer vias 355 and 356 act as obstacles that limit and / or prevent heat from being dissipated to the circuit patterns 63 to 65 of the third layer L23 to the fifth layer L25.

[0102] like Fig.16 As shown in FIG. 1 , the circuit pattern 63 of the third layer L23 has a recess 637 (e.g., without the circuit pattern 63) surrounding the ground terminal connection portion 34, wherein a through-hole pad 39 is formed in the recess 637. The ground terminal connection portion 34 and the through-hole pad 39 are separated from the circuit pattern 63 by a certain gap length through the recess 637. In the circuit pattern 63, vias 351 and 352 are not formed, but intermediate layer vias 355 and 356 are formed. The circuit patterns 64 and 65 on the fourth layer L24 and the fifth layer L25, respectively, are configured the same as the circuit pattern 63.

[0103] Reference Fig.17 , on the sixth layer L26, the through-hole pad 39 formed in the ground terminal connection portion 34 is not connected to another pattern. Therefore, such an arrangement suppresses heat dissipation to other patterns.

[0104] In the present embodiment, the substrate 50 has intermediate layer vias 355 and 356 formed therein to penetrate the intermediate circuit patterns 62 to 65 on the intermediate inner layer. In this case, the intermediate inner layer is a layer including circuit patterns other than the first circuit pattern 61 and the sixth circuit pattern 66 (i.e., the last or nth circuit pattern). The intermediate inner layer may be a layer (e.g., L21 and L26) that is not adjacent to the first surface 501 and the second surface 502 in the substrate. Although the present embodiment has six layers, the intermediate layer vias 355 and 356 may be formed in any number of intermediate inner layers, as long as the substrate 50 has 4 or more layers. In the present embodiment, the circuit patterns 62 to 65 may be referred to as "intermediate circuit patterns". Therefore, the intermediate circuit pattern may be used to reduce and / or eliminate (i.e., suppress) heat dissipation from the ground terminal connection portion 34 to the circuit patterns 62 to 66.

[0105] The intermediate layer vias 355 and 356 are formed at different positions away from the positions of the vias 351 and 352. That is, the intermediate layer vias 355 and 356 are formed at positions deviated from the positions of the inner vias 351 and the outer vias 352 so that the inner vias 351 and the outer vias 352 do not overlap / overlap the intermediate layer vias 355 and 356. The intermediate layer via 355 is formed at a position closer to the center of the substrate 50 than the ground terminal connection portion 34 and the inner via 351. In this way, positioning the intermediate layer via 355 can better limit and / or prevent heat from being dissipated radially toward the circuit pattern around the center of the substrate 50.

[0106] The second circuit pattern 62 includes an outer pattern 622 connecting the outer via 352 and the ground terminal connection portion 34, and an inner pattern 621 extending toward the center of the substrate 50. The inner pattern 621 is formed to extend on both sides of the outer pattern 622. The intermediate layer via 356 in the inner pattern 621 is formed on both sides of the outer pattern 622 to face the outer pattern 622. By using such a configuration, the size of the inner pattern 621 can be maintained while limiting the heat dissipated from the outer pattern 622 to the inner pattern 621. The present embodiment can achieve the same advantageous effects as described in the aforementioned embodiment.

[0107] (Fifth Embodiment)

[0108] Reference Fig.18 A fifth embodiment is described. In this embodiment, an intermediate layer via 357 on the center side of the terminal connection portion 34 and an intermediate layer via 358 on the peripheral side of the terminal connection portion 34 are formed in the substrate 50. The intermediate layer via 357 is formed immediately below the inner front side via 351, and the intermediate layer via 358 is formed immediately below the outer front side via 352.

[0109] The substrate 50 further includes rear vias 361 and 362, which are formed to connect the circuit pattern 66 of the sixth layer L26 and the circuit pattern 65 of the fifth layer L25. The rear vias 361 and 362 are laser vias, and the interiors of the vias 361 and 362 are filled with a conductive material (i.e., a conductor) such as copper. The second surface 502 side of the vias 361 and 362 is covered with a surface resist layer 68. In this embodiment, as shown in FIG. Fig.18 As shown in FIG. 5 , the backside vias 361 and 362 are aligned with the frontside vias 351 and 352 and are disposed immediately below the middle layer vias 357 and 358. However, the backside vias 361 and 362 are not limited to such locations and may be located at other locations in the substrate 50.

[0110] In this embodiment, an intermediate layer via 357 is formed immediately below the inner front via 351 , and an intermediate layer via 358 is formed immediately below the outer front via 352 . Such a structure is more conducive to dissipating heat to the second surface 502 .

[0111] In the present embodiment, the substrate 50 has "n" layers, where n is an integer of 3 or greater. In contrast to the first layer, the nth layer may indicate the last layer in the layered substrate 50. In the present embodiment, the substrate 50 has, for example, 6 layers (i.e., n=6). Thus, in this example, the sixth layer may be referred to as the nth layer. The substrate 50 is provided with rear side vias 361 and 362, which connect the sixth circuit pattern 66 on the sixth layer L26 to the fifth circuit pattern 65 on the fifth layer L25, wherein the rear side vias 361 and 362 are filled with a conductive material. In this example, the sixth layer L26 is considered to be adjacent to the fifth layer L25, so that if the sixth layer is referred to as, for example, the nth layer, the adjacent layer of the nth layer will be the next adjacent layer in the layered substrate. When the rear side vias 361 and 362 are formed, n is an integer of 3 or greater. Such a configuration with the rear side vias 361 and 362 facilitates the generation of solder fillets during the soldering operation. This embodiment can achieve the same advantageous effects as described in the previous embodiment.

[0112] (Other embodiments)

[0113] The first and second embodiments describe a four-layer substrate with through holes, and the third to fifth embodiments describe a six-layer substrate with a build-up layer. However, the type and number of layers of the substrate are not limited to the examples in the above embodiments. For example, the number of layers can be three, five, seven or more. The type of substrate can also be different. The number and arrangement of through holes, front side vias, intermediate layer vias, and rear side vias can be appropriately set based on manufacturing and assembly considerations (for example, based on the degree or state of solder temperature rise), and internal vias can be omitted.

[0114] In the above-described embodiment, the power terminal and the ground terminal are inserted into the substrate from the surface opposite to the motor (i.e., the surface facing the cover), and welding is performed on the motor side surface. In other embodiments, a connector may be provided between the substrate and the motor, and the power terminal and the ground terminal may be inserted into the terminal connection portion from the motor side. In such a case, since welding is performed on the surface of the substrate facing the cover, the above-described embodiment may be applied in a similar manner, wherein it is assumed that the first surface described in the above embodiment will be the second surface of the present example. In this way, the teachings in the above-described embodiment may be adapted to accommodate a situation in which welding is performed on the surface of the substrate facing the cover.

[0115] In the above embodiment, the outermost terminals are power terminals and ground terminals. In other embodiments, the leads connecting the motor windings and the substrate can be considered as "outermost terminals", the motor wire connections can be considered as "terminal connections", and the vias can be set at positions close to the motor wire connections. Intermediate layer vias and rear surface vias can also be included in such embodiments. In the above embodiment, the terminal connection is formed into an oval / elliptical shape. In other embodiments, the terminal connection can have a shape other than an oval, such as a circular shape or a rectangular shape.

[0116] In the above-described embodiment, the motor is a three-phase brushless motor. In other embodiments, the motor is not limited to a three-phase brushless motor, and may be any motor. The motor unit is not limited to an electric motor, but may also be a generator, or may be an electric generator that functions as both a motor and a generator.

[0117] In the above-mentioned embodiments, the electronic control unit (ECU) is applied to the electric power steering device. In other embodiments, the ECU may be applied to devices other than the electric power steering device. As described above, the ECU of the present disclosure is not limited to the above-mentioned embodiments, and may be implemented in various forms without departing from the spirit and scope of the present disclosure.

Claims

1. An electronic control unit, comprising: A substrate (30, 50) having an electrical component mounted at the center thereof, the substrate comprising: A first surface (301, 501); a second surface (302, 502) disposed opposite to the first surface; a plurality of circuit patterns (41 to 44, 61 to 66) which are arranged in layers between the first surface and the second surface and are layered from a first layer to an nth layer, where n is an integer of 2 or more; a surface resist layer (47, 67) disposed on the first layer; a terminal connection portion (33, 34) arranged as a through hole penetrating the first surface (301, 501), extending through the substrate and penetrating the second surface (302, 502), the terminal connection portion being arranged at an outermost position in a peripheral region close to the periphery of the substrate; resist openings (37, 38) that expose the first circuit pattern of the first layer along the outer edge of the terminal connecting portion; and a plurality of vias (331, 332, 341, 342, 351, 352) disposed adjacent to the resist openings, and an outermost terminal (463, 464) in the terminal connection portion and connected to the substrate by a connecting member, wherein The first surface is a main surface of the substrate close to the first layer, and the second surface is another main surface of the substrate close to the nth layer, and wherein, The plurality of vias include a plurality of external vias (332, 342, 352) formed in a heat receiving region (H) and on a peripheral side of the substrate between the resist opening and a periphery of the substrate, the heat receiving region being configured to receive heat from the connecting member during a connection process when the outermost terminal (463, 464) is inserted into the terminal connecting portion and connected to the substrate by the connecting member, The plurality of vias further include a plurality of intermediate layer vias (355, 356, 357, 358) formed in an inner layer of the substrate (50), the inner layer of the substrate being disposed between the first layer and the nth layer, wherein n is an integer of 4 or greater, and each of the plurality of intermediate layer vias penetrates and extends through an intermediate circuit pattern (62 to 65) disposed on the inner layer.

2. The electronic control unit according to claim 1, wherein: The plurality of vias also include a plurality of internal vias (331, 341, 351) formed in the heat receiving area (H) and on the inner side of the substrate (30) between the resist opening and the center of the substrate, wherein the inner side of the substrate is opposite to the peripheral side with respect to the resist opening (37, 38).

3. The electronic control unit according to claim 2, wherein: The plurality of vias include a plurality of front vias (351, 352) connecting the first circuit pattern (61) of the first layer (L21) and the second circuit pattern (62) of the second layer (L22), wherein the interior of each of the front vias is filled with a conductive material, and wherein, The first surface (501) of the substrate (50) is covered with the surface resist layer (67).

4. The electronic control unit according to claim 3, wherein: The surface resist layer is formed such that the plurality of via holes and the resist openings do not form a continuous region and are separated from each other.

5. The electronic control unit according to claim 3, wherein: The intermediate layer via holes (355, 356) are formed at positions offset from the positions of the internal via holes (351) so that the inner front side via holes (351) do not overlap with the intermediate layer via holes (355, 356).

6. The electronic control unit according to claim 5, wherein: The intermediate layer via hole (355) is formed at a position closer to the center of the substrate (50) than the terminal connection portion (34) and the internal via hole (351).

7. The electronic control unit according to claim 5, wherein: The second circuit pattern (62) comprises: an external circuit pattern (622) configured to connect the external front side via (352) to the terminal connection portion (34); and an inner circuit pattern (621) extending inwardly toward the center of the substrate (50), wherein: A separation groove (623) is provided between the inner circuit pattern (621) and the outer circuit pattern (622) to separate the inner circuit pattern (621) from the outer circuit pattern (622), and wherein, The internal circuit pattern (621) includes two extension portions (621a) extending to the periphery of the substrate so that each of the extension portions extends on one side of the external circuit pattern (622), wherein each of the extension portions separates the separation groove (623) from one side of the external circuit pattern (622), and each of the extension portions includes a plurality of intermediate layer vias (356) formed therein, and the plurality of intermediate layer vias (356) are arranged to be adjacent to the separation groove (623) and opposite to the external circuit pattern (622).

8. The electronic control unit according to claim 4, wherein: The intermediate layer vias (357, 358) are formed immediately below the front side vias (351, 352).

9. The electronic control unit according to any one of claims 3 to 8, wherein: The plurality of vias include a plurality of rear side vias (361, 362) formed in the substrate (50), the plurality of rear side vias (361, 362) being used to connect the nth circuit pattern (66) of the nth layer (L26) to the circuit pattern (65) on the layer (L25) immediately adjacent to the nth layer, each of the plurality of rear side vias (361, 362) being filled with a conductive material.

10. The electronic control unit according to claim 1 or 2, wherein: The via holes (331, 332, 341, 342) are through holes that penetrate the first surface (301), extend through the substrate, and penetrate the second surface (302), and wherein, A surface resist layer (47) is formed at a position between the via holes (331, 332, 341, 342) and the resist openings (37, 38) on the first surface (301).

11. The electronic control unit according to claim 10, wherein: Each of the via holes is connected to the terminal connection portion (34) through an auxiliary pattern (422, 432) provided for each via hole.

12. The electronic control unit according to claim 10, wherein: The vias arranged on the central side of the terminal connection portion (34) are arranged in a grounding circuit pattern (421) extending from the terminal connection portion (34) toward the center of the substrate (30), and the vias arranged on the peripheral side of the terminal connection portion (34) are connected to the terminal connection portion (34) through an auxiliary pattern (422), and the auxiliary pattern (422) is arranged for each of the vias arranged on the peripheral side of the terminal connection portion.

13. The electronic control unit according to any one of claims 1 to 8, wherein: A circuit pattern formed on a central side of the terminal connection portion (33, 34) on a layer other than the first layer in the substrate (30) includes an isolating portion (425, 435, 445), the isolating portion (425, 435, 445) being configured to separate a circuit pattern connected to the terminal connection portion (33, 34) from a circuit pattern formed on a central side of the terminal connection portion (33, 34) extending toward the center of the substrate (30).

14. The electronic control unit according to any one of claims 1 to 8, wherein: The outermost terminals are: (i) a power terminal (463) configured to be connected to a power source, or (ii) A ground terminal (464) configured to be connected to ground.

15. An electric power steering device, comprising: An electronic control unit according to any one of claims 1 to 8.

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