Printed circuit device and power conversion device

Abstract

This printed circuit device (1) comprises a metal plate (10), a printed circuit board (20), a first solder joint (41), and a second solder joint (42). At least one through-hole (27, 28) is provided in the printed circuit board (20). At least a portion of the at least one through hole is inside a belt-like region (37) connecting the first solder joint (41) and the second solder joint (42). The length of at least a portion of the at least one through hole is at least 50% of a first width of the first solder joint (41) or at least 50% of a second width of the second solder joint (42).

Description

Printed circuit devices and power conversion devices

[0001] The present disclosure relates to printed circuit devices and power conversion devices.

[0002] Japanese Patent Laid-Open Publication No. 9-331123 (Patent Document 1) discloses a metal-based multilayer wiring board comprising a metal base, an upper surface insulating layer provided on the upper surface of the metal base, a lower surface insulating layer provided on the lower surface of the metal base, and a double-sided circuit board provided on the upper surface insulating layer.

[0003] Japanese Patent Application Publication No. 9-331123

[0004] An object of the present disclosure is to provide printed circuit devices and power conversion devices that have higher reliability.

[0005] The printed circuit device of the present disclosure includes a metal plate, a printed circuit board, a first solder joint, and a second solder joint. The printed circuit board includes a first main surface facing the metal plate and a second main surface opposite the first main surface. The first solder joint and the second solder joint join the printed circuit board to the metal plate. The printed circuit board is provided with at least one through hole extending from the first main surface to the second main surface. In a plan view of the second main surface, at least a portion of the at least one through hole is located within a strip-shaped region connecting the first solder joint and the second solder joint. The length of at least a portion of the at least one through hole in a second direction perpendicular to the first direction in which the first solder joint and the second solder joint are spaced apart from each other is 50% or more of a first width of the first solder joint in the second direction, or 50% or more of a second width of the second solder joint in the second direction.

[0006] The power conversion device of the present disclosure includes the printed circuit device of the present disclosure.

[0007] The printed circuit devices and power conversion devices of the present disclosure have higher reliability.

[0008] 1 is a schematic plan view of a printed circuit device of embodiment 1. FIG. 1 is a schematic cross-sectional view of the printed circuit device of embodiment 1 taken along the cross-sectional line II-II shown in FIG. 1 . FIG. 2 is a schematic cross-sectional view showing one step of a manufacturing method for the printed circuit device of embodiment 1. FIG. 3 is a schematic partially enlarged cross-sectional view showing a step subsequent to the step shown in FIG. 3 in the manufacturing method for the printed circuit device of embodiment 1. FIG. 4 is a schematic partially enlarged cross-sectional view showing a step subsequent to the step shown in FIG. 5 in the manufacturing method for the printed circuit device of embodiment 1. FIG. 5 is a schematic cross-sectional view of a printed circuit device of a comparative example. FIG. 6 is a schematic partially enlarged plan view of the printed circuit device of embodiment 1. FIG. 7 is a schematic plan view of a printed circuit device of a first modified example of embodiment 1. FIG. 8 is a schematic plan view of a printed circuit device of a second modified example of embodiment 1. FIG. 9 is a schematic cross-sectional view of the printed circuit device of embodiment 2 taken along the cross-sectional line XII-XII shown in FIG. 11 . FIG. 10 is a schematic plan view of a printed circuit device of a first modified example of embodiment 2. FIG. 11 is a schematic plan view of a printed circuit device of a second modified example of embodiment 2. FIG. 12 is a schematic plan view of a printed circuit device of embodiment 3. 15 is a schematic cross-sectional view of a printed circuit device of a third embodiment taken along the cross-sectional line XVI-XVI shown in FIG. 15. FIG. 16 is a schematic plan view of a printed circuit device of a fourth embodiment. FIG. 17 is a schematic cross-sectional view of a printed circuit device of a fourth embodiment taken along the cross-sectional line XVIII-XVIII shown in FIG. 17. FIG. 18 is a schematic plan view of a printed circuit device of a fifth embodiment. FIG. 19 is a schematic cross-sectional view of a printed circuit device of a fifth embodiment taken along the cross-sectional line XX-XX shown in FIG. 19. FIG. 19 is a schematic plan view of a printed circuit device of a modified example of the fifth embodiment. FIG. 21 is a schematic cross-sectional view of a printed circuit device of a modified example of the fifth embodiment taken along the cross-sectional line XXII-XXII shown in FIG. 21. FIG. 26 is a schematic plan view of a printed circuit device of a sixth embodiment. FIG. 23 is a schematic cross-sectional view of a printed circuit device of a sixth embodiment taken along the cross-sectional line XXIV-XXIV shown in FIG. 23. FIG. 27 is a schematic plan view of a printed circuit device of a first modified example of the sixth embodiment. FIG. 28 is a schematic cross-sectional view of a printed circuit device of a first modified example of the sixth embodiment taken along the cross-sectional line XXVI-XXVI shown in FIG. 25.27 is a schematic plan view of a printed circuit device according to a second modified example of the sixth embodiment. 28 is a schematic cross-sectional view of a printed circuit device according to a second modified example of the sixth embodiment, taken along the cross-sectional line XXVIII-XXVIII shown in FIG. 27. 29 is a schematic plan view of a printed circuit device according to a seventh embodiment. 30 is a schematic cross-sectional view of a printed circuit device according to the seventh embodiment and a modified example thereof, taken along the cross-sectional line XXX-XXX shown in FIG. 29. 31 is a schematic cross-sectional view of a printed circuit device according to the seventh embodiment and a modified example thereof, taken along the cross-sectional line XXXI-XXXI shown in FIG. 29. 32 is a schematic plan view of a printed circuit device according to a modified example of the seventh embodiment. 33 is a schematic cross-sectional view of a printed circuit device according to an eighth embodiment, taken along the cross-sectional line XXXIV-XXXIV shown in FIG. 33. 34 is a schematic plan view of a printed circuit device according to a modified example of the eighth embodiment. 35 is a schematic cross-sectional view of a printed circuit device according to a modified example of the eighth embodiment, taken along the cross-sectional line XXXVI-XXXVI shown in FIG. 35. 36 is a schematic plan view of a printed circuit device according to a ninth embodiment. 37 is a schematic cross-sectional view of the printed circuit device of embodiment 9. FIG. 38 is a schematic cross-sectional view showing one step of a manufacturing method for the printed circuit device of embodiment 9. FIG. 39 is a schematic cross-sectional view of a printed circuit device of a modified example of embodiment 9. FIG. 40 is a schematic view of a power conversion device of embodiment 10.

[0009] Hereinafter, embodiments of the present disclosure will be described. Note that the same reference numerals are used to designate the same components, and the description thereof will not be repeated.

[0010] 1 to 4, a printed circuit device 1 according to a first embodiment will be described. The printed circuit device 1 includes a metal plate 10, a printed circuit board 20, a first solder joint 41, a second solder joint 42, and electronic components 45, 45b, 46, and 46b.

[0011] The metal plate 10 includes a metal layer 11, an insulating layer 12, and a circuit pattern layer 13. The metal layer 11 is formed of, for example, steel, stainless steel, aluminum, an aluminum alloy, copper, brass, a copper alloy, magnesium, or a magnesium alloy. The thermal conductivity of the metal layer 11 is greater than the thermal conductivity of the insulating resin layer 21 of the printed circuit board 20.

[0012] The insulating layer 12 is disposed on the metal layer 11. The insulating layer 12 is disposed between the metal layer 11 and the circuit pattern layer 13. The insulating layer 12 electrically insulates the circuit pattern layer 13 from the metal layer 11. The insulating layer 12 is formed, for example, from a prepreg. The prepreg is formed by impregnating a fibrous substrate such as glass cloth with a thermosetting resin. The insulating layer 12 may be formed from ceramic, an insulating resin, or the like.

[0013] The circuit pattern layer 13 is disposed on the insulating layer 12. The circuit pattern layer 13 is a metal foil made of, for example, copper, a copper alloy, aluminum, an aluminum alloy, etc. The circuit pattern layer 13 is adhered to the insulating layer 12, for example.

[0014] The printed circuit board 20 includes an insulating resin layer 21 , conductive pattern layers 22 and 23 , and solder resist layers 24 and 25 .

[0015] The insulating resin layer 21 is formed of, for example, glass fiber, paper fiber, or glass nonwoven fabric impregnated with epoxy resin, phenolic resin, polyimide resin, bismaleimide triazine resin, or the like. The insulating resin layer 21 includes a back surface 21a facing the metal plate 10 and a front surface 21b opposite the back surface 21a. The back surface 21a and the front surface 21b each extend in a first direction (x-direction) and a second direction (y-direction) perpendicular to the first direction.

[0016] The conductor pattern layers 22, 23 are, for example, copper foil such as electrolytic copper foil or rolled copper foil. The conductor pattern layers 22, 23 are, for example, adhered to the insulating resin layer 21. The conductor pattern layers 22, 23 are arranged on both sides of the insulating resin layer 21. Specifically, the conductor pattern layer 22 is arranged on the back surface 21a of the insulating resin layer 21. The conductor pattern layer 23 is arranged on the front surface 21b of the insulating resin layer 21. An additional conductor pattern layer (not shown) may be arranged inside the insulating resin layer 21.

[0017] The solder resist layers 24 and 25 are insulating layers. The solder resist layer 24 covers a portion of the back surface 21a of the insulating resin layer 21 that is exposed from the conductor pattern layer 22 and a portion of the conductor pattern layer 22. The solder resist layer 25 covers a portion of the front surface 21b of the insulating resin layer 21 that is exposed from the conductor pattern layer 23 and a portion of the conductor pattern layer 23.

[0018] The printed circuit board 20 includes a first main surface 30 facing the metal plate 10, a second main surface 31 opposite the first main surface 30, a first side surface 32, a second side surface 33 opposite the first side surface 32, a first end surface 34, and a second end surface 35 opposite the first end surface 34.

[0019] The first main surface 30 and the second main surface 31 extend in a first direction (x direction) and a second direction (y direction). The first main surface 30 and the second main surface 31 are both end surfaces of the printed circuit board 20 in the thickness direction of the printed circuit board 20. The thickness direction of the printed circuit board 20 is a third direction (z direction) perpendicular to the first direction and the second direction. The printed circuit board 20 has a thickness t. The thickness t is the distance between the first main surface 30 and the second main surface 31. The longitudinal direction of each of the first main surface 30 and the second main surface 31 is, for example, the first direction. The lateral direction of each of the first main surface 30 and the second main surface 31 is, for example, the second direction.

[0020] The first side surface 32 and the second side surface 33 are connected to the first main surface 30 and the second main surface 31, respectively. The first side surface 32 and the second side surface 33 extend along the first direction (x direction) and the third direction (z direction), respectively. The first side surface 32 and the second side surface 33 are both end surfaces of the printed circuit board 20 in the second direction (y direction).

[0021] The first end surface 34 and the second end surface 35 are connected to the first main surface 30, the second main surface 31, the first side surface 32, and the second side surface 33, respectively. The first end surface 34 and the second end surface 35 extend along the second direction (y direction) and the third direction (z direction), respectively. The first end surface 34 and the second end surface 35 are both end surfaces of the printed circuit board 20 in the first direction (x direction).

[0022] The first solder joint 41 and the second solder joint 42 join the printed circuit board 20 to the metal plate 10. For example, the first solder joint 41 and the second solder joint 42 join the circuit pattern layer 13 of the metal plate 10 and the conductor pattern layer 22 of the printed circuit board 20 to each other. For example, Sn, Sn-0.7Cu, Sn-37Pb, Sn-3.0Ag-0.5Cu, Sn-0.7Cu-Ni, or Sn-58Bi (all composition numbers represent weight percent) is used as the first solder joint 41 and the second solder joint 42. In a plan view of the second main surface 31, the first solder joint 41 and the second solder joint 42 are spaced apart from each other in the first direction (x direction).

[0023] The printed circuit board 20 is provided with at least one through hole extending from the first main surface 30 to the second main surface 31. In this embodiment, the at least one through hole includes a first through hole 27 and a second through hole 28.

[0024] In a plan view of the second main surface 31, at least one through hole (e.g., the first through hole 27 and the second through hole 28) has an elongated shape. In the present embodiment, at least one through hole is a slit having an elongated shape in the second direction (y direction). The longitudinal direction of at least one through hole is the second direction, and the lateral direction of at least one through hole is the first direction (x direction).

[0025] In a plan view of the second main surface 31, at least one through hole (e.g., the first through hole 27 and the second through hole 28) is located between the first solder joint 41 and the second solder joint 42. The first through hole 27 is closer to the first solder joint 41 than the second through hole 28. The second through hole 28 is closer to the second solder joint 42 than the first through hole 27. The at least one through hole is distant from the first side surface 32, the second side surface 33, the first end face 34, and the second end face 35.

[0026] In a plan view of the second main surface 31, at least a portion of at least one through hole (e.g., the first through hole 27 and the second through hole 28) is located within a strip-shaped region 37 that connects the first solder joint 41 and the second solder joint 42. For example, at least a portion of each of the first through hole 27 and the second through hole 28 is located within the strip-shaped region 37. In the present embodiment, the strip-shaped region 37 has an elongated shape extending in the first direction (x-direction). The longitudinal direction of the strip-shaped region 37 is the first direction, and the lateral direction of the strip-shaped region 37 is the second direction (y-direction).

[0027] The length of the portion of at least one through hole (for example, the first through hole 27 and the second through hole 28) located within the strip region 37 in the second direction (y direction) is １ or the width W of the second solder joint 42 in the second direction is 50% or more of ２ For example, the length of the portion of each of the first through-hole 27 and the second through-hole 28 located within the strip region 37 is 50% or more of the width W of the first solder joint 41. １ or the width W of the second solder joint 42 is 50% or more of ２ The width W of the first solder joint 41 is 50% or more. １ is the distance between both ends of the first solder joint 41 in the second direction. ２ is the distance between both ends of the second solder joint 42 in the second direction.

[0028] Specifically, the length of the portion of at least one through hole (e.g., the first through hole 27 and the second through hole 28) located within the strip region 37 in the second direction (y direction) is equal to or less than the width W of the first solder joint 41. １ and the width W of the second solder joint 42 is 50% or more of ２ For example, the length of the portion of each of the first through-hole 27 and the second through-hole 28 located within the strip-shaped region 37 may be 50% or more of the width W of the first solder joint 41. １ and the width W of the second solder joint 42 is 50% or more of ２ It may be 50% or more of the above.

[0029] The length of at least one through hole in the second direction (y direction) (for example, the length L of the first through hole 27) １ and the length L of the second through hole 28 ２ ) is the width W of the first solder joint 41 １ or the width W of the second solder joint 42 ２ For example, the length L of the first through hole 27 may be １ and the length L of the second through hole 28 ２ are the width W of the first solder joint 41, respectively. １ or the width W of the second solder joint 42 ２ It may be more than that.

[0030] Specifically, the length of at least one through hole in the second direction (y direction) (for example, the length L of the first through hole 27) １ and the length L of the second through hole 28 ２ ) is the width W of the first solder joint 41 １ or more, and the width W of the second solder joint 42 ２ For example, the length L of the first through hole 27 may be １ and the length L of the second through hole 28 ２ are the width W of the first solder joint 41, respectively. １ or more, and the width W of the second solder joint 42 ２ It may be more than that.

[0031] The width of at least one through hole in the first direction (x direction) (for example, the width w of the first through hole 27) １ and the width w of the second through hole 28 ２ ) is equal to or greater than half the thickness t of the printed circuit board 20.

[0032] The electronic components 45, 45b, 46, and 46b are, for example, passive electronic components such as resistors or capacitors, or active electronic components such as semiconductor switching elements. The electronic components 45 and 45b are soldered to the conductor pattern layer 22. The electronic components 46 and 46b are soldered to the conductor pattern layer 23. The melting point of the solder material constituting the first solder joints 41 and the second solder joints 42 may be lower than the melting point of the solder material used to solder the electronic components 45, 45b, 46, and 46b to the conductor pattern layers. This prevents the solder between the electronic components 45, 45b, 46, and 46b and the conductor pattern layers 22 and 23 from melting when the printed circuit board 20 is soldered to the metal plate 10.

[0033] In a plan view of the second main surface 31, the electronic components 45, 45b, 46, and 46b are arranged between the first through hole 27 and the second through hole 28. In a plan view of the second main surface 31, the electronic components 45, 45b, 46, and 46b are located within the strip-shaped region 37. In a plan view of the second main surface 31, the electronic components 45, 45b, 46, and 46b are arranged between the first solder joint 41 and the second solder joint 42. The first through hole 27 is arranged on the first solder joint 41 side relative to the electronic components 45, 45b, 46, and 46b. The second through hole 28 is arranged on the second solder joint 42 side relative to the electronic components 45, 45b, 46, and 46b.

[0034] An example of a method for manufacturing the printed circuit device 1 of this embodiment will be described with reference to FIGS.

[0035] 3, a printed circuit board 20 is prepared. Specifically, at least one through hole (e.g., a first through hole 27 and a second through hole 28) is formed by machining the insulating resin layer 21. Conductive pattern layers 22 and 23 are formed on the insulating resin layer 21 by plating and etching processes. The conductive pattern layers 22 and 23 are bonded to the insulating resin layer 21. Solder resist layers 24 and 25 are formed on the insulating resin layer 21 and the conductive pattern layers 22 and 23 by coating and patterning processes.

[0036] 4, electronic components 45 and 45b are soldered to the conductor pattern layer 22. Electronic components 46 and 46b are soldered to the conductor pattern layer 23.

[0037] 5, solder pastes 41p and 42p are applied onto metal plate 10. For example, solder pastes 41p and 42p are provided on circuit pattern layer 13 by printing using a mask or by applying using a dispenser.

[0038] Referring to FIG. 6 , the printed circuit board 20 is placed on the metal plate 10 via the solder pastes 41p and 42p. The solder pastes 41p and 42p contact the conductive pattern layer 22 of the printed circuit board 20. The laminate of the printed circuit board 20, the solder pastes 41p and 42p, and the metal plate 10 is placed in a heating furnace 50. The laminate is heated to a temperature higher than the melting points of the solder pastes 41p and 42p to melt the solder pastes 41p and 42p. The laminate is cooled to room temperature to solidify the molten solder pastes 41p and 42p. The solder pastes 41p and 42p become the first solder joints 41 and the second solder joints 42. The printed circuit board 20 is soldered to the metal plate 10 by the first solder joints 41 and the second solder joints 42. In this manner, the printed circuit device 1 is obtained.

[0039] The operation of the printed circuit device 1 of this embodiment will be described in comparison with a printed circuit device 1b of a comparative example.

[0040] 7 has a configuration similar to that of the printed circuit device 1 of the present embodiment, but the printed circuit device 1b of the comparative example does not have at least one through hole (e.g., the first through hole 27 and the second through hole 28). Therefore, when manufacturing the printed circuit device 1b, if the temperature of the laminate of the printed circuit board 20, the solder pastes 41p and 42p, and the metal plate 10 is lowered from a temperature higher than the melting points of the solder pastes 41p and 42p to room temperature, the printed circuit device 1b will warp significantly due to the difference in thermal expansion coefficient between the metal layer 11 of the metal plate 10 and the insulating resin layer 21 of the printed circuit board 20, as shown in FIG.

[0041] As a result, large mechanical stress is applied to the first solder joints 41 and the second solder joints 42. Cracks occur in the first solder joints 41 and the second solder joints 42, reducing the reliability of the first solder joints 41 and the second solder joints 42. Furthermore, when the warped printed circuit device 1b is pressed against a flat member (not shown) and fixed to the flat member, even greater mechanical stress is applied to the first solder joints 41 and the second solder joints 42. As a result, the reliability of the first solder joints 41 and the second solder joints 42 is further reduced. Cracks are likely to occur in the first solder joints 41 and the second solder joints 42 due to the temperature cycles applied to the printed circuit board 20 when the printed circuit device 1b is in use.

[0042] In contrast, the printed circuit device 1 of this embodiment shown in Figures 1 and 2 is provided with at least one through hole (e.g., first through hole 27 and second through hole 28). When the printed circuit device 1 warps due to the difference in thermal expansion coefficient between the metal layer 11 of the metal plate 10 and the insulating resin layer 21 of the printed circuit board 20, the at least one through hole deforms as shown in Figure 8. This reduces warping of the printed circuit device 1. This reduces mechanical stress applied to the first solder joints 41 and the second solder joints 42. This prevents cracks from occurring in the first solder joints 41 and the second solder joints 42 even when temperature cycles are applied to the printed circuit board 20 during use of the printed circuit device 1.

[0043] 9, in a first modification of the present embodiment, the circuit pattern layer 13 is composed of a plurality of circuit pattern portions 13a, 13b, and 13c. The longitudinal direction of each of the plurality of circuit pattern portions 13a, 13b, and 13c is a first direction (x direction). The plurality of circuit pattern portions 13a, 13b, and 13c are arranged at intervals in a second direction (y direction).

[0044] The first solder joint 41 is composed of a plurality of solder joint portions 41a, 41b, and 41c. The plurality of solder joint portions 41a, 41b, and 41c are arranged at intervals in the second direction (y direction). The solder joint portion 41a joins the circuit pattern portion 13a to the conductor pattern layer 22. The solder joint portion 41b joins the circuit pattern portion 13b to the conductor pattern layer 22. The solder joint portion 41c joins the circuit pattern portion 13c to the conductor pattern layer 22. The width W of the first solder joint 41 １ is the distance between both ends of the plurality of solder joint portions 41a, 41b, and 41c in the second direction (y direction).

[0045] The second solder joint 42 is composed of a plurality of solder joint portions 42a, 42b, and 42c. The plurality of solder joint portions 42a, 42b, and 42c are arranged at intervals in the second direction (y direction). The solder joint portion 42a joins the circuit pattern portion 13a to the conductor pattern layer 22. The solder joint portion 42b joins the circuit pattern portion 13b to the conductor pattern layer 22. The solder joint portion 42c joins the circuit pattern portion 13c to the conductor pattern layer 22. The width W of the second solder joint 42 ２ is the distance between both ends of the plurality of solder joint portions 42a, 42b, and 42c in the second direction (y direction).

[0046] In the second modification of the present embodiment, in a plan view of the second main surface 31, the first solder joint 41 is not limited to a rectangular shape as shown in Fig. 1, but may be a circular shape as shown in Fig. 10. The second solder joint 42 is also not limited to a rectangular shape as shown in Fig. 1, but may be a circular shape.

[0047] The effects of the printed circuit device 1 of this embodiment will be described. The printed circuit device 1 of this embodiment includes a metal plate 10, a printed circuit board 20, a first solder joint 41, and a second solder joint 42. The printed circuit board 20 includes a first main surface 30 facing the metal plate 10 and a second main surface 31 opposite the first main surface 30. The first solder joint 41 and the second solder joint 42 join the printed circuit board 20 to the metal plate 10. The printed circuit board 20 has at least one through hole (e.g., a first through hole 27 and a second through hole 28) extending from the first main surface 30 to the second main surface 31. In a plan view of the second main surface 31, at least a portion of the at least one through hole is located within a strip-shaped region 37 connecting the first solder joint 41 and the second solder joint 42. The length of at least a portion of at least one through hole in a second direction (y direction) perpendicular to a first direction (x direction) in which the first solder joint and the second solder joint are spaced apart from each other is less than a first width (width W １ ) or the second width (width W ２ ) is more than 50%.

[0048] When the printed circuit device 1 warps due to the difference in thermal expansion coefficient between the metal plate 10 and the printed circuit board 20, at least one of the through holes (e.g., the first through hole 27 and the second through hole 28) is deformed. This reduces the warping of the printed circuit device 1 and the mechanical stress applied to the first solder joints 41 and the second solder joints 42. This results in higher reliability of the printed circuit device 1.

[0049] The printed circuit board 20 is fixed to the metal plate 10 not by thermally conductive grease but by the first solder joints 41 and the second solder joints 42. The thermal conductivity of the first solder joints 41 and the second solder joints 42 is greater than that of thermally conductive grease. This reduces the thermal resistance from the printed circuit board 20 to the metal plate 10. Heat generated from the electronic components 45, 45b, 46, and 46b is efficiently dissipated to the metal plate 10 through the first solder joints 41 and the second solder joints 42. This improves the heat dissipation of the printed circuit device 1. This improves the heat dissipation of the printed circuit device 1, allowing the electronic components 45, 45b, 46, and 46b to be arranged more densely. This allows the printed circuit device 1 to be made smaller.

[0050] In the printed circuit device 1 of this embodiment, the length of at least one through hole in the second direction (y direction) (for example, the length L of the first through hole 27) １ and the length L of the second through hole 28 ２ ) is the first width (width W １ ) or more, and the second width (width W ２ ) That's all.

[0051] Therefore, when the printed circuit device 1 warps, at least one of the through holes (e.g., the first through hole 27 and the second through hole 28) is easily deformed. This reduces warping of the printed circuit device 1. This reduces mechanical stress applied to the first solder joints 41 and the second solder joints 42. This results in higher reliability of the printed circuit device 1.

[0052] In the printed circuit device 1 of this embodiment, the width of at least one through hole in the first direction (x direction) (for example, the width w of the first through hole 27) １ and the width w of the second through hole 28 ２ ) is equal to or greater than half the thickness t of the printed circuit board 20.

[0053] Therefore, when the printed circuit device 1 warps, at least one of the through holes (e.g., the first through hole 27 and the second through hole 28) is easily deformed. This reduces warping of the printed circuit device 1. This reduces mechanical stress applied to the first solder joints 41 and the second solder joints 42. This results in higher reliability of the printed circuit device 1.

[0054] In the printed circuit device 1 of this embodiment, the at least one through hole includes a first through hole 27 and a second through hole 28. In a plan view of the second main surface 31, the first through hole 27 and the second through hole 28 are disposed between the first solder joint portion 41 and the second solder joint portion 42.

[0055] When there are two through holes, the through holes can be arranged closer to the first solder joints 41 and the second solder joints 42 than when there is one through hole, which reduces warping of the printed circuit device 1. The mechanical stress applied to the first solder joints 41 and the second solder joints 42 is reduced, which results in higher reliability of the printed circuit device 1.

[0056] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a first side surface 32 and a second side surface 33 opposite the first side surface 32. The first side surface 32 and the second side surface 33 are connected to the first main surface 30 and the second main surface 31, respectively, and extend along the first direction (x direction). The first through hole 27 and the second through hole 28 are arranged away from the first side surface 32 and the second side surface 33.

[0057] This reduces warping of the printed circuit device 1. This reduces mechanical stress applied to the first solder joints 41 and the second solder joints 42. The printed circuit device 1 has higher reliability.

[0058] Second Embodiment A printed circuit device 1 according to a second embodiment will be described with reference to Figures 11 and 12. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the first embodiment, but differs mainly in the following respects.

[0059] In the present embodiment, the first through hole 27 and the second through hole 28 extend to the first side surface 32 and are spaced apart from the second side surface 33. The first through hole 27 and the second through hole 28 may be arranged symmetrically with respect to the center line of the second main surface 31 in the first direction (x direction) in which the first solder joint 41 and the second solder joint 42 are spaced apart from each other.

[0060] 13 , in a first modification of the present embodiment, the first through hole 27 extends to the first side surface 32 and is spaced apart from the second side surface 33. The second through hole 28 extends to the second side surface 33 and is spaced apart from the first side surface 32. Therefore, when the printed circuit device 1 warps due to the difference between the thermal expansion coefficient of the metal layer 11 of the metal plate 10 and the thermal expansion coefficient of the insulating resin layer 21 of the printed circuit board 20, the first side surface 32 and the second side surface 33 are likely to deform. The first through hole 27 and the second through hole 28 may be arranged point-symmetrically with respect to the center of the second main surface 31.

[0061] 14 , in a second modification of the present embodiment, the at least one through hole includes a third through hole 27 b and a fourth through hole 28 b. The third through hole 27 b and the fourth through hole 28 b extend to the second side surface 33 and are spaced apart from the first side surface 32. The third through hole 27 b and the fourth through hole 28 b are each located within a strip-shaped region 37 connecting the first solder joint 41 and the second solder joint 42. The fact that the third through hole 27 b and the fourth through hole 28 b are each located within the strip-shaped region 37 means that at least a portion of each of the third through hole 27 b and the fourth through hole 28 b is located within the strip-shaped region 37. The third through hole 27 b and the fourth through hole 28 b are located between the first solder joint 41 and the second solder joint 42.

[0062] In a plan view of the second main surface 31, the first through hole 27 and the third through hole 27b are arranged closer to the first solder joint 41 than the second solder joint 42. In a plan view of the second main surface 31, the second through hole 28 and the fourth through hole 28b are arranged closer to the second solder joint 42 than the first solder joint 41. The combination of the first through hole 27 and the third through hole 27b and the combination of the second through hole 28 and the fourth through hole 28b may be arranged point-symmetrically with respect to each other with respect to the center of the second main surface 31.

[0063] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0064] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a first side surface 32 and a second side surface 33 opposite the first side surface 32. The first side surface 32 and the second side surface 33 are connected to the first main surface 30 and the second main surface 31, respectively, and extend along the first direction (x direction). The first through hole 27 and the second through hole 28 extend to the first side surface 32 and are spaced apart from the second side surface 33.

[0065] Therefore, the portion of the printed circuit board 20 between the first through hole 27 and the second through hole 28 is a cantilever plate, which is easily deformed when the printed circuit device 1 warps due to the difference in thermal expansion coefficient between the metal plate 10 and the printed circuit board 20. This further reduces the mechanical stress applied to the first solder joint 41 and the second solder joint 42. This improves the reliability of the printed circuit device 1.

[0066] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a first side surface 32 and a second side surface 33 opposite the first side surface 32. The first side surface 32 and the second side surface 33 are connected to the first main surface 30 and the second main surface 31, respectively, and extend along the first direction (x direction). The first through hole 27 extends to the first side surface 32 and is spaced apart from the second side surface 33. The second through hole 28 extends to the second side surface 33 and is spaced apart from the first side surface 32.

[0067] Therefore, when the printed circuit device 1 warps due to the difference in the thermal expansion coefficient between the metal plate 10 and the printed circuit board 20, both the first side surface 32 and the second side surface 33 can be deformed in the same manner. When the printed circuit device 1 warps due to the difference in the thermal expansion coefficient between the metal plate 10 and the printed circuit board 20, the printed circuit device 1 is prevented from deforming unevenly. The mechanical stress applied to the first solder joints 41 and the second solder joints 42 is further reduced. The reliability of the printed circuit device 1 can be improved.

[0068] In the printed circuit device 1 of the present embodiment, the at least one through hole includes a third through hole 27b and a fourth through hole 28b. The third through hole 27b and the fourth through hole 28b extend to the second side surface 33 and are spaced apart from the first side surface 32. In a plan view of the second main surface 31, the first through hole 27b and the third through hole 27b are positioned closer to the first solder joint 41 than the second solder joint 42. In a plan view of the second main surface 31, the second through hole 28b and the fourth through hole 28b are positioned closer to the second solder joint 42 than the first solder joint 41.

[0069] Therefore, the portion of the printed circuit board 20 between the first through hole 27 and the fourth through hole 28b can deform like a spring. When the printed circuit device 1 warps due to the difference in thermal expansion coefficient between the metal plate 10 and the printed circuit board 20, the printed circuit device 1 is prevented from deforming unevenly. The mechanical stress applied to the first solder joint 41 and the second solder joint 42 is further reduced. The reliability of the printed circuit device 1 can be improved.

[0070] Third Embodiment A printed circuit device 1 according to a third embodiment will be described with reference to Figures 15 and 16. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the first embodiment, but differs mainly in the following respects.

[0071] The printed circuit device 1 of the present embodiment includes electronic components 46 and 46b, similar to the printed circuit device 1 of the first embodiment, but does not include electronic components 45 and 45b. At least one through hole is the first through hole 27. In the first direction (x direction), the first solder joint 41 and the second solder joint 42 are disposed between the electronic components 46 and 46b. Therefore, the distance between the first solder joint 41 and the second solder joint 42 in the present embodiment is shorter than the distance between the first solder joint 41 and the second solder joint 42 in the first embodiment. In a plan view of the second main surface 31, the first solder joint 41 is located between the electronic component 46 and the first through hole 27. In a plan view of the second main surface 31, the second solder joint 42 is located between the electronic component 46b and the first through hole 27. The strip-shaped region 37 has an elongated shape in the second direction (y direction).

[0072] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0073] The printed circuit device 1 of this embodiment further includes a first electronic component (electronic component 46) joined to the printed circuit board 20, and a second electronic component (electronic component 46b) joined to the printed circuit board 20. The first solder joint 41 and the second solder joint 42 are disposed between the first electronic component and the second electronic component.

[0074] Therefore, the distance between the first solder joints 41 and the second solder joints 42 is reduced. When the printed circuit device 1 warps due to the difference between the thermal expansion coefficients of the metal plate 10 and the printed circuit board 20, warping of the printed circuit device 1 is reduced. Mechanical stress applied to the first solder joints 41 and the second solder joints 42 is reduced. The reliability of the printed circuit device 1 can be improved. In addition, the first solder joints 41 and the second solder joints 42 can be arranged near the first electronic component (electronic component 46) and the second electronic component (electronic component 46b). Heat generated from the first electronic component and the second electronic component is more efficiently dissipated to the metal plate 10 through the first solder joints 41 and the second solder joints 42. The heat dissipation performance of the printed circuit device 1 is improved.

[0075] Fourth Embodiment A printed circuit device 1 according to a fourth embodiment will be described with reference to Figures 17 and 18. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the first embodiment, but differs mainly in the following respects.

[0076] In the printed circuit device 1 of the present embodiment, the printed circuit board 20 includes metal films 52 and 53. The metal films 52 and 53 are, for example, copper-plated films. The metal film 52 is formed on the inner wall surface that defines the first through hole 27. The metal film 52 is formed, for example, on a portion of the inner wall surface that defines the first through hole 27 that is close to the first solder joint 41 in a plan view of the second main surface 31. The metal film 53 is formed on the inner wall surface that defines the second through hole 28. The metal film 53 is formed, for example, on a portion of the inner wall surface that defines the second through hole 28 that is close to the second solder joint 42 in a plan view of the second main surface 31. The metal films 52 and 53 extend from the first main surface 30 to the second main surface 31.

[0077] The first solder joint 41 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22, but also on the metal film 52. The first solder joint 41 can be seen through the first through hole 27. The second solder joint 42 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22, but also on the metal film 53. The second solder joint 42 can be seen through the second through hole 28.

[0078] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0079] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a metal film 52 formed on an inner wall surface that defines at least one through hole (e.g., the first through hole 27). The first solder joint 41 is also formed on the metal film 52.

[0080] Therefore, the state of the joint between the printed circuit board 20 and the metal plate 10 by the first solder joint 41 can be confirmed through at least one through hole (for example, the first through hole 27), thereby improving the productivity of the printed circuit device 1.

[0081] Fifth Embodiment A printed circuit device 1 according to a fifth embodiment will be described with reference to Figures 19 and 20. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the first embodiment, but differs mainly in the following respects.

[0082] In this embodiment, the first end surface 34 of the printed circuit board 20 is provided with at least one through recess 55 extending from the first main surface 30 to the second main surface 31. The at least one through recess 55 may be a plurality of through recesses 55. The second end surface 35 of the printed circuit board 20 is provided with at least one through recess 56 extending from the first main surface 30 to the second main surface 31. The at least one through recess 56 may be a plurality of through recesses 56.

[0083] The printed circuit board 20 includes metal films 57 and 58. The metal films 57 and 58 are, for example, copper-plated films. The metal films 57 and 58 extend from the first main surface 30 to the second main surface 31. The metal film 57 is formed on at least one through-hole 55. The first solder joint 41 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22 but also on the metal film 57. The first solder joint 41 is visible through the at least one through-hole 55. The metal film 58 is formed on at least one through-hole 56. The second solder joint 42 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22 but also on the metal film 58. The second solder joint 42 is visible through the at least one through-hole 56.

[0084] 21 and 22 , in a modified example of the present embodiment, the printed circuit board 20 includes protrusions 60, 61. The protrusion 60 protrudes in a first direction (x direction) from the first end face 34. The protrusion 61 protrudes in the first direction (x direction) from the second end face 35. At least one through recess 55 is provided in the protrusion 60. The at least one through recess 55 may be a plurality of through recesses 55. In a plan view of the second main surface 31, the plurality of through recesses 55 may be provided on a plurality of sides of the protrusion 60. At least one through recess 56 is provided in the protrusion 61. The at least one through recess 56 may be a plurality of through recesses 56. In a plan view of the second main surface 31, the plurality of through recesses 56 may be provided on a plurality of sides of the protrusion 61.

[0085] The metal film 57 is formed on at least one through recess 55. The first solder joint 41 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22, but also on the metal film 57. The first solder joint 41 can be seen through the at least one through recess 55. The metal film 58 is formed on at least one through recess 56. The second solder joint 42 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22, but also on the metal film 58. The second solder joint 42 can be seen through the at least one through recess 56.

[0086] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0087] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a first end surface 34 connected to the first main surface 30 and the second main surface 31, and a metal film 57. The first end surface 34 extends along the second direction (y direction). A through recess 55 extending from the first main surface 30 to the second main surface 31 is provided in the first end surface 34. The metal film 57 is formed on the through recess 55. The first solder joint 41 is also formed on the metal film 57.

[0088] Therefore, the state of the joint between the printed circuit board 20 and the metal plate 10 by the first solder joint 41 can be confirmed through the through recess 55. This improves the productivity of the printed circuit device 1. Furthermore, because the size of the first solder joint 41 increases, the length of the crack until the first solder joint 41 completely breaks increases. Therefore, the first solder joint 41 is less likely to break completely, and the reliability of the first solder joint 41 improves. The printed circuit device 1 has higher reliability.

[0089] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a first end surface 34 connected to the first main surface 30 and the second main surface 31, a protrusion 60 protruding from the first end surface 34, and a metal film 57. The first end surface 34 extends along a second direction (y direction) perpendicular to a first direction (x direction) in which the first solder joints 41 and the second solder joints 42 are spaced apart from each other. The protrusion 60 is provided with a through recess 55 extending from the first main surface 30 to the second main surface 31. The metal film 57 is formed on the through recess 55. The first solder joints 41 are also formed on the metal film 57.

[0090] Therefore, the state of the joint between the printed circuit board 20 and the metal plate 10 by the first solder joints 41 can be confirmed through the through recesses 55. This improves the productivity of the printed circuit device 1. Furthermore, because the through recesses 55 are provided in the protrusions 60, the number of through recesses 55 can be increased. The state of the joint between the printed circuit board 20 and the metal plate 10 by the first solder joints 41 can be confirmed with higher accuracy.

[0091] Sixth Embodiment A printed circuit device 1 according to a sixth embodiment will be described with reference to Figures 23 and 24. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the first embodiment, but differs mainly in the following respects.

[0092] In this embodiment, holes 63 and 64 are provided in the printed circuit board 20. The holes 63 and 64 extend from the first main surface 30 to the second main surface 31. In a plan view of the second main surface 31, the hole 63 overlaps with the first solder joint 41. The first solder joint 41 can be seen through the hole 63. Flux gas generated when soldering the printed circuit board 20 to the metal plate 10 is released from the first solder joint 41 through the hole 63. In a plan view of the second main surface 31, the hole 64 overlaps with the second solder joint 42. The second solder joint 42 can be seen through the hole 64. Flux gas generated when soldering the printed circuit board 20 to the metal plate 10 is released from the second solder joint 42 through the hole 64.

[0093] 25 and 26 , in a first modification of the present embodiment, the printed circuit board 20 includes metal films 57 and 58. The metal films 57 and 58 are, for example, copper-plated films. The metal films 57 and 58 extend from the first main surface 30 to the second main surface 31 and are through-hole conductors.

[0094] The metal film 57 is formed on the inner wall surface that defines the hole 63. The solder paste wets and rises on the metal film 57, and the first solder joint 41 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22 but also on the metal film 57. The first solder joint 41 may be formed on the entire metal film 57. The hole 63 may be filled with the metal film 57 and the first solder joint 41.

[0095] The metal film 58 is formed on the inner wall surface that defines the hole 64. The solder paste wets and rises on the metal film 58, and the second solder joint 42 is formed not only on the circuit pattern layer 13 and the conductor pattern layer 22 but also on the metal film 58. The second solder joint 42 may be formed on the entire metal film 58. The hole 64 may be filled with the metal film 58 and the second solder joint 42.

[0096] 27 and 28, the diameter D of the hole 63 of the second modification of this embodiment is １is larger than the diameter of the hole 63 in this embodiment and the first modification of this embodiment. The diameter D of the hole 64 in the second modification of this embodiment ２ is larger than the diameter of the hole 64 in this embodiment and the second modification of this embodiment. １ and diameter D ２ In the second modification of the present embodiment, the diameter D of the hole 63 is, for example, 1 mm or more. １ and the diameter D of the hole 64 ２ are each equal to or greater than the thickness t of the printed circuit board 20.

[0097] Diameter D of hole 63 １ Since the diameter D of the hole 64 is large, the solder paste only wets a part of the metal film 57, and the first solder joint 41 is formed only on a part of the metal film 57. A part of the hole 63 is not filled with the metal film 57 and the first solder joint 41. ２ , the solder paste wets only a portion of the metal film 58, and the second solder joint 42 is formed only on a portion of the metal film 58. A portion of the hole 64 is not filled with the metal film 58 and the second solder joint 42.

[0098] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0099] In the printed circuit device 1 of the present embodiment, a hole 63 is provided in the printed circuit board 20. The hole 63 extends from the first main surface 30 to the second main surface 31, and overlaps with the first solder joint 41 in a plan view of the second main surface 31.

[0100] Therefore, flux gas generated when soldering the printed circuit board 20 to the metal plate 10 is released from the first solder joint 41 through the holes 63. Voids in the first solder joint 41 can be reduced or eliminated. The reliability of the first solder joint 41 is improved. Furthermore, the thermal resistance of the first solder joint 41 is reduced. The heat dissipation performance of the printed circuit device 1 is improved.

[0101] In the printed circuit device 1 of this embodiment, the printed circuit board 20 includes a metal film 57 formed on the inner wall surface that defines the hole 63. The first solder joint 41 is also formed on the metal film 57.

[0102] Therefore, by checking the degree of coverage of the metal film 57 by the first solder joints 41 through the holes 63, it is possible to check the bonding state between the printed circuit board 20 and the metal plate 10 by the first solder joints 41. This improves the productivity of the printed circuit device 1.

[0103] In the printed circuit device 1 of this embodiment, the diameter D of the hole 63 is １ is equal to or greater than the thickness t of the printed circuit board 20.

[0104] Diameter D of hole 63 １ Since the hole 63 is large, the release of flux gas through the hole 63 is further promoted. Since a portion of the hole 63 is not filled by the metal film 57 and the first solder joint 41, the release of flux gas through the hole 63 is further promoted. The reliability of the first solder joint 41 is improved. The thermal resistance of the first solder joint 41 is reduced, improving the heat dissipation performance of the printed circuit device 1. Furthermore, by checking the degree of coverage of the metal film 57 by the first solder joint 41 through the hole 63, the bonding state between the printed circuit board 20 and the metal plate 10 by the first solder joint 41 can be confirmed. The productivity of the printed circuit device 1 is improved.

[0105] Seventh Embodiment A printed circuit device 1 according to a seventh embodiment will be described with reference to Figures 29 to 31. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the second embodiment, but differs mainly in the following respects.

[0106] The printed circuit device 1 of this embodiment further includes a third solder joint 43, a fourth solder joint 44, and electronic components 46c and 46d.

[0107] The third solder joint 43 and the fourth solder joint 44 join the printed circuit board 20 to the metal plate 10. For example, the third solder joint 43 and the fourth solder joint 44 join the circuit pattern layer 13 of the metal plate 10 and the conductor pattern layer 22 of the printed circuit board 20 to each other. The third solder joint 43 and the fourth solder joint 44 are formed of, for example, the same solder material as the first solder joint 41 and the second solder joint 42. In a plan view of the second main surface 31, the third solder joint 43 and the fourth solder joint 44 are spaced apart from each other in the first direction (x direction).

[0108] The third solder joint 43 is spaced apart in the second direction (y direction) from the first solder joint 41. The fourth solder joint 44 is spaced apart in the second direction from the second solder joint 42. In a plan view of the second main surface 31, the distance d between the first solder joint 41 and the second solder joint 42 is １ is the distance d between the first solder joint 41 and the third solder joint 43 ２ In a plan view of the second main surface 31, the distance d between the first solder joint 41 and the second solder joint 42 is greater than １ is greater than the distance between the second solder joint 42 and the fourth solder joint 44. In a plan view of the second main surface 31, the distance between the third solder joint 43 and the fourth solder joint 44 is greater than the distance d ２ In a plan view of the second main surface 31 , the distance between the third solder joint 43 and the fourth solder joint 44 is greater than the distance between the second solder joint 42 and the fourth solder joint 44 .

[0109] The at least one through hole includes a third through hole 27 b and a fourth through hole 28 b. In a plan view of the second main surface 31, the third through hole 27 b and the fourth through hole 28 b have an elongated shape. In the present embodiment, the third through hole 27 b and the fourth through hole 28 b are slits having an elongated shape in the second direction (y direction). The longitudinal direction of each of the third through hole 27 b and the fourth through hole 28 b is the second direction, and the lateral direction of each of the third through hole 27 b and the fourth through hole 28 b is the first direction (x direction).

[0110] The third through hole 27b and the fourth through hole 28b are located between the third solder joint 43 and the fourth solder joint 44. The third through hole 27b is closer to the third solder joint 43 than the fourth through hole 28b. The fourth through hole 28b is closer to the fourth solder joint 44 than the third through hole 27b. The third through hole 27b and the fourth through hole 28b extend to the second side surface 33 and are spaced apart from the first side surface 32.

[0111] At least a portion of each of the third through hole 27b and the fourth through hole 28b is located within a strip-shaped region 37b that connects the third solder joint 43 and the fourth solder joint 44. For example, at least a portion of each of the third through hole 27b and the fourth through hole 28b is located within the strip-shaped region 37b. The strip-shaped region 37b has an elongated shape extending in the first direction (x-direction). The longitudinal direction of the strip-shaped region 37b is the first direction, and the lateral direction of the strip-shaped region 37b is the second direction (y-direction).

[0112] The length in the second direction (y direction) of the portion of each of the third through holes 27b and the fourth through holes 28b located within the strip-shaped region 37 is 50% or more of the width of the third solder joint 43 in the second direction, or 50% or more of the width of the fourth solder joint 44 in the second direction. For example, the length in the second direction (y direction) of the portion of each of the third through holes 27b and the fourth through holes 28b located within the strip-shaped region 37 may be 50% or more of the width of the third solder joint 43 in the second direction and 50% or more of the width of the fourth solder joint 44 in the second direction. The width of the third solder joint 43 in the second direction is the distance between both ends of the third solder joint 43 in the second direction. The width of the fourth solder joint 44 in the second direction is the distance between both ends of the fourth solder joint 44 in the second direction.

[0113] The length of each of the third through hole 27b and the fourth through hole 28b in the second direction (y direction) may be equal to or greater than the width of the third solder joint 43 in the second direction, or may be equal to or greater than the width of the fourth solder joint 44 in the second direction. For example, the length of each of the third through hole 27b and the fourth through hole 28b in the second direction may be equal to or greater than the width of the third solder joint 43 in the second direction and equal to or greater than the width of the fourth solder joint 44 in the second direction.

[0114] The width of each of the third through hole 27 b and the fourth through hole 28 b in the first direction (x direction) is equal to or greater than half the thickness t of the printed circuit board 20 .

[0115] The combination of the first through hole 27 and the third through hole 27 b and the combination of the second through hole 28 and the fourth through hole 28 b may be arranged point-symmetrically with respect to each other with respect to the center of the second main surface 31. The combination of the first through hole 27 and the second through hole 28 and the combination of the third through hole 27 b and the fourth through hole 28 b may be arranged point-symmetrically with respect to each other with respect to the center of the second main surface 31.

[0116] No elongated through hole such as the first through hole 27 is disposed between the first solder joint portion 41 and the third solder joint portion 43. No elongated through hole such as the first through hole 27 is disposed between the second solder joint portion 42 and the fourth solder joint portion 44.

[0117] The electronic components 46c and 46d are, for example, passive electronic components such as resistors or capacitors, or active electronic components such as semiconductor switching elements. The electronic components 46c and 46d are soldered to the conductor pattern layer 23. In a plan view of the second main surface 31, the electronic components 46c and 46d are disposed between the third through hole 27b and the fourth through hole 28b. The third through hole 27b is disposed on the third solder joint 43 side relative to the electronic components 46c and 46d. The fourth through hole 28b is disposed on the fourth solder joint 44 side relative to the electronic components 46c and 46d.

[0118] 32 , in a modification of the present embodiment, at least one through hole (first through hole 27, second through hole 28, third through hole 27b, and fourth through hole 28b) is formed by a first slit 66 having an elongated shape in the second direction (y direction) and a second slit 67 connected to an end of the first slit 66. The second slit 67 has an elongated shape in the first direction (x direction). The length of the second slit 67 in the first direction (x direction) is greater than the width of the first slit 66 in the first direction. In the second direction (y direction), the second slit 67 of the first through hole 27 and the second slit 67 of the third through hole 27b are located between the first solder joint 41 and the third solder joint 43. In the second direction, the second slit 67 of the second through hole 28 and the second slit 67 of the fourth through hole 28b are located between the second solder joint 42 and the fourth solder joint 44.

[0119] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the second embodiment.

[0120] The printed circuit device 1 of this embodiment further includes third solder joints 43 that join the printed circuit board 20 to the metal plate 10. In a plan view of the second main surface 31, the third solder joints 43 are spaced apart in the second direction (y direction). In a plan view of the second main surface 31, a first distance (distance d １ ) is the second distance (distance d ２ ) is larger than

[0121] The first distance (distance d １ ) is the second distance (distance d ２), the warpage of the printed circuit device 1 is greater in the first direction (x direction) in which the first solder joints 41 and the second solder joints 42 are spaced apart than in the second direction (y direction) in which the first solder joints 41 and the third solder joints 43 are spaced apart. However, the large warpage of the printed circuit device 1 in the first direction is reduced by at least one through hole (e.g., the first through hole 27 and the second through hole 28). This improves the reliability of the first solder joints 41, the second solder joints 42, and the third solder joints 43. The printed circuit device 1 has higher reliability.

[0122] In the printed circuit device 1 of this embodiment, at least one through hole (e.g., the first through hole 27 and the second through hole 28) is formed by a first slit 66 having an elongated shape in the second direction (y direction) and a second slit 67 connected to an end of the first slit 66. The second slit 67 has an elongated shape in the first direction (x direction). The length of the second slit 67 in the first direction is greater than the width of the first slit 66 in the first direction. In the second direction, the second slit 67 is located between the first solder joint 41 and the third solder joint 43.

[0123] The first slits 66 reduce warping of the printed circuit device 1 in the first direction (x direction), and the second slits 67 reduce warping of the printed circuit device 1 in the second direction (y direction). This improves the reliability of the first solder joints 41, the second solder joints 42, and the third solder joints 43. The printed circuit device 1 has higher reliability.

[0124] Eighth Embodiment A printed circuit device 1 of an eighth embodiment will be described with reference to Figures 33 and 34. The printed circuit device 1 of this embodiment has a similar configuration to the printed circuit device 1 of the first embodiment, but differs from the printed circuit device 1 of the first embodiment mainly in the following points.

[0125] In this embodiment, the at least one through hole is a first through hole 27. The at least one through hole has an elongated shape in a first direction (x direction). The longitudinal direction of the at least one through hole is the first direction, and the lateral direction of the at least one through hole is the second direction (y direction). The at least one through hole is disposed away from the first side surface 32 and the second side surface 33.

[0126] The printed circuit device 1 of this embodiment includes an electronic component 47 instead of the electronic components 45, 45b, 46, and 46b (see FIGS. 1 and 2 ). The electronic component 47 is, for example, a passive electronic component such as a resistor or a capacitor, or an active electronic component such as a semiconductor switching element. The electronic component 47 is bonded to the metal plate 10. Specifically, the electronic component 47 is soldered to the circuit pattern layer 13. The electronic component 47 is disposed in at least one through hole (first through hole 27). In a plan view of the second main surface 31, the electronic component 47 is located between the first solder joint 41 and the second solder joint 42.

[0127] 35 and 36, in a modification of this embodiment, at least one through hole (first through hole 27) extends to first side surface 32 and is spaced apart from second side surface 33.

[0128] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0129] The printed circuit device 1 of this embodiment further includes an electronic component 47 bonded to the metal plate 10. The electronic component 47 is disposed in at least one through-hole (first through-hole 27).

[0130] This increases the degree of freedom in arranging the electronic components 47, and therefore increases the degree of freedom in designing the printed circuit device 1.

[0131] Ninth Embodiment A printed circuit device 1 according to a ninth embodiment will be described with reference to Figures 37 and 38. The printed circuit device 1 according to this embodiment has a similar configuration to the printed circuit device 1 according to the first embodiment, but differs mainly in the following respects.

[0132] In this embodiment, holes 15 and 16 are provided on the surface of the metal plate 10 facing the printed circuit board 20. The holes 15 and 16 may be through holes that penetrate the metal plate 10. The number of holes 15 and 16 is not limited to two, and may be one, or three or more. In a plan view of the second main surface 31, the holes 15 and 16 have an elongated shape. The holes 15 and 16 are slits that are elongated in the second direction (y direction). The longitudinal direction of each of the holes 15 and 16 is the second direction, and the lateral direction of each of the holes 15 and 16 is the first direction (x direction).

[0133] In a plan view of the second main surface 31, the holes 15 and 16 are distant from the circuit pattern layer 13. In a plan view of the second main surface 31, the holes 15 and 16 are located between the first solder joint 41 and the second solder joint 42. In a plan view of the second main surface 31, the hole 15 is closer to the first solder joint 41 than the hole 16. In a plan view of the second main surface 31, the hole 16 is closer to the second solder joint 42 than the hole 15.

[0134] In a plan view of the second main surface 31, at least a portion of the hole 15 or at least a portion of the hole 16 overlaps with the strip region 37. For example, the length in the second direction (y direction) of the portion of the hole 15 that overlaps with the strip region 37 in a plan view of the second main surface 31 is equal to or less than the width W of the first solder joint 41. １ or the length in the second direction (y direction) of the portion of the hole 16 that overlaps the strip region 37 in a plan view of the second main surface 31 is 50% or more of the width W of the second solder joint 42 ２ More than 50% of the total.

[0135] Specifically, in a plan view of the second main surface 31, at least a portion of the hole 15 and at least a portion of the hole 16 may overlap the strip region 37. For example, the length in the second direction (y direction) of the portion of the hole 15 that overlaps the strip region 37 in a plan view of the second main surface 31 is equal to or less than the width W of the first solder joint 41. １ and the length in the second direction (y direction) of the portion of the hole 16 that overlaps the strip region 37 in a plan view of the second main surface 31 is equal to or greater than the width W of the second solder joint 42. ２In a plan view of the second main surface 31, the holes 15 and 16 may entirely overlap the band-shaped region 37.

[0136] The length of each of the holes 15 and 16 in the second direction is equal to or less than the width W of the first solder joint 41. １ or the width W of the second solder joint 42 ２ Specifically, the length of each of the holes 15 and 16 in the second direction may be equal to or greater than the width W of the first solder joint 41. １ or more, and the width W of the second solder joint 42 ２ It may be more than that.

[0137] The width of each of the holes 15 and 16 in the first direction (x direction) is equal to or greater than half the thickness t of the printed circuit board 20 .

[0138] In a plan view of the second main surface 31, the hole 15 may overlap the first through hole 27. In a plan view of the second main surface 31, the hole 15 may surround the first through hole 27. In a plan view of the second main surface 31, the hole 16 may overlap the second through hole 28. In a plan view of the second main surface 31, the hole 16 may surround the second through hole 28. In a plan view of the second main surface 31, the shape of the hole 15 may be the same as the shape of the first through hole 27 or may be different from the shape of the first through hole 27. In a plan view of the second main surface 31, the shape of the hole 16 may be the same as the shape of the second through hole 28 or may be different from the shape of the second through hole 28. In a plan view of the second main surface 31, the holes 16, 16 may or may not overlap the printed circuit board 20.

[0139] In a plan view of the second main surface 31, the holes 15 and 16 may be arranged in line symmetry with each other about the center line of the second main surface 31 in the first direction (x direction) in which the first solder joints 41 and the second solder joints 42 are spaced apart from each other. In a plan view of the second main surface 31, the holes 15 and 16 may be arranged in point symmetry with each other about the center of the second main surface 31.

[0140] 39 , when the holes 15 and 16 overlap the first through hole 27 and the second through hole 28 in a plan view of the second main surface 31, the printed circuit board 20 may be aligned with the metal plate 10 using alignment jigs 70 and 71, and then solder-joined to the metal plate 10 using the first solder joints 41 and the second solder joints 42. The alignment jigs 70 and 71 have a rod shape. The alignment jigs 70 and 71 may have, for example, a tapered shape. The printed circuit board 20 is aligned with the metal plate 10 by passing the alignment jig 70 through the hole 15 and the first through hole 27 and the alignment jig 71 through the hole 16 and the second through hole 28.

[0141] As shown in FIG. 40, in a modification of this embodiment, the holes 15 and 16 may terminate in the metal layer 11.

[0142] The printed circuit device 1 of this embodiment has the following advantages in addition to the advantages of the printed circuit device 1 of the first embodiment.

[0143] In the printed circuit device 1 of the present embodiment, a hole (at least one of holes 15 and 16) is provided on the surface of the metal plate 10 facing the printed circuit board 20. In a plan view of the second main surface 31, at least a portion of the hole overlaps with the band-shaped region 37.

[0144] Therefore, when the printed circuit device 1 warps due to the difference in thermal expansion coefficient between the metal plate 10 and the printed circuit board 20, the hole in the metal plate 10 (at least one of the holes 15 and 16) is also deformed in addition to at least one through hole in the printed circuit board 20 (e.g., the first through hole 27 and the second through hole 28). This further reduces warping of the printed circuit device 1. This further reduces mechanical stress applied to the first solder joints 41 and the second solder joints 42. This further prevents cracks from occurring in the first solder joints 41 and the second solder joints 42 even when temperature cycles are applied to the printed circuit board 20 during use of the printed circuit device 1.

[0145] Tenth Embodiment In this embodiment, the printed circuit device 1 according to any one of the above-described first to ninth embodiments and their modified examples is applied to a power conversion device. Although the present disclosure is not limited to a specific power conversion device, the following describes, as the tenth embodiment, a case in which the printed circuit device 1 according to any one of the first to ninth embodiments and their modified examples is applied to a three-phase inverter.

[0146] The power conversion system shown in Fig. 41 is composed of a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power conversion device 200. The power supply 100 is not particularly limited, and may be composed of, for example, a DC system, a solar cell, or a storage battery, or may be composed of a rectifier circuit or an AC / DC converter connected to an AC system. The power supply 100 may be composed of a DC / DC converter that converts DC power output from the DC system into a predetermined power.

[0147] The power conversion device 200 is a three-phase inverter connected between the power supply 100 and the load 300, converts DC power supplied from the power supply 100 into AC power, and supplies the AC power to the load 300. The power conversion device 200 includes the printed circuit device 1 according to any one of the first to ninth embodiments and their modifications. Therefore, the power conversion device 200 of this embodiment has improved reliability.

[0148] The load 300 is a three-phase electric motor driven by AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, but is an electric motor mounted on various electrical devices, and is used as an electric motor for, for example, a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioning device.

[0149] The power conversion device to which the present disclosure is applied is not limited to cases where the load is an electric motor, and may be incorporated, for example, into a power supply device for an electric discharge machine or a laser processing machine, a compressor, or a power supply device for an induction heating cooker or a contactless power supply system. The power conversion device to which the present disclosure is applied may also be used as a power conditioner for a solar power generation system, a power storage system, or the like.

[0150] Various aspects of the present disclosure are summarized below as appendices. (Supplementary Note 1) A printed circuit device comprising: a metal plate; a printed circuit board including a first main surface facing the metal plate and a second main surface opposite the first main surface; a first solder joint joining the printed circuit board to the metal plate; and a second solder joint joining the printed circuit board to the metal plate; wherein the printed circuit board has at least one through hole extending from the first main surface to the second main surface; in a plan view of the second main surface, at least a portion of the at least one through hole is located within a band-shaped region connecting the first solder joint and the second solder joint; and a length of the at least a portion of the at least one through hole in a second direction perpendicular to a first direction in which the first solder joint and the second solder joint are spaced apart from each other is 50% or more of a first width of the first solder joint in the second direction, or is 50% or more of a second width of the second solder joint in the second direction. (Supplementary Note 2) The printed circuit device according to Supplementary Note 1, wherein a length of the at least one through hole in the second direction is equal to or greater than the first width of the first solder joint and equal to or greater than the second width of the second solder joint. (Supplementary Note 3) The printed circuit device according to Supplementary Note 1 or Supplementary Note 2, wherein a width of the at least one through hole in the first direction is equal to or greater than half the thickness of the printed circuit board. (Supplementary Note 4) The printed circuit device according to any of Supplementary Notes 1 to 3, wherein the at least one through hole includes a first through hole and a second through hole, and wherein the first through hole and the second through hole are arranged between the first solder joint and the second solder joint in the plan view of the second main surface. (Supplementary Note 5) The printed circuit board includes a first side and a second side opposite to the first side, the first side and the second side are connected to the first main surface and the second main surface, respectively, and extend along the first direction, and the first through hole and the second through hole are spaced apart from the first side and the second side.(Supplementary Note 6) The printed circuit device according to Supplementary Note 4, wherein the printed circuit board includes a first side surface and a second side surface opposite to the first side surface, the first side surface and the second side surface are connected to the first main surface and the second main surface, respectively, and extend along the first direction, the first through hole and the second through hole extend to the first side surface and are spaced apart from the second side surface. (Supplementary Note 7) The printed circuit device according to Supplementary Note 4, wherein the printed circuit board includes a first side surface and a second side surface opposite to the first side surface, the first side surface and the second side surface are connected to the first main surface and the second main surface, respectively, and extend along the first direction, the first through hole extends to the first side surface and is spaced apart from the second side surface, and the second through hole extends to the second side surface and is spaced apart from the first side surface. (Supplementary Note 8) The printed circuit device according to Supplementary Note 6, wherein the at least one through hole includes a third through hole and a fourth through hole, the third through hole and the fourth through hole extend to the second side surface and are spaced apart from the first side surface, the first through hole and the third through hole are arranged closer to the first solder joint than the second solder joint in the plan view of the second main surface, and the second through hole and the fourth through hole are arranged closer to the second solder joint than the first solder joint in the plan view of the second main surface. (Supplementary Note 9) The printed circuit device according to any of Supplementary Note 1 to Supplementary Note 3, further comprising: a first electronic component bonded to the printed circuit board; and a second electronic component bonded to the printed circuit board, wherein the first solder joint and the second solder joint are arranged between the first electronic component and the second electronic component. (Supplementary Note 10) The printed circuit device according to any one of Supplementary Notes 1 to 9, wherein the printed circuit board includes a metal film formed on an inner wall surface defining the at least one through hole, and the first solder joint portion is also formed on the metal film.(Supplementary Note 11) The printed circuit device according to any one of Supplementary Notes 1 to 8, wherein the printed circuit board includes a first end face connected to the first main surface and the second main surface, and a metal film, the first end face extending along the second direction, a through recess extending from the first main surface to the second main surface being provided in the first end face, the metal film being formed on the through recess, and the first solder joint being also formed on the metal film. (Supplementary Note 12) The printed circuit device according to any one of Supplementary Notes 1 to 8, wherein the printed circuit board includes a first end face connected to the first main surface and the second main surface, a protrusion protruding from the first end face, and a metal film, the first end face extending along the second direction, a through recess extending from the first main surface to the second main surface being provided in the protrusion, the metal film being formed on the through recess, and the first solder joint being also formed on the metal film. (Supplementary Note 13) The printed circuit device according to Supplementary Note 1 or Supplementary Note 2, wherein a hole is provided in the printed circuit board, the hole extending from the first main surface to the second main surface and overlapping the first solder joint portion in the plan view of the second main surface. (Supplementary Note 14) The printed circuit device according to Supplementary Note 13, wherein the printed circuit board includes a metal film formed on an inner wall surface that defines the hole, and the first solder joint portion is also formed on the metal film. (Supplementary Note 15) The printed circuit device according to Supplementary Note 13 or Supplementary Note 14, wherein a diameter of the hole is equal to or greater than a thickness of the printed circuit board. (Appendix 16) A printed circuit device described in any of Appendices 1 to 15, further comprising a third solder joint that joins the printed circuit board to the metal plate, wherein, in the planar view of the second main surface, the third solder joint is spaced apart in the second direction from the first solder joint, and, in the planar view of the second main surface, a first distance between the first solder joint and the second solder joint is greater than a second distance between the first solder joint and the third solder joint.(Supplementary Note 17) The printed circuit device according to Supplementary Note 16, wherein the at least one through hole is formed by a first slit having an elongated shape in the second direction and a second slit connected to an end of the first slit, the second slit having an elongated shape in the first direction, the length of the second slit in the first direction is greater than the width of the first slit in the first direction, and the second slit is located between the first solder joint and the third solder joint in the second direction. (Supplementary Note 18) The printed circuit device according to any of Supplementary Notes 1 to 3, further comprising an electronic component bonded to the metal plate, the electronic component being disposed in the at least one through hole. (Supplementary Note 19) The printed circuit device according to any of Supplementary Notes 1 to 18, wherein a hole is provided in a surface of the metal plate facing the printed circuit board, and at least a portion of the hole overlaps the strip-shaped region in the plan view of the second main surface. (Supplementary Note 20) A power conversion device comprising the printed circuit device according to any one of Supplementary Notes 1 to 19.

[0151] The disclosed embodiments 1 to 10 and their modifications should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0152] REFERENCE SIGNS LIST 1, 1b Printed circuit device, 10 Metal plate, 11 Metal layer, 12 Insulating layer, 13 Circuit pattern layer, 13a, 13b, 13c Circuit pattern portion, 15, 16 Hole, 20 Printed circuit board, 21 Insulating resin layer, 21a Back surface, 21b Front surface, 22, 23 Conductive pattern layer, 24, 25 Solder resist layer, 27 First through hole, 27b Third through hole, 28 Second through hole, 28b Fourth through hole, 30 First main surface, 31 Second main surface, 32 First side surface, 33 Second side surface, 34 First end surface, 35 Second end surface, 37, 37b Strip-shaped region, 41 First solder joint portion, 41p, 42p Solder paste, 41a, 41b, 41c Solder joint portion, 42 Second solder joint, 42a, 42b, 42c solder joint portion, 43 Third solder joint, 44 Fourth solder joint, 45, 45b, 46, 46b, 46c, 46d, 47 Electronic component, 50 Heating furnace, 52, 53, 57, 58 Metal film, 55, 56 Through recess, 60, 61 Protrusion, 63, 64 Hole, 66 First slit, 67 Second slit, 70, 71 Alignment jig, 100 Power source, 200 Power conversion device, 300 Load.

Claims

1. A printed circuit device comprising: a metal plate; a printed circuit board including a first main surface facing the metal plate and a second main surface opposite the first main surface; a first solder joint joining the printed circuit board to the metal plate; and a second solder joint joining the printed circuit board to the metal plate; wherein the printed circuit board has at least one through hole extending from the first main surface to the second main surface; in a plan view of the second main surface, at least a portion of the at least one through hole is located within a strip-shaped region connecting the first solder joint and the second solder joint; and the length of the at least a portion of the at least one through hole in a second direction perpendicular to a first direction in which the first solder joint and the second solder joint are spaced apart from each other is 50% or more of a first width of the first solder joint in the second direction, or is 50% or more of a second width of the second solder joint in the second direction.

2. The printed circuit device of claim 1, wherein the length of the at least one through hole in the second direction is equal to or greater than the first width of the first solder joint and equal to or greater than the second width of the second solder joint.

3. The printed circuit device according to claim 1, wherein the width of said at least one through hole in said first direction is equal to or greater than half the thickness of said printed circuit board.

4. The printed circuit device according to claim 1, wherein the at least one through hole includes a first through hole and a second through hole, and in the plan view of the second main surface, the first through hole and the second through hole are positioned between the first solder joint portion and the second solder joint portion.

5. The printed circuit device according to claim 4, wherein the printed circuit board includes a first side surface and a second side surface opposite the first side surface, the first side surface and the second side surface are connected to the first main surface and the second main surface, respectively, and extend along the first direction, and the first through hole and the second through hole are spaced apart from the first side surface and the second side surface.

6. The printed circuit device of claim 4, wherein the printed circuit board includes a first side and a second side opposite the first side, the first side and the second side are connected to the first main surface and the second main surface, respectively, and extend along the first direction, and the first through hole and the second through hole extend to the first side and are spaced apart from the second side.

7. The printed circuit device of claim 4, wherein the printed circuit board includes a first side and a second side opposite the first side, the first side and the second side being connected to the first main surface and the second main surface, respectively, and extending along the first direction, the first through hole extending to the first side and spaced apart from the second side, and the second through hole extending to the second side and spaced apart from the first side.

8. The printed circuit device of claim 6, wherein the at least one through hole includes a third through hole and a fourth through hole, the third through hole and the fourth through hole extend to the second side surface and are spaced apart from the first side surface, the first through hole and the third through hole are positioned closer to the first solder joint than the second solder joint in the planar view of the second main surface, and the second through hole and the fourth through hole are positioned closer to the second solder joint than the first solder joint in the planar view of the second main surface.

9. The printed circuit device of claim 1, further comprising: a first electronic component bonded to the printed circuit board; and a second electronic component bonded to the printed circuit board, wherein the first solder joint and the second solder joint are disposed between the first electronic component and the second electronic component.

10. The printed circuit device according to claim 1, wherein the printed circuit board includes a metal film formed on an inner wall surface defining the at least one through hole, and the first solder joint portion is also formed on the metal film.

11. The printed circuit device of claim 1, wherein the printed circuit board includes a first end face connected to the first main surface and the second main surface, and a metal film, the first end face extending along the second direction, the first end face having a through recess extending from the first main surface to the second main surface, the metal film being formed on the through recess, and the first solder joint also being formed on the metal film.

12. The printed circuit device of claim 1, wherein the printed circuit board includes a first end face connected to the first main surface and the second main surface, a protruding portion protruding from the first end face, and a metal film, the first end face extending along the second direction, the protruding portion having a through recess extending from the first main surface to the second main surface, the metal film being formed on the through recess, and the first solder joint also being formed on the metal film.

13. The printed circuit device according to claim 1, wherein a hole is provided in the printed circuit board, the hole extending from the first main surface to the second main surface and overlapping the first solder joint portion in the plan view of the second main surface.

14. The printed circuit device according to claim 13, wherein the printed circuit board includes a metal film formed on an inner wall surface that defines the hole, and the first solder joint is also formed on the metal film.

15. The printed circuit device of claim 13, wherein the diameter of the hole is equal to or greater than the thickness of the printed circuit board.

16. The printed circuit device of claim 1, further comprising a third solder joint that joins the printed circuit board to the metal plate, wherein, in the plan view of the second main surface, the third solder joint is spaced apart from the first solder joint in the second direction, and, in the plan view of the second main surface, a first distance between the first solder joint and the second solder joint is greater than a second distance between the first solder joint and the third solder joint.

17. The printed circuit device of claim 16, wherein the at least one through hole is formed by a first slit having an elongated shape in the second direction and a second slit connected to an end of the first slit, the second slit has an elongated shape in the first direction, the length of the second slit in the first direction is greater than the width of the first slit in the first direction, and the second slit is located between the first solder joint and the third solder joint in the second direction.

18. The printed circuit device of claim 1, further comprising an electronic component bonded to said metal plate, said electronic component being disposed within said at least one through hole.

19. The printed circuit device according to claim 1, wherein a hole is provided in the surface of the metal plate facing the printed circuit board, and at least a portion of the hole overlaps the band-shaped region in the plan view of the second main surface.

20. A power conversion device comprising the printed circuit device according to any one of claims 1 to 19.

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