circuit board unit

Abstract

circuit board unit (1), comprising: a circuit arrangement (10) comprising a circuit board (20) and a busbar (30) arranged on one side of the circuit board (20); and a housing (40) comprising a frame-like housing (42), a top cover (44) and a heat dissipation element (50), wherein the frame-like housing (42) forms a receiving space for receiving the circuit board (20), wherein the circuit arrangement (10) is inserted into the frame-like housing through a top opening of the frame-like housing (42), wherein the top cover (44) covers the top opening, wherein the heat dissipation element (50) serves as a bottom plate for closing a bottom opening of the frame-like housing (42), and the busbar (30) includes: a main section (32) to which the circuit board (20) is joined, and several facing sections (340) which are facing a surface of the frame-like housing (42), characterized by the fact that the facing sections (340) protrude from opposite sides of the main section (32), and the facing sections (340) and the frame-like housing (42) comprise a locking structure for engaging the facing sections (340) and the frame-like housing (42) with each other in order to hold the circuit arrangement (10) at a predetermined position in the frame-like housing (42).

Description

Technical field

[0001] The present invention relates to a circuit board unit. The present application claims priority from Japanese patent application No. 2016-114856, filed on June 8, 2016. The entire disclosure of the above application is incorporated herein by reference in its entirety. State of the art

[0002] Document JP 2010-166 691 A discloses a circuit board assembly (an electrical terminal box) in which a circuit arrangement is contained in a housing, wherein the circuit arrangement is fixed to the housing with screws in order to position the circuit arrangement relative to the housing and to hold the circuit arrangement and the housing in a predetermined position.

[0003] Document US 7,074,053 B2 discloses a printed circuit board (PCB) housed in an enclosure consisting of a frame and a heat-dissipating disc. The PCB is held to the frame by screws, and a cover over the PCB is temporarily secured to the frame by a latch and additionally by screws.

[0004] Document WO 2015 / 170578A1 discloses a printed circuit board to which several busbars are glued. The multiple busbars have connecting pieces that are bent into an L-shape to form terminals. Summary of the invention

[0005] A circuit board assembly according to the present disclosure is a circuit board assembly comprising: a circuit arrangement comprising a circuit board and a busbar arranged on one side of the circuit board; and a housing comprising a frame-like enclosure, a top cover, and a heat dissipation element, wherein the frame-like enclosure forms a receiving space for receiving the circuit board, wherein the circuit arrangement is inserted into the frame-like enclosure through a top opening of the frame-like enclosure, wherein the top cover covers the top opening, and wherein the heat dissipation element serves as a bottom plate for closing a bottom opening of the frame-like enclosure, and the busbar includes: a main section to which the circuit board is joined, and several facing sections that project from opposite sides of the main section and face a surface of the frame-like housing, and The facing sections and the frame-like housing comprise a locking structure for engaging the facing sections and the frame-like housing with each other to hold the circuit assembly in a predetermined position within the frame-like housing. Brief description of the drawings Fig. Figure 1 is a schematic perspective view showing a circuit board unit according to a first embodiment in a state in which a top cover has been removed. Fig. 2 is a cross-sectional view along (II)-(II) from Fig. 1, showing a state in which a protruding locking piece has been inserted into a through hole. Fig. Figure 3 is a cross-sectional view showing how the protruding locking piece engages with the through-hole in the circuit board unit according to the first embodiment. Fig. Figure 4 is a front view of the area surrounding a position where the protruding locking piece is arranged in the circuit board unit according to the first embodiment. Fig. Figure 5 is a schematic cross-sectional view showing a locking structure of a circuit board unit according to a second embodiment. Fig. Figure 6 is a schematic cross-sectional view showing a locking structure of a circuit board unit according to a third embodiment. Fig. Figure 7 is a schematic cross-sectional view showing a locking structure of a circuit board unit according to a fourth embodiment. Description of embodiments Technical task

[0006] For several years, there has been a desire to improve productivity in printed circuit board (PCB) assembly. A circuit assembly and its housing can be held in place with screws at a predetermined position. However, screwing them in requires positioning through-holes provided in both the circuit assembly and the housing, and then inserting screws into these holes. Consequently, screwing the assembly in multiple locations tends to be a complex task. It is assumed that simplifying the process of fixing the circuit assembly to the housing will improve PCB assembly productivity.

[0007] In view of this, one objective of the present disclosure is to provide a circuit board unit in which a circuit arrangement can be easily held in a predetermined position relative to a housing and which offers very good productivity. Beneficial effects of disclosure

[0008] According to the present disclosure, a circuit board unit can be provided in which a circuit arrangement can be easily held in a predetermined position relative to a housing and which offers very good productivity. Description of embodiments of the invention

[0009] First, embodiments of the present invention are listed and described below.

[0010] (1) A circuit board unit according to an embodiment of the present invention is a circuit board unit comprising: a circuit arrangement comprising a circuit board and a busbar arranged on one side of the circuit board; and a housing comprising a frame-like enclosure, a top cover, and a heat dissipation element, wherein the frame-like enclosure forms a receiving space for receiving the circuit board, wherein the circuit arrangement is inserted into the frame-like enclosure through a top opening of the frame-like enclosure, wherein the top cover covers the top opening, and wherein the heat dissipation element serves as a bottom plate for closing a bottom opening of the frame-like enclosure. the busbar includes: a main section with which the circuit board is assembled, and several facing sections that project from opposite sides of the main section and face a surface of the frame-like housing, and The facing sections and the frame-like housing comprise a locking structure for engaging the facing sections and the frame-like housing with each other to hold the circuit assembly in a predetermined position within the frame-like housing.

[0011] According to the design described above, the facing sections and the frame-like housing have a locking structure for engaging the facing sections and the frame-like housing with each other, so that the circuit assembly can be held in a predetermined position relative to the frame-like housing without using any element other than the circuit assembly and the frame-like housing (e.g., a screw). Furthermore, a step in fixing the circuit assembly and the frame-like housing (e.g., a step of fastening with screws) can be eliminated, since the circuit assembly and the frame-like housing can be engaged with each other simply by assembling the circuit assembly and the frame-like housing.Furthermore, the facing sections extend onto two opposite sides of the main section and engage with the frame-like housing, thus allowing the circuit assembly to be fixed evenly to the frame-like housing from both sides of the main section. As already described, the circuit assembly is easily held in the predetermined position relative to the frame-like housing according to the design described above, and productivity is very good. By locking the circuit assembly and the frame-like housing together, detachment of the circuit assembly from the frame-like housing, misalignment of the circuit assembly with respect to the frame-like housing, and so on, can be prevented without the need for any other element, even if the circuit assembly and frame-like housing assembly is turned upside down.

[0012] (2) In one embodiment of the circuit board unit described above, the locking structure may comprise the through holes formed in the facing sections and the projecting locking pieces which extend from the frame-like housing towards the facing section and engage with the through holes.

[0013] The fact that the locking structure includes the through holes provided in the facing sections and the protruding locking pieces provided on the frame-like housing simplifies holding the circuit assembly in the predetermined position relative to the frame-like housing.

[0014] (3) In one embodiment of the circuit board unit described above, the locking structure may include a projecting locking element extending from a surface of the frame-like housing along an outer circumferential side surface towards an outer surface of the facing section.

[0015] The protruding locking element serves as the locking structure on the frame-like housing along the outer circumferential side surfaces, extending towards the outer surface of the facing sections. Accordingly, no through-holes need to be provided in the facing sections, thus ensuring a more conductive region in the busbar compared to a housing where through-holes are provided in the facing sections.

[0016] (4) In one embodiment of the circuit board unit described above, the facing sections may each be provided with an upright section which stands upright on the main section and faces an inner surface of the frame-like housing, and the locking structure may be provided on the upright sections and the inner surface of the frame-like housing.

[0017] The locking mechanism is provided on the upright sections and the inner surface of the frame-like housing, so that when the circuit assembly is attached to the frame-like housing, the upright sections naturally fall along the inner surface of the frame-like housing under the force of gravity. Accordingly, the circuit assembly and the frame-like housing can be locked without exerting a significant load on the busbar. Description of embodiments

[0018] A circuit board assembly according to embodiments of the present invention is described below with reference to the drawings. Identical reference numerals in the drawings indicate parts with the same name. First embodiment circuit board unit

[0019] Below, a circuit board unit 1 of the first embodiment is described with reference to Fig. 1 to 4 described. As in Fig. As shown in Figure 1, the circuit board unit 1 comprises a circuit arrangement 10 and a housing 40, which forms a receiving space for the circuit arrangement 10. The circuit arrangement 10 is provided with a circuit board 20 and a busbar 30, which is superimposed on the circuit board 20. The housing 40 is formed from: a frame-like housing 42, an upper cover 44 for covering an upper opening of the frame-like housing 42, and a base plate (a heat dissipation element 50) for closing a lower opening of the frame-like housing 42. The busbar 30 comprises a main section 32 ( Fig. 2 and Fig. 3), with which the circuit board 20 is joined, and several extension sections 34 ( Fig. 1) projecting from opposite sides of the main section 32. The extension sections 34 each have an facing section 340, which faces a surface of the frame-like housing 42. A key feature of the circuit board unit 1 of the first embodiment is that the facing section 340 and the frame-like housing 42 have an interlocking structure for engaging with each other to hold the circuit arrangement 10 in a predetermined position within the frame-like housing 42. In this example, the facing section 340 comprises an upright section 344, which stands upright on the main section 32 and faces the inner surface 42m of the frame-like housing 42, and the interlocking structure comprises a through-hole 344h formed in the upright section 344 and a projecting locking element 420 provided on the frame-like housing 42. The training courses are described in detail below.It should be noted that in the description below, the side of the heat dissipation element 50 of the housing 40 of the circuit board unit 1 is referred to as the bottom side and the side of the top cover 44 is referred to as the top side. Circuit arrangement

[0020] The circuit arrangement 10 comprises a circuit board 20 and a power rail 30. As shown in Fig. As shown in Figures 1 to 3, the circuit board 20 is an approximately rectangular printed circuit board mounted on the busbar 30, which will be described later. It has a conductive pattern (not shown) formed on one side opposite the busbar 30. A conductor formed by the conductive pattern is a control trace (part of a circuit). A connector section 22 and electronic components (not shown), such as a switching element, are mounted on the circuit board 20. A connector section of an external control device or the like (not shown) is connected to the connector section 22. busbar

[0021] As in Fig. As shown in 1 to 3, the power rail 30 comprises a main section 32 ( Fig. 2 and Fig. 3), with which the circuit board 20 can be assembled, and extension sections 34 ( Fig. 1) which are formed integrally with the main section 32 and protrude from the main section 32. The circuit board 20 can be joined with the main section 32 of the busbar 30. Accordingly, the circuit board 20 and the busbar 30 can be handled as a single component.

[0022] The extension sections 34 of the busbar 30 are sections for the electrical connection of an external device, and the connection terminals (not shown) of a cable (cable harness) are electrically connected to the extension sections 34. Through holes 34h ( Fig. 1) For the passage of externally threaded screws 90, which will be described later, are formed in the extension sections 34. In this example, the extension sections 34 are provided on two opposite sides of the rectangular main section 32 of the busbar 30, and the connecting terminals of conductors are electrically connected to the extension sections 34. The extension sections 34 are displaceable in the longitudinal direction of the circuit board 20 (a direction that is orthogonal to both the direction in which the extension sections 34 are opposite each other and to the thickness direction of the main section 32) as long as the extension sections 34 are in a conductive state with respect to the externally threaded screws 90.

[0023] The extension section 34 of the busbar 30 is formed by a curved piece. In particular, the extension section 34 can comprise: a base end section 342 extending along the side of the main section 32, an upright section 344 standing erect on the base end section 342 (the main section 32), and a leading end section 346 curved relative to the upright section 344 and extending outward from the busbar 30. The base end section 342 is arranged on a heat dissipation element 50, which will be described later; the upright section 344 is arranged to face an inner surface 42m of a frame-like housing 42, which will be described later; and the leading end section 346 is arranged to face an upper surface 422u of the frame-like housing 42 (a base section 422).In this example, the upright section 344 and the leading end section 346, arranged to face the surface of the frame-like housing 42 (the inner surface 42m and the upper surface 422u), form the facing section 340. The leading end section 346 includes a through-hole 34h for passing the externally threaded screw 90 described above. The busbar 30 and the connecting terminal described above can be electrically connected by inserting the externally threaded screw 90 into the through-hole 34h formed in the leading end section 346, while simultaneously inserting the externally threaded screw 90 into the through-hole formed in the connecting terminal, and screwing a nut (not shown) onto the externally threaded screw 90.

[0024] The upright section 344 includes several through-holes 344h. The through-holes 344h extend through the busbar 30 in the thickness direction. A feature of the circuit board unit 1 of the first embodiment is that the through-holes 344h are components of the locking structure for holding the circuit arrangement 10 in a predetermined position in the frame-like housing 42. In the present example, the upright sections 344 each have two through-holes 344h. The through-holes 344h provided in the upright sections 344 will be described in detail in the description of the frame-like housing 42. Housing

[0025] The housing 40 comprises the frame-like housing 42, the top cover 44, and the heat dissipation element 50. The circuit arrangement 10 is accommodated in an inner space formed by assembling the frame-like housing 42, the top cover 44, and the heat dissipation element 50. Frame-like housing

[0026] As in Fig. As shown in Figure 1, the frame-like housing 42 is a rectangular frame that covers the entire outer circumference of the circuit arrangement 10 except for the leading end sections 346 of the busbar 30. The frame-like housing 42 includes base sections 422, which are the parts of the frame on which the leading end sections 346 of the busbar 30 are placed. As shown in Fig. As shown in Figure 1, the frame-like housing 42 is arranged relative to the circuit arrangement 10 such that the main section 32 and the base end section 342 of the busbar 30, on which the circuit board 20 is arranged, bridge the opposing frame sections within the frame-like housing 42, the upright sections 344 of the busbar 30 face the inner surface 42m of the frame-like housing 42, and the leading end sections 346 of the busbar 30 face the upper surface 422u of the base section 422 of the frame-like housing 42. The inner surface 42m of the frame-like housing 42 is provided with projecting locking pieces 420 that engage with the through holes 344h provided in the upright sections 344 on which the upright sections 344 of the busbar 30 are arranged.A feature of the circuit board unit 1 of the first embodiment is that the protruding locking pieces 420 are components of the locking structure for holding the circuit arrangement 10 at a predetermined position of the frame-like housing 42.

[0027] As in Fig. As shown in Figures 2 to 4, the protruding locking pieces 420 have a self-supporting support structure in which slots 420s ( Fig. 4) are formed in the frame-like housing 42 in such a way that the projecting locking pieces 420 can be elastically deformed. In particular, as shown in Fig. 2 and Fig. 3 shown, the protruding locking piece 420 is a plate-like piece in which one end (the upper side) is made of Fig. 2 and Fig. 3) a supporting end which is formed integrally with the base section 422 of the frame-like housing 42, and another end (the lower side made of Fig. 2 and Fig. 3) is an open, free end. On the side of the free end of the projecting locking element 420, a locking head section 420a is provided, which projects into the frame-like housing 42. The locking head section 420a comprises an inclined surface 420ax, where the amount of projection increases from the upper side to the lower side of the frame-like housing 42, and a locking surface 420ay, which is capable of engaging with the inner surface of the through-hole 344h below the inclined surface 422ax.

[0028] The circuit assembly 10 is inserted through the upper opening into the frame-like housing 42, with the main section 32 of the busbar 30, on which the circuit board 20 is arranged, facing downwards, and the circuit assembly 10 is inserted until the leading end section 346 of the busbar 30 abuts the upper surface 422u of the frame-like housing 42 (the base section 422) (see Fig. 2) When the circuit arrangement 10 is inserted into the frame-like housing 42, the inclined surface 420ax of the locking head section 420a abuts a surface of the upright section 344 of the busbar 30 and enters the through-hole 344h of the upright section 344. Since the locking section 420 is cantilevered, the locking section 420 is elastically deformed outwards from the frame-like housing 42 while the inclined surface 420ax abuts the surface of the upright section 344 (left side in Fig. 2 and Fig. 3), and when the locking head section 420a is fully inserted into the through hole 344h, the elastic deformation is returned to the state before the deformation.

[0029] In a state in which the leading end section 346 of the busbar 30 rests against the upper surface 422u of the frame-like housing 42, as in Fig. As shown in Figure 2, the locking surface 420ay of the locking head section 420a does not rest against the inner surface of the through hole 344h. However, as shown in Figure 2, the locking surface 420ay of the locking head section 420a does not rest against the inner surface of the through hole 344h. Fig. As shown in Figure 3, when the locking head section 420a is inserted into the through-hole 344h, the circuit assembly 10 is lifted from the frame-like housing 42, or the assembly consisting of the circuit assembly 10 and the frame-like housing 42 is turned upside down, the leading end section 346 of the busbar 30 moves away from the upper surface 422u of the frame-like housing 42. Since the locking surface 420ay of the locking head section 420a engages with the inner surface of the through-hole 344h, the circuit assembly 10 can be held in the predetermined position without detaching from the frame-like housing 42, regardless of whether the base plate (the heat dissipation element 50) is present. The circuit arrangement 10 and the frame-like housing 42 are temporarily fixed by the locking structure (the through hole 344h and the protruding locking piece 420).When the locking head section 420a, which is inserted into the through hole 344h, is pressed, the protruding locking piece 420 is elastically deformed and the locking state of the through hole 344h and the protruding locking piece 420 is released.

[0030] The shape and number of locking structures can be selected appropriately, as long as the circuit arrangement 10 and the frame-like housing 42 are held in the predetermined position. In this example, two locking structures are provided for each of the two upright sections 344 (see Fig. 1) However, one, three, or more elements of the locking structure can also be provided for each of the upright sections 344. It should be noted that if through-holes 344h are formed in the busbar 30, the position and size of the through-holes 344h are preferably chosen such that the conductive region is not affected by the through-holes 344h. In this example, the cross-section of the through-holes 344h is rectangular. However, the cross-section of the through-holes 344h can also have a non-rectangular polygonal or circular shape, as long as the through-hole 344h and the projecting locking element 420 can be engaged with each other.

[0031] Externally threaded screws 90 project upwards from the upper surfaces 422u of the base sections 422. Each externally threaded screw 90 comprises a shank and a head that is fixed to the base section 422. In this example, each base section 422 includes a recess into which the head of the externally threaded screw 90 can be inserted from one side, and a retaining section for securing the head in the recess. The busbar 30 and an external device can be electrically connected by inserting the shanks of the externally threaded screws 90 into through holes 34h formed in the leading end sections 346 of the busbar 30, placing the leading end sections 346 on the upper surfaces 422u of the base sections 422, and tightening the leading end sections 346 with connecting terminals (not shown) of a conductor using a nut.

[0032] The frame-like housing 42 comprises an insertion groove 424 for inserting the upper cover 44 onto the upper surface, excluding the base section 422, and an engagement section (engagement projection 426) for engaging with the upper cover 44. A side wall section 44b of the upper cover 44 is inserted into the insertion groove 424. The width of the insertion groove 424 can be selected to suit the thickness of the side wall section 44b of the upper cover 44, and the depth of the insertion groove 424 can be selected to suit the insertion depth of the side wall section 44b. The engagement projection 426 is provided at a suitable position in the circumferential direction of the frame-like housing 42 and, in a state where the side wall section 44b of the upper cover 44 is inserted into the insertion groove 424, fixes the upper cover 44 and the frame-like housing 42 integrally to one another. Heat dissipation element

[0033] The heat dissipation element 50 is an element for dissipating heat generated by the circuit arrangement 10, electronic components, and so on, to the outside. The heat dissipation element 50 serves as a base plate for closing the lower opening of the frame-like housing 42.

[0034] A stepped section (not shown) is formed on the inner edge on the side of the lower opening of the frame-like housing 42, and the heat dissipation element 50 is inserted into this stepped section. Through holes (not shown) for the passage of bolts (not shown), which are integrally joined with the frame-like housing 42, are formed in the heat dissipation element 50. Bolt holes for securing bolts, which are integrally joined with the heat dissipation element 50, are formed in the stepped section of the frame-like housing 42. The heat dissipation element 50 and the frame-like housing 42 can be integrally joined by inserting the heat dissipation element 50 into the stepped section of the frame-like housing 42, positioning the through holes of the heat dissipation element 50 relative to the bolt holes of the frame-like housing 42, and screwing in the bolts. Top cover

[0035] As in Fig. As shown in Figure 1, the upper cover 44 is a single part consisting of a plate-shaped ceiling section 44a, which covers the upper opening of the frame-like housing 42 and forms the upper surface of the housing 40, and an approximately rectangular side wall section 44b, which projects upright from the edge of the ceiling section 44a at a low height. The upper cover 44 can be fixed to the frame-like housing 42 and integrally joined with it by inserting the side wall section 44b into the insertion groove 424 of the frame-like housing 42 and engaging the engagement projections 426 of the frame-like housing 42 with engagement holes 446 provided in the side wall section 44b.

[0036] The upper cover 44 has a shape that covers the upper side of the frame-like housing 42, while the base sections 422 of the frame-like housing 42 remain exposed, and includes recessed sections 44c in parts of the outer wall. The recessed sections 44c provide spaces through which the leading end sections 346 of the busbar 30 can be guided, even when the upper cover 44 is fixed to the frame-like housing 42. These spaces allow the leading sections 346 of the busbar 30 to be mounted onto the upper surfaces 422u of the base sections 422.

[0037] The side wall section 44b of the upper cover 44 includes an upper recess 448, the frame-like housing 42 includes a lower recess 428 at a position corresponding to the upper recess 448, and a connector section 22 is arranged in the opening formed by the upper recess 448 and the lower recess 428. Effects

[0038] The circuit board unit 1 described above is provided with a locking structure in which the upright sections 344 include through holes 344h and the inner surfaces 42m of the frame-like housing 42 include the projecting locking elements 420. Accordingly, the circuit assembly 10 and the frame-like housing 42 can be easily locked together simply by attaching the circuit assembly 10 to the frame-like housing 42. Furthermore, the upright sections 344 extend to two opposite sides of the main section 32 and engage with the frame-like housing 42, thus enabling the circuit assembly 10 to be fixed evenly to the frame-like housing 42 on the two opposite sides of the main section 32.In particular, the protruding locking pieces 420 are elastically deformable and have a self-supporting support structure, and thus the protruding locking pieces 420 can be inserted into the through holes 344h without exerting a heavy load on the busbar 30 when the circuit arrangement 10 is attached to the frame-like housing 42.

[0039] Since the circuit assembly 10 and the frame-like housing 42 can be locked together simply by attaching the circuit assembly 10 to the frame-like housing 42, no additional process is required to fix the circuit assembly 10 to the frame-like housing 42, resulting in excellent machinability. Furthermore, no other element (e.g., a screw) is needed besides the circuit assembly 10 and the frame-like housing 42, thus reducing the number of components. Second embodiment

[0040] In a second embodiment, as in Fig. Figure 5 shows an aspect in which the locking structure comprises through holes 346h formed in the leading end section 346 of the busbar 30 and protruding locking pieces 420 provided on the upper surface 442u of the frame-like housing 42 (the base section 422). Fig. Figure 5 is a schematic cross-sectional view showing a state in which the projecting locking elements 420 engage with the through holes 346h, as seen from inside or outside the frame-like housing 42. The second embodiment differs from the first embodiment in that the locking structure is provided on the leading end sections 346 of the busbar 30 and the upper surfaces 442u of the frame-like housing 42 (the base section 422), and the remaining design is similar to the first embodiment.

[0041] The through-holes 346h are provided in the leading end sections 346 of the busbar 30 to hold the circuit assembly 10 in the predetermined position in the frame-like housing 42. In this example, each of the leading end sections 346 has two through-holes 346h. The projecting locking elements 420, which engage with the through-holes 346h in the leading end section 346, are provided in the upper surface 422u of the base section 422 of the frame-like housing 42. Similar to the first embodiment, the projecting locking elements 420 each have a locking head section 420a that projects outwards.The locking head section 420a comprises an inclined surface 420ax that rests against the edge of the through-hole 346h when it is inserted into the through-hole 346h, and a locking surface 420ay that comes into contact with the surface of the leading end section 346 when the locking head section 420a is fully inserted into the through-hole 346h. The projecting locking piece 420 is formed from segmented projecting pieces 420d obtained by dividing the locking head section 420a into several (here two) pieces in the circumferential direction.When the split protruding pieces 420d are assembled, a slot is formed in the middle along the direction in which the protruding locking piece 420 projects, so that when the locking head section 420a is inserted into the through-hole 346h, the split protruding pieces 420d move closer together and the diameter of the locking head section 420a is reduced. When the split protruding pieces 420d are in their natural state without reduction of their diameter, the maximum diameter of the locking head section 420a is larger than the inner diameter of the through-hole 346h.

[0042] In this example, two split protruding pieces 420d are present. However, three or more protruding pieces 420d may be provided. Furthermore, in this example, the split protruding pieces 420d form a slot that extends in the direction of projection over the entire length of the protruding locking piece 420. However, only the leading end of the protruding locking piece 420 (the part that serves as the locking head section 420a) may also be split.

[0043] When the circuit assembly 10 is inserted into the frame-like housing 42, the locking head section 420a enters the through-hole 346h, with the inclined surface 420ax coming into contact with the edge of the through-hole 346h. The split protruding pieces 420a then enter the through-hole 346h and move closer together, thus reducing their diameter. When the locking head section 420a is fully inserted into the through-hole 346h, the split protruding pieces 420d return to their original state before the reduction in diameter, and the locking surface 420ay engages with the edge portion of the through-hole 346h.If, for example, the assembly consisting of circuit arrangement 10 and frame-like housing 42 is turned upside down, the circuit arrangement 10 does not detach from the frame-like housing 42, since the locking surface 420ay is in contact with the edge part of the through-hole 346h, and thus both the circuit arrangement 10 and the frame-like housing 42 can be held in the predetermined position. Third embodiment

[0044] In the third embodiment, as in Fig. Figure 6 shows an aspect in which the locking structure comprises projecting locking pieces 420 extending from the surface of the frame-like housing 42 (of the base section 422) along the outer circumferential side surfaces of the leading end section 346 towards the side of the outer surface of the leading end section 346 of the busbar 30. Fig. Figure 6 is a schematic cross-sectional view showing a state in which the surface edge sections of the leading end section 346 are engaged with the projecting locking elements 420, as seen from inside or outside the frame-like housing 42. The third embodiment differs from the second embodiment in that the locking structure is provided in the surface edge sections of the leading end section 346 of the busbar 30, and the remaining design is similar to the second (first) embodiment.

[0045] On the upper surface 422u of the base section 422 of the frame-like housing 42, a pair of projecting locking elements 420 are provided, projecting upwards. The pair of projecting locking elements 420 are located at opposite positions in the direction that intersects the direction in which the extension sections 34 of the leading end section 346 of the busbar 30 project. Each pair of projecting locking elements 420 is provided with locking head sections 420a, which project towards each other.The locking head section 420a comprises an inclined surface 420ax that comes into contact with the edge section of the leading end section 346 of the busbar 30 when the leading end section 346 is mounted on the upper surface 422u of the base section 422, and a locking surface 420ay that comes into contact with the surface edge section of the busbar 30 when the leading end section 346 is held between the pair of protruding locking pieces 420. Fourth embodiment

[0046] In the fourth embodiment, as in Fig. Figure 7 shows an aspect in which the locking structure comprises projecting locking pieces 420 that extend downwards from the edge section of the leading end section 346 of the busbar 30, and recessed sections 422b that are formed in side walls of the frame-like housing 42 (of the base section 422) in a direction that intersects the direction in which the extension section 34 extends. Fig.Figure 7 is a schematic cross-sectional view showing a state in which the projecting locking elements 420 engage with the recessed sections 422b, as seen from inside or outside the frame-like housing 42. The fourth embodiment differs from the second embodiment in that the locking structure comprises projecting locking elements extending downwards from the side edge sections of the leading end section 346 of the busbar 30 and recessed sections 422b formed in the base section 422, and the remaining design is similar to the second (first) embodiment. List of reference numbers 1 circuit board unit 10 Circuit arrangement 20 circuit boards 22 Connector section 30 busbar 32 Main Section 34 Extension section 34h through hole 340 Facing Section 342 Base end section 344 Upright section 346 Top Section 344h, 346h through hole 40 cases 42 Frame-like housing 42m² internal surface 420 protruding locking piece 420d Split protruding piece 420a Locking head section 420ax Inclined Surface 420ay locking surface 420s slot 422 Basic section 422u Upper surface 422b Spare section 422 Insertion groove 426 Intervention advantage 428 Lower recess 44 Top cover 44a Ceiling section 44b Side wall section 44c Exclusion section 446 Access hole 448 Upper recess 50 Heat emission element 90° external thread screw

Claims

[1] Circuit board assembly (1) comprising: a circuit arrangement (10) comprising a circuit board (20) and a busbar (30) arranged on one side of the circuit board (20); and a housing (40) comprising a frame-like housing (42), a top cover (44) and a heat dissipation element (50), wherein the frame-like housing (42) forms a receiving space for receiving the circuit board (20), wherein the circuit arrangement (10) is inserted into the frame-like housing through a top opening of the frame-like housing (42), wherein the top cover (44) covers the top opening, and wherein the heat dissipation element (50) serves as a bottom plate for closing a lower opening of the frame-like housing (42), and the busbar (30) includes: a main section (32) to which the circuit board (20) is joined, and several facing sections (340) which are facing a surface of the frame-like housing (42), characterized by , that the facing sections (340) protrude from opposite sides of the main section (32), and the facing sections (340) and the frame-like housing (42) comprise a locking structure for engaging the facing sections (340) and the frame-like housing (42) with each other in order to hold the circuit arrangement (10) at a predetermined position in the frame-like housing (42). [2] Circuit board unit (1) according to claim 1, wherein the locking structure comprises: Through holes (344h) formed in the facing sections (340); and protruding locking pieces (420) which extend from the frame-like housing (42) to the side of the facing section (340) and engage with the through holes (344h). [3] Circuit board unit (1) according to claim 1, wherein the locking structure comprises a projecting locking element (420) extending from a surface of the frame-like housing (42) along an outer circumferential side surface towards an outer surface of the facing section (340). [4] Circuit board unit (1) according to any one of claims 1 to 3, wherein the facing sections (340) each comprise an upright section (344) which stands upright on the main section (32) and faces an inner surface of the frame-like housing (42), and the locking structure is provided on the upright section (344) and the inner surface of the frame-like housing (42). [5] Circuit board unit (1) according to one of claims 1 to 4, wherein a stepped part is formed on an inner edge on the side of the lower opening of the frame-like housing (42), and the heat dissipation element (50) is inserted into the stepped part.

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