Assembly of a printed circuit board and an electrically and / or thermally conductive component and method for manufacturing said assembly

Abstract

An assembly comprising a first printed circuit board (2) provided with first components interconnected by at least one conduction track, the first board (2) having one or more first connection zones accessible from at least one face (8), referred to as the connection face, of said first printed circuit board (2), said assembly further comprising at least one second electrically and / or thermally conductive component (4), said second component (4) being connected by laser welding to the first printed circuit board (2) at the location of the one or at least one of the first connection zones.

Description

Description Title of the invention: Assembly of a printed circuit board and an electrical and / or thermal conduction component and method for manufacturing said assembly

[0001] The invention relates to an assembly of a first printed circuit board and an electrical and / or thermal conduction component. It also relates to a method for manufacturing said assembly. It will find applications, particularly in the field of motor vehicles, and even more specifically in electrical and / or electronic devices used for their propulsion.

[0002] In this field, it is common practice to manufacture pre-assembled printed circuit boards, meaning boards already equipped with electrical and / or electronic components that allow the board to perform various functions. These are generally called PCBs, from the English acronym "Printed Circuit Board Assembly".

[0003] To connect them to external circuits or components, these pre-assembled printed circuit boards are fitted with electrical conduction bars which are added to the board at a later stage.

[0004] According to one technique, the electrical conduction bars are mechanically fixed to the board at pads using a screw. This technique has limitations in the face of the risks of vibration and / or thermal stress.

[0005] According to another technique, they are fixed to the board by brazing involving a specific part mounted on the board and their reliability may be questionable depending on the quality of the brazing.

[0006] Alternatively, power connectors are used. These also present risks in terms of vibrational stress. Furthermore, they can be subject to electrical arcing.

[0007] In each case, these techniques have the disadvantage of requiring one or more intermediate parts such as screws, studs and / or connectors.

[0008] The invention aims to overcome at least in part the previous drawbacks and proposes for this purpose an assembly comprising a first printed circuit board equipped with first components connected to each other by at least one conduction track, the first board having one or more first connection areas accessible from at least one face, called the connection face, of said first printed circuit board, said assembly further comprising at least one second electrical and / or thermal conduction component, said second component being connected by laser welding to the first printed circuit board at the level of the or at least one of the first connection areas.

[0009] Since the first connection area(s) are an integral part of the first printed circuit board, and the laser soldering occurs directly at these first connection areas, no intermediate component is needed to connect the second component to the first board, thus improving the reliability of the assembly. Furthermore, it should be noted that this soldering method can be performed on a board without damaging either the first components, pre-assembled on the board, or the second component, thanks to the highly localized energy release it generates.

[0010] According to various additional features of the invention, which may be taken together or separately and which constitute so many embodiments of the invention: - the aforementioned first connection zone(s) comprise a conductive pad in connection with said conduction track, - said pellet originates from said conduction track, - said pellet has a surface, called the contact surface, connected to said second component, - said second component includes one or more second connection areas at which said solder is positioned, - said solder is located between said contact surface and said second component, in particular said second connection area(s), - said second connection area(s) are substantially flat, - said second connection area(s) have a surface parallel to the contact surface of said pad(s), - said first printed circuit board includes a housing for said pad, - said contact surface is flush with said housing on the surface of said connection face of the first printed circuit board, - the said dwelling is windowless, - said dwelling is designed to allow said welding to be carried out through said dwelling. - said pellet has a surface, called the weld impact surface, opposite to the contact surface, - said housing has a shoulder for locking said pad, - said laser weld is located substantially at the center of said pad, - said second component comprises an electrical conduction busbar, - said second component comprises a second printed circuit board, - said second component comprises a heat dissipation plate, - said heat dissipation plate is configured to be a component of a power electronic enclosure, - said housing is intended to be assembled in a vehicle, - said second component includes a housing for the first card.

[0011] The invention also relates to a method of manufacturing an assembly as described above comprising a laser welding step of the second component to the first card at the level of the or at least one of the first connection areas, said first card being previously provided with said first component(s).

[0012] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent in the course of the detailed explanatory description which follows, of at least one embodiment of the invention given by way of purely illustrative and non-limiting example, with reference to the accompanying schematic drawings, among which:

[0013] [Fig.1] schematically illustrates in cross-section a first embodiment of an assembly according to the invention;

[0014] [Fig.2] schematically illustrates in cross-section a second embodiment of an assembly according to the invention;

[0015] [Fig.3] schematically illustrates in cross-section a third embodiment of an assembly according to the invention;

[0016] [Fig.4] schematically illustrates in cross-section a fourth embodiment of an assembly according to the invention.

[0017] As illustrated in the various figures, the invention relates to an assembly comprising a first printed circuit board 2.

[0018] According to the invention, said first card 2 is provided with first components connected to each other by one or more connection traces. It is thus a pre-assembled printed circuit board, or PCB A, according to the English acronym "Printed Circuit Board Assembly," that is to say, a card already equipped with electrical and / or electronic components and not a bare card equipped only with its printed circuits. In the figures, said first components and the connection trace(s) are not shown.

[0019] The first card 2 is formed, for example, of a board for holding and electrically connecting the first electronic components together. This board consists, in particular, of a thin layer or stack of thin layers of electrically conductive material, in particular copper, separated by an insulating material. The layer(s) of electrically conductive material are etched, in particular by a chemical process, to obtain the track(s) forming the printed circuit board in the board. For the purposes of this invention, the term "printed" in the expression "printed circuit board" should be taken in its broadest sense, regardless of the embodiment of said track(s).

[0020] The electrical components include, for example, resistors, capacitors, and / or inductors. The electronic components include, among other things, diodes, transistors, microcontrollers, and / or microprocessors. The first components are, for example, surface-mounted on the first board and / or connected by soldering, including wave soldering.

[0021] The assembly further comprises at least one second component 4, and the invention provides a solution for facilitating the electrical connection between the first board 2 and the second component 4. As will be understood later, the nature and / or function of the second component 4 varies, although it always remains an electrical and / or thermal conductive component. Moreover, the invention applies equally to an assembly comprising a single second component 4 connected to the first board 2, as shown in the drawings, and to several second components 4 connected to the same first board 2, even if this is not illustrated.

[0022] According to the invention, said first card 2 has one or more first connection areas accessible from at least one face 8, referred to as the connection face, of said first printed circuit board 2. This connection area(s) are integrated into said pre-assembled first card 2. Furthermore, said second component 4 is connected by laser welding to the first printed circuit board 2 at the level of the first connection area(s).

[0023] Since the laser welding takes place directly on the first connection area(s), the invention eliminates the need for an intermediate component to connect the first board 2 and the second component 4. Furthermore, when mounting the second component 4, this type of welding has the advantage of being able to be performed on the first board 2 without damaging either the first components pre-assembled on the board or the second component 4, thanks to the highly localized energy release involved. In the figures, the direction of a laser beam used during welding is indicated by an arrow labeled 10.

[0024] The first connection area(s) include, for example, a conductive pad 6 (or pad in Anglo-Saxon terminology) connected to the conduction track(s). In other words, the pad(s) 6 are electrically connected to the conduction track(s) of the first board 2.

[0025] The pad(s) 6 are, for example, made of the same electrically conductive material as the track(s), in particular copper. The pad(s) 6 are advantageously formed from the said conduction track(s). The laser weld is located, for example, substantially at the center of the pad(s) 6.

[0026] The pad(s) 6 have a surface 12, called the contact surface, connected to the second component 4. The pad(s) 6 have a thickness less than the thickness of the plate forming the first printed circuit board 2. The thickness of the pad(s) 6 is, for example, greater than or equal to that of the track to which they are connected.

[0027] The second component 4 comprises one or more second connection zones 14 at which the laser weld is positioned. The weld is located between the contact surface 12 and the second component 4, in particular the second connection zone(s) 14.

[0028] The second connection zone(s) 14 are, for example, substantially flat. They have a surface parallel to the contact surface 12 of the pad(s) 6.

[0029] Preferably, said first printed circuit board 2 includes a housing 16 for said pad(s) 6. Said contact surface 12 is flush with said housing 16 on the surface of said connection face 8 of the first printed circuit board 2.

[0030] In the embodiment shown in Figures 1 and 2, the housing 16 of the first card 2 is blind. The laser welding takes place on a face 18 of the second connection zone(s) 14 opposite the pad 6 of the first card 2.

[0031] In the embodiment of Figures 3 and 4, said housing 16 is through the plate forming said first printed circuit board 2 so as to allow soldering through said housing 16. Said pad 6 has a surface 20, called the solder impact surface, opposite its contact surface 12. Said housing 16 here has a shoulder 22 made in the plate forming said first printed circuit board 2 for locking said pad 6.

[0032] In [Fig.1], said second component 4 comprises an electrical conduction busbar 24.

[0033] In the illustrated embodiment, the busbar 24 has a first end 26 intended to be connected to another electrical and / or electronic component (not shown), possibly another printed circuit board, and a second, opposite end forming one or more of the second connection zones 14. The first end 26 extends beyond the plate forming the first printed circuit board 2. The busbar 24 has, for example, a substantially S-shaped form.

[0034] In [Fig.2], said second component 4 comprises a second printed circuit board 30.

[0035] The said second card 30 conforms to the invention as stated above. In the first card 2, the housing 16 is blind, whereas in the second card 30, said housing 16 is through-hole and the pad 6 of said second printed circuit board forms the second connection area 14 of the second component 4.

[0036] In [Fig. 3], it can be seen that said second component 4 is connected to two said first cards 2 according to the invention. In said first card(s) 2, said housing 16 is through-hole.

[0037] The second component 4 here includes a heat dissipation plate 32, in particular made of aluminum. The heat dissipation plate 32 includes, for example, one or more cooling channels 34, in particular for the circulation of a cooling fluid.

[0038] Preferably, the heat dissipation plate is a separate and independent component of the vehicle chassis. It is, for example, a component of a sub-assembly such as a power electronics unit, intended to be assembled in the vehicle.

[0039] According to a first variant, corresponding to the first card 2 located on the left in the drawing, the second connection area 14 of the second component 4 is formed by a pad 36. According to another variant, corresponding to the first card 2 located on the right in the drawing, the second connection area 14 of the second component 4 is formed directly by an external surface 38 of said dissipation plate 32.

[0040] In [Fig.4], said second component 4 includes a housing 40 for the first card 2. Said housing 40 allows thermal dissipation, in particular dissipation of the heat released by said first card 2. Indeed, the electrical connection established between said first card 2 and said housing 42 in accordance with the invention allows the creation of a thermal bridge enabling such heat dissipation.

[0041] The second connection zone(s) 14 of the second component 4 are formed, for example, by a pad 42 in thermal exchange relationship with a housing 44 formed by said housing 40. The pad(s) 42 are here made from the material of said housing 44.

[0042] The invention also relates to a manufacturing method for the assembly described above. As will be understood, said method includes a laser welding step of the second component 4 to the first board 2 at the level of the first connection areas, in particular the pads 6.

[0043] Advantageously, the manufacturing process allows, in a single step, the soldering of two printed circuit boards together, and of said printed circuit boards to the second component 4, which can for example be the heat dissipation plate 32.

[0044] The assembly formed by the said first card 2 and the said first components is previously made to form a pre-assembled card equipped with the said first connection areas, in particular the said pads 6.

Claims

Demands

1. Assembly comprising a first printed circuit board (2) having first components connected to each other by at least one conduction track, the first board (2) having one or more first connection areas accessible from at least one face (8), referred to as the connection face, of said first printed circuit board (2), said assembly further comprising at least one second electrical and / or thermal conduction component (4), said second component (4) being connected by laser welding to the first printed circuit board (2) at the level of the or at least one of the first connection areas.

2. Assembly according to claim 1 in which the first connection area(s) comprise a conductive pad (6) in connection with said conduction track.

3. Assembly according to the preceding claim in which said pellet (6) is derived from said conduction track.

4. Assembly according to any one of claims 2 or 3 in which said first printed circuit board (2) includes a housing (16) for said pad (6).

5. Assembly according to the preceding claim in which said housing (16) is blind and / or through so as to permit said welding through said housing (16).

6. Assembly according to any one of the preceding claims wherein said second component (4) comprises an electrically conductive busbar (24).

7. Assembly according to any one of claims 1 to 5 wherein said second component (4) comprises a second printed circuit board (30).

8. Assembly according to any one of claims 1 to 5 wherein said second component (4) comprises a heat dissipation plate (32).

9. Assembly according to any one of claims 1 to 5 wherein said second component (4) comprises a housing (40) for housing the first card (2).

10. A method for manufacturing an assembly according to any one of the preceding claims comprising a laser welding step of the second component (4) to the first board (2) at the level of the first or at least one of the first connection areas, said first board (2) being previously provided with said first component(s).

Images