FIELD OF THE INVENTION

The invention relates to the field of electronic devices, e.g. LED drivers, and more specifically to the field of methods of connecting a circuit board of such an electronic device to a housing of the device. Such a circuit board may e.g. comprise an LED driver or components thereof and may need to be connected to a housing, e.g. an LED driver housing, in order to, during use, provide a grounding of the circuit board.

BACKGROUND OF THE INVENTION

The present invention relates to the field of illumination or illumination sources, in particular LED based illumination sources, that are e.g. powered by an LED driver.

Such an LED driver typically comprises a plurality of electrical components, e.g. having the functionality of a rectifier, a switched mode power converter, a power factor correction device, etc. such components are typically mounted or arranged on one or more boards, referred to as circuit boards, e.g. printed circuit boards or PCBs. Such boards are typically enclosed by a housing which also serves to ground the circuit board. Known methods to connect the circuit board to the housing may require a manual handling of the circuit board and the housing and may require time-consuming handling of the circuit board and housing. Known connecting methods may also suffer from providing an unreliable or insufficient connection of the circuit board to the housing which, during use, may result in an unreliable grounding of the circuit board.. It is an object of the present invention to provide in an alternative manner of connecting a circuit board, e.g. to a housing of an electrical device.

SUMMARY OF THE INVENTION

It would be desirable to provide in a grounding method for a circuit board that is more reliable. It would also be desirable to provide in a method of connecting a circuit board to a housing that is less cumbersome and time-consuming than known methods.

To better address one or more of these concerns, in a first aspect of the invention, there is provided a method of connecting a circuit board to a housing, e.g. a housing of an LED driver, the method comprising:

providing a circuit board with a grounding contact, the grounding contact comprising a through hole; providing a bus or bushing into the through hole, the bus or bushing comprising one or more deformable members, the one or more deformable members at least partially obscuring a passage through the through hole of the circuit board;

providing a housing, the housing comprising a conducting member that is arranged on a surface of the housing;

assembling the circuit board and the housing, thereby connecting the circuit board to the housing by providing a contact between the conducting member and the one or more deformable members.

In a first step, the method according to the present invention comprises the step of providing a circuit board, e.g. a printed circuit board or PCB, with a grounding contact, the grounding contact comprising a through hole. Within the present invention, grounding contact refers to a location on the circuit board which serves to be contacted with a ground potential, e.g. a ground potential provided, during use, by a housing into or onto which the circuit board is to be mounted.

In a second step, the method according to the present invention comprises providing a bus or bushing into the through hole, the bus or bushing comprising one or more deformable members. Within the meaning of the present invention, a bus or bushing refers to a tubular component that can be inserted into the through hole of the circuit board. The tubular component may e.g. have a similar cross-section as the through hole. Both the bus or bushing and the through hole may e.g. have a circular cross-section. The bus or bushing may have a cylinder shape. In accordance with the present invention, the bus or bushing comprises one or more deformable members which are configured to at least partially obscure a passage through the through hole of the circuit board. Such deformable members may e.g. be formed as integral parts of the bus or bushing. In such embodiment, the deformable members may e.g. be realised by applying a cutting process to the bus or bushing.

In a third step, the method according to the present invention comprises providing a housing, the housing comprising a conducting member that is arranged on a surface of the housing. In an embodiment, the conducting member extends in a direction substantially perpendicular to the surface of the housing. Typically, circuit boards, e.g. circuit boards comprising a circuit of an electrical device, e.g. an LED driver, are arranged inside a housing, the housing being, during use, connected to a ground potential. In accordance with the present invention, use is made of a housing that comprises a conducting member, e.g. a pin or strip shaped member. In an embodiment, said member may be arranged to extend in a direction substantially perpendicular to the surface of the housing. Such a conducting member may e.g. be a pin that is soldered or welded to the housing. Alternative means for connecting the conducting member to the housing may be considered as well. In an embodiment, the conducting member is an integral part of the housing, i.e. it is created from a part of the housing.

In a fourth step, the method according to the present invention provides in assembling the circuit board and the housing, in order to connect the circuit board to the housing. Such an assembling of the circuit board and the housing can e.g. be realized by mounting the circuit board to the housing, thereby arranging the conducting member into the bus or bushing. By doing so, an electric contact will be provided between the conducting member and the one or more deformable member of the bus or bushing. In such embodiment, the grounding may thus be realised by inserting the conducting member of the housing into the bus or bushing, thereby providing a contact between the conducting member and the one or more deformable members. Such inserting of the conducting member can be realised by moving the circuit board towards the housing or vice versa. In the fourth step, the grounding contact is created by inserting the conducting member of the housing into the bus or bushing. In accordance with the present invention, a reliable grounding contact is realised due to the deformation of the one or more deformable members that are being deformed or displaced when the conducting member is inserted in the bus or bushing. By doing so, a comparatively easy manner of creating a reliable electrical contact is realised, which does not require a soldering or the like of the housing to the circuit board.

In an embodiment, the present invention provides in a LED driver comprising a circuit board and a housing, whereby a connection of the circuit board to the housing is realised by means of the method according to the present invention.

These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 and 2 depict cross-sectional view of circuit boards that can be applied in the present invention.

Figures 3a and 3b depicts a cross-sectional view of a circuit board and a housing as can be applied in the present invention.

Figure 4a schematically depicts a perspective view of a housing part with a conductive member as can be applied in the present invention. Figure 4b schematically depicts a top view of a housing part with a conductive member as can be applied in the present invention.

Figure 4c schematically depicts a top view of a housing part with another conductive member as can be applied in the present invention.

Figures 5-8b schematically depict various embodiments of buses or bushings as can be applied in the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 depicts a cross-section view of a circuit board 100 comprising a through hole 110, and a bus or bushing 120. Typically, a circuit board, e.g. a printed circuit board or PCB, is provided with a plurality of electrical components such as capacitors, resistors, semiconductor components and processors or processing units, which form an electrical circuit with a particular functionality. Such a printed circuit board including components may also be referred to as a PCBA (printed circuit board assembly). Typically, such a circuit needs to be connected to a ground or ground potential, which is typically provided by a housing of the device that comprises the circuit board. A grounding of the circuit board may serve multiple purposes:

having a ground potential of the circuit substantially equal to the ground potential of the planet; by doing so, issues when connecting the circuit board to other circuits may be avoided.

a grounding may provide a radiation and susceptibility protection (EMC).

Typically, a housing, e.g. a metal housing of an electric or electronic device, is applied or required for the second purpose, i.e. to provide a shielding against EMC. In such case, the application of a connection between the circuit board and the housing as proposed by the present invention avoids the need of having to solder a conducting wire, e.g. a copper lead, to the circuit board.

In the top portion of Figure 1 , the circuit board 100 and the bus or bushing 120 are shown as separate components, whereas, in the bottom portion of Figure 1 , the circuit board 100 and the bus or bushing 120 are shown in an assembled state, i.e. after the bus or bushing 120 has been inserted in the through hole 110 of the circuit board.

In an embodiment, the through hole of the circuit board may be plated prior to the insertion of the bus or bushing. Such an arrangement is schematically shown in Figure 2. Figure 2 depicts a cross-section view of a circuit board 200 comprising a through hole 210, and a bus or bushing 220. In the embodiment as shown, a surface 201.1 of the through hole, i.e. the inner surface of the through hole, has been subjected to a plating process; i.e. the surface has been provided with a layer or coating of an electrically conducting material, e.g. a metal or metal alloy. By doing so, an improved electrical contact between the circuit board 200 and the bus or bushing 220 is obtained when the bus or bushing 220 is mounted inside the through hole 210. In the top portion of Figure 2, the circuit board 200 and the bus or bushing 220 are shown as separate components, whereas, in the bottom portion of Figure 2, the circuit board 200 and the bus or bushing 220 are shown in an assembled state, i.e. after the bus or bushing 220 has been inserted in the through hole 210 of the circuit board 200.

In an embodiment, the circuit board may e.g. comprise a copper track at or near the through hole. In such embodiment, the bus or bushing may be soldered to such a copper track to provide an electrical contact between the circuit board and the bus or bushing.

Figure 3a schematically shows a cross-sectional view of a circuit board 300 with a bus or bushing 320 inserted in a through hole of the circuit board 300, and part of a housing 350, the housing part 350 comprising a conducting member 360. In an embodiment of the present invention, a good electrical contact between the bus or bushing and the circuit board, e.g. a plating of the circuit board may be realized by proper dimensioning of the through hole and the bus or bushing. In particular, by dimensioning the bus or bushing such that its outer dimensions, e.g. an outer diameter, are slightly larger than an inner dimension of the through hole, a mechanical force or pressure needs to be applied to insert the bus or bushing into the through hole and keeping the bus or bushing in contact with the through hole or plating of the through hole. In the embodiment as shown, the bottom portion 320.1 of the bus or bushing 320 is assumed to comprise one or more deformable members. In the top portion of Figure 3a, the circuit board 300 and the housing part 350 are shown as separate components, i.e. in a disassembled state, whereas in the bottom portion of Figure 3a, the circuit board 300 and housing 350 are shown after the conducting member 360 has been inserted in the bus or bushing 320 that is provided in the through hole of the circuit board 300. As schematically shown in bottom portion, by inserting the conducting member 360, e.g. a metal pin or strip, into the bus or bushing 320, the conducting member 360 will contact the one or more deformable members comprised in the bottom portion 320 1 of the bus or bushing 320, thereby deforming the one or more deformable members and pushing them upwards in order to allow passage of the conducting member in the bus or bushing 320. In an embodiment of the present invention, the one or more deformable members of the bus or bushing applied are thus arranged so as to obscure a passage through the bus or bushing of the conducting member, or, at least partly, hinder the insertion of the conducting member. Due to the one or more deformable members being deformable however, the conducting member, e.g.

member 360, can be inserted, causing the deformable members to deform, thereby ensuring an electrically conducting contact with the conducting member. In the embodiment as schematically shown in Figure 3a, the bus or bushing 320 is inserted into the through hole of the circuit board via the top surface 300.1 of the circuit board 300. By doing so, a flange

320.1 of the bus or bushing 320 becomes substantially flush with this top surface 300.1.

In an alternative embodiment, as schematically shown in Figure 3b, the bus or bushing 320 is inserted into the through hole of the circuit board 300 via a bottom surface

300.2 of the circuit board, as e.g. shown in top portion of Figure 3b. The bottom portion of Figure 3b schematically shows the circuit board 300 and housing in an assembled state, whereby the conducting member 360 protrudes the bottom portion 320.1 of the bus or bushing 320, thereby contacting the one or more deformable members of the bus or bushing 320. In the embodiment as schematically shown in Figure 3b, the flange 320.2 of the bus or bushing 320, the flange being substantially flush with the bottom surface 300.2 of the circuit board 300, prohibits that the bus or bushing 320 is pushed through the through hole, when the conducting member 360 is inserted. In the embodiment as shown in Figure 3a, prohibiting that the bus or bushing 320 is pushed back out of the through hole may require that the bus or bushing is firmly attached to the circuit board 300. This can e.g. be realized by soldering the bus or bushing 320, in particular the flange 320.2 of the bus of bushing to the top surface 300.1 of the circuit board, e.g. to a copper track arranged on the top surface 300.2 of the circuit board. Alternatively, or in addition, the dimensioning of the through hole and bus or bushing may be such that, after its insertion, the bus or bushing remains firmly mounted to the through hole, even during the insertion of the conducting member.

In an embodiment of the present invention, the conducting member is created or manufactured as an integral member of the housing; i.e. the conducting member is not a separate component that is mounted to the housing but rather, it is manufactured from a part of the housing.

Figure 4a schematically shows an embodiment of a part of a housing whereby a conducting member is manufactured from a part of the housing. Figure 4a schematically shows a portion 375 of a housing that can e.g. be applied to enclose a circuit board of an electrical device, e.g. an LED driver. The portion 375 of the housing can e.g. be a bottom plate of the housing. Such a housing or housing portion may typically be made from a metal or metal alloy. In the embodiment as shown, the housing portion 375 comprises a conducting member 385 that extends in a direction substantially perpendicular to a surface of the housing portion 375. In the embodiment as shown, the conducting member 385 is a strip-shaped conducting member that is for example manufactured by applying a cutting process along the contour 390 and folding or pushing the strip thus formed upwards, in the direction as indicated by the arrow 395. Alternative manufacturing techniques can be considered too, such as die-cutting, punching, stamping, etc. By providing the conducting member 385 as an integral part of the housing, a well-defined and reliable electrical contact between the conducting member 385 and the housing or housing part 375 can be ensured. As will be understood by the skilled person, alternative shapes for the conducting member such as triangular or trapezoidal shapes can be considered as well. It can be pointed out that the orientation of the conducting member relative to the housing need not be perpendicular, but may depend on the orientation of the housing relative to the circuit board during the assembling of the housing to the circuit board. In case the mounting of the circuit board to the housing would require for example a rotational movement, it may be advantageous to have the conducting member extend in a non-perpendicular direction, in order to insert it in the through hole of the circuit board.

Figure 4b schematically depicts a top view of the housing part 375 of Figure 4a with the conductive member 385, prior to the conductive member 385 being folded upwards. Figure 4b further shows the contour 390 along which a cutting process, e.g. a laser cutting process can be performed, in order to form the conductive member 385.

Figure 4c schematically depicts a top view of another housing part 376 with a conductive member 386, prior to the conductive member 386 being folded upwards. Figure 4c further shows the contour 390 along which a cutting process, e.g. a laser cutting process can be performed, in order to form the conductive member 386. In the embodiment as shown, the conductive member 386 comprises a base portion 386.1 , the base portion being closest to the housing surface 376 when the conductive member is folded upwards, and a top portion 386.2, the top portion 386.2 being further remote from the housing surface 376 when the conductive member is folded upwards. In the embodiment as shown, the top portion 386.2 is dimensioned in such manner that it can be inserted in the through hole of a circuit board, in particular in a bus or bushing that is mounted in such a through hole, in order to contact the one or more deformable members of the bus or bushing. The base portion 386.1 however is dimensioned in such manner that it has a width Wb that is wider than a corresponding dimension of the bus or bushing, such that it cannot be inserted into the bus or bushing. By doing so, i.e. by having a conductive member that has a base portion that is too wide for insertion into the bus or bushing, one can ensure that a controlled distance remains between the circuit board and the housing, when the conductive member 386 is inserted into the bus or bushing of the circuit board. As will be understood by the skilled person, a similar spacing between the circuit board and the housing can be realized by applying a conductive member that has a trapezoidal or triangular shape.

The embodiment of the present invention whereby the conducting member is created or manufactured as an integral member of the housing may advantageously be combined with the step of soldering the bus or bushing as applied to the conducting member. By doing so, a further improvement to the grounding resistance can be obtained. As will be appreciated by the skilled person, there are standards or norms to which a grounding resistance may need to comply, whereby the grounding resistance needs to be below a predefined value. By the grounding methods according to the invention, in particular grounding methods whereby an integral member of the housing is connected, e.g. via a bus or bushing, to the circuit board, ensure that such requirements are met. An additional soldering of the bus or bushing to the conducting member ensure a further low resistance path between the circuit board and the housing.

Figures 5-8b schematically show, in more detail, various embodiments of the buses or bushings as can be applied in the present invention to realize an electrical contact between a circuit board and a housing, in order to provide a grounding contact to the circuit board. It is submitted that the manufacturing of such bus or bushing or of the housing requires careful engineering as is known to a person skilled in metallics. Such aspects e.g. are the material choice of pin, bus or bushing, material thickness, cutting/punching/stamping mechanisms, amount of material deformation, not violating Hooke’s law, and resulting material measures, applicable tooling forces, etc.

The top portion of Figure 5 schematically shows a cross-sectional view of a bus or bushing 400 as can be applied in the present invention. The bus or bushing 400 as shown comprises a tubular portion 410 and a flange 420. Such a flange 420 may be advantageously applied in order to ensure that the bus or bushing 400, in particular the tubular portion 410 remains inside the through hole of the circuit board and does not fall through the hole. In order to ensure this, a dimension D of the flange 420, e.g. an outer diameter of the flange, should be larger than a corresponding dimension of the through hole. In the embodiment as shown, the tubular portion 410 is open at both ends, i.e. at the top end 400.1 1 where the flange 420 is present and at the bottom end 400.12. In an embodiment, the tubular portion 410 may have a circular cross-section although other cross-sections such as square or rectangular may be considered as well.

In the embodiment as shown, the bus or bushing 400 further comprises two deformable members 400.3, the deformable members 400.3 being connected to the tubular portion 410 at lower ends 400.31 , the top ends 400.32 of the deformable members 400.3 being brought in close vicinity at the top ends, thereby at least partially blocking or hindering a passage in or through the bus or bushing 400, in particular a passage through the tubular portion 410 of the bus or bushing 400. The two deformable members 400.3 can e.g. be manufactured by a cutting process applied to the tubular portion 410 of the bus or bushing 400. The bottom portion of Figure 5 schematically shows a side view of the bus or bushing 400 and a contour 400.33 along which a cutting process can be performed, in order to create the deformable portion or portions 400.3. After the cutting process, the one or more deformable members 400.3 can be brought into the position as shown in the top portion of Figure 5 by pushing the deformable members 400.3 inwards, i.e. in a direction as indicated by the arrows 430. Figure 6 schematically depicts another embodiment of a bus or bushing 500 that can be applied in the present invention. The top portion of Figure 6 schematically shows a cross- sectional view of a bus or bushing 500 as can be applied in the present invention. The bus or bushing 500 as shown comprises a tubular portion 500.1 and a flange 500.2. Such a flange 500.2 may be advantageously applied in order to ensure that the bus or bushing 500, in particular the tubular portion 500.1 remains inside the through hole of the circuit board and does not fall through the hole. In the embodiment as shown, the tubular portion 500.1 is open at the top end 500.11 , where the flange 500.2 is present and is initially closed at the bottom end 500.12, or at least initially has a partial bottom end 500.12. In an embodiment, the tubular portion 410 may have a circular cross-section although other cross-sections such as square or rectangular may be considered as well.

In accordance with the present invention, the bus or bushing 500 comprises one or more deformable members 500.3 that are schematically shown in the bottom portion of Figure 6, the bottom portion of Figure 6 schematically showing a top view of the bus or bushing 500.

In the embodiment as shown, the bottom portion 500.12 of the bus or bushing 500 comprises three wedge shaped portions, which can e.g. be made by performing a cutting process to the bottom portion 500.12 of the bus or bushing 500. As can be seen, the deformable portions thus created at least partially block the bottom end of the tubular portion 500.1. As such, when a conducting member such as conducting member 360 or 385 is inserted into the bus or bushing 500, i.e. via the bottom portion 500.12 of the bus or bushing 500, this will require the deformable portions 500.3 to be folded or deformed upwards, by the conducting member. When the conducting member is thus inserted, a reliable electrical contact between the conducting member, and thus the housing, and the bus or bushing that is provided in the through hole of the circuit board. In the embodiment as shown in Figure 6, the three wedge shaped deformable members may e.g. be generated by cutting away or removing the area 500.4 of the bottom portion 500.12 of the bus or bushing 500.

As will be understood by the skilled person, alternative shapes may be applied as well for the deformable members.

Figure 7 schematically shows two alternative manners for generating one or more deformable members in a bottom portion of a bus or bushing as can be applied in the present invention.

The top portion of Figure 7 schematically shows a top view of a bus 600 having a tubular portion 600.1 and a flange 600.2, e.g. similar to the tubular portion 500.1 and the flange 500.2 of bus 500 shown in Figure 6. In the embodiment as shown, a bottom portion of the tubular portion 600.2 has be processed, e.g. by a cutting process, to form 4 wedge shaped deformable members 600.3, e.g. by cutting the bottom portion along the lines 600.4. The bottom portion of Figure 7 schematically shows a top view of a bus 700 having a tubular portion 700.1 and a flange 700.2, e.g. similar to the tubular portion 500.1 and the flange 500.2 of bus 500 shown in Figure 6. In the embodiment as shown, a bottom portion of the tubular portion 700.2 has be processed, e.g. by a cutting process, to form two strip shaped deformable members 700.3, e.g. by cutting away or removing part 700.4 of the bottom portion.

Figure 8a schematically shows, in the top portion, a cross-sectional view of a bus or bushing 800 that can be applied in the present invention to connect a circuit board to a housing. The bus or bushing 800 comprises a side surface 800.1 , a bottom flange 800.2 and a bottom portion 800.3. The bus or bushing 800 may e.g. be realized by deep-drawing a disk-shaped metal sheet. The bottom portion 800.3 may e.g. be processed in a similar manner as shown in Figures 6 or 7, so as to provide the bottom portion 800.3 with one or more deformable members, as is shown in the bottom portion of Figure 8a, which schematically shows a top view of the bus or bushing 800. In the embodiment as shown, a top portion 800.4 of the side surface 800.1 of the bus or bushing 800 is provided with multiple cuts (not shown) which enable the top portion 800.4 to be folded outwardly, after the bus or bushing 800 has been inserted. In Figure 8b, top portion, the bus or bushing 800 is schematically shown after being inserted in a circuit board 810. The arrows 820 indicate the direction in which the top portion 800.4 is to be folded. Figure 8b, bottom portion schematically shows the bus or bushing 800 as arranged in the circuit board 810, after the top portion 800.4 of the bus or bushing 800 has been folded outwardly, thereby generating a top flange 800.5.

The method according to the present invention may advantageously be applied for the grounding of circuit boards of electrical devices. As such, the present invention provides in an electrical device that comprises a circuit board and a housing and wherein the circuit board is grounded to the housing according to the grounding method according to the present invention, as described above.

As an example of such an electrical device, an LED driver can be mentioned. As such, in an embodiment, the present invention provides in an LED driver comprising a circuit board and a housing and wherein the circuit board is grounded to the housing according to the grounding method according to the present invention, as described above.

In such embodiment, the circuit board may e.g. comprise at least one of a rectifier circuit, a switched mode power converter circuit or a power factor correction circuit.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention.

The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language, not excluding other elements or steps). Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The term coupled, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.