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Title:
AN ELECTRICAL UNIT
Document Type and Number:
WIPO Patent Application WO/2013/006103
Kind Code:
A1
Abstract:
The present invention relates to an electronic unit (16) comprising a housing (1) and a circuit board (2) arranged to be mounted to the housing (1).The housing (1)in turn comprises a first wall (3) and a first electrical component (4) mounted onto the first wall (3). The first electrical component (4) has at least one electrically conducting contact pin (5, 6). The electronic unit (16) further comprises a first connector (7), a second connector (8) and an intermediate holder (9). The connectors (7, 8) are attached to the circuit board (2) and to said contact pin (5, 6) such that an electrical connection is formed between said contact pin (5, 6) and the circuit board (2). The intermediate holder (9) is arranged to hold the connectors (7, 8) in fixed relation with respect to one another. The intermediate holder (9) comprises at least one of a first type of holder guiding parts (10, 11) that is arranged to engage at least one corresponding circuit board guiding part (12, 13).

Inventors:
HUGAUD PASCAL (FR)
LENORMAND HUGUES (FR)
Application Number:
PCT/SE2011/050914
Publication Date:
January 10, 2013
Filing Date:
July 06, 2011
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
AUTOLIV DEV (SE)
HUGAUD PASCAL (FR)
LENORMAND HUGUES (FR)
International Classes:
H01R9/18; H05K3/30; H05K3/32
Domestic Patent References:
WO2009010704A12009-01-22
Foreign References:
DE10062962A12002-07-25
US6163460A2000-12-19
US6341976B12002-01-29
Attorney, Agent or Firm:
AUTOLIV DEVELOPMENT AB (Wallentinsvägen 22, Vårgårda, SE)
Download PDF:
Claims:
CLAIMS 1. An electronic unit (16) comprising a housing (1) and a circuit board (2) arranged to be mounted to the housing (1), the housing (1) in turn comprising a first wall (3) and a first electrical component (4) mounted onto the first wall (3), the first electrical component (4) having at least one electrically conducting contact pin (5, 6) , the electronic unit (16) further comprising at least one connector (7, 8) and an intermediate holder (9), where said connector (7, 8) is attached to the circuit board (2) and to said contact pin (5, 6) such that an electrical connection is formed between said contact pin (5, 6) and the circuit board (2), the intermediate holder (9) being arranged to hold said connector (7, 8) in fixed relation with respect to one another, characterized in that the intermediate holder (9) comprises at least one of a first type of holder guiding parts (10, 11) and that the circuit board (2) comprises at least one corresponding circuit board guiding part (12, 13), where said first type of holder guiding parts (10, 11) is arranged to engage said corresponding circuit board guiding part (12, 13) . 2. An electronic unit according to claim 1, characterized in that the electronic unit (16) comprises a first connector (7) and a second connector (8), the first electrical component (4) having two corresponding electrically conducting contact pins (5, 6) , where the intermediate holder (9) i arranged to hold the connectors (7, 8) in fixed relation with respect to one another.

3. An electronic unit according to any one of the claims

1 or 2, characterized in that said first type of holder guiding part (10, 11) is in the form of a protrusion and that the circuit board guiding part (12, 13) is in the form of a corresponding aperture. 4. An electronic unit according to any one of the previous claims, characterized in that the intermediate holder (9) comprises at least one of a second type of holder guiding parts (14) that is arranged to engage at least one corresponding housing guiding part (15) .

5. An electronic unit according to claim 4, characterized in that said second type of holder guiding part is in the form of an aperture (14) and that the housing guiding part is in the form of a corresponding protrusion (15) .

6. An electronic unit according to any one of the previous claims, characterized in that each connector (7, 8) is attached to the circuit board (9) by means of soldering, gluing or press-fitting.

7. A method for assembling an electronic unit (16) comprising the steps:

mounting a first electrical component (4) onto a first wall (3) of a housing (1); and

attaching electrically conducting connectors (7, 8) to an intermediate holder (9) used to hold the connectors (7, 8) in fixed relation with respect to one another;

characterized in that the method further comprises the steps:

mounting the assembled connectors (7, 8) and intermediate holder (9) to the circuit board (2) using guiding means (10, 11; 12, 13) provided in the intermediate holder (9) and in the circuit board (2); and mounting the housing (1) to the circuit board (2) such that electrical contact is made between the first electrical component (4) and the connectors (7, 8) using further guiding means (14, 15) provided in the intermediate holder (9) and in the housing (1), an electrical connection being formed between the first electrical component (4) and the circuit board (2) .

8. A method according to claim 7, characterized in that the step of mounting the assembled connectors (7, 8) and intermediate holder (9) to the circuit board (2) comprises the steps of:

dispensing a conductive compound on positions on the circuit board (2) where the connectors (7, 8) are intended to make electrical contact with the circuit board (2);

placing the assembled connectors (7, 8) and intermediate holder (9) on the circuit board (2) such that pin parts (29a, 29b) comprised in the connectors (7, 8) at least party are positioned in the conductive compound; and

allowing the conductive compound to harden.

9. A method according to claim 7, characterized in that the step of mounting the assembled connectors (7, 8) and intermediate holder (9) to the circuit board (2) comprises the steps of:

mounting the assembled connectors (7, 8) and intermediate holder (9) to a temporary holding tool (38);

pressing a circuit board (2) against the temporary holding tool (38) such that the connectors (7, 8) are press- fitted to the circuit board (2) using guiding means (10, 11; 12, 13) provided in the intermediate holder (9) and in the circuit board (2); and

removing the temporary holding tool (38) .

10. A method according to claim 9, characterized in that the method comprises the step of mounting at least one further component (39) , intended to be press-fitted to the circuit board (2), to the temporary holding tool (38) when the assembled connectors (7, 8) and intermediate holder (9) are mounted to the temporary holding tool (38) .

Description:
An Electrical Unit

Description of the invention

The present invention relates to an electronic unit comprising a housing and a circuit board arranged to be mounted to the housing, the housing in turn comprising a first wall and a first electrical component mounted onto the first wall. The first electrical component has at least one electrically conducting contact pin. The electronic unit further comprises a first connector, a second connector and an intermediate holder. The connectors are attached to the circuit board and to said contact pin such that an electrical connection is formed between said contact pin and the circuit board. The intermediate holder is arranged to hold the connectors in fixed relation with respect to one another.

The present invention also relates to a method for assembling an electronic unit comprising the steps of: mounting a first electrical component onto a first wall of a housing and attaching electrically conducting connectors to an intermediate holder used to hold the connectors in fixed relation with respect to one another.

In several technical fields, for instance in the control of electrical systems on board a motor vehicle, it is desirable to provide a sealed non-conductive (e.g. plastic) housing containing a PCB, onto which are mounted several electrical components. An electrical unit of this type is disclosed in US 6163460.

In many cases, one of the electrical components that must be housed within the unit is a large, relatively heavy capacitor. While most of the electronic components are surface-mounted on the PCB, it is preferred not to attach a bulky capacitor to the PCB directly, since the weight of the capacitor is likely to break or distort the substrate or electrically conducting tracks of the PCB under certain conditions. It has therefore been proposed to attach large components such as capacitors to an interior surface of the housing of the unit, so that the weight of the component places no mechanical stress on the PCB itself, and to connect the component electrically to the PCB by one or more wires, cables or similar. However, when assembling a unit of this type, it is preferred not to carry out such soldering operations, since they would be undesirable due to cost and efficiency.

In WO 2009/010704 it is descried how intermediate electrical connectors in holders are positioned such that conductive communication is provided between the PCB and conductive contact pins of a component, such as a relatively large and heavy capacitor attached to a housing of an electronic unit. The electrical connectors are press-fitted into the PCB in order to achieve the desired stability and electrical contact.

However, the need for press-fitting requires special electrical connectors, and in some situations it is desired to have other types of connections to the PCB while maintaining the desired stability. There may also be a need for further alignment .

There is thus a need for an electronic unit comprising a PCB and a housing, where an electrical component is mounted to the housing and connection is made between the component and the PCB with more flexibility than presented in prior art, enabling different mounting possibilities and not necessarily requiring any complex pin designs. It is an object of the present invention to provide an electronic unit according to the above.

The object above is achieved by means of an electronic unit comprising a housing and a circuit board arranged to be mounted to the housing. The housing in turn comprises a first wall and a first electrical component mounted onto the first wall. The first electrical component has at least one electrically conducting contact pin. The electronic unit further comprises a first connector, a second connector and an intermediate holder. The connectors are attached to the circuit board and to said contact pin such that an electrical connection is formed between said contact pin and the circuit board. The intermediate holder is arranged to hold the connectors in fixed relation with respect to one another. The intermediate holder comprises at least one of a first type of holder guiding parts and the circuit board comprises at least one corresponding circuit board guiding part. Said first type of holder guiding parts is arranged to engage said corresponding circuit board guiding part.

Said first type of holder guiding part may for example be in the form of a protrusion and the circuit board guiding part may for example be in the form of a corresponding aperture.

According to an example, the intermediate holder comprises at least one of a second type of holder guiding parts that is arranged to engage at least one corresponding housing guiding part .

Said second type of holder guiding part may for example be in the form of an aperture and the housing guiding part may for example be in the form of a corresponding protrusion. This object is also achieved by means of a method for assembling an electronic unit comprising the steps of:

mounting a first electrical component onto a first wall of a housing, and

attaching electrically conducting connectors to an intermediate holder used to hold the connectors in fixed relation with respect to one another.

The method further comprises the steps of:

mounting the assembled connectors and intermediate holder to the circuit board using guiding means provided in the intermediate holder and in the circuit board, and

mounting the housing to the circuit board such that electrical contact is made between the first electrical component and the connectors using further guiding means provided in the intermediate holder and in the housing, so that an electrical connection is formed between the first electrical component and the circuit board.

The step of mounting the assembled connectors and intermediate holder to the circuit board comprises the steps of:

dispensing a conductive compound on positions on the circuit board where the connectors are intended to make electrical contact with the circuit board,

placing the assembled connectors and intermediate holder on the circuit board such that pin parts comprised in the connectors at least party are positioned in the conductive compound, and

allowing the conductive compound to harden. Alternatively, the step of mounting the assembled connectors and intermediate holder to the circuit board comprises the steps of:

mounting the assembled connectors and intermediate holder to a temporary holding tool, pressing a circuit board against the temporary holding tool such that the connectors are press-fitted to the circuit board using guiding means provided in the intermediate holder and in the circuit board, and

removing the temporary holding tool.

Further examples are apparent in the dependent claims.

A number of advantages are obtained by means of the present invention, for example the first electrical component may be attached to the circuit board in any suitable way such as soldering or gluing. When press-fitting the electrical component to the circuit board, an enhanced alignment is acquired, where the design of the press-fit pins may be less complex .

Brief description of the drawings

The present invention will now be described more in detail with reference to the appended drawings, where:

Figure 1 shows a schematic perspective view of an electronic unit ;

Figure 2 shows a schematic perspective view of a capacitor about to be mounted in a housing according to the present invention;

Figure 3 shows a schematic perspective view of a capacitor mounted in a housing according to the present invention ;

Figure 4 shows a schematic perspective view of connectors about to be mounted in a holder according to the present invention; Figure 5 shows a schematic perspective view of connectors mounted in a holder according to the present invention ;

Figure 6 shows a schematic perspective view of the device in

Figure 5 turned 180° along its longitudinal axis;

Figure 7 shows a schematic perspective view of a holder according to the present invention about to be mounted in a temporary holding tool;

Figure 8 shows a schematic perspective view of a holder according to the present invention mounted in a temporary holding tool, and a printed circuit board about to be mounted to the holder and the temporary holding tool;

Figure 9 shows a schematic perspective view of the printed circuit board mounted to the holder and the temporary holding tool;

Figure 10 shows a schematic perspective view of the printed circuit board mounted to the holder with the temporary holding tool removed;

Figure 11 shows a schematic perspective view of a holder according to the present invention mounted to the printed circuit board and being about to be mounted to the housing; and

Figure 12 shows a schematic perspective view of an alternative housing according to the present invention. Detailed description

With reference to Figure 1, an electronic unit 16 is shown, the electronic unit 16 comprising a printed circuit board 2 (PCB) and a housing 1. The electronic unit 16 may be a part of a control system in a vehicle and comprises electronic components and connectors, although these are not shown in this simplified view. The PCB 2 is of an ordinary kind, comprising conductive tracks and component connections. The PCB 2 may have one or several conductive layers, where some layers may comprise conductive tracks and some layers may comprise ground planes.

With reference to Figure 2, the housing 1 is shown having a first wall 3, facing downwards in Figure 2, and corresponding side walls 19, 20, 21 22 to define an inner space. For reasons of clarity, one side wall 22, shown transparent and indicated with dashed lines, will not be shown in Figure 3, Figure 11 and Figure 12, although it should be assumed to be present. The housing 1 is formed from a sturdy, insulating material such as a plastics material.

There is a mounting arrangement 24 comprising a first clip pair 25 and a second clip pair 26, the clip pairs 25, 26 projecting from an inner side of the first wall 3 in an opposing manner. Each clip in the clip pairs 25, 26 comprises a substantially rectangular body, which is arranged to be generally perpendicular to the inner side of the first wall 3, and each of the clips in the clip pairs 25, 26 has a protruding lip 27, 28 at or near the free end thereof, which protrudes towards the other one of the clip pairs 25, 26. Only the lips 27, 28 of the first clip pair 25 are shown, the other clip pair 26 having corresponding lips. The clip pairs 25, 26 are preferably formed from a sturdy, resilient, non-conductive material, and may be formed integrally with the first wall 3. A capacitor 4 is shown and is of a type which incorporates a relatively large, substantially cylindrical body 30 and has two electrically conducting contact pins 5, 6 protruding therefrom, each of the contact pins 5, 6 comprising a metal lead having a round or rectangular cross-section.

The mounting arrangement 24 is adapted to receive and retain the capacitor 4. The dimensions and spacing of the two clip pairs 25, 26 are such that the body 30 of the capacitor 4 may be pushed between them, contacting the lips 27, 28 thereof so that the clip pairs 25, 26 are deflected and forced apart, and then allowed to return to their initial positions once the body 30 of the capacitor 4 has been pushed past the lips 27, 28. The capacitor 4 is then held in pi3.CG / cL S shown in Figure 3, being trapped between the inner surfaces of the first wall 18 and the clip pairs 25, 26, and being prevented from becoming detached from the mounting arrangement 24 by the protruding lips 27, 28 of the two clip pairs 25, 26, since the gap between the protruding lips 25, 26 is less than the width of the body 30 of the capacitor 4.

When the capacitor 4 is mounted as shown in Figure 3, the contact pins 5, 6 are arranged to rest on a positioning element 35 attached to the inner side of the first wall 3. The positioning element 35 is preferably formed from a robust, non-conductive material, and comprises a first groove 36 and a second groove 37, the grooves 36, 37 being arranged to receive the contact pins 5, 6.

With reference to Figure 4, the electronic unit further comprises a first connector 7 and a second connector 8, each connector having a corresponding pin part 29a, 29b arranged to contact the PCB 2, a corresponding intermediate main body 31a, 31b and, opposite the pin parts 29a, 29b, a corresponding contact arrangement 32a, 32b. Each contact arrangement 32a, 32b is adapted to form electrical contact with a corresponding pin 5, 6 of the capacitor 4. Each contact arrangement 32a, 32b therefore comprises a pair of spaced apart tines 33a, 34a; 33b, 34b, each having a gap between them which is adapted to receive and to electrically contact the contact pins 5, 6 of the capacitor 4.

The electronic unit further comprises an intermediate holder 9, arranged to hold the connectors 7, 8 in fixed relation with respect to one another, the holder 9 being a molded plastic component having a first slot 35a and a second slot 35b, the slots 35a, 35b running through the holder and being dimensioned to receive and retain the connectors 7, 8, as shown in Figure 5, so that at least the pin parts 29a, 29b project from one side of the holder 9 and the connection arrangements 32a, 32b project from the other side of the holder 9.

In the finally mounted electronic unit, the connectors 7, 8 are attached to the PCB 2 and to the contact pins 5, 6 such that an electrical connection is formed between the contact pins 5, 6 and the circuit board 2, each connector 7, 8 connecting a corresponding contact pin 5, 6 to the PCB 2. The connection to the PCB 2 is performed by press-fitting the pin parts 29a, 29b into corresponding connector apertures 17a, 17b in the PCB 2, each of the connector apertures 17a, 17b being in conductive communication with at least one conductive track formed on the PCB 2. According to the present invention, as shown in Figure 4 and Figure 5, showing an assembly 23 of the connectors 7, 8 and the intermediate holder 9, the intermediate holder 9 comprises a first guiding part 10 and a second guiding part 11 in the form of protrusions which are arranged to engage corresponding PCB guiding parts 12, 13 in the form of corresponding apertures as shown in Figure 8. The protrusions 10, 11 in the intermediate holder 9 constitute a first type of holder guiding part.

Furthermore, as shown in Figure 6, the intermediate holder 9 comprises a third guiding part 14 in the form of an aperture that is arranged to engage a corresponding housing guiding part in the form of a protrusion 15 in the positioning element 35 as shown in Figure 2. The aperture 14 in the intermediate holder 9 constitutes a second type of holder guiding part.

The holder guiding parts 10, 11, 14 provide a more precise mounting of the housing 1 to the PCB, and more specifically a more precise mounting of the capacitor 4. This leads to a more flexible mounting possibility of the capacitor 4 to the PCB 2, the holder guiding parts 10, 11, 14 providing the necessary fitting. This results in that the pin parts 29a, 29b may be soldered or glued to the connector apertures 17a, 17b in the PCB 2 as well, and no further alignment is necessary for any type of mounting.

The connector apertures 17a, 17b may be substituted to electrically conducting pads or surfaces on the PCB 2, to which the pin parts 29a, 29b are glued or soldered, the pin parts then being configured for surface-mounting.

When assembling the electronic unit and thus mounting the capacitor 4, the housing 1 and the PCB 2, different methods may be used depending on which type of connection that is intended to be made between the pin parts 29a, 29b and the PCB 2. For all methods described here, the capacitor 4 is fixed to the mounting arrangement 24 as shown in Figure 2 so that the contact pins 5, 6 of the capacitor 4 lie substantially parallel to, but spaced apart from, the first wall 3. The connectors 7, 8 are inserted into the holder 9 as shown in Figure 4 and Figure 5. If the pin parts 29a, 29b are soldered to corresponding electrically conducting pads or surfaces on the PCB 2, a standard surface-mounting process may be used, for example in the form of so-called pin-in-paste where solder paste first is dispensed to the electrically conducting pads and then the assembly 23 comprising the assembled connectors 7, 8 and intermediate holder 9 is placed on the PCB 2 by a pick & place machine such that the adapted pin parts 29a, 29b at least partly are positioned in the adhesive solder paste. The assembly 23 is placed on the PCB 2 by the pick & place machine such that the first guiding part 10 and the second guiding part 11 in the intermediate holder 9 engage the corresponding PCB guiding parts 12, 13.

When the assembly 23 is in place, a reflow soldering takes place where the solder paste is melted and then allowed to cool and harden such that the pin parts 29a, 29b are soldered in place.

When the assembly has been soldered in place, the housing 1 is mounted to the PCB 2 as shown in Figure 11 such that electrical contact is made between the contact pins 5, 6 of the capacitor 4 and the connectors 7, 8, where the guiding aperture 14 provided in the holder 9 and the guiding protrusion 15 provided in the housing are used for alignment at the mounting procedure such that no further alignment is needed .

If the pin parts 29a, 29b are glued to corresponding electrically conducting pads or surfaces on the PCB 2, a corresponding procedure is carried out, with the solder paste changed to electrically conducting glue.

Instead of surface-mounting, it is of course conceivable that the pin parts 29a, 29b are inserted in the previously mentioned connector apertures 17a, 17b in the PCB 2 and soldered or glued in the desired position.

In the following, a mounting procedure for the capacitor, the housing 1 and the PCB will be described for press-fitting, using a temporary holding tool 38.

With reference to Figure 7, the assembly 23 comprising the assembled connectors 7, 8 and the holder 9 are mounted to a temporary holding tool 38, holding the assembly 23 in a fixed position. As also is shown in Figure 7, one further part 39, intended to be mounted to the PCB 2 as well, is also mounted to the temporary holding tool 38. The mounting to the temporary holding tool 38 is made by inserting the parts in question in corresponding apertures 40, 41 in the temporary holding tool 38. The further part 39 may be any kind of part such as a connector arrangement for external contact with the electronic unit 16, shown as an example of how the temporary holding tool 38 may be used for more than one component to be mounted to the PCB 2.

As shown in Figure 8 and Figure 9, the PCB 2 is pressed against the temporary holding tool 38 such that the connectors 7, 8 are press-fitted to the connector apertures 17a, 17b in the circuit board 2 using the guiding protrusions 10, 11 provided in the holder 9 and the corresponding apertures 12, 13 provided in the circuit board 9 for alignment at the mounting procedure such that no further alignment is needed. The further part 39 comprises a connector row 42 that is press-fitted to a corresponding connector aperture row 43 in the PCB 2.

As shown in Figure 10, the temporary holding tool 38 is now removed, where the assembly 23 and the further part 39 are shown with dashed lines.

With reference now to Figure 11, the housing 1 is mounted to the PCB 2 such that electrical contact is made between the contact pins 5, 6 of the capacitor 4 and the connectors 7, 8, where the guiding aperture 14 provided in the holder 9 and the guiding protrusion 15 provided in the housing is used for alignment at the mounting procedure such that no further alignment is needed.

Since the contact pins 5, 6 are arranged to rest on the grooves 36, 37 in the positioning element 35, the contact pins 5, 6 are prevented from being deflected away from the PCB 2 when it is mounted, such an undesired deflection most likely preventing the contact pins 5, 6 from forming a good electrical and mechanical with the connectors 7, 8.

Now, an electrical connection has been formed between the contact pins 5, 6 of the capacitor 4 and the PCB 2.

As shown in Figure 7, Figure 8 and Figure 9, the PCB 2 is provided with guiding apertures 44, 45 which are arranged to receive corresponding guiding protrusions 46, 47 in the temporary holding tool 38 in order to obtain an even better alignment when the PCB 2 is mounted to the temporary holding tool 38.

The present invention is not limited to the above, but may vary freely within the scope of the appended claims. For example, the capacitor 4 may be mounted to any suitable mounting arrangement in the housing 1, comprising any number and type of holders. The capacitor 4 may even be glued or stuck to the housing 1 in any other convenient way. In the same way, the positioning element configuration may vary. With reference to Figure 12, an example of a different arrangement for the housing 1' is shown, where only one clip 46, 47 at each side is used. Furthermore, four positioning elements 48, 49, 50, 51 are used, two for each contact pin 5, 6, each positioning element 48, 49, 50, 51 comprising a pair of guiding protrusions 52, 53, 54, 55.

The first wall 3 may be any of the walls in the housing 1. In the example above, it is a top or bottom wall with surrounding side walls, and may then also form a removable lid. If the first wall 3 is such a lid of the housing 1, the connection between the PCB 2 and the capacitor 4 may be formed when the lid 3 is placed on the housing 1 to form a sealed unit. There may be less walls in the housing than shown.

The electronic unit 16 may have any suitable shape, for example cylindrical, where the electric component in that case is positioned on a flat circular wall.

The PCB may be any sort of suitable circuit board, being made from for example glass fiber or any other suitable material. The number and type of guiding parts may vary, the types and numbers shown is just an example of a possible configuration. The holder comprises at least one of a first type of holder guiding parts 10, 11 that is arranged to engage at least one corresponding circuit board guiding part 12, 13. Preferably, the intermediate holder 9 also comprises at least one of a second type of holder guiding parts 14 that is arranged to engage at least one corresponding housing guiding part 15. The shape of the guiding parts may vary, as long as the two corresponding guiding parts have a guiding function, they may for example be rectangular or polygonal.

All materials mentioned are only to be regarded as examples of suitable materials.

The capacitor 4 may generally be any type of component having at least one contact pin 5, 6 that is intended to be electrically connected to the PCB 2. A number of electrical components may be attached to the housing and mounted to the PCB in the same way as the capacitor 4 shown in the examples above, that capacitor generally constituting a first electrical component. This means that the assembly 23 of contact pins and intermediate holder 9 comprises at least one contact pin.

The solder paste and the electrically conducting glue are examples of electrically conducting compounds; in the examples above any suitable electrically conducting compound may be used .