ELECTRONIC CONNECTORS FOR USE ON BOARD OF A SPACE VEHICLE

Description

Domaine technique

[0001] This disclosure relates to a connector on board a spacecraft equipped with at least one motherboard and daughter cards. Technique antérieure

[0002] In the space industry, each electronic board is held in its housing, which is attached to a thermally regulated structure of the spacecraft. When connecting electronic boards to each other, it is common to encounter a problem of misalignment of the boards, which results from variations in the dimensions of the boards, the location of the connectors, or the flatness of the electronic boards.

[0003] Printed circuit boards (PCBs) can be mounted on slides, but these limit the heat exchange surfaces and therefore the maximum heat flow achievable in a space environment. The mass of the slides is also a disadvantage of this solution.

[0004] Alternatively, it is possible, for example, to use cards formed from a so-called flexible printed circuit, also referred to as "flex" in English, i.e. a printed circuit comprising a flexible support, for example formed from a polyimide or PEEK film, on which the electrically conductive tracks are arranged.

[0005] Alternatively, a so-called semi-flexible printed circuit board, also known as "semi-flex" in English, can also be used, which is made up of a set of plates, typically made of epoxy resin, extended by films, for example polyimide.

[0006] Thus, the presence of flexible portions makes these printed circuits more complex to manufacture, therefore more expensive, but also more fragile. Moreover, in a space environment, heat dissipation is mainly done by the epoxy plates, which are placed in contact with a mechanical support allowing heat to be evacuated. Heat dissipation in a semi-flexible printed circuit is more complex to control because the heat dissipation capacities of the support films are much more limited than the heat dissipation offered by the epoxy plates. This is even more true in the space sector, where the cooling of an electronic component by convection is not exploitable. Consequently, even for so-called semi-flexible printed circuits, heat dissipation is only correctly achieved at the level of the epoxy plates.Additionally, the number of layers in a PCB laid on film is limited, which limits the number of signals and current density that these circuits can carry. Signal routing is also more complex due to the impossibility of electromagnetic shielding on the support films.

[0007] US 2011 / 0151683 discloses a computer comprising a motherboard and an expansion card where each card comprises several connectors capable of cooperating together, and the connectors of the expansion card comprise an openwork tab.

[0008] It is known from DE102010045884 a motherboard which is connected to several expansion cards via a connection board; where each card comprises a tab carrying a connector which plugs into a respective connector on the connection board. Résumé

[0009] This disclosure improves the situation.

[0010] There is provided an electronic device capable of being embarked in a spacecraft according to claim 1.

[0011] In embodiments, in each daughter card, the tab is delimited on either side of its first connector by two slots extending transversely from an edge of its plate.

[0012] In embodiments, said plate is made of epoxy resin, the main plane of the printed circuit of the motherboard being arranged perpendicular to the main planes of the printed circuits of the daughter cards.

[0013] In embodiments, each first connector comprises guide members arranged at its two ends providing guidance relative to one of the second connectors.

[0014] In embodiments, each daughter card is inserted into a metal housing, the metal housings being assembled together and fixed to a supporting structure of the spacecraft, this supporting structure being temperature regulated by a temperature regulation system.

[0015] In embodiments, each daughter card is thermally connected to its metal housing by a thermal interface.

[0016] In embodiments, the motherboard is inserted into a metal cover, being thermally connected to the cover by a thermal interface.

[0017] Another subject matter of the present invention is a spacecraft comprising an electronic device according to the foregoing description.

[0018] Another subject matter relates to a method of assembling an electronic device according to the preceding description, comprising: a step of assembling daughter cards in their respective housings, a step of mechanically assembling the housings of the daughter cards together, and a step of electrically connecting each daughter card to said motherboard, said step comprising a deflection of a tab of at least one of the daughter cards supporting a first connector cooperating with second connectors of said motherboard to adapt to the relative positions of the daughter cards and said motherboard, said first electrical connector being fixed to a support plate of the printed circuit of said daughter card, said second connectors being fixed to a support plate of the printed circuit of said motherboard, said tab of said daughter card being produced by a portion of its plate capable of being deflected relative to a main plane of its printed circuit, and a step of assembling a cover to the motherboard.

[0019] In embodiments, the assembly method further comprises assembling, to a temperature-controlled support structure of the spacecraft, the housings of the daughter cards.

[0020] Advantageously, the design of electronic assemblies each comprising at least one motherboard and daughter cards is facilitated.

[0021] Another advantage is improved thermal regulation in areas near the connections between the motherboard and daughterboards.

[0022] Another advantage is that the proposed electronic device allows the use of printed circuits arranged on epoxy plates without flexible parts, which offer advantages in terms of costs and supply. The present invention intelligently exploits the slight elasticity of epoxy plates to allow the compensation of clearances during assembly.

[0023] Advantageously, the flexibility of the tab carrying the daughter card connector can be increased by recesses, which also makes it possible to reduce the force supported by each connector. The end of the tab, in front of the recesses, can also remain solid to further reduce the forces supported by the connector pins.

[0024] Advantageously, the play compensation that the invention allows does not come at the expense of the weight of the whole. Brève description des dessins

[0025] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1 [ Fig. 1 ] shows part of a daughter card according to the invention. Fig. 2 [ Fig. 2 ] represents a connection between a motherboard and a daughter card according to the invention. Fig. 3 [ Fig. 3 ] represents the connection according to the invention shown in [ fig.2 ] according to another view. Fig. 4 [ Fig. 4 ] represents a motherboard comprising a plurality of connectors according to the invention. Fig. 5 [ Fig. 5 ] schematically represents a connection according to the invention between a motherboard and daughter cards. Fig. 6a [ Fig. 6a ] represents an example of a metal housing for supporting a daughter card. Fig. 6b [ Fig. 6b ] represents the kinematics of inserting a daughter card into its housing Fig. 7 [ Fig. 7 ] schematically represents a spacecraft comprising a temperature-regulated carrier structure. Fig. 8 [ Fig. 8 ] represents an assembly of a motherboard with a plurality of daughter cards, the daughter cards being contained in respective carrier housings. Fig. 9a [ Fig. 9a ] represents a motherboard assembled with a plurality of daughter cards contained in respective support boxes. Fig. 9b [ Fig. 9b ] represents the assembly of the figure 9a after assembling a cover on the motherboard. Description des modes de réalisation

[0026] In reference to the figures 1 à 5 , we will now describe an electronic device 1 capable of being embarked in a spacecraft, comprising at least one motherboard 2 and a plurality of daughter cards 3 electrically connected to the motherboard.

[0027] Each of the motherboard 2 and the daughter cards 3 is an electronic card comprising a substantially planar support plate 4, 5. Each support plate 4, 5 can form the support for a rigid type printed circuit or PCB for "Printed Circuit Board" in English, and be formed from an electrically insulating material, for example epoxy resin. It is possible, for example, to use a PCB of the FR4 or polyimide type. On each plate can be arranged a set of electrically conductive tracks (not shown) as well as locations and connectors (not shown) allowing electronic components to be mounted on each card and connected to each other. In the present invention, the daughter card PCBs will be deformed while remaining within the tolerances given by the manufacturer to preserve the reliability of the PCB.

[0028] In addition, each daughter card 3 comprises a connector 6 fixed to its plate 4, and the motherboard comprises a plurality of connectors referenced 7a, 7b, 7c and 7d fixed to the plate 5 of the motherboard, each connector 7 of the motherboard being adapted to cooperate mechanically and electrically with the connector referenced 6a, 6b, 6c or 6d of a respective daughter card referenced 3a, 3b, 3c or 3d in order to connect each daughter card to the motherboard. Each connector 6, 7 can be fixed to its respective plate for example by screwing.

[0029] Each connector 6, 7 may comprise mechanical guide members 60, 70 and electrical contacts 61, 71. In embodiments, the connectors extend in a main direction, the mechanical guide members and the electrical contacts being aligned in this main direction. Each connector may comprise two mechanical guide members 60a, 60b, 70a, 70b at the two ends in this main direction, the electrical contacts 61, 71 being arranged between the mechanical guide members. This is the case in the example shown in the figures, where the connectors of the daughter cards comprise female guide members capable of receiving male guide members complementary to the connectors of the motherboard. Of course, this example is in no way limiting and the opposite case can also be envisaged. It is also possible to have connectors without mechanical guides.

[0030] In reference to the figure 4 , identical connectors 7a, 7b, 7c and 7d of the motherboard are dedicated to the connection with connectors of the respective daughter cards 3a, 3b 3c and 3d. Each connector of each daughter card is for example identical. The advantageously identical connectors of the motherboard are mounted on the same face of the support plate 5 of the motherboard. These connectors 7a, 7b, 7c and 7d are further aligned parallel to each other so as to be able to connect several daughter cards to the motherboard, so that the daughter cards extend parallel to each other.

[0031] As represented in the figures 3 And 5 , the connectors 6,7 of the motherboard and the daughter cards are shaped to allow a connection between the motherboard and the daughter cards so that the plane PM of the support plate 5 of the motherboard 2 is perpendicular to the planes PFa, PFb, PFc of the support plates 4a, 4b, 4c of the daughter cards 3a, 3b, 3c. The figure 5 represents in particular each tab and, in its extension, the main plane of each daughter card. The connectors thus make a connection perpendicular to the motherboard, then two deviations in opposite directions to join the main plane, also perpendicular to the motherboard. In this respect, the connectors of the motherboard or daughter cards can be right-angled connectors, that is to say whose connection pins extend parallel to the plate on which the connector is mounted, while the other connectors are straight connectors, that is to say whose connection pins extend perpendicular to the plate on which the connector is mounted.

[0032] In order to be able to connect several daughter cards 3 to the motherboard 2 while avoiding the problems linked to the play on the dimensions of the components, the positions of the components or even the flatness of the PCBs, the plate 4 of each daughter card 3 comprises a portion forming a tab 8 capable of being deflected relative to the main plane of the support plate 4 of the card, this portion carrying the connector 6 of the daughter card. With reference to the figure 1 , the tab 8 can be delimited on either side of the connector by two slots 9a, 9b extending transversely from an edge 40 of the plate, the connector 6 itself being mounted on the plate between the slots, and preferably in the vicinity of this edge. In this way, with reference to the figure 5 , it is possible to compensate for certain clearances or misalignments by giving this portion of the plate a slight elasticity allowing the tab 8 on which the connector 6 is mounted to flex. Thus, and as shown schematically in the figure 5 , at the time of assembly of the electronic device, comprising the connection of several daughter cards 3a to 3d to the motherboard 2, it is possible to position each daughter card relative to the motherboard, and to deflect the tab 8a to 8d carrying the connector 6a to 6d of each daughter card 3a to 3d in order to connect it to a respective connector 7a to 7d of a motherboard.

[0033] The two slots 9a, 9b delimiting the tab 8 laterally are advantageously sized according to the desired deviation of the tab 8 relative to the plane of the plate. They may for example have a length of between 1 and 5 cm, this length being measured from the edge of the plate to the end of each slot. According to a non-limiting example, the two slots may have a length of 3 cm to compensate for an offset of 400 µm between an electrical connector carried by the motherboard and the corresponding connector of the daughter card.

[0034] In embodiments, the tab 8, i.e. the portion of the card between the side slots 9a, 9, may be longer than the portions of the plate located outside the slots, so as to have a tab projecting from the edge of the plate, which may allow greater ease of assembly and handling of the connectors.

[0035] The two slots 9a, 9b extending on either side of the connector may extend perpendicular to the edge 40 of the plate 4. In one embodiment, the two slots 9 may comprise a first bent portion 90 extending from the edge of the plate and going around the lateral ends of the connector, and a straight end portion 91, extending for example perpendicular to the edge of the plate. In this way, the tab has a width, between the lateral ends of the two slots, which is less than the width of the connector, which gives greater flexibility to the tab. The average width of the tab can in particular be reduced thanks to the two recesses 90 at the edge of the daughter card. The base of the tab then has a first width extending to a widened part of the tab on which its connector is fixed. In the non-limiting example shown in figure 1 , the connector comprises at its two ends two guide members 60a, 60b, and each slot comprises an end portion 91 aligned with each guide member of the connector and a bent portion 90 connecting the end portion to the edge of the plate thus forming a step.

[0036] In embodiments, the tab 8 also comprises one or more tab softening recesses 80 disposed in a middle portion of the tab. These recesses may or may not be through-recesses.

[0037] Each tab 8 comprises, for example, a plurality of through and rectilinear recesses 80 extending parallel to each other and, where appropriate, parallel to the slots delimiting the tab. The tab may nevertheless comprise, at its end located on the edge side of the plate, a solid portion 81 for supporting the connector. In this case, the softening recesses 80 of the tab 8 may extend from the solid portion 81 to the level of the ends of the slots 9a and 9b.

[0038] Maintaining a solid support portion 81 of the connector makes it possible to limit the tearing stresses applied to the electrically conductive pins of the connector arranged in this solid portion 81.

[0039] Each daughter card 3 can be inserted into a respective metal housing 30, each card being thermally connected to its respective housing by a thermal interface (not shown). With reference to the figure 6a , a daughter card and its support housing 30, also called a bowl, are shown. The housing 30 of each daughter card is shaped to allow deflection of the tab. In particular, the tab 8 is not fixed to the housing by a thermal interface. The heat generated on the card is evacuated through the PCB into the metal frame. On the figure 6b , the kinematics of insertion of the daughter card 3 into the housing 30 have been shown. The housing may in particular comprise a bottom wall 31 and a peripheral rim 32 delimiting an open cavity into which the card can be inserted. The housing 30 comprises a through-orifice 33 arranged in the peripheral rim 32 and sized to allow the insertion of the connector 6 carried by the tab 8 of a daughter card through the orifice. In a first step S1, the daughter card is therefore inserted into the housing in a position inclined relative to the plane of the bottom wall of the housing, by inserting the connector carried by the tab 8 through the orifice 33, then it is folded down S2 to extend parallel to the plane of the bottom wall of the housing. It can then be mechanically assembled to the housing 30, for example by screwing. With reference to the figure 8 , the plate 4 of a daughter card may comprise bores 41 allowing the daughter card to be screwed to the bottom wall of the housing. Thus, each daughter card is rigidly assembled to its housing but the tab 8 remains movable relative to the plane of each plate, being free to deflect slightly through the through-hole 33 of each housing. This allows the daughter cards to be assembled to the motherboard by slightly deflecting the tab carrying the connector of one or more daughter cards to correspond to the alignment of the connectors on the motherboard. Thus, errors in the positioning of the connectors of the daughter cards relative to the connector on the motherboard can be compensated.

[0040] Once each daughter card is assembled to its case, the cases are rigidly assembled together.

[0041] In reference to the figures 8 And 9a, the motherboard is then assembled to the daughterboards, by connecting each connector on the motherboard to a respective connector on a daughterboard, said connector being diverted if necessary.

[0042] In reference to the figure 9b , the motherboard 2 is assembled to a cover 20 which may be in the form of a bottom wall provided with a peripheral rim and thus forming an open cavity, this open cavity being oriented, during assembly of the card itself to the daughter cards, towards the daughter cards.

[0043] In reference to the figure 7, when the electronic device 1 is on board a spacecraft S, each housing 30 of a daughter card can itself be fixed on a supporting structure 21 of the spacecraft which can be regulated in temperature by a thermal regulation system, comprising for example a heat transfer structure comprising an evaporator 22a connected to a heat source, in this case the electronic device 1 via the supporting structure 21, and a radiator 22b located outside the spacecraft S so as to evacuate the heat towards space.

[0044] Thus, according to one embodiment, a method of assembling an electronic device according to the preceding description may further comprise fixing the housings of the daughter cards and / or the cover of the motherboard to the supporting structure 21 of the spacecraft, this supporting structure being temperature-regulated by a temperature-regulating system 22.

Claims

1. Electronic device (1) suitable for use on board a spacecraft, comprising at least one motherboard (2) electrically connected to daughterboards (3a, 3b, 3c), said motherboard (2) and said daughterboards (3) each comprising a support plate (4a, 4b, 4c, 5) in order to form a printed circuit board, each plate extending in a respective main plane, each daughterboard (3a, 3b, 3c) comprises at least one first electrical connector (6a, 6b, 6c, 6d) fixed to its plate and the motherboard comprises a corresponding number of second connectors (7a, 7b, 7c, 7d) fixed to the plate of the motherboard, each first connector (6a, 6b, 6c, 6d) engaging with one of the second connectors (7a, 7b, 7c, 7d), characterized in that said first connector (6a, 6b, 6c, 6d) of each daughterboard being arranged on a portion of the plate forming a tab (8) capable of deflection relative to the main plane of the printed circuit board, each tab (8) having at its end a solid portion (81) supporting said first connector and further comprising cavities (80) for increasing the flexibility of the tab.

2. Electronic device according to claim 1, wherein, in each daughterboard, the tab (8) is delimited on either side of its first connector by two slots (9a, 9b) extending transversely from an edge (40) of its plate.

3. Electronic device according to one of the preceding claims, wherein said plate is made of epoxy resin, the main plane of the printed circuit board of the motherboard being arranged perpendicularly to the main planes of the printed circuit boards of the daughterboards.

4. Electronic device according to one of the preceding claims, wherein each first connector (6a) comprises guide members (110) arranged at its two ends, providing guidance relative to one of the second connectors.

5. Electronic device according to one of the preceding claims, wherein each daughterboard (3) is inserted into a metal housing (30), the metal housings (30) being assembled together and fixed to a supporting structure (21) of the spacecraft, this supporting structure being temperature-regulated by a temperature regulation system (22).

6. Electronic device according to the preceding claim, wherein each daughterboard is thermally connected to its metal housing (30) via a thermal interface.

7. Electronic device according to one of the preceding claims, wherein the motherboard (2) is inserted into a metal cover (20), being thermally connected to the cover by a thermal interface.

8. Spacecraft comprising an electronic device according to one of claims 1 to 7.

9. Method for assembling an electronic device according to one of claims 1 to 7, comprising: - a step of assembling daughterboards (3) in their respective housings (30), - a step of mechanically assembling together the housings (30) of the daughterboards (3), - a step of electrically connecting each daughterboard (3) to said motherboard (2), said step comprising a deflection of a tab (8) of at least one of the daughterboards (3), said tab supporting a first connector (6a, 6b, 6c, 6d) which can engage with second connectors (7a, 7b, 7c) of said motherboard, in order to adapt to the relative positions of the daughterboards and of said motherboard, said first electrical connector (6a, 6b, 6c) being fixed to a support plate of the printed circuit board of said daughterboard, said second connectors (7a, 7b, 7c) being fixed to a support plate of the printed circuit board of said motherboard, said tab of said daughterboard being created by a portion of its plate capable of deflection relative to a main plane of its printed circuit board, and - a step of assembling a cover (20) to the motherboard.

10. Method for assembling an electronic device according to the preceding claim, further comprising the assembling of the housings of the daughterboards to a temperature-regulated supporting structure (21) of the spacecraft.