Electrical devices

Abstract

One aspect of the invention relates to an electrical device comprising an electronic block (2) comprising a heat transfer surface (22) and a connection surface (20), an external connector (21) comprising a connector body (210) comprising a base extending from the connection surface (20). The electrical device (1) further comprises a sealing layer (3) predominantly comprising a polydimethylsiloxane-based elastomer and covering the connection surface (20) by surrounding and being in contact with at least part of the base of each connector body (210). The electrical device (1) comprises a heat transfer film (4) covering the heat transfer surface (22), having a thermal conductivity greater than or equal to 1 W / (m·K) and a hardness greater than that of the sealing layer (3), and comprising an edge (41) crosslinked with the sealing layer (3) and fibres, and a binder comprising polydimethylsiloxane.

Description

DESCRIPTION TITLE: Electrical Equipment TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of the sealing of electrical equipment.

[0002] The present invention relates to a sealed electrical equipment and a method for sealing an electronic block. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Various methods exist for sealing electrical equipment, such as encapsulating an electronic block with resin. However, this solution prevents disassembly and is therefore irreparable. Furthermore, resin encapsulation is only suitable for small electronic blocks due to its coefficient of thermal expansion. Another problem with resin encapsulation is the cooling of the electronic block, as the resin hinders efficient heat transfer from the block to the outside. While resins containing metal oxides or metal nitrides exist that improve heat transfer, their thermal resistance is directly proportional to their thickness.

[0004] It is also known that some devices include a housing containing the electronic unit, which may be metallic to improve cooling of the electronic unit, and seals at various points on the housing, particularly around the electrical connectors. However, such a housing with this type of seal is not resistant to salt spray.

[0005] Indeed, salt spray is highly corrosive to most metals and, more importantly, due to its high salt content, is electrically conductive and can cause short circuits if it penetrates the electronic connectors of equipment. While electronic boards are generally tropicalized for protection, this is obviously not possible for electrical connectors, which are not waterproof. Since salt spray is water saturated with salt, it is very fluid and can easily seep into the electronic components through capillary action, causing short circuits.

[0006] Therefore, there is a need for equipment that is resistant to salt spray while also being able to be cooled effectively. SUMMARY OF THE INVENTION

[0007] The invention offers a solution to the problems mentioned above, by encasing the equipment in an elastomer to isolate it from the external environment while having a thermal transfer layer made of a thermal interface material on a surface of the electronic block.

[0008] One aspect of the invention relates to electronic equipment comprising: an electronic block comprising at least: a first thermal transfer surface, and a second connection surface, at least one external connector projecting from the connection surface, comprising a connector body including a base extending from the connection surface, and electrical connection plugs surrounded by the connector body, a sealing layer comprising mainly a polydimethylsiloxane-based elastomer, the sealing layer comprising: a first part covering the connection surface by surrounding and being in contact with at least a part of the base of each connector body, a thermal transfer layer, covering the first thermal transfer surface, comprising an edge in contact with the sealing layer.

[0009] Thanks to the invention, the electronic block is sealed and features an efficient heat exchange surface thanks to the heat transfer layer. The heat transfer layer, in contact with the sealing layer, reduces or eliminates the risk of salt air intrusion into the electronic block. The elastomer has the particularity of easily coating surfaces during its application. The application involves sealing the connectors, particularly the base of each connector, to prevent salt spray from passing between the connector base and the electronic block's contact surface. While some elastomers contain fillers to improve heat transfer, it would be very difficult, if not impossible, to achieve a sufficiently thin sealing layer with an elastomer to provide a heat transfer coefficient equivalent to that of the thermal transfer layer. Therefore, the thermal transfer layer is thinner than the sealing layer. Furthermore, the elastomer's flexibility hinders secure attachment of the equipment to a support, especially with screws that cannot maintain the required torque when tightened against the elastomer.The thermal transfer layer allows for a very thin profile, ensuring efficient heat exchange. Its superior hardness compared to the elastomer allows for secure mounting of electrical equipment and efficient heat transfer to the substrate surface. The thermal transfer layer is also waterproof and has a higher thermal conductivity than the sealing layer.

[0010] In addition to the characteristics mentioned in the preceding paragraph, the electrical equipment according to one aspect of the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations: In one embodiment, the thermal transfer layer includes a cross-linked edge with the sealing layer. The cross-linked edge eliminates any possibility of gaps between the thermal transfer layer and the sealing layer, thus sealing the electronic block together. In one embodiment, the thermal transfer layer comprises fibers and a binder comprising polydimethylsiloxane. The thermal transfer layer and the sealing layer, predominantly comprising an elastomer containing polydimethylsiloxane, allow the highly flexible and highly adhesive elastomer to crosslink with the thin thermal transfer layer, eliminating any possibility of gaps between them. The polydimethylsiloxane crosslinks the elastomer of the sealing layer and the product of the thermal transfer layer, making them watertight against salt spray. More specifically, a sealing liquid predominantly comprising Once installed against the equipment's connection surface, the elastomer forms a liquid sealing layer with an edge. This layer, once cured, becomes the sealing layer. A heat transfer product (gel, paste, liquid, or film), forming the heat transfer layer, is applied over the initial heat transfer surface, creating a layer of heat exchanger that subsequently becomes the heat transfer layer. The liquid sealing layer and the heat exchanger layer each have an edge in contact with the other, which will cross-link together during the curing of the liquid sealing layer.We understand that the two edges crosslink, a bonding of the elastomer of the sealing layer with the thermal transfer layer by the creation of intermolecular chemical bonds in the two interfaces of the thermal transfer layer and the elastomer of the sealing layer forming a composition. As an example, the heat transfer layer has a thermal conductivity greater than or equal to 1 W / (m K). According to one embodiment, the thermal transfer layer is derived from a film (before being cross-linked). According to a variant of the previous embodiment, the heat transfer layer is derived from a layer consisting mainly of elastomer formed by a heat transfer liquid brushed onto the first heat transfer surface. According to one embodiment, the first heat transfer surface has the shape of a part of a cylindrical surface or a cylindrical surface. According to a variant of the previous embodiment, the first heat transfer surface has the shape of a portion of a spherical surface and According to another variant of these two previous embodiments, the first heat transfer surface has the shape of a part of a flat surface or a flat surface. According to one embodiment, the second connecting surface has the shape of a part of a cylindrical surface or a cylindrical surface. According to a variant of the previous embodiment, the second connecting surface has the shape of a part of a spherical surface and According to another variant of these two previous embodiments, the second connecting surface has the shape of a part of a flat surface or a flat surface. According to one embodiment, the first heat transfer surface is smooth. By smooth, we mean that it does not have any protrusions visible to the naked eye. According to one embodiment, the electronic block further comprises, in addition to the first surface and the second surface, at least one other surface, each other surface being coated by the sealing layer; This makes it possible to prevent a gap between the elastomer and a wall of the electronic block and thus to have a seal against salt spray. In one embodiment, the binder further comprises mainly silicone filled with metal oxide or nitride, and the fibers are arranged in a mesh. The mesh increases the hardness of the heat transfer layer, and the binder filler increases the heat transfer coefficient. The fibers are coated with a binder containing polydimethylsiloxane. The fibers are, for example, carbon fibers or glass fibers. According to one embodiment, the thermal transfer layer has a thickness between 0.1 and 0.5mm; According to one embodiment, the sealing layer comprises a Young's modulus E such that E < 0.1 GPa and a hardness between 20 shore OO and 70 shore 00; According to one embodiment, the thermal transfer layer includes at least one hole, and the electronic block includes at least one mounting tab including a hole opposite the hole in the thermal transfer layer to receive a screw.

[0011] Another aspect of the invention relates to a method for manufacturing electronic equipment according to the aspect of the previous invention, with or without the various examples described above, the method comprising: A step of supplying a mold comprising a fixing wall including an internal surface corresponding to the first heat transfer surface, a portion of the internal surface having a chemical property non-reactive with polydimethylsiloxane, a step of supplying a heat transfer layer corresponding to the heat transfer surface of the electronic block, a step of fixing the electronic block to the first mold wall by sandwiching the heat transfer layer between the first heat transfer surface and the internal surface, a step of injecting a sealing liquid comprising mainly elastomer including the materials of the sealing layer onto the connection surface of the electronic block in the mold, forming a first assembly,the sealing liquid flowing over the connection surface until it reaches the edge of the heat transfer layer and completely covers the connection surface, being in contact with at least part of the base of each connector body; a step of crosslinking a liquid sealing layer formed by the sealing liquid on the connection surface of the electronic block into a sealing layer; and a step of demolding the electronic equipment.

[0012] By non-reactive, we mean that the materials do not have the chemical properties to crosslink by chemical reaction.

[0013] As an example, the curing step of the liquid sealing layer is carried out by heating the electronic assembly to a temperature between 90°C and 150°C for a predetermined period, for example, five minutes at 150°C and one hundred minutes at 90°C at ambient atmospheric pressure. The curing temperature depends on the elastomer.

[0014] According to one variant, the crosslinking step of the liquid sealing layer is carried out at room temperature, for example for 24 hours at ambient atmospheric pressure.

[0015] For example, the step of supplying the thermal transfer layer includes a substep of positioning the thermal transfer layer on the mold wall opposite the thermal transfer surface of the electronic block. This is simpler to perform in the case of a mold assembled wall by wall. It will then remain on the thermal transfer surface of the electronic block. This step is even simpler when the thermal transfer layer is a film.

[0016] According to one embodiment of the process: the block comprises at least one molding wall corresponding to another surface of the electronic block, the fixing wall and at least one contiguous molding wall having at least one part of an internal surface not having a chemical crosslinking property with polydimethylsiloxane and each internal surface of a molding wall is separated from a surface of the electronic block, during the injection step of the liquid sealing layer, flows inside the mold between each other surface of the electronic block and each internal surface of each molding wall, during the crosslinking step, each edge of the thermal transfer layer in contact with the liquid sealing layer in the mold crosslinks with the layer comprising mainly elastomer.

[0017] According to one embodiment, the entire internal surface of the mold fixing wall is devoid of a chemical crosslinking property with polydimethylsiloxane.

[0018] According to one embodiment, the process further comprises: a step of coating a mold block by molding wall with an interface film between the mold block and the sealing layer, based on polyvinyl chloride on each internal surface of each block, forming the internal surface of each molding wall of the mold devoid of a chemical crosslinking property with polydimethylsiloxane, and The demolding stage includes a sub-step of dismantling the mold blocks and then a sub-step of removing the polyvinyl chloride-based films remaining on each part of the sealing layer.

[0019] An interface film, based on polyvinyl chloride (PVC), is a film flexible enough to wrap a wall. For example, the interface film has a thickness between 10 and 15 µm. Such a PVC film lacks chemical crosslinking properties with PDMS; its thickness of 10 to 15 µm provides the flexibility to peel easily while serving as an interface between the sealing layer and the mold. The interface film can be made of polyvinyl chloride.

[0020] According to one embodiment: the mold is formed by molding walls, each molding wall being removable from one another and a single fixing wall being fixed to the other contiguous molding walls, the electronic block being fixed only to the fixing wall, the method further includes a step of mounting each wall of the mold around the block including the step of fixing the fixing wall, the fixing by first fixing each contiguous molding wall to the fixing wall one after the other, then to each other, and then to each other covering each of the other faces of the electronic block.

[0021] According to an example, the sub-step of fixing one of the walls to the fixing wall is a bottom wall opposite the back surface and in that each other wall is fixed to the bottom wall.

[0022] According to one example, the fixing can be achieved by a screw passing through a hole in one wall and butting against its external surface and a tapping in the other wall coupled to the screw.

[0023] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0024] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0025] [Fig. 1] represents a schematic diagram of an electrical equipment according to an embodiment of the invention.

[0026] [Fig. 2] represents a schematic diagram of an electronic block of the electrical equipment in Figure 1.

[0027] [Fig. 3] represents a schematic diagram of a mold wall before and after coating with an interface film, based on Polyvinyl Chloride.

[0028] [Fig. 4] represents a schematic diagram of an assembly comprising an electronic block, a mold wall and a thermal transfer layer before assembly.

[0029] [Fig. 5] represents a schematic diagram of the whole of figure 4 assembled.

[0030] [Fig. 6] represents a schematic diagram of the whole of figure 5 with the entire mold.

[0031] [Fig. 7] represents a schematic diagram of the whole of figure 6 with a sealing layer.

[0032] [Fig. 8] represents a schematic diagram of the whole of figure 7, without two walls of the mold.

[0033] [Fig. 9] represents a schematic diagram of the whole of figure 7, without the mold. DETAILED DESCRIPTION

[0034] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0035] [Fig. 1] shows a schematic representation of an electronic equipment 1 comprising an electronic block shown alone in figure 2.

[0036] The electronic block 2 comprises a first heat transfer surface 22, a second connection surface 20. In this example, it has the shape of a parallelepiped but could have another shape, such as a half-cylinder, a cylinder, a sphere, a hemisphere, a polygon, etc. The electronic block 2 therefore comprises, in this example, a third and fourth lateral surfaces 24a, 24b, a rear surface 24c, and a bottom surface 24d. In this example, the lateral surfaces, 24a, 24b, the rear surface 24c and the bottom surface 24d are each a face of the electronic block formed by a wall of the electronic block.

[0037] In this example, the second connection surface 20 is adjacent to the first heat transfer surface 22, but the first heat transfer surface 22 could also be located opposite the second connection surface 20. In this example, the electronic block 2 has only one connection surface 20 (with protruding connectors), but it could have more than one; for example, one of the lateral surfaces 24a, 24b could be a connection surface. In this example, the electronic block 2 has only one heat transfer surface, but it could have two opposite ones.

[0038] The electronic block 2 therefore comprises walls forming the aforementioned surfaces and an internal housing containing the electronic circuit boards of the electronic block, which may be tropicalized. The electronic block 2 includes at least one external connector 21 projecting from the connection surface 20. In this case, the electronic block 2 includes seven external connectors 21, one of which is cylindrical and the others rectangular, of type DB for example.

[0039] Each external connector 21 comprises a connector body 210, in this case one for the cylindrical connector and four for DB type connectors.

[0040] Each connector body 210 includes a base extending from the connection surface 20. In this example, each connector body 210 includes a plate in contact with the connection surface 20 of the electronic block 2. Each connector body 210 further includes electrical connection plugs 211 surrounded by the connector body 210.

[0041] The electronic equipment 1 further includes a sealing layer 3 comprising mainly or predominantly by mass an elastomer based on polydimethylsiloxane. The expression "based on" means that it comprises at least 50% by mass. By predominantly by mass, it is understood that at least 50% by mass of the sealing layer is the elastomer. By predominantly, it is understood that the material has the highest percentage by mass of the compound; for example, "mainly composed of A" could mean comprising 45% by mass of A, 20% of B, and 10% of C. and 25% of D. According to one example, polydimethylsiloxane includes vinyl groups, allowing the crosslinking of a liquid sealing layer into a waterproof layer forming the sealing layer 3. The sealing layer 3 includes a first part completely covering the connection surface 20 by surrounding and being in contact with at least a part of the base of each connector body 21. In this example, the sealing layer includes a Young's modulus E such that E < 0.1 GPa and a hardness between 20 Shore 00 and 70 Shore 00.

[0042] The electronic equipment 1 further comprises a thermal transfer layer 4 covering the first thermal transfer surface 22 in contact with the sealing layer 3. The thermal transfer layer 4 has a thermal conductivity greater than that of the sealing layer and, in this example, has a thermal conductivity greater than or equal to 1 W / (m K). The thermal transfer layer also has, for example, a greater hardness than the sealing layer 3. In this example, the thermal transfer layer 4 includes an edge 41 cross-linked with the sealing layer 3. The thermal transfer layer 4 optionally comprises fibers. The fibers can be, for example, glass fibers or carbon fibers. In one example, the thermal transfer layer 4 is a thermal blanket (thickness > 0.5 mm) subjected to a fixed compression pressure on the thermal transfer surface 22.

[0043] The thermal layer also includes a binder comprising polydimethylsiloxane coating the fibers. A close-up of the corner between edge 41 and sealing layer 3 is shown. A weld 43, schematically represented, is formed by the crosslinking between the thermal transfer layer 4 and sealing layer 3. This crosslinking prevents the formation of a gap between the thermal transfer layer 4 and sealing layer 3. The thermal transfer layer 4 can, for example, be a film applied to the thermal surface, which is crosslinked with the sealing layer 3. The thermal transfer layer 4 can also be a gel or a thermal paste.

[0044] In this embodiment, all lateral surfaces, 24a, 24b, the rear surface 24c, and the bottom surface 24d are covered by the sealing layer 3. The binder of the thermal transfer layer 4 is also waterproof; in this example, it mainly comprises silicone filled with metal oxide or nitride. In this example, the fibers of the thermal transfer layer 4 are arranged in a grid pattern. The thermal transfer layer 4 has a thickness between 0.1 and 0.5mm.

[0045] As can be seen, the electronic block 2 includes two mounting tabs 28a, 28b, each comprising a hole 26a, 26b, in this case through and smooth (not tapped) opening onto the first heat transfer surface 22 and onto an opposite face of the corresponding mounting tab 28a, 28b.

[0046] Furthermore, the wall of the electronic block forming the first heat transfer surface 22 includes two mounting holes 26c, 26d, smooth or threaded. In another example, the wall includes a mounting base set in an external recess of the wall, comprising a surface forming part of the first internal surface, the base including the mounting holes. The base can simply be placed in position and then held in place by the sealing layer and / or the heat transfer layer. In the case of a smooth hole, screws are first inserted into the wall and held against rotation by an internal surface of the wall, allowing the screw to pass through a smooth hole in another wall (mold or heat exchanger) to secure them with a nut.

[0047] Each tapped hole 26c, 26d is aligned along an edge with the corresponding through hole 26b, 26a, allowing, in particular, the attachment of a heat exchanger to press one surface of the heat exchanger against the heat exchange surface 22 for optimal heat transfer between them. For example, the screws 6a, 6b, 6c, 6d shown in Figure 3 can be used to attach the heat exchanger.

[0048] The thermal transfer layer 4, as seen in Figure 3, therefore includes in this example a through hole 46a, 46b at the level of the fixing tabs 28a, 28b, opposite the hole 28a, 28b of the corresponding fixing tab 28a, 28b, as well as holes 46c, 46d opposite the holes 56c, 56d allowing screws 6c, 6d to be fixed there.

[0049] In this example, the fixing tabs 28a, 28b are covered by the sealing layer 3 but they may not be.

[0050] The manufacturing process of electronic equipment 1 will now be described.

[0051] The process includes a step of supplying a mold 5 comprising a fixing wall 52a and at least one molding wall, here in this case the recurrence of molding walls 54a, 54b, 54c, 54d.

[0052] In this example, the mold 5 is formed by four molding walls 54a, 54b, 54c, 54d, which are detachable from one another, and a single fixing wall 52a that is fixed to the other contiguous molding walls 54a, 54b, 54c. Among the four molding walls 54a, 54b, 54c, 54d: the first is a bottom wall 54c, opposite the connecting surface 20, comprising an internal surface pressed against the rear flank of the fixing wall 52a, Two of the walls contiguous to the fixing wall 52a are respectively a first side wall 54a and a second side wall 54b, and the last molding wall, opposite the fixing wall is called in this example the opposite wall 54d.

[0053] In this example, the electronic block 2 is fixed only to the mounting wall 52a.

[0054] In this case, as shown in Figure 5, each screw 6a, 6b, whose head abuts against the corresponding fixing lug 28a, 28b, passes through the hole 26a, 26b and the corresponding hole 46a, 46b and is screwed into the corresponding tapped hole 56a, 56b in the fixing wall 52a. According to another example, each screw 6a, 6b abuts against the external surface of the fixing wall 52a, and passes through the hole 56a, 56b by being screwed into the corresponding tapped hole 26a, 26b in the fixing lug 28a, 28b.

[0055] Each screw 6c, 6d passes through the corresponding hole 56c, 56d in the mounting wall 52a and is screwed into the corresponding tapped hole 26c, 26d. The mounting wall 52a and each molding wall 54a, 54b, 54c, 54d each have at least one portion of an internal surface 520 having a chemical property that prevents crosslinking with polydimethylsiloxane. In this example, the electronic block 2 is housed in the mold 5, as seen in Figure 6, such that only the connection surface 20 is visible through an opening in the mold 5.

[0056] The fixing wall 52a and each molding wall 54a, 54b, 54c, 54d have an external surface opposite the internal surface 520 and flanks connecting the internal surface to the external surface.

[0057] The fixing wall 52 includes in this example tapped holes 565 opening onto each side flank and tapped holes not shown opening onto the rear flank not shown.

[0058] In this example, the surfaces of the mold walls 54a, 54b, 54c, and 54d of the mold 5, and all the surfaces of the retaining wall 52a, do not have a chemical property that allows them to crosslink with polydimethylsiloxane. In this example, each wall 54a, 54b, 54c, 54d, and 52a of the mold 5 comprises a block 52, the retaining wall 52a being shown in Figure 3, for example, a metallic block covered with an interface film 7, represented in Figure 3 by a roll of film, which in this case is based on polyvinyl chloride (PVC). The interface film 7 provides an interface between the mold block and the sealing layer 3 to prevent tearing of the sealing layer bonded to the mold block during its removal.The process may therefore include a step of coating each mold block with interface film 7, based on polyvinyl chloride, either on the inner face only or, as in this example, on each inner surface of each block by wrapping it with interface film 7. Interface film 7 lacks a chemical crosslinking property with polydimethylsiloxane. Preferably, interface film 7 has a thickness between 10 and 15 µm, giving it sufficient flexibility to easily detach from the sealing layer 3, as explained later, while tearing or peeling during mold removal. Interface film 7 thus forms an interface between the sealing layer and the mold for removal. Interface film 7 may be made entirely of polyvinyl chloride.

[0059] The process further includes a step of supplying the thermal transfer layer 4, here in this case a film, corresponding to the thermal transfer surface of the electronic block 2 and a step of fixing the electronic block 2 to the fixing wall 52a of the mold 5 by sandwiching the thermal transfer layer 4 as shown in Figure 4 before fixing and in Figure 5 once the fixing wall 52a of the mold 5 has been fixed to the electronic block 2 by means of screws 6a, 6b, 6c, 6d to fix and compress the thermal transfer layer 4 between the fixing wall 52a of the mold 5 and the electronic block 2.

[0060] The process in this example further includes a step of mounting each other wall 54a, 54b, 54c, 54d of the mold 5 around the electronic block 2 comprising a substep of fixing at least one of the walls 54a, 54b, 54c, 54d to the fixing wall 52a, then the other walls 54a, 54b, 54c, 54d, to at least one of the fixed walls 54a, 54b, 54c, 54d, each covering the other faces of the electronic block 2.

[0061] In this example, the substep of fixing one of the walls 54a, 54b, 54c, 54d, to the fixing wall 52a is the bottom molding wall 54c opposite the back surface 24c and in that each wall 54a, 54b, 54d, is then fixed to the bottom wall 54c.

[0062] Figure 8 shows, in particular, smooth through holes 552, each of which is traversed by a screw (not shown) with its head abutting an external surface of the bottom wall 54c. Each screw is screwed into a tapped hole on a rear side of the fixing wall 52a, or into a tapped hole on a rear side of the corresponding first and second side walls 54a, 54b, or into a tapped hole on a rear side of the opposite wall 54d. This ensures that the mold walls 54a, 54b, 54d, and 52a are pressed against the surface of the bottom wall 54c to prevent leakage of the sealing liquid, which forms the sealing layer on the connection surface once cured.

[0063] Optionally, in this example, the first and second side walls 54a, 54b (in this case, only the first side wall 54a is shown with this option) include through holes through which screws 65 pass, screwed into the tapped holes 565 in the side flank of the fixing wall 52a and into a side flank of the opposite wall 54d. This prevents leakage of the liquid sealant layer by ensuring a seal between each molding wall. The advantage of such a mold with multiple removable walls is that it facilitates demolding by dismantling wall by wall to avoid breaking down the sealant layer into several layers and, optionally, the application of a mold block-sealant layer interface film, based on polyvinyl chloride, as explained later.

[0064] The assembly order for the molding walls is therefore: the fixing wall 52a to block 2, then for example the bottom wall 54c to the fixing wall, then the other molding walls afterwards.

[0065] For example the order then is: the second side wall 54b to the bottom wall 54c and optionally to the fixing wall 52a, then the opposite wall 54d of the mold 5 to the bottom wall 54c then possibly to the second side wall 54b and finally the first side wall 54a to the bottom wall 54c, and optionally to the fixing wall 52a and to the opposite wall 54d.

[0066] The process then includes an injection step of a sealing liquid comprising mainly polydimethylsiloxane based elastomer, comprising the materials of the sealing layer on the connection surface 20 of the electronic block 2 housed in the mold 5, forming a first assembly 6.

[0067] In this example, the mold walls 54a, 54b, 54c, 54d are slightly offset from the surfaces of the electronic block 2, allowing the sealing fluid to flow between them. Thus, during this injection step, the mold 5 and the electronic block 2 are oriented such that the third mold wall 54c, visible in Figure 8, covers the back surface 24c of the block 2 and rests on the ground. By gravity, the sealing fluid then enters the gaps between the mold walls 54a, 54b, 54c, 54d and the surfaces 24a, 24b, 24c, 24d of the electronic block 2, which they cover.

[0068] The sealing liquid thus flows over the connection surface 20 until it comes against the edge 41 of the thermal transfer layer 4 until it completely covers the connection surface 20. The sealing liquid also comes into contact with the base of each connector body 210, here in this case by covering each plate in contact with the connection surface 20 of the electronic block 2. The sealing liquid forms a liquid sealing layer on each surface, including the connection surface 20, by covering it.

[0069] The process further includes a step of crosslinking the liquid sealant layer into a sealant layer 3. Once the sealant liquid has crosslinked (cured) into a sealant layer 3, the electronic block 2, the layer sealing layer 3 and thermal transfer layer 4 together form electronic equipment 1.

[0070] The crosslinking step can be carried out by heating the first assembly 6 to a temperature between 90 and 150°C for a predetermined period, for example 5 minutes at 150°C or, for example, at least 1 hour and 40 minutes at 90°C at ambient atmospheric pressure. The temperature and time (pressure) depend on the characteristics of the elastomer.

[0071] Following the example of the thermal transfer layer 4 comprising an edge crosslinked with the sealing layer 3, this crosslinking step further crosslinks the liquid sealing layer / sealing layer 3 with the edge 41 of the thermal transfer layer 4 in contact with the liquid sealing layer in the mold 5. This makes it possible to make it airtight against salt air without gaps between the two layers.

[0072] Finally, the process includes a demolding step for the electronic equipment 1. This demolding step involves disassembling each wall block 52 of the mold 5 from the others. Specifically, during this disassembly step, the interface film 7 tears or peels away, leaving a portion covering the mold block 52, while some or all of the internal surface of this block remains bonded to the sealing layer 3 or the heat transfer layer 4.For example, as shown in Figure 8, the blocks of the first molding side wall 54a and the fixing wall 52a were disassembled, leaving on the one hand a remnant of interface film 7 bonded against the sealing layer 3 of the side face 24a, together forming a covered sealing layer 37, and on the other hand a remnant of interface film 7 bonded against the thermal transfer layer 4, here a film, together forming a covered thermal transfer film 47. In this example, the thermal transfer film was bonded to the fixing wall 52a and therefore to the film 7 covering the block 52 of the fixing wall 52a, but it could not be bonded; in this case, the fixing wall 52a can be detached without tearing the interface film 7 or only at the weld zone between the sealing layer and the thermal transfer film.

[0073] Once the sub-step of dismantling the blocks has been completed, in this example the demolded assembly includes electrical equipment 1 and the block interface film. mold-sealing layer on each sealing layer 3 as seen in Figure 9, since the latter have each adhered to the sealing layer 3 when the liquid sealing layer has crosslinked.

[0074] The demolding step in this example includes a sub-step of removing each remnant of the mold block-sealing layer interface film, based on Polyvinyl Chloride, remaining bonded to the sealing layer 3 after the demolding step, in order to obtain the electrical equipment such as that in Figure 1. Here in this case, this demolding step also includes a sub-step of removing the remnant of the interface film 7 bonded against the thermal transfer layer 4.

[0075] Electronic equipment 1 comprises electronic components (e.g., transistors, resistors, capacitors, electronic chips, microcontrollers, etc.) within the electronic block. These electronic components can be electrically connected via circuits (e.g., PCB boards, traces, electrical conductors, etc.) to form aeronautical or space-related electronic equipment 1 (e.g., a very high voltage converter, or a standalone control module, etc.).

[0076] Unless otherwise specified, the same element appearing on different figures has a unique reference.

Claims

DEMANDS

1. Electronic equipment (1) comprising: - an electronic block (2) comprising at least: o a first thermal transfer surface (22), and o a second connection surface (20), o at least one external connector (21) projecting from the connection surface (20), comprising a connector body (210) comprising a base extending from the connection surface (20), and - a sealing layer (3) comprising mainly an elastomer, based on polydimethylsiloxane, the sealing layer (3) comprising a first part covering the connection surface (20) by surrounding and being in contact with at least a part of the base of each connector body (210), - a thermal transfer layer (4) covering the first thermal transfer surface (22), in contact with the sealing layer (3).

2. Electronic equipment according to the preceding claim, wherein the heat transfer layer comprises an edge (41) crosslinked with the sealing layer (3).

3. Electronic equipment according to claim 1 or 2, wherein the thermal transfer layer (4) comprises fibers and a binder, the binder comprising polydimethylsiloxane, the fibers being coated with the binder.

4. Electronic equipment according to the preceding claim, wherein the binder further comprises predominantly silicone loaded with metal oxide or nitride and the fibers are arranged in a weft.

5. Electronic equipment according to any one of the preceding claims, wherein the heat transfer layer (4) is derived from a heat transfer film.

6. Electronic equipment according to any one of the preceding claims, wherein the heat transfer layer has a higher hardness than the sealing layer (3),

7. Electronic equipment according to any one of the preceding claims, wherein the heat transfer layer (4) has a thermal conductivity greater than or equal to 1W / (mK).

8. Electronic equipment according to any one of the preceding claims, the electronic block (2) comprises, in addition to the first surface (20) and the second surface (22), at least one other surface (24a, 24b, 24c, 24d), each other surface (24a, 24b, 24c, 24d) being totally enclosed by the sealing layer (3).

9. Electronic equipment according to any one of the preceding claims, wherein the heat transfer layer (4) has a thickness between 0.1 and 0.5mm.

10. Electronic equipment according to any one of the preceding claims, wherein the sealing layer comprises a Young's modulus E such that E < 0.1 GPa and a hardness between 20 shore OO and 70 shore 00.

11. Electronic equipment according to any one of the preceding claims, wherein the thermal transfer layer (4) includes at least one hole, and the electronic block (2) includes at least one mounting tab (28) comprising a hole opposite the hole in the thermal transfer layer (4) for receiving a screw.

12. A method for manufacturing electronic equipment according to any one of the preceding claims, comprising: - a step of supplying a mold (5) comprising a fixing wall (52a) comprising an internal surface corresponding to the first heat transfer surface (22) at least a part of the internal surface (520) devoid of a chemical crosslinking property with polydimethylsiloxane, - a step of supplying a thermal transfer layer corresponding to the shape and size of the thermal transfer surface (22) of the electronic block (2), - a step of fixing the electronic block to the fixing wall (52a) of the mold (5) by sandwiching the thermal transfer layer (4) between the first thermal transfer surface and the internal surface, - a step of injecting a sealing liquid comprising the materials of the sealing layer (3) onto the connection surface (20) of the electronic block (2) in the mold (5), forming a first assembly (6), the sealing liquid flowing onto the second connection surface (20) until it comes against the edge (41) of the thermal transfer layer (4) and until it completely covers the second connection surface (20) by being in contact with at least a part of the base of each connector body (31), - a crosslinking step of a liquid sealing layer formed by the sealing liquid on the connection surface of the electronic block in a sealing layer (3), and - a demolding step for the electronic equipment.

13. A method according to the preceding claim, wherein: - the block comprises at least one molding wall (54a, 54b, 54c, 54d) corresponding to another surface of the electronic block, the fixing wall (52a) and at least one molding wall (54a, 54b, 54c, 54d) being contiguous and each having at least a part of an internal surface (520) devoid of a chemical crosslinking property with polydimethylsiloxane and each internal surface of a molding wall is separated from another surface (24a, 24b, 24c, 24d) of the electronic block (2), - during the sealing liquid injection step, flows inside the mold (5) between each other surface (24a, 24b, 24c, 24d) of the electronic block (2) and each internal surface of each molding wall (54a, 54b, 54c, 54d), during the crosslinking step, each edge (41) of the heat transfer layer (4) in contact with the gel in the mold (5) crosslinks with the gel.

14. A method according to the preceding claim, further comprising: - a step of coating a mold block (52) (5) by a mold wall (54a, 54b, 54c, 54d, 52a) of the mold (5), with a mold block-sealing layer interface film, based on Polyvinyl Chloride, on each internal surface of each block, forming the internal surface of each mold wall and the fixing wall, each lacking a chemical crosslinking property with polydimethylsiloxane, and - the demolding stage includes a sub-stage of dismantling the mold blocks and then a sub-stage of removing the Polyvinyl Chloride-based films remaining on each part of the sealing layer (3).

15. A method according to any one of the preceding claims 7 to 9, wherein: - the mold (5) is formed by molding walls (54a, 54b, 54c, 54d), each molding wall being removable from the other walls of the mold and a single fixing wall (52a) being fixed to the other contiguous molding walls, the electronic block (2) being fixed only to the fixing wall (52a), - the process further includes a step of mounting each wall of the mold around the block comprising after the step of fixing the fixing wall, the fixing of each molding wall contiguous to the fixing wall one after the other, then to each other, each covering the other faces of the electronic block.

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