EP1299907A1 - Electronic device with heat conductive encasing device - Google Patents

Electronic device with heat conductive encasing device

Info

Publication number
EP1299907A1
EP1299907A1 EP01984192A EP01984192A EP1299907A1 EP 1299907 A1 EP1299907 A1 EP 1299907A1 EP 01984192 A EP01984192 A EP 01984192A EP 01984192 A EP01984192 A EP 01984192A EP 1299907 A1 EP1299907 A1 EP 1299907A1
Authority
EP
European Patent Office
Prior art keywords
cover
encapsulant
electronic device
projections
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01984192A
Other languages
German (de)
French (fr)
Inventor
Nicolas Thales Intellectual Property GUIRAGOSSIAN
Catherine Thales Intellectual Property DUPIN
Christophe Thales Intellectual Property VENENCIE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thales SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thales SA filed Critical Thales SA
Publication of EP1299907A1 publication Critical patent/EP1299907A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/42—Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
    • H01L23/433—Auxiliary members in containers characterised by their shape, e.g. pistons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/367—Cooling facilitated by shape of device
    • H01L23/3675—Cooling facilitated by shape of device characterised by the shape of the housing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H05K1/0203—Cooling of mounted components
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings
    • H05K3/284—Applying non-metallic protective coatings for encapsulating mounted components

Definitions

  • the invention relates to the field of electronic devices with thermally conductive encapsulant making it possible to evacuate part of the energy dissipated by the electronic components contained in the electronic device.
  • the thermally conductive encapsulant generally dissipates the dissipated energy towards a thermally conductive cover also.
  • the thermally conductive encapsulant usually also allows homogenization of hot spots which are due to more localized energy dissipation at the level of certain components.
  • the thermal encapsulant is a one-piece thermal pad whose face on the component side is flat.
  • the number of components on the circuit also increases and the different components have an increasingly variable altimetry, that is to say more and more different from a component. to the other.
  • the thermal efficiency that is to say the efficiency of the evacuation from the electronic device of the energy dissipated at the level of the electronic components, of such a monobloc thermal pad with flat face on a circuit including the components is relatively variable, is reduced.
  • forced ventilation requires a fan inside or outside the electronic device, consumes energy and makes the environment of the electronic device noisy.
  • reducing or eliminating forced ventilation decreases thermal efficiency by reducing the evacuation of energy by convection.
  • An electronic device with improved thermal efficiency would be interesting because it would make it possible to reduce or eliminate forced ventilation.
  • the thermally conductive cover has bosses so as to adapt to the variable paltimetry of the components on the circuit.
  • Thermally conductive encapsulants are arranged between the embossed cover and the components.
  • Each electronic device requires a dedicated thermally conductive cover. The adaptation of a specific cover for each type of electronic device represents a high cost.
  • the invention provides an electronic device with good thermal efficiency in which good thermal conduction is ensured between the components, at the level of which the energy is dissipated, and the thermally conductive cover, at the level of which the dissipated energy is evacuated. While reducing the thickness of the air interfaces present on the path for dissipating the dissipated energy, in order to maintain the thermal conduction above a given threshold required by the particular electronic device envisaged, the invention avoids that excessive mechanical stresses are applied to the electronic components which are generally fragile as well as possibly to other fragile elements such as the soldering of the connection lugs of these components for example.
  • an electronic device comprising: a circuit on which are arranged several electronic components capable of dissipating energy; a thermally conductive cover located opposite the circuit; a thermally conductive encapsulant disposed between the circuit and the cover so as to ensure the thermal transfer, by conduction to the cover, of the energy dissipated at the level of the components; characterized in that the respective surfaces of the encapsulant and of the cover which are facing one another comprise a set of hollows and substantially complementary projections allowing the fitting of the cover and the encapsulant, and in that that games are arranged between the recesses and the projections so as on the one hand to reduce the stress exerted by the cover on the encapsulant in the direction of the circuit and on the other hand to maintain the thermal conduction between the encapsulant and the upper cover at a given conduction threshold.
  • FIG. 1 schematically shows a preferred example of an electronic device according to the invention
  • FIG. 2 schematically shows a preferred example of a thermally conductive cover of an electronic device according to the invention
  • FIG. 3 schematically shows a first preferred embodiment of an at least partial covering device of the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention
  • FIG. 4 shows schematically a second preferred embodiment of an at least partial covering device of the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention.
  • the electronic device has a circuit. Several electronic components are placed on this circuit. The electronic components dissipate, in operating mode, energy which must be evacuated, at least partially, outside the electronic device. The components are relatively fragile elements on which the stress exerted is reduced thanks to the invention.
  • the electronic device has a cover. The cover is located opposite the circuit. The cover is thermally conductive, that is to say it is sufficiently conductive to allow a substantial part of the energy dissipated at the level of the components and brought to the level of the cover, to be evacuated outside the electronic device. To bring the energy dissipated to the components at the level of the thermally conductive cover, a thermally conductive encapsulant is placed between the circuit and the thermally conductive cover.
  • the encapsulant is sufficiently thermally conductor to transfer a substantial part of the energy dissipated at the components to the hood.
  • a substantial part of the energy is a sufficiently large part of the energy so that the thermal conduction between the components and the cover is maintained above a given conduction threshold which is determined by the type of electronic device envisaged, that is to say by the type of application envisaged.
  • the circuit, the encapsulant and the cover form a stack, the layers of which are arranged substantially parallel to the mean plane of the stack.
  • the cover has a surface facing the encapsulant and the encapsulant has a surface facing the cover.
  • These respective surfaces of the encapsulant and of the cover which are opposite one another comprise a set of projections and recesses substantially complementary so as to allow the fitting of the cover and the encapsulant one in the 'other.
  • the protrusions of the cover fit into the recesses of the encapsulant while the projections of the encapsulant fit into the recesses of the cover. If the recesses and the projections were completely complementary, the fitting of the cover and of the encapsulant would be total, and there would be no play between the recesses and the projections or else the existing play would be negligible and without significant effect.
  • the size and the arrangement of the recesses and the projections are chosen so that the stress exerted by the cover on the encapsulant in the direction of the circuit is reduced.
  • This constraint is reduced compared to the case where the nesting would be total.
  • This constraint is also reduced compared to the case of the prior art, since in the prior art, the surfaces of the cover and of the encapsulant which are opposite are plane and bearing one on the other, exerting and transmitting a stress on the components at least as strong and if not stronger than in the case of a total interlocking of the recesses and the projections without play or in the presence of negligible and insufficient play to significantly reduce the stress exerted on the components.
  • the electronic device makes it possible to reduce or even eliminate the stress which is exerted on the components and which can damage them or disturb their operation.
  • This constraint is, in the prior art, induced by the crushing of the encapsulant, generally a fairly hard material having a hardness which is, for example, typically several tens of shores A, on the surface of the circuit comprising several or even many components whose Paltimetry, that is to say the height exceeding the level of the circuit, is different between the components or at least between some of them.
  • the clearances between the respective surfaces of the cover and of the encapsulant which are rather parallel to the mean plane of the layers of the stack are sufficiently great for the stress exerted by the cover on the encapsulant in the direction of the circuit to be reduced or even almost eliminated.
  • the clearances between the respective surfaces of the cover and of the encapsulant which are rather orthogonal to the mean plane of the layers of the stack are sufficiently low so that the thermal conduction between the encapsulant and the cover is maintained above the required given conduction threshold by the type of electronic device envisaged.
  • FIG. 1 schematically represents a preferred example of an electronic device according to the invention.
  • the electronic device according to the invention consists of a stack of several layers arranged parallel to the mean plane of the stack.
  • the mean plane of the stack is parallel to the direction X and orthogonal to the direction Y and to the plane of FIG. 1.
  • the thermally conductive cover 1 includes projections 2 and recesses 3, preferably rectangular, that is to say preferably of rectangular profile.
  • the thermally conductive encapsulant 4 has projections 5 and recesses 6, preferably rectangular.
  • the projections 2 and the recesses 3 of the cover 1 on the one hand and the projections 5 and the recesses 6 of the encapsulant 4 on the other hand are substantially complementary.
  • the projections 2 of the cover 1 fit together in the recesses 6 of the encapsulant 4 while the projections 5 of the encapsulant 4 fit into the recesses 3 of the cover 1.
  • the projections 2 of the cover 1 are preferably all identical to each other.
  • the recesses 3 of the cover 1 are preferably all identical to each other.
  • components 8 are arranged connected to the circuit 7 by lugs 9 for connection.
  • the lower surface 10 of the encapsulant 4, located opposite the circuit 7, has a shape which is adapted to the paltimetry of the components 8 on the circuit 7 so that, on the one hand, the stress exerted by the encapsulant 4 on the components 8 as well as of course on their connection lugs 9, is low enough not to risk damaging the components 8 and their connection lugs 9, and on the other hand that the thermal conduction between the components 8 of the circuit 7 and the encapsulant 4 is high enough not to risk excessive heating of the components 8.
  • the arrow in dotted lines represents one of the many possible paths for the evacuation of the energy dissipated at the level of one of the components 8 from circuit 7 to the thermally conductive cover 1 first through the thermally conductive encapsulant 4, then to the outside of the electronic device then.
  • games j1 and j2 are arranged along the axis Y
  • a first set j1 is disposed between the recesses 3 of the cover 1 and the projections 5 of the encapsulant 4 and a second set j2 is arranged between the recesses 6 of the encapsulant 4 and the projections 2 of the cover 1.
  • the cover 1 rests on a part of the electronic device which is not shown in FIG. 1 for reasons of simplicity.
  • the sets j1 and j2 are preferably each of the order of a millimeter.
  • the depth of the projections 2 of the cover 1, that is to say the distance between the free end of the projections 2 of the cover 1 and the outer surface 12 of the cover 1 is equal to e'2 while the thickness of the cover 1, that is to say the dimension of the cover 1 in the direction Y orthogonal to the mean plane of the cover 1, is equal to e'1.
  • a minimum contact area SC between each projection 2 of the cover 1 on the one hand and each projection 5 of the encapsulant 4 on the other hand is ensured.
  • the sum of all these contact surfaces SC is the overall contact surface SG between the cover 1 and the encapsulant 4.
  • the clearances between projections 2 of cover 1 on the one hand and projections 5 of encapsulant 4 d on the other hand, along the X axis are either zero or negligible enough not to disturb the thermal conduction, or even slightly negative to ensure a good contact surface between the cover 1 and the encapsulant 4 so as to improve thermal conduction.
  • the number of protrusions 2 of the cover 1 and of the projections 5 of the encapsulant 4, as well as of the recesses 3 of the cover 1 and of the recesses 6 of the encapsulant 4, is not critical. This number is preferably sufficiently high to ensure an overall contact surface SG sufficient to ensure the desired thermal conduction between the encapsulant 4 and the cover 1. This number is preferably sufficiently low to ensure, during the manufacture of the encapsulant preferably of moldable material which is either polymerizable or crosslinkable, a fluid flow of the material of the encapsulant by injection between the projections of a tool cover detailed later on in FIG. 3, as well as an easy demolding without risk of damage to the encapsulant 4.
  • the cover 1, the encapsulant 4 and the circuit 7 constituting the layers of a stack, the contact surfaces between recesses and projections, located opposite the components 8, are preferably not parallel to the mean plane of the layers, this is not -parallelism being especially important for the components 8 which are particularly fragile.
  • the contact surfaces SC on the one hand between the recesses 3 of the cover 1 and the projections 5 of the encapsulant 4 and on the other hand between the recesses 6 of the encapsulant 4 and the projections 2 of the cover 1 are not parallel to the mean plane of the layers of the stack which is the plane perpendicular to the axis Y. Consequently, the only contact surfaces SC between the cover 1 and the encapsulant 4 are contact surfaces SC between the projections 2 of the cover 1 and the projections 5 of the encapsulant 4.
  • the contact surfaces between recesses and projections, which are not located opposite component 8 or connection tabs 9, are preferably not parallel to the mean plane of the layers, but the stress exerted on the components 8 and on their connecting lugs 9 otherwise less risk of damaging the components 8 or their connecting lugs 9.
  • the contact surfaces between the recesses and the projections, located opposite the components 8 are orthogonal to the mean plane of the layers. The more said contact surfaces are orthogonal the better, because the lesser the stress exerted by the cover 1 on the encapsulant 4 in the direction of the circuit 7, and consequently on the components 8.
  • the contact surfaces SC are all parallel to the axis Y.
  • the projections advantageously have a rectangular profile. This is the case, for example, in the electronic device shown in FIG. 1.
  • the projections of the cover have a trapezoidal profile, the oblique sides of the trapezium forming an acute angle between them, the apex of which is in the direction of the circuit 7.
  • This type of trapezoidal profile of the projections is also suitable but is less effective than the rectangular profile, since a greater stress is exerted in the direction of the circuit 7, on the components 8 and their connection lugs 9.
  • the set of all the contact surfaces SC between recesses and projections totals an overall surface SG preferably greater than or equal to the surface of the mean plane of the cover 1.
  • the overall surface SG which is the sum of all the contact surfaces between the projections 2 of the cover 1 and the projections 5 of the encapsulant 4
  • the overall surface SG is then also greater than the surface area of the outer surface 12 of the cover 1.
  • the projections 2 of the cover 1 are preferably fins; mounting the electronic device is then easier to perform. In another embodiment, the projections 2 of the cover 1 may be pins.
  • the cover 1 also preferably includes protrusions on its outer surface which is not opposite the encapsulant 4.
  • FIG. 2 schematically represents a preferred example of a thermally conductive cover 1 of an electronic device according to the invention.
  • the thick arrows represent natural convection movements outside the electronic device.
  • projections 11 are arranged on the outer surface 12 of the cover 1 arranged projections 11.
  • the projections 11 are preferably spikes.
  • the material of the cover 1 is thermally conductive, it is preferably aluminum.
  • the outer surface 12 of the cover 1 is preferably worth at least ten centimeters in each of the directions of its plane.
  • the size of the outer surface 12 of the cover 1 is generally comparable to the size of the circuit 7.
  • the electronic device is advantageously a digital electronic card, of a size worth, for example, ten centimeters by fifteen centimeters.
  • An electronic card tray comprising several digital electronic cards according to the invention can operate with reduced forced ventilation, or even without any forced ventilation.
  • the method of manufacturing a thermally conductive encapsulant 4 for an electronic device preferably comprises a step of injecting the encapsulant 4 into a mold which comprises a tooling cover which has, on the side intended to be in contact with the encapsulant 4, projections substantially as wide and deeper than the projections 2 of the cover 1, the depth of a projection being measured with respect to a reference chosen at the level of the external surface of the tool cover, so that the second set j2 is correctly arranged during the mounting of the electronic device.
  • the tooling cover preferably has a greater thickness than the cover 1, so that the first set j1 is correctly placed during mounting the electronic device.
  • the thermally conductive encapsulant preferably has good dielectric strength.
  • the thermally conductive encapsulant is then preferably a moldable elastomer.
  • the thermally conductive encapsulant is for example from "Pelastosil” (registered trademark) RT675 from the company “WACKER” or else from “TSE 3281 G1" (registered trademark) from the company “GE Silicones”.
  • the process for manufacturing the thermally conductive encapsulant uses a mold which comprises, opposite the tooling cover, a tooling circuit similar to the circuit, and a device for at least partially covering the tooling circuit, the covering device being located between the tooling cover and the tooling circuit and being arranged so as to substantially match the shape of the tooling circuit and so as to prevent the injection of encapsulant under the components or under the tabs for connecting the components of the tooling circuit.
  • the removable nature of the electronic device, and more particularly of the encapsulant 4 is preserved, thus allowing maintenance and repair of the electronic device by authorizing access to the electronic components 8 located on the circuit 7. Two devices at least partial overlap of the tooling circuit will now be described respectively in FIGS. 3 and 4.
  • FIG. 3 schematically represents a first preferred embodiment of an at least partial covering device for the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention.
  • the mold comprises a tooling cover 21 having projections 22 and recesses 23.
  • the projections 22 of the tooling cover 21 advantageously have the same dimension as the projections 2 of the cover 1.
  • the projections 22 of the tool cover 21 have a depth greater than the depth of the projections 2 of the cover 1, to allow the creation of the second set j2, during the mounting of the electronic device according to the invention.
  • the depth is measured from the level of the outer surface 26 of the tool cover 21 and up to the free end of the projections 22 for the tool cover 21, it is equal to e2 in FIG. 3.
  • the depth is measured from the level of the outer surface 12 of the cover 1 and up to the free end of the projections 2 for the cover 1, it is equal to e'2 in FIG. 1.
  • the thickness of the tool cover 21, c ' that is to say its dimension along the axis Y orthogonal to its mean plane, which is equal to e1 in FIG. 3, is greater than the thickness of the cover 1 which is equal to e'1 in FIG. 1.
  • a tooling circuit 27 correctly profiled or a tooling circuit 27 with components 28 and connecting lugs 29 has a space 30 between the tooling circuit 27 and the components 28 which is a prohibitive zone for dismantling. Between the tooling cover 21 and the tooling circuit 27 is located a space 24 which is the area for injecting the encapsulant 4. A frame 25 closes the mold.
  • the purpose of the device 31 at least partially covering the tooling circuit 27 is to prevent the injection of encapsulant 4 into the zone 30 which is unacceptable for dismantling. If encapsulant 4 is injected into the zone 30 which is unacceptable for dismantling, the encapsulant 4 can no longer be disassembled and therefore the components 28 can no longer be repaired from the tooling circuit 27.
  • the covering device 31 preferably covers the entire tool circuit 27.
  • the covering device 31 is preferably a film with low adhesion.
  • the film 31 is for example made of polyethylene or polypropylene or of styrene. In Figure 3, the film 31 is shown in long thick dotted lines.
  • the injection of encapsulant 4 into the injection zone 24 can be carried out for example using a hole 41 and a vent 42 in the tool cover 21. After that, the tool cover 21 is removed, and thanks to the film 31 with low adhesion, the thermally conductive encapsulant 4 can be easily extracted to then be mounted in the electronic device.
  • FIG. 4 schematically represents a second preferred embodiment d 'An at least partial covering device of the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention.
  • the covering device is a heel 32 embedding the connection lugs 29 and filling the space between components 28 and circuit of tool 27, namely the zone 30 prohibitive for dismantling.
  • the material of the heel 32 is advantageously epoxy.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Cooling Or The Like Of Electrical Apparatus (AREA)
  • Casings For Electric Apparatus (AREA)

Abstract

The invention concerns the field of electronic devices with heat conductive encasing device for eliminating part of the energy dissipated by the electronic components contained in the electronic device. It consists in a device comprising: a circuit (7) whereon are arranged several electronic components (8) capable of dissipating energy; a heat conductive cover (1) located opposite the circuit (7); a heat conductive encasing device (4) arranged between the circuit (7) and the cover (1) so as to ensure heat transfer, by conduction towards the cover (1), of the energy dissipated at the components (8); the respective surfaces of the encasing device (4) and of the cover (1) which are mutually opposite comprising an assembly of substantially matching recesses (3, 6) and protrusions (2, 5) for nesting the cover (1) and the encasing device (4), and clearances (j1, j2) are provided between the recesses (3, 6) and protrusions (2, 5) so as to reduce the load exerted by the cover (1) on the encasing device (4) towards the circuit (7) and for maintaining heat conduction between the encasing device (4) and the cover (1) at a level higher than a given conduction threshold. The invention can in particular be used for digital electronic cards.

Description

DISPOSITIF ELECTRONIQUE AVEC ENCAPSULANT THERMIQUEMENT ELECTRONIC DEVICE WITH THERMALLY ENCAPSULATING
CONDUCTEURDRIVER
L'invention concerne le domaine des dispositifs électroniques avec encapsulant thermiquement conducteur permettant d'évacuer une partie de l'énergie dissipée par les composants électroniques contenus dans le dispositif électronique. L'encapsulant thermiquement conducteur évacue généralement l'énergie dissipée vers un capot thermiquement conducteur également. L'encapsulant thermiquement conducteur permet habituellement aussi une homogénéisation des points chauds qui sont dus à une dissipation de l'énergie plus localisée au niveau de certains composants.The invention relates to the field of electronic devices with thermally conductive encapsulant making it possible to evacuate part of the energy dissipated by the electronic components contained in the electronic device. The thermally conductive encapsulant generally dissipates the dissipated energy towards a thermally conductive cover also. The thermally conductive encapsulant usually also allows homogenization of hot spots which are due to more localized energy dissipation at the level of certain components.
Selon un premier art antérieur, l'encapsulant thermique est un patin thermique monobloc dont la face côté composants est plane. Or, lorsque la taille du circuit du dispositif électronique augmente, le nombre des composants sur le circuit augmente également et les différents composants présentent une altimétrie de plus en plus variable, c'est-à-dire de plus en plus différente d'un composant à l'autre. L'efficacité thermique, c'est-à-dire l'efficacité de l'évacuation hors du dispositif électronique de l'énergie dissipée au niveau des composants électroniques, d'un tel patin thermique monobloc à face plane sur un circuit dont Paltimétrie des composants est relativement variable, est réduite.According to a first prior art, the thermal encapsulant is a one-piece thermal pad whose face on the component side is flat. However, when the size of the circuit of the electronic device increases, the number of components on the circuit also increases and the different components have an increasingly variable altimetry, that is to say more and more different from a component. to the other. The thermal efficiency, that is to say the efficiency of the evacuation from the electronic device of the energy dissipated at the level of the electronic components, of such a monobloc thermal pad with flat face on a circuit including the components is relatively variable, is reduced.
Actuellement, les dispositifs électroniques dissipant beaucoup d'énergie fonctionnent généralement avec une ventilation forcée. Or, il serait intéressant de pouvoir diminuer ou supprimer cette ventilation forcée. En effet, la ventilation forcée nécessite un ventilateur dans ou en dehors du dispositif électronique, consomme de l'énergie et rend bruyant l'environnement du dispositif électronique. Mais la diminution ou la suppression de la ventilation forcée diminue l'efficacité thermique en réduisant l'évacuation d'énergie par convection. Un dispositif électronique à efficacité thermique améliorée serait intéressant car il permettrait de diminuer ou de supprimer la ventilation forcée.Currently, electronic devices that dissipate a lot of energy generally work with forced ventilation. However, it would be interesting to be able to reduce or eliminate this forced ventilation. In fact, forced ventilation requires a fan inside or outside the electronic device, consumes energy and makes the environment of the electronic device noisy. However, reducing or eliminating forced ventilation decreases thermal efficiency by reducing the evacuation of energy by convection. An electronic device with improved thermal efficiency would be interesting because it would make it possible to reduce or eliminate forced ventilation.
Selon un deuxième art antérieur, afin d'améliorer l'efficacité thermique, des drains enterrés peuvent être ajoutés au niveau du circuit du dispositif électronique. Or, il est avantageux de pouvoir améliorer l'efficacité thermique sans refaire la conception du circuit contenu dans le dispositif électronique, notamment pour un circuit déjà existant et optimisé. Selon un troisième art antérieur, le capot thermiquement conducteur comporte des bossages de manière à s'adapter à Paltimétrie variable des composants sur le circuit. Des encapsulants thermiquement conducteurs sont disposés entre le capot bossé et les composants. Chaque dispositif électronique nécessite un capot thermiquement conducteur dédié. L'adaptation d'un capot spécifique pour chaque type de dispositif électronique représente un coût élevé.According to a second prior art, in order to improve thermal efficiency, buried drains can be added at the level of the circuit of the electronic device. However, it is advantageous to be able to improve thermal efficiency without redesigning the circuit contained in the electronic device, in particular for an already existing and optimized circuit. According to a third prior art, the thermally conductive cover has bosses so as to adapt to the variable paltimetry of the components on the circuit. Thermally conductive encapsulants are arranged between the embossed cover and the components. Each electronic device requires a dedicated thermally conductive cover. The adaptation of a specific cover for each type of electronic device represents a high cost.
L'invention propose un dispositif électronique à bonne efficacité thermique dans lequel une bonne conduction thermique est assurée entre les composants, au niveau desquels l'énergie est dissipée, et le capot thermiquement conducteur, au niveau duquel l'énergie dissipée est évacuée. Tout en diminuant l'épaisseur des interfaces d'air présentes sur le chemin d'évacuation de l'énergie dissipée, afin de maintenir la conduction thermique au-dessus d'un seuil donné requis par le dispositif électronique particulier envisagé, l'invention évite que soient appliquées des contraintes mécaniques excessives sur les composants électroniques qui sont généralement fragiles ainsi qu'éventuellement sur d'autres éléments fragiles comme les soudures des pattes de connexion de ces composants par exemple.The invention provides an electronic device with good thermal efficiency in which good thermal conduction is ensured between the components, at the level of which the energy is dissipated, and the thermally conductive cover, at the level of which the dissipated energy is evacuated. While reducing the thickness of the air interfaces present on the path for dissipating the dissipated energy, in order to maintain the thermal conduction above a given threshold required by the particular electronic device envisaged, the invention avoids that excessive mechanical stresses are applied to the electronic components which are generally fragile as well as possibly to other fragile elements such as the soldering of the connection lugs of these components for example.
Selon l'invention, il est prévu un dispositif électronique comportant : un circuit sur lequel sont disposés plusieurs composants électroniques pouvant dissiper de l'énergie ; un capot thermiquement conducteur situé en regard du circuit ; un encapsulant thermiquement conducteur disposé entre le circuit et le capot de manière à assurer le transfert thermique, par conduction vers le capot, de l'énergie dissipée au niveau des composants ; caractérisé en ce que les surfaces respectives de l'encapsulant et du capot qui sont en regard l'une de l'autre comportent un ensemble de creux et de saillies substantiellement complémentaires permettant l'emboîtement du capot et de l'encapsulant, et en ce que des jeux sont disposés entre les creux et les saillies de manière à d'une part diminuer la contrainte exercée par le capot sur l'encapsulant en direction du circuit et d'autre part maintenir la conduction thermique entre l'encapsulant et le capot supérieure à un seuil de conduction donné. L'invention sera mieux comprise et d'autres particularités et avantages apparaîtront à l'aide de la description ci-après et des dessins joints, donnés à titre d'exemples, où :According to the invention, an electronic device is provided comprising: a circuit on which are arranged several electronic components capable of dissipating energy; a thermally conductive cover located opposite the circuit; a thermally conductive encapsulant disposed between the circuit and the cover so as to ensure the thermal transfer, by conduction to the cover, of the energy dissipated at the level of the components; characterized in that the respective surfaces of the encapsulant and of the cover which are facing one another comprise a set of hollows and substantially complementary projections allowing the fitting of the cover and the encapsulant, and in that that games are arranged between the recesses and the projections so as on the one hand to reduce the stress exerted by the cover on the encapsulant in the direction of the circuit and on the other hand to maintain the thermal conduction between the encapsulant and the upper cover at a given conduction threshold. The invention will be better understood and other features and advantages will become apparent from the following description and the attached drawings, given by way of examples, in which:
- la figure 1 représente schématiquement un exemple préférentiel de dispositif électronique selon l'invention ;- Figure 1 schematically shows a preferred example of an electronic device according to the invention;
- la figure 2 représente schématiquement un exemple préférentiel de capot thermiquement conducteur d'un dispositif électronique selon l'invention ;- Figure 2 schematically shows a preferred example of a thermally conductive cover of an electronic device according to the invention;
- la figure 3 représente schématiquement une première réalisation préférentielle d'un dispositif de recouvrement au moins partiel du circuit d'outillage utilisé dans un procédé préférentiel de fabrication d'un encapsulant thermiquement conducteur d'un dispositif électronique selon l'invention ;- Figure 3 schematically shows a first preferred embodiment of an at least partial covering device of the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention;
- la figure 4 représente schématiquement une deuxième réalisation préférentielle d'un dispositif de recouvrement au moins partiel du circuit d'outillage utilisé dans un procédé préférentiel de fabrication d'un encapsulant thermiquement conducteur d'un dispositif électronique selon l'invention.- Figure 4 shows schematically a second preferred embodiment of an at least partial covering device of the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention.
Le dispositif électronique comporte un circuit. Sur ce circuit, sont disposés plusieurs composants électroniques. Les composants électroniques dissipent, en mode de fonctionnement, de l'énergie qui doit être évacuée, au moins partiellement, hors du dispositif électronique. Les composants sont des éléments relativement fragiles sur lesquels la contrainte exercée est diminuée grâce à l'invention. Le dispositif électronique comporte un capot. Le capot est situé en regard du circuit. Le capot est thermiquement conducteur, c'est-à-dire qu'il est suffisamment conducteur pour permettre à une partie substantielle de l'énergie dissipée au niveau des composants et amenée au niveau du capot, d'être évacuée à l'extérieur du dispositif électronique. Pour amener au niveau du capot thermiquement conducteur l'énergie dissipée au niveau des composants, un encapsulant thermiquement conducteur est disposé entre le circuit et le capot thermiquement conducteur. Ainsi, le transfert thermique par conduction vers le capot, d'une partie substantielle de l'énergie dissipée au niveau des composants, est assuré. L'encapsulant est suffisamment thermiquement conducteur pour assurer le transfert d'une partie substantielle de l'énergie dissipée au niveau des composants vers le capot. Une partie substantielle de l'énergie est une partie suffisamment importante de l'énergie pour que la conduction thermique entre les composants et le capot soit maintenue au- dessus d'un seuil de conduction donné lequel est déterminé par le type de dispositif électronique envisagé, c'est-à-dire par le type d'application envisagée. Le circuit, l'encapsulant et le capot forment un empilement dont les couches sont disposées sensiblement parallèlement au plan moyen de l'empilement. Le capot a une surface en regard de l'encapsulant et l'encapsulant a une surface en regard du capot. Ces surfaces respectives de l'encapsulant et du capot qui sont en regard l'une de l'autre comportent un ensemble de saillies et de creux substantiellement complémentaires de manière à permettre l'emboîtement du capot et de l'encapsulant l'un dans l'autre. Les saillies du capot s'emboîtent dans les creux de l'encapsulant tandis que les saillies de l'encapsulant s'emboîtent dans les creux du capot. Si les creux et les saillies étaient totalement complémentaires, l'emboîtement du capot et de l'encapsulant serait total, et il n'existerait pas de jeux entre les creux et les saillies ou bien les jeux existants seraient négligeables et sans effet notable. Or, la taille et la disposition des creux et des saillies sont choisies de manière à ce que la contrainte exercée par le capot sur l'encapsulant en direction du circuit soit diminuée. Cette contrainte est diminuée par rapport au cas où l'emboîtement serait total. Cette contrainte est également diminuée par rapport au cas de l'art antérieur, puisque dans l'art antérieur, les surfaces du capot et de l'encapsulant qui sont en regard sont planes et en appui l'une sur l'autre, exerçant et transmettant une contrainte sur les composants au moins aussi forte et sinon plus forte que dans le cas d'un emboîtement total des creux et des saillies sans jeu ou en présence de jeux négligeables et insuffisants pour diminuer sensiblement la contrainte exercée sur les composants.The electronic device has a circuit. Several electronic components are placed on this circuit. The electronic components dissipate, in operating mode, energy which must be evacuated, at least partially, outside the electronic device. The components are relatively fragile elements on which the stress exerted is reduced thanks to the invention. The electronic device has a cover. The cover is located opposite the circuit. The cover is thermally conductive, that is to say it is sufficiently conductive to allow a substantial part of the energy dissipated at the level of the components and brought to the level of the cover, to be evacuated outside the electronic device. To bring the energy dissipated to the components at the level of the thermally conductive cover, a thermally conductive encapsulant is placed between the circuit and the thermally conductive cover. Thus, the thermal transfer by conduction to the cover, of a substantial part of the energy dissipated at the level of the components, is ensured. The encapsulant is sufficiently thermally conductor to transfer a substantial part of the energy dissipated at the components to the hood. A substantial part of the energy is a sufficiently large part of the energy so that the thermal conduction between the components and the cover is maintained above a given conduction threshold which is determined by the type of electronic device envisaged, that is to say by the type of application envisaged. The circuit, the encapsulant and the cover form a stack, the layers of which are arranged substantially parallel to the mean plane of the stack. The cover has a surface facing the encapsulant and the encapsulant has a surface facing the cover. These respective surfaces of the encapsulant and of the cover which are opposite one another comprise a set of projections and recesses substantially complementary so as to allow the fitting of the cover and the encapsulant one in the 'other. The protrusions of the cover fit into the recesses of the encapsulant while the projections of the encapsulant fit into the recesses of the cover. If the recesses and the projections were completely complementary, the fitting of the cover and of the encapsulant would be total, and there would be no play between the recesses and the projections or else the existing play would be negligible and without significant effect. However, the size and the arrangement of the recesses and the projections are chosen so that the stress exerted by the cover on the encapsulant in the direction of the circuit is reduced. This constraint is reduced compared to the case where the nesting would be total. This constraint is also reduced compared to the case of the prior art, since in the prior art, the surfaces of the cover and of the encapsulant which are opposite are plane and bearing one on the other, exerting and transmitting a stress on the components at least as strong and if not stronger than in the case of a total interlocking of the recesses and the projections without play or in the presence of negligible and insufficient play to significantly reduce the stress exerted on the components.
Le dispositif électronique selon l'invention permet de diminuer ou même de supprimer la contrainte qui s'exerce sur les composants et qui peut les abîmer ou perturber leur fonctionnement. Cette contrainte est, dans l'art antérieur, induite par l'écrasement de l'encapsulant, généralement un matériau assez dur ayant une dureté valant par exemple typiquement plusieurs dizaines de shores A, sur la surface du circuit comportant plusieurs voire beaucoup de composants dont Paltimétrie, c'est-à-dire la hauteur dépassant du niveau du circuit, est différente entre les composants ou au moins entre certains d'entre eux. Lors de la mise en mécanique du dispositif électronique, c'est-à-dire lors de son montage, les contraintes qui auraient du être exercées sur le circuit par le capot par l'intermédiaire de l'encapsulant, sont diminuées car elles ont été absorbées au moins partiellement par les jeux disposés entre les creux et les saillies. Ces jeux sont également disposés de manière à ne pas trop réduire la conduction thermique entre l'encapsulant et le capot, voire même à l'augmenter dans certaines réalisations préférentielles, et en tout état de cause à maintenir la conduction thermique entre l'encapsulant et le capot supérieure à un seuil de conduction donné requis par le type de dispositif électronique envisagé, c'est-à-dire par le type d'application envisagée. Les jeux entre les surfaces respectives du capot et de l'encapsulant qui sont plutôt parallèles au plan moyen des couches de l'empilement sont suffisamment importants pour que la contrainte exercée par le capot sur l'encapsulant en direction du circuit soit diminuée voire quasiment supprimée. Les jeux entre les surfaces respectives du capot et de l'encapsulant qui sont plutôt orthogonales au plan moyen des couches de l'empilement sont suffisamment faibles pour que la conduction thermique entre l'encapsulant et le capot soit maintenue supérieure au seuil de conduction donné requis par le type de dispositif électronique envisagé.The electronic device according to the invention makes it possible to reduce or even eliminate the stress which is exerted on the components and which can damage them or disturb their operation. This constraint is, in the prior art, induced by the crushing of the encapsulant, generally a fairly hard material having a hardness which is, for example, typically several tens of shores A, on the surface of the circuit comprising several or even many components whose Paltimetry, that is to say the height exceeding the level of the circuit, is different between the components or at least between some of them. When the electronic device is put into mechanics, that is to say during its assembly, the stresses which should have been exerted on the circuit by the cover by means of the encapsulant, are reduced because they have been absorbed at least partially by the clearances arranged between the recesses and the projections. These clearances are also arranged so as not to reduce the thermal conduction between the encapsulant and the cover too much, or even to increase it in certain preferred embodiments, and in any event to maintain the thermal conduction between the encapsulant and the cover above a given conduction threshold required by the type of electronic device envisaged, that is to say by the type of application envisaged. The clearances between the respective surfaces of the cover and of the encapsulant which are rather parallel to the mean plane of the layers of the stack are sufficiently great for the stress exerted by the cover on the encapsulant in the direction of the circuit to be reduced or even almost eliminated. . The clearances between the respective surfaces of the cover and of the encapsulant which are rather orthogonal to the mean plane of the layers of the stack are sufficiently low so that the thermal conduction between the encapsulant and the cover is maintained above the required given conduction threshold by the type of electronic device envisaged.
La figure 1 représente schématiquement un exemple préférentiel de dispositif électronique selon l'invention. Le dispositif électronique selon l'invention se compose d'un empilement de plusieurs couches disposées parallèlement au plan moyen de l'empilement. Le plan moyen de l'empilement est parallèle à la direction X et orthogonal à la direction Y et au plan de la figure 1. Parmi les couches de l'empilement se trouvent le capot 1 , l'encapsulant 4 et le circuit 7. Le capot 1 thermiquement conducteur comporte des saillies 2 et des creux 3, préférentiellement rectangulaires, c'est-à-dire de profil préférentiellement rectangulaire. L'encapsulant 4 thermiquement conducteur comporte des saillies 5 et des creux 6, préférentiellement rectangulaires. Les saillies 2 et les creux 3 du capot 1 d'une part et les saillies 5 et les creux 6 de l'encapsulant 4 d'autre part sont substantiellement complémentaires. Les saillies 2 du capot 1 s'emboîtent dans les creux 6 de l'encapsulant 4 tandis que les saillies 5 de l'encapsulant 4 s'emboîtent dans les creux 3 du capot 1. Les saillies 2 du capot 1 sont de préférence toutes identiques entre elles. Les creux 3 du capot 1 sont de préférence tous identiques entre eux. Sur le circuit 7, sont disposés des composants 8 reliés au circuit 7 par des pattes 9 de connexion. La surface inférieure 10 de l'encapsulant 4, située en regard du circuit 7, a une forme qui est adaptée à Paltimétrie des composants 8 sur le circuit 7 de manière à ce que, d'une part la contrainte exercée par l'encapsulant 4 sur les composants 8 ainsi que bien sûr sur leurs pattes de connexion 9, soit suffisamment faible pour ne pas risquer d'endommager les composants 8 et leurs pattes 9 de connexion, et d'autre part que la conduction thermique entre les composants 8 du circuit 7 et l'encapsulant 4 soit suffisamment élevée pour ne risquer un échauffement excessif des composants 8. La flèche en traits pointillé représente l'un des nombreux chemins possibles pour l'évacuation de l'énergie dissipée au niveau de l'un des composants 8 du circuit 7 vers le capot 1 thermiquement conducteur d'abord au travers de l'encapsulant 4 thermiquement conducteur, puis vers l'extérieur du dispositif électronique ensuite.FIG. 1 schematically represents a preferred example of an electronic device according to the invention. The electronic device according to the invention consists of a stack of several layers arranged parallel to the mean plane of the stack. The mean plane of the stack is parallel to the direction X and orthogonal to the direction Y and to the plane of FIG. 1. Among the layers of the stack are the cover 1, the encapsulant 4 and the circuit 7. The thermally conductive cover 1 includes projections 2 and recesses 3, preferably rectangular, that is to say preferably of rectangular profile. The thermally conductive encapsulant 4 has projections 5 and recesses 6, preferably rectangular. The projections 2 and the recesses 3 of the cover 1 on the one hand and the projections 5 and the recesses 6 of the encapsulant 4 on the other hand are substantially complementary. The projections 2 of the cover 1 fit together in the recesses 6 of the encapsulant 4 while the projections 5 of the encapsulant 4 fit into the recesses 3 of the cover 1. The projections 2 of the cover 1 are preferably all identical to each other. The recesses 3 of the cover 1 are preferably all identical to each other. On the circuit 7, components 8 are arranged connected to the circuit 7 by lugs 9 for connection. The lower surface 10 of the encapsulant 4, located opposite the circuit 7, has a shape which is adapted to the paltimetry of the components 8 on the circuit 7 so that, on the one hand, the stress exerted by the encapsulant 4 on the components 8 as well as of course on their connection lugs 9, is low enough not to risk damaging the components 8 and their connection lugs 9, and on the other hand that the thermal conduction between the components 8 of the circuit 7 and the encapsulant 4 is high enough not to risk excessive heating of the components 8. The arrow in dotted lines represents one of the many possible paths for the evacuation of the energy dissipated at the level of one of the components 8 from circuit 7 to the thermally conductive cover 1 first through the thermally conductive encapsulant 4, then to the outside of the electronic device then.
De manière à diminuer la contrainte exercée par le capot 1 sur l'encapsulant 4 en direction du circuit 7, et plus particulièrement sur les composants 8 et leurs pattes 9 de connexion, des jeux j1 et j2 sont disposés le long de l'axe Y. Un premier jeu j1 est disposé entre les creux 3 du capot 1 et les saillies 5 de l'encapsulant 4 et un deuxième jeu j2 est disposé entre les creux 6 de l'encapsulant 4 et les saillies 2 du capot 1. Le capot 1 repose sur une partie du dispositif électronique qui n'est pas représentée sur la figure 1 pour des raisons de simplicité. Dans un exemple numérique préférentiel, les jeux j1 et j2 sont de préférence chacun de l'ordre du millimètre. La profondeur des saillies 2 du capot 1 , c'est-à-dire la distance entre l'extrémité libre des saillies 2 du capot 1 et la surface extérieure 12 du capot 1 vaut e'2 tandis que l'épaisseur du capot 1 , c'est dire la dimension du capot 1 suivant la direction Y orthogonale au plan moyen du capot 1 , vaut e'1. Le capot d'outillage, détaillé ultérieurement au niveau de la figure 3, aura de préférence une épaisseur valant e1=e'1+j1 et la profondeur de ses saillies vaudra avantageusement e2=e'2+j2. De manière à maintenir la conduction thermique entre l'encapsulant 4 et le capot 1 supérieure à un seuil de conduction donné requis par le type de dispositif électronique envisagé, une surface de contact SC minimum entre chaque saillie 2 du capot 1 d'une part et chaque saillie 5 de l'encapsulant 4 d'autre part est assurée. La somme de toutes ces surfaces SC de contact est la surface globale SG de contact entre le capot 1 et l'encapsulant 4. De préférence, les jeux entre saillies 2 du capot 1 d'une part et saillies 5 de l'encapsulant 4 d'autre part, suivant l'axe X, sont, soit nuls, soit suffisamment négligeables pour ne pas perturber la conduction thermique, soit même faiblement négatifs pour assurer une bonne surface de contact entre le capot 1 et l'encapsulant 4 de manière à améliorer la conduction thermique.In order to reduce the stress exerted by the cover 1 on the encapsulant 4 in the direction of the circuit 7, and more particularly on the components 8 and their connection lugs 9, games j1 and j2 are arranged along the axis Y A first set j1 is disposed between the recesses 3 of the cover 1 and the projections 5 of the encapsulant 4 and a second set j2 is arranged between the recesses 6 of the encapsulant 4 and the projections 2 of the cover 1. The cover 1 rests on a part of the electronic device which is not shown in FIG. 1 for reasons of simplicity. In a preferred numerical example, the sets j1 and j2 are preferably each of the order of a millimeter. The depth of the projections 2 of the cover 1, that is to say the distance between the free end of the projections 2 of the cover 1 and the outer surface 12 of the cover 1 is equal to e'2 while the thickness of the cover 1, that is to say the dimension of the cover 1 in the direction Y orthogonal to the mean plane of the cover 1, is equal to e'1. The tooling cover, detailed later in FIG. 3, will preferably have a thickness equal to e1 = e'1 + j1 and the depth of its projections will advantageously be worth e2 = e'2 + j2. In order to maintain the thermal conduction between the encapsulant 4 and the cover 1 above a given conduction threshold required by the type of electronic device envisaged, a minimum contact area SC between each projection 2 of the cover 1 on the one hand and each projection 5 of the encapsulant 4 on the other hand is ensured. The sum of all these contact surfaces SC is the overall contact surface SG between the cover 1 and the encapsulant 4. Preferably, the clearances between projections 2 of cover 1 on the one hand and projections 5 of encapsulant 4 d on the other hand, along the X axis, are either zero or negligible enough not to disturb the thermal conduction, or even slightly negative to ensure a good contact surface between the cover 1 and the encapsulant 4 so as to improve thermal conduction.
Le nombre des saillies 2 du capot 1 et des saillies 5 de l'encapsulant 4, ainsi que des creux 3 du capot 1 et des creux 6 de l'encapusulant 4, n'est pas critique. Ce nombre est préférentiellement suffisamment élevé pour assurer une surface globale SG de contact suffisante pour assurer la conduction thermique voulue entre l'encapsulant 4 et le capot 1. Ce nombre est préférentiellement suffisamment faible pour assurer, lors de la fabrication de l'encapsulant de préférence en matériau moulable qui est soit polymérisable soit reticulable, un écoulement fluide du matériau de l'encapsulant par injection entre les saillies d'un capot d'outillage détaillé ultérieurement au niveau de la figure 3, ainsi qu'un démoulage aisé sans risque d'endommagement de l'encapsulant 4.The number of protrusions 2 of the cover 1 and of the projections 5 of the encapsulant 4, as well as of the recesses 3 of the cover 1 and of the recesses 6 of the encapsulant 4, is not critical. This number is preferably sufficiently high to ensure an overall contact surface SG sufficient to ensure the desired thermal conduction between the encapsulant 4 and the cover 1. This number is preferably sufficiently low to ensure, during the manufacture of the encapsulant preferably of moldable material which is either polymerizable or crosslinkable, a fluid flow of the material of the encapsulant by injection between the projections of a tool cover detailed later on in FIG. 3, as well as an easy demolding without risk of damage to the encapsulant 4.
Le capot 1 , l'encapsulant 4 et le circuit 7 constituant les couches d'un empilement, les surfaces de contact entre creux et saillies, situées en regard des composants 8, ne sont de préférence pas parallèles au plan moyen des couches, ce non-parallélisme étant surtout important pour les composants 8 qui sont particulièrement fragiles. Moins lesdites surfaces de contact sont parallèles au plan moyen des couches et mieux c'est, car moindre est la contrainte exercée par le capot 1 sur l'encapsulant 4 en direction du circuit 7, et par conséquent sur les composants 8. Par exemple dans le cas de la figure 1 où les saillies et les creux sont rectangulaires, les surfaces de contact SC d'une part entre les creux 3 du capot 1 et les saillies 5 de l'encapsulant 4 et d'autre part entre les creux 6 de l'encapsulant 4 et les saillies 2 du capot 1 ne sont pas parallèles au plan moyen des couches de l'empilement qui est le plan perpendiculaire à l'axe Y. Par conséquent les seules surfaces de contact SC entre le capot 1 et l'encapsulant 4, sont des surfaces de contact SC entre les saillies 2 du capot 1 et les saillies 5 de l'encapsulant 4. Les surfaces de contact entre creux et saillies, qui ne sont pas situées en regard de composant 8 ou de pattes de connexion 9, ne sont préférentiellement pas parallèles au plan moyen des couches, mais la contrainte exercée sur les composants 8 et sur leurs pattes 9 de connexion dans le cas contraire risque moins d'endommager les composants 8 ou leurs pattes 9 de connexion. De préférence, les surfaces de contact entre creux et saillies, situées en regard des composants 8, sont orthogonales au plan moyen des couches. Plus lesdites surfaces de contact sont orthogonales et mieux c'est, car moindre est la contrainte exercée par le capot 1 sur l'encapsulant 4 en direction du circuit 7, et par conséquent sur les composants 8. Par exemple dans le cas de la figure 1 où les saillies et les creux sont rectangulaires, les surfaces de contact SC sont toutes parallèles à l'axe Y.The cover 1, the encapsulant 4 and the circuit 7 constituting the layers of a stack, the contact surfaces between recesses and projections, located opposite the components 8, are preferably not parallel to the mean plane of the layers, this is not -parallelism being especially important for the components 8 which are particularly fragile. The less said contact surfaces are parallel to the mean plane of the layers and the better, because the lesser the stress exerted by the cover 1 on the encapsulant 4 in the direction of the circuit 7, and consequently on the components 8. For example in the case of FIG. 1 where the projections and the recesses are rectangular, the contact surfaces SC on the one hand between the recesses 3 of the cover 1 and the projections 5 of the encapsulant 4 and on the other hand between the recesses 6 of the encapsulant 4 and the projections 2 of the cover 1 are not parallel to the mean plane of the layers of the stack which is the plane perpendicular to the axis Y. Consequently, the only contact surfaces SC between the cover 1 and the encapsulant 4 are contact surfaces SC between the projections 2 of the cover 1 and the projections 5 of the encapsulant 4. The contact surfaces between recesses and projections, which are not located opposite component 8 or connection tabs 9, are preferably not parallel to the mean plane of the layers, but the stress exerted on the components 8 and on their connecting lugs 9 otherwise less risk of damaging the components 8 or their connecting lugs 9. Preferably, the contact surfaces between the recesses and the projections, located opposite the components 8, are orthogonal to the mean plane of the layers. The more said contact surfaces are orthogonal the better, because the lesser the stress exerted by the cover 1 on the encapsulant 4 in the direction of the circuit 7, and consequently on the components 8. For example in the case of the figure 1 where the projections and the recesses are rectangular, the contact surfaces SC are all parallel to the axis Y.
Dans un plan de coupe orthogonal au plan moyen des couches, les saillies ont avantageusement un profil rectangulaire. C'est le cas par exemple dans le dispositif électronique représenté sur la figure 1. Dans un autre mode de réalisation, dans un plan de coupe orthogonal au plan moyen des couches, les saillies du capot ont un profil trapézoïdal, les côtés obliques du trapèze formant entre eux un angle aigu dont le sommet est en direction du circuit 7. Ce type de profil en trapèze des saillies convient également mais est moins efficace que le profil rectangulaire, car une contrainte plus importante s'exerce alors en direction du circuit 7, sur les composants 8 et leurs pattes 9 de connexion.In a section plane orthogonal to the mean plane of the layers, the projections advantageously have a rectangular profile. This is the case, for example, in the electronic device shown in FIG. 1. In another embodiment, in a section plane orthogonal to the mean plane of the layers, the projections of the cover have a trapezoidal profile, the oblique sides of the trapezium forming an acute angle between them, the apex of which is in the direction of the circuit 7. This type of trapezoidal profile of the projections is also suitable but is less effective than the rectangular profile, since a greater stress is exerted in the direction of the circuit 7, on the components 8 and their connection lugs 9.
L'ensemble de toutes les surfaces de contact SC entre creux et saillies totalise une surface globale SG de préférence supérieure ou égale à la surface du plan moyen du capot 1. Par exemple, dans la figure 1 , la surface globale SG qui est la somme de toutes les surfaces de contact entre les saillies 2 du capot 1 et les saillies 5 de l'encapsulant 4, est supérieure à la surface de l'interface qu'il y aurait entre le capot 1 et l'encapsulant 4 si les surfaces respectivement en regard du capot 1 et de l'encapsulant 4 étaient planes et ne comportaient ni creux ni saillies. La surface globale SG est alors également supérieure à la superficie de la surface extérieure 12 du capot 1.The set of all the contact surfaces SC between recesses and projections totals an overall surface SG preferably greater than or equal to the surface of the mean plane of the cover 1. For example, in FIG. 1, the overall surface SG which is the sum of all the contact surfaces between the projections 2 of the cover 1 and the projections 5 of the encapsulant 4, is greater than the surface of the interface that there would be between the cover 1 and the encapsulant 4 if the surfaces respectively opposite the cover 1 and the encapsulant 4 were flat and had neither recesses nor projections. The overall surface SG is then also greater than the surface area of the outer surface 12 of the cover 1.
Dans un mode de réalisation, les saillies 2 du capot 1 sont de préférence des ailettes ; le montage du dispositif électronique est alors plus facile à réaliser. Dans un autre mode de réalisation, les saillies 2 du capot 1 peuvent être des picots.In one embodiment, the projections 2 of the cover 1 are preferably fins; mounting the electronic device is then easier to perform. In another embodiment, the projections 2 of the cover 1 may be pins.
Le capot 1 comporte également préférentiellement des saillies sur sa surface extérieure qui n'est pas en regard de l'encapsulant 4. La figure 2 représente schématiquement un exemple préférentiel de capot 1 thermiquement conducteur d'un dispositif électronique selon l'invention. Les flèches épaisses représentent des mouvements de convection naturelle à l'extérieur du dispositif électronique. Sur la surface extérieure 12 du capot 1 sont disposées des saillies 11. Les saillies 11 sont de préférence des picots. Le matériau du capot 1 est thermiquement conducteur, c'est préférentiellement de l'aluminium.The cover 1 also preferably includes protrusions on its outer surface which is not opposite the encapsulant 4. FIG. 2 schematically represents a preferred example of a thermally conductive cover 1 of an electronic device according to the invention. The thick arrows represent natural convection movements outside the electronic device. On the outer surface 12 of the cover 1 are arranged projections 11. The projections 11 are preferably spikes. The material of the cover 1 is thermally conductive, it is preferably aluminum.
La surface extérieure 12 du capot 1 vaut préférentiellement au moins dix centimètres dans chacune des directions de son plan. La taille de la surface extérieure 12 du capot 1 est généralement comparable à la taille du circuit 7. Le dispositif électronique est avantageusement une carte électronique numérique, d'une taille valant par exemple une dizaine de centimètres sur une quinzaine de centimètres. Un bac à cartes électroniques comportant plusieurs cartes électroniques numériques selon l'invention peut fonctionner avec une ventilation forcée réduite, voire même sans aucune ventilation forcée. Le procédé de fabrication d'un encapsulant 4 thermiquement conducteur pour dispositif électronique selon l'invention comporte préférentiellement une étape d'injection de l'encapsulant 4 dans un moule qui comprend un capot d'outillage lequel présente, du côté destiné à être en contact avec l'encapsulant 4, des saillies sensiblement aussi larges et plus profondes que les saillies 2 du capot 1 , la profondeur d'une saillie étant mesurée par rapport à une référence choisie au niveau de la surface extérieure du capot d'outillage, de manière à ce que le deuxième jeu j2 soit correctement disposé lors du montage du dispositif électronique. Le capot d'outillage présente de préférence une épaisseur plus importante que le capot 1 , de manière à ce que le premier jeu j1 soit correctement disposé lors du montage du dispositif électronique. L'encapsulant thermiquement conducteur possède préférentiellement une bonne rigidité diélectrique. L'encapsulant thermiquement conducteur est alors de préférence un élastomère moulable. L'encapsulant thermiquement conducteur est par exemple de « Pelastosil » (marque déposée) RT675 de la société « WACKER » ou bien du « TSE 3281 G1 » (marque déposée) de la société « GE Silicones ».The outer surface 12 of the cover 1 is preferably worth at least ten centimeters in each of the directions of its plane. The size of the outer surface 12 of the cover 1 is generally comparable to the size of the circuit 7. The electronic device is advantageously a digital electronic card, of a size worth, for example, ten centimeters by fifteen centimeters. An electronic card tray comprising several digital electronic cards according to the invention can operate with reduced forced ventilation, or even without any forced ventilation. The method of manufacturing a thermally conductive encapsulant 4 for an electronic device according to the invention preferably comprises a step of injecting the encapsulant 4 into a mold which comprises a tooling cover which has, on the side intended to be in contact with the encapsulant 4, projections substantially as wide and deeper than the projections 2 of the cover 1, the depth of a projection being measured with respect to a reference chosen at the level of the external surface of the tool cover, so that the second set j2 is correctly arranged during the mounting of the electronic device. The tooling cover preferably has a greater thickness than the cover 1, so that the first set j1 is correctly placed during mounting the electronic device. The thermally conductive encapsulant preferably has good dielectric strength. The thermally conductive encapsulant is then preferably a moldable elastomer. The thermally conductive encapsulant is for example from "Pelastosil" (registered trademark) RT675 from the company "WACKER" or else from "TSE 3281 G1" (registered trademark) from the company "GE Silicones".
De préférence, le procédé de fabrication de l'encapsulant thermiquement conducteur utilise un moule qui comprend, en regard du capot d'outillage un circuit d'outillage semblable au circuit, et un dispositif de recouvrement au moins partiel du circuit d'outillage, le dispositif de recouvrement étant situé entre le capot d'outillage et le circuit d'outillage et étant disposé de manière à épouser sensiblement la forme du circuit d'outillage et de manière à empêcher l'injection d'encapsulant sous les composants ou sous les pattes de connexion des composants du circuit d'outillage. Ainsi, le caractère démontable du dispositif électronique, et plus particulièrement de l'encapsulant 4, est conservé, permettant ainsi l'entretien et la réparation du dispositif électronique en autorisant l'accession aux composants électroniques 8 situés sur le circuit 7. Deux dispositifs de recouvrement au moins partiel du circuit d'outillage vont maintenant être décrits respectivement au niveau des figures 3 et 4.Preferably, the process for manufacturing the thermally conductive encapsulant uses a mold which comprises, opposite the tooling cover, a tooling circuit similar to the circuit, and a device for at least partially covering the tooling circuit, the covering device being located between the tooling cover and the tooling circuit and being arranged so as to substantially match the shape of the tooling circuit and so as to prevent the injection of encapsulant under the components or under the tabs for connecting the components of the tooling circuit. Thus, the removable nature of the electronic device, and more particularly of the encapsulant 4, is preserved, thus allowing maintenance and repair of the electronic device by authorizing access to the electronic components 8 located on the circuit 7. Two devices at least partial overlap of the tooling circuit will now be described respectively in FIGS. 3 and 4.
La figure 3 représente schématiquement une première réalisation préférentielle d'un dispositif de recouvrement au moins partiel du circuit d'outillage utilisé dans un procédé préférentiel de fabrication d'un encapsulant thermiquement conducteur d'un dispositif électronique selon l'invention. Le moule comporte un capot d'outillage 21 présentant des saillies 22 et des creux 23. Dans la direction X, les saillies 22 du capot d'outillage 21 ont avantageusement la même dimension que les saillies 2 du capot 1. Dans la direction Y, les saillies 22 du capot d'outillage 21 ont une profondeur supérieure à la profondeur des saillies 2 du capot 1 , pour permettre la création du deuxième jeu j2, lors du montage du dispositif électronique selon l'invention. La profondeur est mesurée à partir du niveau de la surface extérieure 26 du capot d'outillage 21 et jusqu'à l'extrémité libre des saillies 22 pour le capot d'outillage 21 , elle vaut e2 sur la figure 3. La profondeur est mesurée à partir du niveau de la surface extérieure 12 du capot 1 et jusqu'à l'extrémité libre des saillies 2 pour le capot 1 , elle vaut e'2 sur la figure 1. Pour que le premier jeu j1 soit correctement positionné lors du montage du dispositif électronique, l'épaisseur du capot d'outillage 21 , c'est-à-dire sa dimension suivant l'axe Y orthogonal à son plan moyen, qui vaut e1 sur la figure 3, est supérieure à l'épaisseur du capot 1 qui vaut e'1 sur la figure 1. Un circuit d'outillage 27 correctement profilé ou un circuit d'outillage 27 avec des composants 28 et des pattes 29 de connexion présente un espace 30 entre le circuit d'outillage 27 et les composants 28 qui est une zone rédhibitoire pour la démontabilité. Entre le capot d'outillage 21 et le circuit d'outillage 27 est situé un espace 24 qui est la zone d'injection de l'encapsulant 4. Un cadre 25 ferme le moule. Le but du dispositif 31 de recouvrement au moins partiel du circuit d'outillage 27 est d'empêcher l'injection d'encapsulant 4 dans la zone 30 rédhibitoire pour la démontabilité. Si de l'encapsulant 4 est injecté dans la zone 30 rédhibitoire pour la démontabilité, l'encapsulant 4 ne pourra plus être démonté et par conséquent, les composants 28 ne pourront plus être réparés du circuit d'outillage 27. Le dispositif 31 de recouvrement recouvre de préférence tout le circuit d'outillage 27. Le dispositif 31 de recouvrement est de préférence un film à faible adhérence. Le film 31 est par exemple en polyéthylène ou en polypropylène ou en styrémique. Sur la figure 3, le film 31 est représenté en longs traits pointillés épais.FIG. 3 schematically represents a first preferred embodiment of an at least partial covering device for the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention. The mold comprises a tooling cover 21 having projections 22 and recesses 23. In the direction X, the projections 22 of the tooling cover 21 advantageously have the same dimension as the projections 2 of the cover 1. In the direction Y, the projections 22 of the tool cover 21 have a depth greater than the depth of the projections 2 of the cover 1, to allow the creation of the second set j2, during the mounting of the electronic device according to the invention. The depth is measured from the level of the outer surface 26 of the tool cover 21 and up to the free end of the projections 22 for the tool cover 21, it is equal to e2 in FIG. 3. The depth is measured from the level of the outer surface 12 of the cover 1 and up to the free end of the projections 2 for the cover 1, it is equal to e'2 in FIG. 1. In order for the first set j1 to be correctly positioned during the mounting of the electronic device, the thickness of the tool cover 21, c ' that is to say its dimension along the axis Y orthogonal to its mean plane, which is equal to e1 in FIG. 3, is greater than the thickness of the cover 1 which is equal to e'1 in FIG. 1. A tooling circuit 27 correctly profiled or a tooling circuit 27 with components 28 and connecting lugs 29 has a space 30 between the tooling circuit 27 and the components 28 which is a prohibitive zone for dismantling. Between the tooling cover 21 and the tooling circuit 27 is located a space 24 which is the area for injecting the encapsulant 4. A frame 25 closes the mold. The purpose of the device 31 at least partially covering the tooling circuit 27 is to prevent the injection of encapsulant 4 into the zone 30 which is unacceptable for dismantling. If encapsulant 4 is injected into the zone 30 which is unacceptable for dismantling, the encapsulant 4 can no longer be disassembled and therefore the components 28 can no longer be repaired from the tooling circuit 27. The covering device 31 preferably covers the entire tool circuit 27. The covering device 31 is preferably a film with low adhesion. The film 31 is for example made of polyethylene or polypropylene or of styrene. In Figure 3, the film 31 is shown in long thick dotted lines.
L'injection d'encapsulant 4 dans la zone 24 d'injection peut être réalisée par exemple à l'aide d'un trou 41 et d'un évent 42 dans le capot d'outillage 21. Après quoi, le capot d'outillage 21 est retiré, et grâce au film 31 à faible adhérence, l'encapsulant 4 thermiquement conducteur peut être facilement extrait pour être ensuite monté dans le dispositif électronique.The injection of encapsulant 4 into the injection zone 24 can be carried out for example using a hole 41 and a vent 42 in the tool cover 21. After that, the tool cover 21 is removed, and thanks to the film 31 with low adhesion, the thermally conductive encapsulant 4 can be easily extracted to then be mounted in the electronic device.
L'injection d'encapsulant 4 peut aussi être réalisée par exemple en coulant directement l'encapsulant 4 dans la zone 24 d'injection par gravité selon une direction perpendiculaire au plan de la figure 3. La figure 4 représente schématiquement une deuxième réalisation préférentielle d'un dispositif de recouvrement au moins partiel du circuit d'outillage utilisé dans un procédé préférentiel de fabrication d'un encapsulant thermiquement conducteur d'un dispositif électronique selon l'invention. Le dispositif de recouvrement est un talon 32 noyant les pattes 29 de connexion et remplissant l'espace entre composants 28 et circuit d'outillage 27, à savoir la zone 30 rédhibitoire pour la démontabilité. Le matériau du talon 32 est avantageusement de l'époxy. The injection of encapsulant 4 can also be carried out for example by directly casting the encapsulant 4 into the zone 24 of gravity injection in a direction perpendicular to the plane of FIG. 3. FIG. 4 schematically represents a second preferred embodiment d 'An at least partial covering device of the tooling circuit used in a preferred method of manufacturing a thermally conductive encapsulant of an electronic device according to the invention. The covering device is a heel 32 embedding the connection lugs 29 and filling the space between components 28 and circuit of tool 27, namely the zone 30 prohibitive for dismantling. The material of the heel 32 is advantageously epoxy.

Claims

R E V E N D I C A T I O N S
1. Dispositif électronique comportant :1. Electronic device comprising:
- un circuit (7) sur lequel sont disposés plusieurs composants (8) électroniques pouvant dissiper de l'énergie ;- a circuit (7) on which are arranged several electronic components (8) capable of dissipating energy;
- un capot (1) thermiquement conducteur situé en regard du circuit- a thermally conductive cover (1) located opposite the circuit
(7) ;(7);
- un encapsulant (4) thermiquement conducteur disposé entre le circuit (7) et le capot (1) de manière à assurer le transfert thermique, par conduction vers le capot (1), de l'énergie dissipée au niveau des composants- a thermally conductive encapsulant (4) disposed between the circuit (7) and the cover (1) so as to ensure the thermal transfer, by conduction to the cover (1), of the energy dissipated at the level of the components
(8) ; caractérisé en ce que les surfaces respectives de l'encapsulant(8); characterized in that the respective surfaces of the encapsulant
(4) et du capot (1 ) qui sont en regard l'une de l'autre comportent un ensemble de creux (3, 6) et de saillies (2, 5) substantiellement complémentaires permettant l'emboîtement du capot (1) et de l'encapsulant(4) and of the cover (1) which are opposite one another include a set of hollows (3, 6) and projections (2, 5) substantially complementary allowing the fitting of the cover (1) and encapsulant
(4), et en ce que des jeux (j1 , j2) sont disposés entre les creux (3, 6) et les saillies (2, 5) de manière à d'une part diminuer la contrainte exercée par le capot (1) sur l'encapsulant (4) en direction du circuit (7) et d'autre part maintenir la conduction thermique entre l'encapsulant (4) et le capot (1) supérieure à un seuil de conduction donné.(4), and in that clearances (j1, j2) are arranged between the recesses (3, 6) and the projections (2, 5) so as on the one hand to reduce the stress exerted by the cover (1) on the encapsulant (4) in the direction of the circuit (7) and on the other hand maintain the thermal conduction between the encapsulant (4) and the cover (1) above a given conduction threshold.
2. Dispositif électronique selon la revendication 1 , caractérisé en ce que, le capot (1), l'encapsulant (4) et le circuit (7) constituant les couches d'un empilement, les surfaces de contact (SC) entre creux (3, 6) et saillies (2, 5), situées en regard des composants (8), ne sont pas parallèles au plan moyen des couches.2. Electronic device according to claim 1, characterized in that, the cover (1), the encapsulant (4) and the circuit (7) constituting the layers of a stack, the contact surfaces (SC) between recesses ( 3, 6) and projections (2, 5), located opposite the components (8), are not parallel to the mean plane of the layers.
3. Dispositif électronique selon la revendication 2, caractérisé en ce que les surfaces de contact (SC) entre creux (3, 6) et saillies (2, 5), situées en regard des composants (8), sont orthogonales au plan moyen des couches. 3. Electronic device according to claim 2, characterized in that the contact surfaces (SC) between recesses (3, 6) and projections (2, 5), located opposite the components (8), are orthogonal to the mean plane of the layers.
4, Dispositif électronique selon la revendication 3, caractérisé en ce que, dans un plan de coupe orthogonal au plan moyen des couches, les saillies (2, 5) ont un profil rectangulaire.4, electronic device according to claim 3, characterized in that, in a cutting plane orthogonal to the mean plane of the layers, the projections (2, 5) have a rectangular profile.
5. Dispositif électronique selon la revendication 2, caractérisé en ce que, dans un plan de coupe orthogonal au plan moyen des couches, les saillies (2) du capot (1) ont un profil trapézoïdal, les côtés obliques du trapèze formant entre eux un angle aigu dont le sommet est en direction du circuit (7).5. Electronic device according to claim 2, characterized in that, in a cutting plane orthogonal to the mean plane of the layers, the projections (2) of the cover (1) have a trapezoidal profile, the oblique sides of the trapezium forming between them a acute angle whose apex is in the direction of the circuit (7).
6. Dispositif électronique selon l'une quelconque des revendications 2 à 5, caractérisé en ce que l'ensemble de toutes les surfaces de contact (SC) entre creux (3, 6) et saillies (2, 5) totalise une surface globale (SG) sensiblement supérieure à la surface du plan moyen du capot (1).6. Electronic device according to any one of claims 2 to 5, characterized in that the assembly of all the contact surfaces (SC) between recesses (3, 6) and projections (2, 5) totals an overall surface ( SG) substantially greater than the surface of the mean plane of the cover (1).
7. Dispositif électronique selon l'une quelconque des revendications 1 à 6, caractérisé en ce que les saillies (2) du capot (1) sont des ailettes.7. Electronic device according to any one of claims 1 to 6, characterized in that the projections (2) of the cover (1) are fins.
8. Dispositif électronique selon l'une quelconque des revendications 1 à 6, caractérisé en ce que les saillies (2) du capot (1 ) sont des picots.8. Electronic device according to any one of claims 1 to 6, characterized in that the projections (2) of the cover (1) are pins.
9: Dispositif électronique selon l'une quelconque des revendications précédentes, caractérisé en ce que les jeux (j1 , j2) entre creux (3, 6) et saillies (2, 5) sont de l'ordre du millimètre.9: Electronic device according to any one of the preceding claims, characterized in that the clearances (j1, j2) between recesses (3, 6) and projections (2, 5) are of the order of a millimeter.
10. Dispositif électronique selon l'une quelconque des revendications précédentes, caractérisé en ce que le capot (1) comporte également des saillies (11) sur sa surface extérieure (12) qui n'est pas en regard de l'encapsulant (4).10. Electronic device according to any one of the preceding claims, characterized in that the cover (1) also has projections (11) on its outer surface (12) which is not opposite the encapsulant (4) .
11. Dispositif électronique selon l'une quelconque des revendications précédentes, caractérisé en ce que les dimensions de la surface extérieure (12) du capot (1) valent au moins dix centimètres dans chaque direction.11. Electronic device according to any one of the preceding claims, characterized in that the dimensions of the outer surface (12) of the cover (1) is worth at least ten centimeters in each direction.
12. Dispositif électronique selon l'une quelconque des revendications précédentes, caractérisé en ce que le capot (1) est en aluminium.12. Electronic device according to any one of the preceding claims, characterized in that the cover (1) is made of aluminum.
13. Dispositif électronique selon l'une quelconque des revendications précédentes, caractérisé en ce que le dispositif électronique est une carte électronique numérique.13. Electronic device according to any one of the preceding claims, characterized in that the electronic device is a digital electronic card.
14. Bac à cartes électroniques caractérisé en ce qu'il comporte plusieurs cartes électroniques numériques selon la revendication 13 et en ce qu'il n'est pas soumis à une ventilation forcée.14. Electronic card tray characterized in that it comprises several digital electronic cards according to claim 13 and in that it is not subjected to forced ventilation.
15. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur pour dispositif électronique selon l'une quelconque des revendications 1 à 13, l'encapsulant (4) thermiquement conducteur présentant des creux (6) et des saillies (5) sur sa surface destinée à être en regard du capot (1), caractérisé en ce que le procédé comporte une étape d'injection de l'encapsulant (4) dans un moule qui comprend un capot d'outillage (21) lequel présente, du côté destiné à être en contact avec l'encapsulant (4), des saillies (22) sensiblement aussi larges et plus profondes que les saillies (2) du capot (1), la profondeur (e'2, e2) d'une saillie (2, 22) étant la distance de l'extrémité libre de la saillie (2, 22) à la surface extérieure (12, 26) du capot (1) ou du capot d'outillage (21).15. A method of manufacturing a thermally conductive encapsulant (4) for an electronic device according to any one of claims 1 to 13, the thermally conductive encapsulant (4) having recesses (6) and projections (5) on its surface intended to be opposite the cover (1), characterized in that the method comprises a step of injecting the encapsulant (4) into a mold which comprises a tool cover (21) which has, on the side intended to be in contact with the encapsulant (4), projections (22) substantially as wide and deeper than the projections (2) of the cover (1), the depth (e'2, e2) of a projection (2 , 22) being the distance from the free end of the projection (2, 22) to the external surface (12, 26) of the cover (1) or of the tool cover (21).
16. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur selon la revendication 15, caractérisé en ce que l'épaisseur (e1 ), c'est-à-dire la dimension suivant la direction orthogonale (Y) à son plan moyen, du capot d'outillage (21) est supérieure à l'épaisseur (e'1) du capot (1).16. A method of manufacturing a thermally conductive encapsulant (4) according to claim 15, characterized in that the thickness (e1), that is to say the dimension in the direction orthogonal (Y) to its mean plane , of the tool cover (21) is greater than the thickness (e'1) of the cover (1).
17. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur selon l'une quelconque des revendications 15 à 16, caractérisé en ce que le moule comprend, en regard du capot d'outillage (21) un circuit d'outillage (27) semblable au circuit (7), et un dispositif de recouvrement (31 , 32) au moins partiel du circuit d'outillage (27) , le dispositif de recouvrement (31 , 32) étant situé entre le capot d'outillage (21) et le circuit d'outillage (27) et étant disposé de manière à épouser sensiblement la forme du circuit d'outillage (27) et de manière à empêcher l'injection d'encapsulant (4) sous les composants (28) ou sous les pattes (29) de connexion des composants (28) du circuit d'outillage (27).17. A method of manufacturing a thermally conductive encapsulant (4) according to any one of claims 15 to 16, characterized in that the mold comprises, opposite the tooling cover (21), a tooling circuit (27) similar to the circuit (7), and an at least partial covering device (31, 32) of the tooling circuit (27), the covering device (31, 32) being located between the tooling cover (21) and the tooling circuit (27) and being arranged so as to substantially match the shape of the tooling circuit (27 ) and so as to prevent the injection of encapsulant (4) under the components (28) or under the tabs (29) for connecting the components (28) of the tooling circuit (27).
18. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur selon la revendication 17, caractérisé en ce que le dispositif de recouvrement (32) est un talon noyant les pattes (29) de connexion et remplissant l'espace (30) entre composants (28) et circuit d'outillage (27).18. A method of manufacturing a thermally conductive encapsulant (4) according to claim 17, characterized in that the covering device (32) is a heel embedding the connection lugs (29) and filling the space (30) between components (28) and tooling circuit (27).
19. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur selon la revendication 18, caractérisé en ce que le matériau du talon (32) est de l'époxy.19. A method of manufacturing a thermally conductive encapsulant (4) according to claim 18, characterized in that the heel material (32) is epoxy.
20. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur selon la revendication 17, caractérisé en ce que le dispositif de recouvrement (31) est un film à faible adhérence.20. A method of manufacturing a thermally conductive encapsulant (4) according to claim 17, characterized in that the covering device (31) is a film with low adhesion.
21. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur selon la revendication 20, caractérisé en ce que le film (31) est en polyéthylène ou en polypropylène ou en styrémique.21. A method of manufacturing a thermally conductive encapsulant (4) according to claim 20, characterized in that the film (31) is made of polyethylene or polypropylene or styrene.
22. Procédé de fabrication d'un encapsulant (4) thermiquement conducteur pour dispositif électronique selon l'une quelconque des revendications 15 à 21 , caractérisé en ce que l'encapsulant (4) thermiquement conducteur est un élastomère moulable. 22. A method of manufacturing a thermally conductive encapsulant (4) for an electronic device according to any one of claims 15 to 21, characterized in that the thermally conductive encapsulant (4) is a moldable elastomer.
EP01984192A 2000-07-07 2001-07-06 Electronic device with heat conductive encasing device Withdrawn EP1299907A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0008916 2000-07-07
FR0008916A FR2811476B1 (en) 2000-07-07 2000-07-07 ELECTRONIC DEVICE WITH THERMALLY CONDUCTIVE ENCAPSULANT
PCT/FR2001/002187 WO2002005346A1 (en) 2000-07-07 2001-07-06 Electronic device with heat conductive encasing device

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US6924559B2 (en) 2005-08-02
FR2811476B1 (en) 2002-12-06
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US20040026798A1 (en) 2004-02-12
WO2002005346A1 (en) 2002-01-17

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