EP0637826B1 - Power resistor, with device for application under pressure on a heat sink - Google Patents

Power resistor, with device for application under pressure on a heat sink Download PDF

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Publication number
EP0637826B1
EP0637826B1 EP19940401739 EP94401739A EP0637826B1 EP 0637826 B1 EP0637826 B1 EP 0637826B1 EP 19940401739 EP19940401739 EP 19940401739 EP 94401739 A EP94401739 A EP 94401739A EP 0637826 B1 EP0637826 B1 EP 0637826B1
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EP
European Patent Office
Prior art keywords
casing
resistive element
component
heat sink
dielectric barrier
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EP19940401739
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German (de)
French (fr)
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EP0637826A1 (en
Inventor
José DUPONT
Jean-Yves Bougeard
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MCB Industrie
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MCB Industrie
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/08—Cooling, heating or ventilating arrangements
    • H01C1/084—Cooling, heating or ventilating arrangements using self-cooling, e.g. fins, heat sinks

Definitions

  • the present invention relates to resistive power components, as used in cooled power electronics systems.
  • this dielectric barrier The thickness of the materials constituting this dielectric barrier is therefore decisive.
  • the quality of the physical contact between each resistive element and this dielectric barrier plays a large role, as does the quality of the physical contact between the latter and the heat sink on which the component is to be installed.
  • the known embodiments call upon, without greatly improving the characteristics, complicated and expensive systems. Performance and reliability are often reduced in the absence of precautions taken to maintain a temperature of each resistive element, which is a heat emitting element, sufficiently low in the critical zones necessary for the low ohmic values and at the level of electrical connections of each resistive element of the component.
  • the invention aims to overcome the aforementioned drawbacks of known embodiments of resistive power components.
  • the non-deformable element advantageously has a central part, projecting towards the central zone of said upper part of the housing, and a large flat lower face resting on the resistive element or elements, and said predetermined load is a central load, exerted on said part. central of the non-deformable element through said central zone of the upper part of the housing, and distributed by said large underside of said non-deformable element.
  • the resistive component for example with a power of 200 W at 2 kW, comprises a housing 1, made of elastically insulating plastic material, which covers and laterally surrounds an internal structure 2.
  • the latter essentially comprises stacking consisting of a non-deformable element 3, electrically insulating in this example, and made of ceramic or porcelain, resting by its large flat lower face over practically the entire upper face of a resistive element 4, flat and thin, resting itself by its lower face on the large upper face of a flat dielectric barrier 5, which rests by its large opposite face or lower face, against the flat upper face of a heat sink 6, made of metal with or without circulation of heat transfer fluid, when the component is fixed on this dissipator 6 by screws such as 7, retained on the housing 1 to be “captive” by any means known for this purpose, and passing through bores 8 of opposite lateral parts of the housing 1 to be screwed into the dissipator 6.
  • the dielectric barrier 5 is laminated and comprises two superimposed layers, which may be ceramic, for example made of Al2 O3, AlN or BeO, or a mixture of these bodies, or else in a combination of these bodies with sheets of metal or alloy, for example copper or Invar, so that the dielectric barrier 5 is simultaneously electrically insulating, of excellent thermal conductivity, and of good mechanical robustness.
  • ceramic for example made of Al2 O3, AlN or BeO, or a mixture of these bodies, or else in a combination of these bodies with sheets of metal or alloy, for example copper or Invar, so that the dielectric barrier 5 is simultaneously electrically insulating, of excellent thermal conductivity, and of good mechanical robustness.
  • the resistive element 4 described below with reference to FIG. 3, comprises two connection tabs 9, each of which is electrically connected to one respectively of two terminals 10 for external connection of the component by a flexible connection element 11 , low resistivity.
  • Each terminal 10 is housed in a chimney 12 of the upper part 13 of the housing 1, and has a connection tab 14, projecting towards the inside of the housing 1, and each flexible connection element 11 is simply connected to the lugs 9 and 14 corresponding connection by electrical welding or soldering.
  • the internal structure 2 is assembled to the housing 1, and more precisely mechanically connected to the internal lateral walls of the housing 1, by a semi-rigid body or constituent 15, electrically insulating, such as a flexible synthetic resin, which strongly adheres to the structure internal 2 and to the material of the housing 1, and envelops the connections of the flexible connecting elements 11 to the connection lugs 9.
  • This component 15 is introduced into the housing 1 by a partial filling process.
  • the resistant element 4 of such a high-power resistive component gives off, when it is traversed by an electric power current, significant amounts of heat, which must be evacuated, through the dielectric barrier 5 forming a heat sink, by the dissipator 6.
  • the dielectric barrier 5 and the dissipator 6 in a heat exchange relationship as favorable as possible, the faces of the non-deformable element 3 and of the dielectric barrier 5 which must maintain good physical contact with the resistant element 4 are machined by lapping, grinding or any other process ensuring excellent overall flatness.
  • the flatness of the lower face of the dielectric barrier 5 must be good and adapted to that of the upper face of the dissipator 6 with which it must maintain good physical contact.
  • This device comprises at least one elastically deformable element 16, including an elastic deformation predetermined, when fixed on the housing 1, allows to exert a predetermined and stable load on the internal structure 2, in which the non-deformable element 3 receives this load and retransmits it, by distributing it, to the resistant element 4 and to the dielectric barrier 5, to ensure the calibrated pressurization.
  • the elastically deformable element with calibrated deformation 16 is for example made of metal or any other material which does not exhibit creep phenomenon under load. It can include or be constituted by a spring, a washer, or any other similar mechanical member.
  • this element 16 has a bar structure having at rest, as shown in broken lines 16a in Figure 4, a general shape of V very open, with two substantially symmetrical wings 17 inclined on a substantially flat central base 18 and, in the end of each wing 17, a hole for the passage of a screw 7 for fixing the element 16 on the housing 1 in its predetermined elastic deformation position, shown in solid line 16b in FIG. 4.
  • the element 16 is brought into its predetermined elastic deformation position in order to obtain the predetermined load by screwing the screws 7 into the dissipator 6 until the heads of the screws 7 abut against the wings 17 themselves in abutment against the housing 1, as shown in FIG. 1.
  • the wings 17 are flexed substantially in the extension of one another, and the central base 18 applies the predetermined load against the central zone of the upper part 13 of the housing 1.
  • the non-deformable element 3 of the internal structure 2 has a central part 20 projecting towards the housing 1, and on which the central zone of the upper part 13 of this housing bears, under which the projection 20 is centered in a rib 19 of the housing 1.
  • the screws 7 are therefore simultaneously means for fixing the resistive component by its housing 1 on the dissipator 6, and means for fixing and deformation of the elastically deformable element 16 in its predetermined elastic deformation position on the housing 1.
  • the predetermined and stable load is thus a central load, exerted by the base 18 of the deformable element 16 on the central part 20 of the non-deformable element 3 through the central zone of the upper part 13 of the housing 1.
  • the non-deformable element 3 distributes the predetermined load it receives and ensures calibrated pressurization.
  • the predetermined load self-calibrated by elastic bending
  • a pressurizing device which may include several elastically deformable elements such as 16, the number of which is adapted to a judicious distribution of the load, depending on the size of the component and characteristics requested.
  • the "captive" mounting of the screws 7 on the housing 1 simultaneously makes the elastically deformable elements 16 of the pressurizing device integral with the housing 1, even at rest, which facilitates the distribution and assembly of the component.
  • FIG. 2 differs essentially from that described above by the fact that the projecting central part 20 of the non-deformable element 3 crosses a opening in the central area of the upper part 13 of the housing 1, so that the central base 18 of the elastically deformable element 16 is applied directly against the upper face of the central part 20 of the non-deformable element 3, which is accessible outside the housing 1.
  • the predetermined load is thus directly transmitted from the elastically deformable element 16 to the non-deformable element 3.
  • the dielectric barrier 5 comprises a third layer 5a, lower, in copper for example, to improve the transmission of heat to the dissipator with which it is in contact, and which is also alement crossed by the screws 7.
  • the resistant element 4 of the components of FIGS. 1 and 2, represented in FIG. 3, is formed from a sheet or a deposit of a metallic alloy or of an electrically conductive metal and has a shape at the periphery. which allows an installation and an economic immobilization, requiring no additional accessory, for example a square or rectangular shape. Its particular structure and its particular dimensions described below are intended to obtain the required ohmic value of the component, without hot spot and with an almost zero inductance.
  • the thickness "e" of the resistant element 4 is chosen so that its mass of alloy or metal guarantees sufficient adiabatic capacity, and so that it simultaneously allows good thermal conductivity transverse to the thermal flow this thin element in its plan.
  • This element is produced by laser machining, chemical etching or by mechanical cutting from a sheet or a deposit of metal or metal alloy which may or may not have been subjected to a prior thermal expansion treatment.
  • the machining of the sheet or the rectangular deposit of the resistant element 4 consists in subdividing it, perpendicular to the two long sides of the rectangle, into parallel strips or cells 21, of a substantially constant width b, except for the two end strips 22 which have a width h greater than b.
  • These bands 21 and 22 are separated from each other by slots 23 of width a which are formed alternately from one to the other of the two long sides of the rectangle, stopping at a distance c from the other side opposite. This distance c corresponds to the width of an end zone 24 by which two adjacent strips are connected to each other.
  • the alternating slots 23 thus have a common longitudinal extension d, in perpendicular projection on the short sides of the rectangle.
  • the two connection lugs 9 are each rectangular and folded perpendicular to the plane of the rectangle of the bands 21 and 22, and each extends over the same length i along one of the two short sides of the rectangle, respectively. from one respectively of two opposite vertices, at the ends of a diagonal of the rectangle.
  • the width of the slots 23 is as small as possible so that the resistant element 4 has the largest possible surface in contact with the dielectric barrier 5, this width a remaining however of a sufficient value to ensure sufficient electrical isolation between the adjacent cells or bands 21 and 22.
  • the width b of the bands 21 and the common extension d of the slots 23 are chosen to obtain the required resistance value.
  • the width c of the end zones 24 is, as a general rule, always greater than b, so that the end zone 24 constitutes a heat sink made efficient by the transverse conduction in the thickness e of the resistive element 4.
  • these zones 25 with bottom of slot are thus arranged in the peripheral part of the resistant element 4, which is better cooled than the central part.
  • the current density is lowered, and therefore also the temperature rise, by adopting a width h of the end strips 22 at least equal to c and by choosing the length i of the connection lugs 9 such that it is greater than h.
  • This arrangement constitutes a thermal brake for the electrical connections 9 which are not trapped in the assembly receiving the calibrated pressure or predetermined mechanical load.
  • the dimensions a, b, c, d, e, h and i are chosen so as to allow heat dissipation without hot spot in the active parts of the element 4, and in particular the relationships between the dimensions c, h and i are defined so as to avoid hot spots in the outlet connections and to maintain there a temperature substantially equal to that of the active parts.
  • the faces of the non-deformable element 3 and of the dielectric barrier 5 in contact with the resistive element 4 are made conductive, by a metallic deposit of suitable resistivity, or by a transfer of a conductive sheet or of suitable resistivity. , not disturbing the ohmic value of the component, by a surface treatment achievable by different methods, such as screen printing, deposit in thin or thick layers, from a few microns to a few hundred microns. This technical measure means that the component does not exhibit the phenomenon of "partial discharges" for potentials up to at least 7 kV.
  • the resistant element 4 also has four small tabs 26, folded perpendicularly, which facilitate the positioning of the resistant element 4 under the non-deformable element 3, the lower part of which is arranged in a rectangular sole for distributing pressure on the resistant element 4, on the upper face of which the limit of influence of the non-deformable element 3 is identified by the dotted perimeter 27 in FIG. 3.
  • the shape of the dielectric barrier 5 is also rectangular.
  • planar shapes of the parts in physical contact of the deformable element 3, of the resistant element 4 and of the dielectric barrier 5 are homothetic forms.
  • the element 3 is positioned centered, on the one hand, on the element 4, by its sole received between the positioning tabs 26 of the element 4, and, on the other hand, in the housing 1, by its part protruding central 20, which is centered either in the rib 19 (fig. 1), or in the opening in the top 13 of the housing 1 (fig. 2).
  • the barrier 5 is positioned with respect to the housing 1, in the base of which it fits with limited play.
  • the shapes of elements 3 and 4 and of barrier 5, and in general of all the constituent elements of the internal structure guarantee rapid, precise and economical positioning during assembly, without it it is necessary to resort to external means such as bonding, welding, soldering or other assembly methods often generating dilatometric tension or increasing the thermal resistances of the assemblies.
  • the resistive component is therefore economically manufactured.
  • resistive component may comprise one or more resistive elements, each provided with at least two terminals or connection lugs, the resistive element or elements being able to be fitted in resistive network.

Description

La présente invention est relative aux composants résistifs de puissance, tels qu'utilisés dans les systèmes refroidis de l'électronique de puissance.The present invention relates to resistive power components, as used in cooled power electronics systems.

Ces composants sont actuellement réalisés selon plusieurs techniques, qui tentent de satisfaire aux principales contraintes antagonistes imposées, qui sont essentiellement des contraintes dimensionnelles, thermiques et électriques.These components are currently produced according to several techniques, which attempt to satisfy the main opposing constraints imposed, which are essentially dimensional, thermal and electrical constraints.

En particulier, la réduction des dimensions de ces composants, imposée dans les applications modernes, augmente la densité de chaleur émise, dans chaque composant, par le ou les éléments résistifs correspondants, qui doivent donc être isolés électriquement, mais non thermiquement. Pour cette raison. une barrière diélectrique, assurant l'isolement électrique de chaque élément résistif, doit simultanément, pour constituer un drain thermique approprié, posséder une résistance thermique la plus faible possible.In particular, the reduction in the dimensions of these components, imposed in modern applications, increases the density of heat emitted, in each component, by the corresponding resistive element or elements, which must therefore be electrically insulated, but not thermally. For this reason. a dielectric barrier, ensuring the electrical isolation of each resistive element, must simultaneously, in order to constitute an appropriate thermal drain, have the lowest possible thermal resistance.

L'épaisseur des matériaux constituant cette barrière diélectrique est donc déterminante. De plus, la qualité du contact physique entre chaque élément résistif et cette barrière diélectrique joue un grand rôle, de même que la qualité du contact physique entre cette dernière et le dissipateur thermique sur lequel le composant doit être implanté.The thickness of the materials constituting this dielectric barrier is therefore decisive. In addition, the quality of the physical contact between each resistive element and this dielectric barrier plays a large role, as does the quality of the physical contact between the latter and the heat sink on which the component is to be installed.

Les réalisations mises en oeuvre aujourd'hui, qui comportent au moins un élément résistif, par exemple métallique, sur une semelle diélectrique, l'ensemble étant monté dans un boîtier, comme connu par EP-A-0 454 904, n'apportent pas de résultats satisfaisants à ces exigences techniques, ne garantissent pas le niveau de puissance demandée, et n'assurent pas la stabilité des contacts thermiques à long terme.The embodiments implemented today, which comprise at least one resistive element, for example metallic, on a dielectric sole, the assembly being mounted in a housing, as known by EP-A-0 454 904, do not provide satisfactory results to these technical requirements, do not guarantee the level of power required, and do not ensure the stability of thermal contacts in the long term.

Dans d'autres cas, les réalisations connues font appel, sans améliorer grandement les caractéristiques, à des systèmes compliqués et coûteux. Les performances et la fiabilité se trouvent bien souvent réduites en l'absence de précautions prises pour conserver une température de chaque élément résistif, qui est un élément émetteur de chaleur, suffisamment faible dans les zones critiques nécessaires pour les faibles valeurs ohmiques et au niveau des connexions électriques de chaque élément résistif du composant.In other cases, the known embodiments call upon, without greatly improving the characteristics, complicated and expensive systems. Performance and reliability are often reduced in the absence of precautions taken to maintain a temperature of each resistive element, which is a heat emitting element, sufficiently low in the critical zones necessary for the low ohmic values and at the level of electrical connections of each resistive element of the component.

Les composants résistifs de puissance actuellement sur le marché sont l'aboutissement de transferts de technologies ne s'adaptant pas forcément aux différentes contraintes, parmi lesquelles on note plus particulièrement :

  • la finesse extrême des éléments résistifs, qui les rend difficile à mettre en oeuvre dès lors que les dimensions augmentent,
  • l'existence d'un support des éléments résistifs, ce support étant réalisé en matériaux thermiquement isolants
  • un système mécanique reliant chaque élément résistif et sa semelle au boîtier qui ne garantit pas le contact physique nécessaire à une bonne évacuation de la chaleur produite,
  • des boîtiers et matériaux non adaptés aux composants de grandes tailles, et
  • une forme inadaptée des éléments résistifs, provoquant des points chauds sur ces derniers, préjudiciables à leur durée de vie et/ou leur donnant une inductance élevée.
The resistive power components currently on the market are the result of technology transfers not necessarily adapting to the various constraints, among which we note more particularly:
  • the extreme fineness of the resistive elements, which makes them difficult to implement when the dimensions increase,
  • the existence of a support for resistive elements, this support being made of thermally insulating materials
  • a mechanical system connecting each resistive element and its sole to the housing which does not guarantee the physical contact necessary for good evacuation of the heat produced,
  • enclosures and materials not suitable for large components, and
  • an unsuitable shape of the resistive elements, causing hot spots on the latter, detrimental to their service life and / or giving them a high inductance.

L'invention vise à pallier les inconvénients précités des réalisations connues de composants résistifs de puissance.The invention aims to overcome the aforementioned drawbacks of known embodiments of resistive power components.

A cet effet, l'invention propose un composant résistif de puissance, du type connu par EP-A-0 454 904, destiné à être installé sur un dissipateur thermique, et comportant :

  • a) une structure interne, qui comprend au moins un élément résistif électriquement conducteur, plat et mince, reposant sur une barrière diélectrique sensiblement plane, électriquement isolante et à bonne conductivité thermique,
  • b) un boîtier à partie supérieure électriquement isolante, et qui loge ladite structure interne et est muni d'au moins deux bornes de connexion électrique externe du composant, dont chacune est électriquement raccordée à au moins un élément résistif par au moins un élément de liaison interne au boîtier,
  • c) des moyens de liaison mécanique de la structure interne au boîtier et
  • d) un dispositif d'application sous pression de chaque élément résistif et de la barrière diélectrique vers le dissipateur thermique, ledit dispositif d'application exerçant sur la structure interne une charge prédéterminée assurant ladite mise en pression et comprenant au moins un élément élastiquement déformable dans une mesure prédéterminée pour obtenir ladite charge prédéterminée, des moyens de retenue du ou des éléments élastiquement déformés dans ladite mesure prédéterminée par rapport au boîtier, et un élément indéformable de distribution de pression, intégré à la structure interne dans laquelle il est empilé avec le ou les éléments résistifs et la barrière diélectrique, et qui leur transmet, en la répartissant, la charge prédéterminée qu'il reçoit du ou des éléments élastiquement déformables, et qui se caractérise en ce que
    • ladite barrière diélectrique présente une face de contact destinée à reposer sur ledit dissipateur thermique lorsque le composant est installé sur ledit dissipateur,
    • ledit boîtier, entièrement électriquement isolant, enveloppe ladite structure interne, sauf au niveau de ladite face de contact de ladite barrière diélectrique avec ledit dissipateur,
    • ledit dispositif d'application sous pression applique avec une pression calibrée chaque élément résistif sur ladite barrière diélectrique et ladite barrière sur ledit dissipateur, ladite charge prédéterminée étant exercée sur ledit élément de distribution de pression, au travers de ladite partie supérieure du boîtier, par ledit ou lesdits éléments élastiquement déformables que lesdits moyens de retenue fixent sur l'extérieur de ladite partie supérieure du boîtier, et le composant comprend également des moyens de fixation du composant par son boîtier sur ledit dissipateur thermique.
To this end, the invention provides a resistive power component, of the type known by EP-A-0 454 904, intended to be installed on a heat sink, and comprising:
  • a) an internal structure, which comprises at least one electrically conductive resistive element, flat and thin, resting on a substantially planar dielectric barrier, electrically insulating and with good thermal conductivity,
  • b) a housing with an electrically insulating upper part, which houses said internal structure and is provided with at least two external electrical connection terminals of the component, each of which is electrically connected to at least one resistive element by at least one connecting element internal to the housing,
  • c) mechanical connection means of the internal structure to the housing and
  • d) a device for applying pressure of each resistive element and the dielectric barrier towards the heat sink, said application device exerting on the internal structure a predetermined load ensuring said pressurization and comprising at least one elastically deformable element in a predetermined measure for obtaining said predetermined load, means for retaining the element or elements elastically deformed in said predetermined measure with respect to the housing, and a non-deformable pressure distribution element, integrated into the internal structure in which it is stacked with the or the resistive elements and the dielectric barrier, and which transmits to them, by distributing it, the predetermined charge which it receives from the elastically deformable element or elements, and which is characterized in that
    • said dielectric barrier has a contact face intended to rest on said heat sink when the component is installed on said heat sink,
    • said case, entirely electrically insulating, envelops said internal structure, except at the level of said contact face of said dielectric barrier with said dissipator,
    • said pressure application device applies with a calibrated pressure each resistive element to said dielectric barrier and said barrier to said dissipator, said predetermined load being exerted on said pressure distribution element, through said upper part of the housing, by said one or more elastically deformable elements that said retaining means fix on the outside of said upper part of the housing, and the component also comprises means for fixing the component by its housing on said heat sink.

L'élément indéformable présente avantageusement une partie centrale, en saillie vers la zone centrale de ladite partie supérieure du boîtier, et une grande face inférieure plane reposant sur le ou les éléments résistifs, et ladite charge prédéterminée est une charge centrale, exercée sur ladite partie centrale de l'élément indéformable au travers de ladite zone centrale de la partie supérieure du boîtier, et répartie par ladite grande face inférieure dudit élément indéformable.The non-deformable element advantageously has a central part, projecting towards the central zone of said upper part of the housing, and a large flat lower face resting on the resistive element or elements, and said predetermined load is a central load, exerted on said part. central of the non-deformable element through said central zone of the upper part of the housing, and distributed by said large underside of said non-deformable element.

Dans des modes de réalisation préférés, on a recours, en outre, à l'une et/ou à l'autre des dispositions suivantes :

  • les moyens de fixation du ou des éléments élastiquement déformables sur le boîtier sont simultanément des moyens de fixation du boîtier sur le dissipateur thermique,
  • la liaison mécanique du boîtier à l'empilage constitué par l'élément indéformable, le ou les éléments résistifs et la barrière diélectrique est assurée par un constituant semi-rigide électriquement isolant, remplissant partiellement le boîtier,
  • la face de l'élément indéformable et/ou de la barrière diélectrique au contact du ou des éléments résistifs est rendue électriquement conductrice par un dépôt de résistivité appropriée ou un report d'une feuille conductrice ou de résistivité appropriée, ne perturbant pas la valeur ohmique du composant,
  • chaque élément résistif est réalisé dans une feuille d'alliage métallique ou de métal d'épaisseur choisie de sorte que sa masse lui donne une capacité adiabatique suffisante,
  • chaque élément résistif présente en plan la forme sensiblement d'un quadrilatère subdivisé, perpendiculairement à deux côtés opposés, en bandes parallèles d'une largeur sensiblement constante (b), sauf pour les deux bandes d'extrémité qui sont d'une largeur (h) supérieure à (b), les bandes étant reliées par des zones d'extrémité et séparées les unes des autres par des fentes de largeur (a) aussi faible que possible compatible avec un isolement suffisant entre les bandes, les fentes étant ménagées alternativement de l'un vers l'autre des deux côtés opposés en s'arrêtant à une distance (c) de l'autre côté opposé qui correspond à la largeur d'une zone d'extrémité, et les fentes ayant une extension longitudinale commune (d), en projection parallèle auxdits côtés opposés, l'élément résistif comportant en outre des pattes de connexion repliées par rapport au plan du quadrilatère et chacune s'étendant sur une même longueur (i) le long de l'un respectivement de deux autres côtés opposés, les distances (b) et (d) étant choisies pour obtenir la valeur ohmique déterminée du composant, la distance (c) étant supérieure à b pour constituer dans chaque zone d'extrémité un drain thermique efficace par conduction selon l'épaisseur (e) et limitant la température dans chaque zone voisine du fond d'une fente, dans la partie périphérique de l'élément résistif, la dimension (h) étant supérieure ou égale à la dimension (c) et la dimension (i) étant supérieure à h, pour limiter la température dans les zones de connexion électriques.
In preferred embodiments, use is also made of one and / or the other of the following arrangements:
  • the means for fixing the elastically deformable element or elements on the housing are simultaneously means for fixing the housing to the heat sink,
  • the mechanical connection of the housing to the stack consisting of the non-deformable element, the resistive element or elements and the dielectric barrier is ensured by an electrically insulating semi-rigid component, partially filling the housing,
  • the face of the non-deformable element and / or of the dielectric barrier in contact with the resistive element (s) is made electrically conductive by a deposit of appropriate resistivity or a transfer of a conductive sheet or of suitable resistivity, not disturbing the ohmic value component,
  • each resistive element is made of a metal alloy or metal sheet of selected thickness so that its mass gives it sufficient adiabatic capacity,
  • each resistive element has in plan form substantially a subdivided quadrilateral, perpendicular to two opposite sides, in parallel strips of substantially constant width (b), except for the two end strips which are of width (h ) greater than (b), the strips being connected by end zones and separated from each other by slots of width (a) as small as possible compatible with sufficient insulation between the strips, the slots being provided alternately of towards each other on the two opposite sides, stopping at a distance (c) from the other opposite side which corresponds to the width of an end zone, and the slots having a common longitudinal extension (d ), in projection parallel to said opposite sides, the resistive element further comprising connection tabs folded relative to the plane of the quadrilateral and each extending over the same length (i) along one resp ectively from two other opposite sides, the distances (b) and (d) being chosen to obtain the determined ohmic value of the component, the distance (c) being greater than b to constitute in each end zone a drain thermal effect by conduction according to the thickness (e) and limiting the temperature in each zone close to the bottom of a slit, in the peripheral part of the resistive element, the dimension (h) being greater than or equal to the dimension (c ) and dimension (i) being greater than h, to limit the temperature in the electrical connection areas.

D'autres avantages et caractéristiques de l'invention découlent de la description donnée ci-dessous, à titre non limitatif, d'exemples de réalisation décrits en référence aux dessins annexés sur lesquels :

  • la figure 1 est une vue schématique, en coupe transversale, d'un premier exemple de composant résistif,
  • la figure 2 est une vue analogue à la figure 1 d'un second exemple de composant résistif,
  • la figure 3 est une vue en perspective de l'élément résistif des composants des figures 1 et 2, et
  • la figure 4 est une vue schématique en élévation latérale d'un élément élastiquement déformable du dispositif de mise sous pression calibrée des composants des figures 1 et 2.
Other advantages and characteristics of the invention derive from the description given below, without implied limitation, of exemplary embodiments described with reference to the appended drawings in which:
  • FIG. 1 is a schematic view, in cross section, of a first example of a resistive component,
  • FIG. 2 is a view similar to FIG. 1 of a second example of a resistive component,
  • FIG. 3 is a perspective view of the resistive element of the components of FIGS. 1 and 2, and
  • FIG. 4 is a schematic side elevation view of an elastically deformable element of the calibrated pressurizing device of the components of FIGS. 1 and 2.

Sur la figure 1, le composant résistif, par exemple d'une puissance de 200 W à 2 kW, comprend un boîtier 1, en matière plastique élastiquement isolante, qui recouvre et entoure latéralement une structure interne 2. Cette dernière comprend essentiellement l'empilage constitué d'un élément indéformable 3, électriquement isolant dans cet exemple, et en céramique ou porcelaine, reposant par sa grande face inférieure plane sur pratiquement toute la face supérieure d'un élément résistif 4, plat et mince, reposant lui-même par sa face inférieure sur la grande face supérieure d'une barrière diélectrique 5 plane, laquelle repose par sa grande face opposée ou face inférieure, contre la face supérieure plane d'un dissipateur thermique 6, en métal avec ou sans circulation de fluide caloporteur, lorsque le composant est fixé sur ce dissipateur 6 par des vis telles que 7, retenues sur le boîtier 1 pour être "imperdables" par tous moyens connus à cet effet, et traversant des alésages 8 de parties latérales opposées du boîtier 1 pour se visser dans le dissipateur 6.In FIG. 1, the resistive component, for example with a power of 200 W at 2 kW, comprises a housing 1, made of elastically insulating plastic material, which covers and laterally surrounds an internal structure 2. The latter essentially comprises stacking consisting of a non-deformable element 3, electrically insulating in this example, and made of ceramic or porcelain, resting by its large flat lower face over practically the entire upper face of a resistive element 4, flat and thin, resting itself by its lower face on the large upper face of a flat dielectric barrier 5, which rests by its large opposite face or lower face, against the flat upper face of a heat sink 6, made of metal with or without circulation of heat transfer fluid, when the component is fixed on this dissipator 6 by screws such as 7, retained on the housing 1 to be "captive" by any means known for this purpose, and passing through bores 8 of opposite lateral parts of the housing 1 to be screwed into the dissipator 6.

Dans cet exemple, la barrière diélectrique 5 est stratifiée et comprend deux couches superposées, qui peuvent être en céramique, par exemple en Al2 O3, AlN ou BeO, ou en un mélange de ces corps, ou encore en une association de ces corps avec des feuilles de métal ou d'alliage, par exemple de cuivre ou d'Invar, de sorte que la barrière diélectrique 5 soit simultanément électriquement isolante, d'une excellente conductivité thermique, et d'une bonne robustesse mécanique.In this example, the dielectric barrier 5 is laminated and comprises two superimposed layers, which may be ceramic, for example made of Al2 O3, AlN or BeO, or a mixture of these bodies, or else in a combination of these bodies with sheets of metal or alloy, for example copper or Invar, so that the dielectric barrier 5 is simultaneously electrically insulating, of excellent thermal conductivity, and of good mechanical robustness.

L'élément résistif 4, décrit ci-dessous en référence à la figure 3, comprend deux pattes de connexion 9, dont chacune est électriquement raccordée à l'une respectivement de deux bornes 10 de connexion externe du composant par un élément de liaison souple 11, de faible résistivité. Chaque borne 10 est logée dans une cheminée 12 de la partie supérieure 13 du boîtier 1, et présente une patte de connexion 14, en saillie vers l'intérieur du boîtier 1, et chaque élément de liaison souple 11 est raccordé de manière simple aux pattes de connexion 9 et 14 correspondantes par soudure électrique ou par brasure.The resistive element 4, described below with reference to FIG. 3, comprises two connection tabs 9, each of which is electrically connected to one respectively of two terminals 10 for external connection of the component by a flexible connection element 11 , low resistivity. Each terminal 10 is housed in a chimney 12 of the upper part 13 of the housing 1, and has a connection tab 14, projecting towards the inside of the housing 1, and each flexible connection element 11 is simply connected to the lugs 9 and 14 corresponding connection by electrical welding or soldering.

La structure interne 2 est assemblée au boîtier 1, et plus précisément mécaniquement reliée aux parois latérales internes du boîtier 1, par un corps ou constituant semi-rigide 15, électriquement isolant, tel qu'une résine souple synthétique, qui adhère fortement à la structure interne 2 et au matériau du boîtier 1, et enveloppe les raccordements des éléments de liaison souples 11 aux pattes de connexion 9. Ce constituant 15 est introduit dans le boîtier 1 par un procédé de remplissage partiel.The internal structure 2 is assembled to the housing 1, and more precisely mechanically connected to the internal lateral walls of the housing 1, by a semi-rigid body or constituent 15, electrically insulating, such as a flexible synthetic resin, which strongly adheres to the structure internal 2 and to the material of the housing 1, and envelops the connections of the flexible connecting elements 11 to the connection lugs 9. This component 15 is introduced into the housing 1 by a partial filling process.

Comme cela est bien connu, l'élément résistant 4 d'un tel composant résistif de forte puissance dégage, lorsqu'il est parcouru par un courant électrique de puissance, des quantités importantes de chaleur, qui doivent être évacuées, au travers de la barrière diélectrique 5 formant drain thermique, par le dissipateur 6. Pour mettre l'élément résistant 4, la barrière diélectrique 5 et le dissipateur 6 dans une relation d'échanges thermiques aussi favorable que possible, les faces de l'élément indéformable 3 et de la barrière diélectrique 5 qui doivent conserver un bon contact physique avec l'élément résistant 4 sont usinées par rodage, rectification ou tout autre procédé assurant une planéité globale excellente. De même, la planéité de la face inférieure de la barrière diélectrique 5 doit être bonne et adaptée à celle de la face supérieure du dissipateur 6 avec laquelle elle doit conserver un bon contact physique.As is well known, the resistant element 4 of such a high-power resistive component gives off, when it is traversed by an electric power current, significant amounts of heat, which must be evacuated, through the dielectric barrier 5 forming a heat sink, by the dissipator 6. To put the resistant element 4, the dielectric barrier 5 and the dissipator 6 in a heat exchange relationship as favorable as possible, the faces of the non-deformable element 3 and of the dielectric barrier 5 which must maintain good physical contact with the resistant element 4 are machined by lapping, grinding or any other process ensuring excellent overall flatness. Likewise, the flatness of the lower face of the dielectric barrier 5 must be good and adapted to that of the upper face of the dissipator 6 with which it must maintain good physical contact.

Ces bons contacts physiques sont garantis par un dispositif d'application sous pression calibrée de l'élément résistant 4 contre la barrière diélectrique 5 et de cette dernière contre le dissipateur 6. Ce dispositif comprend au moins un élément élastiquement déformable 16, dont une déformation élastique prédéterminée, lorsqu'il est fixé sur le boîtier 1, permet d'exercer une charge prédéterminée et stable sur la structure interne 2, dans laquelle l'élément indéformable 3 reçoit cette charge et la retransmet, en la répartissant, à l'élément résistant 4 et à la barrière diélectrique 5, pour assurer la mise en pression calibrée.These good physical contacts are guaranteed by a device for applying calibrated pressure of the resistant element 4 against the dielectric barrier 5 and of the latter against the dissipator 6. This device comprises at least one elastically deformable element 16, including an elastic deformation predetermined, when fixed on the housing 1, allows to exert a predetermined and stable load on the internal structure 2, in which the non-deformable element 3 receives this load and retransmits it, by distributing it, to the resistant element 4 and to the dielectric barrier 5, to ensure the calibrated pressurization.

L'élément élastiquement déformable à déformation calibrée 16 est par exemple en métal ou en tout autre matériau ne présentant pas de phénomène de fluage sous charge. Il peut comprendre ou être constitué par un ressort, une rondelle, ou tout autre organe mécanique analogue.The elastically deformable element with calibrated deformation 16 is for example made of metal or any other material which does not exhibit creep phenomenon under load. It can include or be constituted by a spring, a washer, or any other similar mechanical member.

Tel que représenté sur la figure 4 et monté sur le boîtier 1 de la figure 1, cet élément 16 a une structure de barrette ayant au repos, comme représenté en traits interrompus 16a sur la figure 4, une forme générale de V très ouvert, avec deux ailes 17 sensiblement symétriques inclinées sur une base centrale 18 sensiblement plane et, dans l'extrémité de chaque aile 17, un trou pour le passage d'une vis 7 de fixation de l'élément 16 sur le boîtier 1 dans sa position de déformation élastique prédéterminée, représenté en trait plein 16b sur la figure 4.As shown in Figure 4 and mounted on the housing 1 of Figure 1, this element 16 has a bar structure having at rest, as shown in broken lines 16a in Figure 4, a general shape of V very open, with two substantially symmetrical wings 17 inclined on a substantially flat central base 18 and, in the end of each wing 17, a hole for the passage of a screw 7 for fixing the element 16 on the housing 1 in its predetermined elastic deformation position, shown in solid line 16b in FIG. 4.

L'élément 16 est amené dans sa position de déformation élastique prédéterminée pour obtenir la charge prédéterminée par le vissage des vis 7 dans le dissipateur 6 jusqu'à ce que les têtes des vis 7 viennent en butée contre les ailes 17 elles-mêmes en butée contre le boîtier 1, comme montré sur la figure 1. Dans cette position, les ailes 17 sont fléchies sensiblement dans le prolongement l'une de l'autre, et la base centrale 18 applique la charge prédéterminée contre la zone centrale de la partie supérieure 13 du boîtier 1. L'élément indéformable 3 de la structure interne 2 présente une partie centrale 20 en saillie vers le boîtier 1, et sur laquelle prend appui la zone centrale de la partie supérieure 13 de ce boîtier, sous laquelle la saillie 20 est centrée dans une nervure 19 du boîtier 1.The element 16 is brought into its predetermined elastic deformation position in order to obtain the predetermined load by screwing the screws 7 into the dissipator 6 until the heads of the screws 7 abut against the wings 17 themselves in abutment against the housing 1, as shown in FIG. 1. In this position, the wings 17 are flexed substantially in the extension of one another, and the central base 18 applies the predetermined load against the central zone of the upper part 13 of the housing 1. The non-deformable element 3 of the internal structure 2 has a central part 20 projecting towards the housing 1, and on which the central zone of the upper part 13 of this housing bears, under which the projection 20 is centered in a rib 19 of the housing 1.

Les vis 7 sont donc simultanément des moyens de fixation du composant résistif par son boîtier 1 sur le dissipateur 6, et des moyens de fixation et de déformation de l'élément élastiquement déformable 16 dans sa position de déformation élastique prédéterminée sur le boîtier 1.The screws 7 are therefore simultaneously means for fixing the resistive component by its housing 1 on the dissipator 6, and means for fixing and deformation of the elastically deformable element 16 in its predetermined elastic deformation position on the housing 1.

La charge prédéterminée et stable est ainsi une charge centrale, exercée par la base 18 de l'élément déformable 16 sur la partie centrale 20 de l'élément indéformable 3 au-travers de la zone centrale de la partie supérieure 13 du boîtier 1. Par sa grande face inférieure, l'élément indéformable 3 répartit la charge prédéterminée qu'il reçoit et assure la mise sous pression calibrée.The predetermined and stable load is thus a central load, exerted by the base 18 of the deformable element 16 on the central part 20 of the non-deformable element 3 through the central zone of the upper part 13 of the housing 1. By its large underside, the non-deformable element 3 distributes the predetermined load it receives and ensures calibrated pressurization.

La charge prédéterminée, auto-calibrée par flexion élastique, peut être obtenue par un dispositif de mise en pression pouvant comporter plusieurs éléments élastiquement déformables tels que 16, dont le nombre est adapté à une répartition judicieuse de la charge, en fonction de la taille du composant et des caractéristiques demandées.The predetermined load, self-calibrated by elastic bending, can be obtained by a pressurizing device which may include several elastically deformable elements such as 16, the number of which is adapted to a judicious distribution of the load, depending on the size of the component and characteristics requested.

De plus, le montage "imperdable" des vis 7 sur le boîtier 1 rend simultanément les éléments élastiquement déformables 16 du dispositif de mise sous pression solidaires du boîtier 1, même au repos, ce qui facilite la distribution et le montage du composant.In addition, the "captive" mounting of the screws 7 on the housing 1 simultaneously makes the elastically deformable elements 16 of the pressurizing device integral with the housing 1, even at rest, which facilitates the distribution and assembly of the component.

L'exemple de la figure 2, sur laquelle les mêmes références numériques ont été utilisées pour désigner les mêmes éléments, se distingue essentiellement de celui décrit ci-dessus par le fait que la partie centrale en saillie 20 de l'élément indéformable 3 traverse une ouverture ménagée dans la zone centrale de la partie supérieure 13 du boîtier 1, de sorte que la base centrale 18 de l'élément élastiquement déformable 16 s'applique directement contre la face supérieure de la partie centrale 20 de l'élément indéformable 3, qui est accessible à l'extérieur du boîtier 1. La charge prédéterminée est ainsi directement transmise de l'élément élastiquement déformable 16 à l'élément indéformable 3. Une autre différence vis-à-vis de la figure 1 est que la barrière diélectrique 5 comporte une troisième couche 5a, inférieure, en cuivre par exemple, pour améliorer la transmission de chaleur au dissipateur avec lequel elle est en contact, et qui est également traversée par les vis 7.The example of FIG. 2, in which the same reference numerals have been used to designate the same elements, differs essentially from that described above by the fact that the projecting central part 20 of the non-deformable element 3 crosses a opening in the central area of the upper part 13 of the housing 1, so that the central base 18 of the elastically deformable element 16 is applied directly against the upper face of the central part 20 of the non-deformable element 3, which is accessible outside the housing 1. The predetermined load is thus directly transmitted from the elastically deformable element 16 to the non-deformable element 3. Another difference with respect to FIG. 1 is that the dielectric barrier 5 comprises a third layer 5a, lower, in copper for example, to improve the transmission of heat to the dissipator with which it is in contact, and which is also alement crossed by the screws 7.

L'élément résistant 4 des composants des figures 1 et 2, représenté sur la figure 3, est constitué à partir d'une feuille ou d'un dépôt d'un alliage métallique ou d'un métal électriquement conducteur et présente une forme en périphérie qui permet une mise en place et une immobilisation économique, ne demandant aucun accessoire supplémentaire, par exemple une forme carrée ou rectangulaire. Sa structure particulière et ses dimensions particulières décrites ci-dessous sont destinées à obtenir la valeur ohmique requise du composant, sans point chaud et avec une inductance quasi-nulle. L'épaisseur "e" de l'élément résistant 4 est choisie de sorte que sa masse d'alliage ou de métal garantisse une capacité adiabatique suffisante, et de sorte qu'elle permette simultanément une bonne conductibilité thermique transversalement au flux thermique parcourant cet élément mince dans son plan. Cet élément est réalisé par usinage laser, gravure chimique ou par découpe mécanique à partir d'une feuille ou d'un dépôt de métal ou d'alliage métallique ayant subi ou non un traitement thermique préalable de détente. L'usinage de la feuille ou du dépôt rectangulaire de l'élément résistant 4 consiste à la ou le subdiviser, perpendiculairement aux deux grands côtés du rectangle, en bandes ou cellules 21 parallèles, d'une largeur sensiblement constante b, sauf pour les deux bandes 22 d'extrémité qui ont une largeur h supérieure à b. Ces bandes 21 et 22 sont séparées les unes des autres par des fentes 23 de largeur a qui sont ménagées alternativement de l'un vers l'autre des deux grands côtés du rectangle, en s'arrêtant à une distance c de l'autre côté opposé. Cette distance c correspond à la largeur d'une zone d'extrémité 24 par laquelle deux bandes adjacentes sont reliées l'une à l'autre. Les fentes alternées 23 présentent ainsi une extension longitudinale commune d, en projection perpendiculaire sur les petits côtés du rectangle. Dans cet exemple, les deux pattes de connexion 9 sont chacune rectangulaires et repliées perpendiculairement au plan du rectangle des bandes 21 et 22, et chacune s'étend sur une même longueur i le long de l'un respectivement des deux petits côtés du rectangle, à partir de l'un respectivement de deux sommets opposés, aux extrémités d'une diagonale du rectangle.The resistant element 4 of the components of FIGS. 1 and 2, represented in FIG. 3, is formed from a sheet or a deposit of a metallic alloy or of an electrically conductive metal and has a shape at the periphery. which allows an installation and an economic immobilization, requiring no additional accessory, for example a square or rectangular shape. Its particular structure and its particular dimensions described below are intended to obtain the required ohmic value of the component, without hot spot and with an almost zero inductance. The thickness "e" of the resistant element 4 is chosen so that its mass of alloy or metal guarantees sufficient adiabatic capacity, and so that it simultaneously allows good thermal conductivity transverse to the thermal flow this thin element in its plan. This element is produced by laser machining, chemical etching or by mechanical cutting from a sheet or a deposit of metal or metal alloy which may or may not have been subjected to a prior thermal expansion treatment. The machining of the sheet or the rectangular deposit of the resistant element 4 consists in subdividing it, perpendicular to the two long sides of the rectangle, into parallel strips or cells 21, of a substantially constant width b, except for the two end strips 22 which have a width h greater than b. These bands 21 and 22 are separated from each other by slots 23 of width a which are formed alternately from one to the other of the two long sides of the rectangle, stopping at a distance c from the other side opposite. This distance c corresponds to the width of an end zone 24 by which two adjacent strips are connected to each other. The alternating slots 23 thus have a common longitudinal extension d, in perpendicular projection on the short sides of the rectangle. In this example, the two connection lugs 9 are each rectangular and folded perpendicular to the plane of the rectangle of the bands 21 and 22, and each extends over the same length i along one of the two short sides of the rectangle, respectively. from one respectively of two opposite vertices, at the ends of a diagonal of the rectangle.

La largeur a des fentes 23 est aussi faible que possible pour que l'élément résistant 4 présente la plus grande surface possible en contact avec la barrière diélectrique 5, cette largeur a restant cependant d'une valeur suffisante pour assurer un isolement électrique suffisant entre les cellules ou bandes adjacentes 21 et 22. La largeur b des bandes 21 et l'extension commune d des fentes 23 sont choisies pour obtenir la valeur ohmique requise. La largeur c des zones d'extrémité 24 est, en règle générale, toujours plus grande que b, afin que la zone d'extrémité 24 constitue un drain thermique rendu efficace par la conduction transversale dans l'épaisseur e de l'élément résistif 4. Ces mesures permettent d'éviter une augmentation excessive de la température dans chaque zone 25 délimitée autour du fond d'une fente 23. On remarque que ces zones 25 à fond de fente sont ainsi disposées dans la partie périphérique de l'élément résistant 4, qui est mieux refroidie que la partie centrale. Dans les zones des connexions électriques 9, la densité de courant est abaissée, et donc aussi l'élévation de température, en adoptant une largeur h des bandes d'extrémité 22 au moins égale à c et en choisissant la longueur i des pattes de connexion 9 telle qu'elle soit supérieure à h. Cette disposition constitue un frein thermique pour les connexions électriques 9 qui ne sont pas emprisonnées dans l'ensemble recevant la pression calibrée ou charge mécanique prédéterminée.The width of the slots 23 is as small as possible so that the resistant element 4 has the largest possible surface in contact with the dielectric barrier 5, this width a remaining however of a sufficient value to ensure sufficient electrical isolation between the adjacent cells or bands 21 and 22. The width b of the bands 21 and the common extension d of the slots 23 are chosen to obtain the required resistance value. The width c of the end zones 24 is, as a general rule, always greater than b, so that the end zone 24 constitutes a heat sink made efficient by the transverse conduction in the thickness e of the resistive element 4. These measures make it possible to avoid an excessive increase in temperature in each zone 25 delimited around the bottom of a slot 23. It is noted that these zones 25 with bottom of slot are thus arranged in the peripheral part of the resistant element 4, which is better cooled than the central part. In the areas of the electrical connections 9, the current density is lowered, and therefore also the temperature rise, by adopting a width h of the end strips 22 at least equal to c and by choosing the length i of the connection lugs 9 such that it is greater than h. This arrangement constitutes a thermal brake for the electrical connections 9 which are not trapped in the assembly receiving the calibrated pressure or predetermined mechanical load.

Ainsi, les dimensions a, b, c, d, e, h et i sont choisies de façon à permettre une dissipation thermique sans point chaud dans les parties actives de l'élément 4, et en particulier les rapports entre les dimensions c, h et i sont définis de façon à éviter les points chauds dans les connexions de sortie et à y maintenir une température sensiblement égale à celle des parties actives.Thus, the dimensions a, b, c, d, e, h and i are chosen so as to allow heat dissipation without hot spot in the active parts of the element 4, and in particular the relationships between the dimensions c, h and i are defined so as to avoid hot spots in the outlet connections and to maintain there a temperature substantially equal to that of the active parts.

De plus, les faces de l'élément indéformable 3 et de la barrière diélectrique 5 en contact avec l'élément résistif 4 sont rendues conductrices, par un dépôt métallique de résistivité appropriée, ou par un report d'une feuille conductrice ou de résistivité appropriée, ne perturbant pas la valeur ohmique du composant, par un traitement de surface réalisable par différents procédés, tels que sérigraphie, dépôt en couches minces ou épaisses, de quelques microns à quelques centaines de microns. Cette mesure technique fait que le composant ne présente pas de phénomène de "décharges partielles" pour des potentiels allant jusqu'à au moins 7 kV.In addition, the faces of the non-deformable element 3 and of the dielectric barrier 5 in contact with the resistive element 4 are made conductive, by a metallic deposit of suitable resistivity, or by a transfer of a conductive sheet or of suitable resistivity. , not disturbing the ohmic value of the component, by a surface treatment achievable by different methods, such as screen printing, deposit in thin or thick layers, from a few microns to a few hundred microns. This technical measure means that the component does not exhibit the phenomenon of "partial discharges" for potentials up to at least 7 kV.

A proximité des quatre sommets du rectangle, et le long des deux grands côtés de ce dernier, l'élément résistant 4 présente également quatre petites pattes 26, repliées perpendiculairement, qui facilitent le positionnement de l'élément résistant 4 sous l'élément indéformable 3, dont la partie inférieure est aménagée en semelle rectangulaire de distribution de pression sur l'élément résistant 4, sur la face supérieure duquel la limite d'influence de l'élément indéformable 3 est repérée par le périmètre en pointillés 27 sur la figure 3.Near the four vertices of the rectangle, and along the two long sides of the latter, the resistant element 4 also has four small tabs 26, folded perpendicularly, which facilitate the positioning of the resistant element 4 under the non-deformable element 3, the lower part of which is arranged in a rectangular sole for distributing pressure on the resistant element 4, on the upper face of which the limit of influence of the non-deformable element 3 is identified by the dotted perimeter 27 in FIG. 3.

Dans cet exemple, la forme de la barrière diélectrique 5 est également rectangulaire.In this example, the shape of the dielectric barrier 5 is also rectangular.

Avantageusement, dans toutes les réalisations possibles, les formes en plan des parties en contact physique de l'élément déformable 3, de l'élément résistant 4 et de la barrière diélectrique 5 sont des formes homothétiques.Advantageously, in all the possible embodiments, the planar shapes of the parts in physical contact of the deformable element 3, of the resistant element 4 and of the dielectric barrier 5 are homothetic forms.

L'élément 3 est positionné centré, d'une part, sur l'élément 4, par sa semelle reçue entre les pattes de positionnement 26 de l'élément 4, et, d'autre part, dans le boîtier 1, par sa partie centrale en saillie 20, qui se centre soit dans la nervure 19 (fig. 1), soit dans l'ouverture dans le dessus 13 du boîtier 1 (fig. 2). Enfin la barrière 5 est positionnée vis-à-vis du boîtier 1, dans la base duquel elle s'emboîte avec un jeu limité.The element 3 is positioned centered, on the one hand, on the element 4, by its sole received between the positioning tabs 26 of the element 4, and, on the other hand, in the housing 1, by its part protruding central 20, which is centered either in the rib 19 (fig. 1), or in the opening in the top 13 of the housing 1 (fig. 2). Finally, the barrier 5 is positioned with respect to the housing 1, in the base of which it fits with limited play.

En conséquence, les formes des éléments 3 et 4 et de la barrière 5, et d'une façon générale de tous les éléments constitutifs de la structure interne, garantissent un positionnement rapide, précis et économique lors de l'assemblage, sans qu'il soit nécessaire de recourir à des moyens externes tels que des collages, soudures, brasures ou autres procédés d'assemblage souvent générateurs de tension dilatométrique ou augmentant les résistances thermiques des assemblages. Le composant résistif est donc d'une fabrication économique.Consequently, the shapes of elements 3 and 4 and of barrier 5, and in general of all the constituent elements of the internal structure, guarantee rapid, precise and economical positioning during assembly, without it it is necessary to resort to external means such as bonding, welding, soldering or other assembly methods often generating dilatometric tension or increasing the thermal resistances of the assemblies. The resistive component is therefore economically manufactured.

Bien que les exemples de composant résistif décrits ci-dessus ne comportent qu'un seul élément résistif 4 muni de deux pattes de connexion 9 seulement, il doit être bien compris que le composant résistif selon l'invention peut comprendre un ou plusieurs éléments résistifs, chacun muni d'au moins deux bornes ou pattes de connexion, le ou les éléments résistifs pouvant être aménagés en réseau résistif.Although the examples of resistive component described above only include a single resistive element 4 provided of two connection lugs 9 only, it should be clearly understood that the resistive component according to the invention may comprise one or more resistive elements, each provided with at least two terminals or connection lugs, the resistive element or elements being able to be fitted in resistive network.

Claims (11)

  1. A resistive power component intended for installation on a heat sink (6), and comprising:
    a) an internal structure (2) which comprises at least one electrically conductive, flat and thin electrically resistive element (4) resting on a substantially flat electrically insulating dielectric barrier (5) which has good thermal conductivity,
    b) a casing (1) having an electrically insulating top part (13) and housing the said internal structure (2) and provided with at least two terminals (10) for external electrical connection of the component, each terminal being electrically connected to at least one resistive element (4) by at least one connecting element (11) inside the casing (1),
    c) means (15) for mechanically connecting the internal structure (2) to the casing (1) and
    d) a device (3, 16, 7) for applying each resistive element (4) and the dielectric barrier (5) under pressure to the heat sink (6), said application device exerting on the internal structure (2) a predetermined load which ensures the said pressure application and comprising at least one element (16) which is elastically deformable to a predetermined extent in order to give the said predetermined load, means (7) for retaining the or each element (16) elastically deformed to the said predetermined extent in relation to the casing (1), and an indeformable pressure distribution element (3) incorporated in the internal structure (2) in which it is stacked with the or each resistive element (4) and the dielectric barrier (5) and which transmits thereto, with distribution of, the predetermined load which it receives from the or each elastically deformable element (16), characterised in that
    - the said dielectric barrier (5) has a contact surface intended to rest on the said heat sink (6) when the component is installed on said heat sink (6),
    - the said casing (1), which is completely electrically insulating, envelops the said internal structure (2) except at the level of the said contact surface of the said dielectric barrier (5) with the said heat sink (6),
    - the said pressure application device applies each resistive element (4) to the said dielectric barrier (5) and the said barrier (5) to the said heat sink (6) with a calibrated pressure, the said predetermined load being exerted on the said pressure distribution element (3), through the said top part (13) of the casing (1), by the or each said elastically deformable element (16) fixed by the said retaining means (7) on the outside of the said top part (13) of the casing (1), and the component also comprises means (7) for fixing the component by its casing (1) on the said heat sink (6).
  2. A component according to claim 1, characterised in that the said indeformable element (3) has a central part (20) projecting towards the central zone of the said top part (13) of the casing (1), and a flat bottom large surface resting on the or each resistive element (4), and the said predetermined load is a central load exerted on said central part (20) of the indeformable element (3) through the said central zone of the top part (13) of the casing (1), and distributed by the said bottom large surface of the said indeformable element (3).
  3. A component according to claim 2, characterised in that the said central load is applied by a central base (18) of at least one elastically deformable element (16) against the said central zone of the top part (13) of the casing (1), which central zone bears on the said central part (20) of the indeformable element (3).
  4. A component according to claim 2, characterised in that the said central part (20) of the indeformable element (3) extends through an opening formed in the said central zone of the top part (13) of the casing (1) so as to present a top surface accessible to the exterior of the casing (1) and against which there is applied directly at least one elastically deformable element (16).
  5. A component according to any one of claims 1 to 4, characterised in that the means (7) for fixing the or each elastically deformable element (16) on the casing (1) are simultaneously means (7) for fixing the casing (1) on the heat sink (6).
  6. A component according to any one of claims 1 to 5, characterised in that at least one elastically deformable element (16) is in the form of a bar which, at rest, has a general shape of a wide-open V (16a) with a substantially flat base (18) and, in the end of each arm (17) of the V-structure, at least one hole for the passage of a screw (7) for fixing and flexural deformation of the bar, the two arms (17) of which are bent substantially in extension of one another to urge the base (18) towards the internal structure (2) in a position (16b) for applying calibrated pressure to the bar.
  7. A component according to any one of claims 1 to 6, characterised in that the mechanical connection of the casing (1) to the stack formed by the indeformable element (3), the or each resistive element (4) and the dielectric barrier (5) is provided by a semi-rigid electrically insulating constituent (15) which partially fills the casing (1).
  8. A component according to any one of claims 1 to 7, characterised in that the surface of the indeformable element (3) and/or of the dielectric barrier (5) in contact with the or each resistive element (4) is made electrically conductive by a deposit of appropriate resistivity or an addition of a film which is conductive or of suitable resistivity and which does not interfere with the ohmic value of the component.
  9. A component according to any one of claims 1 to 8, characterised in that the connecting elements (11) connecting each resistive element (4) to the terminals (10) are flexible elements of low electrical resistivity connected to connecting tags (9) of the resistive element (4) by electric welding or brazing.
  10. A component according to any one of claims 1 to 9, characterised in that each resistive element (4) is made from a film or a deposit of metal alloy or of metal of a thickness (e) so selected that its mass gives it a sufficient adiabatic capacity.
  11. A component according to any one of claims 1 to 10, characterised in that each resistive element (4) has in plan the shape substantially of a quadrilateral subdivided, perpendicularly to two opposite sides, into parallel strips (21) of a substantially constant width (b), except for the two end strips (22), which are of a width (h) greater than (b), the strips (21, 22) being connected by end zones (24) and separated from one another by slots (23) of a width (a) as small as possible compatible with sufficient insulation between the strips (21, 22), the slots (23) being formed alternately from one towards the other of the two composite sides and terminating at a distance (c) from the other opposite side corresponding to the width of an end zone (24), and the slots having a common longitudinal extension (d), in projection parallel to the said opposite sides, the resistive element (4) also comprising connecting tags (9) bent relatively to the plane of the quadrilateral and each extending over the same length (i) along one respectively of two other opposite sides, the distances (b) and (d) being so selected as to give the specific ohmic value of the component, the distance (c) being greater than (b) in order to form in each end zone (24) an effective conductive heat drain depending on the thickness (e) and limiting the temperature in each zone (25) neighbouring the base of a slot (23), in the peripheral part of the resistive element (4), the dimension (h) being greater than or equal to the dimension (c) and the dimension (i) being greater than (h) in order to limit the temperature in the electrical connection zones.
EP19940401739 1993-08-05 1994-07-28 Power resistor, with device for application under pressure on a heat sink Expired - Lifetime EP0637826B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9309675A FR2708782B1 (en) 1993-08-05 1993-08-05 Resistive power component, with pressure application device on a heat sink.
FR9309675 1993-08-05

Publications (2)

Publication Number Publication Date
EP0637826A1 EP0637826A1 (en) 1995-02-08
EP0637826B1 true EP0637826B1 (en) 1997-10-01

Family

ID=9449981

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19940401739 Expired - Lifetime EP0637826B1 (en) 1993-08-05 1994-07-28 Power resistor, with device for application under pressure on a heat sink

Country Status (3)

Country Link
EP (1) EP0637826B1 (en)
DE (1) DE69405944T2 (en)
FR (1) FR2708782B1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2758409B1 (en) * 1997-01-10 1999-04-02 Vishay Sa RESISTANCE TO HIGH POWER AND / OR ENERGY DISSIPATION
US7843309B2 (en) 2007-09-27 2010-11-30 Vishay Dale Electronics, Inc. Power resistor
EP2215639A1 (en) * 2007-09-27 2010-08-11 Vishay Dale Electronics, Inc. Power resistor

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3802397A1 (en) * 1988-01-28 1989-08-10 Bsg Schalttechnik DEVICE FOR FASTENING AN ACTUATOR FOR POTENTIOMETERS AND THE LIKE ON A SUPPORTING DOCUMENT
DE4014104A1 (en) * 1990-05-02 1991-11-14 Draloric Electronic ELECTRICAL POWER RESISTANCE
US5140298A (en) * 1990-09-04 1992-08-18 International Business Machines Corporation Ceramic base component packaging assembly
DE9217269U1 (en) * 1992-12-17 1993-02-18 Hodek, Alfred, 8672 Selb, De

Also Published As

Publication number Publication date
FR2708782B1 (en) 1995-10-06
FR2708782A1 (en) 1995-02-10
DE69405944D1 (en) 1997-11-06
DE69405944T2 (en) 1998-04-16
EP0637826A1 (en) 1995-02-08

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