WO2019121117A1 - Element for supporting at least one electronic component - Google Patents

Abstract

The invention concerns a support element (10a) for supporting at least one electronic component, said support element (10a) comprising: • - a receiving area (11) intended to support at least one electronic component; • - at least one linking element (12a-12b) suitable for providing a non-removable mechanical link between said receiving area (11) and an outer edge (14) of said support element (10a); and • - a temperature control element (18) for controlling the temperature of said receiving area (11) arranged in a plane of said receiving area (11) and movable between two positions: • - a position of low thermal conductance with said receiving area (11); and • - a position of high thermal conductance with said receiving area (11).

Description

 SUPPORT ELEMENT OF AT LEAST ONE ELECTRONIC COMPONENT

TECHNICAL AREA

The invention relates to a support element for an electronic component and more particularly to control the influence of the ambient temperature on the electronic component.

The invention finds a particularly advantageous application for thermo-regulated electronic components, such as surface-emitting vertical cavity laser diodes (also called VCSELs in the English literature for "vertical-cavity surface-emitting laser").

PRIOR ART

The thermo-regulated electronic components have the advantage of being free of external temperature variations. For this purpose, the thermoregulated electronic components include a temperature control device. The thermoregulated electronic components are necessarily mounted in a support element to absorb the variations of the thermal conditions of the near environment, the external shocks and reduce the consumption of the control device. This support element comprises means for connecting the thermoregulated component with external elements, in particular for its power supply and to exchange signals.

For example, an atomic clock typically includes:

 a surface-emitting vertical cavity laser diode (VCSEL);

 optical components for adjusting the polarization and the intensity of the laser beam emitted by the VCSEL;

 a cell containing a saturated vapor of an alkali metal such as cesium or rubidium disposed in the axis of the laser beam;

a photodiode arranged after the cell so as to measure the optical power variations of the laser beam after penetration into the cell; a coil for generating a magnetic field in the cell so as to discard the neighboring transitions generated by the Zeeman effect and correctly resolve the clock transition; and

 heating elements and temperature probes for thermally regulating the cell and the VCSEL.

The average energy consumption of a physical module generally depends on the thermal insulation between the thermo-regulated components. In the case of an atomic clock, the thermal insulation between the two central components, the VCSEL and the cell, also makes it possible to guarantee the frequency stability during fluctuations in the ambient temperature. It is therefore necessary to minimize the thermal conduction between the thermo-regulated components by using connecting elements that mechanically maintain and thermally isolate these components. In addition, to overcome thermal losses by the conduction of air, these components are conventionally encapsulated in a vacuum support member and are configured to operate over a very wide temperature range, for example between -40 ° C. and + 85 ° C.

In an atomic clock, the VCSEL is an active element that is temperature regulated at a precise temperature. When the ambient temperature is close to the operating temperature of the VCSEL, it is necessary to dissipate the heat produced by the VCSEL to maintain a stable operating temperature. On the contrary, when the ambient temperature is low compared to the operating temperature of the VCSEL, it is more advantageous to thermally isolate the VCSEL to limit the energy required to heat the VCSEL to the operating temperature. There is therefore a problem related to this contraction between these two constraints.

To solve this problem, the current solution is to effectively isolate the VCSEL is to increase the temperature of the VCSEL well above the maximum ambient temperature so as to limit the influence of the ambient temperature on the operation of the VCSEL. However, this solution limits the life of the VCSEL because the high temperature of the VCSEL rapidly deteriorates its physical properties.

Document US 2016/233143 proposes to dispose an electronic component on a plate with a deformable material disposed around the electronic component. As the temperature increases, the deformable material conducts thermal conduction with an upper portion of the housing so as to modify the thermal conductance between the electronic component and the housing.

Document 2007/21205473 also describes a structure in which a substrate forming the upper part of the housing can be positioned in contact with thermally deformable elements formed on a substrate inside the housing.

In these two documents, the modification of this thermal resistance passes through a deformable element disposed on an upper part of the housing and the configuration of the distance between the deformable element and the reception zone, must be adjusted in a transfer stage of the upper part of the case.

In this transfer step, it is necessary to weld the walls of the housing with the upper part and the realization of this weld causes a variation of the flatness of this upper part.

It is therefore particularly complex to finely adjust the distance between an element formed from the upper part and another element, typically the receiving zone, formed from the lower substrate.

The technical problem of the invention is therefore to find a support element of a simple electronic component to be made and to both dissipate the heat of the component when it heats, and to thermally isolate this component when it works. at a temperature far from the ambient temperature. SUMMARY OF THE INVENTION

The present invention proposes to solve this technical problem by means of a support element having a receiving zone of an electronic component connected at the same time by a fixed connection element and by a temperature regulation element so as to modulate the thermal conductance of the support element as a function of the ambient temperature.

For this purpose, the invention relates to a support element of at least one electronic component, said support element comprising:

 a receiving zone intended to support at least one electronic component; and

 - At least one connecting element adapted to provide an immovable mechanical connection between said receiving zone and an outer edge of said support member.

The invention is characterized in that said support element comprises a temperature regulation element of said receiving zone, disposed in a plane of said receiving zone and movable between two positions:

 a position of low thermal conductance with said receiving area; and a position of high thermal conductance with said reception zone in which a thermal conductance, between said reception zone and said external edge, induced by said regulation element, is greater than a thermal conductance between said reception zone and said outer edge induced by said regulating element in the position of low thermal conductance;

 the displacements of said regulating element being ensured by the deformations induced by thermal expansion phenomena of said regulating element.

The invention thus makes it possible to obtain a support element in which the receiving zone varies its equivalent thermal conductance by using the displacements of the regulation element. In doing so, the invention makes it possible to dissipate the excess heat of an electronic component when the ambient temperature is high and to isolate the electronic component as well as possible when the ambient temperature is low.

To meet the specific problem of the VCSEL of an atomic clock, it is no longer necessary to greatly increase the operating temperature above the maximum ambient temperature because the position of low thermal conductance of the control element Isolates the VCSEL when the ambient temperature is low compared to the operating temperature of the VCSEL.

Conversely, the position of strong thermal conductance of the control element makes it possible to dissipate the surplus heat of the VCSEL when the ambient temperature is close to the operating temperature of the VCSEL. In doing so, the invention makes it possible to limit the power consumption to regulate the VCSEL while increasing the lifetime of the VCSEL.

According to one embodiment, said thermal conductance, between said receiving zone and said outer edge, induced by said regulating element in the position of low thermal conductance, is less than a quarter of a thermal conductance induced by said connecting element.

This embodiment makes it possible to effectively limit the thermal conductance induced by the regulation element in the position of low thermal conductance.

According to one embodiment, said thermal conductance, between said receiving zone and said external edge, induced by said regulation element in the position of high thermal conductance, is greater than half of a thermal conductance induced by said connecting element. .

This embodiment effectively dissipates the heat of the receiving zone through the regulating element in the position of high thermal conductance. According to one embodiment, said regulating element is made of a laminated material and pre-impregnated with hydrocarbon ceramic.

This material makes it possible to obtain reliable thermal expansion properties with a large expansion factor, thus making it possible to anticipate the movements of the regulating element as a function of temperature over time. For example, this material may correspond to Roger R04000 ^® material.

According to one embodiment, said regulating element takes the form of a bar extending longitudinally between an outer edge of said support member and said receiving zone, a spacing being provided between one end of said bar and said receiving zone of so that:

 when the ambient temperature is lower than a first threshold value, said spacing limits the thermal conductance of said bar; and

 when the ambient temperature is greater than a second threshold value, said spacing is filled by the thermal expansion of said bar.

This embodiment is particularly simple to implement because it is sufficient to realize the receiving area with several connecting elements and perform a laser cut in one of the connecting elements to form the spacing and realize the invention.

According to one embodiment, said spacing has a thickness of between 5 and 60 μm.

According to one embodiment, said regulating member takes the form of an arc extending between two perpendicular outer edges of said support member, said arc extending with a spacing along said connecting member so that:

 when the ambient temperature is lower than a first threshold value, said spacing limits the thermal conductance of said arc; and

when the ambient temperature is greater than a second threshold value, said spacing is filled by the thermal expansion of said arc; the movements of said arc with respect to said reception zone, induced by the ambient temperature, making it possible to vary said thermal conductance continuously.

This embodiment provides four distinct thermal bridges that can each be associated with a distinct temperature to gradually vary the thermal conductance.

According to one embodiment, said regulating element takes the form of an arc extending between two internal angles of said support element, an apex of said arc extending with a spacing close to said reception zone so that:

 when the ambient temperature is lower than a first threshold value, said spacing limits the thermal conductance of said arc; and

 when the ambient temperature is greater than a second threshold value, said spacing is filled by the thermal expansion of said arc;

 the movements of said arc with respect to said reception zone, induced by the ambient temperature, making it possible to vary said thermal conductance continuously.

This embodiment makes it possible to obtain a significant displacement of the arc by the thermal expansion, thus facilitating the method of producing the arc.

According to one embodiment, said regulating element takes the form of a bar extending longitudinally between an outer edge of said support member and said receiving zone, a set of grooves being formed on said bar so that:

 when the ambient temperature is lower than a first threshold value, said set of grooves limits the thermal conductance of said bar; and

 when the ambient temperature is greater than a second threshold value, said set of grooves is filled by the thermal expansion of said bar;

the displacements of said bar relative to said reception zone, induced by the ambient temperature, making it possible to vary said thermal conductance continuously. This embodiment also makes it possible to obtain a significant expansion of the bar. According to one embodiment, said first threshold value is between 20 and 40 ° C while said second threshold value is between 60 and 80 ° C. SUMMARY DESCRIPTION OF THE FIGURES

The manner of carrying out the invention as well as the advantages which result therefrom, will emerge clearly from the following embodiment, given by way of indication but without limitation, in support of the appended figures in which FIGS. 1 to 4 represent:

 - Figure la-lb: schematic representations in perspective of a support member according to a first embodiment of the invention and the influence of temperature on its behavior;

 - Figure 2a-2b: schematic representations in perspective of a support member according to a second embodiment of the invention and the influence of temperature (Figure 2b) on its behavior;

 3a-3b: schematic representations in perspective of a support element according to a third embodiment of the invention as well as the influence of temperature (FIG. 3b) on its behavior; and

 - Figure 4a-4b: schematic representations in perspective of a support member according to a fourth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figures la to lb illustrate a first embodiment in which a support member 10a, substantially parallelepipedic, has an outer edge 14 so as to cooperate with the inner edges of a housing. This support element 10a comprises a receiving zone 11 for an electronic component, advantageously a thermo-regulated component. This receiving zone 11 is disposed substantially in the center of the support element 10a and held by two arms 12a, 12b.

Each arm 12a, 12b extends longitudinally between the receiving zone 11 and an outer edge 14 of the support member 10a. Thus, the two arms 12a, 12b are coplanar with the receiving zone 11. In order to limit the heat exchange between the housing and the electronic component, these arms 12a, 12b extend in the length of the support element 10a and are fixed substantially at the center of the width of the outer edge 14 of the element of support 10a.

The heat exchanges between the housing and the electronic component are also controlled by a temperature control element 18. According to the invention, this temperature regulation element 18 is arranged in a plane of the reception zone 11.

In the example of FIGS. 1a-1b, this temperature control element 18 is in the form of two bars 20a and 20b each extending longitudinally between the center of a length of the outer edge 14 and the receiving zone 11 In this embodiment, the characteristic that the temperature control element 18 is disposed in a plane of the reception zone 11 induces that the two bars 20a and 20b extend in the same plane as the arms 12a, 12b and the outer edge 14. Unlike the arms 12a, 12b, these bars 20a, 20b do not always touch the receiving zone 11 because a spacing 21a, 21b is provided between these bars 20a, 20b and the receiving zone 11.

This temperature regulation element 18 is movable between two positions: a position of low thermal conductance with the receiving zone 11; and a position of high thermal conductance with the receiving zone 11.

As shown in FIG. 1b, in the low conductance position, the bars 20a, 20b do not touch the receiving zone 11. For example, the bars 20a, 20b are spaced from the receiving zone 11 of a spacing 21a, 21b between 5 and 60 pm. Although this spacing 21a, 21b is very fine in the position of low conductance, the absence of contact limits the heat exchange between the bars 20a, 20b and the reception zone 11 only to radiation exchanges, excluding any conduction between the bars 20a, 20b and the reception zone 11. In contrast, in the position of strong thermal conductance, as shown in Figure la, the bars 20a, 20b touch the receiving zone 11 and the spacing 21a, 21b no longer exists. In doing so, the bars 20a, 20b participate in the thermal regulation of the receiving zone 11 with the arms 12a, 12b.

Thus, in this position of high thermal conductance, the thermal conductance between the receiving zone 11 and the outer edge 14, induced by the regulation element 18, is greater than the thermal conductance induced by the regulation element 18 in the position of low thermal conductance. Typically, the thermal conductance induced by the regulating element 18 in the low thermal conductance position is less than a quarter of the thermal conductance induced by the arms 12a-12b because of the spacing 21a, 21b whereas the thermal conductance induced by the regulating element 18 in the position of high thermal conductance is greater than half the thermal conductance induced by the arms 12a-12b.

The displacements of the bars 20a, 20b between the position of low thermal conductance and the position of high thermal conductance are provided by the deformations induced by the thermal expansion phenomenon of the bars 20a, 20b. When the ambient temperature is high, for example greater than 80 ° C, the bars 20a, 20b store the ambient temperature and heat.

During heating of the bars 20a, 20b a thermal expansion occurs which makes it possible to fill the spacings 21a, 21b. The bars 20a, 20b then allow to dissipate the temperature of an electronic component mounted on the receiving zone 11 when the ambient temperature is high. On the contrary, when the ambient temperature is low, for example less than 20 ° C, the bars 20a, 20b are not sufficiently expanded to fill the spacings 21a, 21b to obtain a greater thermal insulation between the receiving zone 11 and the outer edge 14. It follows that the thermal conductance between the bars 20a, 20b and the receiving zone 11 is discontinuous as a function of the ambient temperature. This expansion capacity can be configured by the nature of the constituent materials of the bars 20a, 20b. For example, the bars 20a, 20b may be made of a laminated material and pre-impregnated with hydrocarbon ceramic, typically Roger R04000 ^® material marketed by ROGER ^® .

FIGS. 2a and 2b illustrate a second embodiment in which the support element 10b has a temperature control element 18 made in the form of four arcs 22a-22d fixed on either side to the outer edge 14. Each arc 22a-22d is written in a quarter of the surface of the support member 10b and extends between half the length of an outer edge 14 and half the width of an outer edge 14. The curvature of each arc 22a-22d is predetermined so that a large portion of each arc 22a-22d follows the trajectory of the arms 12a, 12b.

In the position of low thermal conductance, as shown in Figure 2a, there is a spacing 23a-23d, for example of the order of 5 to 60 mhi, between the arcs 22a-22d and arms 12a, 12b. The previously described thermal expansion makes it possible to fill this gap 23a-23d so that, in the position of high thermal conductance, as illustrated in FIG. 2b, the arcs 22a-22b touch the arms 12a, 12b and improve the thermal conductance. between the outer edge 14 and the receiving zone 11.

FIGS. 3a and 3b illustrate a third embodiment in which the support member 10c has a temperature control element 18 made in the form of two arcs 24a, 24b fixed on either side to the outer edge 14 Each arc 24a, 24b is formed in one half of the surface of the support member 10c and extends between two inner corners 15 of the outer edge 14. The curvature of each arc 24a, 24b is predetermined so that a apex 26a, 26b of each arc 24a, 24b extending with a small spacing 25a, 25b close to the receiving zone 11 in the position of low thermal conductance.

Thus, in the position of low thermal conductance, as illustrated in FIG. 3a, there is a spacing 25a, 25b, for example of the order of 5 to 60 μm, between the arcs 24a, 24b and the receiving zone. 11. The thermal expansion previously described makes it possible to fill this gap 25a, 25b so that, in the position of high thermal conductance, as illustrated in FIG. 3b, the arcs 24a, 24b touch the reception zone 11 and improve the thermal conductance between the outer edge 14 and the receiving zone 11.

FIGS. 4a and 4b illustrate a fourth embodiment in which the support member 10d has a temperature control element 18 made in the form of a bar 27 fixed between the receiving zone 11 and the center of the length of the external edge 14. Unlike the first embodiment, the bar 27 is fixed on the receiving zone 11 regardless of the temperature.

Indeed, the bar 27 has an accordion shape 28 formed by grooves formed on either side of the bar 27. In the position of low thermal conductance, the accordion shape is stretched, while in the position of strong thermal conductance, the accordion shape is compressed. Thus, the contact section of the bar 27 with the receiving zone 11 is lower in the position of low thermal conductance than in the position of high thermal conductance.

Indeed, in this embodiment, the thermal expansion previously described makes it possible to fill the grooves forming the accordion 28 so that, in the position of high thermal conductance, the bar 27 touches the receiving zone 11 over its entire section, thus increasing the heat transfer by conduction.

Alternatively, the support member 10 may have other shapes without changing the invention. For example, the support member 10 may be configured to support multiple electronic components with a plurality of separate receiving areas 11. The arms 12a, 12b may have non-rectilinear paths to increase the length of the thermal path. In addition, the receiving zone 11 may be arranged differently with respect to the outer edge 14 of the support element 10. For example, the receiving zone 11 can be maintained by a single connecting arm 12 extending over three quarters. the length of the support element 10. Embodiment of either of these embodiments may include taking a solid plate and forming laser cuts to obtain the previously described patterns. The invention thus makes it possible to effectively manage the heat dissipation of a component mounted on the reception zone 11 with at least two distinct states:

 - A first state in which the support member 10 allows a large heat dissipation of the component when the expansion of the control element 18 is sufficient to improve the heat dissipation of the receiving zone 11; and

 a second state in which the support element 10 makes it possible to obtain a lower heat dissipation of the component when the expansion of the regulating element 18 is not sufficient for the regulating element 18 to participate actively in the heat dissipation of the receiving zone 11.

This variation in heat dissipation is obtained passively without modifying the temperature control system of the electronic component. This variation may be discontinuous, as illustrated by the first embodiment, or continuous, as illustrated by the other three embodiments.

Claims

A support member (10a-10d) of at least one electronic component, said support member (10a-10d) comprising:  a reception zone (11) intended to support at least one electronic component; and  at least one connecting element (12a-12b) capable of providing an irremovable mechanical connection between said receiving zone (11) and an outer edge (14) of said support element (10a-10d); characterized in that said support member (10a-10d) comprises a temperature regulating element (18) of said receiving zone (11) disposed in a plane of said receiving zone (11) and movable between two positions:  a position of low thermal conductance with said receiving zone (11); and  a position of high thermal conductance with said reception zone (11) in which a thermal conductance between said reception zone (11) and said external edge (14), induced by said regulation element (18), is greater than a thermal conductance between said receiving zone (11) and said outer edge (14) induced by said regulating element (18) in the low thermal conductance position;  the displacements of said regulating element being ensured by the deformations induced by thermal expansion phenomena of said regulating element. The support member of claim 1, wherein said thermal conductance between said receiving zone (11) and said outer edge (14) induced by said regulating element (18) in the low thermal conductance position is less than a quarter of a thermal conductance induced by said connecting element (! 2a-12b). A support member according to claim 1 or 2, wherein said thermal conductance between said receiving zone (11) and said outer edge (14) induced by said regulating element (18) in the position of strong thermal conductance , is greater than half of a thermal conductance induced by said connecting element (12a-12b). 4. Support element according to one of claims 1 to 3, wherein said control element (18) is made of a laminate material and prepreg of hydrocarbon ceramic. The support member according to one of claims 1 to 4, wherein said regulating member (18) takes the form of a bar (20a-20b) extending longitudinally between an outer edge (14) of said support (10a-10d) and said receiving zone (11), a spacing (21a-21b) being provided between one end of said bar (20a-20b) and said receiving zone (11) so that:  when the ambient temperature is lower than a first threshold value, said spacing (21a-21b) limits the thermal conductance of said bar (20a-20b); and when the ambient temperature is greater than a second threshold value, said spacing (21a-21b) is filled by the thermal expansion of said bar (20a-20b). The support member of claim 5, wherein said spacing has a thickness of between 5 and 60 mhi. The support element according to one of claims 1 to 4, wherein said regulating element (18) takes the form of an arc (22a-22d) extending between two perpendicular outer edges (14) of said support (10a-10d), said arc (22a-22d) extending with a spacing (23a-23d) along said connecting member (12-22b) so that:  when the ambient temperature is lower than a first threshold value, said spacing (23a-23d) limits the thermal conductance of said arc (22a-22d); and when the ambient temperature is greater than a second threshold value, said spacing (23a-23d) is filled by the thermal expansion of said arc (22a-22d); displacements of said arc (22a-22d) relative to said reception zone (11), induced by the ambient temperature, making it possible to vary said thermal conductance continuously. The support member according to one of claims 1 to 4, wherein said regulating member (18) is in the form of an arc (24a-24b) extending between two internal angles (15) of said support member. (10a-10d), a vertex (26a-26b) of said arc (24a-24b) extending with a spacing (25a-25b) close to said receiving zone (11) so that:  when the ambient temperature is lower than a first threshold value, said spacing (25a-25b) limits the thermal conductance of said arc (24a-24b); and  when the ambient temperature is greater than a second threshold value, said spacing (25a-25b) is filled by the thermal expansion of said arc (24a-24b);  displacements of said arc (24a-24b) with respect to said reception zone (11), induced by the ambient temperature, making it possible to vary said thermal conductance continuously. The support member according to one of claims 1 to 4, wherein said regulating member (18) takes the form of a bar (27) extending longitudinally between an outer edge (14) of said support member ( 10a-10d) and said receiving zone (11), a set of grooves (28) being formed on said bar (20a-20b) so that:  when the ambient temperature is lower than a first threshold value, said set of grooves (28) limits the thermal conductance of said bar (20a-20b); and when the ambient temperature is greater than a second threshold value, said set of grooves (28) is filled by the thermal expansion of said bar (20a-20b); displacements of said bar (27) with respect to said reception zone (11), induced by the ambient temperature, making it possible to vary said thermal conductance continuously. 10. Support element according to one of claims 5 to 9, wherein said first threshold value is between 20 and 40 ° C while said second threshold value is between 60 and 80 ° C.