US20130340991A1

US20130340991A1 - Layout for electronic component to be cooled, chamber containing the layout, vacuum cooling system including chamber, method of using the vacuum cooling system

Info

Publication number: US20130340991A1
Application number: US13/922,700
Authority: US
Inventors: Gilles Lasfargues; Jean-Charles Cigna; Manuel Fendler
Original assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2012-06-22
Filing date: 2013-06-20
Publication date: 2013-12-26
Also published as: EP2677230A1; FR2992518B1; EP2677230B1; FR2992518A1

Abstract

The layout for an electronic component to be cooled during operation, said layout comprises a support (1) on which the electronic component (16) will be mounted, a base (2) configured so that it will be cooled, and a connecting element (3) mechanically and thermally connecting the base (2) to the support (1) so as to cool it. The connecting element (3) is configured such that the support (1) is free to move relative to the base (2), and the layout comprises a displacement adjustment system (4) configured so as to apply a movement to said support (1) relative to the base.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to the domain of electronic components that have to be operated cold.
The purpose of the invention is specifically a layout for an electronic component to be cooled, said layout in particular enabling support of said electronic component.

PRIOR ART

Document U.S. Pat. No. 5,552,608 discloses a radiation detection component associated with a cold pin. A pin cooling system induces vibrations that can cause prejudice to operation of the detection component. If these vibrations are too high, measurement errors occur in signals output from the detection component. This document U.S. Pat. No. 5,552,608 proposes to solve this problem using a flexible heat conducting connecting element.
Obviously, this flexible connecting element may absorb a maximum amount of vibrations, but in some cases, some vibrations will still be induced at the detection component. A vibration sensor may be used to correct a signal output from the detection component as a function of a signal output from said vibration sensor, so as to solve the problem of residual errors due to unabsorbed vibrations.
This solution is not satisfactory in that simple electronic correction of the signal output from the detection component cannot give an optimum result.
Document U.S. Pat. No. 6,131,394 discloses how to make an entire cooling system vibrate in a controlled manner as a function of measurements made by a vibration sensor. This system is not satisfactory because it is expensive to set up.
There is also more generally a need to solve the problem of vibrations for all types of electronic components.

PURPOSE OF THE INVENTION

The purpose of this invention is to disclose a solution to optimise operation of an electronic component to be cooled.
A start towards this aim is made by choosing a layout for the electronic component to be cooled during operation, which comprises:

- a support on which the electronic component will be mounted,
- a base configured so that it will be cooled,
- a connecting element mechanically and thermally connecting the base to the support so as to cool it, said connecting element being configured so that the support is free to move relative to the base, and
- a displacement adjustment system configured so as to apply a movement to said support relative to the base.

Advantageously, the connecting element is at least partly deformable. For example, the connecting element comprises two end devices connected to each other through a deformable element, one of the end devices being fixed to the base and the other end device being fixed to the support.
The deformable element is preferably in the form of a braid made from a heat conducting material.
Advantageously, the thermal conductivity of the deformable element is greater than or equal to at least 300 W.m⁻¹.K⁻¹.
According to one embodiment, the displacement adjustment system comprises a displacement element in contact with the support, said displacement element being configured so as to limit the input of heat derived from the displacement adjustment system to said support.
Thus the thermal conductivity of the displacement element may be at least 100 times less than the thermal conductivity of the connecting element, for example the displacement element comprises a Polyetheretherketone-based material.
According to one embodiment, the displacement adjustment system comprises a motor drive device, preferably based on piezoelectric motors, configured to apply a movement to the displacement element. Means other than a motor may be used to perform the same function without going outside the scope of the invention.
Preferably, the layout is configured such that the support movement is inscribed in a plane. In other words, it is contained in the same plane during movement of the support.
The invention relates also to a vacuum cooling chamber comprising a layout as described.
Advantageously, the base is fixed relative to an internal cavity of the chamber inside which the base, the connecting element and the support extend.
According to one embodiment, said motor drive device is located inside the chamber or outside the chamber.
According to one embodiment, the motor drive device is laid out in the internal cavity and is fixed to a plate in the chamber, said plate being fixed to a wall delimiting the internal cavity so as to keep the operating temperature of the motor drive device at the ambient temperature of the internal cavity.
The invention also relates to a vacuum cooling system comprising a vacuum cooling chamber and an electronic component, particularly a laser or an electronic component configured to measure at least one wavelength parameter, installed on the support, said system comprising a cooling device configured to cool the base.
The invention also relates to a method of using a vacuum cooling system according to the previous claim, said method comprising an operating step of the electronic component made during a cooling step configured so as to keep the temperature of the electronic component within an operating temperature range.
Advantageously, the method comprises a step to detect vibrations applied to the support, and a step to adjust displacement of the support using the displacement adjustment system as a function of the detected vibrations in order to eliminate said vibrations to stabilise the electronic component at least during the operating step.
According to one embodiment, the electronic component is configured to measure at least one wavelength parameter, and the operating step comprises a step to acquire at least one signal output from the electronic component and representative of the measured parameter.
According to one variant, the acquisition step comprises successively acquisition of a first signal, displacement of the support by the displacement adjustment system and acquisition of a second signal, and the method comprises the generation of a 3D image using the first and second signals.
The invention also relates to a support for recording data that can be read by a computer on which a computer program is recorded comprising computer programming means for implementing steps in a method like that described.
The invention also relates to a computer program comprising a computer programming means adapted to performing steps in the method, when the program is run on a computer.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and characteristics will become clearer after reading the following description of particular embodiments of the invention given as non-limitative examples and shown in the appended drawings, in which:

FIG. 1 is a perspective view showing a particular embodiment of a layout according to the invention,

FIG. 2 is a perspective view showing a connecting element used in the layout shown in FIG. 1,

FIG. 3 shows a principle diagram for manufacturing a connecting element of the type shown in FIG. 2,

FIG. 4 shows an exploded perspective view of a connecting element of the type shown in FIG. 2,

FIG. 5 shows a perspective view of a layout without the connecting element and the base,

FIG. 6 shows a partial perspective view of FIG. 5 without the support and part of the displacement element,

FIG. 7 shows a vacuum cold chamber implementing the layout in the figures described above,

FIG. 8 shows the variation of temperature of different elements used in the layout during a support cooling step, as a function of time.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The layout described below is different from prior art particularly in that it comprises a displacement adjustment system capable of modifying the position of a support on which an electronic component to be cooled will be fitted.
An electronic component to be cooled refers to any component that is advantageously continuously cooled during operation such that it remains within a temperature range suitable for its operation.
The temperature range for an infrared component to be cooled is typically between 70K and 90K, or approximately between −200° C. and −180° C.
In FIG. 1, the layout for an electronic component to be cooled during operation comprises a support 1 on which the electronic component will be fitted and a base 2 configured so as to be cooled. A connecting element 3 mechanically and thermally connects the base 2 to the support 1 so as to cool it. In fact, cooling of the support 1 causes cooling of the electronic component when the electronic component is mounted on said support 1. In other words, the connecting element 3 provides frigories from the base 2 to the support 1 that then transmits them to the electronic component. Said connecting element 3 is configured so that the support 1 is free to move relative to the base 2.
The base 2 and the support 1 are preferably formed from a metallic material, for example such as copper, to give good thermal conductivity.
The connecting element 3 may for example be configured to at least partially absorb vibrations from the base 2 in order to prevent these vibrations from being transmitted to the support 1, or to limit them.
The layout also comprises a displacement adjustment system 4 configured so as to apply a movement to said support 1 relative to the base 2.
According to the particular example in FIG. 1, the displacement adjustment system 4 is configured such that the movement is applied to the support 1 without prejudice to the positioning of the base 2. In other words, the displacement adjustment system 4 does not induce any displacement of the base 2 when it moves the support 1.
This displacement adjustment system 4 can then perform two functions. A first function relates to the vibrations problem mentioned above. If some vibrations are transmitted despite the use of the connecting element 3 in its configuration capable of at least partially absorbing vibrations, or in the case in which the connecting element 3 is not configured to absorb vibrations, the displacement adjustment system 4 can perform a stabilisation function for the support 1. The displacement adjustment system 4 may be slaved for example to data from a layout movement sensor located on the support 1 or the base 2, to stabilise the support 1. The second function is to deliberately displace the support 1, for example so as to place the electronic component in at least two different locations, and to make it function.
The connecting element 3 is advantageously at least partly deformable to control the displacement of the support 1 relative to the base 2. The deformation characteristics of the connecting element 3 are such that when a force is applied on the support 1 by the displacement adjustment system 4, the connecting element 3 deforms at least partially to allow displacement of the support 1 without inducing displacement of the base 2.
FIG. 2 shows a particular embodiment of the connecting element 3. In this embodiment, the connecting element 3 comprises two end devices 5 a, 5 b connected together by a deformable element 6, one of the end devices 5 b being fixed to the base 2 (FIG. 1) and the other end device 5 a being fixed to the support 1 (FIG. 1).
The deformable element 6 may be in the form of a braid made from a heat conducting material, or a deformable parallelogram formed from a heat conducting material. For example, the braid may be made from a metallic material, for example copper. This braid may for example be 2 mm wide and 0.5 mm thick. This braid form is particularly suitable for absorbing vibrations.
In the example in FIG. 2, the deformable element 6 is formed from a single braid adopting a zigzag configuration. The zigzag configuration comprises a broken line showing forward and return paths between two approximately parallel planes P1, P2, the principle diagram of which is shown in FIG. 3. Thus, for each passage through one of the two planes P1, P2, the deformable element 6 has one end configured to couple either with the end device 5 a at plane P1, or with the end device 5 b at plane P2. Each coupling between an end device 5 a, 5 b and the deformable element 6 is made so as to encourage heat exchange between said end device 5 a, 5 b and the deformable element 6. For example, to make a coupling, the deformable element 6 is locally force fitted into a corresponding cavity of the end device 5 a, 5 b associated with it. This coupling by crimping due to force fitting facilitates thermal coupling between the component elements of the connecting element 3.
“Substantially parallel” means preferably precisely parallel or parallel within plus or minus 5 degrees.
According to one particular embodiment shown in FIG. 4, the two end devices 5 a, 5 b each comprise a solid part 105 a. One of the solid parts will come into contact with the support 1 and the other solid part will come into contact with the base 2. Each of the two end devices 5 a, 5 b also comprises a perforated part 105 b that holds the metallic braid 6 in position and enables the contact of the metallic braid with the associated solid part 105 a. Use of a solid part 105 a (except for any attachment holes) in physical contact with the base 2 provides a means of collecting a maximum number of frigories from the base 2 and use of a solid part 105 a (except for any attachment holes) in physical contact with the support 1 provides a means of transmitting the maximum number of frigories to the support 1.
In general, the thermal conductivity of the deformable element 6 (or the connecting element) is advantageously greater than or equal to 300 W.m⁻¹.K⁻¹. Typically, this value may be reached using aluminium; however it is also possible to use copper (401 W.m⁻¹.K⁻¹) or gold (500 W.m⁻¹.K⁻¹). Preferably, a thermal conductivity of between 300 W.m⁻¹.K⁻¹and 500 W.m⁻¹.K⁻¹will be chosen. The same will preferably be true for end devices 5 a, 5 b that will be in direct contact with the base 2 and the deformable element 6 respectively, or with the deformable element 6 and the support 1 respectively.
It will be understood from the above that the objective is to have the lowest possible temperature at the support 1 such that this support cools the electronic component optimally so as to keep it within an appropriate operating temperature range. In such a configuration, when the displacement adjustment system 4 is in direct contact with the support 1, it forms a hot point for which it is preferable to limit the input of calories to the support 1. The input of calories to support 1 by the displacement adjustment system 4 would degrade operation of the electronic component. In this view, the displacement adjustment system 4 may comprise a displacement element 7 in contact with the support 1 (FIG. 1), said displacement element 7 being configured so as to limit the input of calories output from the displacement adjustment system 4 to said support 1. In order to perform this calorie input limitation function, the displacement element may comprise a material based on polyetheretherketone. In general, the thermal conductivity of the displacement element 7 is advantageously at least 100 times less than the thermal conductivity of the connecting element 3.
According to one particular embodiment, the displacement element 7 is formed from an assembly of several parts configured so as to form thermal bridges so as to increase heat losses.
According to one particular example of this particular embodiment shown in FIG. 5, the displacement element 7 comprises two main parts 8 a, 8 b, each with a through hole, separated by a first spacer element such that the through holes are approximately coaxial. The first spacer element is in the form of three rods 9 a in the example, each fixed firstly to one main part 8 b and also to the other main part 8 a. Furthermore, one of the main parts 8 a is proximal to the support 1 and is mounted fixed to the support 1 through a second spacer element in the form of three rods 9 b each fixed firstly to the proximal main part 8 a of the support 1 and to the support 1, in the example. FIG. 5 shows the layout without the base and the connecting element, for reasons of clarity and to facilitate understanding. In fact, the connecting element 3 is mounted as shown in FIG. 1 so as to pass through the through holes of the two main parts 8 a, 8 b and the displacement element 7 is located between the support 1 and the base 2.
“Approximately coaxial” means precisely coaxial or that the holes are arranged so that the connecting element 3 passes through them while allowing a movement travel distance of the support 1 relative to the base 2 without the connecting element 3 coming into contact with the displacement element 7.
The displacement element 7 as described above is only given as an example, those skilled in the art could find many other forms provided that they can limit the input of calories.
According to one particular embodiment, the displacement adjustment system 4 comprises a motor drive device 10 (FIGS. 1, 5 and 6), preferably a piezoelectric motor-based device, configured to move the displacement element 7.
In fact, the motor drive device 10 may form a hot point during operation. In this case, if the displacement element 7 is formed from an assembly of several parts configured so as to form thermal bridges to increase heat losses, these thermal bridges are arranged between the motor drive device 10 and the support 1.
In FIGS. 1, 5 and 6, the motor drive device 10 non-limitatively comprises four piezoelectric motors 10 a, 10 b, 10 c, and 10 d. These four piezoelectric motors are arranged to inscribe a multi-directional movement of the support 1 in a plane. Typically, they are arranged around the displacement element 7 and in the particular example are configured so that each is in contact with the main part 8 b (FIGS. 5 and 6). Although not shown in FIG. 1 for reasons of clarity, the piezoelectric motors are advantageously mounted on a single plate 11 as can be seen in FIGS. 5 and 6. In fact, each piezoelectric motor is configured to compress or to extend along an associated axis A1, A2, A3, A4 under the effect of an electrical stimulation. The electrical stimulation can then adjust the displacement of the support 1. Advantageously, the axes are parallel in pairs, and two of the axes that are not parallel are perpendicular to each other.
Depending on the case, the electronic component to be cooled may only be able to function at low temperatures, for example −200° C. Thus, a vacuum cooling chamber may comprise a layout like that described above.
“Cool” means that the temperature of the chamber can partly keep an electronic component to be cooled within its operating range. Therefore those skilled in the art will be capable of adapting the value of the “cold” temperature as a function of the targeted application.
In fact, as shown in FIG. 7, a vacuum cooling chamber 12 may comprise an internal cavity 13, preferably a vacuum cavity. “Under a vacuum” means a secondary vacuum, for example equal to 10⁻⁵mbars. Creation of a vacuum prevents any condensation inside the chamber 12, and facilitates keeping the inside of the chamber 12 at low temperature. The vacuum may be created by an associated opening 14 that will be connected to a vacuum creation device.
In general the base 2 is fixed inside the chamber 12 relative to the internal cavity 13 of the chamber 12 inside which the base 2, the connecting element 3 and the support 1 extend.
The motor drive device 10 may be placed in the chamber 12 or outside the chamber 12. In FIG. 7, the motor drive device 10 forms part of the chamber 12, in other words it is located in the internal cavity 13. In fact, the motor drive device 10 is located outside the chamber 12 when its operation could be impacted by cooling or by a vacuum in the chamber 12. When the motor drive device 10 is arranged outside the chamber 12, it is coupled to the displacement element through a hermetically sealed transmission device, for example a tombac type device. A tombac is metallic bellows allowing propagation of a movement through a sealed wall.
The motor drive device 10 is advantageously fixed to a wall 15 through the plate 11, thus delimiting the internal cavity 13 of the vacuum cooling chamber 12. This attachment keeps the motor drive device 10 at an ambient temperature inside the chamber so as to not degrade the performances of the motor drive device. In fact, if piezoelectric motors are used, the piezoelectric motors may lose 80% of their efficiency below a certain temperature. In other words, when the motor drive device 10 is located in the internal cavity 13, the motor drive device is fixed on a plate 11 of the chamber 12, said plate 11 being fixed to a wall 15 delimiting the internal cavity 13 so as to keep the operating temperature of the motor drive device 10 at the ambient temperature of the internal cavity 13. In this case, the temperature of the motor drive device 10 tends towards the temperature of the wall 15 of the internal cavity 13 in the chamber 12.
The chamber will contain an electronic component 16, particularly a laser, or an electronic component configured to measure at least one wavelength parameter (for example an infrared sensor). This electronic component is mounted on the support 1. Typically, this component must be capable of interacting with the outside of the vacuum cooling chamber 12 for example to receive information (case of the wavelength measurement), or to emit information (case of the laser). To achieve this, the vacuum cooling chamber may comprise a port 17, such a port 17 is transparent to information.
The chamber 12 comprises a configuration in which it is hermetically sealed such that the pressure in the internal cavity 13 remains constant.
The base 2 may be cooled by any appropriate type of cooling device to cool the electronic component 16. For example, a bath cryostat or a cooling machine may be used. If a bath cryostat is used, the base 2 is cooled by a circulation of a coolant (liquid nitrogen or liquid helium) in contact with the base. In the case of the cooling machine, the base 2 is cooled by means of a gas compression and decompression cycle. The case of the cooling machine will be preferred because it is easy to use. The bath cryostat requires that a reservoir is regularly filled with liquid.
When the base 2 is cooled, this chamber 12 makes it possible for the electronic component 16 mounted on the support 1 to operate within a suitable operating temperature range, for example less than −200° C.
Possible applications of this chamber 12 are the electronic and optical fields.
Therefore, a vacuum cooling system may comprise a vacuum cooling chamber 12 as described above and an electronic component 16 (for example of the type described above) is mounted on the support 1. The system also comprises a cooling device, for example like those described above, configured to cool the base 2.
The invention also relates to a method of using the vacuum cooling system as described. The method comprises an operating step of the electronic component 16 made during a cooling step configured so as to keep the temperature of the electronic component 16 within a given operating temperature range. This operating temperature range may be adapted by those skilled in the art as a function of characteristics of the electronic component used. This cooling step may use the cooling device and more particularly may be made by cooling the base 1 by the cooling device so as to transmit frigories to the base 2, and then to the connecting element 3, and then to the support 1 and finally to the electronic component 16.
According to a first embodiment, the method may comprise a step to detect vibrations applied to support 1, and a step to adjust the displacement of the support 1 by the displacement adjustment system 4 as a function of detected vibrations (for example during the detection step) so as to eliminate said vibrations to stabilise the electronic component 16 at least during the operating step. Thus, the electronic component 16 is stabilised during operation. This so-called “active” stabilisation slaves the deliberate displacement of the support 1 by the adjustment system 4. To achieve this, the slaving may use the data output from a movement sensor giving a signal representative of the movement of said support 1, as input. The movement sensor may be arranged at the support 1, and may be of the accelerometer type.
According to a second embodiment, the electronic component 16 is configured to measure at least one wavelength parameter, and the functioning step comprises a step to acquire at least one signal output from the electronic component 16, said signal being representative of the measured parameter.
According to this second embodiment, the acquisition step may comprise firstly acquisition of a first signal followed by displacement of the support 1 by the displacement adjustment system 4 and then acquisition of a second signal. The method may then comprise generation of a 3-D image from the first and the second signals.
In the context of the embodiment of the second embodiment, using an electronic component 16 fitted with 30 μm photon capture pixels, a shift in the position of the electronic component 16 by one or two pixels is sufficient to generate a 3-D image. With piezoelectric motors, the support 1 and therefore the electronic component 16 can be displaced within a 100 μm square.
In general, the fact that the support 1 is made mobile independently of the base 2 makes it possible to obtain faster movements or higher frequencies than in prior art in which the complete assembly is moved. The result is better stabilisation, and fast positioning for an image acquisition at different positions. Typically, it would be possible to make translation movements of the support 1 in a plane with a frequency of more than 50 Hz. It is also possible with another embodiment of the motors to make the adjustment along an axis approximately normal to the plane of the translation movements.
FIG. 8 shows operation of the vacuum cooling system when bringing the support 1 to the operating temperature of −200° C. of the electronic component. FIG. 8 shows the temperature variation as a function of time for the base 2, for the support 1, for the motor drive device 10 based on piezoelectric motors, and for the displacement element 7. This graph shows that the motor drive device 10 is not impacted by the temperature of the support 1 due to the use of the displacement element 7. Therefore, it is possible to note thermal decoupling between the support 1 and the motor drive device 10.
A medium for recording data that can be read by a computer, on which a computer program is recorded may comprise computer programming means for application of the steps in the method as described above in the different embodiments.
A computer program may comprise a computer programming means adapted to performing steps in the method as described above in its different embodiments, when the program is run on a computer.

Claims

1. A layout for an electronic component to be cooled during operation, said layout comprising:

a support for mounting the electronic component,

a base configured to be cooled,

a connecting element mechanically and thermally connecting the base to the support so as to cool said base,

wherein said connecting element is configured such that the support is free to move relative to the base, and further comprising a displacement adjustment system configured to apply a movement to said support relative to the base.

2. A layout according to claim 1, wherein the connecting element is at least partly deformable.

3. A layout according to claim 2, wherein the connecting element comprises two end devices connected to each other through a deformable element, one of the end devices being fixed to the base and the other end device being fixed to the support.

4. A layout according to claim 3, wherein the deformable element is a braid made from a heat conducting material.

5. A layout according to claim 3, wherein the thermal conductivity of the deformable element is greater than or equal to 300 W.m⁻¹.K⁻¹.

6. A layout according to claim 1, wherein the displacement adjustment system comprises a displacement element in contact with the support, said displacement element being configured to limit the input of heat derived from the displacement adjustment system to said support.

7. A layout according to claim 6, wherein the thermal conductivity of the displacement element is at least 100 times less than the thermal conductivity of the connecting element.

8. A layout according to claim 6, wherein the displacement adjustment system comprises a motor drive device comprising piezoelectric motors, said motor drive device being configured to apply a movement to the displacement element.

9. A layout according to claim 1, wherein the movement of the support is inscribed in a plane.

10. A vacuum cooling chamber comprising a layout according to claim 1.

11. A chamber according to claim 10, wherein the base is fixed relative to an internal cavity of the chamber inside which the base, the connecting element and the support extend.

12. A chamber comprising a layout according to claim 8, wherein said motor drive device is located inside the chamber, or outside the chamber.

13. A chamber according to claim 11, wherein the motor drive device is located in the internal cavity, and is fixed to a plate in the chamber, said plate being fixed to a wall delimiting the internal cavity so as to keep the operating temperature of the motor drive device at the ambient temperature of the internal cavity.

14. A vacuum cooling system comprising a chamber according to claim 10 and an electronic component configured to measure at least one wavelength parameter installed on the support, said system comprising a cooling device configured to cool the base.

15. A method of using a vacuum cooling system according to claim 14, said method comprising an operating step of the electronic component made during a cooling step configured so as to keep the temperature of the electronic component within an operating temperature range.

16. A method according to claim 15, further comprising a step to detect vibrations applied to the support, and a step to adjust displacement of the support using the displacement adjustment system as a function of the detected vibrations in order to eliminate said vibrations to stabilise the electronic component at least during the operating step.