Thermal drainage part of a 3D electronic module

The thermal drainage part enhances the thermal management of optoelectronic sensors in 3D modules by increasing heat exchange surface area, addressing the limitations of existing cooling solutions and improving image quality while maintaining compactness and reducing costs.

FR3136110B1Active Publication Date: 2025-06-203D PLUS CO
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Patent Information

Application Number
FR2022005065
Authority / Receiving Office
FR · FR
Patent Type
Patents
Current Assignee / Owner
Filing Date
2022-05-25
Publication Date
2025-06-20
Estimated Expiration
2042-05-25

AI Technical Summary

Technical Problem

Existing solutions for cooling optoelectronic sensors in 3D electronic modules are costly and complex, limiting the compactness and efficiency of thermal management, especially in space applications where maintaining low temperatures is crucial for image quality.

Method used

A low-cost thermal drainage part made of thermally conductive materials, designed to maximize heat exchange surface area between the sensor and a rigid cradle, reducing thermal resistance and enabling efficient external cooling.

Benefits of technology

The solution effectively reduces thermal noise and maintains the sensor at a low temperature, improving image quality in low-light conditions without compromising the compactness of the 3D module, and reduces manufacturing and assembly costs.

✦ Generated by Eureka AI based on patent content.

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Abstract

The invention relates to a thermal drainage part (40) made of a thermally conductive material and intended to thermally connect an optoelectronic sensor (10) to a rigid cradle (30) cooled by external cooling means; the optoelectronic sensor (10) being mounted on a printed circuit (20); the cradle having at least one fixing boss (32) and an opening (31) intended to house the optoelectronic sensor (10); said thermal drainage part (40) comprising: a base (41) intended to be brought into thermal contact with at least one fixing boss (32) of the cradle; a protuberance (42) intended to be brought into thermal contact with a lower face of the optoelectronic sensor (10) through a hole passing through the printed circuit (20). Figure for abstract: Fig. 1b
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Description

Title of the invention: Thermal drainage part of a 3D electronic module

[0001] Scope of application

[0002] The present invention relates to the field of 3D optoelectronic imaging modules, in particular spatial imaging. More particularly, the invention relates to the thermal management of an image sensor used in the context of spatial applications, whether scientific or industrial.

[0003] Problem raised

[0004] In the space industry it is desirable to miniaturize optoelectronic imaging modules while using more efficient optoelectronic sensors with greater resolution.

[0005] In the context of spatial imaging, maintaining the image sensor at a low and stable temperature is necessary to ensure its proper functioning. The performance of an optoelectronic sensor degrades drastically when the temperature increases. The dark current increases and thus the black becomes gray during detection. This is problematic in spatial applications for which black is predominant in the majority of images. This problem is amplified by the use of sensors with increasingly higher resolution. Increasing the resolution leads to an increase in power consumption for the same sensor technology and therefore the sensor dissipates more heat during its operation.

[0006] Thus, for operation in low-light conditions, reducing thermal noise in imagers is fundamental. "Thermal noise" means noise generated by the thermal agitation of charge carriers.

[0007] A problem to be solved in this context is to maintain a low temperature of an optoelectronic sensor in a 3D electronic module for a space application. A general objective is to ensure a low operating temperature for an optoelectronic sensor in order to reduce thermal noise, and thus dark current. This allows for improved image quality.

[0008] Prior art / State of the art restrictions

[0009] The solutions currently used to cool the sensors are the addition of a Peltier type heat exchanger and a radiator to dissipate the heat. However, this type of solution has a high cost. In addition, the implementation of this solution and its implementation remain complex. Indeed, the surface dedicated to the heat exchange in the sensor is not easily accessible to install a such a device in a 3D electronic module. Thus, the implementation of a heat exchanger is at the expense of the compactness of the 3D module.

[0010] European patent EP3340303B1 illustrates a 3D electronic module comprising an optoelectronic sensor and a thermally conductive rigid cradle in the form of a frame delimiting an opening which houses said sensor. The cradle is passively cooled and acts as a thermal mass. However, the contact surface between the cradle and the sensor is limited to the periphery of the sensor. This increases the thermal resistance between the sensor and the cradle and limits the heat exchange surface.

[0011] Response to the problem and provision of solution

[0012] To overcome the limitations of existing solutions with regard to improving the heat dissipation of the optoelectronic sensor integrated in a 3D electronic module, the invention proposes a low-cost thermal drainage part, simple to implement and compatible with a three-dimensional structure of an electronic module. The thermal drainage part makes it possible to reduce the thermal resistance by 4°C / W compared to the solution of European patent EP3340303B1 (3°C / W instead of 7°C / W). The drainage part according to the invention makes it possible to maximize the heat exchange surface between the sensor and the cradle regardless of the way in which the sensor is transferred into the cradle. In addition, the invention proposes a 3D electronic module in which the drainage part according to the invention is implemented so as to create a thermal circuit connecting the sensor to an interface cooled by external means.Furthermore, the invention presents a method for manufacturing the 3D electronic module according to the invention.

[0013] The solution according to the invention makes it possible to improve the quality of images in a low-light environment by reducing thermal noise in the sensor. The reduction of thermal noise is achieved by reducing the thermal resistance between the sensor and the thermal mass of the module. The reduction of thermal resistance between the sensor and the thermal mass of the module is achieved by increasing the heat exchange surface between the sensor and the thermal mass of the module.

[0014] The solution allows to control the temperature of the sensor more efficiently, thus allowing to keep it at a low temperature without losing in terms of compactness of the 3D module.

[0015] In addition, the drainage part according to the invention makes it possible to reduce manufacturing and assembly costs compared to state-of-the-art solutions.

[0016] Furthermore, the solution according to the invention is compatible with any optical sensor having a free surface in its connector matrix of the LGA (acronym for Land Grid Array), BGA (acronym for Bail Grid Array), CGA (acronym for Column Grid Array) or PGA (acronym for Pin Grid Array) type.

[0017] Summary / Claims

[0018] The subject of the invention is a thermal drainage part made of a thermally conductive material and intended to thermally connect an optoelectronic sensor to a rigid cradle cooled by external cooling means. The optoelectronic sensor being mounted on a printed circuit; the cradle having at least one fixing boss and an opening intended to house the optoelectronic sensor.

[0019] Said thermal drainage part comprising: - a base intended to be placed in thermal contact with at least one cradle fixing boss; - a protrusion intended to be placed in thermal contact with a lower face of the optoelectronic sensor through a hole passing through the printed circuit and passing through a hole in the printed circuit.

[0020] According to a particular aspect of the invention, the base is composed of one or more integral arms.

[0021] According to a particular aspect of the invention, the arms are coplanar along a first plane.

[0022] According to a particular aspect of the invention, the arms are secured via a common central intersection surface.

[0023] According to a particular aspect of the invention, the protrusion extends from the central intersection surface.

[0024] According to a particular aspect of the invention, the arms are secured via a mechanical fixing part in the form of a frame or ring connecting the arms together.

[0025] According to a particular aspect of the invention, the protrusion extends from the mechanical fixing part.

[0026] According to a particular aspect of the invention, the protuberance has a first flat upper surface.

[0027] According to a particular aspect of the invention, each arm comprises at least one end having a second upper surface intended to be glued to the base of the associated fixing boss.

[0028] According to a particular aspect of the invention, each arm comprises at least one end having a shape complementary to that of the lateral surface of the associated fixing boss.

[0029] The invention also relates to a 3D electronic module comprising: - an optoelectronic sensor mounted on a printed circuit, - a rigid cradle cooled by external cooling means; the cradle having a central opening intended to house the optoelectronic sensor and having at least one fixing boss, - a thermal drainage part according to the invention.

[0030] According to a particular aspect of the invention, the optoelectronic sensor comprises a housing in which is housed a photosensitive chip with a flat active face, with on the opposite face of the housing electrical connection pins connected to the printed circuit through the opening of the cradle.

[0031] According to a particular aspect of the invention, the height of the protuberance is chosen so as to obtain a volume of empty space between the base and the printed circuit.

[0032] According to a particular aspect of the invention, the sensor is molded in an epoxy resin.

[0033] The invention also relates to a method for manufacturing a 3D electronic module according to the invention comprising the following steps: i. fix the optoelectronic sensor to the cradle by gluing it to the edges of the central opening using a thermally conductive glue. ii. drill the circuit board to make holes aligned with the cradle mounting bosses and the drainage piece protrusion. iii. Assemble the assembly formed by the optoelectronic sensor and the cradle to the printed circuit after inserting the fixing bosses into the dedicated holes. iv. Assemble the assembly formed by the optoelectronic sensor, the cradle and the printed circuit to the thermal drainage part by inserting the protrusion into the dedicated hole and by gluing the ends of the base to the support bosses using a thermally conductive glue.

[0034] According to a particular aspect of the invention, the method further comprises a step of molding the optoelectronic sensor in an epoxy resin after the fixing step i). Detailed description

[0035] Other characteristics and advantages of the present invention will appear more clearly on reading the description which follows in relation to the following appended drawings.

[0036] [Fig. la] [Fig. la] illustrates a first perspective view of the electronic module according to a first embodiment of the invention.

[0037] [Fig. 1b] [Fig. 1b] illustrates a second perspective view of the electronic module according to the first embodiment of the invention.

[0038] [Fig. 1c] [Fig. 1c] illustrates a sectional view of the electronic module according to the first embodiment of the invention.

[0039] [Fig. Id] [Fig. Id] illustrates a perspective view of the thermal drainage part according to the first embodiment of the invention.

[0040] [Fig.2a] [Fig.2a] illustrates a perspective view of the electronic module according to a second embodiment of the invention.

[0041] [Fig.2b] [Fig.2b] illustrates a sectional view of the electronic module according to the second embodiment of the invention.

[0042] [Fig.2c] [Fig.2c] illustrates a perspective view of the thermal drainage part according to the second embodiment of the invention.

[0043] [Fig.3a] [Fig.3a] illustrates a perspective view of the thermal drainage part according to a third embodiment of the invention.

[0044] [Fig.3b] [Fig.3b] illustrates a perspective view of the thermal drainage part according to a fourth embodiment of the invention.

[0045] [Fig.4] [Fig.4] illustrates a flowchart of the steps in the manufacturing process of a 3D electronic module according to the invention.

[0046] In the remainder of the description, the expressions "front", "rear", "upper", "lower" are used with reference to the orientation of the figures described. To the extent that the elements can be positioned in other orientations, the directional terminology is indicated for illustration purposes and is not limiting.

[0047] [Fig. 1a] illustrates a first perspective view of the electronic module 1 according to a first embodiment of the invention. The electronic module 1 comprises an optoelectronic sensor 10 mounted on a printed circuit 20, a rigid cradle 30 and a thermal drainage part 40. [Fig. 1a] illustrates the electronic module 1 from the side of the active face of the optoelectronic sensor 10. [Fig. 1b] illustrates a second perspective view of the electronic module according to the first embodiment of the invention. [Fig. 1b] illustrates the electronic module 1 from the side of the thermal drainage part 40.

[0048] The optoelectronic sensor 10 comprises a housing 101 in which a photosensitive chip 102 is housed. The photosensitive chip 102 has a first planar active face (orthogonal to the Z axis) capable of converting photons into electrical charges. The sensor further comprises, on the opposite face orthogonal to the Z axis (here the lower face) of the housing 101, electrical connection pins 103. The pins 103 are intended to connect the photosensitive chip to the conductive tracks of the printed circuit 20. The printed circuit 20 is shown transparently in [Fig. 1b] in order to visualize the distribution of the pins and the lower surface of the optoelectronic sensor 10. The pins 103 partially occupy the lower face of the housing 101 so as to leave a partial surface without pins. In the illustrated case, this is the central surface of the lower face of the sensor 10.The pins 103 can be of type LGA (acronym for Land Grid Array), BGA (acronym for Bail Grid Array), CGA (acronym for Column Grid Array) or PGA (acronym for Pin Grid Array).

[0049] The printed circuit 20 can be produced by a PCB (acronym for Printed Circuit Board) type circuit comprising electrically conductive tracks. The electrically conductive tracks are connected to the pins in order to carry the signals from the optoelectronic sensor 10. Alternatively, it is possible to stack a plurality of printed circuits on top of each other below the sensor 10. The printed circuits can be interconnected by metal vias or lateral conduction tracks.

[0050] The cradle 30 is made in the form of a rigid frame in which the sensor 10 is positioned and glued by its rear face comprising the pins 103. The cradle 30 plays a role of mechanical stabilization of the sensor 10. The cradle comprises an opening 31 in which the sensor 10 is housed. The periphery of the lower face of the sensor 10 rests on a part of the peripheral surface of the opening 31. The opening 31 allows the pins 103 to pass towards the printed circuit 20. The opening 31 is generally rectangular but not necessarily. The sensor 10 is fixed to the cradle 30 by means of a thermally conductive glue at the peripheral contact surface of the opening 31. Advantageously, the sensor 10 is molded in an epoxy resin, preferably an epoxy resin loaded with silica beads. This makes it possible to mechanically stabilize the sensor in the frame of the cradle 30.

[0051] By way of non-limiting example, the cradle 30 is made of steel or aluminum.

[0052] In addition, the cradle 30 has a plurality of fixing bosses 32 to mechanically stabilize the cradle 30 and thus the 3D module 10. The printed circuit 20 has holes aligned with the positioning of the fixing bosses 32. The fixing bosses 32 are inserted into the associated holes; the printed circuit 20 is assembled with the cradle 30 by soldering. The fixing bosses 32 are inserted into the holes of the printed circuit 20 so as to obtain electrical contact between the pins 103 of the sensor and the metal tracks of the printed circuit 20 through the opening 31.

[0053] Moreover, the cradle 30 acts as a thermal mass for the entire 3D electrical module 1. More particularly, it is a thermal interface for the sensor of the 3D electronic module. The cradle 30 is cooled by external cooling means not shown for the sake of simplification. The cooling means can be produced by different active means (heat pipe for example) or passive means (Peltier type device for example) which connect via the mechanical interfaces available on the 3D electronic module. Thus, the temperature of the cradle is maintained at a generally low target value in the context of the invention.

[0054] The thermal drainage part 40 comprises a base 41 and a protrusion 42 which extends from the base towards the underside of the sensor 10. The base 41 is fixed to at least one fixing boss 32 by gluing using a thermally conductive glue. This makes it possible to create at least one thermal contact point between the base 41 and the cradle acting as a thermal mass.

[0055] In addition, the protrusion 42 extends from the base until it reaches the lower face of the sensor 10 through a hole aligned with the positioning of the protrusion 42. The protrusion is inserted into the associated hole in the printed circuit 20 and its height is chosen so as to come into abutment with the lower face of the sensor 10. This makes it possible to create at least one thermal contact surface between the thermal drainage part 40 and the sensor 10 to be cooled. The contact surface between the protrusion 41 and the lower face of the sensor 10 is located in an area of ​​said face devoid of the pins 103.

[0056] Advantageously, the protrusion 41 has a flat upper surface. It is possible to fix the upper surface of the protrusion 42 to the lower face of the sensor 10 using a thermally conductive glue. This makes it possible to improve the mechanical robustness of the structure of the 3D electronic module.

[0057] This results in the creation of a heat evacuation circuit from the sensor 10 to the cradle 30 acting as a thermal mass. The introduction of the thermal drainage part 40 makes it possible to increase the heat exchange surface between the cradle 30 and the sensor 10. Thus, the invention makes it possible to reduce the thermal resistance between the cradle and the sensor without increasing the size of the 3D electronic module compared to a structure without thermal drainage.

[0058] Advantageously, the base 41 is composed of a plurality of arms secured to each other, more particularly two coplanar arms 412 and 411 which cross in the middle. The first arm 411 connects a first fixing boss to the fixing boss which is diagonally opposite it. The second arm 412 connects a second fixing boss to the fixing boss which is diagonally opposite it. The second fixing boss is adjacent to the first fixing boss. Each arm has at one end a flat surface bearing against the lower surface of the associated fixing boss. The end of each arm is fixed to the associated fixing boss by a thermally conductive adhesive. The use of the arms makes it possible to reduce the weight of the drainage part 40 without weakening the mechanical robustness of the part 40. The length of each of the arms 411 and 412 is greater than or equal to the length of the diagonal of the frame of the rigid cradle 30.

[0059] The two arms 412 and 411 are secured via a central intersection surface S0 common to the two arms. The protrusion 42 extends from said intersection surface S0 towards the sensor 10 mounted in the cradle.

[0060] [Fig. 1e] illustrates a sectional view of the electronic module according to the first embodiment in order to understand the heat evacuation path. The interface between the protrusion 42 and the lower face of the sensor 10 serves as a heat exchange surface to receive a portion of the amount of heat generated by the sensor during its operation. The amount of heat recovered at the interface 10 is propagated through the protrusion 42 and the arms 411 and 412 of the base 41 by thermal conduction. The thermal path created by the thermal drainage part 40 guides the heat towards the interfaces II and 12 between each arm of the base 41 and the associated fixing boss 31 of the cradle 30. We recall that the cradle is cooled by external cooling means. This then makes it possible to avoid overheating of the sensor 10 during its operation by evacuating the heat produced by the Joule effect. This thus makes it possible to maintain the sensor 10 at a target temperature and to minimize the thermal noise in said sensor.

[0061] In the first embodiment, the base 41 of the thermal drainage part 41 rests on the lower surfaces of the bosses 32. This makes it possible to improve the mechanical robustness of the 3D electronic module while minimizing the mechanical stress applied by the protuberance 42 on the sensor 10.

[0062] The length of the protrusion 42 is chosen so as to come into abutment with the lower face of the sensor 11 through the printed circuit 20 and the opening 31. Advantageously, it is possible to design the length of the protrusion 42 so as to obtain a volume of empty space V0 between the base 41 and the printed circuit 20. The empty space V0 can be used to house additional electronic components in order to obtain a more compact 3D electronic module.

[0063] [Fig. 1d] illustrates a perspective view of the thermal drainage part 40 alone according to the first embodiment of the invention. As a non-limiting example, the protrusion 42 is of parallelepipedal shape with a flat upper surface. The flat upper surface acts as a heat exchange surface with the sensor. Each of the arms 411 and 412 is of flat shape in order to improve the stability of the 3D electrical module after assembly. The flat shape at the ends of the arms makes it possible to produce an assembly where the arms 411 and 412 rest on the fixing bosses 32, while maximizing the heat exchange surface between the cradle 30 and the thermal drainage part 40.

[0064] The thermal drainage part 40 is made with thermally conductive materials such as metals (aluminum, steel, etc.), light metal alloys or thermally conductive polymers, or graphene.

[0065] [Fig.2a] illustrates a perspective view of the electronic module 1 according to a second embodiment of the invention. [Fig.2b] illustrates a sectional view of the electronic module according to the second embodiment of the invention. [Fig.2c] illustrates a perspective view of the thermal drainage part according to the second embodiment of the invention.

[0066] The second embodiment of the invention has the same characteristics as the first embodiment, with the exception of the shape of the ends of the arms 411 and 412 of the base 4L. The end of each of the arms 411, 412 forming the base 41 of the drainage part 40 has a shape complementary to that of the lateral surface of the associated fixing boss. By way of non-limiting example, if the fixing bosses are cylindrical in shape, the shape of the end of each arm is in the form of an arc of a circle as illustrated in [Fig.2c]. The thermal drainage part is assembled to the cradle in the following manner: the end of the arm in the form of an arc of a circle matches the lateral surface of the associated cylindrical fixing boss as illustrated in [Fig.2a]. This creates a sliding connection guided by the fixing bosses 32. The thermal drainage part is inserted inside the structure of the cradle until there is abutting contact between the top of the protuberance 42 and the lower face of the sensor 10.A thermally conductive adhesive is applied to the upper surface of the protrusion 42 in order to mechanically fix the thermal drainage part 40 to the integral assembly formed by the sensor 10, the printed circuit 20 and the cradle 30.

[0067] The length of the arms 411 and 412 is equal to the length of the diagonal of the cradle frame in order to be able to insert the base 41 in a slide guided by the fixing bosses 32.

[0068] The advantage of the second embodiment over the first is that it facilitates assembly since the thermal drainage part is centered by construction relative to the cradle frame.

[0069] [Fig.3a] illustrates a perceptual view of the thermal drainage part 41 according to a third embodiment of the invention. According to this embodiment, the arms 411 and 412 are further secured via a mechanical fixing part 43 in the form of a frame or ring connecting the arms 411, 412 together. This makes it possible to improve the mechanical robustness of the thermal drainage part. It is possible for the partial area of ​​the lower face of the sensor 10, aligned with the mechanical fixing part 43, to be devoid of connection pins. In this case, it is conceivable to produce one or more protrusions which extend from the mechanical fixing part 43 towards said partial area. Thus, the heat exchange surface is increased compared to the previous embodiments.

[0070] [Fig.3b] illustrates a perspective view of the thermal drainage part according to a fourth embodiment of the invention. In the fourth embodiment, the base is a plane comprising holes 420, 421, 422, 423 making it possible to lighten the part. In addition, this embodiment allows access to the components mounted in a volume of empty space V0 between the base 41 and the printed circuit 20. In addition, the holes make it possible to integrate components in the volume V0 having a height greater than that of the protuberance so as to exceed the base 4L

[0071] The advantage of the third and fourth embodiments compared to the previous embodiments thus consists of increasing the mechanical robustness and reduce thermal resistance.

[0072] More generally, the shape of the base 41 is not limited to a structure with several arms. It is possible to adapt the shape of the base according to the shape of the cradle frame (rectangular, circular, etc.). For example, it is possible to produce a base 41, in the form of a solid plane parallel to the lower face of the sensor, or a flat ring (or frame) connecting the boss supports of the cradle.

[0073] [Fig.4] illustrates a flowchart of the steps of the PI method for manufacturing an electronic module 1 according to the invention.

[0074] The first step i) consists of fixing the optoelectronic sensor 10 to the cradle 30 by gluing it to the edges of the central opening 31 using a thermally conductive glue. The sensor 10 is placed in the opening 31 of the frame of the cradle 30. The periphery of the lower face of the sensor 10 rests on a part of the peripheral surface of the opening 31. The sensor 10 is centered relative to said opening 31. This produces the mechanical assembly between the sensor 10 and the cradle 30.

[0075] The second step ii) consists of drilling the printed circuit 20 to make holes aligned with the fixing bosses 32 of the cradle and the at least one protuberance 42 of the drainage part 40.

[0076] Alternatively, it is possible to use a printed circuit 20 pre-labeled by the manufacturer.

[0077] The third step iii) consists of assembling the assembly formed by the sensor 10 and the cradle 30 to the printed circuit 20 by inserting the fixing bosses 32 into the dedicated holes. The cradle 30 is inserted into the printed circuit 20 through the holes associated with the bosses until the pins 103 of the sensor make contact with the metal tracks of the printed circuit 20.

[0078] . The assembly of the printed circuit 20 to the sensor 10 is then carried out by soldering. pins on the metal tracks of the printed circuit board.

[0079] The fourth step iv) consists of assembling the assembly formed by the optoelectronic sensor 10, the cradle 30 and the printed circuit 20 to the thermal drainage part 40. This step is carried out by inserting the protrusion 32 into the dedicated hole through the printed circuit 20 until there is abutting contact between the top of the protrusion 40 and the lower face of the sensor 10. The ends of the base 41 are assembled to the fixing bosses 32 using a thermally conductive glue. It is possible to apply the thermally conductive glue to the upper surface of the protrusion 42 in contact with the lower face of the sensor 10.

[0080] Optionally, the PI method comprises a step of molding the optoelectronic sensor 10 in an epoxy resin after the first step i) so as to reinforce the mechanical connection between the sensor and the cradle.

[0081] Optionally, the PI process comprises a resin molding step of the assembly formed by the sensor, the cradle, the printed circuit board and the drainage part. This helps protect the entire assembled structure.

Claims

Claims

1. Thermal drainage part (40) made of a thermally conductive material and intended to thermally connect an optoelectronic sensor (10) to a rigid cradle (30) cooled by external cooling means; the optoelectronic sensor (10) being mounted on a printed circuit (20); the cradle having at least one fixing boss (32) and an opening (31) intended to house the optoelectronic sensor (10); said thermal drainage part (40) comprising: - a base (41) intended to be placed in thermal contact with at least one fixing boss (32) of the cradle; - a protuberance (42) intended to be placed in thermal contact with a lower face of the optoelectronic sensor (10) through a hole passing through the printed circuit (20).

2. Thermal drainage part (40) according to claim 1 in which the base (41) is composed of one or more arms (411, 412) integral with each other.

3. Thermal drainage part (40) according to claim 2 in which the arms (411,412) are coplanar along a first plane (PI).

4. Thermal drainage part (40) according to claim 3 in which the arms (411, 412) are integral via a common central intersection surface (S0).

5. A thermal drainage part (40) according to claim 4 wherein the protrusion (42) extends from the central intersecting surface.

6. Thermal drainage part (40) according to any one of claims 2 to 5 in which the arms (411, 412) are secured via a mechanical fixing part (43) in the form of a frame or ring connecting the arms (411, 412) together.

7. A thermal drainage part (40) according to claim 6 wherein the protrusion (42) extends from the mechanical fixing part (43).

8. A thermal drainage part (40) according to any one of claims 1 to 7 wherein the protrusion (42) has a first planar upper surface.

9. A thermal drainage part (40) according to any one of claims 2 to 8 wherein each arm (411,412) comprises at least one end having a second upper surface intended to be bonded to the base of the associated fixing boss.

10. A thermal drainage part (40) according to any one of claims 2 to 8 wherein each arm (411,412) comprises at least one end having a shape complementary to that of the lateral surface of the associated fixing boss.

11. 3D electronic module (1) comprising: - an optoelectronic sensor (10) mounted on a printed circuit (20) - a rigid cradle (30) cooled by external cooling means; the cradle having a central opening (31) intended to house the optoelectronic sensor and having at least one fixing boss (32), - a thermal drainage part (40) according to any one of the preceding claims.

12. 3D electronic module (1) according to claim 11 in which the optoelectronic sensor (10) comprises a housing (101) in which is housed a photosensitive chip (102) with a flat active face, with on the opposite face of the housing (101) electrical connection pins (103) connected to the printed circuit (20) through the opening (31).

13. 3D electronic module (1) according to any one of claims 11 to 12 in which the height of the protuberance is chosen so as to obtain a volume of empty space (V0) between the base (41) and the printed circuit (20).

14. 3D electronic module (1) according to any one of claims 11 or 13 in which the sensor (10) is molded in an epoxy resin.

15. Manufacturing method (PI) of a 3D electronic module (1) according to any one of claims 11 to 14 comprising the following steps: i. fixing the optoelectronic sensor (10) to the cradle (30) by gluing on the edges of the central opening (31) using a thermally conductive glue. ii. drilling the printed circuit (20) to make holes aligned with the fixing bosses (32) of the cradle and the protuberance of the drainage part. iii. Assembling the assembly formed by the optoelectronic sensor (10) and the cradle (30) to the printed circuit (20) after insertion fixing bosses (32) in the dedicated holes. iv. Assemble the assembly formed by the optoelectronic sensor (10), the cradle (30) and printed circuit (20) to the thermal drainage part by inserting the protrusion (32) into the dedicated hole and by gluing the ends of the base (41) to the support bosses (32) using a thermally conductive glue.

16. Manufacturing method (PI) according to the preceding claim for producing a 3D electronic module according to claim 14 further comprising a step of molding an optoelectronic sensor (10) in an epoxy resin after the fixing step i).