CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of French Patent Application No. 1902830 filed Mar. 19, 2019, the disclosure of which is herein incorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is that of memory module cooling systems.

This invention relates to a cooling system for memory modules and in particular for memory modules for compute blades mountable in the rack of a rack system.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Compute blades for rack systems may for example comprise processors, graphics cards, random access memory such as memory module, mass storage such as hard disks. These compute blades are for example used to perform high-performance computing; the components thereof, therefore, give off heat during operation and need to be cooled to ensure their proper operation and durability.

Since they are rack-mounted, there is not enough air circulation within the rack systems to effectively cool the compute blades using air cooling systems.

For this reason, fluid cooling systems have been developed. These cooling systems comprise, for example, pipes, usually made of copper, in which a fluid circulates. These pipes can be connected directly to the components to be cooled, for example by forming a loop around the components. The fluid can also circulate between two plates, for example made of metal, at least one of the two plates being directly connected to a component to be cooled. It is also possible to braze channels inside a metal plate, e.g. copper, to have fluid flow through them. The fluid can thus flow within a metal plate connected to a component, for example along a memory module.

These fluid cooling systems are bulky since they require a gap around the components for the metal plates accommodating the fluid.

Other hybrid cooling systems exist, which have the advantages of fluid cooling and those of dry contact cooling. This is the case, for example, of patent FR2966318, entitled “Carte électronique pourvue d'un système de refroidissement liquide” (Electronic board provided with a liquid cooling system), which proposes a cooling system comprising a cooling module in which a cooling liquid circulates, and a detachable conductive heatsink, placed in contact with the surfaces of an electronic component through a thermal material to recover the heat energy produced by the component, the heatsink being in dry contact with the cooling module in a detachable manner, for example by screws. This system known from the state of the art is shown inFIG. 1. This system allows to have reduced bulk around the component, since no fluid flows around the component.

FIG. 1shows a cooling system according to the state of the art.

Thus, in the cooling system100shown inFIG. 1, the heat energy produced by the electronic component110is recovered by the heatsink120through a heat pad and then transferred to the cooling module130through the dry contact points140. The heatsink120and the cooling module130are held together by screws150by dry contact. This makes the heatsink120detachable, allowing access to the component110. The only point of contact between the heatsink120and the cooling module130is, therefore, the dry contact point140.

The cooling module13is also called “cold plate” and can for example be made of metal, for example aluminum. This cold plate can, for example, extend along the entire compute blade and at least some of the compute blade components can be connected to it. The electronic component11can for example be a memory module.

By “memory module” is meant an electronic component with a random access memory for storing and erasing information processed by a computing device. “Random access memory” means a memory with short access time and that is volatile, i.e., resulting in the loss of all data in memory when it is no longer powered.

As technology advances, there is a need to integrate more random access memory on a compute blade of the same restricted dimension. One solution can be to increase the memory capacity of the memory modules cooled by the system100of the state of the art. However, since the cost of a memory module relative to its capacity is not linear, increasing the capacity of a memory module results in a much greater proportional increase in its cost. The cost of a compute blade therefore increases very significantly with this solution. A second solution is to increase the number of memory modules on a compute blade, in order to have more random access memory per processor while limiting the cost by having memory modules of smaller capacity which are therefore less expensive.

However, the dimensions of a compute blade that can be mounted in the rack of a rack system are constrained, in particular by the 19-inch standard. Indeed, the total width of the subrack in the rack of rack systems of the state of the art is 482.6 mm, i.e. 19 inches including mounting brackets. This width is the basis for the 19-inch mounting system. Thus, the width of the elements accommodated by the rack of rack systems of the state of the art complies with this 19-inch standard, and the compute blade therefore has restricted dimensions.

In addition, the heatsink12of the prior art requires a distance between two components11placed side by side. This distance is due, on the one hand, to the bulk of the heat pad separating the component11and the heatsink12. On the other hand, this distance is necessary to be able to surround the component11with the heatsink12when mounting the component11and the heatsink12, or to be able to remove the heatsink12from the component11in order to access the component11. This distance is, for example, around 11 millimeters if the components11are memory modules.

However, the current memory module connectors, which allow a memory module to be connected to an electronic board of a compute blade, allow a minimum distance of 8 millimeters between two connectors. This distance is also necessary in particular to comply with routing rules.

It is therefore not possible to reduce the distance between two memory modules to increase the number of memory modules in a compute blade of restricted dimension while using the cooling system100of the state of the art.

In addition, the cooling system10of the state of the art is expensive to manufacture as it requires at least two screws and several copper plates for each component11.

Therefore, there is a need for a cooling system for memory modules that allows to keep the minimum distance between two memory modules while using fluid cooling and that is less expensive than the cooling systems of the state of the art.

SUMMARY OF THE INVENTION

The invention offers a solution to the above-mentioned problems by allowing efficient cooling of several memory modules separated by a distance smaller than the distance between two memory modules according to the prior art, and thus allowing more memory modules on a compute blade of restricted dimensions while enabling less expensive manufacturing.

One aspect of the invention thus relates to a heatsink for a plurality of memory modules connectable to an electronic board, said electronic board comprising at least one fluid cooling system and at least one first connector for each memory module of the plurality of memory modules, each memory module comprising at least one second connector configured to be connected to the at least one first connector of the electronic board and two heat exchange surfaces, characterized in that:the heatsink comprises at least one envelope, said envelope comprising:a top surface configured to at least partially cover the top part of each memory module of the plurality of memory modules,at least two outer tabs, each outer tab being configured to be in thermal contact with at least one heat exchange surface of the two heat exchange surfaces of at least one memory module of the plurality of memory modules,at least one contact surface, configured to be in thermal contact with said fluid cooling system of said electronic board when each memory module of the plurality of memory modules is connected to said electronic board,at least one inner tab, configured to be interposed between two memory modules of the plurality of memory modules in order to make thermal contact with at least one heat exchange surface among the two heat exchange surfaces of each of the two memory modules,said envelope is configured to be detachably placed against the two exchange surfaces of each memory module of the plurality of memory modules,said envelope is configured to be mechanically detachably fastened to said electronic board when each memory module of the plurality of memory modules is connected to said electronic board.

The invention advantageously allows to reduce the distance between two memory modules, by advantageously having a single inner heatsink tab interposed between two memory modules. This allows more memory modules to be placed on an electronic board of the same dimension as an electronic board of the state of the art.

By virtue of the invention, it is possible to cool several memory modules with a single heatsink, advantageously enabling a lower manufacturing cost.

The top surface configured to cover each memory module advantageously allows to have the shortest possible thermal path between the cold source and each of the memory modules without having the cold source between the memory modules.

Advantageously, the heatsink envelope is detachable, allowing easy access to the memory modules, for example, to replace a memory module when it fails or when capacity increase is desired.

The invention advantageously allows, by having an inner tab in thermal contact with at least one surface of each of the two memory modules between which it is interposed, to capture a large part of the heat emitted by the two modules.

Comprising a contact surface in thermal contact with the fluid cooling system of the electronic board when the memory modules with which it is in contact are connected to the electronic board, i.e. when they are in operation and, therefore, when they heat up, the heatsink allows to redirect the heat from all the memory modules with which it is in contact to the fluid cooling system.

Thus, by capturing and redirecting the heat emitted by the memory modules with which it is in contact, the heatsink alone allows to ensure the durability and proper operation of several memory modules.

Thermal contact of the heatsink envelope with the fluid cooling system advantageously allows to have no fluid to circulate around the memory modules. Thus, problems of bulk associated for example with the inlet and outlet lines for a liquid of the state of the art solutions are avoided. This allows to have a reduced distance between the memory modules.

In addition to the characteristics which have just been mentioned in the preceding paragraph, the heatsink, according to one aspect of the invention, may have one or more of the following complementary characteristics, considered individually or in any technically possible combinations:The heatsink further comprises a plurality of thermal interfaces, each thermal interface being interposed either between an exchange surface of a memory module of the plurality of memory modules and an outer tab of the envelope, or between an exchange surface of a memory module of the plurality of memory modules and an inner tab of the envelope.The at least one top surface, the at least two outer tabs and the at least one inner tab of the heatsink are arranged so as to form, for each memory module of the plurality of memory modules, a gap adapted to receive the memory module.The heatsink comprises two contact surfaces, each contact surface being in thermal contact with the fluid cooling system.The heatsink comprises two top surfaces.The heatsink further comprises a heat pipe configured to be in thermal contact with the contact surface and with the outer tab of the heatsink envelope furthest from the contact surface.

The thermal interfaces allow not to damage the memory modules when the envelope is inserted and to produce more efficient thermal contact.

By comprising two contact surfaces each in thermal contact with the fluid cooling system, the heatsink according to the invention allows better cooling of the plurality of memory modules.

One advantage of comprising a heat pipe is that the heatsink according to the invention can better cool the memory modules furthest from the fluid cooling system.

Another aspect of the invention relates to an electronic board comprising at least one fluid cooling system, a plurality of memory modules, at least one first electrical connector for each memory module, each memory module comprising at least one second connector configured to be connected to at least one first connector of the electronic board and the heatsink according to the invention.

The invention and its various applications will be better understood after reading the following description and examining the accompanying figures.

