Method of manufacturing a brazed micro-channel cold plate heat exchanger assembly

Abstract

The invention relates to a method of making a brazed micro-channel cold plate assembly for cooling a heat producing electronic component. The primary components of a cold plate assembly are a base plate, a manifold cover, and inlet / outlet pipes; wherein the individual components are assembled and brazed into an integral unit. The joining surfaces of the individual components have novel features that provide for permanent bonding of the joints by brazing and a hermetic seal along the joint seams. The novel features also forestall excess braze alloy from contaminating the interior surfaces of the assembled cold plate and obstructing the engineered flow channels.

Description

TECHNICAL FIELD OF INVENTION[0001]The invention relates to a method of making a brazed micro-channel cold plate assembly for cooling a heat producing electronic component.BACKGROUND OF INVENTION[0002]Recirculating closed-loop liquid cooling systems are used for cooling heat generating electronic components such as computer processing units (CPU). Shown in FIG. 1 is a typical recirculating closed-loop liquid cooling system 10 known in the art that includes a reservoir tank 15, a coolant pump 22, a cold plate 25, a radiator 35, and a fan 40, wherein the cold plate 25 is in thermal contact with a heat generating electronic component 30.[0003]In reference to FIG. 1, the coolant pump 22 transfers a liquid coolant from the reservoir tank 15 to the cold plate 25. Within the cold plate 25 are engineered channels through which the coolant flows for optimized transfer of excess heat from the electronic component 30 to the coolant. After exiting the cold plate 25, the hot coolant continues to ...

AI Technical Summary

Benefits of technology

[0019]An advantage of the present invention allows the individual components of a micro-channel cold plate to be assembled, permanently bonded, and hermetically sealed by conventional means that is predictable and cost effective.

[0020]Another advantage of the present invention is that the combination of novel features on the joining surfaces of the base plate, manifold cover, and inlet / outlet pipes allows a micro-channel cold plate to be permanently bonded by brazing without braze alloy clogging or jeopardizing the coolant flow in the micro-channels.

[0021]Still another advantage of the present invention is that the combination of novel features on the individual components provides for a robust hermetic seal along the joining surfaces for the designed life of the micro-channel cold plate.

[0022]Further features and advantages of the invention will appear more clearly on a reading of the following detail description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.

Problems solved by technology

The multiple crossing interfaces between the bottom coplanar edges of the manifold channels and the top coplanar edges of the micro-fins have to be held to very close tolerances to prevent any bypass flow of coolant, which would cause reduced heat transfer efficiency.

Any liquid coolant leakage from the cold plate assembly will severely damage the electronic component for which it is designed to cool, as well as any other components which the coolant may come into contact with.

Also, any air introduced into the closed-loop system may risk lowering the performance of the coolant pump 22, creating unacceptable noise during the operation of the pump, and lowering heat transfer efficiency.

In addition, the presence of air in the system would reduce the volume of the initial coolant charge, resulting in reduced heat transfer efficiency.

Known methods of permanently bonding and hermetically sealing the base plate and inlet / outlet pipes to the manifold cover have been known to fail over prolonged use or can be too complex and expensive to be manufactured.

Due to the compact size of a typical cold plate required for cooling electronic components, typically in the neighborhood of 40 mm to 50 mm in diameter, the heat required to weld diminutive metal components may warp the cold plate assembly causing the coplanar edges of the micro-fins and the coplanar edges of the alternating channels to lose intimate contact and results in a non-functional unit.

Furthermore, the use of elastomer has proven to be unreliable where the elastomer along the joining surfaces has failed after prolonged temperature cycling.

Resistance welding provides for a permanent bond and hermetic seal for the usable life of the cold plate; however, resistant welding may not be cost effective.

Besides the suitable material, the joining surfaces of the base plate, inlet / outlet pipes, and manifold cover have to be precision machined to exact specifications resulting in complexity and cost of manufacturing.

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