Copper-Plated Graphite Fins to Enable Manufacturable High-Reliability, High-Performance Parallel Plate Heat Exchangers
Publication Date: 2015-Nov-04
The IP.com Prior Art Database
Described is the use of copper-plated graphite fins to enhance the thermal performance of parallel plate heat exchangers with minimal impact to current manufacturing technologies, hardware, or process.
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-Performance Parallel Plate Heat Exchangers
Performance Parallel Plate Heat Exchangers
Recent server thermal development work highlighted a need for better performing heatsinks; many modern servers include multiple high-power chips dissipating 250+ watts each. It is well documented in material science that carbon-based conductors perform extremely well in heat spreading applications and as such have been used effectively in a variety of heat dissipating applications. Some companies with low reliability requirements have begun coating their heatsinks with carbon in order to aid in spreading the heat more effectively and thus reducing the overall resistance of the heatsink. Unfortunately, this is not an option for enterprise class systems with strict reliability requirements; the carbon represents a high shorting risk as flaking and particulate matter is commonly blown or rubbed off the heatsink, and these unwanted contaminants now flying through the server are electrically conductive and will cause shorts in the system. This disclosure proposes a system of carbon-based sheets clad with copper (electroplating) to realize the performance gains of carbon, but without compromising reliability. When applied to a parallel plate heat exchanger, the sheet-metal fins may be wholly replaced by the copper-plated graphite/carbon fins as the full outer surface is still solderable.
A typical parallel plate heat exchanger is composed of a base, with heat pipes soldered into it, extending up into a stack of fins. The fins are simply thin plates of aluminum or copper with holes in the plate which are soldered to hold the heatpipes. This construction is quite effective due to the good thermal contact enabled by the solder joints and the efficiency of heat pipes in moving heat into the fins. The system of this article is a heatsink utilizing both heat pipes and carbon materials for maximum heatsink conductivity. Plates of copper material are created in the desired fin shapes before being first being drilled with the required holes to mate to the heat pipes. The fins are then electroplated with copper which serves the dual purpose of both creating robust exterior layer of a ductile material that is resistant to brittle fracture and creates a surface that is easily soldered to just like a traditional copper or aluminum fin in a parallel plate heatsink.
The number of heatpipes is determined mostly by two distinct parameters; the first is the heat carrying capacity of the heatpipe, which is a function of the heatpipe diameter. The total heat carrying capacity of all the heatpipes in the heat exchanger must exceed the greatest possible heat output of the item requiring cooling in order to prevent dry-out and thermal run-away. The other factor in determining the number of heatpipes is the available area for the fins; the heatpipes must be dispersed evenly within the fin volume in order to attempt to make the most uniform distribution of heat throu...