Electronics continue to get smaller. The more the power demands continue to increase. In between, engineers are finding running out of methods to keep parts cool by air alone.
Liquid cooling comes in handy here. But, one key element lives at the heart of most liquid cooling systems—the cold plate. The liquid cold plate design is not an option — it can often be the difference between a system that can handle its workload without a problem and a system that slows down when it's called to jobs. This precision engineering is what companies such as PT Heatsink have labored on over the years to create thermal solutions. It is beneficial to know what constitutes an effective cold plate design before making a move toward a cooling strategy.
Traditional heat sinks work well for a lot of applications. However, beyond a certain point, air is not able to remove heat from the power source quickly enough.
Heat loads are found in high power computing systems, industrial lasers, EV battery packs and servers, where air cannot effectively dissipate the heat. Liquid is much more effective at transferring heat than air, due to its thermal capacity. That's why cold plates are there.
The cold plate is basically a metal block that has internal channels. These channels are filled with liquid coolant which absorbs heat from the component that it is set against, and then transfers this heat to the radiator or heat exchanger. Simple in concept. Difficult to execute correctly.
The internal channel pattern has a significant influence on the efficiency of the heat transfer into the coolant. Channels that are straight are simple to produce but not always the most efficient. Serpentine paths, pin fin structures, and designs for micro channels can have a significant impact on the performance, but also involve more sophisticated manufacturing capability.
A properly designed plate provides a compromise between heat transfer and pressure drop. If you have too much resistance in the channels, then your pump will have to work harder, and this adds to the cost and noise of the system.
The materials used for most cold plates are copper, aluminum or a combination of these materials. Copper has better heat conductivity, but is heavier and more expensive. Aluminum is lighter and cheaper but not as thermally efficient.
That is where it becomes important to work with experienced aluminium extrusion suppliers, particularly in the context of aluminium based cold plates which require close tolerances and uniformity of wall thickness. Shoddy extrusion work may lead to weak spots or irregular surfaces, which may affect the efficiency of contact with the cooled component.
The best internal channel designs will get you little help if the surface of the plate isn't parallel to the surface of the part being cooled. Thermal resistance is created at the microscopic level, making the liquid cooling pointless in the first place. The precise manufacturing of the internal geometry is of equal importance as the correct surface finishing.
A cold plate is not isolated! It needs to be compatible with pumps, tubing, radiators and coolant chemistry. It's easy to produce a design that appears good on paper, but it doesn't function well if it wasn't designed in the context of the rest of the loop.