The Impact of Using Different Technologies in Liquid Cold Plate Fabrication
Liquid cold plate prices can vary quite a bit; understanding why can help you cut costs and still obtain the performance you need to properly cool your application. The two biggest cost drivers in cold plate manufacturing are thermal performance requirements and annual demand, which generally thermal engineers and manufacturing engineers have little or no control over. However, you can reduce costs by understanding how roughness, flatness, hardness, surface topography, mounting features, and liquid connections specifications can all affect the cost of a cold plate. By involving your cold plate manufacturer early in the design process, you'll be able to identify the manufacturing cost drivers and select the most cost effective design.
Most cold plates are made of aluminum but some new technologies use copper. Although copper has better thermal conductivity, aluminum is used more often because it is usually cheaper, lighter, and easier to work with. Machining copper is very difficult and expensive. If aluminum meets the thermal performance specifications, it is generally the best material to use.
Two of the most popular aluminum cold plate technologies are tubed and vacuum-brazed (See Figure 1). Tubed cold plates are usually copper or stainless steel tubes pressed into a channeled aluminum extrusion. They are cost-effective and offer good bulk heat removal for low-to-medium watt densities. Vacuum-brazed cold plates consist of two plates metallurgically bonded together with internal fin. They are available in all sizes and offer extremely high performance, making them ideal for applications where heat loads are concentrated. Labor time is limited with both tubed and vacuum-brazed cold plate technologies. For that reason, U.S. cold plate manufacturers tend to be competitive with offshore manufacturers for moderate volumes. The lower labor cost reduction from buying offshore is typically offset by shipping and customs costs, and additional inventory associated with long transport times. The threshold quantity for offshore savings is usually about 10,000 cold plates or more per year.
The biggest cost drivers for aluminum cold plates, after those mentioned above, are machining time and additional processing steps. Cold plate manufacturers typically have a cost associated with machining time which covers depreciation costs of the machine, power, supplies, and maintenance. Therefore, the longer the cold plate sits in the machine the more costly it is. Each additional processing step continues to drive the cost up.