Amphenol FCI (AFCI) is a developer and manufacturer of connector and cable assembly solutions for industries as diverse as telecommunications, data storage, servers and consumer electronics. In a recent project, the Berlin-based company equipped a data center with high-speed modules for optical interfaces with a data rate of 300 Gbps. One of the tasks at hand was to ensure reliable cooling of the high-performance servers.

To this end, the people responsible at AFCI were looking for a supplier of heat sinks and found what they were looking for in CTX Thermal Solutions. The company specializes in cooling solutions for a wide range of applications, including cooling solutions for automotive, household and consumer electronics as well as industrial power supplies and computers. The heat sink portfolio, which ranges from cooling elements for SMD components measuring just a few millimetres and weighing just a few grams to liquid heat sinks weighing 200 kg for inverters in railroads, includes special pin heat sinks for maximum cooling performance. These provide heat dissipation for LED applications or BGA designs, for example, and met AFCI's requirements for equipping the data center.

Production using the cold extrusion process

The optical fibers of the pin heat sinks from CTX Thermal Solutions are arranged parallel to the air flow.

© CTX Thermal Solutions

The pin heat sinks are manufactured from pure aluminum (Al99.5/1070) or pure copper (CU1100/CU1020) using the cold extrusion process. In the extrusion process, a flat metal blank, which has approximately the same volume as the finished product, is made to flow at room temperature under high pressure. The material successively fills all the cavities of the forming tool. As the special forming process prevents the formation of air bubbles and blowholes as well as the inclusion of foreign bodies, the material structure of cold extruded heat sinks is extremely homogeneous and dense. As a result, this structure increases the conductivity of the finished product in contrast to the raw material. In addition, the surface quality and dimensional accuracy are so high that mechanical post-treatment is only necessary in exceptional cases. Due to the high material density achieved by the manufacturing process, these pin heat sinks achieve significantly better thermal conductivity (>220 W/mk) than comparable extrusion or die-cast solutions. As a result, cold extruded pin heat sinks can be used for heat dissipation wherever high performance is required.

For the data center equipped by AFCI, simulations have shown that modules fitted with CTX pin heat sinks can be placed regardless of the flow direction and without having to adapt the cooling concept. This is particularly helpful when the direction of air movement is not clear in complex systems.

Air movement in three directions

The cold extrusion process is particularly suitable for the production of small, project-specific series, as it allows for high-precision shaping - from cylindrical pins and thin fins to square bar or hexagonal column shapes, anything is possible. The thickness of the cooling pins can be up to 0.7 mm, with a minimum distance between the individual pins of 1 mm. The thin and closely spaced fins significantly increase the cooling surface and thus support convection. As the air in cold extruded heat sinks also moves in three directions instead of just two dimensions as in extruded heat sinks with long cooling fins, their cooling capacity is higher.

Due to this material composition and the resulting thermal properties, the cold extruded pin heat sinks from CTX were interesting for AFCI's application. For the data center project, small pin heat sinks with thin and particularly long pins were required in order not to lose too much space in the area. In the case described, the surface area corresponded to a square of 18 mm x 18 mm. In order to maintain the convection surface and thus the cooling capacity, many thin pins had to be pressed to a height of 25 mm.

Author:
Arthur Brinkmann works in sales at CTX Thermal Solutions in Nettetal.