Interconnection
How quick disconnect connectors ensure reliable liquid cooling systems in AI data centres
By Rolf Horn, applications engineer at DigiKey T
he deployment of artificial intelligence (AI) is increasing the demand for high-performance data centres and advanced computing infrastructure. These systems generate significant heat, and designers are finding traditional convection and forced-air cooling increasingly inadequate to meet their thermal management requirements. For next- generation computing centres, designers are turning to liquid cooling for its highly efficient heat dissipation. The challenge for designers is that computing systems need to be scaled, modified, maintained, and replaced without dismantling the cooling system.
Part of the solution lies in liquid cooling connectors that can be quickly connected or disconnected, enabling efficient cooling without sacrificing maintenance flexibility or modular expandability. Such connectors need to be compact, reliable, corrosion resistant, leak-free, and easy to use, with high mating-cycle durability. This article provides a brief overview of the challenges designers of AI infrastructure cooling systems face. It then introduces quick-disconnect (QD) liquid cooling connectors from Amphenol and shows how to select and apply them to address these challenges.
Quick disconnects
Liquid cooling for electronics, at its most basic, uses a coolant circulating under pressure to cool electronic devices mounted on cold plates and connected to external heat exchangers. The heated coolant exits the cold plate and is circulated to the heat exchanger, where it is cooled and then recirculated. When multiple devices need to be cooled, manifolds distribute coolant
38 September 2026
Figure 1: Shown are examples of a liquid cooling UQD plug and UQDB socket illustrating their mating action. (Image source: Amphenol)
close before the seal is broken, sealing the coolant channel and preventing leakage.
UQD Socket UQDB Socket
to each cold plate. Common coolants include deionized water, ethylene glycol, and propylene glycol. These coolants are nonconductive, preventing damage to powered electronics in the case of a leak. Each heat exchanger needs both an input cold line and an output hot line. The tricky part is designing the system so the cold plate and electronic device can be removed without disassembling the cooling system. This is where QD connectors come in (Figure 1). These universal QD (UQD) plug and blind mount (UQDB) socket devices allow coolant lines to be separated without leaking. Available in multiple sizes, terminations, and connection configurations, these connectors help designers integrate coolant connections across a wide range of industrial and data centre architectures. The UQDB sockets are designed to blind mate with the UQD plug in enclosed racks without access to the back of the cabinet. The plug and socket are each mounted on their respective cold
Components in Electronics
plate at defined locations using threaded studs. O-rings seal the QD body to the mounting surface. Each cold plate has two QD connectors: one for the cold coolant and one for the heated return coolant. When the server or other electronic device is installed, the socket, with its conical opening, guides the plug into the mated configuration. The QD connectors are generally marked with identification rings: blue for cold lines, and red for warm returns.
These QD connectors feature a dry disconnect operation that seals against coolant leaks when uncoupled. They contain internal valves that remain closed during coupling until the mating halves are fully engaged, then open for maximum coolant flow. When uncoupled, the valves
Open Compute Project The Open Compute Project (OCP) is an organisation that applies the benefits of open source and open collaboration to hardware development, accelerating innovation in the computer industry. Cooling systems are one of their areas of concern. They have released UQD and UQDB specifications, which describe the characteristics of these connectors. The OCP specifies QD devices in four sizes: UQD02, UQD04, UQD06, and UQD08 (and UQDB02, UQDB04, UQDB06, and UQDB08). The number in the designation indicates the fluid opening diameter and corresponds to 1/8”, 1/4”, 3/8”, and 1/2”, respectively. The fluid opening determines the connector’s maximum flow rate.
Single source for QD connectors For designers of liquid cooling systems, it is efficient to have a reliable single source of QD connectors.
Amphenol has introduced a series of UQD/UQDB pairs in a wide range of OCP sizes, mounting options, and terminations. They are engineered for rugged environments common in data centre applications. The shell material for all components in this family is stainless steel. The internal components exposed to the coolant, such as internal springs, are made of corrosion- resistant stainless steel. They are designed to work with widely used coolants, and all components in the
Figure 2: The UQDBP-02TMU01-N000 is an OCP- compliant UQDB02 plug with an external threaded stud for termination. (Image source: Amphenol)
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