If the thermal performance of a system can no longer be achieved by air cooling then liquid cooling is a natural evolution.

Columbia-Staver offer several different Liquid cold plate technologies including, Tube in Plate, Gun Drilled & Brazed. The Tube-in Plate technology has been developed to offer a simple design.

These cold plates are very cost-effective and offer good heat removal performance for components with low-to-medium power densities.

Typical applications

Tube in Plate cold plate applications would include:

• Power electronics
• RF generators and transmitters
• Semiconductor processing equipment
• Uninterruptible power supplies

This technology is possibly the simplest form of cold plate and consists of a joint free tube that is embedded into a copper or aluminium carrier plate.

Depending on the required thermal performance and the cooling fluid to be used the tube can be copper or stainless steel and the attachment method can be a simple mechanical (dry) press fit, press fit with a thermal epoxy boundary to eliminate micro voids or for superior performance soldered.

There are also several different ways of embedding the tube each with a cost performance advantage.

Standard embedding

This is the lowest cost but also lowest performing Tube in Plate cold plate as the heat has to penetrate several thermal interfaces in order to get into the cooling fluid. Manufacturing costs are however low as the tube can remain in its round cross section form.

Surface contact embedding

This embedding technique ensures that the thermal resistance between the device and the cooling fluid is kept to a minimum. The cooling tube is flattened and is in direct contact with the base of the device. Performance can be further enhanced by the addition of a High Conductive epoxy layer between the tube and the carrier plate, this eliminates micro-voids. Best possible performance would be achieved if the tube is soldered in place but this requires that the carrier plate is Nickle plated adding production time and cost.

Clam shell Embedding

In circumstances where components are required to be mounted on both sides of the cold plate and require the same thermal performance the tube can be sandwiched between an upper and lower carrier plate. This also allows for the cold plate to have surface features to accommodate PCB landscapes.

Advanced Tube in Plate designs

In most cases the tube in a Tubs in Plate design is a continuous joint free tube is one piece from fluid inlet to fluid outlet. This reduces the risk of any leakage but also has a graduated thermal profile as the cooling fluid gets progressively hotter thereby presenting the last component with a different coolant temperature than the first.

This drawback can be somewhat reduced by constructing a Multi-Pass design where the cooling fluid can be looped back through the cold plate or a separate fluid feed can travel in the opposite direction to the first.

Another method of improving the Thermal profile offered to all components is to design a Tube in Plate cold plate with inlet and out let headers. This divides the incoming cooling fluid into parallel tubes that offer a much more even Thermal profile.