Heat Sinks

Liquid cooled heat sinks provide the highest thermal performance per unit volume and when optimally designed can exhibit a very low thermal resistance. Liquid heat sinks can be constructed by soldering copper tubing on to a flat copper plate or by drilling holes in a metal block through which water may pass. With greater complexity and greater thermal performance an elaborate serpentine water channel may be milled in a copper or aluminum block that later is sealed off. While liquid cooling may be considered undesirable and /or unsatisfactory for many applications it may be the only viable approach in specific situations. Liquid cooling, in addition to being compact, keeps noise to a minimum and can increase semiconductor life due to reduced temperatures. We can also provide chiller units for complete cooling systems.

We commonly use several cold plate construction methods:

• Two Piece Gasket.
• Full Buried Tube.
• Sandwich Design.
• Exposed Tube.
• Deep Drilled.
• Half Buried Tube.
• Aluma Cop.
• Two Piece Brazed.

Sizes of these plates range from a few centimeters to slightly more than 2 meters.

For maximum power heat transfer we offer Powder Type heat pipes. These come in standard lengths from 150 to 300 mm. Tube diameters range from 2 to 8 mm with maximum power capacity of 45 watts.

Tubes can be flattened in order to stack several heat pipe into a very tight space in order to increase heat carrying capacity of an assembly. Heat pipes are typically supplies as a finished assembly integrated with a plate and fins (corrugated, or zipper fins are most common)

Advantage of Powder Type Heat Pipes
• The best for heat transfer.
• Better quality reliability.
• Workable for any operation direction
• Easy for bending and flatten.

Disadvantage
• Higher cost.
• Difficult to produce.
• Flattening limitation (2mm)

The above drawing depicts basic heat pipe construction and theory of operation.

In general a heat pipe consists of a sealed usually aluminum or copper tube, a wicking structure and a few cc’s of fluid under pressure. When heat is applied to a point along the length of the heat pipe the liquid at that point will boil into a vapor. By boiling, the liquid extracts heat through vaporization (turning into a gas). As a gas, this vapor travels to the cold side of the heat pipe and condenses back into a fluid. This fluid then moves back through the wicking structure and the process is repeated.