Brief description and key facts about the three most common types of heat pipes.
#1 Standard Heat Pipes
Standard heat pipes are the most commonly recognized type. These devices typically feature a copper enclosure with a sintered copper wick covering the internal walls and water as the working fluid. Variations exist with different materials, fluids, and wick types.
Fast Facts:
- Thermal conductivity increases with length.
- Maximum heat transfer (Qmax) is additive; for example, multiple 3-20W pipes can transfer up to 60W.
Applications: Ones where required heat sink thermal resistance is below 0.5 C/W and heat needs to be moved distances farther than 50mm or so.
Standard Heat Pipe Inner Workings
#2 Vapor Chambers
Vapor chambers are designed for planar heat spreading. While they share similarities with standard heat pipes — copper enclosures, sintered wicks, and water as the working fluid — they excel at spreading heat across a large surface area. They come in two main types: traditional 2-piece designs and cost-effective 1-piece designs.
Fast Facts:
- 1-piece vapor chambers can be bent into L or U shapes along the Z-axis and are less expensive than traditional 2-piece vapor chamber designs.
- Lower thermal conductivity due to a large cross-sectional area compared to heat pipes but superior performance in reducing temperature rise (delta-T).
Applications: Ones where IC heat needs to be spread across a larger surface area, power density is high, and when heat pipes can’t meet thermal requirements.
Traditional 2-Piece and Low Cost 1-Piece Vapor Chambers
#3 Thermosiphons
Thermosiphons are wickless heat pipes, often featuring a grooved design or localized sintered material to aid fluid return. They excel in transporting heat over long distances but require a gravity-aided setup, with the condenser above the evaporator.
Fast Facts:
- Can transfer up to three times the heat of a standard heat pipe of the same size.
- Effective over distances exceeding 20 meters.
Applications: Suitable for industrial and large-scale systems where long-distance heat transfer is required.
Wickless (L) and Partial Wick (R) Thermosyphons
