Fabrication and experimental evaluation of bendable copper flat-plate oscillating heat pipes

Recent technological advancements in the packaging and integration of electronics in compact systems have introduced a growing demand for efficient and thin heat spreading devices. For various applications, it would be further beneficial to have passive heat spreaders that are also bendable during assembly or end use. Traditional wick-based heat pipes are susceptible to performance degradation under bending due to their sensitive internal wick structures. Oscillating heat pipes (OHPs) are a wickless alternative, leveraging oscillating plug flows within simple channels or tubes, thereby offering a promising solution for bending-tolerant passive two-phase heat spreading. This work introduces the fabrication and testing of a submillimeter thick copper OHP device that maintains functionality under bending. The device is fabricated using an etching process that yields $\sim 250-300 \mu \mathrm{~m}$ deep and $1000 \mu \mathrm{~m}$ wide channels on a 500 $\mu \mathrm{m}$ thick copper substrate, masked with photoresist, using ferric chloride (FeCl3) etchant. Sealing is achieved through thermocompression bonding with a $127 \mu \mathrm{~m}$ thick copper top plate and an intermediate electroplated tin layer. The vacuum-holding capability of the OHP is validated under both flat and bent conditions, demonstrating the structural integrity. Thermal performance tests in horizontal and vertical (gravity assisted with bottom heating) orientations demonstrate effective thermal resistance reduction compared to baseline uncharged copper channels. These results demonstrate significant progress toward bendable copper OHPs that could offer adaptable thermal solutions in next-generation compact electronic systems.

• Publication year

  2025

• Venue

  Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems

• Publication date

  2025-05-27

• Fields of study

  Not labeled

• Identifiers
  DOI 10.1109/ITherm55376.2025.11235810
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar

• No claims are published for this paper.

• No concepts are published for this paper.

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