What is 3DVC/3D vapor chamber? What is the structure of 3DVC?

Comparison of Structures of Heat Pipes, VC and 3DVC

For phase-change heat transfer elements, what we are familiar with are heat pipes and heat spreaders. From a structural perspective, a heat pipe is one-dimensional heat conduction, while a heat spreader is two-dimensional heat conduction. The "3D" in 3DVC can actually be understood from two angles.

1> The path of heat conduction is three-dimensional, not on a plane;

2> The path of heat conduction is simultaneous in three dimensions.

Structural Characteristics of 3DVC and Typical Product Applications

Considering the application scenarios of 3DVC, apart from meeting the heat transfer paths in three dimensions, another application is to solve the problem of rapid heat conduction for high-density heat sources. Therefore, the most commonly used 3DVC structure nowadays is the combination of flat VC and heat pipes.One notable feature of this 3DVC is that the VC body and the internal cavity of the heat pipe are connected, and the capillary structure is also connected. Unlike the structure where the heat pipe is welded onto the VC, because the cavities are connected, the vapor can directly enter the interior of the heat pipe to achieve heat transfer. Compared to VC + heat pipe welding, the heat transfer efficiency will be higher.

The application advantages of 3DVC:

The heat spreader itself is a rapid heat-conducting component. Before the emergence of 3DVC, heat was mainly transferred from the BASE to each heat sink plate through heat pipes. Between the BASE (which could be copper plate, aluminum plate or thermal spreader) and the heat pipe, there still existed contact thermal resistance and the thermal resistance of the copper material itself. Without introducing external moving parts to enhance heat dissipation, 3DVC directly and efficiently transfers the chip heat to the far end of the teeth through the three-dimensional structure's heat diffusion and the principle of phase change heat transfer. It has advantages such as "efficient heat dissipation, uniform temperature distribution, and reduction of hot spots", which can meet the bottleneck requirements of large power devices for heat dissipation and uniform temperature distribution in high heat flux density areas. Currently, AI servers are one of the most popular markets for 3DVC. In recent years, with the popularity of big data models and AI applications such as ChatGPT, the demand for AI servers has soared. According to market research firm TrendForce's prediction, from 2022 to 2026, the shipment of AI servers will increase at a compound annual growth rate of 10.8%, and in 2023, AI servers will grow by 38%, reaching 1.2 million units. The demand for AI chip heat dissipation has become the largest potential market for 3DVC. NVIDIA's AI servers are equipped with at least 6 to 8 GPU chips. In addition to using the thermal spreader, high-end models also have 3D VC heat sinks.

The manufacturing process of 3DVC

The manufacturing process of 3DVC is quite complex and has a low yield rate, which indeed significantly limits its development and application. The core of 3DVC manufacturing lies in the connection method between the heat pipe and the VC housing, as well as the sintering of the internal capillary structure. Currently, a typical process is that the copper tube is connected to the uniform temperature plate housing (the stamped upper cover) through solder (atmospheric furnace protection welding or high-frequency heating welding), then the capillary structure is sintered, and finally it is diffused welded with the VC lower cover to form the final product.

• Written by

  CoolingThermal Engineering Team

  CoolingThermal is an automation equipment manufacturer based in Kunshan, China, specializing in heat pipe and vapor chamber production equipment since 2017. Our engineering team designs, builds, and commissions complete production lines covering forming, degassing, welding, testing, and assembly processes. The technical content on this blog is written by the same team that develops the equipment — based on real production experience, not secondary research.