During the Summer of 2023, I interned at Kelvin Thermal, creators of one of the thinnest and most flexible phase-change cooling solutions.
As a manufacturing engineering intern, I contributed to the production of ultra-thin vapor chambers for space applications. Over the 12-week internship, I gained hands-on experience with the design lifecycle, participating in nearly every stage of vapor chamber production.
The TGPs consist of a liquid and vapor substrate that undergo a series of production stages, including surface treatment and plasma processing, to prepare them for thermal bonding processes. Pictures of these stages are shown on the right.
Background
A Kelvin Thermal TGP (Thermal Ground Plane) is a thin vapor chamber, essentially a 2D flat heat pipe, fabricated using flexible printed circuit (FPC)-compatible processes. It offers several advantages:
Low Cost
Ultra-Thin (0.15-0.25 mm thick)
Extremely Light (0.05-0.15 g/cm²)
Flexible (Bending radius between 10-3 mm)
High Thermal Conductivity (Ranges from 4,000 to 25,000 W/mK)
Unprocessed Vapor and Liquid Substrates, Respectively
The vapor and liquid substrates are first bonded to their respective casings, then bonded to each other to form a vapor chamber. This chamber is filled with a heat-transfer liquid, such as water. The liquid substrate contains tiny 'pillars' that create effective flow channels within a specified range. As heat is transferred, the water evaporates and moves to the vapor substrate, carrying the heat away. The vapor then condenses back into water through a wicking structure, allowing the cycle to repeat.
My Contributions
I was involved in nearly all stages of TGP production, from general manufacturing to quality control and testing. My specific contributions included:
Developing a Manufacturing Assembly Line: I worked alongside a mentor to establish the assembly process.
Collaborating with Engineers: I worked with both manufacturing and R&D engineers to identify opportunities for process optimization and increased efficiency.
Quality Control Activities: I assisted with inspections, testing, and root cause analysis for non-conforming vapor chambers.
High-Volume Manufacturing: I successfully produced a high volume of vapor chambers each week, utilizing plasma processing and thermal cycling techniques.
Teamwork with Interns: I collaborated with a diverse group of interns with various backgrounds and skill sets.
The pictures on the left shows the post-bonding result of a liquid and vapor substrate on a casing. Quality control at this stage includes measuring bond lines with a caliper to ensure consistency across batches. This step also determines whether the bond lines are sufficient for further production or if they meet conformance standards. Additionally, pillar height in vapor chambers is measured post-pressing with a micrometer to ensure optimal flow.
Bonded Liquid and Vapor Substrate Casings
Liquid Substrate Bonded to Casing
Vapor Substrate Bonded to Casing
While there is much more I could share about this experience, many details are confidential. Overall, this internship allowed me to apply key manufacturing principles and translate my coursework into a practical setting. I had the opportunity to contribute to an important aerospace mission and collaborate with a talented group of interns and engineers.
I also developed a newfound appreciation for often-overlooked aspects of engineering, such as quality control, which I now recognize as a critical step in product development. This lesson has left a lasting impression on me.
I hope to return and contribute further to the company's mission, or to bring the skills I gained here to future opportunities.
