High performance and reliable ultra-thin vapor chamber via an optimised second vacuuming and sealing process

Ultra-thin vapor chambers (UTVCs) have been widely used for cooling high-power electronics owing to their superior heat transfer properties. However, UTVCs, especially those with thicknesses below 0.4 mm, still face poor performance and unreliability problems. As a key processing technology, the second vacuuming and sealing process can significantly improve the heat transfer performance and reliability of UTVC; however, it has seldom been studied. In this study, a UTVC with a thickness of only 0.32 mm was developed, and an optimised second vacuuming and sealing process was proposed to obtain a high-performance and reliable UTVC. The UTVC, prepared via resistance welding sealing, demonstrates reliable performance, operating effectively at high temperatures (240 C) and internal pressures exceeding 3.3 MPa, without leakage. Optimising second vacuuming parameters effectively removes most non-condensable gas, thereby enhancing the heat transfer performance of UTVCs. UTVC proposed with the vacuuming time of 35 s, vacuuming temperature of 90 C, and gas collecting section length of 20 mm exhibits a thermal resistance of 1.701 W/C at a heat load of 3 W. This study benefits the design of a second vacuuming and sealing process for UTVC with thickness less than 0.4 mm, further promoting its industrial applications.