Recently, with the development of the IT industry, technology for satellite communication network systems using multichannel, high-capacity data is getting increasingly popular. Especially in the field of defense, experts emphasize the necessity for research and development (R&D) to improve communication quality in order to facilitate Network-Centric Warfare (NCW) and increase mission efficiency through the use of satellite communication network systems. High power is required for the implementation of this technology, and its quality is greatly affected by Passive InterModulation Distortion (PIMD). In order to improve PIMD levels, the leakage characteristics of the system were analyzed with knowledge of the strong influence of the state of the flange joint that has been confirmed by years of experience and previous studies. In this paper, we analyzed various problems from the mechanical point of view in order to improve the radio frequency (RF) performance by minimizing PIMD in the X band, which is used for the satellite communication. Based on our findings, we propose the flange shape to achieve the test result of -150 dBm, which is an improvement from the existing PIM performance and reference level.