As mobile phones become compact and thin, the demand for waterproof phones is growing. However, the assembly of waterproof mobile phones requires stricter tolerances then those of non-waterproof devices. Also, waterproof construction requires additional parts, so the assembly of waterproof devices involves more process, which increases the probability of waterproofing malfunction due to assembly defects. Therefore, ensuring that uniform pressure is applied by the assembly jigs during the assembly of waterproof devices is an important issue.