In this work 10-GHz-band RF measurement and microscopy characterizations were performed on thermally and mechanically long-term-stressed coplanar waveguides (CPW) to observe electrical and mechanical degradation in 1-mm-thick PPO/PPE polymer substrates with inkjet-printed Ag conductors. The structure contained two different CPW geometries in a total of 18 samples with 250/270μm line widths/gaps and 670/180μm line widths/gaps. A reliability test was carried out with three sets. In set #1 three 250μm and three 670μm lines were stored in room temperature conditions and used as a reference. In set #2 six samples were thermally cycled (TC) for 10,000cycles, and in set #3 six samples were thermally cycled and bent with 6mm and 8mm bending diameters.Thermal stressing was done by cycling the samples in a thermal cycling test chamber operating at 0/100°C with 15-minutes rise, fall, and dwell times, resulting in a one-hourcycle. The samples were analyzed during cycling breaks using a vector network analyzer (VNA). In addition to optical microscopy, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) imaging were used to mechanically characterize the structures.The results showed that the line width of 670μm had better signal performance and better long-term reliability than the line width of 250μm. In this study, the average limit for proper RF operation was 2500 thermal cycles with both line geometries. The wide CPW lines provided more stable characteristics than the narrow CPW lines for the whole 10,000-cycle duration of the test, combined with repeated bending with a maximum bending radius of 6mm. A phenomenon of nanoparticle silver protruding from cracks in the print of the bent samples was observed, as well as fracturing of the silver print in the CPW lines.