PEEK (poly ether ether ketone) materials printed using FFF 3D printing have been actively studied on applying electronic devices in satellites owing to their excellent light weight and thermal resistance. However, the PEEK FFF process generated cavities inside due to large shrinkage has degraded both mechanical integrity and printing reliability. Here, we have investigated the correlations between nozzle temperatures and PEEK printing behaviors such as the reliability of printed line width and surface roughness. As the temperature increased from 360 to 380 °C, the width of the printed line showed a tendency to decrease. However, the width of PEEK printed lines re-increased from 350 to 426 μm at the nozzle temperatures between 380 and 400 °C, associated with solid to liquid-like phase transition and printed out distorted and disconnected lines. The surface roughness of PEEK objects increased from 49 to 55 μm as the nozzle temperature increased from 380 to 400 °C, where PEEK is melted down and quickly solidified based on more energy and additional heating time at higher printing temperatures at 400 °C. Based on these printing trends, a reliability analysis of the printed line was performed. The printed line formed the most uniform width at 380 °C and had a highest Weibull coefficient of 28.6 using the reliability analysis technique called Weibull modulus.

PEKK (polyether-ketone-ketone) polymer has been actively studied in applying electronic devices in satellites owing to its excellent light weight and thermal resistance. However, the limitation of metal coating to form on the PEKK surface is due to the high-volume resistivity and surface resistance. Here, we have investigated the correlations between the chemical treatment of the surface and adhesion strength between polymer–metal coating. Three-dimensional printed PEKK objects were manufactured and nickel was deposited on the surface by electroless plating. As the concentration of H₂SO₄ increased from 12.5 to 14.3 mol/L, the pore diameter showed a tendency to increase. However, as growing pore induced connecting each other, the pore size re-decreased from 15.1 to 18.0 mol/L. To control pore size and uniformity, we investigated the pore diameter of 3D printed PEKK as a function of treatment time and temperature. Uniform pores were observed at a temperature of 50 °C which were formed after 10 min and the average pore size was 0.28 μm. After H₂SO₄ swelling, samples were re-treated in the KMnO₄-H₃PO₄ etching system for the hydrophilic group. KMnO₄ broken C=C bonding and generated hydrophilic groups such as -COOH and -OH, the contact angle decreased from 64.7 to 51.1° compared with H₂SO₄ swelling. XPS survey spectra confirmed that not only breaking C=C bonding but also increasing hydrophilicity due to -OH, -C-, -SO3 and the catalyst absorption of Pd was improved. As a result of adhesive strength by ASTM D3359, compared with the H₂SO₄ swelling, the KMnO₄-H₃PO₄ etching system showed 5B which is the best result in standard test methods by adhesive tape test and peeling amount on the tape was less than 0.01%.