This letter details the metallization process of 3-D-printed WR-28 and WR-10 waveguides using electroplating. The 3-D printing technique is stereolithography, so the printed parts are plastic-based. A two-step metallization process is followed: a premetallization with nickel spray to make the part conductive and a subsequent electroplating process, emphasizing the chemical compounds and quantities needed to improve the result obtained, as well as the metallization times and currents applied on the parts. In addition, manufacturing deviations are measured and compensated. The results obtained are compared with simulations and commercial waveguide sections. Measurements show $S_{11}$ below −33 and −21 dB for WR-28 and WR-10, respectively. Measured average losses are around 1 dB/m for WR-28 and 4 dB/m for WR-10, which is equivalent to copper with an effective surface roughness lower than $0.4~\mu \text{m}$ .

中文翻译：

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适用于毫米波设备的精确内部电镀和 3D 打印工艺指南

这封信详细介绍了使用电镀的 3D 打印 WR-28 和 WR-10 波导的金属化过程。3-D 打印技术是立体光刻技术，因此打印的部件是基于塑料的。遵循两步金属化工艺：用镍喷涂进行预金属化以使零件导电，然后进行电镀工艺，强调改善所获得结果所需的化合物和数量，以及金属化时间和施加在零件上的电流. 此外，测量和补偿制造偏差。获得的结果与模拟和商业波导部分进行了比较。测量显示 $S_{11}$WR-28 和 WR-10 分别低于 -33 和 -21 dB。WR-28 的测量平均损耗约为 1 dB/m，WR-10 的平均损耗约为 4 dB/m，这相当于铜的有效表面粗糙度低于 $0.4~\mu \text{m}$ .