Effects of Post-Processing Treatments on the Microwave Performance of Additively Manufactured Samples

Several flat metal samples, produced by selective laser melting (SLM), have under-gone a variety of post-processing treatments. Microwave surface resistance values at a nominal frequency of 7.5 GHz are used to form a comparison between treatments, whilst also performing a comparison with traditionally manufactured copper PCB and aluminium samples. Measured values are then used to create a 3D simulation of a C-Band waveguide filter, utilising measurements from both horizontally and vertically built samples. Overall performance (quantified via low measured surface resistance) was found to be best in the traditionally manufactured copper samples. However silver plating was found to reduce the surface resistance of some SLM samples close to the values of bulk silver and copper.