Fortify, a company that develops groundbreaking technology by redefining what’s possible in manufacturing, has partnered with Averatek to study, characterize and evaluate the insertion loss of 3D printed metallized microcircuits using Rogers' low-loss dielectric material with varied surface roughness profiles. Fortify has partnered with Averatek to explore metallized parts and has performed several studies on the metallization of Radix material with very good results. The company has conducted an experiment to determine the impact of insertion loss of the available stock surface roughness that could occur on different faces of a device.
Fortify uses its Flux Core, a 3D print solution that is inevitably the most capable on the market to print Roger’s low-loss resin with high print resolution. Roger’s RF material is a loaded photo-curable polymer and has a tendency of the filler material to settle in the liquid resin.
The company used a default build plate and selected 8 print orientations that would produce unique roughness profiles on the signal side of a microstrip device. For each orientation, a 2” long structure and an 8” long structure were printed. These orientations included three varieties where the microstrip substrates were printed parallel to the build plate – signal side directly on the build plate, signal side directly on the reservoir film, and signal side directly on the film with ground side offset from the build plate by printed support structures.
The last variety was added to control the thickness variation of the substrate. Five additional varieties were printed with the signal side of the substrate perpendicular to the build plate. The angle of the device pairs was varied from horizontal along the build plate (0°) to a full vertical span from the build plate (90°) and three additional angles in between (30°, 40°, and 70°).
All samples were then characterized for surface roughness using Fortify’s Keyence One-Shot 3D VR laser profilometry system. Three areas along the surface of each device were measured and averaged. The average roughness for all the 8 styles of the device was then recorded before shipping them out for metallization.
Upon characterization of roughness, Averatek performed metallization of the circuits according to two artwork varieties based on some variation of nominal thickness due to print orientation. The two artworks ensured that a 50 +/- 2 ohm characteristic impedance was maintained across all devices.
All circuits were then characterized using an Intercontinental Microwave W7000 fixture that uses two built-in probes to contact the microstrip line and interfaces the device with a Keysight N5230 PNA-L network analyzer. All circuits were swept from 50 MHz to 20 GHz and S-parameters for all measurements were exported as .csv files in magnitude/phase format. In order to de-embed the effects of the fixture and launch points of the microstrip devices, the S21 insertion loss magnitude results of the 2” circuit for each orientation pair were subtracted from the S21 magnitude results of the 8” circuit of the same orientation. The resulting value was then divided by the remaining 6” of the device and plotted to show the insertion loss per inch over the frequency of each of the print orientations.
The results were derived with plotted results showing that for a reasonable, average dielectric thickness that the insertion loss per inch on Radix materials as printed on Fortify Flux Core printer does not change enough for high concern on orientation of parts and that all sides of a printed part can be utilized for metallization.
Click here to learn more about Fortify's Flux Core 3D printing solution.
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