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While the precision CNC milling method is widely used to fabricate relatively large sized folded waveguides (FWGs), especially W-band FWGs, UV-LIGA is considered capable of fabricating small dimensional FWGs, such as those at 220 GHz or above. In this work, an attempt has been made to produce W-band FWG circuits by using UV-LIGA for the TWT. The designed FWGs feature a wide side of 1.9 mm, and narrow side 0.3 mm. The UV-LIGA technique was used to fabricate the halves of waveguides with the height of 0.95 mm. The copper FWG halves were then bonded to form completed FWGs, with dimensional accuracy of ±2 μm and + 10 μm for the height and width, respectively. According to CST calculation results, the dimension error has no obvious effect on the S 12 -parameters in the range of the operating bandwidth. [Display omitted] [ABSTRACT FROM AUTHOR]

This letter presents the fabrication of 340-GHz copper folded waveguides (FWGs) using the UV-LIGA method. During the process, KMPR photoresist was employed instead of SU-8 due to its easy removability after electroforming. KMPR patterns with a sidewall height of 300 \mu\m and a trench width of 100 \mu\m were achieved repeatedly under one single-spin deposition and optimized processing conditions, such as UV exposure dose and KMPR bake temperature and time. The dimensional accuracies of the wide side (500 \mu\m) and narrow side (100 \mu\m) of the copper FWGs were found to be \leqslant \6 and \leqslant \2\ \mu\m, respectively, and the sidewall surface roughness was about 44 nm, with a profile of about 90^\circ. [ABSTRACT FROM PUBLISHER]

W70Cu30(W-30 wt.% Cu) alloys were fabricated using cold pressing and infiltration sintering methods from two types of powders, i.e., mixed copper-tungsten (M-Cu-W) powders and our newly developed copper-coated tungsten composite (Cu@W) powders. Microstructure, mechanical and arc-ablation properties of the W70Cu30 alloys were investigated, and the mechanism of enhanced physical/mechanical properties and arc-erosion resistance of the W70Cu30 alloys was discussed. For the W70Cu30 alloys prepared using the Cu@W powders, their physical properties, including hardness, electrical conductivity and relative density were much better than those prepared from the M-Cu-W powders. The W70Cu30 alloys fabricated from the Cu@W powders were free of cracks, and showed homogenous distributions of W and Cu network structures. Whereas for the alloys prepared from the M-Cu-W powders, segregation of Cu was observed and the segregation size was about 40–100 μm. Characterization of arc-erosion morphologies of the W70Cu30 alloys prepared with the Cu@W powders revealed the occurrence of evaporation of Cu phase; whereas that of W70Cu30 alloys prepared with the M-Cu-W powders revealed the occurrence of the sputtering of Cu. After arc breakdown for 200 times, mass loss of alloys made using the mixed powders was twice as much as those made using the coated composite powders. Based on the experimental results and theoretical analysis, an arc breakdown mechanism of the WCu-C alloys using the composite powders was proposed which is attributed to the formation of a homogeneous Cu-Cu network structure to uniformly disperse arc energy and dissipate the generated heat, thus prolonging the service life of the WCu alloy contacts. [ABSTRACT FROM AUTHOR]