SWB Wideband RF Transformers Coilcraft SWB Wideband RF Transformers are available in both surface-mount and through-hole versions. The transformers feature 500Vrms, one-minute interwinding isolation, and a 250mA maximum current rating. The SWB components are resistant to soldering heat and have an ambient temperature range of -40°C to +85°C with a maximum temperature of +85°C (ambient + temperature rise). Coilcraft SWB Wideband RF Transformers are made with a ferrite core material and RoHS-compliant matte tin over nickel over phosphorus bronze terminations.