High-voltage resistors go lead-free

November 16, 2018 // By Julien Happich
Toxic lead was banned from most electronic products in 2006 but for now, component manufacturers are still allowed to have lead oxide in the glass within thick-film materials. RoHS (Restriction of Hazardous Substances) allows certain exemptions which are continually reviewed and only extended if industry successfully makes the case that alternatives are not yet viable.

The ban on lead in metallic form has eliminated it from most solders and solder finishes. This addressed the problem of lead leaching into groundwater from electronic waste in landfill. Lead compounds like lead oxide in glass within thick-film materials are less toxic but is not totally safe.

Working with its material suppliers and following an 18-month development program, TT Electronics has developed high-performing, green thick-film chip resistors, free of lead (Pb) and lead compounds.  This new development is not only safer for the environment, it also allows manufacturers to future-proof medical and industrial equipment designs by eliminating reliance on RoHS exemptions.

The series comprises E24 and E96 resistance values from 25kΩ to 100MΩ, in standard EIA 1206, 2010, and 2512 chips with power rating of 0.3W, 0.5W and 1.0W respectively. Specified with DC- or AC-peak Limiting Element Voltage (LEV) up to 3000V for 2512 chips, and up to 4000V overload, the GHVC series simplifies design for high working voltages saving board space and bill of materials.

The resistors are extremely rugged, with 1.2/50μs surge-voltage rating of 7kV and ambient operating temperature range of -55°C to 125°C. Temperature coefficient of ±100ppm/°C and voltage coefficient of -1.5ppm/V ensure consistent parameters over wide-ranging conditions. In addition, the resistors feature anti-sulphur terminations that pass ASTM-B-809 tests to ensure reliability and stability in sulphurous environments such as mining or chemical processing.

TT Electronics - www.ttelectronics.com


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