Thick-Film Chip Resistors Combat Sulphide Growth

New from TT electronics Welwyn Components is a series of thick-film chip resistors designed to ward off the effects of sulphur-bearing fumes. Sulphide growth in ordinary resistors consumes silver or copper in the terminations and is most problematic in automotive, roadside, generating set and industrial applications - especially processes using sulphurous chemicals such as tyre manufacturing and wine production.

To combat this, the sulphur resisting ASC series offers standard sizes from 0402 to 2512, and values 1R0 to 10M?, all featuring special terminations that withstand sulphur-bearing gasses. The conductors, resistive element, glass inner protection and epoxy outer protection are applied to a 96% alumina substrate, and the chips are supplied with wrap-around terminations suitable for soldering. Terminations have an electro-plated nickel barrier and a RoHS-compliant 100 percent matt tin finish.

Sulphide growth resistance is demonstrated by testing in accordance with ASTM international standard B809-95(2008): Standard Test Method for Porosity in Metallic Coatings by Humid Sulfur Vapor (Flowers-of-Sulfur). Components in the new ASC thick-film chip resistor series are available now, and supplied on tape-and-reel for automated assembly.

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