Anti-Sulfur Resistors

Various product type and wide size lineup
-Suitable for high reliable applications requiring long-term stability-

Application examples

Suitable to be used under the environment including sulfide gas or sulfur-contained substances

Mechanism of sulfuration

Sulfuration is a phenomenon that occurs in flat chip resistors (Typically thick film chip resistors) that use silver for internal electrodes.
When flat chip resistors are used in an atmosphere containing sulfur, sulfur entering through gaps between protective film and the external electrodes react with silver in internal electrodes to form silver sulfide, which have no conductivity and lead to a disconnection of resistors due to sulfuration.
KOA offers a series of complete anti sulfuration resistors with internal electrodes made from special materials that do not sulfide.

Sulfuration Test (Soaked in oil)

Comparison of disconnection speed by sulfuration

Even KOA's original severe test conditions "Soaked in industrial oil with sulfur substance 3.5% contained" for 5,000 hours, this product series is not affected but still indicates an extremely high sulfidation characteristics.

Product Lineup

General Catalog(12.7MB)

Features	Product Series	Resistance Range(Ω)	Power Rating(W)	Size mm (inch)	Tolerance (±%)	T.C.R.(×10^-6/K)
Anti Sulfuration (General)	RK73B-RT	1 to 10M	0.03 to 2	0402 to 6432 (01005 to 2512)	2, 5	0 to +300 ±200 to ±300
Anti Sulfuration(Precision)	RK73H-RT	1 to 10M	0.03 to 2	0402 to 6432 (01005 to 2512)	0.5, 1	±100 to ±300
Anti Sulfuration(Jumper)	RK73Z-RT	50m max. (100m: 1H)	-	0603 to 6432 (0201 to 2512)	-	-
Anti Sulfuration(Ultra Precision)	RK73G-RT	30 to 1M	0.1 to 0.25	1005 to 3216 (0402 to 1206)	0.25, 0.5, 1	±50
Anti sulfur (Ultra precision, High reliability)	RS73-RT	10 to 10M	0.125 to 0.33	1005 to 3216 (0402 to 1206)	0.1, 0.25, 0.5, 1	±25, ±50
Anti Sulfuration (Wide terminal)	WK73-RT	0.2 to 1M	0.75 to 4	1220 to 3264 (0508 to 1225)	1, 5	±100 to ±200
Anti Sulfuration (High Voltage)	HV73-RT	10k to 51M	0.1 to 1	1608 to 6432 (0603 to 2512)	0.5, 1, 2, 5	±100 to ±200
Anti Sulfuration (High Voltage, For Automotive)	HV73V-RT	10k to 51M	0.1 to 0.33	1608 to 3216 (0603 to 1206)	0.5, 1, 2, 5	±100 to ±200
Anti Sulfuration (Anti-Surge・Anti-Pulse)	SG73-RT	1 to 1M	0.1 to 1	1608 to 6432 (0603 to 2512)	10, 20	±200 to ±400
Anti Sulfuration (Anti-Surge, Precision)	SG73S-RT	1 to 10M	0.125 to 1.5	1005 to 3225 (0402 to 1210)	0.5, 1, 2, 5	±100 to ±200
Anti Sulfuration (Anti-Pulse, Precision)	SG73P-RT	1 to 10M	0.125 to 1.5	1005 to 3225 (0402 to 1210)	0.5, 1, 2, 5	±100 to ±200
Anti Sulfuration (Heat resistance)	HSG73P-RT	1 to 10M	0.2 to 0.75	1005 to 3216 (0402 to 1206)	1, 5	±200
Anti Sulfuration (Low Resistance)	SR73-RT	100m to 10	0.166 to 0.66	1005 to 3225 (0402 to 1210)	1, 2, 5	±100～±300