Engineering question
What approximate sheet resistance is implied by this measured rectangular test pattern?
Equation and assumptions
Squares N = L/W. Sheet resistance Rs = R/N = R × W/L. Length and width may use any common unit because their ratio is dimensionless; measured resistance is entered in ohms and the result is ohms per square.
- Uniform film thickness and material
- Rectangular active region
- Length measured between the effective contact boundaries
- Contacts span the width and contact/lead resistance is negligible or corrected
- Measurement conditions and temperature are recorded
Published test vectors
| Resistance | Length | Width | Expected squares | Expected sheet resistance |
|---|---|---|---|---|
| 100 Ω | 20 mm | 10 mm | 2 | 50 Ω/□ |
| 250 Ω | 10 mm | 10 mm | 1 | 250 Ω/□ |
| 80 Ω | 5 mm | 10 mm | 0.5 | 160 Ω/□ |
Carry the result into a real review
- Material/paste identity and lot
- Substrate and surface condition
- Printed, dried and fired/cured process state
- Active geometry and contact construction
- Instrument, connection, temperature and measurement direction
- Repeat locations, variation and acceptance rule