RTD versus NTC SMD sensors
There are two types of SMD’s (surface mount devices):
A platinum SMD (Pt100 or Pt1000) is a type of thin film RTD (resistance temperature detector). These have a positive temperature coefficient (PTC) meaning that the resistivity increases with an increase in temperature.
A NTC (negative temperature coefficient) SMD is a sensing element whose resistance decreases as temperature increases. Each SMD type has certain functions in common but also have unique attributes that can affect a customer’s choice.
| RTD SMD | NTC SMD |
|---|---|
| Most common choice in the process industry and especially for machine building. Suitable for protection from overcurrent and short circuit | Used for temperature measurement, control and compensation (eg signaling when a battery is fully charged). |
| Meets international standards. | Standardization for NTC elements is not possible as a result of material and specific production criteria. |
| Functions over a wider range of temperatures up to 200°C with thin film technology. | Very narrow temperature range:up to 125 °C. |
| Platinum is a more expensive material making the Pt SMD a more costly option. Thin film is reducing the price difference as less platinum is needed. | Cheaper and therefore more suited to applications where large volumes are required. |
| Better long term drift stability and is more accurate. | Has higher sensitivity and faster response time (however this is only the cae within a narrow temperature range). |
In conclusion, when choosing whether to use and NTC SMD or a RTD SMD element the following questions will ultimately determine your choice:
- What are the operating conditions and temperature?
- What is the required resistance (tolerance) at which temperature range?
- What temperature accuracy is needed at which temperature?
- What are the certification requirements?
- What quantity of SMD’s are required and what is the budget?
- Is a specific soldering technique required?
- For SMD;
- SMD; soft soldering
- SMD FC: soft soldering, bonding
- SMD 1206 sinterable: sintering, ultrasonic wire bonding
- For SMD;
Our Yageo Nexensos Pt100 and Pt1000 SMD sensors are available in tolerance class B and 2B and in both simplex and duplex executions. There are four different sizes with a temperature range of -50°C to +150°C and a temperature coefficient of 3850 ppm. Furthermore, we offer the SMD 1206 SC which can be sintered instead of soldered which increases the temperature range to 200°C.