When should you choose a Pt SMD over a NTC SMD?

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 SMDNTC SMD
Most common choice in the process industry and especially for machine building. Suitable for protection from overcurrent and short circuitUsed 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

Our Heraeus 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.

Kamet Webshop

Orders can be placed directly via our webshop or by contacting a member of our team. Our in-house experts are also available for advice on choosing the correct type of SMD for your application.