Frequently Asked Questions (FAQ)

In this section we attempt to answer the most common customer questions.

How is the sensor mounted/soldered onto a PCB?

The sensor can be surface mounted manually or by standard pick-and-place machines.

The use of underfill is not necessary, but this enhances the mechanical robustness of the system and improves the link to the thermal mass (the PCB carrier in our Development Kit). JonDeTech design rules should be carefully read prior to applying underfill.

The use of RoHS compliant soldering technique can be used. (The sensors can withstand more than 240C for several minutes). With respect to soldering, the sensor is very similar to a flex-PCB chip.

How are IR-filters applied/mounted?

Plastic IR filters can be easily be applied by using a double adhesive tape frame that is attached to the PCB around the sensor. It is also possible to dispense an adhesive agent in lines around the sensor. Silicon and other ceramic filters can be attached in the same way.

How is the sensor encapsulated?

The sensor requires no special encapsulation since it is robust enough to allow pressure and physical contact. It is therefore possible to use the JonDeTech IR-sensors for touch buttons or for input device applications.

Encapsulation to remove thermal noise (e.g. noise from air movement) might be necessary depending on the application. Filters could be used to reduce this noise (read above FAQ). It is of course possible to encapsulate the sensor in an arbitrary metal/plastic container or use a protective housing if required.

The sensor component is typically delivered to the customer without any encapsulation in a standard chip tray.

How "sensitive" are the sensors?

As a rule of thumb: without any optics or filters the sensitivity/response is enough to detect the presence of a human person (~5C above ambient temperature) at 1-1.5 meters, a hand/arm at 0.5 meters and a finger at 5-10 cm. If optics and filters are used, the distance to object can be much larger. The signal will be very clear for objects with higher temperature (40-50C) in the field of view at these distances.

What is field of view?

The theoretical field of view is 180 deg, but the practical response to thermal objects follows geometrical laws based on a square flat detector and the space angle to the object. Hence the sensor signal will be higher for an object at a normal direction from sensor plane compared to an object at oblique angle.

The field of view can be reduced by mounting an aperture above/around the sensor.