It protects RF transmitters, sensors and circuitry from harsh environments, vibration, temperature extremes and water ingression
Finding a suitable vehicle parking spot in a parking lot is a troublesome task that drivers have to somehow contend with. They either go around in circles searching or have to wait for a spot to become empty. To address this issue, Electrolube has collaborated with a customer on a new car park sensor application in which sensor technology directs drivers to available parking spots, highlighting empty spaces on maps and offering directions to them. The smart car park not only helps in reducing pollution by eliminating the endless circling of the area by drivers (looking for an empty parking space) but also creates happier drivers too.
The challenge was to protect domed shaped sensors present in a car park floor with an appropriate resin solution. The sensors not only had to withstand cars driving over them and be resistant to temperature extremes and water ingress but also allow effective RF communication., whereby the signal can travel through the sensor as well as the resin.
It was found that the existing material in the car park floor was not tough enough to withstand the impact of cars driving over it. Additionally, the surface energy of the housing material was too low to allow a good wetting of the resin and subsequently evaded good adhesion, causing the unit material to bend. Despite a reasonable adhesion of the resin, delamination and water ingression was found inside the unit. The desired resin needed to be of low viscosity to fill all gaps in the small unit, show good adhesion to the material of the unit and provide protection at low temperatures during the winter and high temperatures during the summer.
Therefore, the UR5118 polyurethane resin was used to avoid RF interference and provide a dielectric constant of between 3-4 @50Hz. The UR5118 has a viscosity of 2300 @ 23°C and 860 @ 60°C, ensuring sufficient flow in small gaps. It has a wide temperature range -60 to +125 °C and a low exotherm (<35°C). With a shore hardness of A80, the UR5118 is gentle to more delicate components whilst providing good impact resistance. The reformed unit was tested with the new UR5118 resin and passed all tests.
Thanks to the capability to protect RF transmitters, sensors and circuitry from harsh environments, vibration, temperature extremes and water ingression, the UR5118 resin is proving to be a suitable resin for IoT applications. The IoT environment is ever-increasing for which it is important to safeguard the reliability and performance of interactive, connected devices.