Up to one-hundred sensors may be used in a single vehicle, helping to perform a variety of functions, including safety checks, engine steering and convenience. The sensor market will even continue to grow as automobiles become more and more automated and ‘drive’ themselves.
Many sensors have components that are fixed with adhesives and are protected with encapsulants and potting compounds. Chemical, thermal and mechanical requirements are extremely demanding in vehicles, so adhesives must work reliably and efficiently for extended periods of time in harsh environments – like the engine compartment.
DELO, one of the world’s leading manufacturers of industrial adhesives for automotive, consumer and industrial electronics applications provides some tips on which type of adhesive is most appropriate for different types of sensors.
Safe Parking Made Easy
When it comes to parking distance sensors, it is important that the adhesive used has good mechanical functionality and good acoustic characteristics, like the right oscillation behavior, so that a high-quality ultrasonic signal can be transmitted unadulterated.
By putting adhesives through a salt spray test, engineers can determine which products are suitable and which are non-suitable for this specific application. It is also important to note that due to the sensor’s position in bumpers the adhesives’ need an operating temperature range of -40 °C to +85 °C to function properly.
The light-curing epoxy resins DELO KATIOBOND not only fulfill these demands, they also allow for short cycle times in series production. As customer demand increases for park distance control sensors in their vehicles, production processes will need to speed up.
Finding the Right Balance
Hall sensors are always applicable when position or speed need to be captured. These sensors are sometimes located directly on the wheel rim, or even on the wheel hub. In these cases, dual-curing (light-/anaerobic-curing) DELO DUALBOND adhesives are especially appropriate because they assure a rapid pre-fixation and secure final curing of the magnet, the magnet holder and the hall die, even in shadowed areas. The adhesives are also highly resistant to media impacts like oil, gas, or even braking fluid, and also pass salt spray tests, reflow tests according to the semiconductor standardization body (JEDEC), vibration tests, and drop tests with flying colors.
Just the Right Mix
Mass air-flow sensors, MAF sensors for short, help reduce emissions and are located in the engine compartment, or more precisely in the air intake system. MAF sensors have the primary task of communicating the incoming air mass to the engine control unit.
In order to protect sensors, extremely reliable DELO DUOPOX epoxy resins with special hardeners are used that pass all the typical automotive tests. They are resistant to oil, gas, and braking fluid and can survive in a temperature range of -40 °C to +155 °C. Even when stored at these temperatures, the encapsulant on the sensor does not display any stress cracks. There is also no interaction between the transmission oil and encapsulant.
Just recently, DELO has released DELO-DUOPOX CR8031, a new potting compound that’s a promising alternative for applications in the engine compartment. This new, easy-to-handle two-component epoxy resin exhibits good adhesion to different plastics, including PA and ABS. It offers a compression shear strength of 20 MPa even on PE after plasma treatment.
With an elongation at tear of 5%, DELO-DUOPOX CR8031 is tough-hard and can withstand permanent temperatures up to 180°C. After 1000 hours of storage at this same temperature, and after 1000 hours at 85°C and 85% air humidity, the product’s mechanical properties remain the same.
With a decent resistance to oil and fuel, this new epoxy resin achieves reliability and flows easily without any fillers, allowing for no risk of filler sedimentation. No stirring or degassing of the potting compound is needed, resulting in a simpler system design.
DELO-DUOPOX CR8031 is a low-viscous product and is mixed in a 2:1 ratio. It can be used for fully automatic production, as well as semi-automatic processes in medium production volumes. The multi-purpose casting compound can be applied as if it is a one component adhesive through dispensing guns with static mixing tubes.
It is optimized for fast production and can be heat-cured within 10 minutes at 80°C. Without additional heating, functional strength is reached after 16 hours of curing at room temperature. This saves energy and minimizes stress on the component.
Summary
As shown by the examples, the ideal adhesive depends heavily on the thermal, mechanical, and chemical requirements of the sensor. There are even appropriate
adhesives, encapsulants and casting compounds for the high-reliability sector that enable durable functionality under the most severe environmental conditions.
https://www.delo-adhesives.com/us/applications/automotive-adhesive/?xtor=AD-41-[AD_Design_Solutions_US]
