Thermal management for radar sensors
Modern radar sensor units are no bigger than a smartphone. Heat dissipation and thermal protection are crucial for the long-term functionality of these sensitive components. Thermally conductive liquid gap fillers are designed for automatic dispensing in high-volume production. They provide excellent thermal and mechanical performance and place virtually no stress on components during assembly. Because gap fillers are liquids, they can be freely applied in practically any desired pattern or shape, allowing high flexibility in manufacturing and design.
However, thermally conductive pastes pose fundamental challenges to the dispensing technology used. On the one hand, there is the abrasiveness of the fillers, which must be processed without increasing wear on the components of the dispensing system. The use of more thermally conductive solid particles as well as different and usually ceramic fillers enables high thermal conductivities of up to 8 W/mK. As a result, thermally conductive pastes are becoming more and more abrasive. On the other hand, the low proportion of polymer matrix, which tends to separate from the filler portion of the formulation under high pressure and mechanical stress.
bdtronic has been using eccentric screw pumps successfully for the application of thermal interface materials for many decades. Compared to other pump systems, it offers significant advantages due to its robust and low-wear technology. The inner parts of the pump are specially designed for abrasive media. Thus, bdtronic offers various stator geometries made of different elastomers and rotors with special coatings such as ceramic or diamond-like carbon (DLC). In comparison to eccentric screw pumps, gear pumps quickly reach their wear limit with such highly filled materials. Piston metering pumps, on the other hand, often require complex and lengthy maintenance due to their complex design.
bdtronic?has been using high-abrasion resistant ceramic rotors for many years. Numerous tests in the field at customers were done to design rotor geometries and material combinations that result in the longest possible lifetime of the pumps, leading to maximum process reliability, cost reductions and savings in spare parts consumption. Depending on material and dispensing speed up to 6 times longer lifetime was achieved. Even for micro dispensing, where wear-and-tear will have a major impact on the dispensing accuracy, great results could be obtained. The requirement of a customer for dispensing at least 100,000 shots of a 1-component thermal interface material with a viscosity of 214,000 mPas, a density of 3.02 g/cm3 at a dispensing rate of 7.5 mg/s and a dispensing amount of 15 mg was exceeded with more than 2 times with 231,000 shots. The dispensing pump with the ceramic rotor is running in series production at this customer on more than 10 installations since 2017.
The machine solutions offered by bdtronic, which consist of a flexible combination of machine, material preparation and dispensing method, are tailored to the customer's requirements and the material properties. In addition, a comprehensive process monitoring ensures an optimal dispensing result. The product range covers manual workstations for single-part production, integration solutions, and fully automated production lines for high volume production of, for example, ADAS systems.
An optimal material preparation of such challenging, high viscosity to paste-like, highly filled and abrasive materials is solved with the PPS (Pail Preparation System). The PPS supplies thermal conductive materials from original pails at low operating pressures and is gentle on the material. It requires only a small amount of space and ensures minimum downtimes thanks to fast and uncomplicated container changes.
The various applications within ADAS systems are constantly increasing.?One of the applications is plasma pretreatment for surface activation prior to dispensing on radar/LiDAR and ADAS systems. This improves the adhesion of the dispensed adhesive. Another application is heat staking, which is used on radar / LiDAR and ADAS systems. Heat staking is a component-friendly joining technology for sensitive electronics. bdtronic provides various process solutions within ADAS systems. This offers the customer only advantages: because it all comes from a single source.
?“bdtronic offers various production technologies that are used for the mass production of ADAS systems and the next generation of e-mobility. Linking different process steps not only offers economic advantages, but also brings additional process stability for series production,” states Andy Jorissen, Chief Commercial Officer at bdtronic.