SMT007 Magazine

SMT-Sept2015

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40 SMT Magazine • September 2015 markings, and provides the driver with a warn- ing if the vehicle veers over the line without in- dicating. The system interprets the absence of purposeful use of the indictors as a likely result of the driver losing concentration, or in its ex- treme form, falling asleep. The first generation of LDWS activated a significant vibration alert in the seat in order to alert the driver to immi- nent danger. The second generation took things closer to automatic intervention with a low- torque nudge of the steering wheel to put the vehicle back "on-course". The reliability of such a system is clearly more critical than the simple parking sensors, as the operation is designed to work at speed and prevent high-speed collision. An increasingly common feature in vehi- cles is cruise control. This has been available for decades and like many features which en- ter the market on luxury vehicles, has become standard for any vehicles intended for distance driving. The new generation of cruise control is emerging, and is known as "active cruise con- trol." This technology not only regulates the speed, but also maintains a minimum distance between the vehicle in front, automatically re- ducing the throttle, and in some cases activat- ing the brakes automatically, and then only returning to the set-speed when the distance to the vehicle in front allows. This radar based technology is integrated with the braking and throttle controls to achieve its function, and so its performance is absolutely critical to safety. The fourth and final area we will consider is the new generation of parking aids. Supple- menting the radar-based parking sensors is the integration of rear-view cameras with superim- posed guidance lines to help the driver with re- versing into a parking space. This passive park- ing technology is already being advanced with some active systems which will actually assess a parking space and automatically steer the vehi- cle into a parking space requiring the driver to only operate the throttle and the brake pedals. This technology uses a combination of radar and cameras to provide this advanced parking function. Design and manufacturing Constraints and Considerations So what does all of this mean? It means that a complex array of cameras and sensors are being integrated into the vehicle's periph- ery, which has two major challenges to the as- sembly process. The first challenge is that these units need to be small and discreet to meet both weight and design integration requirements, and the second is that that they need to be ro- bustly reliable. Automotive vision and detection systems typically utilise camera technology which has come straight from the mobile device market, which by definition is highly miniaturised. This is convenient for successful and discreet integra- tion into the vehicle, but also poses a challenge to meet the extended lifetime demanded by increasing vehicle warranty terms. To achieve these goals the assembler must consider the fol- lowing aspects of material and process selection. 1. Mechanical reliability 2. Electrochemical reliability 3. Process performance requirements Taking each of these factors in turn: 1. Mechanical reliability: There can be no universal mechanical reliability test for au- tomotive electronics as there is great variabil- ity in operating conditions from one electron- ic system to the next. For example, an engine control unit sees much harsher conditions than an in-car audio system. For vision and detec- tion systems, the solder joints need to be able to provide adequate strength and creep resis- tance to survive the temperature and vibration FeAture mAterIAL CONsIDerAtIONs FOr ADvANCeD DrIver AssIstANCe systems AssembLy continues

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