Abstract
Keywords
Microelectronics, contamination control, pressure sensor, gas sensor, humidity sensor
Abstract
Automotive electronic systems could grow from an average of 22% of vehicle content today to as much as 40% by 2010. In fact, experts expect that sensor use in typical vehicles will increase 20-25% annually, with economy cars having roughly 75 to 80 sensors by 2005 and certain luxury models having as many as 120 or more.
At the same time, electronic component failures make up nearly half the warranty costs paid by some automakers. Currently, automotive warranty spending worldwide amounts to roughly $22-$25 billion Euros annually, and this amount is growing at a 19% annual rate. Because a sizable number of these failures could very well be due to sensor and microelectronic contamination, it is critical that designers use all tools available to protect microelectronics appropriately.
A number of automotive microelectronics require exposure to harsh environments, and contamination from automotive fluids, water or particulate matter in the ambient air can lead to calibration drift and component failure particularly with gas, humidity and pressure sensors. In these types of situations, expanded polytetrafluoroethylene (ePTFE) membrane has proven itself as a viable contamination control solution.
Expanded PTFE permits air to flow freely to sensitive microelectronic components, yet it selectively filters out solid-, liquid- and gas-phase contaminants down to the submicron level. It is robust, chemically inert, and gas permeable, yet hydrophobic and available with various oleophobic treatments. Expanded PTFE high performance laminates provide low pressure drop, high air flow and high efficiency, making ePTFE an excellent choice for numerous microelectronic applications.
Once an optimal ePTFE membrane has been selected for a specific application, it is also important to consider how the media should be integrated with the sensor package. At times, it may be easiest and most cost-effective to attach the filter to the sensor module by means of pressure-sensitive adhesive. In other instances, however, thermal bonding, insert moulding or some other mechanical means may be the most optimal integration method. Careful and early consideration of various media packaging options during the preliminary design phase can save significant amounts of time and money.
One of the many challenges facing automotive sensor designers is to find the optimal combination of response time, accuracy, and protection from contamination - at the lowest possible cost. Deployed as part of a designer engineers arsenal of potential contamination control solutions, ePTFE is useful not only with gas, pressure and humidity sensors, but also with headlamp assemblies, anti-lock brake systems, pressure switches, power window and other types of electric motors, fuel system components, horns and wheel hub vents.