Sensor system ensures optimal heat sink efficiency
26 October 2010
The novel Tactilus sensor technology from US-based Sensor Products is currently being used to help designers map and measure pressure distribution between heat sinks and components in real time, enabling design iterations to be made virtually 'on the fly'
The heat loads associated with state-of-the-art semiconductors in embedded applications demand heat sinks with substantial cooling capability. Designing effective heat sinks has always involved a certain amount of trial and error; even a slight warping of the heat exchange structure or reduction in surface contact area can have a profound effect on cooling efficacy. If the pressure distribution is not uniform, heat conduction will be low, and the electronics may overheat.
That uncertainty can now be relegated to the past, thanks to a new heat-sink analysis system developed by Sensor Products, and based on its novel Tactilus sensor technology, which is enabling researchers and designers to test and correct the surface contact and pressure distribution between the heat sink and semiconductor, rapidly and with high precision.
With Tactilus, engineers can visualise actual contact forces and pressure distribution data on the circuit board components. As the mounting screws between the CPU and the heat sink are tightened, the system maps and measures the changing pressure distribution between the mating surfaces and displays it on screen using special software developed by Sensor Products. The heat sink interface can be tested, manipulated, and repositioned in real-time, speeding the trial and error process and eliminating the need for additional assembly. Tactilus also provides the pressure data needed for FEA simulation predictions.
Unlike conventional transducers, a Tactilus sensor pad is flexible (it’s just 0.38mm thick), allowing it to be placed between the CPU and heat sink without affecting the assembly. The pad comprises 625 resistive sensing points arrayed on a 25 × 25 grid and giving a total sensing area marginally greater than 50 x 50mm. The scan speed is up to 1,000Hz, and the operating pressure range is 0 - 7kg/cm2.
The Windows-based software that is provided with this system performs a variety of useful tasks, including the creation of pressure versus time graphs and histograms; 2D, 3D and 360 degree image rendering and region of interest scaling; the display of maximum, minimum and average pressures plus force integration, and the preparation of reports via export to Excel or Access applications.
Sensor Products says its Tactilus sensor system will endure hundreds of diagnostic uses on different heat sinks with consistent repeatability. It offers high resistance to electromagnetic noise, and is tolerant of high temperatures and humidity fluctuations. The system provides an accuracy of ±10%, with repeatability at ±2%, hysteresis at ±5% and non-linearity at ±1.5%.
Heat sink performance is just one pressure-related application for Tactilus. The sensor system is particularly versatile and can be adapted to virtually any measurement modality or application that requires the mapping and measurement of surface pressure distribution in real time. For example, it is used to map and measure surface pressure distribution at the interface of tyre treads with their running surfaces, door seals, heat seals, fuel cells, printed circuit boards, flat panel displays and wafer polishing, among others.
The technology is available off-the-shelf or in custom designed packages for special applications, and the dynamic link library files and graphical user interface can be adapted according to customer requirements.
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