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A common problem in depth pro®le measurement is the calibration of the depth scale. The new technique of sputter assisted electron probe microanalysis offers the possibility of calculating the composition as well as the depth scale solely from the acquired X-ray intensity data without further information, e.g. sputter rates. To achieve a depth resolution that is smaller than the depth of information of the electron probe, i.e. 0.1À1 mm, special deconvolution algorithms must be applied to the acquired data.To assess the capabilities of this new technique it was applied to a Ti/Al/Ti multilayer on Si under different measurement conditions. Quantitative depth pro®les were obtained by application of a deconvolution algorithm based on maximum entropy analysis. By comparison of these pro®les with AES depth pro®les and AFM roughness measurements, it was shown that the limiting factor to the achievable depth resolution is the occurrence of surface roughening induced by the sputtering process rather than the relatively large depth of information of the electron probe.We conclude that for certain applications sputterassisted EPMA can be regarded as a valid depth pro®ling technique with a depth resolution in the nm range.

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A high power LED platform for automotive front lighting is described. Based on small footprint ceramic LED packages customized designs can be realized in a highly flexible way. The diverse automotive applications have different requirements in terms of optical performance, i.e. assembly tolerance and package density, but also regarding the thermal performance of the boards, which are used as substrates for the LEDs. For a future design of a low beam function with a distributed multi cavity reflector concept the optical tolerances are evaluated which are required to form a beam which provides the sharp cut-off line needed to illuminate the road without glaring the oncoming traffic. For such optical concept an overall positioning tolerance below 100µm is required. The tolerances of the LED assembly process on advanced PCB solutions, including reflow soldering, are investigated and compared with alternative assembly solutions. Additionally, the thermal performance of the LED subassemblies is investigated by T3Ster measurements and finite element simulations. The advantage of special Cu-IMS is demonstrated compared to Fr4 based and Al-IMS solutions.