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56 DESIGN007 MAGAZINE I MAY 2018 tion between the resin and the PCB, which ultimately leads to delamination. Of course, after cleaning, any solvent or cleaning solution must be removed, and the PCB needs to be thoroughly dried prior to resin application. By paying attention to these basic design pointers, you are likely to achieve the levels of reliability and long service life that will ensure long and happy relationships with your cus- tomers! Over the coming months, I shall be looking at a wide range of issues concerning the correct choice and application of resins, so be sure to check out this column in future issues. DESIGN007 Alistair Little is the global business/technical director for the Resins Division of Electrolube. Fourier-transform infrared (FTIR) spectrometers are too large to be used in the field to detect compounds. Sev- eral attempts have been made to develop miniaturized FTIR spectrometers for integration into drones to monitor greenhouse gases remotely, for example, or for integra- tion into smartphones and other devices. However, cur- rent miniaturized devices are costly to produce and there- fore cannot be widely used. Scientists at the University of Campinas's Device Research Laboratory (LPD-UNICAMP) in Brazil, collabo- rating with colleagues at the University of California San Diego, have overcome these constraints by developing an FTIR spectrometer based on silicon photonics, the technology currently used to produce chips for comput - ers, smartphones and other electronic devices. Resulting from Mário César Mendes Machado de Sou- za's PhD research and a research internship abroad, supported by scholarships from FAPESP and supervised by Professor Newton Frateschi, the new spectrometer is described in an article published in Nature Communi - cations. According to Souza, FTIR spectroscopy identifies chem- icals using an infrared light source to measure absorption. A sample is exposed to different wavelengths of infrared light, and the spectrometer measures which wavelengths are absorbed. The computer takes these raw absorption data and conducts a mathematical process known as the Fourier transform to generate an absorbance pat- tern or spectrum, which is compared to a library of spectra for chemical com- pounds to find a match. Various projects have appeared in recent years to develop an FTIR spec- trometer based on integrated photon- ics, which uses light especially in the infrared spectrum, but progress had so far been scant owing to several techni- cal challenges, Souza explained. One of these challenges is the highly dispersive profile of silicon waveguides, meaning that each wavelength travels at a different speed in this material and hence has a different refractive index. The researchers now plan to engineer a device that is totally functional and integrated with photodetectors, light sources and optical fibers. Infrared Spectrometer on a Chip