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70 The PCB Magazine • September 2015 This chemistry requires tight process con- trol. Proper plating conditions and control over the entire process are critical to performance. Proper chemical add-backs and numerous chemical analyses are required during start up and plating. Layer thickness is also critical. Low nickel thickness will result in poor corrosion and thermal resistance in end use. Low gold thickness will result in less resistance to thermal conditioning during assembly and high gold thickness can promote nickel corrosion or black pad. Too much or not enough metal area in the plating bath will affect plating performance. ENEPIG—Electroless Nickel Electroless Palladium Immersion Gold: •Gold and aluminum wire bonding •Applications include medical and U.S. military •Excellent solderability •Mitigation of black pad •Gaining interest and acceptance in the market The primary caution at the assembly level is palladium thickness. Palladium that is too thick reduces the solderability performance. This will be slower to wet and have potentially palla- dium-rich areas in the solder joint. Palladium does not readily solubilize into the solder joint like silver or gold. Surface Finish Breakdown by Market Sector: •Automotive: Silver, OSP, immersion tin •Data/Telecom: silver, OSP, ENIG •High-end consumer: ENIG, silver, OSP •Low-end consumer: HASL, OSP •Aerospace, defense and high-performance electronics: HASL, immersion tin, ENIG, ENEPIG •Medical: ENIG, ENEPIG, silver Regardless of whether your application is automotive, medical or military, there are many factors to consider when selecting a final surface finish. Cost, lead or lead-free requirements, end environment, shelf life, fine-pitch components, RF applications, probe-ability, thermal resis- tance and shock and drop resistance, to name a few. There is not a one-size-fits-all finish. Un- derstanding the advantages and disadvantages of each surface finish allows the designer to se- lect the finish that best fits each particular ap- plication. PCB researchers at the universitat Jaume i in spain have developed materials based on graphene that can catalyse reactions for the conversion and storage of energy. the technol- ogy patented by the uJi combines graphene and organometallic com- pounds in a single material without altering the most interesting prop- erties of graphene, such as its elec- trical conductivity. the technology, developed by the group of organometallic chemistry and homogeneous catalysis (Qomcat) of the uJi, is of great in- terest to the energy industry and is part of the so-called "hydrogen economy." an alternative energetic model in which energy is stored as hy- drogen. in this regard, the materials patented by the uJi allow catalysing reactions for obtaining hydrogen from alcohols and may also serve as storage systems of this gas. the patented materials can be used both in the development of catalysts as well as storage batter- ies or other energy types. New Graphene-based Catalysts for the Energy Industry Tara Dunn is the president of omni PcB. she works with PcB designers and purchasing organi- zations to find the best fit solution based on volume, technology and lead-time requirements. click here to reach tara. FINAL SuRFACE FINISHES FOR AuTOMOTIVE: NO ONE-SIzE-FITS-ALL SOLuTION continues FlEx tAlk

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