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46 The PCB Magazine • November 2014 radic discoloration on the surface treated with an OSP process. When the surface was ana- lyzed, the data showed that film thickness was non-uniform and there were areas on the surface where the film thickness was less than 0.20 microns. That, of course, is unac- ceptable. The Role of the OSP Film Molecular Structure The functional groups that are part of the molecular structure of the imidazole molecule play a key role in the organic films ability to minimize oxygen penetration to the base cop- per. In addition to the amine groups in the azole molecule bonding with the copper of the base metal, next generation OSP technol- ogy shows increased cross-linking of other functional groups on the OSP molecule. This allows for a much tighter film that in turn fur- ther acts as a barrier against oxygen and hu- midity (Figure 4). Summary While next-generation OSP as a final finish has become the standard for lead-free compat- ible assembly, one should assume that any new OSP meets the criteria. A number of simple pro- cedures may be followed to qualify any new OSP and ensure it is compatible with these higher assembly temperatures. PCB LEAD-FREE COMPATIBLE OSPS: WHAT DOES THIS REALLy MEAN? continues michael Carano is with omG electronic Chemicals, a devel- oper and provider of processes and materials for the electron- ics industry supply chain. to read past columns, or to con- tact the author, click here. figure 4: Conventional imidazole (left) and improved imidazole (right). the national institutes of health (nih) awarded lawrence livermore national laboratory a grant to develop an electrode array system that will enable researchers to better understand how the brain works through unprecedented resolution and scale. lawrence livermore is developing a neu- ral measurement and manipulation system—an advanced electronics system to monitor and modulate neurons—that will be packed with more than 1,000 tiny electrodes embedded in different areas of the brain to record and stimu- late neural circuitry. the goal is to develop a system that will allow scientists to simultane- ously study how thousands of neuronal cells in various brain regions work together during complex tasks such as decision making and learning. Electrode Array System to Monitor Brain Activity