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PCB-Dec2017

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64 The PCB Magazine • December 2017 ing other processes and possibly even having panels processed outside the facility having an issue. For the first process check, the lamination and exposure parameters were scrutinized. Ta- ble 1 lists the variables along with the outcome of the process checks. With assistance from the photoresist sup- plier, the lamination and exposure parameters were reviewed. Only minor process issues re- quired any attention. As an example, there was concern as to the exposure intensity. That is, (Exposure Energy) x (Time of Exposure) = Exposure Intensity It was determined that, while overall expo- sure of the resist looked effective, there was an issue of perhaps too high an exposure intensity, which may allow for partial polymerization of the resist that is not intended to be exposed. As an adjustment was made to correct the increase in intensity, the team then processed panels through the developing process. Interestingly, the defects (mouse bites, pitting) remained. The team then decided to concentrate on the devel- oping portion of the imaging process and the pattern plating operation. This will be present- ed in a future column as Part 2. Summary It was important during this exercise to gather the team together and brainstorm over the multitude of possible causes for the pitting and mouse bite problem described herein. For Part 1, the possible process areas that could con- tribute to the defect were identified and a sys- tematic approach to finding the root cause was begun. PCB Michael Carano is VP of techn- ology and business development for RBP Chemical Technology. To reach Carano, or read past columns, click here. CASE STUDY: SOLVING PLATING PITS AND MOUSE BITE ISSUES, PART 1 NASA launched the Technology Education- al Satellite, or TechEdSat-6, to the International Space Station on Orbital ATK's Cygnus spacecraft from NASA's Wallops Flight Facility in Virginia on November 12. This bread loaf-sized satellite is part of a continuing series to demonstrate the "Exo- Brake" parachute device, advanced communica- tions and wireless sensor networks. TechEdSat-6 was released into low-Earth orbit from the NanoRacks platform on No- vember 20, to begin wire- less sensor experiments that will be the first self-powered tests, expanding the capa- bilities of sensor networks for future ascent or re-entry systems. This is the fourth TechEdSat satellite carrying an updated version of the Exo-Brake that will dem- onstrate guided controlled re-entry of small space- craft to safely return science experiments from space. "The Exo-Brake's shape can be changed to vary the drag on the satellite. With the help of high-fi- delity simulations, we will demonstrate a low-cost, propellant-less method of returning small payloads quickly, and to fairly precise locations, for retrieval," said Michelle Munk, NASA's Sys- tem Capability Lead for Entry, Descent and Landing. The Exo-Brake is funded by the Entry Systems Model- ing project within the Space Technology Mission Director- ate's Game Changing Devel- opment program. NASA to Test Advanced Device for Returning Small Spacecraft to Earth

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