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Manufacturing Wrong: Case Studies in Non Conformance. Dave Hillman Principal Materials and Process Engineer Rockwell Collins Cedar Rapids, IA USA ddhillma@rockwellcollins.com SMCBA 2013. Case Study 6 – Barney Boards. Case Study 6 – Barney Boards. The Setup:
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Manufacturing Wrong: Case Studies in Non Conformance Dave Hillman Principal Materials and Process Engineer Rockwell Collins Cedar Rapids, IA USA ddhillma@rockwellcollins.com SMCBA 2013
Case Study 6 – Barney Boards • The Setup: • High Performance product OEMs are somewhat obsessed with the cleaning of printed wiring boards • The root of the cleaning obsession has its source in Space and Military product historical material & process protocols • “you must use Rosin fluxes but you must clean within one work shift” • A clean printed wiring board is a happy printed wiring board!
Case Study 6 – Barney Boards • Root Cause: • Excessive Cleaning of Solder Joint Surfaces • Cleaning Solution Was Slightly Alkaline • The Printed Wiring Boards Were Cleaned 10 Times • The Solder Joints Were SnPb • The Sn Phase Was Preferentially Etched • The Pb Phase Dominated the Solder Joint Surfaces • Optically, the Solder Joints Had A Cosmetic Purple- Blueish Appearance • Touching the solder joints with a soldering iron made them bright and shiny