Environmental Scanning Electron Microscopic Investigation on Interface Debonding of Thermal Cycled FR-4 Board

Environmental Scanning Electron Microscopic Investigation on Interface Debonding of Thermal Cycled FR-4 Board Junhui Li, R.S. Balasubramanyam and Michael Pecht CALCE Electronic Packaging Research Center University of Maryland College Park, Maryland 20742 Abstract

Interface debonding is a potential precipitator of insulation resistance breakdown in FR-4 printed wiring boards. In this paper, an experimental effort on thermal cycling effect on interface debonding using environmental scanning electronic microscope is discussed. Resinfiber interface debonding was observed in the area near plated through holes. Microcracks near plated through holes were also observed and studied. Temperature cycling, the mismatch of coefficients of thermal expansion between epoxy resin and glass fiber, and the geometry of the FR-4 board all play an important role in the interface degradation and debonding.