Forwarded from: Andy Brannen - Applications Engineer Rogers - Circuit Materials Unit Tel: (602) 917-5204 Fax: (602) 917-5256 E-Mail: [log in to unmask] ______________________________ Forward Header __________________________________ Subject: Re[2]: Dendritic Growth? Author: Andy Lloyd Brannen at Rogers-MCD Date: 10/9/95 8:31 AM The below paragraph leads me to wonder if the PWA had soldermask or coverlay on the top surface or was merely solder coated as many boards are. If it were merely solder coated, failure to meet minimum standoff values of Mil-Std-2000A would have resulted in insufficient flux cleaning beneath the chip and the resultant short. Flux, even RMA, if not properly removed after soldering, will act as a facilitator in developing the condition described (latent shorts). _ "Analysis of the PWA revealed a short had developed between two parallel traces underneath an IC. The traces are .006" wide and .010" apart. The short was not visible (even under a microscope). The short was approximately 2 1/2 ohms in value. Once a razor was run between the traces the short was eliminated and the PWA was functional once again."