Hi Russ, While the PWB material between layers 5 & 6 may have a problem, this is not likely. The likely problem is the uncontrolled hand soldering operation. This operation is very dependent upon the operator, the PWB construction, and the type of component being soldered (heat sinking). I have heard of hand soldering operations performed with irons in excess of 410C! Depending of the polymer glass transition temperature, that might be a delta-T of 285C above Tg. The excessive compressive hoop stresses on the PTH barrel together with the land rotation of the lands near the surface produce loading conditions for which the materials ionvolved are not designed. If you like to get more in-depth background on this, I will be giving a workshop "Design, Manufacturing and Reliability Issues of Small-Diameter/High-Aspect-Ratio Plated-Through-Holes and Vias" the IPCWorks'97 on October 5. Werner Engelmaier Engelmaier Associates, Inc. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street Mendham, NJ 07945 USA Phone & Fax: 973-543-2747 E-mail: [log in to unmask]